CN114497734A - High-voltage lithium ion battery electrolyte and lithium ion battery containing same - Google Patents

High-voltage lithium ion battery electrolyte and lithium ion battery containing same Download PDF

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Publication number
CN114497734A
CN114497734A CN202111584309.6A CN202111584309A CN114497734A CN 114497734 A CN114497734 A CN 114497734A CN 202111584309 A CN202111584309 A CN 202111584309A CN 114497734 A CN114497734 A CN 114497734A
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ion battery
lithium ion
electrolyte
lithium
carbonate
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肖兴立
陈吉
李红
杨海秀
王林海
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Guangdong Biwo New Energy Co ltd
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Guangdong Biwo New Energy 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
    • H01M10/0567—Liquid materials characterised by the additives
    • 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
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/4235—Safety or regulating additives or arrangements in electrodes, separators or electrolyte

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Inorganic Chemistry (AREA)
  • Materials Engineering (AREA)
  • Secondary Cells (AREA)

Abstract

The invention discloses a high-voltage lithium ion battery electrolyte and a lithium ion battery containing the electrolyte. According to the invention, the trimethylsilyl-1, 3-heterocyclic thiopentane derivative is added into the lithium ion battery electrolyte, and because the trimethylsilyl-1, 3-heterocyclic thiopentane derivative contains B, S, O and other elements and an S ═ O double bond structure, when the derivative is used as an electrolyte additive of the lithium ion battery, compared with the electrolyte without the additive, a thinner protective film is formed on the surface of a positive electrode material, the structure is stable, the impedance is smaller, the electrolyte can be inhibited from being subjected to oxidative decomposition in subsequent circulation and the structure of the positive electrode material is damaged, an electrode/electrolyte interface is stabilized, and the circulation stability of the high-voltage lithium ion battery is finally improved.

