Applications of Metal Chloride Bridged Dimers

Abstract

The present invention discloses an application of a metal chloro-bridged dimer, which is applied to recovering LiPF6 from waste electrolyte of batteries. The metal chloro-bridged dimer includes one or more of iridium and platinum. The above metal chloro-bridged dimer is based on the ion exchange principle, and a cationic complex M of iridium or platinum + combines with anionic PF6 ‑ to form a stable and water-insoluble MPF6, achieving the purpose of highly efficient separation of MPF6 and Li, and enabling the recovery rates of Li + and PF6 ‑ in the electrolyte to be both higher than 95%.

Description

Technical Field

[0001] The present invention relates to the technical field of resource recycling, and particularly to an application of a metal chloro-bridged dimer. Background Art

[0002] Lithium batteries (LLBs) have advantages such as high discharge voltage and no memory effect, and are widely used in fields such as communication base stations and new energy vehicles. The electrolyte is one of the main components of lithium-ion batteries, affecting battery capacity, cycle efficiency, and safety and stability. The main components of lithium battery electrolytes are lithium salt electrolytes (LiPF 6 , LiBF 4 , LiClO 4 , LiAsF 6 , etc.), organic solvents (ethylene carbonate (EC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), etc.), and additives (vinylene carbonate (VC), N-methylpyrrolidone (NMP), etc.). Among them, the organic solvent accounts for 80-85%, the lithium salt electrolyte accounts for 12.5-15%, and the additive accounts for 2-8%. Since LiPF 6 has high solubility and conductivity in carbonates, it is currently the electrolyte for large-scale applications. The electrolyte (LiPF 6 ) is unstable and highly corrosive. When it encounters water, it will undergo a stepwise hydrolysis reaction, generating toxic gas HF and a series of soluble fluorides (LiF) and phosphides (Li 3 PO 4 ), causing water pollution and endangering human health. The electrolyte accounts for about 12% of the battery production cost, while the profit can be as high as 40%. It is a component with strong profitability in the material cost of lithium-ion batteries. Therefore, recycling the electrolyte of retired lithium-ion batteries has certain economic and environmental benefits.

[0003] So far, the recycling methods of electrolytes include component transformation methods and component transformation methods, etc. Among them, the component transformation method refers to introducing ionic reagents and converting metastable LiPF 6 into more thermodynamically stable hexafluorophosphates and Li salts to achieve the full-component recycling method; the component transformation method refers to introducing stabilizers and ionizing agents to decompose and transform LiPF 6 in the electrolyte into soluble and stable Li salts, F salts, and P salts, and recovering them by stepwise precipitation, but both have deficiencies such as complex process flows, low product purity, and low yield. Summary of the Invention

[0004] Based on this, in order to improve the product purity and yield of LiPF 6 in the recycled electrolyte, it is necessary to provide an application of a metal chloro-bridged dimer.

[0005] The present invention provides an application of a metal chloro-bridged dimer, and the metal chloro-bridged dimer is applied to the recovery of LiPF in waste battery electrolyte 6 , and the metal chloro-bridged dimer includes one or more of iridium and platinum.

[0006] In one embodiment, the general structural formula of the metal chloro-bridged dimer is:

[0007]

[0008] Wherein, R 1 and R 2 are each independently selected from, A is selected from the groups shown in any one of (B-1) to (B-2): ,

[0009] X 1 and X 2 are each independently selected from Ir or Pt, n and m are selected from 1 or 2, and Y 1 each occurrence is independently selected from N or CR 3 ; R 3 each occurrence is independently selected from: -H, -D or a straight-chain alkyl group having 1 to 5 carbon atoms.

[0010] In one embodiment, A is selected from the groups shown in any one of the following: Wherein: * represents the connection or fusion site.

[0011] In one embodiment, the structure of the metal chloro-bridged dimer is one of those shown in formulas (1-1) and (1-6):

[0012]

[0013]

[0014] In one embodiment, the composition of the waste electrolyte includes, by weight percentage: 5% to 15% of lithium hexafluorophosphate, 80% to 90% of an organic solvent, and 1% to 8% of an additive.

[0015] In one embodiment, the steps for recovering LiPF in the waste battery electrolyte 6 include:

[0016] Mix the metal chloro-bridged dimer, a first organic solvent and the waste electrolyte, filter to prepare a first solid and a first solution, wash the first solid with a second organic solvent and then dry it, and recover the dried product.

[0017] Mix the first solution, amino acid, soluble base and water, extract to prepare a first organic layer solution and an aqueous layer solution, evaporate the aqueous layer solution, and recover the evaporation product.

[0018] In one embodiment, in the step of recovering the dried product, it has at least one of the following characteristics:

[0019] (1) The mass of the metal chloro-bridged dimer is 30% - 80% of the mass of the waste electrolyte solution, and the mass of the first organic solvent is 20% - 50% of the mass of the metal chloro-bridged dimer;

[0020] (2) The first organic solvent is selected from one or more of dichloromethane and chloroform;

[0021] (3) The second organic solvent is selected from one or more of dimethyl carbonate and diethyl carbonate;

[0022] (4) The time for mixing the metal chloro-bridged dimer, the first organic solvent and the waste electrolyte solution is 0.5 h - 2.0 h, and the temperature is 10°C - 40°C.

