Acta Phys. -Chim. Sin. ›› 2011, Vol. 27 ›› Issue (09): 2123-2128.doi: 10.3866/PKU.WHXB20110902

• ELECTROCHEMISTRY AND NEW ENERGY • Previous Articles     Next Articles

Sol-Gel Synthesis and Electrochemical Performance of Porous LiMnPO4/MWCNT Composites

NIE Ping, SHEN Lai-Fa, CHEN Lin, SU Xiao-Fei, ZHANG Xiao-Gang, LI Hong-Sen   

  1. 1. College of Chemistry and Chemical Engineering, Xinjiang University, Urumqi 830046, P. R. China;
    2. College of Material Science and Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, P. R. China
  • Received:2011-05-23 Revised:2011-06-20 Published:2011-08-26
  • Contact: ZHANG Xiao-Gang
  • Supported by:

    The project was supported by the National Key Basic Research Program of China (973) (2007CB209703), National Natural Science Foundation of China (20873064), Jiangsu Innovation Program for Graduate Education, China (CXZZ11_0204) and Outstanding Doctoral Dissertation in NUAA, China (BCXJ11-10).

Abstract: Porous LiMnPO4 and LiMnPO4/MWCNT (multi-walled carbon nanotube) composites were prepared using a citric acid assisted sol-gel method. X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), nitrogen adsorption-desorption isotherms (BET), and transmission electron microscopy (TEM) were performed to characterize their morphologies and structures. The results indicated that fine-sized, well-crystallized olivine LiMnPO4 was synthesized. The interlaced carbon nanotube networks were intimately embedded and incorporated into the porous LiMnPO4 particle to form highlyconductive three-dimensional (3D) networks. The LiMnPO4 particle and LiMnPO4/MWCNT composite had rich hierarchical pores. A detailed analysis showed that the average pore size was in the mesoporous range and specific surface areas of 73.7 and 69.9 m2·g-1 were obtained, respectively. Compared with the LiMnPO4 particle the LiMnPO4/MWCNT composite exhibited much higher specific capacity. When discharged at a rate of 0.05C and 2C the capacities were 108.8 and 33.2 mAh·g-1, respectively. The MWCNT effectively improved the electronic conductivity of the hybrid materials as shown by electrochemical impedance spectroscopy (EIS). The improved electrochemical performance of the LiMnPO4/MWCNT electrode is attributed to the enhanced electrical conductivity caused by the tighter binding of the carbon nanotubes with the LiMnPO4 primary particles as well as by the interconnected open pores with a high surface area.

Key words: Lithium manganese phosphate, Carbon nanotube, Porous material, Sol-gel method, Lithium ion battery