Electrolyte, battery monomer and electric device

Abstract

The invention relates to an electrolyte, a battery monomer and a power utilization device, the electrolyte comprises an acidic material and an additive which are connected in a coordination mode, and the additive comprises a carbodiimide compound and a trimethylsilyl compound.

Description

Technical Field

[0001] The present application relates to an electrolyte, a battery cell and an electrical device. Background Art

[0002] Battery cells have the characteristics of high capacity and long life, so they are widely used in electronic devices, such as mobile phones, laptops, battery cars, electric cars, electric airplanes, electric ships, electric toy cars, electric toy ships, electric toy airplanes and electric tools, etc. Due to the great progress made in battery cells, higher requirements are placed on the performance of battery cells. In order to improve the performance of battery cells, the electrolyte in the battery cells is usually optimized and improved.

[0003] However, when the electrolyte is currently applied to battery cells, the reliability and cycle performance of the battery cells are still relatively poor. Summary of the invention

[0004] The present application provides an electrolyte, a battery cell and an electrical device. The use reliability and cycle performance of the battery cell described in the present application can be improved.

[0005] In a first aspect, an embodiment of the present application provides an electrolyte, wherein the electrolyte includes an acidic substance and an additive connected in a coordination manner, wherein the additive includes a carbodiimide compound and a trimethylsilyl compound.

[0006] Therefore, in the embodiment of the present application, when the electrolyte includes both carbodiimide compounds and trimethylsilyl compounds, the carbodiimide compounds and trimethylsilyl compounds may form hydrogen bonds, so that the wetting performance of the two in the electrolyte system is improved, especially the wetting performance in the polar system is improved, so that the dispersion of the carbodiimide compounds and trimethylsilyl compounds in the electrolyte system is more uniform, and the carbodiimide compounds and trimethylsilyl compounds can more fully contact the acidic substances in the electrolyte system. The carbodiimide compounds and trimethylsilyl compounds cooperate with each other and coordinate with the acidic substances to form coordination compounds, thereby reducing the content of acidic substances in the electrolyte system and improving the structural stability of the electrolyte itself. When the electrolyte is applied to battery cells, the reliability and cycle performance of the battery cells can be improved.

[0007] In some embodiments, based on the total mass of the electrolyte, the ratio of the mass content of the carbodiimide compound to the mass content of the trimethylsilyl compound is 0.01 to 1.0; when the ratio of the mass content of the carbodiimide compound to the mass content of the trimethylsilyl compound is within the above range, the carbodiimide compound can play a more important coordination role with acidic substances such as HF or H +A strong coordination effect occurs, and the formed coordination compound is more stable, which is more conducive to reducing the HF content.

[0008] In some embodiments, the mass content of the carbodiimide compound is 0.001% to 0.100%; or the mass content of the trimethylsilane compound is 0.001% to 0.100%. When the mass content of the carbodiimide compound is within the above range, it is beneficial for the carbodiimide compound to form a coordination compound with HF, thereby reducing the HF content, improving the stability of the electrolyte system, and improving the cycle performance of the battery cell. When the mass content of the trimethylsilyl compound is within the above range, it is beneficial for the trimethylsilyl compound to form a coordination compound with HF, thereby reducing the HF content, improving the stability of the electrolyte system, and improving the cycle performance of the battery cell.

[0009] In some embodiments, the carbodiimide compound includes a compound represented by formula (A),

[0010] R 11 -N=C=NR 12 Formula (A),

[0011] In formula (A),

[0012] R 11 and R 12 Each independently includes at least one of a substituted or unsubstituted C2 to C10 chain alkyl group, a substituted or unsubstituted C3 to C12 cycloalkyl group, a substituted or unsubstituted C2 to C10 dimethylaminoalkyl group or an alkylsilyl group;

[0013] In some embodiments, R 11 and R 12 Each independently includes at least one of a substituted or unsubstituted C2 to C5 chain alkyl group, a substituted or unsubstituted C3 to C6 cycloalkyl group, a substituted or unsubstituted C2 to C5 dimethylaminoalkyl group or an alkylsilyl group.

[0014] Therefore, in the embodiment of the present application, the chain length of the carbodiimide compound is relatively short, which is conducive to forming a hydrogen bond with the trimethylsilyl compound. The shorter the chain length of the carbodiimide compound, the smaller the steric hindrance, and the more conducive it is to forming a hydrogen bond with the trimethylsilyl compound; and as the chain length of the carbodiimide compound becomes shorter, R 11 and R 12 The smaller the interference effect, the easier it is for the core structure of the carbodiimide compound to coordinate with HF.

[0015] In some embodiments, the carbodiimide compound includes at least one of the compounds represented by formula (A-1) to the compounds represented by formula (A-6),

[0016]

[0017]

[0018] In some embodiments, the trimethylsilyl compound includes a compound represented by formula (B),

[0019]

[0020] In formula (B),

[0021] R2 includes substituted or unsubstituted C2 to C10 alkyl, substituted or unsubstituted C6 to C10 aryl or -MR 21 At least one of: M includes at least one of an oxygen atom, a sulfur atom, a selenium atom or a tellurium atom; R 21 including substituted or unsubstituted C6 to C10 aryl groups;

[0022] Optionally,

[0023] R2 includes substituted or unsubstituted C2 to C5 alkyl, substituted or unsubstituted C6 to C8 aryl or -MR 21 At least one of R 21 Substituted or unsubstituted C6 to C8 aryl groups are included.

[0024] Therefore, the chain length of the trimethylsilyl compound in the embodiment of the present application is relatively short, which is conducive to the formation of hydrogen bonds with the carbodiimide compound. The shorter the chain length of the trimethylsilyl compound, the smaller the steric hindrance, and the more conducive it is to the formation of hydrogen bonds with the carbodiimide compound; and as the chain length of the carbodiimide compound becomes shorter, the interference effect of R2 becomes smaller, and the core structure of the carbodiimide compound is more likely to coordinate with HF.

[0025] In some embodiments, the trimethylsilyl compound includes at least one of the compounds represented by formula (B-1) to the compounds represented by formula (B-7),

[0026]

[0027]

[0028] In some embodiments, the electrolyte includes an organic solvent, and the organic solvent includes at least one of a cyclic carbonate solvent and a linear carbonate solvent; optionally, the cyclic carbonate solvent includes one or more of ethylene carbonate EC, propylene carbonate PC, vinyl carbonate VC, vinyl ethylene carbonate VEC, dioctyl carbonate CC, ethylene carbonate EC, or propylene carbonate PC; the linear carbonate solvent includes one or more of ethyl allyl carbonate AEC, diphenyl carbonate DPC, methyl allyl carbonate MAC, methyl ethyl carbonate MEC, dimethyl carbonate DMC, diethyl carbonate DEC, methyl propyl carbonate MPC, or ethyl propyl carbonate EPC. Cyclic carbonate solvents have a higher dielectric constant and can improve the ionic conductivity of the electrolyte; linear carbonate solvents have a lower viscosity and can improve the migration rate of active ions such as lithium ions in the electrolyte.

[0029] In some embodiments, the electrolyte includes a lithium salt, and the lithium salt includes at least one of lithium hexafluorophosphate LiPF6, lithium perchlorate LiClO4, lithium hexafluoroarsenate LiAsF6, lithium bis(trifluoromethanesulfonyl)imide, or lithium trifluoromethanesulfonate. The lithium salt may carry a trace of acidic substances such as hydrogen fluoride HF, and the water or alcohol carried in the organic solvent can further react with the above lithium salt to generate HF, increasing the HF content; and the carbodiimide compound and trimethylsilyl compound in the embodiment of the present application can react strongly with HF to reduce the HF content in the electrolyte system.

