부산대학교 도서관

The excessive use of lithium-ion batteries (LIBs) poses a potential severe environmental problem. Spent LIBs are prospective lithium (Li) sources. This study aims to recover Li from LIBs and regenerate cathode from the recovered and residual Li. The spent cathode was mixed with a spent anode and heated at a given temperature and time for its reduction. The reduced cathode was leached using carbonated water and was analyzed before and after its leaching. The leachate was examined to determine the Li content, and it was evaporated to obtain solid high purity Li2CO3. At a 6% solid/liquid (S/L) ratio and a 2-L/min CO2 flowrate, the leaching efficiency was 94%, which decreased as the S/L ratio increased. The Li2CO3 purity was close to that of pure Li2CO3 and superior to that of commercial Li2CO3. Regenerated lithium nickel–cobalt–aluminum oxide (RNCA) cathode material was obtained via a reaction of Li2CO3 and the leaching residue. RNCA achieved a discharge capacity of 128 mA h/g at 0.1C (102 mA h/g at 1C) and 79% capacity retention after 50 cycles at 1C. The discharge capacities of a commercial NCA cathode and spent cathode were 133 mA h/g at 0.1C (115 mA h/g at 1C) with 82.6% capacity retention after 50 cycles at 1C and 38 mA h/g at 0.1C with 52% capacity retention after 50 cycles at 0.1C, respectively. The obtained Li2CO3 met the requirements of LIB cathode manufacturing, and the spent NCA cathode could be regenerated to form cathode materials with good characteristics via a simple technique.