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

Novel ε-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 ε-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 ε-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 α-CuV2O6 nanograins are obtained by calcining the micro-nanostructured ε-Cu0.95V2O5 precursor. The post-treated α-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.

Figure optionsDownload as PowerPoint slideHighlights
► Self-assembled micro-nano ε-Cu0.95V2O5 is easily fabricated by solution method.
► ε-Cu0.95V2O5 superstructures reversibly react with 2.75 Li.
► Copper immobilization is highly desired indicated by ex situ XRD investigations.
► Calcinating the prepared ε-Cu0.95V2O5 forms single-crystalline α-CuV2O6 nanograins.
► The calcined α-CuV2O6 shows broad prospects in long-term and high-rate primary LBs.