CN115832433A - Electrolyte and battery comprising same - Google Patents

Electrolyte and battery comprising same Download PDF

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Publication number
CN115832433A
CN115832433A CN202211275776.5A CN202211275776A CN115832433A CN 115832433 A CN115832433 A CN 115832433A CN 202211275776 A CN202211275776 A CN 202211275776A CN 115832433 A CN115832433 A CN 115832433A
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electrolyte
additive
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unsubstituted
formula
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王海
李素丽
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Zhuhai Cosmx Battery Co Ltd
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Zhuhai Cosmx Battery Co Ltd
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Priority to CN202211275776.5A priority Critical patent/CN115832433A/en
Publication of CN115832433A publication Critical patent/CN115832433A/en
Priority to PCT/CN2023/123415 priority patent/WO2024082979A1/en
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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
    • H01M10/052—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 provides an electrolyte and a lithium ion battery comprising the electrolyte, wherein a first additive in the electrolyte is an unsaturated cyclic compound containing sulfonic acid groups, and the sulfonic acid groups can form lithium alkyl sulfonate RSO on the surface of a negative electrode 3 Li, which increases ion conductivity of SEI film, the nitrile group in polynitrile compound is an electron-withdrawing group with higher dipole moment, and Co 3+ The second additive and the first additive can also form a polymerization net structure and act on the surface of the positive electrode together, so that the side reaction of the positive electrode and the electrolyte is reduced. And when the contents of the first additive and the second additive of the electrolyte satisfy the relation: when the ratio of 0.7 to 2A/(A + B) is less than or equal to 1, the two can achieve the best protection effect, and the safety performance can be effectively achievedThe barrier effect of (1).

Description

Electrolyte and battery comprising same
Technical Field
The invention belongs to the technical field of batteries, and particularly relates to an electrolyte and a battery comprising the electrolyte.
Background
The lithium ion battery has the advantages of high working voltage, high energy density, long service life, environmental friendliness and the like, and is widely applied to the fields of 3C digital products, electric tools, electric automobiles and the like. Especially in the 3C digital field, the lithium ion battery is becoming more popular due to the trend of lighter and thinner mobile power supplies of mobile electronic devices such as smart phones in recent years.
A lithium ion battery is a type of rechargeable battery that mainly relies on lithium ions moving between a positive electrode and a negative electrode to operate. During charging and discharging, li + Intercalation and deintercalation to and from two electrodes: upon charging, li + The lithium ion battery is extracted from the positive electrode and is inserted into the negative electrode through the electrolyte, and the negative electrode is in a lithium-rich state; the opposite is true during discharge. The electrolyte is one of the major materials of the lithium ion battery, has an indispensable function, and is known as the blood of the lithium ion battery. However, the most critical parts of the electrolyte for lithium ion batteries are additives, such as negative electrode film-forming additives, positive electrode film-forming additives, stabilizers, water scavengers, acid scavengers, and the like.
Generally, sulfur-containing additives have some effect on lowering the impedance of the battery, thereby improving the high-temperature and low-temperature performance of the battery. 1,3-Propane Sultone (PS) and vinyl sulfate (DTD) are used as representative additives containing sulfur elements, and have the effect of reducing battery impedance. However, since the PS additive has a carcinogenic hazard, the european union has strict regulations on the use of the PS additive, and when the electrolyte is injected into a battery to produce a product, the PS additive is subjected to a sample test (Reach test). And the thermal stability of the vinyl sulfate (DTD) is poor, and if no stabilizer exists, the acid value and the chromaticity of the electrolyte are deteriorated, so that the high-temperature performance of the battery is influenced. It is therefore not always feasible to develop new low impedance additives that can replace PS and DTD additives.
Disclosure of Invention
In order to solve the problem that PS and DTD are limited in use, the invention aims to provide an electrolyte and a battery comprising the electrolyte.
The purpose of the invention is realized by the following technical scheme:
an electrolyte comprising an organic solvent, an electrolytic lithium salt, and a functional additive comprising a first additive and a second additive; the first additive is selected from unsaturated cyclic compounds containing sulfonic acid groups, and the second additive is selected from polynitrile compounds.
