CN117594875A - Electrolyte additive, electrolyte, battery and electricity utilization device - Google Patents

Electrolyte additive, electrolyte, battery and electricity utilization device Download PDF

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Publication number
CN117594875A
CN117594875A CN202311334531.XA CN202311334531A CN117594875A CN 117594875 A CN117594875 A CN 117594875A CN 202311334531 A CN202311334531 A CN 202311334531A CN 117594875 A CN117594875 A CN 117594875A
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electrolyte
additive
lithium
battery
positive electrode
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岳玉娟
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Jiujiang Tinci Advanced Materials Co ltd
Guangzhou Tinci Materials Technology Co Ltd
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Jiujiang Tinci Advanced Materials Co ltd
Guangzhou Tinci Materials Technology 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
    • H01M10/05—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
    • 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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  • Chemical & Material Sciences (AREA)
  • 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 application discloses electrolyte additive, electrolyte, battery, power consumption device, electrolyte additive includes first additive and first lithium salt, first additive includes tetraethylsilane, first lithium salt includes tetrafluoro oxalic acid lithium phosphate. Thus, the electrolyte containing the electrolyte additive can improve the rate performance and high temperature performance of the battery.

Description

Electrolyte additive, electrolyte, battery and electricity utilization device
Technical Field
The application relates to the technical field of batteries, in particular to an electrolyte additive, an electrolyte, a battery and an electric device.
Background
With the emphasis of people on the problem of exhaustion of non-renewable energy sources and environmental pollution, renewable clean energy sources are rapidly developed. The lithium ion battery has the advantages of high specific energy, long cycle life, small self discharge and the like, and is widely applied to consumer electronic products and energy storage and power batteries. Typically, a battery includes a positive electrode tab, a negative electrode tab, an electrolyte, and a separator. The electrolyte of the lithium ion battery consists of a solvent, electrolyte lithium salt and electrolyte additives. The electrolyte additive is added into the electrolyte, so that the high-temperature cycle performance, overcharge performance and the like of the battery can be effectively improved. However, current electrolyte additives still have some problems during practical application.
It should be noted that the foregoing statements are merely to provide background information related to the present application and may not necessarily constitute prior art.
Disclosure of Invention
In a first aspect of the present application, the present application proposes an electrolyte additive comprising a first additive comprising tetraethylsilane and a first lithium salt comprising lithium tetrafluorooxalate phosphate. Thus, the electrolyte containing the electrolyte additive can improve the rate performance and high temperature performance of the battery.
In some embodiments, the mass fraction of the tetraethylsilane in the electrolyte additive is a, the mass fraction of the lithium tetrafluorooxalate phosphate in the electrolyte additive is b, and a/b is 0.1-5. Thereby, the rate performance and high temperature performance of the battery containing the electrolyte additive can be further improved.
In some embodiments, further comprising: and the second additive comprises at least one of a high-temperature additive, a negative electrode film-forming additive, a lithium salt additive and a water and acid removal additive. Thereby, the rate performance, high temperature performance, and cycle life of the battery containing the electrolyte additive can be improved.
In some embodiments, the second additive satisfies at least one of the following conditions: the high-temperature additive comprises at least one of 1, 3-propane sultone, 1, 3-propylene sultone, ethylene sulfate and ethylene sulfite; the negative electrode film-forming additive comprises at least one of ethylene carbonate, fluoroethylene carbonate and ethylene carbonate; the lithium salt additive comprises at least one of lithium bisoxalato borate, lithium difluorooxalato borate, lithium difluorodioxaato phosphate, lithium tetrafluoroborate, lithium bistrifluoromethylsulfonyl imide, lithium bis (pentafluoroethylsulfonyl) imino, lithium trifluoromethane sulfonate and lithium difluorophosphate; the water and acid removal additive comprises at least one of tri (trimethylsilane) borate and tri (trimethylsilane) phosphate. Thereby, the rate performance, high temperature performance, and cycle life of the battery containing the electrolyte additive can be further improved.
In some embodiments, the first additive further comprises tetravinylsilane. Thereby, the rate performance of the battery containing the electrolyte additive can be improved.
In a second aspect of the present application, the present application provides an electrolyte comprising the foregoing electrolyte additive. Thus, the electrolyte has all the features and advantages of the electrolyte additives described above and will not be described in detail herein.
In some embodiments, further comprising: a solvent and an electrolyte lithium salt comprising at least one of lithium hexafluorophosphate, lithium bis-fluorosulfonimide. Thereby, the conductivity and stability of the electrolyte can be improved.
In some embodiments, the electrolyte lithium salt in the electrolyte is 12% -18% by mass. Thereby, the ionic conductivity of the electrolyte can be improved.
