CN116190784A - Electrolyte and lithium ion battery comprising same - Google Patents

Electrolyte and lithium ion battery comprising same Download PDF

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Publication number
CN116190784A
CN116190784A CN202211637260.0A CN202211637260A CN116190784A CN 116190784 A CN116190784 A CN 116190784A CN 202211637260 A CN202211637260 A CN 202211637260A CN 116190784 A CN116190784 A CN 116190784A
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carbon atoms
additive
compound
electrolyte
group
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刘文博
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Dongguan Weike Battery Co ltd
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Dongguan Weike Battery 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

Abstract

The invention relates to the technical field of lithium ion batteries, in particular to an electrolyte and a lithium ion battery comprising the same. The electrolyte comprises lithium salt, an organic solvent and an additive; the additive comprises an additive A and an additive B, wherein the additive A is a sulfonamide compound or a sulfinamide compound, and the additive B is a thiophene silicon nitrile compound. According to the invention, through the synergistic effect of the sulfonamide and/or sulfinamide compounds and the thiophene silicon nitrile compounds, the high-voltage resistance of the battery can be effectively improved, and the low-temperature performance and the cycle performance of the battery can be considered.

Description

Electrolyte and lithium ion battery comprising same
Technical Field
The invention relates to the technical field of lithium ion batteries, in particular to an electrolyte and a lithium ion battery comprising the same.
Background
The lithium ion battery is widely used by people due to the characteristics of high working voltage, large specific energy, long cycle life, no memory effect and the like. Currently, lithium ion batteries are widely applied to the field of 3C digital consumer electronics. Along with the continuous improvement of the capacity requirement of electric equipment on lithium ion batteries, the energy density improvement of the lithium ion batteries is expected to be higher and higher. Particularly, various portable devices such as smart phones, tablet computers, notebook computers and the like have higher requirements on lithium ion batteries with small volumes and long standby time. Also in other consumers, such as: energy storage devices, electric tools, electric automobiles and the like are also continuously emitting lithium ion batteries with lighter weight, smaller volume and higher output voltage and power density, so that the development of lithium ion batteries with high energy density is an important research and development direction of the lithium battery industry.
Increasing the charge cutoff voltage of lithium ion batteries is one of the important means to increase energy density. However, high voltage lithium ion batteries have a great contribution in improving the energy density of the batteries, but have a great problem. Under high voltage, the oxidation activity of the positive electrode material is increased, the stability is reduced, so that the electrolyte can continuously perform oxidative decomposition reaction on the surface of the positive electrode, active lithium ions are continuously consumed, and the high-temperature storage performance of the battery is deteriorated; meanwhile, the transition metal element in the positive electrode active material may be eluted due to the occurrence of oxidation-reduction reaction, resulting in further deterioration of the lithium ion battery.
Therefore, the electrolyte provided has important significance in improving the high-voltage resistance, the low-temperature resistance and the cycle performance of the lithium ion battery.
Disclosure of Invention
In view of the above, it is necessary to provide an electrolyte and a lithium ion battery including the electrolyte, which can effectively improve the high voltage resistance of the battery and also can give consideration to the low temperature performance and cycle performance of the battery.
In order to achieve the above purpose, the present invention adopts the following technical scheme:
in a first aspect, the present invention provides an electrolyte comprising a lithium salt, an organic solvent, and an additive. The additive comprises an additive A and an additive B, wherein the additive A is a sulfonamide compound and/or a sulfinamide compound, and the additive B is a thiophene silicon nitrile compound;
the structural formula of the sulfinamide compound is shown as a formula I, and the structural formula of the sulfonamide compound is shown as a formula II:
Figure BDA0004003712180000021
wherein R1 to R4 are each independently selected from at least one of a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, an aryl group having 6 to 12 carbon atoms, an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, and an aryl group having 6 to 12 carbon atoms substituted with a cyano group or a halogen atom;
the structural formula of the thiophene silicon nitrile compound is shown as formula III:
Figure BDA0004003712180000022
wherein R5 to R6 are each independently selected from at least one of a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, an aryl group having 6 to 12 carbon atoms, an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, and an aryl group having 6 to 12 carbon atoms substituted with a cyano group or a halogen atom;
wherein R is at least one selected from the group consisting of an alkyl group having 0 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, an aryl group having 6 to 12 carbon atoms, an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, and an aryl group having 6 to 12 carbon atoms substituted with a cyano group or a halogen atom.
