Lithium imine compound, preparation method thereof and application of lithium imine compound in battery

Abstract

The invention provides an imine lithium compound, a preparation method thereof and application of the imine lithium compound in a battery. The structural formula of the lithium imide compound is as shown in the formula I in the specification. The preparation method of the lithium imide compound comprises the following steps: adding sulfuryl fluoride, ammonia gas and an acid-binding agent, and carrying out ammonification reaction to obtain a first intermediate; adding phosphorus trichloride into the first intermediate, and carrying out phosphating reaction to obtain a second intermediate; adding ethylene glycol into the second intermediate for substitution reaction to obtain a third intermediate; and adding a lithiation compound into the third intermediate to carry out lithiation reaction. As a new substance, the lithium imide compound contains a fluorosulfonyl imide group and a cyclic phosphate group, has the advantages of cyclic phosphate, sulfonyl imide group and fluoro group, has a good application prospect, can be applied to a secondary battery, and can also be used as an intermediate for material and medicine processing. # 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 lithium imide compound and a preparation method thereof, and the application of the lithium imide compound and the preparation method thereof in a battery, and the application of the compound in a battery. Background Art

[0002] With the rapid development of pure electric vehicles and hybrid electric vehicles, people's requirements for the energy density, long cycle life, rate performance and safety performance of lithium-ion batteries are constantly increasing. The positive electrode material of lithium-ion batteries has shifted from lithium iron phosphate and lithium manganese oxide systems to high-voltage ternary material systems.

[0003] The electrolyte is the blood of lithium-ion batteries. It plays a role in transferring 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. In the traditional electrolyte system, the ternary materials will undergo obvious interfacial catalytic reactions under high voltage and high temperature conditions, resulting in the decomposition and gas production of the electrolyte, which makes it difficult to ensure the life and safety of the lithium-ion battery. At present, studies have reported that adding some additives that can form films at the interface of ternary materials (such as organic additives VC, PS, DTD, TMSP, inorganic additives LiPO2F2, LiFSI, LiTFSI, LiPF2(C2O4)2, LiBOB, etc.) to the electrolyte can effectively protect the positive electrode, improve the withstand voltage window of the electrolyte and the cycle life of the battery.

[0004] However, researchers have also found that these additives can not only form CEI at the interface of positive electrode materials, but also form SEI at the interface of graphite negative electrode, which increases the internal resistance of the battery and affects the rate and low temperature performance of the battery. Therefore, developing an additive that can form a good protective film at the interface of positive and negative electrode materials and has a small internal resistance is still a difficult problem that the industry needs to consider urgently. Summary of the invention

[0005] Based on the above problems, the object of the present invention is to provide a lithium imide compound and a preparation method thereof, and application in a battery. The preparation method is simple to operate, and the yield and purity of the target product are high. As a new substance, the lithium imide compound includes a fluorosulfonyl imide group and a cyclic phosphate group, has good application prospects, and can be applied to material processing, the medical field and secondary batteries.

[0006] To achieve the above-mentioned purpose, the first aspect of the present invention provides a lithium imide compound, the structural formula of which is shown in Formula 1.

[0007]

[0008] The lithium imide compound of the present invention is a new substance containing a fluorinated sulfonyl imide group and a cyclic phosphate group, and has the advantages of a cyclic phosphate, a sulfonyl imide group and a fluorine group, and has good application prospects. It can be used in secondary batteries and can also be used as an intermediate for material and pharmaceutical processing.

[0009] The second aspect of the present invention provides a method for preparing a lithium imide compound, comprising the steps of:

[0010] (1) Amination reaction

[0011] adding sulfuryl fluoride, ammonia gas and an acid-binding agent to carry out an amination reaction to obtain a first intermediate;

[0012] (2) Phosphation reaction

[0013] adding phosphorus trichloride to the first intermediate to carry out a phosphating reaction to obtain a second intermediate;

[0014] (3) Substitution reaction

[0015] Adding ethylene glycol to the second intermediate to carry out a substitution reaction to obtain a third intermediate;

[0016] (4) Lithiation reaction

[0017] A lithium compound is added to the third intermediate to carry out a lithium reaction.

