Cyclic lithium methylene disulfonate compound, preparation method and application in battery

Abstract

The invention provides a cyclic lithium methylene disulfonate compound, a preparation method and application in a battery. The structural formula of the cyclic lithium methylene disulfonate compound is as shown in a formula I or a formula II, wherein R1 is CH2, CF2 or CHF; x1 is BF2 or PF4, and X2 is B or PF2. The preparation method of the cyclic lithium methylene disulfonate compound comprises the following steps: mixing a compound as shown in a formula III and a first solvent to form a first solution; the first solution and the second solution are dropwise added and mixed and react under a certain heating condition to obtain a primary product, the second solution is a salt solution, and the salt solution is a mixed solution of tetrafluoroborate and a first solvent or a mixed solution of hexafluorophosphate and the first solvent; and purifying and drying the primary product. As a novel substance, the cyclic lithium methylene disulfonate compound contains a sulfonic acid group and a lithium source, has a good application prospect and can be applied to a secondary battery, the preparation method is simple to operate, and the yield and purity of a target product are high. # imgabs0 #

Description

Technical Field

[0001] The present invention relates to the technical field of material synthesis, and in particular to a compound used in a battery, and more particularly to a cyclic methylene disulfonic acid lithium salt compound and a preparation method thereof, and application in a battery. Background Art

[0002] The electrolyte is the blood of lithium-ion batteries. It transfers lithium ions between the positive and negative electrode materials and the separator. In addition, the electrolyte also plays an important role in the formation of SEI and CEI at the interface of the positive and negative electrode materials and the impedance size. With the rapid development of pure electric vehicles and hybrid vehicles, people's requirements for the energy density, long cycle life, rate performance and safety performance of lithium-ion batteries are constantly increasing, which has put forward more requirements for the development of electrolytes.

[0003] Currently, commercial lithium-ion battery electrolytes generally use carbonate as solvent, LiPF 6 As a supporting electrolyte. With the development of power batteries and large-scale energy storage equipment, LiPF 6 Defects such as poor high-temperature performance have gradually become the bottleneck problem of lithium battery technology. Therefore, the development of new conductive lithium salts with excellent chemical and electrochemical stability has become a common goal of academia and industry. Summary of the invention

[0004] Based on the above problems, the object of the present invention is to provide a cyclic methylene disulfonic acid lithium salt compound and a preparation method, and application in batteries. The preparation method is simple to operate, and the yield and purity of the target product are high. As a new substance, the cyclic methylene disulfonic acid lithium salt compound contains a sulfonic acid group and a lithium source, has good application prospects, and can be applied to secondary batteries.

[0005] To achieve the above-mentioned object, the present invention provides a cyclic methylene disulfonic acid lithium salt compound in the first aspect, the structural formula of which is shown in Formula 1 or Formula 2, wherein R 1 CH 2 CF 2 or CHF;X 1 For BF 2 or PF 4 , X 2 B or PF 2 .

[0006]

[0007] The cyclic methylene disulfonic acid lithium salt compound of the present invention is a new substance, contains an intracyclic sulfonic acid group and a lithium source, is a new conductive lithium salt, has good application prospects, and can be applied to secondary batteries.

[0008] As a technical solution of the present invention, the cyclic methylene disulfonic acid lithium salt compound includes at least one of compound 1 to compound 6.

[0009]

[0010] The second aspect of the present invention provides a method for preparing a cyclic methylene disulfonic acid lithium salt compound, comprising the steps of:

[0011] (1) mixing the compound represented by formula 3 and a first solvent to form a first solution;

[0012] (2) adding the first solution and the second solution dropwise and mixing them and reacting them under certain heating conditions to obtain a primary product, wherein the second solution is a salt solution, and the salt solution is a mixed solution of tetrafluoroborate and the first solvent or a mixed solution of hexafluorophosphate and the first solvent;

[0013] (3) purifying and drying the primary product,

[0014]

[0015] Among them, R 1 CH 2 CF 2 or CHF.

[0016] The preparation method of the invention is simple, and can be prepared by reacting the sulfonic acid silicate of formula three with tetrafluoroborate or hexafluorophosphate under heating conditions. The target product with high yield and purity can be obtained after purification and drying, and is easy for industrial production.

[0017] As a technical solution of the present invention, the compound represented by formula 3 can be prepared by reacting methyl disulfonic acid with hexamethylsiloxane under condensation reflux and stirring, removing water and then distilling.

[0018] As a technical solution of the present invention, the first solvent includes at least one of a nitrile solvent, a halogenated hydrocarbon solvent, an ether solvent, an ester solvent, a ketone solvent and an aromatic hydrocarbon solvent.

