## 4 Discussion  
In order to verify the assumptions made, a comparison of the results with other existing projections of battery material demand is conducted. Here, Bloomberg predicts that battery demand will reach 1460 GWh in 2030 [20], which is similar to the result of 1531 GWh obtained in this study. Furthermore, Bloomberg calculates a projected Co demand of 64 kt for the year 2024, which corresponds well with the 61 kt obtained in the simulation. Furthermore, the results obtained for the recycled Co in Europe in 2030 of roughly 6 kt match the findings by [PERSON] et al. [31]. Compared to the results of previous studies such as [PERSON] et al. [1] or [PERSON] et al. [46], the simulated results for recycled Co in the present study differ. This is due to the fact that a specific cell-chemistry rollout has been assumed in this study, whereas [PERSON] et al. Figure 5: Sensitivity analysis to assess the impact of different parameters on the cumulated amount of recovered cobalt from battery recycling until 2030.  
have assumed NMC111 and LFP exclusively. Additionally, different vehicle forecasts have been implemented in the present study. Moreover, [PERSON] et al. calculate that in 2030, Co demand will be appr. 200 kt while the amount of available secondary Co will amount to 100 kt in 2030 [1]. Meanwhile, a study by Baltac estimates that the capacity for LIB recycling with 33 kt of batteries per year in the EU would not be enough to cover the demand [47]. The study estimates that the demand will increase to almost 100 kt of batteries in 2040. [PERSON] et al. forecast a quantity of 1,163,500 EoL batteries, which corresponds to a capacity of 46.5 GWh in the EU in 2030 [26]. Within the LithoRec project, a quantity of 22,500t EoL batteries has been calculated for Germany in 2030 [48], while an EU Recycling specialists journal projects 15 kt of LIBs to be recycled in 2030 [49]. At the same time, Umicore, a recycling company, estimates that 75 kt of batteries were already at their EoL before 2019 and need to be recycled [50]. Generally, these figures indicate that recycling forecasts for LIBs exist; however, the estimates significantly differ depending on the scope, data sources used, as well as assumed battery technologies and other parameters. Therefore, future studies should provide updated calculations and challenge the assumptions made for LIB recycling on an ongoing basis in order to provide robust and precise projections on secondary-material availability. Furthermore, future research should take into account that due to innovation in battery technology, the assumptions on battery size in terms of capacity and weight can be subject to changes, depending on the vehicle segment and cell chemistry. Additionally, the material compositions should be adjusted for the different types of vehicle (BEV, PHEV, FCEV) and the non-plug-in batteries should be added. Moreover, the rate of the batteries exceeding the assumed lifetime of 10 years should be further analyzed, together with the increasing risk of market losses, i.e., batteries that do not find their way into professional recycling facilities. Lastly, the rollout of different recycling methods and corresponding improvements in achievable recycling rates and material qualities should be closely monitored. In this study, the focus was only on automotive battery demand. However, it might also be reasonable to consider material flows from other industries that share the recycling path of automotive batteries. For that, integrating battery-recycling initiatives across industries could enable companies to jointly increase recycling-market capacities and to share the investment costs. This should be analyzed in further studies. Moreover, and in the context of a CE, remanufacturing describes the process of refurbishing a product towards the same properties as the original one [51]. It thus represents another strategy to further use LIBs at their EoL. Similar to repurposing, it affects the inputs and outputs of battery recycling.