Boosting ionic conductivity of antiperovskite solid electrolyte by potassium ions substitution for cation clusters

Solid-state electrolytes (SSEs) with high ionic conductivities are crucial for the development of all-solid-state lithium batteries (ASSLBs), and there is a strong correlation between the ionic conductivities and underlying lattice structures of SSEs. Here, we report a novel lattice manipulation method of replacing 6OH>+ octahedral clusters with potassium ions in antiperovskite SSEs (Li2OH)0.99K0.01Cl, which leads to its ionic conductivity at room temperature two orders of magnitude higher than that of Li2OHCl. The mechanisms analysis indicates that the novel lattice manipulation method leads to the stabilization of cubic phase and lattice contraction for antiperovskite, and causes significant changes in Li-ion transport paths and migration barriers. Also, the Li | Li symmetric cell and LiFePO4 | Li ASSLB employing (Li2OH)0.99K0.01Cl electrolyte exhibit long-term stable cycling performance, which indicates the application prospects of antiperovskite electrolyte in ASSLBs.