In some embodiments, the solvent comprises at least one of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, methylethyl carbonate, ethyl propionate, propyl propionate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate. Thereby, the ionic conductivity of the electrolyte can be improved.
In some embodiments, the mass fraction of the solvent in the electrolyte is 50% -80%. Thereby, the ionic conductivity of the electrolyte can be further improved.
In some embodiments, the mass fraction of tetraethylsilane in the electrolyte is 0.1% -2%.
In some embodiments, the mass fraction of lithium tetrafluorooxalate phosphate in the electrolyte is 0.03% -3%; optionally, the mass fraction of the lithium tetrafluorooxalate phosphate in the electrolyte is 0.1% -2%. This improves the rate performance and high temperature performance of the battery containing the electrolyte.
In some embodiments, the mass fraction of the second additive in the electrolyte is 0.5% -3%. This improves the rate performance, high temperature performance, and cycle life of the battery containing the electrolyte.
In a third aspect of the present application, a battery is presented comprising the aforementioned electrolyte additive, or the aforementioned electrolyte.
In some embodiments, the lithium ion battery further comprises a positive electrode plate, wherein the positive electrode plate comprises a positive electrode current collector and a positive electrode active material layer positioned on at least one side surface of the positive electrode plate, the positive electrode active material layer comprises a positive electrode active material, and the mass fraction of nickel element in the positive electrode active material is greater than or equal to 40%. Thus, the gram capacity of the positive electrode active material can be increased, and the cost of the positive electrode active material can be reduced.
In some embodiments, the positive electrode active material satisfies the general formula Li a Ni b Co c M1 d M2 e O f R g Wherein a is more than or equal to 1 and less than or equal to 1.2,0.6<b<1，0<c<1，0<d<1.0.ltoreq.e.ltoreq.0.2, b+c+d+e.ltoreq.1, f.ltoreq.2, 0.ltoreq.g.ltoreq.1, f+g.ltoreq.2; m1 comprises Mn and/or Al, M2 comprises at least one of Zr, zn, cu, cr, mg, fe, V, ti, sr, sb, Y, W, nb, and R comprises at least one of N, F, S, cl. Thus, the gram capacity of the positive electrode active material can be further increased, and the cost of the positive electrode active material can be reduced.
In some embodiments, the positive electrode active material includes LiNi 0.7 Co 0.1 Mn 0.2 O 2 、LiNi 0.8 Co 0.1 Mn 0.1 O 2 、LiNi 0.8 Co 0.15 Al 0.05 O 2 、LiNi 0.9 Co 0.05 Mn 0.05 O 2 At least one of them. Thus, the gram capacity of the positive electrode active material can be further increased, and the cost of the positive electrode active material can be reduced.
In a fourth aspect of the present application, the present application proposes an electrical device comprising the aforementioned battery. Therefore, the power utilization device has all the characteristics and advantages of the battery and is not described in detail herein.
Detailed Description
Embodiments of the present application, examples of which are described below, are described in detail, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The following examples are illustrative only and are not to be construed as limiting the present application.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used in the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application; unless otherwise indicated, the numerical values of the parameters set forth in this application may be measured by various measurement methods commonly used in the art (e.g., may be tested according to the methods set forth in the examples of this application).
The terms "comprising" and "having" and any variations thereof in the description and claims of the present application are intended to be open-ended, i.e., to include the material indicated herein, but not to exclude other aspects.
In the description of the present application, all numbers disclosed herein are approximate, whether or not words of "about" or "about" are used. The numerical value of each number may vary by less than 10% or reasonably as considered by those skilled in the art, such as 1%, 2%, 3%, 4% or 5%.
In the description of the present application, the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. The "first feature" and "second feature" may include one or more of the features.
In the description of the present application, "a and/or B" may include any of the cases of a alone, B alone, a and B, wherein A, B is merely for example, which may be any technical feature of the present application using "and/or" connection.
The electrolyte additive is used in an amount that is only a small fraction of the electrolyte in a lithium ion battery, but a suitable amount of additive is capable of forming an SEI (Solid Electrolyte Interface, solid electrolyte interface film) on the surface of the negative active material and a CEI (Cathode ElectrolyteInterface Interface, positive electrode-electrolyte interface film) on the surface of the positive active material. SEI and CEI are respectively formed on the surfaces of the anode active material and the cathode active material, so that the problem that side reactions occur after the active material is directly contacted with electrolyte is solved. The existing SEI film and CEI film have the problems of uneven film thickness, poor film structure stability, easy damage in the charge-discharge cycle process of the battery, and the like.
