The Effects of Carbon Nanotubes on the Electrochemical Performance of LiFePO4 Composite Cathode Materials for Li-ion Batteries

摘要

The multi-walled carbon nanotubes (MWNTs) have been added into LiFePO4 as composite electrodes of lithium battery by ball milling.The charge-discharge capacity,cyclic voltammetry,cycle life,alternating current impedance and discharge temperatures characteristic are investigated.It’s found that adding carbon nanotubes is advantageous to enhance the electrochemical performance of the LiFePO4 electrodes as a whole.The composite electrode with 10％ MWNTs adding quality exhibites a superior charge-discharge performance,and has initial charge capacities of 148 mAhg-1 and discharge capacities of 145 mAhg-1 respectively in the initial cycle at 0.1C chargedischarge rate.And the discharge capacity is 135 mAhg-1 at 0.5C rate and 124 mAhg-1 at 1.5C rate.The resistance values of LiFePO4/MWNTs composite electrode adding MWNTs quantity from 0％ to 20％ have a significant decrease when adding appropriate MWNTs.After 80 cycles,it has still 131mAh/g and the capacity holding is 90％ after 80 cycles.The discharge capacity of composite electrode increases with increasing environment temperatures from 0 to 60°C,and maximal value is 153 mAhg-1 in the temperature of 60°Cand has better performance of high temperature.