Battery cell and manufacturing method therefor, negative electrode sheet, battery device, and electric device

Abstract

The present application discloses a battery cell and a manufacturing method therefor, a negative electrode sheet, a battery device, and an electric device. The battery cell comprises an electrode sheet and an electrolyte. The electrode sheet comprises a current collector and a film layer provided on at least one surface of the current collector; the film layer comprises an active material and an additive provided on at least part of the surface of the active material; a main chain of the additive comprises one or more of a triazine ring group, an ether bond, and a carbamate group; a terminal group of the additive comprises a silanol group; and a pendant group of the additive comprises one or more of a silanol group, a triazine ring group, an ether bond, and a carbamate group. The embodiments of the present application can improve the wettability of the battery cell, thereby improving the cycle life and storage life of the battery cell.

Description

Battery cells and their preparation methods, negative electrode sheets, battery devices and electrical devices Technical Field

[0001] This application relates to battery cells, and more particularly to a battery cell and its preparation method, negative electrode sheet, battery device, and power consumption device. Background Technology

[0002] Because battery cells can convert chemical energy into electrical energy, they have become one of the important energy sources for human production and life, and are therefore widely used in many fields such as power tools, electric vehicles, and electronic devices to provide them with power.

[0003] With the widespread application of battery cells in various fields, the requirements for their performance are becoming increasingly stringent, among which the wettability of battery cells has become a key focus. Therefore, how to improve the wettability of battery cells is one of the urgent technical problems to be solved. Summary of the Invention

[0004] This application provides a battery cell and its preparation method, a negative electrode sheet, a battery device, and an electrical device, which can improve the wettability of the battery cell, thereby improving the cycle life and storage life of the battery cell.

[0005] In a first aspect, embodiments of this application provide a battery cell including a negative electrode sheet, the negative electrode sheet including a negative current collector and a film layer disposed on at least one surface of the negative current collector, the film layer including an additive, the main chain of the additive including one or more of triazine ring groups, ether bonds and urethane groups, the end group of the additive including silanol groups, and the side groups of the additive including one or more of silanol groups, triazine ring groups, ether bonds, alkyl groups, alkoxy groups and urethane groups.

[0006] The side groups of the additives in this application include silanol, triazine ring group, ether bond, alkyl, alkoxy, and carbamate groups. The silanol, triazine ring group, ether bond, alkyl, alkoxy, or carbamate group can be substituted or unsubstituted groups. The substituted groups can be one or more of the following: silanol, triazine ring group, ether bond, alkyl, alkoxy, and carbamate groups.

[0007] In this application embodiment, a long-chain polymer structure can be formed by repeating the main chain groups, for example, when the main chain groups are ether bonds and urethane groups. In this case, the end groups of the additive include silanol groups. Silanol groups can enhance the hydrophilicity of the additive, allowing it to be better dispersed in the slurry. This, in turn, allows the additive to better coat the surface of the active particles, thereby improving the ion transport performance in the active material and increasing charge transport efficiency. Simultaneously, the film formed by the additive coating the surface of the active particles can absorb the stress generated by the volume expansion of the active particles, thereby reducing the volume change of the active particles during charging and discharging, thus improving the energy density, charging speed, and cycle stability of the battery cell.

[0008] In this application embodiment, a polymer cross-linked network structure can be formed by repeating the main chain groups, for example, when the main chain groups are triazine ring groups. Compared with long-chain polymer structures and polymer network structures, polymer cross-linked network structures have more hydrophilic group grafting sites and the ability to absorb stress, thereby further improving the wettability of the electrode, reducing electrode defects, thereby reducing electrode impedance, and reducing the volume change of active particles during charging and discharging, thereby improving the energy density, charging speed and cycle stability of the battery cell.

[0009] In the above case, when the side group of the additive contains a triazine ring group, it can increase the grafting sites of the branch chain, thereby giving the additive a polymer network structure, which can improve the wettability of the electrode, reduce the defects of the electrode, and thus reduce the impedance of the electrode, thereby improving the cycle life and storage life of the battery cell; and when the side group of the additive also contains silanol groups, it can further improve the hydrophilicity of the additive.

[0010] In some embodiments, the additive includes one or more of the first additive shown in formula (1) and the second additive shown in formula (2):

[0011] Among them, R 1-1 -R 1-4 Independently includes any one of C1-C4 alkyl groups, C1-C4 alkoxy groups, and groups shown in formula (1-1); R 2-9 -R 2-11 Including C1-C8 alkyl groups; R 2-1 -R 2-8 R 2-12 -R 2-14 Independently includes any one of C1-C4 alkyl, C1-C4 alkoxy, group shown in formula (1-1), group shown in formula (2-1), group shown in formula (2-2), and group shown in formula (2-3); R1 and R2 independently include polyurethane group and / or polyether group; n1 and n2 independently include 10 to 10000;

[0012] Among them, R 1-5 -R 1-8 R 2-15 -R 2-22 R 2-26 -R 2-28 R 2-29 -R 2-36 R 2-40 -R 2-42 R 3-1 R 3-2 R 3-6 -R 3-10 and R 3-12 -R 3-16 Independently includes any one of C1-C4 alkyl groups, C1-C4 alkoxy groups, and silanol-containing groups; R 2-23 -R 2-25 R 2-37 -R 2-39 R3-R6, R 3-3 and R 3-11 Independently includes C1-C8 alkyl groups; R1 1 R2 1 R2 2 It independently includes polyurethane groups and / or polyether groups; n3-n6 are independently 10 to 10000, n1 is greater than n3, and n2 is greater than any one of n3 to n6.

[0013] When one or more of the first additive shown in formula (1) and the second additive shown in formula (2) are applied to a battery cell, the polymer network structure containing silicon-oxygen bonds in the first additive shown in formula (1) and the second additive shown in formula (2) can absorb and retain more electrolyte, thereby improving the wettability of the electrode, reducing electrode defects, and thus reducing electrode impedance, thereby improving the cycle life and storage life of the battery cell. The second additive shown in formula (2) contains a triazine ring structure, which can provide more crosslinking sites, thus giving the second additive a polymer crosslinking network structure, thereby improving the wettability of the second additive. In addition, the polymer network structure with silicon-oxygen bonds can enhance the hydrophilicity of the first and second additives, allowing them to be better dispersed in the slurry. This, in turn, allows the first and second additives to better coat the surface of the active particles, thereby improving the ion transport performance in the active material and increasing charge transport efficiency. At the same time, the film layer formed by the first and second additives coating the surface of the active particles can also absorb the stress generated by the volume expansion of the active particles, thereby reducing the volume change of the active particles during charging and discharging, thus improving the energy density, charging speed, and cycle stability of the battery cell.

[0014] The additives in the embodiments of this application can be the first additive shown in formula (1), the second additive shown in formula (2), or a mixture of the first additive shown in formula (1) and the second additive shown in formula (2).

[0015] In some embodiments, R1, R2, R1 1 R2 1 R2 2 Independently includes any one of the groups shown in formula (3-1), formula (3-2), formula (3-3), formula (3-4), formula (3-5), and formula (3-6);

[0016] R7, R 19 R 20 and R 25 Independently selected from any one of hydrogen atoms and C1-C4 alkyl groups; R 10 and R 11 Alkyl groups independently selected from C1-C4; R8, R9, R 17 R 18 R 21 R 22 R 23 and R 24 Independently selected from or lacking C1-C6 alkylene groups; R 12 and R 16 Independently selected from any one of the following: an alkylene divalent group substituted with an aliphatic compound having at least three carbon atoms, an alkylene divalent group substituted with an aliphatic compound having one carbon atom, and an alkylene divalent group substituted with an aromatic compound; or, R 12 and R 16 Independently missing; R 14 Selected from any one of C1-C6 alkylene groups and phenyl groups substituted with at least two methyl or ethyl groups; R 13 and R 15 Independently selected from C2-C200 divalent hydrocarbon groups or omitted; Ar is aryl, n7-n 14 And m independently ranges from 10 to 10000.

[0017] In some embodiments, the swelling rate of the additive is 70% to 500%.

[0018] Optionally, the swelling rate of the additive is 100% to 400%.

[0019] In some embodiments, the membrane layer includes a negative electrode active material, and the mass ratio of the additive to the negative electrode active material is (0.05% to 5.00%): 1.

[0020] Optionally, the mass ratio of the additive to the negative electrode active material is (0.2% to 2.00%): 1.

[0021] The embodiments of this application have an appropriate ratio of additives and negative electrode active materials, which can make the additives form a liquid-absorbing film layer more uniformly between the negative electrode active materials, and can also make the thickness of the liquid-absorbing film layer coated on the surface of the negative electrode active particles more uniform, thereby better improving the cycle life, storage life and cycle stability of the battery cell.

[0022] In some embodiments, the additives account for 0.05% to 4.65% of the mass based on the film layer.

[0023] Optionally, based on the membrane layer, the mass percentage of the additive is 0.20% to 2.00%.

[0024] The additives in this application embodiment with an appropriate mass ratio can improve the wettability of the active material while increasing the mass ratio of the active material, so as to balance the stability and energy density of the battery cell.

[0025] In some embodiments, the battery cell further includes a positive electrode sheet, which includes a positive electrode active material, and the positive electrode active material includes one or more of lithium transition metal oxides and lithium phosphates.

[0026] Optionally, lithium transition metal oxides include those having the general formula Li a Ni b Co c M d O e D f One or more of lithium transition metal oxides and their modified compounds, 0.8≤a≤1.2, 0.5≤b<1, 0<c<1, 0<d<1, 1≤e≤2, 0≤f≤1, M includes one or more of Ge, Mo, Sn, Mn, Al, Zr, Zn, Cu, Cr, Mg, Fe, V, Ti and B, and D includes one or more of N, F, S and Cl.