The positive electrode active material undergoes irreversible phase change during the charge and discharge of the battery, and thus causes defects such as transition metal dissolution and microcrack generation of the positive electrode active material. When the charge current of the battery is large or stored in an environment with a high temperature, the temperature of the battery system may increase. When the CEI film forming on the surface of the positive electrode active material is unstable, cracking of the CEI film is easy to occur under a high-temperature environment, and further, dissolution of transition metals in the positive electrode active material is further aggravated under the high-temperature condition. In addition, after the CEI film on the surface of the positive electrode active material is cracked, electrolyte can permeate into the surface of the positive electrode active material and the inside of the positive electrode active material with microcracks, so that the positive electrode active material is in direct contact with the electrolyte and reacts with the electrolyte, and oxidative decomposition of the electrolyte is accelerated. The continuous side reaction of the positive active material with the electrolyte may cause a large loss of active lithium, causing rapid capacity fade of the battery, and deteriorating high temperature performance of the battery. The high-temperature cycle performance and the high-temperature storage performance of the battery can be effectively improved by selecting the additive with better CEI film forming stability.
An additive for forming a relatively stable CEI film on the surface of an anode active material can form an SEI film on the surface of a cathode active material, but the additive can increase the impedance of the SEI film, so that the lithium ions are difficult to be inserted into and extracted from the cathode active material, and the rate performance of a battery is influenced. By using the additive together with other additives for improving SEI film impedance, the effect of forming a stable CEI film at high temperature on the surface of the positive electrode active material and simultaneously forming a SEI film with smaller impedance on the surface of the negative electrode active material can be realized.
In the application, by adopting the electrolyte additive containing the tetraethyl silane and the lithium tetrafluorooxalate phosphate, the uniform and firm CEI film and SEI film are respectively formed on the surfaces of the positive electrode active material and the negative electrode active material in situ by utilizing the cooperative use of the tetraethyl silane and the lithium tetrafluorooxalate phosphate, and the electrolyte additive can be effectively improved for inhibiting side reactions in the electrolyte, improving the migration rate of lithium ions and the like, and is beneficial to the battery adopting the electrolyte additive to show excellent high-temperature cycle performance, high-temperature storage performance and multiplying power performance.
Specifically, by adopting lithium tetrafluorooxalate phosphate with higher fluorine content as an electrolyte additive, the LiF content in the CEI film can be effectively improved. Compared with a CEI film rich in organic matters, the CEI film rich in inorganic LiF is not easy to oxidize under high voltage, bonding between the CEI film rich in LiF and a positive electrode active material containing transition metal is weak, and strain/stress born in the process of volume change of the positive electrode active material is small, so that the CEI film can keep high structural stability, is not easy to crack under high temperature conditions, and high-temperature cycle performance and high-temperature storage performance of a battery are effectively improved.
Further, when lithium tetrafluorooxalate phosphate with higher fluorine content is used as an electrolyte additive, the SEI film on the surface of the anode active material has larger thickness and non-uniform film formation, and more free hydrogen can be combined, so that hydrogen fluoride is generated, the stability of an anode interface is poor, the gas production of a battery is serious, and hydrogen fluoride can be consumed by adding tetraethyl silane, so that the defect of larger SEI film and non-uniform film formation is effectively improved, the SEI film with moderate film thickness and higher film formation uniformity is formed, the lithium ions can be conveniently inserted into and separated from the anode active material, and the rate capability of the battery is effectively improved.
In a first aspect of the present application, the present application proposes an electrolyte additive comprising a first additive comprising tetraethylsilane and a first lithium salt comprising lithium tetrafluorooxalate phosphate. When the electrolyte contains the electrolyte additive, by utilizing the synergistic use of the tetraethyl silane and the lithium tetrafluorooxalate phosphate, uniform and firm CEI films and SEI films can be respectively formed on the surfaces of the positive electrode active material and the negative electrode active material in situ, and the rate capability, the high-temperature cycle performance and the high-temperature storage performance of the battery are effectively improved.
In some embodiments, the electrolyte additive has a mass fraction of tetraethylsilane of a and the electrolyte additive has a mass fraction of lithium tetrafluorooxalate phosphate of b, a/b being 0.1-5.
As examples, a/b may be 0.1, 0.2, 0.5, 0.8, 1, 1.1, 1.2, 1.5, 1.8, 2, 2.1, 2.2, 2.5, 2.8, 3, 3.1, 3.2, 3.5, 3.8, 4, 4.1, 4.2, 4.5, 4.8, or 5.
Through the reasonable proportion of the tetraethyl silane and the lithium tetrafluorooxalate phosphate, the uniform and firm formation of CEI films and SEI films aiming at different battery systems can be realized.
In some embodiments, further comprising: the second additive comprises at least one of a high-temperature additive, a negative electrode film-forming additive, a lithium salt additive and a water and acid removal additive.
The rate performance, high temperature cycle performance, and cycle life of the battery containing the electrolyte additive can be improved by the addition of the second additive.
