A Study on the Cathode Materials Recovery Process Using Various Wet Chemistry

Abstract

Demand for lithium-ion batteries (LIBs) has increased dramatically over the years due to the rapid market expansion of electric vehicles. Current commercial lithium ion batteries mainly contain nickel, cobalt, manganese metal oxides, lithium, phosphates, aluminum, copper, graphite, organic electrolytes and other chemicals. Therefore, the recycling and reuse of used lithium-ion batteries at the end of their useful life are of great interest by many researchers. However, due to the high energy density, high safety and low price of lithium-ion batteries, the difference and variety are large, which poses great difficulties in recycling waste lithium-ion batteries. Lithium ion batteries recycling typically involves both physical and chemical processes. Physical processes typically include pretreatment and direct recovery of electrode materials. These processes typically include decomposition, crushing, screening, magnetic separation, washing, heat treatment, etc. As shown in Figure 1, chemical processes can generally be divided into pyrometallurgical and hydrometallurgical processes which include leaching, separation, extraction and chemical/electrochemical precipitation. Recently, recycling technologies for lithium secondary batteries through a direct regeneration process have been attracting attention. Directly regeneration technique has the advantages of short recovery route, low energy consumption, eco-friendly compared to pyrometallurgical and hydrometallurgical processes. In order to recover the cathode active material from the separated electrode plate, a process for separating the PVDF binder and the cathode active material is required. In general, N-methyl-2-pyrrolidone (NMP) is the most common solvent for the manufacture of cathode electrodes in the battery industry. Although ~99% of the solvent used in electrode manufacturing is recovered, it is however limited in several countries due to negative environmental impacts.In this study, the cathode materials were separated electrode from used lithium ion cell using various wet-chemistry. Chemical, structural, and electrochemical characteristics of the cathode materials and substrate were investigated. Figure 1