Electrochemical Failure Mechanism of δ‐MnO 2 in Zinc Ion Batteries Induced by Irreversible Layered to Spinel Phase Transition

作者：Chunyu Zhao, Mengqi Wu, Wencheng Lu, Yingjie Cheng, Xiaoya Zhang, Ismae͏̈l Saadoune, Ruqian Lian, Yizhan Wang, Yingjin Wei · 发表于：Small · 年份：2024 · DOI：10.1002/smll.202401379 · 被引用次数：23 · 研究领域：Advanced battery technologies research、Advancements in Battery Materials、Advanced Battery Materials and Technologies

Abstract Phase transitions of Mn‐based cathode materials associated with the charge and discharge process play a crucial role on the rate capability and cycle life of zinc ion batteries. Herein, a microscopic electrochemical failure mechanism of Zn‐MnO 2 batteries during the phase transitions from δ‐MnO 2 to λ‐ZnMn 2 O 4 is presented via systematic first‐principle investigation. The initial insertion of Zn 2+ intensifies the rearrangement of Mn. This is completed by the electrostatic repulsion and co‐migration between guest and host ions, leading to the formation of λ‐ZnMn 2 O 4 . The Mn relocation barrier for the λ‐ZnMn 2 O 4 formation path with 1.09 eV is significantly lower than the δ‐MnO 2 re‐formation path with 2.14 eV, indicating the irreversibility of the layered‐to‐spinel transition. Together with the phase transition, the rearrangement of Mn elevates the Zn 2+ migration barrier from 0.31 to 2.28 eV, resulting in poor rate performance. With the increase of charge–discharge cycles, irreversible and inactive λ‐ZnMn 2 O 4 products accumulate on the electrode, causing continuous capacity decay of the Zn‐MnO 2 battery.