Selective recovery of manganese from spent ternary lithium-ion batteries for efficient catalytic oxidation of VOCs: Unveiling the mechanism of activity Enhancement in recycled catalysts.

With the widespread application of ternary lithium-ion batteries (TLBs) in various fields, the disposal of spent TLBs has become a globally recognized issue. This study proposes a novel method for reutilizing metal resources from TLBs. Through selective oxidation, manganese in a leaching solution of TLBs was converted into MnO with α, γ, and δ crystal phases (referred to as T-MnO) for catalytic oxidation of volatile organic compounds (VOCs), while efficiently separating manganese from high-value metals such as nickel, cobalt, and lithium, achieving a manganese recovery rate of 99.99%. Compared to similar MnO prepared from pure materials, T-MnO exhibited superior degradation performance for toluene and chlorobenzene, with T decreasing by around 30 °C. The acidic synthesis environment provided by the leaching solution and the doping of trace metals altered the physicochemical properties of T-MnO, such as increased specific surface area, elevated surface manganese valence, and improved redox performance and oxygen vacancy properties, enhancing its catalytic oxidation capacity. Furthermore, the degradation pathway of toluene on T-γ-MnO was inferred using thermal desorption-gas chromatography/mass spectrometry (TD-GC/MS) and in-situ DRIFTs. This study provides a novel approach for recycling spent TLBs and treating VOCs catalytically.