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As recently explored lithium-ion battery (LIB) anode materials, transition metal vanadates have attracted much attention due to their excellent electrochemical performance. In this work, we successfully synthesized solid Co3V2O8 microspheres (sCVO MSs) via a facile and controllable hydrothermal reaction, and the magical formation mechanism was also revealed by the different morphologies of sCVO MSs at different reaction times. When tested as LIB anode materials, sCVO MSs showed superior reversible capacities (∼780 mA h g−1 after 250 cycles at 1000 mA g−1 and as high as 550 mA h g−1 even after 400 cycles at 5000 mA g−1) and excellent rate performance (a capacity of ∼500 mA h g−1 at a current density of 2000 mA g−1). It is accordingly demonstrated that uniform sCVO MSs have great potential to be used as high-performance LIB anodes. [ABSTRACT FROM AUTHOR]

Transition metal vanadates have attracted much attention for high capacity anodes of lithium ion batteries (LIBs). However, they have obvious drawbacks (short cycle-lives and low rate performance) because of the intrinsically low electronic conductivity and serious volume variation during Li-ion desorption and insertion. In particular, pure Co3V2O8 micro-pencils (pCVO MPs) have a stable and regular crystal structure, large tap density and uniform grain size, but, unfortunately, they have not exhibited expected electrochemical performance. Herein, we report the successful preparation of reduced graphene oxide coated Co3V2O8 micro-pencils (rGO@CVO MPs) through a facile approach combining hydrothermal synthesis with thermal reduction. When tested as anodes for LIBs, rGO@CVO MPs exhibit superior electrochemical performance compared to that of pure Co3V2O8 micro-pencils (pCVO MPs). The anodes of rGO@CVO MPs show a high reversible capacity of 760 mA h g−1 over 200 cycles at 200 mA g−1, and 500 mA h g−1 can remain after 500 cycles at 1000 mA g−1, with an increase in 200 mA h g−1 in contrast to the pCVO MPs. It is consequently demonstrated that the composite material (rGO@CVO MPs) is a promising anode material for LIBs. [ABSTRACT FROM AUTHOR]