Synthesis of carbonaceous/carbon-free nanofibers consisted of Co₃V₂O₈ nanocrystals for lithium-ion battery anode with ultralong cycle life

Transition metal vanadate material has attracted many battery researchers due to its layered type structure enabling facilitated lithium ion insertion/extraction and ability of vanadium to exist in multiple valence states. Cobalt vanadates have been receiving much research attention as superior anode candidates for use in lithium ion batteries with high specific capacity. Here, synthesis of 1-D nanofibers comprised of cobalt vanadate nanocrystals via electrospinning and subsequent thermal treatment in air atmosphere is reported. Heat treatment at various temperatures yielded Co₃V₂O₈ nanocrystals-embedded nanofibers with low and high carbon contents, and carbon-free hollow Co₃V₂O₈ nanofiber and their electrochemical properties were analyzed in detail. The discharge capacity of Co₃V₂O₈ nanocrystals-embedded nanofiber with high carbon content, that with low carbon content, and carbon-free hollow Co₃V₂O₈ nanofiber after 1200 cycles at a current density of 1 A g⁻¹ were 541, 735, and 302 mA h g⁻¹, respectively. Co₃V₂O₈ crystals-embedded nanofiber with low carbon content showed the best rate performance; 422 mA h g⁻¹ was achieved at a high current density of 10 A g⁻¹.