[0027] Optionally, the lithium-containing phosphate includes one or more of lithium iron phosphate and lithium manganese iron phosphate.

[0028] In some embodiments, the negative electrode active material includes one or more of carbon-based materials and silicon-based materials;

[0029] Alternatively, the carbon-based material includes one or more of natural graphite, artificial graphite, soft carbon, and hard carbon.

[0030] Optionally, the silicon-based material includes one or more of elemental silicon, silicon oxide, silicon-carbon composite, silicon-nitrogen composite, and silicon alloy materials.

[0031] In some embodiments, the negative electrode active material satisfies at least one of the following conditions:

[0032] (1) The specific surface area of ​​the negative electrode active material is 0.5–2.6 m². 2 / g;

[0033] (2) The Dv50 of the negative electrode active material is 8-25 μm.

[0034] Secondly, embodiments of this application provide a method for preparing a battery cell, comprising: providing a positive electrode, a negative electrode, a separator, and an electrolyte; providing a slurry comprising an additive precursor liquid, a negative electrode active material, and a solvent, wherein the additive precursor liquid comprises a first raw material having the structure shown in formula (4); coating the slurry onto the surface of the negative electrode, and drying it to form a negative electrode with an additive film layer, wherein the main chain of the additive comprises one or more of triazine ring groups, ether bonds, and urethane groups, the end group of the additive comprises silanol groups, and the side groups of the additive comprise one or more of silanol groups, triazine ring groups, ether bonds, alkyl groups, alkoxy groups, and urethane groups; assembling the positive electrode, the negative electrode, the separator, and the electrolyte to obtain a battery cell, wherein the separator is located between the positive electrode and the negative electrode;

[0035] Among them, R 20 Including polyurethane groups and / or polyether groups, R 20-1 -R 20-6 Independently includes any one of C1-C4 alkyl and C1-C4 alkoxy groups, and R 20-1 -R 20-6 At least one of them includes a C1-C4 alkoxy group.

[0036] In this embodiment, a first raw material containing alkoxy groups is added during the preparation of the negative electrode slurry, which allows the first raw material to undergo a hydrolysis reaction with water to hydrolyze the alkoxy groups connected to the silicon group into silanol groups, thereby obtaining a first precursor containing silanol groups. During the drying process of the slurry, the first precursor undergoes a dehydration condensation reaction, which causes the silanol groups between multiple first precursors to dehydrate and condense to form silicon-oxygen-silicon bonds, thereby forming a first additive with a network structure as shown in formula (1), thereby making the first additive uniformly dispersed on the surface of the active material.

[0037] In some embodiments, in order to make the first raw material more fully hydrolyzed, the first raw material can be hydrolyzed in advance. The additive precursor liquid includes: mixing the first raw material having the structure shown in formula (4) with water and carrying out a hydrolysis reaction under certain conditions to obtain the additive precursor liquid.

[0038] In some embodiments, the additive precursor fluid further includes a second raw material having the structure shown in formula (5);

[0039] Among them, R 21-1 -R 21-9 Independently includes any one of C1-C4 alkyl and C1-C4 alkoxy groups, and R 21- 1-R 21-9 At least one of them includes a C1-C4 alkoxy group, R 21 -R 23 Independently includes C1-C4 alkyl groups.

[0040] In this embodiment, a first raw material containing alkoxy groups and a second raw material containing alkoxy groups and crosslinking sites can be added together when preparing the negative electrode slurry. The first and second raw materials will undergo hydrolysis reactions with water to hydrolyze the alkoxy groups connected to the silicon group into silanol groups, thereby obtaining a first precursor containing silanol groups and a second precursor containing silanol groups and crosslinking sites. During the drying process of the slurry, the first and second precursors will undergo dehydration condensation reactions to dehydrate and condense the silanol groups of the first and second precursors to form silicon-oxygen-silicon bonds. At this time, the second raw material can act as a crosslinking agent, thereby forming a second additive with a crosslinking network structure as shown in formula (2), thereby making the second additive uniformly dispersed on the surface of the active material.

[0041] In some embodiments, in order to make the first raw material and the second raw material more fully hydrolyzed, the first raw material and the second raw material can be hydrolyzed in advance. The additive precursor liquid includes: mixing the first raw material having the structure shown in formula (4), the second raw material having the structure shown in formula (5) and water, and carrying out a hydrolysis reaction under certain conditions to obtain the additive precursor liquid.

[0042] In some embodiments, the number average molecular weight of the first raw material is 2000-10000 Da, and the number average molecular weight of the second raw material is 500-700 Da.

[0043] In some embodiments, the first raw material includes one or more of silane-terminated polyurethane and silane-terminated polyether.

[0044] In some embodiments, the second raw material includes one or more of 1,3,5-tris(trimethoxysilylpropyl)isocyanurate, 1,3-di(trimethoxysilylpropyl)-5-dimethoxysilylpropyl isocyanurate and 1,3-di(trimethoxysilylpropyl)-5-methoxysilylpropyl isocyanurate.

[0045] In some embodiments, the hydrolysis reaction takes 8 to 15 minutes and the hydrolysis reaction temperature is 90 to 110°C.

[0046] In some embodiments, the temperature for drying the slurry coated on the surface of the negative electrode sheet is 60–120°C, and the time is 5–360 min.

[0047] Thirdly, embodiments of this application provide a negative electrode sheet, which includes a negative current collector and a negative electrode film layer disposed on at least one surface of the negative current collector. The negative electrode film layer includes an additive; the main chain of the additive includes one or more of triazine ring groups, ether bonds, and carbamate groups; the end group of the additive includes silanol groups; and the side groups of the additive include one or more of silanol groups, triazine ring groups, ether bonds, alkyl groups, alkoxy groups, and carbamate groups.

[0048] In some embodiments, the contact angle θ of the negative electrode at 25°C satisfies 0°≤θ≤30°.

[0049] Optionally, the contact angle θ of the negative electrode at 25°C satisfies 0°≤θ≤20°.

[0050] The electrode with a suitable contact angle θ in the embodiments of this application can make the negative electrode better wettable, so that the electrolyte can better wet the negative electrode, thereby enabling the negative electrode to absorb and store more electrolyte, and thus improve the cycle life and storage life of the battery cell.

[0051] In some embodiments, the liquid absorption rate of the negative electrode is 15.00% to 40.00%.

[0052] Optionally, the liquid absorption rate of the negative electrode sheet is 28.00% to 40.00%.

[0053] Fourthly, embodiments of this application provide a battery device including a plurality of battery cells as described in the first aspect.

[0054] Fifthly, embodiments of this application provide an electrical device, including a battery cell as described in the first aspect or a battery device as described in the fourth aspect. Attached Figure Description

[0055] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments of this application will be briefly introduced below. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0056] Figure 1 shows a schematic diagram of a battery cell provided in some embodiments of this application.

[0057] Figure 2 shows a schematic diagram of an electrical device provided in some embodiments of this application.

[0058] The accompanying drawings are not necessarily drawn to scale. Detailed Implementation

[0059] To better understand the above-mentioned objectives, features, and advantages of this application, the solution of this application will be further described below. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0060] Many specific details are set forth in the following description in order to provide a full understanding of this application, but this application may also be implemented in other ways different from those described herein; obviously, the embodiments in the specification are only some embodiments of this application, and not all embodiments.

[0061] The following detailed description, with appropriate reference to the accompanying drawings, discloses embodiments of the battery cell and its preparation method, negative electrode sheet, battery device, and power-consuming device of this application. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided for the purpose of enabling those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0062] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60–120 and 80–110 are listed for a specific parameter, it is understood that ranges of 60–110 and 80–120 are also expected. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1–3, 1–4, 1–5, 2–3, 2–4, and 2–5. In this application, unless otherwise stated, the numerical range "a–b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0~5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0063] Unless otherwise specified, all embodiments and optional embodiments of this application may be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the disclosure of this application.

[0064] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions, and such technical solutions shall be deemed to be included in the disclosure of this application.

[0065] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0066] Unless otherwise specified, in this application, the terms "first," "second," etc., are used to distinguish different objects, rather than to describe a specific order or primary / secondary relationship.

[0067] In this application, the terms "multiple" or "various" refer to two or more kinds.

[0068] In the description of the embodiments of this application, unless otherwise specified, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0069] Unless otherwise stated, the test temperature for all parameters mentioned in this application is 25°C.

[0070] The battery cells mentioned in the embodiments of this application are capable of charging and discharging independently. The battery cells may be cylindrical, cuboid, or other shapes, and the embodiments of this application are not limited in this respect. Figure 1 shows an example of a cuboid battery cell.

[0071] In this embodiment of the application, the battery cell can be a secondary battery, which refers to a battery cell that can be recharged to activate the active materials and continue to be used after the battery cell has been discharged.

[0072] The battery cell provided in the embodiments of this application includes an electrode assembly and an electrolyte. The electrode assembly includes a positive electrode, a negative electrode, and a separator, with the separator disposed between the negative electrode and the positive electrode. During the charging and discharging process of the battery cell, active ions (e.g., lithium ions) repeatedly insert and extract between the positive and negative electrodes. The separator, disposed between the positive and negative electrodes, serves to prevent short circuits between the positive and negative electrodes while allowing active ions to pass through. The electrode assembly can be a wound structure or a stacked structure; the embodiments of this application are not limited in this regard.

[0073] The battery cell also includes an outer packaging, which encapsulates the electrode components and electrolyte. The outer packaging can be a rigid shell, such as a hard plastic shell, aluminum shell, or steel shell. It can also be a flexible package, such as a pouch. The material of the flexible package can be plastic, such as one or more of aluminum-plastic film, polypropylene, polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0074] The battery cells provided in the embodiments of this application can be lithium-ion battery cells, sodium-ion battery cells, sodium-lithium-ion battery cells, magnesium-ion battery cells, etc., and the embodiments of this application are not limited to this.

