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CN113871712A - Lithium ion battery electrolyte, preparation method thereof and lithium ion battery - Google Patents

Lithium ion battery electrolyte, preparation method thereof and lithium ion battery Download PDF

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CN113871712A
CN113871712A CN202111122265.5A CN202111122265A CN113871712A CN 113871712 A CN113871712 A CN 113871712A CN 202111122265 A CN202111122265 A CN 202111122265A CN 113871712 A CN113871712 A CN 113871712A
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ion battery
lithium ion
additive
lithium
battery electrolyte
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CN113871712B (en
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王子沅
王仁和
余乐
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Envision Power Technology Jiangsu Co Ltd
Envision Ruitai Power Technology Shanghai Co Ltd
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Envision Power Technology Jiangsu Co Ltd
Envision Ruitai Power Technology Shanghai Co Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0567—Liquid materials characterised by the additives
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

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Abstract

The invention discloses a lithium ion battery electrolyte, a preparation method thereof and a lithium ion battery. A lithium ion battery electrolyte comprising a non-aqueous solvent and a lithium salt dissolved in the non-aqueous solvent, the lithium ion battery electrolyte further comprising an additive comprising an alkenyl group. The lithium ion battery electrolyte can not be easily oxidized, reduced and decomposed on the surfaces of the anode and the cathode in a high-temperature state, thereby reducing high-temperature gas generation of the lithium ion battery and improving the high-temperature storage performance, the high-temperature cycle performance and the safety performance of the lithium ion battery.

Description

Lithium ion battery electrolyte, preparation method thereof and lithium ion battery
Technical Field
The invention relates to the technical field of electrolyte, in particular to lithium ion battery electrolyte, a preparation method thereof and a lithium ion battery.
Background
The lithium ion battery has the advantages of high energy density, high working voltage, long cycle life, no memory effect and the like, is a main energy source of the conventional portable electronic equipment, and simultaneously shows good performance in the application fields of electric vehicles, intelligent Internet of things and the like.
To further meet the growing application demands, lithium ion batteries are required to have higher energy densities. At present, there are two main schemes for improving the energy density of lithium ion batteries: the first scheme is that a positive electrode material with high nickel element content is adopted; the second solution is to increase the charge cut-off voltage of the lithium ion battery. However, both solutions have an adverse effect on the electrolyte at the same time. Too high content of nickel element can reduce the stability of the anode material, and trivalent unstable nickel ions can cause the electrolyte to be oxidized and decomposed on the anode; on the other hand, the increase of the charging voltage of the battery can raise the potential of the positive electrode, and the electrolyte is easy to generate an oxidative decomposition process, which can cause a series of problems of battery flatulence, interface impedance increase and the like. In summary, both of the above solutions put more stringent requirements on the electrolyte material.
In view of the above, there is a need to develop and provide an electrolyte formulation capable of solving the above problems and forming a stable SEI film to inhibit the electrolyte from continuously reacting with the positive and negative electrodes, thereby improving the high-temperature storage performance, high-temperature cycle performance and safety performance of the lithium ion secondary battery.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to provide a lithium ion battery electrolyte, a preparation method thereof and a lithium ion battery.
One of the objectives of the present invention is to provide an electrolyte for a lithium ion battery, and to achieve the objective, the present invention adopts the following technical scheme:
the lithium ion battery electrolyte comprises a non-aqueous solvent and a lithium salt dissolved in the non-aqueous solvent, and further comprises an alkenyl-containing additive, wherein the infrared C-C double bond vibration characteristic peak of the alkenyl-containing additive is 1636-1690 cm-1。
The additive is a compound shown as a formula (I) or a formula (II):
Figure BDA0003277696690000021
wherein, in the formula (I), R1、R2And R3The groups are independently selected from substituents with unsaturation degree of 0-4 and carbon atom number of 1-10;
the arc in formula (II) represents R4、R5Are linked to form a ring which is cycloalkyl or at least one CH of cycloalkyl2Cyclic groups substituted with heteroatoms.
