Recent Progress and Prospects of Layered Cathode Materials for Potassium‐ion Batteries

Layered materials with two‐dimensional ion diffusion channels and fast kinetics are attractive as cathode materials for secondary batteries. However, one main challenge in potassium‐ion batteries is the large ion size of K + , along with the strong K + −K + electrostatic repulsion. This strong interaction results in initial K deficiency, greater voltage slope, and lower specific capacity between set voltage ranges for layered transition metal oxides. In this review, a comprehensive review of the latest advancements in layered cathode materials for potassium‐ion batteries is presented. Except for layered transition metal oxides, some polyanionic compounds, chalcogenides, and organic materials with the layered structure are introduced separately. Furthermore, summary and personal perspectives on future optimization and structural design of layered cathode materials are constructively discussed. We strongly appeal to the further exploration of layered polyanionic compounds and have demonstrated a series of novel layered structures including layered K 3 V 2 (PO 4 ) 3 .