N,N-diethyl-trimethylsilylamine as an Electrolyte Additive for Enhancing Electrochemical Performance of High Voltage Spinel Cathode

In this work, N, N-diethyl-trimethylsilylamine (EMSA) is used as an electrolyte additive for a 5 V-class high voltage LiNi0.5Mn1.5O4 cathode. In presence of 0.5 wt.% EMSA, Li/LiNi0.5Mn1.O-5(4) cell exhibits an attractive cycling performance compared to the cell without EMSA, improving the discharge capacity retention from 76.1 % to 84.9% after 500 cycles at 1 C and 25 degrees C, and from 52.4% to 94.8% after 100 cycles at 0.5 C and 55 degrees C. F-19 nuclear magnetic resonance (F-19 NMR), inductively coupled plasma atomic emission spectrometry (ICP-AES) and X-ray photoelectron spectroscopy (XPS) studies reveal that EMSA serves as a hydrofluoric acid scavenger to alleviate the dissolution of Mn and Ni ions from LiNi0.5Mn1.5O4 cathode and the concurrent decomposition of electrolyte. As a result, the stability of the cathode/electrolyte interface and cycling performance of LiNi0.5Mn1.5O4 are significantly improved. Moreover, the superior cycling performance of a Li/graphite cell with EMSA is also achieved because the surface film modified by EMSA allows facile charge transfer.