Electrolyte, battery monomer, battery device and energy storage device

Abstract

The invention relates to the technical field of batteries, in particular to an electrolyte, a battery monomer, a battery device and an energy storage device. The electrolyte provided by the invention comprises a first additive, and the first additive comprises a fluorosulfonamide compound and an isocyanate compound, r1 and R2 respectively and independently comprise one of hydrogen, fluorine, substituted or unsubstituted alkane, substituted or unsubstituted alkylene, substituted or unsubstituted alkyne, substituted or unsubstituted alkyl carbonyl and substituted or unsubstituted alkyl nitrile, and at least one of R1 and R2 contains a fluorine element; and R3 comprises one of a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkyl carbonyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted alkoxy group and a substituted or unsubstituted heterocyclic group. Under the synergistic effect of the fluorosulfonamide compound and the isocyanate compound, the electrolyte has good stability and is not easy to decompose.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to an electrolyte, a battery cell, a battery device, and an energy storage device. Background Technology

[0002] Lithium-ion batteries are widely used in daily life, work, and production. With societal development, the demands on them are increasing, such as requiring higher energy density. Methods to improve energy density include using high-energy-density cathode materials (such as high-nickel ternary cathode materials) and increasing battery charging voltage. However, these methods can reduce electrolyte stability and make it prone to decomposition. Compounds containing fluorine, nitrogen, and sulfur can be used as electrolyte additives, but these compounds are not very effective in improving electrolyte stability and urgently need improvement. Summary of the Invention

[0003] This application is made in view of the above-mentioned technical problems, and its purpose is to solve the problem that compounds containing fluorine, nitrogen and sulfur simultaneously have insufficient effect on improving the stability of electrolytes.

[0004] To achieve the above objectives, this application provides an electrolyte, a battery cell, a battery device, and an energy storage device.

[0005] The first aspect of this application provides an electrolyte comprising a first additive, the first additive comprising a fluorosulfonamide compound and an isocyanate compound, the fluorosulfonamide compound comprising the structure shown in formula (1):

[0006]

[0007] R1 and R2 each independently include one of hydrogen, fluorine, substituted or unsubstituted alkane group, substituted or unsubstituted alkene group, substituted or unsubstituted alkyne group, substituted or unsubstituted alkane carbonyl group, and substituted or unsubstituted alkane nitrile group, and at least one of R1 and R2 contains fluorine.

[0008] R3 includes one of the following: substituted or unsubstituted alkane group, substituted or unsubstituted alkane carbonyl group, substituted or unsubstituted aromatic group, substituted or unsubstituted alkoxy group, or substituted or unsubstituted heterocyclic group.

[0009] In the electrolyte of this application embodiment, in addition to using fluorosulfonamide compounds having the structure of formula (1) as additives, isocyanate compounds are added. The synergistic effect of these two compounds can effectively improve the stability of the electrolyte, making it less prone to decomposition. The possible mechanism is as follows:

[0010] The fluorine, nitrogen, and sulfur groups in fluorosulfonamide compounds facilitate the formation of solid electrolyte interfacial films rich in fluorides, nitrides, and sulfides, such as LiF, Li3N, and Li2S, on the electrode surface. These inorganic components possess excellent chemical stability, enhancing the stability of the solid electrolyte interfacial film. Since the solid electrolyte interfacial film is formed by the redox decomposition of the electrolyte and its deposition on the electrode material surface, improving the stability of the solid electrolyte and the interfacial film can reduce electrolyte decomposition during battery cycling, thus improving electrolyte stability. Simultaneously, the sulfur atoms in these compounds have a complexing effect on transition metals in the positive electrode active material, inhibiting their dissolution and migration. Transition metals, in turn, promote electrolyte decomposition; therefore, inhibiting their dissolution and migration also inhibits electrolyte decomposition, further improving electrolyte stability.

[0011] Meanwhile, the isocyanate compounds in the first additive can react with water and HF, reducing the content of water and HF in the electrolyte and having the function of removing water and acid. Therefore, it can inhibit the decomposition of electrolyte caused by water and HF and improve the stability of electrolyte.

[0012] Therefore, the electrolyte exhibits excellent stability and is not easily decomposed due to the synergistic effect of fluorosulfonamides and isocyanates.

[0013] In some embodiments, the total number of fluorine atoms in both R1 and R2 is 1 to 3. Fluorine in fluorosulfonamide compounds can participate in the formation of the interface film on the positive electrode surface, making the interface film contain chemically stable fluorides, improving the stability of the interface film, and thus helping to improve the stability of the electrolyte.

[0014] In some embodiments, at least one of R1 and R2 includes a fluorine or a fluorinated alkane group. The fluorine or fluorinated alkane group can provide the required fluorine element for the fluorosulfonamide compound, which is beneficial for forming a fluoride-containing interfacial film on the positive electrode surface, improving the stability of the interfacial film, and thus improving the stability of the electrolyte.

[0015] In some embodiments, R1 includes one of fluorine or fluorinated alkane groups, and R2 includes one of substituted or unsubstituted alkane groups, substituted or unsubstituted alkenyl groups, substituted or unsubstituted alkyne groups, substituted or unsubstituted alkane carbonyl groups, or substituted or unsubstituted alkane nitrile groups. Optionally, the fluorinated alkane group in R1 includes a fluorinated C1-C6 alkane group.

[0016] In some embodiments, R3 comprises a substituted or unsubstituted heterocyclic group. Optionally, the heterocyclic group comprises a thiophene group.

[0017] In some embodiments, the fluorosulfonamide compound includes one or more of compounds 1 to 6:

[0018]

[0019] Practice has shown that when R1, R2, and R3 are selected from these groups, and when fluorosulfonamide compounds are selected from these compounds, combining them with isocyanate compounds can effectively improve the stability of the electrolyte.

[0020] In some embodiments, the fluorosulfonamide compound has a mass content of 0.1% to 10% in the electrolyte, optionally 0.1% to 5%. Fluorosulfonamide compounds can participate in the formation of the positive electrode interface film, forming a stable interface film rich in fluorides, nitrides, and sulfides, improving the stability of the interface film and helping to reduce electrolyte decomposition during battery cycling. For batteries containing this electrolyte, advantages such as reduced gas production and increased cycle life are observed. At a suitable mass content of fluorosulfonamide compounds, the battery can have very low gas production and a long cycle life. Furthermore, at this mass content, the interface film formed has a moderate thickness and low impedance.

[0021] In some embodiments, the isocyanate compounds include one or more of hexamethylene diisocyanate (HDI), triallyl isocyanurate, p-toluenesulfonyl isocyanate, and m-phenylenedimethyl diisocyanate. These isocyanate compounds can react with water and HF, reducing the water and HF content in the electrolyte, thus having a dehydrating and deacidifying effect. Therefore, they can inhibit electrolyte decomposition caused by water and HF, and when combined with fluorosulfonamide compounds, they can effectively improve the stability of the electrolyte.

[0022] In some embodiments, the isocyanate compound has a mass content of 0.1% to 2% in the electrolyte, optionally 0.2% to 0.5%. As a dehydrating and deacidifying additive in the electrolyte, the isocyanate compound can effectively reduce the water and acid in the electrolyte when the amount is appropriate, while causing little or no side reactions.

[0023] In some embodiments, the electrolyte further includes a second additive, which comprises one or more of cyclic carbonate electrolyte additives, cyclic sulfonyl lactone electrolyte additives, cyclic sulfate electrolyte additives, and lithium salt electrolyte additives. Exemplary cyclic carbonate electrolyte additives include one or more of vinylene carbonate (VC), fluoroethylene carbonate (FEC), and ethylene ethylene carbonate (VEC). Exemplary cyclic sulfonyl lactone electrolyte additives include one or more of 1,3-propanesulfonyl lactone (PS) and 1,3-propenesulfonyl lactone (PST). Exemplary cyclic sulfate electrolyte additives include vinyl sulfate (DTD). Exemplary lithium salt electrolyte additives include one or more of lithium difluorophosphate (LiPO2F2), lithium difluorooxalate borate (LiODFB), lithium bis(oxalate borate) (LiBOB), lithium tetrafluoroborate (LiBF4), and lithium difluorooxalate phosphate (LiODFP).

