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

Abstract 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 Li 6 PS 5 Cl (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 0.83 Co 0.11 Mn 0.06 O 2 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.