Battery cells, batteries and electrical devices

Abstract

The present application provides a battery cell, a battery, and an electric device, the battery cell comprising an electrode assembly including a first pole piece, a second pole piece, and a separator, and an electrolyte, the first pole piece and the second pole piece having opposite polarities, the separator being disposed between the first pole piece and the second pole piece, and at least one of the first pole piece, the second pole piece, and the separator comprising a lyophilic polymer, the battery cell satisfying the following formula: [Number 1] JPEG2026502360000065.jpg684

Description

[Technical Field]

[0001] This application relates to the field of batteries, and more particularly to battery cells, batteries, and electrical devices. [Background technology]

[0002] Due to their characteristics such as high capacity and long life, battery cells are widely used in electronic devices such as mobile phones, laptops, electric scooters, electric cars, electric airplanes, electric boats, electric toy cars, electric toy boats, electric toy airplanes, and power tools.

[0003] As the application range of batteries becomes more and more widespread, the requirements for the performance of battery cells become more and more stringent. In order to improve the performance of battery cells, the usage reliability and cycle performance of battery cells are usually still low. Summary of the Invention

[0004] The present application has been made in view of the above problems, and its object is to provide a battery cell, a battery, and an electric device.

[0005] A first aspect of the present application is a battery cell including an electrode assembly including a first pole piece, a second pole piece, and a separator, and an electrolyte, wherein the polarities of the first pole piece and the second pole piece are opposite, the separator is disposed between the first pole piece and the second pole piece, and at least one of the first pole piece, the second pole piece, and the separator includes a lyophilic polymer, and the battery cell satisfies the following formula:

number

[0006] p1 represents the porosity of the first pole piece;

[0007] v1 is the total volume of the first pole piece in μm 3 It is expressed as

[0008] p2 represents the porosity of the second pole piece;

[0009] v2 is the total volume of the second pole piece in μm 3 It is expressed as

[0010] p3 represents the porosity of the separator,

[0011] v3 is the total volume of the separator in μm 3 It is expressed as

[0012] y represents the mass of free electrolyte in the battery cell in g, providing the battery cell.

[0013] In this way, when the embodiment of the present application satisfies the above formula, the lyophilic polymer has a relatively good affinity for the electrolyte, and the electrolyte can rapidly diffuse between the molecular chains of the lyophilic polymer and be encapsulated in the molecular chains, resulting in an elastic, porous, sustained-release electrolyte through swelling and adsorption. The sustained-release electrolyte can absorb the free electrolyte in the battery cell, reducing its presence. The free electrolyte is encapsulated, reducing the risk of extrusion, thereby reducing the risk of short circuits between the positive and negative electrode pieces caused by the formation of dendrites, and improving the reliability and cycle performance of the battery cell. The absorbed free electrolyte then forms a new cohesive electrolyte with the elastic, porous, sustained-release electrolyte, ensuring a relatively high electrolyte conductivity and thereby improving the electrical performance of the battery cell.

[0014] In some embodiments, the battery cells satisfy the following formula:

number

number

[0015] In this way, when the embodiment of the present application satisfies the above formula, it is possible to further improve both the reliability of use and the cycle performance of the battery cell.

[0016] In some embodiments, the battery cells also satisfy the following formula:

number

number

number

[0017] m1 is the mass of the electrode assembly before drying in g,

[0018] m2 represents the mass of the electrode assembly after drying in g.

[0019] In this way, when the embodiment of the present application satisfies the above formula, it is possible to further improve both the reliability of use and the cycle performance of the battery cell.

[0020] In some embodiments, the amount of free electrolyte per unit capacity of the battery cell is b, whose unit is mg / Ah, where 0≦b≦1400, optionally 0.1≦b≦1000, and further optionally 0.3≦b≦800.

[0021] In this way, when the embodiment of the present application satisfies the above formula, it is possible to further improve both the reliability of use and the cycle performance of the battery cell.

[0022] In some embodiments, the first pole piece includes a current collector and an active material layer disposed on at least one surface of the current collector, the active material layer including a lyophilic polymer and active material particles, the lyophilic polymer being distributed on the surfaces of the active material particles, and / or the active material particles are multiple and have pores between adjacent active material particles, and the lyophilic polymer being distributed in the pores between the active material particles.

[0023] In this way, the embodiments of the present application can improve the liquid retention ability of the first electrode by installing a lyophilic polymer on the first electrode, and can further achieve both the improvement of the reliability in use and the cycle performance of the battery cell.

[0024] In some embodiments, the separator includes a base material and a coating provided on at least one surface of the base material, the lyophilic polymer is distributed in the pores of the base material, and / or the lyophilic polymer is distributed in the coating, and / or the lyophilic polymer is provided on the surface of the coating away from the base material.

[0025] In this way, the embodiments of the present application can improve the liquid retention ability of the separator by installing a lyophilic polymer on the separator, and can further achieve both the improvement of the reliability in use and the cycle performance of the battery cell.

[0026] In some embodiments, the lyophilic polymer includes a fluoropolymer, the crystallinity of the fluoropolymer measured by differential scanning calorimetry is Xc1, 0 < Xc1 ≤ 30%, and the melting temperature of the fluoropolymer is T m1 , the unit is °C, 0 < T m1 ≤ 140.

[0027] In some embodiments, the glass transition temperature of the fluoropolymer is T g1 , the unit is °C, -150 ≤ T g1 ≤ 60.

[0028] [[ID=Z7]] In some embodiments, the fluoropolymer includes at least one of the structural units represented by formula (AI) to the structural units represented by formula (AIII),

Chemical formula

[0029] In formula (AI) and formula (AII), R 11 , R 12 , R 13 and R 14Each independently contains a hydrogen atom, a fluorine atom, a chlorine atom, a substituted or unsubstituted C1-C3 alkyl group or a substituted or unsubstituted C1-C3 alkoxy group, and R 11 、R 12 、R 13 and R 14 at least one of which contains a fluorine atom, and when substituted, the substituent contains one or more of a nitrile group (-CN), a nitro group, a sulfonic acid group, a sulfonyl group, an amide, a carboxy group, an ester group, and a halogen atom, [Chemical formula]

[0030] In formula (AIII), R 15 is a single bond, a substituted or unsubstituted C1-C3 alkyl group, and when substituted, the substituent contains one or more of a nitrile group (-CN), a nitro group, a sulfonic acid group, a sulfonyl group, an amide, a carboxy group, an ester group, and a halogen atom, p is a positive integer selected from 1 to 3, and n is a positive integer selected from 1000 to 30000.

[0031] In some embodiments, the lyophilic polymer includes an ether-based polymer. Here, the ether-based polymer is made into a sheet-like structure, and the sheet-like structure obtains an elastic modulus G'-energy consumption coefficient G" curve by a dynamic frequency scanning test at (T m2 +20)°C. The slope of the elastic modulus G'-energy consumption coefficient G" curve is K1, 1 < K1 < ∞, and T m2 °C represents the melting temperature of the ether-based polymer. Optionally, 1 < K1 ≤ 100, and more optionally, 1 < K1 ≤ 10.

[0032] In some embodiments, the ether-based polymer includes a structural unit represented by formula (BI) and / or a structural unit represented by formula (BII). [Chemical formula]

[0033] In formula (BI), R 21 and R 22 each independently contain a hydrogen atom, a substituted or unsubstituted C1-C3 alkyl group, or a substituted or unsubstituted C1-C3 alkoxy group, and R 23 contains a substituted or unsubstituted C1-C5 alkylene group.

Chemical formula

[0034] In formula (BII), R 24 to R 27 each independently contain a hydrogen atom, a substituted or unsubstituted C1-C3 alkyl group, a substituted or unsubstituted C1-C3 alkoxy group, or an ether group, and at least one of R 24 to R 27 contains a substituted or unsubstituted C1-C3 alkoxy group or an ether group.

[0035] In some embodiments, the substituent may contain one or more of a nitrile group (-CN), a nitro group, a sulfonic acid group, a sulfonyl group, an amide, a carboxy group, an ester group, and a halogen atom.

[0036] In some embodiments, the lyophilic polymer contains an ester-based polymer. Here, the ester-based polymer is made into a sheet-like structure. The sheet-like structure obtains an elastic modulus G'-energy consumption coefficient G" curve by a dynamic frequency scanning test at (T m3 +20)°C. The slope of the elastic modulus G'-energy consumption coefficient G" curve is K2, where 1 < K2 < ∞. T m3 °C represents the melting temperature of the ester-based polymer. Optionally, 1 < K2 ≤ 100, and more optionally, 1 < K2 ≤ 10.

[0037] In some embodiments, the ester-based polymer contains a structural unit represented by formula (CI) and / or a structural unit represented by formula (CII).

Chemical formula

[0038] In formula (CI), R 31 , R 32 and R 33 each independently contains a hydrogen atom or a substituted or unsubstituted C1 to C8 alkyl group, and R 34 comprises a substituted or unsubstituted C1-C8 alkyl group or a substituted or unsubstituted C1-C8 hydroxyalkyl group, [ka]

[0039] In formula (CII), R 35 contains a substituted or unsubstituted C2-C6 methylene group, and optionally R 35 each independently comprises a substituted or unsubstituted C2 to C4 methylene group.

[0040] In some embodiments, the substituents may include one or more of a nitrile group (-CN), a nitro group, a sulfonic acid group, a sulfonyl group, an amide, a carboxy group, an ester group, or a halogen atom.

[0041] In some embodiments, the lyophilic polymer comprises an aldehyde ketone polymer, wherein the aldehyde ketone polymer is fabricated into a sheet-like structure, and the sheet-like structure is formed into a polymer having a molecular weight of (T m4 The elastic modulus G'-energy dissipation coefficient G" curve was obtained by dynamic frequency scanning test at +20°C. The slope of the elastic modulus G'-energy dissipation coefficient G" curve was K3, 0.8≦K3<∞, and T m4 °C represents the melting temperature of the aldehyde ketone polymer, optionally 0.8≦K3≦100, more optionally 0.8≦K3≦10.

[0042] In some embodiments, the aldehyde ketone polymer comprises a structural unit shown in formula (DI) and / or a structural unit shown in formula (DII): [ka]

[0043] In formula (DI), R 41 contains a single bond or a substituted or unsubstituted C1-C6 methylene group, and R 42 contains a hydrogen atom or a substituted or unsubstituted C1-C6 alkyl group, [ka]

[0044] In formula (DII), R 43 ~R 46 each independently comprises a hydrogen atom, a hydroxy group, a substituted or unsubstituted C1-C3 alkyl group, a substituted or unsubstituted C1-C3 hydroxyalkyl group, or a substituted or unsubstituted C1-C3 alkoxy group, and r and s each independently represent an integer selected from 0 to 5, and at least one of r and s is selected from a positive integer.

[0045] In some embodiments, the substituents may include one or more of a nitrile group (-CN), a nitro group, a sulfonic acid group, a sulfonyl group, an amide, a carboxy group, an ester group, or a halogen atom.

[0046] In some embodiments, the molecular weight of the lyophilic polymer is 1.2×10 5 g / mol ~ 1 × 10 6 g / mol.

[0047] A second aspect of the present application further provides a battery comprising the battery cell according to any one of the embodiments of the first aspect of the present application.

[0048] A third aspect of the present application further provides an electrical device comprising a battery according to an embodiment of the second aspect of the present application. [Brief explanation of the drawings]

[0049] In order to more clearly explain the technical solutions in the embodiments of the present application, the following briefly describes the drawings necessary for the embodiments of the present application. Obviously, the drawings described below are only some embodiments of the present application, and those skilled in the art can further obtain other drawings based on the drawings without any creative efforts.

[0050] [Figure 1] 1 is a schematic diagram of one embodiment of a battery cell according to the present application.

[0051] [Figure 2] FIG. 2 is an exploded schematic view of an embodiment of the battery cell of FIG. 1.

[0052] [Figure 3] 1 is a schematic diagram of an embodiment of a battery module according to the present application.

[0053] [Figure 4] 1 is a schematic diagram of an embodiment of a battery pack according to the present application.

[0054] [Figure 5] FIG. 5 is an exploded schematic view of the embodiment of the battery pack shown in FIG. 4.

[0055] [Figure 6] 1 is a schematic diagram of one embodiment of an electrical device including a battery cell according to the present application as a power source.

[0056] The drawings are not necessarily drawn to scale.

