Microwave-enhanced carbothermal reduction for efficient recovery of valuable metals from spent lithium-ion batteries

In conventional recycling processes for spent lithium-ion batteries (LIBs), the black mass (BM) of spent LIBs is typically subjected to high-temperature treatment, followed by leaching of valuable metals using strong acids or alkalis. However, these processes are energy-intensive, environmentally detrimental, and costly. Herein, we proposed a microwave-enhanced carbothermal reduction (MECTR) method characterized by a rapid heating rate and high heating efficiency. Under microwave irradiation at approximately 20  W, the temperature of the BM was elevated to 545 °C, and LiNi_0.8Co_0.1Mn_0.1O₂ (NCM811) was completely decomposed within 10  min. Subsequently, lithium was selectively extracted via simple water leaching at room temperature, achieving a leaching efficiency of 96.07 %. Nickel, cobalt, and manganese were effectively leached using a 0.5  M sulfuric acid solution at 60 °C, with leaching efficiencies of 98.01 %, 98.53 %, and 99.50 %, respectively. In addition, the particle morphology and elemental distribution of the BM before and after microwave heating and water leaching were investigated using SEM-EDS, and the formation and leaching behavior of lithium carbonate were analyzed. This strategy, with significant advantages in terms of recovery efficiency, processing time, and energy consumption, provides a promising and sustainable alternative for the recycling of spent LIBs.