Silica-reinforced functional composite polymer electrolyte with high electrochemical compatibility for solid-state lithium metal battery

Composite polymer-ceramic electrolytes (CPEs) are emerging as viable substitute providing high ionic conductivity, mechanical stability, and good safety for the progress of all-solid-state rechargeable batteries. Here, SiO₂ particles were generated from beach sands via a simple gelation method and embedded in to poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) to obtain precisely two types of the electrolytes namely, electrospun and solution casted. The 2.5 wt.% SiO₂-embedded CPEs generated by electrospinning and solution-casting exhibit best ionic conductivities being 3.6 × 10^–4 and 1.3 × 10^–4 S cm^-1 at 30 °C, respectively. The polarization voltage for the electrospun CPE was particularly low and showed an extremely stable voltage plateau up to 300 h demonstrating high electrochemical compatibility and immense cycling stability. Consequently, the all solid-state lithium metal battery (Li|CPE|LiFePO₄) using the electrospun CPE initially exhibits a discharge capacity of 142 mAh g^-1 at 0.1C-rate superior to that of the full cell using the solution-casted CPE.