Lithium secondary batteries and power consumption devices

Abstract

The present application provides an electrode sheet and related battery cells, batteries, and power consumption devices. The electrode sheet includes a current collector and an active material layer provided on at least one surface of the current collector. The active material layer includes an active material and an ether-based polymer, and the active material layer satisfies formulas (1) to (3). As a component of the active material layer, the ether-based polymer forms uniformly high wetting points within the active material layer, thereby uniformly improving the wetting performance of the active material layer, increasing the liquid absorption rate of the entire active material layer, and improving the cycle performance of the battery cell. [Equation 1] JPEG2025529305000019.jpg41170

Description

[Technical Field]

[0001] This application relates to the field of batteries, and more particularly to polar sheets and associated battery cells, batteries and power consuming 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 vehicles, electric toy boats, electric toy airplanes, and power tools.

[0003] As the range of battery applications becomes wider, the requirements for battery cell performance are also becoming more stringent. To improve the safety performance of battery cells, the performance of the electrode sheets in the battery cells is usually optimized and improved. However, the active material in the electrode sheets currently has poor liquid absorption performance, resulting in poor cycle performance when used in battery cells. Summary of the Invention

[0004] The present invention has been made in view of the above problems, and aims to provide an electrode sheet and related battery cells, batteries, and power consumption devices.

[0005] A first aspect of the present application provides an electrode sheet comprising a current collector and an active material layer provided on at least one surface of the current collector, the active material layer containing an active material and an ether-based polymer, and the active material layer satisfies formulas (1) to (3).

number

[0006] In formulas (1) to (3), λ represents the porosity of the active material layer, P1 represents the actual compressed density of the active material layer, and its unit is g / cm 3 and P2 represents the true compression density of the active material, with the unit of g / cm 3 and v represents the liquid absorption rate of the active material layer, with the unit of mg / s, d represents the diameter of the capillary in the capillary test provided in the active material layer, with the unit of mm, h represents the liquid level height in the capillary, with the unit of mm, ρ represents the density of the electrolyte in the capillary test, with the unit of g / cm 3 and t represents the time when the electrolyte in the capillary is absorbed, with the unit of s.

[0007] Thereby, the ether-based polymer of the present application is introduced into the manufacturing process of the active material layer, so as to form a uniform high wetting point inside the active material layer, uniformly improve the wetting performance of the active material layer, improve the liquid absorption rate of the entire active material layer, and improve the cycle performance of the battery cell using the electrode sheet.

[0008] In some embodiments, the active material includes a positive electrode active material, and the active material layer satisfies 1.00 < v / λ < 4.00, and optionally satisfies 1.20 ≤ v / λ ≤ 3.80.

[0009] In some embodiments, the active material includes a positive electrode active material, and the mass percentage of the ether-based polymer with respect to the mass of the active material layer is A%, where 0.1 ≤ A ≤ 1.5. When the mass percentage of the ether-based polymer is within the above range, the liquid absorption capacity of the positive electrode active material layer can be significantly improved.

[0010] In some embodiments, the active material includes a negative electrode active material, and the active material layer satisfies 3.00 < v / λ < 50.00, and optionally satisfies 3.40 ≤ v / λ ≤ 30.00.

[0011] In some embodiments, the active material includes a negative electrode active material. With respect to the mass of the active material layer, the mass percentage of the ether-based polymer is B%, and 0.2 ≤ B ≤ 5.0. When the mass percentage of the ether-based polymer is within the above range, the liquid absorption capacity of the negative electrode active material layer can be significantly improved.

[0012] In some embodiments, the ether-based polymer is manufactured into a sheet-like structure, and a dynamic frequency scanning test is performed on the sheet-like structure at (T m + 20) °C to obtain a storage modulus G'-loss modulus G" curve. The slope of the storage modulus G'-loss modulus G" curve is K, and 1 < K < ∞, optionally 1 < K ≤ 100, and further optionally 1 < K ≤ 10. T m °C represents the melting temperature of the ether-based polymer. Thus, when the polymer of the present application satisfies the above range, the entanglement state of the molecular chains can be further reduced, which is advantageous for the solvent molecules in the electrolyte to diffuse between the molecular chains. Also, the polymer still maintains a certain entanglement state of the molecular chains, can lock the solvent molecules in-situ inside the polymer, and can reduce the risk of the polymer dissolving in the electrolyte, improving the stability of the polymer performance. Also, it is advantageous for the polymer to form a protective layer on the surface of the active material, improving the solid-liquid interface performance, reducing the side reaction between the active material and the electrolyte, and improving the cycle performance and storage performance of the battery cell.

[0013] In some embodiments, the glass transition temperature of the ether-based polymer is Tg, with the unit of °C, and -100 ≤ Tg ≤ 50, optionally -80 ≤ Tg ≤ 30. When the glass transition temperature of the ether-based polymer is relatively low, the flexibility of the segments of the molecular chains is better, adjacent molecular chains are more easily opened, an in-situ gel is more easily formed, and by improving the wetting performance of the electrolyte on the active material layer, the cycle performance of the battery cell is improved.

[0014] In some embodiments, the ether-based polymer includes a structural unit represented by formula (I). [ka]

[0015] In formula (I), R1 and R2 each independently comprise a hydrogen atom, a substituted or unsubstituted C1-C3 alkyl group, or a substituted or unsubstituted C1-C3 alkoxy group; R3 comprises a substituted or unsubstituted C1-C5 methylene group; optionally, R1 and R2 each independently comprise a hydrogen atom, a substituted or unsubstituted C1-C2 alkyl group, and / or R3 comprises a single bond, a substituted or unsubstituted C1-C4 methylene group.

[0016] In some embodiments, the ether-based polymer includes at least one of structural units represented by formula (I-1) to (I-8). [ka]

[0017] In some embodiments, the ether-based polymer comprises a structural unit represented by formula (II). [ka]

[0018] In formula (II), R4 to R7 each independently comprise 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 at least one of R4 to R7 comprises a substituted or unsubstituted C1 to C3 alkoxy group or ether group; alternatively, R4 to R7 each independently comprise a hydrogen atom, a substituted or unsubstituted C1 to C2 alkyl group, a substituted or unsubstituted C1 to C2 alkoxy group, or an ether group, and at least one of R4 to R7 comprises a substituted or unsubstituted C1 to C2 alkoxy group or ether group.

[0019] In some embodiments, the ether-based polymer includes at least one of structural units represented by formula (II-1) to (II-7). [ka]

[0020] In some embodiments, n is selected from a positive integer of 1500 to 25000, and / or the molecular weight of the ether-based polymer is 1.2×10 5 g / mol ~ 1.0 × 10 6 g / mol. When the molecular weight of the polymer is within this range, it is possible to ensure that the polymer exhibits a certain solubility in the electrolyte, and it is difficult for the polymer to be completely dissolved and dispersed in the electrolyte, which is advantageous for adjusting the distribution and dispersion of the polymer on the surface of the active material. In addition, it is possible to further improve the flexibility of the polymer's molecular chains, and the interaction between the molecular chains is relatively weak, which is advantageous for the solvent molecules in the electrolyte to open the molecular chains, enter between the molecular chains, and be enveloped by them. This is advantageous for the active ions to enter the active material through the solvent, realizing smooth and rapid migration of the active ions.

