A non-aqueous lithium battery electrolyte and a lithium battery

Abstract

The present invention relates to a non-aqueous lithium battery electrolyte and a lithium battery, and mainly solves the problems of poor cycling performance and large internal resistance of the lithium battery at high temperatures. By adding the compound shown in formula (1) and / or the compound shown in formula (2), the non-aqueous lithium battery electrolyte can form a dense film on the lithium battery electrode sheet, enabling the battery to have better cycling performance and smaller internal resistance at high temperatures.

Description

Technical Field

[0001] The invention relates to a non-aqueous lithium battery electrolyte and a lithium battery. Background Art

[0002] Lithium-ion battery technology is becoming more and more important in people's daily lives. With the development of new energy, the use of clean energy is becoming more and more extensive. From small electronic components to large cars and airplanes, lithium-ion batteries are used in almost all places where power is used. Therefore, in recent years, the development of battery technology has also increased rapidly. The vast market provides more development opportunities but also brings greater challenges. The widespread use of lithium-ion batteries has led to higher requirements for battery technology to adapt to the battery use environment. The market requires batteries to maintain good performance in different harsh environments. A larger temperature range has become an important topic in battery development. At the same time, widespread use has also put forward higher requirements for battery safety performance. How to solve the problem of poor safety performance of batteries at high energy density is particularly urgent. In order to solve this problem, people need to make more progress in battery materials.

[0003] As the blood of the battery, the electrolyte has a great influence on the high and low temperature performance of the battery. According to the literature, film-forming additives are usually added to the battery electrolyte to improve the cycle performance of the battery. For example, the use of vinylene carbonate can form a good film on the surface of the battery electrode during battery formation to prevent the further reaction. However, the film formed by adding vinylene carbonate is easily decomposed at high temperatures and is constantly destroyed, resulting in the battery being unable to function at high temperatures. For example, adding additives such as lithium bis(oxalatoborate) to the electrolyte can form a good film at high temperatures, but due to the large thickness of the film and the low conductivity of the film, the internal resistance of the battery will be too large, thereby affecting the performance of the battery. Similarly, adding flame retardant additives to the electrolyte can also play a certain role in the safety performance of the battery, but at the same time, most flame retardant additives will have more or less effects on other properties of the battery.

[0004] Based on this, how to improve the high-temperature cycle performance of the battery while reducing the internal resistance of the battery at high temperatures has become a technical problem that urgently needs to be solved. Summary of the invention

[0005] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a non-aqueous lithium battery electrolyte and a lithium battery with good cycle performance and good internal resistance performance at high temperature.

[0006] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] A non-aqueous lithium battery electrolyte, comprising a lithium salt, an organic solvent, and an additive, wherein the additive comprises a compound represented by formula (1) and / or a compound represented by formula (2), and formula (1) is Formula (2) is Wherein, R1, R2, R3, R4, R5, R6, and R7 in formula (1) are each independently selected from hydrogen, hydroxyl, halogen, alkyl, alkoxy, haloalkoxy, haloalkyl, alkenyl, haloalkenyl, amino, ester group, aryl, or nitrile group; R1, R2, R3, R4, R5, R6, and R7 in formula (2) are the same as R1, R2, R3, R4, R5, R6, and R7 in formula (1) respectively; and R8 in formula (2) is selected from hydrogen, hydroxyl, halogen, alkyl, alkoxy, haloalkoxy, haloalkyl, alkenyl, haloalkenyl, amino, ester group, aryl, or nitrile group.

[0008] Preferably, R1, R2, R3, R4, R5, R6, R7, and R8 are each independently selected from hydrogen, hydroxyl, alkyl, and haloalkoxy.

[0009] More preferably, R1, R2, R3, R4, R5, R6, R7, and R8 are each independently selected from hydrogen, hydroxyl, alkyl having 1 to 3 carbon atoms, and haloalkoxy having 1 to 3 carbon atoms.

[0010] Even more preferably, R1, R2, R7, and R8 are each independently selected from alkyl having 1 to 3 carbon atoms, haloalkoxy having 1 to 3 carbon atoms, and hydroxyl; R4 and R5 are each hydrogen; and R3 and R6 are each independently selected from alkyl having 1 to 3 carbon atoms or hydrogen.

[0011] Preferably, the halogen in the halogenation is fluorine.

