Graphite Anode for Potassium Ion batteries: Current Status and Perspective

With the increased demand from the storage of renewable energy sources, some safe and inexpensive energy storage technologies instead of Li-ion batteries become urgently needed. Therefore, K-ion batteries (KIBs) have attracted much attention and evolved significant development because of the low price, safety, and similar property compared with Li-ion batteries. Due to the high reversibility, stability, and low potential plateau, graphite becomes a current research focus and is regarded as one of the most promising KIB's anode materials. In this review, we mainly discuss the electrochemical reaction mechanism of graphite during potassiation-depotassiation process and analyze the effects of electrode/electrolyte interface on graphite for K-ion storage. Besides, we summarize several kinds of methods to improve the performance of graphite for KIBs, including the design of graphite structure, selection of appropriate binder, solvent chemistry, and salt chemistry. Meanwhile, a concept of "relative energy density" is raised, which can be more accurate to evaluate the genuine electrochemical performance of graphite anode involving the specific capacity and potential. In addition, we also summarize the considerable challenges to current graphite anode in KIBs and we believe our work will offer alterative solutions to further explore high-performance graphite anode of K-ion storage.