## 2 Materials and Methods
### Life Cycle Inventory
#### 2.2.3 End-of-Life  
The impact of the EoL stage on both the cell materials and the non-cell materials was divided into three parts: Recycling (impact of the recycling process), Credits (savings obtained by replacing part of the virgin materials with recovered ones), and Further waste disposal (impacts necessary to complete the disposal of nonrecycled materials). It was assumed that the EoL phase occurred in Europe, and the average European electricity mix was therefore used. Everbatt reports material and energy flows for both pyrometallurgical and hydrometallurgical recycling processes, with regards to the recycling of cell materials, but the two processes are modelled as alternatives. In this work, battery cell recycling was modelled through a combined recycling process (Figure 2), which is in line with the recommendations of PEFCR on rechargeable batteries [26]. In other words, the cells first underwent a pyrometallurgical process, and the metal alloy and slag obtained as outputs were then treated again through a hydrometallurgical process to extract valuable metals. The inventories for the pyrometallurgical and hydrometallurgical treatments were taken from the [PERSON] model but adapted by the authors to this new approach. Further details are reported in Section 2.2.3.1, recycling of the cell materials. The \"Credits\" for cell materials are due to the recovery of Nickel, Manganese, Cobalt, and Copper, whereas \"Further waste disposal\" quantifies the impact due to the wastewater treatment, incineration of Graphite, PVDF, Carbon black and Plastics, and the landfilling of Aluminium, Lithium, and the remaining slag. The EoL, with reference to the non-cell materials, included the \"Recycling\" of BMS, the cooling system, and battery packaging, \"Credits\" for recovering Copper, Aluminium and Steel with appropriate recovery rates, and \"Further waste disposal\" to quantify the impact due to the treatment of the remaining nonrecycled materials. Further details are reported in Section 2.2.3.2 \"Non-cell materials-EoL\". 2.2.3.1 Recycling of the Cell Materials  
In the Pyrometallurgical process, batteries are fed to a furnace where they are smelted. This high-temperature process recovers an alloy of Co, Cu, Ni, and Fe [9] but does not allow graphite, electrolyte, and plastic materials (because they are burned), Aluminium (because it is oxidized), or Manganese to be recovered. However, Lithium exits from the furnace in a slag, along with Aluminium, because the recovery of Lithium is currently not economically viable [9]. The fate of the cell materials is detailed in Table S5. The recycling process inventory is reported in Table S6. The required feed materials and energy for Pyrometallurgical and Hydrometallurgical processes are listed separately. Since Everbatt provides the two Pyrometallurgical and Hydrometallurgical processes as alternatives, the amounts of materials and energy associated with the Hydrometallurgical process were adjusted, taking account the molten metal alloy resulting from the Pyrometallurgical step to model the process in cascade. 2.2.3.2 Non-Cell Materials-EoL  
The inventory proposed in [43] was applied to model the recycling of non-cell materials. In other words, the recycling processes of the BMS, cooling system, and battery packaging were modelled taking into account the energy required for both the preparation of the Aluminium, Iron, and Copper scraps for recycling and the energy required to recycle each recoverable fraction. The amounts of recovered materials were assessed considering the recovery rates R\({}_{2}\) reported in PEFCR for rechargeable batteries [26]. According to this PEFCR, R\({}_{2}\) is the proportion of material in the product that can be recycled (or reused) in a subsequent system. The suggested R\({}_{2}\) values for Copper and Aluminium are 90%, whereas the R\({}_{2}\) for Steel is 85%. The remaining parts of Copper and Steel were modelled according to the specific Ecoinvent \"Market for scrap\", while the remaining Aluminium was considered to be sent for landfilling.