Boosting Electrochemical Performance via Red Phosphorus-Manganese(III) Oxide Composite Electrodes for Supercapacitors  

Boosting Electrochemical Performance via Red Phosphorus-Manganese(III) Oxide Composite Electrodes for Supercapacitors | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Boosting Electrochemical Performance via Red Phosphorus-Manganese(III) Oxide Composite Electrodes for Supercapacitors Sowmiya Selvaraj, Anand Sreekantan Thampy This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9352351/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 8 You are reading this latest preprint version Abstract The development of high-performance electrode materials that simultaneously deliver high capacitance, high energy density, and long-term stability remains a key challenge in symmetric supercapacitor research. This study successfully produced a red phosphorus‒manganese(III) oxide (RP‒MO) composite electrode to address the intrinsic retarding factors for the application of manganese(III) oxide (MO), including low conductivity and poor rate capability. The electrochemical performance is enhanced by the simultaneous effects of pseudocapacitance from the metal oxide and the redox process. The RP-MO composite exhibited a specific capacitance of 317 F g − 1 at 5 A g − 1 , the highest energy density of 13 Wh kg − 1 , and a maximum power density of 2250 W kg − 1 , which is better than that of the MO and pretreated RP electrodes. The composite has a relatively high energy density at intermediate power density, indicating good charge transport with low kinetic hindrance. The RP-MO underwent cycling stability tests and retained 96% after 2000 consecutive charge/discharge tests. The coulombic efficiency is quite high (~ 90%), which indicates that the faradaic reactions are reversible and kinetically favourable. These results suggest that the RP-MO composites are potential energy storage candidates that exhibit capacitance fading, possibly due to the degradation of the MO. Red phosphorus Manganese oxide Supercapacitors Pseudocapacitance Electrochemical energy storage Charge transfer kinetics Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 1. Introduction The increasing need for energy storage systems is causing a buzz in the scientific community. Supercapacitors (SCs) are a good research and development (R&D) candidate because they provide a perfect trade-off between the functionalities of conventional capacitors and batteries [ 1 – 3 ]. Supercapacitors deliver high power and large current while charging and discharging. Moreover, they exhibit remarkable cycle life; these materials are well suited for portable and wearable electronics, hybrid electric vehicles, and grid stabilization [ 4 – 6 ]. However, despite these advantages, a defect persists: high energy density at the expense of power performance and long-term stability. The properties of electrode materials and charge-storage mechanisms can influence the performance of supercapacitors. Supercapacitor electrodes should ideally possess high conductivity and a substantial number of electrochemically active sites that enable fast diffusion and stability during prolonged cycling [ 7 , 8 ]. Most single-component materials do not meet these requirements. Manganese oxides (MnO) belong to a family of transition metal oxides. They are attracting much attention because of their high theoretical capacitance and low cost, as well as their eco-friendliness. Among these materials, manganese (III) oxide (MO) exhibits promising pseudocapacitance from the reversible redox reaction of Mn³⁺/Mn⁴⁺ in alkaline electrolytes. Nonetheless, MO has intrinsic problems such as low electrical conductivity and slow charge transfer kinetics, limiting its electrochemical performance in real-world applications, especially at a high rate of operation. Owing to these limitations, which restrict MO from reaching its theoretical capacity [ 9 – 11 ], the rate capability is poor, the internal resistance is high, and the cycling stability is low. To solve these problems, intensive work has been done to enhance the electrochemical behavior of manganese oxide-based electrodes. Nanostructuring, doping, and hybridization with conductive materials are different techniques. Nanostructuring increases the surface area and shortens the ion diffusion route, thus improving the electrochemical accessibility [ 12 ]. However, nanoscale materials often undergo aggregation and structural instability during cycling. The presence of heteroatoms in polyethylene can make it conductive, but at the same time, it can lead to defects. In recent research, composite approaches involving manganese oxides with conductive matrices (carbon materials such as graphene [ 11 , 13 – 15 ] and carbon nanotubes [ 16 – 20 ] or conducting polymers [ 21 – 25 ]) have shown promising potential. The aim of these composites is to achieve, through synergy, an increase in the electric double-layer capacitance (EDLC) to increase the pseudocapacitance. Carbon composite materials are synthesized via elaborate routes, which increase their production costs and limit their scalability. On the other hand, conducting polymers may be mechanically unstable and degrade after repeated cycling. Moreover, several studies have reported enhancements in capacitance or conductivity, often ignoring the intertwined issues of long-term stability and rate performance. This shows that although the synergy concept is well known, the application is not yet complete [ 26 ]. Red phosphorus (RP) has recently emerged as a new and interesting candidate for composite electrode development. Historically, RP has unique physicochemical properties, including a high theoretical capacity and the potential to form surface functional groups that can increase the electrochemical activity of batteries [ 27 , 28 ]. Pretreated red phosphorus (PTRP) desensitizes a sample, subsequently promoting conductivity and surface reactivity, and has the potential to be a matrix for redox-active materials. The RP is unlike carbon matrices that are used traditionally; it can contribute to conductance and capacitive behavior, thus offering double functionality. Nevertheless, the connection of RP with transition metal oxides, particularly MO, is underexplored. Research on phosphorus-based composites has focused mainly on lithium-ion or sodium-ion batteries, neglecting supercapacitor systems. Creating an ideal electric double-layer capacitor and pseudocapacitor system is challenging since the two mechanisms often operate against each other. To achieve this, the material composition, morphology, and interfacial properties need to be controlled, which remains a main focus of current research [ 29 ]. To resolve this problem, a red phosphorus‒manganese(III) oxide (RP‒MO) composite electrode has been developed. Next, the electrochemical performance was systematically investigated in an alkaline electrolyte. This work investigated PTRP as a multifunctional additive that improves the conductivity and capacitive behavior, unlike conventional systems with only carbon-based matrices. This research aims to overcome the limitations of MO by combining it with PTRP, which has specific properties arising from its RP content, and is analysed at different ratios. The author of the study also performed a detailed examination of performance metrics, such as the specific capacitance of the RP-MO composite, which was 317 F g-1 at a current density of 5 A g-1 with energy and power densities of 8.9 Wh kg-1 and 1125 W kg-1, respectively. The cycling stability and coulombic efficiency of the RP-MO composite are 96% and 90.26%, respectively, after 2000 cycles. In summary, although composite electrode design has been beneficial according to past research, there are gaps in the identification of other conductive matrices and their interactions with transition metal oxides. The goal of this work is to develop a new component of MO-based electrodes containing RP for the effective development of supercapacitor materials. These findings are expected to advance the field of energy storage by revealing novel composite mechanisms and guiding the design of next-generation electrode architectures. 2. Materials and methods 2.1. Materials 2.2. Synthesis of pretreated-RP (PTRP) The RPs were pretreated via the reflux method. In this process, 1 g of RP powder in 100 ml of water was stirred at 70°C for 12 hours in an oil bath under reflux. The RP powder was cooled to room temperature and washed with DI water and ethanol several times. The pretreated RP was dried at 60°C overnight. The powder was well ground with a mortar and pestle ( Fig. 1 a ) . 2.3. Synthesis of manganese(III) oxide (MO) Synthesis of manganese(III) oxide by coprecipitation and annealing. By this method, 1.5 g of MnCl 2 and 0.9 g of KMnO 4 were separately dissolved in 50 ml of water and stirred for 30 mins. The KMnO 4 solution was added dropwise to the MnCl 2 solution. The mixture was agitated at room temperature for 15–16 hours. The resulting black precipitate was thoroughly washed several times with deionized water and ethanol. The product was dried for 12 hours at 60°C. The powder was dried and heat-treated at 900°C for 6 hours. Afterward, the final product was crushed into a fine powder for composite synthesis. ( Fig. 1 a ) . 2.4. Synthesis of the RP‒MO Composite The RP‒MO composite was prepared via sonication. MO and PTRP (20 mg) were added to a beaker containing 20 ml of acetone. The mixture was sonicated for 1 hour and dried at 60°C for 12 hours. The RP-MO composite was ground well and stored for further analysis. In this way, the RP‒MO composite was prepared by varying the ratio of RP. 2.5. Preparation of the RP‒MO electrode The RP‒MO composite electrode was prepared alongside a polyvinyl pyrrolidone (PVDF) binder and activated carbon (AC) at a ratio of 8:1:1. A total of 100 µL of 1-methyl-2-pyrrolidone (NMP) was added to the mixture, which was subjected to ultrasonication for one hour. The resulting slurry is coated onto the cleaned nickel foam via a drop-casting method. Afterward, the nickel foam was dried at 60°C for 12 hours ( Fig. 1 b ). 2.6. Electrochemical and structural characterization X-ray diffraction patterns were obtained with a Bruker D8 Advance diffractometer with a PANalytical X’Pert3 CuKα radiation source in a 2θ range of 10–90°. An EVO 18 Research (CARL ZEISS) scanning electron microscope (SEM) was used to study the morphology and elemental mapping. The CHI 660C device is employed for electrochemical analysis, with a 1 M potassium hydroxide (KOH) solution utilized as the electrolyte. The electrodes consisted of a platinum wire for the counter electrode, Ag/AgCl for the reference electrode, and nickel foam coated with slurry as the working electrode. The CH instrument is employed for various electrochemical analyses, including specific capacitance at different current densities, Ragone plots, and impedance spectroscopy. 