[0057] The drawing symbols are explained as follows:

[0058] 1. Battery pack, 2. Upper case, 3. Lower case, 4. Battery module,

[0059] 5. Battery cell; 51. Casing; 52. Electrode assembly;

[0060] 53, cover plate,

[0061] 6. Electrical equipment. DETAILED DESCRIPTION OF THE INVENTION

[0062] Hereinafter, embodiments specifically disclosing the battery cell, battery, and electrical device according to the present application will be described in detail. However, unnecessary details may be omitted. For example, detailed descriptions of well-known matters and redundant descriptions of structures that are actually the same may be omitted. This is to avoid the following description becoming unnecessarily long and to facilitate understanding by those skilled in the art. Note that the drawings and the following description are provided to enable those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0063] The "ranges" disclosed herein are defined in the form of lower and upper limits. A given range is defined by selecting one lower limit and one upper limit, and the selected lower and upper limits define the boundaries of the particular range. Such defined ranges may be inclusive or exclusive of the end values, and are arbitrarily combinable; i.e., any lower limit can be combined with any upper limit to form a single range. For example, if ranges of 60 to 120 and 80 to 110 are listed for a particular parameter, it is understood that ranges of 60 to 110 and 80 to 120 are also contemplated. Furthermore, if 1 and 2 are listed as minimum range values ​​and 3, 4, and 5 are listed as maximum range values, the ranges 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4, and 2 to 5 are all contemplated. In this application, unless otherwise specified, a numerical range "a to b" is a shorthand notation for any combination of real numbers a to b, where a and b are both real numbers. For example, the numerical range "0-5" indicates that this specification has already listed all real numbers between "0-5," and "0-5" is merely a shorthand representation of combinations of these numbers. Also, expressing a parameter as an integer ≧2 is equivalent to disclosing that this parameter is, for example, the integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0064] Unless otherwise stated, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution. Unless otherwise stated, all technical features and optional technical features of the present application can be combined with each other to form a new technical solution.

[0065] Unless otherwise specified, all steps herein may be performed in order or randomly, preferably in order. For example, a method including steps (a) and (b) means that the method may include steps (a) and (b) performed in order, or steps (b) and (a) performed in order. For example, a method that further includes step (c) means that step (c) may be added to the method in any order, e.g., the method may include steps (a), (b), and (c), or may include steps (a), (c), and (b), or may include steps (c), (a), and (b), etc.

[0066] Unless otherwise specified, the terms "comprise" and "comprises" used herein may be open-ended or closed-ended. For example, "comprise" and "comprises" may indicate that other components not listed may be further included or included, or that only the listed components may be included or included.

[0067] Unless otherwise stated, in this application, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B." More specifically, any one of the following conditions satisfies "A or B": A is true (or exists) and B is false (or does not exist), A is false (or does not exist) and B is true (or exists), or both A and B are true (or exist).

[0068] As used herein, the terms "plurality" and "plurality" refer to two or more than two.

[0069] Unless otherwise explained, terms used in this application have the meanings commonly understood by those skilled in the art.

[0070] Unless otherwise specified, the numerical values ​​of each parameter referred to in this application can be measured by various measurement methods commonly used in the art, and can be tested, for example, according to the methods described in the examples of this application.

[0071] The term "alkyl group" includes both straight-chain and branched-chain alkyl groups. For example, the alkyl group may be a C1-C5 alkyl group, a C1-C4 alkyl group, a C1-C3 alkyl group, or a C1-C2 alkyl group. In some embodiments, the alkyl group includes a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, and the like. Furthermore, the alkyl group may be optionally substituted. When substituted, the substituent may include a fluorine atom.

[0072] The term "alkoxy group" refers to an alkyl group attached to an oxygen atom via a single bond. For example, the alkoxy group may be a C1-C5 alkoxy group, a C1-C3 alkoxy group, or a C1-C2 alkoxy group. In some embodiments, the alkoxy group may include a methoxy group, an ethoxy group, or a propoxy group. Furthermore, the alkoxy group may be optionally substituted.

[0073] The term "halogen atom" refers to fluorine atom, chlorine atom, bromine atom, and the like.

[0074] The term "hydrogen" refers to 1H (hydrogen, H), 2H (deuterium, D), or 3H (tritium, T). In each embodiment, "hydrogen" may be 1H (hydrogen, H).

[0075] The battery cell includes an electrode assembly including positive electrode pieces, negative electrode pieces, and a separator, and an electrolyte. The separator is installed between the positive electrode pieces and the negative electrode pieces and serves mainly to prevent short circuits between the positive electrode pieces and the negative electrode pieces, while at the same time allowing active ions to pass freely through it to form a circuit.

[0076] When the electrolyte is immersed in the electrode assembly, active ions can migrate from the positive electrode piece of the electrode assembly through the separator to the negative electrode piece. However, during the use process of the battery cell, the volume of the electrode assembly may change (e.g., expand) due to the insertion or desorption of active ions, and the electrolyte immersed in the electrode assembly may be continuously extruded. The extruded electrolyte cannot be fully absorbed back into the electrode assembly, which may cause metal deposition in the electrode assembly due to a lack of liquid, increasing the risk of dendrite formation. As the dendrite grows, it may break through the separator, causing a short circuit between the positive electrode piece and the negative electrode piece, which may reduce the usage reliability and cycle performance of the battery cell.

[0077] In view of the above problems, the present application provides a battery cell that can improve the reliability of the battery cell by adding a lyophilic polymer to the electrode assembly, which can form a cohesive electrolyte by packing the electrolyte between the molecular chains of the polymer after contacting and mixing with the free electrolyte, thereby ensuring the electrical performance of the battery cell. Next, the technical solution of the present application will be described in detail.

[0078] Battery cell

[0079] In a first aspect, the present application provides a battery cell including an electrode assembly including a first pole piece, a second pole piece, and a separator, and an electrolyte, wherein the first pole piece and the second pole piece have opposite polarities, the separator is disposed between the first pole piece and the second pole piece, and at least one of the first pole piece, the second pole piece, and the separator includes a lyophilic polymer.

[0080] The battery cell satisfies the following formula:

number

[0081] p1 represents the porosity of the first pole piece;

[0082] v1 is the total volume of the first pole piece in μm3 It is expressed as

[0083] p2 represents the porosity of the second pole piece;

[0084] v2 is the total volume of the second pole piece in μm 3 It is expressed as

[0085] p3 represents the porosity of the separator;

[0086] v3 is the total volume of the separator in μm 3 It is expressed as

[0087] y represents the mass of free electrolyte in the battery cell in g;

[0088] In the embodiments of the present application, the porosity p has a meaning known in the art and can be detected using an instrument and a method known in the art. For example, it can be obtained by a gas displacement method.

number

[0089]

number

number

[0090] In the embodiments of the present application, the total volume v has a meaning known in the art and can be detected using equipment and methods known in the art. For example, the total volume can be calculated by measuring the length, width, and height of a sample using a ruler and multiplying the three values.

[0091] In the present embodiment, after the electrolyte is injected into the battery cell, the electrolyte exists in several main forms: first, adsorbed on the pole pieces and / or separator; second, forming a coagulated electrolyte with the lyophilic polymer; and third, remaining liquid and free within the battery cell. y represents the mass of the electrolyte in the third state, i.e., the mass of the free electrolyte. The mass of the free electrolyte can be measured as follows: A new battery cell is removed and fully discharged to a 0% SOC state of charge. A hole with a diameter of 5-8 mm is drilled at a local position on the battery cell. The battery cell is placed directly above a container with the hole facing downwards, allowing the free electrolyte within the battery cell to drip into the container below. The battery cell is left in this state for 3-5 hours until all the free electrolyte inside has dripped into the container. The volume of the electrolyte within the container is then measured to obtain y. In the embodiments of the present application, a new battery cell may be a battery cell immediately after being shipped from a factory (a battery cell that has not undergone any charge / discharge cycles since its formation), or a battery cell that has been installed in an electrical device and has undergone fewer than 10 cycles.

[0092]

number

[0093] When the present embodiment satisfies the above formula, the lyophilic polymer has a relatively good affinity for the electrolyte, allowing the electrolyte to rapidly diffuse between the molecular chains of the lyophilic polymer and be encapsulated by the molecular chains, resulting in an elastic, porous, sustained-release electrolyte through swelling and adsorption. The sustained-release electrolyte can absorb and reduce the presence of free electrolyte in the battery cell. The free electrolyte is then trapped, reducing the risk of extrusion, thereby reducing the risk of short circuits between the positive and negative electrode pieces caused by dendrite formation and improving the reliability and cycle performance of the battery cell. The absorbed free electrolyte then forms a new cohesive electrolyte with the elastic, porous, sustained-release electrolyte, ensuring a relatively high electrolyte conductivity and thereby improving the electrical performance of the battery cell.

[0094] Therefore, the embodiment of the present application

number

number

number

[0095] for example,

number

[0096] are 0%, 0.001%, 0.002%, 0.003%, 0.004%, 0.005%, 0.006%, 0.007%, 0.008%, 0.009%, 0.01%, 0.012%, 0.014%, 0.016%, 0.018%, 0.02%, 0.022%, 0.024%, 0.0 26%, 0.028%, 0.03%, 0.032%, 0.034%, 0.036%, 0.038%, 0.04%, 0.042%, 0.044%, 0.046%, 0.048%, 0.05%, 0.052%, 0.054%, 0.056%, 0.058%, 0.06%, 0.062% ,0.064%,0.066%,0.068%,0.07%,0.072%,0.074%,0.076%,0.078%,0.08%,0.082%,0.084%,0.086%,0.088%,0.09%,0.092%,0.094%,0.096%,0.098%,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%, 1.10%, 1.20%, 1.30%, 1.40%, 1.50%, 1.60%, 1.70%, 1.80%, 1.90%, 2.00%, 2.10%, 2.20%, 2.30%, 2.40%, 2.50%, 2.60%, 2.70%, 2.80%, 2.90%, 3.00%, 3.10%, 3.20%, 3.30% ,3.40%,3.50%,3.60%,3.70%,3.80%,3.90%,4.00%,4.10%,4.20%,4.30%,4.40%,4.50%,4.60%,4.70%,4.80%,4.90%,5.00%,5.10%,5.20%,5.30%,5.40 %, 5.50%, 5.60%, 5.70%, 5.80%, 5.90%, 6.00%, 6.10%, 6.20%, 6.30%, 6.40%, 6.50%, 6.60%, 6.70%, 6.80%, 6.90%, 7.00%, 7.10%, 7.20%, 7.30%, 7.40%, 7.5 0%, 7.60%, 7.70%, 7.80%, 7.90%, 8.00%, 8.10%, 8.20%, 8.30%, 8.40%, 8.50%, 8.60%, 8.70%, 8.80%, 8.90%, 9.00%, 9.10%, 9.20%, 9.30%, 9.40%, 9.50%, 9.60%, 9.70%, 9.80%, 9.90%, 10%, 10.10%, 10.20%, 10.30%, 10.40%, 10.50%, 10.60%, 10.70%, 10.80%, 10.90%, 11.00%, 11.10%, 11.20%, 11.30%, 11.40%, 11.5 0%, 11.60%, 11.70%, 11.80%, 11.90%, 12.00%, 12.10%, 12.20%, 12.30%, 12.40%, 12.50%, 12.60%, 12.70%, 12.80%, 12.90%, 13.00%, 13.10%, 13.20%, 13.30% , 13.40%, 13.50%, 13.60%, 13.70%, 13.80%, 13.90%, 14.00%, 14.10%, 14.20%, 14.30%, 14.40%, 14.50%, 14.60%, 14.70%, 14.80%, 14.90%, 15.00%, 15.50%, 16.00%, 16.50%, 17.00%, 17.50%, 18.00%, 18.50%, 19.00%, 19.50%, 20.00%, 20.50%, 21.00%, 21.50%, 22.00%, 22.50%, 23.00%, or a range consisting of any two of the above values.

[0097] In some embodiments, the battery cells also satisfy the following formula:

number

[0098] m1 represents the mass of the electrode assembly before drying in the unit of g, and the mass before drying represents the mass of the electrode assembly obtained by disassembling the battery cell, removing the electrode assembly, leaving the electrode assembly to stand for 3 to 5 hours, and then draining the free electrolyte in the electrode assembly.

[0099] m2 represents the mass of the electrode assembly after drying in g, and the mass after drying refers to the mass of the electrode assembly obtained after drying and removing the electrolyte adsorbed on the electrode assembly. For example, the electrode assembly is placed in a drying box and dried at 60°C to 95°C for 24 to 48 hours, then immersed in dimethyl carbonate (DMC) solvent, and then placed in a drying box again and dried at 60°C to 95°C for 24 to 48 hours. The resulting electrode assembly is called the dried electrode assembly.

[0100] m2-m1 represents the mass of the electrolyte adsorbed on the electrode assembly, and y+m2-m1 represents the sum of the mass of the free electrolyte and the mass of the electrolyte adsorbed on the electrode assembly, which can be considered as the total amount of electrolyte in the battery cell.

[0101]

number

[0102] The embodiments of the present application fall within the range of the above formula.

number

number

number

number

[0103] In some embodiments, the amount of free electrolyte per unit capacity of the battery cell is b, expressed in mg / Ah, and is 0≦b≦1400. When the amount of free electrolyte per unit capacity of the battery cell, b, satisfies the above range, the usage reliability and cycle performance of the battery cell can be further improved.