[0030] In some embodiments, the HF content in the electrolyte is less than or equal to 1 ppm. Under the action of the carbodiimide compound and the trimethylsilyl compound, the additive in the electrolyte can effectively reduce the HF content to a lower range.

[0031] In a second aspect, the present application further proposes a battery cell, wherein the battery cell comprises the electrolyte as described in any embodiment of the first aspect of the present application.

[0032] In a third aspect, the present application further proposes an electrical device, comprising a battery cell as described in any embodiment of the third aspect of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments of the present application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the drawings without paying creative work.

[0034] Figure 1 It is a schematic diagram of an embodiment of a battery cell of the present application.

[0035] Figure 2 yes Figure 1 An exploded schematic diagram of an embodiment of a battery cell.

[0036] Figure 3 It is a schematic diagram of an embodiment of a battery module of the present application.

[0037] Figure 4 It is a schematic diagram of an embodiment of the battery pack of the present application.

[0038] Figure 5 yes Figure 4 An exploded schematic diagram of an embodiment of a battery pack is shown.

[0039] Figure 6 It is a schematic diagram of an embodiment of an electric device including the battery cell of the present application as a power source.

[0040] The drawings are not necessarily drawn to scale.

[0041] The following are the descriptions of the reference numerals:

[0042] 1. Battery pack; 2. Upper box; 3. Lower box; 4. Battery module;

[0043] 5. Battery cell; 51. Housing; 52. Electrode assembly;

[0044] 53. Cover plate;

[0045] 6. Electrical equipment. DETAILED DESCRIPTION

[0046] Hereinafter, the embodiments of the electrolyte, battery cells and electrical devices of the present application are specifically disclosed in detail with appropriate reference to the accompanying drawings. However, there may be cases where unnecessary detailed descriptions are omitted. For example, there are cases where detailed descriptions of well-known matters and repeated descriptions of actually the same structures are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the drawings and the following descriptions are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0047] "Scope" disclosed in the present application is limited in the form of lower limit and upper limit, and a given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a special range. The scope limited in this way can be including end values ​​or not including end values, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a scope. For example, if the scope of 60-120 and 80-110 is listed for a specific parameter, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range values ​​1 and 2 are listed, and if the maximum range values ​​3, 4 and 5 are listed, the following scope can be all expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In the present application, unless otherwise specified, the numerical range "ab" represents the abbreviation of any real number combination between a and b, wherein a and b are real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" are listed in this document, and "0-5" is just an abbreviation of these numerical combinations. In addition, when a parameter is expressed as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0048] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0049] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0050] If there is no special explanation, all steps of the present application can be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), which means that step (c) may be added to the method in any order. For example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0051] The term "chain alkyl" encompasses straight and branched alkyl groups. For example, the alkyl group may be a C1 to C50 alkyl group, a C1 to C40 alkyl group, a C1 to C30 alkyl group, a C1 to C20 alkyl group, a C1 to C12 alkyl group, a C1 to C10 alkyl group, a C1 to C6 alkyl group, a C1 to C4 alkyl group. In certain embodiments, the alkyl group includes a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a cyclobutyl group, a pentyl group, an isopentyl group, a neopentyl group, a tert-pentyl group, a cyclopentyl group, a hexyl group, a cyclohexyl group, a heptyl group, a cycloheptyl group, an octyl group, a cyclooctyl group, a nonyl group, and a decyl group. In addition, the alkyl group may be optionally substituted. The term "haloalkyl" refers to an alkyl group in which a hydrogen atom is partially or completely replaced by a halogen atom, and the term "halogen atom" refers to a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, and the like.

[0052] The term "cycloalkyl" refers to a closed alkyl ring system. For example, the cycloalkyl can be a C3 to C50 cycloalkyl, a C3 to C40 cycloalkyl, a C3 to C30 cycloalkyl, a C3 to C20 cycloalkyl, a C3 to C12 cycloalkyl, a C3 to C8 cycloalkyl, wherein the C3 to C8 cycloalkyl refers to a cycloalkyl containing 3 to 8 carbon atoms for forming a ring. In addition, the cycloalkyl can be optionally substituted, and the carbon atoms in the cycloalkyl ring are replaced by heteroatoms, which can include nitrogen atoms, oxygen atoms, sulfur atoms, etc.

[0053] The term "aryl" refers to a closed aromatic ring or ring system. For example, aryl can be C6 to C50 aryl, C6 to C40 aryl, C6 to C30 aryl, C6 to C20 aryl, C6 to C10 aryl, wherein C6 to C30 aryl refers to containing 6 to 30 carbon atoms for forming a ring. In certain embodiments, aryl includes phenyl, naphthyl, phenanthrenyl, anthracenyl, biphenyl, triphenylene, pyrenyl, spiro bifluorenyl, pyrenyl, peryl, indenyl and azulenyl etc. In addition, aryl can be optionally substituted, and carbon atoms in the aryl ring are replaced by heteroatoms, and heteroatoms can include nitrogen atoms, oxygen atoms, sulphur atoms etc.

[0054] The term "halogen atom" means a fluorine atom, a chlorine atom, a bromine atom or the like.

[0055] The term "hydrogen" refers to 1H (protium, H), 2H (deuterium, D) or 3H (tritium, T). In various embodiments, "hydrogen" may be 1H (protium, H).

[0056] In various places of this specification, the substituent of compound is disclosed with group or scope.It is clearly expected that this description includes each individual subcombination of the member of these groups and scope.For example, it is clearly expected that the term "C1 to C8 alkyl" discloses C1, C2, C3, C4, C5, C6, C7, C8, C1 to C8, C1 to C7, C1 to C6, C1 to C5, C1 to C4, C1 to C3, C1 to C2, C2 to C8, C2 to C7, C2 to C6, C2 to C5, C2 to C4, C2 to C3, C3 to C8, C3 to C7, C3 to C6, C3 to C5, C3 to C4, C4 to C8, C4 to C7, C4 to C6, C4 to C5, C5 to C8, C5 to C7, C5 to C6, C6 to C8, C6 to C7 and C7 to C8 alkyl.

[0057] As other examples, the integers in the range of 5 to 40 are specifically intended to disclose individually 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, and 40; the integers in the range of 1 to 20 are specifically intended to disclose individually 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, and 20. Accordingly, other groups or ranges are specifically contemplated.

[0058] When the above groups are substituted, the substituents may be independently selected from halogen atoms or heteroatoms.

[0059] The electrolyte usually contains trace amounts of acidic substances such as hydrogen fluoride HF. When the HF content is too high, the electrolyte may decompose, resulting in poor stability of the electrolyte itself. In addition, since HF is extremely corrosive, during the contact between the electrolyte and the positive electrode active material, the electrolyte can react with the positive electrode active material, resulting in decomposition of the positive electrode active material, and the transition metal ions in the positive electrode active material are dissolved into the electrolyte. On the one hand, the dissolution of the transition metal ions may cause structural collapse of the positive electrode active material and reduce the structural stability of the positive electrode sheet. On the other hand, the transition metal ions migrate to the surface of the negative electrode sheet through the electrolyte, which may cause the SEI film on the surface of the negative electrode sheet to be destroyed, thereby increasing the risk of side reactions occurring when the negative electrode sheet and the electrolyte are in direct contact, and reducing the cycle stability of the battery cell.

