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EP-4736256-A1 - METHOD FOR RECOVERING PERFLUORINATED LITHIUM COMPOUNDS FROM LITHIUM-ION BATTERIES

EP4736256A1EP 4736256 A1EP4736256 A1EP 4736256A1EP-4736256-A1

Abstract

The invention relates to a method for recovering a perfluorinated lithium compound from an electrolyte of a lithium-ion battery. The method comprises the steps of: (a) thermally treating the electrolyte such that the perfluorinated lithium compound is decomposed to obtain a first compound as a gaseous reaction product and a second compound as a solid reaction product; (b) providing an electrolyte matrix which contains the second compound; and (c) leading the first compound obtained in step (a) to the electrolyte matrix, the first compound obtained in step (a) being reacted with the second compound contained in the electrolyte matrix provided in step (b), to form the perfluorinated lithium compound.

Inventors

  • BERTAU, MARTIN
  • HANSEL, Bastian
  • PÄTZOLD, Carsten

Assignees

  • Technische Universität Bergakademie Freiberg Körperschaft des öffentlichen Rechts

Dates

Publication Date
20260506
Application Date
20240626

Claims (15)

  1. 1. A process for recovering a perfluorinated lithium compound from an electrolyte of a lithium-ion battery, comprising the steps (a) thermally treating the electrolyte to decompose the perfluorinated lithium compound to obtain a first compound as a gaseous reaction product and a second compound as a solid reaction product; (b) providing an electrolyte matrix containing the second compound; and (c) adding the first compound obtained in step (a) to the electrolyte matrix, reacting the first compound obtained in step (a) with the second compound contained in the electrolyte matrix provided in step (b) to form the perfluorinated lithium compound.
  2. 2. Process according to claim 1, characterized in that the perfluorinated lithium compound is lithium hexafluorophosphate or lithium tetrafluoroborate.
  3. 3. Process according to claim 1 or claim 2, characterized in that the electrolyte used in step (a) is obtained by disassembling and/or crushing one or more lithium-ion batteries.
  4. 4. Process according to one of the preceding claims, characterized in that in step (a) the thermal treatment is carried out at a temperature of 40 °C or more.
  5. 5. Process according to one of the preceding claims, characterized in that the second compound contained in the electrolyte matrix provided in step (b) is the solid reaction product obtained in step (a) and/or originates from another source.
  6. 6. Process according to one of the preceding claims, characterized in that the second compound obtained in step (a) is fed to a reactor in which an electrolyte matrix is present, whereby the electrolyte matrix containing the second compound is obtained.
  7. 7. Process according to one of the preceding claims, characterized in that in step (c) the first compound is fed to the electrolyte matrix by means of an inert gas.
  8. 8. A process according to claim 6 or claim 7, characterized in that the first compound is fed into the reactor in which the electrolyte matrix containing the second compound is located.
  9. 9. Process according to one of the preceding claims, characterized in that the electrolyte matrix provided in step (b) is dried by distillation of its components and/or by using a molecular sieve.
  10. 10. Process according to one of the preceding claims, characterized in that in step (c) the first compound is supplied in a molar amount m which corresponds to a molar ratio of 1:1 to 1:15 to the molar amount of the second compound contained in the electrolyte matrix provided in step (b).
  11. 11. Process according to one of the preceding claims, characterized in that in step (c) the reaction is carried out at a temperature in a range between 0 and 25 °C.
  12. 12. Process according to one of the preceding claims, characterized in that following step (c) a purification of the electrolyte matrix containing the perfluorinated lithium compound is carried out.
  13. 13. Process according to claim 12, characterized in that the purification is carried out using an anion exchanger.
  14. 14. The method according to claim 13, characterized in that the anion exchanger is treated with a salt having a perfluorinated anion corresponding to the anion of the perfluorinated lithium compound.
  15. 15. A method for producing a conductive salt-containing electrolyte matrix for a lithium-ion battery, wherein the conductive salt is a perfluorinated lithium compound, comprising the steps (a) thermally treating the electrolyte of a lithium-ion battery containing the conducting salt to decompose the conducting salt to obtain a first compound as a gaseous reaction product and a second compound as a solid reaction product; (b) providing an electrolyte matrix containing the second compound; and (c) feeding the first compound obtained in step (a) to the electrolyte matrix, reacting the first compound obtained in step (a) with the second compound contained in the electrolyte matrix provided in step (b), to obtain the electrolyte matrix containing conductive salt.