Further, the sulfinamide compound is at least one of the following compounds:
Figure BDA0004003712180000031
further, the sulfonamide compound is selected from at least one of the following compounds:
Figure BDA0004003712180000032
further, the thiophen silacrylic acid compound is selected from at least one of the following compounds:
Figure BDA0004003712180000041
further, the additive further comprises at least one of vinylene carbonate, 1, 4-butane sultone, 1, 3-propene sultone, fluoroethylene carbonate, ethylene carbonate, ethylene sulfate, methylene methane disulfonate, succinonitrile, adiponitrile, 1,3, 6-hexanetrinitrile, 1,2, 3-tris (2-cyanooxy) propane, ethylene glycol bis (propionitrile) ether, tripropynyl phosphate (TPP).
Further, the mass of the additive is 0.5-15 wt% of the total mass of the electrolyte.
Preferably, the mass of the additive B is 1-3 wt% of the total mass of the electrolyte.
Further, the lithium salt includes LiPF 6 、LiBF 4 、LiClO 4 、LiFSI、LiTFSI、LiBOB、LiDFOB、LiFAP、LiSbF6、LiCF 3 SO 3 、LiN(SO 2 CF 3 ) 2 、LiN(SO 2 C 2 F 5 ) 2 、LiN(SO 2 CF 3 ) 2 、LiN(SO 2 C 4 F 9 ) 2 、LiC(SO 2 CF 3 ) 3 、LiPF 3 (C 3 F 7 ) 3 、LiB(CF 3 ) 4 And LiBF 3 (C 2 F 5 ) At least one of them.
Further, the mass of the lithium salt is 8-20wt% of the total mass of the electrolyte.
Further, the organic solvent is at least one of ethylene carbonate, propylene carbonate, diethyl carbonate, methyl ethyl carbonate, ethyl propionate, propyl propionate, ethyl acetate, ethyl n-butyrate and gamma-butyrolactone.
Further, the mass of the organic solvent is 50-90 wt% of the total mass of the electrolyte.
In a second aspect, the present invention provides a lithium ion battery comprising a positive electrode, a negative electrode, a separator and the electrolyte.
Further, the active material in the positive electrode includes, but is not limited to, liCoO 2 、LiNiO 2 、LiVO 2 、LiCrO 2 、LiMn 2 O 4 、LiCoMnO 4 、L i2 NiMn 3 O 8 、LiNi 0.5 Mn 1.5 O 4 、LiCoPO 4 、LiMnPO 4 、LiFePO 4 、LiNiPO 4 、LiCoFSO 4 、CuS 2 、FeS 2 、MoS 2 、NiS、TiS 2 At least one of them.
Preferably, the active material in the positive electrode is modified by a modification process including, but not limited to, coating or doping; the materials used for the modification treatment include, but are not limited to, at least one of Al, B, P, zr, si, ti, ge, sn, mg, ce, W.
Further, the active material in the negative electrode includes, but is not limited to, at least one of graphite, soft carbon, hard carbon, carbon fibers, mesophase carbon microspheres, silicon-based materials, tin-based materials, lithium titanate, or other metals capable of forming alloys with lithium.
Preferably, the graphite comprises at least one of artificial graphite, natural graphite and modified graphite; the silicon-based material comprises at least one of elemental silicon, a silicon oxygen compound, a silicon carbon compound and a silicon alloy; the tin-based material comprises at least one of elemental tin, a tin oxide compound and a tin alloy.
Further, the separator includes, but is not limited to, at least one of polyethylene, polypropylene, polyvinylidene fluoride, aramid, polyethylene terephthalate, polytetrafluoroethylene, polyacrylonitrile, polyimide, polyamide, polyester, and natural fibers.
