CN116264321A - Nonaqueous lithium battery electrolyte and lithium battery - Google Patents
Nonaqueous lithium battery electrolyte and lithium battery Download PDFInfo
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Abstract
The invention relates to a nonaqueous lithium battery electrolyte and a lithium battery, which mainly solve the problems of poor cycle performance and large internal resistance of the lithium battery at high temperature. According to the invention, through the addition of the compound shown in the formula (1) and/or the compound shown in the formula (2), the nonaqueous lithium battery electrolyte can form a compact film on the lithium battery pole piece, so that the battery has better cycle performance and smaller internal resistance at high temperature.
Description
Technical Field
The invention relates to a nonaqueous lithium battery electrolyte and a lithium battery.
Background
The lithium ion battery technology is more and more important in daily life of people, and along with the development of new energy, the clean energy is more and more widely used, is as small as an electronic device, is as large as an automobile and an airplane, and almost all places where power is used need to use the lithium ion battery. Thus, in recent years, the development of battery technology has also increased rapidly, and the wide market offers more development opportunities and also presents greater challenges. The wide use of lithium ion batteries leads to higher requirements of battery technology on the adaptability of the battery to the use environment, the market needs that the batteries can keep better performance under different severe environments, and a larger temperature range becomes an important subject for the development of the batteries. Meanwhile, the wide use of the battery has put higher demands on the safety performance of the battery, and the problem of poor safety performance of the battery under high energy density is solved.
The electrolyte is used as the blood of the battery, has a great influence on the high-low temperature performance of the battery, and according to the literature, a film forming additive is generally added into the electrolyte of the battery to improve the cycle performance of the battery, for example, vinylene carbonate is used, so that a better film can be formed on the surface of an electrode of the battery during the formation of the battery, and the reaction is prevented from further proceeding. However, the film formed by adding vinylene carbonate is easily decomposed at high temperature and is continuously destroyed, so that the battery cannot function at high temperature. For example, although a good film can be formed at a high temperature by adding an additive such as lithium bisoxalato borate to the electrolyte, the film thickness is large and the film conductivity is low, which results in an excessive internal resistance of the battery and thus affects the performance of the battery. Likewise, the addition of flame retardant additives to the electrolyte can also have a role in the safety performance of the battery, but at the same time most of the flame retardant additives have a more or less impact on other performance of the battery.
Based on this, how to reduce the internal resistance of a battery at high temperature while improving the high-temperature cycle performance of the battery is an urgent technical problem to be solved.
Disclosure of Invention
The invention aims to solve the technical problem of overcoming the defects of the prior art and providing a nonaqueous lithium battery electrolyte and a lithium battery with good cycle performance and internal resistance performance at high temperature.
In order to achieve the above purpose, the invention adopts the following technical scheme:
a nonaqueous lithium battery electrolyte comprises lithium salt, an organic solvent and an additive, wherein the additive comprises a compound shown in a formula (1) and/or a compound shown in a formula (2), and the formula (1) is
The formula (2) is->
Wherein R in the formula (1) 1 、R 2 、R 3 、R 4 、R 5 、R 6 、R 7 Each independently selected from hydrogen, hydroxy, halogen, alkyl, alkoxy, haloalkoxy, haloalkyl, alkenyl, haloalkenyl, amino, ester, aryl, or nitrile, R in formula (2) 1 、R 2 、R 3 、R 4 、R 5 、R 6 、R 7 Respectively with R in the formula (1) 1 、R 2 、R 3 、R 4 、R 5 、R 6 、R 7 Similarly, R in the formula (2) 8 Selected from hydrogen, hydroxy, halogen, alkyl, alkoxy, haloalkoxy, haloalkyl, alkenyl, haloalkenyl, amino, ester, aryl, or nitrile.
Preferably, said R 1 、R 2 、R 3 、R 4 、R 5 、R 6 、R 7 、R 8 Each independently selected from hydrogen, hydroxy, alkyl, haloalkoxy.
Further preferably, the R 1 、R 2 、R 3 、R 4 、R 5 、R 6 、R 7 、R 8 Independently selected from hydrogen, hydroxy, alkyl having 1 to 3 carbon atoms, and haloalkoxy having 1 to 3 carbon atoms.