[0012] According to some preferred embodiments, the compound represented by formula (1) includes and / or

[0013] According to some preferred embodiments, the compound represented by formula (2) includes one or more of

[0014] Preferably, the compound represented by formula (1) accounts for 1 to 10% of the total mass of the non-aqueous lithium battery electrolyte.

[0015] More preferably, the compound represented by formula (1) accounts for 3 to 10% of the total mass of the non-aqueous lithium battery electrolyte.

[0016] More preferably, the compound represented by the formula (1) accounts for 5-10% of the total mass of the non-aqueous lithium battery electrolyte.

[0017] Preferably, the compound represented by the formula (2) accounts for 1-10% of the total mass of the non-aqueous lithium battery electrolyte.

[0018] More preferably, the compound represented by the formula (2) accounts for 3-10% of the total mass of the non-aqueous lithium battery electrolyte.

[0019] Even more preferably, the compound represented by the formula (2) accounts for 5-10% of the total mass of the non-aqueous lithium battery electrolyte.

[0020] Preferably, the additive further includes one or more of lithium difluorophosphate, vinylene sulfate, and succinonitrile.

[0021] More preferably, the lithium difluorophosphate accounts for 1-2% of the total mass of the non-aqueous lithium battery electrolyte.

[0022] More preferably, the vinylene sulfate accounts for 0.5-1% of the total mass of the non-aqueous lithium battery electrolyte.

[0023] More preferably, the succinonitrile accounts for 0.5-1% of the total mass of the non-aqueous lithium battery electrolyte.

[0024] Preferably, the lithium salt is selected from one or more of LiPF6, LiBF4, LiClO4, LiCH3SO3, LiSCN, LiNO3, LiO3SCF2CF3, LiAsF6, and LiAlCl4.

[0025] More preferably, the concentration of the lithium salt in the non-aqueous lithium battery electrolyte is 0.7-1.5 mol / L.

[0026] Even more preferably, the concentration of the lithium salt in the non-aqueous lithium battery electrolyte is 0.9-1.2 mol / L.

[0027] Preferably, the organic solvent includes one or more of carbonates, carboxylates, ethers, and sulfone solvents.

[0028] More preferably, the carbonates include one or more of ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, and propylene carbonate.

[0029] More preferably, the carboxylates include cyclic carboxylates and / or chain carboxylates. When the cyclic carboxylate and the chain carboxylate are used simultaneously, the mass ratio of the cyclic carboxylate to the carboxylate is 1:(0.5-2.5).

[0030] More preferably, the carboxylic acid ester includes one or more of methyl formate, ethyl formate, methyl acetate, ethyl acetate, propyl acetate, ethyl propionate, methyl butyrate, and ethyl butyrate.

[0031] Preferably, the ether includes one or more of dimethoxymethane, 1,2 - dimethoxyethane, tetrahydrofuran, and 1,3 - dioxolane.

[0032] Preferably, the sulfone includes one or more of dimethyl sulfoxide, sulfolane, and dimethyl sulfone.

[0033] According to some preferred embodiments, the organic solvent is a mixed solvent of ethylene carbonate, ethyl methyl carbonate, dimethyl carbonate, and propylene carbonate with a mass ratio of (2 - 6):(5 - 11):(1 - 2):1.

[0034] More preferably, the organic solvent is a mixed solvent of ethylene carbonate, ethyl methyl carbonate, dimethyl carbonate, and propylene carbonate with a mass ratio of (2 - 3):(5 - 7):(1 - 1.5):1.

[0035] Another aspect of the present invention provides a lithium battery, which uses the above non - aqueous lithium battery electrolyte.

[0036] Due to the application of the above technical solutions, the present invention has the following advantages compared with the prior art:

[0037] The non - aqueous lithium battery electrolyte of the present invention can form a dense film on the lithium battery electrode sheet. This film can not only stably exist at high temperatures but also has a high ionic conductivity, enabling the battery to have good cycling performance and a small internal resistance at high temperatures. Detailed Embodiments

[0038] In order to improve the cycling performance of the battery at high temperatures, some additives are often added to the electrolyte. However, the addition of additives will more or less affect other properties of the battery. For example, it will cause the internal resistance of the battery to be too large at high temperatures. How to enable the battery to have both good high - temperature cycling performance and a small internal resistance has become a difficulty in the prior art. Based on the deficiencies of the prior art, the applicant has obtained the solution of this application through long - term experiments and extensive research. The following further elaborates on this solution.