Advantageous effects
1. According to the electrolyte provided by the invention, the sulfonic acid/sulfinic acid groups of the additive A can be subjected to reduction reaction preferentially to other additives, so that a low-impedance SEI film with a sulfur-containing structure is formed, and the low-temperature performance of the battery is improved; the contained amide group has Lewis base characteristic, so that HF in the electrolyte can be neutralized, and corrosion of HF on the anode material is reduced; thiophene groups of the electrolyte additive B can be reduced on the surface of the negative electrode preferentially to form a large amount of low-impedance SEI films of dimeric sulfur compounds, and the low-temperature characteristic and the rate characteristic of the battery can be improved.
2. The silane group of the additive B in the electrolyte provided by the invention can form a derivative on the surface of the anodeThe stable SEI film can better adapt to the volume change of the negative electrode in the charge and discharge process, improve the electrode/electrolyte interface of the high-voltage lithium ion battery and slow down the occurrence of negative and positive electrode interface side reaction in the circulation process; the silane structure is also a Lewis base, and can be used with HF and H containing active proton hydrogen in electrolyte 2 O is hydrolyzed or polymerized to remove H 2 O and HF inhibition purposes, thereby improving LiPF 6 And the heat stability of the battery is improved. The cyano group in the electrolyte additive B provided by the invention can be complexed with the metal ions of the positive electrode to play a role in protecting the positive electrode, so that the high-temperature performance of the battery under high voltage is greatly improved.
3. According to the invention, through the synergistic effect of the sulfonamide/sulfinamide compound and the thiophen silicon nitrile compound, the high-voltage resistance of the battery can be effectively improved, and the low-temperature performance and the cycle performance of the battery can be considered.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be further clearly and completely described in the following in conjunction with the embodiments of the present invention. It should be noted that the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The invention provides an electrolyte additive, an electrolyte and a lithium ion battery.
An electrolyte includes a lithium salt, an organic solvent, and an additive. The additive comprises an additive A and an additive B, wherein the additive A is a sulfonamide compound and/or a sulfinamide compound, and the additive B is a thiophene silicon nitrile compound;
the structural formula of the sulfinamide compound is shown as a formula I, and the structural formula of the sulfonamide compound is shown as a formula II:
Figure BDA0004003712180000071
wherein R1 to R4 are each independently selected from at least one of a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, an aryl group having 6 to 12 carbon atoms, an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, and an aryl group having 6 to 12 carbon atoms substituted with a cyano group or a halogen atom;
the structural formula of the thiophene silicon nitrile compound is shown as formula III:
Figure BDA0004003712180000072
wherein R5 to R6 are each independently selected from at least one of a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, an aryl group having 6 to 12 carbon atoms substituted with a cyano group or a halogen atom;
wherein R is at least one selected from the group consisting of an alkyl group having 0 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, an aryl group having 6 to 12 carbon atoms, an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, and an aryl group having 6 to 12 carbon atoms substituted with a cyano group or a halogen atom.
R is selected from alkyl groups having 0 carbon atoms, that is, R is not contained in formula III.
In some embodiments, the sulfenamide compound is selected from at least one of the following:
Figure BDA0004003712180000081
in some embodiments, the sulfonamide compound is selected from at least one of the following:
Figure BDA0004003712180000082
in some embodiments, the thiophenecarbonitrile compound is selected from at least one of the following:
Figure BDA0004003712180000091
in some embodiments, the additive further comprises at least one of vinylene carbonate, 1, 4-butane sultone, 1, 3-propene sultone, fluoroethylene carbonate, ethylene sulfate, methylene methane disulfonate, succinonitrile, adiponitrile, 1,3, 6-hexanetrinitrile, 1,2, 3-tris (2-cyanooxy) propane, ethylene glycol bis (propionitrile) ether, tripropynyl phosphate (TPP).
In some embodiments, the additive is present in an amount of 0.5 to 15wt% based on the total mass of the electrolyte.
