Charakterisierung und Optimierung eines zweistufigen Verfahrens zur Rückgewinnung von Graphit aus verbrauchten Lithium-Ionen-Batterien

Translated title of the contribution: Characterization and optimization of a two-stage process for the recovery of graphite from spent lithium-ion batteries

Research output: ThesisMaster's Thesis

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Abstract

Graphite is a modification of carbon used in a wide range of applications such as electrodes, refractory materials, and lubricants. Graphite is also commonly used as an anode material for lithium-ion batteries. Due to its classification as a critical raw material in the European Union and the increasing demand in electromobility as well as other future technologies, recycling of this resource has become of great importance and a main focus of research. This results in the necessity, to recover the raw material from residuals as an alternative to primary mining. Recycling processes can be categorised into either pyro- or hydrometallurgical routes, both of which can also be combined. Pyrometallurgical processing of lithium-ion batteries is nowadays often integrated into recycling operations for other metallurgical waste streams. Within these process schemes, it is not possible to selectively recover individual elements. Furthermore, graphite is only used as an energy source and reducing agent, but the material itself is not recycled. Hydrometallurgical technologies have enhanced the separation of individual metals for further recycling. In hydrometallurgy, most of the graphite remains in the solid residue, which is obtained by a solid-liquid-separation. The hydrometallurgical process development of the recovery of graphite from spent lithium-ion-batteries is discussed in this thesis, with additional emphasis placed on the characterisation of the purified fraction. A two-stage leaching process removes valuable metals such as cobalt, nickel, manganese and further accompanying elements. The objective is the production of a graphite fraction with high purity and low levels of metallic and oxidic impurities. In order to limit the environmental impact, the experiments are conducted at low temperatures and with the help of citric acid as a leaching agent. To assess the success of the process, the fine powder obtained from the latter process is characterised in detail. Gelation effects occurred in some experiments, which also impacted the further processing of the residues. The best results were obtained using a medium temperature leach (32.5 °C) for 24 hours, with an acid concentration of 1.5 mol/L and 2.5 vol.-% hydrogen peroxide as reducing agent.
Translated title of the contributionCharacterization and optimization of a two-stage process for the recovery of graphite from spent lithium-ion batteries
Original languageGerman
QualificationDipl.-Ing.
Awarding Institution
  • Montanuniversität
Supervisors/Advisors
  • Gerold, Eva, Co-Supervisor (internal)
  • Antrekowitsch, Helmut, Supervisor (internal)
Award date22 Mar 2024
DOIs
Publication statusPublished - 2024

Bibliographical note

no embargo

Keywords

  • lithium-ion-batteries
  • battery recycling
  • graphite
  • black mass
  • hydrometallurgy
  • critical raw materials

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