Well-crystallized and nanosized LiFePO4/C composite have been successfully synthesized by spray-drying under N2 atmosphere. The morphology, physical and electrochemical properties of the LiFePO4/C were tested and analyzed. The charge transfer resistances (Rct) and chemical diffusion coefficients of lithium ions (DLi+) in LiFePO4/C was systematically tested by EIS. The results show that the lithium ions diffusion coefficients obtained from EIS is 1.58×10-14 cm2·s-1. The assembled soft-packed cell with LiFePO4/C show better rate capability and cycling stability. The average capacity retention of LiFePO4/C soft-packed cell decreases to 100%, 98.9%, 96.5%, 92.4%, and 90.3% when current rate increases to 0.3, 0.5, 1, 2, and 3C, respectively. The capacity retention after 80 cycles is retained at more than 99%.

LiFePO4/C materials were synthesized by spray-drying using FePO4·2H2O, LiOH·H2O as raw materials, with three kinds of organic carbon sources: soluble starch, crystal sugar and glucose. The particle size, tap density, specific surface area, morphology, structure and electrochemical properties of the LiFePO4/C were tested and analyzed. The results indicate that the organic carbon source has no effect on the phase of LiFePO4, but has a remarkable influence on the tap density and specific surface area of LiFePO4. The LiFePO4/C synthesized with crystal sugar and glucose has higher tap density, smaller particle size and specific surface area. The LiFePO4/C synthesized with the glucose as the carbon source exhibited the most excellent electrochemical performance. The discharge capacities are 160.6, 148.5 and 114.1mAh/g respectively at 0.1C, 1C and 5C. Under low temperature 253K, the discharge capacity is 56.2% of that at 298K with 0.2C.

LiFePO4/C materials were synthesized by spray-drying using FePO4·2H2O, LiOH·H2O as raw materials, glucose as reducing agent and conductive additive. The morphology, structure and electrochemical properties of the LiFePO4/C were tested and analyzed. The morphology of the LiFePO4/C was biconcave and round looked similar to red blood cells, the tap density of the material up to 1.45g/cm3. The electrochemical performance of the material was excellent. The LiFePO4/C had an initial discharge specific capacity of 161.8mAh/g at rate of 0.1C and its specific capacities were 148.7, 120.9mAh/g at rates of 1, 5C rate, respectively. The discharge capacity remained at 95.8%, 81.7% after 500, 1000 cycles respectively at rate of 5C.

LiFePO4/C materials were synthesized by spray-drying method. The particle size of the LiFePO4/C was controlled by mechanical crushing or airflow crushing. The morphology, structure and electrochemical properties of the materials were characterized. The results show that: The smaller powder particle and better particle size distribution could be got using the two granularity control methods above. The special surface area of the material increased, the tap density decreased and the high rate performance deteriorated when the particle size of LiFePO4/C was controlled. After the particle size of LiFePO4/C is controlled the contacts of LiFePO4/C and carbon will deteriorate. The special capacity of the material decreases and the rate performance deteriorates, due to the stripping of carbon.