In some embodiments, the lithium salt comprises LiPF 6 、LiBF 4 、LiClO 4 、LiFSI、LiTFSI、LiBOB、LiDFOB、LiFAP、LiSbF6、LiCF 3 SO 3 、LiN(SO 2 CF 3 ) 2 、LiN(SO 2 C 2 F 5 ) 2 、LiN(SO 2 CF 3 ) 2 、LiN(SO 2 C 4 F 9 ) 2 、LiC(SO 2 CF 3 ) 3 、LiPF 3 (C 3 F 7 ) 3 、LiB(CF 3 ) 4 And LiBF 3 (C 2 F 5 ) At least one of them.
In some embodiments, the lithium salt is 8 to 20wt% of the total mass of the electrolyte.
In some embodiments, the organic solvent is at least one of ethylene carbonate, propylene carbonate, diethyl carbonate, methylethyl carbonate, ethyl propionate, propyl propionate, ethyl acetate, ethyl n-butyrate, gamma-butyrolactone.
In some embodiments, the mass of the organic solvent is 50 to 90wt% of the total mass of the electrolyte.
A lithium ion battery comprises a positive electrode, a negative electrode, a diaphragm and the electrolyte.
In some embodiments, the active material in the positive electrode includes, but is not limited to, liCoO 2 、LiNiO 2 、LiVO 2 、LiCrO 2 、LiMn 2 O 4 、LiCoMnO 4 、L i2 NiMn 3 O 8 、LiNi 0.5 Mn 1.5 O 4 、LiCoPO 4 、LiMnPO 4 、LiFePO 4 、LiNiPO 4 、LiCoFSO 4 、CuS 2 、FeS 2 、MoS 2 、NiS、TiS 2 At least one of them.
In some embodiments, the active material in the positive electrode is subjected to a modification treatment, including but not limited to coating or doping; the materials used for the modification treatment include, but are not limited to, at least one of Al, B, P, zr, si, ti, ge, sn, mg, ce, W.
In some embodiments, further, the active material in the negative electrode includes, but is not limited to, at least one of graphite, soft carbon, hard carbon, carbon fibers, mesophase carbon microspheres, silicon-based materials, tin-based materials, lithium titanate, or other metals capable of forming alloys with lithium.
In some embodiments, the graphite comprises one or more of artificial graphite, natural graphite, and modified graphite; the silicon-based material comprises one or more of elemental silicon, a silicon-oxygen compound, a silicon-carbon compound and a silicon alloy; the tin-based material comprises one or more of elemental tin, tin oxide and tin alloy.
In some embodiments, the separator includes, but is not limited to, at least one of polyethylene, polypropylene, polyvinylidene fluoride, aramid, polyethylene terephthalate, polytetrafluoroethylene, polyacrylonitrile, polyimide, polyamide, polyester, and natural fibers.
The compound used in the embodiment of the invention is synthesized by adopting a conventional chemical method, and the structural formula of the compound is satisfied, and the invention is not particularly limited.
In the description of the present invention, it is to be noted that the specific conditions are not specified in the examples, and the description is performed under the conventional conditions or the conditions recommended by the manufacturer. The reagents or apparatus used were conventional products commercially available without the manufacturer's attention.
Example 1
1. Preparation of electrolyte
Mixing Ethylene Carbonate (EC), propylene Carbonate (PC), propyl Propionate (PP) and diethyl carbonate (DEC) according to a mass ratio of 1:1:2:1 in a glove box filled with argon, wherein the moisture content is less than 5ppm and the oxygen content is less than 5ppm, so as to obtain an organic solvent; mixing an organic solvent with lithium hexafluorophosphate, wherein the lithium hexafluorophosphate is 14.0wt% of the total mass of the electrolyte; then adding an additive, and uniformly mixing, wherein the additive is 4.0wt% of 1, 3-propylene sultone, 10.0wt% of fluoroethylene carbonate, 2wt% of 1,3, 6-Hexanetrinitrile (HTCN), 0.2wt% of compound I-2 and 2wt% of compound III-10. The mass fraction in the examples is the percentage of the additive substance in the total mass of the electrolyte.
