A Novel Aminoalkylsilane Compound with Oligo(ethylene oxide) Units as Effective Additive for Improving Cyclability of Lithium-ion Batteries

A new aminoalkylsilane compound, ((2-(2-(N,N-dimethylamino)ethoxy)ethoxy) methyl)trimethylsilane (TMSC1N2) based on the oligo(ethylene oxide) chain end-capped with organosilicon functional group and alkylamine group on each end, was introduced as an electrolyte additive for lithium-ion batteries. Electrochemical performances of different volume ratios of TMSC1N2 in the baseline electrolyte were conducted through cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic charge/discharge tests of lithium-ion batteries. With adding 5 vol.% TMSC1N2 to the baseline electrolyte (1 mol/L LiPF6 in ethylene carbonate and diethyl carbonate (EC:DEC = 1:1, in volume)), the capacity retention of LiFePO4/Li cells could be significantly improved from 74.7% to 90.8% after 130 cycles. Furthermore, TMSC1N2 showed good compatibility with graphite electrode and would not deteriorate the electrochemical performance of graphite/Li anode cells. These data suggested that TMSC1N2 could be utilized as an effective additive for lithium-ion batteries.