0013-4651/2012/159(4)/A331/5/$28.00 © The Electrochemical Society 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 analyz-ing 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◦C under a 5 % H2–95 % N2 atmosphere for 3 h. The LiFePO4/C thus prepared has a well developed olivine-type structure, small crystals, and a narrow size distribution. Electro-chemical 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 signifi-cant capacity fading after 200 cycles, and the material delivers a good high-rate discharge property and excellent cycling performance