[0104] Optionally, 0.1≦b≦1000, and further optionally, 0.3≦b≦800. Illustratively, the amount of free electrolyte per unit capacity of the battery cell is 0 mg / Ah, 0.001 mg / Ah, 0.002 mg / Ah, 0.003 mg / Ah, 0.004 mg / Ah, 0.005 mg / Ah, 0.006 mg / Ah, 0.007 mg / Ah, 0.008 mg / Ah, 0.009 mg / Ah, 0.01 mg / Ah, 0.02 mg / Ah, 0.0 3mg / Ah, 0.04mg / Ah, 0.05mg / Ah, 0.06mg / Ah, 0.07mg / Ah, 0.08mg / Ah, 0.09mg / Ah, 0.1mg / Ah, 0 .2mg / Ah, 0.3mg / Ah, 0.5mg / Ah, 1.0mg / Ah, 5.0mg / Ah, 10.0mg / Ah, 20.0mg / Ah, 50.0mg / Ah, 80. 0mg / Ah, 100mg / Ah, 120mg / Ah, 150mg / Ah, 180mg / Ah, 200mg / Ah, 220mg / Ah, 250mg / Ah, 300mg / A h, 350mg / Ah, 400mg / Ah, 450mg / Ah, 500mg / Ah, 550mg / Ah, 600mg / Ah, 650mg / Ah, 700mg / Ah, 750 mg / Ah, 800 mg / Ah, 850 mg / Ah, 900 mg / Ah, 950 mg / Ah, 1000 mg / Ah, 1050 mg / Ah, 1100 mg / Ah, 1150 mg / Ah, 1200 mg / Ah, 1250 mg / h, 1300 mg / Ah, 1350 mg / Ah, 1400 mg / Ah, or a range consisting of any two of the above values.

[0105] In the present embodiment, b is equal to y / x, where x is the nominal capacity of the battery cell in Ah, and y is the mass of the free electrolyte mentioned above.

[0106] In the embodiment of the present application, x can be detected using a method and device known in the art, for example, it is the product of the total amount of current that can be output when a battery cell is discharged to an end voltage at a constant current and voltage of 0.33 C in a fully charged state and the discharge time.

[0107] In some embodiments, the battery cell is charged to 100% SOC after a linear frequency sweep vibration test, a hole is drilled in the battery cell, and the hole is positioned at the lowest point in the vertical direction; and the mass of the electrolyte flowing out of the battery cell is recorded as M1, where 0≦M1≦6 g, and optionally, M1 is 0 g;

[0108] where:

[0109] The vibration direction of the linear frequency sweep vibration test is a single vibration in an up and down direction,

[0110] The vibration rate of the linear frequency sweep vibration test is 10 Hz to 55 Hz,

[0111] The maximum acceleration of the linear frequency sweep vibration test is 30 m / s2;

[0112] The number of frequency sweep cycles in the linear frequency sweep vibration test is 10;

[0113] The vibration time of the linear frequency sweep vibration test is 3 hours.

[0114] In related art, battery cells may be vibrated by external forces during use, causing the electrolyte located in the electrode assembly to detach from the electrode assembly and form free electrolyte. The free electrolyte may then leak, corroding the battery cell and potentially leading to risks such as failure of the battery cell. In contrast, embodiments of the present application allow the battery cell to be left stationary and vibrated, effectively collecting and discharging the electrolyte within the battery cell, thereby more accurately determining whether electrolyte is flowing between the battery cell casing and the electrode assembly and determining the amount of free electrolyte. When the battery cell of the present application satisfies the above conditions, the amount of free electrolyte within the battery cell is extremely small, or even essentially zero, thereby significantly improving the usage reliability and cycle performance of the battery cell.

[0115] Illustratively, M1 may be 0, 0.05 g, 0.10 g, 0.15 g, 0.20 g, 0.25 g, 0.3 g, 0.35 g, 0.4 g, 0.45 g, 0.5 g, 0.55 g, 0.60 g, 0.65 g, 0.70 g, 0.75 g, 0.80 g, 0.85 g, 0.90 g, 0.95 g, 1.00 g, 1.10 g, 1.20 g, 1.30 g, 1.40 g, 1.50 g, 1.60 g, 1.70 g, 1.80 g, 1.90 g, 2.00 g, 2.10 g, 2.20 g, 2.30 g, 2.40 g, 2.50 g, 2.60 g, 2.70 g, 2.80 g, 2.90 g, 3.00 g, 3.10 g, 3.20 g, 3.30 g, 3.40 g, 3.50 g, 3.60 g, 3.70 g, 3.80 g, 3.90 g, 4.00 g, 4.10 g, 4.20 g, 4.30 g, 4.40 g, 4.50 g, 4.60 g, 4.70 g, 4.80 g, 4.90 g, 5.00 g, 5.10 g, 5.20 g, 5.30 g, 5.40 g, 5.50 g, 5.60 g, 5.70 g, 5.80 g, 5.90 g, 6.00 g, 6.10 g, 6.20 g, 2.30 g, 2.40 g, 2.50 g, 2.60 g, 2.70 g, 2.80 g, 2.90 g, 3.00 g, 3.10 g, 3.20 g, 3.30 g, 3.40 g, 3.50 g, 3.60 g, 3.70 g, 3.80 g, 3.90 g, 4.00 g, 4.10 g, 4.20 g, 4.30 g, 4.40 g, 4.50 g, 4.60 g, 4.70 g, 4.80 g, 4.90 g, 5.00 g, 6.00 g, or a range consisting of any two of the above values. An M1 of 0 g indicates that the amount of free electrolyte is 0, i.e., the battery cell is essentially free of free electrolyte after the linear frequency sweep vibration test.

[0116] In some embodiments, after the linear frequency sweep vibration test, the battery cell is subjected to the linear frequency sweep vibration test, the casing is removed, the electrode assembly is taken out, and after the pressing test, the volume of the electrolyte flowing out of the electrode assembly is recorded as M2 (the pressing device is suspended, and a weighing balance and an electrolyte collection container are placed at the bottom), and 0≦M2≦0.6 g, optionally M2 is 0 g,

[0117] The pressing direction of the pressing test is perpendicular to the thickness direction of the electrode assembly,

[0118] The pressure level in the compression test was 0.35 MPa.

[0119] In the related art, battery cells may be compressed by external forces during use, causing the electrolyte located in the electrode assembly to detach from the electrode assembly and form free electrolyte. Meanwhile, the free electrolyte in the battery cell may leak, corroding the battery cell and potentially leading to risks such as battery cell failure. According to an embodiment of the present application, a compression test is performed on the battery cell to effectively compress and cause the electrolyte in the battery cell to flow out, thereby more accurately determining whether electrolyte is flowing between the battery cell casing and the electrode assembly and determining the amount of free electrolyte. When the battery cell of the embodiment of the present application satisfies the above conditions, the amount of free electrolyte in the battery cell is extremely small, or even essentially zero, thereby significantly improving the usage reliability and cycle performance of the battery cell.

[0120] Illustratively, M2 may be 0, 0.05 mg, 0.10 mg, 0.15 mg, 0.20 mg, 0.25 mg, 0.3 mg, 0.35 mg, 0.4 mg, 0.45 mg, 0.5 mg, 0.55 mg, 0.60 mg, 0.65 mg, 0.70 mg, 0.75 mg, 0.80 mg, 0.85 mg, 0.90 mg, 0.95 mg, 1.00 mg, 1.10 mg, 1.20 mg, 1.30 mg, 1.40 mg, 1.50 mg, 1.60 mg, 1.70 mg, 1.80 mg, 1.90 mg, 2.00 mg, 2.10 mg, 2.20 mg, 2.30 mg, 2.40 mg , 2.50mg, 2.60mg, 2.70mg, 2.80mg, 2.90mg, 3.00mg, 3.10mg, 3.20mg, 3.30mg, 3.40mg, 3.50mg, 3.60mg, 3.70mg, 3.80mg, 3.90mg, 4.00mg, 4.10mg, 4.2 0mg, 4.30mg, 4.40mg, 4.50mg, 4.60mg, 4.70mg, 4.80mg, 4.90mg, 5.00mg, 10.00mg, 20.00mg, 30.00mg, 40.00mg, 50.00mg, 60.00mg, 70.00mg, 80.00mg , 90.00mg, 100.00mg, 110.00mg, 120.00mg, 130.00mg, 140.00mg, 150.00mg, 160.00mg, 170.00mg, 180.00mg, 190.00mg, 200.00mg, 210.00mg, 220.00 mg, 230.00mg, 240.00mg, 250.00mg, 260.00mg, 270.00mg, 280.00mg, 290.00mg, 300.00mg, 310.00mg, 320.00mg, 330.00mg, 340.00mg, 350.00mg, 360 0.00mg, 370.00mg, 380.00mg, 390.00mg, 400.00mg, 410.00mg, 420.00mg, 430.00mg, 440.00mg, 450.00mg, 460.00mg, 470.00mg, 480.00mg, 490.00mg, 500.00mg, 510.00mg, 520.00mg, 530.00mg, 540.00mg, 550.00mg, 560.00mg, 570.00mg, 580.00mg, 590.00mg, 600.00mg or a range consisting of any two of the above values.M2 being 0g indicates that the amount of free electrolyte is 0, that is, the battery cell has essentially no free electrolyte inside after the compression test.

[0121] In the present application, the pressing test may be performed after the linear frequency sweep vibration test, that is, the battery cell is first subjected to the linear frequency sweep vibration test and then subjected to the pressing test, and the M2 value is measured, and 0≦M2≦0.5g, and optionally, M2 is 0g;

[0122] In some embodiments, a voltage of 200V is supplied to the battery cell and the circuit is formed for 4 hours, and the absolute value of the temperature change of the battery cell is ≦4° C.

[0123] For example, if the negative terminal of a battery cell and the outer casing are connected to a 200V voltage to form a current circuit, the temperature fluctuation of the battery cell will be less than 4°C within 4 hours, and there will be no failure behavior such as fire or explosion. In particular, when the free electrolyte y=0, the temperature fluctuation range is relatively small, greatly improving the reliability of the battery cell.

[0124] In some embodiments, the pole pieces include a lyophilic polymer. Specifically, the first pole piece includes a current collector and an active material layer disposed on at least one surface of the current collector, the active material layer including a lyophilic polymer and active material particles. The lyophilic polymer may be disposed only on the first pole piece, or only on the second pole piece, or the lyophilic polymer may be disposed on both the first and second pole pieces. The first pole piece may be a positive pole piece, and correspondingly, the second pole piece may be a negative pole piece. Alternatively, the first pole piece may be a negative pole piece, and correspondingly, the second pole piece may be a positive pole piece.

[0125] In some examples, the lyophilic polymer is distributed on the surface of the active material particles. It can be understood that the active material particles and adhesive are solidified into a film layer on the surface of the current collector, and the lyophilic polymer is disposed on the surface of the film layer away from the current collector. This arrangement allows the electrolyte to rapidly diffuse between the molecular chains of the lyophilic polymer and be encapsulated by the molecular chains, forming a gel-like substance on the surface of the active material particles. This adheres to the surface of the active material particles and provides protection for the active material particles. This tightly binds the active material particles to the electrolyte, improves solid-liquid interface performance, reduces side reactions between the active material particles and the electrolyte, and improves the reliability and electrical characteristics (e.g., cycle performance and storage performance) of the battery cell.

[0126] Specifically, the manufacturing process of the pole pieces is as follows:

[0127] adding active material particles to a solvent to form an active slurry;

[0128] applying the active slurry to the surface of a current collector and drying it to solidify it into a film layer;

[0129] and applying a lyophilic polymer to the surface of the film layer to form a pole piece.

[0130] In some other examples, the active material particles are plural and have pores between adjacent active material particles, and the lyophilic polymer is distributed in the pores between the active material particles. This arrangement can improve the liquid storage capacity of the active material layer, i.e., the capacity to confine the electrolyte, thereby improving the reliability and electrical properties of the battery cell.

[0131] Specifically, the manufacturing process for one embodiment of the pole piece is:

[0132] Dispersing a lyophilic polymer in a solvent to form a mixed system;

[0133] adding active material particles to the mixed system to prepare a slurry;

[0134] The slurry is applied to the surface of a current collector, and then dried to solidify into a pole piece.

[0135] Specifically, the manufacturing process for another embodiment of the pole piece comprises:

[0136] Dispersing a lyophilic polymer and active material particles in a solvent to prepare a slurry;

[0137] The slurry is applied to the surface of a current collector, and then dried to solidify into a pole piece.

[0138] In some further examples, the lyophilic polymer is distributed on the surfaces of the active material particles, and the lyophilic polymer is distributed in the pores between the active material particles.

[0139] Specifically, the manufacturing process for one embodiment of the pole piece is:

[0140] Dispersing a lyophilic polymer and active material particles in a solvent to prepare a slurry;

[0141] applying the slurry to a surface of a current collector and drying it to solidify it into a film layer;

[0142] and applying a lyophilic polymer to the surface of the film layer to form a pole piece.

[0143] In some other embodiments, the separator includes a lyophilic polymer, and specifically, the separator may include a substrate, and optionally, the separator may further include a coating disposed on at least one surface of the substrate.

[0144] In some examples, the substrate may generally be a porous structure having pores, and the lyophilic polymer may be distributed in the pores of the substrate.

[0145] As some other examples, the lyophilic polymer may be distributed within the coating.

[0146] As some further examples, the lyophilic polymer may be disposed on a surface of the coating that faces away from the substrate.

[0147] The specific distribution position of the lyophilic polymer may be any one of the above three types, any two of the above three types, or a combination of the above three types of positions.

