Assessing resource depletion of NCM lithium-ion battery production for electric vehicles: An exergy-based perspective

Abstract

Electric vehicles (EVs) play an important role in the low-carbon transition of transportation, and lithium-ion battery (LIB) is a key component of EVs. Because of the high demand for energy and critical metals for LIB production, it is necessary to quantify the associated resource consumption intensity from multiple perspectives. In the present study, the exergy derived from the second law of thermodynamics was applied to assess the abiotic resource depletion associated with lithium nickel cobalt manganate (NCM) battery production, including NCM111, NCM523, NCM622, and NCM811. For comparability of results, the functional unit was defined as 1 kWh NCM power pack. The results showed that the cumulative exergy demand (CExD) value of the NCM523 pack production is 2857.56 MJ/kWh, with the cathode material manufacturing process accounting for 56.77% because of the significant contribution of CoSO4. The CExD of battery production can be effectively reduced by reducing cobalt use and adding a solvent recovery device. The supply stage of upstream raw and auxiliary materials is the key to CExD reduction. The comparison results indicated a significant reduction in the CExD of Ni-rich NCM batteries due to improvement in energy density and reduction in cobalt demand. In addition, the comparison of abiotic resource depletion characterization results and method characteristics among the CExD, ReCiPe, and CML-IA methods showed that using CExD has clear advantages with regard to objectivity and long-term stability in the evaluation of rapidly innovated battery products. Applying exergy-based accounting methods for resources contributes to a scientific understanding of abiotic depletion levels and improves resource efficiency in the relevant industries.