Composite Polymer Electrolytes Based on Silicon Dioxide Nanoparticles for Lithium Metal Batteries

Composite polymer electrolytes (CPEs) formed of non‐ionically conducting inorganic fillers, such as SiO 2 nanoparticles, dispersed in a polymer matrix, are considered as promising candidates for solid‐state lithium metal batteries. By decreasing the crystallinity and lowering the T g of the polymer matrix, and inducing Lewis acid‐base interactions with lithium salts, inorganic fillers are reported for increasing ion transport in CPEs. Here, we disclose two types of composite polymer electrolytes (CPEs). The first CPE is a blend comprising lithium salt‐loaded poly(ethylene oxide) (PEO) as polymer matrix, bio‐based carbonated soybean oil (CSBO) as additive, and SiO 2 nanoparticles as inorganic component. The second CPE is a lithium salt‐loaded poly(hydroxyurethane) network prepared from α,ω‐diamino PEO and CSBO cross‐linker as polymer matrix entrapping SiO 2 nanoparticles. For both CPEs, the combined effect of the polymer component and SiO 2 facilitates the formation of electrolyte membranes with good flexibility and conductivity in the range of 10 −5 S cm −1 at 60°C. Moreover, the addition of inorganic fillers broadens oxidative potential limitations to > 4.8 and 4.4 V versus Li/Li + for CPEs based on linear PEO and PHU network polymers, respectively. Finally, the PEO‐CSBO‐SiO 2 ‐based LFP‐Li cell delivers an interesting initial discharge capacity of 140 mAh g −1 at 0.1C and 60°C.