## 1 Introduction  
In the past, the on-board energy supply of battery electric vehicles (BEVs) was based on lead-acid, Nickel-metal hydride (NiMH) or on Sodium-Nickel-Chloride (ZEBRA) batteries [1, 2, 3, 4]. Over the years, an increasing number of battery types have been explored [5] in the search for better performances, stability, and/or longer lifespans. Among these, Li-ion batteries (LIB) have emerged as the dominant technology for BEVs [2, 3, 6, 7]. The main reasons for this are connected to the favourable material characteristics of Lithium [1] Lithium is in fact the lightest of all known metals and offers the best electrochemical potential, which results in a higher power and energy density [1]. The latter is of paramount importance for BEVs in order to compete with the performance and costs of internal combustion engine vehicles [7, 8]. Different cathode chemistries have been investigated for LIBs over the last decade. The first serial-production electric cars, launched just over a decade ago, used Lithium CobaltOxide (LCO) and Lithium Manganese Oxide (LMO) cathodes [6]. Attention then moved to other chemistries, for example, Nickel-Manganese-Cobalt oxide (NMC), Lithium Iron Phosphate (LFP) and, more recently, Lithium Nickel Cobalt Aluminium oxide (NCA) [3; 6; 9]. LFP batteries show an excellent cycle stability and long lifetime [3; 10]. However, due to their low energy density [3; 10], they are used less frequently in commercial BEVs [10]. NCA batteries are characterised by a high energy density but also by less safety [3; 6]. NMC batteries feature the highest energy density after NCA ones [3] and are currently the choice for power tools, e-bikes, and many electric powertrains [10; 11; 12]. Therefore, since the launching of mass-market electric vehicles, the focus of research and innovation activities has shifted towards NMC batteries [3; 6; 12], as evidenced by the large number of recent patents on this subject [6]. The cathode combination is typically one-third Nickel, one-third Manganese and one-third Cobalt, and this combination is known as NMC111. However, Cobalt is expensive and in limited supply, and its content largely determines the overall cost and sustainability of NMC batteries [3; 6; 13; 14; 15; 16]. Therefore, battery manufacturers are reducing the Cobalt content and shifting to cathodes with a higher Nickel content [3; 11; 13; 14; 15; 16]. Some of the combinations that have proved successful are NMC532 (with 5 parts Nickel, 3 parts Cobalt, and 2 parts Manganese), NMC622 and NMC811 [3; 7; 11; 13; 14; 15; 16]. From the technical point of view, Nickel-based cells have a higher energy density [3; 7; 14; 15; 16] and longer cycle life than Cobalt-based cells, but they may also have a slightly lower voltage [17]. In addition, Nickel-based cells decrease the dependence on Cobalt resources, which are geographically concentrated, expensive [7; 13; 14; 15; 16], and are starting to be scarce due to the significant increase in the exploitation of the mineral deposits required to provide the raw materials necessary for the LIB market [5]. The environmental impacts of different battery types and chemistries are generally analysed using a Life Cycle Assessment (LCA) [10]. In fact, a complete LCA is comprehensive of all the life cycle stages that characterise a product. Many studies [9; 11; 12; 18; 19; 20; 21; 22] have assessed the impacts of the production stage of NMC batteries, but they have not covered the other life cycle stages, and have often been neglected the End-of-Life (EoL) and Use stages. As far as the End-of-Life (EoL) stage is concerned, the actual low recycling rates for LIB could lead to a loss in the environmental benefits inherent to this type of battery. Moreover, the great uncertainties associated with the use of certain materials (e.g., solvents) and energy in the recycling processes, due to the lack of industry data [10], have led many researchers to neglect the EoL stage.