Dissolution Behavior of Lithium-Ion Battery Cathode Materials in Aquatic Systems: Key Drivers and Molecular Mechanisms

The rapid expansion of lithium-ion battery (LIBs) deployment has generated increasing volumes of spent batteries that are often improperly discarded, raising concerns about their environmental impact. Lithium nickel cobalt manganese oxides (NCM), the predominant cathode materials in modern LIBs, are of particular concern because of their high content of redox-active transition metals (TMs). Nevertheless, their dissolution behavior and underlying molecular mechanisms under environmentally relevant conditions are poorly understood. In this study, we systematically examined four commercial NCM compositions (NCM111, 523, 622, and 811) under environmentally relevant variables, including pH, temperature, salinity, and organic ligands. Lithium ions (Li⁺) exhibited high solubility across all conditions (>80%), whereas nickel ions (Ni²⁺), cobalt ions (Co²⁺), and manganese ions (Mn²⁺) demonstrated low but environmentally sensitive release (∼2%). Compared with temperature, salinity, and humic acid, metal dissolution was governed primarily by pH and citric acid. Density functional theory (DFT), combined with the computational hydrogen electrode (CHE) model, revealed that environmental factors influence the dissolution free energy (ΔG) through proton attack, ligand binding, ionic strength, and lattice destabilization. Experiments conducted in six representative waters further confirmed enhanced Ni²⁺ and Co²⁺ release in acidic, organic-rich leachates. Collectively, these findings provide mechanistic insights into NCM dissolution pathways and contribute to risk assessment and sustainable management strategies for spent LIBs.