Effect of temperature on the structure and electrochemical performance of LiFePO4-based composite prepared by microwave chemical vapor deposition

LiFePO4-based composite cathode materials have been synthesized by a rapid microwave chemical vapor deposition method within 10 min at temperatures as low as 550 °C. The samples prepared at different temperatures have been characterized by X-ray diffraction, field emission scanning electron microscope, energy dispersive X-ray spectroscopy, high resolution transmission electron microscopy and electrochemical measurements in lithium cells. Results show that the composite prepared at 650 °C exhibits the best electrochemical properties, with the discharge capacity as high as 122.7 mAh g−1 at 5 C and the charge transfer resistance as low as 80 Ω. This can mainly be attributed to the formation of a three-dimensional conductive network provided by vapor-grown carbon fiber, pyrolytic carbon film and graphite. The synthesis and processing approach presented here offer a simple and high-efficiency method to obtain high-performance LiFePO4 cathode materials.

► The structure of the samples change regularly with the temperature. ► A three-dimensional conductive network is formed in one step via this method. ► The properties of the samples can be controlled by adjusting the temperature.