[0075] The method for preparing the battery cell of this application is well known. In some embodiments, a positive electrode, a separator, a negative electrode, and an electrolyte can be assembled to form a battery cell. As an example, the positive electrode, separator, and negative electrode can be formed into an electrode assembly through a winding process or a stacking process. The electrode assembly is placed in an outer packaging, dried, and then injected with electrolyte. After vacuum sealing, settling, formation, and shaping processes, a battery cell is obtained.

[0076] The battery apparatus mentioned in the embodiments of this application may include one or more battery cell assemblies for providing voltage and capacity. A battery cell assembly may include multiple battery cells, which are connected in series, parallel, or mixed connections via a busbar.

[0077] In some embodiments, a battery cell assembly is typically formed by arranging multiple battery cells.

[0078] As an example, a battery cell assembly can be a battery module, which is formed by arranging and fixing multiple battery cells together to form an independent module. As another example, a battery module can be formed by bundling multiple battery cells together with cable ties.

[0079] In some embodiments, the battery device may be a battery pack, which includes a housing and one or more individual battery cells housed within the housing.

[0080] As an example, the battery cell assembly can be a battery module, which can be housed in a housing by fixing the battery module in the housing.

[0081] As an example, battery cell assemblies can also be housed in a housing by directly fixing multiple battery cells to the housing.

[0082] As an example, the enclosure may include a first enclosure and a second enclosure. The first enclosure and the second enclosure are fastened together to form a closed space inside the enclosure to house the individual battery cells. Here, "closed" refers to covering or closing, and can be either sealed or unsealed. The first enclosure may be a top cover or a bottom plate.

[0083] As an example, the enclosure may include a top cover, a frame, and a bottom plate. The top cover and bottom plate are connected to the frame, creating an enclosed space inside the enclosure to house the individual battery cells.

[0084] In some embodiments, the housing may be part of the vehicle's chassis structure. For example, a portion of the housing may be at least a part of the vehicle's floor, or a portion of the housing may be at least a part of the vehicle's crossbeams and longitudinal beams.

[0085] The technical solutions described in the embodiments of this application are applicable to various electrical devices that use battery cells or battery devices, such as, but not limited to, mobile devices (e.g., mobile phones, tablets, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc. Battery cells and battery devices are used to store or provide electrical energy.

[0086] Figure 2 is a schematic diagram of an example electrical device. This electrical device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc.

[0087] Throughout this specification, substituents of the polymers / compounds are disclosed by groups or ranges. It is expressly intended that this description include every individual subcombination of members of these groups and ranges. For example, the term "C1-C8 alkyl" is explicitly intended to individually disclose C1, C2, C3, C4, C5, C6, C7, C8, C1-C8, C1-C7, C1-C6, C1-C5, C1-C4, C1-C3, C1-C2, C2-C8, C2-C7, C2-C6, C2-C5, C2-C4, C2-C3, C3-C8, C3-C7, C3-C6, C3-C5, C3-C4, C4-C8, C4-C7, C4-C6, C4-C5, C5-C8, C5-C7, C5-C6, C6-C8, C6-C7, and C7-C8 alkyl.

[0088] The term "alkoxy" encompasses both straight-chain and branched alkoxy groups. In some embodiments, alkoxy groups include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, cyclobutyl, pentyl, isopentyl, neopentyl, tert-pentyl, cyclopentyl, hexyl, cyclohexyl, heptyl, cycloheptyl, octyl, cyclooctyl, nonyl, and decyl, etc. Additionally, alkoxy groups may optionally be substituted.

[0089] The term "alkyl" refers to a group formed by the loss of any one hydrogen atom from an alkane molecule.

[0090] The term "aryl" refers to a closed aromatic ring or ring system. For example, aryl groups can be C6-C50, C6-C40, C6-C30, C6-C20, or C6-C10, where C6-C30 aryl refers to a group containing 6-30 carbon atoms for ring formation. In some embodiments, aryl groups include phenyl, naphthyl, phenanthryl, anthracene, biphenyl, triphenylene, pyrene, spirobisfluorene, perylene, indene, and azulene, etc. Furthermore, aryl groups can be optionally substituted, with carbon atoms in the aryl ring being replaced by heteroatoms, which can include nitrogen, oxygen, sulfur, etc.

[0091] The term "alkynyl group" refers to a group formed by the loss of any one hydrogen atom from an alkyne molecule.

[0092] The term "hydrogen" refers to 1H (protium, H), 2H (deuterium, D), or 3H (tritium, T). In various embodiments, "hydrogen" may be 1H (protium, H).

[0093] The term "polyurethane group" refers to a polymer chain segment consisting of repeating units linked by multiple substituted or unsubstituted urethane groups.

[0094] The term "polyether group" refers to a polymer chain segment consisting of multiple repeating units linked by substituted or unsubstituted ether bonds (COC).

[0095] The term "alkylene" refers to a group formed by losing any one hydrogen atom from an alkyl group.

[0096] The term "aliphatic compounds," also known as open-chain compounds, refers to compounds in which carbon atoms in the molecule are linked together in a chain. These include chain hydrocarbons (open-chain hydrocarbons) and cyclic hydrocarbons and their derivatives, excluding aromatic compounds.

[0097] The term "aromatic compound" usually refers to compounds that contain a benzene ring structure in their molecules.

[0098] In view of the problems in the background technology, the embodiments of this application provide a battery cell and its preparation method, a negative electrode sheet, a battery device and an electrical device, which can improve the wettability of the battery cell, thereby improving the cycle life and storage life of the battery cell.

[0099] battery cell

[0100] A battery cell includes a negative electrode sheet, the negative electrode sheet includes a negative current collector and a film layer disposed on at least one surface of the negative current collector, the film layer includes an additive, the main chain of the additive includes one or more of triazine ring groups, ether bonds and urethane groups, the end group of the additive includes silanol groups, and the side groups of the additive include one or more of silanol groups, triazine ring groups, ether bonds, alkyl groups, alkoxy groups and urethane groups.

[0101] The side groups of the additives in this application include silanol, triazine ring, ether, alkyl, alkoxy, and carbamate groups. These groups can be substituted or unsubstituted. The substituted groups can be one or more of the following: silanol, triazine ring, ether, alkyl, alkoxy, and carbamate groups.

[0102] In this application embodiment, a long-chain polymer structure can be formed by repeating the main chain groups, for example, when the main chain groups are ether bonds and urethane groups. In this case, the end groups of the additive include silanol groups. Silanol groups can enhance the hydrophilicity of the additive, allowing it to be better dispersed in the slurry. This, in turn, allows the additive to better coat the surface of the active particles, thereby improving the ion transport performance in the active material and increasing charge transport efficiency. Simultaneously, the film formed by the additive coating the surface of the active particles can absorb the stress generated by the volume expansion of the active particles, thereby reducing the volume change of the active particles during charging and discharging, thus improving the energy density, charging speed, and cycle stability of the battery cell.

[0103] In this application embodiment, a polymer cross-linked network structure can be formed by repeating the main chain groups, for example, when the main chain groups are triazine ring groups. Compared with long-chain polymer structures and polymer network structures, polymer cross-linked network structures have more hydrophilic group grafting sites and the ability to absorb stress, thereby further improving the wettability of the electrode, reducing electrode defects, thereby reducing electrode impedance, and reducing the volume change of active particles during charging and discharging, thereby improving the energy density, charging speed and cycle stability of the battery cell.

[0104] In the above case, when the side group of the additive contains a triazine ring group, it can increase the grafting sites of the branch chain, thereby giving the additive a polymer network structure, which can improve the wettability of the electrode, reduce the defects of the electrode, and thus reduce the impedance of the electrode, thereby improving the cycle life and storage life of the battery cell; and when the side group of the additive also contains silanol groups, it can further improve the hydrophilicity of the additive.

[0105] In some embodiments, the additive includes one or more of the first additive shown in formula (1) and the second additive shown in formula (2):

[0106] Among them, R 1-1 -R 1-4 Independently includes any one of C1-C4 alkyl groups, C1-C4 alkoxy groups, and groups shown in formula (1-1); R 2-9 -R 2-11 Including C1-C8 alkyl groups; R 2-1 -R 2-8 R 2-12 -R 2-14 Independently includes any one of C1-C4 alkyl, C1-C4 alkoxy, group shown in formula (1-1), group shown in formula (2-1), group shown in formula (2-2), and group shown in formula (2-3); R1 and R2 independently include polyurethane group and / or polyether group; n1 and n2 independently include 10 to 10000;

[0107] Among them, R 1-5 -R 1-8 R 2-15 -R 2-22 R 2-26 -R 2-28 R 2-29 -R 2-36 R 2-40 -R 2-42 R 3-1 R 3-2 R 3-6 -R 3-10 and R 3-12 -R 3-16 Independently includes any one of C1-C4 alkyl groups, C1-C4 alkoxy groups, and silanol-containing groups; R 2-23 -R 2-25 R 2-37 -R 2-39 R3-R6, R 3-3 and R 3-11 Independently includes C1-C8 alkyl groups; R1 1 R2 1 R22 It independently includes polyurethane groups and / or polyether groups; n3-n6 are independently 10 to 10000, n1 is greater than n3, and n2 is greater than any one of n3 to n6.

[0108] When the wettability of the electrode is poor, the ion transport path becomes longer, which in turn hinders the shuttle of ions between the positive and negative electrodes. The electrode that is not in contact with the electrolyte cannot participate in the electrochemical reaction of the battery, which increases the interfacial resistance and reduces the rate performance, discharge capacity and lifespan of the battery cell.

[0109] When one or more of the first additive shown in formula (1) and the second additive shown in formula (2) of this application are applied to a battery cell, the polymer network structure containing silicon-oxygen bonds in the first additive shown in formula (1) and the second additive shown in formula (2) can absorb and retain more electrolyte to improve the wettability of the electrode, reduce the defects of the electrode, and thus reduce the impedance of the electrode, thereby improving the cycle life and storage life of the battery cell.