The lithium ion battery electrolyte is added with the additive containing the alkenyl, the battery has better stability in a high-temperature storage state and a high-temperature circulation state, and the electrolyte is not easy to be subjected to oxidation reduction decomposition on the surfaces of the anode and the cathode, so that the generation of gas is reduced, and therefore, the lithium ion battery has the advantage of small battery thickness expansion in high-temperature storage and high-temperature circulation, and has more ideal battery performance.
The infrared C-C double bond vibration characteristic peak of the alkenyl-containing additive is 1636-1690 cm-1The positive and negative electrode interface protective films with good compactness can be obtained.
Wherein, in the formula (I), R1、R2And R3The groups can be independently selected from alkyl groups with the degree of unsaturation of 0-4 and the number of carbon atoms of 1-10; r1、R2And R3The groups can be independently selected from alkoxy with the degree of unsaturation of 0-4 and the number of carbon atoms of 1-10; r1、R2And R3The groups can be independently selected from alkylthio groups with the unsaturation degree of 0-4 and the carbon number of 1-10; r1、R2And R3The groups can be respectively and independently selected from disubstituted alkylamino with the degree of unsaturation of 0-4 and the number of carbon atoms of 1-10; r1、R2And R3The groups can be respectively and independently selected from fluoroalkyl with the degree of unsaturation of 0-4 and the number of carbon atoms of 2-10; r1、R2And R3The groups can be independently selected from ester with unsaturation degree of 0-4 and carbon number of 2-10A substituent group; r1、R2And R3The groups may each be independently selected from cyano-containing substituents having an unsaturation degree of 0 to 4 and a carbon number of 2 to 10.
The arc in the formula (II) represents a carbon atom framework forming a ring, R4、R5The groups form a cyclopentyl or cyclohexyl group containing a heteroatom, wherein the heteroatom is nitrogen or oxygen.
The compound represented by the general formula (I) contains a substituent with electron pushing effect or electron pulling effect in the molecular structure, and can affect the electron cloud density of olefinic bonds. Firstly, the olefinic bond has a certain complexation effect on transition metal atoms; meanwhile, according to the push-pull electron effect, the molecular orbital energy level of the compound can be improved or reduced to different degrees, so that the priority of the redox reaction of the compound in the formula (I) or the formula (II) on the surface of the positive electrode or the negative electrode is further influenced, the compound is subjected to electrochemical polymerization on the positive electrode or the negative electrode to generate a polymer passivation film, and the oxidation or reduction decomposition of electrolyte components on the surfaces of the positive electrode and the negative electrode is inhibited, so that the high-temperature gas generation of the battery is reduced, and the high-temperature storage performance and the high-temperature cycle performance of the lithium ion battery are improved.
In an improvement of the lithium ion battery electrolyte according to the present invention, the amount of the alkenyl group-containing additive is 0.1 to 15% by mass of the lithium ion battery electrolyte, and for example, the amount of the alkenyl group-containing additive is 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, or 15% by mass of the lithium ion battery electrolyte. If the content is too low and is lower than 0.1 percent, the improvement effect of the addition of the additive on high-temperature storage and high-temperature circulation is not obvious; if the content is too high, more than 15%, the addition of the additive may form a thick passivation film, resulting in an increase in internal resistance of the battery and a decrease in battery capacity. The mass of the additive containing the alkenyl accounts for 0.1-15% of the mass of the lithium ion battery electrolyte, so that the battery can obtain better high-temperature performance and has higher capacity exertion.
As an improvement of the lithium ion battery electrolyte, the mass of the additive containing the alkenyl accounts for 0.1-10% of the mass of the lithium ion battery electrolyte.
