High-rate and durable sulfide-based all-solid-state lithium battery with in situ Li₂O buffering

Sulfide electrolytes (SEs)-based all-solid-state lithium batteries (ASSLBs) are advantageous over traditional lithium-ion batteries (LIBs) because of high energy density and safety. Unfortunately, the commercialization of SEs-based ASSLBs is presently hindered by interfacial instability between SEs and active materials, sluggish dynamics and poor cycling performance. Here we report, for the first time, a stable and conductive Li₂O buffering coating for Ni-rich LiNi_0.8Co_0.1Mn_0.1O₂ (NCM811) in ASSLBs using SEs of Li₆PS₅Cl via a facile one-step sintering. We show using judiciously combined computation and experiment that Li₂O buffering improves the stability of NCM811 and significantly boosts transfer of Li⁺. Via tuning the thickness of the Li₂O buffer, we demonstrate the high initial discharge capacity of 189.66 mAh g ^{− 1} (0.1C) and rate capability of 61.71 mAh g ^{− 1} (3C), together with outstanding long-term cycling performance of ∼ 2600 cycles at 1C with capacity retention of 81.47%, and Coulombic efficiency of 99.9%. We conclude that conductive Li₂O buffering can be used to obviate interfacial instability between SEs and active materials and to boost dynamics and cycling performance. Findings will be of immediate benefit to a range of researchers in design for high-performance ASSLBs for practical application and commercialization. © 2022 Elsevier B.V.