ABSTRACT – Lithium-based electric vehicle (EV) batteries currently dominate the market, imposing a problem as lithium shortage is expected to develop if effective recycling procedures are not put in place to mitigate the issue. Therefore, new battery technologies that do not depend on the limited resources of lithium and rare earth materials – such as cobalt - are desired to ensure a sustainable future for EVs. Thus, this work applies life cycle assessment (LCA) to different Lithium-based batteries and sodium ion (Na-ion) battery as one of the most promising alternative technologies due to the abundance of sodium on the planet. To an extreme, the work also applies a comparative LCA of a lithium-ion (Li-ion) battery EV with a size-compatible fuel cell electric vehicle (FCEV). The methodology encompasses well-to-pump (cradle-to-gate) and well-to-wheel (WTW) approaches using SimaPro and GREET software, focusing on environmental and energy impacts, global warming potential, resource depletion, pollutant and greenhouse gas (GHG) emissions. These include volatile organic compounds (VOC), carbon monoxide (CO), oxides of nitrogen (NOX), particulate matter, sulphur oxides (SOX), methane (CH4), and others. The analysis relies on battery inventories and the main outputs are materials, fuels, electricity and heat. The results show that Na-ion battery present similar level of carbon dioxide (CO2) emissions lithium-based batteries, but about 30% lower resource depletion and 5 times lower stratospheric ozone depletion. The well-to-pump energy consumption of Li-NMC (Nickel-Manganese-Cobalt) battery production in the UK is about 14% lower than China, and 5% lower than the US. GHG emissions are about are around 35% lower in the UK in comparison with China, and 25% lower than the US. The cell components are by far the largest contributors to energy consumption, followed by the pack components and module components. Among the lithium-based batteries, Li-S (Sulphur) battery provides the lowest cycle life but the highest environmental benefit. In general, GHG and pollutant emissions from a fully electric battery EV are substantially higher than those of an equivalent FCEV. The fully electric EV presented high SOX emissions, while the FCEV showed high participation of CH4 on LCA emissions. Carbon dioxide (CO2) accounted for 83-84% of total GHG emissions, while both CO2 and GHG LCA emissions from the FCEV were 62% lower than the battery EV. The limitations of this study are set by the lack of a cradle-to-grave analysis, which could provide more comprehensive understanding of the full battery lifecycle by including recycling and end-of-life stages. Additional limitations come from reliance on the battery inventory available in the software and the high sensitivity of well-to-wheel emissions to the electricity mix and the intensity of car utilization by the drive. The fast evolution of batteries may also change the quantitative results. This work provides new insights into battery technologies by exploring and relating aspects of emissions and energy consumption aspects as not previously reported. In conclusion, while Li-based batteries are playing a major role for vehicle electrification, Na-ion battery was shown to be an interest alternative to reduce the dependence on scarce materials and can in future help to decrease the cost of EVs.

Dr. Jose Sodre, Head of Department of Mechanical, Biomedical and Design Engineering, Aston University