In the electrolyte according to the invention, in particular, the compound of formula (I) or formula (II) may be selected from the group consisting of the alkenyl-containing additives
Figure BDA0003277696690000041
Figure BDA0003277696690000042
The characteristic vibration peaks of infrared C ═ C double bonds of the compounds are 1636-1690 cm-1In this case, the positive and negative electrode interface protective films having good density can be obtained, but the present invention is not limited thereto.
As an improvement of the lithium ion battery electrolyte of the present invention, the lithium ion battery electrolyte further includes a cyclic carbonate additive, a cyclic sultone additive, a cyclic sulfate additive, and a lithium salt additive. The cyclic carbonate additive is selected from any one of Vinylene Carbonate (VC), fluoroethylene carbonate (FEC) and ethylene carbonate (VEC) or a mixture of at least two of the Vinylene Carbonate (VC), the fluoroethylene carbonate (FEC) and the ethylene carbonate (VEC); the cyclic sultone or cyclic sulfate additive is selected from any one or a mixture of at least two of 1, 3-Propane Sultone (PS), 1, 3-Propylene Sultone (PST) and vinyl sulfate (DTD); the lithium salt additive is selected from LiPO2F2Any one or a mixture of at least two of LiFSI, LiODFB, LiTFSI and LiODFP.
As an improvement of the electrolyte of the lithium ion battery of the present invention, the nonaqueous solvent is any one of vinylene carbonate (EC), dimethyl carbonate (DMC), Ethyl Methyl Carbonate (EMC), Propylene Carbonate (PC), diethyl carbonate (DEC), or a mixture of at least two thereof.
Preferably, the nonaqueous solvent accounts for 60% to 85% by mass of the lithium ion battery electrolyte, for example, 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, or 85% by mass of the lithium ion battery electrolyte.
Preferably, the lithium salt dissolved in the nonaqueous solvent is LiPF6、LiBF4、LiClO4、LiAsF6One or a mixture of at least two of LiBOB;
preferably, the concentration of the lithium salt dissolved in the nonaqueous solvent is 0.5mol/L to 2mol/L, for example, 0.5mol/L, 0.6mol/L, 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, 1.6mol/L, 1.7mol/L, 1.8mol/L, 1.9mol/L, 2mol/L, or the like.
The second purpose of the invention is to provide a preparation method of the lithium ion battery electrolyte, which comprises the following steps: and mixing a non-aqueous solvent, lithium salt and an additive containing alkenyl according to a ratio to obtain the lithium ion battery electrolyte.
The invention also provides a lithium ion battery, which comprises a positive electrode current collector, a positive electrode active material coated on the positive electrode current collector, a negative electrode active material coated on the negative electrode current collector, an isolating membrane and the lithium ion battery electrolyte.
Wherein the positive active material comprises any one of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt manganese oxide or lithium nickel cobalt aluminum oxide or a mixture of at least two of the lithium cobalt oxide, the lithium nickel manganese oxide and the lithium nickel cobalt aluminum oxide.
The negative electrode active material is any one or a mixture of at least two of soft carbon, hard carbon, artificial graphite, natural graphite, silicon oxygen compound, silicon carbon compound or lithium titanate.
Compared with the prior art, the lithium ion battery electrolyte is added with the additive containing the alkenyl, so that the battery has better stability in a high-temperature storage state, and the electrolyte is not easy to be subjected to redox decomposition on the surfaces of the anode and the cathode, so that the generation of gas is reduced, therefore, the lithium ion battery has the advantage of small battery thickness expansion in high-temperature storage and high-temperature circulation, and has more ideal battery performance.
As an improvement of the lithium ion battery of the present invention, the positive electrode active material includes any one of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt manganese oxide and lithium nickel cobalt aluminum oxide or a mixture of at least two thereof.
As an improvement of the lithium ion battery of the present invention, the negative active material includes any one of soft carbon, hard carbon, artificial graphite, natural graphite, silicon oxy-compound, silicon carbon compound or lithium titanate or a mixture of at least two of them.
The electrolyte of the present invention can improve high-temperature storage performance and high-temperature cycle performance of a battery assembled from the positive electrode active material and the negative electrode active material.
