Electrochemical Lithium Storage Performance Of CuCl Anode Recovered From Waste Copper/acidic Cu-PCB Etching Waste

As an essential component of many electric and electronic equipments,printed circuit boards(PCBs)are usually produced by means of acid solution corrosion,in which the unwanted copper is etched and then dissolved into a liquid etchant.Unfortunately,the production of PCB is also generally accompanied by massive byproduct waste etching solutions,which are strongly corrosive and contain a large number of copper ions and Cl^-.Random abandonment of these spent etching solutions does not only damage the environment but also results in the resource waste.For this reason,two kinds of Cu-containing wastes including waste Cu and acid Cu-PCB etchant were recycled in the form of tetrahedron-like CuCl.The main contents of this work are listed as follows:(1)Waste Cu scraps and waste copper etchant were simultaneously recycled in the form of tetrahedron-like CuCl crystal via one-step facile co-proportional technique,and its electrochemical Li-storage performancewasalso evaluated.The results show that the resultant tetrahedron-like CuCl crystals possess four smooth triangular surfaces and six isometric sides.CuCl-based anode delivered a reversible discharge capacity of101.8 m Ah/g even cycling at 10 C for 2000 cycles,higher than that of graphite anode under the same conditions,implying the satisfactory long term Li-storage cyclic stability at a high rate.These results could facilitate to promote the development of circular economy mode of waste Cu-based resources and sustainable energy,which is of great importance for the environment protection.(2)Tetrahedron-like CuCl crystals were extracted from waste copper etchant by way of facile electrodeposition for the first time,and the effect of the electrodeposition time on the lithium(Li)-storage capacity of the CuCl crystal was further investigated.The results showed that CuCl crystal had a regular tetrahedral morphology,and the density of the regular tetrahedral particles gradually increased with the extension of the electrodeposition time from 5 to 15,20 and 25 s.Correspondingly,the reversible lithium storage capacity of the CuCl anode experienced an initial increase and a subsequent decrease.In detail,when cycling at 2 C for 250 cycles,the reversible discharge capacity of the CuCl anode increased from 187.3 m Ah·g^-1 at 5 s to 284.5m Ah·g^-1 at 15 s and then decreased to 191.9 m Ah·g^-1 at 20 s and to 125·3 m Ah·g^-1 at25 s,indicating that 15 s may be the most optimal electrodeposition time.Excessive CuCl particles may result in poor performance due to the poor inherent conductivity of CuCl.Such efforts would alleviate environmental pollution and facilitate the circular economy of wastes.