Search

CN-121974940-A - Preparation method of electrolyte salt lithium difluoro oxalate borate for lithium ion battery

CN121974940ACN 121974940 ACN121974940 ACN 121974940ACN-121974940-A

Abstract

The application relates to the technical field of chemical synthesis, and particularly discloses a preparation method of electrolyte salt lithium difluoro oxalato borate for a lithium ion battery. The application discloses a preparation method of lithium difluoro oxalate borate, which comprises the following steps of mixing oxalic acid, lithium fluoride, boric acid, lithium hydroxide, boron trifluoride complex and an organic solvent, heating for reaction, filtering to obtain a reaction solution, wherein the reaction temperature is 50-120 ℃ and the reaction time is 4-48 hours, concentrating the reaction solution in vacuum until white solid is separated out, cooling, adding a poor solvent for crystallization, filtering to obtain a wet product, and vacuum drying to obtain a target product. The novel preparation method of the lithium difluorooxalate borate provided by the application is simple, high in product conversion rate, free of other impurities and environment-friendly.

Inventors

  • CAI MINGJUN
  • SONG NAN
  • HAN JIAHAO
  • WANG YONGQIANG
  • LI XUEWEN
  • ZHOU FUPENG

Assignees

  • 烟台禹辰新材料技术研发有限公司

Dates

Publication Date
20260505
Application Date
20260116

Claims (10)

  1. 1. The preparation method of the lithium difluorooxalato borate is characterized by comprising the following steps: (1) Mixing oxalic acid, lithium fluoride, boric acid, lithium hydroxide, boron trifluoride complex and an organic solvent, heating for reaction, and filtering to obtain a reaction solution containing LiDFOB, wherein the reaction temperature is 50-120 ℃ and the reaction time is 4-48 h; (2) Concentrating the reaction solution containing LiDFOB in vacuum until white solid is separated out, cooling, adding a poor solvent for crystallization, filtering to obtain a wet product, and drying in vacuum to obtain a target product.
  2. 2. The method for producing lithium difluoroborate according to claim 1, wherein the boron trifluoride complex is one or more selected from the group consisting of boron trifluoride diethyl carbonate, boron trifluoride acetonitrile, boron trifluoride dimethyl carbonate, boron trifluoride diethyl etherate and boron trifluoride ethylene carbonate.
  3. 3. The method for preparing lithium difluorooxalato borate according to claim 1, wherein the molar ratio of oxalic acid to lithium fluoride, boric acid, lithium hydroxide and boron trifluoride complex is 1:0.5-0.55:0.5-0.55.
  4. 4. The method for preparing lithium difluorooxalato borate according to claim 1, wherein the molar ratio of oxalic acid to lithium fluoride, boric acid, lithium hydroxide and boron trifluoride complex is 1:0.5-0.52:0.5-0.52:0.525-0.55.
  5. 5. The preparation method of the lithium difluoroborate according to claim 1, wherein the organic solvent is one or more selected from the group consisting of an ester solvent, an ether solvent and a nitrile solvent, wherein the ester solvent is selected from the group consisting of dimethyl carbonate and diethyl carbonate, the ether solvent is selected from the group consisting of diethyl ether and ethylene glycol dimethyl ether, and the nitrile solvent is selected from the group consisting of acetonitrile.
  6. 6. The method for preparing lithium difluorooxalato borate according to claim 1, wherein the reaction temperature is 60-100 ℃ and the reaction time is 6-16 h.
  7. 7. The preparation method of the lithium difluoroborate as claimed in claim 1, wherein the technological parameters of vacuum concentration are that the pressure is-0.09 to-0.095 Mpa and the temperature is 50-80 ℃.
  8. 8. The method for preparing lithium difluoroborate according to claim 1, wherein the temperature of the cooling is 0-30 ℃.
  9. 9. The method for preparing lithium difluoroborate according to claim 1, wherein the poor solvent is one or more selected from the group consisting of dichloromethane, chloroform, toluene, xylene, and n-heptane.
  10. 10. The preparation method of the lithium difluoroborate as claimed in claim 1, wherein the technological parameters of vacuum drying are that the pressure is-0.095 to-0.1 Mpa and the drying temperature is 70-110 ℃.

