Articles
  • Influence of calcined temperatures on the microstructure and electrochemical properties of LiFePO4/C nano-particles with a core-shell structure and It's thermal stability study
  • Peng-zhao Gaoa*, Bing Yana, Ling Wanga, Wei Liub*, Wei-Wei Gonga and Xiao-pan Liua
  • a College of Materials Science and Engineering, Hunan University, Changsha 410082, China b School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China
Abstract
Influence of calcined temperatures on the microstructure and electrochemical properties of LiFePO4/C nano-particles as well as it's thermal stability were studied using HRTEM, XRD, electrochemical workstation and TGA. The results indicated that when calcined at 973 K, the LiFePO4/C nano-particles consisted of a well-crystalline LiFePO4 core with size of 58.6-80.1 nm and an amorphous carbon shell with thickness of 2 nm. With the increase of calcined temperature, the electrochemical properties of LiFePO4/C materials increased first and then decreased, it reached maximum when temperature equaled to 973 K. The initial discharge capacity of the sample was 142 mAh/g, the discharge capacity of it maintained 132 mAh/g with capacity retention of 93.0% after 40 cycles. The decomposition reaction of LiFePO4/C material calcined at 973 K occurred at 938.38- 1194.52 K under 10 K • min−1 in N2 atmosphere and corresponded to approximately 5.8% of the total weight. The decomposition mechanism of it consisted of three stages: the first stage was controlled by gas diffusion in carbon shell; the second stage was controlled by chemical reaction and gas diffusion; the third stage was controlled by chemical reaction.

Keywords: LiFePO4/C nano-particles, Microstructure, Electrochemical properties, Thermal stability.

This Article

  • 2015; 16(1): 137-145

    Published on Feb 28, 2015