Sm2O3 coating to suppress electrode/electrolyte side reactions of single crystal materials at high voltage

Abstract

Coating modification of single-crystal materials was studied to improve the electrochemical properties of the materials by suppressing the electrode/electrolyte side reactions. The commercial LiNi0·6Co0·1Mn0·3O2 was used as the base material and Sm2O3 coating was applied on its surface. The Sm2O3-coated NCM613 single-crystal material was synthesized. The structure and morphology of the electrode materials were characterized by XRD, FESEM, and TEM. The results showed that Sm2O3 was successfully coated on the surface of the particles without damaging the original structure of the material. Meanwhile, the lithium ions diffusion kinetics of the material was analyzed by cyclic voltammetry. The results show that the coated cathode material has a more excellent lithium ions diffusion coefficient, which provides a kinetic basis for charging and discharging the battery at high voltage. At 25 °C, 3.0−4.5 V, and 1 C current density, the capacity retention of the coated cathode material after 100 cycles was 87.5% (182.8−159.9 mAh g−1), which was much higher than that of the original material at 77% (177−136.3 mAh g−1). SEM and other characterizations of the electrode sheets after cycling showed that the Sm2O3 coating layer effectively prevented the direct contact between the cathode material and the electrolyte, which played a positive role in suppressing the occurrence of side reactions, and inhibits the formation of microcracks during the cycling process. In general, this method contributed to the stability of the electrode/electrolyte interface and electrochemical performance.