[0019] As a technical solution of the present invention, the temperature during the mixing in step (1) is 0 to 100° C. and the time is 10 to 60 hours.

[0020] As a technical solution of the present invention, the heating conditions of step (2) are 40 to 90° C. and the reaction time is 1 to 24 hours.

[0021] As a technical solution of the present invention, the molar ratio of the compound represented by Formula 3 to the salt solution is 1 to 2:1.

[0022] As a technical solution of the present invention, the purification is filtering or washing, and the drying condition is vacuum drying at 35 to 120° C. for 1 to 24 hours.

[0023] The third aspect of the present invention provides the use of a cyclic methylene disulfonic acid lithium salt compound in a secondary battery. The cyclic methylene disulfonic acid lithium salt compound can improve the electrochemical performance of the battery and has good application prospects. DETAILED DESCRIPTION

[0024] The cyclic methylene disulfonic acid lithium salt compound of the present invention can be used as an intermediate in material synthesis or in batteries. In particular, the cyclic methylene disulfonic acid lithium salt compound is used in secondary batteries such as lithium ion batteries or sodium ion batteries, and as a new conductive lithium salt, it can improve the electrochemical properties of secondary batteries, such as cycle performance.

[0025] The structural formula of the cyclic methylene disulfonic acid lithium salt compound of the present invention is as shown in Formula 1 or Formula 2, R 1 CH 2 CF 2 or CHF;X 1 For BF 2 or PF 4 , X 2 B or PF 2 .

[0026]

[0027] Furthermore, the cyclic methylene disulfonic acid lithium salt compound includes at least one of Compounds 1 to 6. Of course, the cyclic methylene disulfonic acid lithium salt compound may also be other compounds, at least conforming to the structural formula of Formula 1 or Formula 2.

[0028]

[0029] The method for preparing the cyclic methylene disulfonic acid lithium salt compound of the present invention may include the following steps.

[0030] (1) Mixing the compound represented by Formula 3 and a first solvent to form a first solution.

[0031] (2) The first solution and the second solution are added dropwise and mixed and reacted under certain heating conditions to obtain a primary product, wherein the second solution is a salt solution, and the salt solution is a mixed solution of tetrafluoroborate and the first solvent or a mixed solution of hexafluorophosphate and the first solvent.

[0032] (3) Purify and dry the primary product.

[0033] The compound represented by formula (3) in step (1) is as follows, wherein R 1 CH 2 CF2 or CHF.

[0034]

[0035] The compound shown in Formula 3 can be purchased directly or prepared by itself. It can be prepared by reacting methyl disulfonic acid and hexamethylsiloxane under condensation reflux stirring and removing water and distilling. Further, the compound shown in Formula 3 can be prepared by heating methyl disulfonic acid and hexamethylsiloxane to a certain temperature in a toluene solvent, separating the water produced by the reaction with a water separator under condensation reflux stirring, and distilling under reduced pressure after the reaction is completed. The temperature of the reduced pressure distillation can be 100°C, and the temperature range of the collected fraction can be 80-100°C.

[0036] The first solvent includes at least one of a nitrile solvent, a halogenated hydrocarbon solvent, an ether solvent, an ester solvent, a ketone solvent, and an aromatic hydrocarbon solvent. Specifically, the nitrile solvent is acetonitrile or butyronitrile, the halogenated hydrocarbon solvent is dichloromethane, chloroform, 1,2-dichloroethane or tetrachloroethane, the ether solvent is methyl tert-butyl ether, ethylene glycol dimethyl ether, tetrahydrofuran or dioxane, the ester solvent is dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, methyl acetate, ethyl acetate or propyl acetate, the ketone solvent is acetone, cyclohexanone or 4-methyl-2-pentanone, and the aromatic hydrocarbon solvent is benzene, toluene or xylene. Preferably, the first solvent is at least one of acetonitrile and dimethyl carbonate.

[0037] The temperature during mixing is 0 to 100° C., and further, the temperature during mixing is 10 to 30° C. As an example, the temperature may be, but is not limited to, 0° C., 6° C., 12° C., 17° C., 22° C., 30° C., 38° C., 45° C., 50° C., 55° C., 60° C., 65° C., 70° C., 75° C., 80° C., 85° C., 90° C., 95° C., 100° C. The time is 10 to 60 hours, and as an example, the time may be, but is not limited to, 10 hours, 15 hours, 20 hours, 25 hours, 30 hours, 35 hours, 40 hours, 45 hours, 50 hours, 55 hours, 60 hours.