[0023] In one embodiment, in the step of recovering the evaporation product, it has at least one of the following characteristics:

[0024] (1) The amino acid is selected from one or more of glycine, alanine, valine, leucine, isoleucine, methionine, proline, tryptophan, serine, tyrosine, cysteine, phenylalanine, asparagine, glutamine, threonine, aspartic acid, glutamic acid, lysine, arginine and histidine;

[0025] (2) The mass of the amino acid is 6% - 13% of the mass of the waste electrolyte solution, the mass of the soluble base is 3% - 8% of the mass of the waste electrolyte solution, and the mass of water is 20% - 50% of the mass of the waste electrolyte solution;

[0026] (3) The soluble base is one or more of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium methoxide and potassium ethoxide;

[0027] (4) The extraction time is 10 min - 30 min.

[0028] In one embodiment, after the step of recovering LiPF 6 in the battery waste electrolyte solution, there is further a step of recovering the metal chloro-bridged dimer:

[0029] Mix the first organic layer solution, strong acid and water to prepare a mixed solution, extract the mixed solution to prepare a second organic layer solution, and evaporate the second organic layer solution;

[0030] Wherein the strong acid is selected from one or more of hydrochloric acid, sulfuric acid, nitric acid, formic acid, trifluoroacetic acid, and trifluoromethanesulfonic acid.

[0031] In one embodiment, in the step of recovering the metal chloro-bridged dimer, there is at least one of the following characteristics:

[0032] (1) The mixed solution further includes metal chlorides, and the metal chlorides are selected from one or more of sodium chloride, potassium chloride, magnesium chloride, calcium chloride, and zinc chloride;

[0033] (2) The mass of the strong acid is 13% - 40% of the mass of the waste electrolyte;

[0034] (3) The mass of water is 30% - 100% of the mass of the waste electrolyte;

[0035] (4) The mass of the metal chloride is 5% - 20% of the mass of the metal chloro-bridged dimer;

[0036] (5) The extraction time is 10 min - 30 min.

[0037] The above-mentioned metal chloro-bridged dimer is based on the ion exchange principle, and a complex M of cationic iridium or platinum + reacts with the anion PF 6 - to form a stable and water-insoluble MPF 6 , achieving the purpose of highly efficient separation of MPF 6 from Li, so that the recovery rates of Li + and PF 6 - in the electrolyte are both higher than 95%.

[0038] At the same time, PF 6 - and Li + are recovered as the products hexafluorophosphate and lithium chloride respectively, and the purities of the recovered products are both higher than 99%. Moreover, the step of recovering Li + and PF 6 - from the waste electrolyte by using the metal chloro-bridged dimer has the advantages of simple operation, low equipment investment, environmental friendliness, quality controllability, and easy industrialization, etc., can produce good economic and social benefits, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 XRD pattern of the lithium chloride prepared in Example 1.

[0040] Figure 2 NMR (CDCl 3)Atlas. Detailed implementation

[0041] The present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided to make the disclosure of the present invention more thorough and comprehensive. Of course, they are only examples and are not intended to limit the present invention. In addition, the present invention may repeat reference numerals and / or letters in different examples. This repetition is for the purpose of simplicity and clarity and does not itself indicate the relationship between the various embodiments and / or arrangements discussed.

[0042] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the invention, "a plurality" means at least two, such as two, three, etc., unless otherwise specifically defined. In the description of the present invention, "several" means at least one, such as one, two, etc., unless otherwise specifically defined.

[0043] Unless otherwise specified, all percentages, fractions, and ratios are calculated based on the total mass of the composition of the present invention. Unless otherwise specified, all masses of the listed components are given for the content of the active substance, so they do not include solvents or by-products that may be contained in commercially available materials. The term "mass percentage content" in this article can be represented by the symbol "%".

[0044] The terms "include", "comprise", "contain", "have", or other variants herein are intended to cover non-closed inclusion, and no distinction is made between these terms. The term "comprise" means that other steps and components can be added without affecting the final result. The term "comprise" also includes the terms "consist of" and "consist essentially of". The compositions and methods / processes of the present invention comprise, consist of, and consist essentially of the essential elements and limitations described herein and any additional or optional components, ingredients, steps, or limitations described herein. No distinction is made between the terms "efficacy", "performance", "effect", and "function" in this article.

[0045] The terms "preferably", "more preferably", etc. in the present invention refer to embodiments of the present invention that can provide certain beneficial effects in certain cases. However, in the same or other cases, other embodiments may also be preferred. In addition, the description of one or more preferred embodiments does not imply that other embodiments are not available, nor is it intended to exclude other embodiments from the scope of the present invention.

[0046] When a numerical range is disclosed herein, the above range is considered continuous and includes the minimum and maximum values of the range, as well as every value therebetween. Further, when the range refers to integers, every integer between the minimum and maximum values of the range is included. In addition, when multiple ranges are provided to describe features or characteristics, the ranges may be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all sub-ranges subsumed therein.