[0148]

[0149] In some further embodiments, the lyophilic polymer may be disposed on the pole pieces and separator, and the specific location of the polymer is as described above, and therefore the description thereof will be omitted here.

[0150]

[0151] In some embodiments, the lyophilic polymer may include one or more of a fluorine-based polymer, an ether-based polymer, an ester-based polymer, and a ketone aldehyde-based polymer.

[0152] [Fluorine-based polymer]

[0153] In some embodiments, the lyophilic polymer comprises a fluoropolymer, and the crystallinity of the fluoropolymer as measured by differential scanning calorimetry is greater than or equal to X C1 %, 0 <X C1 ≦30, and the melting temperature of the fluoropolymer is T m1 , its units are °C, 0 <T m1 ≦140.

[0154] Crystallization refers to the process by which atoms, ions, or molecules in a material are arranged in a certain spatial order to form a well-ordered structure. The conformation of a polymer in crystallization is determined by two factors: intramolecular and intermolecular forces, and intermolecular forces affect the stacking density between molecular chains. Crystallinity X C1The crystallinity of the material is characterized by differential scanning calorimetry (DSC). Specifically, the test involves taking a 0.5g-0.8g sample, placing it in a crucible, and heating the sample in a nitrogen atmosphere at a heating rate of 10°C / min to measure the intrinsic T of the material. g1 From an initial temperature 20°C lower than the m1 The actual glass transition temperature T of the material according to the heat absorption / dissipation peak value or transition point of the material in the process, up to 20°C higher than the cutoff temperature. g1 and melting temperature T m1 etc. will be determined.

[0155] In this way, fluoropolymers have a relatively low crystallinity and melting temperature, tend to have loose molecular chain arrangements, and the inter-chain forces are relatively small, allowing adjacent molecular chains to open easily, allowing the movement of chain segments through internal intermolecular rotation, forming a relatively flexible molecular chain structure, and the fluoropolymer and the electrolyte in the battery cell can form a gel-like substance, improving the usage reliability and cycle performance of the battery cell.

[0156] Illustratively, the crystallinity X of the fluoropolymer measured by differential scanning calorimetry C1 The % may be 5%, 10%, 15%, 20%, 25%, 30% or a range consisting of any two of the above values.

[0157] Illustratively, the melting temperature of the fluoropolymer may be 10°C, 20°C, 50°C, 70°C, 90°C, 100°C, 120°C, 140°C, or a range consisting of any two of the foregoing values.

[0158] In some embodiments, the glass transition temperature of the fluoropolymer is T g1 , the unit is °C, -150≦T g1 ≦60.

[0159] The glass transition temperature is the temperature at which a polymer chain segment transitions from frozen to mobile. The glass transition temperature has a certain effect on the flexibility of the polymer molecular chain. The lower the glass transition temperature, the more flexible the polymer molecular chain at room temperature. The higher the glass transition temperature, the less flexible the molecular chain at room temperature. The glass transition temperature can be measured by differential scanning calorimetry (DSC). The lower the glass transition temperature of a polymer, the more flexible the chain segments of the molecular chain are, and the more easily adjacent molecular chains open. For example, the glass transition temperature of a fluoropolymer may be -150°C, -120°C, -100°C, -80°C, -60°C, -30°C, 0°C, 30°C, 60°C, or a range consisting of any two of the above values.

[0160] In some embodiments, the fluoropolymer comprises at least one of structural units represented by formula (AI) to structural units represented by formula (AIII): [ka]

[0161] In formula (AI) and formula (AII), R 11 , R 12 , R 13 and R 14 each independently contains a hydrogen atom, a fluorine atom, a chlorine atom, a substituted or unsubstituted C1-C3 alkyl group, or a substituted or unsubstituted C1-C3 alkoxy group, and R 11 , R 12 , R 13 and R 14 At least one of the groups contains a fluorine atom, and when substituted, the substituents may include one or more of a nitrile group (—CN), a nitro group, a sulfonic acid group, a sulfonyl group, an amide, a carboxy group, an ester group, and a halogen atom.

[0162] In formula (AIII), R 15includes a single bond or a substituted or unsubstituted C1-C3 alkyl group, and if substituted, the substituent may include one or more of a nitrile group (-CN), a nitro group, a sulfonic acid group, a sulfonyl group, an amide group, a carboxy group, an ester group, and a halogen atom. p is a positive integer selected from 1 to 3. n is a positive integer selected from 1,000 to 30,000.

[0163] In some embodiments, R 11 , R 12 , R 13 and R 14 each independently comprises a hydrogen atom, a fluorine atom, a chlorine atom, a substituted or unsubstituted C1-C2 alkyl group, or a substituted or unsubstituted C1-C2 alkoxy group, and optionally further comprises R 11 , R 12 , R 13 and R 14 each independently includes a hydrogen atom, a fluorine atom, a chlorine atom, a methyl group, a fluoromethyl group, a methoxy group, or a perfluoromethoxy group.

[0164] In some embodiments, the fluoropolymer comprises at least one of the structural units shown in formula (AI-1) to formula (AI-11): [ka]

[0165] In some embodiments, the fluoropolymer comprises at least one of the structural units represented by formula (AII-1) to formula (AII-5): [ka]

[0166] In some embodiments, the fluoropolymer comprises at least one of the structural units represented by formula (AIII-1) to formula (AIII-3): [ka]

[0167] Illustratively, the fluoropolymer includes one or more of polyperfluoroethylene PTFE, polyvinylidene fluoride PVDF, perfluoroethylene propylene copolymer FEP, perfluoroalkoxy polymer PFA, perfluoropolyether PFPE, polyvinylidene fluoride-hexafluoropropylene copolymer PVDF-HFP, polyvinylidene fluoride-trifluoroethylene copolymer PVDF-TrFE, and perfluoro(1-butenyl vinyl ether) polymer (abbreviated as CYTOP).

[0168] Optionally, the fluoropolymer comprises one or more of polyperfluoroethylene PTFE, polyvinylidene fluoride PVDF, perfluoroethylene propylene copolymer FEP, polyvinylidene fluoride-hexafluoropropylene copolymer PVDF-HFP, polyvinylidene fluoride-trifluoroethylene copolymer PVDF-TrFE.

[0169] The fluoropolymer may be one or more of monomers derived from fluorocyclohexane, vinyl fluoride, 1,2-difluoroethylene, vinylidene fluoride, trifluoroethylene, chlorotrifluoroethylene, tetrafluoroethylene, hexafluoropropylene, 3,3,3-trifluoropropylene, trifluoropropylene, tetrafluoropropylene, pentafluoropropylene, etc. Alternatively, the fluoropolymer may be at least two of monomers derived from fluorocyclohexane, vinyl fluoride, 1,2-difluoroethylene, vinylidene fluoride, trifluoroethylene, chlorotrifluoroethylene, tetrafluoroethylene, hexafluoropropylene, 3,3,3-trifluoropropylene, trifluoropropylene, tetrafluoropropylene, and pentafluoropropylene.

[0170] The monomers used in the above fluoropolymers are all short-chain monomers, which can be polymerized to form a straight-chain linear structure or a short-branched structure. This type of structure has a relatively low degree of entanglement, which can improve the flexibility of the molecular chains, allowing them to fully extend in the electrolyte, thereby further improving the interfacial performance of the active material.

[0171] In some embodiments, n is a positive integer selected from 5,000 to 20,000, and / or the molecular weight of the lyophilic polymer is 2×10 5 g / mol ~ 1.5 × 10 6 g / mol. When the molecular weight of the polymer is within the above range, it can ensure that the polymer exhibits a certain solubility in the electrolyte and is not easily dissolved or dispersed by the electrolyte, which helps to control the distribution and dispersion of the polymer on the surface of the active material, and further improves the flexibility between the molecular chains of the polymer, and the interaction between the molecular chains is relatively weak, which helps the solvent molecules in the electrolyte open the molecular chains to enter between them and be enveloped by them, thereby helping the active ions to enter the active material through the solvent and realize the smooth and fast movement of the active ions.

[0172] When the molecular weight of the lyophilic polymer is within the above range, it is possible to ensure that the polymer exhibits a certain solubility in the electrolyte and is not easily dissolved or dispersed by the electrolyte, which helps to control the distribution and dispersion of the polymer on the surface of the active material, and further improves the flexibility between the molecular chains of the polymer, and the interaction between the molecular chains is relatively weak, which helps the solvent molecules in the electrolyte open the molecular chains, enter between the molecular chains, and be enveloped by the molecular chains, thereby helping the active ions to enter the active material through the solvent, realizing smooth and rapid migration of the active ions. For example, the molecular weight of the polymer is 2×10 5 g / mol, 5 × 10 5 g / mol, 8 × 10 5 g / mol, 1×10 6 g / mol, 1.5 × 10 6It may be g / mol or a range consisting of any two of the above values.

[0173] [Ether polymer]

[0174] In some embodiments, the lyophilic polymer comprises an ether-based polymer, and the ether-based polymer is formed into a sheet-like structure, and the sheet-like structure has a structure such that (T m2 +20) ° C., a dynamic frequency scanning test was performed to obtain the elastic modulus G'-energy dissipation coefficient G" curve, and the slope of the elastic modulus G'-energy dissipation coefficient G" curve was K1,1 <K1<∞であり、T m2 °C represents the melting temperature of the ether-based polymer.

[0175] Specifically, the manufacturing process of the sheet-like structure is as follows: The ether-based polymer is vacuum-dried at 80°C for 12 hours. The dried ether-based polymer is hot-pressed in a flat vulcanizer to form a thin sheet, and the hot-press temperature is set to (T m2 The temperature is set to +20°C, the rolling thickness is 1 to 2 mm, the rolling time is 2 minutes, and the pressure is 8 MPa. After rolling for 2 minutes, the sample is removed and placed in another vulcanizing device of the same model for cold rolling at a cold rolling pressure of 10 MPa. A circular die with a diameter of 25 mm can be used to obtain a polymer disc (sheet-like structure) of a fixed size. For example, the sheet-like structure may be a disc with a thickness of 1 to 2 mm and a diameter of 25 mm, and the sample may be prepared according to the sample specifications required by the testing equipment.

[0176] Based on the conclusions of classical linear viscoelasticity, for polymers, especially linear polymers, the elastic modulus G'-energy dissipation coefficient G" curve conforms to a frequency dependence in the terminal region (the range approaching the maximum angular velocity) and the longest chain of the polymer has an effect on the viscoelastic behavior.

[0177] The specific steps of the dynamic frequency scanning test are as follows. Use a TA-AR2000EX rotational rheometer (TA instruments, USA) to conduct the dynamic frequency scanning test, with the diameter of the parallel plates being 25 mm and the thickness being 0.9 mm. To ensure that the test is carried out in the linear viscoelastic region, the strain during the dynamic frequency scanning test is 2%, the test temperature is T m2 +20 °C, and the frequency scanning range of the test is 500 rad / s ≤ ω 2 ≤ 0.05 rad / s, and acquire data at the lowest possible frequencies.

[0178] The dynamic frequency scanning test can characterize the degree of entanglement of molecular chains in the solid-phase melting (molten state). Compared with the linear structure or short branched-chain structure, the degree of entanglement of the long branched-chain structure, network structure, and low cross-linked structure is higher, showing a deviation from the linear terminal behavior, and the ether-based polymer shows solid-phase behavior. When the ether-based polymer of the present application meets the above range, the entanglement state of the molecular chains can be further reduced, which is beneficial to the diffusion of solvent molecules in the electrolyte between the molecular chains, and the ether-based polymer still maintains a certain degree of entanglement state of the molecular chains, forms an electrolyte and a gel-like substance, and can improve the cycle performance and storage performance of the battery cell.

[0179] In some embodiments, 1 < K1 ≤ 100, and optionally, 1 < K1 ≤ 10. Exemplarily, K1 may be 0.8, 0.9, 1, 2, 5, 10, 15, 20, 30, 50, 100, 200, 500, 1000, 5000, 10000, or a range consisting of any two of the above values.

[0180] In some embodiments, the glass transition temperature of the ether-based polymer is T g2 , with the unit being °C, -100 ≤ T g2 ≤ 50, and optionally, -80 ≤ T g2 ≤ 30. Exemplarily, the glass transition temperature of the ether-based polymer may be -100 °C, -80 °C, -60 °C, -30 °C, 0 °C, 30 °C, 50 °C, or a range consisting of any two of the above values.

[0181] In some embodiments, the ether-based polymer comprises a structural unit shown in formula (BI): [ka]

[0182] In formula (BI), R 21 and R 22 each independently comprises a hydrogen atom, a substituted or unsubstituted C1-C3 alkyl group, or a substituted or unsubstituted C1-C3 alkoxy group, and R 23 contains a substituted or unsubstituted C1-C5 methylene group, and optionally R 21 and R 22 each independently contain a hydrogen atom, a substituted or unsubstituted C1-C2 alkyl group, and / or R 23 includes a single bond, a substituted or unsubstituted C1 to C4 methylene group.

[0183] In some embodiments, the substituents may include one or more of a nitrile group (-CN), a nitro group, a sulfonic acid group, a sulfonyl group, an amide, a carboxy group, an ester group, and a halogen atom.

