Electrochemical performance of WO2 modified LiFePO4/C cathode material for lithium-ion batteries

WO2 modified LiFePO4/C composites were prepared by sol–gel method. The structures and compositions of LiFePO4/C samples containing 0–5 wt% WO2 were analyzed by X-ray diffraction, Raman spectroscopy, scanning electron microscopy and transmission electron microscopy. The electrochemical performances were also characterized with charge–discharge test and cyclic voltammetry. The WO2 modified LiFePO4/C samples showed improved specific capability and low-temperature performance and reduced the polarization of the cathode significantly. Their apparent lithium ion diffusion coefficients were in the range of 3 × 10−11 to 8 × 10−11 cm2/s depending on the WO2 content. Among the investigated samples, the one with 3 wt% WO2 exhibited the best electrochemical performance. This can be mainly attributed to the improvement of electrochemical kinetics by the modifying with WO2.

Graphical abstractWO2 modified LiFePO4/C composites have been prepared by sol–gel method. The WO2 adding can increase the graphitization degree of the carbon coating to improving the electronic conductivity of LiFePO4/C composites and decreasing surface resistance. Through charge–discharge and cyclic voltammetry test showed that the WO2 adding can improve the specific capability, low-temperature behavior, lithium ion transport and reduce polarization of LiFePO4/C cathode material. So, WO2 modified LiFePO4/C composites exhibit good electrochemical performance.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► The WO2 modified LiFePO4/C composites were synthesized by sol–gel method. ► The existence of WO2 enhanced electrochemical performance of LiFePO4/C composites. ► WO2 and carbon form conductive coating layer on the LiFePO4/C surface together. ► The specific capacity is 157.8 mA h/g at 0.1 °C in the range of 2.5–4.2 V.