Still further preferably, the R 1 、R 2 、R 7 、R 8 Independently selected from alkyl group having 1 to 3 carbon atoms, haloalkoxy group having 1 to 3 carbon atoms, and hydroxy group, wherein R is 4 、R 5 Respectively are hydrogen, R is 3 、R 6 Independently selected from alkyl groups having 1 to 3 carbon atoms and hydrogen.
Preferably, the halogenated halogen is fluorine.
According to some preferred embodiments, the compound of formula (1) comprises
And/or +.>
According to some preferred embodiments, the compound of formula (2) comprises
One or more of the following.
Preferably, the compound shown in the formula (1) accounts for 1-10% of the total mass of the nonaqueous lithium battery electrolyte.
Further preferably, the compound represented by the formula (1) accounts for 3-10% of the total mass of the nonaqueous lithium battery electrolyte.
Still more preferably, the compound represented by the formula (1) accounts for 5 to 10% of the total mass of the nonaqueous lithium battery electrolyte.
Preferably, the compound shown in the formula (2) accounts for 1-10% of the total mass of the nonaqueous lithium battery electrolyte.
Further preferably, the compound represented by the formula (2) accounts for 3-10% of the total mass of the nonaqueous lithium battery electrolyte.
Still more preferably, the compound represented by the formula (2) accounts for 5 to 10% of the total mass of the nonaqueous lithium battery electrolyte.
Preferably, the additive further comprises one or more of lithium difluorophosphate, vinyl sulfate, succinonitrile.
Further preferably, the lithium difluorophosphate accounts for 1-2% of the total mass of the nonaqueous lithium battery electrolyte.
Further preferably, the vinyl sulfate accounts for 0.5-1% of the total mass of the nonaqueous lithium battery electrolyte.
Further preferably, the succinonitrile accounts for 0.5-1% of the total mass of the nonaqueous lithium battery electrolyte.
Preferably, the lithium salt is selected from LiPF 6 、LiBF 4 、LiClO 4 、LiCH 3 SO 3 、LiSCN、LiNO 3 、LiO 3 SCF 2 CF 3 、LiAsF 6 、LiAlCl 4 One or more of (a) and (b).
Further preferably, the concentration of the lithium salt in the nonaqueous lithium battery electrolyte is 0.7 to 1.5mol/L.
Still more preferably, the concentration of the lithium salt in the nonaqueous lithium battery electrolyte is 0.9 to 1.2mol/L.
Preferably, the organic solvent comprises one or more of carbonate, carboxylate, ether, sulfone solvents.
Further preferably, the carbonate comprises one or more of ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, ethylmethyl carbonate, propylene carbonate.
Further preferably, the carboxylic acid ester comprises a cyclic carboxylic acid ester and/or a chain carboxylic acid ester. When the cyclic carboxylic acid ester and the chain carboxylic acid ester are used together, the mass ratio of the cyclic carboxylic acid ester to the carboxylic acid ester is 1 (0.5 to 2.5).
Still more preferably, the carboxylic acid ester comprises one or more of methyl formate, ethyl formate, methyl acetate, ethyl acetate, propyl acetate, ethyl propionate, methyl butyrate, ethyl butyrate.
Preferably, the ether comprises one or more of dimethoxymethane, 1, 2-dimethoxyethane, tetrahydrofuran, 1, 3-dioxolane.
Preferably, the sulfone comprises one or more of dimethylsulfoxide, sulfolane, dimethylsulfone.
According to some preferred embodiments, the organic solvent is a mixed solvent of ethylene carbonate, methyl ethyl carbonate, dimethyl carbonate and propylene carbonate with the mass ratio of (2-6): (5-11): (1-2): 1.
Further preferably, the organic solvent is a mixed solvent of ethylene carbonate, methyl ethyl carbonate, dimethyl carbonate and propylene carbonate with the mass ratio of (2-3) (5-7) (1-1.5) (1).
Another aspect of the invention provides a lithium battery employing the nonaqueous lithium battery electrolyte described above.
Due to the application of the technical scheme, compared with the prior art, the invention has the following advantages:
the nonaqueous lithium battery electrolyte can form a compact film on a lithium battery pole piece, and the film can exist stably at high temperature and has higher ionic conductivity, so that the battery has better cycle performance and smaller internal resistance at high temperature.
