Acta Phys. -Chim. Sin. ›› 2011, Vol. 27 ›› Issue (04): 869-874.doi: 10.3866/PKU.WHXB20110416

• ELECTROCHEMISTRY AND NEW ENERGY • Previous Articles     Next Articles

Effects of Mixed Solvents on the High-Rate Performance of Li3V2(PO4)3/C Prepared by Sol-Gel Method

TANG Yan1, ZHONG Ben-He1, GUO Xiao-Dong1, LIU Heng2, ZHONG Yan-Jun1, NIE Xiang1, TANG Hong1   

  1. 1. College of Chemical Engineering, Sichuan University, Chengdu 610065, P. R. China;
    2. College of Materials Science and Engineering, Sichuan University, Chengdu 610065, P. R. China
  • Received:2011-01-03 Revised:2011-02-14 Published:2011-03-29
  • Contact: ZHONG Ben-He E-mail:Zhongbenhe@hotmail.com
  • Supported by:

    The project was supported by the National Science & Technology Pillar Program of China (2007BAQ01055).

Abstract:

A Li3V2(PO4)3/C composite cathode material was obtained by a sol-gel method using deionized water and organic solvents as mixed solvents. Ethanol, ethylene glycol, and 1,2-propylene glycol were used as the organic solvents and polyacrylic acid (PAA) was used as the chelating agent and carbon source. The structure, morphology, and electrochemical performance of the synthesized materials were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), charge-discharge tests, and cyclic voltammetry. XRD analysis showed that all the materials were well crystallized and that the addition of organic solvents did not affect the crystal structure of Li3V2(PO4)3. The results of galvanostatic cycling showed that the electrochemical performance of the products was improved by the addition of organic solvents. The material synthesized using 1,2-propylene glycol had the best electrochemical performance. It exhibited an initial discharge capacity of 132.89 mAh·g-1 at 0.1C (1C=150 mA·g-1) in the voltage range of 3.0-4.5 V. The initial discharge capacity was as high as 125.42 mAh·g-1 upon discharging at 10C, and it had a capacity retention of 95.79% after 700 cycles. These results indicate a good rate and cycling performance in the voltage range of 3.0-4.5 V; while in the voltage range of 3.0-4.8 V, it exhibits a bad rate performance. SEM images indicated that the sample prepared using the mixed solvents had a flake-like and needle-like shape, which facilitates the interface ion-transfer process and thus improves the overall electrochemical properties.

Key words: Lithium ion battery, Cathode material, Li3V2(PO4)3, Sol-gel method, Mixed solvents

MSC2000: 

  • O646