Electrolyte, battery, and electric device

Abstract

The application provides an electrolyte, a battery and a power utilization device, the electrolyte comprising an amide fluorine-containing monomer, the amide fluorine-containing monomer comprising a compound shown in formula 1, which is beneficial to inhibit decomposition of the electrolyte at high temperature and side reactions between the electrolyte and positive and negative electrode materials, improve the stability of the interface between the positive and negative electrode sheets and the electrolyte, and further improve the high-temperature storage electrochemical performance and safety performance of the battery.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of batteries, in particular to an electrolyte, a battery, and a power consumption device. BACKGROUND

[0002] The electrolyte is an important component of a battery. Currently, the electrolyte used in batteries is generally a liquid electrolyte. When the temperature is high, the liquid electrolyte and the positive and negative electrode materials will have strong side reactions, and other reasons, causing the electrolyte to decompose, accelerating the failure of the battery cell, and leading to the deterioration of the safety performance and high-temperature storage performance of the battery. The above problems need to be solved urgently. SUMMARY

[0003] The present application provides an electrolyte, a battery, and a power consumption device, which can inhibit the decomposition of the electrolyte at high temperatures and the side reactions between the electrolyte and the positive and negative electrode materials, improve the stability of the interface between the positive and negative electrode sheets and the electrolyte, and further improve the high-temperature storage electrochemical performance and safety performance of the battery.

[0004] In a first aspect, the present application provides an electrolyte, which comprises an amide fluorine-containing monomer, and the amide fluorine-containing monomer comprises a compound shown in Formula 1:

[0005] R1-CO-NH-R2 Formula 1,

[0006] wherein at least one of R1 and R2 is selected from a fluorine-containing carbon chain with a carbon atom number greater than or equal to 5.

[0007] In a possible implementation, the carbon atom number of the fluorine-containing carbon chain is 5-10.

[0008] In a possible implementation, the fluorine-containing carbon chain comprises a perfluoroalkyl chain, and the carbon atom number of the perfluoroalkyl chain is less than or equal to the carbon atom number of the fluorine-containing carbon chain.

[0009] In a possible implementation, the ratio of the carbon atom number of the perfluoroalkyl chain to the total carbon atom number of the fluorine-containing carbon chain is 70%-100%.

[0010] In a possible implementation, the fluorine-containing carbon chain further comprises an amide group and / or an alkylene group.

[0011] In a possible implementation, R1 has a structure shown in Formula 2:

[0012] R3-L- Formula 2,

[0013] wherein R3 represents a perfluoroalkyl chain, and L represents a single bond, an amide group, or an alkylene group.

[0014] In a possible implementation, the alkylene group comprises a methylene group and / or an ethylene group.

[0015] In a possible implementation, one of R1 and R2 is selected from the fluorocarbon chain, and the other is selected from a hydrogen atom or an amide group.

[0016] In a possible implementation, the amide-based fluorine-containing monomer includes one or more of CF3CF2CF2CF2CF2CF2CF2-CO-NH2, CF3CF2CF2CF2CF2CF2CH2-CO-NH2, CF3CF2CF2CF2CF2CF2CF2CH2-CO-NH2, CF3CF2CF2CF2CF2CF2CH2CH2-CO-NH2, and CF3CF2CF2CF2CF2CF2-NH-CO-CO-NH2.

[0017] In a possible implementation, the electrolyte further includes an organic solvent, and a mass ratio of the amide-based fluorine-containing monomer to the organic solvent is 5:90-20:70.

[0018] In a possible implementation, the electrolyte has a phase transition temperature, and the electrolyte is liquid under a temperature condition less than the phase transition temperature of the electrolyte.

[0019] In a possible implementation, the phase transition temperature is 50-80℃.

[0020] In a possible implementation, the electrolyte satisfies: under the phase transition temperature, a transition time for the electrolyte to change from liquid to non-liquid is 0.5 min-5 min.

[0021] In a possible implementation, the electrolyte further includes an organic solvent.

[0022] In a possible implementation, the organic solvent includes one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, propyl propionate, ethyl propionate, and butyl propionate.

[0023] In a possible implementation, the electrolyte further includes an electrolyte salt and a film-forming additive.

[0024] In a possible implementation, the electrolyte salt comprises a lithium salt, the lithium salt comprises one or more of lithium hexafluorophosphate, lithium bisfluorosulfonylimide, lithium bis-trifluoromethanesulfonylimide; and / or, the film-forming additive comprises one or more of lithium bis(oxalato)borate, lithium tetrafluoroborate, lithium difluoro(oxalato)borate, lithium bisfluorosulfonylimide, lithium bis-trifluoromethanesulfonylimide, vinylene carbonate, fluoroethylene carbonate, vinyl ethylene carbonate, 1,3-propane sultone, polyphenylene sulfide, vinyl sulfonate, tris(trimethylsilyl)phosphate, tris(trimethylsilyl)phosphite.

[0025] In a second aspect, the present application provides a battery comprising the electrolyte described above.

[0026] In a third aspect, the present application provides a power consumption device comprising the battery described above.

[0027] The present application provides an electrolyte, a battery, and a power consumption device. The electrolyte comprises an amide fluorine-containing monomer, and the amide fluorine-containing monomer comprises a compound shown in Formula 1. The decomposition of the electrolyte at high temperatures and the side reaction between the electrolyte and the positive and negative electrode materials are inhibited, thereby improving the stability of the interface between the positive and negative electrode sheets and the electrolyte, and further improving the high-temperature storage electrochemical performance and safety performance of the battery. DETAILED DESCRIPTION

[0028] To make the objectives, technical solutions, and advantages of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0029] The present application provides an electrolyte, which comprises an amide fluorine-containing monomer, and the amide fluorine-containing monomer comprises a compound shown in Formula 1.

