Enhancement of the electrochemical properties of PEO/PVdF/LiBOB solid polymer electrolytes with succinonitrile as a plasticizer for lithium metal batteries

The increasing demand for lithium-ion batteries (LIBs) highlights the critical importance of electrolyte design in ensuring both electrochemical performance and safety. Limitations associated with conventional liquid electrolytes have driven the development of solid-state electrolytes (SSEs) as a promising alternative to enhance operational safety and extend battery lifespan. This study focuses on the development and optimization of solid polymer electrolytes (SPEs) based on PEO/PVdF/LiBOB systems, with varying PEO:PVdF weight ratios (10:0, 9:1, 8:2, 7:3, 6:4) and succinonitrile (SN) concentrations (0–25%). Results show that a PEO:PVdF ratio of 7:3 achieves the best balance of mechanical strength, flexibility, and electrochemical performance. Increasing SN content reduces PEO crystallinity, leading to enhanced ionic conductivity–from 1.83 × 10−5 to 7.23 × 10−5 S/cm at 25 °C and from 1.09 × 10−4 to 1.79 × 10−4 S/cm at 60 °C–while maintaining high oxidative stability. When employed in Li||LFP cells, SPEs with 15 and 20% SN demonstrate stable cycling at 0.1C, achieving coulombic efficiencies above 99% and capacity retentions of 85.4% (165.3 mAh/g) and 90.8% (170.1 mAh/g) after 100 cycles, respectively. These findings underscore the potential of the developed SPEs for next-generation LIB applications.