[0060] In view of the above problems, the embodiments of the present application add specific additives to the electrolyte, the additives include carbodiimide compounds and trimethylsilyl compounds, such additives can be connected with acidic substances in a coordinated manner to form coordination compounds, reduce the content of acidic substances in the electrolyte, improve the stability of the electrolyte itself, and reduce the risk of side reactions between the electrolyte and the positive electrode active material, thereby improving the cycle stability of the battery cell. The technical solution of the present application is described in detail below.

[0061] Electrolyte

[0062] In a first aspect, an embodiment of the present application proposes an electrolyte, the electrolyte comprising an acidic substance and an additive connected in a coordination manner, the additive comprising a carbodiimide compound and a trimethylsilyl compound.

[0063] The acidic substance refers to a substance having a pH value of less than 7.0 and exhibiting acidity, for example, the acidic substance includes hydrogen fluoride HF, or a substance containing free hydrogen ions.

[0064] In the case where the electrolyte includes both carbodiimide compounds and trimethylsilyl compounds, the carbodiimide compounds and trimethylsilyl compounds may form hydrogen bonds, thereby improving the wettability of the two in the electrolyte system, especially improving the wettability in the polar system, making the dispersion of the carbodiimide compounds and trimethylsilyl compounds in the electrolyte system more uniform, and the carbodiimide compounds and trimethylsilyl compounds can more fully contact with the acidic substances in the electrolyte system. The carbodiimide compounds and trimethylsilyl compounds cooperate with each other and coordinate with the acidic substances to form coordination compounds, thereby reducing the electrolyte. The content of acidic substances in the electrolyte system improves the structural stability of the electrolyte itself; for example, carbodiimide compounds can have a strong coordination effect with hydrogen ions or HF; trimethylsilyl compounds can have a strong coordination bond with HF; when carbodiimide compounds and trimethylsilyl compounds exist together, the two can have a strong coordination effect with HF to form a coordination compound with a stable structure, thereby reducing the content of HF in the electrolyte system, reducing the risk of side reactions between HF and other substances in the electrolyte, and improving the structural stability of the electrolyte itself. When the electrolyte is applied to battery cells, it can improve the reliability and cycle performance of the battery cells.

[0065] Due to the reduction of acidic substances, the transition metal ions dissolved in the positive electrode active material are reduced, which can improve the structural stability of the positive electrode active material itself, and can also improve the structural stability of the negative electrode sheet and improve the cycle performance of the battery cell.

[0066] In some embodiments, the ratio of the mass content of the carbodiimide compound to the mass content of the trimethylsilyl compound is 0.01 to 1.0. When the ratio of the mass content of the carbodiimide compound to the mass content of the trimethylsilyl compound is within the above range, the mass content of the carbodiimide compound is the same as the mass content of the trimethylsilyl compound, or the mass content of the carbodiimide compound is greater than the mass content of the trimethylsilyl compound, and the carbodiimide compound can play a more important coordination role with acidic substances such as HF or H + A strong coordination effect occurs, and the formed coordination compound is more stable, which is more conducive to reducing the HF content.

[0067] Illustratively, the ratio of the mass content of the carbodiimide compound to the mass content of the trimethylsilyl compound can be 0.01, 0.02, 0.04, 0.05, 0.08, 0.10, 0.12, 0.15, 0.18, 0.20, 0.23, 0.25, 0.28, 0.30, 0.32, 0.35, 0.40, 0.45, 0.50, 0.52, 0.55, 0.58, 0.60, 0.62, 0.65, 0.68, 0.70, 0.75, 0.80, 0.85, 0.90, 0.95, 1.00 or a range consisting of any two of the above values.

[0068] In some embodiments, the mass content of the carbodiimide compound is 0.001% to 0.100%. When the mass content of the carbodiimide compound is within the above range, it is beneficial for the carbodiimide compound and HF to form a coordination compound, thereby reducing the HF content, improving the stability of the electrolyte system, and improving the cycle performance of the battery monomer.

[0069] Illustratively, the mass content of the carbodiimide compound can be 0.001%, 0.002%, 0.003%, 0.004%, 0.005%, 0.006%, 0.007%, 0.008%, 0.009%, 0.010%, 0.050%, 0.060%, 0.070%, 0.080%, 0.090%, 0.100% or a range consisting of any two of the above values.

[0070] In some embodiments, the mass content of the trimethylsilyl compound is 0.001% to 0.100%. When the mass content of the trimethylsilyl compound is within the above range, it is beneficial for the trimethylsilyl compound to form a coordination compound with HF, thereby reducing the HF content, improving the stability of the electrolyte system, and improving the cycle performance of the battery monomer.

[0071] Illustratively, the mass content of the trimethylsilyl compound can be 0.001%, 0.002%, 0.003%, 0.004%, 0.005%, 0.006%, 0.007%, 0.008%, 0.009%, 0.010%, 0.050%, 0.060%, 0.070%, 0.080%, 0.090%, 0.100% or a range consisting of any two of the above values.

[0072] In some embodiments, the carbodiimide compound includes a compound represented by formula (A),

[0073] R 11 -N=C=NR 12 Formula (A),

[0074] In formula (A),

[0075] R 11 and R 12 Each independently includes at least one of a substituted or unsubstituted C2 to C10 chain alkyl group, a substituted or unsubstituted C3 to C12 cycloalkyl group, a substituted or unsubstituted C2 to C10 dimethylaminoalkyl group or an alkylsilyl group.

[0076] The chain length of the carbodiimide compound of the above structural formula is relatively short, which is conducive to forming hydrogen bonds with trimethylsilyl compounds. The shorter the chain length of the carbodiimide compound, the smaller the steric hindrance, and the more conducive it is to forming hydrogen bonds with trimethylsilyl compounds; and as the chain length of the carbodiimide compound becomes shorter, R 11 and R 12 The smaller the interference effect, the easier it is for the core structure of the carbodiimide compound to coordinate with HF. 11 and R 12 Each independently includes at least one of a substituted or unsubstituted C2 to C5 chain alkyl group, a substituted or unsubstituted C3 to C6 cycloalkyl group, a substituted or unsubstituted C2 to C5 dimethylaminoalkyl group or an alkylsilyl group.

[0077] Exemplarily, the carbodiimide compound includes at least one of the compounds represented by formula (A-1) to the compounds represented by formula (A-6),

[0078]

[0079]

[0080] in,

[0081] The compound represented by formula (A-1) is N,N-di-tert-butylcarbodiimide,

[0082] The compound represented by formula (A-2) is 1-tert-butyl-3-ethylcarbodiimide,

[0083] The compound represented by formula (A-3) is N,N'-diisopropylcarbodiimide,

[0084] The compound represented by formula (A-4) is dicyclohexylcarbodiimide,

[0085] The compound represented by formula (A-5) is 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide,

[0086] The compound represented by formula (A-6) is bis(trimethylsilyl)carbodiimide.

[0087] In some embodiments, the trimethylsilyl compound includes a compound represented by formula (B),

[0088]

[0089] In formula (B),

[0090] R2 includes substituted or unsubstituted C2 to C10 alkyl, substituted or unsubstituted C6 to C10 aryl or -MR 21 At least one of: M includes at least one of an oxygen atom, a sulfur atom, a selenium atom or a tellurium atom; R 21 Substituted or unsubstituted C6 to C10 aryl groups are included.