[0030] R1-CO-NH-R2 Formula 1,

[0031] wherein at least one of R1 and R2 is selected from a fluorine-containing carbon chain with a carbon atom number greater than or equal to 5 (hereinafter referred to as a fluorine-containing carbon chain).

[0032] According to the research of the inventor, the above-mentioned electrolyte is a phase change electrolyte, and under the above-mentioned system, the amide type fluorine-containing monomer has a long carbon chain and an amide group. During the working process of the battery, when the phase change temperature of the electrolyte is reached, the amide type fluorine-containing monomer is physically cross-linked to form a three-dimensional network structure through the hydrophobic effect of the long carbon chain and the hydrogen bond effect of the amide group, binds the solvent in the electrolyte, changes the electrolyte from a liquid to a non-liquid, reduces the contact of the solvent with the positive and negative active materials, and inhibits the side reaction and decomposition of the electrolyte. The amide type fluorine-containing monomer enhances the hydrophobicity, chemical inertness and thermal stability of the electrolyte through the fluorine atom, improves the electrochemical performance and safety performance of the battery at high temperature storage.

[0033] Specifically, the fluorine-containing carbon chain includes a fluorine-containing alkyl chain with a carbon atom number greater than or equal to 5 (hereinafter referred to as a fluorine-containing alkyl chain), and the fluorine-containing alkyl chain includes one or more fluorine-substituted methylene groups, which can be substituted with one fluorine or multiple fluorines. The fluorine-containing alkyl chain can specifically include one or more fluorine-substituted methylene groups, and can also include non-fluorine-substituted methylene groups. The number of fluorine-substituted methylene groups can be greater than the number of non-fluorine-substituted methylene groups.

[0034] The compound represented by Formula 1 can be measured by the following method: using high performance liquid chromatography-mass spectrometry (HPLC-MS) method, using high performance liquid chromatography (HPLC) to separate the compound represented by Formula 1 from other components in the electrolyte, and mass spectrometry (MS) for qualitative analysis through characteristic ions. The mass spectrum peak of the fluorine-containing monomer can reflect the isotopic distribution of fluorine element, and the structure can be confirmed by combining the fragments of amide bond; quantitative analysis is obtained by external standard method (preparation of monomer standard solution) to obtain the qualitative and quantitative results of the compound represented by Formula 1. In addition, the mass spectrum determines the molecular weight of the monomer by measuring the mass-to-charge ratio of the ion, and the molecular weight can be used to deduce the carbon chain length (i.e. the number of C atoms). The length of the fluorine-containing carbon chain and the structure of the compound represented by Formula 1 (i.e. the type of amide type fluorine-containing monomer) can be measured.

[0035] In some embodiments, the number of carbon atoms in the fluorine-containing carbon chain is 5-10, such as 5, 6, 7, 8, 9, 10. If the fluorine-containing carbon chain is too long, the molecular weight will increase, the viscosity will increase significantly, which may lead to poor solubility of the electrolyte, difficulty in dissolving enough lithium salt, or poor compatibility with other solvent components (such as carbonate), and the ionic conductivity will decrease. High viscosity hinders the migration of lithium ions, reduces the rate performance of the battery, and the number of carbon atoms in the fluorine-containing carbon chain is 5-10, which is more conducive to improving the hydrophobic effect of the amide type fluorine-containing monomer, and more conducive to the formation of a three-dimensional network structure at high temperature, which binds the organic solvent, changes the electrolyte from a liquid to a non-liquid, thereby reducing the contact of the solvent with the positive and negative active materials, inhibiting the side reaction between the electrolyte and the positive and negative materials at high temperature, and the decomposition of the electrolyte, and more conducive to improving the electrochemical performance and safety performance of the battery at high temperature storage.

[0036] In some embodiments, the fluorine-containing carbon chain includes a perfluoroalkyl chain (i.e., all hydrogen atoms in the alkyl chain are replaced by fluorine), and the number of carbon atoms in the perfluoroalkyl chain is less than or equal to the number of carbon atoms in the fluorine-containing carbon chain (i.e., the total number of carbon atoms in the fluorine-containing carbon chain). The fluorine atoms in the perfluoroalkyl chain can enhance the hydrophobicity, chemical inertness and thermal stability of the electrolyte, and can further inhibit decomposition of the electrolyte at high temperatures and side reactions between the electrolyte and the positive and negative electrode materials, thereby improving the electrochemical performance and safety performance of the battery during high-temperature storage.

[0037] In some embodiments, the ratio of the number of carbon atoms in the perfluoroalkyl chain to the total number of carbon atoms in the fluorine-containing carbon chain is 70% to 100%, such as 70%, 75%, 80%, 83%, 85%, 86%, 88%, 90%, 95%, 100%, or a range between any two of them. A high ratio of the number of carbon atoms in the perfluoroalkyl chain indicates a high proportion of fluorine atoms, which is beneficial to enhancing the hydrophobicity, chemical inertness and thermal stability of the electrolyte, and can further inhibit decomposition of the electrolyte at high temperatures and side reactions between the electrolyte and the positive and negative electrode materials, thereby improving the electrochemical performance and safety performance of the battery during high-temperature storage.