Compared with the prior art, the invention has the beneficial effects that:
the lithium ion battery electrolyte can be hardly oxidized, reduced and decomposed on the surfaces of the anode and the cathode at a high temperature, so that the high-temperature gas generation of the lithium ion battery is reduced, and the high-temperature storage performance, the high-temperature cycle performance and the safety performance of the lithium ion battery are improved, specifically, the number of SOH turns at 45 ℃ reaches 80 percent and is 1104-doped 1290, the volume change rate of EOL gas generation at 45 ℃ is 24-59 percent, and the thickness expansion rate of the lithium ion battery after 30-day high-temperature storage at 60 ℃ is 5.4-35.2 percent.
Detailed Description
The technical solution of the present invention is further explained by the following embodiments.
Unless otherwise specified, various starting materials of the present invention are commercially available or prepared according to conventional methods in the art.
In the prior art, one technical scheme provides a high-film-forming-property lithium ion battery electrolyte and a using method thereof, wherein the high-film-forming-property lithium ion battery electrolyte is a high-concentration lithium salt electrolyte with the molar concentration higher than 3mol/L and consists of a lithium salt, a non-aqueous solvent, a positive electrode film-forming additive, a negative electrode film-forming additive and a wetting agent; the specific using process is to prepare a high-concentration lithium salt electrolyte with the molar concentration higher than 3 mol/L; injecting high-concentration lithium salt electrolyte into the soft package lithium ion battery and forming the soft package lithium ion battery; preparing lithium salt electrolyte with a conventional concentration and a molar concentration of 0.9-1.3 mol/L; and injecting lithium salt electrolyte with conventional concentration into the formed soft package lithium ion battery and carrying out cyclic charge and discharge on the soft package lithium ion battery. The electrolyte of the lithium ion battery can passivate aluminum foil, form stable anode and cathode solid electrolyte membranes, and overcome the problem of low ionic conductivity of high-concentration lithium salt.
The other technical scheme provides a lithium ion battery electrolyte and a lithium ion battery. The lithium ion battery electrolyte comprises a solvent, and a lithium salt and an additive which are dissolved in the solvent, wherein the solvent is a non-aqueous organic solvent, and the additive comprises at least one of fluorosulfonyl imide salt, hexafluorophosphate and oxalato borate. The lithium ion battery electrolyte has high working voltage, and the lithium ion battery electrolyte is endowed with chemical stability under the states of high-rate charge-discharge and high-power charge-discharge, meets the cycle requirements under high-rate, high-power and high-temperature, and effectively improves the cycle stability and safety of the lithium ion battery. In addition, the lithium ion battery electrolyte has good wettability and can reduce the impedance (DCR) of the lithium ion battery. The lithium ion battery has high working voltage, good cyclicity under high-rate charge and discharge and high-power charge and discharge, and high safety.
However, the high-temperature storage performance of the lithium ion battery needs to be further improved.
In order to solve at least the technical problems, the invention provides a lithium ion battery electrolyte, which comprises a non-aqueous solvent and a lithium salt dissolved in the non-aqueous solvent, and further comprises an alkenyl-containing additive, wherein the infrared C ═ C double bond vibration characteristic peak of the alkenyl-containing additive is 1636-1690 cm-1. The electrolyte of the lithium ion battery can form a stable SEI film to inhibit the electrolyte from continuously reacting with the anode and the cathode, so that the high-temperature storage performance, the high-temperature cycle performance and the safety performance of the lithium ion secondary battery are improved.
Example 1
(1) Preparing an electrolyte:
mixing Ethylene Carbonate (EC), Ethyl Methyl Carbonate (EMC),Mixing diethyl carbonate (DEC) with the components in the mass ratio of 3:5:2 to obtain a non-aqueous organic solvent, and mixing LiPF6Dissolving to obtain 1mol/L solution, and mixing with alkenyl-containing additive and 4.3% of other additives to obtain electrolyte, wherein the other additives comprise 0.8% of LiPO2F20.5 percent LiFSI, 0.5 percent LiODFP, 1 percent DTD, 0.5 percent VC and 1 percent PS, and the specific compositions are shown in Table 1.
