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CN-116730306-B - Desulfurization method of sulfur-containing metal salt, battery-grade metal salt, preparation method and application thereof

CN116730306BCN 116730306 BCN116730306 BCN 116730306BCN-116730306-B

Abstract

The invention relates to the technical field of secondary battery anode materials, in particular to a sulfur-containing metal salt desulfurization method, a battery-grade metal salt and a preparation method and application thereof. The desulfurization method of the sulfur-containing metal salt provided by the invention can effectively reduce the sulfur content in the metal salt, and has the advantages of good desulfurization effect, low cost, high repeatability, few byproducts and the like. Particularly, the S impurity content in the material can be effectively reduced to below 800ppm, and the requirement of 800ppm sulfur impurity of battery grade phosphate or carbonate can be met.

Inventors

  • LIU MIAN
  • Li yineng
  • KONG LINGYONG
  • ZHENG LICONG

Assignees

  • 曲靖市德方纳米科技有限公司

Dates

Publication Date
20260512
Application Date
20230606

Claims (12)

  1. 1. A method for desulfurizing a sulfur-containing metal salt, comprising the steps of: (a) Mixing sulfur-containing metal salt with organic acid to obtain acid solution, filtering the acid solution to obtain first clear liquid; Wherein the sulfur-containing metal salt comprises phosphate and/or carbonate, and the organic acid comprises oxalic acid and/or benzoic acid; the phosphate comprises at least one of lithium phosphate, manganese phosphate, iron phosphate, cobalt phosphate, titanium phosphate, nickel phosphate, magnesium phosphate and aluminum phosphate; the carbonate comprises at least one of lithium carbonate, manganese carbonate, cobalt carbonate and nickel carbonate; (b) Adding a precipitant into the first clear liquid, regulating the pH value of the solution to be higher than the pH value of the sulfur-containing metal salt precipitate, and filtering to obtain battery-level metal salt and second clear liquid; wherein when the sulfur-containing metal salt is phosphate, the precipitant is ammonia water, and when the sulfur-containing metal salt is carbonate, the precipitant is a mixed solution of ammonium carbonate and ammonia water.
  2. 2. The desulfurization method of a sulfur-containing metal salt according to claim 1, characterized by comprising at least one of the following features (1) to (4) in step (a): (1) The mass ratio of the sulfur-containing metal salt to the organic acid is 1 (1-50); (2) In the step of mixing the sulfur-containing metal salt and the organic acid, the pH value of a solution system is=1-5; (3) In the mixing process, the temperature of the solution system is 0-50 ℃; (4) The mixing time is 1-12 h.
  3. 3. The desulfurization method of a sulfur-containing metal salt according to claim 1, characterized by comprising at least one of the following features (1) to (3) in step (b): (1) The mass ratio of the addition amount of the precipitant to the sulfur-containing metal salt is (1-10) 1; (2) In the process of adjusting the pH of the solution, the temperature of a solution system is 20-90 ℃; (3) And in the process of regulating the pH of the solution, stirring the solution, wherein the stirring speed is 200-600 rpm.
  4. 4. The desulfurization method of a sulfur-containing metal salt according to claim 1, wherein in the step (b), after the step of adjusting the pH of the solution, an aging process of the crystals is further included, and the aging time is 1 to 12 hours.
  5. 5. The method for desulfurizing a sulfur-containing metal salt according to claim 4, wherein in said aging in step (b), the temperature of the solution system is 20 to 90 ℃.
  6. 6. The desulfurization method of a sulfur-containing metal salt according to claim 1, characterized in that in step (b), the pH of the sulfur-containing metal salt precipitate comprises at least one of the following features (1) to (12): (1) The pH value of the lithium phosphate precipitate is more than or equal to 5.5; (2) The pH value of the manganese phosphate precipitate is more than or equal to 7; (3) The pH value of the ferric phosphate sediment is more than or equal to 2; (4) The pH value of the cobalt phosphate precipitate is more than or equal to 6; (5) The pH value of the titanium phosphate sediment is more than or equal to 5; (6) The pH value of the nickel phosphate sediment is more than or equal to 6; (7) The pH value of the magnesium phosphate sediment is more than or equal to 8; (8) The pH value of the aluminum phosphate precipitate is more than or equal to 4; (9) The pH value of the lithium carbonate sediment is more than or equal to 9; (10) The pH value of the manganese carbonate sediment is more than or equal to 6; (11) The pH value of the cobalt carbonate sediment is more than or equal to 6; (12) The pH value of the nickel carbonate sediment is more than or equal to 8.
  7. 7. The desulfurization method of a sulfur-containing metal salt according to claim 6, characterized in that in step (b), the pH of the sulfur-containing metal salt precipitate comprises at least one of the following features (1) to (12): (1) The pH of the lithium phosphate precipitate is 5.5-10; (2) The pH value of the manganese phosphate precipitate is 7-10; (3) The pH of the ferric phosphate precipitate is 2-4; (4) The pH of the cobalt phosphate precipitate is 6-9; (5) The pH value of the titanium phosphate precipitate is 5-8; (6) The pH value of the nickel phosphate precipitate is 6-9; (7) The pH value of the magnesium phosphate precipitate is 8-10; (8) The pH value of the aluminum phosphate precipitate is 4-7; (9) The pH of the lithium carbonate precipitate is 9-11; (10) The pH value of the manganese carbonate precipitate is 6-8; (11) The pH of the cobalt carbonate precipitate is 6-8; (12) The pH of the nickel carbonate precipitate is 8-10.
  8. 8. The method for desulfurizing a sulfur-containing metal salt according to claim 1, wherein in the step (b), the filtration is a thermal filtration, and the temperature of the thermal filtration is 50 to 90 ℃.
  9. 9. The desulfurization method of a sulfur-containing metal salt according to claim 1, characterized by further comprising: (c) Crystallizing and concentrating the second clear solution obtained in the step (b) to obtain ammonium salt of the organic acid, deaminizing the ammonium salt of the organic acid, and recycling the organic acid and ammonia gas.
  10. 10. The method for desulfurizing a sulfur-containing metal salt according to claim 9, wherein said crystallizing and concentrating comprises performing primary crystallization, concentrating, and performing secondary crystallization.
  11. 11. The method for desulfurizing a sulfur-containing metal salt according to claim 10, wherein the temperature of the primary crystallization and/or the secondary crystallization is-5 ℃ to 5 ℃ for 2 to 24 hours.
  12. 12. The method for desulfurizing a sulfur-containing metal salt according to claim 9, wherein the deamination temperature is 90 to 140 ℃ for 2 to 24 hours.

