Preparation method of lithium bis (oxalato) borate
By controlling the temperature and solvent composition, the problems of operational difficulty and low yield in the preparation of lithium bis(oxalato)borate were solved, and high-purity and high-yield lithium bis(oxalato)borate were prepared, which is suitable for industrial production.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-01-16
- Publication Date
- 2026-03-27
AI Technical Summary
In the existing technology, the preparation methods of lithium bis(oxalate-borate) have problems such as high operation difficulty, low product yield and decomposition, especially the incomplete water separation in the traditional solution method, which leads to easy decomposition of the product.
After mixing oxalic acid, lithium source, and aprotic polar solvent, boron trioxide was added and refluxed to remove water. The water was removed by controlling the temperature and time, followed by filtration and drying. Finally, crystals were precipitated in a crystallization solvent, and the temperature and vacuum were controlled for purification.
The preparation of high-purity lithium bis(oxalate-borate) was achieved, which reduced production costs, improved product yield, and made it suitable for industrial production.
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Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of chemical synthesis, in particular to a preparation method of lithium bis(oxalato)borate. BACKGROUND
[0002] Currently, the solvent of commercial electrolyte is mainly a mixture of carbonates, and the electrolyte is mainly lithium hexafluorophosphate (LiPF6); however, lithium hexafluorophosphate has low thermal stability and is easy to hydrolyze, and the decomposition product has strong corrosion, which has a serious impact on the service life and safety performance of the battery. Lithium bis(oxalato)borate (LiBOB) as an electrolyte for non-aqueous electrolyte batteries such as lithium ion batteries and lithium ion capacitors has good thermal stability and chemical stability, and has high conductivity and excellent electrochemical window, and is also an environmentally friendly lithium salt because it does not contain halogen. Therefore, lithium bis(oxalato)borate as an electrolyte has a broad application prospect.
[0003] Currently, there are two main methods for preparing lithium bis(oxalato)borate: one method is to synthesize by solid phase, and the product is obtained by drying and crystallization; but the solid phase method has high requirements for production equipment and operation, and the material mixing and temperature distribution are easy to be uneven, so the actual operation is difficult. Another method is solution method, and the traditional solution method uses lithium hydroxide, oxalic acid dihydrate and boric acid to react directly in the solvent, and then dehydrates to obtain the product; but the main problem of this method is that the water is not completely separated, which leads to the problem that the product is easy to decompose in the post-processing process, and the product yield is reduced.
[0004] Therefore, it is necessary to provide a new method for preparing lithium bis(oxalato)borate. SUMMARY
[0005] In order to solve the above technical problems, the present application provides a preparation method of lithium bis(oxalato)borate.
[0006] The present application provides a preparation method of lithium bis(oxalato)borate, comprising the following steps: (1) uniformly mix oxalic acid, lithium source and aprotic polar solvent, and control the temperature in the range of 20-40℃ during the mixing; then add di boron trioxide, heat to reflux and separate water for 8-36h, after the reaction is completed, cool, filter, rinse and dry to obtain a crude product; (2) add the crude product to a crystallization solvent, heat to 55-65℃ for dissolution, then cool to 10-15℃ for crystallization, and after filtering and drying, a fine lithium bis(oxalato)borate is obtained.
[0007] The reaction formula of the preparation method of lithium bis(oxalato)borate provided by the present application is shown in formula (1).
[0008]
[0009] Formula (1) The preparation method of lithium bis(oxalato)borate provided by the application is simple in operation, no waste gas is generated, the production cost is low, high-purity lithium bis(oxalato)borate can be obtained, and the method is suitable for traditional industrial production.
[0010] Preferably, the molar amount ratio of the oxalic acid to the lithium source is 2-2.2:1; the molar amount ratio of the lithium source to the boron trioxide is 2-2.2:1; wherein the lithium source is calculated according to the molar amount of lithium.
[0011] Preferably, the molar amount ratio of the oxalic acid to the lithium source is 2.02-2.1:1; the molar amount ratio of the lithium source to the boron trioxide is 2.05-2.2:1.
[0012] In a specific embodiment, the molar amount ratio of the oxalic acid to the lithium source can be 2.02:1, 2.05:1, 2.08:1, 2.1:1; the molar amount ratio of the lithium source to the boron trioxide can be 2.05:1, 2.1:1, 2.15:1, 2.2:1.
[0013] Through experimental analysis, it is found that when the molar amount ratio of the oxalic acid to the lithium source and the molar amount ratio of the lithium source to the boron trioxide are controlled within the above ranges, the yield of the target product can be further improved.
