Revisiting the Role of Hydrogen in Lithium‐Rich Antiperovskite Solid Electrolytes: New Insight in Lithium Ion and Hydrogen Dynamics
Sifan Ling, Bei Deng, Ruo Zhao, Haibin Lin, Long Kong, Ruiqin Zhang, Zhouguang Lu, Juncao Bian, Yusheng Zhao
Abstract
Abstract Li 2 OH X ( X = Cl or Br) with an antiperovskite structure possess the advantages of low melting point, low cost, and ease of scaling‐up, which show great promise for applications in all‐solid‐state Li metal batteries (ASSLMBs). However, Li‐ion transport mechanisms in Li 2 OH X are still debated and the influence of H on the electrochemical performance of Li 2 OH X is yet to be explored. Herein, combining the theoretical calculations and experimental measurements, it is found that H affects Li‐ion transport, crystal stability, electrochemical stability, and electronic conductivity of Li 2 OH X . Compared with H‐free Li 3 OCl, although H helps to generate vacancy‐like defects, the electrostatic repulsive force between H and Li‐ion leads to an increase in both the activation energy and the diffusion length (space compensation effect), resulting in special Li ion transport trajectories along the Li‐O plane. Decreasing H content reduces the electronic conductivity and enhances the reduction‐resistant ability of Li 2 OH X , promoting the cycling stability and rate performance of Li∣Li 2 OH X ∣Li symmetric cells and the ASSLMBs. This work delivers a new insight into the role of H in antiperovskite Li 2 OH X and can serve as guidance for solid electrolyte design.