Description

Desulfurization method of sulfur-containing metal salt, battery-grade metal salt, preparation method and application thereof Technical Field The invention relates to the technical field of secondary battery anode materials, in particular to a desulfurization method of sulfur-containing metal salt, a battery-grade metal salt, a preparation method and application thereof. Background In recent years, with the increasing increase of the influence of fossil energy on the earth environment, clean energy is being widely used as a substitute, and lithium ion batteries are widely accepted due to the advantages of high energy density, light weight, small weight, no memory effect, long cycle life, environmental friendliness and the like. The lithium iron phosphate is used as an electrode positive electrode material, has higher reversible charge-discharge specific capacity, has the advantages of wide raw material sources, low pollution, good safety, long cycle life and the like, and is an ideal power-shaped and energy-storage-shaped lithium ion battery positive electrode material at present. On the basis, the lithium iron manganese phosphate can further improve the compaction density and improve the energy density level of the battery. The lithium iron manganese phosphate (LiFe xMn1-xPO4) has the double characteristics of safety and stability of the lithium iron phosphate and high voltage of the lithium manganese phosphate. The crystal structure of the lithium iron phosphate and the crystal structure of the lithium iron phosphate have both manganese and iron, the proportion of iron and manganese can be adjusted, and the structural stability is good. Even if lithium ions are completely extracted in the charging process, the structure collapse can not be caused. However, lithium iron manganese phosphate is a double-voltage platform and has certain instability. The cost of lithium iron phosphate raw materials depends on upstream lithium sources, phosphorus sources, iron sources, and the like. The cost reduction paths of different process routes of raw materials are different. Lithium carbonate, manganese carbonate, ferric phosphate, manganese phosphate and lithium phosphate are used as the cathode raw materials of lithium iron phosphate/lithium manganese iron phosphate, so that the manufacturing cost of the lithium ion battery can be reduced. The lithium carbonate, the manganese phosphate and the lithium phosphate are mostly prepared from ores, the preparation method takes the sulfuric acid method as an example, the lithium phosphate is taken as the main process of extracting lithium from the lithium ores at present, the sulfuric acid method is adopted as the main process, the lithium ores are leached after conversion roasting and sulfating roasting, lime is added to adjust the pH value to be neutral, a large amount of impurity metal ions in the lithium ores can be removed, pure lithium sulfate liquid is obtained after organic extraction, and the lithium phosphate is obtained after phosphorus supplementing and pH value adjustment. The prior patent CN112573546A provides a new method for reducing the sulfate radical content of lithium carbonate directly produced by lithium sulfate and sodium (potassium) carbonate, which selects 'pre-precipitation supplement impurity removal' for assistance, adopts 'reverse feeding, no circulation of mother liquor' and 'high-efficiency desorption', can lead the sulfate radical of industrial-grade lithium carbonate to be reduced to 0.03%, the main content to be increased to 2.5N, the sulfate radical of battery grade to be reduced to 0.010%, the main content to be stable to 3N and even reach 3.5N limit, and the reverse feeding and high-efficiency desorption process adopted by the scheme is only suitable for sulfur removal of lithium phosphate prepared from lithium sulfate, and is not suitable for S removal of high-sulfur lithium phosphate. The prior patent CN102249340A provides a method for preparing manganese sulfate, manganese phosphate and calcium sulfate, which comprises the steps of reacting pure manganese sulfate solution with calcium phosphate solution under stirring, filtering reaction products to obtain a calcium sulfate filter cake and manganese phosphate filtrate, distilling the manganese phosphate filtrate under reduced pressure to obtain a saturated manganese phosphate solution, cooling and crystallizing to obtain manganese phosphate hydrate, drying and crushing to obtain a manganese phosphate crystal product, and washing, drying and crushing the calcium sulfate filter cake to obtain a calcium sulfate dihydrate product. This scheme, the sulfur removal process produces a significant amount of calcium sulfate by-product. In view of this, the present invention has been made. Disclosure of Invention The first object of the present invention is to provide a desulfurization method for sulfur-containing metal salts, which aims at solving the problems of poor sulfur removal effect, high c