Controllable Synthesis and “Fast‐charging” Mechanism of Hollow‐Micropencil Co ₃ V ₂ O ₈ from Perspective of Ion Diffusion in Crystal Structure

Abstract Co 3 V 2 O 8 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 Co 3 V 2 O 8 as an anode material are reported, the formed Co° from Co 3 V 2 O 8 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 Co 3 V 2 O 8 and the diffusion mechanism of lithium ion in Co 3 V 2 O 8 are studied in detail in this work. A hollow‐micropencil Co 3 V 2 O 8 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 Co 3 V 2 O 8 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 Co 3 V 2 O 8 but also offers new means to develop “fast‐charging” anode material for lithium‐ion batteries with remarkable electrochemical performance.