Layer-structured P3-K0.5Mn0.95W0.05O2 for enhanced potassium-ion batteries by mitigating phase transformation

Abstract

Manganese-based layered transition metal oxides exhibit inherent advantages such as a low and high voltage plateau. However, they suffer from complex structural transformations and transition metal migration during cycling, and their energy density and lifespan cannot satisfy the increasing demand. The orbital and electronic structure of the octahedral center metal element are crucial for maintaining octahedral structural integrity and improving K ⁺ diffusivity through the introduced heterogeneous [Me–O] chemical bonding. Herein, inspired by the orbital bonding possibility arising from tungsten's abundant configuration of extranuclear electrons and large ionic radius, P3-type K_0.5Mn_0.95W_0.05O₂ (KMWO) was synthesized and employed as a cathode material for potassium-ion batteries. Experimental results indicate that the incorporation of tungsten significantly enhances cycling stability. After 1000 cycles, the capacity retention rate reached 90.5% at a current density of 200 mA g⁻¹. Hexavalent tungsten substitution is proven to shorten the detrimental phase transition process, effectively suppressing the movement of transition metal layers and the rearrangement from the P3-type structure to the O3-type structure, thereby reinforcing structural stability. This work not only demonstrates a straightforward and reliable potassium-ion battery cathode material but also provides novel design insights for the future exploration of advanced potassium-ion layered oxide cathode materials.