[0021] In some embodiments, the polymer is added to a first solvent at 45°C to form a polymer system, the polymer system is allowed to stand at 45°C for 8 hours, and then allowed to stand at 25°C for 24 hours or more. After the polymer system is filtered through a 200 mesh filter, a first substance remains, wherein the mass of the polymer is n in g, the mass of the first substance is m in g, and the ratio of the polymer and the first substance satisfies 5≦m / n≦1000.

[0022] Thus, the present invention achieves the expansion of polymer molecular chains within the safe operating temperature range of a battery cell by increasing the temperature, and promotes mutual attraction and physical bonding between the polymer molecular chains and the solvent. At room temperature, the polymer molecular segments lose their activity and adhere to the active material surface, locking the electrolyte in the polymer's spatial environment and forming an in-situ gel-like state, protecting the active material interface and maintaining normal lithium ion transport, thereby achieving interfacial protection, reducing surface side reactions, and improving cycle performance and storage performance.

[0023] A second aspect of the present application provides a battery cell including a pole sheet according to any one of the embodiments of the first aspect of the present application.

[0024] A third aspect of the present application provides a battery including the battery cell according to the second aspect of the present application.

[0025] A fourth aspect of the present application provides a power consuming device including a battery according to the third aspect of the present application. [Brief explanation of the drawings]

[0026] In order to more clearly explain the technical solutions of the embodiments of the present application, the following briefly introduces the drawings necessary for the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and those skilled in the art can obtain other related drawings based on these drawings without any creative efforts. [Figure 1] FIG. 1 is a schematic diagram of one embodiment of a battery cell of the present application. [Figure 2] FIG. 2 is an exploded schematic view of an embodiment of the battery cell of FIG. 1. [Figure 3] 1 is a schematic diagram of one embodiment of a battery module of the present application. [Figure 4] 1 is a schematic diagram of one embodiment of a battery pack of the present application. [Figure 5] 5 is an exploded schematic view of the embodiment of the battery pack shown in FIG. 4. [Figure 6]1 is a schematic diagram of one embodiment of a power consuming device that includes a battery cell of the present application as a power source.

[0027] The drawings are not necessarily drawn to scale. DETAILED DESCRIPTION OF THE INVENTION

[0028] Hereinafter, embodiments of the electrode sheet and the related battery cell, battery, and power consumption device specifically disclosed in the present application will be described in detail. However, unnecessary details may be omitted. For example, detailed descriptions of well-known matters or redundant descriptions of substantially identical configurations may be omitted. This is to avoid unnecessary redundancy in the following description and to facilitate understanding by those skilled in the art. Note that the accompanying 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.

[0029] "Ranges" disclosed in this application 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 that particular range. Such defined ranges may be inclusive or exclusive of the end values, and may be arbitrarily combined, i.e., any lower limit may be combined with any upper limit to form a range. For example, if ranges of 60 to 120 and 80 to 110 are recited for a particular parameter, it is understood that ranges of 60 to 110 and 80 to 120 are also contemplated. Furthermore, if minimum range values ​​of 1 and 2 and maximum range values ​​of 3, 4, and 5 are recited, then ranges of 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 between a and b, where a and b are both real numbers. For example, the numerical range "0 to 5" indicates that all real numbers between "0 and 5" are listed in this specification, and "0 to 5" is an abbreviation for combinations of these numerical values. Furthermore, the notation that a parameter is an integer greater than or equal to 2 (≧2) is equivalent to disclosing that the parameter is, for example, the integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc. Unless otherwise specified, all embodiments and optional embodiments of the present application may be combined with each other to form new technical solutions. Unless otherwise specified, all technical features and optional technical features of the present application may be combined with each other to form new technical solutions.

[0030] Unless otherwise specified, all steps in this application may be performed in order or randomly, but are preferably performed in order. For example, when the method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed in order, or may include steps (b) and (a) performed in order. For example, when it is stated that the method may further include step (c), it means that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or may include steps (a), (c), and (b), or may include steps (c), (a), and (b), etc.

[0031] Unless otherwise specified, the terms "comprise" and "include" used in this application mean open-ended and may also be closed-ended. For example, the terms "comprise" and "include" can mean "comprise" or "include" other components not listed, or "comprise" or "include" only the listed components.

[0032] 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 of the following satisfies the condition "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).

[0033] In this application, the terms "plurality" and "plurality" refer to two or more.

[0034] The term "alkyl" includes straight-chain and branched-chain alkyl. For example, an alkyl group can 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, alkyl includes methyl, ethyl, propyl, isopropyl, butyl, isobutyl, and the like. Additionally, alkyl groups can be optionally substituted. When substituted, the substituents include fluorine atoms.

[0035] The term "alkoxy group" refers to a group in which an alkyl group and an oxygen atom are linked by 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. The alkoxy group may also be optionally substituted.

[0036] The term "hydroxyalkyl group" refers to a group in which a hydroxy group and an alkyl group are linked by a single bond. For example, the hydroxyalkyl group may be a C1-C8 hydroxyalkyl group, a C1-C5 hydroxyalkyl group, a C1-C3 hydroxyalkyl group, or a C1-C2 hydroxyalkyl group. In some embodiments, the hydroxyalkyl group may include hydroxymethyl, hydroxyethyl, hydroxypropyl, hydroxybutyl, etc. Additionally, the hydroxyalkyl group may be optionally substituted.

[0037] The term "halogen atom" means a fluorine atom, a chlorine atom, a bromine atom, and the like.

[0038] The term "hydrogen" refers to 1H (protium, H), 2H (deuterium, D), or 3H (tritium, T). In each embodiment, "hydrogen" may be 1H (protium, H).

[0039] The battery cell includes an electrode assembly and an electrolyte. The electrode assembly includes a positive electrode sheet, a negative electrode sheet, and a separator between the positive and negative electrode sheets. The electrode assembly has a gap-void structure, and the electrolyte wets the electrode assembly. The driving force for wetting is mainly capillary force, which is a spontaneous permeation and absorption process. Due to the blocking of the current collector in the electrode sheet, the electrolyte permeates and is absorbed into the electrode assembly from the end face through the separator. The gap between the electrode assembly layers acts as a current guide, and the separator acts as a current divider. The process by which the electrolyte penetrates into the electrode assembly includes: (1) the electrolyte is transported through the gap between the electrode sheet and the separator under the action of capillary force; (2) the electrolyte preferentially penetrates into the voids in the separator (the electrolyte's wetting speed in the separator is much faster than its wetting speed in the active material layer of the electrode sheet); and (3) the electrolyte diffuses through the separator to the surfaces of the positive and negative electrode sheets on both sides and penetrates into the voids in the active material layer.

[0040] In the related art, the electrode sheet has poor affinity with the electrolyte and the electrode sheet has poor wettability, which slows down the rate at which the electrolyte diffuses from the surface of the active material layer to the inside of the active material layer, resulting in poor liquid absorption performance of the active material and deteriorating the cycle performance of the battery cell.

[0041] Therefore, in an embodiment of the present application, from the viewpoint of improving the liquid absorption rate of the active material layer, the material in the active material layer, such as an ether-based polymer, is improved to increase the liquid absorption rate, thereby improving the cycle performance of the battery cell.