According to an embodiment of the invention, the mass of the first additive is 0.1wt% to 5.0wt%, such as 0.1wt%, 0.2wt%, 0.3wt%, 0.4wt%, 0.5wt%, 0.6wt%, 0.7wt%, 0.8wt%, 0.9wt%, 1wt%, 1.1wt%, 1.2wt%, 1.3wt%, 1.4wt%, 1.5wt%, 1.6wt%, 1.7wt%, 1.8wt%, 1.9wt%, 2wt%, 2.2wt%, 2.4wt%, 2.5wt%, 2.6wt%, 2.8wt%, 3wt%, 3.3wt%, 3.5wt%, 3.8wt%, 4wt%, 4.2wt%, 4.5wt%, 4.8wt%, or 5wt% of the total mass of the electrolyte.
According to an embodiment of the invention, the mass of the second additive is 1wt% to 5.5wt%, such as 1wt%, 1.1wt%, 1.2wt%, 1.3wt%, 1.4wt%, 1.5wt%, 1.6wt%, 1.7wt%, 1.8wt%, 1.9wt%, 2wt%, 2.2wt%, 2.4wt%, 2.5wt%, 2.6wt%, 2.8wt%, 3wt%, 3.3wt%, 3.5wt%, 3.8wt%, 4wt%, 4.2wt%, 4.5wt%, 4.8wt%, 5wt%, 5.2wt% or 5.5wt% of the total mass of the electrolyte.
According to an embodiment of the present invention, the electrolyte satisfies the following relational expression:
0.7≤2A/(A+B)≤1
wherein A is the percentage content of the mass of the first additive in the total mass of the electrolyte, and B is the percentage content of the mass of the second additive in the total mass of the electrolyte.
According to an embodiment of the invention, 2A/(a + B) is 0.7, 0.75, 0.8, 0.85, 0.9, 0.95 or 1.
According to the embodiment of the invention, when 0.7 is not less than 2A/(A + B) is not less than 1, lithium alkyl sulfonate is arranged on the surface of the negative electrode by the first additive, and cobalt ions are complexed with the surface of the positive electrode by the second additive to form protection, so that the high-temperature performance and the safety performance of the battery at high temperature can be obviously improved under the synergistic effect of the lithium alkyl sulfonate and the cobalt ions; when 2A/(a + B) <0.7, the battery performance will deteriorate at the later cycle period due to insufficient protection of the negative electrode by the lithium alkylsulfonate formed by the first additive, and when 2A/(a + B) >1, the negative electrode impedance will be greatly affected by excessive content of the second additive, the compatibility will be poor, and cycle deterioration will result.
According to an embodiment of the present invention, the sulfonic acid group-containing unsaturated cyclic compound is a sulfonic acid group (-SO) -containing unsaturated cyclic compound 3 -) and an unsaturated double bond (-C = C-), and the-S-O-bond in the sulfonic acid group is linked to the unsaturated double bond and participates in the cyclization.
According to an embodiment of the invention, the first additive is selected from at least one of the compounds represented by formula (1):
Figure BDA0003896566470000031
in the general formula (1), R 1 、R 2 、R 3 、R 4 、R 5 、R 6 The same or different, independently from each other, is selected from hydrogen, halogen, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, substituted or unsubstituted cycloalkyl, substituted or unsubstituted aryl; if substituted, the substituent is alkyl or halogen.
According to an embodiment of the invention, R 1 、R 2 、R 3 、R 4 、R 5 、R 6 Identical or different, independently of one another, from hydrogen, halogen, substituted or unsubstituted C 1-20 Alkyl, substituted or unsubstituted C 2-20 Alkenyl, substituted or unsubstituted C 2-20 Alkynyl, substituted or unsubstituted C 3-20 Cycloalkyl, substituted or unsubstituted C 6-20 An aryl group; if substituted, the substituent is C 1-20 Alkyl, halogen.
