Controllable Synthesis and “Fast-charging” Mechanism of Hollow-Micropencil Co3V2O8 from Perspective of Ion Diffusion in Crystal Structure

Co₃V₂O₈ as a bimetallic oxide with “fast-charging” capacity presents some potential advantages, comprising decent theoretical specific capacity, favorable crystal structure, and intrinsic safety. Presently, although extensive research of Co₃V₂O₈ as an anode material are reported, the formed Co° from Co₃V₂O₈ after the initial discharging is not oxidized to CoO during the charging process, and the ion diffusion mechanism are not well clarified. The lithium-storage process of Co₃V₂O₈ and the diffusion mechanism of lithium ion in Co₃V₂O₈ are studied in detail in this work. A hollow-micropencil Co₃V₂O₈ prepared through the hydrothermal method without using surfactants or templates demonstrates a high “fast-charging” capability even at the current densities as high as 1.0–2.0 A g⁻¹. The electrochemical kinetic results illustrate that the hollow-micropencil Co₃V₂O₈ presents low charge transfer resistance. The distinctive lithium ion storage sites as well as diffusion paths are predicted. The in situ X-ray diffraction analysis is adopted to confirm that the formed Co° after the initial discharging is not oxidized to CoO during the delithiation process. The work not only helps to understand the lithium insertion mechanisms of Co₃V₂O₈ but also offers new means to develop “fast-charging” anode material for lithium-ion batteries with remarkable electrochemical performance.