Substrate-Enhanced Atomic Layer Deposition of Lithium Niobate on NMC Cathodes for Sulfide-Based All-Solid-State Batteries

Abstract Maintaining a stable interface between sulfide solid-state electrolytes and layered oxide cathodes remains a major challenge limiting the performance of all-solid-state batteries. Atomic layer deposition (ALD) of lithium niobate (LNO) on layered oxide cathodes is widely used to stabilize these interfaces, yet the early-stage growth of LNO remains poorly understood and strongly influenced by precursor chemistry. Here, we demonstrate substrate-enhanced ALD growth of LNO on single-crystal LiNi0.82Mn0.07Co0.11O2 (NMC) achieved using commercial lithium–niobium precursor chemistry, enabling complete surface encapsulation with conformal LNO coatings thinner than 8 nm. The resulting ultrathin LNO coatings increase the discharge capacity of Li6PS5Cl-NMC all-solid-state batteries by up to 20% while maintaining good rate capability. The improved electrochemical performance is attributed to the suppressed electrochemical decomposition of the Li6PS5Cl solid-state electrolyte during cycling, as evidenced by X-ray photoelectron spectroscopy, highlighting the importance of controlling the early-stage ALD growth of LNO.