Comparative analysis of systematic variations in life cycle analysis of lithium-ion batteries for automotive applications

Abstract

Lithium-ion batteries can have considerable environmental impacts due to the multiple emission-intensive materials and complex manufacturing processes involved in their production. These environmental impact hotspots need to be identified and managed to reduce emissions from battery manufacturing. Researchers have quantified these environmental impacts and emissions for various cathode chemistries in the past; however, the life cycle impacts reported in previous studies differ considerably. To analyze the reasons for these differences, a detailed comparative analysis of life-cycle studies of lithium-ion batteries over the last decade is conducted. The data inventory and results of these previous studies are compared with the state-of-the-art inventory and results from the current version of the R&D GREET^® model. The analysis indicates that the primary reason for the divergence in life-cycle results across studies is the difference in approaches to sourcing secondary life-cycle inventory data, as well as the use of outdated or non-relevant inventory data. The non-standardized definition of battery assembly, a key energy- and emission-intensive step in lithium-ion battery production, is identified as another potential source of uncertainty and variation. The results indicate that controlling emissions from materials and processes used in cathode production can be a key factor in reducing the battery's greenhouse gas, particulate matter, sulfur oxide, and nitrogen oxide emissions. Battery assembly is also identified as a key source of greenhouse gas emissions with clear opportunities for reduction, while nickel sulfate is identified as the primary cause of sulfur oxide emissions in nickel-based cathode chemistries.