Synergetic Effects of Al3+ Doping and Graphene Modification on the Electrochemical Performance of V2O5 Cathode Materials

A series of V2O5-based cathode materials that include V2O5 and Al0.14V2O5 nanoparticles, V2O5/reduced graphene oxide (RGO), and Al0.16V2O5/RGO nanocomposites are prepared by a simple soft chemical method. XRD and Raman scattering show that the Al ions reside in the interlayer space of the materials. These doping ions strengthen the VO bonds of the [VO5] unit and enhance the linkage of the [VO5] layers, which thus increases the structural stability of V2O5. SEM and TEM images show that the V2O5 nanoparticles construct a hybrid structure with RGO that enables fast electron transport in the electrode matrix. The electrochemical properties of the materials are studied by charge-discharge cycling, cyclic voltammetry, and electrochemical impedance spectroscopy. Of all the materials tested, the one that contained both Al ions and RGO (Al0.16V2O5/RGO) exhibited the highest discharge capacity, the best rate capability, and excellent capacity retention. The superior electrochemical performance is attributed to the synergetic effects of Al3+ doping and RGO modification, which not only increase the structural stability of the V2O5 lattice but also improve the electrochemical kinetics of the material.