Entropy-stabilized layered KxMn7/13Ni1/13Fe1/13Mg1/13Zn1/13Cu1/13Al1/13O2 as stable cathode for potassium-ion batteries

To address challenges such as poor structural stability and short cycle life in potassium-ion battery cathodes, this study designed and synthesized a novel seven-component high-entropy oxide cathode material: K x Mn 7/13 Ni 1/13 Fe 1/13 Mg 1/13 Zn 1/13 Cu 1/13 Al 1/13 O 2 . A homogeneous solid solution with a single-phase rock-salt structure was successfully prepared via high-temperature solid-state synthesis, where the high-entropy effect significantly enhanced lattice stability. Electrochemical tests demonstrated that the material maintains over 81 % capacity retention after 100 cycles at 0.2 C. The synergistic effects of multiple transition metals effectively suppressed Jahn-Teller distortion and structural phase transitions, while Al 3+ and Mg 2+ doping reinforced framework stability. Additionally, Cu 2+ /Ni 2+ redox couples contributed to enhanced reversible capacity. This work confirms that the high-entropy strategy substantially improves structural integrity during K + (de)intercalation through lattice distortion and retarded diffusion effects, offering a new approach for developing long-cycle-life, high-stability potassium-ion battery cathodes. • Synthesis of rock-salt HEO cathode K x (Mn,Ni,Fe,Mg,Zn,Cu,Al)O 2 via co-precipitation and solid-state reaction. • x = 0.5 shows ideal crystallinity and morphology, enabling fast K+ diffusion (D K + = 2.78 × 10 −6 cm 2 s −1 ). • Synergy of Al 3+ /Mg 2+ and Cu 2+ /Ni 2+ with Mn 4+ dominance inhibits Jahn-Teller distortion and phase transitions. • Outstanding cycling stability: 81 % retention after 100 cycles at 100 mA g −1 .