Description

High-voltage lithium ion battery electrolyte and lithium ion battery containing same
Technical Field
The invention relates to the technical field of lithium ion batteries, in particular to a lithium ion battery electrolyte and a lithium ion battery containing the electrolyte.
Technical Field
Energy and environment are two serious problems that human beings must face in the 21 st century, and the continuous development of new energy and clean renewable energy is an important basis for the sustainable development of human society. In recent years, lithium ion batteries in the world and China are rapidly developed and widely applied to household electrical appliances. Conventional automobiles are subject to a shortage of petroleum supply and environmental pollution, and electric automobiles will alleviate or partially solve these problems. The lithium ion battery can be used as a main power source of an electric vehicle with excellent performance, and can quickly occupy the market. At present, the holding capacity of electric automobiles in the market shows an exponential rising trend, and the rapid development of lithium ion batteries is promoted.
The market determines the demand, and along with the large-scale application of the lithium ion battery, the improvement of the performance of the lithium ion battery is the key and difficult point of the current scientific research. At present, the use voltage of the lithium ion battery is lower, the energy density still needs to be improved, and the main ways of improving the energy density comprise using positive and negative electrode active materials with high specific capacity and improving the working voltage of the lithium ion battery. Under high voltage, the oxidation of the lithium ion battery anode active material is increased, so that the electrolyte is easier to decompose, a large amount of byproducts are generated and deposited on the surface of the anode material, the impedance is increased, and the performance of the lithium ion battery is rapidly reduced.
The electrolyte additive can be used for effectively improving the working voltage of the lithium ion battery. By adding the high-voltage additive into the electrolyte, the additive can form a thin and stable SEI film on the surface of the positive electrode material in the circulation process, so that the oxidative decomposition of the electrolyte on the surface of the positive electrode material is inhibited. The SEI film formed by the traditional high-voltage additive is thicker, the impedance of the lithium ion battery is improved, the interface impedance is increased, and the improvement effect cannot be effectively achieved, so that the development of the high-efficiency high-voltage lithium ion battery electrolyte additive has practical significance.
Disclosure of Invention
Aiming at the difficulties existing in the technical background, the invention provides a high-voltage lithium ion battery electrolyte, wherein a trimethylsilyl-1, 3-heterocyclic sulfur cyclopentane derivative additive is added into the lithium ion battery electrolyte, and because the additive contains multiple elements and S ═ O bonds, when the additive is used as the lithium ion battery electrolyte additive, compared with the electrolyte without the additive, a thinner protective film is formed on the surface of a positive electrode material, the structure is stable, the impedance is smaller, the electrolyte can be inhibited from being subjected to oxidative decomposition and damage to the structure of the positive electrode material in the subsequent circulation, the electrode/electrolyte interface is stabilized, and the circulation stability of the high-voltage lithium ion battery is finally improved.
In order to achieve the purpose, the invention adopts the following technical scheme:
a high-voltage lithium ion battery electrolyte comprises lithium salt, an organic solvent, an additive and a trimethylsilyl-1, 3-heterocyclic sulfur cyclopentane derivative additive, wherein the structural general formula of the trimethylsilyl-1, 3-heterocyclic sulfur cyclopentane derivative additive is as follows:
Figure BDA0003424738500000021
wherein R is a substituent group and is H, halogen, -CH3CN, cycloalkyl.
Further, based on the total mass of the high-voltage lithium ion battery electrolyte, the mass fraction of the lithium salt is 8-15%, the mass fraction of the additive is 0.1-10%, the mass fraction of the 1,3, 2-dioxathiacyclopentyl derivative additive is 0.1-3%, and the balance is the organic solvent.
Further, the lithium salt is one or more of lithium hexafluorophosphate, lithium difluorophosphate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium perchlorate, lithium bis (oxalato) borate, lithium difluoro (oxalato) borate, lithium bis (trifluoromethylsulfonyl) imide and lithium bis (fluorosulfonato) imide.
Further, the organic solvent is organic ester C1-10One or more of alkyl ethers, cyclic ethers, sulfones, dinitriles and ionic liquids.
Further, the organic ester is at least one of ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, dipropyl carbonate, methyl ethyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, 1, 4-butyrolactone, methyl formate, ethyl acetate, methyl propionate, ethyl propionate, butyl propionate and ethyl butyrate; said C is1-10The alkyl ether is at least one of dimethyl ether, diethyl ether and methyl ethyl ether; the dinitrile is adiponitrile, succinonitrile,At least one of glutaronitriles; the sulfones are at least one of dimethyl sulfoxide and sulfolane; the ionic liquid is at least one of imidazole and pyrrole ionic liquids.
Further, the additive is one or more of butyl sultone, ethylene sulfate, ethylene sulfite, pyridine, furan, thiophene, methyl ethylene carbonate, nitriles, sulfones and amides.
Preferably, the additive accounts for 0.01-3% of the total mass of the electrolyte.
Preferably, the organic solvent accounts for 65-85% of the total mass of the electrolyte.
Preferably, the lithium salt accounts for 10-15% of the total mass of the electrolyte.
Preferably, the trimethylsilyl-1, 3-heterocyclic sulfur cyclopentane derivative additive accounts for 0.5-3% of the total mass of the electrolyte.
Another object of the invention is to provide a lithium ion battery comprising a battery electrolyte.
Compared with the prior art, the invention has the following beneficial effects:
1. the trimethylsilyl-1, 3-heterocyclic sulfur cyclopentane derivative additive is used in the invention, the addition amount is less, and the performance of the lithium ion battery can be improved efficiently. Because the additive contains various elements such as B, S, O, F and the like and an S ═ O double bond structure, a stable SEI film can be formed on the surface of the cathode material in the circulation process, and compared with the SEI film formed by the conventional high-voltage additive, the SEI film is thinner, the impedance is lower, and the performance of the lithium ion battery is more optimized.
2. The lithium ion battery electrolyte has good compatibility with positive and negative electrode materials, and has excellent cycle performance and coulombic efficiency.
Detailed Description
Example 1
The preparation steps of the trimethylsilyl-1, 3-heterocyclic sulfur cyclopentane derivative additive are as follows:
