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

Abstract

The performance of the Li/LiNi 0.5 Mn 1.5 O 4 cells cycled to 5.0 V (vs. Li/Li + ) using 1.0 M LiPF 6 -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 LiNi 0.5 Mn 1.5 O 4 /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/LiNi 0.5 Mn 1.5 O 4 cells.

Review—An Unpredictable Hazard in Lithium-ion Batteries from Transition Metal Ions: Dissolution from Cathodes, Deposition on Anodes and Elimination Strategies

“…63 The P-O additives include tris(trimethylsilyl)phosphate, 64 tris(trimethylsilyl)phosphite, 11 dimethyl phenylphosphonite, 65 triethyl phosphite, 66 diethyl (thiophen-2-ylmethyl) phosphonate, 67 lithium difluorobis(oxalato) phosphate, 68 and LiPO 2 F 2. 69 The Si-O containing additives include dimethoxydiphenylsilane, 70 and those included in B-O and P-O containing electrolyte additives. F, Si and phenyl groups are beneficial to the robustness of the cathode interphase films because of their chemical and structural stability, such as tris (pentafluorophenyl) phosphine, 71,72 4-(trifluoromethyl)-Benzonitrile, 73 phenyl trifluoromethyl sulfide, 74 ethylene glycol bis (propionitrile) ether, 75 trimethylsilylcyclopentadiene, 76 diethyl Phenylphosphonite, 77 and N-Allyl-N,N-Bis(trimethylsilyl)amine.…”