[0039] A non - aqueous lithium battery electrolyte includes a lithium salt, an organic solvent, and an additive. The additive includes the compound shown in formula (1) and / or the compound shown in formula (2). Formula (1) is Formula (2) is

[0040] In the present invention, R1, R2, R3, R4, R5, R6, and R7 in formula (1) are each independently selected from hydrogen, hydroxyl, halogen, alkyl, alkoxy, haloalkoxy, haloalkyl, alkenyl, haloalkenyl, amino, ester, aryl, or nitrile. R1, R2, R3, R4, R5, R6, and R7 in formula (2) are the same as R1, R2, R3, R4, R5, R6, and R7 in formula (1), respectively, and R8 in formula (2) is selected from hydrogen, hydroxyl, halogen, alkyl, alkoxy, haloalkoxy, haloalkyl, alkenyl, haloalkenyl, amino, ester, aryl, or nitrile. In the present invention, the halogen or halogenated halogen is fluorine, chlorine, or bromine. The alkyl includes linear alkyl and cyclic alkyl, such as methyl, ethyl, propyl, isopropyl, butyl, cyclopropyl, cyclobutyl, etc. The alkoxy includes, but is not limited to, common alkoxys such as methoxy, ethoxy, propoxy, etc. The alkenyl includes, but is not limited to, common alkenyls such as vinyl, propenyl, butenyl, etc. The ester includes, but is not limited to, common esters such as methyl formate, ethyl formate, propyl formate, methyl acetate, ethyl acetate, etc. If the addition amount of the compound shown in formula (1) is too low, it will not have an effect, while if the addition amount is too high, it will affect the discharge performance of the battery at room temperature. Preferably, the compound shown in formula (1) accounts for 1-10% of the total mass of the non-aqueous lithium battery electrolyte, such as 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%. Similarly, if the addition amount of the compound shown in formula (2) is too low, it will not have an effect, while if the addition amount is too high, it will affect the discharge performance of the battery at room temperature. Preferably, the compound shown in formula (2) accounts for 1-10% of the total mass of the non-aqueous lithium battery electrolyte, such as 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%.

[0041] According to some specific and preferred embodiments, the additive includes one or more of the following structural formulas A, B, C, D, E, and F.

[0042]

[0043] In the present invention, the addition of A, C, and F can not only improve the cycling performance of the battery at high temperature and reduce the internal resistance of the battery at high temperature, but also reduce the flammability of the electrolyte and improve the safety performance of the battery.

[0044] In the present invention, A can be synthesized from bis(trifluoroethyl)phosphoryl chloride, 1,2-dichloroethane, imidazole, and N,N-dimethylethylenediamine. The specific steps are as follows: (1) Under the protection of inert gas throughout the process, add 56 g of bis(trifluoroethyl)phosphoryl chloride, 200 ml of 1,2-dichloroethane, and 15 g of imidazole into a 500 ml three-necked flask, and control the temperature of the system below 0 °C. (2) Slowly add dropwise 50 ml of a 1,2-dichloroethane solution containing 18.5 g of N,N-dimethylethylenediamine, control the dropping rate to ensure that the reaction temperature is maintained within 5 °C. After the addition is completed, react at 20 °C - 25 °C for 2 h. (3) Slowly add 200 ml of 10% hydrochloric acid by mass to quench the reaction, let it stand for liquid separation, and wash the organic phase successively with 200 ml of 10% sodium carbonate by mass, 200 ml of water, and 200 ml of saturated sodium chloride. (4) Dry the organic phase with anhydrous sodium sulfate overnight, filter off the sodium sulfate by suction. After removing the solvent from the organic phase, place it in a vacuum drying oven and dry to constant weight to obtain 61 g of product A, with a yield of 91.9% and a purity of 99.1%.

[0045] In the present invention, F can be synthesized from bis(trifluoroethyl)phosphoryl chloride, tetrahydrofuran, and ethylenediamine. The specific steps are as follows: (1) Under the protection of inert gas throughout the process, add 45 g of bis(trifluoroethyl)phosphoryl chloride and 200 ml of tetrahydrofuran into a 500 ml three-necked flask. (2) Control the temperature of the system below 0 °C, slowly add dropwise 50 ml of a tetrahydrofuran solution containing 12 g of ethylenediamine, control the dropping rate to ensure that the reaction temperature is maintained within 5 °C. After the addition is completed, react at 25 °C for 8 h. (3) After rotary evaporation to remove the organic phase, wash the residue with deionized water 3 times, with a dosage of 100 ml each time, and then filter by suction to obtain the filter residue. (4) Place the filter residue in a vacuum drying oven and dry to constant weight to obtain 39.5 g of product F, with a yield of 89.7%, a purity of 99.3%, and a water content of 80 ppm.

