Nano-SiO₂@PMMA-doped composite polymer PVDF-HFP/PMMA/PEO electrolyte for lithium metal batteries

Polymer electrolytes have attracted widespread attention owing to their low cost and excellent processability. However, polymer electrolytes have yet been widely applied in commercial batteries due to their own drawbacks, such as weak mechanical properties and lower ionic conductivity. In this paper, poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) was blended with polyethylene oxide (PEO) and polymethyl methacrylate (PMMA) to build a novel polymer matrix, and SiO₂@PMMA was doped into blended polymer matrix to form a composite polymer electrolyte named CPE-(SiO₂@PMMA). The CPE-(SiO₂@PMMA) performs superior electrochemical performance, such as a favorable electrochemical stability window (4.7 V vs Li/Li⁺), decent ionic conductivity (8.54 × 10^–5 S cm⁻¹ at 60 ℃), and excellent interface stability. The lithium metal battery LiNi_0.8Co_0.1Mn_0.1O₂/CPE/Li was fabricated to build a high specific energy system, which performs excellent cycling and C-rate performance compared to others polymer electrolytes. Capacity retention of LiNi_0.8Co_0.1Mn_0.1O₂/Li cell with CPE-(SiO₂@PMMA) achieves 81.6% after 100 cycles, while CPE was broken with 100 cycles unfinished. All of the above favorable properties proved that PVDF-HFP/PMMA/PEO polymer matrix with SiO₂@PMMA doped is a promising electrolyte candidate for flexible lithium metal batteries.