Oligo(ethylene oxide)-functionalized trialkoxysilanes as novel electrolytes for high-voltage lithium-ion batteries

Oligo(ethylene oxide)-functionalized trialkoxysilanes were synthesized through hydrosilylation reaction by reacting trialkoxysilane with oligo(ethylene oxide) allyl methyl ether using PtO 2 as a catalyst. The physical properties of these compounds, such as viscosity, dielectric constant, and ionic conductivity, were characterized. Among them, [3-(2-(2-methoxyethoxy)ethoxy)-propyl]triethoxysilane (TESM2) exhibited a commercial viable ionic conductivity of 1.14 mS cm −1 and a wide electrochemical window of 5.2 V. A preliminary investigation was conducted by using TESM2 as an electrolyte solvent for high-voltage applications in lithium-ion batteries. Using 1 M LiPF 6 in TESM2 with 1 vol% vinyl carbonate as an electrolyte, LiCoO 2 /Li half-cell delivered a specific capacity of 153.9 mAh g −1 and 90 % capacity retention after 80 cycles (3.0–4.35 V, 28 mA g −1 ); Li 1.2 Ni 0.2 Mn 0.6 O 2 /Li 4 Ti 5 O 12 full cell exhibited the initial capacity of 161.3 mAh g −1 and 86 % capacity retention after 30 cycles (0.5–3.1 V, 18 mA g −1 ).