CN111943970B - Preparation method of lithium dioxalate borate - Google Patents
Preparation method of lithium dioxalate borate Download PDFInfo
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- CN111943970B CN111943970B CN202010916092.3A CN202010916092A CN111943970B CN 111943970 B CN111943970 B CN 111943970B CN 202010916092 A CN202010916092 A CN 202010916092A CN 111943970 B CN111943970 B CN 111943970B
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07F—ACYCLIC, CARBOCYCLIC OR HETEROCYCLIC COMPOUNDS CONTAINING ELEMENTS OTHER THAN CARBON, HYDROGEN, HALOGEN, OXYGEN, NITROGEN, SULFUR, SELENIUM OR TELLURIUM
- C07F5/00—Compounds containing elements of Groups 3 or 13 of the Periodic System
- C07F5/02—Boron compounds
- C07F5/022—Boron compounds without C-boron linkages
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Abstract
The invention discloses a preparation method of lithium dioxalate borate, which comprises the following steps: mixing oxalic acid with a boron-containing compound, reacting at 40-130 ℃ under normal pressure and mechanical stirring, and vacuum drying at 60-220 ℃; during the reaction, oxalic acid and a boron-containing compound generate oxalic acid boric acid; cooling the reactant obtained in the steps to room temperature, adding a polar solvent, and stirring for dissolution; filtering the solution obtained in the steps, adding a lithium salt compound into the filtrate, and reacting at room temperature to reflux temperature; the reaction of the oxalic acid boric acid and the lithium salt compound to generate lithium oxalic acid boric acid; after the reaction is finished, cooling the reaction liquid to room temperature, filtering, concentrating, crystallizing and drying filtrate in sequence to obtain a solid lithium dioxalate borate product. The method has the advantages of mild reaction, simple process, low production cost, economy, environmental protection and high reaction yield, can obtain high-purity lithium dioxalate borate, and is relatively suitable for industrial production.
Description
Technical Field
The invention belongs to the technical field of synthesis of electrolyte lithium salt used in the lithium ion battery industry, and particularly relates to a preparation method of lithium difluoro oxalate borate.
Background
The lithium ion battery has the advantages of high energy density, high output voltage, long cycle life, no memory effect, small environmental pollution and the like, is a secondary battery with the most attractive and development potential, and is the first choice of power supplies of hybrid electric vehicles and pure electric vehicles. The electrolyte is one of the basic key materials of the lithium ion battery, and as the main component of the electrolyte, the performance of the electrolyte plays a decisive role for the electrolyte and the lithium ion battery.
Lithium hexafluorophosphate, which is the most mature and most commonly used electrolyte salt in current commercialization, has certain drawbacks. Lithium hexafluorophosphate is easy to hydrolyze, has poor thermal stability, and can generate decomposition reaction under trace moisture to generate corrosive hydrofluoric acid, which can cause the performance attenuation and failure of the lithium ion battery.
The lithium dioxalate LiBOB is used as a novel electrolyte lithium salt, has good chemical property and stability, and the thermal decomposition temperature can reach 300 ℃. The addition of LiBOB can form stable SEI film on the carbon cathode, prevent the intercalation of solvent molecules, have higher conductivity and wider electrochemical window, can improve the stability and safety of the lithium ion battery, and prolong the service life of the lithium ion battery.
At present, the preparation method of the lithium dioxalate borate mainly comprises a solid phase method and a liquid phase method, and oxalic acid, a boron source and a lithium-containing compound (such as lithium hydroxide or lithium carbonate) are adopted as reaction raw materials to generate the lithium dioxalate borate and water. The lithium dioxalate borate is easy to absorb water to form a lithium dioxalate hydrate, and meanwhile, under the action of water, partial hydrolysis reaction occurs, and the hydrolysis reaction formula is as follows:
LiB(C 2 O 4 ) 2 +2H 2 O→LiBO 2 +2H 2 C 2 O 4 ；
LiB(C 2 O 4 ) 2 +3H 2 O→LiOOCCOOH+H 3 BO 3 +H 2 C 2 O 4 ；
in the preparation method, water is produced in the reaction process, which is difficult to avoid; the existence of water can cause higher water content in the final product and is difficult to remove completely; meanwhile, the lithium dioxalate borate can be partially hydrolyzed, particularly, when the lithium dioxalate borate is heated and dehydrated, the hydrolysis is accelerated, and the product yield is low, and the three wastes are more.