[0038] In some embodiments, the fluorine-containing carbon chain further includes an amide group, which is more conducive to the formation of a three-dimensional network structure by the amide fluorine-containing monomer at high temperatures, and binds the organic solvent, so that the electrolyte changes from a liquid to a non-liquid, thereby reducing the contact between the solvent and the positive and negative active materials, inhibiting side reactions between the electrolyte and the positive and negative electrode materials and decomposition of the electrolyte, and more conducive to improving the electrochemical performance and safety performance of the battery during high-temperature storage.

[0039] In some embodiments, the fluorine-containing carbon chain further includes an alkylene group, which can reduce the rigidity of the fluorine-containing carbon chain, break the strong hydrophobic aggregation tendency of the perfluoroalkyl chain, improve the solubility and dispersibility of the monomer in the electrolyte, and make the amide group in the monomer more accessible to the solvent molecules, promote efficient crosslinking, bind the organic solvent, so that the electrolyte changes from a liquid to a non-liquid, thereby reducing the contact between the solvent and the positive and negative active materials, inhibiting side reactions between the electrolyte and the positive and negative electrode materials and decomposition of the electrolyte, and more conducive to improving the electrochemical performance and safety performance of the battery during high-temperature storage.

[0040] Specifically, when the fluorine-containing carbon chain includes a perfluoroalkyl chain, an amide group and an alkylene group, the alkylene group can be connected between the perfluoroalkyl chain and the amide group.

[0041] In some embodiments, R1 has the structure shown in Formula 2:

[0042] R3-L- Formula 2,

[0043] wherein R3 represents a perfluoroalkyl chain, and L represents a single bond, an amide group or an alkylene group.

[0044] Specifically, when R2 is a hydrogen atom, R3 represents a perfluoroalkyl chain, and L represents a single bond, the amide type fluorine-containing monomer includes a compound represented by Formula 3:

[0045] R3-CO-NH2 Formula 3.

[0046] When R2 is a hydrogen atom, R3 represents a perfluoroalkyl chain, and L represents an alkylene group, the amide type fluorine-containing monomer includes a compound represented by Formula 4:

[0047] R3-(CH2)n-CO-NH2 Formula 4;

[0048] wherein n represents the number of alkylene groups that are not substituted by fluorine.

[0049] When R1 is an amide group, and R2 is selected from a fluorine-containing carbon chain, the amide type fluorine-containing monomer includes a compound represented by Formula 5:

[0050] R2-NH-CO-CO-NH2 Formula 5.

[0051] In some embodiments, the alkylene group includes at least one alkylene group, for example, including a methylene group and / or an ethylene group, which can further inhibit decomposition of the electrolyte at high temperatures, and side reactions between the electrolyte and the positive and negative electrode materials, improve the stability of the interface between the positive and negative electrode sheets and the electrolyte, and thus improve both the electrochemical performance and the safety performance of the battery during high-temperature storage.

[0052] In some embodiments, one of R1 and R2 is selected from a fluorine-containing carbon chain having a number of carbon atoms greater than or equal to 5, and the other is selected from a hydrogen atom or an amide group.

[0053] Specifically, one of R1 and R2 is selected from a perfluoroalkyl chain, and the other is selected from a hydrogen atom or an amide group, which is conducive to the formation of a three-dimensional network by the amide type fluorine-containing monomer when the electrolyte reaches the phase transition temperature, which is conducive to binding the organic solvent in the electrolyte, which is conducive to further inhibiting decomposition of the electrolyte at high temperatures, and side reactions between the electrolyte and the positive and negative electrode materials, improving the stability of the interface between the positive and negative electrode sheets and the electrolyte, and thus improving both the electrochemical performance and the safety performance of the battery during high-temperature storage.

[0054] In some embodiments, the amide type fluorine-containing monomer includes one or more of CF3CF2CF2CF2CF2CF2CF2-CO-NH2, CF3CF2CF2CF2CF2CF2CH2-CO-NH2, CF3CF2CF2CF2CF2CF2CF2CH2-CO-NH2, CF3CF2CF2CF2CF2CF2CH2CH2-CO-NH2, and CF3CF2CF2CF2CF2CF2-NH-CO-CO-NH2, which can further enhance the hydrophobicity, chemical inertness and thermal stability of the electrolyte, and improve the electrochemical performance and safety performance of the battery at high temperature storage.

[0055] In some embodiments, the electrolyte further includes an organic solvent, and the mass ratio of the amide type fluorine-containing monomer to the organic solvent is 5:90 to 20:70, for example, 5:90, 10:90, 10:80, 10:70, 15:85, 20:70, or a range consisting of any two of them. According to the research of the inventors, by introducing the amide type fluorine-containing monomer shown in Formula 1 into the electrolyte, the electrolyte has a phase change characteristic, and the mass ratio of the amide type fluorine-containing monomer to the organic solvent is controlled in the above range. When the temperature is higher than the phase change temperature, the organic solvent in the electrolyte is more likely to be bound by the three-dimensional network structure formed by the amide type fluorine-containing monomer, which is conducive to the change of the electrolyte from liquid to non-liquid at high temperature, reduces the contact of the organic solvent with the positive and negative active materials, and is more conducive to inhibiting the side reaction between the electrolyte and the positive and negative materials and the decomposition of the electrolyte, thereby improving the electrochemical performance and safety performance of the battery at high temperature storage. It is more conducive to the change of the electrolyte from liquid to non-liquid at high temperature, thereby reducing the contact of the organic solvent with the positive and negative active materials, inhibiting the side reaction between the electrolyte and the positive and negative materials and the decomposition of the electrolyte, and more conducive to improving the electrochemical performance and safety performance of the battery at high temperature storage.