[0091] The chain length of the trimethylsilyl compound of the above structural formula is relatively short, which is conducive to forming hydrogen bonds with carbodiimide compounds. The shorter the chain length of the trimethylsilyl compound, the smaller the steric hindrance, and the more conducive it is to forming hydrogen bonds with carbodiimide compounds; and as the chain length of the carbodiimide compound becomes shorter, the interference effect of R2 becomes smaller, and the core structure of the carbodiimide compound is more likely to coordinate with HF. Optionally, R2 includes substituted or unsubstituted C2 to C5 alkyl, substituted or unsubstituted C6 to C8 aryl or -MR 21 At least one of R 21 Substituted or unsubstituted C6 to C8 aryl groups are included.

[0092] Exemplarily, the trimethylsilyl compound includes at least one of the compounds represented by formula (B-1) to the compounds represented by formula (B-7),

[0093]

[0094] in,

[0095] The compound represented by formula (B-1) is ethyltrimethylsilane,

[0096] The compound represented by formula (B-2) is isopropoxytrimethylsilane,

[0097] The compound represented by formula (B-3) is benzyltrimethylsilane,

[0098] The compound represented by formula (B-4) is p-tolyltrimethylsilane,

[0099] The compound represented by formula (B-5) is phenylthiotrimethylsilane,

[0100] The compound represented by formula (B-6) is (2-allylphenoxy)trimethylsilane,

[0101] The compound represented by formula (B-7) is (phenylselenol)trimethylsilane.

[0102] In some embodiments, the electrolyte further includes an organic solvent, and the organic solvent includes at least one of a cyclic carbonate solvent and a linear carbonate solvent. The cyclic carbonate solvent has a high dielectric constant and can improve the ionic conductivity of the electrolyte; the linear carbonate solvent has a low viscosity and can improve the migration rate of active ions such as lithium ions in the electrolyte. The cyclic carbonate solvent and the linear carbonate solvent are used in combination, so that the electrolyte has a high dielectric constant and low viscosity, which can improve the ionic conductivity of the electrolyte; and the electrochemical stability of the electrolyte is high, and the electrochemical window is significantly improved.

[0103] The organic solvent may introduce a trace amount of water or alcohol, which can react with the lithium salt in the electrolyte to generate hydrogen fluoride, thereby possibly increasing the concentration of hydrogen fluoride HF. The carbodiimide compounds and trimethylsilyl compounds in the embodiments of the present application can undergo a strong coordination reaction with HF, thereby reducing the HF content in the electrolyte system.

[0104] In some embodiments, the mass content of the organic solvent is 30% to 90% based on the total mass of the electrolyte. For example, the mass content of the organic solvent can be 30%, 35%, 40%, 45%, 50%, 52%, 53%, 55%, 56%, 57%, 58%, 59%, 60%, 62%, 65%, 66%, 68%, 70%, 72%, 75%, 78%, 80%, 82%, 85%, 88%, 90% or a range consisting of any two of the above values.

[0105] Illustratively, the cyclic carbonate solvent includes one or more of ethylene carbonate EC, propylene carbonate PC, vinylene carbonate VC, vinyl ethylene carbonate VEC, dioctyl carbonate CC, ethylene carbonate EC, or propylene carbonate PC.

[0106] Illustratively, the linear carbonate solvent includes one or more of ethyl allyl carbonate AEC, diphenyl carbonate DPC, methyl allyl carbonate MAC, methyl ethyl carbonate MEC, dimethyl carbonate DMC, diethyl carbonate DEC, methyl propyl carbonate MPC or ethyl propyl carbonate EPC.

[0107] In some embodiments, the electrolyte includes a lithium salt, and the lithium salt includes at least one of lithium hexafluorophosphate LiPF6, lithium perchlorate LiClO4, lithium hexafluoroarsenate LiAsF6, lithium bis(trifluoromethanesulfonyl)imide, or lithium trifluoromethanesulfonate. Optionally, the lithium salt includes at least one of lithium hexafluorophosphate LiPF6, lithium perchlorate LiClO4, and lithium hexafluoroarsenate LiAsF6. The lithium salt may carry a trace amount of acidic substances such as hydrogen fluoride HF, and the water or alcohol carried in the organic solvent can further react with the above lithium salt to generate HF, thereby increasing the HF content; and the carbodiimide compounds and trimethylsilyl compounds in the embodiments of the present application can undergo a strong coordination reaction with HF, thereby reducing the HF content in the electrolyte system.

[0108] In some embodiments, the mass content of the lithium salt is 8% to 15% based on the total mass of the electrolyte.

[0109] Illustratively, the mass content of the lithium salt may be 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, or a range consisting of any two of the above values.

[0110] In some embodiments, the organic solvent may include but is not limited to at least one of a nitrile solvent, an ether solvent, and a sulfone solvent. For example, the nitrile solvent may include acetonitrile, etc., the ether solvent may include at least one of tetrahydrofuran and 2-methyltetrahydrofuran; the sulfone solvent may include at least one of cyclopentane sulfone (SF), dimethyl sulfone (MSM), ethyl methyl sulfone (EMS) or diethyl sulfone (ESE).

[0111] In some embodiments, the electrolyte may further include additives. For example, the additives may include film-forming additives such as positive electrode film-forming additives, etc., and may also include additives that can improve certain battery properties, such as additives that improve battery overcharge performance, additives that improve battery high temperature performance, additives that improve battery low temperature power performance, etc.

[0112] In some embodiments, the HF content in the electrolyte is less than or equal to 1 ppm. Exemplarily, the HF content in the electrolyte is 1 ppm, 0.9 ppm, 0.8 ppm, 0.7 ppm, 0.6 ppm, 0.5 ppm, 0.4 ppm, 0.3 ppm, 0.2 ppm, 0.1 ppm, 0 or a range consisting of any two of the above values. Under the action of carbodiimide compounds and trimethylsilyl compounds, the additive in the electrolyte can effectively reduce the HF content to a lower range.

[0113] In the embodiments of the present application, the type or content of each substance in the electrolyte has a well-known meaning in the art, and can be detected by using commonly used equipment and methods in the art. For example, the electrolyte is taken as a sample, or the electrolyte in a fresh battery cell is taken as a sample for detection. For example, when detecting the HF content, the HF can be calculated by acid-base titration. + Among them, fresh battery cells refer to battery cells that have been cycled less than 10 times.

[0114] Battery Cell

[0115] In the second aspect, the present application proposes a battery cell, wherein the battery cell includes an electrolyte. The electrolyte includes the electrolyte of any embodiment of the first aspect of the present application. During the charge and discharge process of the battery cell, active ions are embedded and released back and forth between the positive electrode sheet and the negative electrode sheet, and the electrolyte plays a role in conducting active ions between the positive electrode sheet and the negative electrode sheet. By adopting the above electrolyte, the self-discharge performance and cycle performance of the battery cell can be improved.

[0116] [Positive electrode]

[0117] In some embodiments, the battery cell further includes a positive electrode tab.

[0118] The positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer disposed on at least one surface of the positive electrode current collector, wherein the positive electrode active material layer includes a positive electrode active material.

[0119] As an example, the positive electrode current collector has two surfaces facing each other in its thickness direction, and the positive electrode active material layer is disposed on any one or both of the two facing surfaces of the positive electrode current collector.

[0120] In some embodiments, the positive electrode current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer material base and a metal layer formed on at least one surface of the polymer material base. The composite current collector may be formed by forming a metal material (aluminum, aluminum 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.).