[0014] Preferably, the lithium source is selected from one or more of lithium carbonate, anhydrous lithium hydroxide, and monohydrate lithium hydroxide.
[0015] Preferably, the aprotic polar solvent is selected from one or more of acetonitrile, propionitrile, ethyl acetate, isopropyl acetate, acetone, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, and tetrahydrofuran; and the amount of the aprotic polar solvent is 3-10 times the mass of the oxalic acid.
[0016] Preferably, the moisture content of the aprotic polar solvent is controlled to be within 500 ppm.
[0017] Preferably, the temperature of the reflux water separation is 90-100℃, and the time is 9-24h.
[0018] Preferably, the crystallization solvent is selected from two or more of a nitrile solvent, ethyl acetate, acetone, a carbonate solvent, dichloromethane, toluene, and 1,4-dioxane.
[0019] Preferably, the crystallization solvent is composed of a mixture of a nitrile solvent and a carbonate solvent in a weight ratio of 1:2-4; the nitrile solvent is selected from one or more of acetonitrile and propionitrile; and the carbonate solvent is selected from one or more of dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate.
[0020] In one specific embodiment, the weight ratio of the nitrile solvent and the carbonate solvent can be 1:2, 1:3, or 1:4.
[0021] Through experimental analysis, it is found that the crystallization solvent composed of the nitrile solvent and the carbonate solvent in the above weight ratio can further improve the yield of the target product.
[0022] Preferably, in step (1), the drying vacuum degree is -0.07 Mpa to -0.09 Mpa, and the drying temperature is 200-250°C.
[0023] In one specific embodiment, in step (1), the drying vacuum degree can be -0.07 Mpa, -0.08 Mpa, or -0.09 Mpa, and the drying temperature can be 200°C, 210°C, 220°C, 230°C, or 250°C.
[0024] Preferably, in step (2), the drying vacuum degree is -0.07 Mpa to -0.09 Mpa, and the fine drying temperature is 70-120°C.
[0025] In one specific embodiment, in step (2), the drying vacuum degree can be -0.07 Mpa, -0.08 Mpa, or -0.09 Mpa, and the fine drying temperature can be 70°C, 80°C, 90°C, 100°C, 110°C, or 120°C.
[0026] In summary, the technical solution of the present application has the following effects: The reaction raw material used in the present application is anhydrous oxalic acid, which can be dissolved in the solvent before the crude product is crystallized, and then directly used for the next batch. Lithium hydroxide is removed during the refining process, which is beneficial to improve the purity of the final product.
[0027] The reaction raw material used in the preparation method provided by the present application is easy to obtain and has low cost. Almost no side reactions occur in the entire reaction, and the product is easy to purify.
[0028] The present application uses the reflux water separation method to remove water, which is thorough and avoids product decomposition, thereby improving the yield of the product. BRIEF DESCRIPTION OF DRAWINGS
[0029] Figure 1 The X-ray diffraction spectrum of the fine lithium bis (oxalate) borate in Example 1 is shown in Figure 1.
[0030] Figure 2 The X-ray diffraction spectrum of the fine lithium bis (oxalate) borate in Example 2 is shown in Figure 2.
[0031] Figure 3 The X-ray diffraction spectrum of the fine lithium bis (oxalate) borate in Example 3 is shown in Figure 3.
[0032] Figure 4 X-ray diffraction pattern of the fine lithium bis (oxalato) borate of Example 7.
[0033] Figure 5 X-ray diffraction pattern of the standard lithium bis (oxalato) borate. DETAILED DESCRIPTION
[0034] The application will be further described in conjunction with the examples, comparative examples and performance test, which cannot be understood as limiting the scope of the application.
[0035] Example
[0036] Example 1 The present example provides a method for preparing lithium bis (oxalato) borate.
[0037] The method for preparing lithium bis (oxalato) borate in the present example is specifically shown as follows.
[0038] Lithium bis (oxalato) borate is prepared by using anhydrous oxalic acid, lithium hydroxide as a lithium source, and dimethyl carbonate as an aprotic polar solvent.
[0039] (1) At room temperature, 1.89 mol of oxalic acid, 0.86 mol of lithium hydroxide as a lithium source, and 600 ml of dimethyl carbonate as an aprotic polar solvent were added to a reaction bottle, stirred for 10 min to mix uniformly, and the temperature was controlled in the range of 20-40°C during the period; then 0.43 mol of boron trioxide was added, and the temperature was raised to 100°C to reflux and remove water for 10 h; after the reaction was completed, the temperature was lowered to room temperature, filtered, the filter cake was washed with dimethyl carbonate, and the filter cake was dried at a vacuum degree of -0.08 Mpa and 230°C for 8 h to obtain a crude product.
