One-step recovery of valuable metals from spent Lithium-ion batteries and synthesis of persulfate through paired electrolysis

[Display omitted] •The paired electrolysis reduces energy consumption in the recycling of spent LIBs.•Synchronously recovering Co2+ as cobalt metal and synthesizing persulfate.•Simultaneous desalting in the recycling process of spent LIBs. The application of electrochemical methods on the recycling of valuable metals from spent lithium-ion batteries, and the removing of pollutant from wastewater by persulfate have attracted widespread attention in recent years. However, high energy consumption resulting from side electrochemical reactions constrains its application. Herein, a paired electrolysis method was designed to achieve the recycling of valuable metals from the spent LIBs and the synthesis of persulfate synchronically. In the process, high purity cobalt metal (>99.9%) was obtained from the leachate (catholyte) of the spent LIBs, and valuable persulfate were synchronically synthesized anolyte through a diaphragm electrolyzer. The prepared persulfate was directly thermally activated for pollutant degradation. Two important synthesis process are conducted in one step. About 30% energy consumption is reduced through paired electrolysis to produce valuable products of equal quality and the cathodic current efficiency is also enhanced about 4% compared with the single cobalt electrolysis system at same stage. Additionally, Li+ is recycled as Li2CO3 through precipitation from the electrolyte. As a green method, paired electrolysis will own a wide application prospects in the waste recycling and other hydrometallurgical fields because of low energy consumption and high valuable products.