High-throughput discovery of Li3Sc2(PO4)3 as a protective coating for stabilizing mid-Ni NCM interfaces in all-solid-state batteries

As all-solid-state battery (ASSB) technologies continue to advance, interest has resurfaced in mid-nickel (mid-Ni) LiNixCoyMnzO2 (NCM; x = 0.5) cathodes due to their enhanced structural stability, reduced oxygen evolution, and higher capacities at elevated cutoff voltages compared to high-nickel compositions. However, interfacial degradation including parasitic reactions with solid-state electrolytes (SSEs) remains a major challenge. To address this issue, we conducted a high-throughput computational screening of oxide-based coating materials, evaluating their electrochemical stability, interfacial robustness, and Li-ion conductivity using Li–Li network descriptors. From this screening, 8 candidates were selected based on strict criteria. Among them, Li3Sc2(PO4)3 emerged as a particularly promising coating material, exhibiting strong electrochemical stability under high-voltage conditions (> 4 V) and substantial ionic conductivity (0.2 mS/cm), exceeding that of most oxide-type SSEs, as confirmed by ab initio molecular dynamics simulations. Furthermore, large-scale molecular dynamics simulations using a universal machine-learning interatomic potential demonstrate its ability to suppress surface degradation of mid-Ni NCM and prevent [PS4]3− decomposition in Li6PS5Cl, confirming its potential as a protective coating. These findings highlight the effectiveness of our computational screening strategy for coating-material discovery and underscore the potential of Li3Sc2(PO4)3 as a robust interfacial layer for stabilizing mid-Ni ASSBs.