Recycling is vital to the sustainable scale-up of the lithium-ion battery (LIB) production, especially with regard to the great amount needed for electric vehicles, which places a significant strain on the critical raw materials[1]. Graphite – natural or synthetic – is the most dominant active material for the negative electrode[2]. Natural graphite, though, is considered a critical material within the EU[3], while synthetic graphite is obtained from coke[4] – a carbon precursor typically produced from coal or petroleum. By recycling graphite from spent LIBs, the eventual waste and CO2 emissions can be substantially decreased, while the overall resources are preserved. In fact, the efficient recycling and reuse is key towards a truly circular economy concerning LIB fabrication[5].
Herein, we report a new and highly efficient process to obtain high-quality graphite from spent LIBs. Following a comprehensive physicochemical characterization of the materials obtained, we conducted an extensive electrochemical characterization in half-cells and graphite‖NMC532 full-cells and compared the results with the data obtained for half-cells and full-cells employing pristine commercial graphite. In half-cells, the recycled graphite reveals remarkably high reversible specific capacities (e.g., 350 mAh g 1 at C/20) and very stable cycling for several hundred cycles at 1C. The graphite‖NMC532 full-cells show an excellent cycling stability as well, with a capacity retention of 80% after about 1,000 cycles. In fact, the comparison with the pristine graphite comprising full-cells reveals very comparable performance, highlighting the great promise of recycled and reused graphite as key step towards truly sustainable LIBs and the great goal of a circular economy.
References
[1] X. Sun, H. Hao, P. Hartmann, Z. Liu, and F. Zhao, “Supply risks of lithium-ion battery materials: An entire supply chain estimation,” Mater. Today Energy, vol. 14, p. 100347, Dec. 2019.
[2] J. Asenbauer, T. Eisenmann, M. Kuenzel, A. Kazzazi, Z. Chen, and D. Bresser, “The success story of graphite as a lithium-ion anode material – fundamentals, remaining challenges, and recent developments including silicon (oxide) composites,” Sustain. Energy Fuels, 2020.
[3] Comisión Europea, European Commission, Report on Critical Raw Materials and the Circular Economy, 2018. 2018.
[4] S. Richard, W. Ralf, H. Gerhard, P. Tobias, and W. Martin, “Performance and cost of materials for lithium-based rechargeable automotive batteries,” Nat. Energy, vol. 3, no. Li, pp. 267–278, 2018.
[5] A. Vanderbruggen, E. Gugala, R. Blannin, K. Bachmann, R. Serna-Guerrero, and M. Rudolph, “Automated mineralogy as a novel approach for the compositional and textural characterization of spent lithium-ion batteries,” Miner. Eng., vol. 169, p. 106924, 2021.