[0056] In the embodiments of the present application, the content of the amide type fluorine-containing monomer and other components in the electrolyte can be measured by conventional methods, such as gas chromatography-mass spectrometry (or simply GC-MS) and the like.

[0057] In a specific implementation, the mass ratio of the amide fluorine-containing monomer to the organic solvent in the electrolyte can be measured by the following method: using a GC-MS method, the electrolyte sample is injected into a gas chromatograph (GC), separated into single components in the chromatographic column, and sequentially flows out according to the retention time. The outflow component enters the ion source of the mass spectrometer (MS), is ionized and fragmented into ions. The ions are separated in the mass analyzer according to m / z. The separated ions are detected by the detector to generate an electrical signal. The qualitative results identify the electrolyte components corresponding to each chromatographic peak in combination with the retention time and mass spectrum (compared with the standard library). The content (concentration or percentage) of the target component in the original electrolyte sample is calculated using the chromatographic peak area of the target component, and a standard curve established by an external standard method or an internal standard method. The content of the amide fluorine-containing monomer in the original electrolyte sample and the content of the organic solvent in the original electrolyte sample can be obtained, and the mass ratio of the amide fluorine-containing monomer to the organic solvent in the electrolyte can be further obtained.

[0058] In some embodiments, the electrolyte has a phase transition temperature, the electrolyte is a liquid at a first temperature, the first temperature is less than the phase transition temperature of the electrolyte; the electrolyte is a non-liquid at a second temperature, the second temperature is greater than or equal to the phase transition temperature of the electrolyte, at this time, the amide fluorine-containing monomers are glued to form a three-dimensional network structure, the amide group of one amide fluorine-containing monomer is connected to the alkylene group of another amide fluorine-containing monomer, and does not react with other substances in the electrolyte, and the organic solvent in the electrolyte is more conducive to being bound by the three-dimensional network structure formed by the amide fluorine-containing monomers.

[0059] Under the above system, after being warmed from the first temperature to the second temperature, the amide fluorine-containing monomers form a three-dimensional network structure through the hydrophobic effect of the long carbon chain and the hydrogen bonding effect of the amide group, bind the solvent in the electrolyte, the electrolyte changes from a liquid to a non-liquid, reduces the contact of the solvent with the positive and negative active materials, inhibits the side reactions between the electrolyte and the positive and negative materials and the decomposition of the electrolyte, and improves the electrochemical performance and safety performance of the battery during high-temperature storage. When cooled from the second temperature to the first temperature, the electrolyte changes from a non-liquid back to a liquid and functions as a liquid electrolyte. For example, after being warmed from the first temperature to the second temperature, the electrolyte changes from a liquid to a non-liquid, which can be a gel state, i.e., the electrolyte changes from a liquid to a gel state substance.

[0060] In some embodiments, the phase transition temperature is 50-80°C, for example, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, or a range consisting of any two of them, which is more conducive to improving the electrochemical performance and safety performance of the battery during high-temperature storage.

[0061] In some embodiments, the electrolyte satisfies: the transition time of the electrolyte from liquid to non-liquid at the phase transition temperature is 0.5 min to 5 min (equivalent to 30 s to 300 s), i.e., the phase transition time of the electrolyte is 0.5 min to 5 min, such as 0.5 min, 1 min, 2 min, 3 min, 4 min, 5 min, or a range consisting of any two of them, which is conducive to promoting the electrolyte to quickly change from liquid to non-liquid at the phase transition temperature, reducing the contact of the solvent with the positive and negative active materials, and more conducive to inhibiting the side reaction of the electrolyte with the positive and negative electrode materials and the decomposition of the electrolyte, and taking into account the improvement of the electrochemical performance and safety performance of the battery during high-temperature storage.

[0062] In some embodiments, the electrolyte satisfies: the transition time of the electrolyte from liquid to non-liquid at 50-80°C is 0.5 min to 5 min, such as 0.5 min, 1 min, 2 min, 3 min, 4 min, 5 min, or a range consisting of any two of them, which is conducive to promoting the electrolyte to change from liquid to non-liquid, reducing the contact of the solvent with the positive and negative active materials, and more conducive to inhibiting the side reaction of the electrolyte with the positive and negative electrode materials and the decomposition of the electrolyte, and taking into account the improvement of the electrochemical performance and safety performance of the battery during high-temperature storage. Specifically, the aforementioned temperature can be 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, or a range consisting of any two of them.

[0063] In some embodiments, the mass percentage of the organic solvent in the electrolyte is 70% to 90%, such as 70%, 75%, 80%, 85%, 90%, or a range consisting of any two of them.

[0064] In some embodiments, the organic solvent includes one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, propyl propionate, ethyl propionate, and butyl propionate.

[0065] In addition, the electrolyte can also include an electrolyte salt and a film-forming additive. According to the research of the inventor, the electrolyte salt is conducive to the transmission of active ions in the battery (such as the transmission of lithium ions in a lithium ion battery), and the film-forming additive is conducive to the formation of a protective film on the surface of the positive and negative active materials, maintaining the structural stability of the positive and negative active materials, and improving the electrochemical performance of the battery during storage and other performances.

[0066] In some embodiments, the concentration of the electrolyte salt in the electrolyte is 0.8 mol / L to 1.5 mol / L, such as 0.8 mol / L, 1 mol / L, 1.3 mol / L, 1.5 mol / L, or a range consisting of any two of them, which is conducive to promoting the migration of active ions in the battery and improving the electrochemical performance of the battery during high-temperature storage.