[0046] In the present invention, the additive further includes one or more of lithium difluorophosphate, vinylene sulfate, and succinonitrile. When the above additives are used in combination with lithium difluorophosphate, vinylene sulfate, and succinonitrile, the cycle and internal resistance performance of the battery can be further improved. Among them, lithium difluorophosphate accounts for 1 - 2% of the total mass of the non-aqueous lithium battery electrolyte, for example: 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2%. Vinylene sulfate accounts for 0.5 - 1% of the total mass of the non-aqueous lithium battery electrolyte, for example: 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%. Succinonitrile accounts for 0.5 - 1% of the total mass of the non-aqueous lithium battery electrolyte, for example: 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%.

[0047] In the present invention, the lithium salt is selected from one or more of LiPF6, LiBF4, LiClO4, LiCH3SO3, LiSCN, LiNO3, LiO3SCF2CF3, LiAsF6, and LiAlCl4. The concentration of the lithium salt in the non-aqueous lithium battery electrolyte is 0.7 to 1.5 mol / L, for example: 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, 1 mol / L, 1.1 mol / L, 1.2 mol / L, 1.3 mol / L, 1.4 mol / L, 1.5 mol / L.

[0048] In the present invention, the organic solvent includes one or more of carbonates, carboxylates, ethers, and sulfone solvents. Among them, the carbonates include one or more of ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, and propylene carbonate. The carboxylates include one or more of methyl formate, ethyl formate, methyl acetate, ethyl acetate, propyl acetate, ethyl propionate, methyl butyrate, and ethyl butyrate. The ethers include one or more of dimethoxymethane, 1,2-dimethoxyethane, tetrahydrofuran, and 1,3-dioxolane. The sulfones include one or more of dimethyl sulfoxide, sulfolane, and dimethyl sulfone.

[0049] The present invention will be further described below in conjunction with embodiments. However, the present invention is not limited to the following embodiments. The implementation conditions adopted in the embodiments can be further adjusted according to different requirements of specific use, and the implementation conditions not specified are conventional conditions in the industry. The technical features involved in each implementation mode of the present invention can be combined with each other as long as they do not conflict with each other.

[0050] Comparative Example 1

[0051] The lithium salt LiPF6 was dissolved in a mixed solvent of ethylene carbonate / ethyl methyl carbonate / dimethyl carbonate / propylene carbonate (mass ratio 25 / 50 / 15 / 10), where the concentration of LiPF6 was 1 mol / L, to obtain a comparative electrolyte.

[0052] Example 1

[0053] The lithium salt LiPF6 was dissolved in a mixed solvent of ethylene carbonate / ethyl methyl carbonate / dimethyl carbonate / propylene carbonate (mass ratio 25 / 50 / 15 / 10), where the concentration of LiPF6 was 1 mol / L. 6% of A was added to this solution based on the total mass of the electrolyte to obtain the electrolyte of this example.

[0054] Example 2

[0055] Dissolve the lithium salt LiPF6 in a mixed solvent of ethylene carbonate / ethyl methyl carbonate / dimethyl carbonate / propylene carbonate (mass ratio 25 / 50 / 15 / 10), where the concentration of LiPF6 is 1 mol / L. Add 6% of B to this solution based on the total mass of the electrolyte to obtain the electrolyte of this example.

[0056] Example 3

[0057] Dissolve the lithium salt LiPF6 in a mixed solvent of ethylene carbonate / ethyl methyl carbonate / dimethyl carbonate / propylene carbonate (mass ratio 25 / 50 / 15 / 10), where the concentration of LiPF6 is 1 mol / L. Add 6% of C to this solution based on the total mass of the electrolyte to obtain the electrolyte of this example.

[0058] Example 4

[0059] Dissolve the lithium salt LiPF6 in a mixed solvent of ethylene carbonate / ethyl methyl carbonate / dimethyl carbonate / propylene carbonate (mass ratio 25 / 50 / 15 / 10), where the concentration of LiPF6 is 1 mol / L. Add 6% of D to this solution based on the total mass of the electrolyte to obtain the electrolyte of this example.