Detailed Description
In order to improve the cycle performance of the battery at high temperature, some additives are often added into the electrolyte, and the addition of the additives can have more or less influence on other performances of the battery, for example, the internal resistance of the battery at high temperature is excessively high. How to make the battery have the characteristics of good high-temperature cycle performance and small internal resistance at the same time becomes the difficulty of the prior art. Based on the shortcomings of the prior art, the applicant has obtained the scheme of the application through long-term experiments and a great deal of research, and the scheme is further described below.
A nonaqueous lithium battery electrolyte comprises lithium salt, organic solvent and additive, wherein the additive comprises compound shown in formula (1) and/or compound shown in formula (2), and formula (1) is
The structural formula (2) is
In the present invention, R in formula (1) 1 、R 2 、R 3 、R 4 、R 5 、R 6 、R 7 Each independently selected from hydrogen, hydroxy, halogen, alkyl, alkoxy, haloalkoxy, haloalkyl, alkenyl, haloalkenyl, amino, ester, aryl, or nitrile. R in formula (2) 1 、R 2 、R 3 、R 4 、R 5 、R 6 、R 7 Respectively with R in the formula (1) 1 、R 2 、R 3 、R 4 、R 5 、R 6 、R 7 Same, R in formula (2) 8 Selected from hydrogen, hydroxy, halogen, alkyl, alkoxy, haloalkoxy, haloalkyl, alkenyl, haloalkenyl, amino, ester, aryl, or nitrile. In the present invention, halogen or halogenated halogen is fluorine, chlorine or bromine. Alkyl groups include straight chain alkyl groups as well as cyclic alkyl groups, for example: methyl, ethyl, propyl, isopropyl, butyl, cyclopropyl, cyclobutyl, and the like. Alkoxy groups include, but are not limited to, methoxy, ethoxy, propoxy, and the like, as commonly found alkoxy groups. Alkenyl groups include, but are not limited to, ethenyl, propenyl, butenyl, and the like, as are commonly found alkenyl groups. The ester groups include, but are not limited to, common ester groups such as methyl formate, ethyl formate, propyl formate, methyl acetate, ethyl acetate, and the like. The compound represented by the formula (1) is excessively low in addition amount to exert no effect, whereas the excessive addition amount affects the discharge performance of the battery at normal temperature, and preferably, the compound represented by the formula (1) accounts for 1 to 10% of the total mass of the nonaqueous lithium battery electrolyte, for example: 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%. Also, the addition amount of the compound represented by the formula (2) is too low to exert an effect, whereas the addition amount is too high to affect the discharge performance of the battery at normal temperature, and preferably, the compound represented by the formula (2) accounts for 1 to 10% of the total mass of the nonaqueous lithium battery electrolyte, for example: 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%.
According to some specific and preferred embodiments, the additives include one or more of the following A, B, C, D, E and F formulas.
According to the invention, A, C, F is added, so that the cycle performance of the battery at high temperature can be improved, the internal resistance of the battery at high temperature can be reduced, the flammability of the electrolyte can be reduced, and the safety performance of the battery can be improved.
In the invention, A can be synthesized from bis (trifluoroethyl) phosphoryl chloride, 1, 2-dichloroethane, imidazole and N, N-dimethyl ethylenediamine, and the specific steps comprise: (1) 56g of bistrifluoroethyl phosphoryl chloride, 200ml of 1, 2-dichloroethane and 15g of imidazole are introduced into a 500ml three-necked flask under the complete protection of inert gas, and the temperature of the system is controlled to be lower than 0 ℃. (2) 50ml of 1, 2-dichloroethane solution containing 18.5g of N, N-dimethylethylenediamine is slowly dripped, the dripping speed is controlled, the reaction temperature is kept within 5 ℃, and the reaction is carried out for 2 hours at 20-25 ℃ after the dripping is finished. (3) Slowly adding 200ml of 10% by mass of dilute hydrochloric acid to quench the reaction, standing for liquid separation, and sequentially adding 200ml of 10% by mass of sodium carbonate, 200ml of water and 200ml of saturated sodium chloride to wash the organic phase. (4) The organic phase is dried over anhydrous sodium sulfate overnight, sodium sulfate is removed by suction filtration, the solvent is removed from the organic phase, and the organic phase is dried to constant weight in a vacuum drying oven to obtain 61g of product A, the yield is 91.9%, and the purity is 99.1%.