3. Results and Discussion 3.1. Study design The current research shows that, compared with the individual components, the RP-MO composite has enhanced electrochemical properties on nickel foam. This enhancement results from the synergistic combination of the EDLC and pseudocapacitance, according to structural and electrochemical characterization. On a theoretical level, these results are coherent with the principles employed in the design of hybrid SCs, i.e., faradaic and non-faradaic systems. MO is well known for its pseudocapacitance via reversible redox transitions of the Mn³+/Mn⁴+ states. RP enhances the electrical conductivity as well as the surface-driven capacitance. The improvement observed in the RP-MO composite is consistent with the theory of interfacial charge-storage enhancement, in which heterostructures provide more active sites and reduce the charge-transfer resistance [ 30 , 31 ]. Previous studies have highlighted the importance of tuning the composition of metal-based oxide composites, and hybrid materials are typically superior to component electrodes because of their complementary charge-storage processes [ 32 ]. Likewise, nanoscale engineering and compositional synergy prominently enhance the rate capability and capacitance of pseudocapacitive systems [ 2 ]. The current findings enhance our understanding of RP, a relatively unexplored material in supercapacitor electrodes, and its ability to modulate the electrochemical behavior of MO. Earlier studies on manganese oxides generally reported that they have performance limitations due to their poor electrical conductivity. However, this study revealed that RP incorporation satisfactorily alleviated this limitation. This difference might be due to improved contact at the interface and even spread, which occurred during synthesis, according to SEM mapping. Moreover, as nickel foam is a conductive substrate, it favours electron transmission and electrolyte access, enhancing the performance of the composite [ 33 ]. These factors underscore the importance of electrode architecture in conjunction with material composition. 3.2. Structural and morphological analysis As shown in Fig. 2 , commercial RP shows two broad peaks at 2θ ~ 15.50° and 34.1°, which can be assigned to the (102) and (232) crystal planes of red phosphorous, respectively (JCPDS No. 44–0906) [ 34 ]. Compared with that of commercial RP, the XRD pattern of PTRP exhibited a high-intensity peak at 2θ ~ 15.50°. Several peaks of MO are detected at 2θ values of 23.2°, 33.2°, 38.7°, 45.5°, 49.4°, 53.3°, 55.2°, 57.5°, 60.8°, 64.1°, 66.0°, and 67.8° (JCPDS No. 41-1442). XRD analysis of the two bare materials indicated the formation of a composite [ 35 ]. SEM analysis provided useful information on the morphological changes that commercial RP (Fig. 3 a) underwent to convert to PTRP (Fig. 3 b), bare MO (Fig. 3 c), and the RP-MO composite (Fig. 3 d) and provided a structural explanation of the electrochemical behavior in the investigated electrolytic media. According to the information presented in Fig. 3 a, commercial RP appears as agglomerates with irregular shapes, are bulky, and possess relatively smooth surfaces. They therefore likely have a low surface area and dispersion characteristics. As shown in Fig. 3 b, RP is visibly more fragmented and rougher after pretreatment. Through this structural modification, its surface reactivity and dispersion capacity are enhanced, which is vital for effective composites. In Fig. 3 c, bare MO has a relatively well-defined angular microstructure, indicating the formation of a crystalline oxide. However, the high packing density of particles with low surface irregularities may inhibit electrolyte penetration and decrease the effective electrochemically active surface area. This observation is not surprising because pristine manganese oxides often have poorly accessible ions despite being intrinsically pseudocapacitive [ 32 ]. In comparison, the morphology depicted in Fig. 3 d for the RP-MO composite varies significantly, indicating the presence of MO, with RP being decorated or partly embedded. The SEM images indicate the presence of a heterogeneous but well-connected network, with smaller RP particles dispersed on the MO surface. The EDX spectrum shown in Fig. 3 and the elemental mapping images in Fig. 4 further support the coexistence of the constituents. The sequential spatial overlap of Mn, O, and P is suggestive of composite formation without appreciable phase separation. The importance of homogeneous dispersion is to facilitate the formation of continuous electronic channels and favourable interfacial contact, which positively influences the electrochemical performance. These morphological observations strengthen the synergistic charge storage mechanism in hybrid SCs involving EDLC and faradaic reactions in terms of capacitance performance. The rough RP surface and its distribution over MO most likely enhance the density of electrochemically active sites and the electronic conductivity. The theory of interfacial charge transfer holds that increasing the area of contact between different phases promotes the transfer of electrons and ions. In addition, the composite structure may construct a percolation network, potentially improving electron transport within the electrode for better rate capability and cycling stability [ 36 ]. XRD analyses of these materials confirmed the existence of the crystalline phase of MO and the amorphous or semicrystalline phase of RP. This is followed by SEM imaging with elemental mapping, which further shows that the MO is relatively homogeneously distributed within the phosphorus matrix. 3.3. Electrochemical performance and synergistic effects The MO, PTRP, and RP-MO composite electrodes under alkaline conditions exhibit electrochemical behavior in a KOH electrolyte, which is used to understand the faradaic process and interfacial charge transfer. The hybrid electrode systems have a potential window of 0–0.45 V. Characterizing distinct charge storage mechanisms and kinetics through cyclic voltammetry (CV), galvanostatic charge–discharge (GCD), and electrochemical impedance spectroscopy (EIS) not only corroborates the theories but also indicates possible new enhancements due to the composite. The CV profiles of all three electrodes exhibit prominent redox features, indicating pseudocapacitive behavior due to faradaic reactions. The oxidation and reduction peaks are caused by the Mn³⁺/Mn⁴⁺ reversible process in alkaline solution, which is attributed to MO (Fig. 5 a) [ 37 ]. However, the ongoing behavior of monometallic MnO is rather broad and moderate, which indicates low electronic conductivity and slow ion diffusion. Both are well-established weaknesses of MOs due to their semiconducting characteristics. The shift in peak potential, related to the increase in scan rate, also indicated polarization effects, indicating that pristine oxide has a diffusion-limited character. In contrast, the electrochemical behavior of the PTRP electrode is different. As mentioned before, MO has a relatively wide peak shape and a moderate current response. The peak is not expected to have high electrical conductivity or fast ion diffusion. These problems of MOs are well known because of their semiconducting character. The electrochemical signature of the PTRP electrode is completely different. The RP is usually regarded as a weak pseudocapacitive material. The CV curve in Fig. 6 a is weak but denotes redox activity. This is attributed to oxidation and reduction at the surface level. This may also be due to the development of phosphorus-oxygen functionalities during pretreatment. This observation agrees with some studies reporting the electroactivity of different modified phosphorus-based materials [ 38 ]. The absence of distinct redox peaks and a low current density indicate that charge storage is limited by surface phenomena and has a limited faradaic contribution. Although having a reduced current density, the RP‒MO composite electrode is more pronounced. The CV curves (Fig. 7 a) retained their shape and exhibited sharper redox peaks. These improvements are indicative of a strong MO-matrix RP interaction. The combined configuration likely assists more effectively in electron transfer and enhances the number of active electrochemical sites. Such impacts have been widely observed in hybrid systems, which increase the utilization of redox-active materials through a conductive matrix. substances. [ 12 ]. The decreased peak separation of the composite electrode indicates improved reversible and rapid charge transfer kinetics, indicative of a faster faradaic process. A closer examination of the scan rate dependence further supports this interpretation. The redox characteristics of the RP-MO electrode are maintained even at a scan rate of 200 mV s⁻¹, which indicates that surface-controlled pseudocapacitance mainly governs its reaction kinetics. Pristine MO behaves differently, as the peak distortion increases with increasing scan rate. The better kinetics of the composite are attributed to the hierarchical morphology of the RP-MO composite. These trends are also confirmed by the GCD measurements. The MO electrode exhibited a nonlinear charge–discharge curve along with a short discharge time (Fig. 5 b ) , which indicates its lower capacitance and high internal resistance. It has a capacitance of 290 F g − 1 at 1 A g − 1 and 120 F g − 1 at 10 A g − 1 (Fig. 5 d ) . A significant IR drop further indicates that the material has a poor conduction property. The discharge properties of the PTRP electrode are somewhat improved (Fig. 6 b ) , likely due to its larger surface area and partial conductivity resulting from pretreatment. Figure 6 e shows that the specific capacitance of the PTRP is 193 F g − 1 at 1 A g − 1 and 121 F g − 1 at 10 A g − 1 . However, it still does not have much faradaic contribution. The RP-MO composite shows much improved GCD performance with a potential window of 0–0.45 V, which discharges for significantly longer times and results in a smaller decrease in the IR at all current densities, as shown in Fig. 7 b. The consistent shape of the coulombic