[0040] The molar amount ratio of oxalic acid to lithium source is 2.2:1, and the molar amount ratio of lithium source to boron trioxide is 2:1. The amount of the aprotic polar solvent is 3.52 times the mass of the oxalic acid.
[0041] (2) The crude product was added to 3 times the mass of a crystallization solvent (ethyl acetate), heated to 60°C to completely dissolve, and then cooled to 10°C for crystallization. After filtration, the filter cake was dried at a vacuum degree of -0.08 Mpa and 90°C for 8 h to obtain fine lithium bis (oxalato) borate.
[0042] The moisture content of the fine lithium bis (oxalato) borate is ≤90 ppm, the acid value is ≤100 ppm, the purity is 99.61%, and the yield is 84.89% (theoretical yield: 166.66 g of product, actual yield: 141.48 g, yield = actual yield / theoretical yield = 84.89%). As Figure 1 X-ray diffraction pattern of the fine lithium bis (oxalato) borate of Example 7. Figure 5The X-ray diffraction spectrum of the prepared high-quality lithium bis (oxalato) borate in Example 1 is shown in Figure 1. It can be seen that the X-ray diffraction spectrum of the prepared high-quality lithium bis (oxalato) borate in Example 1 is consistent with the standard spectrum of lithium bis (oxalato) borate, which indicates that the lithium bis (oxalato) borate is successfully prepared. Figure 1 The X-ray diffraction spectrum of the prepared high-quality lithium bis (oxalato) borate in Example 1 is shown in Figure 1. It can be seen that the X-ray diffraction spectrum of the prepared high-quality lithium bis (oxalato) borate in Example 1 is consistent with the standard spectrum of lithium bis (oxalato) borate, which indicates that the lithium bis (oxalato) borate is successfully prepared.
[0043] Example 2
[0044] The present embodiment provides a preparation method of lithium bis (oxalato) borate.
[0045] The preparation method of lithium bis (oxalato) borate in the present embodiment is specifically shown as follows.
[0046] The lithium bis (oxalato) borate is prepared by using anhydrous oxalic acid, lithium hydroxide as a lithium source, and diethyl carbonate as an aprotic polar solvent.
[0047] (1) At room temperature, 2.583 mol of oxalic acid, 1.26 mol of lithium source lithium hydroxide, and 900 ml of aprotic polar solvent diethyl carbonate were added to a reaction bottle, stirred for 10 min to mix uniformly, and the temperature was controlled in the range of 20-40°C during the period; then 0.6 mol of boron trioxide was added, the temperature was raised to 100°C to reflux and remove water for 12 h, after the reaction was completed, the temperature was lowered to room temperature, then filtered, the filter cake was washed with diethyl carbonate, and the filter cake was dried at a vacuum degree of-0.08 Mpa and a temperature of 230°C for 8 h to obtain a crude product.
[0048] The molar amount ratio of oxalic acid to lithium source is 2.08:1; the molar amount ratio of lithium source to boron trioxide is 2.1:1. The amount of aprotic polar solvent is 3.87 times the mass of oxalic acid.
[0049] (2) The crude product was added to 3 times the mass of a crystallization solvent (diethyl carbonate), heated to 60°C to completely dissolve, and then cooled to 10°C to crystallize, and then filtered, and the filter cake was dried at a vacuum degree of-0.08 Mpa and a temperature of 90°C for 8 h to obtain high-quality lithium bis (oxalato) borate, The moisture content of the high-quality lithium bis (oxalato) borate is ≤90 ppm, the acid value is ≤100 ppm, the purity is 99.84%, and the yield is 85.26% (theoretical yield 232.55 g, actual yield 198.27 g, yield 85.26%). Figure 2 The X-ray diffraction spectrum of the prepared high-quality lithium bis (oxalato) borate in Example 2 is shown in Figure 1. It can be seen that the X-ray diffraction spectrum of the prepared high-quality lithium bis (oxalato) borate in Example 1 is consistent with the standard spectrum of lithium bis (oxalato) borate, which indicates that the lithium bis (oxalato) borate is successfully prepared. Figure 1 The X-ray diffraction spectrum of the prepared high-quality lithium bis (oxalato) borate in Example 1 is shown in Figure 1. It can be seen that the X-ray diffraction spectrum of the prepared high-quality lithium bis (oxalato) borate in Example 1 is consistent with the standard spectrum of lithium bis (oxalato) borate, which indicates that the lithium bis (oxalato) borate is successfully prepared.