In the invention, F can be synthesized from bis (trifluoroethyl) phosphoryl chloride, tetrahydrofuran and ethylenediamine, and comprises the following specific steps: (1) 45g of bistrifluoroethyl phosphoryl chloride, 200ml of tetrahydrofuran were introduced into a 500ml three-necked flask under the complete protection of inert gas. (2) The temperature of the system is controlled below 0 ℃, 50ml of tetrahydrofuran solution containing 12g of ethylenediamine is slowly dripped, the dripping speed is controlled, the reaction temperature is kept within 5 ℃, and the reaction is carried out for 8 hours at 25 ℃ after the dripping is finished. (3) The organic phase is removed by rotary evaporation, the residue is washed with deionized water for 3 times, 100ml of the water is used each time, and then the residue is obtained by suction filtration. (4) The filter residue is placed in a vacuum drying oven to be dried to constant weight, and 39.5g of a product F is obtained, the yield is 89.7%, the purity is 99.3%, and the water content is 80ppm.
In the invention, the additive also comprises one or more of lithium difluorophosphate, vinyl sulfate and succinonitrile. When the additive is used in combination with lithium difluorophosphate, vinyl sulfate and succinonitrile, the cycle and internal resistance of the battery can be further improved. Wherein, the lithium difluorophosphate accounts for 1-2% of the total mass of the nonaqueous lithium battery electrolyte, for example: 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2%. Vinyl sulfate accounts for 0.5-1% of the total mass of the nonaqueous 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 to 1 percent of the total mass of the nonaqueous lithium battery electrolyte, for example: 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%.
In the present invention, the lithium salt is selected from LiPF 6 、LiBF 4 、LiClO 4 、LiCH 3 SO 3 、LiSCN、LiNO 3 、LiO 3 SCF 2 CF 3 、LiAsF 6 、LiAlCl 4 One or more of (a) and (b). The concentration of the lithium salt in the nonaqueous lithium battery electrolyte is 0.7 to 1.5mol/L, for example: 0.7mol/L, 0.8mol/L, 0.9mol/L, 1mol/L, 1.1mol/L, 1.2mol/L, 1.3mol/L, 1.4mol/L, 1.5mol/L.
In the present invention, the organic solvent includes one or more of carbonate, carboxylate, ether, sulfone solvents. Wherein the carbonic ester comprises one or more of ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate and propylene carbonate. The carboxylic acid ester comprises one or more of methyl formate, ethyl formate, methyl acetate, ethyl acetate, propyl acetate, ethyl propionate, methyl butyrate and ethyl butyrate. The ether comprises one or more of dimethoxymethane, 1, 2-dimethoxyethane, tetrahydrofuran, and 1, 3-dioxolane. The sulfone comprises one or more of dimethyl sulfoxide, sulfolane, and dimethyl sulfone.
The invention is further described below with reference to examples. The present invention is not limited to the following examples. The implementation conditions adopted in the embodiments can be further adjusted according to different requirements of specific use, and the implementation conditions which are not noted are conventional conditions in the industry. The technical features of the various embodiments of the present invention may be combined with each other as long as they do not collide with each other.
Comparative example 1
Lithium salt LiPF 6 In a mixed solvent of ethylene carbonate/methyl ethyl carbonate/dimethyl carbonate/propylene carbonate (mass ratio 25/50/15/10), wherein LiPF 6 The concentration is 1mol/L, and the contrast electrolyte is obtained.
Example 1
Lithium salt LiPF 6 Dissolved in ethylene carbonate/methyl ethyl carbonate/dimethyl carbonate/carbonIn a mixed solvent of acrylic acid propylene ester (mass ratio 25/50/15/10), wherein LiPF 6 The concentration was 1mol/L, and 6% of A was added to the solution based on the total mass of the electrolyte to obtain an electrolyte of this example.
Example 2
Lithium salt LiPF 6 In a mixed solvent of ethylene carbonate/methyl ethyl carbonate/dimethyl carbonate/propylene carbonate (mass ratio 25/50/15/10), wherein LiPF 6 The concentration was 1mol/L, and 6% of B was added to the solution based on the total mass of the electrolyte to obtain an electrolyte of this example.
Example 3
Lithium salt LiPF 6 In a mixed solvent of ethylene carbonate/methyl ethyl carbonate/dimethyl carbonate/propylene carbonate (mass ratio 25/50/15/10), wherein LiPF 6 The concentration was 1mol/L, and 6% of C was added to the solution based on the total mass of the electrolyte to obtain an electrolyte of this example.
