Enhanced low temperature electrochemical performances of LiFePO4/C by surface modification with Ti3SiC2

Ti3SiC2-modified LiFePO4/C cathode materials are prepared via a suspension mixing method followed by heat-treatment at 400 °C. The galvanostatic electrochemical measurements indicate that 4 wt% Ti3SiC2-modified LiFePO4/C exhibits the best electrochemical performances in the voltage range of 2.0-4.2 V. The sample shows the highest initial discharge capacity of 116.0 mAh g−1 at the rate of 0.1 C at −20 °C. And it keeps a capacity retention of 97.0% at 1 C at −10 °C after 100 cycles, higher than 81.2% for LiFePO4/C at the same conditions. Furthermore, Ti3SiC2-modified LiFePO4/C samples deliver lower charge-transfer resistance and higher diffusion coefficient of Li+ compared with the pristine LiFePO4/C, especially the 4 wt% Ti3SiC2-modified LiFePO4/C sample exhibits the lowest charge-transfer resistance and highest diffusion coefficient of Li+ among all the four samples. The improved electrochemical performances can be attributed to the lower charge transfer resistance and higher diffusion coefficient of lithium ions resulted from the modification of appropriate amount of Ti3SiC2. Besides, a series of electrochemical results show that the performances of the electrodes with 10 wt% super-P are superior to those of the electrodes with 5 wt% super-P.