Effect of anions on the copper vanadate structure during ion-exchange and its lithium storage performance

Copper vanadate materials have a higher gravimetric capacity and energy density than those of the traditional vanadium oxide or vanadate electrodes because of the multistep oxidation-reduction reactions. This work presents the synthesis of nano-structured copper vanadates using ion-exchange reaction of sodium vanadate nanowire arrays in an aqueous solution, containing copper acetate or copper nitrate. The morphology, crystal structure, composition and lithium-storage performance of the materials are measured and characterized thoroughly. Due to the dissolution effect of the acetate anion on the sodium vanadate nanowire arrays, copper vanadate spheres composed of nanosheets are produced. By contrast, after the ion-exchange reaction in the copper nitrate solution, the sample maintains its original nanowire arrays structure. The copper vanadate nanowire arrays synthesized in copper nitrate solution for 48 h followed with calcination at 300 °C for 2 h exhibit a remarkably high storage capacity of up to 997.76 mAh g−1 in 3–0.01 V versus Li/Li+, thus showing a great potential for application in lithium-ion batteries.