[0042] Extreme Sheet

[0043] In a first aspect, the present application provides an electrode sheet including a current collector and an active material layer provided on at least one surface of the current collector, the active material layer including an active material and an ether-based polymer. The electrode sheet may be a positive electrode sheet and / or a negative electrode sheet, and correspondingly, the positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer, and the negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer.

[0044] The electrode sheet can be manufactured by applying the slurry to a current collector, drying it, and cold pressing it. Alternatively, the electrode sheet can be derived from a battery cell. The battery cell can be disassembled, and the electrode sheet wetted with the electrolyte can be removed from the battery cell and vacuum-dried at 100°C for 12 hours to obtain the electrode sheet, which can then be used for electrode sheet tests such as electrolyte absorption rate.

[0045] Ether-based polymers can be synthesized by emulsion polymerization, suspension polymerization, bulk polymerization, solution polymerization, etc. Alternatively, ether-based polymers can be derived from battery cells. The battery cells are disassembled, and the electrode sheets wetted with the electrolyte are removed. The active material of the electrode sheets is then removed from the current collectors by external force to form powder samples. These samples are then added to dimethyl carbonate (DMC) and stirred at 80°C for 8 hours at 500 rpm. After stirring, the mixture is allowed to stand at room temperature for 10 minutes. The supernatant is then removed at 80°C and dried for 12 hours to obtain the ether-based polymer. The resulting ether-based polymer may contain a small amount of lithium salt, but this does not substantially affect infrared and sedimentation value testing. To ensure the accuracy of the ether-based polymer, the lithium salt can be separated by further washing with DMC at room temperature.

[0046] The active material layer satisfies the following formula:

[0047]

number

[0048] In formulas (1) to (3), λ represents the porosity of the active material layer, P1 represents the actual compressed density of the active material layer, expressed in g / cm 3 and P2 represents the true compressed density of the active material, expressed in g / cm 3 and v represents the liquid absorption rate of the active material layer, and is expressed in mg / s. d represents the diameter of a capillary tube provided in the active material layer in a capillary test, and is expressed in mm; h represents the liquid level in the capillary test, and is expressed in mm. ρ indicates the density of the electrolyte in the capillary test, and its unit is g / cm 3 and t represents the time taken for the electrolyte in the capillary to be absorbed, and is expressed in s.

[0049] In this application, the actual compressed density P1 refers to the ratio of the mass to the thickness of the active material layer per unit area of ​​the electrode sheet, and is determined by the force applied to press the electrode sheet with a roll after coating, and is expressed in units of g / cm. 3 The specific measurement steps are to take a polar sheet with a certain area S, weigh the mass M of its active material layer, and take the thickness D of the active material layer, and the actual compressed density = M / (S × D).

[0050] In this application, the true compaction density P2 refers to the density of the active material itself in the active material layer, where the active material is a negative electrode active material, for example, graphite, and the density of graphite is 2.25 g / cm 3 and the true compressed density of the active material is 2.25 g / cm 3 is.

[0051] Taking the positive electrode active material as an example, this specifically refers to the mass per unit of the "actual volume of a solid material (not including open and closed pores and interparticle voids)" in a dense state, which is measured to obtain the true volume V, and then the true compressed density is calculated based on P = m / V, which can be measured with reference to GB / T24586-2009. Specifically, the measurement steps are as follows:

[0052] 1) Pretreatment: Place a clean, dry sample cup on the balance, perform zero clear, add the powder sample to the sample cup so that it occupies approximately half of the volume of the sample cup, and record the mass of the sample.

[0053] 2) Place the sample cup containing the sample into the true density measuring instrument, seal the measuring system, introduce helium gas according to the process, detect the gas pressure in the sample chamber and the expansion chamber, and then calculate the true volume based on Bohr's law (PV=nRT) to calculate the true compressed density.

[0054] Here, the volume of the sample cup is 3.5 cm 3 and the analysis gas is helium gas.

[0055] Formula (1) can calculate the porosity λ of the active material layer from the actual compressed density and the true compressed density. Specifically, it is as follows:

number

[0056] where V1 represents the volume of the active material layer with mass m, and is expressed in cm 3 and V2 represents the volume occupied by active material particles with mass m, expressed in cm 3 and m represents the mass of the active material layer, and is expressed in g.

[0057] Equation (2) can represent the rate at which a certain point on the polar sheet almost completely absorbs the liquid (e.g., electrolyte) in the capillary within a unit time. In this application, a certain point on the polar sheet refers to a region of the polar sheet having a certain area, which corresponds to the cross-sectional area of ​​the capillary.

[0058] In this application, the method for detecting the liquid absorption rate of a polar sheet includes the following steps:

[0059] A predetermined amount of electrolyte is absorbed using a capillary tube.

[0060] The capillary tube is brought into contact with the electrode sheet, and the electrode sheet to be measured absorbs the electrolyte in the capillary tube due to capillary action.

[0061] After a predetermined time t has passed, the height h of the electrolyte absorbed in the capillary is recorded, and the amount of electrolyte absorbed is calculated based on the height h of the electrolyte in the capillary, its diameter d, and the density ρ of the electrolyte. The liquid absorption rate v of the electrode sheet is quantitatively calculated based on the ratio of the amount absorbed to the predetermined time t.

[0062] Illustratively, the value of d is between 0.2 and 1, for example, 0.2, and the value of h is between 3 and 5, for example, 3.

[0063] The capillary tube has a capillary channel that allows it to directly draw in the electrolyte by capillary action, eliminating the need for an external driving means to provide suction power. This allows for more accurate control of the amount of electrolyte drawn in by capillary action. Meanwhile, the electrode sheet absorbs the electrolyte by its own capillary action. When the capillary tube comes into contact with the electrode sheet being measured, the electrode sheet draws in the electrolyte from inside the capillary tube. When the capillary tube is not in contact with the electrode sheet being measured, the electrolyte inside the capillary tube does not flow out. Therefore, the amount of electrolyte absorbed by the capillary tube can accurately reflect the corresponding volume of electrolyte absorbed by the electrode sheet, further improving the accuracy of the test results and enabling quantitative calculation of the absorption rate of the electrode sheet.

[0064] In the present application, the standard electrolyte solution is used as the test sample for the test, and the specific formulation of the electrolyte solution can be referred to in the examples.

[0065] Equation (3) shows the liquid absorption rate of the electrode sheet in terms of the porosity λ, and can express the liquid absorption rate of the electrode sheet.

[0066] The ether-based polymer of the present application is introduced into the manufacturing process of the active material layer, and can form uniformly high wetting points inside the active material layer, uniformly improving the wetting performance of the active material layer, improving the liquid absorption speed of the entire active material layer, and improving the cycle performance of a battery cell using the electrode sheet.

[0067] Optionally, 1.00 <v / λ<50.00である。

[0068] In some embodiments, the ether-based polymer is manufactured into a sheet-like structure, and the sheet-like structure obtains a storage modulus G'-loss modulus G" curve by a dynamic frequency scanning test at (T m +20)°C. The slope of the storage modulus G'-loss modulus G" curve is K, where 1 < K < ∞, 1 < K ≤ 100, and optionally, 1 < K ≤ 10. T m °C represents the melting temperature of the ether-based polymer.

