Effect of carbon precursor on electrochemical performance of LiFePO4-C nano composite synthesized by ultrasonic spray pyrolysis as cathode active material for Li ion battery

Abstract

In this study, LiFePO4-C (LFP-C) nanocomposites are synthesized by ultrasonic spray pyrolysis technique followed by short calcination step, to apply as cathode active material of Li ion battery. 5.0 g of either table sugar, citric acid, and 2.5, 5.0, 7.5, and 10 g of sucrose are added to separate 100 ml solutions containing 0.2 M of LiNO3, Fe(NO3)3, and H3PO4, as starting solution. A carbon-free sample and an uncalcinated sample are also prepared. X-ray diffraction analysis revealed that the olivine phase is obtained only after calcination. SEM images show spherical morphology with micron and submicron sizes and features, as well as change in morphology and agglomeration, especially when carbon content of LFP-C is not enough. Calcination and addition of carbon-leaving species to the starting solution is proved to be vital for acceptable electrochemical performance. LFP-C sample derived from addition of 5 g sucrose to 100 ml of the starting solution shows the best electrochemical performance in terms of capacity, cyclability, capacity retention, and rate performance.