Effect of Carbon Sources on Electrochemical Properties of LiFePO₄/C Composite Cathode

Abstract

Olivine-type LiFePO4/C composite cathode materials were synthesized by a solid-state reaction method in an inert atmosphere. Glycerin, glucose and citric acid were added as different conductive precursors before the formation of the crystalline phase. The effects of the carbon source on the properties of as-synthesized cathode materials were investigated. SEM and LSD measurement indicate that the particle size of the samples produced by glycerin and glucose distributed in a narrow way, while the particle of the sample produced by citric acid varied from submicron to several micron. The galvanostatically charge and discharge tests show that the material obtained by glucose gives a maximal specific discharge capacity of 142.5 mAh•g-1 in the first cycle. Further AC impedance measurements reveal the sample produced by glucose shows the lowest charge transfer resistance.