Synthesis and Electrochemical Performance in Modified Electrolyte of Microspheres LiNi0.8Co0.1Mn0.1O2

Microsphere high-nickel ternary LiNi0.8Mn0.1Co0.1O2(LNCM811) cathode was syntheisized by the chemical co-precipitation method with a simple solid-state reaction, and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscope (TEM). Electrochemical behavior of LNCM811 was investigated by electrochemical impedance spectroscopy (EIS), combining with cyclic voltammogram (CV) and charge/discharge test in the 1 mol.L-1 LiPF6EC:EMC electrolyte with 2% (w/w) ethylene sulfate (DTD) and 1% (w/w) methylene methanedisulfonate (MMDS) additives either singly or in combination at room temperature of 25 degrees C or elevated temperature of 60 degrees C. It is found that compared with 1% MMDS, the 2% DTD can slightly improve the initial coulombic efficiency and initial discharge capacity of the LNCM811 at room temperature. Both 2% DTD and 1% MMDS can improve the long cycling performance of LNCM811, and the 2% DTD additive is better than the 1% MMDS additive at 25 degrees C, however, the 1% MMDS is better than the 2% DTD at elevated temperature of 60 degrees C. After long cycles, the LNCM811 cathode has the best cycling performance with additive combination 2% DTD+1% MMDS. EIS results reveal that the additive blend of 2% DTD+1% MMDS can drastically lower the kinetics impedances.