Example 4
Lithium salt LiPF 6 In a mixed solvent of ethylene carbonate/methyl ethyl carbonate/dimethyl carbonate/propylene carbonate (mass ratio 25/50/15/10), wherein LiPF 6 The concentration was 1mol/L, and 6% of D was added to the solution based on the total mass of the electrolyte to obtain an electrolyte of this example.
Example 5
Lithium salt LiPF 6 In a mixed solvent of ethylene carbonate/methyl ethyl carbonate/dimethyl carbonate/propylene carbonate (mass ratio 25/50/15/10), wherein LiPF 6 The concentration was 1mol/L, and 6% of E was added to the solution based on the total mass of the electrolyte to obtain an electrolyte of this example.
Example 6
Lithium salt LiPF 6 In a mixed solvent of ethylene carbonate/methyl ethyl carbonate/dimethyl carbonate/propylene carbonate (mass ratio 25/50/15/10), wherein LiPF 6 The concentration was 1mol/L, and 6% of F was added to the solution based on the total mass of the electrolyte to obtain an electrolyte of this example.
Example 7
Lithium salt LiPF 6 Dissolved in ethylene carbonate/methyl ethyl carbonateIn a mixed solvent of dimethyl carbonate/propylene carbonate (mass ratio 25/50/15/10), wherein LiPF 6 The concentration was 1mol/L, and 1% of A was added to the solution based on the total mass of the electrolyte to obtain an electrolyte of this example.
Example 8
Lithium salt LiPF 6 In a mixed solvent of ethylene carbonate/methyl ethyl carbonate/dimethyl carbonate/propylene carbonate (mass ratio 25/50/15/10), wherein LiPF 6 The concentration was 1mol/L, and 3% of A was added to the solution based on the total mass of the electrolyte to obtain an electrolyte of this example.
Example 9
Lithium salt LiPF 6 In a mixed solvent of ethylene carbonate/methyl ethyl carbonate/dimethyl carbonate/propylene carbonate (mass ratio 25/50/15/10), wherein LiPF 6 The concentration was 1mol/L, and 1% of F was added to the solution based on the total mass of the electrolyte to obtain an electrolyte of this example.
Example 10
Lithium salt LiPF 6 In a mixed solvent of ethylene carbonate/methyl ethyl carbonate/dimethyl carbonate/propylene carbonate (mass ratio 25/50/15/10), wherein LiPF 6 The concentration was 1mol/L, and 3% of F was added to the solution based on the total mass of the electrolyte to obtain an electrolyte of this example.
Example 11
Lithium salt LiPF 6 In a mixed solvent of ethylene carbonate/methyl ethyl carbonate/dimethyl carbonate/propylene carbonate (mass ratio 25/50/15/10), wherein LiPF 6 The concentration was 1mol/L, and 9% of A was added to the solution based on the total mass of the electrolyte to obtain an electrolyte of this example.
Example 12
Lithium salt LiPF 6 In a mixed solvent of ethylene carbonate/methyl ethyl carbonate/dimethyl carbonate/propylene carbonate (mass ratio 25/50/15/10), wherein LiPF 6 The concentration was 1mol/L, and 9% of F was added to the solution based on the total mass of the electrolyte to obtain an electrolyte of this example.
Example 13
Lithium salt LiPF 6 Dissolved in carbonic acidIn a mixed solvent of vinyl ester/methyl ethyl carbonate/dimethyl carbonate/propylene carbonate (mass ratio 25/50/15/10), wherein LiPF 6 The concentration was 1mol/L, and 6% of A, 1% of lithium difluorophosphate, 0.5% of vinyl sulfate, and 0.5% of succinonitrile were added to the solution based on the total mass of the electrolyte to obtain an electrolyte of this example.
Example 14
Lithium salt LiPF 6 In a mixed solvent of ethylene carbonate/methyl ethyl carbonate/dimethyl carbonate/propylene carbonate (mass ratio 25/50/15/10), wherein LiPF 6 The concentration was 1mol/L, and 6% of B, 1% of lithium difluorophosphate, 0.5% of vinyl sulfate, and 0.5% of succinonitrile were added to the solution based on the total mass of the electrolyte to obtain an electrolyte of this example.
