Magnetic studies of the carbothermal effect on LiFePO4

Abstract The effect of carbon coating on the properties of LiFePO 4 particles is studied from magnetic measurements. Magnetization experiments are an excellent tool to detect very low concentrations of iron‐based impurities (<1 ppm) which are poisoning the phospho‐olivine used as positive electrode material in rechargeable Li‐ion batteries. The results indicate that addition of 5% carbon withdraws traces of the Fe(III) phase such as Fe 2 P and/or Fe 2 O 3 . This carbothermal effect appears to be beneficial for long‐term application of LiFePO 4 materials in Li‐ion batteries. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)