Description

Preparation method of electrolyte salt lithium difluoro oxalate borate for lithium ion battery Technical Field The application relates to the technical field of chemical synthesis, in particular to a preparation method of electrolyte salt lithium difluoro oxalato borate for a lithium ion battery. Background The electrolyte is one of the main components of lithium ion battery and has been the main research points in this technical field. LiPF 6 used in commercial scale at present has insufficient thermal stability, is easily decomposed to generate highly corrosive HF, and has a harmful effect on the performance of the electrode. Lithium difluorooxalato borate (LiDFOB) is used as an electrolyte additive, so that the electrolyte additive not only has good high-low temperature performance, but also can form a stable SEI film structure on the surface of an electrode material, and the cycle performance of a lithium ion battery is obviously improved. At present, the preparation methods of LiDFOB at home and abroad are classified into a boron trifluoride (BF 3) complex method and a lithium tetrafluoroborate (LiBF 4) method. The BF 3 complex method is to react BF 3 complex and lithium oxalate as raw materials with diethyl ether or carbonic ester as solvent to obtain a mixed crude product of LiBF 4 and LiDFOB, and recrystallizing for multiple times to obtain a target product. Because LiBF 4 and LiDFOB have similar solubility in common solvents, the product is difficult to separate and has low yield. The LiBF 4 method takes oxalic acid and BF 3 complex as raw materials, adds a catalyst (silicon tetrachloride, aluminum trichloride, silicon tetrabromide or boron tribromide) into solvents such as carbonic acid esters, acetonitrile and the like, and reacts in a dry environment to obtain a solution containing LiDFOB, and the solution is concentrated and then is reduced by Wen Xijing, and a product with the purity of 99.9% can be obtained after vacuum drying. However, a large amount of chloride ions or bromide ions are introduced into the product of the method, a large amount of acid gases are generated in the reaction process, and the tail gas treatment is complicated. Therefore, how to provide a preparation method of lithium difluoroborate with high conversion rate, high product purity and yield and no corrosive gas generated in the reaction process is a technical problem to be solved urgently by the technicians in the field. Disclosure of Invention In order to solve the technical problems, the application provides a preparation method of electrolyte salt lithium difluoro oxalato borate for a lithium ion battery. The application provides a preparation method of lithium difluoro oxalate borate, which comprises the following steps: (1) Mixing oxalic acid, lithium fluoride, boric acid, lithium hydroxide, boron trifluoride complex and an organic solvent, heating for reaction, and filtering to obtain a reaction solution containing LiDFOB, wherein the reaction temperature is 50-120 ℃ and the reaction time is 4-48 h; (2) Concentrating the reaction solution containing LiDFOB in vacuum until white solid is separated out, cooling, adding a poor solvent for crystallization, filtering to obtain a wet product, and drying in vacuum to obtain a target product. The reaction formula of the preparation method of the lithium difluoroborate provided by the application is shown as a formula (1). (1) According to the method, oxalic acid, lithium fluoride, boric acid, lithium hydroxide, boron trifluoride complex and an organic solvent are used as raw materials to prepare the lithium difluorooxalate borate through a one-pot method, the traditional process is remarkably simplified, the high conversion rate of the product is realized through optimizing the reaction conditions, more importantly, no other impurities are generated in the whole reaction process, the purity of the product is higher, the complicated purification step is not needed, and the production cost and the energy consumption are directly reduced. The method is green and environment-friendly, completely accords with the green chemical concept, greatly reduces the environmental protection investment and the operation cost of enterprises, realizes win-win of economic benefit and environmental benefit, and has remarkable industrial application value. Preferably, the boron trifluoride complex is selected from one or more of boron trifluoride diethyl carbonate, boron trifluoride acetonitrile, boron trifluoride dimethyl carbonate, boron trifluoride diethyl ether and boron trifluoride ethylene carbonate. Preferably, the molar ratio of oxalic acid to lithium fluoride, boric acid, lithium hydroxide and boron trifluoride complex is 1:0.5-0.55:0.5-0.55. Preferably, the molar ratio of oxalic acid to lithium fluoride, boric acid, lithium hydroxide and boron trifluoride complex is 1:0.5-0.52:0.5-0.52:0.525-0.55. In a specific embodiment, the molar ratio of oxalic acid to lithium fluoride, boric