[0184] Illustratively, the ether-based polymer includes at least one of structural units represented by formulas (BI-1) to (BI-8), [ka]

[0185] In some embodiments, the ether-based polymer comprises a structural unit shown in formula (BII): [ka]

[0186] In formula (BII), R 24 ~R 27each independently contains a hydrogen atom, a substituted or unsubstituted C1-C3 alkyl group, a substituted or unsubstituted C1-C3 alkoxy group, or an ether group, and R 24 ~R 27 At least one of them contains a substituted or unsubstituted C1 to C3 alkoxy group or ether group.

[0187] Selectively, R 24 ~R 27 each independently contains a hydrogen atom, a substituted or unsubstituted C1-C2 alkyl group, a substituted or unsubstituted C1-C2 alkoxy group, or an ether group, and R 24 ~R 27 At least one of them contains a substituted or unsubstituted C1 to C2 alkoxy group or ether group.

[0188] In some embodiments, the ether-based polymer comprises at least one of structural units represented by formula (BII-1) to structural units represented by formula (BII-7), [ka]

[0189] The monomers used in the ether polymers are polycyclic structures, such as structures with six or fewer ring members, or short-chain monomers, which are useful for forming a high content of -O- structures upon polymerization. Such structures have a relatively low degree of entanglement, which is useful for improving the flexibility of the molecular chains, allowing the molecular chains to fully extend in the electrolyte and easily form a gel material with the electrolyte, thereby improving the cycle performance and storage performance of the battery cell.

[0190] The above polymers are merely examples of structural groups in the main molecular chain, and in the embodiments of the present application, the polymer may be obtained by copolymerizing the above structural groups with other types of structural groups (e.g., olefin-based structural units, acrylonitrile-based structural units, etc.).

[0191] When the above groups are substituted, the substituents may include one or more of a nitrile group (-CN), a nitro group, a sulfonic acid group, a sulfonyl group, an amide group, a carboxy group, an ester group, and a halogen atom. Making the above substituents high-pressure resistant is advantageous for stabilizing the polymer structure. The halogen atoms may include fluorine atoms, chlorine atoms, bromine atoms, etc.

[0192] In some embodiments, n is a positive integer selected from 1,500 to 25,000.

[0193] Optionally, n is a positive integer selected from 3,000 to 18,000.

[0194] In some embodiments, the molecular weight of the polymer is 1.2×10 5 g / mol ~ 1.0 × 10 6 g / mol.

[0195] Illustratively, the molecular weight of the polymer is 1.2×10 5 g / mol, 2 × 10 5 g / mol, 5 × 10 5 g / mol, 8 × 10 5 g / mol, 1×10 6 It may be g / mol or a range consisting of any two of the above values.

[0196] [Ester polymer]

[0197] In some embodiments, the lyophilic polymer comprises an ester-based polymer, wherein the ester-based polymer is fabricated into a sheet-like structure, and the sheet-like structure comprises a polymer having a molecular weight of 1000 or more, and ... m3 +20) ° C., a dynamic frequency scanning test was performed to obtain the elastic modulus G'-energy dissipation coefficient G" curve, and the slope of the elastic modulus G'-energy dissipation coefficient G" curve was K2,1 <K2<∞であり、T m3 ° C. represents the melting temperature of the ester-based polymer.

[0198] When the ester polymer of the present application satisfies the above range, the entanglement state of the molecular chain can be further reduced, which is advantageous for the diffusion of solvent molecules in the electrolyte between the molecular chains, and the ether polymer still maintains a certain entanglement state of the molecular chain, forms an electrolyte and a gel substance, and can improve the cycle performance and storage performance of the battery cell.

[0199] In some embodiments, 1 < K2 ≤ 100, and optionally, 1 < K2 ≤ 10.

[0200] Exemplarily, K2 may be 1.01, 1.1, 1.2, 1.5, 2, 5, 10, 15, 20, 30, 50, 100, 200, 500, 1000, 5000, 10000, or a range consisting of any two of the above values.

[0201] In some embodiments, the glass transition temperature of the ester polymer is T g3 , with the unit of °C, -100 ≤ T g3 ≤ 50, and optionally, -80 ≤ T g3 ≤ 30.

[0202] Exemplarily, the glass transition temperature of the ester polymer may be -100 °C, -90 °C, -80 °C, -60 °C, -30 °C, 0 °C, 30 °C, 50 °C, or a range consisting of any two of the above values.

[0203] In some embodiments, the ester polymer includes a structural unit represented by formula (CI),

Chemical formula

[0204] In formula (CI), R 31 , R 32 and R 33 are each independently a hydrogen atom or a substituted or unsubstituted C1-C8 alkyl group, and R 34 is a substituted or unsubstituted C1-C8 alkyl group or a substituted or unsubstituted C1-C8 hydroxyalkyl group, and optionally, R34 includes a substituted or unsubstituted C1 to C6 alkyl group, or a substituted or unsubstituted C1 to C6 hydroxyalkyl group.

[0205] Selectively, R 31 contains a hydrogen atom or a substituted or unsubstituted methyl group, and R 32 and R 33 each independently contains a hydrogen atom, and R 34 includes a substituted or unsubstituted C1 to C4 alkyl group, or a substituted or unsubstituted C1 to C4 hydroxyalkyl group.

[0206] Illustratively, the ester-based polymer includes at least one of the structural units represented by formula (CI-1) to formula (CI-15), [ka] [ka]

[0207] In some embodiments, the ester-based polymer comprises a structural unit shown in formula (CII): [ka]

[0208] In formula (CII), R 35 contains a substituted or unsubstituted C2-C6 methylene group, and optionally R 35 each independently comprises a substituted or unsubstituted C2 to C4 methylene group.

[0209] Illustratively, the ester-based polymer includes at least one of the structural units represented by formulas (CII-1) to (CII-5), [ka]

[0210] The molecular chains of the ester polymer have a relatively low degree of entanglement, which helps to improve the flexibility of the molecular chains, and the molecular chains can be sufficiently extended in the electrolyte, making it easy to form a gel-like substance with the electrolyte.

[0211] The above polymers are merely examples of structural groups in the main molecular chain, and in the embodiments of the present application, the polymer may be obtained by copolymerizing the above structural groups with other types of structural groups (for example, monomers having functional groups such as olefin-based structural units, acrylonitrile-based structural units, and maleic anhydride).

[0212] In some embodiments, the substituents may include one or more of a nitrile group (-CN), a nitro group, a sulfonic acid group, a sulfonyl group, an amide, a carboxy group, an ester group, or a halogen atom.

[0213] In some embodiments, n is a positive integer selected from 800 to 20,000.

[0214] Optionally, n is a positive integer selected from 1,000 to 15,000.

[0215] In some embodiments, the molecular weight of the polymer is 1.2×10 5 g / mol ~ 1.0 × 10 6 g / mol.

[0216] Illustratively, the molecular weight of the polymer is 1.2×10 5 g / mol, 2 × 10 5 g / mol, 5 × 10 5 g / mol, 8 × 10 5 g / mol, 1×10 6 g / mol, 1.5 × 10 6 It may be g / mol or a range consisting of any two of the above values.

[0217] [Ketone aldehyde polymer]

[0218] In some embodiments, the lyophilic polymer comprises an aldehyde ketone polymer, wherein the aldehyde ketone polymer is formed into a sheet-like structure, and the sheet-like structure has a structure such as (T m4 +20) ° C., a dynamic frequency scanning test is performed to obtain a curve of elastic modulus G'-energy dissipation coefficient G"; the slope of the curve of elastic modulus G'-energy dissipation coefficient G" is K3, 0.8≦K3<∞; T m4 °C represents the melting temperature of the aldehyde ketone polymer.

[0219] In some embodiments, 0.8≦K3≦100, and optionally, 0.8≦K3≦10.

[0220] Illustratively, K3 may be 0.8, 0.9, 1, 2, 5, 10, 15, 20, 30, 50, 100, 200, 500, 1000, 5000, 10000, or a range consisting of any two of the above values.

[0221] In some embodiments, the aldehyde ketone polymer has a glass transition temperature T g4 , the unit is °C, -100≦T g4 ≦50, and optionally, −80≦T g4 ≦30.

[0222] Illustratively, the glass transition temperature of the aldehyde ketone polymer may be −100° C., −90° C., −80° C., −60° C., −30° C., 0° C., 30° C., 50° C., or a range consisting of any two of the foregoing values.

[0223] In some embodiments, the aldehyde ketone polymer comprises a structural unit shown in formula (DI): [ka]

[0224] In formula (DI), R 41 contains a single bond or a substituted or unsubstituted C1-C6 methylene group, and R 42contains a hydrogen atom or a substituted or unsubstituted C1-C6 alkyl group,

[0225] Selectively, R 41 includes a single bond, a substituted or unsubstituted C1-C2 methylene group,

[0226] Selectively, R 42 includes a hydrogen atom, or a substituted or unsubstituted C1 to C3 alkyl group.

[0227] In the present embodiment, a single bond represents that the group is absent and the atoms on both sides of the group are connected by a single bond, for example, R 41 is a single bond, R 41 It indicates that the carbon atoms on both sides are connected in the form of a single bond.

[0228] Illustratively, the aldehyde ketone polymer includes at least one of the structural units represented by formulas (DI-1) to (DI-6), [ka]

[0229] Illustratively, the aldehyde ketone polymer comprises a structural unit shown in formula (DII): [ka]

[0230] In formula (DII), R 43 ~R 46 each independently comprises a hydrogen atom, a hydroxy group, a substituted or unsubstituted C1-C3 alkyl group, a substituted or unsubstituted C1-C3 hydroxyalkyl group, or a substituted or unsubstituted C1-C3 alkoxy group; r and s each independently represent an integer selected from 0 to 5, and at least one of r and s is selected from a positive integer; and optionally, R 43 ~R 46each independently comprises a hydrogen atom, a hydroxy group, a substituted or unsubstituted C1 to C3 alkyl group, a substituted or unsubstituted C1 to C2 hydroxyalkyl group, or a substituted or unsubstituted C1 to C2 alkoxy group.

[0231] In some embodiments, the aldehyde ketone polymer comprises at least one of structural units represented by formula (DII-1) to structural units represented by formula (DII-4), [ka]

[0232] The molecular chains of the aldehyde ketone polymer have a relatively low degree of entanglement, which helps to improve the flexibility of the molecular chains, allowing the molecular chains to stretch sufficiently in the electrolyte and easily form a gel-like substance with the electrolyte.

[0233] The above polymers are merely examples of structural groups in the main molecular chain, and in the embodiments of the present application, the polymer may be obtained by copolymerizing the above structural groups with other types of structural groups (e.g., olefin-based structural units, enol-based structural units, acrylonitrile-based structural units, etc.).

[0234] In some embodiments, the substituents may include one or more of a nitrile group (-CN), a nitro group, a sulfonic acid group, a sulfonyl group, an amide, a carboxy group, an ester group, or a halogen atom.

[0235] In some embodiments, n is a positive integer selected from 500 to 15,000.

[0236] Optionally, n is a positive integer selected from 500 to 10,000.

[0237] In some embodiments, the molecular weight of the polymer is 1.2×10 5 g / mol ~ 1.0 × 10 6 g / mol.

[0238] Illustratively, the molecular weight of the polymer is 1.2×10 5 g / mol, 2 × 10 5 g / mol, 5 × 10 5 g / mol, 8 × 10 5 g / mol, 1×10 6 g / mol, 1.0 × 10 6 It may be g / mol or a range consisting of any two of the above values.

[0239] The embodiment of the present application can further improve the usage reliability and cycle performance of the battery cell if the lyophilic polymer further satisfies one or more of the following conditions:

[0240] In some embodiments, the lyophilic polymer is added to a first solvent at 70°C to form a polymer system, which is then left to stand at 70°C for 8 hours and then at 25°C for 24 hours or more. After these two steps, the polymer system portion swells and absorbs to form a gel-like substance. The polymer system is then filtered through a 200-mesh filter to leave a first substance. The mass of the lyophilic polymer is n (g), the mass of the first substance is m (g), and the ratio of the polymer and the first substance is 5≦m / n≦1000, optionally 10≦m / n≦1000, and more optionally 10≦m / n≦50. Exemplarily, m / n may be 5, 10, 20, 25, 28, 30, 32, 35, 40, 50, 80, 100, 200, 500, 1000, or a range consisting of any two of the above values.

[0241] Illustratively, the ratio of the mass content of the lyophilic polymer to the mass content of the first solvent ranges from 1:100 to 1:10, for example, 3:50, based on the mass of the polymer system.

[0242] Illustratively, the first solvent may be the same as or similar to the solvent of the electrolyte, and the first solvent may include a carbonate-based solvent, for example, a cyclic carbonate solvent and / or a linear carbonate solvent.

[0243] Examples of cyclic carbonate solvents include one or more of ethylene carbonate EC, vinylidene carbonate VC, fluoroethylene carbonate FEC, difluoroethylene carbonate DFEC, vinylethylene carbonate VEC, and dioctyl carbonate CC.

