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

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-K_0.48[Li_0.1Mn_0.9]O₂ (P2-KLMO) delivers improved electrochemical performance, specific capacity and average discharge voltage of ∼124.4 mA h g⁻¹ and ∼2.7 V (vs. K⁺/K) at 0.05C (1C = 260 mA g⁻¹), outperforming P2-K_0.5MnO₂. 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 high-performance and practical cathode materials for KIBs.