Boosting Electrochemical Performances of High-Voltage NCA/LTO Cells by Cathode Electrolyte Interface Nano Film Formation in Ionic Liquid Electrolyte

LiTFSI/EMITFSI ionic liquid was applied in this study as an electrolyte to enhance electrochemical performances of LiNi0.8 Co0.15 Al0.05 O2 /Li4 Ti5 O12 (NCA/LTO) batteries at a high charging cutoff voltage of 3.2 V. Li-EMITFSI electrolyte generated extremely stable and uniform cathode electrolyte interface (CEI) nano film on the cathode surface. This CEI film not only inhibited the continuous decomposition of electrolyte, but also stabilized the high operating voltage of NCA/LTO batteries, resulting in enhanced discharge gravimetric specific capacity (Cg) and cyclic stability of NCA/LTO batteries. With Li-EMITFSI electrolyte, the NCA/LTO batteries achieved higher C g of 172 mAhg –1 at 0.1 C and good capacity retention of 75% over 50 cycles at 1.4 ~ 3.2 V, compared to traditional commercial electrolytes.