Synergistic Effect of Co‐Mo Pinning in Lay‐Structured Oxide Cathode for Enhancing Stability toward Potassium‐Ion Batteries

Abstract

AbstractOwing to the high economic efficiency and energy density potential, manganese‐based layer‐structured oxides have attracted great interests as cathode materials for potassium ion batteries. In order to alleviate the continuous phase transition and K+ re‐embedding from Jahn‐Teller distortion, the [Mn‐Co‐Mo]O6 octahedra are introduced into P3‐K0.45MnO2 herein to optimize the local electron structure. Based on the experimental and computational results, the octahedral center metal molybdenum in [MoO6] octahedra proposes a smaller ionic radius and higher oxidation state to induce second‐order JTE (pseudo‐JTE) distortion in the adjacent [MnO6] octahedra. This distortion compresses the [MnO6] octahedra along the c‐axis, leading to an increased interlayer spacing in the K+ layer. Meanwhile, the Mn3+/Mn4+ is balanced by [CoO6] octahedra and the K+ diffusion pathway is optimized as well. The proposed P3‐K0.45Mn0.9Co0.05Mo0.05O2 cathode material shows an enhanced cycling stability and rate performance. It demonstrates a high capacity of 80.2 mAh g−1 at 100 mAh g−1 and 77.3 mAh g−1 at 500 mAh g−1. Furthermore, it showcases a 2000 cycles stability with a 59.6% capacity retention. This work presents a promising solution to the challenges faced by manganese‐based layered oxide cathodes and offers a deep mechanism understanding and improved electrochemical performance.