In some embodiments, the high temperature additive includes at least one of 1, 3-Propane Sultone (PS), 1, 3-Propene Sultone (PST), ethylene sulfate (DTD), ethylene Sulfite (ES).
The high temperature resistance of the electrolyte can be improved by adding the high temperature additive.
In some embodiments, the negative film-forming additive includes at least one of Vinylene Carbonate (VC), fluoroethylene carbonate (FEC), ethylene carbonate (VEC).
The film formation of SEI can be improved by adding the negative electrode film forming additive, and the film formation uniformity of SEI is improved.
In some embodiments, the lithium salt additive includes lithium bis (oxalato) borate (LiBOB), lithium difluoro (LiODFB), lithium difluoro (LiODFP) oxalato phosphate, lithium tetrafluoroborate, lithium bis (trifluoromethylsulfonyl) imide, lithium bis (pentafluoroethylsulfonyl) imide, lithium trifluoromethylsulfonate, lithium difluoro (LiPO) 2 F 2 ) At least one of them.
The solubility of lithium salt in the electrolyte can be improved by adding the lithium salt additive, the stability of the electrolyte under the high-temperature condition is improved, the ionic conductivity of the electrolyte is improved, the hydrolysis of the electrolyte under the water-containing condition is reduced, and the oxidation of the electrolyte is inhibited.
In some embodiments, the water and acid removal additive comprises at least one of tris (trimethylsilane) borate (TMSB), tris (trimethylsilane) phosphate (TMSP).
The addition of the water removal and acid removal additive can react with water and acidic substances in the electrolyte, such as hydrofluoric acid and the like, reduce the influence of the water and/or the acidic substances on the stability of the electrolyte, and can also participate in the film formation of SEI and CEI after water removal and acid removal.
In some embodiments, the first additive further comprises a tetravinylsilane.
The tetravinyl silane can be subjected to polymerization reaction on the surfaces of the positive electrode active material and the negative electrode active material to generate an oligomer, so that the oligomer is coated on the surface of the active material, and the structural stability of the SEI film and the CEI film is further improved.
In a second aspect of the present application, the present application provides an electrolyte comprising the foregoing electrolyte additive. Thus, the electrolyte has all the features and advantages of the electrolyte additives described above and will not be described in detail herein.
In some embodiments, further comprising: a solvent and an electrolyte lithium salt, wherein the electrolyte lithium salt comprises at least one of lithium hexafluorophosphate and lithium bis-fluorosulfonyl imide.
The solvent is a main component of the electrolyte, which should have a high solubility of lithium salt so that the electrolyte has a high ionic conductivity.
The electrolyte lithium salt can release lithium ions after being dissolved in an electrolyte solvent, and the lithium ions and the electrolyte form a solvation structure, so that the rapid migration of the lithium ions is facilitated.
In some embodiments, the mass fraction of electrolyte lithium salt in the electrolyte is 12% -18%.
As an example, the mass fraction of electrolyte lithium salt in the electrolyte may be 12%, 12.5%, 13%, 13.5%, 14%, 14.5%, 15%, 15.5%, 16%, 16.5%, 17%, 17.5% or 18%.
When the mass fraction of the electrolyte lithium salt in the electrolyte is within the above range, the electrolyte lithium salt can be sufficiently dissolved in the electrolyte solvent, and the electrolyte has high ionic conductivity and low manufacturing cost.
In some embodiments, the solvent may include at least one of Ethylene Carbonate (EC), propylene Carbonate (PC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl Methyl Carbonate (EMC), ethyl propionate, propyl propionate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate.
The solvent in the electrolyte is used as an important carrier for ion transmission, and the electrolyte lithium salt can have higher electronic conductivity after being dissolved, so that the cycle life, the charge-discharge multiplying power, the high-low temperature performance and the energy density of the battery can be improved by selecting the solvent.
In some embodiments, the mass fraction of solvent in the electrolyte is 50% -80%.
As an example, the mass fraction of solvent in the electrolyte may be 55%, 57%, 60%, 63%, 65%, 67%, 70%, 73%, 75%, 77%, or 80%.
In some embodiments, the mass fraction of tetraethylsilane in the electrolyte is 0.1% -2%.
As an example, the mass fraction of tetraethylsilane in the electrolyte may be 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9% or 2.0%.
When the mass fraction of the tetraethyl silane in the electrolyte is 0.1% -2%, the content of the tetraethyl silane is moderate, CEI film formation is relatively sufficient, the thickness is moderate, SEI film formation resistance and overall DCR are low, the residual tetraethyl silane after formation film formation consumption is less, and the tetraethyl silane is not easy to decompose and produce gas under the later high-temperature condition, so that the battery performance is degraded.