Disclosure of Invention
In order to solve the technical problems, the invention aims to provide the preparation method of the lithium difluoroborate, which has the advantages of mild reaction, simple process, low production cost, economy, environmental protection and high reaction yield, can obtain the high-purity lithium difluoroborate, and is more suitable for industrial production.
In order to achieve the technical purpose and the technical effect, the invention is realized by the following technical scheme:
the preparation method of the lithium dioxalate borate comprises the following steps:
(1) Mixing a certain amount of oxalic acid with a boron-containing compound, reacting for 1-12 hours at 40-130 ℃ under normal pressure and mechanical stirring, and drying for 2-8 hours at 60-220 ℃ under vacuum; during the reaction, oxalic acid and a boron-containing compound generate oxalic acid boric acid;
(2) Cooling the reactant obtained in the step (1) to room temperature under the nitrogen atmosphere, then adding a polar solvent, and stirring and dissolving for 1-8 hours;
(3) Filtering the solution obtained in the step (2), adding a lithium salt compound into the filtrate, and reacting for 1-8 hours at the temperature range from room temperature to reflux temperature; reacting the lithium dioxalate borate with a lithium salt compound under nearly anhydrous conditions to produce lithium dioxalate borate;
(4) After the reaction in the step (3) is finished, cooling the reaction liquid to room temperature, filtering, concentrating, crystallizing, washing and drying the filtrate in sequence to obtain a solid lithium dioxalate borate product.
Preferably, the oxalic acid is anhydrous oxalic acid or dihydrate oxalic acid; the boron-containing compound is one or a mixture of two or more of boric acid, diboron trioxide, metaboric acid and pyroboric acid.
Further, the addition amount of oxalic acid and the boron-containing compound is calculated according to the molar ratio of oxalic acid radical ion to boron element; specifically, the molar ratio of the oxalate ion to the boron element is (2-2.2): 1.
Preferably, the polar solvent in the step (2) is selected from one or a combination of two or more of acetonitrile, propionitrile, methyl acetate, ethyl acetate, propyl acetate, acetone, methyl ethyl ketone, 1, 4-dioxane, 1, 4-butyrolactone and tetrahydrofuran.
Further, the addition amount of the polar solvent is 1 to 5 times of the mass of the boric acid di-oxalate after drying in the step 1).
Further, the moisture content of the polar solvent is controlled to be within 500 ppm.
Preferably, the lithium salt compound is one of anhydrous halogenated lithium salt, lithium hydride and lithium nitride; if the lithium halide is lithium halide, one of lithium fluoride, lithium chloride and lithium bromide is selected;
further, the addition amount of the lithium salt compound is calculated in terms of the molar amount of the boron element in the boron-containing compound; specifically, the molar amount of the lithium salt compound is 1 to 1.1 times the molar amount of the boron element in the boron-containing compound.
The beneficial effects of the invention are as follows:
according to the invention, oxalic acid and a boron-containing compound are adopted to generate an intermediate oxalic acid boric acid, the oxalic acid boric acid cannot be combined with water molecules to form a crystal water complex, and after vacuum drying, the water is thoroughly removed; therefore, the next reaction process of the lithium dioxalate borate and the lithium salt compound is in a nearly anhydrous condition, and water is not generated, so that the hydrolysis caused by the contact of the lithium dioxalate borate product obtained after the reaction and the water can be avoided, and the product yield and purity are improved.
In addition, the excessive lithium salt compound in the reaction raw materials is almost insoluble in the polar solvent, and can be removed by filtration, thereby being beneficial to improving the purity of the final product; the preparation method is simple and convenient in post-treatment after the reaction is finished, and the lithium dioxalate borate product can be obtained through concentration, crystallization, washing and drying.
The whole reaction process of the preparation method has almost no side reaction, the reaction yield is high, the residual quantity of moisture in the obtained product is low, the product is easy to purify, and the product purity is high.
