H-CoNiSe2/NC Dodecahedral Hollow Structures for High-performance Supercapacitors

The synergistic effect between metal ions and increasing the surface area leads to the fabrication of supercapacitor materials with high capacity. It is predicted that transition metal selenide compounds will be ideal electrode materials for supercapacitors. However, the defects of poor conductivity and volume expansion of the compounds are fundamental problems that must be solved. In this work, we successfully synthesized the cobalt-nickel selenide nitrogen-doped carbon (H-CoNiSe 2 /NC) hollow polyhedral composite structure using ZIF-67 as a precursor. The CoSe 2 and NiSe 2 nanoparticles embedded in the NC polyhedral framework offer a wealth of active sites for the whole electrode. Moreover, the presence of the NC structure in the proposed composite can simultaneously lead to improved conductivity and reduce the volume effect created during the cycling procedure. The H-CoNiSe 2 /NC electrodes provide high specific capacity (1131 C/g at 1.0 A/g) and outstanding cyclic stability (91.4% retention after 3000 cycles). In addition, the H-CoNiSe 2 /NC//AC hybrid supercapacitors deliver ultrahigh energy density and power density (81.9 Wh/kg at 900 W/kg) and excellent cycle stability (93.5% of initial capacity after 3000 cycles). This study will provide a supercapacitor electrode material with a high specific capacity for energy storage devices.