Novel ε-Cu0.95V2O5 hollow microspheres and α-CuV2O6 nanograins: Facile synthesis and application in lithium-ion batteries

Novel epsilon-Cu0.95V2O5 hollow microspheres assembled by single-crystalline nanoribbons can be easily synthesized directly from a hydrothermal reaction between V(IV)O(acac)(2) and Cu(NO3)(2) in a solution containing a proper amount of polymer polyvinyl pyrrolidone (PVP, K30). A possible growth mechanism has been proposed. Electrochemical measurements demonstrate that the as-prepared epsilon-Cu0.95V2O5 superstructures display a reversible capacity of 304 mAh g(-1), and could sustain respectable rate capability. By reinvestigating the cooperative displacement/intercalation (CDI) mechanism of epsilon-Cu0.95V2O5 using cyclic voltammetry (CV), ex situ XRD, and ex situ SEM-EDS techniques, it is found that the copper dissolution problem, which leads to poor capacity retention of cells operating on Li-driven Cu extrusion-insertion process, has not been well tackled due to its superstructure collapse. Rational electrode configuration design is urgently needed. In addition, single-crystalline alpha-CuV2O6 nanograins are obtained by calcining the micro-nanostructured epsilon-Cu0.95V2O5 precursor. The post-treated alpha-CuV2O6 exhibits high discharge capacity of 507 mAh g(-1) at 20 mA g(-1) and 390 mAh g(-1) at 80 mA g(-1), indicating it is a promising cathode candidate for long-term and high-rate lithium primary batteries. (C) 2013 Elsevier B.V. All rights reserved.