[0047] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terms used herein in the specification of the present invention are for the purpose of describing particular embodiments only and are not intended to limit the present invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0048] The present invention provides an application of a metal chloro-bridged dimer, and the metal chloro-bridged dimer is applied to recovering LiPF in spent battery electrolyte 6 , and the metal chloro-bridged dimer includes one or more of iridium and platinum.

[0049] In a specific example, the structural general formula of the metal chloro-bridged dimer is:

[0050]

[0051] Wherein, R 1 and R 2 each independently selected from, A is selected from the groups shown in any one of (B-1) to (B-2):

[0052]

[0053] X 1 and X 2 each independently selected from Ir or Pt, n and m are selected from 1 or 2, Y 1 each occurrence, independently selected from N or CR 3 ; R 3 each occurrence, respectively independently selected from: -H, -D or a straight-chain alkyl group having 1 to 5 carbon atoms.

[0054] In a specific example, A is selected from any one of the following groups: Wherein: * represents a connection or fusion site.

[0055] In a specific example, the structure of the metal chloro-bridged dimer is one of those shown in Formula (1-1) and (1-6):

[0056]

[0057]

[0058] Understandably, the metal chloro-bridged dimers of the structural formulas (1-1) to (1-6) are respectively iridium dichloro-bridged 2-phenylpyridine, iridium dichloro-bridged 2-phenylquinoline, iridium dichloro-bridged 2-phenylisoquinoline, platinum dichloro-bridged 2-phenylpyridine, platinum dichloro-bridged 2-phenylquinoline, and platinum dichloro-bridged 2-phenylisoquinoline.

[0059] In a specific example, the composition of the waste electrolyte includes, by weight percentage: 5% to 15% of lithium hexafluorophosphate, 80% to 90% of an organic solvent, and 1% to 8% of an additive.

[0060] Further, the organic solvent in the waste electrolyte is selected from one or more of ethylene carbonate (EC), dimethyl carbonate (DMC), diethyl carbonate (DEC), and ethyl methyl carbonate (EMC), and the additive is selected from one or more of vinylene carbonate (VC) and N-methylpyrrolidone (NMP).

[0061] In a specific example, the steps for recovering LiPF 6 from the waste electrolyte of the battery include:

[0062] Mixing the metal chloro-bridged dimer, the first organic solvent, and the waste electrolyte, filtering to prepare a first solid and a first solution, washing the first solid with the second organic solvent and then drying, and recovering the dried product.

[0063] Mixing the first solution, an amino acid, a soluble base, and water, extracting to prepare a first organic layer solution and an aqueous layer solution, and evaporating the aqueous layer solution to recover the evaporation product.

[0064] In a specific example, in the step of recovering the dried product, the mass of the metal chloro-bridged dimer is 30% - 80% of the mass of the waste electrolyte. A mass ratio within this range is more conducive to the separation of the components of the present invention, ensuring a relatively high product purity and yield. If the addition amount of the metal chloro-bridged dimer is lower than this range, lithium ions cannot be completely precipitated, resulting in a low yield of lithium chloride and a low purity of hexafluorophosphate; while if the addition amount of the metal chloro-bridged dimer is higher than this range, the yield and purity will not be further improved.

[0065] Further, in the step of recovering the dried product, the mass of the first organic solvent is 20% - 50% of the mass of the metal chloro-bridged dimer.

[0066] In a specific example, in the step of recovering the dried product, the first organic solvent is selected from one or more of dichloromethane and chloroform.

[0067] In a specific example, in the step of recovering the dried product, the second organic solvent is selected from one or more of dimethyl carbonate and diethyl carbonate.

[0068] In a specific example, in the step of recovering the dried product, the time for mixing the metal chloro-bridged dimer, the first organic solvent and the waste electrolyte is 0.5 h to 2.0 h, and the temperature is 10 °C to 40 °C.

[0069] It can be understood that the above reaction conditions are more conducive to higher product yield and purity of the present invention. If the reaction temperature is higher than 40 °C or the reaction time is less than 0.5 h, the lithium chloride yield and the hexafluorophosphate purity are low; if the reaction temperature is lower than 10 °C or the reaction time is less than 0.5 h, the lithium chloride yield and the hexafluorophosphate purity are low.

[0070] In a specific example, in the step of recovering the evaporated product, the amino acid is one or more of glycine, alanine, valine, leucine, isoleucine, methionine, proline, tryptophan, serine, tyrosine, cysteine, phenylalanine, asparagine, glutamine, threonine, aspartic acid, glutamic acid, lysine, arginine and histidine.

[0071] In a specific example, in the step of recovering the evaporated product, the mass of the amino acid is 6% to 13% of the mass of the waste electrolyte, and the mass of the soluble base is 3% to 8% of the mass of the waste electrolyte. If the addition amount of the amino acid or the soluble base is lower than the scope of the present invention, the hexafluorophosphate purity remains unchanged, but the yield is low; while if the amino acid or the soluble base is higher than the scope of the present invention, the yield and purity will not be further improved.

[0072] In a specific example, in the step of recovering the evaporated product, the mass of water is 20% to 50% of the mass of the waste electrolyte.

[0073] In a specific example, in the step of recovering the evaporated product, the soluble base is at least one of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium methoxide and potassium ethoxide.