[0018] The preparation method of the invention is simple, and an organic lithium compound containing a cyclic phosphate, a sulfonyl imide group and a fluorine group can be prepared through an amination reaction, a phosphation reaction, a substitution reaction and a lithiation reaction in sequence. The organic lithium compound is easy to produce industrially and can be promoted for use.

[0019] As a technical solution of the present invention, an organic solvent is added to the raw materials of the amination reaction, the phosphation reaction and the lithiation reaction, and the organic solvents independently include at least one of N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, 1,4-dioxane, toluene, acetonitrile, ether, tetrahydrofuran, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate and propylene carbonate.

[0020] As a technical solution of the present invention, the acid binding agent includes at least one of triethylamine, pyridine and 1,8-diazabicycloundec-7-ene.

[0021] As a technical solution of the present invention, the molar ratio of the sulfuryl fluoride to the ammonia is 1:1-2, and the molar ratio of the sulfuryl fluoride to the acid binding agent is 1-4:1.

[0022] As a technical solution of the present invention, the molar ratio of the first intermediate to the phosphorus trichloride is 0.01-1.00:0.01-1.00, the molar ratio of the second intermediate to the ethylene glycol is 1:1-10, and the molar ratio of the third intermediate to the lithium compound is 1:0.1-2.0.

[0023] As a technical solution of the present invention, the lithium compound includes lithium methoxide, lithium ethoxide, lithium isopropoxide or lithium tert-butoxide.

[0024] As a technical solution of the present invention, the temperature of the amination reaction is -40 to 50°C, the time of the amination reaction is 1 to 10 hours, the temperature of the phosphating reaction is 20 to 100°C, the time of the phosphating reaction is 5 to 25 hours, the temperature of the substitution reaction is 20 to 150°C, the time of the substitution reaction is 10 to 36 hours, the temperature of the lithiation reaction is -25 to 10°C, and the time of the lithiation reaction is 0.1 to 2.0 hours.

[0025] As a technical solution of the present invention, the amination reaction, the phosphation reaction, the substitution reaction and the lithiation reaction are carried out in different reactors.

[0026] The third aspect of the present invention provides the application of lithium imide compounds in secondary batteries. The lithium imide compounds can not only form a good protective film at the interface of positive and negative electrode materials, but also have low internal resistance, can improve the electrochemical performance of the battery, and have good application prospects. DETAILED DESCRIPTION

[0027] The lithium imide compounds of the present invention can be used as intermediates for the synthesis of materials or medicines, and can also be used in secondary batteries. In particular, the lithium imide compounds are used in secondary batteries such as lithium ion batteries or sodium ion batteries. As a new film-forming compound, they can not only form a good protective film at the interface of positive and negative electrode materials, but also have a small internal resistance, and can improve the electrochemical properties of the secondary battery, such as the cycle performance at a high rate.

[0028] The structural formula of the lithium imide compound of the present invention is shown in Formula 1.

[0029]

[0031] The preparation method of the lithium imide compound of the present invention may include the following steps.

[0032] (1) Amination reaction

[0033] Sulfuryl fluoride, ammonia gas and an acid-binding agent are added to carry out an amination reaction to obtain a first intermediate.

[0034] (2) Phosphation reaction

[0035] Phosphorus trichloride is added to the first intermediate to carry out a phosphating reaction to obtain a second intermediate.

[0036] (3) Substitution reaction

[0037] Ethylene glycol is added to the second intermediate to carry out a substitution reaction to obtain a third intermediate.

[0038] (4) Lithiation reaction

[0039] A lithium compound is added to the third intermediate to carry out a lithium reaction.

[0040] The acid-binding agent includes at least one of triethylamine, pyridine and 1,8-diazabicycloundec-7-ene, and the acid-binding agent can absorb the acid generated in the reaction so that the acid does not affect the progress of the reaction. The lithium compound includes lithium methoxide, lithium ethoxide, lithium isopropoxide or lithium tert-butoxide. The raw materials sulfuryl fluoride, ammonia, acid-binding agent, phosphorus trichloride, ethylene glycol and lithium compound involved in the preparation method of the lithium imide compound of the present invention are all conventional substances and can be obtained from the market. The reaction conditions are simple and thus convenient for industrial promotion.