efficiency alongside the quasi-symmetric charge‒discharge profile reveals excellent reversibility and efficiency of the redox process. More importantly, the composite continues to deliver a high capacitance even at high current densities, indicating its superior rate capability. It has a capacitance of 464 F g − 1 at 1 A g − 1 and 242 F g − 1 at 10 A g − 1, as shown in Fig. 7 d. This behavior matches previous works on phosphorus–metal oxide composites, in which a conductive scaffold was shown to reduce resistance loss and stabilize the electrochemical interface [ 39 ]. The enhanced GCD performance is attributed to the additional contribution from the phosphorus matrix and the pseudocapacitance of MO in terms of the mechanism. This charge storage mechanism aligns with theoretical models of composite electrodes in which the total capacitance is equal to the sum of contributions from surface adsorption and the faradaic redox process. However, the interaction between the two components appears to be more than additive, highlighting the importance of interfacial interactions between MO and PTRP [ 40 , 41 ]. Impedance spectroscopy (EIS) provides additional insight into the interfacial and transport properties of the respective electrodes. The Nyquist plots clearly differ among the three systems shown in Fig. 5 c, 6 c, and 7 c. The large semicircle of MO at high frequency indicates a large charge-transfer resistance (R ct ≈ 3–5 Ω), whereas the shallower Warburg region indicates hindered ion diffusion. PTRP has a modified oval shape (R ct ≈ 4–6 Ω ) , which decreases in size. In contrast, the RP-MO composite has a much smaller semicircle, indicating a lower charge transfer resistance (R ct ≈ ~ 0.5–1.5 Ω). In the low-frequency range, there is almost a vertical line, which indicates ideal capacitor behavior and good ion diffusion. The better performance of the CV and GCD tests also agrees with the above results and further confirms that the composite strategy helps improve the electrochemical kinetics. Other hybrid systems have been studied, including carbon-metal oxide composites, which show similar reductions in R ct owing to the conductive network for fast electron transport [ 42 ]. The electrochemical comparison of the MO, PTRP, and RP-MO electrodes revealed distinctive differences in charge storage behavior, kinetics, and energy storage performance, as indicated by the CV, GCD, EIS, capacitance, and energy density studies. In Fig. 8 a, the CV profiles suggest that all the electrodes are pseudocapacitive in nature and that RP-MO has the highest current response with more prominent redox peaks than MO and PTRP. The redox activity is dominated by the Mn³⁺/Mn⁴⁺ transition in alkaline media, which is in accordance with well-known manganese oxide chemistry [ 37 ]. Compared with the MO and PTRP electrodes, the RP-MO electrode offers an increased discharge time and a decreased IR drop, as shown in Fig. 8 b. This indicates that it has more capacitance and lower internal resistance. The near-symmetrical charge‒discharge curves imply high reversibility of the faradaic reactions. In Fig. 8 c, the Nyquist plot shows that the RP-MO electrode has a smaller semicircle due to a noticeably lower charge transfer resistance (R ct ) and a steeper low-frequency slope, which indicates efficient diffusion of ions. In quantitative terms, the capacitance and energy density results further confirmed the advantages of the composite electrode. The system of RP-MO achieves the maximum specific capacitance (approximately 460 F g − 1 ) and obtains an increased energy density (~ 13 Wh kg − 1 ) and a maximum power density of 2250 W kg − 1 , which are significantly greater than those of MO and PTRP (Table 1 and Fig. 8 d and 8 e ) . The MO pseudocapacitance contributes to this improvement. Importantly, the ability to maintain good energy density even at moderate power density indicates efficient charge transport and minimal kinetic limitations, which are usually difficult to achieve in purely faradaic systems. The electrochemical performance of RP-MO was compared with that of previously reported materials ( Table 2 ) . Table 1 Performance of the bare and composite materials prepared at different ratios. S. No. Electrode Capacitance (F g − 1 ) at 3 A g − 1 Energy density (Wh kg − 1 ) Power density (W kg − 1 ) Voltage (V) 1 MO 218 6.1 675 0.45 2 PTRP 167 4.6 675 0.45 3 25% RP-75% MO 148 4.1 675 0.45 4 37.5% RP-62.5% MO 135 3.8 675 0.45 5 50% RP-50% MO 377 10.6 675 0.45 Table 2 Electrochemical performance comparison of the previously reported work. Electrode Electrolyte Capacitance (F g − 1 ) Capacitance Retention (%) Cycles Voltage (V) Ref. BP/RP hybrid 1 M KOH 60.1 at 0.5 A g − 1 83.3 2000 -1 to 0 [ 43 ] P nonodot-rGO 1 M H 2 SO 4 334.2 at 1 A g − 1 - - 0.2 to 0.8 [ 44 ] rP@rGO 2 M KOH 294 at 1.5 A g − 1 97 4500 -0.1 to 0 [ 31 ] C-RP 1 MKOH 105.8 at 0.5 A g − 1 100 3000 0 to 1 [ 45 ] g-C 3 N 4 -RPh 0.2 M Na 2 SO 4 465 at 1 A g − 1 90 1000 0 to 0.4 [ 46 ] RP-MO (1:1) 1 M KOH 463.1 at 1 A g − 1 96 2000 0 to 0.45 This work The RP-MO composite electrode performed well in KOH for long-term cycling, indicating the stability of the faradaic process as well as the benefit of the composite itself. As shown in Fig. 7 f, the capacitance retention decreases steeply during the first cycles and then plateaus, with a retention of 96.22% after 2000 cycles. The RP-MO composite starts with a coulombic efficiency of 90.26% after 2000 cycles, which later decreases to 84%. In contrast, the process has a consistently high coulombic efficiency of ~ 90% throughout the cycles, which means that it remains highly reversible. The consistently high coulombic efficiency indicates that faradaic reactions are kinetically favourable and reversible, which is in agreement with pseudocapacitive theory. The 96% suggests a promising level of performance; however, the reduced capacitance still indicates a gradual decline in the active material or accessible surface area due to the degradation of MO. 4. Conclusion The aim of this study was to investigate red phosphorus‒manganese(III) oxide (RP‒MO) composites that can potentially enhance the electrochemical performance of supercapacitor electrodes. This work successfully addressed the poor electronic conductivity and moderate electrochemical stability of MO by effectively incorporating PTRP and MO. The composite electrode exhibited a specific capacitance of 377 F g⁻¹, the maximum value. Compared with the individual components, it also has energy and power densities of ~ 13 Wh kg⁻¹ and 2250 W kg⁻¹, respectively. The improved charge storage and transfer characteristics are due to the synergistic interplay of the faradaic pseudocapacitance of MO with RP. Importantly, the fact that the composite can deliver a high energy density at relatively moderate power densities implies that charge can be transported through it without severe kinetic limitations, a common challenge in purely faradaic systems. The RP-MO electrode shows acceptable stability in a KOH electrolyte, with a retention of 96.22% after 2000 cycles, confirming stable electrochemical interface formation. This highlights the composite mechanism that has the potential to enhance the electrochemical performance beyond the performance of the materials alone. The RP-MO composite approach offers promising prospects for the design of next-generation energy storage materials, which are highly useful in supercapacitor applications. Declarations Author(s) Contributions First author: Conceptualization, Methodology, Investigation, Data Curation, Formal Analysis, Writing-original draft. Corresponding author: Supervision, Validation, Resources, Writing—Review & Editing, Project Administration. Funding Sources Not applicable Acknowledgement The authors express their thanks to Vellore Institute of Technology, Vellore, India, for providing financial assistance. References Salaheldeen M, Eskander TNA, Fathalla M, Zhukova V, Blanco JM, Gonzalez J, Zhukov A, Abu-Dief AM (2025) Empowering the Future: Cutting-Edge Developments in Supercapacitor Technology for Enhanced Energy Storage. Batteries 11:232. 10.3390/batteries11060232 Augustyn V, Simon P, Dunn B (2014) Pseudocapacitive oxide materials for high-rate electrochemical energy storage. 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Matter 3:2012–2028. 10.1016/j.matt.2020.09.017 Liu S, Xu H, Bian X, Feng J, Liu J, Yang Y, Yuan C, An Y, Fan R, Ci L (2018) Hollow nanoporous red phosphorus as an advanced anode for sodium-ion batteries. J Mater Chem A 6:12992–12998. 10.1039/C8TA03301C Kong W, Xu S, Yin J, Yang H, Feng W, Cui L, Wen Z (2021) A novel red phosphorus/reduced graphene oxide-C3N4 composite with enhanced sodium storage capability. J Electroanal Chem 902:115819. 10.1016/j.jelechem.2021.115819 Gupta S, Carrizosa SB, Aberg B (2024) Designing high-performance asymmetric and hybrid energy devices via merging supercapacitive/pseudopcapacitive and Li-ion battery type electrodes. Sci Rep 14:29277. 10.1038/s41598-024-79622-6 Parveen N, Hilal M, Han JI (2020) Newly Design Porous/Sponge Red Phosphorus@Graphene and Highly Conductive Ni2P Electrode for Asymmetric Solid State Supercapacitive Device With Excellent Performance. Nano-Micro Lett 12:25. 10.1007/s40820-019-0360-3 Simon P, Gogotsi Y (2008) Materials for electrochemical capacitors. Nat Mater 7:845–854. 10.1038/nmat2297 Davis MA, Andreas HA (2018) Improved manganese oxide electrochemical capacitor performance arising from a systematic study of film storage/drying effects on electrochemical properties. Electrochim Acta 292:147–156. 10.1016/j.electacta.2018.08.099 Yadav A, Singal S, Kumar J, Sharma RK (2024) Sonochemically synthesized porous V2CTx MXene/red-black phosphorus composite: A promising electrode for supercapacitors. J Energy Storage 79:110155. 10.1016/j.est.2023.110155 Li J-Q, Zhou F-C, Sun Y-H, Nan J-M (2018) FeMnO3 porous nanocubes/Mn2O3 nanotubes hybrids derived from Mn3[Fe(CN)6]2·nH2O Prussian Blue Analogues as an anode material for lithium-ion batteries. J Alloys Compd 740:346–354. 10.1016/j.jallcom.2017.12.370 Irfan M, Shahi A, Bari MA, Laiba, Atiq S, Shakoor A, Sadiq I, Tariq A, Adnan M, Shahzad A et al (2026) Emerging composite electrode architectures based on transition metal oxides for high-performance Li-ion capacitors. RSC Adv 16:4801–4840. 10.1039/D5RA08307A Nathan T, Cloke M, Prabaharan SRS (2008) Electrode Properties of Mn 2 O 3 Nanospheres Synthesized by Combined Sonochemical/Solvothermal Method for Use in Electrochemical Capacitors. J Nanomaterials 2008:948183. 