Iranian Journal of Chemical Engineering (IJChE)

Abstract Lithium-ion batteries are widely used in various electronic devices and typically discarded after their service life, causing significant environmental damage and resource wastage. Therefore, recycling the valuable components of the batteries, such as graphite, is essential. Graphite, employed as the anode material, is one of the key components targeted for recovery. In graphite recycling operations from spent batteries, critical hydrometallurgical processes are primary and secondary leaching stages using sulfuric acid. In this research, both leaching processes were systematically optimized. The optimal conditions identified for primary leaching were the temperature of 77 °C, concentration of 1.75 M of sulfuric acid, leaching duration of 4 hours, and liquid-to-solid graphite powder ratio of 5. Under these conditions, the graphite purity after the primary leaching process was 99.56 wt%. Subsequently, in the secondary leaching stage, a final high purity of 99.98% was achieved for the graphite product. To evaluate the electrochemical performance of the recycled graphite, galvanostatic charge-discharge tests, which demonstrated the specific capacity of 350 mAh/g, were conducted. This capacity is comparable to that of the commercial graphite, confirming the effectiveness of the developed recycling process.