[0244] Examples of linear carbonate solvents include one or more of dimethyl carbonate DMC, diethyl carbonate DEC, ethyl methyl carbonate EMC, diphenyl carbonate DPC, methyl allyl carbonate MAC, and polycarbonate PC.

[0245] Optionally, the first solvent may also contain a lithium salt and an electrolyte additive, such as lithium hexafluorophosphate, vinylidene carbonate VC, fluorovinylidene carbonate FEC, and the like.

[0246] In this application, m / n is also called the sedimentation value, and characterizes the ability of the lyophilic polymer and solvent to transform into a gel-like substance.

[0247] The first substance mainly contains a gel-like substance formed by a lyophilic polymer and a first solvent, and in the gel-like substance, the molecular structure of the polymer does not fundamentally change.

[0248] In some embodiments, to remove the first solvent in the first substance, the first substance is dried at 80°C for 12 hours, and infrared spectroscopy (IR detection) or nuclear magnetic resonance (NMR) testing reveals that the main component of the first substance after drying is the lyophilic polymer.

[0249] The relevant parameters of the lyophilic polymers of the present embodiment can be detected using the following method.

[0250] The lyophilic polymer group of the present embodiment can be detected by infrared spectroscopy (IR). Specifically, the lyophilic polymer is tested using a Thermo Nicolet Nexus 670 attenuated total reflectance Fourier transform infrared spectrometer (FTIR-ATR), and then tested in accordance with the GB / T6040-2002 standard, with the test range being 600-4000 cm by ATR. -1 , reproducibility ±2cm -1 , resolution 4cm -1 Thus, the penetration depth is 0.2 to 0.6 μm.

[0251] The structure of the lyophilic polymer of the present embodiment can be examined using nuclear magnetic resonance (NMR). Specifically, 1H NMR and 13C NMR were performed on a Varian Mercury Plus-400 NMR spectrometer at a test temperature of 20°C, TMS as the internal standard, CDCl3 as the solvent, and a proton resonance frequency of 400 MHz.

[0252] The polymer cell type (suitable for cells with a relatively small proportion of polymer) of the lyophilic polymer of the present embodiment can be tested by decomposition-gas chromatography-mass spectrometry. The specific test steps are as follows: 0.5 mg of sample is accurately weighed and placed in a sample cup, which is then attached to an injection rod and placed in a decomposition apparatus installed near the GC (gas chromatography) inlet. After the temperature of the decomposition apparatus reaches the set temperature, the injection button is pressed and the sample cup quickly falls into the center of the decomposition furnace by free fall. In an inert gas N2 atmosphere, the volatile components are instantly vaporized and carried by the carrier gas to a gas chromatography column for separation. Finally, they are detected by a flame ionization detector (FID) or a mass spectrometer (MS), thereby obtaining a gas chromatogram or total ion flow diagram.

[0253] The molecular weight of the lyophilic polymer of the present embodiment has a meaning known in the art and can be measured using instruments and methods commonly used in the art, such as gel permeation chromatography (GPC). The specific test steps are to weigh out an appropriate amount of sample to be measured (the sample concentration can ensure a light shielding degree of 8% to 12%), add 20 ml of deionized water, and simultaneously irradiate with ultraviolet light (53 kHz / 120 W) for 5 minutes to ensure the sample is completely dispersed. Then, measure the sample according to GB / T19077-2016 / ISO13320:2009 standard.

[0254] Alternatively, the test is performed using a multi-angle laser light scattering (MALLS) instrument. Specifically, a GPC and Dawn Heleos II multi-angle laser light scattering instrument, an Optilab T-rEX refractive index (RI) detector, and a Visco Star II viscometer (Wyatt Technology Corporation, USA) are used. The test is performed using tetrahydrofuran as the mobile phase at a flow rate of 1.0 ml / min at 30°C, and the SEC-SAMLL data are processed using commercially available software ASTRA6 to obtain molecular weight parameters.

[0255] [Positive electrode piece]

[0256] The positive electrode piece includes a positive electrode current collector and a positive electrode active material layer disposed on the positive electrode current collector, the positive electrode active material layer including a positive electrode active material and a lyophilic polymer.

[0257] For example, the positive electrode current collector has two surfaces that face each other in the thickness direction of the positive electrode current collector, and the positive electrode active material layer is disposed on one or both of the two facing surfaces of the positive electrode current collector.

[0258] The positive electrode active material layer includes a positive electrode active material known in the art for use in battery cells, and may include, for example, at least one of a lithium-containing phosphate compound, a lithium-containing transition metal oxide, a sodium-containing phosphate compound, and a sodium-containing transition metal oxide.

[0259] For example, the general formula of an olivine-type phosphate active material (lithium-containing phosphate compound) is Li x A y Me a M b P 1-c X c Y z wherein 0≦x≦1.3, 0≦y≦1.3, and 0.9≦x+y≦1.3; 0.9≦a≦1.5, 0≦b≦0.5, and 0.9≦a+b≦1.5; 0≦c≦0.5; and 3≦z≦5; A includes one or more of Na, K, and Mg; Me includes one or more of Mn, Fe, Co, and Ni; M includes one or more of B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, and Ce; X includes one or more of S, Si, Cl, B, C, and N; and Y includes one or more of O and F. Specifically, the olivine-type phosphate active material includes one or more of LiFePO4, LiMnPO4, LiNiPO4, and LiCoPO4.

[0260] Illustratively, lithium transition metal oxides (layered materials, such as ternary, lithium / sodium nickelate, lithium / sodium cobaltate, lithium / sodium manganate, lithium-rich layered, and rock salt layered materials) are used. The general formula for the layered cathode active material is Li x A y Ni a Co b Mn c M (1-a-b-c) Y zwhere 0≦x≦2.1, 0≦y≦2.1, and 0.9≦x+y≦2.1; 0≦a≦1, 0≦b≦1, 0≦c≦1, and 0.1≦a+b+c≦1; and 1.8≦z≦3.5. A includes one or more of Na, K, and Mg; M includes one or more of B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Fe, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, and Ce; and Y includes one or more of O and F. Optionally, y=0. Specifically, the layered positive electrode active material may be lithium cobalt oxide (LCO), lithium nickel oxide (LNO), lithium manganese oxide (LMO), or 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) and LiNi 0.5 Co 0.2 Mn 0.3 It may contain one or more of O2 (NCM523), NCA.

[0261] In some embodiments, the positive electrode current collector may be a metal foil piece or a composite current collector. Examples of the metal foil piece include aluminum foil or aluminum alloy foil. The composite current collector may include a polymeric material base layer and a metal material layer formed on at least one surface of the polymeric material base layer. For example, the metal material may be a combination of one or more selected from aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy. The polymeric material base layer may be a combination of one or more selected from polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0262] In some embodiments, the positive electrode active material layer also optionally contains a positive electrode conductive agent. The present application is not particularly limited by the type of positive electrode conductive agent. For example, the positive electrode conductive agent may be a combination including one or more selected from superconducting carbon, conductive carbon black, conductive graphite, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. In some embodiments, the mass percentage of the positive electrode conductive agent is 5% or less, based on the total mass of the positive electrode active material layer.

[0263] In some embodiments, the positive electrode active material layer also optionally includes a positive electrode adhesive. The present application is not particularly limited by the type of positive electrode adhesive. For example, the positive electrode adhesive may be a combination including one or more selected from polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylic ester resin. In some embodiments, the mass percentage of the positive electrode adhesive is 5% or less, based on the total mass of the positive electrode active material layer. The positive electrode adhesive has a higher crystallinity than the fluoropolymer of the present application. The positive electrode adhesive has a higher melting temperature than the fluoropolymer of the present application.

[0264] The positive electrode active material layer is typically formed by applying a positive electrode slurry to a positive electrode current collector, drying, and cold rolling. The positive electrode slurry is typically formed by dispersing a positive electrode active material, a lyophilic polymer, an optional conductive agent, an optional adhesive, and any other components in a solvent and stirring the mixture uniformly. The solvent may be, but is not limited to, N-methylpyrrolidone (NMP). Of course, the manufacturing method of the positive electrode pieces is not limited to the above method, and the manufacturing methods described above may also be used.

[0265] [Negative electrode piece]

[0266] In some embodiments, the negative electrode piece includes a negative electrode current collector and a negative electrode active material layer disposed on at least one surface of the negative electrode current collector, the negative electrode active material layer being disposed on one or both of the two opposing surfaces of the negative electrode current collector.

[0267] The negative electrode active material may be any negative electrode active material known in the art and used in battery cells. For example, the negative electrode active material may include, but is not limited to, at least one of natural graphite, artificial graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, lithium metal, sodium metal, and lithium alloys. The silicon-based material may include at least one of elemental silicon, silicon oxide, silicon carbon composite, silicon nitrogen composite, and silicon alloy materials. The tin-based material may include at least one of elemental tin, tin oxide, and tin alloy materials.

[0268] In some embodiments, the negative electrode active material layer also optionally contains a negative electrode conductive agent. The present application is not particularly limited by the type of the negative electrode conductive agent, and for example, the negative electrode conductive agent may include at least one of superconducting carbon, conductive graphite, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. In some embodiments, the mass percentage of the negative electrode conductive agent is ≦5% based on the total mass of the negative electrode active material layer.

[0269] In some embodiments, the negative electrode active material layer also optionally includes a negative electrode adhesive. The present application is not particularly limited by the type of the negative electrode adhesive. For example, the negative electrode adhesive may include at least one of styrene butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, water-soluble acrylic acid-based resin (e.g., polyacrylic acid (PAA), polymethacrylic acid (PMAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS). In some embodiments, the mass percentage of the negative electrode adhesive is ≦5% based on the total mass of the negative electrode active material layer.

[0270] In some embodiments, the negative electrode active material layer also optionally contains other additives. For example, the other additives may include thickeners such as sodium carboxymethyl cellulose (CMC) or PTC thermistor materials. In some embodiments, the weight percentage of the other additives is ≦2% based on the total weight of the negative electrode active material layer.

[0271] In some embodiments, the negative electrode current collector may be a metal foil piece or a composite current collector. An example of the metal foil piece may be copper foil. The composite current collector may include a polymeric material base layer and a metal material layer formed on at least one surface of the polymeric material base layer. For example, the metal material may include at least one of copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy. For example, the polymeric material base layer may include at least one of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0272] The negative electrode active material layer is typically formed by applying a negative electrode slurry to a negative electrode current collector, drying, and cold rolling. The negative electrode slurry is typically formed by dispersing a negative electrode active material, a lyophilic polymer, an optional conductive agent, an optional adhesive, and optional other additives in a solvent and stirring the mixture uniformly. The solvent may be, but is not limited to, N-methylpyrrolidone (NMP) or deionized water. Of course, the method for producing the negative electrode pieces is not limited to the above method, and the aforementioned manufacturing methods may also be used.

[0273] The negative electrode piece does not exclude additional functional layers other than the negative electrode active material layer. For example, in certain embodiments, the negative electrode piece described herein further includes a conductive primer (e.g., composed of a conductive agent and an adhesive) sandwiched between the negative electrode current collector and the negative electrode active material layer and disposed on the surface of the negative electrode current collector. In other embodiments, the negative electrode piece described herein further includes a protective layer covering the surface of the negative electrode active material layer.

[0274] [Separator]

[0275] The separator includes a substrate and a coating disposed on at least one surface of the substrate.

[0276] In some examples, the substrate may generally be a porous structure having pores, and the lyophilic polymer may be distributed in the pores of the substrate.

[0277] As some other examples, the lyophilic polymer may be distributed within the coating.

[0278] As some further examples, the lyophilic polymer may be disposed on a surface of the coating that faces away from the substrate.

[0279] The specific distribution position of the lyophilic polymer may be any one of the above three types, any two of the above three types, or a combination of the above three types of positions.

[0280] The present embodiment is not particularly limited by the material of the substrate, and any known substrate having good chemical and mechanical stability can be selected, such as glass fiber, nonwoven fabric, polyethylene, polypropylene, and at least one of polyvinylidene fluoride. The substrate may be a single-layer film or a multilayer composite film. When the substrate is a multilayer composite film, the materials of each layer may be the same or different. The substrate generally has a porous structure having pores, and the lyophilic polymer may be distributed in the pores of the substrate.

[0281] In some embodiments, the coating may further include a filler. Further, the filler may include at least one of inorganic particles and organic particles. The lyophilic polymer may be distributed within the coating.

[0282] In some embodiments, a lyophilic polymer may be disposed on a surface of the coating away from the substrate.

[0283] In some embodiments, the decomposition temperature of the filler may be 200°C or higher, so that the filler has good thermal stability and is not easily decomposed, and further improves the heat resistance of the separator.

[0284] The inorganic particles have the characteristics of high thermal stability and resistance to decomposition. Optionally, the inorganic particles include at least one of inorganic particles having a dielectric constant of 5 or more, inorganic particles having ionic conductivity but not storing ions, and inorganic particles capable of electrochemical reactions.