[0121] In some embodiments, the positive electrode active material may be a positive electrode active material for a battery cell known in the art. As an example, the positive electrode active material may include at least one of the following materials, a layered positive electrode active material (e.g., ternary, lithium nickelate / sodium, lithium cobaltate / sodium, lithium manganate / sodium, lithium-rich / sodium layered and rock salt phase layered materials), an olivine-type phosphate active material, a spinel structured positive electrode active material (e.g., spinel lithium manganate, spinel nickel lithium manganate, lithium-rich spinel lithium manganate, and lithium nickel lithium manganate, etc.).

[0122] For example, the general formula of the layered positive electrode active material is Li x A y Ni a Co b Mn c M (1-a-b-c) Y z , wherein 0≤x≤2.1, 0≤y≤2.1, and 0.9≤x+y≤2.1; 0≤a≤1, 0≤b≤1, 0≤c≤1, and 0.1≤a+b+c≤1; 1.8≤z≤3.5; A includes one or more of Na, K, and Mg; M includes one or more of B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Fe, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, and Ce; and Y includes one or more of O and F. Specifically, the layered positive electrode active material may include lithium cobalt oxide LCO, lithium nickel oxide LNO, lithium manganese oxide LMO, and the like.

[0123] Optionally, the layered positive electrode active material is a ternary material, for example, 0<a≤1, 0<b≤1, 0<c≤1, illustratively, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2(NCM333), LiNi 0.8 Co 0.1 Mn 0.1 O2(NCM811) and LiNi 0.5 Co 0.2Mn 0.3 O2 (NCM523) or more.

[0124] For example, the general formula of the olivine phosphate active material is Li x A y Me a M b P 1-c X c Y z , wherein 0≤x≤1.3, 0≤y≤1.3, and 0.9≤x+y≤1.3; 0.9≤a≤1.5, 0≤b≤0.5, and 0.9≤a+b≤1.5; 0≤c≤0.5; 3≤z≤5; A includes one or more of Na, K, and Mg; Me includes one or more of Mn, Fe, Co, and Ni; M includes one or more of B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, and Ce; X includes one or more of S, Si, Cl, B, C, and N; and Y includes one or more of O and F. Specifically, the olivine-type phosphate active material includes one or more of LiFePO4, LiMnPO4, LiNiPO4, and LiCoPO4.

[0125] For example, the general formula of the positive electrode active material of the spinel structure is Li x A y Mn a M 2-a Y z , wherein 0≤x≤2, 0≤y≤1, and 0.9≤x+y≤2; 0.5≤a≤2; 3≤z≤5; A includes one or more of Na, K, and Mg; M includes one or more of Ni, Co, B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Fe, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, and Ce; and Y includes one or more of O and F. Specifically, the positive active materials of the spinel structure include LiMn2O4, LiNi 0.5 Mn 1.5 O4、LiCr 0.3 Mn 1.7 O4、Li 1.1 Al 0.1 Mn 1.9 O4, Li2Mn2O4 and Li 1.5 One or more of Mn2O4.

[0126] The battery cell will be accompanied by the deintercalation and consumption of active ions such as Li during the charge and discharge process, and the molar content of Li in the battery cell is different when it is discharged to different states. In the list of positive electrode active materials in the embodiments of the present application, the molar content of Li is the initial state of the material, that is, the state before feeding. The positive electrode active material is used in the battery system, and the molar content of Li may change after charge and discharge cycles.

[0127] In the list of positive electrode active materials in the embodiments of the present application, the molar content of oxygen O is only a theoretical value. The release of oxygen from the lattice will cause the molar content of oxygen O to change. In reality, the molar content of oxygen O will fluctuate.

[0128] In some embodiments, the positive electrode active material layer may further include a binder. As an example, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylate resin.

[0129] In some embodiments, the positive electrode active material layer may further include a conductive agent. As an 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.

[0130] In some embodiments, the positive electrode sheet can be prepared in the following manner: the components for preparing the positive electrode sheet, such as the positive electrode active material, the conductive agent, the binder and any other components are dispersed in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; the positive electrode slurry is coated on the positive electrode collector, and after drying, cold pressing and other processes, the positive electrode sheet can be obtained.

[0131] [Negative electrode]

[0132] In some embodiments, the battery cell further includes a negative electrode tab.

[0133] In some embodiments, the negative electrode sheet includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector and including a negative electrode active material. For example, the negative electrode current collector has two surfaces opposite to each other in its thickness direction, and the negative electrode film layer is disposed on any one or both of the two opposite surfaces of the negative electrode current collector.

[0134] The negative electrode active material may be a negative electrode active material for a battery cell known in the art. As an example, the negative electrode active material may include but is not limited to at least one of natural graphite, artificial graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate. The silicon-based material may include at least one of elemental silicon, silicon oxide, silicon-carbon composite, silicon-nitrogen composite, and silicon alloy material. The tin-based material may include at least one of elemental tin, tin oxide, and tin alloy material.

[0135] In some embodiments, the negative electrode film layer may further include a negative electrode conductive agent. The embodiment of the present application has no particular restrictions on the type of the negative electrode conductive agent. As an example, the negative electrode conductive agent may include at least one of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers. In some embodiments, based on the total weight of the negative electrode film layer, the mass percentage of the negative electrode conductive agent is ≤5wt%.

[0136] In some embodiments, the negative electrode film layer may also optionally include a negative electrode binder. The embodiment of the present application has no particular restrictions on the type of the negative electrode binder. As an example, the negative electrode binder may include at least one of styrene-butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, water-based acrylic resin (e.g., polyacrylic acid PAA, polymethacrylic acid PMAA, sodium polyacrylate PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA) and carboxymethyl chitosan (CMCS). In some embodiments, based on the total weight of the negative electrode film layer, the mass percentage of the negative electrode binder is ≤5wt%.

[0137] In some embodiments, the negative electrode film layer may further include other additives. As an example, other additives may include thickeners, such as sodium carboxymethyl cellulose (CMC-Na), PTC thermistor materials, etc. In some embodiments, based on the total weight of the negative electrode film layer, the mass percentage of the other additives is ≤2wt%.

[0138] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. As an example of a metal foil, a copper foil may be used. The composite current collector may include a polymer material base layer and a metal material layer formed on at least one surface of the polymer material base layer. As an example, the metal material may include at least one of copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy. As an example, the polymer material base layer may include at least one of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS) and polyethylene (PE).

[0139] The negative electrode film layer is usually formed by coating the negative electrode slurry on the negative electrode current collector, drying and cold pressing. The negative electrode slurry is usually formed by dispersing the negative electrode active material, optional conductive agent, optional binder, and other optional auxiliary agents in a solvent and stirring them uniformly. The solvent can be N-methylpyrrolidone (NMP) or deionized water, but is not limited thereto.

[0140] The negative electrode plate does not exclude other additional functional layers in addition to the negative electrode film layer. For example, in some embodiments, the negative electrode plate described in the embodiments of the present application further includes a conductive primer layer (e.g., composed of a conductive agent and a binder) sandwiched between the negative electrode collector and the negative electrode film layer and disposed on the surface of the negative electrode collector. In some other embodiments, the negative electrode plate described in the embodiments of the present application further includes a protective layer covering the surface of the negative electrode film layer.

[0141] [Isolation film]

[0142] In some embodiments, the battery cell further includes a separator.

[0143] The present application has no particular limitation on the type of isolation membrane, and any known porous isolation membrane with good chemical stability and mechanical stability can be selected.

[0144] In some embodiments, the material of the isolation membrane may include at least one of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride. The isolation membrane may be a single-layer film or a multi-layer composite film, without particular limitation. When the isolation membrane is a multi-layer composite film, the materials of each layer may be the same or different, without particular limitation.

