Improved electrochemical performance of AlPO_4-coated LiMn_(1.5)Ni_(0.5)O_4 electrode for lithium-ion batteries

摘要

LiMn_(1.5)Ni_(0.5)O_4 materials coated with AIPO_4 are prepared by a sol-gel method with citric acid to improve their electrochemical performance; the physical and electrochemical properties are characterized by various analytical techniques. The coated AIPO_4 layer completely covers the surfaces of the LiMn_(1.5)Ni_(0.5)O_4 particles and the thickness of the coated layer is ～15nm. 1 wt.% AlPO_4-coated LiMn_(1.5)Ni_(0.5)O_4 has much lower surface and charge-transfer resistances and shows a higher lithium diffusion rate in comparison with the pristine sample. The modified material demonstrates dramatically enhanced electrochemical reversibility and stability under elevated temperature conditions. This is because the coated AIPO_4 layer reduces the contact area between the electrode and electrolyte and suppresses the formation of undesirable solid electrolyte interface films.