According to an embodiment of the invention, R 1 、R 2 、R 3 、R 4 、R 5 、R 6 Identical or different, independently of one another, from hydrogen, halogen, substituted or unsubstituted C 1-12 Alkyl, substituted or unsubstituted C 2-12 Alkenyl, substituted or unsubstituted C 2-12 Alkynyl, substituted or unsubstituted C 3-12 Cycloalkyl, substituted or unsubstituted C 6-12 An aryl group; if substituted, the substituent is C 1-12 Alkyl, halogen.
According to an embodiment of the invention, R 1 、R 2 、R 3 、R 4 、R 5 、R 6 Identical or different, independently of one another, from hydrogen, halogen, substituted or unsubstituted C 1-6 Alkyl, substituted or unsubstituted C 2-6 Alkenyl, substituted or unsubstituted C 2-6 Alkynyl, substituted or unsubstituted C 3-6 Cycloalkyl, substituted or unsubstituted C 6-10 An aryl group; if substituted, the substituent is C 1-6 Alkyl, halogen.
According to an embodiment of the invention, R 1 、R 2 、R 3 、R 4 、R 5 、R 6 Identical or different, independently of one another, from hydrogen, halogen, substituted or unsubstituted C 1-3 Alkyl, substituted or unsubstituted C 2-3 Alkenyl, substituted or unsubstituted C 2-3 Alkynyl, substituted or unsubstituted C 3-4 Cycloalkyl, substituted or unsubstituted C 6-8 An aryl group; if substituted, the substituent is C 1-3 Alkyl, halogen.
According to an embodiment of the invention, R 1 、R 2 、R 3 、R 4 、R 5 、R 6 Identical or different, independently of one another, from hydrogen, halogen, substituted or unsubstituted C 1-2 Alkyl, substituted or unsubstituted C 2-3 Alkenyl, substituted or unsubstituted phenyl; if substituted, the substituent is C 1-3 Alkyl, halogen.
According to an embodiment of the invention, the first additive is selected from at least one of the compounds represented by formula (I) -formula (VIII):
Figure BDA0003896566470000041
according to an embodiment of the present invention, the polynitrile compound is selected from one or more of a dinitrile compound, a trinitrile compound and a tetranitrile compound.
According to an embodiment of the present invention, the polynitrile compound is at least one selected from the group consisting of a dinitrile-based compound represented by formula II-1, a trinitrile compound represented by formula II-2, and a tetranitrile compound represented by formula II-3:
NC-R 21 -CN formula II-1
Figure BDA0003896566470000051
Wherein R is 21 Is a group having 1 to 10 carbon atoms and having at least 2 substitution positions; r 22 Is a group having 1 to 10 carbon atoms and having at least 3 substitution positions; r 23 Is a group having 1 to 10 carbon atoms and having at least 4 substitution positions.
According to an embodiment of the invention, the group having 1 to 10 carbon atoms is selected from substituted or unsubstituted C 1 - 10 Alkyl, substituted or unsubstituted C 1-10 Alkoxy, substituted or unsubstituted C 2-10 Alkenyl, substituted or unsubstituted C 1-10 alkyl-O-C 1-10 Alkyl, substituted or unsubstituted C 1-10 alkyl-C (O) -C 1-10 Alkyl, substituted or unsubstituted C 4-10 Heteroaryl, substituted or unsubstituted C 4-10 Heterocyclic radical, substituted or unsubstituted C 6-10 Aryl, the substituent being halogen, substituted or unsubstituted C 1-10 An alkyl group.
According to an embodiment of the present invention, the dinitrile compound represented by formula II-1 is selected from at least one of the following compounds: succinonitrile, glutaronitrile, adiponitrile, sebaconitrile, nonanonitrile, dicyanobenzene, terephthalonitrile, pyridine-3,4-dinitrile, 2,5-dicyanopyridine, 2,2,3,3-tetrafluorosuccinonitrile, tetrafluoroterephthalonitrile, 4-tetrahydrothiopyran methylenemalononitrile, fumaronitrile, ethylene glycol dipropionitrile ether and 1,4,5,6-tetrahydro-5,6-dioxo-2,3-pyrazinedicarboxonitrile.
According to an embodiment of the present invention, the nitrile compound represented by formula II-2 is at least one selected from the group consisting of: 1,3,6-Hexanetricarbonitrile, 1,3,5-Cyclohexanetricarbonitrile, 1,3,5-benzenetricarbonitrile, 1,2,3-propanetricyanide, glycerol trinitrile.
