The surface capacitance behavior and its contribution to the excellent performance of cobalt ferrite/carbon anode in lithium storage

Carbon coated CoFe₂O₄ (CFO/C) is synthesized with the polyvinylpyrrolidone as carbon source by using the hydrothermal and subsequent heat treatment. The particle size of the CFO (CFO/C) is less than 50 nm, which facilitates the transport of Li⁺. The CFO/C composite delivers reversible discharge specific capacity of 934.8, 790.5, 685.9, 524.6, and 418.7 mAh g⁻¹ at current density of 0.2C, 0.5C, 1C, 3C, 5C, respectively. When the current density is 1C, the CFO/C composite maintains the reversible specific discharge capacity of 775.6 mAh g⁻¹ after 380 cycles. The quantitative calculation of the Cyclic voltammetry (CV) shows that the total charge is derived from the contribution of both surface capacitance behavior and diffusion-controlled process during lithium storage, and the capacitance behavior plays a critical role in determining the rate performance and cycle stability.