Changes of LiCoO2 cathode material for lithium-ion battery during long cycling

Changes of the cathode material LiCoO2 of our homemade lithium-ion batteries with good uniformity, high capacity, and good cycling were investigated after 500, 1060, and 1600 cycles. The results show clearly that the cathode partially contributes to capacity fading of lithium-ion batteries due to two factors: (i) reactions between the electrolytes and LiCoO2, which produce a continuously growing surface layer on the cathode, leading to the increase of the charge transfer resistance, and (ii) the fading of LiCoO2 structure. These results provide valuable clues to extend the cycling life for lithium-ion batteries. (c) 2007 The Electrochemical Society.