10.1155/2008/948183 Fu Y, Wei Q, Zhang G, Sun S (2018) Advanced Phosphorus-Based Materials for Lithium/Sodium‐Ion Batteries: Recent Developments and Future Perspectives. Adv Energy Mater 8:1703058. 10.1002/aenm.201702849 Li X, Elshahawy AM, Guan C, Wang J (2017) Metal Phosphides and Phosphates-based Electrodes for Electrochemical Supercapacitors. Small 13:1701530. 10.1002/smll.201701530 Jiang H, Yan L, Zhang S, Zhao Y, Yang X, Wang Y, Shen J, Zhao X, Wang L (2021) Electrochemical Surface Restructuring of Phosphorus-Doped Carbon@MoP Electrocatalysts for Hydrogen Evolution. Nano-Micro Lett 13:215. 10.1007/s40820-021-00737-w Raikwar AS, Panda HS (2025) A review on nano-structured electrodes for high-performance supercapacitors: panoramic insights across dimensional spectra. Discov Electron 2:94. 10.1007/s44291-025-00132-4 Kumar K, Pani B, Maity SK, Singh S, Roy D, Kumar G (2026) Toward greener energy storage electrodes: Hierarchically engineered rice straw-derived activated carbon integrated with SnO2/ZnO binary oxides for high-performance supercapacitors. Diam Relat Mater 113594. 10.1016/j.diamond.2026.113594 Chen X, Xu G, Ren X, Li Z, Qi X, Huang K, Zhang H, Huang Z, Zhong J (2017) A black/red phosphorus hybrid as an electrode material for high-performance Li-ion batteries and supercapacitors. J Mater Chem A 5:6581–6588. 10.1039/C7TA00455A Khalid Mohd, Varela H (2018) A general potentiodynamic approach for red phosphorus and sulfur nanodot incorporation on reduced graphene oxide sheets: metal-free and binder-free electrodes for supercapacitor and hydrogen evolution activities. J Mater Chem A 6:3141–3150. 10.1039/C7TA11342K Khalid Mohd, Honorato AMB, Pasa AA, Varela H (2020) A sugar derived carbon-red phosphorus composite for oxygen evolution reaction and supercapacitor activities. Mater Sci Energy Technol 3:508–514. 10.1016/j.mset.2020.05.002 Ansari SA, Ansari MO, Cho MH (2016) Facile and Scale Up Synthesis of Red Phosphorus-Graphitic Carbon Nitride Heterostructures for Energy and Environment Applications. Sci Rep 6:27713. 10.1038/srep27713 Additional Declarations No competing interests reported. Cite Share Download PDF Status: Under Review Version 1 posted Reviews received at journal 11 May, 2026 Reviews received at journal 23 Apr, 2026 Reviewers agreed at journal 23 Apr, 2026 Reviewers agreed at journal 23 Apr, 2026 Reviewers invited by journal 20 Apr, 2026 Editor assigned by journal 10 Apr, 2026 Submission checks completed at journal 10 Apr, 2026 First submitted to journal 08 Apr, 2026 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-9352351","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":628388033,"identity":"dd7cad48-215f-4f18-b53a-b212501c8cdb","order_by":0,"name":"Sowmiya Selvaraj","email":"","orcid":"","institution":"Vellore Institute of Technology University","correspondingAuthor":false,"prefix":"","firstName":"Sowmiya","middleName":"","lastName":"Selvaraj","suffix":""},{"id":628388034,"identity":"f50dac02-5f6d-40a4-9513-3591af1c2834","order_by":1,"name":"Anand Sreekantan Thampy","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABCUlEQVRIiWNgGAWjYLACHiCWYGBsYAbSciCBAw9I0WIM1pJAnBYGBpCWxAaQCD4t/LObnz14w1DHIDn7cPPnwh126fPDDj8E2mInp9uAXYvEnWPmhnMYDjNI8yW2Sc88k5y78XaaAVBLsrHZARzW3Egwk+ZhOMAgx8PYxszbxpy7cXYCSMuBxG04tMjfSP8G1FIH0tL8mbetPt1wdvoHvFoMbuSAbGFmkOZhbJDmbTucIC+dg98Wwxs5ZZJzDA7zSPYwtgG1HDfcIJ1TcCDBALdf5G6kb5N4U1EnJ3GG/THQYdXy8rPTN3/4UGEnh9P7EOeBowbKPgARIQHIN5CiehSMglEwCkYCAAATa1g/9jLVrQAAAABJRU5ErkJggg==","orcid":"","institution":"Vellore Institute of Technology University","correspondingAuthor":true,"prefix":"","firstName":"Anand","middleName":"Sreekantan","lastName":"Thampy","suffix":""}],"badges":[],"createdAt":"2026-04-08 06:23:16","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-9352351/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-9352351/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":108132651,"identity":"c9421ee5-d23c-41fa-9b5a-4cc653db648e","added_by":"auto","created_at":"2026-04-29 16:39:37","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":445496,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cem\u003eSchematic representation of the synthesis of (a) manganese (III) oxide (MO) and pretreated red phosphorus (PTRP) and (b) red phosphorus‒manganese (III) oxide (RP‒MO) composite electrode coatings on nickel foam.\u0026nbsp;\u003c/em\u003e\u003c/p\u003e","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-9352351/v1/a4aebf639f33830ee14b6d90.png"},{"id":108132661,"identity":"ab0478cc-b454-4a65-9485-9e075b88f966","added_by":"auto","created_at":"2026-04-29 16:39:39","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":263548,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cem\u003eXRD patterns of (a) RP before and after pretreatment and (b) the composite of the RP-MO composite\u003c/em\u003e\u003c/p\u003e","description":"","filename":"floatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-9352351/v1/77e5b5c51814cfa0d718cdf5.png"},{"id":108132654,"identity":"44eadc39-9ab9-4205-9451-79c06e54a8f0","added_by":"auto","created_at":"2026-04-29 16:39:37","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":936128,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cem\u003eFESEM images and EDX spectra of (a) commercial RP, (b) PTRP,(c) MO and (d) the RP-MO composite\u003c/em\u003e\u003c/p\u003e","description":"","filename":"floatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-9352351/v1/5ef890dd71cf69bb7b7f039f.png"},{"id":108132657,"identity":"5b99e6b9-5cd6-4239-9b5c-0960fd8fccea","added_by":"auto","created_at":"2026-04-29 16:39:38","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":1212619,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cem\u003eFESEM-EDX mapping images of (a) commercial RP, (b) PTRP, (c) MO, and (d) the RP-MO composite\u003c/em\u003e\u003c/p\u003e","description":"","filename":"floatimage4.png","url":"https://assets-eu.researchsquare.com/files/rs-9352351/v1/1d1805935376cefbc8109368.png"},{"id":108132649,"identity":"b8322db3-3820-4ed1-99e3-4cc33c6e7e9d","added_by":"auto","created_at":"2026-04-29 16:39:37","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":322059,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cem\u003eElectrochemical performance analysis of bare MO samples: (a) CV curves, (b) GCD curves, (c) Nyquist plot, (d) specific capacitances calculated from the GCD curves at different current densities (1 to 10 A g\u003c/em\u003e\u003csup\u003e\u003cem\u003e-1\u003c/em\u003e\u003c/sup\u003e\u003cem\u003e), and (e) energy density vs power density plots.\u003c/em\u003e\u003c/p\u003e","description":"","filename":"floatimage5.png","url":"https://assets-eu.researchsquare.com/files/rs-9352351/v1/393d56be08944313d757a1d0.png"},{"id":108132642,"identity":"850d2f28-ac09-41a0-a7c7-f946f1d8e347","added_by":"auto","created_at":"2026-04-29 16:39:34","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":317795,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cem\u003eElectrochemical performance analysis of PTRP: (a) CV curves, (b) GCD curves, (c) Nyquist plot, (d) energy density vs\u003c/em\u003e\u003cu\u003e\u003cem\u003e.\u003c/em\u003e\u003c/u\u003e\u003cem\u003e power density plot, and (e) specific capacitance calculated from the GCD curve at different current densities (1-10 A g\u003c/em\u003e\u003csup\u003e\u003cem\u003e-1\u003c/em\u003e\u003c/sup\u003e\u003cem\u003e).\u003c/em\u003e\u003c/p\u003e","description":"","filename":"floatimage6.png","url":"https://assets-eu.researchsquare.com/files/rs-9352351/v1/ce030dd72d6e42159c3bb40c.png"},{"id":108182317,"identity":"b5f0cd1a-7543-4287-8be7-6f82a366e9ce","added_by":"auto","created_at":"2026-04-30 08:59:18","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":398487,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cem\u003eElectrochemical performance analysis of RP-MO composites\u003c/em\u003e\u003cu\u003e\u003cem\u003e:\u003c/em\u003e\u003c/u\u003e\u003cem\u003e (a) CV curves, (b) GCD curves, (c) Nyquist plot, (d) specific capacitance calculated from the GCD curve at different current densities\u003c/em\u003e\u003cdel\u003e\u003cem\u003e,\u003c/em\u003e\u003c/del\u003e\u003cem\u003e (1 to 5 A g\u003c/em\u003e\u003csup\u003e\u003cem\u003e-1\u003c/em\u003e\u003c/sup\u003e\u003cem\u003e)\u003c/em\u003e\u003cu\u003e\u003cem\u003e,\u003c/em\u003e\u003c/u\u003e\u003cem\u003e (e) energy density vs\u003c/em\u003e\u003cu\u003e\u003cem\u003e.\u003c/em\u003e\u003c/u\u003e\u003cem\u003e power density plot, and (f) capacitance retention of the electrode after up to 2000 GCD cycles.\u003c/em\u003e\u003c/p\u003e","description":"","filename":"floatimage7.png","url":"https://assets-eu.researchsquare.com/files/rs-9352351/v1/7c48a020c715725b74661966.png"},{"id":108132647,"identity":"18949f3b-6d66-4761-8578-fb10d19d3ef3","added_by":"auto","created_at":"2026-04-29 16:39:36","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":331398,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cem\u003eElectrochemical performance of the bare MO, PTRP, and RP‒MO composite electrodes evaluated via a three-electrode system: (a) CV curves, (d) GCD curves, (c) Nyquist plot, (d) energy density at a power density of 725 W kg⁻¹, and (e) specific capacitance derived from the GCD curve.\u003c/em\u003e\u003c/p\u003e","description":"","filename":"floatimage8.png","url":"https://assets-eu.researchsquare.com/files/rs-9352351/v1/a5557f5e57f24d7490193f01.png"},{"id":108184542,"identity":"fa885a90-2320-4a77-9190-fc5e6f777113","added_by":"auto","created_at":"2026-04-30 09:04:22","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":4559761,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9352351/v1/95b65af0-6330-44a9-a31b-287ae086e9f4.