[0067] In some embodiments, the electrolyte salt comprises a lithium salt, and the lithium salt comprises one or more of lithium hexafluorophosphate (LiPF6), lithium bisfluorosulfonylimide (LiFSI), lithium bis-trifluoromethanesulfonylimide (LiTFSI).

[0068] In some embodiments, the concentration of the lithium salt in the electrolyte is 0.8 mol / L to 1.5 mol / L, for example 0.8 mol / L, 1 mol / L, 1.3 mol / L, 1.5 mol / L, or a range between any two of them, which is conducive to promoting the migration of lithium ions in the battery and improving the electrochemical performance of the battery at high temperature storage.

[0069] In some embodiments, the mass percentage of the film-forming additive in the electrolyte is 5% to 20%, for example 5%, 10%, 15%, 20%, or a range between any two of them.

[0070] In some embodiments, the film-forming additive comprises one or more of lithium bis(oxalato)borate (LiBOB), lithium tetrafluoroborate (LiBF4), lithium bis(oxalato)borate (LiBOB), lithium difluoro(oxalato)borate (LiODFB), lithium difluorophosphate (LiPO2F2), lithium bisfluorosulfonylimide, lithium bis-trifluoromethanesulfonylimide, vinylene carbonate (VC), fluoroethylene carbonate (FEC), vinyl ethyl carbonate (VEC), 1,3-propane sultone (PS), polyphenylene sulfide (PST), vinyl sulfonate (DTD), tris(trimethylsilyl)phosphate (TMSP), tris(trimethylsilyl)phosphite (TMSPi).

[0071] In some embodiments, the mass ratio of the film-forming additive to the organic solvent is 5:90 to 20:70, for example 5:90, 10:90, 10:80, 10:70, 15:70, 20:70, or a range between any two of them.

[0072] In the embodiments of the present application, the amide-based fluorine-containing monomer represented by Formula 1, the electrolyte salt, the film-forming additive, and the organic solvent, etc. can be mixed to form components of the electrolyte, and the electrolyte can be prepared. The electrolyte can be prepared according to the conventional preparation process of the electrolyte, and no particular limitation is made thereto.

[0073] The embodiments of the present application also provide a battery comprising the above-mentioned electrolyte or the electrolyte prepared according to the above-mentioned electrolyte preparation method, which has properties corresponding to the above-mentioned electrolyte, and no further description is made herein.

[0074] The battery of the embodiments of the present application can be a lithium ion battery.

[0075] Generally, the battery includes a cell, an electrolyte, and a shell encapsulating the cell, the electrolyte is injected into the cell in the shell, and the cell includes a positive electrode sheet, a negative electrode sheet, and a separator between the positive electrode sheet and the negative electrode sheet. The cell can be a jelly-roll type cell and / or a stacked type cell.

[0076] The battery can be prepared by a conventional method in the art. For example, the positive electrode sheet, the separator, and the negative electrode sheet can be alternately stacked to obtain a stacked type cell, or the positive electrode sheet, the separator, and the negative electrode sheet can be sequentially wound to obtain a jelly-roll type cell. Then, the cell is placed in the shell, and the battery is prepared by conventional processes such as injection (i.e., injection of the electrolyte), encapsulation, standing, formation, and capacity distribution.

[0077] Specifically, the positive electrode sheet includes a positive electrode current collector and a positive electrode coating (positive electrode active material layer) on at least one side surface of the positive electrode current collector. Specifically, the positive electrode coating can be provided on one side surface of the positive electrode current collector, or the positive electrode coating can be provided on both side surfaces of the positive electrode current collector in the thickness direction.

[0078] Specifically, the positive electrode coating can include a positive electrode active material, a positive electrode conductive agent, and a positive electrode binder. The positive electrode active material, the positive electrode conductive agent, and the positive electrode binder can be conventional materials in the art. For example, the positive electrode active material can include one or more of lithium iron phosphate, lithium cobaltate, lithium manganate, and a positive electrode ternary material. The positive electrode ternary material can include nickel-cobalt-manganese ternary material (NCM) and / or nickel-cobalt-aluminum ternary material. The positive electrode conductive agent can include one or more of conductive carbon black, carbon nanotube (CNT), acetylene black, graphene, ketjen black, and carbon fiber. The positive electrode binder can include one or more of polyvinylidene fluoride (PVDF), polyvinyl fluoride, polyethylene, polypropylene, polyvinyl alcohol, polyvinyl chloride, carboxylated polyvinyl chloride, oxirane-containing polymer, polyvinylpyrrolidone, and polyurethane.

[0079] The positive electrode current collector can be a conventional positive electrode current collector in the art. For example, the positive electrode current collector can include aluminum foil.

[0080] The positive electrode sheet can be prepared by a conventional method in the art. For example, the positive electrode active material, the positive electrode conductive agent, and the positive electrode binder can be dispersed in a positive electrode solvent such as N-methylpyrrolidone (NMP) to prepare a positive electrode slurry. Then, the positive electrode slurry is coated on the surface of the positive electrode current collector, and the positive electrode sheet is prepared by drying and rolling.

[0081] Specifically, the negative electrode sheet comprises a negative electrode current collector, and a negative electrode active material layer (negative electrode coating) located on at least one side surface of the negative electrode current collector. Specifically, the negative electrode coating can be arranged on one side surface of the negative electrode current collector, or the negative electrode coating can be arranged on both side surfaces of the negative electrode current collector in the thickness direction.