[0050] Examples 3-8 Examples 3-8 respectively provide a preparation method of lithium bis (oxalato) borate.
[0051] The difference between the above-mentioned examples and Example 2 is specifically that the types of the crystallization solvents are different, and are specifically as shown below.
[0052] In Example 3: the crystallization solvent is composed of acetonitrile and 1,4-dioxane in a weight ratio of 1:3.
[0053] In Example 4: the crystallization solvent is composed of dichloromethane and dimethyl carbonate in a weight ratio of 1:3.
[0054] In Example 5: the crystallization solvent is composed of acetonitrile and dimethyl carbonate in a weight ratio of 3:1.
[0055] In Example 6: the crystallization solvent is composed of acetonitrile and dimethyl carbonate in a weight ratio of 1:2.
[0056] In Example 7: the crystallization solvent is composed of acetonitrile and dimethyl carbonate in a weight ratio of 1:3.
[0057] In Example 8: the crystallization solvent is composed of acetonitrile and dimethyl carbonate in a weight ratio of 1:4.
[0058] In the above-mentioned examples, other process parameters are the same as those in Example 2.
[0059] In the above-mentioned examples, the yield results of the target product are specifically as shown below.
[0060] In Example 3: the purity of the fine lithium bis (oxalato) borate is 99.86%, and the yield is 87.09%. Figure 3 The X-ray diffraction spectrum of the fine lithium bis (oxalato) borate in Example 7 is shown. It can be known that the X-ray diffraction spectrum of the fine lithium bis (oxalato) borate prepared in Example 7 of the present application is the same as the standard spectrum Figure 1 , indicating that the lithium bis (oxalato) borate is successfully prepared.
[0061] In Example 4: the purity of the fine lithium bis (oxalato) borate is 99.90%, and the yield is 86.05%.
[0062] In Example 5: the purity of the fine lithium bis (oxalato) borate is 99.85%, and the yield is 90.32%.
[0063] In Example 6: the purity of the fine lithium bis (oxalato) borate is 99.87%, and the yield is 96.71%.
[0064] In Example 7: the purity of the fine lithium bis (oxalato) borate is 99.91%, and the yield is 96.63%. Figure 4 The X-ray diffraction spectrum of the fine lithium bis (oxalato) borate in Example 7 is shown. It can be known that the X-ray diffraction spectrum of the fine lithium bis (oxalato) borate prepared in Example 7 of the present application is the same as the standard spectrum Figure 1 , indicating that the lithium bis (oxalato) borate is successfully prepared.
[0065] In Example 8: the purity of the fine lithium bisoxalate borate is 99.88%, and the yield is 95.06%.
[0066] In the above examples, the moisture content of lithium bisoxalate borate is ≤90 ppm, and the acid value is ≤100 ppm.
[0067] Examples 9-13 Examples 9-13 respectively provide a preparation method of lithium bisoxalate borate.
[0068] The difference between the above examples and Example 7 is specifically as follows: the molar amount ratio of oxalic acid to lithium source or the molar amount ratio of lithium source to boron trioxide, which is specifically as follows.
[0069] In Example 9: the molar amount ratio of oxalic acid to lithium source is 2:1; the molar amount ratio of lithium source to boron trioxide is 2:1; and the molar amount of boron trioxide is 0.6 mol.
[0070] In Example 10: the molar amount ratio of oxalic acid to lithium source is 2.08:1; the molar amount ratio of lithium source to boron trioxide is 2:1; and the molar amount of boron trioxide is 0.6 mol.
[0071] In Example 11: the molar amount ratio of oxalic acid to lithium source is 2.2:1; the molar amount ratio of lithium source to boron trioxide is 2.2:1; and the molar amount of boron trioxide is 0.6 mol.
[0072] In Example 12: the molar amount ratio of oxalic acid to lithium source is 2.02:1; the molar amount ratio of lithium source to boron trioxide is 2.2:1; and the molar amount of boron trioxide is 0.6 mol.
[0073] In Example 13: the molar amount ratio of oxalic acid to lithium source is 2.1:1; the molar amount ratio of lithium source to boron trioxide is 2.05:1; and the molar amount of boron trioxide is 0.6 mol.
[0074] In the above examples, other process parameters are the same as those in Example 1.
[0075] In the above examples, the yield results of the target product are as follows.
[0076] In Example 9: the purity of the fine lithium bisoxalate borate is 99.86%, and the yield is 84.18%.
[0077] In Example 10: the purity of the fine lithium bisoxalate borate is 99.90%, and the yield is 86.13%.
[0078] In Example 11: the purity of the fine lithium bisoxalate borate is 99.85%, and the yield is 94.07%.