[0074] In a specific example, in the step of recovering the evaporated product, the extraction time is 10 min to 30 min.

[0075] Furthermore, in the step of recovering the evaporated product, the extraction time is 15 min to 20 min. It can be understood that the extraction time is not limited to 15 min, 16 min, 17 min, 18 min, 19 min or 20 min.

[0076] In a specific example, after the step of recovering LiPF 6 in the waste battery electrolyte, there is further a step of recovering the metal chloro-bridged dimer:

[0077] Prepare a mixture by mixing the first organic layer solution, a strong acid, and water, perform extraction, prepare the second organic layer solution, and evaporate the second organic layer solution;

[0078] The strong acid is selected from one or more of hydrochloric acid, sulfuric acid, nitric acid, formic acid, trifluoroacetic acid, and trifluoromethanesulfonic acid.

[0079] In a specific example, the mixture further includes a metal chloride, and the metal chloride is selected from one or more of sodium chloride, potassium chloride, magnesium chloride, calcium chloride, and zinc chloride.

[0080] Further, the method for preparing the mixture in the step of recovering the metal chloro-bridged dimer includes:

[0081] Mix the first organic layer solution, hydrochloric acid, and water to prepare a mixture; or,

[0082] Mix the first organic layer solution, a strong acid other than hydrochloric acid, water, and a metal chloride to prepare a mixture, and collect the organic layer.

[0083] In a specific example, in the step of recovering the metal chloro-bridged dimer, the mass of the strong acid is 13% - 40% of the mass of the waste electrolyte solution.

[0084] In a specific example, in the step of recovering the metal chloro-bridged dimer, the mass of water is 30% - 100% of the mass of the waste electrolyte solution.

[0085] In a specific example, in the step of recovering the metal chloro-bridged dimer, the mass of the metal chloride is 5% - 20% of the mass of the metal chloro-bridged dimer.

[0086] In a specific example, in the step of recovering the metal chloro-bridged dimer, the extraction time is 10 min - 30 min. Further, the extraction time is 10 min - 20 min. It can be understood that the extraction time is not limited to 10 min, 11 min, 12 min, 13 min, 14 min, 15 min, 16 min, 17 min, 18 min, 19 min, or 20 min.

[0087] The above metal chloro-bridged dimer is based on the ion exchange principle, and uses a complex M of cationic iridium or platinum + to combine with the anion PF 6 - to form a stable and water-insoluble MPF 6 , to achieve the purpose of highly efficient separation of MPF 6 from Li, so that the recovery rates of Li + and PF 6 - in the electrolyte solution are both higher than 95%, and at the same time PF6 - With Li + They are respectively recovered with the product hexafluorophosphate and lithium chloride, and the purity of the recovered products is higher than 99%. Moreover, the present invention uses metal chloro-bridged dimers to recover Li in the waste electrolyte + and PF 6 - The steps have the advantages of simple operation, low equipment investment, environmental friendliness, quality controllability and easy industrialization, etc., can produce good economic and social benefits, and have broad application prospects.

[0088] The following provides specific embodiments to further illustrate in detail the application of the metal chloro-bridged dimers of the present invention. The raw materials involved in the following specific embodiments, unless otherwise specified, can all be obtained commercially.

[0089] The content of LiPF in the waste electrolyte 6 may vary slightly. Within the possible range of the content of LiPF in the waste electrolyte 6 , the ideal effect can be achieved by adopting the scheme of the present invention. The recovery method disclosed in the present invention is applicable to various waste electrolytes. In order to facilitate the description of the recovery method of the present invention, the mass percentage of LiPF in the waste electrolyte used in the examples 6 is 10%, the mass percentage of the organic solvent ((ethylene carbonate (EC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC))) is 85%, and the mass percentage of the additive (vinylene carbonate (VC) and N-methylpyrrolidone (NMP)) is 5%. This parameter does not limit the scope of the present invention.

[0090] Example 1

[0091] 100 g of waste electrolyte, 30 g of iridium (II) dichloro(2-phenylpyridine) dimer and 10 g of dichloromethane are mixed and dissolved, and reacted at 40 °C for 1.5 h, followed by solid-liquid separation to obtain a first solid and a first solution. The first solid is washed with dimethyl carbonate and dried at 80 °C for 5.0 h to obtain anhydrous lithium chloride, yield: 96.2%, purity: 99.2%;

[0092] The first solution is mixed with 8 g of serine, 4 g of sodium methoxide and 50 g of pure water and extracted for 20 min. The first organic layer solution and the aqueous layer solution are collected respectively. The aqueous layer solution is evaporated and concentrated to obtain sodium hexafluorophosphate, yield: 98.7%, purity: 99.1%. The first organic layer solution is mixed with 20 g of hydrochloric acid and 50 g of pure water and extracted for 10 min. The second organic layer solution is collected, and the second organic layer solution is evaporated to dryness to obtain iridium (II) dichloro(2-phenylpyridine) dimer, purity: 99.2%, yield: 98.9%.

[0093] XRD test is performed on the lithium chloride prepared above to obtainFigure 1 The diffraction pattern shown was compared with the corresponding product standard card, confirming that the product obtained in this example is indeed lithium chloride. NMR tests were performed on iridium(III) dichloro(2-phenylpyridine) dimer, and the Figure 2 NMR spectrum shown was obtained, confirming that the product obtained in this example is indeed iridium(III) dichloro(2-phenylpyridine) dimer.

