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EP-4741518-A1 - A METHOD FOR RECOVERING AN OFF-SPEC PRUSSIAN WHITE MATERIAL

EP4741518A1EP 4741518 A1EP4741518 A1EP 4741518A1EP-4741518-A1

Abstract

The present disclosure generally relates to a method for recovering an off-spec Prussian White material comprising: a) providing an off-spec Prussian White material; b) reacting the off-spec Prussian White material with an aqueous solution comprising sodium cyanide (NaCN) or potassium cyanide (KCN) under conditions that allow for at least one Prussian White precursor to form. The present disclosure also relates to a system for recovering an off-spec Prussian White material.

Inventors

  • RICCARDI, Ludovico
  • MOGENSEN, Ronnie

Assignees

  • Altris AB

Dates

Publication Date
20260513
Application Date
20241108

Claims (16)

  1. A method for recovering an off-spec Prussian White material comprising: a) providing an off-spec Prussian White material; b) reacting said off-spec Prussian White material with an aqueous solution comprising sodium cyanide (NaCN) or potassium cyanide (KCN) under conditions that allow for at least one Prussian White precursor to form.
  2. The method according to claim 1, wherein said off-spec Prussian White material is derived from a failed Prussian White slurry, a failed Prussian White manufacturing process, a spent, discarded, or off-spec electrode, and/or a spent, discarded or off-spec battery cell.
  3. The method according to claim 1 or claim 2, wherein said off-spec Prussian White material is defined by A a X 1 [X 2 (CN) 6 ] 1-y , wherein A is Na or K, a ≤ 2, 0 ≤ y ≤ 0.2, and wherein X 1 and X 2 are individually selected from Fe, Mn, Co, or Cr.
  4. The method according to claim 3, wherein a < 1.8, such as 1 < a < 1.8.
  5. The method according to any one of the preceding claims, where said at least one Prussian White precursor is a sodium or potassium hexacyanometallate.
  6. The method according to any one of the preceding claims, wherein said at least one Prussian White precursor is defined by A 4 X 1 (CN) 6 and/or A 4 X 2 (CN) 6 , wherein A is Na or K, and wherein X 1 and X 2 are individually selected from Co, Cr, Fe, and Mn.
  7. The method according to any one of the preceding claims, wherein said step b) is performed at a temperature of from 40 to 95°C, preferably from 50 to 90°C.
  8. The method according to any one of the preceding claims, wherein said step b) is performed at a pH of from 8 to 14, preferably from 9 to 13.5, more preferably from 10 to 13.
  9. The method according to any one of the preceding claims, wherein the amount of sodium cyanide (NaCN) or potassium cyanide (KCN) in said aqueous solution is in stoichiometric excess relative to the amount required to react with said off-spec Prussian White material and form said Prussian White precursor.
  10. The method according to claim 9, wherein said stoichiometric excess of sodium cyanide (NaCN) or potassium cyanide (KCN) ranges from 15% to 100%, preferably from 20% to 100% above the amount required to react with said off-spec Prussian White material and form said Prussian White precursor.
  11. The method according to any one of the preceding claims, wherein said method further comprises: c) reacting said Prussian White precursor, after said step b), with an acid selected from H 2 SO 4 , H 4 C 2 O 2 , H 2 C 2 O 4 , H 2 CO 2 , H 3 PO 4 , H 3 PO 3 , HCl, and HClO 2 under conditions that allow for a second Prussian White material to form.
  12. The method according to claim 11, wherein said second Prussian White precursor is defined by A b X 1 [X 2 (CN) 6 ] 1-y , wherein A is Na or K, 1.8 ≤ b ≤ 2, 0 ≤ y ≤ 0.2, and wherein X 1 and X 2 are individually selected from Fe, Mn, Co, and Cr.
  13. The method according to claim 11 or claim 12, wherein said step c) is performed at a pH of from 1.8 to 4.5, preferably from 2 to 3.5.
  14. The method according to any one of claims 11-13, wherein said step c) is performed at a temperature of from 65 to 95°C, preferably from 75 to 95°C.
  15. A system for recovering an off-spec Prussian White material comprising a first reactor unit configured to: a) receive an off-spec Prussian White material; and b) conduct a first reaction of said off-spec Prussian White material with an aqueous solution comprising sodium cyanide (NaCN) or potassium cyanide (KCN) under conditions that allow for at least one Prussian White precursor to form.
  16. The system according to claim 15, wherein said system further comprises a second reactor unit configured to: c) conduct a second reaction of said Prussian White precursor with an acid selected from H 2 SO 4 , H 4 C 2 O 2 , H 2 C 2 O 4 , H 2 CO 2 , H 3 PO 4 , H 3 PO 3 , HCl, and HClO 2 under conditions that allow for a second Prussian White material to form.