[0024] The second additive has a mass content of 0.1% to 20% in the electrolyte, optionally 0.2% to 5%. Optionally, the lithium salt electrolyte additive has a mass content of 0.5% to 2% in the electrolyte. Optionally, the cyclic carbonate electrolyte additive has a mass content of 0.2% to 1% in the electrolyte. Optionally, the cyclic sulfonyl lactone electrolyte additive has a mass content of 0.1% to 2% in the electrolyte. Optionally, the cyclic sulfate electrolyte additive has a mass content of 0.5% to 1% in the electrolyte.

[0025] Cyclic carbonate electrolyte additives, cyclic sulfonyl lactone electrolyte additives, cyclic sulfate electrolyte additives, and lithium salt electrolyte additives are important additives that can improve the electrochemical performance of batteries, such as inhibiting electrolyte decomposition and improving battery cycle performance. By adding a second additive to the electrolyte, it can work synergistically with the first additive, which contains fluorosulfonamide compounds and isocyanate compounds, to give the electrolyte better stability and improve battery performance.

[0026] A second aspect of this application provides a battery cell including the electrolyte described above.

[0027] The battery cell includes an electrolyte containing fluorosulfonamide compounds and isocyanate compounds. This electrolyte has excellent stability and is not easily decomposed at both room temperature and high temperature, reducing gas generation. Therefore, the battery cell has the advantage of small thickness expansion when used or stored at room temperature or high temperature, and has excellent stability and safety. In addition, the battery cell also exhibits the advantages of long cycle life and low impedance.

[0028] A third aspect of this application provides a battery device comprising a plurality of the aforementioned battery cells.

[0029] The battery cells of this application exhibit minimal thickness expansion during use or storage at both room temperature and high temperature, demonstrating excellent stability and safety. Furthermore, they exhibit long cycle life and long storage life. Therefore, applying these battery cells to battery devices improves the safety of the battery devices and extends their storage and operating time.

[0030] A fourth aspect of this application provides an energy storage device, including multiple battery cells or multiple battery devices, wherein the battery cells or battery devices are used to store or provide electrical energy. The aforementioned battery cells and battery devices, used to store or provide electrical energy for the energy storage device, can improve the safety of the energy storage device and extend its storage and operating time. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 This is a schematic diagram of a battery cell according to one embodiment of this application;

[0033] Figure 2 for Figure 1 An exploded view of a battery cell according to one embodiment of this application is shown. Detailed Implementation

[0034] The embodiments of this application are hereby disclosed in detail with appropriate reference to the accompanying drawings. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of actually identical structures may be omitted. This is to avoid making the following description unnecessarily lengthy and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0035] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60–120 and 80–110 are listed for a specific parameter, it is understood that ranges of 60–110 and 80–120 are also expected. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1–3, 1–4, 1–5, 2–3, 2–4, and 2–5. In this application, unless otherwise stated, the numerical range "a–b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0" and "5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0036] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0037] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0038] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0039] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0040] Unless otherwise specified, the term "or" is inclusive in this application. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, the condition "A or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0041] Methods to improve the energy density of lithium-ion batteries include using high-energy-density cathode materials (such as high-nickel ternary cathode materials) and increasing the battery's charging voltage. High-nickel ternary cathode materials, due to their high nickel content, can provide higher discharge specific capacity and volumetric energy density, so researchers have attempted to use them to improve the high energy density of lithium-ion batteries. However, this approach has adverse effects on the electrolyte. For example, excessively high nickel content in this material reduces the stability of the cathode material. During charging and discharging, nickel is usually in an unstable trivalent state, and these unstable trivalent nickel ions can cause oxidative decomposition of the electrolyte at the cathode. Simultaneously, increasing the battery's charging voltage can increase the battery's voltage plateau, thereby also improving the battery's energy density. However, due to the low oxidation potential of the solvent in the electrolyte, it is difficult to remain stable at high voltages, and due to other factors, increasing the battery's charging voltage makes the electrolyte more susceptible to oxidative decomposition. Oxidative decomposition of the electrolyte can lead to a series of problems such as battery swelling, increased interfacial impedance, and reduced cycle life. Therefore, it is necessary to develop an electrolyte formulation with good stability and resistance to decomposition.

[0042] Common methods for improving electrolyte stability include adding electrolyte additives. Related studies have found that fluorine-containing, nitrogen-containing, or sulfur-containing groups in some compounds can participate in the formation of the solid electrolyte interfacial film on the electrode surface, enriching the solid electrolyte interfacial film with fluorides, nitrides, or sulfides, which is beneficial for improving the chemical stability of the solid electrolyte interfacial film. Since the solid electrolyte interfacial film is mainly formed by the oxidative decomposition of the electrolyte and its deposition on the electrode surface, improving the stability of the solid electrolyte interfacial film can reduce electrolyte decomposition, thereby improving electrolyte stability. Because additives containing only one functional group have limited effect on improving the electrolyte, it is possible to try combining these different groups in the same compound, that is, using a compound containing multiple functional groups as an additive, which may enhance the effectiveness of the additive. For example, combining fluorine-containing, nitrogen-containing, and sulfur-containing groups in the same compound can form a compound containing fluorine, nitrogen, and sulfur simultaneously. This compound can improve the stability of the solid electrolyte interfacial film better than compounds containing a single group. Nevertheless, water is inevitably introduced during electrolyte preparation, and lithium salts such as LiPF6 in the electrolyte react with trace amounts of water to generate HF. HF will damage the solid electrolyte interfacial film, thereby causing electrolyte decomposition. These compounds, which contain fluorine, nitrogen, and sulfur, do not have the function of removing water and acid and cannot improve this problem. Therefore, their effect on improving electrolyte stability is very limited.

[0043] Combining multiple additives can achieve synergistic effects. Since compounds containing fluorine, nitrogen, and sulfur lack dehydration and deacidification functions, it's possible to try combining them with dehydration and deacidification additives. However, practice has shown that combining these compounds with many dehydration and deacidification additives does not improve electrolyte stability; in fact, they are more prone to decomposition than when no additives are used. Therefore, how to improve the stability of the solid electrolyte interfacial film using compounds containing fluorine, nitrogen, and sulfur while simultaneously enhancing dehydration and deacidification functions, thereby effectively improving electrolyte stability, is a problem that urgently needs to be solved.

[0044] Based on this, embodiments of this application provide an electrolyte in which the additives contain both fluorosulfonamide compounds and isocyanate compounds. By combining these two types of compounds, the stability of the solid electrolyte interface film can be improved by utilizing fluorine-containing, nitrogen-containing, and sulfur-containing groups, while the water-removing and acid-removing effects of isocyanate compounds can be utilized without causing side reactions, thus effectively improving the stability of the electrolyte.

[0045] The electrolyte of this application embodiment can be applied to battery cells, such as lithium secondary batteries, enabling the battery cells to exhibit long cycle life, low internal resistance, and low gas production at both room temperature and high temperature. This battery cell can be used in battery devices and energy storage devices.

[0046] The battery cell in this embodiment includes an electrolyte, and typically also includes a negative electrode, a positive electrode, and a separator. During battery charging and discharging, active ions repeatedly insert and extract between the positive and negative electrodes. The electrolyte acts as a conductor of ions between the positive and negative electrodes. The separator is disposed between the positive and negative electrodes, primarily to prevent short circuits between the positive and negative electrodes, while simultaneously allowing ions to pass through.

[0047] Electrolyte

[0048] The electrolyte acts as a conductor of ions between the positive and negative electrodes. In the embodiments of this application, the electrolyte includes a first additive, which includes a fluorosulfonamide compound and an isocyanate compound. The fluorosulfonamide compound has the structure shown in formula (1):

[0049]

[0050] R1 and R2 each independently include one of hydrogen, fluorine, substituted or unsubstituted alkane group, substituted or unsubstituted alkene group, substituted or unsubstituted alkyne group, substituted or unsubstituted alkane carbonyl group, and substituted or unsubstituted alkane nitrile group, and at least one of R1 and R2 contains fluorine.

