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

Novel ε-Cu 0.95 V 2 O 5 hollow microspheres assembled by single-crystalline nanoribbons can be easily synthesized directly from a hydrothermal reaction between V(IV)O(acac) 2 and Cu(NO 3 ) 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 ε-Cu 0.95 V 2 O 5 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 ε-Cu 0.95 V 2 O 5 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 α-CuV 2 O 6 nanograins are obtained by calcining the micro-nanostructured ε-Cu 0.95 V 2 O 5 precursor. The post-treated α-CuV 2 O 6 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 .