According to an embodiment of the present invention, the tetracyanonitrile compound represented by the formula II-3 is at least one compound selected from the group consisting of: 1,1,3,3-propanetetracyclonitrile, 1,2,2,3-tetracyanopropane, 1,2,4,5-tetracyanobenzene, 2,3,5,6-pyrazine tetracyclonitrile, 3-methyl-3-propyl-cyclopropane-1,1,2,2-tetracyclonitrile, 7,7,8,8-tetracyanoquinodimethane, tetracyanoethylene, 1,1,2,2, -tetrakis (ethoxycyano) ethane, 3-methyl-3-propyl-cyclopropane-1,1,2,2-tetracyclonitrile.
According to embodiments of the present invention, the first additive may be prepared by methods known in the art or may be commercially available.
According to embodiments of the present invention, the second additive may be prepared by methods known in the art or may be commercially available.
According to the embodiment of the invention, the electrolyte further comprises a third additive, and the third additive is selected from at least one of fluoroethylene carbonate, vinyl sulfate, 1,3-propylene sultone, lithium difluoro oxalato borate, lithium difluoro phosphate and lithium difluoro dioxaoxalato phosphate. The third additive can participate in the generation of an SEI film in the initial formation stage to play a role in protecting the negative electrode, and can also continuously repair the damaged SEI film in the later cycle stage, so that the electrochemical performance of the battery is improved.
According to an embodiment of the present invention, the third additive is added in an amount of 10wt% to 15wt%, for example, 10wt%, 11wt%, 12wt%, 13wt%, 14wt%, or 15wt% based on the total weight of the electrolyte.
According to an embodiment of the invention, the electrolyte lithium salt is selected from lithium hexafluorophosphate (LiPF) 6 ) Lithium difluorophosphate (LiPO) 2 F 2 ) Lithium difluorooxalato borate (LiDFOB), lithium bistrifluoromethylsulfonimide, lithium difluorobis-oxalato phosphate, lithium tetrafluoroborate, lithium bisoxalato borate, lithium hexafluoroantimonate, lithium hexafluoroarsenate, bis (R), (R) and (R)One or more of lithium trifluoromethanesulfonyl) imide, lithium bis (pentafluoroethylsulfonyl) imide, lithium tris (trifluoromethanesulfonyl) methide or lithium bis (trifluoromethanesulfonyl) imide.
According to an embodiment of the present invention, the organic solvent is selected from carbonates and/or carboxylic esters, the carbonates being selected from one or several of the following fluorinated or unsubstituted solvents: ethylene Carbonate (EC), propylene Carbonate (PC), dimethyl carbonate, diethyl carbonate (DEC), ethyl methyl carbonate; the carboxylic ester is selected from one or more of the following fluorinated or unsubstituted solvents: propyl acetate, n-butyl acetate, isobutyl acetate, n-pentyl acetate, isoamyl acetate, propyl Propionate (PP), ethyl Propionate (EP), methyl butyrate, ethyl n-butyrate.
According to an embodiment of the invention, the electrolyte is used in a lithium ion battery.
The invention also provides a battery, which comprises the electrolyte.
According to an embodiment of the present invention, the battery further includes a positive electrode sheet containing a positive electrode active material, a negative electrode sheet containing a negative electrode active material, and a separator.
According to an embodiment of the present invention, the positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer coated on one or both surfaces of the positive electrode current collector, and the positive electrode active material layer includes a positive electrode active material, a conductive agent, and a binder.
According to an embodiment of the present invention, the negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer coated on one or both surfaces of the negative electrode current collector, the negative electrode active material layer including a negative electrode active material, a conductive agent, and a binder.
According to the embodiment of the invention, the positive electrode active material layer comprises the following components in percentage by mass: 80-99.8 wt% of positive active material, 0.1-10 wt% of conductive agent and 0.1-10 wt% of binder.
Preferably, the positive electrode active material layer comprises the following components in percentage by mass: 90-99.6 wt% of positive active material, 0.2-5 wt% of conductive agent and 0.2-5 wt% of binder.