Example 15
Lithium salt LiPF 6 In a mixed solvent of ethylene carbonate/methyl ethyl carbonate/dimethyl carbonate/propylene carbonate (mass ratio 25/50/15/10), wherein LiPF 6 The concentration was 1mol/L, and 6% of C, 1% of lithium difluorophosphate, 0.5% of vinyl sulfate, and 0.5% of succinonitrile were added to the solution based on the total mass of the electrolyte to obtain an electrolyte of this example.
Example 16
Lithium salt LiPF 6 In a mixed solvent of ethylene carbonate/methyl ethyl carbonate/dimethyl carbonate/propylene carbonate (mass ratio 25/50/15/10), wherein LiPF 6 The concentration was 1mol/L, and 6% of D, 1% of lithium difluorophosphate, 0.5% of vinyl sulfate, and 0.5% of succinonitrile were added to the solution based on the total mass of the electrolyte to obtain an electrolyte of this example.
Example 17
Lithium salt LiPF 6 In a mixed solvent of ethylene carbonate/methyl ethyl carbonate/dimethyl carbonate/propylene carbonate (mass ratio 25/50/15/10), wherein LiPF 6 The concentration was 1mol/L, and 6% of E, 1% of lithium difluorophosphate, 0.5% of vinyl sulfate, and 0.5% of succinonitrile were added to the solution based on the total mass of the electrolyte to obtain an electrolyte of this example.
Example 18
Lithium salt LiPF 6 Dissolved in carbonic acidIn a mixed solvent of vinyl ester/methyl ethyl carbonate/dimethyl carbonate/propylene carbonate (mass ratio 25/50/15/10), wherein LiPF 6 The concentration was 1mol/L, and 6% of F, 1% of lithium difluorophosphate, 0.5% of vinyl sulfate, and 0.5% of succinonitrile were added to the solution based on the total mass of the electrolyte to obtain an electrolyte of this example.
Example 19
Lithium salt LiPF 6 In a mixed solvent of ethylene carbonate/methyl ethyl carbonate/dimethyl carbonate/propylene carbonate (mass ratio 25/50/15/10), wherein LiPF 6 The concentration was 1mol/L, and 1% of A, 1% of lithium difluorophosphate, 0.5% of vinyl sulfate, and 0.5% of succinonitrile were added to the solution based on the total mass of the electrolyte to obtain an electrolyte of this example.
Example 20
Lithium salt LiPF 6 In a mixed solvent of ethylene carbonate/methyl ethyl carbonate/dimethyl carbonate/propylene carbonate (mass ratio 25/50/15/10), wherein LiPF 6 The concentration was 1mol/L, and 3% of A, 1% of lithium difluorophosphate, 0.5% of vinyl sulfate, and 0.5% of succinonitrile were added to the solution based on the total mass of the electrolyte to obtain an electrolyte of this example.
Example 21
Lithium salt LiPF 6 In a mixed solvent of ethylene carbonate/methyl ethyl carbonate/dimethyl carbonate/propylene carbonate (mass ratio 25/50/15/10), wherein LiPF 6 The concentration was 1mol/L, and 1% of F, 1% of lithium difluorophosphate, 0.5% of vinyl sulfate, and 0.5% of succinonitrile were added to the solution based on the total mass of the electrolyte to obtain an electrolyte of this example.
Example 22
Lithium salt LiPF 6 In a mixed solvent of ethylene carbonate/methyl ethyl carbonate/dimethyl carbonate/propylene carbonate (mass ratio 25/50/15/10), wherein LiPF 6 The concentration was 1mol/L, and 3% of F, 1% of lithium difluorophosphate, 0.5% of vinyl sulfate, and 0.5% of succinonitrile were added to the solution based on the total mass of the electrolyte to obtain an electrolyte of this example.
Example 23
Lithium salt LiPF 6 Dissolved in carbonic acidIn a mixed solvent of vinyl ester/methyl ethyl carbonate/dimethyl carbonate/propylene carbonate (mass ratio 25/50/15/10), wherein LiPF 6 The concentration was 1mol/L, and 6% of A, 1% of lithium difluorophosphate and 0.5% of succinonitrile were added to the solution based on the total mass of the electrolyte to obtain an electrolyte of this example.