[0285] Alternatively, the inorganic particles having a dielectric constant of 5 or more may be boehmite, aluminum oxide, zinc oxide, silicon oxide, titanium oxide, zirconium oxide, barium oxide, calcium oxide, magnesium oxide, nickel oxide, tin oxide, cerium oxide, yttrium oxide, hafnium oxide, aluminum hydroxide, magnesium hydroxide, silicon carbide, boron carbide, aluminum nitride, silicon nitride, boron nitride, magnesium fluoride, calcium fluoride, barium fluoride, barium sulfate, magnesium aluminum silicate, magnesium lithium silicate, magnesium sodium silicate, bentonite, hectorite, zirconium titanate Pb(Zr,Ti)O3 (abbreviated as PZT), Pb 1-m La m Zr 1-n Ti n O3 (abbreviated as PLZT, 0 <m<1、0<n<1)、Pb(Mg3Nb 2 / 3 The coating composition includes at least one of the following: )O3-PbTiO3 (abbreviated as PMN-PT), and modified inorganic particles. Optionally, the modification method of each inorganic particle may be chemical and / or physical. The chemical modification method may include coupling agent modification (e.g., the use of a silane coupling agent, a titanate ester coupling agent, etc.), surfactant modification, polymer graft modification, etc. The physical modification method may be mechanical dispersion, ultrasonic dispersion, high-energy treatment, etc. The modification treatment can reduce the aggregation of inorganic particles, thereby forming a more stable and uniform spatial network structure with nanocellulose. Furthermore, selecting a coupling agent, surfactant material, or polymer-modified inorganic particle with a specific functional group can improve the immersion properties of the coating in the electrolyte and help increase the adhesive strength between the coating and the substrate.

[0286] Optionally, the inorganic particles having ionic conductivity but not storing ions include Li3PO4, lithium titanium phosphate, Li x1 Ti y1 (PO4)3, Lithium titanium aluminum phosphate Li x2 Al y2 Ti z1 (PO4)3(LiAlTiP) x3O y3 type glass, lithium lanthanum titanate Li x4 La y4 TiO3, lithium germanium thiophosphate Li x5 Ge y5 P z2 S w , lithium nitride Li x6 N y6 , SiS2 type glass Li x7 Si y7 S z3 and P2S5 type glass Li x8 P y8 S z4 contains at least one of them, where 0 < x1 < 2, 0 < y1 < 3, 0 < x2 < 2, 0 < y2 < 1, 0 < z1 < 3, 0 < x3 < 4, 0 < y3 < 13, 0 < x4 < 2, 0 < y4 < 3, 0 < x5 < 4, 0 < y5 < 1, 0 < z2 < 1, 0 < w < 5, 0 < x6 < 4, 0 < y6 < 2, 0 < x7 < 3, 0 < y7 < 2, 0 < z3 < 4, 0 < x8 < 3, 0 < y8 < 3, 0 < z4 < 7. In this way, the ion transmission characteristics of the separator can be further improved.

[0287] Since the organic particles have the characteristics of high thermal stability and being difficult to decompose, the heat resistance of the separator can be improved. At the same time, when the internal temperature of the battery cell reaches the melting point of the organic particles due to overcharge abuse, thermal abuse, etc., the organic particles melt and are sucked into the micropores of the substrate by capillary action to close the pores and cut off the circuit, thus playing a role in ensuring the high safety performance of the battery cell.

[0288] In some embodiments, the organic particles include, but are not limited to, at least one of polyethylene particles, polypropylene particles, polystyrene particles, melamine resin particles, phenolic resin particles, polyester particles (e.g., polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate), polyimide particles, polyamideimide particles, polyaramid particles, polyphenylene sulfide particles, polysulfone particles, polyethersulfone particles, polyetheretherketone particles, polyaryletherketone particles, and a copolymer of butyl acrylate and ethyl methacrylate (e.g., a crosslinked polymer of butyl acrylate and ethyl methacrylate).

[0289] In some embodiments, the coating further comprises an adhesive. The present application is not particularly limited to the type of adhesive, and any known material having good adhesive properties can be selected. For example, the adhesive may comprise at least one of a water-soluble acrylic acid-based resin (e.g., a homopolymer of acrylic acid, methacrylic acid, or sodium acrylate monomer, or a copolymer with other comonomers), polyvinyl alcohol, isobutylene-maleic anhydride copolymer, and polyacrylamide.

[0290] Optionally, the content of the adhesive in the coating is less than 30% based on the weight of the coating.

[0291] [Electrolyte]

[0292] During the charge and discharge process of the battery cell, active ions are repeatedly inserted and removed between the positive and negative electrode pieces, and the electrolyte serves to conduct the active ions between the positive and negative electrode pieces. The present application is not particularly limited to the type of electrolyte, and it can be selected according to actual needs.

[0293] The electrolyte solution includes an electrolyte salt and a solvent. The types of the electrolyte salt and the solvent are not specifically limited and may be selected according to actual needs.

[0294] When the battery cell according to the present application is a lithium-ion battery, the electrolyte salt may include, by way of example only, at least one of lithium hexafluorophosphate (LiPF), lithium tetrafluoroborate (LiBF), lithium perchlorate (LiClO), lithium hexafluoroarsenate (LiAsF), lithium bisfluorosulfonimide (LiFSI), lithium bistrifluoromethanesulfonimide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorooxalate borate (LiDFOB), lithium dioxalate borate (LiBOB), lithium difluorophosphate (LiPOF), lithium difluorodioxalate phosphate (LiDFOP), and lithium tetrafluorooxalate phosphate (LiTFOP).

[0295] When the battery cell according to the present application is a sodium-ion battery, the electrolyte salt may include, by way of example only, at least one of lithium sodium hexafluorophosphate (NaPF), sodium tetrafluoroborate (NaBF), sodium perchlorate (NaClO), sodium hexafluoroarsenate (NaAsF), sodium bisfluorosulfonimide (NaFSI), sodium bistrifluoromethanesulfonimide (NaTFSI), sodium trifluoromethanesulfonate (NaTFS), sodium difluorooxalyl borate (NaDFOB), sodium dioxalyl borate (NaBOB), sodium difluorophosphate (NaPOF), sodium difluorodioxalyl phosphate (NaDFOP), and sodium tetrafluorooxalyl phosphate (NaTFOP).

[0296] By way of example, the solvent may include, but is not limited to, 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), butylene 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), ethyl methyl sulfone (EMS), and diethyl sulfone (ESE).

[0297] In some embodiments, the electrolyte solution also optionally contains additives. For example, the additives may include a negative electrode film-forming additive, a positive electrode film-forming additive, and may further include additives that can improve specific battery performance, such as an additive that improves the overcharge performance of the battery, an additive that improves the high-temperature performance of the battery, or an additive that improves the low-temperature power performance of the battery.

[0298] In some embodiments, the positive electrode pieces, the separator, and the negative electrode pieces can be fabricated into an electrode assembly by a winding process and / or a stacking process.

[0299] In some embodiments, the battery cell may include an outer packaging that can be used to enclose the electrode assembly and electrolyte.

[0300] In some embodiments, the battery cell exterior packaging may be a hard casing such as a hard plastic casing, an aluminum casing, or a steel casing. The battery cell exterior packaging may be a soft pack such as a bag-type soft pack. The soft pack may be made of plastic such as at least one of polypropylene (PP), polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0301] In some embodiments, the positive electrode pieces, separator, and negative electrode pieces can be fabricated into an electrode assembly by a winding or lamination process.

[0302] The present application is not particularly limited to the shape of the battery cell, and it may be cylindrical, rectangular, or any other shape. Figure 1 shows an example of a battery cell 5 with a rectangular structure.

[0303] In some embodiments, as shown in FIGS. 1 and 2 , the exterior package may include a casing 51 and a cover plate 53. Here, the casing 51 may include a base plate and a side plate connected to the base plate, and the base plate and the side plate surround and form a receiving cavity. The casing 51 has an opening communicating with the receiving cavity, and the cover plate 53 is used to cover the opening and seal the receiving cavity. The positive electrode piece, the negative electrode piece, and the separator may be formed into an electrode assembly 52 by a winding process or a stacking process. The electrode assembly 52 is sealed in the receiving cavity. An electrolyte is immersed in the electrode assembly 52. ​​The number of electrode assemblies 52 included in the battery cell 5 may be one or more and can be adjusted as needed.

[0304] The manufacturing method of the battery cell according to the present application is well known. In some embodiments, a battery cell can be formed by assembling a positive electrode piece, a separator, a negative electrode piece, and an electrolyte. For example, the positive electrode piece, the separator, and the negative electrode piece can be wound or stacked to form an electrode assembly. The electrode assembly can then be placed in an outer package, dried, and then injected with an electrolyte. The battery cell can then be obtained by processes such as vacuum sealing, standing, chemical formation, and shaping.

[0305] In some embodiments of the present application, a battery module can be assembled using the battery cells of the present application, and the number of battery cells included in the battery module can be multiple, and the specific number can be adjusted according to the application and capacity of the battery module.

[0306] 3 is a schematic diagram of an exemplary battery module 4. As shown in FIG. 3, in the battery module 4, a plurality of battery cells 5 can be arranged in order along the length of the battery module 4. Of course, they can also be arranged in any other manner. Furthermore, the plurality of battery cells 5 can be fixed by fastening members.

[0307] Optionally, the battery module 4 may further include an exterior casing having an accommodating space, and the plurality of battery cells 5 are accommodated in the accommodating space.

[0308] In some embodiments, the battery modules may be assembled into a battery pack, and the number of battery modules included in the battery pack may be adjusted according to the application and capacity of the battery pack.

[0309] Both the battery module 4 and the battery pack can be specific examples of the battery of the present application.

[0310] 4 and 5 are schematic diagrams of an example battery pack 1. As shown in FIGS. 4 and 5, the battery pack 1 may include a battery case and a plurality of battery modules 4 installed in the battery case. The battery case includes an upper case 2 and a lower case 3, and the upper case 2 is used to cover the lower case 3 and form a sealed space for accommodating the battery modules 4. The plurality of battery modules 4 can be arranged in the battery case according to any method.

[0311] Electrical equipment

[0312] In a second aspect, the present application provides an electric device including at least one of the battery cell, battery module, and battery pack according to the present application. The battery cell, battery module, and battery pack may be used as a power source for the electric device or as an energy storage unit for the electric device. The electric device may be, but is not limited to, a mobile device (e.g., a mobile phone, a laptop, etc.), an electric vehicle (e.g., a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck, etc.), an electric train, a ship, a satellite, an energy storage system, etc. In some embodiments, the battery cell includes a liquid injection hole for injecting an electrolyte, and when the battery cell is applied to an electric device, the liquid injection hole is located at the bottom along the vertical direction of the battery cell. Because the amount of free electrolyte in the battery cell is extremely small, or even there is no free electrolyte, even when the liquid injection hole is located at the bottom along the vertical direction of the battery cell, the reliability of the battery cell can be improved, thereby improving the reliability of the electric device.

[0313] An electric device can be configured as a battery cell, a battery module, or a battery pack depending on its usage needs. FIG. 6 is a schematic diagram of an example electric device. The electric device 6 can be a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the high power and high energy density needs of the electric device, a battery pack 1 or a battery module can be used. Other example electric devices include mobile phones, tablet computers, and laptops. The electric device generally requires thinness and light weight, and can use battery cells as a power source.

[0314] Example

[0315] The following examples of the present application are described. The examples described below are illustrative and are intended only to explain the present application and should not be understood as limitations on the present application. Unless specific techniques or conditions are specified in the examples, they are carried out in accordance with techniques or conditions described in literature in the art or in accordance with product specifications. Unless manufacturers are specified, reagents or equipment used are all ordinary products that can be obtained commercially.

[0316] Example 1: Manufacture of a lithium-ion battery

[0317] (1) Manufacturing of positive electrode pieces:

[0318] A 12 μm thick aluminum foil was used as the positive electrode current collector.

[0319] Lyophilic polymer, LiNi, the positive electrode active material 0.8 Co 0.1 Mn 0.1Positive electrode slurry was prepared by adding and mixing O2 (NCM811), the conductive agent carbon black, and the adhesive polyvinylidene fluoride (PVDF) with N-methylpyrrolidone (NMP). The mass ratio of the lyophilic polymer, NCM811, conductive carbon black, PVDF, and N-methylpyrrolidone (NMP) in the positive electrode slurry was 0.5:96.8:2.2:0.5. The positive electrode slurry was applied to an aluminum foil current collector, dried at 85°C, and then cold-rolled. After trimming, cutting, and slitting, the foil was dried at 85°C under vacuum for 4 hours to produce positive electrode pieces.

[0320] (2) Manufacturing of negative electrode pieces:

[0321] A copper foil with a thickness of 8 μm was prepared as the negative electrode current collector.

[0322] A lyophilic polymer, artificial graphite (anode active material), carbon black (conductive agent), styrene butadiene rubber (SBR) (adhesive), and sodium carboxymethyl cellulose (CMC) (thickener) were added to deionized water in a weight ratio of 2.5:94.9:2:0.5:0.1 and mixed uniformly to produce anode slurry. The anode slurry was applied to a copper foil current collector and dried at 85°C. The foil was then cold-rolled, trimmed, cut, and slit, and then dried in a vacuum at 120°C for 12 hours to produce anode pieces.

