Effects of phenolic resin on the electrochemical performance of Li3V2(PO4)3/C cathode materials

As a kind of lithium-ion battery cathode material, monoclinic lithium vanadium phosphate/carbon Li3V2(PO4)(3)/C was synthesized by adopting phenolic resin as carbon source, both for reducing agent and coating material. The crystal structure and morphology of the samples were characterized through X-ray diffraction (XRD) and scanning electron microscope (SEM). Galvanostatic charge-discharging experiments and electrochemical impedance spectrum (EIS) were utilized to determine the electrochemical insertion properties of the samples. XRD data revealed that phenolic resin does not change the crystal structure of Li3V2(PO4)(3)/C. Furthermore, the morphology of grains and the electronic conductivity of Li3V2(PO4)(3)/C were improved. Galvanostatic charge-discharging and EIS results showed that the optimal electrochemical properties and the minimum charge-transfer resistance of Li3V2(PO4)(3)/C can be reached when added by 5 wt.% of redundant carbon (except the carbon needed to reduce V5+ to V3+). The initial discharge capacity is 128.4 mAh g(-1) at 0.2 C rate and 101.2 mAh g(-1) at 5 C in the voltage range of 3.0 similar to 4.3 V.