[0060] Example 5

[0061] Dissolve the lithium salt LiPF6 in a mixed solvent of ethylene carbonate / ethyl methyl carbonate / dimethyl carbonate / propylene carbonate (mass ratio 25 / 50 / 15 / 10), where the concentration of LiPF6 is 1 mol / L. Add 6% of E to this solution based on the total mass of the electrolyte to obtain the electrolyte of this example.

[0062] Example 6

[0063] Dissolve the lithium salt LiPF6 in a mixed solvent of ethylene carbonate / ethyl methyl carbonate / dimethyl carbonate / propylene carbonate (mass ratio 25 / 50 / 15 / 10), where the concentration of LiPF6 is 1 mol / L. Add 6% of F to this solution based on the total mass of the electrolyte to obtain the electrolyte of this example.

[0064] Example 7

[0065] Dissolve the lithium salt LiPF6 in a mixed solvent of ethylene carbonate / ethyl methyl carbonate / dimethyl carbonate / propylene carbonate (mass ratio 25 / 50 / 15 / 10), where the concentration of LiPF6 is 1 mol / L. Add 1% of A to this solution based on the total mass of the electrolyte to obtain the electrolyte of this example.

[0066] Example 8

[0067] Dissolve the lithium salt LiPF6 in a mixed solvent of ethylene carbonate / ethyl methyl carbonate / dimethyl carbonate / propylene carbonate (mass ratio 25 / 50 / 15 / 10), where the concentration of LiPF6 is 1 mol / L. Add 3% of A to this solution based on the total mass of the electrolyte to obtain the electrolyte of this example.

[0068] Example 9

[0069] Dissolve the lithium salt LiPF6 in a mixed solvent of ethylene carbonate / ethyl methyl carbonate / dimethyl carbonate / propylene carbonate (mass ratio 25 / 50 / 15 / 10), where the concentration of LiPF6 is 1 mol / L. Add 1% of F to this solution based on the total mass of the electrolyte to obtain the electrolyte of this example.

[0070] Example 10

[0071] Dissolve the lithium salt LiPF6 in a mixed solvent of ethylene carbonate / ethyl methyl carbonate / dimethyl carbonate / propylene carbonate (mass ratio 25 / 50 / 15 / 10), where the concentration of LiPF6 is 1 mol / L. Add 3% of F to this solution based on the total mass of the electrolyte to obtain the electrolyte of this example.

[0072] Example 11

[0073] Dissolve the lithium salt LiPF6 in a mixed solvent of ethylene carbonate / ethyl methyl carbonate / dimethyl carbonate / propylene carbonate (mass ratio 25 / 50 / 15 / 10), where the concentration of LiPF6 is 1 mol / L. Add 9% of A to this solution based on the total mass of the electrolyte to obtain the electrolyte of this example.

[0074] Example 12

[0075] Dissolve the lithium salt LiPF6 in a mixed solvent of ethylene carbonate / ethyl methyl carbonate / dimethyl carbonate / propylene carbonate (mass ratio 25 / 50 / 15 / 10), where the concentration of LiPF6 is 1 mol / L. Add 9% of F to this solution based on the total mass of the electrolyte to obtain the electrolyte of this example.

[0076] Example 13

[0077] Dissolve the lithium salt LiPF6 in a mixed solvent of ethylene carbonate / ethyl methyl carbonate / dimethyl carbonate / propylene carbonate (mass ratio 25 / 50 / 15 / 10), where the concentration of LiPF6 is 1 mol / L. Add 6% of A, 1% of lithium difluorophosphate, 0.5% of vinylene sulfate, and 0.5% of succinonitrile to this solution based on the total mass of the electrolyte to obtain the electrolyte of this example.

[0078] Example 14

[0079] Dissolve the lithium salt LiPF6 in a mixed solvent of ethylene carbonate / ethyl methyl carbonate / dimethyl carbonate / propylene carbonate (mass ratio 25 / 50 / 15 / 10), where the concentration of LiPF6 is 1 mol / L. Add 6% of B, 1% of lithium difluorophosphate, 0.5% of vinylene sulfate, and 0.5% of succinonitrile to this solution according to the total mass of the electrolyte to obtain the electrolyte of this example.

[0080] Example 15

[0081] Dissolve the lithium salt LiPF6 in a mixed solvent of ethylene carbonate / ethyl methyl carbonate / dimethyl carbonate / propylene carbonate (mass ratio 25 / 50 / 15 / 10), where the concentration of LiPF6 is 1 mol / L. Add 6% of C, 1% of lithium difluorophosphate, 0.5% of vinylene sulfate, and 0.5% of succinonitrile to this solution according to the total mass of the electrolyte to obtain the electrolyte of this example.

