## 2 Materials and Methods  
Based on the outlined challenges and knowledge gaps, the goal of the present study is to address the following research question: When is the availability of secondary Co, Ni, Li or Mn from LIB recycling sufficient to satisfy the global cobalt demand for EV applications? In order to arrive at an answer to this question, we firstly determine the global demand for the materials in scope, taking into account different rollout scenarios in terms of battery chemistries. Afterwards, we calculate the expected number of LIBs entering recycling between 2020 and 2035 worldwide. Based on the results, we determine the break-even point of global material demand and available secondary materials. Finally, we analyze and discuss the effects of different modelling parameters on the available LIB quantities for recycling as part of a sensitivity analysis and derive implications for the future recycling industry. For the calculations, we use an Excel-based simulation tool which allows to adopt different sources of EV battery-technology forecasts and to adjust specific input parameters. For each scenario, we used verified data sources (see Appendix A) in order to estimate the amount of recovered LIB materials. In this respect, the following input factor categories have been identified and integrated in the simulation tool:  
* The number of battery electric vehicles (BEVs), plug-in electric vehicles (PHEVs), and fuel cell electric vehicles (FCEVs) can be varied between different market projections by Bloomberg, IHS and a mixture of T&E, IEA, etc., [20; 21; 22; 23; 24]. * The regional split can be adjusted between worldwide, Europe, NAFTA, China, and the rest of the world. The split is based on annual regional shares as defined by Bloomberg [20]. * The average battery capacity for BEVs, PHEVs, and FCEVs has been calculated as the average of the EVs available in 2019 [25]. * The LIB lifetime can be varied between 8 and 15 years with a standard value of 10 years being assumed as a baseline. Although this value exceeds the average warranty period of 8 years defined by several OEMs, it can be considered a pessimistic assumption,  
Figure 1: List of LIB-recycling companies in Europe (data based on published sources [12; 18] (ERLOS), [19] (Nickelhuette Aue)). given that further development in battery technology to prolong battery lifetime is expected in multiple studies [26; 27; 28]. Generally, it is necessary to define the percentage of batteries returning from the market, i.e., the vehicle owners, and enter a recycling process. As a baseline, we assume that all batteries return and enter a recycling process, thereby neglecting that a certain share of market losses can occur. Furthermore, based on statistics by insurance companies such as HUK-COBURG [29] we assume that a share of 1% of all batteries is damaged during lifetime and thus enters recycling before reaching their EoL. In addition, another input parameter is the number of batteries entering a repurposing process. Battery repurposing--also called battery 2 nd life--describes the possibility of further using batteries in stationary applications at the end of their useful life in the vehicle [30]. Battery 2 nd life thereby extends the lifetime of the battery before reaching the EoL and entering the recycling stage, and thus needs to be included in the simulation. In this regard, [PERSON] et al. assumed a 20% repurposing rate in Europe in 2030 [31]. Elsewhere, [PERSON] et al. assumed a 10% share of batteries entering 2 nd life for LMO batteries [32]. Taking into account uncertainties regarding the adoption of battery 2 nd life at scale, a pessimistic repurposing rate of 5% was initially assumed in this study [33]. Furthermore, the effect of the parameter was critically assessed as part of the sensitivity analysis.