[0051] R3 includes one of the following: substituted or unsubstituted alkane group, substituted or unsubstituted alkane carbonyl group, substituted or unsubstituted aromatic group, substituted or unsubstituted alkoxy group, or substituted or unsubstituted heterocyclic group.

[0052] Understandably, the term "alkane group" refers to an organic group composed of saturated carbon-hydrogen bonds, derived from alkane molecules (alkanes are hydrocarbons containing only carbon-carbon and carbon-hydrogen single bonds, lacking double or triple bonds in their molecular structure). Alkane groups are typically chain-like, and can be straight-chain or branched; in some cases, alkane groups may also contain cyclic structures. In the embodiments of this application, alkane groups optionally include C1-C6 alkane groups, and optionally include C1-C3 alkane groups. Cx-Cy refers to the number of carbon atoms x-y; for example, C1-C6 alkane groups represent alkane groups with 1-6 carbon atoms. Exemplary alkane groups may include one or more of methyl, ethyl, propyl, butyl, pentyl, hexyl, cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl.

[0053] "Alkenyl group," also known as olefin group, can be considered as a group formed by removing one or more hydrogen atoms from an olefin molecule, containing one or more carbon-carbon double bonds. In the embodiments of this application, the olefin group includes C2-C6 olefin groups, optionally including C2-C3 olefin groups. Exemplary olefin groups include one or more of vinyl, propenyl, butenyl, pentenyl, hexenyl, butadienyl, pentadienyl, hexadienyl, and hextrienyl groups.

[0054] "Alkyne group," or alkynyl group, is a group containing a carbon-carbon triple bond (-C≡C-). In the embodiments of this application, the alkynyl group includes C2-C6 alkynyl groups, and optionally includes C2-C3 alkynyl groups. Exemplary alkynyl groups include one or more of ethynyl, propynyl, butynyl, pentyynyl, hexynyl, butyynyl, pentyynyl, hexadiynyl, and hexadiynyl.

[0055] "Alkyl carbonyl" is a group containing a carbonyl group (-C=O), wherein the carbon atom of the carbonyl group is attached to an alkane group. Exemplary alkyl carbonyl groups include -R4-CO-R5, where R4 is a substituted or unsubstituted alkane group and R5 is H or a substituted or unsubstituted alkane group.

[0056] "Alkanilide" refers to a group composed of an alkane group and a cyano group (-CN), also known as "cyanoalkyl". In the embodiments of this application, the alkanilide may optionally include a group composed of a C1-C6 alkane group and a cyano group. Exemplary alkanilide groups include one or more of methacrylonitrile, ethylacrylonitrile, propylacrylonitrile, butylacrylonitrile, pentylacrylonitrile, and hexylacrylonitrile.

[0057] "Aromatic group" is a group containing an aromatic ring (usually a benzene ring).

[0058] An "alkoxy group" is a group consisting of an alkane group and an oxygen atom, usually represented by R6O-, where R6 represents an alkane group. Exemplary alkoxy groups include methoxy (CH3O-), ethoxy (C2H5O-), propoxy (C3H7O-), etc.

[0059] A "heterocyclic group" is a group having a cyclic structure that contains at least one heteroatom in addition to a carbon atom. These heteroatoms are typically non-carbon atoms such as oxygen, sulfur, or nitrogen, and can be part of the ring or an external substituent. Exemplary heterocyclic groups include thiophene groups, pyridinium groups, etc.

[0060] "Substituted or unsubstituted" means that the hydrogen atom in the group is replaced by another group, or that the hydrogen atom in the group is not replaced by another group. The group used for substitution can include one or more of fluorine, hydroxyl, and amino groups.

[0061] At least one of R1 and R2 contains fluorine, including at least one of the following 1) and 2): 1) At least one of R1 and R2 is fluorine, i.e., N in the structural formula (1) is directly connected to at least one fluorine; 2) At least one of R1 and R2 is selected from one of substituted alkane group, substituted alkenyl group, substituted alkyne group, substituted alkane carbonyl group, and substituted alkane nitrile group, and the substituents of the substituted alkane group, substituted alkenyl group, substituted alkyne group, substituted alkane carbonyl group, and substituted alkane nitrile group contain fluorine substituents.

[0062] Isocyanates are organic compounds containing isocyanate (-N=C=O) groups.

[0063] The structural formulas of fluorosulfonamides and isocyanates in the electrolyte and their substituents can be identified using gas chromatography-mass spectrometry (GC-MS).

[0064] In the electrolyte of this application embodiment, in addition to using fluorosulfonamide compounds having the structure of formula (1) as additives, isocyanate compounds are added. The synergistic effect of these two compounds can effectively improve the stability of the electrolyte, making it less prone to decomposition. The possible mechanism is as follows:

[0065] The fluorine, nitrogen, and sulfur groups in fluorosulfonamide compounds facilitate the formation of solid electrolyte interfacial films rich in fluorides, nitrides, and sulfides, such as LiF, Li3N, and Li2S, on the electrode surface. These inorganic components possess excellent chemical stability, enhancing the stability of the solid electrolyte interfacial film. Since the solid electrolyte interfacial film is formed by the redox decomposition of the electrolyte and its deposition on the electrode material surface, improving the stability of the solid electrolyte and the interfacial film can reduce electrolyte decomposition during battery cycling, thus improving electrolyte stability. Simultaneously, the sulfur atoms in these compounds have a complexing effect on transition metals in the positive electrode active material, inhibiting their dissolution and migration. Transition metals, in turn, promote electrolyte decomposition; therefore, inhibiting their dissolution and migration also inhibits electrolyte decomposition, further improving electrolyte stability.

[0066] Meanwhile, the isocyanate compounds in the first additive can react with water and HF, reducing the content of water and HF in the electrolyte and having the function of removing water and acid. Therefore, it can inhibit the decomposition of electrolyte caused by water and HF and improve the stability of electrolyte.

[0067] Therefore, the electrolyte exhibits excellent stability and is not easily decomposed due to the synergistic effect of fluorosulfonamides and isocyanates.

[0068] In some implementations, the unsaturation degrees of R1 and R2 are independently 0 to 4, and optionally independently 2 to 4, for example, they can be any point value of 0, 1, 2, 3, 4 or any range of values ​​between the two.

[0069] The degree of unsaturation of a functional group refers to the number of hydrogen atoms missing from the double bonds (C=C), triple bonds (C≡C), or cyclic structures formed by carbon atoms in the group compared to a fully saturated carbon group (i.e., all carbon atoms connected by single bonds). The types of functional groups R1 and R2 can be identified by GC-MS, and the degree of unsaturation can be calculated using the formula Ω = (2C + 2H - X + N) / 2, where Ω represents the degree of unsaturation, C represents the number of carbon atoms, X represents the number of hydrogen atoms, X represents the number of halogen atoms, and N represents the number of nitrogen atoms.

[0070] The degree of unsaturation of the functional groups has a significant impact on the formation and stability of the interfacial film between the electrolyte and the electrode. Under certain saturation conditions, R1 and R2 can facilitate the redox reaction of fluorosulfonamide compounds, thereby forming a stable interfacial film on the positive electrode surface. This results in a stable interfacial film rich in fluorides, nitrides, and sulfides, which improves the stability of the interfacial film and helps reduce electrolyte decomposition during battery cycling, thus enhancing the overall stability of the electrolyte.

[0071] In some embodiments, the total number of fluorine atoms in R1 and R2 is 1 to 3, for example, any one of 1, 2, or 3. Fluorine in fluorosulfonamide compounds can participate in the formation of the interface film on the positive electrode surface, making the interface film contain chemically stable fluorides, improving the stability of the interface film, and thus contributing to the improvement of electrolyte stability.

[0072] In some embodiments, at least one of R1 and R2 includes a fluorine or a fluorinated alkane group. The fluorine or fluorinated alkane group can provide the required fluorine element for the fluorosulfonamide compound, which is beneficial for forming a fluoride-containing interfacial film on the positive electrode surface, improving the stability of the interfacial film, and thus improving the stability of the electrolyte.

