High-Performance Sulfide All-Solid-State Batteries Enabled by High-Voltage Ni-Rich Cathode with a Conformal and Conductive Protective Layer

All-solid-state lithium batteries (ASSLBs), comprising a sulfide-based solid-state electrolyte and state-of-the-art cathode, hold great promise as the next generation of energy storage systems. Nevertheless, the persistent challenge lies in the poor interfacial stability between the state-of-the-art cathode and the sulfide-based electrolyte, necessitating the implementation of coatings to mitigate these reactions. In this study, we report on the atomic layer deposition (ALD) of a thin and homogeneous LiAl(PO3)4 protective layer onto LiNi0.88Co0.09Mn0.03O2 (NCM88) cathode material. The fast ionic transport nature, compatibility toward NCM88, and sulfide-based electrolyte of LiAl(PO3)4 accelerate the charge transfer and mitigate the interfacial deterioration. Utilizing Li6PS5Cl as the solid electrolyte, the LiAl(PO3)4-coated NCM88 enables the ASSLB to deliver superior rate capability (105.4 mAh g–1 at 3C) and excellent cycling performance. In particular, the ASSLB with a high loading of 20.1 mg cm–2 exhibits a reversible capacity of 4.25 mAh/cm2 and a capacity retention of 98.3% after 440 cycles. The results demonstrate that the application of the LiAl(PO3)4 protective layer via ALD provides more possibilities for the commercial application of ASSLBs.