2. Preparation of the Positive electrode
The positive electrode active material LiCoO was mixed at a mass ratio of 97:1.8:1.2 2 Conductive carbon black Super-P and a binder polyvinylidene fluoride (PVDF) are then dispersed in N-methyl-2-pyrrolidone (NMP) to obtain a positive electrode slurry. The slurry is evenly coated on two sides of an aluminum foil, and the positive plate is obtained after drying, calendaring and vacuum drying, and an aluminum outgoing line is welded by an ultrasonic welder, and the thickness of the pole piece is 120-150 mu m.
3. Preparation of negative electrode
The negative electrode active material artificial graphite, conductive carbon black Super-P, binder Styrene Butadiene Rubber (SBR) and carboxymethyl cellulose (CMC) are mixed according to the mass ratio of 96:0.8:1.6:1.6, and then dispersed in ionized water to obtain a negative electrode slurry. Coating the slurry on two sides of a copper foil, drying, calendaring and vacuum drying, and welding a nickel outgoing line by an ultrasonic welder to obtain a negative plate, wherein the thickness of the negative plate is 120-150 mu m.
4. Preparation of lithium ion batteries
And stacking the anode, the isolating film and the cathode in sequence, enabling the isolating film to be positioned between the anode and the cathode to play a role of isolation, then placing the isolating film in an outer packaging foil, injecting electrolyte into the dried battery, and completing the preparation of the lithium ion battery through the procedures of vacuum packaging, standing, formation, shaping and the like.
Example 2
The difference from example 1 was that the additive was 4.0wt% of 1, 3-propenesulfonic acid lactone, 10.0wt% of fluoroethylene carbonate, 2wt% of 1,3, 6-Hexanetrinitrile (HTCN), 0.5wt% of compound I-2 and 2wt% of compound III-10. The remainder were identical.
Example 3
The difference from example 1 is that the additives are 4.0% by weight of 1, 3-propenesulfonic acid lactone, 10.0% by weight of fluoroethylene carbonate, 2% by weight of 1,3, 6-Hexanetrinitrile (HTCN), 1% by weight of compound I-2 and 2% by weight of compound III-10. The remainder were identical.
Example 4
The difference from example 1 is that the additives are 4.0% by weight of 1, 3-propenesulfonic acid lactone, 10.0% by weight of fluoroethylene carbonate, 2% by weight of 1,3, 6-Hexanetrinitrile (HTCN), 2% by weight of compound I-2 and 2% by weight of compound III-10. The remainder were identical.
Example 5
The difference from example 1 is that the additives are 4.0% by weight of 1, 3-propenesulfonic acid lactone, 10.0% by weight of fluoroethylene carbonate, 2% by weight of 1,3, 6-Hexanetrinitrile (HTCN), 1% by weight of compound II-2 and 2% by weight of compound III-10. The remainder were identical.
Example 6
The difference from example 1 was that the additives were 4.0wt% of 1, 3-propenesulfonic acid lactone, 10.0wt% of fluoroethylene carbonate, 2wt% of 1,3, 6-Hexanetrinitrile (HTCN), 1wt% of compound I-2 and 0.5wt% of compound III-10. The remainder were identical.
Example 7
The difference from example 1 is that the additives are 4.0% by weight of 1, 3-propenesulfonic acid lactone, 10.0% by weight of fluoroethylene carbonate, 2% by weight of 1,3, 6-Hexanetrinitrile (HTCN), 1% by weight of compound I-2 and 1% by weight of compound III-10. The remainder were identical.
Example 8
The difference from example 1 is that the additives are 4.0% by weight of 1, 3-propenesulfonic acid lactone, 10.0% by weight of fluoroethylene carbonate, 2% by weight of 1,3, 6-Hexanetrinitrile (HTCN), 1% by weight of compound I-2 and 3% by weight of compound III-10. The remainder were identical.