[0145] In some embodiments, the positive electrode sheet, the separator, and the negative electrode sheet may be formed into an electrode assembly by a winding process and / or a lamination process.

[0146] In some embodiments, the battery cell may include an outer packaging, which may be used to encapsulate the electrode assembly and the electrolyte.

[0147] In some embodiments, the outer packaging of the battery cell may be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer packaging of the battery cell may also be a soft package, such as a bag-type soft package. The material of the soft package may be plastic, such as at least one of polypropylene (PP), polybutylene terephthalate (PBT) and polybutylene succinate (PBS).

[0148] The present application has no particular restrictions on the shape of the battery cell, which can be cylindrical, square or any other shape. Figure 1 The battery cell 5 is a square structure as an example.

[0149] In some embodiments, Figure 2 As shown, the outer package may include a shell 51 and a cover plate 53. The shell 51 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate enclose a receiving cavity. The shell 51 has an opening connected to the receiving cavity, and the cover plate 53 is used to cover the opening to close the receiving cavity. The positive electrode sheet, the negative electrode sheet and the isolation film can form an electrode assembly 52 through a winding process and / or a lamination process. The electrode assembly 52 is encapsulated in the receiving cavity. The electrolyte is infiltrated in the electrode assembly 52. ​​The number of electrode assemblies 52 contained in the battery cell 5 can be one or more, which can be adjusted according to demand.

[0150] The preparation method of the battery cell of the present application is well known. In some embodiments, the positive electrode sheet, the separator, the negative electrode sheet and the electrolyte can be assembled to form a battery cell. As an example, the positive electrode sheet, the separator and the negative electrode sheet can be formed into an electrode assembly through a winding process and / or a lamination process, and the electrode assembly is placed in an outer package, and the electrolyte is injected after drying, and the battery cell is obtained through vacuum packaging, standing, forming, shaping and other processes.

[0151] In some embodiments of the present application, the battery cells according to the present application may be assembled into a battery module. The battery module may contain multiple battery cells, and the specific number may be adjusted according to the application and capacity of the battery module.

[0152] Figure 3 FIG. 4 is a schematic diagram of a battery module 4 as an example. Figure 3 As shown, in the battery module 4, the plurality of battery cells 5 may be arranged in sequence along the length direction of the battery module 4. Of course, they may also be arranged in any other manner. Further, the plurality of battery cells 5 may be fixed by fasteners.

[0153] Optionally, the battery module 4 may further include a housing having a receiving space, and the plurality of battery cells 5 are received in the receiving space.

[0154] In some embodiments, the battery modules described above may also be assembled into a battery pack, and the number of battery modules contained in the battery pack may be adjusted according to the application and capacity of the battery pack.

[0155] Figure 4 and Figure 5 FIG. 1 is a schematic diagram of a battery pack 1 as an example. Figure 4 and Figure 5 As shown, the battery pack 1 may include a battery box and a plurality of battery modules 4 disposed in the battery box. The battery box includes an upper box body 2 and a lower box body 3, wherein the upper box body 2 is used to cover the lower box body 3 and form a closed space for accommodating the battery modules 4. The plurality of battery modules 4 may be arranged in the battery box in any manner.

[0156] The battery according to the embodiment of the present application may include one battery cell or a plurality of battery cells. When the battery includes a plurality of battery cells, the battery may include a battery module or a battery pack.

[0157] Electrical devices

[0158] The third aspect of the embodiment of the present application provides an electric device, which includes at least one of the battery cells, battery modules or battery packs of the present application. The battery cells, battery modules or battery packs can be used as the power source of the electric device, and can also be used as the energy storage unit of the electric device. The electric device can be, but is not limited to, a mobile device (such as a mobile phone, a laptop computer, etc.), an electric vehicle (such as a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck, etc.), an electric train, a ship and a satellite, an energy storage system, etc.

[0159] The electrical device may select a battery cell, a battery module or a battery pack according to its usage requirements.

[0160] Figure 6 Schematic diagram of an exemplary electric device 6. The electric device 6 is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. In order to meet the requirements of the electric device 6 for high power and high energy density, a battery pack or a battery module may be used.

[0161] As another example, the electric device may be a mobile phone, a tablet computer, a notebook computer, etc. The electric device is usually required to be light and thin, and a battery cell may be used as a power source.

[0162] Example

[0163] The following embodiments describe the contents disclosed in the present application in more detail, and these embodiments are only used for illustrative explanations, because it is obvious to those skilled in the art that various modifications and changes are made within the scope of the present application disclosure. Unless otherwise stated, all parts, percentages and ratios reported in the following embodiments are based on mass, and all reagents used in the embodiments are commercially available or synthesized according to conventional methods, and can be used directly without further processing, and the instruments used in the embodiments are commercially available.

[0164] Preparation of Lithium Ion Batteries in Examples and Comparative Examples

[0165] 1. Preparation of positive electrode sheet

[0166] Aluminum foil with a thickness of 12 μm was used as the positive electrode current collector.

[0167] The positive electrode active material LiNi 0.5 Co 0.2 Mn 0.3 O2, conductive agent carbon black, and binder polyvinylidene fluoride (PVDF) are fully stirred and mixed in a proper amount of solvent NMP at a weight ratio of 97.5:1.4:1.1 to form a uniform positive electrode slurry; the positive electrode slurry is evenly coated on the surface of the positive electrode current collector aluminum foil, and after drying and cold pressing, a positive electrode sheet is obtained.

[0168] 2. Preparation of negative electrode sheet

[0169] A copper foil with a thickness of 8 μm was used as the negative electrode current collector.

[0170] The negative electrode active material artificial graphite, the binder styrene-butadiene rubber (SBR), the thickener sodium carboxymethyl cellulose (CMC-Na), and the conductive agent carbon black (Super P) are fully stirred and mixed in an appropriate amount of solvent deionized water at a weight ratio of 96.2:1.8:1.2:0.8 to form a uniform negative electrode slurry; the negative electrode slurry is evenly coated on the surface of the negative electrode current collector copper foil, and after drying and cold pressing, a negative electrode sheet is obtained.

[0171] 3. Isolation film

[0172] A porous polyethylene (PE) film was used as the isolation membrane.

[0173] 4. Preparation of electrolyte

[0174] In an environment where the water content is less than 10 ppm, an organic solvent, an additive and a lithium salt are uniformly mixed to obtain an electrolyte.

[0175] 5. Preparation of battery cells

[0176] The positive electrode sheet, the separator, and the negative electrode sheet are stacked in order, so that the separator is between the positive electrode sheet and the negative electrode sheet to play an isolating role, and then they are wound to obtain an electrode assembly; the electrode assembly is placed in an outer packaging shell, and after drying, the electrolyte is injected, and after vacuum packaging, standing, forming, shaping and other processes, a lithium-ion battery is obtained.

[0177] Example 1

[0178] The lithium ion battery is prepared by the above steps, and the preparation of the electrolyte includes:

[0179] In an environment with a water content of less than 10ppm, organic solvents ethylene carbonate EC and diethyl carbonate DMC are mixed in a volume ratio of 1:1 to obtain a mixed solvent, and additives and lithium salts are added to the mixed solvent and mixed evenly. The additives include dimethylaminopropyl ethylcarbonamide (0.002%) of the compound shown in formula (A-5), 1-tert-butyl-3-ethylcarbodiimide (0.001%) of the compound shown in formula (A-2) and isopropoxytrimethylsilane (0.003%) of the compound shown in formula (B-2), and the lithium salt includes 12% of lithium hexafluorophosphate LiPF6.