Example 24
Lithium salt LiPF 6 In a mixed solvent of ethylene carbonate/methyl ethyl carbonate/dimethyl carbonate/propylene carbonate (mass ratio 25/50/15/10), wherein LiPF 6 The concentration was 1mol/L, and 6% of A, 0.5% of vinyl sulfate, and 0.5% of succinonitrile were added to the solution based on the total mass of the electrolyte to obtain an electrolyte of this example.
Example 25
Lithium salt LiPF 6 In a mixed solvent of ethylene carbonate/methyl ethyl carbonate/dimethyl carbonate/propylene carbonate (mass ratio 25/50/15/10), wherein LiPF 6 The concentration was 1mol/L, and 6% of A, 1% of lithium difluorophosphate and 0.5% of vinyl sulfate were added to the solution based on the total mass of the electrolyte to obtain an electrolyte of this example.
Example 26
Lithium salt LiPF 6 In a mixed solvent of ethylene carbonate/methyl ethyl carbonate/dimethyl carbonate/propylene carbonate (mass ratio 25/50/15/10), wherein LiPF 6 The concentration was 1mol/L, and 6% of F, 1% of lithium difluorophosphate and 0.5% of succinonitrile were added to the solution based on the total mass of the electrolyte to obtain an electrolyte of this example.
Example 27
Lithium salt LiPF 6 In a mixed solvent of ethylene carbonate/methyl ethyl carbonate/dimethyl carbonate/propylene carbonate (mass ratio 25/50/15/10), wherein LiPF 6 The concentration was 1mol/L, and 6% of F, 1% of lithium difluorophosphate and 0.5% of vinyl sulfate were added to the solution based on the total mass of the electrolyte to obtain an electrolyte of this example.
Example 28
Lithium salt LiPF 6 In a mixed solvent of ethylene carbonate/methyl ethyl carbonate/dimethyl carbonate/propylene carbonate (mass ratio 25/50/15/10), whereinLiPF 6 The concentration was 1mol/L, and 6% of A and 1% of lithium difluorophosphate were added to the solution based on the total mass of the electrolyte to obtain an electrolyte of this example.
Example 29
Lithium salt LiPF 6 In a mixed solvent of ethylene carbonate/methyl ethyl carbonate/dimethyl carbonate/propylene carbonate (mass ratio 25/50/15/10), wherein LiPF 6 The concentration was 1mol/L, and 6% of A and 2% of lithium difluorophosphate were added to the solution based on the total mass of the electrolyte to obtain an electrolyte of this example.
Example 30
Lithium salt LiPF 6 In a mixed solvent of ethylene carbonate/methyl ethyl carbonate/dimethyl carbonate/propylene carbonate (mass ratio 25/50/15/10), wherein LiPF 6 The concentration was 1mol/L, and 9% of A, 1% of lithium difluorophosphate, 0.5% of vinyl sulfate, and 0.5% of succinonitrile were added to the solution based on the total mass of the electrolyte to obtain an electrolyte of this example.
Example 31
Lithium salt LiPF 6 In a mixed solvent of ethylene carbonate/methyl ethyl carbonate/dimethyl carbonate/propylene carbonate (mass ratio 25/50/15/10), wherein LiPF 6 The concentration was 1mol/L, and 9% of F, 1% of lithium difluorophosphate, 0.5% of vinyl sulfate, and 0.5% of succinonitrile were added to the solution based on the total mass of the electrolyte to obtain an electrolyte of this example.
Experimental results
The electrolytes obtained in comparative example 1 and examples 1 to 31 were injected into the same batch of lithium cobaltate soft pack batteries of the same type, and the test batteries were subjected to a cycle performance test of 1C in a high temperature 45 ℃ environment of 2.75-4.2V, a post-shelf test of internal resistance at a high temperature of 60 ℃ and an electrolyte ignition time test at normal temperature. The comparative data of all comparative examples and examples in terms of high-temperature cycle capacity retention, high Wen Gezhi internal resistance and electrolyte ignition time are shown in table 1.
TABLE 1
The electrolyte solutions obtained in comparative example 1 and examples 1, 6 to 13, 18 to 22, 30, 31 were injected into the same batch and model lithium cobaltate soft pack battery, and the test battery was subjected to 1C cycle performance test in a normal temperature 25 ℃ environment at 2.75-4.2V. Specific results of all comparative examples and examples room temperature cycle capacity retention rate comparison data are shown in table 2 below.