Description

TECHNICAL FIELD The present disclosure generally relates to a method for recovering an off-spec Prussian White material and to a system for recovering the off-spec Prussian White material. BACKGROUND Prussian White (PW) is an environmentally friendly cathode material, which has gained considerable attention due to its high theoretical capacity and rate performance. Prussian White has a crystal structure with an open three-dimensional framework and large interstitial voids, which makes it capable of storing sodium (or potassium) ions in an efficient manner. Prussian White is typically used as the active cathode material in sodium ion battery cells, where it facilitates the reversible insertion and extraction of sodium (or potassium) ions during charge and discharge cycles. Over time, through repeated charge and discharge cycles, the performance of the cathode and the battery cell may be impaired. For example, the cathode may no longer be able to hold sufficient charge to function effectively. When a battery cell reaches the end of its lifetime, the components, including the Prussian White cathode, are typically discarded. The disposal process contributes to environmental waste and may also require specific waste handling procedures and precautions. The disposal of spent battery components also represents a loss of valuable resources, including cyanide molecules, iron, manganese, sodium, and/or potassium contained in Prussian White cathodes. Accordingly, this approach is not sustainable in the long term. The discarded resources must be newly extracted and processed, which may place additional strain on natural resources and may increase the environmental footprint of battery production. Furthermore, during the production of Prussian White, a proportion of the material formed may not meet the quality or performance specifications required for its intended use. To date, such "failed" Prussian White material is typically incinerated at high temperatures. However, incineration presents an economic and environmental burden due to the release of significant amounts of greenhouse gases, contributing to climate change. Furthermore, the incineration process leads to the loss of valuable resources incorporated in the Prussian White material. In view of this, there is a need for a sustainable process for recovering failed Prussian White containing materials and components. Such a process should enable recycling of valuable components, minimize waste, and reduce the overall environmental impact. SUMMARY In view of above-mentioned and other drawbacks of the prior art, it is an object of the present disclosure to provide a sustainable and cost-efficient procedure for recovering Prussian White. According to a first aspect of the present disclosure, there is provided a method for recovering an off-spec Prussian White material comprising: a) providing an off-spec Prussian White material;b) reacting the off-spec Prussian White material with an aqueous solution comprising sodium cyanide (NaCN) or potassium cyanide (KCN) under conditions that allow for at least one Prussian White precursor to form. The present disclosure is based on the realization that Prussian White (PW) may be recovered by reacting an off-spec Prussian White material with an aqueous solution comprising NaCN or KCN such that the off-spec Prussian White material is converted into at least one Prussian White precursor. The Prussian White precursor(s) may subsequently be used in the manufacture of new, high-quality Prussian White material. In this regard, key components contained in the off-spec PW material are repurposed, recycled and re-used, thereby reducing the need for new material extraction. Furthermore, the emission of greenhouse gases is significantly reduced, and a more sustainable and cost-efficient solution is provided. Instead of discarding a spent battery or a Prussian White material of low quality, the material is converted into new precursor(s), which may be utilized for the synthesis of new Prussian White material associated with a higher quality. The inventors have found that the reaction of the off-spec Prussian White with an aqueous solution comprising NaCN or KCN generates Prussian White precursor in a high yield. As demonstrated in the Example section, a significantly higher yield of Prussian White precursor is obtained with NaCN (or KCN) compared to an aqueous solution comprising sodium hydroxide (NaOH). The off-spec Prussian White material may originate from a variety of sources. For example, the off-spec Prussian White material may be derived from a failed Prussian White slurry, a failed Prussian White manufacturing process, a spent, discarded, or off-spec electrode, and/or a spent, discarded or off-spec battery cell. During the production of Prussian White, manufacturing defects or variations in the synthesis process can result in a material that does not meet the required quality or performance specifications, such as improper stoichiom