The Quest for Stable Potassium-Ion Battery Chemistry

Potassium-ion batteries (KIBs) have attracted wide interest for energy storage because of the abundance of the electrode materials involved; however, their electrochemical performances are far behind what can be achieved from lithium-ion batteries (LIBs) or sodium-ion batteries (SIBs). Herein, key promising electrode and electrolyte materials for potassium-ion batteries are identified, the coupled electrochemical reactions in the cell are investigated, and the compatibility between different materials is demonstrated to play the most important role. K2Mn[Fe(CN)(6)] cathode can deliver a high capacity of approximate to 125 mAh g(-1) and exceptional cycling stability over 61 000 cycles (approximate to 9 months) if the side reactions from the anode can be prevented. Graphite is a good anode material but is subjected to degradation in traditional carbonate electrolytes. New concentrated electrolytes are developed and evaluated. A stable KIB system is demonstrated by coupling a stable K2Mn[Fe(CN)(6)] cathode, a prepotassiated graphite anode with a concentrated electrolyte to achieve a high energy density of approximate to 260 Wh kg(-1) (based on the active mass of cathode and anode) and good cycling of over 1000 cycles.

Automated summary

Potassium-ion batteries have the potential for high capacity and exceptional cycling stability, but advancements are needed in electrode and electrolyte materials selection, as well as controlling coupled electrochemical reactions and ensuring compatibility between materials. Stability can be achieved by using a stable K2Mn[Fe(CN)(6)] cathode, prepotassiated graphite anode, and concentrated electrolyte, resulting in a high energy density and good cycling performance.