High Entropy-Tuning Enables Suppressed Phase Transition of Layered Manganese-Based Oxides for High-Mass-Loading Potassium-Ion Batteries

Abstract

Layered manganese-based oxides are regarded as promising cathode materials for potassium-ion batteries (PIBs). However, their practical application is hindered by sluggish reaction kinetics and poor cycling stability, primarily due to multiple phase transitions and pronounced Jahn–Teller distortion. Herein, a high-entropy layered oxide, K_0.45Mn_0.75Mg_0.05Al_0.05Cr_0.05 Co_0.05Ti_0.05O₂ is reported, in which the synergistic effect of multicomponent incorporation effectively addresses these challenges. The Cr³⁺/Cr⁶⁺ redox couple provides additional charge compensation and reduces the dependence on the Mn³⁺/Mn⁴⁺ redox pair, thereby mitigating Jahn–Teller distortion. Moreover, the increased configurational entropy suppresses the formation of the unfavorable P3″ phase and delays the P3′ phase transition during cycling, which enhances K⁺ diffusion kinetics and inhibits microcrack propagation. As a result, the synthesized cathode delivers a high discharge capacity of 124.2 mAh g⁻¹ at 20 mA g⁻¹ and retains 81% of its capacity after 120 cycles in a full-cell. Notably, a thick electrode with an ultrahigh mass loading of 48.5 mg cm⁻² achieves an areal capacity of 4.0 mAh cm⁻², representing a record-high value among PIB cathodes. This work offers a new pathway for the rational design of high-performance cathode materials, underscoring their promise for high-energy-density PIBs.