Example 9
The difference from example 1 is that the additives are 4.0% by weight of 1, 3-propenesulfonic acid lactone, 10.0% by weight of fluoroethylene carbonate, 2% by weight of 1,3, 6-Hexanetrinitrile (HTCN), 1% by weight of compound I-2 and 5% by weight of compound III-10. The remainder were identical.
Example 10
The difference from example 1 is that the additives are 4.0% by weight of 1, 3-propenesulfonic acid lactone, 10.0% by weight of fluoroethylene carbonate, 2% by weight of 1,3, 6-Hexanetrinitrile (HTCN), 1% by weight of compound I-2 and 2% by weight of compound III-1. The remainder were identical.
Example 11
The difference from example 1 is that the additive is 4.0% by weight of 1, 3-propenesulfonic acid lactone, 10.0% by weight of fluoroethylene carbonate, 1% by weight of compound I-2 and 2% by weight of compound III-10. The remainder were identical.
Example 12
The difference from example 1 is that the additives are 4.0% by weight of 1, 3-propenesulfonic acid lactone, 10.0% by weight of fluoroethylene carbonate, 2% by weight of 1,3, 6-Hexanetrinitrile (HTCN), 1% by weight of compound I-2, 1% by weight of compound II-2 and 2% by weight of compound III-10. The remainder were identical.
Example 13
The difference from example 1 was that the additive was 4.0wt% of 1, 3-propenesulfonic acid lactone, 10.0wt% of fluoroethylene carbonate, 2wt% of 1,3, 6-Hexanetrinitrile (HTCN), 1wt% of compound I-2, 2wt% of compound III-1 and 2wt% of compound III-10. The remainder were identical.
Example 14
The difference from example 1 was that the additive was 4.0wt% of 1, 3-propenesulfonic acid lactone, 10.0wt% of fluoroethylene carbonate, 2wt% of 1,3, 6-Hexanetrinitrile (HTCN), 0.5wt% of compound I-2, 0.5wt% of compound II-2 and 2wt% of compound III-10. The remainder were identical.
Example 15
The difference from example 1 was that the additive was 4.0wt% of 1, 3-propenesulfonic acid lactone, 10.0wt% of fluoroethylene carbonate, 2wt% of 1,3, 6-Hexanetrinitrile (HTCN), 1wt% of compound I-2, 1wt% of compound III-1 and 1wt% of compound III-10. The remainder were identical.
Example 16
The difference from example 1 was that the additives were 4.0wt% of 1, 3-propenesulfonic acid lactone, 10.0wt% of fluoroethylene carbonate, 2wt% of 1,3, 6-Hexanetrinitrile (HTCN), 0.5wt% of compound I-2, 0.5wt% of compound II-2, 1wt% of compound III-1 and 1wt% of compound III-10. The remainder were identical.
Comparative example 1
The difference from example 1 is that the additive is 4.0% by weight of 1, 3-propenesulfonic acid lactone, 10.0% by weight of fluoroethylene carbonate. The remainder were identical.
Comparative example 2
The difference from example 1 is that the additive is 4.0wt% 1, 3-propenesulfonic acid lactone, 10.0wt% fluoroethylene carbonate, 2wt%1,3, 6-Hexanetrinitrile (HTCN). The remainder were identical.
Comparative example 3
The difference from example 1 is that the additive is 4.0% by weight of 1, 3-propenesulfonic acid lactone, 10.0% by weight of fluoroethylene carbonate, 2% by weight of 1,3, 6-Hexanetrinitrile (HTCN), 1% by weight of compound I-2. The remainder were identical.
Comparative example 4
The difference from example 1 is that the additive is 4.0% by weight of 1, 3-propenesulfonic acid lactone, 10.0% by weight of fluoroethylene carbonate, 2% by weight of 1,3, 6-Hexanetrinitrile (HTCN), 2% by weight of compound III-10. The remainder were identical.
