Utilization of waste leather for efficient removal of Ca ²⁺ and Mg ²⁺ in lithium carbonate production <i>via</i> nano-structural adsorption

With the growth of electric vehicles (EVs), the demand for battery-grade lithium carbonate (Li₂CO₃) is increasing significantly. However, a large part of the available Li₂CO₃ is of industrial-grade, either ternary material or lithium iron phosphate (Li₂CO₃ is one of the precursors for either ternary material or lithium iron phosphate), which cannot satisfy the requirements for the preparation of cathode. Traditional production of battery-grade Li₂CO₃ involves converting industrial-grade lithium carbonate into LiHCO₃ solution through carbonization using CO₂; the insoluble impurities are then removed by filtering, followed by thermal decomposition. However, Ca²⁺ and Mg²⁺ are the most difficult impurities to be removed due to their similar characteristics as that of Li⁺. This study evaluates the use of a vegetable-aldehyde combination tanned leather to filter Ca²⁺ and Mg²⁺ from a LiHCO₃ solution utilizing the nano structure of the leather. Results show an effective reduction in Ca²⁺ and Mg²⁺ concentrations in the LiHCO₃ solution. When treated with EDTA, the leather can be reused for at least 12 cycles, indicating a cost-effective and sustainable high-quality lithium carbonate production strategy. This study highlights the tanned leather's potential as a reliable filtration medium for lithium-ion battery precursors.