[0180] Comparative Example 1

[0181] A lithium ion battery was prepared by a method similar to that of Example 1. The difference from Example 1 is that the preparation of the electrolyte includes:

[0182] In an environment with a water content of less than 10 ppm, organic solvents ethylene carbonate EC and diethyl carbonate DMC are mixed in a volume ratio of 1:1 to obtain a mixed solvent, and lithium salt is added into the mixed solvent and mixed evenly, wherein the lithium salt includes 12% lithium hexafluorophosphate LiPF6.

[0183] Comparative Example 2

[0184] A lithium ion battery was prepared by a method similar to that of Example 1. The difference from Example 1 is that the preparation of the electrolyte includes:

[0185] In an environment with a water content of less than 10ppm, organic solvents ethylene carbonate EC and diethyl carbonate DMC are mixed in a volume ratio of 1:1 to obtain a mixed solvent, and additives and lithium salts are added to the mixed solvent and mixed evenly. The additives include dimethylaminopropyl ethylcarbonamide (0.002%) and 1-tert-butyl-3-ethylcarbodiimide (0.001%), and the lithium salt includes 12% lithium hexafluorophosphate LiPF6.

[0186] Comparative Example 3

[0187] A lithium ion battery was prepared by a method similar to that of Example 1. The difference from Example 1 is that the preparation of the electrolyte includes:

[0188] In an environment with a water content of less than 10 ppm, organic solvents ethylene carbonate EC and diethyl carbonate DMC are mixed in a volume ratio of 1:1 to obtain a mixed solvent, and additives and lithium salts are added to the mixed solvent and mixed evenly. The additives include isopropoxytrimethylsilane (0.003%), and the lithium salt includes 12% lithium hexafluorophosphate LiPF6.

[0189] Example 2-1

[0190] A lithium ion battery was prepared by a method similar to that of Example 1. The difference from Example 1 is that the preparation of the electrolyte includes:

[0191] In an environment with a water content of less than 10ppm, organic solvents ethylene carbonate EC and diethyl carbonate DMC are mixed in a volume ratio of 1:1 to obtain a mixed solvent, and additives and lithium salts are added to the mixed solvent and mixed evenly. The additives include the compounds di(trimethylsilyl)carbodiimide (0.003%) and isopropoxytrimethylsilane (0.003%) shown in formula (A-6), and the lithium salt includes 12% lithium hexafluorophosphate LiPF6.

[0192] Example 2-2

[0193] A lithium ion battery was prepared by a method similar to that of Example 1. The difference from Example 1 is that the preparation of the electrolyte includes:

[0194] In an environment with a water content of less than 10ppm, organic solvents ethylene carbonate EC and diethyl carbonate DMC are mixed in a volume ratio of 1:1 to obtain a mixed solvent, and additives and lithium salts are added to the mixed solvent and mixed evenly. The additives include dimethylaminopropyl ethylcarbonamide (0.002%) of the compound shown in formula (A-5), 1-tert-butyl-3-ethylcarbodiimide (0.001%) of the compound shown in formula (A-2) and phenylthiotrimethylsilane (0.003%) of the compound shown in formula (B-5), and the lithium salt includes 12% of lithium hexafluorophosphate LiPF6.

[0195] Example 2-3

[0196] A lithium ion battery was prepared by a method similar to that of Example 1. The difference from Example 1 is that the preparation of the electrolyte includes:

[0197] In an environment with a water content of less than 10ppm, organic solvents ethylene carbonate EC and diethyl carbonate DMC are mixed in a volume ratio of 1:1 to obtain a mixed solvent, and additives and lithium salts are added to the mixed solvent and mixed evenly. The additives include dimethylaminopropyl ethylcarbonamide (0.002%) of the compound shown in formula (A-5), 1-tert-butyl-3-ethylcarbodiimide (0.001%) of the compound shown in formula (A-2) and (2-allylphenoxy)trimethylsilane (0.003%) of the compound shown in formula (B-6), and the lithium salt includes 12% of lithium hexafluorophosphate LiPF6.

[0198] Example 3-1

[0199] A lithium ion battery was prepared by a method similar to that of Example 1. The difference from Example 1 is that the preparation of the electrolyte includes:

[0200] In an environment with a water content of less than 10ppm, organic solvents ethylene carbonate EC and diethyl carbonate DMC are mixed in a volume ratio of 1:1 to obtain a mixed solvent, and additives and lithium salts are added to the mixed solvent and mixed evenly. The additives include dimethylaminopropyl ethylcarbonamide (0.0005%) of the compound shown in formula (A-5), 1-tert-butyl-3-ethylcarbodiimide (0.0005%) of the compound shown in formula (A-2) and isopropoxytrimethylsilane (0.100%) of the compound shown in formula (B-2), and the lithium salt includes 12% of lithium hexafluorophosphate LiPF6.

[0201] Example 3-2

[0202] A lithium ion battery was prepared by a method similar to that of Example 1. The difference from Example 1 is that the preparation of the electrolyte includes:

[0203] In an environment with a water content of less than 10ppm, organic solvents ethylene carbonate EC and diethyl carbonate DMC are mixed in a volume ratio of 1:1 to obtain a mixed solvent, and additives and lithium salts are added to the mixed solvent and mixed evenly. The additives include dimethylaminopropyl ethylcarbonamide (0.002%) of the compound shown in formula (A-5), 1-tert-butyl-3-ethylcarbodiimide (0.003%) of the compound shown in formula (A-2) and isopropoxytrimethylsilane (0.100%) of the compound shown in formula (B-2), and the lithium salt includes 12% of lithium hexafluorophosphate LiPF6.

[0204] Example 3-3

[0205] A lithium ion battery was prepared by a method similar to that of Example 1. The difference from Example 1 is that the preparation of the electrolyte includes:

[0206] In an environment with a water content of less than 10ppm, organic solvents ethylene carbonate EC and diethyl carbonate DMC are mixed in a volume ratio of 1:1 to obtain a mixed solvent, and additives and lithium salts are added to the mixed solvent and mixed evenly. The additives include dimethylaminopropyl ethylcarbonamide (0.001%) of the compound shown in formula (A-5), 1-tert-butyl-3-ethylcarbodiimide (0.001%) of the compound shown in formula (A-2) and isopropoxytrimethylsilane (0.020%) of the compound shown in formula (B-2), and the lithium salt includes 12% of lithium hexafluorophosphate LiPF6.

[0207] Embodiment 3-4

[0208] A lithium ion battery was prepared by a method similar to that of Example 1. The difference from Example 1 is that the preparation of the electrolyte includes:

[0209] In an environment with a water content of less than 10ppm, organic solvents ethylene carbonate EC and diethyl carbonate DMC are mixed in a volume ratio of 1:1 to obtain a mixed solvent, and additives and lithium salts are added to the mixed solvent and mixed evenly. The additives include dimethylaminopropyl ethylcarboamide (0.001%) of the compound shown in formula (A-5), 1-tert-butyl-3-ethylcarbodiimide (0.001%) of the compound shown in formula (A-2) and isopropoxytrimethylsilane (0.004%) of the compound shown in formula (B-2), and the lithium salt includes 12% of lithium hexafluorophosphate LiPF6.

