Improving the cycling stability of LiCoO2 at 4.5 V through surface modification by Fe2O3 coating

Fe 2 O 3 nanoparticles are employed as a coating material to optimize the electrochemical performance of LiCoO 2 at high voltage. When the current rate is 1   C with the cutoff potential at 4.5   V, the 5   wt.% Fe 2 O 3 -coated LiCoO 2 delivers an initial capacity of 168.7   mAh   g −1 . More importantly, its capacity retention after 50 cycles reaches up to 92.6%, whereas the value for pristine LiCoO 2 is only 58.5%. The electrochemistry impedance spectroscopy analysis demonstrates that Fe 2 O 3 coating plays an important role in decreasing the charge transfer resistance of cell. Compared with the performance of the Fe 2 O 3 -mixed and Fe-doped LiCoO 2 samples, it is found that the role of Fe 2 O 3 coating is unique, which may change the characteristic of the surface of LiCoO 2 particles. This technique may provide an effective and convenient way for optimizing other electrode materials .