[0094] The above-prepared lithium chloride, sodium hexafluorophosphate, and iridium(III) dichloro(2-phenylpyridine) dimer were analyzed by inductively coupled plasma atomic emission spectrometry (ICP) and chemical analysis. The contents of impurities such as sodium, potassium, calcium, iron, barium, copper, manganese, cobalt, and nickel in lithium chloride were all less than 5 ppm. The contents of impurities such as lithium, potassium, calcium, iron, barium, copper, manganese, cobalt, and nickel in sodium hexafluorophosphate were all less than 5 ppm. The contents of impurities such as sodium, potassium, calcium, iron, barium, copper, manganese, cobalt, and nickel in iridium(III) dichloro(2-phenylpyridine) dimer were all less than 5 ppm.

[0095] 29 g of iridium(III) dichloro(2-phenylpyridine) dimer recovered in Example 1 was mixed and dissolved with 96 g of waste electrolyte solution and 10 g of dichloromethane, and the reaction was carried out at 40 °C for 1.5 h. Solid-liquid separation was performed to obtain a first solid and a first solution. The first solid was washed with dimethyl carbonate and dried at 80 °C for 5.0 h to obtain anhydrous lithium chloride, with a yield of 95.9% and a purity of 99.0%.

[0096] Example 2

[0097] 300 g of waste electrolyte solution, 200 g of platinum(II) dichloro(2-phenylquinoline) dimer, 20 g of chloroform, and 30 g of dichloromethane were mixed and dissolved, and the reaction was carried out at 30 °C for 1.0 h. Solid-liquid separation was performed to obtain a first solid and a first solution. The first solid was washed with diethyl carbonate and dried at 90 °C for 3.0 h to obtain anhydrous lithium chloride, with a yield of 95.8% and a purity of 99.6%.

[0098] The first solution was mixed with 30 g of glycine, 12 g of sodium hydroxide, and 100 g of pure water and extracted for 15 min. The first organic layer solution and the aqueous layer solution were collected separately. The aqueous layer solution was evaporated and concentrated to obtain sodium hexafluorophosphate, with a yield of 98.2% and a purity of 99.3%. The first organic layer solution was mixed with 50 g of sulfuric acid, 25 g of sodium chloride, and 150 g of pure water and extracted for 20 min. The second organic layer solution was collected, and the second organic layer solution was evaporated to dryness to obtain platinum(II) dichloro(2-phenylquinoline) dimer, with a yield of 98.5%.

[0099] The above-prepared lithium chloride and sodium hexafluorophosphate were analyzed by inductively coupled plasma atomic emission spectrometry (ICP) and chemical analysis. The contents of impurities such as sodium, potassium, calcium, iron, barium, copper, manganese, cobalt, and nickel in lithium chloride were all less than 8 ppm. The contents of impurities such as lithium, potassium, calcium, iron, barium, copper, manganese, cobalt, and nickel in sodium hexafluorophosphate were all less than 6 ppm.

[0100] Example 3

[0101] 200 g of waste electrolyte solution, 150 g of iridium(III) 2-phenylisoquinoline dichloride bridge and 45 g of dichloromethane were mixed and dissolved, and the reaction was carried out at 20 °C for 1.5 h. Solid-liquid separation was performed to obtain a first solid and a first solution. The first solid was washed with dimethyl carbonate and dried at 60 °C for 4.0 h to obtain anhydrous lithium chloride, with a yield of 95.3% and a purity of 99.3%.

[0102] The first solution was mixed with 25 g of phenylalanine, 10 g of potassium hydroxide and 60 g of pure water, and then extracted for 15 min. The first organic layer solution and the aqueous layer solution were collected separately. The aqueous layer solution was evaporated and concentrated to obtain potassium hexafluorophosphate, with a yield of 98.4% and a purity of 99.0%. The first organic layer solution was mixed with 70 g of trifluoroacetic acid, 35 g of calcium chloride and 150 g of pure water, and then extracted for 15 min. The second organic layer solution was collected, and the second organic layer solution was evaporated to dryness to obtain iridium(III) 2-phenylisoquinoline dichloride bridge, with a yield of 98.9%.

[0103] The prepared lithium chloride and potassium hexafluorophosphate were analyzed by inductively coupled plasma atomic emission spectrometry (ICP) and chemical analysis. The contents of impurities such as sodium, potassium, calcium, iron, barium, copper, manganese, cobalt and nickel in lithium chloride were all less than 10 ppm, and the contents of impurities such as lithium, sodium, calcium, iron, barium, copper, manganese, cobalt and nickel in potassium hexafluorophosphate were all less than 10 ppm.

[0104] Example 4

[0105] 500 g of waste electrolyte solution, 380 g of platinum(IV) 2-phenylisoquinoline dichloride bridge and 130 g of chloroform were mixed and dissolved, and the reaction was carried out at 10 °C for 2.0 h. Solid-liquid separation was performed to obtain a first solid and a first solution. The first solid was washed with diethyl carbonate and dried at 90 °C for 2.0 h to obtain anhydrous lithium chloride, with a yield of 95.8% and a purity of 99.3%.

