Enthalpy-Driven Molecular Engineering Enables High-Performance Quasi-Solid-State Electrolytes for Long Life Lithium...

The advancement of lithium metal batteries toward their theoretical energy density potential remains constrained by safety and performance issues inherent to liquid electrolytes. Quasi-solid-state electrolytes (QSSEs) based on poly-1,3-dioxolane (poly-DOL) represent a promising development, yet challenges in achieving satisfactory Coulombic efficiency and long-term stability have impeded their practical implementation. While lithium nitrate addition can enhance efficiency, its incorporation results in prohibitively slow polymerization rates spanning several months. In this work, high-polymerization-enthalpy 1,1,1-trifluoro-2,3-epoxypropane is introduced as a co-polymerization promoter, successfully integrating lithium nitrate into poly-DOL-based QSSEs. The resulting electrolyte demonstrates exceptional performance with 2.23 mS cm^-1 of ionic conductivity at 25 °C, a Coulombic efficiency of 99.34% in Li|Cu cells, and stable lithium metal interfaces sustained through 1300 h of symmetric cell cycling. This co-polymerization approach also suppresses poly-DOL crystallization, enabling Li|LiFePO₄ cells to maintain stability beyond 2000 cycles at 1C. Scale-up validation in a ≈1 Ah Li|NCM811 pouch cell achieves 94.4% capacity retention over 60 cycles. This strategy establishes a new pathway for developing high-performance, in situ polymerized quasi-solid-state batteries for practical energy storage applications.