Surface engineering of nickel-rich single-crystal layered oxide cathode enables high-capacity and long cycle-life sulfide all-solid-state batteries

Sulfide all-solid-state lithium batteries (SASSLBs) with a single-crystal nickel-rich layered oxide cathode (LiNi_xCo_yMn_1-x-yO₂, x ​≥ ​0.8) are highly desirable for advanced power batteries owing to their excellent energy density and safety. Nevertheless, the cathode material's cracking issue and its severe interfacial problem with sulfide solid electrolytes have hindered the further development. This study proposes to employ surface modification engineering to produce B-NCM cathode materials coated with boride nanostructure stabilizer in situ by utilizing NCM encapsulated with residual lithium. This approach enhances the electrochemical performance of SASSLBs by effectively inhibiting electrochemical-mechanical degradation of the NCM cathode material on cycling and reducing deleterious side reactions with the solid sulfide electrolyte. The B-NCM/LPSCl/Gr SASSLBs demonstrate impressive cycling stability, retaining 84.19 ​% of its capacity after 500 cycles at 0.2 ​C, which represents a 30.13 ​% increase vs. NCM/LPSCl/Gr. It also exhibits a specific capacity of 170.4 mAh/g during its first discharge at 0.1 ​C. This work demonstrates an effective surface engineering strategy for enhancing capacity and cycle life, providing valuable insights into solving interfacial problems in SASSLBs.