Detailed Description
The following description of the embodiments of the present invention will be made more apparent and fully by reference to the accompanying drawings, in which it is shown, by way of illustration, only some, but not all embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Example 1
The preparation method of the lithium dioxalate borate in the embodiment 1 comprises the following steps:
(1) 126g (1 mol) of oxalic acid dihydrate and 31g (0.5 mol) of boric acid are taken and added into a three-neck flask with a stirring device, and the reaction raw materials are heated to 55 ℃ under normal pressure and mechanical stirring conditions and react for 2 hours; after decompression, continuously heating to 90 ℃, and vacuum drying at the temperature for 8 hours; obtaining a white honeycomb solid reactant in the flask; in the reaction process, the oxalic acid dihydrate and boric acid generate oxalic acid boric acid;
the reaction formula of the step (1) is as follows:
2H 2 C 2 O 4 .2 H 2 O+H 3 BO 3 →HB(C 2 O 4 ) 2 +5H 2 O
(2) Cooling the reactant obtained in the step (1) to room temperature under nitrogen atmosphere, and weighing to obtain a net weight of 85g; then adding 320g of ethyl acetate with the moisture content of 180ppm into the reactant, and stirring and dissolving for 2 hours;
(3) Filtering the solution obtained in the step (2), slowly adding 21g (0.5 mol) of anhydrous lithium chloride into the filtrate in batches, and stirring and reacting for 8 hours at 25 ℃; in the step (2), under the nearly anhydrous condition, the boric acid of the oxalic acid reacts with anhydrous lithium chloride to generate lithium borate of the oxalic acid; the reaction formula is as follows:
HB(C 2 O 4 ) 2 +LiCl→LiB(C 2 O 4 ) 2 +HCl↑
the hydrogen chloride gas generated in the reaction process escapes, and then is absorbed by water;
(4) After the reaction in the step (3) is finished, the reaction solution is cooled to room temperature, then is filtered, filtrate is concentrated and crystallized, is washed by petroleum ether for a plurality of times, and is dried under vacuum to obtain 81g of solid lithium dioxalate borate product, the yield is 83.5%, the product purity is 99.81%, and the product moisture content is 38ppm.
Example 2
The preparation method of the lithium dioxalate borate in the embodiment 2 comprises the following steps:
(1) 198g (2.2 mol) of anhydrous oxalic acid and 35g (0.5 mol) of diboron trioxide are taken and added into a three-neck flask with a stirring device, and the reaction raw materials are heated to 85 ℃ under normal pressure and mechanical stirring conditions for reaction for 8 hours; after decompression, continuously heating to 200 ℃, and vacuum drying at the temperature for 2 hours; obtaining a white honeycomb solid reactant in the flask; in the reaction process, the oxalic acid dihydrate and boric acid generate oxalic acid boric acid;
(2) Cooling the reactant obtained in the step (1) to room temperature under nitrogen atmosphere, and weighing to obtain a net weight of 178g; then 600g of acetonitrile with the moisture content of 230ppm is added into the reactant, and the mixture is stirred and dissolved for 8 hours;
(3) Filtering the solution obtained in the step (2), adding 28.6g (1.1 mol) of lithium fluoride into the filtrate, and carrying out reflux reaction for 5 hours under stirring; in the step (2), under the nearly anhydrous condition, the lithium oxalato borate reacts with lithium fluoride to generate lithium oxalato borate; after the gas generated in the reaction process escapes, water is adopted for absorption;
(4) After the reaction in the step (3) is finished, the reaction solution is cooled to room temperature, then is filtered, and after the filtrate is concentrated and crystallized, the filtrate is washed for a plurality of times by using dichloromethane, and is dried under vacuum, 159g of solid lithium dioxalate borate product is obtained, the yield is 82%, the purity of the product is 99.79%, and the water content of the product is 32ppm.
Example 3
The preparation method of the lithium dioxalate borate in the embodiment 3 comprises the following steps:
(1) 90g (1 mol) of anhydrous oxalic acid and 31g (0.5 mol) of boric acid are taken and added into a three-neck flask with a stirring device, and the reaction raw materials are heated to 120 ℃ under normal pressure and mechanical stirring conditions and react for 1 hour; after decompression, continuously heating to 160 ℃, and vacuum drying at the temperature for 5 hours; obtaining a white honeycomb solid reactant in the flask; in the reaction process, the oxalic acid dihydrate and boric acid generate oxalic acid boric acid;
(2) Cooling the reactant obtained in the step (1) to room temperature under nitrogen atmosphere, and weighing to obtain a net weight of 90g; then 350g of 1, 4-dioxane with the moisture content of 150ppm is added into the reactant, and stirred and dissolved for 3 hours;
(3) Filtering the solution obtained in the step (2), slowly adding 17.5g (0.5 mol) of lithium nitride into the filtrate in batches, and reacting for 4 hours at 65 ℃ under stirring; in the step (2), under the nearly anhydrous condition, the lithium oxalato borate reacts with lithium fluoride to generate lithium oxalato borate; after the gas generated in the reaction process escapes, water is adopted for absorption;
(4) After the reaction in the step (3) is finished, the reaction solution is cooled to room temperature, then is filtered, and after the filtrate is concentrated and crystallized, the filtrate is washed by dichloroethane for a plurality of times and is dried under vacuum, thus obtaining 76g of solid lithium dioxalate borate product, the yield is 78.4%, the purity of the product is 99.73%, and the water content of the product is 26ppm.