with sulfuryl chloride and HMDS4And boric acid as raw materials, sequentially adding into a three-neck flask provided with an electric stirrer, a reflux condenser tube and a thermometer, and stirringReacting at the temperature of 80 ℃ for 10h, taking liquid phase samples at intervals of 2h, measuring by using a gas chromatograph, cooling to room temperature after the reaction is finished, filtering to obtain solid substances, purifying the clear filtrate by adopting a reduced pressure distillation method, and collecting the fraction at the temperature of 78-80 ℃ to obtain the product.
Preparing an electrolyte 1 sample, which comprises the following specific steps:
in an argon glove box with the water content less than or equal to 10ppm, Ethylene Carbonate (EC) and methyl ethyl carbonate (EMC) are mixed according to the mass ratio of EC to EMC of 3: 7, uniformly mixing to obtain an organic solvent, slowly adding lithium hexafluorophosphate into the organic solvent, adding vinylene carbonate and a compound (trimethylsilyl-1, 3-heterocyclic thiocyclopentane derivative additive) with a structural formula (1) after the lithium hexafluorophosphate is completely dissolved, and uniformly stirring to obtain the electrolyte 1, wherein the usage amounts of the lithium hexafluorophosphate, the organic solvent, the vinylene carbonate and the trimethylsilyl-1, 3-heterocyclic thiocyclopentane derivative additive are respectively 10%, 85%, 3% and 2% of the total mass of the electrolyte.
The experimental cell 1 sample was prepared by the following specific steps:
the method comprises the following steps of mixing a positive electrode active material (NMC811), a conductive agent acetylene black and a binder polyvinylidene fluoride according to a mass ratio of NMC 811: acetylene black: mixing polytetrafluoroethylene (95: 3: 2), adding NMP after mixing, fully stirring and uniformly mixing to obtain positive electrode slurry, uniformly coating the positive electrode slurry on an aluminum foil with the thickness of 15 mu m, and drying to obtain a positive electrode plate; the method comprises the following steps of mixing a negative electrode active material (graphite), a conductive agent acetylene black, a binder CMC and a plasticizer SBR according to the mass ratio of graphite: acetylene black: CMC: and mixing SBR (styrene butadiene rubber) 95:2:2:1, fully stirring and uniformly mixing to obtain negative electrode slurry, uniformly coating the negative electrode slurry on a copper foil with the thickness of 9 mu m, and drying to obtain the negative electrode sheet. Manufacturing a laminated battery containing soft packages in a dry environment with the dew point temperature of below-40 ℃, stacking a positive plate, a diaphragm and a graphite negative plate in sequence, ensuring that the diaphragm completely separates the positive plate from the negative plate, packaging and welding a tab by using an aluminum plastic film to form the battery to be injected with liquid, baking the moisture content of the battery to be below 300ppm before the liquid injection, injecting electrolyte 1, sealing, forming and grading to obtain the experimental battery 1.
Figure BDA0003424738500000061
Example 2
An electrolyte 2 and an experimental cell 2 were prepared as in example 1, except that the additives added to the electrolyte 2 were vinylene carbonate and a compound of formula (2) (trimethylsilyl-1, 3-thiacyclopentane derivative additive), wherein the mass percentages of lithium hexafluorophosphate, organic solvent, vinylene carbonate, trimethylsilyl-1, 3-thiacyclopentane derivative additive were 10%, 85%, 3%, and 2%, respectively.
Figure BDA0003424738500000062
Example 3
An electrolyte 3 and an experimental cell 3 were prepared as in example 1, except that the additives added to the electrolyte 3 were vinylene carbonate and a compound of formula (3) (trimethylsilyl-1, 3-thiacyclopentane derivative additive), wherein the mass percentages of lithium hexafluorophosphate, organic solvent, vinylene carbonate, trimethylsilyl-1, 3-thiacyclopentane derivative additive were 10%, 85%, 3%, and 2%, respectively.
Figure BDA0003424738500000071
Example 4
An electrolyte 4 and an experimental cell 4 were prepared as in example 1, except that the additives added to the electrolyte 4 were vinylene carbonate and a compound of formula (3) (trimethylsilyl-1, 3-thiacyclopentane derivative additive), wherein the mass percentages of lithium hexafluorophosphate, organic solvent, vinylene carbonate, trimethylsilyl-1, 3-thiacyclopentane derivative additive were 11%, 85%, 3%, 1%, respectively.
Comparative example 1
An electrolyte 5 and an experimental battery 5 were prepared as in example 1, except that the additive added to the electrolyte 5 was vinylene carbonate, wherein the mass percentages of lithium hexafluorophosphate, the organic solvent, and vinylene carbonate were 10%, 85%, and 5%, respectively.
Comparative example 2
An electrolyte 6 and an experimental battery 6 were prepared as in example 1, except that the additives added to the electrolyte 6 were vinylene carbonate and ethylene sulfate, wherein the lithium hexafluorophosphate, the organic solvent, the vinylene carbonate and the lithium bis (oxalato) borate were 10%, 85%, 3% and 2% by mass, respectively.
The compositions and contents of the electrolytes of examples 1 to 4 and comparative examples 1 to 2 are shown in table 1.
TABLE 1 electrolyte composition
Figure BDA0003424738500000081
The batteries prepared in examples 1 to 4 and comparative examples 1 to 2 described above were subjected to a cycle performance test and an EIS impedance test, respectively.
1. Cycle performance test
Under the high-temperature test condition of 45 ℃, the lithium ion batteries of the electrolytes 1 to 6 are respectively charged at 0.5C and discharged at 1C to carry out charge-discharge cycle performance test, the voltage setting interval is 3.0v to 4.2v, the cycle number is 300 weeks, and the capacity retention rate is recorded.
2. EIS impedance test
And (3) fully charging the lithium ion batteries with the electrolytes 1-6 after capacity grading, testing an impedance curve graph of a fresh battery by using an EIS impedance tester, and calculating the impedance R of a battery interface film by an equivalent circuit fitting method, wherein the testing frequency range is 0.01-10kHz, and the disturbance voltage is set to be 10 mV.
The test results are shown in table 2.
Table 2 experimental battery performance testing
Figure BDA0003424738500000082
Figure BDA0003424738500000091
According to the experimental data results, the following results are obtained:
1. it is understood from the interfacial resistance of examples 1 to 4 and comparative example 2 that the battery added with trimethylsilyl-1, 3-thiacyclopentane derivative additive has lower resistance and thinner SEI film than the conventional high voltage additive, and can efficiently improve the cycle performance of the lithium ion battery.
2. From the capacity retention rates of examples 1-4 and comparative examples 1-2, it can be seen that the battery with the trimethylsilyl-1, 3-thiacyclopentane derivative additive exhibits more excellent capacity retention rate after 300 weeks of cycling at 45 ℃, which is more stable than the formed SEI film and can allow the rapid transmission of lithium ions.
In conclusion, the additive of the invention has application advantages over single film forming additive or traditional high voltage additive schemes, has lower film forming resistance, and simultaneously significantly improves the high temperature cycle performance under high voltage conditions.

