Abstract
Traction batteries are a key factor in the environmental sustainability of electric mobility and, therefore, it is necessary to evaluate their environmental performance to allow a comprehensive sustainability assessment of electric mobility. This article presents an environmental assessment of a lithium-ion traction battery for plug-in hybrid electric vehicles, characterized by a composite cathode material of lithium manganese oxide (LiMn2O4) and lithium nickel manganese cobalt oxide Li(NixCoyMn1-x-y)O2. Composite cathode material is an emerging technology that promises to combine the merits of several active materials into a hybrid electrode to optimize performance and reduce costs. In this study, the environmental assessment of one battery pack (with a nominal capacity of 11.4 kWh able to be used for about 140,000 km of driving) is carried out by using the Life Cycle Assessment methodology consistent with ISO 14040. The system boundaries are the battery production, the operation phase and recycling at the end of life, including the recovery of various material fractions. The composite cathode technology examined besides a good compromise between the higher and the lower performance of NMC and LMO cathodes, can present good environmental performances.The results of the analysis show that the manufacturing phase is relevant to all assessed impact categories (contribution higher than 60%). With regard to electricity losses due to battery efficiency and battery transport, the contribution to the use phase impact of battery efficiency is larger than that of battery transport. Recycling the battery pack contributes less than 11% to all of the assessed impact categories, with the exception of freshwater ecotoxicity (60% of the life cycle impact). The environmental credits related to the recovery of valuable materials (e.g. cobalt and nickel sulphates) and other metal fractions (e.g. aluminium and steel) are particularly relevant to impact categories such as marine eutrophication, human toxicity and abiotic resource depletion.The main innovations of this article are that (1) it presents the first bill of materials of a lithium-ion battery cell for plug-in hybrid electric vehicles with a composite cathode active material; (2) it describes one of the first applications of the life cycle assessment to a lithium-ion battery pack for plug-in hybrid electric vehicles with a composite cathode active material with the aim of identifying the “hot spots” of this technology and providing useful information to battery manufacturers on potentially improving its environmental sustainability; (3) it evaluates the impacts associated with the use phase based on primary data about the battery pack's lifetime, in terms of kilometres driven; and (4) it models the end-of-life phase of the battery components through processes specifically created for or adapted to the case study.
Highlights
Electricity is currently one of the most relevant energy carriers used in decarbonisation of the energy sector in terms of either building applications (Cellura et al, 2017, 2015; Finocchiaro et al, 2016; Ortiz et al, 2014) or transportation (Spencer et al, 2017)
Whereas the anode is usually made of graphite (Steen et al, 2017), there are greater differences in the active materials used in the cathode, which is usually made of LiMn2O4 (LMO), LiFePO4 (LFP) or Li(NixCoyMn1-x-y)O2 (NCM) (Steen et al, 2017)
The data and results of this study allow the expansion of the state of the art in relation to Li-ion traction batteries, providing the first contribution analysis of the materials in an LMOeNMC cell technology for plug-in hybrid EV (PHEV) and the first assessment of the energy and environmental data related to its production and recycling processes
Summary
Electricity is currently one of the most relevant energy carriers used in decarbonisation of the energy sector in terms of either building applications (Cellura et al, 2017, 2015; Finocchiaro et al, 2016; Ortiz et al, 2014) or transportation (Spencer et al, 2017). Existing LCA studies cover Liion traction batteries that have different active cathode materials, such as LMO (Notter et al, 2010; Richa et al, 2015), LFP (MajeauBettez et al, 2011; Zackrisson et al, 2010) and NMC (Ellingsen et al, 2014; Majeau-Bettez et al, 2011), to the authors’ knowledge the only environmental assessment of an LMOeNMC traction battery for battery electric vehicles (BEVs) was carried out by Kim et al (2016). A pyrometallurgical recycling treatment followed by a hydrometallurgical one is considered, and the potential environmental credits resulting from the recycling of recoverable products, depending on the composition of the battery cell examined, are assessed This is an important contribution of the study as, to the authors' knowledge, most previous LCAs of Li-ion batteries have not provided a detailed analysis of recycling in terms of environmental impacts and credits. The current article considers available life cycle datasets (as in the Ecoinvent database) that have been updated in accordance with the abovementioned studies (Chancerel and Marwede, 2016; Recharge, 2018; UMICORE, 2018), tailored to the materials used in the battery chemistry assessed in the article and designed to take into
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