Recovery and reuse of spent lithium-ion batteries as catalysts for low-temperature NH3-SCR

•This work proposes a new idea of recycling spent LIBs.•Recycled LIBs as catalysts for NOx removal.•Oxalic acid as leaching and precipitating agent.•The use of oxalic acid facilitates the creation of pore structures.•Catalyst achieves nearly 100 % NOx conversion at 110 ∼ 230 °C. The wide application of lithium-ion batteries (LIBs) for electric vehicles forebodes the decommissioning tide of spent LIBs. Therefore, recycling valuable element from spent LIBs are becoming urgent to minimize the impact on the environment and supply chain of battery manufacturers. In this work, we propose to extract valuable elements from the cathode materials of spent ternary lithium-ion batteries and synthesize NiCoMnOx catalysts for low-temperature NH3 selective catalyst reduction (NH3-SCR) reactions. The oxalic acid is used as a precipitant and reducing agent and prepared as NiCoMnOx catalyst by hydrothermal process and heat treatment. The as-prepared catalyst presents a porous fluffy foam structure with abundant oxygen defects, ensuring sufficient catalytic active sites. As a result, the NiCoMnOx catalyst exhibits optimal catalytic activity with over 90% NOx conversion in the temperature range of 110 ∼ 230 °C, which is wider than the temperature range of 155 ∼ 210 °C for the catalysts prepared from metal salts. Meanwhile, the NiCoMnOx catalyst also shows better catalytic stability and resistance to H2O and SO2. This work provides a promising strategy to recycle spent LIBs to low-temperature NH3-SCR catalysts.