[0069] Specifically, in the manufacturing process of the sheet-like structure, the polymer is vacuum dried at 80°C for 12 hours. The dried polymer is hot pressed into a sheet by a press vulcanizer, the hot pressing temperature is set to (T m +20)°C, the rolling thickness is 1 - 2 mm, the rolling time is 2 minutes, and the pressure is 8 MPa. After rolling for 2 minutes, the sample is taken out and cold pressed in another vulcanizer of the same model number. The cold pressing pressure is 10 MPa. Using a circular mold with a diameter of 25 mm, a polymer wafer (sheet-like structure) of a certain size is obtained. Exemplarily, the sheet-like structure may be a wafer with a thickness of 1 - 2 mm and a diameter of 25 mm, and it may also be manufactured according to the specifications of the sample required by the test device.

[0070] According to the conclusion of classical linear viscoelasticity, for polymers, especially linear polymers, in the terminal region (the range of the section approaching the maximum value of the angular velocity) of the storage modulus G'-loss modulus G" curve, the storage modulus G'-loss modulus G" satisfies frequency dependence, and the longest chain of the polymer plays a role in the viscoelastic behavior.

[0071] The specific steps of the dynamic frequency scanning test are to perform a dynamic frequency scanning test using a TA-AR2000EX rotational rheometer (TA instruments, USA). The diameter of the parallel plates is 25 mm, and the thickness is 0.9 mm. To ensure the test in the linear elastic region, the strain during the dynamic frequency scanning test is 2%, the test temperature is T m +20°C, and the frequency scanning range of the test is 500 rad / s ≤ ω 2 ≤ 0.05 rad / s, so that data in the lowest possible frequency region can be obtained.

[0072] Dynamic frequency sweep tests can indicate the degree of molecular chain entanglement in solid-state melting (molten state), and compared with linear or short-branched structures, long-branched structures, network structures, and low-crosslinked structures have a higher degree of entanglement, exhibiting behavior that deviates from the linear ends, and the polymer exhibits solid-state behavior. When the polymer of the present application satisfies the above range, the molecular chain entanglement can be further reduced, which is favorable for the diffusion of solvent molecules between molecular chains in the electrolyte, and the polymer still maintains a certain molecular chain entanglement state, allowing solvent molecules to be locked in situ inside the polymer, reducing the risk of the polymer dissolving in the electrolyte and improving the performance stability of the polymer. It is also favorable for the polymer to form a protective layer on the surface of the active material, improving solid-liquid interfacial performance, reducing side reactions between the active material and the electrolyte, and improving the cycle performance and storage performance of the battery cell.

[0073] In some embodiments, the glass transition temperature of the ether-based polymer is Tg, in ° C., where -100≦Tg≦50, and optionally, -80≦Tg≦30.

[0074] The glass transition temperature (Tg) is the transition temperature between the freezing and movement of the segments of an ether-based polymer. The Tg has a certain effect on the flexibility of the molecular chains of the ether-based polymer. The lower the Tg, the better the flexibility of the molecular chains of the ether-based polymer at room temperature. The higher the Tg, the worse the flexibility of the molecular chains at room temperature. The Tg can be measured using differential scanning calorimetry (DSC). Specifically, the measurement involves taking a 0.5g-0.8g sample, placing the sample in a crucible, and heating the sample under a nitrogen atmosphere at a heating rate of 10°C / min from an initial temperature 20°C lower than the intrinsic Tg of the material to a cutoff temperature 20°C higher than the intrinsic Tm of the material. The actual Tg and Tm of the material are determined based on the peak or transition point of the heat absorption and heat dissipation of the material during the process.

[0075] The ether-based polymer has a relatively low glass transition temperature, which allows the molecular chain segments to have better flexibility, allowing adjacent molecular chains to open more easily, and allowing an in-situ gel to be formed more easily, thereby improving the wetting of the electrolyte to the active material layer and thereby improving the cycle performance of the battery cell. For example, the glass transition temperature of the ether-based polymer may be −100° C., −90° C., −80° C., −60° C., −30° C., 0° C., 30° C., 50° C., or a range combining any two of the above values.

[0076] In some embodiments, the ether-based polymer comprises a structural unit represented by formula (I). [ka]

[0077] In formula (I), R1 and R2 each independently comprise a hydrogen atom, a substituted or unsubstituted C1-C3 alkyl group, or a substituted or unsubstituted C1-C3 alkoxy group; R3 comprises a substituted or unsubstituted C1-C5 methylene group; optionally, R1 and R2 each independently comprise a hydrogen atom, a substituted or unsubstituted C1-C2 alkyl group, and / or R3 comprises a single bond, a substituted or unsubstituted C1-C4 methylene group.

[0078] Illustratively, the ether-based polymer includes at least one of the structural units represented by formula (I-1) to formula (I-8). [ka]

[0079] In some embodiments, the ether-based polymer comprises a structural unit represented by formula (II). [ka]

[0080] In formula (II), R4 to R7 each independently comprise 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 R4 to R7 comprises a substituted or unsubstituted C1-C3 alkoxy group or ether group. Optionally, R4 to R7 each independently comprise a hydrogen atom, a substituted or unsubstituted C1-C2 alkyl group, a substituted or unsubstituted C1-C2 alkoxy group, or an ether group, and at least one of R4 to R7 comprises a substituted or unsubstituted C1-C2 alkoxy group or ether group.

[0081] In some embodiments, the ether-based polymer includes at least one of structural units represented by formula (II-1) through formula (II-7). [ka]

[0082] The monomers used in the above ether-based polymers are multi-membered rings, such as six-membered or less ring structures or short-chain monomers, which are advantageous for forming a high content of -O- structures upon polymerization. Such structural types have a low degree of entanglement, which is advantageous for improving the flexibility of the molecular chains, allowing the molecular chains to fully extend in the electrolyte, thereby further improving the interfacial performance of the active material.

[0083] 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.).

[0084] The groups of the polymer of the present invention can be detected by infrared spectroscopy (IR), specifically, the polymer is measured using a ThermoNicolet Nexus 670 attenuated total reflectance Fourier transform infrared spectrophotometer (FTIR-ATR), and then measured with reference to standard GB / T 6040-2002, with the measurement range of the ATR method being 600-4000 cm -1 and the overlap is ±2cm-1 and the resolution is 4cm -1 Better, the penetration depth is 0.2-0.6 μm.

[0085] The structure of the polymer of the present invention can be determined by nuclear magnetic resonance (NMR) measurement, specifically, 1H NMR and 13C NMR are performed using a Varian MercuryPlus-400 nuclear magnetic resonance spectrometer, the measurement temperature is 20°C, TMS is the internal standard, CDCl3 is the solvent, and the proton resonance frequency is 400 MHz.

[0086] The type of polymer monomer of the present invention (especially applicable to monomers that occupy a small proportion in the polymer) can be determined by decomposition gas chromatography mass spectrometry. The specific measurement steps are as follows: 0.5 mg of sample is accurately weighed and placed in a sample cup, which is then fixed to an injection rod and placed in a cracker installed near the GC (gas chromatograph) injection port; after the temperature of the cracker reaches the set temperature, the injection button is pressed, and the sample cup is quickly dropped into the core of the decomposition furnace; in the inert gas N2 atmosphere, the volatile components are instantly gasified and carried by the carrier gas into the gas chromatograph column for separation; and finally detected by a flame ionization detector FID or mass spectrometer, thereby obtaining a gas chromatograph or total ion flow diagram.