[0073] In some embodiments, R1 comprises one of fluorine or fluorinated alkane groups, and R2 comprises one of substituted or unsubstituted alkane groups, substituted or unsubstituted alkenyl groups, substituted or unsubstituted alkyne groups, substituted or unsubstituted alkane carbonyl groups, or substituted or unsubstituted alkane nitrile groups. Optionally, the fluorinated alkane group in R1 comprises a fluorinated C1-C6 alkane group. Optionally, the substituted or unsubstituted alkane group in R2 comprises a fluorinated or unsubstituted C1-C6 alkane group, the substituted or unsubstituted alkenyl group comprises a fluorinated or unsubstituted C2-C6 alkenyl group, the substituted or unsubstituted alkyne group comprises a fluorinated or unsubstituted C2-C6 alkyne group, the substituted or unsubstituted alkane carbonyl group comprises a fluorinated or unsubstituted C1-C6 alkane carbonyl group, and the substituted or unsubstituted alkane nitrile group comprises a fluorinated or unsubstituted C1-C6 alkane nitrile group.

[0074] In some embodiments, R3 comprises a substituted or unsubstituted heterocyclic group. Optionally, the heterocyclic group comprises a thiophene group. When R3 is a thiophene group, the fluorosulfonamide compound comprises the structure shown in formula (2):

[0075]

[0076] In some embodiments, the fluorosulfonamide compound includes one or more of compounds 1 to 6:

[0077]

[0078] Practice has shown that when R1, R2, and R3 are selected from these groups, and when fluorosulfonamides are selected from these compounds, combining them with isocyanate compounds can effectively improve the stability of the electrolyte.

[0079] In some embodiments, the fluorosulfonamide compound is present in the electrolyte at a mass content of 0.1% to 10%, optionally 0.1% to 5%, and even more optionally 0.1% to 1%. For example, the mass content may be any one of 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, 10%, or a range between any two.

[0080] The mass content of fluorosulfonamide compounds can be analyzed using gas chromatography-mass spectrometry (GC-MS). Understandably, during electrolyte preparation, fluorosulfonamide compounds can be added to the electrolyte at the mass content described above. Furthermore, although some fluorosulfonamide compounds are consumed during battery application and operation due to their participation in the formation of the positive electrode interface film, this consumption is negligible because the interface film is typically very thin. Therefore, the mass content of fluorosulfonamide compounds in the electrolyte usually does not change significantly after application and during operation. Moreover, when the fluorosulfonamide compound contains specific compounds with different structural formulas, these compounds can be combined in any proportion. For example, if the fluorosulfonamide compound is a combination of compound 1 and compound 6, compounds 1 and 6 can be combined in any proportion, as long as their total mass content remains within the aforementioned range.

[0081] Fluorosulfonamide compounds can participate in the formation of the positive electrode interfacial film, forming a stable interfacial film rich in fluorides, nitrides, and sulfides. This improves the stability of the interfacial film and helps reduce electrolyte decomposition during battery cycling, thus enhancing electrolyte stability. Batteries containing this type of electrolyte exhibit advantages such as reduced gas production and increased cycle life. At appropriate mass concentrations of fluorosulfonamide compounds, the battery can achieve very low gas production and long cycle life. Furthermore, at these mass concentrations, the formed interfacial film has a suitable thickness and low impedance.

[0082] In some embodiments, the isocyanate compounds include one or more of hexamethylene diisocyanate (HDI), triallyl isocyanurate, p-toluenesulfonyl isocyanate, and m-phenylenedimethyl diisocyanate. These isocyanate compounds can react with water and HF, reducing the water and HF content in the electrolyte, thus having a dehydrating and deacidifying effect. Therefore, they can inhibit electrolyte decomposition caused by water and HF, and when combined with fluorosulfonamide compounds, they can effectively improve the stability of the electrolyte.

[0083] In some embodiments, the isocyanate compound in the electrolyte contains 0.1% to 2% by mass, optionally 0.2% to 0.5%. For example, this mass content can be any one of 0.1%, 0.5%, 1%, 1.5%, or 2%, or a range between any two. Similarly, the mass content of the isocyanate compound can be analyzed using gas chromatography-mass spectrometry (GC-MS). As a dehydrating and deacidifying additive in the electrolyte, the isocyanate compound, when used in appropriate amounts, can effectively reduce water and acid in the electrolyte while causing little or no side reactions.

[0084] In some embodiments, the electrolyte further includes a second additive, which comprises one or more of cyclic carbonate electrolyte additives, cyclic sulfonyl lactone electrolyte additives, cyclic sulfate electrolyte additives, and lithium salt electrolyte additives. Exemplary cyclic carbonate electrolyte additives include one or more of vinylene carbonate (VC), fluoroethylene carbonate (FEC), and ethylene ethylene carbonate (VEC). Exemplary cyclic sulfonyl lactone electrolyte additives include one or more of 1,3-propanesulfonyl lactone (PS) and 1,3-propenesulfonyl lactone (PST). Exemplary cyclic sulfate electrolyte additives include vinyl sulfate (DTD). Exemplary lithium salt electrolyte additives include one or more of lithium difluorophosphate (LiPO2F2), lithium difluorooxalate borate (LiODFB), lithium bis(oxalate borate) (LiBOB), lithium tetrafluoroborate (LiBF4), and lithium difluorooxalate phosphate (LiODFP).

[0085] The second additive has a mass content of 0.1% to 20% in the electrolyte, optionally 0.2% to 5%, for example, any one of 0.1%, 0.2%, 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 12%, 14%, 16%, 18%, or 20%, or a range between any two. Optionally, the lithium salt electrolyte additive has a mass content of 0.5% to 2% in the electrolyte, for example, any one of 0.5%, 1%, 1.5%, or 2%, or a range between any two. Optionally, the cyclic carbonate electrolyte additive has a mass content of 0.2% to 1% in the electrolyte, for example, any one of 0.2%, 0.5%, or 1%, or a range between any two. Optionally, the cyclic sulfonyl lactone electrolyte additive has a mass content of 0.1% to 2% in the electrolyte, for example, any one of 0.1%, 0.5%, 1%, 1.5%, or 2%, or a range between any two. Optionally, the cyclic sulfate ester electrolyte additive has a mass content of 0.5% to 1% in the electrolyte, for example, any one of 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, or 1%, or a range between any two.

[0086] Cyclic carbonate electrolyte additives, cyclic sulfonyl lactone electrolyte additives, cyclic sulfate electrolyte additives, and lithium salt electrolyte additives are important additives that can improve the electrochemical performance of batteries, such as inhibiting electrolyte decomposition and improving battery cycle performance. By adding a second additive to the electrolyte, it can work synergistically with the first additive, which contains fluorosulfonamide compounds and isocyanate compounds, to give the electrolyte better stability and improve battery performance.

[0087] In some embodiments, the electrolyte also includes a solvent and an electrolyte lithium salt.

[0088] The solvent can be a non-aqueous organic solvent, such as one or more of ethylene carbonate (EC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), propylene carbonate (PC), diethyl carbonate (DEC), propylene carbonate (PC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), and ethyl butyrate (EB), and may be selected from two or more.

[0089] The electrolyte lithium salt may include one or more of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorooxalate borate (LiDFOB), lithium bis(oxalate borate) (LiBOB), lithium difluorophosphate (LiPO2F2), lithium difluorooxalate phosphate (LiDFOP), and lithium tetrafluorooxalate phosphate (LiTFOP). It is understood that the "electrolyte lithium salt" in the embodiments of this application is a different concept from the "lithium salt electrolyte additive" mentioned above. The "electrolyte lithium salt" refers to the main component in the electrolyte that provides lithium ions, playing a role in ion transport during battery charging and discharging; while the "lithium salt electrolyte additive" is a small amount of substance added to the electrolyte to improve certain specific battery performance.

[0090] The concentration of the lithium electrolyte salt in the electrolyte can range from 0.5 to 2 mol / L, for example, any one of 0.5 mol / L, 0.6 mol / L, 0.8 mol / L, 1 mol / L, 1.2 mol / L, 1.4 mol / L, 1.5 mol / L, and 2 mol / L, or any range between two values. The mass content of the lithium electrolyte salt in the electrolyte can be 5% to 20%, optionally 10% to 15%, for example, any one of 5%, 10%, 13%, 15%, and 20%, or any range between two values.