[0082] Specifically, the negative electrode coating can comprise a negative electrode active material, a negative electrode conductive agent, and a negative electrode binder, which can all be conventional materials in the art. For example, the negative electrode active material can comprise graphite, including artificial graphite; the negative electrode conductive agent can comprise one or more of conductive carbon black, carbon nanotubes (CNT), acetylene black, graphene, ketjen black, and carbon fiber; and the negative electrode binder can comprise one or more of styrene butadiene rubber (SBR), polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, an oxirane-containing polymer, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamide-imide, polyvinyl alcohol, and sodium polyacrylate.

[0083] The negative electrode current collector used in the embodiments of the present application can be conventional in the art, for example, the negative electrode current collector comprises a copper foil.

[0084] In the embodiments of the present application, the negative electrode sheet can be prepared by conventional methods in the art, for example, by a coating method. Specifically, the negative electrode active material, the negative electrode conductive agent, and the negative electrode binder, which are components used to form the negative electrode coating, can be dispersed in a negative electrode solvent, for example, water, to prepare a negative electrode slurry, which is then coated on the surface of the negative electrode current collector. After drying and rolling, the negative electrode sheet is prepared. The coating, drying, and rolling processes are conventional operations for preparing a negative electrode sheet by a coating method, and are not particularly limited.

[0085] In the embodiments of the present application, a separator is used to separate the positive electrode sheet and the negative electrode sheet to prevent short circuiting. The separator used in the embodiments of the present application can be conventional in the art, for example, the separator comprises one or more of a polypropylene film (PP film) and a polyethylene film (PE film), but is not limited thereto.

[0086] In the embodiments of the present application, a conventional casing material can be used to package the battery cell. For example, the casing comprises a soft packaging material such as an aluminum plastic film (in this case, the battery is a soft packaging battery), but is not limited thereto.

[0087] In general, the battery described above can be a single battery, or a battery form such as a battery module or a battery pack. The battery module or the battery pack comprises a plurality of single batteries, and the single batteries are connected to form the battery module or the battery pack. The single batteries can be electrically connected by conventional methods in the art, for example, in series, in parallel, or in a combination of series and parallel connections, and the present application is not particularly limited in this regard.

[0088] The embodiment of the application further provides a power consumption device comprising the battery and having properties corresponding to the battery.

[0089] The power consumption device of the embodiment of the application can be a conventional power consumption device in the art, for example, a power device (such as an electric vehicle, an electric automobile), an electronic device (such as a mobile phone, a tablet computer, a notebook computer, a digital camera, etc.), a wearable device (such as a watch, a bracelet, VR glasses, etc.), an energy storage power station, etc.

[0090] Hereinafter, the application is further described through specific embodiments.

[0091] Embodiment 1

[0092] 1. Preparation of electrolyte

[0093] CF3CF2CF2CF2CF2CF2CH2CH2-CO-NH2, ethylene carbonate, dimethyl carbonate, methyl ethyl carbonate, LiPF6, LiPO2F2, LiODFB and VC are mixed to obtain an electrolyte. The concentration of LiPF6 is 0.85 mol / L, and the mass ratio of CF3CF2CF2CF2CF2CF2CH2CH2-CO-NH2, ethylene carbonate, dimethyl carbonate, methyl ethyl carbonate, LiPO2F2, LiODFB and VC is shown in Tables 1-3.

[0094] 2. Preparation of positive electrode sheet

[0095] The positive electrode active material (ternary nickel-cobalt-manganese positive electrode active material, wherein the molar ratio of nickel (Ni), cobalt (Co) and manganese (Mn) is Ni:Co:Mn = 1:1:1), the conductive agent (carbon black) and the binder (PVDF) are mixed in a mass ratio of 96:2.5:1.5, and NMP is added, stirred uniformly, and prepared into a positive electrode slurry;

[0096] The positive electrode slurry is coated on the positive and negative surfaces of the aluminum foil, and after drying and rolling, the positive electrode coating is formed on the positive and negative surfaces of the aluminum foil to prepare the positive electrode sheet.

[0097] 3. Preparation of negative electrode sheet

[0098] The negative electrode active material (natural graphite), the conductive agent (carbon black), the binder (SBR) and the binder (CMC) are mixed in a mass ratio of 96.4:1.5:1:1.1, and deionized water is added, stirred uniformly, and prepared into a negative electrode slurry;

[0099] The negative electrode slurry is coated on the positive and negative surfaces of the copper foil, and after drying and rolling, the negative electrode coating is formed on the positive and negative surfaces of the copper foil to prepare the negative electrode sheet.

[0100] 4. Assembly of battery

[0101] The positive electrode sheet, the separator (PE film) and the negative electrode sheet are alternately stacked to form a laminated cell; the laminated cell is placed in an aluminum-plastic film packaging shell, the electrolyte in item 1 is injected, and after standing, hot and cold pressing, formation, and capacity distribution, a battery is obtained.

[0102] Example 2

[0103] The difference from Example 1 is that CF3CF2CF2CF2CF2CF2CH2CH2-CO-NH2, vinyl carbonate, dimethyl carbonate, ethyl methyl carbonate, LiPF6, LiPO2F2, LiFSI, VC, and DTD are mixed to obtain an electrolyte. The mass ratio of CF3CF2CF2CF2CF2CF2CH2CH2-CO-NH2, vinyl carbonate, dimethyl carbonate, ethyl methyl carbonate, LiPO2F2, LiFSI, VC, and DTD is shown in Tables 1-3.

[0104] The remaining steps and conditions are consistent with Example 1.

