LiFePO4/C nanocomposite synthesized by a novel carbothermal reduction method and its electrochemical performance

Abstract

LiFePO4/C cathode material was synthesized via a novel carbothermal reduction method, which combined the solution mixing of the raw materials with a two-step addition of carbon sources (sucrose and TWEEN 80). The sucrose was mainly used for reducing the Fe3+, and the TWEEN 80 was mainly used for carbon coating during the carbothermal reduction process, respectively. The structure, morphology, and composition of the as-prepared samples were characterized by X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, and transmission electron microscope (TEM). High resolution TEM analysis showed that a uniform carbon coating on the surfaces of the LiFePO4 particles was achieved, and the thickness of the carbon layer was about 3.5nm. As cathode material for the lithium ion battery, the as-prepared LiFePO4/C nanocomposite exhibits a high initial discharge capacity of 159.4mAhg−1 at 0.1C, and excellent capacity retention of ~98% at the 50th cycle. Cyclic voltammetry and electrochemical impedance spectroscopy also showed that the carbon coating resulting from the carbonization of TWEEN 80 can effectively reduce the impacts of polarization and charge transfer resistance during electrochemical processes.