[0091] The electrolyte in this embodiment can be prepared by the following method:

[0092] Electrolyte lithium salts, fluorosulfonamides, isocyanates, and other additives are dissolved in a solvent under a protective atmosphere (e.g., argon or nitrogen).

[0093] [Positive electrode plate]

[0094] The battery cell in this application embodiment includes a positive electrode sheet, which includes a positive current collector and a positive active layer disposed on at least one side of the positive current collector. The positive active layer includes a positive active material, a conductive agent, and a binder.

[0095] In some embodiments, the positive electrode active material comprises a transition metal, such as one or more of nickel, cobalt, and manganese. The sulfur in the fluorosulfonamide compounds in the electrolyte of this application can adsorb or coordinate with these transition metals, mitigating their dissolution.

[0096] In some embodiments, the positive electrode active material includes lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, and lithium nickel cobalt manganese oxide [such as LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2(NCM333), LiNi 0.5 Co 0.2 Mn 0.3 O2(NCM523), LiNi 0.5 Co 0.25 Mn 0.25 O2(NCM211), LiNi 0.6 Co 0.2 Mn 0.2 O2(NCM622), LiNi 0.8 Co 0.1 Mn 0.1 O2 (NCM811)], lithium nickel cobalt aluminum oxides [such as LiNi] 0.8 Co 0.15 Al 0.05 O2, LiNi 0.8 Co 0.1 Al 0.1 One or more of O2(NCA811) and its modified compounds. These positive electrode active materials can be used alone or in combination of two or more. Optionally, the positive electrode active materials include NCM811, LiNi 0.8 Co 0.15 Al 0.05 O2, one or more of NCA811, NCM811, LiNi 0.8 Co 0.15 Al 0.05O2 and NCA811 have high nickel content, resulting in high specific capacity and high energy density, which is beneficial for improving the energy density of batteries. In this application, the simultaneous addition of fluorosulfonamide compounds and isocyanate compounds to the electrolyte significantly improves electrolyte stability and reduces the likelihood of electrolyte decomposition, regardless of the cathode active material used in the battery. This improvement is particularly pronounced in high-nickel cathode active material systems.

[0097] The mass content of the positive electrode active material in the positive electrode active layer can be, but is not limited to, 70% to 98%, or 80% to 98%, for example, any one of 70%, 75%, 80%, 85%, 90%, 92%, 94%, 96%, 98%, or any range between two.

[0098] In some embodiments, the binder in the positive electrode active layer may include one or more of the following: polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, fluorinated acrylate resin, polyamide (PA), polyacrylonitrile (PAN), polyacrylate, polyethylene ether, polymethyl methacrylate (PMMA), polyhexafluoropropylene, and styrene-butadiene rubber (SBR).

[0099] In some embodiments, the conductive agent in the positive electrode active layer may include one or more of acetylene black, conductive carbon black (SP), Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0100] The mass content of binder and conductive agent in the positive electrode active layer can be independently, including but not limited to 0.5% to 10%, or 1% to 10%, for example, any one of the values ​​of 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, or any range between the two.

[0101] In some embodiments, the positive electrode active layer may optionally include a thickener, which may include one or more of sodium carboxymethyl cellulose (CMC-Na) and sodium alginate.

[0102] In some embodiments, the positive electrode active layer may optionally include additives, such as additives that can improve certain properties of the positive electrode, such as additives with lithium replenishment effects, such as additives that can improve the regulation of CEI composition.

[0103] In some embodiments, the positive current collector has two surfaces opposite each other in its own thickness direction, and the positive active layer is disposed on either or both of the two opposite surfaces of the positive current collector.

[0104] In some embodiments, the positive current collector includes one or more of a metal foil and a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer substrate and a metal layer formed on at least one surface of the polymer substrate. The composite current collector can be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer substrate [such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.].

[0105] In some implementations, the positive electrode sheet can be prepared in the following manner:

[0106] The components used to prepare the positive electrode sheet, such as positive active material, conductive agent, binder and any other components, are dispersed in a solvent (e.g. N-methylpyrrolidone) to form a positive electrode slurry; the positive electrode slurry is coated on the positive current collector, and after drying, cold pressing and other processes, the positive electrode sheet can be obtained.

[0107] The compaction density of the positive electrode sheet after cold pressing is typically 3 g / cm³. 3 ~5g / cm 3 For example, 3.5g / cm 3 ~4.2g / cm 3 For example, 3g / cm 3 3.5g / cm 3 4g / cm 3 4.2g / cm 3 4.5g / cm 3 5g / cm 3 The value of any one of the points or the range between any two.

[0108] [Negative electrode plate]

[0109] The battery cell in this application embodiment includes a negative electrode sheet, which includes a negative current collector and a negative active layer disposed on at least one side of the negative current collector. The negative active layer includes a negative active material, a conductive agent, and a binder.

[0110] In some embodiments, the negative electrode active material includes one or more of graphite (artificial graphite, natural graphite), soft carbon, hard carbon, silicon-based materials, tin-based materials, and titanium-based materials. Silicon-based materials may include one or more of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. Tin-based materials may include one or more of elemental tin, tin oxide compounds, and tin alloys. Titanium-based materials may include lithium titanate. It is understood that this application is not limited to these materials, and other materials that can be used as negative electrode active materials in batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0111] The mass content of the negative electrode active material in the negative electrode active layer can range from 70% to 98%, or even 90% to 98%, for example, any one of the values ​​of 70%, 75%, 80%, 85%, 90%, 92%, 94%, 96%, or 98%, or any range between two of these values. A high content of negative electrode active material can provide high energy density for the battery.

[0112] In some embodiments, the binder may include one or more of styrene-butadiene rubber (SBR), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS). The mass content of the binder in the negative electrode active layer may be 0.1% to 10%, for example, any one or a range between 0.1%, 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, and 10%.

[0113] In some embodiments, the conductive agent may include one or more of acetylene black, conductive carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. The mass content of the conductive agent in the negative electrode active layer includes 0.5% to 10%, for example, any one of 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, and 10%, or a range between any two.

[0114] In some embodiments, the negative electrode active layer may optionally include other additives, such as thickeners, like carboxymethyl cellulose (CMC), sodium carboxymethyl cellulose (CMC-Na), etc.

[0115] In some embodiments, the negative electrode current collector has two surfaces opposite each other in its own thickness direction, and the negative electrode active layer is disposed on either or both of the two opposite surfaces of the negative electrode current collector. The negative electrode current collector includes one or more of metal foil and composite current collector. For example, copper foil can be used as the metal foil. The composite current collector may include a polymer material substrate and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector can be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and 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.].

[0116] In some implementations, the negative electrode sheet can be prepared in the following manner:

[0117] The components used to prepare the negative electrode sheet, such as negative electrode active material, binder, and conductive agent (and may also include any other components), are dispersed in a solvent (e.g., water) to form a negative electrode slurry; the negative electrode slurry is coated on at least one side of the negative electrode current collector, and after drying, cold pressing and other processes, the negative electrode sheet can be obtained.

[0118] The compaction density of the negative electrode sheet after cold pressing is typically 1.3 g / cm³. 3 ~2g / cm 3 For example, 1.3g / cm 3 ~1.7g / cm 3 For example, 1.3g / cm 3 1.5g / cm 3 1.7g / cm 3 1.9g / cm 3 2g / cm 3 The value of any one of the points or the range between any two.

[0119] [Isolation membrane]

[0120] Separating membranes are typically stacked between the positive and negative electrodes to separate them, preventing electrons from passing freely and thus preventing short circuits between the electrodes. At the same time, they allow ions in the electrolyte to pass freely between the positive and negative electrodes.

[0121] In the battery of this application, the type of separator can be any known porous structure separator with good chemical and mechanical stability.

[0122] The material of the separator membrane can include one or more of the following: glass fiber, non-woven fabric, polyethylene (PE), polypropylene (PP), and polyvinylidene fluoride (PVDF). The separator membrane can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator membrane is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation. The surface of the separator membrane can be coated with a ceramic coating, such as an alumina coating.

[0123] Positive electrode, negative electrode and separator can be made into electrode assembly by winding process or stacking process.

