The closed-loop recycling strategy of Li and Co metal ions based on aqueous Zn-air desalination battery

Nowadays, it is a global problem to recycle LiCoO₂ from waste lithium-ion batteries (LIBs) due to the deficiency of high business cost and environmental pollution. Here, a novel three-channel ion recovery device based on a Zn-air desalination battery (ZADB) is proposed which can supply energy while separating Li⁺ and Co²⁺ from the recovered solution. The three-channel ZADB device consists of a Zn foil anode chamber with ZnSO₄ anolyte stream, an intermediate chamber with Li⁺ and Co²⁺ recovered stream and an air cathode chamber with LiOH and Co(OH)₂ catholyte stream, chambers are separated by anion exchange membrane (AEM) and cation exchange membrane (CEM) respectively. It can be described by the finite element simulation (FES) of physics field that, the Li⁺ and Co²⁺ in the recovered solution move to the cathode chamber, where the OH^- are produced by absorbing O₂ from the air combined with electronic in the discharge process. At the same time, the SO₄^2- moves to the other end of the Zn foil anode chamber according to the law of charge conservation, which combined with the Zn²⁺ removed from the Zn foil. The results show that the recovery efficiency of the ZADB device is closely related to the discharge current density and the concentration of the recovered stream. The best recovery effect has achieved when 0.2 mol L^-1 recovered solution is run for 24 h at the discharge current density of 0.2 mA cm^-2. The average recovery rate is 0.275 mg min^-1 with the highest recovery rate is 40.73 mg h^-1, and the output energy density is 102.5 Wh Kg^-1 during the experiment process. In addition, the ZADB device has the excellent long-term cycling performance and recycling stability. By comparing this device with other ion recovery methods, which provides that it is a splendid way to recycle Li⁺ and Co²⁺ from waste LIBs.