According to the embodiment of the invention, the anode active material layer comprises the following components in percentage by mass: 80-99.8 wt% of negative active material, 0.1-10 wt% of conductive agent and 0.1-10 wt% of binder.
Preferably, the negative electrode active material layer comprises the following components in percentage by mass: 90-99.6 wt% of negative active material, 0.2-5 wt% of conductive agent and 0.2-5 wt% of binder.
According to an embodiment of the present invention, the negative active material is selected from at least one of artificial graphite, natural graphite, mesocarbon microbeads, hard carbon, soft carbon, nano silicon, silicon oxide, and silicon carbide.
According to the embodiment of the invention, the positive active material is selected from one or more of transition metal lithium oxide, lithium iron phosphate and lithium manganate; the chemical formula of the transition metal lithium oxide is Li 1+x Ni y Co z M (1-y-z) O 2 Wherein-0.1 is less than or equal to x is less than or equal to 1; y is more than or equal to 0 and less than or equal to 1,0 and less than or equal to 1, and y + z is more than or equal to 0 and less than or equal to 1; wherein M is one or more of Mg, zn, ga, ba, al, fe, cr, sn, V, mn, sc, ti, nb, mo and Zr.
According to an embodiment of the present invention, the conductive agent is at least one selected from the group consisting of conductive carbon black, acetylene black, ketjen black, conductive graphite, conductive carbon fiber, carbon nanotube, and metal powder.
According to an embodiment of the present invention, the binder is selected from at least one of sodium carboxymethylcellulose, styrene-butadiene latex, polytetrafluoroethylene, polyethylene oxide.
The invention has the beneficial effects that:
the invention provides an electrolyte and a lithium ion battery comprising the electrolyte, wherein a first additive in the electrolyte is an unsaturated cyclic compound containing sulfonic acid groups, and the sulfonic acid groups can form lithium alkyl sulfonate RSO on the surface of a negative electrode 3 Li increases ion conductivity of the SEI film, and unsaturated bonds in the first additive can perform polymerization reaction on the surface of the positive electrode to form a protective film, so that the oxidation rate of the electrolyte on the surface of the positive electrode is reducedSelf-discharge is reduced; the nitrile functional group contained in the polynitrile compound is an electron withdrawing group with higher dipole moment, which reacts with Co 3+ The second additive and the first additive can also form a polymerization network structure and act on the surface of the anode together, so that the side reaction of the anode and the electrolyte is reduced. And when the contents of the first additive and the second additive of the electrolyte satisfy the relation: when the ratio of 0.7 to 2A/(A + B) is less than or equal to 1, the two can achieve the best protection effect, and the effective barrier effect can be achieved in the aspect of safety performance.
Detailed Description
The present invention will be described in further detail with reference to specific examples. It is to be understood that the following examples are only illustrative and explanatory of the present invention and should not be construed as limiting the scope of the present invention. All the technologies realized based on the above-mentioned contents of the present invention are covered in the protection scope of the present invention.
The experimental methods used in the following examples are all conventional methods unless otherwise specified; reagents, materials and the like used in the following examples are commercially available unless otherwise specified.
Examples 1-13 the lithium ion batteries of comparative examples 1-2 were prepared by the following steps:
1) Preparation of positive plate
The positive electrode active material lithium cobaltate (LiCoO) 2 ) Mixing polyvinylidene fluoride (PVDF), SP (super P) and Carbon Nano Tubes (CNT) according to a mass ratio of 96; uniformly coating the positive active slurry on two surfaces of the aluminum foil; and drying the coated aluminum foil, and then rolling and slitting to obtain the required positive plate.
2) Preparation of negative plate
Mixing artificial graphite serving as a negative electrode active material, silicon monoxide, sodium carboxymethylcellulose (CMC-Na), styrene-butadiene rubber, conductive carbon black (SP) and single-walled carbon nanotubes (SWCNTs) according to a mass ratio of 79.5; uniformly coating the negative active slurry on two surfaces of a copper foil; and (3) airing the coated copper foil at room temperature, then transferring the copper foil to an oven at 80 ℃ for drying for 10h, and then carrying out cold pressing and slitting to obtain the negative plate.