[0124] [Outer Packaging]

[0125] A single battery cell may include an outer packaging that can be used to encapsulate an electrode assembly containing a positive electrode, a negative electrode, a separator, and an electrolyte.

[0126] The outer packaging can be a hard shell, such as a hard plastic shell, aluminum shell, or steel shell; or it can be a soft package, such as a pouch. The material of the soft package can be plastic, such as polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0127] The outer packaging can be cylindrical, square, or any other shape. For example, Figure 1 The battery cell, as an example, has a square outer packaging shape.

[0128] Reference Figure 2 The outer packaging may include a housing 01 and a cover plate 02. The housing 01 may include a base plate and side plates connected to the base plate, the base plate and side plates forming a receiving cavity. The housing 01 has an opening communicating with the receiving cavity, and the cover plate 02 can be placed over the opening to close the receiving cavity. A positive electrode, a negative electrode, and a separator can be formed into an electrode assembly 03 via a winding or stacking process. One or more electrode assemblies 03 are encapsulated within the receiving cavity. Electrolyte is immersed in the electrode assembly 03.

[0129] [Battery cell]

[0130] In this embodiment, the battery cell can be a rechargeable battery, which refers to a battery cell that can be recharged after discharge to activate the active materials and continue to be used. Optionally, the battery cell in this embodiment can be a lithium-ion battery.

[0131] The battery cell includes an electrolyte containing fluorosulfonamide compounds and isocyanate compounds. This electrolyte has excellent stability and is not easily decomposed at both room temperature and high temperature, reducing gas generation. Therefore, the battery cell has the advantage of small thickness expansion when used or stored at room temperature or high temperature, and has excellent stability and safety. In addition, the battery cell also exhibits the advantages of long cycle life and low impedance.

[0132] [Battery Device]

[0133] This application provides a battery apparatus including multiple battery cells. Specifically, the battery apparatus mentioned in the embodiments of this application may include one or more battery cell assemblies for providing voltage and capacity. A battery cell assembly may include multiple battery cells, which are connected in series, parallel, or mixed connections via a busbar.

[0134] The battery cells of this application exhibit minimal thickness expansion during use or storage at both room temperature and high temperature, resulting in excellent stability and safety. Furthermore, they demonstrate long cycle life and low impedance. Therefore, applying these battery cells to battery devices improves device safety and extends storage and runtime.

[0135] In some implementations, a battery cell assembly is typically formed by arranging multiple battery cells.

[0136] As an example, a battery cell assembly can be a battery module, which is formed by arranging and fixing multiple battery cells together to form an independent module. As another example, a battery module can be formed by bundling multiple battery cells together with cable ties.

[0137] In some implementations, the battery device may be a battery pack, which includes a housing and one or more individual battery cells housed within the housing.

[0138] As an example, the battery cell assembly can be a battery module, which can be housed in a housing by fixing the battery module in the housing.

[0139] As an example, battery cell assemblies can also be housed in a housing by directly fixing multiple battery cells to the housing.

[0140] As an example, the enclosure may include a first enclosure and a second enclosure. The first enclosure and the second enclosure are fastened together to form a closed space inside the enclosure to house the individual battery cells. Here, "closed" refers to covering or closing, and can be either sealed or unsealed. The first enclosure may be a top cover or a bottom plate.

[0141] As an example, the enclosure may include a top cover, a frame, and a bottom plate. The top cover and bottom plate are connected to the frame, creating an enclosed space inside the enclosure to house the individual battery cells.

[0142] In some embodiments, the housing may be part of the vehicle's chassis structure. For example, a portion of the housing may be at least a part of the vehicle's floor, or a portion of the housing may be at least a part of the vehicle's crossbeams and longitudinal beams.

[0143] The technical solutions described in the embodiments of this application are applicable to various electrical devices that use individual battery cells, such as mobile phones, portable devices, laptops, electric vehicles, electric toys, power tools, vehicles, ships, and spacecraft. For example, spacecraft include airplanes, rockets, space shuttles, and spacecraft.

[0144] [Energy Storage Device]

[0145] This application provides an energy storage device, including multiple battery cells or multiple battery devices, wherein the battery cells or battery devices are used to store or provide electrical energy.

[0146] The aforementioned battery cells and battery devices are used to store or provide electrical energy for energy storage devices, which can improve the safety of energy storage devices and extend the storage and battery life of energy storage devices.

[0147] In some implementations, the energy storage device includes one or more battery clusters to increase the voltage and capacity of the energy storage device. A battery cluster may include multiple battery units connected in series via a busbar to increase the voltage of the energy storage device. When the energy storage device includes multiple battery clusters, the battery clusters are connected in parallel to increase the capacity of the energy storage device.

[0148] Energy storage devices can be used in energy storage power stations, wind power generation systems, solar power generation systems, mobile power systems, or temporary power supply systems. Energy storage devices can store electrical energy as needed and output it when appropriate. For example, an energy storage device can store electrical energy during off-peak hours and provide power to relevant users or electrical equipment during peak hours. The energy storage system provided in this application embodiment can be any power system that requires energy storage devices.

[0149] In some implementations, the energy storage device is an energy storage container or an energy storage cabinet.

[0150] In some implementations, the energy storage device may include a cabinet and one or more battery clusters housed within the cabinet.

[0151] In some implementations, the energy storage device may include modules such as a thermal management module, a main control module, a central control module, a power distribution module, and a fire protection module.

[0152] As an example, the thermal management module may include a liquid cooling unit that supplies coolant to each battery device via piping to regulate the temperature of the individual battery cells.

[0153] As an example, the main control module can serve as the battery management unit for the battery cluster, used to monitor and manage the battery cluster. The main control module can monitor information such as the current, voltage, power, or temperature of the battery cluster. For instance, it can control the charging and discharging current and voltage of the battery cluster. The main control module includes modules such as an auxiliary battery management unit (SBMU) and a fusion switch.

[0154] As an example, the central control module can serve as the battery management unit for an energy storage device, used to monitor and manage the device. The central control module can monitor information such as the energy storage device's current, voltage, power, state of charge, or temperature. For instance, it can control the charging and discharging current and voltage of the energy storage device. As an example, the central control module includes modules such as an Insulation Monitoring Module (IMM), a Master Battery Management Unit (MBMU), an Ethernet (ETH) module, and a fiber optic conversion module.

[0155] As an example, the fire protection module includes a control panel, detectors, alarm devices, etc., used to detect, alarm, or extinguish fires in the energy storage system.

[0156] As an example, a power distribution module can be used to distribute power to modules in an energy storage device that require electricity.

[0157] The embodiments of this application are described in detail below. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed in accordance with the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0158] Example 1

[0159] 1. Positive electrode sheet

[0160] LiNi, the positive electrode active material 0.8 Co 0.1 Mn 0.1 O2 (NCM811), conductive agent acetylene black, and binder polyvinylidene fluoride (PVDF) were thoroughly mixed in an N-methylpyrrolidone solvent system at a mass ratio of 95:3:2. The mixture was then coated onto aluminum foil, dried, and cold-pressed to obtain the positive electrode sheet with a compacted density of 3.5 g / cm³. 3 .

[0161] 2. Negative electrode plate

[0162] The negative electrode active material graphite, conductive agent acetylene black, binder styrene-butadiene rubber (SBR), and thickener sodium carboxymethyl cellulose (CMC) were thoroughly mixed in a deionized water solvent system at a mass ratio of 96:2:1:1. The mixture was then coated onto Cu foil, dried, and cold-pressed to obtain the negative electrode sheet with a compaction density of 1.65 g / cm³. 3 .

[0163] 3. Electrolyte

[0164] The electrolyte was prepared in a glove box (nitrogen content 99.999%, actual oxygen content 0.1 ppm, moisture content 0.1 ppm). First, the corresponding solid lithium salt and solid additives were weighed into the electrolyte sample bottle according to the mass percentage. Then, the corresponding mass percentages of solvent and liquid additives were added to the sample bottle in sequence and mixed thoroughly to obtain the electrolyte with the corresponding formula.

