Vinyl-Integrated In Situ Cross-Linked Composite Gel Electrolytes for Stable Lithium Metal Anodes

Achieving high energy/power densities, longer operating cycles, and ensured battery safety of rechargeable batteries become the primary mission to satisfy the requirements of electrified applications. Lithium metal batteries (LMBs) have been spotlighted because of the potential high energy density with the high theoretical specific capacity (3860 mA h g–1) and low redox potential. However, a safety hazard and the resulting short cycle life of batteries from uncontrollable dendritic growth of Li during the electrochemical cycles are a deterrence to their their commercialization. Here, we report in situ formation of a covalent network of composite gel polymer electrolytes (CPEs) integrating the vinyl-functionalized silica (VSNP) with polymer structures. A small addition (1 wt %) of VSNP into the CPE greatly enhances the mechanical modulus and Li-ion transference number of the CPE while maintaining high ionic conductivity. The VSNP-CPE assembled LiCoO2/Li and Li(Ni0.8Co0.1Mn0.1)O2/Li metal batteries show durable battery operation with a capacity retention of 88% after 500 cycles and 80% after 200 cycles, respectively, compared to liquid electrolytes, which show a gradual decay. The functionalized nanofiller with in situ formed CPE provides a feasible platform to improve mechanical properties and ionic conduction of CPEs as well as the processability of fabrication of high energy density LMBs.