Optimization of Synthesis Conditions for LiFePO4/C Nanocomposites by Dimethyl Sulfoxide Assisted Solution-Phase Method

Olivine-type LiFePO4 is synthesized by a solution-phase method, using dimethyl sulfoxide (DMSO) as a boiling point raiser and crystal growth inhibitor under ambient pressure and low temperature for a short time. The crystalline structure and morphology of the composites are characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. By analyzing the ratio of solvent to water, reactant concentration, reaction time, sintering time, and temperature we determine the optimal conditions for synthesizing LiFePO4/C nanocomposites, which are as follows: DMSO: water = 1: 1, reactant concentration 1 M, reaction time 2 h, mixed with a certain amount of glucose and sintered at 600 degrees C under a 5% H-2-95% N-2 atmosphere for 3 h. The LiFePO4/C thus prepared has a well developed olivine-type structure, small crystals, and a narrow size distribution. Electrochemical performance tests show that the special capacity of LiFePO4/C at discharge rates of 0.2 C and 1 C is 157.7 mAh g(-1) and 142.5 mAh g(-1), respectively. A special capacity of 126 mAh g(-1) at 5 C and 104 mAh g(-1) at 10 C is even achievable, with no significant capacity fading after 200 cycles, and the material delivers a good high-rate discharge property and excellent cycling performance. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.004204jes] All rights reserved.