[0105] Example 3

[0106] The difference from Example 1 is that CF3CF2CF2CF2CF2CF2-NH-CO-CO-NH2, vinyl carbonate, dimethyl carbonate, ethyl methyl carbonate, LiPF6, LiPO2F2, LiODFB, and DTD are mixed to obtain an electrolyte. The mass ratio of CF3CF2CF2CF2CF2CF2-NH-CO-CO-NH2, vinyl carbonate, dimethyl carbonate, ethyl methyl carbonate, LiPO2F2, LiODFB, and DTD is shown in Tables 1-3.

[0107] The remaining steps and conditions are consistent with Example 1.

[0108] Examples 4-14

[0109] The difference from Example 1 is that the type of amide-based fluorine-containing monomer, the mass ratio of amide-based fluorine-containing monomer to organic solvent, the type of organic solvent, the ratio of each organic solvent to the total mass of organic solvent, the type of film-forming additive, the ratio of each film-forming additive to the total mass of film-forming additive, and the lithium salt concentration are different, as shown in Tables 1-4.

[0110] The remaining steps and conditions are consistent with Example 1.

[0111] Comparative Example 1

[0112] The difference from Example 1 is that the electrolyte does not contain CF3CF2CF2CF2CF2CF2CH2CH2-CO-NH2, and the remaining steps and conditions remain the same as Example 1.

[0113] Comparative Example 2

[0114] The difference from Example 1 is that the number of carbon atoms in the fluorocarbon chain in the amide-containing fluorine-containing monomer in the electrolyte is less than 5, and the remaining steps and conditions remain the same as Example 1.

[0115] Comparative Example 3

[0116] The difference from Example 1 is that the amide-containing fluorine-containing monomer in the electrolyte is replaced by an amide monomer, and the remaining steps and conditions remain the same as Example 1.

[0117] The batteries in the examples and comparative examples were tested by the following processes, and the test results are shown in Table 4:

[0118] (1) High temperature storage performance test

[0119] Capacity test: The battery was placed at 25°C for 4h, then discharged at a current density of 1C to 2.8V, then placed for 15min, then cycled three times, and the steps of the cycle charging and discharging were as follows: charged at 1C to 4.2V, the cutoff current was 0.05C, then placed for 15min, discharged at 1C to 2.8V, and placed for 15min. The discharge capacity during the third cycle charging and discharging process was recorded as the initial capacity Q0.

[0120] Storage performance test: After the cycle charging and discharging was completed, the battery state of charge (SOC) was adjusted to 60%: charged at 1C=Q0 to 3.7V, the cutoff current was 0.05C, then placed for 0.5h, recorded the end voltage E1, discharged at 8C for 10s, recorded the end voltage E2, the data recording interval was 100ms, and placed for 5min. Then the battery was adjusted to the target 100% SOC (charged at 1C=Q0 to 4.2V, the cutoff current was 0.05C, and placed for 30min), then placed at 60°C for 4h, and stored at 60°C for 720h (60 days), placed at 25°C for 4h, and the battery capacity Q1 was tested according to the above capacity test method, then the battery state of charge (SOC) was adjusted to 60% (charged at 1C=Q1 to 3.7V, the cutoff current was 0.05C), then placed for 0.5h, recorded the end voltage E3, discharged for 10s, recorded the end voltage E4, the data recording interval was 100ms, and placed for 5min.

[0121] Capacity retention rate = Q1 / Q0 x 100%;

[0122] Battery impedance before high-temperature storage = E2 - E1 / current;

[0123] Battery impedance after high-temperature storage = E4 - E3 / current;

[0124] Impedance growth rate = battery impedance after high-temperature storage / battery impedance before high-temperature storage × 100%, the capacity retention rate and impedance growth rate of the batteries of each example and comparative example are shown in Table 4.

[0125] (2) Safety performance test

[0126] According to GB38031-2020 8.1.5, the battery was subjected to a heating experiment, and the safety of the battery was tested. The safety performance test results of the batteries of each example and comparative example are shown in Table 4.

[0127] (3) Phase transition temperature test of electrolyte

[0128] Equipment: rotary rheometer;

[0129] Test mode: temperature scanning;

[0130] Heating rate: 1°C / min; after increasing by 2°C, the temperature was kept at this temperature for 10 min;

[0131] Phase transition temperature: when G'(storage modulus) > G"(loss modulus), the corresponding temperature (the intersection point of G'(storage modulus) > G"(loss modulus)) is the phase transition temperature. The phase transition temperature of the electrolyte of each example and comparative example is shown in Table 4.

[0132] (4) Phase transition time test of electrolyte

[0133] Phase transition time: at the phase transition temperature, dynamic rheological test was used, and the calculation formula of the total phase transition time (Δt) was: Δt = tend - tstart, wherein Δt represents the complete duration from the start of phase transition to the stable state of the system;

[0134] tstart: phase transition start time, indicating that the system starts to deviate from the initial state (5% deviation is considered as the phase transition starting point), enters the transition process, and G'(strat) corresponds to the time tstart. G'(start) = G'0 × 1.05, G'0 is the first storage modulus value at the start of the test, i.e. the storage modulus value when the system deviates from the initial state by 5%;

[0135] tend: phase transition termination time, indicating that the system completes the transition and reaches a new stable state, the judgment condition is that G' and G" enter the platform period, and G'(end) corresponds to the time tend. G'(end) = G' 结束 × 1.05, G' 结束The last storage modulus value at the end of the test, i.e. the storage modulus value tested when the system reaches a new stable state. The phase inversion time results of the electrolyte of each example and comparative example are shown in Table 4.