[0087] 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 carboxyl group, an ester group, and a halogen atom. The above substituents are high-pressure-resistant substituents and are advantageous for stabilizing the polymer structure. Examples of halogen atoms include fluorine atoms, chlorine atoms, and bromine atoms.

[0088] In some embodiments, n is selected from a positive integer between 1500 and 25000.

[0089] Optionally, n is selected from a positive integer between 3,000 and 18,000.

[0090] In some embodiments, the molecular weight of the polymer is 1.2×10 5 g / mol ~ 1.0 × 10 6 g / mol.

[0091] When the molecular weight of the polymer is within the above range, it is possible to ensure that the polymer exhibits a certain solubility in the electrolyte, and is less likely to be completely dissolved and dispersed by the electrolyte, which is advantageous for adjusting the distribution and dispersion of the polymer on the surface of the active material. In addition, the flexibility between the molecular chains of the polymer can be further improved, and the interaction between the molecular chains is relatively weak, which is advantageous for the solvent molecules in the electrolyte to open the molecular chains, enter between the molecular chains, and be enveloped by the molecular chains, which is advantageous for the active ions to enter the active material through the solvent, realizing smooth and rapid movement of the active ions. For example, 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 in the range of g / mol or a combination of any two of the above values.

[0092] The molecular weight of the ether polymer is a known meaning in this field, and can be measured using the devices and methods commonly used in this field, and can be measured by gel permeation chromatography (GPC). The specific measurement steps are as follows: take an appropriate amount of sample to be measured (ensure that the sample concentration is 8% to 12% and the light shielding degree is 8%), add 20 ml of deionized water, and apply external ultrasound for 5 minutes (53 KHz / 120 W) to ensure that the sample is completely dispersed, and then measure the sample in accordance with GB / T19077-2016 / ISO13320:2009 standard.

[0093] Alternatively, measurements are performed using a multi-angle light scattering instrument (MALLS), specifically, a GPC system using a DawnHeleos II multi-angle light scattering instrument, an OptilabT-rEX refractive index (RI) detector, and a ViscoStar II viscometer (Wyatt Technology Corporation, USA). Measurements are performed at 30°C with tetrahydrofuran as the mobile phase at a flow rate of 1.0 ml / min, and the SEC-SAMLL data are processed using the commercial software ASTRA6 to obtain molecular weight parameters.

[0094] If the ether-based polymer in the embodiments of the present disclosure further satisfies one or more of the following conditions, the cycle performance of the battery cell can be further improved.

[0095] In some embodiments, the ether-based polymer is added to a first solvent at 45° C. to form an ether-based polymer system, which is then subjected to a two-stage settling process, namely, at 45° C. for 8 hours and at 25° C. for 24 hours or more, whereby a portion or all of the ether-based polymer system is in-situ converted into a gel-state substance, and the ether-based polymer system is then filtered through a 200-mesh filter to leave a first substance. The mass of the ether-based polymer is n (g), the mass of the first substance is m (g), and the masses of the ether-based polymer and the first substance satisfy 5≦m / n≦1000, optionally 10≦m / n≦1000, and further 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 combining any two of the above values. Exemplarily, the ratio of the mass content of the ether-based polymer to the mass content of the first solvent, relative to the mass of the ether-based polymer system, ranges from 1:100 to 1:10, for example, 3:50. Exemplarily, the first solvent may be the same as or similar to the solvent of the electrolyte, and may include a carbonate-based solvent. For example, the carbonate-based solvent may include a cyclic carbonate solvent and / or a linear carbonate solvent.

[0096] Examples of cyclic carbonate solvents include at least one of ethylene carbonate EC, vinylene carbonate VC, fluoroethylene carbonate FEC, difluoroethylene carbonate DFEC, vinylethylene carbonate VEC, and dioctyl carbonate CC.

[0097] Examples of linear carbonate solvents include at least one of dimethyl carbonate DMC, diethyl carbonate DEC, ethyl methyl carbonate EMC, diphenyl carbonate DPC, methyl allyl carbonate MAC, and polycarbonate VA.

[0098] Alternatively, the first solvent may contain a lithium salt and an electrolyte additive, such as lithium hexafluorophosphate, vinylene carbonate (VC), or fluorovinylene carbonate (FEC).

[0099] In this application, m / n is also referred to as the precipitation value, and represents the ability of the ether-based polymer and solvent to convert into a gel-state material.

[0100] The first substance contains a gel-like substance mainly composed of an ether-based polymer and a first solvent, and in such a gel-like substance, the molecular structure of the ether-based polymer remains almost unchanged.

[0101] In some embodiments, the first substance is dried at 80°C for 12 hours to remove the first solvent in the first substance, and then infrared spectrophotometry (IR) or nuclear magnetic resonance (NMR) measurement is performed. The main component of the first substance after drying is the aforementioned ether-based polymer.

[0102] By improving the temperature, the present application can achieve the expansion of the ether-based polymer molecular chain within the safe operating temperature range of the battery cell, promote the mutual attraction and physical bonding between the ether-based polymer molecular chain and the solvent, and improve the liquid absorption capacity. At room temperature, the activity of the molecular segments of the ether-based polymer decreases, and it adheres to the surface of the active material to retain locking the electrolyte in the spatial environment where the ether-based polymer is located, forming a state similar to an in-situ gel, improving the liquid locking ability, and improving the cycle performance.

[0103] [Positive electrode sheet]

[0104] The positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer provided on at least one surface of the positive electrode current collector. The positive electrode active material layer includes a positive electrode active material and an ether-based polymer. In the present application, the ether-based polymer includes the aforementioned ether-based polymer.

[0105] For example, the positive electrode current collector has two surfaces facing each other in its own thickness direction, and the positive electrode active material layer is provided on either one or both of the two opposing surfaces of the positive electrode current collector.

[0106] In some embodiments, 1.00 < v / λ < 4.00, optionally, 1.20 ≤ v / λ ≤ 3.80, and further optionally, 1.4 ≤ v / λ ≤ 3.6. Exemplarily, v / λ may be 1.20, 1.40, 1.80, 2.00, 2.50, 3.00, 3.50, 3.60, 3.80, 3.90 or a range combined by any two of the above numerical values.

[0107] In some embodiments, with respect to the mass of the positive electrode active material layer, the mass percentage of the ether-based polymer is A%, and 0.1 ≤ A ≤ 1.5.

[0108] When the mass percentage of the ether-based polymer is in the above range, the liquid absorption capacity of the positive electrode active material layer can be significantly improved. For example, the mass percentage A% of the ether-based polymer may be 0.1%, 0.2%, 0.5%, 0.8%, 1.0%, 1.2%, 1.5%, or a range that combines any two of the above values.

