A facile process for surface modification with lithium ion conducting material of Li₂TiF₆ for LiMn₂O₄ in lithium ion batteries

A facile method for surface coating with Li₂TiF₆ which has a high lithium-ion conductivity, on LiMn₂O₄ spinel cathode material for high performance lithium ion batteries. The surface coating is performed by using a co-precipitation method with Li₂CO₃ powder and H₂TiF₆ solution under room temperature and atmospheric pressure without special equipment. Total coating amount of Li₂TiF₆ is carefully controlled from 0 to 10 wt.% based on the active material of LiMn₂O₄. They are evaluated by a systematic combination of analyses comprising with XRD, SEM, TEM and ICP. It is found that the surface modification of Li₂TiF₆ is very beneficial to high cycle life and excellent rate capability by reducing surface failure and supporting lithium ions transportation on the surface. The best coating condition is found to have a high cycle life of 103 mAh g at the 100th cycle and a rate capability of 102.9 mAh g under 20 C. The detail electrochemical behaviors are investigated by AC impedance and galvanostatic charge and discharge test.