Interface–Defect Coupling Modulation in CuCo ₂ O ₄ /CuO Heterostructures for Enhanced Lithium Storage Performance

This study utilizes a hydrothermal-calcination synergistic approach to fabricate CuCo₂O₄/CuO materials on a nickel foam (NF) substrate, featuring stacked cluster structures abundant in oxygen vacancies (OV). The elevated oxygen vacancy concentration boosts the likelihood of carrier enrichment at the interface, reinforcing the built-in electric field. This, in turn, substantially decreases charge transfer resistance, leading to enhanced Li⁺ adsorption and diffusion efficiency. The combined effect of these factors significantly improves the material's rate performance. When the current density decreased from 1.0 A g^-1 to 0.1 A g^-1, the reversible capacity rebounded to 1201.5 mAh g^-1. At a current density of 0.1 A g^-1, the initial discharge capacity approached 1889 mAh g^-1, and the reversible capacity remained at 1170 mAh g^-1 after 200 cycles. Density functional theory (DFT) calculations further validate that the bandgap narrows considerably after heterojunction formation compared to single-component materials. The Li⁺ diffusion barrier is reduced from 0.87 eV in CuCo₂O₄ to 0.69 eV, and the electron density of states near the Fermi level is significantly increased. This study adopts a synergistic strategy of "heterojunction interface engineering and oxygen vacancy regulation" to concurrently enhance the high capacity and fast kinetic performance of transition metal oxide anodes. The findings offer experimental and theoretical insights for the structural design and performance optimization of transition metal oxide-based anode materials in lithium-ion batteries.