CN112687950B

CN112687950B - Application of diphenylamine in lithium ion battery electrolyte, lithium ion battery electrolyte and lithium ion battery

Info

Publication number: CN112687950B
Application number: CN201910996767.7A
Authority: CN
Inventors: 董江舟; 李延良; 夏清华; 张�杰
Original assignee: Sinopec Beijing Research Institute of Chemical Industry; China Petroleum and Chemical Corp
Current assignee: Sinopec Beijing Research Institute of Chemical Industry; China Petroleum and Chemical Corp
Priority date: 2019-10-19
Filing date: 2019-10-19
Publication date: 2022-01-04
Anticipated expiration: 2039-10-19
Also published as: CN112687950A

Abstract

The invention relates to the field of batteries, and discloses application of diphenylamine in lithium ion battery electrolyte, the lithium ion battery electrolyte and a lithium ion battery. When the diphenylamine shown in the formula (I) is used in the electrolyte of a lithium ion battery, the high-temperature storage performance and the flame retardant function of the electrolyte can be improved, and the negative influence on the performance of the battery is small.

Description

Application of diphenylamine in lithium ion battery electrolyte, lithium ion battery electrolyte and lithium ion battery

Technical Field

The invention relates to the field of batteries, in particular to application of diphenylamine in lithium ion battery electrolyte, lithium ion battery electrolyte containing diphenylamine and a lithium ion battery containing the lithium ion battery electrolyte.

Background

The energy crisis and the increasingly serious environmental pollution make the automobile technology undergo the major technological changes of fuel diversification, power electric gasification and the like.

The lithium ion battery is unique due to the characteristics of high energy density, long service life, high working voltage, environmental protection and the like, and becomes a key development direction of energy sources for new energy automobiles at present.

Meanwhile, safety issues also become a significant challenge for lithium ion batteries. Overcharge of the battery may cause rapid deterioration of performance of the lithium ion battery, and in severe cases, may increase the possibility of fire and explosion of the lithium ion battery.

In view of this, it is necessary to study the safety performance of the lithium ion battery.

Disclosure of Invention

The invention aims to overcome the defects of poor high-temperature storage performance and poor flame retardant performance of the lithium ion battery electrolyte in the prior art.

In order to achieve the above object, a first aspect of the present invention provides the use of diphenylamine represented by the formula (I):

wherein, in the formula (I), X₁And X₂Each independently selected from halogen.

The second aspect of the invention provides an electrolyte of a lithium ion battery, which contains lithium salt, an organic solvent and at least one diphenylamine shown in a formula (I),

In a third aspect, the present invention provides a lithium ion battery comprising the electrolyte solution according to the second aspect of the present invention.

When the diphenylamine shown in the formula (I) is used in the electrolyte of a lithium ion battery, the high-temperature storage performance and the flame retardant function of the electrolyte can be improved, and the negative influence on the performance of the battery is small.

Detailed Description

The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.

As previously mentioned, a first aspect of the present invention provides the use of a diphenylamine of formula (I):

The halogen of the present invention includes fluorine, chlorine, bromine, iodine.

Preferably, in formula (I), X₁And X₂Each independently selected from F, Cl, Br.

Particularly preferably, in the formula (I), X₁And X₂Is F.

As described above, the second aspect of the present invention provides an electrolyte for a lithium ion battery, which contains a lithium salt, an organic solvent and at least one diphenylamine of formula (I),

In the second aspect of the present invention, in the formula (I), X is preferred₁And X₂Each independently selected from F, Cl, Br; more preferably in formula (I), X₁And X₂Is F.

According to a particularly preferred embodiment, the total content of diphenylamine represented by the formula (I) in the electrolyte is 0.1 to 20% by weight, more preferably 0.1 to 5% by weight.

Preferably, in the electrolyte, the concentration of the lithium salt is 0.1 to 2mol/L in terms of lithium ion content.

Preferably, the lithium salt is selected from LiPF₆、LiBF₄、LiAsF₆、LiClO₄、LiN(SO₂CF₃)₂、LiN(SO₂C₂F₅)₂、LiN(SO₂F)₂、LiSO₃CF₃At least one of (1).

Preferably, the organic solvent is at least one selected from the group consisting of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate.

According to another preferred embodiment, the electrolyte solution further contains at least one additive selected from the group consisting of vinylene carbonate, 1, 3-propane sultone, ethylene vinylene carbonate, 1, 3-propene sultone, methylene methanedisulfonate, 1, 4-butane sultone, biphenyl, fluorobenzene, cyclohexylbenzene, tert-butylbenzene, hexamethyldisilazane and heptamethyldisilamine.

