Cation‐Anion‐Engineering Modified Oxychloride Zr‐Based Lithium Superionic Conductors for All‐Solid‐State Lithium Batteries

Abstract Within the family of halide solid electrolytes (SEs), Li 2 ZrCl 6 demonstrates high oxidative stability, cost‐effectiveness, and mechanical deformability, positioning it as a promising candidate for SEs. However, the application of Li 2 ZrCl 6 as a SEs was hindered by its low ionic conductivity at room temperature. Current strategies to enhance the ionic conductivity of Li 2 ZrCl 6 primarily are focused on single cation or anion sublattice‐engineering, each with distinct advantages and limitations. Here, we propose a novel cation and anion‐sublattice‐engineering strategy, termed CASE, to increase the amorphous content and thus enhance ionic conductivity. The incorporation of Cu 2+ and O 2− induces distinctive structural modifications within Li 2 ZrCl 6 . This structure corroborated through analytic data of X‐ray absorption spectroscopy, the neutron diffraction, and ab initio molecular dynamics. Consequently, the amorphous Li 2.1 Zr 0.95 Cu 0.05 Cl 4.4 O 0.8 achieves an enhanced ionic conductivity of 2.05 mS cm −1 at 25 °C. Furthermore, all‐solid‐state lithium batteries utilizing the amorphous Li 2.1 Zr 0.95 Cu 0.05 Cl 4.4 O 0.8 as an electrolyte and LiNi 0.83 Co 0.11 Mn 0.06 O 2 as a cathode exhibit a superior long‐term cycling stability retaining 90.3% of capacity after 1000 cycles at 2 C under room temperature, which are much higher than those of Zr‐based halide electrolytes in publications. Such a result might stimulate the development of more amorphous structures with high ionic conductivity in the CASE strategy.