Electrochemical performance of LiFePO₄/(C+Fe₂P) composite cathode material synthesized by sol-gel method

Abstract

A LiFePO₄/(C+Fe₂P) composite cathode material was prepared by a sol-gel method using Fe(NO₃)₃·9H₂O, LiAc·H₂O, NH₄H₂PO₄ and citric acid as raw materials, and the physical properties and electrochemical performance of the composite cathode material were investigated by X-ray diffractometry (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and electrochemical tests. The Fe₂P content, morphology and electrochemical performance of LiFePO₄/(C+Fe₂P) composite depend on the calcination temperature. The optimized LiFePO₄/(C+Fe₂P) composite is prepared at 650 °C and the optimized composite exhibits sphere-like morphology with porous structure and Fe₂P content of about 3.2% (mass fraction). The discharge capacity of the optimized LiFePO₄/(C+Fe₂P) at 0.1C is 156 and 161 mA·h/g at 25 and 55 °C, respectively, and the corresponding capacity retentions are 96% after 30 cycles; while the capacity at 1C is 142 and 149 mA·h/g at 25 and 55 °C, respectively, and the capacity still remains 135 and 142 mA·h/g after 30 cycles at 25 and 55 °C, respectively.

Keywords

LiFePO₄/(C+Fe₂P) composite / sol-gel / sphere-like morphology / electrochemical performance

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