3) Preparation of the electrolyte
In a glove box filled with argon (H) 2 O<0.1ppm，O 2 <0.1 ppm), EC/PC/DEC/PP was uniformly mixed in a mass ratio of 10/20/10/60, and then 1mol/L of well-dried lithium hexafluorophosphate (LiPF) was rapidly added thereto 6 ) After dissolution, 9wt% of fluoroethylene carbonate, the first additive (the compound represented by formula (II)) and the second additive (ADN and HTCN) in the amounts of equal mass shown in table 1 were added and mixed uniformly to prepare the electrolyte.
4) Preparation of lithium ion battery
Stacking the positive plate in the step 1), the negative plate in the step 2) and the isolation film in the order of the positive plate, the isolation film and the negative plate, and then winding to obtain a battery cell; and (3) placing the battery cell in an outer package aluminum foil, injecting the electrolyte in the step 3) into an outer package, and performing vacuum packaging, standing, formation, shaping, sorting and other processes to obtain the lithium ion battery. The charging and discharging range of the battery is 3.0-4.5V.
The lithium ion batteries obtained in the examples and the comparative examples were respectively subjected to the following performance tests:
1) High temperature cycle performance test at 45 DEG C
Carrying out charge-discharge circulation on the divided-capacity battery cell within a charge-discharge cut-off voltage range at 45 ℃ according to the multiplying power of 1C for 800 weeks, wherein the discharge capacity in the 1 st week is x 1mAh, and the discharge capacity in the Nth circle is y1mAh; the volume at week N was divided by the volume at week 1 to obtain the cycle volume retention ratio at week N, R1= y1/x1.
2) 85 ℃ high temperature storage test
The battery after the formation and the capacity grading is stood for 10min, then 3V is placed at 0.2C, the battery is stood for 10min, then 0.5C is fully charged, 0.05C is stopped, and the battery is stood for 10min. Testing the voltage, the internal resistance and the thickness of the battery in a full-charge state at 25 +/-5 ℃, placing the battery in an oven at 85 ℃ for 8 hours after the battery is fully charged, taking out the thermal-state battery to test the voltage, the internal resistance and the thickness, and performing capacity maintenance and recovery tests.
3) And (4) safety performance testing:
charging 0.5C of a capacity-divided battery core to the upper limit and cutting to voltage, keeping constant voltage to 0.05C, putting a fully charged sample in a thermal shock test box at the ambient temperature of 25 +/-5 ℃, then increasing the temperature to 140 +/-2 ℃ at the speed of 15 +/-2 ℃/min, keeping the temperature for 42min, finishing the test, observing whether the battery is on fire or exploded, if not, indicating the safety performance as 'safety', and indicating the safety performance as 'OK'; if only fire is fired, the test is indicated as 'fire', if only explosion is performed, the test is indicated as 'explosion', if both fire and explosion exist, the safety performance is indicated as 'fire explosion', and the test is not passed by using NG.
Table 1 compositions of electrolyte additives in lithium ion batteries of examples and comparative examples and test results
Figure BDA0003896566470000101
The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiment. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (10)

1. An electrolyte, characterized in that the electrolyte comprises an organic solvent, an electrolytic lithium salt and a functional additive, wherein the functional additive comprises a first additive and a second additive; the first additive is selected from unsaturated cyclic compounds containing sulfonic acid groups, and the second additive is selected from polynitrile compounds.
2. The electrolyte according to claim 1, wherein the mass percentage of the first additive to the total mass of the electrolyte is 0.1-5.0 wt%;
and/or the mass of the second additive accounts for 1-5.5 wt% of the total mass of the electrolyte.
3. The electrolyte of claim 1 or 2, wherein the electrolyte satisfies the following relationship:
0.7≤2A/(A+B)≤1
wherein A is the percentage content of the mass of the first additive in the total mass of the electrolyte, and B is the percentage content of the mass of the second additive in the total mass of the electrolyte.
4. The electrolyte according to claim 1, wherein the unsaturated cyclic compound having a sulfonic acid group is an unsaturated cyclic compound having a sulfonic acid group (-SO) 3 -) and an unsaturated double bond (-C = C-), and the-S-O-bond in the sulfonic acid group is linked to the unsaturated double bond and participates in the cyclization.