[0041] The reaction formula of the amination reaction in step (1) is shown below.

[0042]

[0043] An organic solvent may be added to the raw materials of the amination reaction, and the organic solvent includes at least one of N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, 1,4-dioxane, toluene, acetonitrile, ether, tetrahydrofuran, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate and propylene carbonate. The molar ratio of sulfuryl fluoride to ammonia is 1:1-2. As an example, the molar ratio of sulfuryl fluoride to ammonia can be, but is not limited to, 1:1.0, 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. Preferably, the molar ratio of sulfuryl fluoride to ammonia is 1:1.0. The molar ratio of sulfuryl fluoride to the acid binding agent is 1 to 4:1. As an example, the molar ratio of sulfuryl fluoride to the acid binding agent can be, but not limited to, 1:1, 2:1, 3:1, 4:1. Preferably, the molar ratio of sulfuryl fluoride to the acid binding agent is 1:1. The temperature of the amination reaction is -40 to 50°C. As an example, the temperature can be, but not limited to, -40°C, -30°C, -20°C, -10°C, 0°C, 10°C, 20°C, 30°C, 40°C, 50°C. The time of the amination reaction is 1 to 10h. As an example, the time can be, but not limited to, 1h, 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h, 10h.

[0044] The reaction formula of the phosphating reaction in step (2) is shown below.

[0045]

[0046] The phosphating reaction can be carried out in other reactors, and an organic solvent can be added to the raw materials, and the organic solvent includes at least one of N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, 1,4-dioxane, toluene, acetonitrile, ether, tetrahydrofuran, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate and propylene carbonate. The molar ratio of the first intermediate to phosphorus trichloride is 0.01-1.00:0.01-1.00. As an example, the molar ratio may be, but is not limited to, 0.01:0.02, 0.01:0.10, 0.01:0.50, 0.01:1.00, 0.10:0.01, 0.10:0.05, 0.10:0.50, 0.10:1.00, 0.50:0.01, 0.50:0.10, 0.50:0.60, 0.50:1.00, 1.00:0.01, 1.00:0.15, 1.00:0.55, 1.00:1.00. Preferably, the molar ratio of the first intermediate to phosphorus trichloride is 1.00:1.00. The temperature of the phosphating reaction is 20-100° C., for example, the temperature may be, but not limited to, 20° C., 30° C., 40° C., 50° C., 60° C., 70° C., 80° C., 90° C., 100° C. The time of the phosphating reaction is 5-25 hours, for example, the time may be, but not limited to, 5 hours, 8 hours, 10 hours, 13 hours, 15 hours, 18 hours, 20 hours, 23 hours, 25 hours.

[0047] The reaction formula of the substitution reaction in step (3) is shown below.

[0048]

[0049] The substitution reaction can be carried out in other reactors, and an organic solvent can be added to the raw materials, and the organic solvent includes at least one of N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, 1,4-dioxane, toluene, acetonitrile, ether, tetrahydrofuran, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate and propylene carbonate. The molar ratio of the second intermediate to ethylene glycol is 1:1-10. As an example, the molar ratio can be but is not limited to 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10. Preferably, the molar ratio of the second intermediate to ethylene glycol is 1:5. The temperature of the substitution reaction is 20 to 150° C., for example, the temperature may be, but is not limited to, 20° C., 30° C., 40° C., 50° C., 60° C., 70° C., 80° C., 90° C., 100° C., 110° C., 120° C., 130° C., 140° C., 150° C. The time of the substitution reaction is 10 to 36 hours, for example, the time may be, but is not limited to, 10 hours, 13 hours, 15 hours, 18 hours, 20 hours, 23 hours, 25 hours, 28 hours, 30 hours, 33 hours, 36 hours.

[0050] The reaction formula of the lithiation reaction in step (4) is as follows: M is an alkane, and specifically M is a methyl group, an ethyl group, an isopropyl group or a tert-butyl group.