In some embodiments, the mass fraction of lithium tetrafluorooxalate phosphate in the electrolyte is 0.03% -3%.
As an example, the mass fraction of tetraethylsilane in the electrolyte may be 0.03%, 0.05%, 0.07%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2.0%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, or 3.0%.
When the mass fraction of lithium tetrafluorooxalate phosphate in the electrolyte is 0.03% -3%, the lithium tetrafluorooxalate phosphate is helpful to form a CEI film rich in LiF, and has less adverse effect on SEI film formation, meanwhile, the residual amount of lithium tetrafluorooxalate phosphate after the consumption of the formation stage is less, the generation of carbon dioxide gas caused by decomposition of oxalate contained in the lithium tetrafluorooxalate phosphate is reduced, and the degradation of the battery performance is reduced.
In some embodiments, the mass fraction of lithium tetrafluorooxalate phosphate in the electrolyte is 0.1% -2%.
In some embodiments, the mass fraction of the second additive in the electrolyte is 0.5% -3%.
As an example, the mass fraction of the second additive in the electrolyte may be 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2.0%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9% or 3.0%.
As an example, when the second additive includes a high temperature type additive, the mass fraction of the high temperature type additive in the electrolyte is 0 to 2%.
As an example, when the second additive includes a negative electrode film-forming additive, the mass fraction of the negative electrode film-forming additive in the electrolyte is 0.5% -3%.
As an example, when the second additive includes a lithium salt additive, the mass fraction of the lithium salt additive in the electrolyte is 0 to 1%.
As an example, when the second additive includes a water and acid removal additive, the mass fraction of the water and acid removal additive in the electrolyte is 0-1%.
In a third aspect of the present application, a battery is presented comprising the aforementioned electrolyte additive, or the aforementioned electrolyte.
Typically, a battery includes a positive electrode tab, a negative electrode tab, an electrolyte, and a separator. During the charge and discharge of the battery, active ions are inserted and extracted back and forth between the positive electrode plate and the negative electrode plate. The electrolyte plays a role in ion conduction between the positive electrode plate and the negative electrode plate. The isolating film is arranged between the positive pole piece and the negative pole piece, and mainly plays a role in preventing short circuit between the positive pole piece and the negative pole, and meanwhile ions can pass through the isolating film.
In some embodiments, the battery comprises a positive electrode sheet, the positive electrode sheet comprises a positive electrode current collector and a positive electrode active material layer positioned on at least one side surface of the positive electrode sheet, the positive electrode active material layer comprises a positive electrode active material, and the mass fraction of nickel element in the positive electrode active material is greater than or equal to 40%.
When the mass fraction of the nickel element in the positive electrode active material is within the above range, the cost of the positive electrode active material is low, and the gram capacity is remarkably improved. The positive electrode active material with higher nickel content has poor thermal stability, transition metal dissolution and microcrack generation at high temperature, and by adopting the electrolyte containing the electrolyte additive as the electrolyte of the high-nickel battery, a uniform and firm CEI film can be formed on the positive electrode active material in situ, and a uniform and firm SEI film can be formed on the surface of the negative electrode active material, so that the high-temperature cycle performance and the rate performance of the battery are effectively improved while the low cost and the high capacity are realized.
In some embodiments, the positive electrode active material satisfies the general formula Li a Ni b Co c M1 d M2 e O f R g Wherein a is more than or equal to 1 and less than or equal to 1.2,0.6<b<1，0<c<1，0<d<1.0.ltoreq.e.ltoreq.0.2, b+c+d+e.ltoreq.1, f.ltoreq.2, 0.ltoreq.g.ltoreq.1, f+g.ltoreq.2; m1 comprises Mn and/or Al, M2 comprises at least one of Zr, zn, cu, cr, mg, fe, V, ti, sr, sb, Y, W, nb, and R comprises at least one of N, F, S, cl.
In some embodiments, the positive electrode active material may be coated withInclude LiNi 0.7 Co 0.1 Mn 0.2 O 2 (NCM712)、LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811)、LiNi 0.8 Co 0.15 Al 0.05 O 2 、LiNi 0.9 Co 0.05 Mn 0.05 O 2 At least one of them. Thereby further improving gram capacity of the positive electrode active material and reducing cost of the positive electrode active material.
Li deintercalation and consumption of the battery occur during charge and discharge. When the battery is discharged to different states, the Li content of the positive electrode active material is also different. In the list of the positive electrode active materials in the present application, the molar content of Li is the initial state of the material, and when the positive electrode active material is applied to a battery and subjected to cyclic charge and discharge, the molar content of Li changes.
In the list of the positive electrode active materials in the application, the molar content of O is only a theoretical state value, and the lattice oxygen release of the positive electrode active material can cause the change of the molar content of oxygen in the cyclic charge and discharge process of the battery.
