A novel synthesis of Fe2P–LiFePO4 composites for Li-ion batteries

Fe2P–LiFePO4 composites were synthesized by a novel method consisting of co-precipitation modified with in situ polyacrylamide (PAM) formation. Simultaneous thermogravimetric-differential scanning calorimetric analysis indicated that the in situ PAM precursor exhibited a moderate continuous weight loss rather than a sharp mass loss process. The best Fe2P–LiFePO4 composite was obtained from 14 wt% in situ PAM precursor under a sintering temperature of 750 °C for 20 h, which delivered a discharge capacity of 131 mAh g−1 at a rate of C/5 and 110 mAh g−1 at 1 C and sustained 30 cycles with almost no capacity fading. The relatively good electrochemical performance originates mainly from the well-mixed gelation precursor and conductive Fe2P phase with better electronic conductivity. This novel method verified that the electrochemical performance was improved compared to the conventional LiFePO4 without in situ PAM. It can be anticipated that the same process should be readily extendable to other olivines, such as LiMnPO4 and LiCoPO4, and also to other phosphates.