[0136] Table 1: Types of amide-containing fluoromonomer and mass ratio of amide-containing fluoromonomer to organic solvent in electrolyte

[0137]

[0138] Table 2: Types and contents of organic solvent and film-forming additive in electrolyte of Examples 1-8

[0139]

[0140] Table 3: Types and contents of organic solvent and film-forming additive in electrolyte of Examples 9-14 and Comparative Examples 1-3

[0141]

[0142] Table 4: Lithium salt concentration, phase inversion temperature and phase inversion time of electrolyte and performance test of battery

[0143]

[0144] As can be seen from Table 4, compared with Comparative Examples 1-3, the electrolyte in Examples 1-14 introduces amide-containing fluoromonomer, and the amide-containing fluoromonomer includes the compound shown in Formula 1, which is beneficial to inhibit the decomposition of the electrolyte at high temperature and the side reaction between the electrolyte and the positive and negative electrode materials, improve the stability of the interface between the positive and negative electrode sheets and the electrolyte, and further improve the electrochemical performance and safety performance of the battery during high-temperature storage.

[0145] In addition, as can be seen from Table 4, when the mass ratio of amide-containing fluoromonomer to organic solvent in the electrolyte is in the range of 5:90-20:70, the decomposition of the electrolyte at high temperature and the side reaction between the electrolyte and the positive and negative electrode materials can be further inhibited, the stability of the interface between the positive and negative electrode sheets and the electrolyte can be improved, and the electrochemical performance and safety performance of the battery during high-temperature storage can be further improved. For example, compared with Examples 13 and 14, the mass ratio of amide-containing fluoromonomer to organic solvent in the electrolyte of Examples 1-12 is in the range of 5:90-20:70, which can further improve the capacity retention rate of the battery and reduce the impedance growth rate of the battery, while further improving the safety performance of the battery.

[0146] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit the present application; although the present application has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions recorded in the above embodiments can be modified, or some or all of the technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. An electrolyte, characterized by, The electrolyte comprises an amide fluorine-containing monomer, the amide fluorine-containing monomer comprises a compound shown in Formula 1: R1-CO-NH-R2 Formula 1, wherein at least one of R1 and R2 is selected from a fluorocarbon chain with a carbon atom number greater than or equal to 5; the fluorocarbon chain comprises a perfluoroalkyl chain, and a ratio of a carbon atom number of the perfluoroalkyl chain to a total carbon atom number of the fluorocarbon chain is 70% to 95%.

2. The electrolyte according to claim 1, characterized in that, The fluorocarbon chain has a carbon atom number of 5 to 10.

3. The electrolyte according to claim 1 or 2, characterized in that, The fluorocarbon chain further comprises an amide group and / or an alkylene group.

4. The electrolyte according to claim 1 or 2, characterized in that, The R1 has a structure shown in Formula 2: R3-L- Formula 2, wherein R3 represents a perfluoroalkyl chain, and L represents a single bond, an amide group, or an alkylene group.

5. The electrolyte of claim 3, wherein The alkylene group comprises a methylene group and / or an ethylene group.

6. The electrolyte according to claim 1 or 2, characterized in that, One of R1 and R2 is selected from the fluorocarbon chain, and the other is selected from a hydrogen atom or an amide group.

7. The electrolyte according to claim 1 or 2, characterized in that, The amide fluorine-containing monomer comprises one or more of CF3CF2CF2CF2CF2CF2CF2-CO-NH2, CF3CF2CF2CF2CF2CF2CF2CH2-CO-NH2, CF3CF2CF2CF2CF2CF2CH2-CO-NH2, CF3CF2CF2CF2CF2CF2CH2CH2-CO-NH2, and CF3CF2CF2CF2CF2CF2-NH-CO-CO-NH2.

8. The electrolyte according to claim 1 or 2, characterized in that, The electrolyte further comprises an organic solvent, and a mass ratio of the amide fluorine-containing monomer to the organic solvent is 5:90 to 20:

70.

9. The electrolyte according to claim 1 or 2, characterized in that, The electrolyte has a phase transition temperature, and the electrolyte is a liquid under a temperature condition less than the phase transition temperature of the electrolyte.

10. The electrolyte of claim 9, wherein, The phase transition temperature is 50 to 80℃.

11. The electrolyte according to claim 10, characterized in that The electrolyte satisfies: under the phase transition temperature, a transition time for the electrolyte to change from a liquid to a non-liquid is 0.5 min to 5 min.

12. The electrolyte of claim 8, wherein, The organic solvent comprises one or more of vinyl carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, propyl propionate, ethyl propionate, and butyl propionate.

13. The electrolyte according to claim 1 or 2, characterized in that, The electrolyte further comprises an electrolyte salt and a film-forming additive.

14. The electrolyte of claim 13, wherein, The electrolyte salt comprises a lithium salt, and the lithium salt comprises one or more of lithium hexafluorophosphate, lithium bisfluorosulfonylimide, and lithium bis-trifluoromethanesulfonylimide; and / or, the film-forming additive comprises one or more of lithium bis(oxalato)borate, lithium tetrafluoroborate, lithium difluoro(oxalato)borate, lithium bisfluorosulfonylimide, lithium bis-trifluoromethanesulfonylimide, vinylene carbonate, fluoroethylene carbonate, vinyl ethylene carbonate, 1,3-propane sultone, polyphenylene sulfide, vinyl sulfonate, tris(trimethylsilyl)phosphate, and tris(trimethylsilyl)phosphite.

15. A battery, characterized by The electrolyte comprises the electrolyte of any one of claims 1 to 14.

16. An electrical device, characterized by The battery comprises the battery of claim 15.

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