[0110] The second additive shown in formula (2) contains a triazine ring structure, which can provide more crosslinking sites, thereby giving the second additive a polymer crosslinking network structure and improving its wettability. In addition, the polymer network structure with silicon-oxygen bonds can enhance the hydrophilicity of the first and second additives, so that the first and second additives can be better dispersed in the slurry, and thus the first and second additives can be better coated on the surface of the active particles, thereby improving the ion transport performance in the active material and increasing the charge transport efficiency. At the same time, the film layer formed by the first and second additives coating the surface of the active particles can also absorb the stress generated by the volume expansion of the active particles, thereby reducing the volume change of the active particles during charging and discharging, thereby improving the energy density, charging speed and cycle stability of the battery cell.

[0111] The additives in the embodiments of this application can be the first additive shown in formula (1), the second additive shown in formula (2), or a mixture of the first additive shown in formula (1) and the second additive shown in formula (2).

[0112] The structure of the additive, the structural units shown in formula (1), and the structural units shown in formula (2) and their contents can be determined using methods known in the art. As an example, the obtained electrode can be cleaned, the film layer scraped off, and then the elemental distribution map in the film layer can be obtained by EDX or EDS elemental analysis combined with TEM or SEM (such as the X-Max EDS of Oxford Instruments Group in the UK combined with the Sigma-02-33 SEM of ZEISS in Germany) surface scanning test. Then, the characteristic functional groups of the film layer can be tested, for example, by nuclear magnetic resonance spectroscopy. Nuclear magnetic resonance spectroscopy is used to study the absorption of radio frequency radiation by atomic nuclei in a strong magnetic field. It is one of the most powerful tools for qualitative analysis of the composition and structure of various organic and inorganic substances, and sometimes it can also be used for quantitative analysis. At the same time, it can also be combined with infrared spectroscopy, for example, by Fourier transform infrared spectroscopy (FTIR) test, the interaction between infrared radiation and the vibration or rotation of molecules, and structural analysis can be performed by recording the infrared absorption spectrum of the sample.

[0113] The following test steps can be used to detect organic functional groups using infrared spectroscopy: An infrared beam passes through a depth of a few μm on the surface of an electrode (ATR is a Ge crystal). When irradiated with infrared light of continuously varying frequencies, molecules on the electrode surface absorb radiation at certain frequencies. This absorption causes a net change in the dipole moment due to their vibrational or rotational motion, resulting in transitions from the ground state to excited states in molecular vibrational and rotational energy levels. This weakens the intensity of transmitted light corresponding to these absorption regions. Recording the percentage transmittance versus wavenumber curve yields the infrared spectrum. The infrared spectrum and functional group analysis results are then obtained. For example, the national standard GB / T6040-2002, "General Rules for Infrared Spectroscopic Analysis," can be referenced. Alternatively, ICP testing can be used, for example, referring to standards YS / T1006.2-2014, GB / T23367.2-2009, or YS / T1028.5-2015.

[0114] Alternatively, an ICP inductively coupled plasma atomic emission spectrometer (model iCAP 740) can be used, and measurements can be performed according to the manufacturer's instructions. Further analysis can be performed by combining pyrolysis gravimetric analysis and gas chromatography-mass spectrometry.

[0115] In some embodiments, R1, R2, R1 1 R2 1 R2 2 Independently includes any one of the groups shown in formula (3-1), formula (3-2), formula (3-3), formula (3-4), formula (3-5), and formula (3-6);

[0116] R7, R 19 R 20 and R25 Independently selected from any one of hydrogen atoms and C1-C4 alkyl groups; R 10 and R 11 Alkyl groups independently selected from C1-C4; R8, R9, R 17 R 18 R 21 R 22 R 23 and R 24 Independently selected from or lacking C1-C6 alkylene groups; R 12 and R 16 Independently selected from any one of the following: an alkylene divalent group substituted with an aliphatic compound having at least three carbon atoms, an alkylene divalent group substituted with an aliphatic compound having one carbon atom, and an alkylene divalent group substituted with an aromatic compound, or R 12 and R 16 Independently missing; R 14 Selected from any one of C1-C6 alkylene groups and phenyl groups substituted with at least two methyl or ethyl groups; R 13 and R 15 Independently selected from C2-C200 divalent hydrocarbon groups or omitted; Ar is aryl, n7-n 14 And m independently ranges from 10 to 10000.

[0117] In the embodiments of this application, the absence of a group means that the group may not exist in the corresponding structural formula. For example, the absence of R8 and R9 means that R8 and R9 do not exist in formula (3-2).

[0118] The additives in this application embodiment can better improve the wettability of the electrode, reduce electrode defects, and thus reduce electrode impedance, thereby improving the cycle life and storage life of the battery cell. 13 and R 15 It can independently be an aliphatic alkane, an aromatic substituted alkane, or an unsaturated alkene; and when R 13 and R 15 When it is an unsaturated olefin structure on its own, the unsaturated double bond is attached to the main chain of formula (3-3) or to the substituted side chain of formula (3-3), or is distributed on both the main chain and the substituted side chain of formula (3-3).

[0119] In some embodiments, the number average molecular weights of the first additive shown in formula (1) and the second additive shown in formula (2) are within a suitable range.

[0120] When the number-average molecular weight of an additive is low, its effect on reducing electrode expansion becomes less pronounced. When the number-average molecular weight of an additive is high, its flexibility and compatibility with the active material decrease, which also leads to a less effective reduction in electrode expansion and a less significant improvement in the cycle performance of the battery cell.

[0121] The first and second additives in the embodiments of this application, having suitable number-average molecular weight ranges, can balance wettability and reduction of volume expansion of active materials, thereby improving the cycle life, storage life, and cycle stability of battery cells.

[0122] In some embodiments, based on the additive, the mass content of the first additive shown in formula (1) is less than the mass content of the second additive shown in formula (2).

[0123] This application uses a mixture of a first additive and a second additive as the additive. The second additive contains a triazine ring structure, which can graft different groups at different amino sites, giving the second additive a polymer cross-linked network structure. This improves the stability of the additive and the SEI film, reducing the possibility of slippage during liquid absorption and swelling. The first additive contains a long-chain structure, and the resulting network structure has better flexibility. This allows the additive film layer coated on the surface of the active particles to better absorb the stress generated by the volume expansion of the active particles, thereby reducing the volume change of the active particles during charge and discharge. This can better improve the cycle stability of the battery cell.

[0124] In some embodiments, the swelling rate of the additive is 70% to 500%.

[0125] Optionally, the swelling rate of the additive is 100% to 400%.

[0126] In this application, the swelling ratio of the additive has a meaning known in the art and can be measured using instruments and methods known in the art. For example: Take a certain mass of additive, the initial mass is recorded as M; immerse the additive in electrolyte at 45°C for 2 days, remove it, gently wipe off the residual electrolyte on the surface, and record the weight M0. Calculate the swelling ratio using the following formula: η = [(M0 - M) / M] × 100%. Another example: Disassemble a battery cell to obtain the additive, the initial mass is recorded as M; after drying the additive, record the weight M0. Calculate the swelling ratio using the following formula: η = [(M - M0) / M0] × 100%.

[0127] Optionally, the swelling rate of the additive is independently selected from any value or a range between any two of 70%, 80%, 90%, 100%, 110%, 120%, 130%, 140%, 150%, 160%, 170%, 180%, 190%, 200%, 210%, 220%, 230%, 240%, 250%, 260%, 270%, 280%, 290%, 300%, 310%, 320%, 330%, 340%, 350%, 360%, 370%, 380%, 390%, 400%, 410%, 420%, 430%, 440%, 450%, 460%, 470%, 480%, 490%, and 500%.

[0128] In some embodiments, the membrane layer includes a negative electrode active material, and the mass ratio of the additive to the negative electrode active material is (0.05% to 5.00%): 1.

[0129] Optionally, the mass ratio of the additive to the negative electrode active material is (0.2% to 2.00%): 1.

[0130] The embodiments of this application have an appropriate ratio of additives and negative electrode active materials, which can make the additives form a liquid-absorbing film layer more uniformly between the negative electrode active materials, and can also make the thickness of the liquid-absorbing film layer coated on the surface of the negative electrode active particles more uniform, thereby better improving the cycle life, storage life and cycle stability of the battery cell.

[0131] Optionally, the mass ratio of the additive to the negative electrode active material is independently selected from 0.05%:1, 0.06%:1, 0.07%:1, 0.08%:1, 0.09%:1, 0.10%:1, 0.2%:1, 0.3%:1, 0.4%:1, 0.5%:1, 0.6%:1, 0.6%:1, 0.7%:1, 0.8%:1, 0.9%:1, 1.00%:1, 1.10%:1, 1.20%:1, 1.30%:1, 1.40%:1, 1.50%:1, 1.60%:1, 1.70%:1, 1.80%:1, 1.90%:1, 2.00%:1, 2.10%:1, 2.20%:1, 2... .30%: 1, 2.40%: 1, 2.50%: 1, 2.60%: 1, 2.70%: 1, 2.80%: 1, 2.90%: 1, 3.00%: 1, 3.10%: 1, 3.20%: 1, 3.30%: 1, 3.40%: 1, 3.50%: 1, 3.60%: 1, 3.70%: 1, 3.80%: 1, 3.90%: 1, 4.00%: 1, 4.10%: 1, 4.20%: 1, 4.30%: 1, 4.40%: 1, 4.50%: 1, 4.60%: 1, 4.70%: 1, 4.80%: 1, 4.90%: 1, 5.00%: 1. Any value in the range of 1 or any range between 1 and 2.

[0132] In some embodiments, the additives account for 0.05% to 4.65% of the mass based on the film layer.