[0082] Example 16

[0083] Dissolve the lithium salt LiPF6 in a mixed solvent of ethylene carbonate / ethyl methyl carbonate / dimethyl carbonate / propylene carbonate (mass ratio 25 / 50 / 15 / 10), where the concentration of LiPF6 is 1 mol / L. Add 6% of D, 1% of lithium difluorophosphate, 0.5% of vinylene sulfate, and 0.5% of succinonitrile to this solution according to the total mass of the electrolyte to obtain the electrolyte of this example.

[0084] Example 17

[0085] Dissolve the lithium salt LiPF6 in a mixed solvent of ethylene carbonate / ethyl methyl carbonate / dimethyl carbonate / propylene carbonate (mass ratio 25 / 50 / 15 / 10), where the concentration of LiPF6 is 1 mol / L. Add 6% of E, 1% of lithium difluorophosphate, 0.5% of vinylene sulfate, and 0.5% of succinonitrile to this solution according to the total mass of the electrolyte to obtain the electrolyte of this example.

[0086] Example 18

[0087] Dissolve the lithium salt LiPF6 in a mixed solvent of ethylene carbonate / ethyl methyl carbonate / dimethyl carbonate / propylene carbonate (mass ratio 25 / 50 / 15 / 10), where the concentration of LiPF6 is 1 mol / L. Add 6% of F, 1% of lithium difluorophosphate, 0.5% of vinylene sulfate, and 0.5% of succinonitrile to this solution according to the total mass of the electrolyte to obtain the electrolyte of this example.

[0088] Example 19

[0089] Dissolve the lithium salt LiPF6 in a mixed solvent of ethylene carbonate / ethyl methyl carbonate / dimethyl carbonate / propylene carbonate (mass ratio 25 / 50 / 15 / 10), where the concentration of LiPF6 is 1 mol / L. Add 1% of A, 1% of lithium difluorophosphate, 0.5% of vinylene sulfate, and 0.5% of succinonitrile to this solution according to the total mass of the electrolyte to obtain the electrolyte of this example.

[0090] Example 20

[0091] Dissolve the lithium salt LiPF6 in a mixed solvent of ethylene carbonate / ethyl methyl carbonate / dimethyl carbonate / propylene carbonate (mass ratio 25 / 50 / 15 / 10), where the concentration of LiPF6 is 1 mol / L. Add 3% of A, 1% of lithium difluorophosphate, 0.5% of vinylene sulfate, and 0.5% of succinonitrile to this solution according to the total mass of the electrolyte to obtain the electrolyte of this example.

[0092] Example 21

[0093] Dissolve the lithium salt LiPF6 in a mixed solvent of ethylene carbonate / ethyl methyl carbonate / dimethyl carbonate / propylene carbonate (mass ratio 25 / 50 / 15 / 10), where the concentration of LiPF6 is 1 mol / L. Add 1% of F, 1% of lithium difluorophosphate, 0.5% of vinylene sulfate, and 0.5% of succinonitrile to this solution according to the total mass of the electrolyte to obtain the electrolyte of this example.

[0094] Example 22

[0095] Dissolve the lithium salt LiPF6 in a mixed solvent of ethylene carbonate / ethyl methyl carbonate / dimethyl carbonate / propylene carbonate (mass ratio 25 / 50 / 15 / 10), where the concentration of LiPF6 is 1 mol / L. Add 3% of F, 1% of lithium difluorophosphate, 0.5% of vinylene sulfate, and 0.5% of succinonitrile to this solution according to the total mass of the electrolyte to obtain the electrolyte of this example.

[0096] Example 23

[0097] Dissolve the lithium salt LiPF6 in a mixed solvent of ethylene carbonate / ethyl methyl carbonate / dimethyl carbonate / propylene carbonate (mass ratio 25 / 50 / 15 / 10), where the concentration of LiPF6 is 1 mol / L. Add 6% of A, 1% of lithium difluorophosphate, and 0.5% of succinonitrile to this solution according to the total mass of the electrolyte to obtain the electrolyte of this example.