[0038] The heating condition of step (2) is 40-90°C. As an example, the heating temperature may be, but is not limited to, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C. The reaction time is 1-24h. Preferably, the reaction time is 6-12h. As an example, the time may be, but is not limited to, 1h, 3h, 5h, 7h, 9h, 10h, 12h, 14h, 16h, 18h, 20h, 22h, 24h. The molar ratio of the compound shown in Formula 3 to the salt solution is 1-2:1. As an example, the molar ratio may be, but is not limited to, 1.0:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9::1, 2.0:1. Preferably, the molar ratio of the compound represented by formula 3 to the salt solution is 1:1 or 2:1.

[0039] In step (3), purification is filtering or washing, and polar solvents / weakly polar solvents are used for washing. Polar solvents include acetonitrile, acetone, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, ethyl acetate, propyl acetate, butyl acetate, ether, methyl tert-butyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, and dioxane. Weakly polar solvents include dichloromethane, chloroform, n-hexane, cyclohexane, toluene, xylene, chlorobenzene, and fluorobenzene. The drying condition is vacuum drying at 35 to 120° C. for 1 to 24 hours, and the vacuum drying temperature can be, but is not limited to, 35° C., 45° C., 55° C., 65° C., 75° C., 85° C., 95° C., 105° C., 115° C., and 120° C. The drying time can be, but is not limited to, 1 h, 3 h, 5 h, 7 h, 9 h, 10 h, 12 h, 14 h, 16 h, 18 h, 20 h, 22 h, or 24 h.

[0040] In order to better illustrate the purpose, technical scheme and beneficial effects of the present invention, the present invention will be further described below in conjunction with specific embodiments. It should be noted that the following implementation method is a further explanation of the present invention and should not be used as a limitation of the present invention.

[0041] Part I: Preparation of Sulfonic Acid Silicate of Formula III

[0042] Example 1

[0043] This embodiment is for preparing compound VII, and its preparation method includes the following steps.

[0044] 100g of methylene disulfonic acid, 570g of toluene and 110.6g of hexamethylsiloxane were put into a multi-mouth flask equipped with a speed-adjustable stirrer, a condenser reflux tube and a water separator. The stirrer was turned on for stirring. The multi-mouth flask was then placed in an oil bath pot, the temperature of the oil bath pot was controlled to be 140°C, and the reflux reaction was carried out for 18 hours to produce about 8mL of water. The reaction solution was filtered, and the solution was concentrated at 80°C to remove the toluene solvent. The product was distilled under reduced pressure by an oil pump, and the fractions in the temperature range of 90 to 100°C were collected to obtain 160g of compound VII, with a yield of 87.9% and a purity of 99%.

[0045] The preparation reaction formula of compound VII is shown below.

[0046]

[0047] Example 2

[0048] This embodiment is for preparing compound VIII, and its preparation method includes the following steps.

[0049] 100g of difluoromethylene disulfonic acid, 570g of toluene and 110.6g of hexamethylsiloxane were put into a multi-mouth flask equipped with a speed-adjustable stirrer, a condenser reflux tube and a water separator. The stirrer was turned on for stirring. The multi-mouth flask was then placed in an oil bath pot, the temperature of the oil bath pot was controlled to be 140°C, and the reflux reaction was carried out for 18 hours to produce about 8mL of water. The reaction solution was filtered, and the solution was concentrated at 80°C to remove the toluene solvent. The product was distilled under reduced pressure by an oil pump, and the fractions in the temperature range of 90 to 100°C were collected to obtain 160g of compound VIII, with a yield of 89.5% and a purity of 99%.

[0050] The preparation reaction formula of compound VIII is shown below.

[0051]

[0052] Part II: Preparation of cyclic methylene disulfonic acid lithium salt compounds

[0053] Example 3

[0054] This embodiment is for preparing compound 1, and its preparation method includes the following steps.

[0055] (1) 20 g of compound VII and 50 g of dimethyl carbonate were stirred at 30° C. for 10 min to form a first solution.

[0056] (2) The second solution was added dropwise to the first solution and reacted at 60° C. for 10 h to obtain a primary product. The second solution was formed by mixing 5.9 g of lithium tetrafluoroborate and 50 g of dimethyl carbonate.

[0057] (3) The primary product was filtered, washed with dimethyl carbonate, and dried in vacuo at 60°C to obtain 13.0 g of compound 1 with a yield of 91% and a purity of 99%. Hydrogen spectrum: 1H NMR (400 MHz, CDCl 3 ):δ0.12(s,18H),5.50(s,2H), indicating that compound 1 was synthesized.

[0058] The preparation reaction formula of compound 1 of this example is shown below.

