Extraction of lithium and manganese ions from spent coin batteries: A new environmentally friendly approach

Coin cell batteries are widely used in portable devices, such as watches and toys, due to their compact size and high energy capacity. However, the growing demand for these batteries results in more waste, causing serious environmental problems due to the lack of adequate recycling processes. Thus, this study evaluated, for the first time, the extraction of lithium and manganese ions from spent coin cell batteries using a hydrometallurgical process with citric acid, without the need for calcination. Kinetic analysis indicated that, to benefit from the use of non-calcined material, reducing the solid-liquid ratio can facilitate the diffusion of the leaching agent, increasing metal ion extraction. Supporting these discussions, the response surface methodology (RSM) provided optimized conditions (solid-liquid ratio of 7.75 g/L, temperature of 80 degrees C, and citric acid concentration of 2 M), achieving extractions of 96 +/- 3% for Li+ and 84 +/- 3% for Mn2+. Physicochemical characterizations, including inductively coupled plasma optical emission spectrometry (ICP-OES), CHNS-O analysis, X-ray diffraction (XRD), Fourier transform infrared spectrometry (FT-IR), and scanning electron microscopy (SEM), confirmed the effective removal of metal ions before and after the leaching process. Additional scale-up studies and mass balances indicated that the hydrometallurgical process developed in this work can be considered technically viable and environmentally friendly for the extraction of Li+ and Mn2+ from spent coin cell batteries, contributing to resource reuse and waste reduction.