Recovery of lithium from spent lithium-ion batteries using precipitation and electrodialysis techniques

Abstract

At present, the projected demand for lithium calls for processing all viable resources especially secondary resources. This paper presents a promising approach for recovering lithium from low lithium high-salt solution which is usually produced in the spent LIBs recycling process. The solution was firstly purified, and then lithium was precipitated by phosphate, the effects of operating conditions on the Li3PO4 precipitation behaviors were evaluated. The results indicated that temperature is a more important factor than seed crystal or flocculant. After that, Li3PO4 was dissolved by acid as the anolyte, and electrodialysis with cation-exchange membranes was used to investigate the separation performance of Li and P. The results showed that Li and P was effectively separated by electrodialysis, and the P/Li mass ratio of the catholyte was reduced to 0.23 (6.5 times lower compared to a feed P/Li ratio of 1.48). Deep separation of lithium and phosphorus in the catholyte was achieved by raising pH to make the lithium precipitated with the permeated phosphorus. The lithium concentration of purified catholyte was 22.5 g/L and was used to prepare lithium carbonate. The Li2CO3 precipitation rate reached 88.3% at 80 °C under CO33−/Li+ molar ratio of 1.1:2. The final product of lithium carbonate was in accord with the standard specification (Li2CO3-0, GB/T 11075-2013). The results of this study provide an efficient and green cyclic process for recovering lithium from spent LIBs.