[0133] Optionally, based on the membrane layer, the mass percentage of the additive is 0.20% to 2.00%.

[0134] The additives in this application embodiment with an appropriate mass ratio can improve the wettability of the active material while increasing the mass ratio of the active material, so as to balance the stability and energy density of the battery cell.

[0135] Optionally, based on the membrane layer, the mass percentage of the additive is independently selected from 0.05%, 0.10%, 0.15%, 0.20%, 0.25%, 0.30%, 0.35%, 0.40%, 0.45%, 0.50%, 0.55%, 0.60%, 0.65%, 0.70%, 0.75%, 0.80%, 0.85%, 0.90%, 0.95%, 1.00%, 1.05%, 1 10%, 1.15%, 1.20%, 1.25%, 1.30%, 1.35%, 1.40%, 1.45%, 1.50%, 1.55%, 1.60%, 1.65%, 1.70%, 1.75%, 1.80%, 1.85%, 1.90%, 1.95%, 2.00%, 2.05%, 2.10%, 2.15%, 2.20%, 2.25%, 2.30%, 2.35%, 2.40%, 2.45%, 2.50%, 2.55%, 2.60%, 2.65%, 2.70%, 2.75%, 2.80%, 2.85%, 2.90%, 2.95%, 3.00%, 3.05%, 3.10%, 3.15%, 3.20%, 3.25%, 3.30%, 3.35%, 3.40%, 3.45%, 3.50%, 3.55% The value can be any value from 3.60%, 3.65%, 3.70%, 3.75%, 3.80%, 3.85%, 3.90%, 3.95%, 4.00%, 4.05%, 4.10%, 4.15%, 4.20%, 4.25%, 4.30%, 4.35%, 4.40%, 4.45%, 4.50%, 4.55%, 4.60%, 4.65%, or any value between any two.

[0136] In some embodiments, the battery cell further includes a positive electrode sheet, which includes a positive electrode active material, and the positive electrode active material includes one or more of lithium transition metal oxides and lithium phosphates.

[0137] Optionally, lithium transition metal oxides include those having the general formula Li a Ni b Co c M d O e D f One or more of lithium transition metal oxides and their modified compounds, 0.8≤a≤1.2, 0.5≤b<1, 0<c<1, 0<d<1, 1≤e≤2, 0≤f≤1, M includes one or more of Ge, Mo, Sn, Mn, Al, Zr, Zn, Cu, Cr, Mg, Fe, V, Ti and B, and D includes one or more of N, F, S and Cl.

[0138] Optionally, the lithium-containing phosphate includes one or more of lithium iron phosphate and lithium manganese iron phosphate.

[0139] In some embodiments, the negative electrode active material includes one or more of carbon-based materials and silicon-based materials;

[0140] Alternatively, the carbon-based material includes one or more of natural graphite, artificial graphite, soft carbon, and hard carbon.

[0141] Optionally, the silicon-based material includes one or more of elemental silicon, silicon oxide, silicon-carbon composite, silicon-nitrogen composite, and silicon alloy materials.

[0142] In some embodiments, the negative electrode active material satisfies at least one of the following conditions:

[0143] (1) The specific surface area of ​​the negative electrode active material is 0.5–2.6 m². 2 / g;

[0144] (2) The Dv50 of the negative electrode active material is 8-25 μm.

[0145] Optionally, the specific surface area of ​​the negative electrode active material is independently selected from 0.5 m². 2 / g, 0.6m 2 / g, 0.7m 2 / g, 0.8m 2 / g, 0.9m 2 / g, 1.0m 2 / g, 1.1m 2 / g, 1.2m 2 / g, 1.3m 2 / g, 1.4m 2 / g, 1.5m 2 / g, 1.6m 2 / g, 1.7m 2 / g, 1.8m 2 / g, 1.9m 2 / g, 2.0m 2 / g、2.1m 2 / g, 2.2m 2 / g, 2.3m 2 / g, 2.4m 2 / g, 2.5m 2 / g, 2.6m 2 Any value in / g or any range between the two.

[0146] Optionally, the Dv50 of the negative electrode active material is independently selected from any value or a range between 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm, 21 μm, 22 μm, 23 μm, 24 μm, and 25 μm.

[0147] [Positive electrode plate]

[0148] In some embodiments, the positive electrode includes a positive current collector and a positive electrode film layer disposed on at least one surface of the positive current collector and comprising a positive electrode active material. For example, the positive current collector has two surfaces opposite each other in its thickness direction, and the positive electrode film layer is disposed on either or both of the two opposite surfaces of the positive current collector.

[0149] In some embodiments, the positive electrode active material includes a material capable of extracting and inserting lithium.

[0150] In some embodiments, the positive electrode active material may simultaneously comprise lithium transition metal oxide and lithium phosphate. This is advantageous for obtaining battery cells that balance high capacity and high reliability.

[0151] As an example, the positive electrode active material may include, but is not limited to, LiCoO2, LiNiO2, LiMnO2, and LiNi 1 / 2 Mn 1 / 2 O2, LiMn2O4, Li 4 / 3 Ti 5 / 3 O4, LiNi 1 / 2 Mn 1 / 2 O2, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2(NCM333), LiNi 0.5 Co 0.2 Mn 0.3 O2(NCM523), LiNi 0.6 Co 0.2 Mn 0.2 O2(NCM622), LiNi 0.8 Co 0.1 Mn 0.1 O2(NCM811), LiNi 0.80 Co 0.15 Al 0.05 O2, LiFePO4, LiMnPO4, Li 1.13 Ti 0.57 Fe 0.3 One or more of S2.

[0152] The modified compounds for the above-mentioned positive electrode active materials can be obtained by doping and / or surface coating of the positive electrode active materials.

[0153] In some embodiments, the positive electrode film may optionally include a positive electrode conductive agent. As an example, the positive electrode conductive agent may include, but is not limited to, one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0154] In some embodiments, the positive electrode film layer may optionally include a positive electrode binder. As an example, the positive electrode binder may include, but is not limited to, one or more of the following: polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, polyethylene oxide, fluorinated acrylate resins, styrene-butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, waterborne acrylic resins (e.g., polyacrylic acid PAA, polymethacrylic acid PMAA, sodium polyacrylate PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS).

[0155] In some embodiments, the positive current collector may be a metal foil or a composite current collector. An example of a metal foil is aluminum foil. The composite current collector may include a polymer substrate and a metal layer formed on at least one surface of the polymer substrate. As an example, the metal material may include, but is not limited to, one or more of aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. As an example, the polymer substrate may include, but is not limited to, one or more of polypropylene, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0156] The positive electrode film is typically formed by coating a positive electrode slurry onto a positive electrode current collector, followed by drying and cold pressing. The positive electrode slurry is usually formed by dispersing positive electrode active materials, positive electrode conductive agents, positive electrode binders, and any other components in a solvent and stirring until homogeneous. The solvent can be N-methylpyrrolidone (NMP), but is not limited to this.

[0157] [Negative electrode plate]

[0158] In some embodiments, the negative electrode sheet may include a negative current collector and a negative electrode film layer disposed on at least one surface of the negative current collector and comprising a negative electrode active material. For example, the negative current collector has two surfaces opposite each other in its thickness direction, and the negative electrode film layer is disposed on either or both of the two opposite surfaces of the negative current collector.

[0159] In some embodiments, the negative electrode film layer may further include a negative electrode conductive agent. As an example, the negative electrode conductive agent may include, but is not limited to, one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0160] In some embodiments, the negative electrode film layer may further include a negative electrode binder. As an example, the negative electrode binder may include, but is not limited to, one or more of styrene-butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, waterborne acrylic resins (e.g., polyacrylic acid PAA, polymethacrylic acid PMAA, sodium polyacrylate PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS).

[0161] In some embodiments, the negative electrode film layer may also include other additives. As an example, other additives may include thickeners, such as sodium carboxymethyl cellulose (CMC), PTC thermistor materials, etc.

[0162] 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, copper foil may be used. The composite current collector may include a polymeric material substrate and a metal material layer formed on at least one surface of the polymeric material substrate. As an example, the metal material may include, but is not limited to, one or more of copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. As an example, the polymeric material substrate may include, but is not limited to, one or more of polypropylene, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene, and polyethylene.

[0163] The negative electrode film is typically formed by coating a negative electrode slurry onto a negative electrode current collector, followed by drying and cold pressing. The negative electrode slurry is usually formed by dispersing the negative electrode active material, negative electrode conductive agent, negative electrode binder, and other optional additives in a solvent and stirring until homogeneous. The solvent can be N-methylpyrrolidone (NMP) or deionized water, but is not limited to these.

[0164] The negative electrode sheet does not exclude other additional functional layers besides the negative electrode film layer. For example, in some embodiments, the negative electrode sheet also includes a conductive undercoat layer (e.g., composed of a conductive agent and a binder) sandwiched between the negative electrode current collector and the negative electrode film layer and disposed on the surface of the negative electrode current collector.

[0165] In some embodiments, the negative electrode sheet can be made of foamed metal. The foamed metal can be foamed nickel, foamed copper, foamed aluminum, foamed alloy, foamed carbon, etc. When foamed metal is used as the negative electrode sheet, the surface of the foamed metal may or may not contain a negative electrode active material.

[0166] [Electrolytes]

[0167] This application does not impose specific limitations on the type of electrolyte, which can be selected according to requirements. For example, the electrolyte can be selected from at least one of solid electrolytes and liquid electrolytes (i.e., electrolyte solutions).

[0168] In some embodiments, the electrolyte is an electrolyte solution comprising an electrolyte salt and a solvent.

[0169] Taking a lithium battery cell as an example, the electrolyte salt may include, but is not limited to, one or more of the following: lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorooxalate borate (LiDFOB), lithium dioxalate borate (LiBOB), lithium difluorophosphate (LiPO2F2), lithium difluorodioxalate phosphate (LiDFOP), and lithium tetrafluorooxalate phosphate (LiTFOP).

