Long-term leaching dynamics and ecotoxicity of wastewater from electric vehicle lithium-ion battery fires

The global adoption of electric vehicles has increased the frequency of lithium-ion battery (LIB) fires, which are typically managed through large-scale water suppression and immersion. While immediate fire behavior is well-documented, the long-term environmental consequences of the resulting wastewater remain poorly understood. This study evaluates the 112-day temporal dynamics of contaminant leaching from nickel-manganese-cobalt (NMC) vehicle batteries following three distinct ignition scenarios: a short circuit, mechanical breakthrough with heavy fire, and thermal stress without visible flames. Physicochemical analysis revealed that the most heavily damaged module exhibited the highest pollutant load in this case study. The module that experienced the most extensive physical damage showed the highest conductivity (23.1 mS/cm), high lithium (1.54 g/L), and elevated fluoride levels (218 mg/L), exceeding typical regulatory limits by orders of magnitude. Ecotoxicological assessments using Daphnia magna, Lemna minor, and Aliivibrio fischeri demonstrated severe acute and chronic toxicity, with EC₅₀ values for D. magna reaching 0.05 %. Even non-ignited, venting modules released significant organic pollutants and exhibited high microbial toxicity. These findings demonstrate that LIB firefighting runoff creates a highly hazardous effluent that matures over time. Specialized on-site containment and pre-treatment are essential to prevent the breakthrough of these toxic elements into the urban sewerage system and the wider aquatic environment.