Preparation of dense LiFePO4/C composite positive electrodes using spark-plasma-sintering process

Composite positive electrodes LiFePO 4 /C, applicable for rechargeable lithium-ion batteries cycled at high current density, were prepared using spark-plasma-sintering (SPS) technique. LiFePO 4 /C composite positive electrodes with carbon content of 20 wt.% was synthesized at 600 °C in the SPS process, and it was found that LiFePO 4 particles were covered with fine carbon particles and they formed agglomerates with the size of about 10 μm. It resulted in higher electrode density. Charge/discharge tests for the cell using LiFePO 4 /C composite positive electrodes showed superior cycle performance at the rates of 17–850 mAh g −1 (0.1–5 C) compared with the cell using the conventionally blended LiFePO 4 + C composite positive electrodes. The improvement of the cell performance was attributed to strong binding between LiFePO 4 and carbon powders. Consequently, the electrical network remained almost unchanged during electrochemical redox cycling, even at high current rates.