In some embodiments, the positive current collector may employ a metal foil or a composite current collector. For example, as the metal foil, aluminum foil may be used. The composite current collector may include a polymeric material base layer and a metal layer formed on at least one surface of the polymeric material base layer. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel alloy, titanium alloy, silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
In some embodiments, the positive electrode active material layer may further optionally include a binder. For example, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), a vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, a vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, a tetrafluoroethylene-hexafluoropropylene copolymer, and a fluoroacrylate resin.
In some embodiments, the positive electrode active material layer may further optionally include a conductive agent. For example, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.
In some embodiments, the negative electrode tab includes a negative electrode current collector and a negative electrode active material layer disposed on at least one surface of the negative electrode current collector, the negative electrode active material layer including a negative electrode active material. The negative active material may include at least one of artificial graphite, natural graphite, soft carbon, hard carbon, mesophase carbon microspheres, a silicon-based material, a tin-based material, and lithium titanate.
In some embodiments, the anode active material layer may further include a binder, a conductive agent, and other auxiliary agents. For example, the binder may include at least one of Styrene Butadiene Rubber (SBR), polyacrylic acid (PAA), sodium Polyacrylate (PAAs), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium Alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS); the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, single-walled carbon nanotubes, graphene, and carbon nanofibers; auxiliaries may include thickeners such as sodium carboxymethylcellulose (CMC-Na) and the like.
The type of the separator is not particularly limited, and any porous separator having good chemical stability and mechanical stability may be selected. For example, the material of the separator may include at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may be a single-layer film or a multilayer composite film.
The battery of the present application may include a battery cell form, a battery module form, and a battery pack form.
In some embodiments, the battery cells may be assembled into a battery module, and the number of battery cells included in the battery module may be one or more, and the specific number may be selected by one skilled in the art according to the application and capacity of the battery module.
In some embodiments, the battery modules may also be assembled into a battery pack, and the number of battery modules included in the battery pack may be one or more, and the specific number may be selected by one skilled in the art according to the application and capacity of the battery pack.
In a fourth aspect of the present application, the present application proposes an electrical device comprising the aforementioned battery. Therefore, the power utilization device has all the characteristics and advantages of the battery and is not described in detail herein.
The battery cell, the battery module, and the battery pack may be used as a power source of the electric device, and may also be used as an energy storage unit of the electric device. The power utilization device may include, but is not limited to, mobile devices (e.g., cell phones, notebook computers, etc.), electric vehicles (e.g., electric only vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, and the like.
As the electricity consumption device, a battery module, or a battery pack may be selected according to the use requirements thereof.
The electric device as an embodiment may be a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, or the like. To meet the high power and high energy density requirements of the power device for the battery, a battery pack or battery module may be employed.
The device as another embodiment may be a mobile phone, a tablet computer, a notebook computer, or the like. The device is generally required to be light and thin, and a battery cell can be used as a power supply.
The following description of the present application is made by way of specific examples, which are given for illustration only and should not be construed as limiting the scope of the present application. The examples are not to be construed as limiting the specific techniques or conditions described in the literature in this field or as per the specifications of the product. The reagents or apparatus used were conventional products commercially available without the manufacturer's attention.
Example 1
Preparing a positive electrode plate:
positive electrode active material NCM811, binder polyvinylidene fluoride (PVDF) and conductive agent acetylene blackMixing according to a weight ratio of 96.5:2:1.5, adding N-methyl pyrrolidone (NMP), and stirring under the action of a vacuum stirrer until the mixed system becomes anode slurry with uniform fluidity; uniformly coating the anode slurry on an aluminum foil with the thickness of 7 mu m; the aluminum foil coated with the positive electrode slurry was dried in an oven at 120 deg.c for 8 hours. Finally, rolling to control the compaction density of the positive pole piece to be 3.5g/cm 3 And cutting to obtain the positive pole piece.
Preparing a negative electrode plate:
mixing negative electrode active material artificial graphite, thickener sodium carboxymethylcellulose (CMC-Na), binder styrene-butadiene rubber, conductive agent acetylene black and conductive agent single-walled carbon nano tube according to the weight ratio of 95.9:1:2:1:0.1, adding deionized water, and obtaining negative electrode slurry under the action of a vacuum stirrer; uniformly coating the negative electrode slurry on a copper foil with the thickness of 6 mu m; the copper foil coated with the negative electrode slurry was dried at 85 ℃ for 5 hours. Finally, rolling to control the compaction density of the negative pole piece to be 1.5g/cm 3 And cutting to obtain the negative electrode plate.
