Improved Electrochemical Performance of a LiFePO4-Based Composite Cathode.

LiFePO4 was synthesized in the presence of high-surface area carbon-black. The carbon was added to the precursors before the formation of the crystalline phase. SEM micrographs confirmed that the addition of the fine carbon powder reduces the LiFePO4 grain size. The carbon is uniformly dispersed between the grains, ensuring a good electronic contact. Electrochemical tests showed that the material obtained by adding 10 wt. % of carbon gives enhanced performance in terms of improved practical capacity and charge/discharge rate. The specific capacity was seen to increase on increasing temperatures. The full capacity (170 mAh g-1) was delivered when discharging the cell at 80°C and C/10 rate. The cyclability of the material was tested at room temperature and C/2 rate. The cell was cycled for over 230 cycles with an average specific capacity of about 95 mAh g-1.