[0165] The lithium salt is LiPF6, which has a mass content of 13% in the electrolyte; the solvent is a mixed solvent composed of ethylene carbonate (EC), ethyl methyl carbonate (EMC) and diethyl carbonate (DEC) in a mass ratio of 3:5:2.

[0166] The additives include a first additive and a second additive. The first additive includes compound 1 and hexamethylene diisocyanate (HDI), with a mass content in the electrolyte of 1% compound 1 and 0.2% HDI. The second additive includes lithium difluorophosphate (LiPO2F2), vinylene carbonate (VC), and 1,3-propanesulfonate lactone (PS), with a mass content in the electrolyte of 1% LiPO2F2, 0.5% VC, and 1% PS.

[0167] The structural formula of compound 1 is:

[0168] 4. Separating membrane

[0169] A coated isolation membrane was obtained by using 9μm polyethylene as the base film and coating the base film with a 3μm thick nano-alumina coating.

[0170] 5. Battery assembly

[0171] The prepared positive electrode, separator, and negative electrode are stacked sequentially, with the separator positioned between the positive and negative electrodes to provide isolation, resulting in a bare cell. The bare cell is then placed in an aluminum-plastic film, baked at 80°C to remove moisture, injected with electrolyte, and sealed. After further processing, including standing, hot and cold pressing, formation, clamping, and capacity testing, the finished soft-pack nickel-cobalt-manganese battery is obtained.

[0172] Example 2

[0173] The difference between this embodiment and Embodiment 1 is that compound 1 in the first additive is replaced with an equal mass of compound 2, and the mass content of HDI in the electrolyte is 0.1% or 0.2%.

[0174] The structural formula of compound 2 is:

[0175] Example 3

[0176] The difference between this embodiment and Embodiment 1 is that compound 1 in the first additive is replaced with an equal mass of compound 3, and the mass content of HDI in the electrolyte is 0.2% or 0.5%.

[0177] The structural formula of compound 3 is:

[0178] Example 4

[0179] The difference between this embodiment and Embodiment 1 is that compound 1 in the first additive is replaced with an equal mass of compound 4, and the mass content of HDI in the electrolyte is 0.2% or 1%.

[0180] The structural formula of compound 4 is:

[0181] Example 5

[0182] The difference between this embodiment and Embodiment 1 is that compound 1 in the first additive is replaced with an equal mass of compound 5.

[0183] The structural formula of compound 5 is:

[0184] Example 6

[0185] The difference between this embodiment and Embodiment 1 is that compound 1 in the first additive is replaced with an equal mass of compound 6.

[0186] The structural formula of compound 6 is:

[0187] Example 7

[0188] The difference between this embodiment and Embodiment 1 is that Compound 6 is added to the first additive at the same time, and the mass content of Compound 1 and Compound 6 in the electrolyte is adjusted to 0.5%.

[0189] Comparative Example 1

[0190] The difference between this comparative example and Example 1 is that the first additive contains only compound 1 and does not contain HDI.

[0191] Comparative Example 2

[0192] The difference between this comparative example and Example 1 is that the first additive contains only HDI and does not contain compound 1.

[0193] Comparative Example 3

[0194] The difference between this comparative example and Example 1 is that the HDI in the first additive is replaced with an equal mass of succinic anhydride.

[0195] Comparative Example 4

[0196] The difference between this comparative example and Example 1 is that the HDI in the first additive is replaced with an equal mass of N,N'-dicyclohexylcarbodiimide.

[0197] The performance of the nickel-cobalt-manganese batteries in each embodiment and comparative example was tested using the following methods:

[0198] (1) Cyclic life at ambient temperature

[0199] After capacity testing, the fully charged battery is discharged at 25°C at 1C to 2.8V, and the initial discharge capacity is recorded as DC(1-R). Then, it is charged at 25°C at a constant current and constant voltage of 1C to 4.2V, with a cutoff current of 0.05C. After resting for 5 minutes, it is discharged again at 1C to 2.8V, and the discharge capacity is recorded as DC(2-R). This cycle is repeated N times until the discharge capacity DC(NR) < 80% of DC(1-R). The number of discharges N is recorded, and N is the room temperature cycle life.

[0200] (2) High-temperature cycle life

[0201] After capacity testing, the fully charged battery is placed in a 45°C incubator and discharged at 1C to 2.8V. The initial discharge capacity is recorded as DC(1-H). Then, it is charged at a constant current and voltage of 1C to 4.2V, with a cutoff current of 0.05C. After resting for 5 minutes, it is discharged again at 1C to 2.8V, and the discharge capacity is recorded as DC(2-H). This cycle is repeated N times until DC(NH) < 80% of DC(1-H). The number of discharges, N, is recorded as the high-temperature cycle life.

[0202] (3) Gas production rate and DCR (direct current resistance) growth rate during high-temperature storage

[0203] After being fully charged at room temperature (25℃), the battery was left to stand for 30 minutes, then discharged at 4C for 30 seconds until it reached 2.8V. The initial full-charge discharge rate (DCR) (0-S) was recorded, and the initial cell volume (Vol(0-S)) was measured simultaneously. The battery was then stored in a 60℃ constant temperature chamber for n days. After being removed, the battery was charged at room temperature with a constant current and voltage of 1C to 4.2V, with a cutoff current of 0.05C. After standing for 30 minutes, the battery was discharged at 4C for 30 seconds, and the full-charge discharge rate (DCR) (nS) after n days of storage was recorded. The DCR growth rate after n days of high-temperature storage is calculated as 100% * [DCR(nS) - DCR(0-S)] / DCR(0-S). Simultaneously, the cell volume (Vol(nS)) after n days was measured, and the gas production rate after n days of high-temperature storage is calculated as 100% * [Vol(nS) - Vol(0-S)] / Vol(0-S).

[0204] The test results are shown in Table 1 below.

[0205] [Table 1]

[0206]

[0207] 1) Gas production rate during high-temperature storage

[0208] Since the gas production in the battery mainly comes from the decomposition of the electrolyte, the higher the gas production rate during high-temperature storage, the easier the electrolyte is to decompose and the worse its stability. Conversely, the lower the gas production during high-temperature storage, the less likely the electrolyte is to decompose and the higher its stability.

[0209] Test results show that when the first additive includes compound 1 alone or HDI alone (i.e., Comparative Examples 1 and 2), the battery exhibits a higher gas production rate during 60-day high-temperature storage. However, in Examples 1 to 7, when the first additive, composed of fluorosulfonamide compounds (such as compounds 1 to 6) and HDI, was added to the electrolyte, the resulting battery exhibited a gas production rate of only 8.3% to 11.3% during 60-day high-temperature storage, which is lower than that of Comparative Examples 1 and 2. This indicates that combining fluorosulfonamide compounds with isocyanate compounds can effectively improve the stability of the electrolyte, making it less prone to decomposition.

[0210] The improved electrolyte stability in Examples 1-7 is primarily due to the synergistic effect of fluorosulfonamide compounds and isocyanate compounds. The fluorine, nitrogen, and sulfur groups in the fluorosulfonamide compounds facilitate the formation of a solid electrolyte interfacial film rich in inorganic components such as LiF, Li3N, and Li2S on the electrode surface. These inorganic components possess excellent chemical stability, enhancing the stability of the solid electrolyte interfacial film. Since the solid electrolyte interfacial film is formed by the redox decomposition of the electrolyte and its deposition on the electrode material surface, improving the stability of the solid electrolyte interfacial film reduces electrolyte decomposition during battery cycling, thus improving electrolyte stability. Simultaneously, the sulfur atoms in the compounds have a complexing effect on transition metals in the positive electrode active material, inhibiting their dissolution and migration. Transition metals, in turn, promote electrolyte decomposition; therefore, inhibiting their dissolution and migration also inhibits electrolyte decomposition, further improving electrolyte stability.

[0211] Meanwhile, moisture causes electrolyte decomposition, generating HF during the process. The presence of HF directly accelerates electrolyte decomposition; furthermore, HF damages the solid electrolyte interfacial film on the electrode surface and corrodes the positive electrode active material. Damage to the solid electrolyte interfacial film continuously consumes electrolyte, exacerbating decomposition; while corrosion of the positive electrode active material causes the dissolution of transition metals, which in turn leads to electrolyte decomposition. The isocyanate compounds in the first additive react with water and HF, reducing their content in the electrolyte and acting as dehydrators and deacidifiers. Therefore, they can inhibit electrolyte decomposition caused by water and HF, improving electrolyte stability.

