1D nanostructure-assembled CuO/Cu₂O hollow spheres for lithium-ion battery with superior capacity and long cycle life

A novel porous CuO/Cu₂O composite hollow sphere assembled with one-dimensional (1D) nanostructures was successfully synthesized by a facile one-pot surfactant and template-free hydrothermal method. The electrochemical performance evidently demonstrated that the achieved porous CuO/Cu₂O composite hollow sphere was a very effective structure for solving the large volume expansion problem, which was serious issue for metal oxide anode materials. Compared to the initial cycle, the porous CuO/Cu₂O composite hollow spheres maintain a high reversible capacity of 680 mAh/g after 500 cycles at 100 mA/g without capacity fading. Meanwhile, the porous CuO/Cu₂O composite hollow spheres exhibit a good rate capability. The reversible capacity and cycling life significantly superior to those of reported CuO and Cu₂O nanostructures as well as CuO/Cu₂O h composite nanostructures, and the capacity fade was significantly inhibited. The excellent electrochemical performance of the CuO/Cu₂O h composite hollow spheres for anode materials in lithium-ion (Li⁺) batteries are attributed to the efficient diffusion of Li⁺ and electron facilitated by porous and 1D nanostructures, which promotes the diffusion of Li⁺ and electrons, effectively mitigates the volume changes caused by mesopores and internal hollow spaces, and the synergistic effect between CuO and Cu₂O within the porous CuO/Cu₂O hollo composite hollow spheres.