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Boosting Electrochemical Performance via Red Phosphorus-Manganese(III) Oxide Composite Electrodes for Supercapacitors ","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eThe increasing need for energy storage systems is causing a buzz in the scientific community. Supercapacitors (SCs) are a good research and development (R\u0026amp;D) candidate because they provide a perfect trade-off between the functionalities of conventional capacitors and batteries [\u003cspan additionalcitationids=\"CR2\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. Supercapacitors deliver high power and large current while charging and discharging. Moreover, they exhibit remarkable cycle life; these materials are well suited for portable and wearable electronics, hybrid electric vehicles, and grid stabilization [\u003cspan additionalcitationids=\"CR5\" citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. However, despite these advantages, a defect persists: high energy density at the expense of power performance and long-term stability. The properties of electrode materials and charge-storage mechanisms can influence the performance of supercapacitors. Supercapacitor electrodes should ideally possess high conductivity and a substantial number of electrochemically active sites that enable fast diffusion and stability during prolonged cycling [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. Most single-component materials do not meet these requirements. Manganese oxides (MnO) belong to a family of transition metal oxides. They are attracting much attention because of their high theoretical capacitance and low cost, as well as their eco-friendliness. Among these materials, manganese (III) oxide (MO) exhibits promising pseudocapacitance from the reversible redox reaction of Mn\u0026sup3;⁺/Mn⁴⁺ in alkaline electrolytes. Nonetheless, MO has intrinsic problems such as low electrical conductivity and slow charge transfer kinetics, limiting its electrochemical performance in real-world applications, especially at a high rate of operation. Owing to these limitations, which restrict MO from reaching its theoretical capacity [\u003cspan additionalcitationids=\"CR10\" citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e], the rate capability is poor, the internal resistance is high, and the cycling stability is low.\u003c/p\u003e \u003cp\u003eTo solve these problems, intensive work has been done to enhance the electrochemical behavior of manganese oxide-based electrodes. Nanostructuring, doping, and hybridization with conductive materials are different techniques. Nanostructuring increases the surface area and shortens the ion diffusion route, thus improving the electrochemical accessibility [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. However, nanoscale materials often undergo aggregation and structural instability during cycling. The presence of heteroatoms in polyethylene can make it conductive, but at the same time, it can lead to defects. In recent research, composite approaches involving manganese oxides with conductive matrices (carbon materials such as graphene [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan additionalcitationids=\"CR14\" citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e] and carbon nanotubes [\u003cspan additionalcitationids=\"CR17 CR18 CR19\" citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e] or conducting polymers [\u003cspan additionalcitationids=\"CR22 CR23 CR24\" citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]) have shown promising potential. The aim of these composites is to achieve, through synergy, an increase in the electric double-layer capacitance (EDLC) to increase the pseudocapacitance. Carbon composite materials are synthesized via elaborate routes, which increase their production costs and limit their scalability. On the other hand, conducting polymers may be mechanically unstable and degrade after repeated cycling. Moreover, several studies have reported enhancements in capacitance or conductivity, often ignoring the intertwined issues of long-term stability and rate performance. This shows that although the synergy concept is well known, the application is not yet complete [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eRed phosphorus (RP) has recently emerged as a new and interesting candidate for composite electrode development. Historically, RP has unique physicochemical properties, including a high theoretical capacity and the potential to form surface functional groups that can increase the electrochemical activity of batteries [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e, \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]. Pretreated red phosphorus (PTRP) desensitizes a sample, subsequently promoting conductivity and surface reactivity, and has the potential to be a matrix for redox-active materials. The RP is unlike carbon matrices that are used traditionally; it can contribute to conductance and capacitive behavior, thus offering double functionality. Nevertheless, the connection of RP with transition metal oxides, particularly MO, is underexplored. Research on phosphorus-based composites has focused mainly on lithium-ion or sodium-ion batteries, neglecting supercapacitor systems. Creating an ideal electric double-layer capacitor and pseudocapacitor system is challenging since the two mechanisms often operate against each other. To achieve this, the material composition, morphology, and interfacial properties need to be controlled, which remains a main focus of current research [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eTo resolve this problem, a red phosphorus‒manganese(III) oxide (RP‒MO) composite electrode has been developed. Next, the electrochemical performance was systematically investigated in an alkaline electrolyte. This work investigated PTRP as a multifunctional additive that improves the conductivity and capacitive behavior, unlike conventional systems with only carbon-based matrices. This research aims to overcome the limitations of MO by combining it with PTRP, which has specific properties arising from its RP content, and is analysed at different ratios. The author of the study also performed a detailed examination of performance metrics, such as the specific capacitance of the RP-MO composite, which was 317 F g-1 at a current density of 5 A g-1 with energy and power densities of 8.9 Wh kg-1 and 1125 W kg-1, respectively. The cycling stability and coulombic efficiency of the RP-MO composite are 96% and 90.26%, respectively, after 2000 cycles. In summary, although composite electrode design has been beneficial according to past research, there are gaps in the identification of other conductive matrices and their interactions with transition metal oxides. The goal of this work is to develop a new component of MO-based electrodes containing RP for the effective development of supercapacitor materials. These findings are expected to advance the field of energy storage by revealing novel composite mechanisms and guiding the design of next-generation electrode architectures.\u003c/p\u003e"},{"header":"2. Materials and methods","content":" \u003cp\u003e2.1. Materials\u003c/p\u003e\n\u003cp\u003e2.2. Synthesis of pretreated-RP (PTRP)\u003c/p\u003e\u003cp\u003eThe RPs were pretreated via the reflux method. In this process, 1 g of RP powder in 100 ml of water was stirred at 70\u0026deg;C for 12 hours in an oil bath under reflux. The RP powder was cooled to room temperature and washed with DI water and ethanol several times. The pretreated RP was dried at 60\u0026deg;C overnight. The powder was well ground with a mortar and pestle \u003cb\u003e(\u003c/b\u003eFig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ea\u003cb\u003e)\u003c/b\u003e.\u003c/p\u003e \u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e2.3. Synthesis of manganese(III) oxide (MO)\u003c/h2\u003e \u003cp\u003eSynthesis of manganese(III) oxide by coprecipitation and annealing. By this method, 1.5 g of MnCl\u003csub\u003e2\u003c/sub\u003e and 0.9 g of KMnO\u003csub\u003e4\u003c/sub\u003e were separately dissolved in 50 ml of water and stirred for 30 mins. The KMnO\u003csub\u003e4\u003c/sub\u003e solution was added dropwise to the MnCl\u003csub\u003e2\u003c/sub\u003e solution. The mixture was agitated at room temperature for 15\u0026ndash;16 hours. The resulting black precipitate was thoroughly washed several times with deionized water and ethanol. The product was dried for 12 hours at 60\u0026deg;C. The powder was dried and heat-treated at 900\u0026deg;C for 6 hours. Afterward, the final product was crushed into a fine powder for composite synthesis. \u003cb\u003e(\u003c/b\u003eFig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ea\u003cb\u003e)\u003c/b\u003e.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e2.4. Synthesis of the RP‒MO Composite\u003c/h2\u003e \u003cp\u003eThe RP‒MO composite was prepared via sonication. MO and PTRP (20 mg) were added to a beaker containing 20 ml of acetone. The mixture was sonicated for 1 hour and dried at 60\u0026deg;C for 12 hours. The RP-MO composite was ground well and stored for further analysis. In this way, the RP‒MO composite was prepared by varying the ratio of RP.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003e2.5. Preparation of the RP‒MO electrode\u003c/h2\u003e \u003cp\u003eThe RP‒MO composite electrode was prepared alongside a polyvinyl pyrrolidone (PVDF) binder and activated carbon (AC) at a ratio of 8:1:1. A total of 100 \u0026micro;L of 1-methyl-2-pyrrolidone (NMP) was added to the mixture, which was subjected to ultrasonication for one hour. The resulting slurry is coated onto the cleaned nickel foam via a drop-casting method. Afterward, the nickel foam was dried at 60\u0026deg;C for 12 hours \u003cb\u003e(\u003c/b\u003eFig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eb\u003cb\u003e).\u003c/b\u003e\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003e2.6. Electrochemical and structural characterization\u003c/h2\u003e \u003cp\u003eX-ray diffraction patterns were obtained with a Bruker D8 Advance diffractometer with a PANalytical X\u0026rsquo;Pert3 CuKα radiation source in a 2θ range of 10\u0026ndash;90\u0026deg;. An EVO 18 Research (CARL ZEISS) scanning electron microscope (SEM) was used to study the morphology and elemental mapping. The CHI 660C device is employed for electrochemical analysis, with a 1 M potassium hydroxide (KOH) solution utilized as the electrolyte. The electrodes consisted of a platinum wire for the counter electrode, Ag/AgCl for the reference electrode, and nickel foam coated with slurry as the working electrode. The CH instrument is employed for various electrochemical analyses, including specific capacitance at different current densities, Ragone plots, and impedance spectroscopy.