Facile synthesis of nanocrystalline-assembled bundle-like CuO nanostructure with high rate capacities and enhanced cycling stability as an anode material for lithium-ion batteries

Abstract

In this work, nanocrystalline-assembled bundle-like CuO structures were successfully synthesized in large-quantity by a friendly, facile two-step process. The bundle-like CuO particles are produced by thermolysis of bundle-like Cu(OH)₂ precursors, which exhibit excellent high specific capacity, high stability, and especially high rate performance for anode materials in lithium-ion batteries, superior to that of most reported CuO-based anodes. The assembled structure of CuO endows it with high rate capacities of 666 mAh g⁻¹, 609 mAh g⁻¹, and 499 mAh g⁻¹ at a current rate of 0.3 C, 1 C and 2 C after 50 cycles, respectively. Even at a high rate of 6 C, the bundle-like CuO can still deliver a capacity of 361 mAh g⁻¹. It is observed that the electrochemical performance of the nanocrystalline-assembled bundle-like CuO is much better than that of CuO nanoparticles obtained by destroying the assembled bundle-like CuO through grinding. XRD analysis of both the electrodes after ending the discharge/charge proved that during the discharge/charge process, the conversion reactions occurring in the assembled structures have better reversibility, leading to the high rate capacity and cycling performances. The better reversibility originates from the better contact area for CuO/electrolyte, enhancing many sites to the access of Li⁺ in the electrolyte Li⁺. In addition, the assembled bundle-like CuO architectures can also relieve the volume variations during the Li⁺ uptake–release process, which also contributes to the excellent electrochemical performance. The high rate capacity and enhanced cycling stability of the bundle-like CuO structure make it a promising candidate as an anode material for high-performance Li-ion batteries.