Revisiting Intercalation Anode Materials for Potassium-Ion Batteries

Potassium-ion batteries (KIBs) have attracted significant attention in the last few years due to the necessity to develop low-cost, sustainable batteries, based on non-critical raw materials, and to be competitive with lithium-ion batteries. KIBs are excellent candidates due to the possibility of providing high power and energy densities because of their faster K+ diffusion and very close re-duction potential to Li+/Li. However, KIBs research is still in its infancy; hence, further investigation should be carried out from the materials to the device level. In this work, we focus on the recent strategies to enhance the electrochemical properties of anode intercalation materials, i.e., carbon-, titanium- and vanadium-based compounds. Hitherto, the most promising anode materials are the carbon-based ones, such as graphite, soft or hard carbon, each with its advantages and disad-vantages. Although a wide variety of strategies have been reported with excellent performances, the standardization of best carbon properties, electrode formulation and electrolyte composition still need to be improved due to the impossibility of a direct comparison. Therefore, further effort should be made to understand which are the crucial carbon parameters to develop a reference electrode and electrolyte formulation to boost the performances further and move a step forward in the commercialization of KIBs.