Lithium ion battery performance test
The lithium ion batteries prepared in comparative examples 1 to 4 and examples 1 to 16 were subjected to cycle performance test, low-temperature discharge performance test and high-temperature storage performance test, respectively, as follows:
1) 45 ℃ cycle performance test
At 45 ℃, the battery is charged to 4.5V with a constant current of 0.5C, further charged to 0.025C with a constant voltage of 4.5V, and discharged to 3.0V with a constant current of 0.5C, which is a charge-discharge cycle process, and the discharge capacity of this time is the discharge capacity C1 of the 1 st cycle. And carrying out repeated cycle charge and discharge tests on the battery according to the mode, detecting to obtain the discharge capacity C2 of the 500 th cycle, and calculating the capacity retention rate of the battery after the cycle according to the following formula. Capacity retention (%) =c2/C1×100% after 500 cycles of the battery.
2) Low temperature discharge performance test
The battery is firstly charged to 4.5V at 25 ℃ with constant current of 0.5C, further charged to 0.025C with constant voltage of 4.5V, discharged to 3.0V with constant current of 0.5C, and the discharge capacity C3 is recorded; the battery was again charged to 4.5V with a constant current of 0.5C, further charged to 0.025C with a constant voltage of 4.5V, left in an environment of-20 ℃ for 24 hours, discharged to 3.0V with a constant current of 0.2C, and the discharge capacity C4 was recorded. Low temperature discharge rate (%) =c4/c3×100% at-20 ℃.
3) High temperature storage performance test
The high-temperature storage performance of the battery is characterized by the volume change rate of the battery before and after storage.
At 25 ℃, the battery is charged to 4.5V with constant current of 0.5C, further charged to 0.025C with constant voltage of 4.5V, the initial volume of the battery is measured in deionized water by a drainage method, the initial volume of the battery at the moment is taken as the volume V1 before the battery is stored, then the battery is stored at 85 ℃ for 6 hours, after the storage is finished, the volume V2 of the battery after the storage at high temperature is measured, and the volume change rate of the battery is calculated by the following formula. The volume change rate (%) =v2/v1% of the battery.
Table 1 lithium ion battery performance
Figure BDA0004003712180000161
Figure BDA0004003712180000171
As is clear from the comparison of examples 1 to 4, the cycle performance of the battery is remarkably improved with the increase of the content of the sulfenamide compound, but the cycle life tends to decrease when the content is large, mainly because the excessive sulfenamide compound causes the transportation obstruction of lithium ions, thereby not effectively improving the cycle performance of the battery.
As is clear from comparison of examples 3 and examples 6 to 9, as the content of the thiophen-based silacrylic compound increases, the high-temperature storage performance of the battery is remarkably improved, but the low-temperature discharge performance thereof is gradually deteriorated, so that the amount of the thiophen-based silacrylic compound is preferably controlled to be 1 to 3wt%.
As can be seen from the comparison of comparative examples 3 to 4 and examples 1 to 10, the sulfonamide and/or sulfenamide compounds and the thiophen silacrylic compounds act synergistically to improve the comprehensive performance of the lithium ion battery.
As is clear from the comparison of comparative examples 1 to 2 and examples 3 to 11, HTCN also improved the cycle performance and the high-temperature storage performance to some extent, and HTCN was synergistic with the three of the sulfonamide/sulfenamide compound and the thiophen silacrylic compound in this example. The lithium ion battery has better comprehensive performance.
The foregoing examples illustrate only a few embodiments of the invention and are described in detail herein without thereby limiting the scope of the invention. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the invention, which are all within the scope of the invention. Accordingly, the scope of protection of the present invention is to be determined by the appended claims.

Claims (10)

1. An electrolyte is characterized by comprising lithium salt, an organic solvent and an additive; the additive comprises an additive A and an additive B, wherein the additive A is a sulfonamide compound and/or a sulfinamide compound, and the additive B is a thiophene silicon nitrile compound;
the structural formula of the sulfinamide compound is shown as a formula I, and the structural formula of the sulfonamide compound is shown as a formula II:
Figure FDA0004003712170000011
wherein R1 to R4 are each independently selected from at least one of a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, an aryl group having 6 to 12 carbon atoms, an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, and an aryl group having 6 to 12 carbon atoms substituted with a cyano group or a halogen atom;
the structural formula of the thiophene silicon nitrile compound is shown as formula III:
Figure FDA0004003712170000012
wherein R5 to R6 are each independently selected from at least one of a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, an aryl group having 6 to 12 carbon atoms, an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, and an aryl group having 6 to 12 carbon atoms substituted with a cyano group or a halogen atom;
wherein R is at least one selected from the group consisting of an alkyl group having 0 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, an aryl group having 6 to 12 carbon atoms, an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, and an aryl group having 6 to 12 carbon atoms substituted with a cyano group or a halogen atom.
