Effect of composite modes on structure and electrochemical performance of V2O5/PPy

The plate-like vanadium pentoxide (V2O5) was prepared by sol-gel method using V2O5 and H2O2 as raw materials. The composites of V2O5/polypyrrole (PPy) were synthesized by chemical oxidative polymerization. By using different methods of adding oxidant, different structure composites were obtained. The composites were investigated and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Brunner-Emmett-Teller method (BET). The conductivities of the composites were measured by a four-probe instrument. The results show that the composites obtained by using different methods of adding the oxidant have different structures and morphologies. When the oxidant is added first, polypyrrole intercalates into the sandwich of V2O5, leading to an increase in the d-spacing from 0.40806 nm for V2O5 to 0.41019 nm for the composites; when the pyrrole is added first, PPy deposits preferentially on the V2O5 particle surface, the d-spacing of the composite is not changed. The specific discharge capacity of the composites reaches 271.8 mAh/g at 0.1 C rate and voltage limits of 1.8 V~4.0 V, and still owned 225.4 mAh/g after 50 cycles.