The foregoing description is only illustrative of the present invention and is not intended to limit the scope of the invention, and all modifications or equivalent arrangements using the teachings of this invention, or direct or indirect application in other related arts, are included within the scope of this invention.
Claims (5)
1. The preparation method of the lithium dioxalate borate is characterized by comprising the following steps:
(1) Mixing a certain amount of oxalic acid with a boron-containing compound, reacting for 1-12 hours at 40-130 ℃ under normal pressure and mechanical stirring, and vacuum drying for 2-8 hours at 60-220 ℃; during the reaction, oxalic acid and a boron-containing compound generate oxalic acid boric acid; the oxalic acid is anhydrous oxalic acid or dihydrate oxalic acid; the boron-containing compound is one or a mixture of two or more of boric acid, diboron trioxide, metaboric acid and pyroboric acid;
the addition amount of oxalic acid and boron-containing compound is calculated according to the molar ratio of oxalic acid radical ion to boron element; the molar ratio of the oxalate ion to the boron element is (2-2.2): 1;
(2) Cooling the reactant obtained in the step (1) to room temperature under the nitrogen atmosphere, then adding a polar solvent, and stirring and dissolving for 1-8 hours;
(3) Filtering the solution obtained in the step (2), adding a lithium salt compound into the filtrate, and reacting for 1-8 hours at room temperature to reflux temperature; reacting the lithium dioxalate borate with a lithium salt compound under nearly anhydrous conditions to produce lithium dioxalate borate; the lithium salt compound is one of anhydrous halogenated lithium salt, lithium hydride and lithium nitride; the halogenated lithium salt is selected from one of lithium fluoride, lithium chloride and lithium bromide;
(4) After the reaction in the step (3) is finished, cooling the reaction liquid to room temperature, filtering, concentrating, crystallizing and drying the filtrate in sequence to obtain a solid lithium dioxalate borate product.
2. The method according to claim 1, wherein the polar solvent in the step (2) is one or a combination of two or more selected from acetonitrile, propionitrile, methyl acetate, ethyl acetate, propyl acetate, acetone, methyl ethyl ketone, 1, 4-dioxane, 1, 4-butyrolactone, and tetrahydrofuran.
3. The method for preparing lithium dioxalate borate according to claim 1, wherein the addition amount of the polar solvent is 1 to 5 times the mass of the dioxalate boric acid after drying in the step 1).
4. The method for producing lithium dioxalate borate according to claim 1, wherein the water content of the polar solvent is controlled to be within 500 ppm.
5. The method for producing lithium dioxalate borate according to claim 1, wherein the addition amount of the lithium salt compound is calculated in terms of the molar amount of boron element in the boron-containing compound; the molar amount of the lithium salt compound is 1 to 1.1 times the molar amount of the boron element in the boron-containing compound.
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| WO2023000198A1 (en) * | 2021-07-21 | 2023-01-26 | 江苏华盛锂电材料股份有限公司 | Method for preparing lithium bisoxalate borate and method for preparing lithium-ion battery electrolyte |
| CN114671899A (en) * | 2022-03-28 | 2022-06-28 | 珠海市赛纬电子材料股份有限公司 | Preparation method of lithium bis (oxalato) borate and application of lithium bis (oxalato) borate |
| CN114773371A (en) * | 2022-05-30 | 2022-07-22 | 无锡威孚环保催化剂有限公司 | Preparation method of lithium bis (oxalato) borate |
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| JP2001247306A (en) * | 2000-03-07 | 2001-09-11 | Central Glass Co Ltd | Method for synthesizing ionic metal complex and method for purifying the same |
| CN102304143A (en) * | 2011-07-13 | 2012-01-04 | 北京大学 | Method for preparing lithium bis(oxalate) borate |
| CN103030657A (en) * | 2011-10-10 | 2013-04-10 | 中国科学院福建物质结构研究所 | Preparation method of electrolyte double-oxalate based lithium borate for lithium ion battery |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001247306A (en) * | 2000-03-07 | 2001-09-11 | Central Glass Co Ltd | Method for synthesizing ionic metal complex and method for purifying the same |
| CN102304143A (en) * | 2011-07-13 | 2012-01-04 | 北京大学 | Method for preparing lithium bis(oxalate) borate |
| CN103030657A (en) * | 2011-10-10 | 2013-04-10 | 中国科学院福建物质结构研究所 | Preparation method of electrolyte double-oxalate based lithium borate for lithium ion battery |
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