[0170] Taking sodium battery cells as an example, the electrolyte salt may include, but is not limited to, one or more of the following: sodium hexafluorophosphate (NaPF6), sodium tetrafluoroborate (NaBF4), sodium perchlorate (NaClO4), sodium hexafluoroarsenate (NaAsF6), sodium difluorosulfonyl imide (NaFSI), sodium difluoromethanesulfonyl imide (NaTFSI), sodium trifluoromethanesulfonate (NaTFS), sodium difluorooxalate borate (NaDFOB), sodium dioxalate borate (NaBOB), sodium difluorophosphate (NaPO2F2), sodium difluorodioxalate phosphate (NaDFOP), and sodium tetrafluorooxalate phosphate (NaTFOP).

[0171] The type of solvent is not specifically limited and can be selected according to actual needs. In some embodiments, as an example, the solvent may include at least one of ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butyl carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), methyl ethyl sulfone (EMS), and diethyl sulfone (ESE).

[0172] In some embodiments, the electrolyte may optionally include additives. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain properties of the battery cell, such as additives that improve the overcharge performance of the battery cell, additives that improve the high-temperature performance of the battery cell, and additives that improve the low-temperature power performance of the battery cell.

[0173] [Isolation membrane]

[0174] Battery cells using electrolytes, as well as some battery cells using solid electrolytes, also include a separator. The separator is disposed between the positive and negative electrodes, primarily serving to prevent short circuits between the positive and negative electrodes, while allowing metal ions to pass through. This application does not impose any particular limitation on the type of separator; any known porous separator with good chemical and mechanical stability can be selected.

[0175] In some embodiments, the isolation membrane includes a porous base membrane and a coating located on at least one side of the porous base membrane.

[0176] In some embodiments, the material of the separator may include at least one selected from glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may be a single-layer film or a multi-layer composite film. When the separator is a multi-layer composite film, the materials of each layer may be the same or different.

[0177] In some embodiments, the coating includes an adhesive, which may include, but is not limited to, one or more of polyacrylate adhesives, nitrile rubber adhesives, polyacrylic acid, polymethacrylic acid, sodium polyacrylate, polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS).

[0178] In some embodiments, the coating may further include a dispersant, such as one or more of alkylphenol polyoxyethylene ethers, polyacrylic acid dispersants, and cellulose dispersants, including but not limited to. For example, the dispersant may include one or more of sodium carboxymethyl cellulose, sodium polyacrylate, and ammonium polyacrylate.

[0179] Preparation method of battery cell

[0180] A method for preparing a battery cell includes: providing a positive electrode, a negative electrode, a separator, and an electrolyte; providing a slurry comprising an additive precursor liquid, a negative electrode active material, and a solvent, wherein the additive precursor liquid comprises a first raw material having the structure shown in formula (4); coating the slurry onto the surface of the negative electrode, and drying it to form a negative electrode with an additive film layer, wherein the main chain of the additive comprises one or more of triazine ring groups, ether bonds, and urethane groups, the end group of the additive comprises silanol groups, and the side groups of the additive comprise one or more of silanol groups, triazine ring groups, ether bonds, alkyl groups, alkoxy groups, and urethane groups; assembling the positive electrode, the negative electrode, the separator, and the electrolyte to obtain a battery cell, wherein the separator is located between the positive electrode and the negative electrode;

[0181] Among them, R 20 Including polyurethane groups and / or polyether groups, R 20-1 -R 20-6 Independently includes any one of C1-C4 alkyl and C1-C4 alkoxy groups, and R 20-1 -R 20-6 At least one of them includes a C1-C4 alkoxy group.

[0182] As shown in formulas (6) and (7), in the embodiments of this application, the first raw material containing alkoxy groups is added when preparing the negative electrode slurry, so that the first raw material can undergo a hydrolysis reaction with water to hydrolyze the alkoxy groups connected to the silicon group into silanol groups, thereby obtaining a first precursor containing silanol groups; and during the drying process of the slurry, the first precursor will undergo a dehydration condensation reaction to form siloxane-silicon bonds between multiple first precursors through dehydration condensation, thereby forming a first additive with a network structure as shown in formula (1), thereby making the first additive uniformly dispersed on the surface of the active material.

[0183] In this embodiment, an additive precursor liquid is added during the preparation of the slurry, which allows the additive precursor liquid to be mixed evenly with the active material before crosslinking, so that the additive formed after crosslinking can be evenly dispersed on the surface of the active material, thereby improving the wettability of the film layer.

[0184] In some embodiments, in order to make the first raw material more fully hydrolyzed, the first raw material can be hydrolyzed in advance. The additive precursor liquid includes: mixing the first raw material having the structure shown in formula (4) with water and carrying out a hydrolysis reaction under certain conditions to obtain the additive precursor liquid.

[0185] In some embodiments, the additive precursor fluid further includes a second raw material having the structure shown in formula (5);

[0186] Among them, R21-1 -R 21-9 Independently includes any one of C1-C4 alkyl and C1-C4 alkoxy groups, and R 21- 1-R 21-9 At least one of them includes a C1-C4 alkoxy group, R 21 -R 23 Independently includes C1-C4 alkyl groups.

[0187] In this embodiment, a first raw material containing alkoxy groups and a second raw material containing alkoxy groups and crosslinking sites can be added together when preparing the negative electrode slurry. The first and second raw materials will undergo hydrolysis reactions with water to hydrolyze the alkoxy groups connected to the silicon group into silanol groups, thereby obtaining a first precursor containing silanol groups and a second precursor containing silanol groups and crosslinking sites. During the drying process of the slurry, the first and second precursors will undergo dehydration condensation reactions to dehydrate and condense the silanol groups of the first and second precursors to form silicon-oxygen-silicon bonds. At this time, the second raw material can act as a crosslinking agent, thereby forming a second additive with a crosslinking network structure as shown in formula (2), thereby making the second additive uniformly dispersed on the surface of the active material.

[0188] In some embodiments, in order to make the first raw material and the second raw material more fully hydrolyzed, the first raw material and the second raw material can be hydrolyzed in advance. The additive precursor liquid includes: mixing the first raw material having the structure shown in formula (4), the second raw material having the structure shown in formula (5) and water, and carrying out a hydrolysis reaction under certain conditions to obtain the additive precursor liquid.

[0189] In some embodiments, the number average molecular weight of the first raw material is 2000-10000 Da, and the number average molecular weight of the second raw material is 500-700 Da.

[0190] Optionally, the number average molecular weight of the first raw material is independently selected from 2000 Da, 2100 Da, 2200 Da, 2300 Da, 2400 Da, 2500 Da, 2600 Da, 2700 Da, 2800 Da, 2900 Da, 3000 Da, 3100 Da, 3200 Da, 3300 Da, 3400 Da, 3500 Da, 3600 Da, 3700 Da, and 3800 Da. a. 3900Da, 4000Da, 4100Da, 4200Da, 4300Da, 4400Da, 4500Da, 4600Da, 4700Da, 4800Da, 490 0Da, 5000Da, 5100Da, 5200Da, 5300Da, 5400Da, 5500Da, 5600Da, 5700Da, 5800Da, 5900Da, 60 00Da, 6100Da, 6200Da, 6300Da, 6400Da, 6500Da, 6600Da, 6700Da, 6800Da, 6900Da, 7000Da, 7100Da, 7200Da, 7300Da, 7400Da, 7500Da, 7600Da, 7700Da, 7800Da, 7900Da, 8000Da, 8100Da Any value from 8200Da, 8300Da, 8400Da, 8500Da, 8600Da, 8700Da, 8800Da, 8900Da, 9000Da, 9100Da, 9200Da, 9300Da, 9400Da, 9500Da, 9600Da, 9700Da, 9800Da, 9900Da, 10000Da, or any value between any two.

[0191] Optionally, the number average molecular weight of the second raw material is independently selected from any value or a range between 500Da, 510Da, 520Da, 530Da, 540Da, 550Da, 560Da, 570Da, 580Da, 590Da, 600Da, 610Da, 620Da, 630Da, 640Da, 650Da, 660Da, 670Da, 680Da, 690Da, and 700Da.

[0192] In some embodiments, the first raw material includes one or more of silane-terminated polyurethane and silane-terminated polyether.

[0193] In the embodiments of this application, silane-terminated polyurethane and silane-terminated polyether refer to the introduction of silane segments by modifying the end groups of polyurethane prepolymer and polyether prepolymer through chemical reaction.

[0194] In some embodiments, the second raw material includes one or more of 1,3,5-tris(trimethoxysilylpropyl)isocyanurate, 1,3-di(trimethoxysilylpropyl)-5-dimethoxysilylpropyl isocyanurate and 1,3-di(trimethoxysilylpropyl)-5-methoxysilylpropyl isocyanurate.

[0195] In some embodiments, the hydrolysis reaction takes 8 to 15 minutes and the hydrolysis reaction temperature is 90 to 110°C.

[0196] In some embodiments, the temperature for drying the slurry coated on the surface of the negative electrode sheet is 60–120°C, and the time is 5–360 min.

[0197] Optionally, the drying temperature is independently selected from any value or a range between 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, and 120°C.

[0198] Optionally, the drying time is independently selected from any value or a range between any two of 5 min, 10 min, 20 min, 30 min, 40 min, 50 min, 60 min, 70 min, 80 min, 90 min, 100 min, 110 min, 120 min, 130 min, 140 min, 150 min, 160 min, 170 min, 180 min, 190 min, 200 min, 210 min, 220 min, 230 min, 240 min, 250 min, 260 min, 270 min, 280 min, 290 min, 300 min, 310 min, 320 min, 330 min, 340 min, 350 min, and 360 min.

