Enhancing power capability and fast discharge behavior in P2-type K layered cathodes through structural stabilization via introducing Li-ions into TM layers

Abstract

Mn-based layered oxides are widely recognized as cathode materials for potassium-ion batteries (KIBs) due to their high specific capacity derived from their low molar mass. However, the structural instability caused by the Jahn-Teller effect of Mn3+ and the large ionic radius of K+ results in poor electrochemical performance. Herein, we propose an effective structural stabilization strategy for P2-type Mn-based layered oxide cathodes of KIBs through Li-incorporation into the transition metal layer. Using the first-principles calculations and experiments, we demonstrate that the P2-K0.48[Li0.1Mn0.9]O2 (P2-KLMO) delivers improved electrochemical performance, specific capacity and average discharge voltage of similar to 124.4 mA h g-1 and similar to 2.7 V (vs. K+/K) at 0.05C (1C = 260 mA g-1), outperforming P2-K0.5MnO2. Operando X-ray diffraction analysis confirms the P2-OP4 phase transition and Mn3+-induced Jahn-Teller distortion are significantly suppressed in P2-KLMO. These improvements are attributed to the lithium introduction into transition metal layers, leading to strengthened structural stability and enhanced K+ diffusion kinetics. Moreover, synthetic accessibility through the conventional solid-state method provides an additional advantage for practical application of Li-incorporated Mn-based P2-type cathodes in KIBs. We believe our study offers a simple yet effective strategy for designing highperformance and practical cathode materials for KIBs. (c) 2025 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights are reserved, including those for text and data mining, AI training, and similar technologies.