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 Mn 2+ dissolution and structural degradation during the cycling process result in performance decay. Herein, interface engineering using an artificial Al 2 O 3 coating layer was proposed to improve the performance of the K 0.5 MnO 2 material. This Al 2 O 3 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 Mn 2+ dissolution. In addition, the Al 2 O 3 coating layer modified K 0.5 MnO 2 electrode exhibits highly reversible structure evolution, which could be attributed to the mitigation of structural degradation. As a result, the K 0.5 MnO 2 @Al 2 O 3 cathode delivers a high capacity (95.3 mAh g ‒1 at 50 mA g ‒1 ) and long lifespan (53% capacity over 300 cycles).