[0199] In some embodiments, those skilled in the art can obtain a first additive with a preset number average molecular weight or a second additive with a preset number average molecular weight by adjusting the mass ratio of the first raw material in the slurry or by adjusting the ratio of the first raw material and the second raw material.

[0200] Negative electrode sheet

[0201] A negative electrode sheet includes a negative current collector and a negative electrode film layer disposed on at least one surface of the negative current collector. The negative electrode film layer includes an additive. The main chain of the additive includes one or more of triazine ring groups, ether bonds, and urethane groups. The end group of the additive includes silanol groups. The side groups of the additive include one or more of silanol groups, triazine ring groups, ether bonds, alkyl groups, alkoxy groups, and urethane groups.

[0202] In some embodiments, the contact angle θ of the negative electrode at 25°C satisfies 0°≤θ≤30°.

[0203] Optionally, the contact angle θ of the negative electrode at 25°C satisfies 0°≤θ≤20°.

[0204] The electrode with a suitable contact angle θ in the embodiments of this application can make the negative electrode better wettable, so that the electrolyte can better wet the negative electrode, thereby enabling the negative electrode to absorb and store more electrolyte, and thus improve the cycle life and storage life of the battery cell.

[0205] In this application, the contact angle θ has a well-known meaning in the art, referring to the angle between the liquid surface and the solid surface when the electrolyte comes into contact with the solid surface, and can be measured using instruments and methods known in the art. For example, for contact angle testing with non-aqueous solvents, a solvent is prepared by mixing EC and EMC in a volume ratio of 7:3. After the solvent is suspended and dropped onto the surface of the negative electrode, the amount added is 10μL±1μL, and the measurement is performed using an Easy Drop contact angle measuring instrument (KRuss, Germany).

[0206] Optionally, the contact angle θ of the negative electrode at 25°C is independently selected from any value or a range between any two of 0°, 1°, 2°, 3°, 4°, 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°, and 30°.

[0207] In some embodiments, the liquid absorption rate of the negative electrode is 15.00% to 40.00%.

[0208] Optionally, the liquid absorption rate of the negative electrode sheet is 28.00% to 40.00%.

[0209] In this application, the liquid absorption rate of the negative electrode sheet has a meaning known in the art and can be measured using instruments and methods known in the art. For example: Negative electrode sheet liquid absorption rate test: Take a circular negative electrode sheet with a diameter of 2.2 cm from each group, weigh it and record it as 'a', immerse the negative electrode sheet in electrolyte for 1 hour to allow it to fully absorb the electrolyte. After absorption, wipe the electrolyte off the surface of the negative electrode sheet, weigh it and record it as 'b', the liquid absorption rate of the negative electrode sheet is (ba) / a × 100%. Another example: Disassemble a battery cell to obtain a negative electrode sheet, the initial mass is recorded as 'a'; after drying the negative electrode sheet, record the weight as 'b'. Calculate the swelling rate using the following formula: η = [(a - b) / b] × 100%.

[0210] Optionally, the liquid absorption rate of the negative electrode is independently selected from any value or a range between 15.00%, 16.00%, 17.00%, 18.00%, 19.00%, 20.00%, 21.00%, 22.00%, 23.00%, 24.00%, 25.00%, 26.00%, 27.00%, 28.00%, 29.00%, 30.00%, 31.00%, 32.00%, 33.00%, 34.00%, 35.00%, 36.00%, 37.00%, 38.00%, 39.00%, and 40.00%.

[0211] Example

[0212] The following embodiments describe the disclosure of this application in more detail. These embodiments are merely illustrative, as various modifications and variations will be apparent to those skilled in the art within the scope of the disclosure of this application. 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 by conventional methods and can be used directly without further processing, and the instruments used in the embodiments are commercially available.

[0213] Provide a separating membrane:

[0214] A PE (polyethylene) substrate with a thickness of 12μm is provided.

[0215] Preparation of negative electrode sheet:

[0216] 1.1A: The first raw material and water are mixed in a certain ratio to obtain a solution containing the additive precursor;

[0217] or,

[0218] 1.1B: The first raw material, the second raw material, and water are mixed in a certain proportion to obtain a solution containing the additive precursor.

[0219] 2. Graphite, conductive carbon black, binder CMC, polystyrene-butadiene rubber SBR, and the above-mentioned solution containing additive precursors were added to a mixer in a weight ratio of 95.7%:1%:1%:2%:0.3%. Deionized water was then added, and the mixture was stirred under vacuum until homogeneous, yielding a negative electrode slurry with a solid content of 53 wt%. The negative electrode slurry was uniformly coated on both sides of the negative electrode current collector copper foil (6 micrometers thick), with a coating width of 75 mm and a single-sided coating weight of 110 g / m². 2The material is dried in a nine-section oven with temperature settings of 100℃ / 100℃ / 95℃ / 85℃ / 85℃ / 80℃ / 80℃ / 80℃ / 60℃, and then compacted using a cold press to a depth of 152 microns to obtain a negative electrode sheet containing additives.

[0220] Preparation of electrolyte:

[0221] In an argon atmosphere glove box (H2O < 0.1 ppm, O2 < 0.1 ppm), non-aqueous organic solvents fluoroethylene carbonate and methyl ethyl carbonate are mixed at a volume ratio of 1:1 to obtain a first solvent. The first solvent is then mixed with ethylene carbonate at a volume ratio of 2:1 to form a non-aqueous solvent. Lithium hexafluorophosphate is added to the non-aqueous solvent to prepare an electrolyte with a lithium hexafluorophosphate concentration of 1 mol / L.

[0222] Preparation of positive electrode sheet:

[0223] Take the positive electrode active material (lithium nickel cobalt manganese oxide, chemical formula LiNi) 0.8 Co 0.1 Mn 0.1 O2), conductive carbon black, and PVDF (polyvinylidene fluoride) were added to a mixer in a ratio of 95%:2.5%:2.5%. Nitrogen-methylpyrrolidone was then added to the mixture, and the mixture was stirred until homogeneous, forming a positive electrode slurry with a solid content of 63%. This positive electrode slurry was then coated onto both surfaces of a 13μm thick aluminum foil current collector, with a coating width of 70mm. The single-sided coating weight of the positive electrode material was 220g / m². 2 The electrode was heated and baked under vacuum conditions using a multi-section oven with temperatures set sequentially at 120℃, 100℃, and 90℃ for 5 to 10 hours. It was then compacted to 160 micrometers using a cold press, resulting in a positive electrode sheet with a compacted density of 3.0 g / cm³. 3 The positive electrode sheet.

[0224] Preparation of battery cells:

[0225] The positive electrode, separator, and negative electrode are wound in sequence, with the separator acting as a separator between the positive and negative electrodes. Three copper wires are added for the electrodes, and the tabs are welded together to form a wound battery cell. The wound battery cell is placed in an outer packaging shell, dried, and then injected with electrolyte. After vacuum sealing, settling, formation, and shaping, a battery cell is obtained with a rated capacity of 150mAh.

[0226] The preparation process parameters and additive structures are shown in Tables 1 and 2.

[0227] Table 1. Preparation process parameters of the additives Note: The structures of equations (4)-(7) and (3-1)-(3-5) in Table 1 are as follows:

[0228] Table 2 Additive Structure Note: The structural formulas of equations (1) and (2) in Table 2 are as follows:

[0229] Table 3 Process parameters of negative electrode sheet

[0230] Data Analysis

[0231] 1. Swelling rate test:

[0232] Take a certain mass of additive, and record the initial mass as M;

[0233] The additive was immersed in the electrolyte at 45°C for 2 days. After immersion, the additive was removed and the residual electrolyte on the surface was wiped off. The weight M0 was recorded.

[0234] Calculate the swelling ratio using the following formula:

[0235] η=[(M0-M) / M]×100%.

[0236] 2. Determination of electrode liquid absorption rate:

[0237] Negative electrode absorbance test: For each group, take a circular negative electrode with a diameter of 2.2 cm, weigh it and record the weight as 'a'. Immerse the negative electrode in the electrolyte for 1 hour to allow it to fully absorb the electrolyte. After absorption, wipe the electrolyte off the surface of the negative electrode, weigh it and record the weight as 'b'. The negative electrode absorbance rate is (ba) / a × 100%.

[0238] 3. Loop testing:

[0239] The battery cells were placed in a constant temperature chamber at 25℃ / 45℃, and their cycle life was tested according to the procedure:

[0240] 1) Charge at a constant current of 0.33C to 3.65V, then charge at a constant voltage of 3.65V to the cutoff current of 0.05C;

[0241] 2) Rest for 5 minutes;

[0242] 3) Discharge at a constant current of 0.33C to 2.5V;

[0243] 4) Rest for 5 minutes;

[0244] 5) Repeat steps 1-4) 800 times or until the capacity decays to 80% of the initial value.

[0245] 4. Storage test:

[0246] 1) At room temperature (25℃), follow the procedure (0.33C constant current charging to 3.65V, 3.65V constant voltage charging to cutoff current 0.05C; rest for 5 minutes; 0.33C constant current discharging to 2.5V (test initial capacity), rest for 5 minutes, 0.33C constant current charging to 3.65V, 3.65V constant voltage charging to cutoff current 0.05C), and fully charge;

[0247] 2) Place the individual battery cells in a constant temperature chamber at 60℃ for 45 days;

[0248] 3) At room temperature (25℃), follow the procedure (rest for 5 minutes; discharge at 0.33C constant current to 2.5V (maintain capacity), rest for 5 minutes, charge at 0.33C constant current to 3.65V, charge at 3.65V constant voltage to cutoff current 0.05C, rest for 5 minutes; discharge at 0.33C constant current to 2.5V (recover capacity).

[0249] Capacity recovery rate = recovered capacity / initial capacity; Capacity retention rate = retained capacity / initial capacity.