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"3. Results and Discussion","content":"\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003e3.1. Study design\u003c/h2\u003e \u003cp\u003eThe current research shows that, compared with the individual components, the RP-MO composite has enhanced electrochemical properties on nickel foam. This enhancement results from the synergistic combination of the EDLC and pseudocapacitance, according to structural and electrochemical characterization. On a theoretical level, these results are coherent with the principles employed in the design of hybrid SCs, i.e., faradaic and non-faradaic systems. MO is well known for its pseudocapacitance via reversible redox transitions of the Mn\u0026sup3;+/Mn⁴+ states. RP enhances the electrical conductivity as well as the surface-driven capacitance. The improvement observed in the RP-MO composite is consistent with the theory of interfacial charge-storage enhancement, in which heterostructures provide more active sites and reduce the charge-transfer resistance [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e, \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e].\u003c/p\u003e \u003cp\u003ePrevious studies have highlighted the importance of tuning the composition of metal-based oxide composites, and hybrid materials are typically superior to component electrodes because of their complementary charge-storage processes [\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e]. Likewise, nanoscale engineering and compositional synergy prominently enhance the rate capability and capacitance of pseudocapacitive systems [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. The current findings enhance our understanding of RP, a relatively unexplored material in supercapacitor electrodes, and its ability to modulate the electrochemical behavior of MO. Earlier studies on manganese oxides generally reported that they have performance limitations due to their poor electrical conductivity. However, this study revealed that RP incorporation satisfactorily alleviated this limitation. This difference might be due to improved contact at the interface and even spread, which occurred during synthesis, according to SEM mapping. Moreover, as nickel foam is a conductive substrate, it favours electron transmission and electrolyte access, enhancing the performance of the composite [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e]. These factors underscore the importance of electrode architecture in conjunction with material composition.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec9\" class=\"Section2\"\u003e \u003ch2\u003e3.2. Structural and morphological analysis\u003c/h2\u003e \u003cp\u003eAs shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e, commercial RP shows two broad peaks at 2θ\u0026thinsp;~\u0026thinsp;15.50\u0026deg; and 34.1\u0026deg;, which can be assigned to the (102) and (232) crystal planes of red phosphorous, respectively (JCPDS No. 44\u0026ndash;0906) [\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e]. Compared with that of commercial RP, the XRD pattern of PTRP exhibited a high-intensity peak at 2θ\u0026thinsp;~\u0026thinsp;15.50\u0026deg;. Several peaks of MO are detected at 2θ values of 23.2\u0026deg;, 33.2\u0026deg;, 38.7\u0026deg;, 45.5\u0026deg;, 49.4\u0026deg;, 53.3\u0026deg;, 55.2\u0026deg;, 57.5\u0026deg;, 60.8\u0026deg;, 64.1\u0026deg;, 66.0\u0026deg;, and 67.8\u0026deg; (JCPDS No. 41-1442). XRD analysis of the two bare materials indicated the formation of a composite [\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e].\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eSEM analysis provided useful information on the morphological changes that commercial RP (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ea) underwent to convert to PTRP (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eb), bare MO (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ec), and the RP-MO composite (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ed) and provided a structural explanation of the electrochemical behavior in the investigated electrolytic media. According to the information presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ea, commercial RP appears as agglomerates with irregular shapes, are bulky, and possess relatively smooth surfaces. They therefore likely have a low surface area and dispersion characteristics. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eb, RP is visibly more fragmented and rougher after pretreatment. Through this structural modification, its surface reactivity and dispersion capacity are enhanced, which is vital for effective composites. In Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ec, bare MO has a relatively well-defined angular microstructure, indicating the formation of a crystalline oxide. However, the high packing density of particles with low surface irregularities may inhibit electrolyte penetration and decrease the effective electrochemically active surface area. This observation is not surprising because pristine manganese oxides often have poorly accessible ions despite being intrinsically pseudocapacitive [\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e].\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eIn comparison, the morphology depicted in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ed for the RP-MO composite varies significantly, indicating the presence of MO, with RP being decorated or partly embedded. The SEM images indicate the presence of a heterogeneous but well-connected network, with smaller RP particles dispersed on the MO surface. The EDX spectrum shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e and the elemental mapping images in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e further support the coexistence of the constituents. The sequential spatial overlap of Mn, O, and P is suggestive of composite formation without appreciable phase separation. The importance of homogeneous dispersion is to facilitate the formation of continuous electronic channels and favourable interfacial contact, which positively influences the electrochemical performance. These morphological observations strengthen the synergistic charge storage mechanism in hybrid SCs involving EDLC and faradaic reactions in terms of capacitance performance. The rough RP surface and its distribution over MO most likely enhance the density of electrochemically active sites and the electronic conductivity. The theory of interfacial charge transfer holds that increasing the area of contact between different phases promotes the transfer of electrons and ions. In addition, the composite structure may construct a percolation network, potentially improving electron transport within the electrode for better rate capability and cycling stability [\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eXRD analyses of these materials confirmed the existence of the crystalline phase of MO and the amorphous or semicrystalline phase of RP. This is followed by SEM imaging with elemental mapping, which further shows that the MO is relatively homogeneously distributed within the phosphorus matrix.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec10\" class=\"Section2\"\u003e \u003ch2\u003e3.3. Electrochemical performance and synergistic effects\u003c/h2\u003e \u003cp\u003eThe MO, PTRP, and RP-MO composite electrodes under alkaline conditions exhibit electrochemical behavior in a KOH electrolyte, which is used to understand the faradaic process and interfacial charge transfer. The hybrid electrode systems have a potential window of 0\u0026ndash;0.45 V. Characterizing distinct charge storage mechanisms and kinetics through cyclic voltammetry (CV), galvanostatic charge\u0026ndash;discharge (GCD), and electrochemical impedance spectroscopy (EIS) not only corroborates the theories but also indicates possible new enhancements due to the composite. The CV profiles of all three electrodes exhibit prominent redox features, indicating pseudocapacitive behavior due to faradaic reactions. The oxidation and reduction peaks are caused by the Mn\u0026sup3;⁺/Mn⁴⁺ reversible process in alkaline solution, which is attributed to MO (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ea) [\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e]. However, the ongoing behavior of monometallic MnO is rather broad and moderate, which indicates low electronic conductivity and slow ion diffusion. Both are well-established weaknesses of MOs due to their semiconducting characteristics. The shift in peak potential, related to the increase in scan rate, also indicated polarization effects, indicating that pristine oxide has a diffusion-limited character.\u003c/p\u003e \u003cp\u003eIn contrast, the electrochemical behavior of the PTRP electrode is different. As mentioned before, MO has a relatively wide peak shape and a moderate current response. The peak is not expected to have high electrical conductivity or fast ion diffusion. These problems of MOs are well known because of their semiconducting character. The electrochemical signature of the PTRP electrode is completely different. The RP is usually regarded as a weak pseudocapacitive material. The CV curve in Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003ea is weak but denotes redox activity. This is attributed to oxidation and reduction at the surface level. This may also be due to the development of phosphorus-oxygen functionalities during pretreatment. This observation agrees with some studies reporting the electroactivity of different modified phosphorus-based materials [\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e]. The absence of distinct redox peaks and a low current density indicate that charge storage is limited by surface phenomena and has a limited faradaic contribution.