TABLE 2
The present invention has been described in detail with the purpose of enabling those skilled in the art to understand the contents of the present invention and to implement the same, but not to limit the scope of the present invention, and all equivalent changes or modifications made according to the spirit of the present invention should be included in the scope of the present invention.
Claims (10)
1. The nonaqueous lithium battery electrolyte comprises lithium salt, an organic solvent and an additive, and is characterized in that: the additive comprises a compound shown in a formula (1) and/or a compound shown in a formula (2),
the formula (1) is
The formula (2) is
Wherein R in the formula (1) 1 、R 2 、R 3 、R 4 、R 5 、R 6 、R 7 Each independently selected from hydrogen, hydroxy, halogen, alkyl, alkoxy, haloalkoxy, haloalkyl, alkenyl, haloalkenyl, amino, ester, aryl, or nitrile, R in formula (2) 1 、R 2 、R 3 、R 4 、R 5 、R 6 、R 7 Respectively with R in the formula (1) 1 、R 2 、R 3 、R 4 、R 5 、R 6 、R 7 Similarly, R in the formula (2) 8 Selected from hydrogen, hydroxy, halogen, alkyl, alkoxy, haloalkoxy, haloalkyl, alkenyl, haloalkenyl, amino, ester, aryl, or nitrile.
2. The nonaqueous lithium battery electrolyte according to claim 1, wherein: the R is 1 、R 2 、R 3 、R 4 、R 5 、R 6 、R 7 、R 8 Each independently selected from hydrogen, hydroxy, alkyl, haloalkoxy.
3. The nonaqueous lithium battery electrolyte according to claim 2, wherein: the R is 1 、R 2 、R 7 、R 8 Independently selected from alkyl group having 1 to 3 carbon atoms, haloalkoxy group having 1 to 3 carbon atoms, and hydroxy group, wherein R is 4 、R 5 Respectively are hydrogen, R is 3 、R 6 Independently selected from alkyl groups having 1 to 3 carbon atoms and hydrogen;
and/or, the halogenated halogen is fluorine.
4. The nonaqueous lithium battery electrolyte according to claim 1 or 3, characterized in that: the compound represented by the formula (1) comprises
The compound represented by the formula (2) comprises
5. The nonaqueous lithium battery electrolyte according to claim 1, wherein: the compound shown in the formula (1) accounts for 1-10% of the total mass of the nonaqueous lithium battery electrolyte;
and/or the compound shown in the formula (2) accounts for 1-10% of the total mass of the nonaqueous lithium battery electrolyte.
6. The nonaqueous lithium battery electrolyte according to claim 1, wherein: the additive also comprises one or more of lithium difluorophosphate, vinyl sulfate and succinonitrile.
7. The nonaqueous lithium battery electrolyte according to claim 6, wherein: the lithium difluorophosphate accounts for 1-2% of the total mass of the nonaqueous lithium battery electrolyte;
and/or, the vinyl sulfate accounts for 0.5-1% of the total mass of the nonaqueous lithium battery electrolyte;
and/or the succinonitrile accounts for 0.5-1% of the total mass of the nonaqueous lithium battery electrolyte.
8. The nonaqueous lithium battery electrolyte according to claim 1, wherein: the lithium salt is selected from LiPF 6 、LiBF 4 、LiClO 4 、LiCH 3 SO 3 、LiSCN、LiNO 3 、LiO 3 SCF 2 CF 3 、LiAsF 6 、LiAlCl 4 One or more of (a) and (b);
and/or the molar concentration of the lithium salt in the nonaqueous lithium battery electrolyte is 0.7-1.5 mol/L.
9. The nonaqueous lithium battery electrolyte according to claim 1, wherein: the organic solvent comprises one or more of carbonate, carboxylate, ether and sulfone solvents;
the carbonic ester comprises one or more of ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate and propylene carbonate;
the carboxylic acid ester comprises one or more of methyl formate, ethyl formate, methyl acetate, ethyl acetate, propyl acetate, ethyl propionate, methyl butyrate and ethyl butyrate;
the ether comprises one or more of dimethoxymethane, 1, 2-dimethoxyethane, tetrahydrofuran, and 1, 3-dioxolane;
the sulfone comprises one or more of dimethyl sulfoxide, sulfolane, and dimethyl sulfone.
10. A lithium battery, characterized in that: the lithium battery employs the nonaqueous lithium battery electrolyte as defined in any one of claims 1 to 9.
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