[0106] The first solution was mixed with 80 g of histidine, 18 g of sodium methoxide and 200 g of pure water, and then extracted for 15 min. The first organic layer solution and the aqueous layer solution were collected separately. The aqueous layer solution was evaporated and concentrated to obtain sodium hexafluorophosphate, with a yield of 98.3% and a purity of 99.1%. The first organic layer solution was mixed with 100 g of formic acid, 40 g of potassium chloride and 300 g of pure water, and then extracted for 20 min. The second organic layer solution was collected, and the second organic layer solution was evaporated to dryness to obtain platinum(IV) 2-phenylisoquinoline dichloride bridge, with a yield of 98.8%.

[0107] The prepared lithium chloride and sodium hexafluorophosphate were analyzed by inductively coupled plasma atomic emission spectrometry (ICP) and chemical analysis. The contents of impurities such as sodium, potassium, calcium, iron, barium, copper, manganese, cobalt and nickel in lithium chloride were all less than 12 ppm, and the contents of impurities such as lithium, potassium, calcium, iron, barium, copper, manganese, cobalt and nickel in sodium hexafluorophosphate were all less than 12 ppm.

[0108] Comparative Example 1

[0109] The waste electrolyte is processed according to the same steps and process as in Example 1, except that the raw material does not use the metal chloro-bridged dimer iridium(III) 2-phenylpyridine dichloride bridge but uses iridium(III) chloride, and other operations are the same as in Example 1.

[0110] The prepared lithium chloride and sodium hexafluorophosphate are analyzed by inductively coupled plasma atomic emission spectrometry (ICP) and chemical analysis. The yield of lithium chloride is 15.3%, and the yield of sodium hexafluorophosphate is 98.1%. Among them, the contents of impurities such as sodium, potassium, calcium, iron, barium, copper, manganese, cobalt, and nickel in lithium chloride are all less than 12 ppm; the contents of impurities such as potassium, calcium, iron, barium, copper, manganese, cobalt, and nickel in sodium hexafluorophosphate are all less than 12 ppm, and the lithium impurity content > 0.5%.

[0111] Comparative Example 2

[0112] The waste electrolyte is processed according to the same steps and process as in Example 1, except that the amount of the metal chloro-bridged dimer added is 10 g, and other operations are the same as in Example 1.

[0113] The prepared lithium chloride and sodium hexafluorophosphate are analyzed by inductively coupled plasma atomic emission spectrometry (ICP) and chemical analysis. The yield of lithium chloride is 56.3%, and the yield of sodium hexafluorophosphate is 98.1%. Among them, the contents of impurities such as sodium, potassium, calcium, iron, barium, copper, manganese, cobalt, and nickel in lithium chloride are all less than 10 ppm; the contents of impurities such as potassium, calcium, iron, barium, copper, manganese, cobalt, and nickel in sodium hexafluorophosphate are all less than 8 ppm, and the lithium impurity content > 0.3%.

[0114] Comparative Example 3

[0115] The waste electrolyte is processed according to the same steps and process as in Example 1, except that the reaction temperature after mixing with dichloromethane is 90 °C, and other operations are the same as in Example 1.

[0116] The prepared lithium chloride and sodium hexafluorophosphate are analyzed by inductively coupled plasma atomic emission spectrometry (ICP) and chemical analysis. The yield of lithium chloride is 98.7%, and the yield of sodium hexafluorophosphate is 83.2%. Among them, the contents of impurities such as sodium, potassium, calcium, iron, barium, copper, manganese, cobalt, and nickel in lithium chloride are all less than 10 ppm; the contents of impurities such as lithium, potassium, calcium, iron, barium, copper, manganese, cobalt, and nickel in sodium hexafluorophosphate are all less than 12 ppm.

[0117] Comparative Example 4

[0118] The waste electrolyte is processed according to the same steps and process as in Example 1, except that no soluble base is added, and other operations are the same as in Example 1.

[0119] The prepared lithium chloride and sodium hexafluorophosphate were analyzed by inductively coupled plasma atomic emission spectrometry (ICP) and chemical analysis. The yield of lithium chloride was 98.8%, and the yield of sodium hexafluorophosphate was 21.4%. Among them, the contents of impurities such as sodium, potassium, calcium, iron, barium, copper, manganese, cobalt, and nickel in lithium chloride were all less than 8 ppm; the contents of impurities such as lithium, potassium, calcium, iron, barium, copper, manganese, cobalt, and nickel in sodium hexafluorophosphate were all less than 10 ppm.

[0120] Comparative Example 5

[0121] The waste electrolyte was treated according to the same steps and process as in Example 1, except that no amino acid was added, and other operations were the same as in Example 1.

[0122] The prepared lithium chloride and sodium hexafluorophosphate were analyzed by inductively coupled plasma atomic emission spectrometry (ICP) and chemical analysis. The yield of lithium chloride was 98.8%, and the yield of sodium hexafluorophosphate was 15.3%. Among them, the contents of impurities such as sodium, potassium, calcium, iron, barium, copper, manganese, cobalt, and nickel in lithium chloride were all less than 10 ppm; the contents of impurities such as lithium, potassium, calcium, iron, barium, copper, manganese, cobalt, and nickel in sodium hexafluorophosphate were all less than 10 ppm.

