Covalent silica-PEO-LiTFSI hybrid solid electrolytes via sol-gel for Li-ion battery applications

Highlights: • Covalent hybrid solid electrolytes using LiTFSI were successfully obtained. • Arrehenius-like temperature dependence of ionic conductivity was observed. • Li⁺ mobility was assisted by segmental motions of PEG chains^. • GPTMS-GTED-LiTFSI (class II hybrid): σ = 2.6 10⁻⁵ S/cm⁻¹ at RT. • Li/SE/Li₄Ti₅O₁₂ cell present high rate performance after 500 cycles. - Abstract: Organic/inorganic hybrid membranes based on (3-glycidoxypropyl) trimethoxysilane (GPTMS) and ethylene glycol diglycidyl ether (EGDE), have been prepared by sol-gel method and organic polymerization as solid electrolytes for Li-ion batteries. Lithium bis(trifluoromethane)sulfonamide (LiTFSI) was used as Li salt. FTIR and Raman spectroscopies were used to confirm the hybrid structure formation and the interactions between Li ions and hybrid network. An Arrhenius-like temperature dependence of ionic conductivity was observed for solid hybrid electrolyte membranes, suggesting that the diffusion of charge carriers was assisted by the segmental motions of the organic network. The Li-ion transfer number was determined and correlated with their ionic conductivities. Maximum ionic conductivities for the solid hybrid electrolyte membrane with LiTFSI and a [Li⁺]/[O] = 0.10 (class II hybrid) of 2.6 × 10⁻⁵ S/cm was obtained at room temperature. A good value of electrochemical stability window (7 V) and an excellent high rate performance after 500 cycles make these hybrids materials a promising electrolyte candidate for all-solid-state lithium battery applications.