[0059]

[0060] Example 4

[0061] This embodiment is for preparing compound 2, and its preparation method includes the following steps.

[0062] (1) 20 g of compound 8 and 50 g of dimethyl carbonate were stirred at 30° C. for 10 min to form a first solution.

[0063] (2) The second solution was added dropwise to the first solution and reacted at 60° C. for 10 h to obtain a primary product. The second solution was formed by mixing 5.3 g of lithium tetrafluoroborate and 50 g of dimethyl carbonate.

[0064] (3) The primary product was filtered, washed with dimethyl carbonate, and dried in vacuo at 60° C. to obtain 13.9 g of compound 2 with a yield of 93% and a purity of 99%. Hydrogen spectrum: 1H NMR (400 MHz, CDCl3): 5.50 (s, 2H), 19 F-NMR (CDCl3): 53.0 2F, indicating that compound 2 was synthesized.

[0065] The preparation reaction formula of compound 2 of this example is shown below.

[0066]

[0067] Example 5

[0068] This embodiment is for preparing compound three, and its preparation method includes the following steps.

[0069] (1) 20 g of compound VII and 50 g of dimethyl carbonate were stirred at 30° C. for 10 min to form a first solution.

[0070] (2) The second solution was added dropwise to the first solution and reacted at 60° C. for 9 hours to obtain a primary product. The second solution was formed by uniformly mixing 9.5 g of lithium hexafluorophosphate and 50 g of dimethyl carbonate.

[0071] (3) The primary product was filtered, washed with dimethyl carbonate, and dried in vacuo at 70° C. to obtain 14.6 g of compound 3 with a yield of 81% and a purity of 99%. The hydrogen spectrum was: 19 F-NMR (CD 3 CN): 43.0 2F, 53.0 2F, indicating that compound 3 was synthesized.

[0072] The preparation reaction formula of compound 3 of this embodiment is shown below.

[0073]

[0074] Example 6

[0075] This embodiment is for preparing compound 4, and its preparation method includes the following steps.

[0076] (1) 20 g of compound 8 and 50 g of dimethyl carbonate were stirred at 30° C. for 10 min to form a first solution.

[0077] (2) The second solution was added dropwise to the first solution and reacted at 60° C. for 10 h to obtain a primary product. The second solution was formed by uniformly mixing 8.5 g of lithium hexafluorophosphate and 50 g of dimethyl carbonate.

[0078] (3) The primary product was filtered, washed with dimethyl carbonate, and dried in vacuo at 70°C to obtain 14.9 g of compound 4 with a yield of 82% and a purity of 99%. Hydrogen spectrum: H NMR (400 MHz, CDCl 3 ):5.30(s,2H), 19 F-NMR (CD3CN): 58.0 4F, indicating that compound 4 was synthesized.

[0079] The preparation reaction equation of compound 4 of this embodiment is shown below.

[0080] Example 7

[0081] This embodiment is for preparing compound 5, and its preparation method includes the following steps.

[0082]

[0083] (1) 20 g of compound VII and 50 g of acetonitrile were stirred at 30° C. for 10 min to form a first solution.

[0084] (2) The second solution was added dropwise to the first solution and reacted at 80° C. for 15 h to obtain a primary product. The second solution was formed by mixing 2.9 g of lithium tetrafluoroborate and 50 g of acetonitrile.

[0085] (3) The primary product was filtered, washed with acetonitrile, and dried in vacuo at 70°C to obtain 9.7 g of compound 5 with a yield of 85% and a purity of 99%. The hydrogen spectrum was: 19 F-NMR (CD 3 CN): 44.0 2F, 56.0 4F, indicating that compound 5 was synthesized.

[0086] The preparation reaction formula of compound 5 of this example is shown below.

[0087]

[0088] Example 8

[0089] This embodiment is for preparing compound 6, and its preparation method includes the following steps.

[0090] (1) 20 g of compound VII and 50 g of acetonitrile were stirred at 30° C. for 10 min to form a first solution.

[0091] (2) The second solution was added dropwise to the first solution and reacted at 80° C. for 15 h to obtain a primary product. The second solution was formed by uniformly mixing 4.7 g of lithium hexafluorophosphate and 50 g of acetonitrile.

[0092] (3) The primary product was filtered, washed with acetonitrile, and dried in vacuo at 70°C to obtain 10.6 g of compound VI with a yield of 80% and a purity of 99%. Hydrogen spectrum: 1H NMR (400 MHz, CD 3 CN):5.60(s,4H), 19 F-NMR (CD 3 CN):57.02F, indicating that compound VI was synthesized.