(2) Preparing a lithium ion battery:
LiNi as positive electrode active material0.8Co0.1Mn0.1O2(LNCM), conductive agent acetylene black and adhesive polyvinylidene fluoride (PVDF) are fully stirred and uniformly mixed in an N-methyl pyrrolidone solvent system according to the mass ratio of 95:3:2, then the mixture is coated on an aluminum foil to be dried and cold-pressed, and a positive pole piece is obtained, wherein the compaction density of the positive pole piece is 3.45g/cm3。
Fully stirring and uniformly mixing a negative active material graphite, a conductive agent acetylene black, a binder Styrene Butadiene Rubber (SBR) and a thickening agent sodium carboxymethyl cellulose (CMC) in a deionized water solvent system according to a mass ratio of 96:2:1:1, coating the mixture on a Cu foil, drying and cold pressing to obtain a negative pole piece, wherein the compaction density of the negative pole piece is 1.65g/cm3。
Polyethylene (PE) with the thickness of 9 μm is used as a base film, and a nano alumina coating layer with the thickness of 3 μm is coated on the base film, so that the diaphragm is obtained.
And stacking the positive pole piece, the diaphragm and the negative pole piece in sequence, so that the diaphragm is positioned between the positive pole piece and the negative pole piece to play an isolating role, and stacking the pieces to obtain the bare cell.
And (2) filling the bare cell into an aluminum-plastic film, baking at the temperature of 80 ℃ to remove water, injecting corresponding electrolyte, sealing, standing, hot-cold pressing, forming, clamping, capacity grading and the like to obtain the finished product of the flexibly-packaged lithium ion secondary battery.
For comparison, an electrolyte was prepared and assembled into a battery in the same manner, the type and concentration of the non-aqueous organic solvent used were the same, and LiPF was present in the electrolyte6Are the same. Except that the electrolyte was different in composition, examples 1 to 15 and the pairThe lithium ion batteries of the ratios 1-2 were prepared by the method of example 1, and the specific compositions and amounts thereof are shown in table 1.
The alkenyl group-containing additives in the examples and comparative examples are specifically as follows: examples 1 to 8 differ only in the structural formula of the alkenyl group-containing additive, and specifically, the structural formula of the alkenyl group-containing additive in example 1 is
Figure BDA0003277696690000091
The structural formula of the alkenyl group-containing additive in example 2 is
Figure BDA0003277696690000092
The structural formula of the alkenyl group-containing additive in example 3 is
Figure BDA0003277696690000093
The structural formula of the alkenyl group-containing additive in example 4 is
Figure BDA0003277696690000094
The structural formula of the alkenyl group-containing additive in example 5 is
Figure BDA0003277696690000095
The structural formula of the alkenyl group-containing additive in example 6 is
Figure BDA0003277696690000096
The structural formula of the alkenyl group-containing additive in example 7 is
Figure BDA0003277696690000097
The structural formula of the alkenyl group-containing additive in example 8 is
Figure BDA0003277696690000098
The structural formula of the alkenyl-containing additives of examples 9 to 15 is
Figure BDA0003277696690000099
TABLE 1
Figure BDA00032776966900000910
Figure BDA0003277696690000101
The lithium ion batteries prepared in examples 1 to 15 and comparative examples 1 to 2 were subjected to performance tests, and the results of the tests are shown in table 2. Among them, the secondary battery of the present invention can be tested by the following method:
after aging treatment of examples and comparative examples, the activated batteries were charged to 4.3V at 45 ℃ with a current of 1C, and were constant-voltage to a current of 0.05C, and then discharged to 2.8V at 1C, and the discharge capacity was recorded. And after the first circle of discharge, performing a cycle test until the discharge capacity of the battery is 80% of the first circle of capacity, and stopping the cycle test until the battery reaches 80% of SOH (battery health state) after the cycle is finished and the volume change of the produced gas is recorded. The gas volume change is generated by the following method: after the secondary battery was fixed with a string, the secondary battery was completely immersed in water at 25 ℃, the weight difference before and after immersion was recorded, and the volume difference was obtained by conversion from the density of water at 25 ℃.
