Effect of synthesizing method on the properties of LiFePO4/C composite for rechargeable lithium-ion batteries

Olivine-type LiFePO 4 /C cathode materials are fabricated with FePO 4 powders that are pre-synthesized by two different processes from iron chloride solution. Process I is a modified precipitation method which is implemented by the pH control of a solution using NH 4 OH to form FePO 4 precipitates at room temperature. Process II is a conventional precipitation method, of which H 3 PO 4 (85%) solution is gradually added to a FeCl 3 solution during the process to maintain a designated mole ratio. The solution is subsequently aged at 90°C in a water bath until FePO 4 precipitates appear. In order to synthesize LiFePO 4 /C composites, each batch of FePO 4 powders is then mixed with pre-milled lithium carbonate and glucose (8 wt. %) as a carbon source in a ball-mill. The structural characteristics of both LiFePO 4 /C composites fabricated using iron phospates from two different routes have been examined employing XRD and SEM. The modified precipitation process is considered to be a relatively simple and effective process for the preparation of LiFePO 4 /C composites owing to their excellent electrochemical properties and rate capabilities.