Li[Li_(0.2)Mn_(0.54)Ni_(0.13)Co_(0.13)]O_2-MoO_3 composite cathodes with low irreversible capacity loss for lithium ion batteries

摘要

To reduce the large first-cycle irreversible capacity loss of the Li-rich layered cathode material Li Li[Li_(0.2)Mn_(0.54)Ni_(0.13)Co_(0.13)]O_2, MoO_3 has been introduced by a simple high-energy ball milling process. The electrochemical properties of cathode material Li[Li_(0.2)Mn_(0.54)Ni_(0.13)Co_(0.13)]O_2 and the influences of different MoO_3 amount on its electrochemical properties are discussed in detail. The first charge-discharge dQ/dV curves suggest that the MoO_3 component provides additional sites for lithium ion insertion to compensate the lost Li sites caused by the simultaneous removal of Li~+ and O~(2-) during the activation of Li [Li_(0.2)Mn_(0.54)Ni_(0.13)Co_(0.13)]O_2. With increasing MoO_3 content from 0 wt.% to 20 wt.%, the first-cycle irreversible capacity loss of the composite decreases from 81.8 mAh g~(-1) to 1.2 mAh g~(-1). The composite with 5 wt% MoO_3 exhibits a good cycling stability with the discharge capacity of 242.5 mAh g~(-1) after 50 cycles, and the thickness of the MoO_3 coating layer on the surface of Li[Li_(0.2)Mn_(0.54)Ni_(0.13)Co_(0.13)]O_2 is about 3-4 nm. However, with the increase of the addition content of MoO_3, the cycling stability of the Li [Li_(0.2)Mn_(0.54)Ni_(0.13)Co_(0.13)]O_2-MoO_3 composite is decreased.