Dimethoxydiphenylsilane (DDS) as an Electrolyte Additive for High Voltage Li-ion Batteries

The performance of the Li/LiNi0.5Mn1.5O4 cells cycled to 5.0 V (vs. Li/Li+) using 1.0 M LiPF6-EC/DMC (1/1, v/v) with and without dimethoxydiphenylsilane (DDS) at 25°C has been investigated. Cells with 1% DDS added deliver slightly lower initial discharge capacity than the cells with baseline electrolyte, 115.3 vs. 120.9 mAh g−1. Electrochemical methods and ex-situ analytical techniques, including TGA and SEM, are employed to conduct the interfacial chemistry of LiNi0.5Mn1.5O4/electrolyte to better understand the improved electrochemical performances of the cells with introduction of DDS. The results indicate that DDS can be electro-oxidized and participates in the formation of the surface layer on cathode electrode, which prevents electrolyte from further decomposition and promotes Li+ conduction of the cathode/electrolyte interphase, thus improves the electrochemical performances of Li/LiNi0.5Mn1.5O4 cells.