Dual‐Role Surface Modification of Layered Oxide Cathodes for High‐Power Sodium‐Ion Batteries

Abstract P2‐type layered oxides have attracted extensive attentions due to their high reversible capacity and operating voltage when applied as cathode materials for sodium‐ion batteries (SIBs). However, the large ionic radius of Na + and restricted 2D diffusion channels account for the inferior Na + conductivity, limiting their practical application under large current densities. Herein, a facile dual‐role surface treatment on oxide precursors using KMnO 4 solution is employed to generate K + pillar and spinel‐like surface nanolayer in the layered oxide cathodes simultaneously. The substantial enhancement of Na kinetics is ascribed to the enlarged interlayer spacing in the lattice induced by K + pillar and the formation of coherent spinel‐like surface structure derived from the decomposition of KMnO 4 , which satisfies the timely Na + insertion/extraction and improves the rate performance. It is anticipated that this dual‐role strategy may provide a promising pathway for the development of the high‐power‐capability SIBs.