A Ceramic-PVDF Composite Membrane with Modified Interfaces as an Ion-Conducting Electrolyte for Solid-State Lithium-Ion Batteries Operating at Room Temperature

Solid-state batteries hold great promise because of their safety and high projected energy density. However, the sizeable interfacial resistance between the electrodes and the electrolyte of such batteries is a significant bottleneck in the development of this technology. In this work, we develop a Li_6.4La₃Zr_1.4Ta_0.6O₁₂ (LLZTO) and polyvinylidene fluoride (PVDF) solid-state composite membrane characterized by high conductivity, tensile strength, and flexibility as well as low impedance if interfacially modified by a minute amount of liquid electrolyte. A solid-state lithium-ion battery using this electrolyte with LiFePO₄ and Li as electrodes delivers excellent rate capability and cycling stability at room temperature. In particular, the battery shows an initial discharge capacity of 155 mAh g⁻¹ and, after 100 cycles at 1C, of 145 mAh g⁻¹. Even at 4C, the discharge capacity is 96 mAh g⁻¹. Our study suggests that the interfacially modified LLZTO-PVDF membrane is a promising electrolyte for solid-state lithium-ion batteries.