Scalable fabrication of Solvent‐Free composite solid electrolyte by a continuous Thermal-Extrusion process

Composite solid-state electrolytes (CSEs) are regarded as a promising alternative for the next‐generation lithium-ion batteries because they integrate the advantages of inorganic electrolytes and organic electrolytes. However, there are two issues faced by current CSEs: 1) a green and feasible approach to prepare CSEs in large scales is desired; and 2) the trace solvents, remaining from the preparation processes, lead to some serious concerns, such as safety hazard issues, electrolyte–electrode interfacial issues, and reduced durability of batteries. Here, a continuous thermal-extrusion process is presented to realize the large-scale fabrication of solvent‐free CSE. A 38.7-meter CSE membrane was prepared as a demonstration in this study. Thanks to the elimination of residual solvents, the electrolyte membrane exhibited a high tensile strength of 3.85 MPa, satisfactory lithium transference number (0.495), and excellent electrochemical stability (5.15 V). Excellent long-term stability was demonstrated by operating the symmetric lithium cell at a stable current density of 0.1 mA cm−2 for over 3700 h. Solvent-free CSE lithium metal batteries showed a discharge capacity of 155.7 – 25.17 mAh g−1 at 0.1 – 2.0C, and the discharge capacity remained 78.1% after testing for 380cycles.