[0109] The positive electrode active material layer includes a positive electrode active material, and the positive electrode active material may be a positive electrode active material for battery cells known in the art. For example, the positive electrode active material may include at least one of a layered positive electrode active material (e.g., a ternary material, a lithium / sodium nickelate, a lithium / sodium cobaltate, a lithium / sodium manganate, a lithium-rich / sodium layered material, and a rock salt layered material), an olivine-type phosphate active material, and a spinel-type positive electrode active material (e.g., a spinel lithium manganate, a spinel lithium nickel manganate, a lithium-rich spinel lithium manganate, and a lithium nickel manganate).

[0110] For example, the general formula of the layered positive electrode active material is Li x A y Ni a Co b Mn c M (1-a-b-c) Y z where 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 is one or more elements selected from Na, K, and Mg; M is one or more elements selected from 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 is one or more elements selected from 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 / 3O2(NCM333), LiNi 0.8 Co 0.1 Mn 0.1 O2(NCM811) and LiNi 0.5 Co 0.2 Mn 0.3 Contains one or more of the following: O2 (NCM523)

[0111] For example, the general formula of the olivine-type phosphate active material is Li x A y Me a M b P 1-c X c Y z wherein 0≦x≦1.3, 0≦y≦1.3, and 0.9≦x+y≦1.3; 0.9≦a≦1.5, 0≦b≦0.5, and 0.9≦a+b≦1.5; 0≦c≦0.5; and 3≦z≦5; A is one or more types selected from Na, K, and Mg; Me is one or more types selected from Mn, Fe, Co, and Ni; M is one or more types selected from 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 is one or more types selected from S, Si, Cl, B, C, and N; and Y is one or more types selected from O and F. Specifically, the olivine-type phosphate active material includes at least one or more of LiFePO4, LiMnPO4, LiNiPO4, and LiCoPO4.

[0112] For example, the general formula of the positive electrode active material with a spinel structure is Li x A y Mn a M 2-a Y zwhere 0≦x≦2, 0≦y≦1, and 0.9≦x+y≦2, 0.5≦a≦2, and 3≦z≦5; A is one or more elements selected from Na, K, and Mg; M is one or more elements selected from Ni, Co, B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Fe, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, and Ce; and Y is one or more elements selected from O and F. Specifically, the positive electrode active material having a spinel structure is LiMn2O4, LiNi 0.5 Mn 1.5 O4, LiCr 0.3 Mn 1.7 O4, Li 1.1 Al 0.1 Mn 1.9 O4, Li2Mn2O4 and Li 1.5 Mn2O4.

[0113] In some embodiments, the positive electrode current collector can be a metal foil or a composite current collector. Examples of the metal foil include aluminum foil and aluminum alloy foil. The composite current collector can 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 can include one or more combinations selected from aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy. The polymeric material base layer can include one or more combinations selected from polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0114] In some embodiments, the positive electrode active material layer optionally further includes a positive electrode conductive agent. In the present application, the type of positive electrode conductive agent is not particularly limited. For example, the positive electrode conductive agent may include one or a combination of two 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 of the total mass of the positive electrode active material layer.

[0115] In some embodiments, the positive electrode active material layer optionally further includes a positive electrode binder. The type of positive electrode binder is not particularly limited in the present application. For example, the positive electrode binder may include one or more combinations selected from polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluoroacrylate-based resin. In some embodiments, the mass percentage of the positive electrode binder is 5% or less relative to the total mass of the positive electrode active material layer. The crystallinity of the positive electrode binder is higher than that of the ether-based polymers described above in the present application, and the melting temperature of the positive electrode binder is higher than that of the ether-based polymers described above in the present application.

[0116] The positive electrode active material layer is typically formed by applying a positive electrode slurry to a positive electrode current collector, drying, and cold pressing. The positive electrode slurry is typically formed by dispersing the positive electrode active material, the ether-based polymer, an optional conductive agent, an optional positive electrode binder, and any other components in a solvent and stirring the mixture uniformly. The solvent may be, but is not limited to, N-methylpyrrolidone (NMP).

[0117] [Negative electrode sheet]

[0118] The negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer provided on at least one surface of the negative electrode current collector, and the negative electrode active material layer includes a negative electrode active material and an ether-based polymer. In the present application, the ether-based polymer includes the aforementioned ether-based polymer. For example, the negative electrode current collector has two surfaces facing each other in the thickness direction, and the negative electrode active material layer is provided on either one or both of the two opposing surfaces of the negative electrode current collector.

[0119] In some embodiments, 3.00 < v / λ < 50.00, and optionally, 3.40 ≤ v / λ ≤ 30.00. Exemplarily, v / λ may be 3.20, 3.40, 3.50, 4.00, 4.50, 5.00, 5.50, 6.00, 6.50, 7.00, 8.00, 9.00, 9.50, 10.00, 10.50, 11.00, 12.00, 13.00, 14.00 or a range combined by any two of the above numerical values.

[0120] In some embodiments, with respect to the mass of the negative electrode active material layer, the mass percentage of the ether-based polymer is B%, and 0.2 ≤ B ≤ 5.0. When the content of the ether-based polymer is within the above range, the liquid absorption capacity of the negative electrode active material layer can be significantly improved. Exemplarily, the mass percentage B% of the ether-based polymer may be 0.2%, 0.5%, 0.8%, 1.0%, 1.2%, 1.5%, 2.0%, 2.5%, 3.0%, 3.5%, 4.0%, 4.5%, 5.5% or a range combined by any two of the above numerical values.

[0121] In some embodiments, the negative electrode current collector can be a metal foil or a composite current collector. For example, copper foil can be used as the metal foil piece. The composite current collector can include a polymeric substrate and a metal layer formed on at least one surface of the polymeric substrate. The composite current collector can be formed by forming a metal material (such as copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, or silver alloy) on a polymeric substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), or polyethylene (PE)).

[0122] In some embodiments, the negative electrode active material may be a known battery negative electrode active material. For example, the negative electrode active material may include at least one of artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate. The silicon-based material may be at least one selected from silicon elemental, silicon-oxygen compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be at least one selected from tin elemental, tin-oxygen compounds, and tin alloys. The present application is not limited to these materials, and other conventional materials usable as battery negative electrode active materials may also be used. These negative electrode active materials may be used alone or in combination.

[0123] In some embodiments, the negative electrode active material layer optionally further comprises a negative electrode binder. The negative electrode binder may be at least one selected from styrene butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS). The crystallinity of the negative electrode binder is higher than that of the ether-based polymer described herein, and the melting temperature of the negative electrode binder is higher than that of the ether-based polymer described herein.

[0124] In some embodiments, the negative electrode active material layer optionally further includes a conductive agent, which may be at least one selected from the group consisting of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0125] In some embodiments, the negative electrode active material layer may optionally further include other auxiliary agents such as a thickener (eg, carboxymethylcellulose sodium (CMC-Na)).

[0126] In some embodiments, the components for producing the negative electrode sheet, such as the negative electrode active material, the ether-based polymer, the conductive agent, the negative electrode binder, and any other components, are dispersed in a solvent (e.g., deionized water) to form a negative electrode slurry, which is then applied to a negative electrode current collector, and the negative electrode sheet is obtained through processes such as drying and cold pressing, thereby producing a negative electrode sheet.

[0127] Battery cell

[0128] In a second aspect, the present application provides a battery cell including a positive electrode sheet, a negative electrode sheet, and a separator and an electrolyte disposed between the positive electrode sheet and the negative electrode sheet. The battery cell may be a lithium-ion battery or the like.

