SiO2 nanofiber composite gel polymer electrolyte by in-situ polymerization for stable Li metal batteries

Gel polymer electrolytes (GPEs) are promising alternatives to liquid electrolytes applied in high-energy-density batteries. Here superior SiO2 nanofiber composite gel polymer electrolytes (SNCGPEs) are developed via in-situ ionic ring-opening polymerization of 1,3-dioxolane (DOL) monomers in SiO2 nanofiber membrane (PDOL-SiO2) for lithium metal batteries. The oxygen atoms of PDOL together with Si-O of SiO2 construct a more efficient channel for Li+ migration. Consequently, the lithium ion transference number (tLi+) and ionic conductivity (σ) at 30 °C of PDOL-SiO2 are 0.80 and 1.68 × 10−4 S/cm separately. PDOL-SiO2 manifests the electrochemical decomposition potentials of 4.90 V. At 0.5 mA/cm2, Li|PDOL-SiO2|Li cell shows a steady cycling performance for nearly 1400 h. LFP|PDOL-SiO2|Li battery can steadily cycle at 0.5 C with a capacity retention rate of 89% after 200 cycles. While cycling at 2 C, the capacity retention rate can maintain at 78% after 300 cycles. This contribution provides a innovative strategy for accelerating Li+ transportation via designing PDOL molecular chains throughout the SiO2 nanofiber framework, which is crucial for high-energy-density LMBs.