Fig. 6. CV curve of anatase TiO2 (a) and TiO2@Co3O4 (b) with a scanning speed of 0.3 mV s−1 and a voltage window of 0.01 V to 3.0 V; (c) total DOS of the films; (d) Nyquist plots of TiO2, TiO2@Co3O4, and Co3O4 in the frequency range of 1 × 10−2 Hz to 1 × 106 Hz. The inset shows the equivalent circuit diagram, where CPE1 represents the double-layer capacitance, R1 represents the internal resistance of the battery, R2 represents the charge transfer resistance, and Wo1 represents the Warburg coefficient for lithium-ion diffusion.54 (e) Calculated lithium-ion migration energy barriers in TiO2, TiO2@Co3O4 and TiO2@CoO along the migration path shown in Fig. S13. 6 inset figures illustrates the charge difference at sites 1, 3, and 6. The isosurface level is set to 0.005, with yellow indicating charge accumulation and cyan representing charge depletion.
