Interface engineering enabled high-performance layered P3-type K0.5MnO2 cathode for low-cost potassium-ion batteries

Mn-based layered oxides exhibit high theoretical capacity and are environmentally friendly. However, the Mn2+ dissolution and structural degradation during the cycling process result in performance decay. Herein, interface engineering using an artificial Al2O3 coating layer was proposed to improve the performance of the K0.5MnO2 material. This Al2O3 protective layer acts as a barrier to avoid direct contact between the active material and the electrolyte, which could improve the Coulombic efficiency by inhibiting the side reactions, and boost the cycling stability via suppressing the Mn2+ dissolution. In addition, the Al2O3 coating layer modified K0.5MnO2 electrode exhibits highly reversible structure evolution, which could be attributed to the mitigation of structural degradation. As a result, the K0.5MnO2@Al2O3 cathode delivers a high capacity (95.3 mAh g‒1 at 50 mA g‒1) and long lifespan (53% capacity over 300 cycles).