## 5 Conclusions  
Battery recycling is a mandatory task along with the electrification of the transport sector. Therefore, providing methods for assessing the availability of secondary materials is a necessary task in order to address issues related to supply risks, environmental sustainability and costs.  
In this regard, the present study provides a quantification of the cumulated supply of battery materials from secondary sources between 2019 to 2030, which in total amounts to appr. 5 Mt. In response to the research question, we find that the available secondary Co from LIB recycling is sufficient to satisfy the Co demand for EV applications in the early up to mid-30s. By observing different technology-rollout scenarios, this finding can be linked to the reduced Co share in future battery technologies. For the other raw materials, Li, Ni and Mn, no intersection between material demand and availability of secondary material is found before 2035. Furthermore, the sensitivity analysis reveals that the parameters with the highest impact on the availability of secondary materials are the production waste and the battery lifetime.  
From a CE perspective, the results thereby underline the potential of EV battery recycling to reduce the dependency on primary-resource extraction by keeping materials at their highest value at all times. This emphasizes the importance of effective legislation and policy making towards a CE, which supports the adoption of highly efficient battery recycling and the implementation of a closed-loop production. While focusing on the potential for reducing primary-material consumption for the production stage of new batteries, our findings suggest that more work is needed to investigate the relationship between recycling and other CE strategies for batteries such as remanufacturing and repurposing (2 nd life). In this context, the results show how companies such as OEMs need to navigate between different CE strategies when managing battery EoL flows and the resulting secondary-material supply. Consequently, future research should investigate how other performance indicators can be used in order to maximize the material circularity of the company as a whole.  
Moreover, the results of the present study indicate that for the case of Co, combining measures for reducing the amount of Co by deploying new battery technologies with an increase in efficient recycling processes provides a feasible pathway for establishing a closed material loop. In order to make this possible and to find similar opportunities for other raw materials, efforts should be dedicated to both product development for LIBs and the upscaling of global recycling infrastructures, especially for the time beyond 2025. This would reduce the environmental and social impacts associated with LIB production, as well as the dependency on the price fluctuations of critical battery materials. Furthermore, strategic procurement activities are recommended for Li and Ni, given that the future material demand cannot be fully satisfied by secondary sources.  
Finally, future studies should focus on measures for reducing battery-production waste and increasing battery lifetime, thereby ensuring a more sustainable use of battery raw materials in general. Here, including waste streams from other industries and markets, e.g., electric trucks, stationary batteries, etc., in future studies seems to be a promising avenue of research, which would allow a more holistic view on the potential for implementing a CE for batteries.  
Conceptualization, M.N.; methodology, M.N. and B.S.; software, M.N.; validation, J.M.-P. and M.S.-M.; formal analysis, M.N., M.S.-M. and J.M.-P.; investigation, M.N. and J.M.-P.; resources, M.N.; data curation, M.N.; writing--original draft preparation, M.N.; writing--review and editing, J.M.-P., J.O.P., R.G.-O., A.K. and B.S.; visualization, M.N. and J.M.-P.; supervision, B.S. All authors have read and agreed to the published version of the manuscript.