[0051]

[0052] The lithiation reaction can be carried out in other reactors, and an organic solvent can be added to the raw materials, and the organic solvent includes at least one of N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, 1,4-dioxane, toluene, acetonitrile, ether, tetrahydrofuran, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate and propylene carbonate. The lithium compound includes lithium methoxide, lithium ethoxide, lithium isopropoxide or lithium tert-butoxide. The molar ratio of the third intermediate to the lithium compound is 1:0.1 to 2.0. As an example, the molar ratio can be but is not limited to 1:0.1, 1:0.5, 1:0.7, 1:1.0, 1:1.2, 1:1.4, 1:1.6, 1:1.8, 1:2.0. Preferably, the molar ratio of the third intermediate to the lithium compound is 1:1.0. The temperature of the lithiation reaction is -20 to 10° C., for example, the temperature may be, but is not limited to, -20° C., -15° C., -10° C., -5° C., -0° C., 5° C., 10° C. The time of the lithiation reaction is 0.1 to 2.0 h, for example, the time may be, but is not limited to, 0.1 h, 0.3 h, 0.5 h, 0.8 h, 1.0 h, 1.3 h, 1.5 h, 1.8 h, 2.0 h.

[0053] 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.

[0054] Example 1

[0055] This embodiment is for preparing lithium imide compounds, and the preparation method thereof includes the following steps.

[0056] (1) Amination reaction

[0057] In a 1000ml autoclave, add 500g acetonitrile and 103g triethylamine, cool to 0-5°C, introduce 102g sulfuryl fluoride, slowly add 17g ammonia, control the temperature at -25-0°C and keep warm for 3.5h, concentrate the organic layer, add dichloromethane and wash, concentrate the organic layer to obtain 75g of the first intermediate, with a yield of 75%. The first intermediate was characterized by mass spectrometry data: 19 F-NMR (CD3CN): 53.0 1F, indicating that the first intermediate was synthesized.

[0058] (2) Phosphation reaction

[0059] In a 1000ml three-necked flask, add 500ml tetrahydrofuran, 99g of the first intermediate, and 137g of phosphorus trichloride, heat to 40-50℃ and keep warm for 10h, concentrate the organic layer to obtain 105g of the second intermediate, with a yield of 52%. The second intermediate was characterized by mass spectrometry data. 19 F-NMR (CD3CN): 53.51F, indicating that the second intermediate was synthesized.

[0060] (3) Substitution reaction

[0061] In a 1000ml three-necked flask, add 500g of ethylene glycol and 100g of the second intermediate, raise the temperature to 90-120°C and keep the reaction for 24h, and concentrate the organic layer to obtain 70g of the third intermediate with a yield of 74%. The third intermediate was characterized by mass spectrometry data. 19 F-NMR (CD3CN): 53.5 1F; H-NMR (CD3CN): 2.1 1H, 3.7 4H, indicating that the third intermediate was synthesized.

[0062] (4) Lithiation reaction

[0063] In a 1000ml three-necked flask, add 500g of acetonitrile and 95g of the third intermediate, cool to 0-5°C, slowly add 19g of lithium methoxide, keep warm at 0-5°C for 0.5h, concentrate the organic layer, add dichloromethane for crystallization, and obtain 80g of product with a yield of 82%. The product was characterized by mass spectrometry data: 19 F-NMR (CD3CN): 53.5 1F; H-NMR (CD3CN): 3.74H, indicating that the lithium imide compound of formula 1 was synthesized.

[0064] Example 2

[0065] This embodiment is an application of lithium amide compounds in secondary batteries.

[0066] 1.0 g of the lithium imide compound prepared in Example 1 and 87.0 g of a non-aqueous organic solvent (ethylene carbonate EC, diethyl carbonate DEC, ethyl methyl carbonate EMC in a mass ratio of 1:2:1) were mixed evenly, and then 12.0 g of lithium hexafluorophosphate LiPF6 was added and mixed evenly to prepare a non-aqueous electrolyte 1#.

[0067] 3.0 g of the lithium imide compound prepared in Example 1 and 86.0 g of a non-aqueous organic solvent (ethylene carbonate EC, diethyl carbonate DEC, ethyl methyl carbonate EMC in a mass ratio of 1:2:1) were mixed evenly, and then 11.0 g of lithium hexafluorophosphate LiPF6 was added and mixed evenly to prepare a non-aqueous electrolyte 2#.

