Core–shell TiO2@Co3O4 anode materials with in situ formed nanoscale Co-based interfaces for enhanced lithium-ion transport

Abstract

In this study, TiO₂@Co₃O₄ microspheres with a core–shell structure are successfully synthesized via a homogeneous precipitation method. The composition, structure, and micro-morphology of the prepared microspheres are systematically characterized. The results confirm that spinel Co₃O₄ uniformly coats the surface of anatase TiO₂ microspheres, forming a lychee-like morphology with excellent dispersibility. The TiO₂@Co₃O₄ anode material exhibits significantly improved cycling performance, specific capacity, cycling stability, and rate capability compared to commercial graphite. To further investigate the synergistic interaction between TiO₂ and Co₃O₄, ex situ characterization, cyclic voltammetry, electrochemical impedance spectroscopy, and theoretical calculations are conducted. In contrast to the layered distribution observed prior to cycling, Co is redistributed in the form of nanoscale CoO and metallic Co particles dispersed across the TiO₂ after cycling, and form a stable interface. Due to interfacial electron accumulation, Ti and Co adopt a higher oxidation state, leading to stronger electron binding. This phenomenon reduces the electrostatic interaction between lithium ions and the surrounding charge, facilitating lithium-ion intercalation/deintercalation and lowering electrode impedance.