Parametric life cycle assessment model for absolute environmental sustainability assessment of lithium-ion batteries

Recent studies indicate that six of the nine planetary boundaries, including climate change, have been exceeded. Decarbonizing the transport sector, a key contributor to climate change, is challenging. While battery electric vehicles offer relative improvements in the use stage, they must be evaluated against absolute sustainability targets, taking into account the entire life cycle. This study develops a simplified life cycle assessment (LCA) model based on parametric modelling for the absolute environmental sustainability assessment of NMC811 battery pack production. Simplified LCA models are constructed through variance decomposition based on first-order Sobol indices.

The estimated climate change impacts are compared against absolute sustainability targets to determine the probability of achieving them. Climate impacts for the battery pack range from 87.9 kg CO₂-eq/kWh at the 5th percentile to 134.0 kg CO₂-eq/kWh at the 95th percentile, with a mean value of 108.0 kg CO₂-eq/kWh. The mean climate change target value, representing the maximum allowable climate impact, for a 58-kWh battery pack is estimated at 27.25 kg CO₂-eq/kWh. Extending the battery pack's lifetime from 10–15 years to 15–25 years increases the target value to 36.20 kg CO₂-eq/kWh. The use of secondary aluminium in battery production has the highest potential for reducing climate change impact. The results of the local sensitivity analysis indicate that using 100 % secondary aluminium reduces the climate change impact by 22.65 %. This also reduces the impacts in 14 other ReCiPe method midpoint impact categories. Notably the ‘human toxicity: carcinogenic’ and ‘energy resources: non-renewable, fossil’ impacts are reduced by 26.36 % and 19.73 % respectively. However, the impacts related to ‘ecotoxicity: freshwater’ and ‘ecotoxicity: terrestrial’ increase by 0.05 % and 0.68 % respectively.

This study contributes to the field of absolute sustainability within the context of battery production. By employing probabilistic analysis and parametric LCA modelling, it enables the evaluation of specific decarbonisation strategies.