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eAlthough having a reduced current density, the RP‒MO composite electrode is more pronounced. The CV curves (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003ea) retained their shape and exhibited sharper redox peaks. These improvements are indicative of a strong MO-matrix RP interaction. The combined configuration likely assists more effectively in electron transfer and enhances the number of active electrochemical sites. Such impacts have been widely observed in hybrid systems, which increase the utilization of redox-active materials through a conductive matrix. substances. [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. The decreased peak separation of the composite electrode indicates improved reversible and rapid charge transfer kinetics, indicative of a faster faradaic process. A closer examination of the scan rate dependence further supports this interpretation. The redox characteristics of the RP-MO electrode are maintained even at a scan rate of 200 mV s⁻\u0026sup1;, which indicates that surface-controlled pseudocapacitance mainly governs its reaction kinetics. Pristine MO behaves differently, as the peak distortion increases with increasing scan rate. The better kinetics of the composite are attributed to the hierarchical morphology of the RP-MO composite. These trends are also confirmed by the GCD measurements. The MO electrode exhibited a nonlinear charge\u0026ndash;discharge curve along with a short discharge time (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003eb\u003cb\u003e)\u003c/b\u003e, which indicates its lower capacitance and high internal resistance. It has a capacitance of 290 F g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e at 1 A g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and 120 F g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e at 10 A g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ed\u003cb\u003e)\u003c/b\u003e. A significant IR drop further indicates that the material has a poor conduction property. The discharge properties of the PTRP electrode are somewhat improved (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003eb\u003cb\u003e)\u003c/b\u003e, likely due to its larger surface area and partial conductivity resulting from pretreatment. Figure\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003ee shows that the specific capacitance of the PTRP is 193 F g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e at 1 A g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and 121 F g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e at 10 A g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e. However, it still does not have much faradaic contribution.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe RP-MO composite shows much improved GCD performance with a potential window of 0\u0026ndash;0.45 V, which discharges for significantly longer times and results in a smaller decrease in the IR at all current densities, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003eb. The consistent shape of the coulombic efficiency alongside the quasi-symmetric charge‒discharge profile reveals excellent reversibility and efficiency of the redox process. More importantly, the composite continues to deliver a high capacitance even at high current densities, indicating its superior rate capability. It has a capacitance of 464 F g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e at 1 A g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and 242 F g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e at 10 A g\u003csup\u003e\u0026minus;\u0026thinsp;1,\u003c/sup\u003e as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003ed. This behavior matches previous works on phosphorus\u0026ndash;metal oxide composites, in which a conductive scaffold was shown to reduce resistance loss and stabilize the electrochemical interface [\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e]. The enhanced GCD performance is attributed to the additional contribution from the phosphorus matrix and the pseudocapacitance of MO in terms of the mechanism. This charge storage mechanism aligns with theoretical models of composite electrodes in which the total capacitance is equal to the sum of contributions from surface adsorption and the faradaic redox process. However, the interaction between the two components appears to be more than additive, highlighting the importance of interfacial interactions between MO and PTRP [\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e, \u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e].\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eImpedance spectroscopy (EIS) provides additional insight into the interfacial and transport properties of the respective electrodes. The Nyquist plots clearly differ among the three systems shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ec, \u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003ec, and \u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003ec. The large semicircle of MO at high frequency indicates a large charge-transfer resistance (R\u003csub\u003ect\u003c/sub\u003e \u0026asymp; 3\u0026ndash;5 Ω), whereas the shallower Warburg region indicates hindered ion diffusion. PTRP has a modified oval shape (R\u003csub\u003ect\u003c/sub\u003e \u0026asymp; 4\u0026ndash;6 Ω\u003cb\u003e)\u003c/b\u003e, which decreases in size. In contrast, the RP-MO composite has a much smaller semicircle, indicating a lower charge transfer resistance (R\u003csub\u003ect\u003c/sub\u003e\u0026thinsp;\u0026asymp;\u0026thinsp;~\u0026thinsp;0.5\u0026ndash;1.5 Ω). In the low-frequency range, there is almost a vertical line, which indicates ideal capacitor behavior and good ion diffusion. The better performance of the CV and GCD tests also agrees with the above results and further confirms that the composite strategy helps improve the electrochemical kinetics. Other hybrid systems have been studied, including carbon-metal oxide composites, which show similar reductions in R\u003csub\u003ect\u003c/sub\u003e owing to the conductive network for fast electron transport [\u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e].\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe electrochemical comparison of the MO, PTRP, and RP-MO electrodes revealed distinctive differences in charge storage behavior, kinetics, and energy storage performance, as indicated by the CV, GCD, EIS, capacitance, and energy density studies. In Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003ea, the CV profiles suggest that all the electrodes are pseudocapacitive in nature and that RP-MO has the highest current response with more prominent redox peaks than MO and PTRP. The redox activity is dominated by the Mn\u0026sup3;⁺/Mn⁴⁺ transition in alkaline media, which is in accordance with well-known manganese oxide chemistry [\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e]. Compared with the MO and PTRP electrodes, the RP-MO electrode offers an increased discharge time and a decreased IR drop, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003eb. This indicates that it has more capacitance and lower internal resistance. The near-symmetrical charge‒discharge curves imply high reversibility of the faradaic reactions. In Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003ec, the Nyquist plot shows that the RP-MO electrode has a smaller semicircle due to a noticeably lower charge transfer resistance (R\u003csub\u003ect\u003c/sub\u003e) and a steeper low-frequency slope, which indicates efficient diffusion of ions.\u003c/p\u003e \u003cp\u003eIn quantitative terms, the capacitance and energy density results further confirmed the advantages of the composite electrode. The system of RP-MO achieves the maximum specific capacitance (approximately 460 F g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) and obtains an increased energy density (~\u0026thinsp;13 Wh kg\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) and a maximum power density of 2250 W kg\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, which are significantly greater than those of MO and PTRP (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e \u003cb\u003eand\u003c/b\u003e Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003ed and \u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003ee\u003cb\u003e)\u003c/b\u003e. The MO pseudocapacitance contributes to this improvement. Importantly, the ability to maintain good energy density even at moderate power density indicates efficient charge transport and minimal kinetic limitations, which are usually difficult to achieve in purely faradaic systems. The electrochemical performance of RP-MO was compared with that of previously reported materials \u003cb\u003e(\u003c/b\u003eTable\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e\u003cb\u003e)\u003c/b\u003e.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003ePerformance of the bare and composite materials prepared at different ratios.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"6\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eS. No.\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eElectrode\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eCapacitance\u003c/p\u003e \u003cp\u003e(F g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) at 3 A g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eEnergy density (Wh kg\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003ePower density (W kg\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eVoltage (V)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMO\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e218\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e6.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e675\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.45\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePTRP\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e167\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e4.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e675\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.45\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e25% RP-75% MO\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e148\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e4.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e675\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.45\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e37.5% RP-62.5% MO\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e135\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e3.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e675\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.45\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e50% RP-50% MO\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e377\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e10.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e675\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.45\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eElectrochemical performance comparison of the previously reported work.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"7\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eElectrode\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eElectrolyte\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eCapacitance\u003c/p\u003e \u003cp\u003e(F g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eCapacitance Retention (%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eCycles\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eVoltage (V)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eRef.