[0129] In some embodiments, the positive electrode sheet may be a positive electrode sheet according to any one of the first aspects of the present application, thereby improving the cycle performance of the battery cell. The negative electrode sheet may be a normal electrode sheet.

[0130] In some embodiments, the negative electrode sheet may be a negative electrode sheet according to any one of the first aspects of the present application, thereby improving the cycle performance of the battery cell. The positive electrode sheet may be a normal electrode sheet.

[0131] In some embodiments, the positive electrode sheet may be a positive electrode sheet according to any one of the embodiments of the first aspect of the present application, and the negative electrode sheet may be a negative electrode sheet according to any one of the embodiments of the first aspect of the present application, thereby improving the cycle performance of the battery cell.

[0132] [Electrolyte]

[0133] The battery cell further includes an electrolyte that serves to conduct ions between the positive electrode sheet and the negative electrode sheet. The present application does not specifically limit the type of electrolyte, and it can be selected as needed. The electrolyte may be, for example, liquid, gel, or all-solid.

[0134] In some embodiments, the electrolyte is an electrolytic solution, which includes an electrolyte salt and a solvent.

[0135] For example, the lithium salt may include one or a combination of two or more selected from the group consisting of lithium hexafluorophosphate (LiPF), lithium tetrafluoroborate (LiBF), lithium perchlorate (LiClO), lithium hexafluoroarsenate (LiAsF), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorooxalatoborate (LiDFOB), lithium bisoxalatoborate (LiBOB), lithium difluorophosphate (LiPOF), lithium difluorobis(oxalato)phosphate (LiDFOP), and lithium tetrafluoro(oxalato)phosphate (LiTFOP).

[0136] By way of example, the organic solvent may comprise one or a combination of more selected from the group consisting 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), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), methyl ethyl sulfone (EMS), and diethyl sulfone (ESE).

[0137] In some embodiments, the electrolyte solution further contains additives as needed. For example, the additives may include a negative electrode film-forming additive and a positive electrode film-forming additive, or may include additives that can improve certain battery performance, such as an additive that improves the overcharge performance of the battery or an additive that improves the high-temperature or low-temperature performance of the battery.

[0138] [Separator]

[0139] In some embodiments, the battery cell further includes a separator. In the present application, the type of separator is not particularly limited, and any known porous structure separator having good chemical stability and mechanical stability can be selected.

[0140] In some embodiments, the separator may be made of one or a combination of materials selected from glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may be a single-layer film or a multi-layer composite film. When the separator is a multi-layer composite film, the materials of each layer may be the same or different.

[0141] In some embodiments, the positive electrode sheet, separator, and negative electrode sheet can be wound or laminated to form an electrode assembly.

[0142] In the present invention, the shape of the battery cell is not particularly limited, and may be cylindrical, rectangular, or any other shape. Figure 1 shows a battery cell 5 with a rectangular structure as an example.

[0143] In some embodiments, as shown in FIGS. 1 and 2 , the exterior may include a housing 51 and a cover plate 53. The housing 51 may include a bottom plate and side plates connected to the bottom plate, which together form a storage cavity. The housing 51 has an opening communicating with the storage cavity, and the cover plate 53 covers the opening to seal the storage cavity. The positive electrode sheet, the negative electrode sheet, and the separator may be formed into an electrode assembly 52 by a winding process or a stacking process. The electrode assembly 52 is packaged in the storage cavity. The electrolyte is impregnated into the electrode body 52. ​​The number of electrode assemblies 52 included in the battery cell 5 may be one or more and can be adjusted as needed.

[0144] The manufacturing method of the battery cell of the present application is known. In some embodiments, a battery cell can be formed by assembling a positive electrode sheet, a separator, a negative electrode sheet, and an electrolyte. For example, the positive electrode sheet, the separator, and the negative electrode sheet can be formed into an electrode assembly by a winding process or a lamination process, and the electrode assembly can be placed in a housing. After drying, the electrode assembly can be infused with an electrolyte, and the battery cell can be obtained through processes such as vacuum sealing, standing, chemical conversion, and shaping.

[0145] In some embodiments of the present application, the battery cells of the present application may be assembled into a battery module, and the number of battery cells included in the battery module may be multiple, and the specific number may be adjusted according to the application and capacity of the battery module.

[0146] Fig. 3 is a schematic diagram of an example battery module 4. As shown in Fig. 3, in the battery module 4, the plurality of battery cells 5 may be arranged in order along the longitudinal direction of the battery module 4. Of course, they may be arranged in any other manner. Furthermore, the plurality of battery cells 5 may be fixed by fasteners.

[0147] Optionally, the battery module 4 may further include a housing having an accommodating space in which the plurality of battery cells 5 are accommodated.

[0148] 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 depending on the application and capacity of the battery pack. FIGS. 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 box and multiple battery modules 4 provided in the battery box. The battery box includes an upper housing 2 and a lower housing 3, and the upper housing 2 covers the lower housing 3 to form a sealed space for accommodating the battery modules 4. The multiple battery modules 4 may be arranged in the battery box in any manner.

[0149] Both the battery module and the battery pack can be examples of the battery of the present application.

[0150] power consumption equipment

[0151] According to a third aspect, the present application provides a power-using device including at least one of the battery cells, battery modules, and battery packs of the present application. The battery cells, battery modules, and battery packs may be used as a power source for a power-consuming device or as an energy storage means for the power-consuming device. The power-consuming 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.), a train, a ship, a satellite, an energy storage system, etc.

[0152] A power consuming 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 power consuming device. The power consuming device 6 may be a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, or the like. To meet the high power and high energy density requirements of the power consuming device, a battery pack 1 or a battery module may be adopted. Other examples of power consuming devices include mobile phones, tablet computers, and laptops. The power consuming device is usually required to be thin, and a battery cell may be adopted as a power source.

[0153] Example

[0154] The following examples of the present application are described. The examples described below are illustrative and are intended to illustrate the present application only and should not be construed as limiting the present application. In the examples, specific techniques or conditions are not specified, but are carried out according to the techniques or conditions described in the literature in this field or according to the product specifications. The reagents or equipment used are not specified by manufacturer, and are all ordinary products that are commercially available.

[0155] Example 1

[0156] (1) Manufacturing of positive electrode sheets

[0157] As the positive electrode current collector, an aluminum foil having a thickness of 12 μm is used.

[0158] A positive electrode slurry was prepared using an ether-based polymer, LiFePO4 (positive electrode active material), carbon black (conductive agent), polyvinylidene fluoride (PVDF) (binder), and N-methylpyrrolidone (NMP). The mass ratio of the ether-based polymer, LiFePO4, conductive carbon black, PVDF, and N-methylpyrrolidone (NMP) in the positive electrode slurry was 0.5:96.8:2:0.7:29. The positive electrode slurry was applied to an aluminum foil current collector, dried at 85°C, cold-pressed, trimmed, cut, and stripped, and then dried in a vacuum at 85°C for 4 hours to produce a positive electrode sheet.

[0159] (2) Manufacturing of negative electrode sheets

[0160] A copper foil with a thickness of 8 μm is used as the negative electrode current collector.

