Li-ion Rechargeable Batteries Based on LiFePO_4: A comparative Study on the Nanostructured Composite Positive Electrode with Two Different Carbon Coating

摘要

Nanostructured Carbon-LiFePO_4 composite cathode materials were prepared with conventional solid-state route. The orthorhombic olivine structure without any impurity was obtained at 650°C. The average LiFePO_4 particle sizes were -80nm and were coated with residual carbon. The cyclic voltammograms showed only a pair of peaks corresponding to the anodic and cathodic reactions. The irreversible capacity loss in the first cycle was 5mAh/gm, and the Coulombic efficiency was 97%. The first discharge capacity was 157 mAh/g, equivalent to 93% of the theoretical capacity (Fe~(2+)/Fe~(3+) redox efficiency). Capacity retention after 80 cycles was ~98% and hence insignificant capacity fading.