\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBP/RP hybrid\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1 M KOH\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e60.1 at 0.5 A g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e83.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e2000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e-1 to 0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e[\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e]\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eP nonodot-rGO\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1 M H\u003csub\u003e2\u003c/sub\u003eSO\u003csub\u003e4\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e334.2 at 1 A g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.2 to 0.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e[\u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e44\u003c/span\u003e]\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003erP@rGO\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2 M KOH\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e294\u0026nbsp;at 1.5 A g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e97\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e4500\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e-0.1 to 0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e[\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e]\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eC-RP\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1 MKOH\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e105.8 at 0.5 A g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e3000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0 to 1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e[\u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e45\u003c/span\u003e]\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eg-C\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e-RPh\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.2 M Na\u003csub\u003e2\u003c/sub\u003eSO\u003csub\u003e4\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e465 at 1 A g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e90\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0 to 0.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e[\u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e46\u003c/span\u003e]\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eRP-MO (1:1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1 M KOH\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e463.1 at 1 A g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e96\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e2000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0 to 0.45\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eThis work\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eThe RP-MO composite electrode performed well in KOH for long-term cycling, indicating the stability of the faradaic process as well as the benefit of the composite itself. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003ef, the capacitance retention decreases steeply during the first cycles and then plateaus, with a retention of 96.22% after 2000 cycles. The RP-MO composite starts with a coulombic efficiency of 90.26% after 2000 cycles, which later decreases to 84%. In contrast, the process has a consistently high coulombic efficiency of ~\u0026thinsp;90% throughout the cycles, which means that it remains highly reversible. The consistently high coulombic efficiency indicates that faradaic reactions are kinetically favourable and reversible, which is in agreement with pseudocapacitive theory. The 96% suggests a promising level of performance; however, the reduced capacitance still indicates a gradual decline in the active material or accessible surface area due to the degradation of MO.\u003c/p\u003e \u003c/div\u003e"},{"header":"4. Conclusion","content":"\u003cp\u003eThe aim of this study was to investigate red phosphorus‒manganese(III) oxide (RP‒MO) composites that can potentially enhance the electrochemical performance of supercapacitor electrodes. This work successfully addressed the poor electronic conductivity and moderate electrochemical stability of MO by effectively incorporating PTRP and MO. The composite electrode exhibited a specific capacitance of 377 F g⁻\u0026sup1;, the maximum value. Compared with the individual components, it also has energy and power densities of ~\u0026thinsp;13 Wh kg⁻\u0026sup1; and 2250 W kg⁻\u0026sup1;, respectively. The improved charge storage and transfer characteristics are due to the synergistic interplay of the faradaic pseudocapacitance of MO with RP. Importantly, the fact that the composite can deliver a high energy density at relatively moderate power densities implies that charge can be transported through it without severe kinetic limitations, a common challenge in purely faradaic systems. The RP-MO electrode shows acceptable stability in a KOH electrolyte, with a retention of 96.22% after 2000 cycles, confirming stable electrochemical interface formation. This highlights the composite mechanism that has the potential to enhance the electrochemical performance beyond the performance of the materials alone. The RP-MO composite approach offers promising prospects for the design of next-generation energy storage materials, which are highly useful in supercapacitor applications.\u003c/p\u003e "},{"header":"Declarations","content":"\u003cp\u003eAuthor(s) Contributions\u003c/p\u003e\n\u003cp\u003eFirst author: Conceptualization, Methodology, Investigation, Data Curation, Formal Analysis, Writing-original draft.\u003c/p\u003e\n\u003cp\u003eCorresponding author: Supervision, Validation, Resources, Writing\u0026mdash;Review \u0026amp; Editing, Project Administration.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding Sources\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors express their thanks to Vellore Institute of Technology, Vellore, India, for providing financial assistance.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eSalaheldeen M, Eskander TNA, Fathalla M, Zhukova V, Blanco JM, Gonzalez J, Zhukov A, Abu-Dief AM (2025) Empowering the Future: Cutting-Edge Developments in Supercapacitor Technology for Enhanced Energy Storage. 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Sci Rep 6:27713. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1038/srep27713\u003c/span\u003e\u003cspan address=\"10.1038/srep27713\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"ionics","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"","sideBox":" Learn more about [Ionics](https://www.springer.com/journal/11581) ","snPcode":"11581","submissionUrl":"https://mc.manuscriptcentral.com/ionics","title":"Ionics","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Red phosphorus, Manganese oxide, Supercapacitors, Pseudocapacitance, Electrochemical energy storage, Charge transfer kinetics","lastPublishedDoi":"10.21203/rs.3.rs-9352351/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9352351/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThe development of high-performance electrode materials that simultaneously deliver high capacitance, high energy density, and long-term stability remains a key challenge in symmetric supercapacitor research. This study successfully produced a red phosphorus‒manganese(III) oxide (RP‒MO) composite electrode to address the intrinsic retarding factors for the application of manganese(III) oxide (MO), including low conductivity and poor rate capability. The electrochemical performance is enhanced by the simultaneous effects of pseudocapacitance from the metal oxide and the redox process. The RP-MO composite exhibited a specific capacitance of 317 F g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e at 5 A g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, the highest energy density of 13 Wh kg\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, and a maximum power density of 2250 W kg\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, which is better than that of the MO and pretreated RP electrodes. The composite has a relatively high energy density at intermediate power density, indicating good charge transport with low kinetic hindrance. The RP-MO underwent cycling stability tests and retained 96% after 2000 consecutive charge/discharge tests. The coulombic efficiency is quite high (~\u0026thinsp;90%), which indicates that the faradaic reactions are reversible and kinetically favourable. These results suggest that the RP-MO composites are potential energy storage candidates that exhibit capacitance fading, possibly due to the degradation of the MO.\u003c/p\u003e","manuscriptTitle":"Boosting Electrochemical Performance via Red Phosphorus-Manganese(III) Oxide Composite Electrodes for Supercapacitors ","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-04-29 16:39:14","doi":"10.21203/rs.3.rs-9352351/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"editorInvitedReview","content":"","date":"2026-05-11T05:25:27+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-04-23T12:50:43+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"284025987712279969955465343624720948916","date":"2026-04-23T10:17:56+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"62315793655224832216419258394530817813","date":"2026-04-23T05:56:04+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-04-20T17:27:51+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-04-10T13:39:34+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-04-10T13:39:26+00:00","index":"","fulltext":""},{"type":"submitted","content":"Ionics","date":"2026-04-08T06:10:23+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"ionics","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"","sideBox":" Learn more about [Ionics](https://www.springer.com/journal/11581) ","snPcode":"11581","submissionUrl":"https://mc.manuscriptcentral.com/ionics","title":"Ionics","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"ebb7267b-8ca1-4c1c-b051-0f6233fb1772","owner":[],"postedDate":"April 29th, 2026","published":true,"recentEditorialEvents":[{"type":"editorInvitedReview","content":"","date":"2026-05-11T05:25:27+00:00","index":28,"fulltext":""}],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-04-29T16:39:15+00:00","versionOfRecord":[],"versionCreatedAt":"2026-04-29 16:39:14","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-9352351","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9352351","identity":"rs-9352351","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}