Converting Spent LiFePO4 Battery into Zeolitic Phosphate for Highly Efficient Heavy Metal Adsorption

Developing efficient recycling technologies for large-scale spent batteries is the key to build a zero-waste city. Herein, a [Al_8.5Fe_0.5P₁₂O₄₈]·[C₂₄H₇₂N₁₆]·[Li·4H₂O]·[12H₂O] (AlFePO-Li) zeolite, crystallizing in space group I4̅3m with a = 16.6778(3) Å, has been constructed via the hydrothermal treatment of spent LiFePO₄ battery. Benefiting from the three-dimensional 12-member-ring channels in its structure and chemical adsorption, excellent Pb²⁺ removal capacity up to 723.8 mg g^-1 has been achieved. Detailed adsorption mechanism study revealed that the cation exchange capacity is significantly contributed by ion exchange of the protonated organic amine cations in the zeolite channel and the protons from the framework dangling phosphate group. This work demonstrates a novel method of reutilizing spent LIBs to construct zeolite for heavy metal removal. It is of great importance to achieve sustainable development based on the "resource utilization" and "trash-to-treasure" strategy.