[0123] Comparative Example 6

[0124] The waste electrolyte was treated according to the same steps and process as in Example 1, except that the raw material did not use the metal chloro-bridged dimer iridium(III) 2-phenylpyridine dichloro-bridged, but used nickel(II) hexammine dichloride, and other operations were the same as in Example 1.

[0125] The prepared lithium chloride and sodium hexafluorophosphate were analyzed by inductively coupled plasma atomic emission spectrometry (ICP) and chemical analysis. The yield of lithium chloride was 44.3%, and the yield of sodium hexafluorophosphate was 67.1%. Among them, the contents of impurities such as sodium, potassium, calcium, iron, barium, copper, manganese, cobalt in lithium chloride were all less than 15 ppm, and the nickel content > 0.7%; the contents of impurities such as potassium, calcium, iron, barium, copper, manganese, cobalt in sodium hexafluorophosphate were all less than 15 ppm, and the lithium impurity content > 0.4%.

[0126] Comparative Example 7

[0127] The waste electrolyte was treated according to the same steps and process as in Example 1, except that the raw material did not use the metal chloro-bridged dimer iridium(III) 2-phenylpyridine dichloro-bridged, but used tetrabutylammonium chloride, and other operations were the same as in Example 1.

[0128] The prepared lithium chloride and sodium hexafluorophosphate were analyzed by inductively coupled plasma atomic emission spectrometry (ICP) and chemical analysis. The yield of lithium chloride was 59.8%, and the yield of sodium hexafluorophosphate was 76.6%. Among them, the contents of impurities such as sodium, potassium, calcium, iron, barium, copper, manganese, cobalt, and nickel in lithium chloride were all less than 15 ppm; the contents of impurities such as potassium, calcium, iron, barium, copper, manganese, cobalt, and nickel in sodium hexafluorophosphate were all less than 15 ppm, and the lithium impurity content > 0.45%.

[0129] Comparative Example 8

[0130] The spent electrolyte was treated according to the same steps and process as in Example 1, except that anhydrous lithium chloride was washed with water, and other operations were the same as in Example 1.

[0131] The prepared lithium chloride and sodium hexafluorophosphate were analyzed by inductively coupled plasma atomic emission spectrometry (ICP) and chemical analysis. The yield of lithium chloride was 33.6%, and the yield of sodium hexafluorophosphate was 98.6%. Among them, the contents of impurities such as sodium, potassium, calcium, iron, barium, copper, manganese, cobalt, and nickel in lithium chloride were all less than 15 ppm; the contents of impurities such as potassium, calcium, iron, barium, copper, manganese, cobalt, and nickel in sodium hexafluorophosphate were all less than 15 ppm, and the lithium impurity content > 0.45%.

[0132] Result analysis:

[0133] From the results of Example 1 and Comparative Example 1, it can be seen that in the steps of Comparative Example 1, the yield of sodium hexafluorophosphate remained basically unchanged, but the purity was low, and the yield of lithium chloride decreased significantly, failing to achieve the purpose of the present invention.

[0134] From the results of Example 1 and Comparative Example 2, it can be seen that in the steps of Comparative Example 2, the amount of metal chloro-bridged dimer added was 10 g, the yield of sodium hexafluorophosphate remained basically unchanged, but the purity was low, and the yield of lithium chloride decreased significantly, failing to achieve the purpose of the present invention.

[0135] From the results of Example 1 and Comparative Example 3, it can be seen that in the steps of Comparative Example 3, the reaction temperature was 90 °C, the purity and yield of lithium chloride remained basically unchanged, but the yield of sodium hexafluorophosphate decreased significantly, failing to achieve the purpose of the present invention.

[0136] From the results of Example 1 and Comparative Example 4, it can be seen that in the steps of Comparative Example 4, no soluble base was added, the purity and yield of lithium chloride remained basically unchanged, but the yield of sodium hexafluorophosphate decreased significantly, failing to achieve the purpose of the present invention.

[0137] From the results of Example 1 and Comparative Example 5, it can be seen that in the steps of Comparative Example 5, no amino acid was added, the purity and yield of lithium chloride remained basically unchanged, but the yield of sodium hexafluorophosphate decreased significantly, failing to achieve the purpose of the present invention.

[0138] From the results of Example 1 and Comparative Example 6, it can be seen that in the steps of Comparative Example 6, nickel dichloride hexammine was used as the metal chloro-bridged dimer. Since nickel impurities would be recovered together with lithium chloride, the purity of lithium chloride decreased, and the yield also decreased significantly. At the same time, the yield and purity of sodium hexafluorophosphate also decreased significantly, failing to achieve the purpose of the present invention.

[0139] As can be seen from the results of Example 1 and Comparative Example 7, in Comparative Example 7, tetrabutylammonium chloride was used as the metal chloro-bridged dimer in the steps. The purity of lithium chloride remained unchanged, but the yield decreased significantly. Moreover, the yield and purity of sodium hexafluorophosphate decreased significantly, failing to achieve the object of the present invention.

