Thermal Decomposition Assisted Construction of Nano-Li₃ N Sites Interface Layer Enabling Homogeneous Li Deposition

Lithium (Li) metal is a highly desirable anode for all-solid-state lithium-ion batteries (ASSLBs) due to its high theoretical capacity and being well matched with solid-state electrolytes. However, the practical applications of Li metal anode are hindered by the uneven Li metal plating/stripping behavior and poor contact between electrolyte and Li anode. Herein, a convenient and efficient strategy to construct the Li₃ N-based interlayer between solid poly(ethylene oxide) (PEO) electrolyte and Li anode is proposed by in situ thermal decomposition of 2,2'-azobisisobutyronitrile (AIBN) additive. The evolved Li₃ N nanoparticles are capable of combining LiF, cyano derivatives and PEO electrolyte to form a buffer layer of about 0.9 μm during the cell cycle, which can buffer Li⁺ concentration and homogenize Li deposition. The Li||Li symmetric cells with Li₃ N-based interlayer show excellent cycle stability at 0.2 mA cm^-2 , which is at least 4 times longer cycle life than that of PEO electrolytes without Li₃ N layer. This work provides a convenient strategy for designing interface engineering between solid-state polymer electrolyte and Li anode.