[0210] Embodiment 3-5

[0211] A lithium ion battery was prepared by a method similar to that of Example 1. The difference from Example 1 is that the preparation of the electrolyte includes:

[0212] In an environment with a water content of less than 10ppm, organic solvents ethylene carbonate EC and diethyl carbonate DMC are mixed in a volume ratio of 1:1 to obtain a mixed solvent, and additives and lithium salts are added to the mixed solvent and mixed evenly. The additives include dimethylaminopropyl ethylcarbonamide (0.0005%) of the compound shown in formula (A-5), 1-tert-butyl-3-ethylcarbodiimide (0.0005%) of the compound shown in formula (A-2) and isopropoxytrimethylsilane (0.080%) of the compound shown in formula (B-2), and the lithium salt includes 12% of lithium hexafluorophosphate LiPF6.

[0213] Embodiment 3-6

[0214] A lithium ion battery was prepared by a method similar to that of Example 1. The difference from Example 1 is that the preparation of the electrolyte includes:

[0215] In an environment with a water content of less than 10ppm, organic solvents ethylene carbonate EC and diethyl carbonate DMC are mixed in a volume ratio of 1:1 to obtain a mixed solvent, and additives and lithium salts are added to the mixed solvent and mixed evenly. The additives include dimethylaminopropyl ethylcarbonamide (0.001%) of the compound shown in formula (A-5), 1-tert-butyl-3-ethylcarbodiimide (0.010%) of the compound shown in formula (A-2) and isopropoxytrimethylsilane (0.001%) of the compound shown in formula (B-2), and the lithium salt includes 12% of lithium hexafluorophosphate LiPF6.

[0216] The relevant parameters of the embodiments and comparative examples are shown in Table 1.

[0217] Test Section

[0218] 1. Cycle performance test of lithium-ion batteries

[0219] At 25°C, the lithium-ion battery is charged to 4.25V at 2C constant current, then charged to 0.05C at 4.25V constant voltage, and then discharged to 2.8V at 1C constant current. This is a charge and discharge cycle. Taking the capacity of the first discharge as 100%, calculate the capacity retention rate of the battery after 500 cycles. The capacity retention rate of the battery after 500 cycles (%) = discharge capacity of the 500th cycle / capacity of the first discharge × 100%.

[0220] 2. K value test

[0221] The K value can be used to describe the physical quantity of the self-discharge rate of a battery cell. It can be calculated by dividing the open circuit voltage difference between two tests by the time interval △t between the two voltage tests. The formula is: K = (OCV2-OCV1) / △t. That is, K can represent the voltage drop per unit time. Generally speaking, the larger the K value, the faster the open circuit voltage drops or the larger the amplitude is, and there may be a micro-short circuit in the battery cell.

[0222] 3. HF content test

[0223] The electrolytes of the embodiments and comparative examples were stored at 25° C. for 15 days, and their contents were analyzed by acid-base titration test.

[0224] Test Results

[0225] The test results are shown in Table 1.

[0226] Table 1

[0227]

[0228]

[0229] In Table 1, the K value represents the K value obtained by testing at a time interval of 14 days.

[0230] It can be seen from Table 1 that, compared with Comparative Example 1, Comparative Example 2 and Comparative Example 3 respectively add additives to the electrolyte, carbodiimide compounds or trimethylsilyl compounds, which can react with HF, but the effect is weak and cannot effectively reduce the HF content.

[0231] In the embodiment of the present application, carbodiimide compounds and trimethylsilyl compounds are added to the electrolyte at the same time. The carbodiimide compounds and trimethylsilyl compounds cooperate with each other and form coordination compounds with acidic substances, which can significantly reduce the content of acidic substances in the electrolyte system and improve the structural stability of the electrolyte itself. By adjusting the mass ratio of carbodiimide compounds and trimethylsilyl compounds, especially when the ratio of the mass content of carbodiimide compounds to the mass content of the trimethylsilyl compounds is 0.01 to 1.0, the content of acidic substances in the electrolyte system can be further reduced.

[0232] Although illustrative embodiments have been demonstrated and described, those skilled in the art should understand that the above embodiments should not be construed as limitations on the present application, and that changes, substitutions and modifications may be made to the embodiments without departing from the spirit, principles and scope of the present application.

Claims

1. An electrolyte comprising an acidic substance and an additive connected in a coordination manner, wherein the additive comprises a carbodiimide compound and a trimethylsilyl compound.

2. The electrolyte according to claim 1, wherein the ratio of the mass content of the carbodiimide compound to the mass content of the trimethylsilyl compound is 0.01 to 1.0 based on the total mass of the electrolyte; Further optionally, The mass content of the carbodiimide compound is 0.001% to 0.100%; or The mass content of the trimethylsilane compound is 0.001% to 0.100%.

3. The electrolyte according to claim 1 or 2, wherein The carbodiimide compounds include compounds represented by formula (A), In formula (A), R 11 and R 12 Each independently includes at least one of a substituted or unsubstituted C2 to C10 chain alkyl group, a substituted or unsubstituted C3 to C12 cycloalkyl group, a substituted or unsubstituted C2 to C10 dimethylaminoalkyl group or an alkylsilyl group; Optionally, R 11 and R 12 Each independently includes at least one of a substituted or unsubstituted C2 to C5 chain alkyl group, a substituted or unsubstituted C3 to C6 cycloalkyl group, a substituted or unsubstituted C2 to C5 dimethylaminoalkyl group or an alkylsilyl group.

4. The electrolyte according to claim 3, wherein The carbodiimide compound includes at least one of the compounds represented by formula (A-1) to the compounds represented by formula (A-6), 5. The electrolyte according to any one of claims 1 to 4, wherein The trimethylsilyl compounds include compounds represented by formula (B), In formula (B), R2 includes substituted or unsubstituted C2 to C10 alkyl, substituted or unsubstituted C6 to C10 aryl or -MR 21 At least one of: M includes at least one of an oxygen atom, a sulfur atom, a selenium atom or a tellurium atom; R 21 including substituted or unsubstituted C6 to C10 aryl groups; Optionally, R2 includes substituted or unsubstituted C2 to C5 alkyl, substituted or unsubstituted C6 to C8 aryl or -MR 21 At least one of R 21 Included are substituted or unsubstituted C6 to C8 aryl groups.

6. The electrolyte according to claim 5, wherein The trimethylsilyl compound includes at least one of the compounds represented by formula (B-1) to the compounds represented by formula (B-7), 7. The electrolyte according to any one of claims 1 to 6, wherein The electrolyte includes an organic solvent, and the organic solvent includes at least one of a cyclic carbonate solvent and a linear carbonate solvent; Optionally, The cyclic carbonate solvent includes one or more of ethylene carbonate EC, propylene carbonate PC, vinylene carbonate VC, vinyl ethylene carbonate VEC, dioctyl carbonate CC, ethylene carbonate EC or propylene carbonate PC; The linear carbonate solvent includes one or more of ethyl allyl carbonate AEC, diphenyl carbonate DPC, methyl allyl carbonate MAC, methyl ethyl carbonate MEC, dimethyl carbonate DMC, diethyl carbonate DEC, methyl propyl carbonate MPC or ethyl propyl carbonate EPC.

8. The electrolyte according to any one of claims 1 to 7, wherein The electrolyte includes a lithium salt, and the lithium salt includes at least one of lithium hexafluorophosphate LiPF6, lithium perchlorate LiClO4, lithium hexafluoroarsenate LiAsF6, lithium bis(trifluoromethanesulfonyl imide) or lithium trifluoromethanesulfonate.

9. A battery cell comprising the electrolyte according to any one of claims 1 to 8.

10. An electrical device comprising the battery cell according to claim 9.

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