[0068] 12.0 g of lithium hexafluorophosphate LiPF6 was added to 88.0 g of non-aqueous organic solvent (ethylene carbonate EC, diethyl carbonate DEC, ethyl methyl carbonate EMC in a mass ratio of 1:2:1) and mixed evenly to prepare non-aqueous electrolyte 1#.

[0069] Lithium cobalt oxide was used as the positive electrode material and lithium metal was used as the counter electrode. Non-aqueous electrolytes 1# to 3# were injected respectively to assemble button batteries 1# to 3#. At room temperature (25°C), the button batteries were charged and discharged at 4.0C / 4.0C (the battery discharge capacity was recorded as C0), the upper limit voltage was 4.55V, and then 4.0C / 4.0C was charged and discharged for 300 weeks, and the capacity retention rate was calculated.

[0070] Capacity retention rate = (battery capacity C1 after 300 cycles / battery initial capacity C0) * 100%

[0071] Table 1 Electrochemical performance test results of each example

[0072]

[0073] From the results in Table 1, it can be seen that the cycle performance of button batteries 1 to 2# at high rates is better than that of button batteries 3#. This is because the electrolyte of button batteries 1 to 2# contains lithium imide compounds, fluorinated sulfonyl imide groups and cyclic phosphate groups, which have the advantages of cyclic phosphate, sulfonyl imide groups and fluorine groups, can form a good protective film at the interface of positive and negative electrode materials, and has low internal resistance, which can improve the cycle performance of the battery at high rates.

[0074] 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 lithium imide compound, characterized in that: The structural formula is shown in Formula 1.

2. The method for preparing the lithium imide compound according to claim 1, characterized in that: Includes steps: (1) Amination reaction adding sulfuryl fluoride, ammonia gas and an acid-binding agent to carry out an amination reaction to obtain a first intermediate; (2) Phosphation reaction adding phosphorus trichloride to the first intermediate to carry out a phosphating reaction to obtain a second intermediate; (3) Substitution reaction Adding ethylene glycol to the second intermediate to carry out a substitution reaction to obtain a third intermediate; (4) Lithiation reaction A lithium compound is added to the third intermediate to carry out a lithium reaction.

3. The method for preparing the lithium imide compound according to claim 2, characterized in that: An organic solvent is added to the raw materials of the amination reaction, the phosphation reaction and the lithiation reaction, and the organic solvents independently include at least one of N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, 1,4-dioxane, toluene, acetonitrile, ether, tetrahydrofuran, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate and propylene carbonate.

4. The method for preparing the lithium imide compound according to claim 2, characterized in that: The acid binding agent includes at least one of triethylamine, pyridine and 1,8-di-azabicycloundec-7-ene.

5. The method for preparing the lithium imide compound according to claim 2, characterized in that: The molar ratio of the sulfuryl fluoride to the ammonia is 1:1-2, and the molar ratio of the sulfuryl fluoride to the acid binding agent is 1:1-4.

6. The method for preparing the lithium imide compound according to claim 2, characterized in that: The molar ratio of the first intermediate to the phosphorus trichloride is 0.01-1.00:0.01-1.00, the molar ratio of the second intermediate to the ethylene glycol is 1:1-10, and the molar ratio of the third intermediate to the lithium compound is 1:0.1-2.

0.

7. The method for preparing lithium imide compounds according to claim 2, characterized in that: The lithium compound includes lithium methoxide, lithium ethoxide, lithium isopropoxide or lithium tert-butoxide.

8. The method for preparing lithium imide compounds according to claim 2, characterized in that: The temperature of the amination reaction is -40 to 50°C, and the time of the amination reaction is 1 to 10 hours. The temperature of the phosphating reaction is 20 to 100°C, and the time of the phosphating reaction is 5 to 25 hours. The temperature of the substitution reaction is 20 to 150°C, and the time of the substitution reaction is 10 to 36 hours. The temperature of the lithiation reaction is -25 to 10°C, and the time of the lithiation reaction is 0.1 to 2.0 hours.

9. The method for preparing lithium imide compounds according to claim 2, characterized in that: The amination reaction, the phosphation reaction, the substitution reaction and the lithiation reaction are carried out in different reactors.

10. Use of the lithium imide compound according to claim 1 or the method for preparing the lithium imide compound according to any one of claims 2 to 9 in a secondary battery.

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