Experimental Investigation of the Impact of End-of-Life Lithium-Ion Battery Chemistry on Index and Engineering Properties of Clayey Soil Stratum

Abstract

The end-of-life (EOL) lithium-ion batteries (LiBs) that contain metals such as cobalt (Co), copper (Cu), iron (Fe), manganese (Mn), nickel (Ni), and lithium (Li) commonly end up in landfills, which pose a threat to soil and groundwater quality. This study investigates the impact of three major electric vehicle (EV) battery chemistries: (1) lithium–nickel–manganese–cobalt oxide (NMC); (2) lithium–cobalt oxide (LCO); and (3) lithium–iron–phosphate (LFP) with the highest heavy metal concentrations on the soil index and engineering properties using extensive laboratory-scale experimentation. The observations reveal that the liquid limit (LL) decreases by 38.02%, 27.7%, and 34.4% for NMC, LCO, and LFP battery chemistry, respectively. In addition, the plastic limit (PL) shows a decrease of 51.75%, 41.96%, and 36.84% for NMC, LCO, and LFP battery chemistry, respectively. The interaction between metal ions in LiB contaminants leads to a 4.86%, 4.51%, and 4.8% increase in specific gravity for NMC, LCO, and LFP battery chemistries, respectively. The void ratio of LiB-contaminated soil increases by 83.33% (NMC), 10.41% (LCO), and 45.43% (LFP), and the coefficient of compression (Cc) increases by 134.61%, 50%, and 104.54%, respectively. In addition, significant increases are observed in the coefficient of volume change (e.g., 236.42%, 113.5%, and 150%), coefficient of consolidation (e.g., 25.92%, 9.09%, and 25%), and permeability (e.g., 135.84%, 25%, and 75.29%) for the respective battery types. The observed changes in soil properties are attributed to the neutralization of the electrostatic forces between soil particles due to metal ion adsorption, which leads to particle aggregation and changes in the soil’s structural integrity. In addition, this study indicates the significant impact of EOL-LiBs on clayey soil stratum, which might compromise the structural integrity and stability of the soil layer and pose environmental risks. Therefore, careful consideration and appropriate remediation measures are essential in relation to landfill site closure and further use of sites for any infrastructural developments.