2. The electrolyte according to claim 1, wherein the sulfenamide compound is selected from at least one of the following compounds:
Figure FDA0004003712170000021
3. the electrolyte according to claim 1, wherein the sulfonamide compound is selected from at least one of the following compounds:
Figure FDA0004003712170000022
4. the electrolyte according to claim 1, wherein the thiophen silacrylic compound is selected from at least one of the following compounds:
Figure FDA0004003712170000031
5. the electrolyte of claim 1 wherein the additive further comprises at least one of vinylene carbonate, 1, 4-butane sultone, 1, 3-propene sultone, fluoroethylene carbonate, ethylene carbonate, vinyl sulfate, methylene methane disulfonate, succinonitrile, adiponitrile, 1,3, 6-hexanetrinitrile, 1,2, 3-tris (2-cyanooxy) propane, ethylene glycol bis (propionitrile) ether, tripropynyl phosphate (TPP).
6. The electrolyte according to claim 1, wherein the mass of the additive is 0.5 to 15wt% of the total mass of the electrolyte.
7. The electrolyte of claim 1 wherein the lithium salt comprises LiPF 6 、LiBF 4 、LiClO 4 、LiFSI、LiTFSI、LiBOB、LiDFOB、LiFAP、LiSbF6、LiCF 3 SO 3 、LiN(SO 2 CF 3 ) 2 、LiN(SO 2 C 2 F 5 ) 2 、LiN(SO 2 CF 3 ) 2 、LiN(SO 2 C 4 F 9 ) 2 、LiC(SO 2 CF 3 ) 3 、LiPF 3 (C 3 F 7 ) 3 、LiB(CF 3 ) 4 And LiBF 3 (C 2 F 5 ) At least one of (a) and (b); the mass of the lithium salt is 8-20wt% of the total mass of the electrolyte.
8. The electrolyte according to claim 1, wherein the organic solvent is at least one of ethylene carbonate, propylene carbonate, diethyl carbonate, methylethyl carbonate, ethyl propionate, propyl propionate, ethyl acetate, ethyl n-butyrate, and γ -butyrolactone; the mass of the organic solvent is 50-90 wt% of the total mass of the electrolyte.
9. A lithium ion battery comprises a positive electrode, a negative electrode, a diaphragm and the electrolyte.
10. The lithium ion battery of claim 9, wherein the active material in the positive electrode includes, but is not limited to, liCoO 2 、LiNiO 2 、LiVO 2 、LiCrO 2 、LiMn 2 O 4 、LiCoMnO 4 、L i2 NiMn 3 O 8 、LiNi 0.5 Mn 1.5 O 4 、LiCoPO 4 、LiMnPO 4 、LiFePO 4 、LiNiPO 4 、LiCoFSO 4 、CuS 2 、FeS 2 、MoS 2 、NiS、TiS 2 At least one of (a) and (b); the active material in the negative electrode includes, but is not limited to, at least one of graphite, soft carbon, hard carbon, carbon fibers, mesophase carbon microspheres, silicon-based materials, tin-based materials, lithium titanate, or other metals capable of forming alloys with lithium; the separator includes, but is not limited to, polyethylene, polypropylene, polyvinylidene fluoride, aramid, polyethylene terephthalate, polytetrafluoroethylene, polyacrylonitrile, and polyamideAt least one of imine, polyamide, polyester and natural fiber.
CN202211637260.0A 2022-12-16 2022-12-16 Electrolyte and lithium ion battery comprising same Pending CN116190784A (en)

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