Improving the Ionic Conductivity and Anode Interface Compatibility of LLZO/PVDF Composite Polymer Electrolytes by...

Utilizing aluminum-doped nano LLZO (Li_6.28La₃Zr₂Al_0.24O₁₂) as the ceramic filler, we synthesized and optimized LLZO/PVDF/LiClO₄ composite polymer electrolytes (CPEs) to achieve high ionic conductivity and good interfacial stability with metallic lithium. The research examines how the PVDF grade and the mass ratio of PVDF to LiClO₄ affect the ionic conductivity, lithium metal compatibility, and overall performance of CPEs. The CPE using Kynar PVDF 741 and a PVDF-to-LiClO₄ mass ratio of 2:1 emerged as superior, displaying a high ionic conductivity at room temperature (0.12 mS/cm), the lowest activation energy (0.247 eV), an extensive electrochemical stability window (approximately 4.9 V), and robust mechanical strength. In tests with lithium metal symmetric cells, the membrane facilitated over 1000 h of stable cycling at 0.1 mA cm^-2 and 0.1 mAh cm^-2. Furthermore, when integrated into full solid-state lithium-metal batteries with LiFePO₄ cathodes, it sustained more than 80% capacity retention across 500 charge/discharge cycles at a rate of 0.5 C with constantly high Coulombic efficiencies above 99.8%, underscoring its exceptional durability and efficiency. This research provides a practical framework and benchmarks for developing LLZO/PVDF-based CPEs with high ionic conductivity and enhanced stability against lithium metals.