Polar–Nonpolar Synergistic Terpolymer Enables Ultra-Thin Sulfide-Based Membrane for High-Energy-Density and Low-Cost All-Solid-State Batteries

Abstract

For developing high-energy-density all-solid-state sulfide batteries (ASSBs), large-area sulfide electrolyte films produced via wet processes hold great potential. However, it is still a major obstacle in the wet process of sulfide membranes to find suitable polymer binders with excellent (electro)chemical compatibility and bonding properties. Here, we not only employ a terpolymer adhesive (Poly(ethylene-co-methyl acrylate-co-glycidyl methacrylate)) with polar–nonpolar synergistic effects to facilitate the wet-process manufacture of sulfide-based films, but also adopt a sulfide electrolyte prepared without expensive Li2S to reduce raw material costs. The sulfide-based electrolyte film (terP-SF) features an ultra-thin thickness (32 µm), favorable mechanical properties, and high ionic conductivity (1.32 mS/cm). For electrochemical performance, the terP-SF has fast ion transport kinetics and electrical insulation, which enables the NCM83//terP-SF//In-Li battery to deliver high-rate performance and long-term cycling stability (with a capacity retention rate of approximately 76.6% after 600 cycles). Furthermore, given the cost-effectiveness of scaled-up production of ASSB, a pouch cell configured as NCM83//terP-SF//Si with an energy density of 320.4 Wh/kg and volumetric energy of 710.7 Wh/L is successfully assembled. This work inspires the selection of binders in wet-process film formation and further guides the resolution of engineering and scientific challenges in the commercialization of high-energy-density and low-cost ASSBs.