Preferably, the total content of the additives in the electrolyte is 0.5-10 wt%.

As described above, the third aspect of the present invention provides a lithium ion battery containing the electrolyte solution described in the second aspect of the present invention.

The components of the lithium ion battery of the third aspect are not particularly limited by the present invention and may be selected conventionally in the art, and the present invention is improved primarily by providing a new electrolyte, and other suitable components of the lithium ion battery of the present invention will be readily apparent to those skilled in the art from the description herein, in conjunction with the prior art in the field. The person skilled in the art should not be construed as limiting the invention.

Further, the present invention has no particular requirements on the preparation method of the battery electrolyte, the preparation method of the battery, etc., and those skilled in the art can determine an appropriate corresponding preparation method according to the specific methods provided in the following examples of the present invention based on the knowledge in the art, and the person skilled in the art should not be construed as limiting the present invention.

The present invention will be described in detail below by way of examples. In the following examples, various materials used are commercially available without specific mention. Unless otherwise specified, each raw material was analytically pure.

Example 1

Preparation of the electrolyte

Under the drying condition, ethylene carbonate, propylene carbonate and diethyl carbonate are mixed according to the weight ratio of EC: PC: mixing DEC 1:1:1 to obtain a mixed solvent, and adding lithium salt LiPF₆Dissolving in the mixed solvent, adding diphenylamine and additive components, and stirring uniformly. Wherein, LiPF₆The concentration of the additive is 1mol/L, the additive component is vinylene carbonate, and X in diphenylamine₁And X₂Both are F, the vinylene carbonate and the diphenylamine contents being 0.5% and 0.5% by weight, respectively.

Battery fabrication

Preparing a positive electrode: mixing 96 percent of LiNi_1/3Co_1/3Mn_1/3O₂And 2% of PVDF and 2% of conductive graphite are fully stirred and uniformly mixed in N-methyl pyrrolidone, and then the mixture is coated on an aluminum foil for drying, compression and cutting to prepare the battery anode.

Preparing a negative electrode: according to the weight percentage, 95% of graphite negative electrode material, 3% of PVDF and 2% of conductive graphite are fully stirred and mixed evenly in N-methyl pyrrolidone, and then coated on copper foil for drying, compressing and cutting to obtain the battery negative electrode.

Preparing a lithium ion battery: and sequentially stacking the positive pole piece, the isolating membrane and the negative pole piece, and winding to obtain the electrode assembly. And (3) placing the electrode assembly in an outer package, injecting the prepared electrolyte and packaging to obtain the lithium ion battery A1.

Comparative example 1

The same procedure as in example 1 was conducted, except that, in the preparation of the electrolyte, the diphenylamine structure was not added in this comparative example, and the additive component was vinylene carbonate having a vinylene carbonate content of 0.5 wt%.

The remaining operations were the same as in example 1, to obtain a lithium ion battery D1.

Comparative example 2

The same procedure as in example 1 was conducted, except that, in the preparation of the electrolyte, the diphenylamine structure was not added in this comparative example, and the additive component was vinylene carbonate having a vinylene carbonate content of 1% by weight.

The remaining operations were the same as in example 1, to obtain a lithium ion battery D2.

Example 2

The procedure was carried out in the same manner as in example 1, except that, in the preparation of an electrolyte, the additive component in this example was 1, 3-propanesultone, X in diphenylamine₁And X₂The contents of both F, 1, 3-propane sultone and diphenylamine were 10 wt.% and 20 wt.%, respectively.

The remaining operations were the same as in example 1, to obtain lithium ion battery a 2.

Example 3

The procedure was carried out in the same manner as in example 1, except that, in the preparation of an electrolyte, the additive component in this example was 1, 4-butanesultone, X in diphenylamine₁And X₂The contents of both F, 1, 4-butanesultone and diphenylamine were 2% by weight and 0.1% by weight, respectively.

The remaining operations were the same as in example 1, to obtain lithium ion battery a 3.

Example 4

The procedure was carried out in the same manner as in example 1, except that, in the preparation of an electrolyte, the additive component in this example was vinylene carbonate, X in diphenylamine₁And X₂Both are F, the vinylene carbonate and diphenylamine contents being 0.5% and 0.05% by weight, respectively.

