Improvement of Electrochemical Performance of Lithium-Ion Anode Materials by Local Oxidation of Multivalent Metal Oxides (CoO)

Efficient and stable lithium-ion batteries (LIBs) have garnered considerable attention; yet, the development of anode electrode materials continues to pose substantial challenges. While CoO electrode material boasts an ideal specific theoretical capacity, it is not without drawbacks, including significant volume expansion and concerns over safety performance, which hinder its viability as an anode material. In this research, we synthesized CoO/Co₃O₄ through a straightforward secondary hydrothermal treatment that locally oxidizes CoO, simultaneously creating oxygen vacancies. The incorporation of oxygen vacancies enhances the material’s internal conductivity and expedites the diffusion of electrons and ions, culminating in superior rate performance. Furthermore, the heterojunction structure diminishes the diffusion barrier, significantly enhancing the electrode’s reaction kinetics and overall electrochemical performance. At a modest current density of 0.1 A g⁻¹, the CoO/Co₃O₄ composite demonstrates enhanced cycling stability, delivering a capacity of 1022 mAh g⁻¹ after 100 cycles. Remarkably, even at an elevated current density of 1 A g⁻¹, it sustains a capacity of 768.8 mAh g⁻¹ over 400 cycles. The method of creating oxygen vacancies via autoxidation may pave the way for the advancement of multivalent oxide anode materials.