Powdery oxychloride solid electrolytes enabling low-pressure all-solid-state batteries

Abstract

Recent years have seen rapid progress in all-solid-state lithium batteries (ASSLBs), yet interfacial mechanical stability—a fundamental challenge—remains critically unresolved. Current technologies typically require stack pressures of several to hundreds of megapascals to maintain intimate contact with electrodes, constituting a key design bottleneck in which the ideal pressure is <0.1 MPa. While organic polymer and inorganic viscoelastic electrolytes enable pressure-free operation due to their exceptional mechanical properties, they face inherent scientific and engineering limitations. In contrast, powdery solid electrolytes, despite inferior mechanical properties, exhibit exceptional compatibility with the established methods of preparing pouch-cell membranes. Thus, enhancing their mechanical properties for stable low-pressure cycling would significantly advance ASSLB development. Here, we design a soft powdery electrolyte, Li2Al0.9Cl3.3O0.7 (LACO), with an ultralow Young’s modulus (1.05 GPa). Its pressure-responsive deformability sustains contact with repeatedly expanding/contracting electrode active materials, enabling stable operation at low stack pressure (1 MPa). The all-solid-state cell coupling LACO with a high-nickel cathode achieves 80.29% capacity retention after 50 cycles at 25 °C under 1 MPa, surpassing all reported performance benchmarks for analogous powdery solid electrolytes.