Preparation of electrolyte:
in a glove box filled with argon (moisture)<10ppm, oxygen content<1 ppm), uniformly mixing a solvent EC, EMC and DEC according to a mass percentage of 3:5:2, and rapidly adding an electrolyte lithium salt LiPF with a mass percentage of 14.5% which is fully dried into the mixed solvent 6 And other additives, wherein the other additives comprise a first additive, a first lithium salt and a second additive, the substance types and mass fractions of the additives are shown in table 1, and the electrolyte is obtained by fully and uniformly mixing and uniformly stirring.
Preparation of a separation film:
polyethylene isolating film with thickness of 8 μm is selected.
Preparation of a lithium ion battery:
winding the prepared positive pole piece, the isolating film and the negative pole piece to obtain a bare cell without liquid injection; and placing the bare cell in an outer package, injecting the prepared electrolyte into the dried bare cell, and performing the procedures of vacuum packaging, standing, formation, shaping, sorting and the like to obtain the lithium ion battery.
Examples 2-20 differ from example 1 with specific reference to table 1, and comparative examples 1-6 differ from example 1 in that: the first additive and the first lithium salt are not added in comparative example 1, and the first additive in comparative example 2 adopts tetravinyl silane to replace tetraethyl silane; the first lithium salt in comparative example 3 uses lithium difluorodioxalate phosphate instead of lithium tetrafluorooxalate phosphate; in comparative example 4, the first additive was tetraethyl silane replaced with tetravinyl silane, and the first lithium salt was lithium difluorooxalate phosphate replaced with lithium tetrafluorooxalate phosphate; the first lithium salt was not added in comparative example 5; the first additive was not added in comparative example 6.
TABLE 1
Electrochemical performance tests were performed on the lithium ion batteries of examples 1 to 20 and comparative examples 1 to 6, and the test results are shown in table 2.
1. Storage test at 85 ℃): placing the battery in a 25 ℃ environment, discharging to a cut-off voltage of 2.75V according to a constant current of 1C, standing for 5min, charging to an upper limit voltage of 4.2V with a constant current and a constant voltage of 1C, and measuring the initial full-charge thickness of the battery to be d1 when the cut-off current is 0.05C; placing the battery in a high temperature box at 85 ℃ for standing for 4 hours, taking out and measuring the thickness d of the battery 2 The calculation formula is as follows:
thickness expansion ratio (%) =d 2 /d 1 ×100％
2. -20 ℃ EIS test: charging the battery to an upper limit voltage of 4.2V according to a constant current and a constant voltage of 1C, keeping the cut-off current at 0.05C, standing the full-charge battery at-20 ℃ for 10h, performing EIS test, setting the potential value to be open-circuit voltage, the sine voltage amplitude to be 1mV-10mV, the scanning frequency to be 0.1Hz-1000000Hz, performing fitting analysis on the data obtained by the test by adopting Z-view software, and obtaining the impedance R of the SEI film SEI Data.
3. Discharge direct current internal resistance test (DCR test): the battery is placed in an environment of 25 ℃ according to the following conditionsDischarging 1C constant current to cut-off voltage of 2.75V, standing for 5min, charging with 1C constant current and constant voltage to upper limit voltage of 4.2V, cutting-off current of 0.05C, discharging according to 1C constant current for 30min, standing for 5min at 25deg.C, discharging with 4C constant current for 30s, discharging current as I when 4C is discharged 4C . Record the initial voltage V 0 And voltage V after 30s discharge 1 . The discharge DC internal resistance at 50% SOC was calculated as follows:
DCR(mΩ)＝(V 0 -V 1 )/I 4C ×1000
4. 25 ℃ quick charge cycle test: placing the battery in an environment with the temperature of (25+/-2), standing for 3 hours, charging to the upper limit voltage of 4.2V according to the constant current and the constant voltage of 2C, keeping the cut-off current of 0.05C, standing for 5min after the battery is fully charged, discharging to the cut-off voltage of 2.75V by the constant current of 1C, and recording the highest discharge capacity of the previous 3 times of circulation as the initial capacity Q 1 When the cycle reached 500 turns, the last discharge capacity Q of the battery was recorded 2 . The calculation formula is as follows:
capacity retention (%) =q 2 /Q 1 ×100％
TABLE 2
It should be noted that the above embodiments are merely examples, and the present application is not limited to the above embodiments. Examples having substantially the same constitution and exhibiting the same effects as those of the technical idea within the scope of the present application are included in the technical scope of the present application. Various modifications, which can be made by those skilled in the art, or equivalent substitutions for some or all of the technical features thereof, may be made to the embodiments without departing from the spirit of the present application, and the essence of the corresponding technical solutions does not deviate from the scope of the technical solutions of the embodiments of the present application, and all such modifications or substitutions are intended to be included in the scope of the claims and the specification of the present application.
