Comparison of Electrochemical and Surface Properties of Bare and TiO2-Coated LiNi0.8Co0.2 O 2 Electrodes

The electrochemical behaviors of native and TiO 2 -coated LiNi 0.8 Co 0.2 O 2 electrodes which were cycled in different potential regions (i.e., 3.0-4.3 and 3.0-4.6 V) were investigated by the powder microelectrode technique. The surface species on the electrodes were also studied by Fourier transform infrared and temperature-programmed desorption-mass spectroscopy (TPD-MS) techniques. Different oxidation products were formed on the bare and coated electrodes, respectively. The results indicated that the improved cyclic stability of the coated electrodes may be attributed to formation of different surface oxide films through an electro-oxidation mechanism of the solvents on the electrodes. A possible electro-oxidation mechanism has been proposed based on the results.