[0093] The preparation reaction formula of compound 6 of this example is shown below.

[0094]

[0095] Part III: Application of cyclic methylene disulfonic acid lithium salt compounds in secondary batteries

[0096] 1g of compounds 1 to 6 prepared in Examples 3 to 8 and 87g of non-aqueous organic solvent (ethylene carbonate EC and ethyl methyl carbonate EMC in a mass ratio of 3:7) were mixed evenly, and then 12g of lithium hexafluorophosphate LiPF was added. 6 After uniform mixing, non-aqueous electrolyte 1# to 6# are prepared.

[0097] 88g of non-aqueous organic solvent (ethylene carbonate EC, ethyl methyl carbonate EMC according to the mass ratio of 3:7) and 12g of lithium hexafluorophosphate LiPF 6 After mixing evenly, non-aqueous electrolyte 7# is prepared.

[0098] Lithium cobalt oxide was used as the positive electrode material and lithium metal was used as the counter electrode. Non-aqueous electrolytes 1# to 7# were injected respectively to assemble button cells 1# to 7#. At room temperature (25°C), the button cells were charged and discharged at 3.0C / 3.0C (the battery discharge capacity was recorded as C 0 ), the upper limit voltage is 4.1V, and then 3.0C / 3.0C charging and discharging are carried out for 300 cycles, and the capacity retention rate is calculated.

[0099] Capacity retention rate = (battery capacity after 200 cycles C 1 / Battery initial capacity C 0 )*100%

[0100] Table 1 Electrochemical performance test results of each example

[0101]

[0102] From the results in Table 1, it can be seen that the cycle performance of button batteries 1 to 6# is better than that of button batteries 7#. This is because the electrolyte of button batteries 1 to 6# contains cyclic methylene disulfonic acid lithium salt compounds, which as a conductive lithium salt contains lithium ions and sulfonic acid groups, and can improve the cycle performance of the battery.

[0103] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention is described in detail with reference to the preferred embodiments, it is not limited to those listed in the embodiments. Those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A cyclic methylene disulfonic acid lithium salt compound, characterized in that: The structural formula is as shown in Formula 1 or Formula 2, R1 is CH2, CF2 or CHF; X1 is BF2 or PF4, X2 is B or PF2, 2. The cyclic methylene disulfonic acid lithium salt compound according to claim 1, characterized in that including at least one of compounds 1 to 6, 3. The method for preparing the cyclic methylene disulfonic acid lithium salt compound according to claim 1 or 2, characterized in that: Includes steps: (1) mixing the compound represented by formula 3 and a first solvent to form a first solution; (2) adding the first solution and the second solution dropwise and mixing them and reacting them under certain heating conditions to obtain a primary product, wherein the second solution is a salt solution, and the salt solution is a mixed solution of tetrafluoroborate and the first solvent or a mixed solution of hexafluorophosphate and the first solvent; (3) purifying and drying the primary product, Wherein, R1 is CH2, CF2 or CHF.

4. The method for preparing the cyclic methylene disulfonic acid lithium salt compound according to claim 3, characterized in that: The compound represented by formula 3 can be prepared by reacting methyl disulfonic acid with hexamethylsiloxane under condensation reflux and stirring, removing water and then distilling.

5. The method for preparing the cyclic methylene disulfonic acid lithium salt compound according to claim 3, characterized in that: The first solvent includes at least one of a nitrile solvent, a halogenated hydrocarbon solvent, an ether solvent, an ester solvent, a ketone solvent and an aromatic hydrocarbon solvent.

6. The method for preparing the cyclic methylene disulfonic acid lithium salt compound according to claim 3, characterized in that: The temperature during the mixing in step (1) is 0 to 100° C. and the time is 10 to 60 hours.

7. The method for preparing the cyclic methylene disulfonic acid lithium salt compound according to claim 3, characterized in that: The heating condition of step (2) is 40-90° C., and the reaction time is 1-24 h.

8. The method for preparing the cyclic methylene disulfonic acid lithium salt compound according to claim 3, characterized in that: The molar ratio of the compound represented by formula 3 to the salt solution is 1 to 2:

1.

9. The method for preparing the cyclic methylene disulfonic acid lithium salt compound according to claim 3, characterized in that: The purification is filtering or washing, and the drying condition is vacuum drying at 35-120° C. for 1-24 hours.

10. Use of the cyclic methylene disulfonic acid lithium salt compound prepared by the cyclic methylene disulfonic acid lithium salt compound according to claim 1 or 2 or the method for preparing the cyclic methylene disulfonic acid lithium salt compound according to any one of claims 3 to 9 in a secondary battery.

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