[0212] Therefore, the electrolyte exhibits excellent stability and is not easily decomposed due to the synergistic effect of fluorosulfonamides and isocyanates.

[0213] 2) High-temperature storage DCR growth rate

[0214] Fluorinated and nitrogen-containing groups in fluorosulfonamide compounds are beneficial for generating solid electrolyte interfacial films rich in inorganic components such as LiF and Li3N on the electrode surface. These inorganic components are very helpful in reducing interfacial impedance, thus reducing the high-temperature storage DCR growth rate of the battery.

[0215] Meanwhile, for high-nickel batteries, their impedance is usually correlated with nickel dissolution. As mentioned earlier, adding isocyanate compounds to the electrolyte can inhibit nickel dissolution, which is beneficial for reducing the DCR growth rate during high-temperature storage.

[0216] 3) Cycle life

[0217] Because the addition of fluorosulfonamide compounds (such as compounds 1-6) and HDI as a first additive to the electrolyte improves the stability of the electrolyte, making it less prone to decomposition, and also enhances the stability of the solid electrolyte interface film on the electrode surface, suppressing nickel dissolution, the loss of electrolyte and positive electrode active material is reduced during battery cycling, resulting in an improved high-temperature cycle life. It is worth noting that the room-temperature cycle life of Examples 1-7 is also significantly improved compared to Comparative Examples 1-2. This may be because the fluorosulfonamide compounds and HDI can also exert the effects described in 1) above at room temperature, improving the stability of the electrolyte at room temperature and suppressing nickel dissolution, thus improving the room-temperature cycle life of the battery.

[0218] 4) In addition, HDI in the first additive is usually used as a dehydrating and deacidifying agent in the electrolyte. It can react with water and acid to reduce the water and acid content in the electrolyte, thus compensating for the inability of fluorosulfonamide compounds to dehydrate and deacidify. Therefore, this application attempts to combine fluorosulfonamide compounds with other electrolyte additives that also have dehydrating and deacidifying effects, namely Comparative Examples 3 and 4, to investigate whether these combinations can also improve the stability of the electrolyte. Succinic anhydride in Comparative Example 3 and N,N'-dicyclohexylcarbodiimide in Comparative Example 4 can both react with water, and water usually causes the electrolyte to react and generate HF. Therefore, succinic anhydride and N,N'-dicyclohexylcarbodiimide are commonly used in electrolytes to achieve dehydration and deacidification effects. However, when compound 1 was used in combination with succinic anhydride or N,N'-dicyclohexylcarbodiimide, the gas production rate of the battery during 60-day high-temperature storage increased to 13.6% and 14.1%, respectively, which was higher than that of Examples 1 to 7. It is evident that combining fluorosulfonamide compounds with other dehydrating and deacidifying additives according to Comparative Examples 3 and 4 did not improve the electrolyte decomposition problem or enhance the electrolyte stability.

[0219] Corresponding to the high-temperature storage gas generation rate, according to the combination of Comparative Example 3 and Comparative Example 4, the high-temperature DCR growth rate of the battery also increased, while the room temperature cycle life and high-temperature cycle life both decreased.

[0220] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. An electrolyte, characterized in that, The additive includes a first additive comprising a fluorosulfonamide compound and an isocyanate compound, wherein the fluorosulfonamide compound comprises the structure shown in formula (1): R1 and R2 each independently include one of hydrogen, fluorine, substituted or unsubstituted alkane group, substituted or unsubstituted alkene group, substituted or unsubstituted alkyne group, substituted or unsubstituted alkane carbonyl group, and substituted or unsubstituted alkane nitrile group, and at least one of R1 and R2 contains fluorine. R3 includes one of the following: substituted or unsubstituted alkane group, substituted or unsubstituted alkane carbonyl group, substituted or unsubstituted aromatic group, substituted or unsubstituted alkoxy group, or substituted or unsubstituted heterocyclic group.

2. The electrolyte according to claim 1, characterized in that, The total number of fluorine atoms in both R1 and R2 is 1 to 3.

3. The electrolyte according to claim 1 or 2, characterized in that, At least one of R1 and R2 includes fluorine or a fluorinated substituted alkane group.

4. The electrolyte according to claim 3, characterized in that, R1 includes one of fluorine or fluorinated alkane groups, and R2 includes one of substituted or unsubstituted alkane groups, substituted or unsubstituted alkenyl groups, substituted or unsubstituted alkyne groups, substituted or unsubstituted alkane carbonyl groups, or substituted or unsubstituted alkane nitrile groups.

5. The electrolyte according to claim 3 or 4, characterized in that, The fluorinated alkane groups include fluorinated C1 to C6 alkane groups.

6. The electrolyte according to any one of claims 1 to 5, characterized in that, R3 includes substituted or unsubstituted heterocyclic groups.

7. The electrolyte according to claim 6, characterized in that, The heterocyclic group includes a thiophene group.

8. The electrolyte according to any one of claims 1 to 7, characterized in that, The fluorosulfonamide compounds include one or more of the following compounds 1 to 6:

9. The electrolyte according to any one of claims 1 to 8, characterized in that, The fluorosulfonamide compound has a mass content of 0.1% to 10% in the electrolyte.

10. The electrolyte according to claim 9, characterized in that, The fluorosulfonamide compound has a mass content of 0.1% to 5% in the electrolyte.

11. The electrolyte according to any one of claims 1 to 10, characterized in that, The isocyanate compounds include one or more of hexamethylene diisocyanate, triallyl isocyanurate, p-toluenesulfonyl isocyanate, and isophthalic diisocyanate.

12. The electrolyte according to any one of claims 1 to 11, characterized in that, The isocyanate compound has a mass content of 0.1% to 2% in the electrolyte.

13. The electrolyte according to claim 12, characterized in that, The isocyanate compound has a mass content of 0.2% to 0.5% in the electrolyte.

14. The electrolyte according to any one of claims 1 to 13, characterized in that, The electrolyte further includes a second additive, which includes one or more of the following: cyclic carbonate electrolyte additives, cyclic sulfonyl lactone electrolyte additives, cyclic sulfate electrolyte additives, and lithium salt electrolyte additives.

15. The electrolyte according to claim 14, characterized in that, The cyclic carbonate electrolyte additives include one or more of vinylene carbonate, fluoroethylene carbonate, and ethylene ethylene carbonate; and / or, The cyclic sulfonyl lactone electrolyte additive includes one or more of 1,3-propanesulfonyl lactone and 1,3-propenesulfonyl lactone; and / or The cyclic sulfate electrolyte additives include vinyl sulfate; and / or, The lithium salt electrolyte additives include one or more of lithium difluorophosphate, lithium difluorooxalate borate, lithium dioxalate borate, lithium tetrafluoroborate, and lithium difluorooxalate phosphate.

16. The electrolyte according to claim 14 or 15, characterized in that, The second additive has a mass content of 0.1% to 20% in the electrolyte.

17. The electrolyte according to claim 16, characterized in that, The second additive has a mass content of 0.2% to 5% in the electrolyte.

18. The electrolyte according to any one of claims 15 to 17, characterized in that, The lithium salt electrolyte additive has a mass content of 0.5% to 2% in the electrolyte; and / or, The cyclic carbonate electrolyte additive is present in the electrolyte at a mass content of 0.2% to 1%; and / or, The cyclic sulfonyl lactone electrolyte additive has a mass content of 0.1% to 2% in the electrolyte; and / or, The cyclic sulfate electrolyte additive has a mass content of 0.5% to 1% in the electrolyte.

19. A single battery cell, characterized in that, Includes the electrolyte described in any one of claims 1 to 18.

20. A battery device, characterized in that, Includes multiple battery cells as described in claim 19.

21. An energy storage device, characterized in that, It includes a battery cell as described in claim 19 or a battery device as described in claim 20, wherein the battery cell or the battery device is used to store or provide electrical energy.

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