5. The electrolyte of claim 1,2 or 4, wherein the first additive is selected from at least one of the compounds of formula (1):
Figure FDA0003896566460000011
in the general formula (1), R 1 、R 2 、R 3 、R 4 、R 5 、R 6 Identical or different, independently of one another, from the group consisting of hydrogen, halogen, substituted or unsubstituted alkyl, substituted or unsubstituted alkenyl, substituted or unsubstituted alkynyl, substituted or unsubstituted cycloalkyl, substituted or unsubstituted aryl; if substituted, the substituent is alkyl or halogen.
6. The electrolyte of claim 5, wherein R is 1 、R 2 、R 3 、R 4 、R 5 、R 6 Same or differentAnd, independently of one another, are selected from hydrogen, halogen, substituted or unsubstituted C 1-20 Alkyl, substituted or unsubstituted C 2-20 Alkenyl, substituted or unsubstituted C 2-20 Alkynyl, substituted or unsubstituted C 3-20 Cycloalkyl, substituted or unsubstituted C 6-20 An aryl group; if substituted, the substituent is C 1-20 Alkyl, halogen.
7. The electrolyte according to claim 1, wherein the polynitrile compound is at least one selected from the group consisting of a dinitrile compound represented by formula II-1, a trinitrile compound represented by formula II-2, and a tetranitrile compound represented by formula II-3:
Figure FDA0003896566460000021
wherein R is 21 Is a group having 1 to 10 carbon atoms and having at least 2 substitution positions; r 22 Is a group having 1 to 10 carbon atoms and having at least 3 substitution positions; r is 23 Is a group having 1 to 10 carbon atoms and having at least 4 substitution positions.
8. The electrolyte of claim 7, wherein the dinitrile compound of formula II-1 is selected from at least one of the following compounds: succinonitrile, glutaronitrile, adiponitrile, sebaconitrile, nonanonitrile, dicyanobenzene, terephthalonitrile, pyridine-3,4-dinitrile, 2,5-dicyanopyridine, 2,2,3,3-tetrafluorosuccinonitrile, tetrafluoroterephthalonitrile, 4-tetrahydrothiopyran methylenemalononitrile, fumaronitrile, ethylene glycol dipropionitrile ether and 1,4,5,6-tetrahydro-5,6-dioxo-2,3-pyrazinedicarboxonitrile;
and/or the trinitrile compound shown in the formula II-2 is selected from at least one of the following compounds: 1,3,6-hexanetricarbonitrile, 1,3,5-cyclohexanetricarbonitrile, 1,3,5-benzenetricarbonitrile, 1,2,3-propanetricyanide, glycerol trinitrile;
and/or, the tetracyanonitrile compound shown in the formula II-3 is selected from at least one of the following compounds: 1,1,3,3-propanetetracyclonitrile, 1,2,2,3-tetracyanopropane, 1,2,4,5-tetracyanobenzene, 2,3,5,6-pyrazine tetracyclonitrile, 3-methyl-3-propyl-cyclopropane-1,1,2,2-tetracyclonitrile, 7,7,8,8-tetracyanoquinodimethane, tetracyanoethylene, 1,1,2,2, -tetrakis (ethoxycyano) ethane, 3-methyl-3-propyl-cyclopropane-1,1,2,2-tetracyclonitrile.
9. The electrolyte of claim 1, further comprising a third additive selected from at least one of fluoroethylene carbonate, ethylene sulfate, 1,3-propylene sultone, lithium difluorooxalato borate, lithium difluorophosphate, lithium difluorodioxaoxalato phosphate;
the addition amount of the third additive is 10-15 wt% of the total weight of the electrolyte.
10. A battery comprising the electrolyte of any one of claims 1-9.
CN202211275776.5A 2022-10-18 2022-10-18 Electrolyte and battery comprising same Pending CN115832433A (en)

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US8697293B2 (en) * 2008-04-25 2014-04-15 Lg Chem, Ltd. Non-aqueous electrolyte solution for lithium secondary battery and lithium secondary battery having the same
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