Enhancement of the high-voltage electrochemical performance of an LiNi0.5Co0.2Mn0.3O2 cathode via WO3 coating

Inspired by the WO 3 transition metal semiconductor, a simple liquid phase WO 3 coating strategy is introduced to improve the surface stability of LiNi 0.5 Co 0.2 Mn 0.3 O 2 . The electrochemical performance of WO 3 -coated LiNi 0.5 Co 0.2 Mn 0.3 O 2 is improved at both a high cut-off voltage (4.5 V) and high temperature (50 °C). With the WO 3 (0.6 wt%) coating amount optimized, the material capacity retention is maintained at 138 mAh g −1 and 170.9 mAh g −1 at 25 °C and 50 °C after 200 cycles compared with 107.8 mAh g −1 and 143.9 mAh g −1 , respectively, for pristine NCM523. The WO 3 -coated sample also exhibits a better rate capability, maintaining 126 mAh g −1 at 25 °C in the voltage range of 3–4.5 V at the current density of 5 C. The enhanced properties of the WO 3 -coated LiNi 0.5 Co 0.2 Mn 0.3 O 2 due to the WO 3 coating layer result from the interface that prevents immediate contact between the electrolyte and the active material as well as the lower polarization and electrochemical resistance of the battery. SEM, TEM, XPS and EIS further reveal these improved electrochemical performances, which indicate the success of the approach for regenerating NCM523.