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

Solid-state electrolytes with high ionic conductivities are crucial for the development of all-solid-state lithium batteries, and there is a strong correlation between the ionic conductivities and underlying lattice structures of solid-state electrolytes. Here, we report a lattice manipulation method of replacing [Li2OH]+ clusters with potassium ions in antiperovskite solid-state electrolyte (Li2OH)0.99K0.01Cl, which leads to a remarkable increase in ionic conductivity (4.5 x 10-3 mS cm-1, 25 degrees C). Mechanistic analysis indicates that the lattice manipulation method leads to the stabilization of the cubic phase and lattice contraction for the antiperovskite, and causes significant changes in Li-ion transport trajectories and migration barriers. Also, the Li||LiFePO4 all-solid-state battery (excess Li and loading of 1.78 mg cm-2 for LiFePO4) employing (Li2OH)0.99K0.01Cl electrolyte delivers a specific capacity of 116.4 mAh g-1 at the 150th cycle with a capacity retention of 96.1% at 80 mA g-1 and 120 degrees C, which indicates potential application prospects of antiperovskite electrolyte in all-solid-state lithium batteries. All-solid-state electrolytes for lithium batteries generally suffer from low ionic conductivity. Here, authors manipulate the lattice of antiperovskite-type Li2OHCl by potassium ion substitution, which alters the lattice structure and improves the lithium ion transport properties.

Automated summary

The lattice manipulation method of replacing [Li2OH]+ clusters with potassium ions in antiperovskite solid-state electrolyte leads to an increase in ionic conductivity. The method stabilizes the cubic phase and causes lattice contraction, resulting in improved lithium ion transport properties. The electrolyte shows potential application prospects in all-solid-state lithium batteries.