The remaining operations were the same as in example 1, to obtain lithium ion battery a 4.

Example 5

The procedure was carried out in the same manner as in example 1, except that, in the preparation of an electrolyte, the additive component in this example was vinylene carbonate, X in diphenylamine₁And X₂Both of which are F, the vinylene carbonate and the diphenylamine contents being 0.5 wt% and 25 wt%, respectively.

The remaining operations were the same as in example 1, to obtain lithium ion battery a 5.

Example 6

The procedure was carried out in the same manner as in example 1, except that, in the preparation of an electrolyte, X in diphenylamine in the present example₁And X₂Are all Cl.

The remaining operations were the same as in example 1, to obtain lithium ion battery a 6.

Test example

And (3) testing the flame retardant property of the electrolyte:

the method comprises the steps of preparing glass fiber cotton into glass cotton balls with the diameter of 3-5 mm, after the glass cotton balls are fully soaked in electrolyte to be tested, rapidly igniting the glass cotton balls by using an ignition device, recording the time from the movement of the ignition device to the automatic extinguishment of flame, wherein the time is called self-extinguishment time, comparing the flame retardant performances of different electrolytes according to the self-extinguishment time of unit mass of the electrolyte, carrying out parallel test for 3 times, averaging, and recording results in a table 1.

Testing the high-temperature storage performance of the battery:

the cell was fully charged in a 0.5C-rate constant current/constant voltage manner, and then placed in an oven at 60 ℃ for 35 days, tested and calculated to obtain the thickness expansion rate and the capacity retention rate, and the results are listed in table 1.

Thickness expansion rate (thickness after storage/thickness before storage-1) × 100%.

Capacity retention rate is discharge capacity after storage/discharge capacity before storage × 100%.

TABLE 1

From the above results, it can be seen that the electrolyte of the present invention containing diphenylamine has good flame retardant properties, and further, the flame retardant effect of the electrolyte will be improved with the increase of the amount of diphenylamine added. Meanwhile, in the aspect of improving the high-temperature storage performance, the functional additive of diphenylamine can achieve the improvement effect only by very low addition amount, and the improvement effect cannot be further improved by excessive addition.

Particularly, the battery adopting the electrolyte has the obviously better effect of taking high-temperature storage performance and flame retardant performance into consideration.

The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.

Claims

1. The application of diphenylamine shown in the formula (I) in lithium ion battery electrolyte is as follows:

2. Use according to claim 1, wherein, in formula (I), X₁And X₂Each independently selected from F, Cl, Br.

3. Use according to claim 2, wherein, in formula (I), X₁And X₂Is F.

4. The electrolyte of the lithium ion battery is characterized by comprising lithium salt, an organic solvent and at least one diphenylamine shown in a formula (I),

5. The electrolyte as claimed in claim 4, wherein, in the formula (I), X₁And X₂Each independently of the otherIs selected from F, Cl and Br.

6. The electrolyte as claimed in claim 5, wherein, in the formula (I), X₁And X₂Is F.

7. The electrolyte according to claim 4, wherein the total content of diphenylamine of the formula (I) is 0.1 to 20% by weight.

8. The electrolyte according to claim 7, wherein the total content of diphenylamine of the formula (I) is 0.1 to 5% by weight.

9. The electrolyte of any one of claims 4 to 8, wherein the concentration of the lithium salt in the electrolyte is 0.1 to 2mol/L in terms of lithium ion content.

10. The electrolyte of any of claims 4-8, wherein the lithium salt is selected from LiPF₆、LiBF₄、LiAsF₆、LiClO₄、LiN(SO₂CF₃)₂、LiN(SO₂C₂F₅)₂、LiN(SO₂F)₂、LiSO₃CF₃At least one of (1).

11. The electrolyte of any one of claims 4-8, wherein the organic solvent is selected from at least one of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate.

12. The electrolytic solution according to any one of claims 4 to 8, further comprising at least one additive selected from the group consisting of vinylene carbonate, 1, 3-propane sultone, vinylene carbonate, 1, 3-propene sultone, methylene methanedisulfonate, 1, 4-butane sultone, biphenyl, fluorobenzene, cyclohexylbenzene, t-butylbenzene, hexamethyldisilazane and heptamethyldisilamine.

13. The electrolyte of claim 12, wherein the total content of the additives in the electrolyte is 0.5 to 10 wt%.

14. A lithium ion battery comprising the electrolyte of any one of claims 4 to 13.