Preparation of CuO nanorods for lithium-ion battery anodes by supercritical hydrothermal reaction of spent acidic etchant

An economical and environmentally friendly treatment method is urgently needed for the copper-containing spent acidic etchant produced by printed circuit boards. In this work, CuO nanorods with ∼30 nm in diameter and ∼100 nm in length were prepared from spent acidic etchant by supercritical hydrothermal synthesis. The structures and morphologies of spent acidic etchant-derived CuO (E-CuO) and analytical pure CuCl₂-derived CuO (P-CuO) were characterized. The E-CuO has more impurities such as Fe and Zn than the P-CuO. The energy storage performance of the prepared CuO anodes was tested. The E-CuO delivers a high initial discharge capacity of 793.3 mAh·g^-1 and a better rate and cycling performance than the P-CuO due to the smaller particles and the doping of Fe and Zn from the spent acidic etchant in the E-CuO.