[0098] Example 24

[0099] Dissolve the lithium salt LiPF6 in a mixed solvent of ethylene carbonate / ethyl methyl carbonate / dimethyl carbonate / propylene carbonate (mass ratio 25 / 50 / 15 / 10), where the concentration of LiPF6 is 1 mol / L. Add 6% of A, 0.5% of vinylene sulfate, and 0.5% of succinonitrile to this solution based on the total mass of the electrolyte to obtain the electrolyte of this example.

[0100] Example 25

[0101] Dissolve the lithium salt LiPF6 in a mixed solvent of ethylene carbonate / ethyl methyl carbonate / dimethyl carbonate / propylene carbonate (mass ratio 25 / 50 / 15 / 10), where the concentration of LiPF6 is 1 mol / L. Add 6% of A, 1% of lithium difluorophosphate, and 0.5% of vinylene sulfate to this solution based on the total mass of the electrolyte to obtain the electrolyte of this example.

[0102] Example 26

[0103] Dissolve the lithium salt LiPF6 in a mixed solvent of ethylene carbonate / ethyl methyl carbonate / dimethyl carbonate / propylene carbonate (mass ratio 25 / 50 / 15 / 10), where the concentration of LiPF6 is 1 mol / L. Add 6% of F, 1% of lithium difluorophosphate, and 0.5% of succinonitrile to this solution based on the total mass of the electrolyte to obtain the electrolyte of this example.

[0104] Example 27

[0105] Dissolve the lithium salt LiPF6 in a mixed solvent of ethylene carbonate / ethyl methyl carbonate / dimethyl carbonate / propylene carbonate (mass ratio 25 / 50 / 15 / 10), where the concentration of LiPF6 is 1 mol / L. Add 6% of F, 1% of lithium difluorophosphate, and 0.5% of vinylene sulfate to this solution based on the total mass of the electrolyte to obtain the electrolyte of this example.

[0106] Example 28

[0107] Dissolve the lithium salt LiPF6 in a mixed solvent of ethylene carbonate / ethyl methyl carbonate / dimethyl carbonate / propylene carbonate (mass ratio 25 / 50 / 15 / 10), where the concentration of LiPF6 is 1 mol / L. Add 6% of A, 1% of lithium difluorophosphate to this solution based on the total mass of the electrolyte to obtain the electrolyte of this example.

[0108] Example 29

[0109] Dissolve the lithium salt LiPF6 in a mixed solvent of ethylene carbonate / ethyl methyl carbonate / dimethyl carbonate / propylene carbonate (mass ratio 25 / 50 / 15 / 10), where the concentration of LiPF6 is 1 mol / L. Add 6% of A, 2% of lithium difluorophosphate to this solution based on the total mass of the electrolyte to obtain the electrolyte of this example.

[0110] Example 30

[0111] Dissolve the lithium salt LiPF6 in a mixed solvent of ethylene carbonate / ethyl methyl carbonate / dimethyl carbonate / propylene carbonate (mass ratio 25 / 50 / 15 / 10), where the concentration of LiPF6 is 1 mol / L. Add 9% of A, 1% of lithium difluorophosphate, 0.5% of vinylene sulfate, and 0.5% of succinonitrile to this solution according to the total mass of the electrolyte to obtain the electrolyte of this example.

[0112] Example 31

[0113] Dissolve the lithium salt LiPF6 in a mixed solvent of ethylene carbonate / ethyl methyl carbonate / dimethyl carbonate / propylene carbonate (mass ratio 25 / 50 / 15 / 10), where the concentration of LiPF6 is 1 mol / L. Add 9% of F, 1% of lithium difluorophosphate, 0.5% of vinylene sulfate, and 0.5% of succinonitrile to this solution according to the total mass of the electrolyte to obtain the electrolyte of this example.

[0114] Experimental results

[0115] Inject the electrolytes obtained from Comparative Example 1 and Examples 1 to 31 into lithium cobalt oxide soft-pack batteries of the same batch and the same model. Test the cycle performance of the batteries at 1C under a high-temperature environment of 45°C at 2.75 - 4.2V, test their internal resistance after being left standing at a high temperature of 60°C, and test the ignition time of the electrolyte at room temperature. The comparison data of the high-temperature cycle capacity retention rate, high-temperature standing internal resistance, and electrolyte ignition time for all comparative examples and examples are shown in Table 1 specifically.