In addition, as long as there is no conflict between the embodiments, the technical features mentioned in the respective embodiments may be combined in any manner. The present application is not limited to the specific embodiments disclosed herein, but encompasses all technical solutions falling within the scope of the claims.

Claims (18)

1. An electrolyte additive comprising a first additive comprising tetraethylsilane and a first lithium salt comprising lithium tetrafluorooxalate phosphate.
2. The electrolyte additive according to claim 1, wherein the mass fraction of the tetraethylsilane in the electrolyte additive is a, and the mass fraction of the lithium tetrafluorooxalate phosphate in the electrolyte additive is b, and a/b is 0.1-5.
3. The electrolyte additive of claim 1, further comprising: and the second additive comprises at least one of a high-temperature additive, a negative electrode film-forming additive, a lithium salt additive and a water and acid removal additive.
4. The electrolyte additive of claim 3, wherein the second additive satisfies at least one of the following conditions:
the high-temperature additive comprises at least one of 1, 3-propane sultone, 1, 3-propylene sultone, ethylene sulfate and ethylene sulfite;
the negative electrode film-forming additive comprises at least one of ethylene carbonate, fluoroethylene carbonate and ethylene carbonate;
the lithium salt additive comprises at least one of lithium bisoxalato borate, lithium difluorooxalato borate, lithium difluorodioxaato phosphate, lithium tetrafluoroborate, lithium bistrifluoromethylsulfonyl imide, lithium bis (pentafluoroethylsulfonyl) imino, lithium trifluoromethane sulfonate and lithium difluorophosphate;
the water and acid removal additive comprises at least one of tri (trimethylsilane) borate and tri (trimethylsilane) phosphate.
5. The electrolyte additive of claim 1 wherein the first additive further comprises tetravinyl silane.
6. An electrolyte comprising the electrolyte additive of any one of claims 1-5.
7. The electrolyte of claim 6, further comprising: a solvent and an electrolyte lithium salt comprising at least one of lithium hexafluorophosphate, lithium bis-fluorosulfonimide.
8. The electrolyte of claim 7, wherein the electrolyte lithium salt is present in the electrolyte in an amount of 12% to 18% by mass.
9. The electrolyte of claim 7 or 8, wherein the solvent comprises at least one of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, methylethyl carbonate, ethyl propionate, propyl propionate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate.
10. The electrolyte according to claim 7 or 8, wherein the mass fraction of the solvent in the electrolyte is 50-80%.
11. The electrolyte according to claim 7 or 8, wherein the mass fraction of tetraethylsilane in the electrolyte is 0.1% -2%.
12. The electrolyte according to claim 7 or 8, wherein the mass fraction of lithium tetrafluorooxalate phosphate in the electrolyte is 0.03% -3%; optionally, the mass fraction of the lithium tetrafluorooxalate phosphate in the electrolyte is 0.1% -2%.
13. Electrolyte according to claim 7 or 8, characterized in that the mass fraction of the second additive in the electrolyte is 0.5% -3%.
14. A battery comprising the electrolyte additive of any one of claims 1-5, or the electrolyte of any one of claims 6-13.
15. The battery according to claim 14, further comprising a positive electrode sheet including a positive electrode current collector and a positive electrode active material layer located on at least one side surface of the positive electrode sheet, the positive electrode active material layer including a positive electrode active material, the mass fraction of nickel element in the positive electrode active material being 40% or more.
16. The battery of claim 15, wherein the positive electrode active material satisfies the general formula Li a Ni b Co c M1 d M2 e O f R g ，
Wherein a is more than or equal to 1 and less than or equal to 1.2, b is more than or equal to 0.6 and less than or equal to 1, c is more than or equal to 0 and less than or equal to 1, d is more than or equal to 0 and less than or equal to 1, e is more than or equal to 0 and less than or equal to 0.2, b+c+d+e=1, f is more than or equal to 1 and less than or equal to 1, g is more than or equal to 0 and less than or equal to 1, and f+g=2; m1 comprises Mn and/or Al, M2 comprises at least one of Zr, zn, cu, cr, mg, fe, V, ti, sr, sb, Y, W, nb, and R comprises at least one of N, F, S, cl.
17. The battery of claim 16, wherein the positive electrode active material comprises LiNi 0.7 Co 0.1 Mn 0.2 O 2 、LiNi 0.8 Co 0.1 Mn 0.1 O 2 、LiNi 0.8 Co 0.15 Al 0.05 O 2 、LiNi 0.9 Co 0.05 Mn 0.05 O 2 At least one of them.
18. An electrical device comprising a battery as claimed in any one of claims 14 to 17.
CN202311334531.XA 2023-10-16 2023-10-16 Electrolyte additive, electrolyte, battery and electricity utilization device Pending CN117594875A (en)

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