[0323] (3) Electrolyte production:

[0324] In an environment with a water content of less than 10 ppm, non-aqueous organic solvents ethylene carbonate (EC) and ethyl methyl carbonate (EMC) were mixed in a volume ratio of 3:7 to obtain an electrolyte solvent, which was then mixed with lithium salt LiPF6 to prepare an electrolyte with a lithium salt concentration of 1 mol / L.

[0325] (4) Lithium-ion battery manufacturing:

[0326] A 16 μm polyethylene film (PE) was used as the substrate for the separator, and a polymer coating was applied to the surface of the substrate. The mass contents of the ordinary vinylidene fluoride (PVDF) and the adhesive styrene butadiene rubber (SBR) in the polymer coating were 85%:15%, respectively.

[0327] The positive electrode pieces, separator, and negative electrode pieces are stacked in this order, and a separator is interposed between the positive electrode pieces and the negative electrode pieces to separate them. Then, the stack is wound to obtain an electrode assembly. The electrode assembly is placed in an outer package, dried, and then an electrolyte is injected. A lithium ion battery is obtained by processes such as vacuum sealing, standing, chemical formation, and shaping.

[0328] Comparative Example 1

[0329] A lithium ion battery was manufactured using a method similar to that of Example 1, except that no lyophilic polymer was added to the positive electrode slurry of Comparative Example 1, and no lyophilic polymer was added to the negative electrode slurry.

[0330] Examples 2-1 to 2-6

[0331] Lithium ion batteries were manufactured using a method similar to that of Example 1, and the difference from Example 1 is that Examples 2-1 to 2-6 were adjusted in at least one of the total pore volume of the positive electrode pieces, the total pore volume of the negative electrode pieces, the amount of lyophilic polymer added in the positive electrode slurry, and the amount of lyophilic polymer added in the negative electrode slurry.

[0332] Examples 3-1 to 3-4

[0333] Lithium ion batteries were manufactured using a method similar to that of Example 1, but the difference from Example 1 is that the type of lyophilic polymer was adjusted in Examples 3-1 to 3-4.

[0334] Examples 4-1 to 4-3

[0335] A lithium ion battery was manufactured using a method similar to that of Example 1. The difference from Example 1 is that in Examples 4-1 to 4-3, the setting position of the lyophilic polymer was adjusted, and in Example 4-3, the mass content of polycarbosilane PCS was 80%, the mass content of the lyophilic polymer was 10%, and the mass content of the adhesive was 10%.

[0336] The data for the examples and comparative examples are shown in Table 1.

[0337] Testing part

[0338] 1. Lithium-ion battery cycle performance test

[0339] The lithium ion batteries manufactured in the examples and comparative examples were charged at a rate of 1C at 25±2°C and discharged at a rate of 1C. A full charge-discharge cycle test was performed until the capacity of the secondary battery decreased to 80% of the initial capacity, and the test was stopped and the number of cycles was recorded.

[0340] 2. Liquid leakage insulation test for lithium-ion battery modules

[0341] The lithium-ion batteries manufactured in the examples and comparative examples were charged to 100% SOC at 0.5C (i.e., a current of 0.5 times the capacity rate) at 25±2°C and left to stand for 1 hour. To simulate a battery core liquid leakage scenario, a small hole with a diameter of 2 mm was drilled at the bottom of the battery core. Twelve battery cores were connected in series, with one end of the module connected to the module negative electrode and the other end half-overlapped / overlapped to the end plate. An external voltage of 200V was applied and observed for 1 hour (if a fire occurred, the short circuit was disconnected). The presence or absence of a fire due to insulation failure and the duration of the fire were confirmed.

[0342] [Table 1] [Table 2] [Table 3]

[0343] In Table 1, VDF stands for vinylidene fluoride, HFP stands for hexafluoropropylene, and TFE stands for tetrafluoroethylene. 80% VDF + 15% HFP + 5% TFE indicates that the weight percent of VDF is 80%, the weight percent of HFP is 15%, and the weight percent of TFE is 5% of the total weight of all monomers.

[0344] The nominal capacity x of the batteries of the comparative example and the example is 151 Ah.

[0345] [Table 4]

[0346] As can be seen from Tables 1 and 2, no lyophilic polymer is added to the positive and negative electrode pieces of Comparative Example 1. During the cycling process of the lithium ion battery, the volume of the lithium ion battery changes, so the electrolyte in the electrode assembly is pushed out, which may cause liquid shortage problems, thereby increasing the risk of lithium dendrite formation and reducing the usage reliability and cycling performance of the lithium ion battery.

[0347] In the examples of the present application, a lyophilic polymer that can form a cohesive electrolyte with the electrolyte to improve the liquid retention capacity is added to at least one of the positive electrode pieces, the negative electrode pieces, and the separator, thereby improving the usage reliability and cycle performance of the lithium ion battery.

[0348] Although the present application has been described with reference to preferred embodiments, various modifications may be made thereto and equivalents may be substituted for elements therein without departing from the scope of the present application. In particular, as long as there is no structural contradiction, the technical features recited in each embodiment may be combined in any manner. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions encompassed by the claims.

Claims

1. A battery cell including an electrode assembly including a first pole piece, a second pole piece, and a separator, and an electrolyte, wherein the polarities of the first pole piece and the second pole piece are opposite, the separator is disposed between the first pole piece and the second pole piece, and at least one of the first pole piece, the second pole piece, and the separator includes a lyophilic polymer, and the battery cell satisfies the following formula: [Equation 1] p1 represents the porosity of the first pole piece; v1 is the total volume of the first pole piece in μm ３ It is expressed as p2 represents the porosity of the second pole piece; v2 is the total volume of the second pole piece in μm ３ It is expressed as p3 represents the porosity of the separator; v3 is the total volume of the separator in μm ３ It is expressed as y represents the mass of free electrolyte in the battery cell in g; Battery cell. 【Request Item 2】 【Number 2】 The battery cell according to claim 1 ,

3. The battery cell also satisfies the following formula: [Equation 3] Selectively, [Equation 4] More selectively, [Equation 5] m １ represents the mass of the electrode assembly before drying in g, m ２ represents the mass of the electrode assembly after drying in g; The battery cell according to claim 1 or 2.

4. The amount of free electrolyte per unit capacity of the battery cell is b, its unit is mg / Ah, and 0≦b≦1400; Alternatively, 0.1≦b≦1000, and more preferably, 0.3≦b≦800. The battery cell according to any one of claims 1 to 3.

5. the first pole piece includes a current collector and an active material layer disposed on at least one surface of the current collector, the active material layer including the lyophilic polymer and active material particles; the lyophilic polymer is distributed on the surface of the active material particles; and / or the active material particles are plural, and pores are formed between adjacent active material particles, and the lyophilic polymer is distributed in the pores between the active material particles; The battery cell according to any one of claims 1 to 4.

6. the separator includes a substrate and a coating disposed on at least one surface of the substrate; the lyophilic polymer is distributed in the pores of the substrate; and / or the lyophilic polymer is distributed within the coating; and / or the lyophilic polymer is disposed on the surface of the coating facing away from the substrate; The battery cell according to any one of claims 1 to 5.

7. the lyophilic polymer comprises a fluoropolymer; The crystallinity of the fluoropolymer measured by differential scanning calorimetry is Xc １ , 0<Xc １ ≦30%; The melting temperature of the fluoropolymer is T ｍ１ , the unit is °C, 0 < T ｍ１ ≦140, The battery cell according to any one of claims 1 to 6.

8. The glass transition temperature of the fluoropolymer is T ｇ１ , the unit is °C, -150≦T ｇ１ ≦60, The battery cell according to claim 7 .

9. The fluoropolymer contains at least one structural unit selected from the structural units represented by formulas (AI) to (AIII), 【Chemistry 1】 In formula (AI) and formula (AII), R １１ , R １２ , R １３ and R １４ each independently comprises a hydrogen atom, a fluorine atom, a chlorine atom, a substituted or unsubstituted C1 to C3 alkyl group, or a substituted or unsubstituted C1 to C3 alkoxy group, and R １１ , R １２ , R １３ and R １４ at least one of the groups contains a fluorine atom, and when substituted, the substituents contain one or more of a nitrile group (—CN), a nitro group, a sulfonic acid group, a sulfonyl group, an amide, a carboxy group, an ester group, and a halogen atom; 【Chemistry 2】 In formula (AIII), R １５ contains a single bond or a substituted or unsubstituted C1 to C3 alkyl group, and if substituted, the substituent contains one or more of a nitrile group (—CN), a nitro group, a sulfonic acid group, a sulfonyl group, an amide group, a carboxy group, an ester group, and a halogen atom; p is a positive integer selected from 1 to 3; and n is a positive integer selected from 1,000 to 30,000. The battery cell according to claim 7 or 8.

10. The lyophilic polymer includes an ether-based polymer, and the ether-based polymer is formed into a sheet-like structure, and the sheet-like structure has a structure such as (T ｍ２ +20°C, a dynamic frequency scanning test was performed to obtain a modulus of elasticity G'-energy dissipation coefficient G" curve, and the slope of the modulus of elasticity G'-energy dissipation coefficient G" curve was K １ , 1<K １ <∞, and T ｍ２ °C represents the melting temperature of the ether-based polymer; optionally, 1 < K １ ≦100, and further optionally, 1<K １ ≦10, The battery cell according to any one of claims 1 to 9.

11. The ether-based polymer contains a structural unit represented by formula (BI) and / or a structural unit represented by formula (BII), 【Transformation 3】 In formula (BI), R ２１ and R ２２ each independently comprises a hydrogen atom, a substituted or unsubstituted C1 to C3 alkyl group, or a substituted or unsubstituted C1 to C3 alkoxy group; R ２３ comprises a substituted or unsubstituted C1-C5 alkylene group, 【Chemistry 4】 In formula (BII), R ２４ ~R ２７ each independently comprises a hydrogen atom, a substituted or unsubstituted C1 to C3 alkyl group, a substituted or unsubstituted C1 to C3 alkoxy group, or an ether group, and R ２４ ~R ２７ at least one of which contains a substituted or unsubstituted C1-C3 alkoxy group or ether group; The battery cell of claim 10.

12. The lyophilic polymer includes an ester-based polymer, and the ester-based polymer is formed into a sheet-like structure, and the sheet-like structure is formed into a polymer having a molecular weight of 1000 or more. ｍ３ +20°C, a dynamic frequency scanning test was performed to obtain a modulus of elasticity G'-energy dissipation coefficient G" curve, and the slope of the modulus of elasticity G'-energy dissipation coefficient G" curve was K ２ , 1<K ２ <∞, and T ｍ３ °C represents the melting temperature of the ester-based polymer, optionally 1 < K ２ ≦100, and further optionally, 1<K ２ ≦10, The battery cell according to any one of claims 1 to 11.

13. The ester-based polymer contains a structural unit represented by formula (CI) and / or a structural unit represented by formula (CII), 【Transformation 5】 In formula (CI), R ３１ , R ３２ and R ３３ each independently comprises a hydrogen atom or a substituted or unsubstituted C1 to C8 alkyl group; R ３４ comprises a substituted or unsubstituted C1-C8 alkyl group or a substituted or unsubstituted C1-C8 hydroxyalkyl group; 【Transformation 6】 In formula (CII), R ３５ comprises a substituted or unsubstituted C2-C6 methylene group, optionally R ３５ each independently comprises a substituted or unsubstituted C2-C4 methylene group; The battery cell of claim 12.

14. The lyophilic polymer includes an aldehyde ketone polymer, and the aldehyde ketone polymer is formed into a sheet-like structure, and the sheet-like structure has a structure represented by (T ｍ４ +20°C, a dynamic frequency scanning test was performed to obtain a modulus of elasticity G'-energy dissipation coefficient G" curve, and the slope of the modulus of elasticity G'-energy dissipation coefficient G" curve was K ３ , 0.8≦K ３ <∞, and T ｍ４ °C represents the melting temperature of the aldehyde ketone polymer, optionally 0.8 < K ３ ≦100, and further optionally, 0.8≦K ３ ≦10, The battery cell according to any one of claims 1 to 13.

15. The aldehyde ketone polymer comprises a structural unit represented by formula (DI) and / or a structural unit represented by formula (DII), 【Transformation 7】 In formula (DI), R ４１ contains a single bond, a substituted or unsubstituted C1-C6 methylene group, and R ４２ contains a hydrogen atom or a substituted or unsubstituted C1-C6 alkyl group, 【Transformation 8】 In formula (DII), R ４３ ~R ４６ each independently comprise a hydrogen atom, a hydroxy group, a substituted or unsubstituted C1 to C3 alkyl group, a substituted or unsubstituted C1 to C3 hydroxyalkyl group, or a substituted or unsubstituted C1 to C3 alkoxy group, and r and s each independently represent an integer selected from 0 to 5, and at least one of r and s is selected from a positive integer; The battery cell of claim 14.

16. The molecular weight of the lyophilic polymer is 1.2×10 ５ g / mol to 1×10 ６ g / mol, The battery cell according to any one of claims 1 to 15.

17. A battery cell according to any one of claims 1 to 16, battery.

18. 18. A battery comprising the battery of claim 17. Electrical equipment.

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