Fusion Bonding Technique for Solvent‐Free Fabrication of All‐Solid‐State Battery with Ultrathin Sulfide Electrolyte

For preparing next-generation sulfide all-solid-state batteries (ASSBs), the solvent-free manufacturing process has huge potential for the advantages of economic, thick electrode, and avoidance of organic solvents. However, the dominating solvent-free process is based on the fibrillation of polytetrafluoroethylene, suffering from poor mechanical property and electrochemical instability. Herein, a continuously solvent-free paradigm of fusion bonding technique is developed. A percolation network of thermoplastic polyamide (TPA) binder with low viscosity in viscous state is constructed with Li₆PS₅Cl (LPSC) by thermocompression (≤5 MPa), facilitating the formation of ultrathin LPSC film (≤25 µm). This composite sulfide film (CSF) exhibits excellent mechanical properties, ionic conductivity (2.1 mS cm^-1), and unique stress-dissipation to promote interface stabilization. Thick LiNi_0.83Co_0.11Mn_0.06O₂ cathode can be prepared by this solvent-free method and tightly adhered to CSF by interfacial fusion of TPA for integrated battery. This integrated ASSB shows high-energy-density feasibility (>2.5 mAh cm^-2 after 1400 cycles of 9200 h and run for more than 10 000 h), and energy density of 390 Wh kg^-1 and 1020 Wh L^-1. More specially, high-voltage bipolar cell (≥8.5 V) and bulk-type pouch cell (326 Wh kg^-1) are facilely assembled with good cycling performance. This work inspires commercialization of ASSBs by a solvent-free method and provides beneficial guiding for stable batteries.