[0140] As can be seen from the results of Example 1 and Comparative Example 8, if water washing is used in Comparative Example 8, the yield of lithium chloride will be reduced, and the yield is lower than 95%, failing to achieve the object of the present invention.

[0141] The technical features of the above embodiments can be combined arbitrarily. For the sake of concise description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0142] The above-described embodiments only represent several implementation manners of the present invention, which are convenient for understanding the technical solutions of the present invention specifically and in detail. However, it should not be construed as a limitation on the protection scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. It should be understood that the technical solutions obtained by those skilled in the art through logical analysis, reasoning or limited experiments based on the technical solutions provided by the present invention are all within the protection scope of the appended claims of the present invention. Therefore, the protection scope of the present invention patent should be subject to the content of the appended claims, and the specification can be used to interpret the content of the claims.

Claims

1. Application of a metal chloro-bridged dimer, characterized in that, The metal chloro-bridged dimer is applied to the recovery of LiPF in waste battery electrolyte 6 , the recovery of LiPF in waste battery electrolyte 6 The steps are as follows: mix the metal chloro-bridged dimer, a first organic solvent and the waste electrolyte solution, filter to prepare a first solid and a first solution, wash the first solid with a second organic solvent and then dry it, and recover the dried product, mix the first solution, an amino acid, a soluble base and water, extract to prepare a first organic layer solution and an aqueous layer solution, and evaporate the aqueous layer solution to recover the evaporation product; wherein, the first organic solvent is selected from one or more of dichloromethane and chloroform; the second organic solvent is selected from one or more of dimethyl carbonate and diethyl carbonate; the structural general formula of the metal chloro-bridged dimer is: ； Wherein, R 1 and R 2 each independently selected from , , , or , A is selected from the group represented by any one of (B-1) to (B-2): , X 1 With X 2 Each independently selected from Ir or Pt, n and m are selected from 1 or 2, Y 1 Each occurrence is independently selected from N or CR 3 ; R 3 Each occurrence is independently selected from: -H, -D or a straight-chain alkyl group having 1 to 5 C atoms.

2. The application of the metal chloro-bridged dimer according to claim 1, characterized in that, the structure of the metal chloro-bridged dimer is one of those shown in formulas (1-1) and (1-6): 。 3. The application of the metal chloro-bridged dimer according to claim 1, characterized in that, the composition of the waste electrolyte solution includes, by weight percentage: 5% - 15% of lithium hexafluorophosphate, 80% - 90% of an organic solvent, and 1% - 8% of an additive.

4. The application of the metal chloro-bridged dimer according to claim 1, characterized in that, the mass of the metal chloro-bridged dimer is 30% - 80% of the mass of the waste electrolyte solution, and the mass of the first organic solvent is 20% - 50% of the mass of the metal chloro-bridged dimer.

5. The application of the metal chloro-bridged dimer according to claim 1, characterized in that, the time for mixing the metal chloro-bridged dimer, the first organic solvent and the waste electrolyte solution is 0.5 h - 2.0 h, and the temperature is 10°C - 40°C.

6. The application of the metal chloro-bridged dimer according to claim 1, characterized in that, the amino acid is selected from one or more of glycine, alanine, valine, leucine, isoleucine, methionine, proline, tryptophan, serine, tyrosine, cysteine, phenylalanine, asparagine, glutamine, threonine, aspartic acid, glutamic acid, lysine, arginine and histidine.

7. The application of the metal chloro-bridged dimer according to claim 1, characterized in that, the mass of the amino acid is 6% - 13% of the mass of the waste electrolyte solution, the mass of the soluble base is 3% - 8% of the mass of the waste electrolyte solution, and the mass of water is 20% - 50% of the mass of the waste electrolyte solution.

8. The application of the metal chloro-bridged dimer according to claim 1, characterized in that, the soluble base is selected from one or more of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium methoxide and potassium ethoxide.

9. The application of the metal chloro-bridged dimer according to claim 1, characterized in that, the extraction time is 10 min - 30 min.

10. The application of the metal chloro-bridged dimer according to claim 1, characterized in that, Recovering LiPF in the waste electrolyte of recycled batteries 6 After the step of mix the first organic layer solution, a strong acid and water to prepare a mixture, extract the mixture to prepare a second organic layer solution, and evaporate the second organic layer solution; Wherein the strong acid is selected from one or more of hydrochloric acid, sulfuric acid, nitric acid, formic acid, trifluoroacetic acid, and trifluoromethanesulfonic acid.

11. The application of the metal chloro-bridged dimer according to claim 10, characterized in that in the step of recovering the metal chloro-bridged dimer, it has at least one of the following characteristics: (1) The mixed solution further includes metal chlorides, and the metal chlorides are selected from one or more of sodium chloride, potassium chloride, magnesium chloride, calcium chloride, and zinc chloride; (2) The mass of the strong acid is 13% - 40% of the mass of the waste electrolyte solution; (3) The mass of water is 30% - 100% of the mass of the waste electrolyte solution; (4) The mass of the metal chloride is 5% - 20% of the mass of the metal chloro-bridged dimer; (5) The extraction time is 10 min - 30 min.

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