Hybrid Dynamic Covalent Network as a Protective Layer and Solid-State Electrolyte for Stable Lithium-Metal Batteries

Lithium (Li) metal is a highly promising anode material for next-generation high-energy-density batteries, while Li dendrite growth and the unstable solid electrolyte interphase layer inhibit its commercialization. Herein, a chemically grafted hybrid dynamic network (CHDN) is rationally designed and synthesized by the 4,4′-thiobisbenzenamine cross-linked poly(poly(ethylene glycol) methyl ether methacrylate-r-glycidyl methacrylate) and (3-glycidyloxypropyl) trimethoxysilane-functionalized SiO2 nanoparticles, which is utilized as a protective layer and hybrid solid-state electrolyte (HSE) for stable Li-metal batteries. The presence of a dynamic exchangeable disulfide affords self-heability and recyclability, and the chemical attachment between SiO2 nanoparticles and the polymer matrix enables the homogeneous distribution of inorganic fillers and mechanical robustness. With integrated flexibility, fast segmental dynamics, and autonomous adaptability, the as-prepared CHDN-based protective layer enables superior electrochemical performance in half cells and full cells (capacity retention of 83.7% over 400 cycles for the CHDN@Li/LiFePO4 cell at 1 C). Furthermore, benefiting from intimate electrode/electrolyte interfacial contact, CHDN-based solid-state cells deliver excellent electrochemical performance (capacity retention of 89.5% over 500 cycles for the Li/HSE/LiFePO4 cell at 0.5 C). In addition, the Li/HSE/LiFePO4 pouch cell exhibits superior safety, even exposing various physical damage conditions. This work thereby provides a fresh insight into a rational design principle for dynamic network-based protective layers and solid-state electrolytes for battery applications.