Description

Description Process for the recovery of perfluorinated lithium compounds from lithium-ion batteries [0001] The invention relates to a method for recovering perfluorinated lithium compounds from lithium-ion batteries. It also relates to a method for producing a conductive salt-containing electrolyte matrix for a lithium-ion battery. [0002] Lithium-ion batteries (LIB) are secondary batteries, also known as accumulators. They consist of several interconnected cells, each of which essentially has a negative electrode, also known as an anode, a positive electrode, also known as a cathode, and an ion-conducting electrolyte. The electrolyte contains a conductive salt that has lithium ions. The conductive salt can be a perfluorinated lithium compound, such as lithium hexafluorophosphate (LiPFe) or lithium tetrafluoroborate (LiBF4). The conductive salt is dissolved in an electrolyte matrix, which is usually a mixture of organic carbonates and various additives, and enables the transport of current between the anode and cathode of a LIB cell. The conductive salt is therefore essential for the production of LIB cells. [0003] The recovery of valuable materials from used lithium-ion batteries is of enormous economic interest. This is essentially the result of the ongoing trend towards social electrification, which is reflected, among other things, in the widespread expansion of global e-mobility. As a result, securing the LIB raw material base is of corresponding importance. This is reflected, among other things, in current legal requirements, which formulate a recycling rate of 65% for the net recovery of the valuable materials of an entire LIB cell by 2025 and 70% by 2030. If we only consider lithium, which is essential for LIB production, a 35% recycling rate is required by 2026 and a 70% recycling rate by 2030. [1] [0004] Already established recycling processes deal with this task by processing the solid electrode material in the form of LIB black mass. This represents the non-magnetic fraction of the layer and electrode materials that arises after mechanical processing. On the way to generating the LIB black mass, which forms the starting material for the LIB recycling processes, the electrolyte of a LIB cell is destroyed at the beginning of the process chain. [0005] The LIB recycling process (100) according to the prior art shown in Fig. 1 starts with the preparation of the used LIB cells (101) to obtain a LIB material. This preparation can involve crushing the LIB cells, optionally under inert gas or aqueous conditions. In the next step, a thermal pretreatment of the possibly crushed LIB material (104) is carried out. The electrolyte is removed by decomposing the conductive salt. The electrolyte does not take part in the further processing of the LIB cells. After the optional crushing (101) and thermal pretreatment of the LIB cells (104), the LIB black mass (105) is obtained. This contains all LIB components that were not removed by the thermal pretreatment. This therefore includes housing part residues that could not be separated during the mechanical processing, electrode material and collector foils. This excludes the original conductive salt, i.e. the perfluorinated lithium compound, and (depending on the process parameters of the thermal pretreatment) the organic components of the electrolyte. The LIB black mass is subjected to hydrometallurgical processing (107). For this purpose, one of the following processes can be used, for example: Accurec process [16-20], Duesenfeld process [21-23], Primobius process [24] or COOL process [25]. These processes are used to develop secondary lithium sources (108) which can be used together with primary lithium sources (109) for LIB production (110). For this purpose, the primary and secondary lithium sources (109, 108) can first be converted into lithium carbonate (111), which can then be used in LIB production (110). The use of lithium from secondary lithium sources (108) is associated with a reduction in greenhouse gas emissions (112). The lithium obtained by adding elements such as Mn, Fe, Co and Ni (113) in LIB production (110) Lithium-ion batteries are recycled again (100) (arrow A) after their use (114), for example for the electrification of vehicles, as storage for renewable energies, etc. The electrolyte is destroyed again. [0006] However, the electrolyte contains valuable lithium compounds, which make up to 2% by weight of an entire LIB cell of a battery vehicle (electronic vehicle, abbreviated to EV) and are pyrolyzed or hydrolyzed during removal. [2] In the process, the valuable lithium compounds mentioned above are lost in their original form. This product devaluation in the form of waste generation therefore does not result in the recovery of the electrolyte's lithium compounds. In summary, this results in a continuous deficit in the balance of lithium recovery for all established LIB recycling processes. Achieving the previously formulated recycling targ