Electrochemical recovery of spent lead acid battery paste to controllably prepare lead powders in deep eutectic solvents

This paper propose a new electrochemical recovery method to controllably prepare lead powders from spent lead acid battery paste (SLP) in choline chloride-urea deep eutectic solvent (ChCl-urea DES). The electrochemical behavior of Pb(Ⅱ) in SLP + ChCl-urea solution is investigated by cyclic voltammetry. The experimental results show that the reduction of Pb(Ⅱ) ion to metallic lead is a quasi-reversible process controlled by diffusion. Electrolysis experiments show that as the cell voltage rises, the current efficiency increases and the specific energy consumption decreases firstly and then increases. When the cell voltage is 2.5 V, the current efficiency and specific energy consumption are 85.77% and 754.05 kWh/t, respectively. XRD and SEM results show that the deposits are pure lead powders and the cell voltage has significant effect on the morphology and particle size of lead powders. At lower voltage, fern-like lead powders with large branches are inclined to form. While, when the cell voltage is higher, it is easier to form finer and uniform rod-shaped lead powders.