Study on Electrochemical Performance of Carbon-coated LiFePO4 as Cathode Material for Lithium Ion Batteries

Carbon-coated LiFePO4 as cathode material was synthesized by a sol-gel process. A solution of FeC2O4.2H(2)O and citric acid dissolved in distilled water was mixed with a solution consisted of Li2CO3, NH4H2PO4, and distilled water by a magnetic stirrer for 2.5 h at 80 degrees C. After drying at 80 degrees C for 24 h and heating process at 320 degrees C for 10 h, the obtained precursor was heated under an inert atmosphere at varied temperatures: 600, 700, and 800 degrees C and varied heating times: namely 6, 8, and 10 h. The obtained phase was observed by analyzing XRD diffraction patterns. The morphology and the particle size of the obtained powders were analyzed by SEM. Cathode materials LiFePO4 were assembled into a coin cell using metallic lithium as a counter electrode and 1 M LiPF6 in a solution of EC:DEC as the electrolyte. The redox reaction of cathode material was characterized by mean Cyclic Voltammetry with a scan rate of 0.1 mV/s in the potential range of 2.5 - 4.2 V. The capacity and rate capability of cathode materials were observed by conducting a Charge-Discharge test with varied C-rates.