Electrochemical characterization of AlPO_(4) coated LiNi_(1/3)Co_(1/3)Mn_(1/3)O_(2) cathode materials for high temperature lithium battery application

Aluminum phosphate(AlPO_(4))was used to modify the surface of LiNi_(1/3)Co_(1/3)Mn_(1/3)O_(2)(NCM)cathode material.The surface structure and electrochemical properties of the coated materials were investigated by X-ray photoelectron spectroscopy(XPS)and electrochemical impedance spectroscopy(EIS).The results confirm the formation of aluminum-containing solid solution on the surface of NCM particles.An aluminum phosphate coating blocks the Li+insertion-extraction process in cells charged at high rates at room temperature,increasing surface film resistance and decreasing discharge capacity.However,an aluminum phosphate aids the formation of a stable solid electrolyte interface film on NCM surface and stabilizes the Rct of cell as samples electrochemically cycled at 55℃.The electrochemical studies suggest that the initial columbic efficiency is significantly enhanced.An NCM sample coated with 1.0 wt%AlPO_(4) delivers a higher discharge capacity and shows excellent capacity retention ability.