[0250] Table 4

[0251] As shown in Table 4, compared to Comparative Example 1, the addition of additives in Examples 1-10 can improve the wettability of battery cells, thereby improving the cycle life and storage life of battery cells. In Examples 1-10, the additive in Example 10 has the structure shown in Formula 1. Compared to the structure shown in Formula 2 in Examples 1-9, the structure shown in Formula 1 has a lower degree of cross-linking, higher liquid absorption and swelling rates, but weaker liquid retention capacity. Therefore, the cycle life and storage life of battery cells in Examples 1-9 are better than those in Example 10.

[0252] The above description is merely a specific implementation of this application. Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, modules, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here. It should be understood that the protection scope of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the protection scope of this application.

Claims

1. A battery cell, comprising a negative electrode sheet, wherein, The negative electrode includes a negative current collector and a film layer disposed on at least one surface of the negative current collector. The film layer includes an additive. The main chain of the additive includes one or more of triazine ring groups, ether bonds, and carbamate groups. The end group of the additive includes silanol groups. The side groups of the additive include one or more of silanol groups, triazine ring groups, ether bonds, alkyl groups, alkoxy groups, and carbamate groups.

2. The battery cell according to claim 1, wherein, The additive includes one or more of the first additive shown in formula (1) and the second additive shown in formula (2): Among them, R 1-1 -R 1-4 Independently includes any one of C1-C4 alkyl groups, C1-C4 alkoxy groups, and groups shown in formula (1-1); R 2-9 -R 2-11 Including C1-C8 alkyl groups; R 2-1 -R 2-8 R 2-12 -R 2-14 Independently includes any one of C1-C4 alkyl, C1-C4 alkoxy, group shown in formula (1-1), group shown in formula (2-1), group shown in formula (2-2), and group shown in formula (2-3); R1 and R2 independently include polyurethane group and / or polyether group; n1 and n2 independently include 10 to 10000; Among them, R 1-5 -R 1-8 R 2-15 -R 2-22 R 2-26 -R 2-28 R 2-29 -R 2-36 R 2-40 -R 2-42 R 3-1 R 3-2 R 3-6 -R 3-10 and R 3-12 -R 3-16 Independently includes any one of C1-C4 alkyl groups, C1-C4 alkoxy groups, and silanol groups; R 2-23 -R 2-25 R 2-37 -R 2-39 R3-R6, R 3-3 and R 3-11 Independently includes C1-C8 alkyl groups; R1 1 R2 1 R2 2 Independently includes polyurethane groups and / or polyether groups; n3-n6 are independently 10 to 10000, n1 is greater than n3, and n2 is greater than any one of n3 to n6.

3. The battery cell according to claim 2, wherein, R1, R2, R1 1 R2 1 R2 2 Independently includes any one of the groups shown in formula (3-1), formula (3-2), formula (3-3), formula (3-4), formula (3-5), and formula (3-6); R7, R 19 R 20 and R 25 Independently selected from any one of hydrogen atoms and C1-C4 alkyl groups; R 10 and R 11 Alkyl groups independently selected from C1-C4; R8, R9, R 17 R 18 R 21 R 22 R 23 and R 24 Alkyl groups selected independently from C1-C6 or omitted; R 12 and R 16 Independently selected from any one of the following: an alkylene divalent group substituted with an aliphatic compound having at least three carbon atoms, an alkylene divalent group substituted with an aliphatic compound having one carbon atom, and an alkylene divalent group substituted with an aromatic compound, or R 12 and R 16 Independently missing; R 14 Selected from any one of C1-C6 alkylene groups and phenyl groups substituted with at least two methyl or ethyl groups; R 13 and R 15 Independently selected from C2-C200 divalent hydrocarbon groups or absent; Ar is aryl, n7-n 14 And m independently ranges from 10 to 10000.

4. The battery cell according to any one of claims 1-3, wherein, The swelling rate of the additive is 70% to 500%; Optionally, the swelling rate of the additive is 100% to 400%.

5. The battery cell according to any one of claims 1-4, wherein, Based on the film layer, the mass percentage of the additive is 0.05% to 4.65%; Optionally, based on the film layer, the mass percentage of the additive is 0.20% to 2.00%.

6. The battery cell according to any one of claims 1-5, wherein, The membrane layer includes a negative electrode active material, and the mass ratio of the additive to the negative electrode active material is (0.05% to 5.00%): 1; Optionally, the mass ratio of the additive to the negative electrode active material is (0.2% to 2.00%):

1.

7. The battery cell according to claim 6, wherein, The negative electrode active material includes one or more of carbon-based materials and silicon-based materials; Optionally, the carbon-based material includes one or more of natural graphite, artificial graphite, soft carbon, and hard carbon; Optionally, the silicon-based material includes one or more of elemental silicon, silicon oxide, silicon-carbon composite, silicon-nitrogen composite, and silicon alloy materials.

8. The battery cell according to claim 7, wherein, The negative electrode active material satisfies at least one of the following conditions: (1) The specific surface area of ​​the negative electrode active material is 0.5–2.6 m². 2 / g; (2) The Dv50 of the negative electrode active material is 8 to 25 μm.

9. The battery cell according to any one of claims 1-8, wherein, The battery cell further includes a positive electrode sheet, which includes a positive electrode active material, and the positive electrode active material includes one or more of lithium transition metal oxides and lithium phosphates; Optionally, the lithium transition metal oxide comprises lithium having the general formula Li a Ni b Co c M d O e D f One or more of lithium transition metal oxides and their modified compounds, 0.8≤a≤1.2, 0.5≤b<1, 0<c<1, 0<d<1, 1≤e≤2, 0≤f≤1, M includes one or more of Ge, Mo, Sn, Mn, Al, Zr, Zn, Cu, Cr, Mg, Fe, V, Ti and B, and D includes one or more of N, F, S and Cl; Optionally, the lithium-containing phosphate includes one or more of lithium iron phosphate and lithium manganese iron phosphate.

10. A method for preparing a single battery cell, wherein, include: We provide positive electrode plates, negative electrode plates, separators, and electrolytes; A slurry comprising an additive precursor liquid, a negative electrode active material, and a solvent is provided, wherein the additive precursor liquid comprises a first raw material having the structure shown in formula (4); The slurry is coated on the surface of the negative electrode sheet and dried to form a negative electrode sheet with an additive film layer. The main chain of the additive includes one or more of triazine ring groups, ether bonds, and carbamate groups. The end group of the additive includes silanol groups. The side groups of the additive include one or more of silanol groups, triazine ring groups, ether bonds, alkyl groups, alkoxy groups, and carbamate groups. The positive electrode, the negative electrode, the separator, and the electrolyte are assembled to form a battery cell, wherein the separator is located between the positive electrode and the negative electrode. Among them, R 20 Including polyurethane groups and / or polyether groups, R 20-1 -R 20-6 Independently includes any one of C1-C4 alkyl and C1-C4 alkoxy groups, and R 20-1 -R 20-6 At least one of them includes a C1-C4 alkoxy group.

11. The preparation method according to claim 10, wherein, The additive precursor fluid includes: The first raw material having the structure shown in formula (4) is mixed with water and subjected to hydrolysis under certain conditions to obtain the precursor fluid of the additive.

12. The preparation method according to claim 10 or 11, wherein, The additive precursor fluid also includes a second raw material having the structure shown in formula (5); Among them, R 21-1 -R 21-9 Independently includes any one of C1-C4 alkyl and C1-C4 alkoxy groups, and R 21- 1-R 21-9 At least one of them includes a C1-C4 alkoxy group, R 21 -R 23 Independently includes C1-C4 alkyl groups.

13. The preparation method according to claim 12, wherein, The additive precursor fluid includes: The first raw material having the structure shown in formula (4), the second raw material having the structure shown in formula (5), and water are mixed and hydrolyzed under certain conditions to obtain the additive precursor liquid.

14. The preparation method according to claim 13, wherein, The number average molecular weight of the first raw material is 2000-10000 Da, and the number average molecular weight of the second raw material is 500-700 Da.

15. The preparation method according to claim 13 or 14, wherein, The first raw material includes one or more of silane-terminated polyurethane and silane-terminated polyether; The second raw material includes one or more of 1,3,5-tris(trimethoxysilylpropyl)isocyanurate, 1,3-di(trimethoxysilylpropyl)-5-dimethoxysilylpropyl isocyanurate and 1,3-di(trimethoxysilylpropyl)-5-methoxysilylpropyl isocyanurate.

16. The preparation method according to claim 11 or 13, wherein, The hydrolysis reaction takes 8–15 minutes and is carried out at a temperature of 90–110 °C.

17. The preparation method according to any one of claims 10-16, wherein, The temperature for drying the slurry applied to the surface of the negative electrode sheet is 60–120°C, and the time is 5–360 min.

18. A negative electrode plate, wherein, The negative electrode sheet includes a negative current collector and a negative electrode film layer disposed on at least one surface of the negative current collector, the negative electrode film layer including additives. The main chain of the additive includes one or more of triazine ring groups, ether bonds, and carbamate groups; the end groups of the additive include silanol groups; and the side groups of the additive include one or more of silanol groups, triazine ring groups, ether bonds, alkyl groups, alkoxy groups, and carbamate groups.

19. The negative electrode sheet according to claim 18, wherein, The contact angle θ of the negative electrode sheet at 25° satisfies 0°≤θ≤30°; Optionally, the contact angle θ of the negative electrode at 25°C satisfies 0°≤θ≤20°.

20. The negative electrode sheet according to claim 18 or 19, wherein, The liquid absorption rate of the negative electrode sheet is 15.00% to 40.00%; Optionally, the liquid absorption rate of the negative electrode sheet is 28.00% to 40.00%.

21. A battery device, wherein, It includes any one of the battery cells according to claims 1-9.

22. An electrical appliance, wherein, Includes the battery cell according to any one of claims 1-9 or the battery device according to claim 21.

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