Charging the lithium ion battery to 4.2V at a constant current of 1C at 25 ℃, then charging the lithium ion battery to a constant voltage of 0.05C, testing the thickness of the lithium ion battery before storage and recording the thickness as D0. Then the fully charged battery is placed in a 60 ℃ oven for storage for 30 days, and the thickness after storage is tested and recorded as D1The thickness expansion rate (%) of the lithium ion battery stored in the storage was calculated as above formula, and the thickness expansion rate (%) after 60 ℃/30 days storage was ═ D1-D0)/D0×100％。
TABLE 2
Figure BDA0003277696690000111
Figure BDA0003277696690000121
As can be seen from the data in Table 2, the lithium ion battery electrolyte of the invention can be hardly oxidized, reduced and decomposed on the surfaces of the anode and the cathode at a high temperature, thereby reducing the high-temperature gas generation of the lithium ion battery and improving the high-temperature storage performance, the high-temperature cycle performance and the safety performance of the lithium ion battery, specifically, the number of SOH turns reaching 80% at 45 ℃ is 1104-1290, the EOL gas generation volume change rate at 45 ℃ is 24-59%, and the thickness expansion rate after 30-day high-temperature storage at 60 ℃ is 5.4-35.2%.
In example 9, only the alkenyl group-containing additive was added, and the cyclic carbonate additive, the cyclic sultone additive, the cyclic sulfate additive, and the lithium salt additive were not added, and although a protective film was formed at the interface between the positive and negative electrodes, the densification of the SEI film was not good enough, and the improvement in performance was slightly reduced.
Example 15 too much alkenyl-containing additive resulted in a sharp increase in the resistance of the high temperature resistant passivation film formed, deteriorating the chemical properties of the lithium ion battery.
Comparative example 1 without the addition of the alkenyl-containing additive, and without the addition of the cyclic carbonate additive, the cyclic sultone additive, the cyclic sulfate additive, and the lithium salt additive, deterioration of battery performance was the most severe because a dense SEI protective film could not be formed between the interfaces of the positive and negative electrode materials and the electrolyte.
Comparative example 2 no alkenyl-containing additive was added, and only the cyclic carbonate additive, the cyclic sultone additive, the cyclic sulfate additive, and the lithium salt additive were added, and although these additives also formed SEI films on the surfaces of the positive and negative electrodes, the compactness of the SEI films was insufficient, and the battery performance could not be significantly improved.
The present invention is illustrated by the above-mentioned examples, but the present invention is not limited to the above-mentioned detailed process equipment and process flow, i.e. it is not meant to imply that the present invention must rely on the above-mentioned detailed process equipment and process flow to be practiced. It should be understood by those skilled in the art that any modification of the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific modes, etc., are within the scope and disclosure of the present invention.
The preferred embodiments of the present invention have been described in detail, however, the present invention is not limited to the specific details of the above embodiments, and various simple modifications may be made to the technical solution of the present invention within the technical idea of the present invention, and these simple modifications are within the protective scope of the present invention.
It should be noted that the various technical features described in the above embodiments can be combined in any suitable manner without contradiction, and the invention is not described in any way for the possible combinations in order to avoid unnecessary repetition.
In addition, any combination of the various embodiments of the present invention is also possible, and the same should be considered as the disclosure of the present invention as long as it does not depart from the spirit of the present invention.

