Polyvinylpyrrolidone (PVP) assisted synthesized nano-LiFePO4/C composite with enhanced low temperature performance

Although it is difficult to obtain LiFePO4/C particles with diameter less than 100 nm via solid state reaction, a simple, low cost and easily scaled-up method assisted by polyvinylpyrrolidone (PVP) was developed for mass production of nano-LiFePO4/C composites with average diameter of 80 nm in this study. Moreover, a homogeneous carbon layer (about 2 nm) was successfully coated on nano-LiFePO4 particle surface, which was difficult without PVP assistance. The combination of nano size and uniform carbon coating is important for the improvement of LiFePO4 electrochemical performance, especially the performance at low temperature. As a result, the obtained nano-LiFePO4/C composite possessed high discharge capacity of 160 mAh g−1 at 0.1 C. The capacity retention of the composite was kept over 120 mAh g−1 even at low temperature of −20 °C with the discharge rate of 0.1 C. In addition, the nano-LiFePO4/C composite showed excellent low temperature cycling performance with less than 3% capacity fading after 500 cycles at 0.6 C. The nano-sized cathode material via such simple method is beneficial for the application in electric vehicles as well as hybrid electric vehicles.