Claims (7)

1. A high voltage lithium ion battery electrolyte comprising a lithium salt, an organic solvent, an additive and a trimethylsilyl-1, 3-thiacyclopentane derivative additive, characterized in that: the structural general formula of the trimethylsilyl-1, 3-heterocyclic sulfur cyclopentane derivative additive is shown as follows:
Figure FDA0003424738490000011
wherein R is a substituent group and is H, halogen, -CH3CN, cycloalkyl.
2. The high voltage lithium ion battery electrolyte of claim 1, wherein: based on the total mass of the lithium ion battery electrolyte, the mass fraction of the lithium salt is 8-15%, the mass fraction of the additive is 0.1-12%, the mass fraction of the trimethylsilyl-1, 3-heterothiocyclopentane derivative additive is 0.1-6%, and the balance is the organic solvent.
3. The high voltage lithium ion battery electrolyte of claim 1, wherein: the lithium salt is one or more of lithium hexafluorophosphate, lithium difluorophosphate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium perchlorate, lithium bis (oxalato) borate, lithium difluoro (oxalato) borate, lithium bis (trifluoromethylsulfonyl) imide and lithium bis (fluorosulfonato) imide.
4. The high voltage lithium ion battery electrolyte of claim 1, wherein: the organic solvent is organic ester C1-10One or more of alkyl ethers, cyclic ethers, sulfones, dinitriles and ionic liquids.
5. The high voltage lithium ion battery electrolyte of claim 4 wherein: the organic esters are at least one of ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, dipropyl carbonate, methyl ethyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, 1, 4-butyrolactone, methyl formate, ethyl acetate, methyl propionate, ethyl propionate, butyl propionate and ethyl butyrate; said C is1-10The alkyl ether is at least one of dimethyl ether, diethyl ether and methyl ethyl ether; the dinitrile is at least one of adiponitrile, succinonitrile and glutaronitrile; the sulfones are at least one of dimethyl sulfoxide and sulfolane; the ionic liquid is at least one of imidazole and pyrrole ionic liquids.
6. The high voltage lithium ion battery electrolyte of claim 1 wherein: the additive is at least one of vinylene carbonate, fluoroethylene carbonate, difluoroethylene carbonate, 1, 3-propylene sultone, 1, 3-propane sultone, ethylene sulfate and methylene methanedisulfonate.
7. A lithium ion battery, characterized by: the electrolyte comprises a positive electrode material, a negative electrode material, a separator and the electrolyte according to any one of claims 1 to 6.
CN202111584309.6A 2021-12-21 2021-12-21 High-voltage lithium ion battery electrolyte and lithium ion battery containing same Pending CN114497734A (en)

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Application publication date: 20220513