Claims (10)

1. The lithium ion battery electrolyte comprises a non-aqueous solvent and a lithium salt dissolved in the non-aqueous solvent, and is characterized by further comprising an alkenyl-containing additive, wherein the infrared C-C double bond vibration characteristic peak of the alkenyl-containing additive is 1636-1690 cm-1。
2. The lithium ion battery electrolyte of claim 1, wherein the additive is a compound of formula (I) or formula (II):
Figure FDA0003277696680000011
wherein, in the formula (I), R1、R2And R3The groups are independently selected from substituents with unsaturation degree of 0-4 and carbon atom number of 1-10;
the arc in formula (II) represents R4、R5Are linked to form a ring which is cycloalkyl or at least one CH of cycloalkyl2Cyclic groups substituted with heteroatoms.
3. The lithium ion battery electrolyte of claim 2 wherein in formula (I), R is1、R2And R3The groups are independently selected from alkyl, alkoxy, alkylthio or disubstituted alkylamino with the degree of unsaturation of 0-4 and the number of carbon atoms of 1-10;
preferably, R1、R2And R3The groups are independently selected from fluoroalkyl, cyano-containing substituent or ester-containing substituent with the degree of unsaturation of 0-4 and the carbon atom number of 2-10;
preferably, the heteroatom is nitrogen or oxygen.
4. The lithium ion battery electrolyte of any of claims 1 to 3, wherein the mass of the alkenyl-containing additive is 0.1 to 15%, preferably 0.1 to 10% of the mass of the lithium ion battery electrolyte.
5. The lithium ion battery electrolyte of any of claims 1-4 wherein the alkenyl-containing additive is
Figure FDA0003277696680000021
Figure FDA0003277696680000022
One kind of (1).
6. The lithium ion battery electrolyte of any of claims 1-5, further comprising a cyclic carbonate additive, a cyclic sultone additive, a cyclic sulfate additive, and a lithium salt additive;
preferably, the cyclic carbonate additive is any one or a mixture of at least two of vinylene carbonate, fluoroethylene carbonate or ethylene carbonate;
preferably, the cyclic sultone additive is 1, 3-propane sultone and/or 1, 3-propene sultone;
preferably, the cyclic sulfate additive is vinyl sulfate;
preferably, the lithium salt additive is LiPO2F2Any one or a mixture of at least two of LiFSI, LiODFB, LiTFSI, and LiODFP.
7. The lithium ion battery electrolyte of any one of claims 1-6, wherein the non-aqueous solvent is any one or a mixture of at least two of vinylene carbonate, dimethyl carbonate, ethyl methyl carbonate, propylene carbonate, or diethyl carbonate;
preferably, the mass of the non-aqueous solvent accounts for 60-85% of the mass of the lithium ion battery electrolyte;
preferably, the lithium salt dissolved in the nonaqueous solvent is LiPF6、LiBF4、LiClO4、LiAsF6One or a mixture of at least two of LiBOB;
preferably, the concentration of the lithium salt dissolved in the nonaqueous solvent is 0.5mol/L to 2 mol/L.
8. A method of preparing the lithium ion battery electrolyte of any of claims 1-7, comprising: and mixing a non-aqueous solvent, lithium salt and an additive containing alkenyl according to a ratio to obtain the lithium ion battery electrolyte.
9. A lithium ion battery comprising a positive electrode current collector and a positive electrode active material coated on the positive electrode current collector, a negative electrode current collector and a negative electrode active material coated on the negative electrode current collector, a separator, and the lithium ion battery electrolyte according to any one of claims 1 to 7.
10. The lithium ion battery according to claim 9, wherein the positive electrode active material comprises any one of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt manganese oxide, or lithium nickel cobalt aluminum oxide, or a mixture of at least two thereof;
preferably, the negative electrode active material is any one of soft carbon, hard carbon, artificial graphite, natural graphite, silicon-oxygen compound, silicon-carbon compound or lithium titanate or a mixture of at least two of the soft carbon, the hard carbon, the artificial graphite, the natural graphite, the silicon-oxygen compound, the silicon-carbon compound or the lithium titanate.
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