[0116] Table 1

[0117]

[0118]

[0119] Inject the electrolytes obtained from Comparative Example 1 and Examples 1, 6 to 13, 18 to 22, 30, and 31 into lithium cobalt oxide soft-pack batteries of the same batch and the same model. Test the cycle performance of the batteries at 1C under a room-temperature environment of 25°C at 2.75 - 4.2V. The comparison data of the room-temperature cycle capacity retention rate for all comparative examples and examples are shown in Table 2 specifically as follows.

[0120] Table 2

[0121]

[0122]

[0123] The above has described the present invention in detail, aiming to enable those skilled in this field to understand the content of the present invention and implement it. However, it should not be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit and essence of the present invention should be covered within the protection scope of the present invention.

Claims

1. A non-aqueous lithium battery electrolyte, comprising a lithium salt, an organic solvent and an additive, characterized in that: The additive includes the compound shown in formula (1) and / or the compound shown in formula (2), The formula (1) is The formula (2) is wherein, R1, R2, R3, R4, R5, R6, R7 in the formula (1) are each independently selected from hydrogen, hydroxyl, halogen, alkyl, alkoxy, haloalkoxy, haloalkyl, alkenyl, haloalkenyl, amino, ester group, aryl or nitrile group; R1, R2, R3, R4, R5, R6, R7 in the formula (2) are the same as R1, R2, R3, R4, R5, R6, R7 in the formula (1) respectively, and R8 in the formula (2) is selected from hydrogen, hydroxyl, halogen, alkyl, alkoxy, haloalkoxy, haloalkyl, alkenyl, haloalkenyl, amino, ester group, aryl or nitrile group.

2. The non-aqueous lithium battery electrolyte according to claim 1, characterized in that: The R1, R2, R3, R4, R5, R6, R7, R8 are each independently selected from hydrogen, hydroxyl, alkyl, haloalkoxy.

3. The non-aqueous lithium battery electrolyte according to claim 2, wherein: The R1, R2, R7, R8 are each independently selected from alkyl with 1 to 3 carbon atoms, haloalkoxy with 1 to 3 carbon atoms, hydroxyl; R4, R5 are each hydrogen; R3, R6 are each independently selected from alkyl with 1 to 3 carbon atoms or hydrogen; and / or, the halogen in the halogenation is fluorine.

4. The non-aqueous lithium battery electrolyte according to claim 1 or 3, characterized in that: The compound represented by the formula (1) includes The compound represented by the formula (2) includes one or more of them.

5. The non-aqueous lithium battery electrolyte according to claim 1, wherein: The compound shown in the formula (1) accounts for 1 to 10% of the total mass of the non-aqueous lithium battery electrolyte; and / or, the compound shown in the formula (2) accounts for 1 to 10% of the total mass of the non-aqueous lithium battery electrolyte.

6. The non-aqueous lithium battery electrolyte according to claim 1, wherein: The additive further includes one or more of lithium difluorophosphate, vinylene sulfate, succinonitrile.

7. The non-aqueous lithium battery electrolyte according to claim 6, wherein: The lithium difluorophosphate accounts for 1 to 2% of the total mass of the non-aqueous lithium battery electrolyte; and / or, the vinylene sulfate accounts for 0.5 to 1% of the total mass of the non-aqueous lithium battery electrolyte; and / or, the succinonitrile accounts for 0.5 to 1% of the total mass of the non-aqueous lithium battery electrolyte.

8. The non-aqueous lithium battery electrolyte according to claim 1, wherein: The lithium salt is selected from one or more of LiPF6, LiBF4, LiClO4, LiCH3SO3, LiSCN, LiNO3, LiO3SCF2CF3, LiAsF6, LiAlCl4; and / or, the molar concentration of the lithium salt in the non-aqueous lithium battery electrolyte is 0.7 to 1.5 mol / L.

9. The non-aqueous lithium battery electrolyte according to claim 1, characterized in that: The organic solvent includes one or more of carbonate, carboxylate, ether, sulfone solvent; The carbonate includes one or more of ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, propylene carbonate; The carboxylate includes one or more of methyl formate, ethyl formate, methyl acetate, ethyl acetate, propyl acetate, ethyl propionate, methyl butyrate, ethyl butyrate; The ether includes one or more of dimethoxymethane, 1,2-dimethoxyethane, tetrahydrofuran, 1,3-dioxolane; The sulfone includes one or more of dimethyl sulfoxide, sulfolane, dimethyl sulfone.

10. A lithium battery, characterized in that: The lithium battery adopts the non-aqueous lithium battery electrolyte as described in any one of claims 1 to 9.

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