[0079] In Example 12: the purity of the fine lithium bisoxalate borate is 99.87%, and the yield is 97.02%.
[0080] In Example 13: the purity of the fine lithium bisoxalate borate is 99.91%, and the yield is 96.58%.
[0081] In the above examples, the moisture content of the lithium bisoxalate borate is ≤90 ppm, and the acid value is ≤100 ppm.
[0082] From the preparation method and detection results of the lithium bisoxalate borate in the above examples, it can be seen that the yield of the target product, fine lithium bisoxalate borate, is improved by using the preparation method of lithium bisoxalate borate provided in the present application.
[0083] From the detection results of Comparative Examples 2-8, it can be seen that the type of the crystallization solvent has a great influence on the yield of the target product. The present application uses a crystallization solvent composed of a mixture of nitrile solvents and carbonate solvents in a weight ratio of 1:2-4, which effectively improves the yield of the target product.
[0084] From the detection results of Comparative Examples 7, 9-13, it can be seen that the molar amount ratio of oxalic acid to lithium source or the molar amount ratio of lithium source to boron trioxide has a great influence on the yield of the target product. By controlling the molar amount ratio of oxalic acid to lithium source to be 2.02-2.1:1 and the molar amount ratio of the lithium source to boron trioxide to be 2.05-2.2:1, the present application further improves the yield of the target product.
[0085] Although the present application has been described in detail in the foregoing general description and examples, modifications and improvements to those that are apparent to those skilled in the art generally or specifically based on the foregoing description and examples can be made without departing from the spirit of the present application. Therefore, these modifications and improvements, which are made without departing from the spirit of the present application, are intended to be within the scope of the present application.
Claims
1. A method for preparing lithium bis(oxalateborate), characterized in that, Includes the following steps: (1) Mix oxalic acid, lithium source and aprotic polar solvent evenly, and control the temperature in the range of 20~40℃ during the process; then add boron trioxide, heat to reflux and remove water for 8~36h. After the reaction is completed, cool, filter, rinse and dry to obtain crude product. (2) Add the crude product to the crystallization solvent, heat to 55~65℃ to dissolve, then cool to 10~15℃ to crystallize, filter and dry to obtain high-quality lithium bis(oxalate-borate).
2. The method for preparing lithium bis(oxalatoborate) according to claim 1, characterized in that, The molar ratio of oxalic acid to lithium source is 2~2.2:1; the molar ratio of lithium source to boron trioxide is 2~2.2:1; wherein the lithium source is measured in molar amounts of lithium.
3. The method for preparing lithium bis(oxalatoborate) according to claim 2, characterized in that, The molar ratio of oxalic acid to lithium source is 2.02~2.1:1; the molar ratio of lithium source to boron trioxide is 2.05~2.2:
1.
4. The method for preparing lithium bis(oxalatoborate) according to claim 1, characterized in that, The lithium source is selected from one or more of lithium carbonate, anhydrous lithium hydroxide, and lithium hydroxide monohydrate.
5. The method for preparing lithium bis(oxalateborate) according to claim 1, characterized in that, The aprotic polar solvent is selected from one or more of acetonitrile, propionitrile, ethyl acetate, isopropyl acetate, acetone, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, and tetrahydrofuran; the amount of the aprotic polar solvent is 3 to 10 times the mass of oxalic acid; the moisture content of the aprotic polar solvent is controlled to be less than 500 ppm.
6. The method for preparing lithium bis(oxalatoborate) according to claim 1, characterized in that, The temperature of the reflux water is 90~100℃, and the time is 9~24h.
7. The method for preparing lithium bis(oxalatoborate) according to claim 1, characterized in that, The crystallization solvent is selected from two or more of the following: nitrile solvents, ethyl acetate, acetone, carbonate solvents, dichloromethane, toluene, and 1,4-dioxane.
8. The method for preparing lithium bis(oxalatoborate) according to claim 7, characterized in that, The crystallization solvent is composed of a mixture of nitrile solvents and carbonate solvents in a weight ratio of 1:2 to 4; the nitrile solvent is selected from one or more of acetonitrile and propionitrile; the carbonate solvent is selected from one or more of dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate.
9. The method for preparing lithium bis(oxalatoborate) according to claim 1, characterized in that, In step (1), the vacuum degree of drying is -0.07Mpa to -0.09Mpa, and the drying temperature is 200 to 250℃.
10. The method for preparing lithium bis(oxalatoborate) according to claim 1, characterized in that, In step (2), the vacuum degree of drying is -0.07Mpa to -0.09Mpa, and the drying temperature of the finished product is 70 to 120℃.