[0161] The negative electrode slurry is prepared by uniformly mixing an ether polymer, artificial graphite as the negative electrode active material, carbon black as the conductive agent, styrene butadiene rubber (SBR) as the binder, sodium hydroxymethylcellulose (CMC) as the thickener, and deionized water in a weight ratio of 2.5:94:0.5:2:1:100. The negative electrode slurry is applied to a copper foil current collector and dried at 85°C. After that, it is cold pressed, trimmed, cut, and stripped, and then dried in a vacuum at 120°C for 12 hours to produce a negative electrode sheet.

[0162] (3) Preparation of electrolyte

[0163] In an environment with a water content of less than 10 ppm, non-aqueous organic solvents ethylene carbonate (EC) and ethyl methyl carbonate (EMC) are mixed in a volume ratio of 3:7 to obtain an electrolyte solvent, and then the resulting solvent is mixed with lithium salt LiPF6 to prepare an electrolyte with a lithium salt concentration of 1 mol / L.

[0164] (4) Lithium-ion battery manufacturing

[0165] A 16 μm polyethylene film (PE) was used as the separator. The positive electrode sheet, separator, and negative electrode sheet were stacked in this order, with the separator positioned between the positive and negative electrode sheets to provide isolation, and then wound to obtain an electrode assembly. The electrode assembly was placed in an outer case, dried, and then injected with electrolyte. The lithium-ion battery was then produced through processes such as vacuum sealing, standing, chemical conversion, and shaping.

[0166] Comparative Example 1

[0167] A lithium ion battery was manufactured in a manner similar to that of Example 1, except that no ether-based polymer was added to the positive electrode sheet of Comparative Example 1, and no ether-based polymer was added to the negative electrode sheet of Comparative Example 1.

[0168] Comparative Example 2

[0169] A lithium ion battery was manufactured in a similar manner to Example 1, except that the positive electrode sheet and the negative electrode sheet of Comparative Example 2 were made of ether-based polymer.

[0170] Examples 2 to 4

[0171] Lithium ion batteries were manufactured in a similar manner to Example 1, but differed from Example 1 in that the positive electrode sheet and negative electrode sheet of Examples 2 to 4 were made of an ether-based polymer.

[0172] Example 5

[0173] A lithium ion battery was manufactured in the same manner as in Example 1, but differed from Example 1 in that an ether-based polymer was added to the positive electrode sheet of Example 5, and no ether-based polymer was added to the negative electrode sheet of Example 5.

[0174] Examples 6 to 9

[0175] Lithium ion batteries were produced in a similar manner to Example 1, but differed from Example 1 in that the content of the ether-based polymer in the positive electrode sheet of Examples 6 to 9 was adjusted.

[0176] Examples 10 to 12

[0177] Lithium ion batteries were produced in the same manner as in Example 1, except that the content of the ether-based polymer in the negative electrode sheet of Examples 10 to 12 was adjusted.

[0178] The data for the examples and comparative examples are shown in Table 1.

[0179] Testing part

[0180] 1. Capacity retention rate test for lithium-ion batteries

[0181] The lithium-ion batteries manufactured in the examples and comparative examples were charged at a constant current of 1 C to 4.25 V in a 45°C environment, then charged at a constant voltage of 0.05 C at 4.25 V, left for 5 minutes, and then discharged at 1 C to 2.8 V. The resulting capacity was designated as the initial capacity, C0. The same batteries were repeatedly charged, and the discharge capacity, Cn, after the nth cycle was recorded. The battery capacity retention rate after each cycle, Pn, was calculated as Cn / C0 × 100%. The 1200 points, P1, P2, ..., P1200, were plotted as the ordinate and the corresponding cycle number as the abscissa, to obtain a dot graph of battery capacity retention rate versus cycle number. In this test, the first cycle corresponds to n=1, the second cycle to n=2, ..., and the 1200th cycle to n=1200. For example, the battery capacity retention rate data for Example 1 in Table 1 is the data measured after 1200 repetitions under the above test conditions, i.e., the P1200 value. The test procedures for Comparative Example 1 and the other Examples are the same as those described above.

[0182] 2. DC impedance test of lithium-ion batteries

[0183] The lithium-ion batteries prepared in the examples and comparative examples were charged at a constant current of 1C to 4.25V at 45°C, then charged at a constant voltage of 0.05C at 4.25V, and allowed to stand for 5 minutes. The voltage V1 was recorded. The batteries were then discharged at 1C for 30 seconds, and the voltage V2 was recorded. This voltage, V2 = (V2 - V1) / 1 / 3C, yielding the battery's internal resistance (DCR1) after the first cycle. The same battery was then subjected to the same procedure, recording its internal resistance (DCRn) at the nth cycle (n = 1, 2, 3, . . . , 1200). The 1200 values ​​(DCR1, DCR2, DCR3, . . . , DCR1200) were plotted on the ordinate and the corresponding cycle number on the abscissa, yielding a graph of battery discharge DCIR versus cycle number for the ether-based polymers of the examples and comparative examples. In this test process, the first cycle corresponds to n=1, the second cycle corresponds to n=2, ..., and the 1200th cycle corresponds to n=1200. For example, the increase rate of the internal resistance of the battery of Example 1 in Table 1 is (DCRn-DCR1) / DCR1×100%, and the test process of Comparative Example 1 and other Examples is the same as above. The data in Table 1 was measured after 1200 repetitions under the above test conditions.

[0184] Test results

[0185] [Table 1]

[0186] In Table 1, 100% ethylene oxide means that the mass percentage of ethylene oxide relative to the total mass of Monomer 1 and Monomer 2 is 100%.

[0187] 80% ethylene oxide means that the weight percentage of ethylene oxide is 80% based on the combined weight of Monomer 1 and Monomer 2, and 20% 2-ethylethylene oxide means that the weight percentage of 2-ethylethylene oxide is 20% based on the combined weight of Monomer 1 and Monomer 2.

[0188] As can be seen from Table 1, compared to Comparative Example 1, in the Examples of the present application, by adding the ether-based polymer of the present application to the positive electrode sheet and / or negative electrode sheet, the ether-based polymer can form uniformly high wetting points inside the active material layer, uniformly improving the wetting performance of the active material layer, improving the liquid absorption rate of the entire active material layer, and improving the cycle performance of the battery cell using the electrode sheet.

[0189] Compared with Comparative Example 2, the Examples of the present application can more significantly improve the cycle performance of lithium ion batteries when v / λ>1 is satisfied.

[0190] Although the present invention has been described in detail with reference to the above-mentioned embodiments, various modifications may be made or equivalents may be substituted without departing from the scope of the present application. In particular, the technical features described in the embodiments may be combined in any manner as long as there is no structural contradiction. The present application is not limited to the specific embodiments disclosed herein, but includes all technical means falling within the scope of the claims. [Explanation of symbols]

[0191] 1 battery pack, 2 upper housing, 3 lower housing, 4 battery module, 5 battery cell, 51 housing, 52 electrode assembly, 53 cover plate, 6 power consumption device.

Claims

1. A polar sheet, a current collector; and an active material layer provided on at least one surface of the current collector, the active material layer including an active material and an ether-based polymer, the active material layer satisfying formulas (1) to (3), [Equation 1] In formulas (1) to (3), λ represents the porosity of the active material layer, P １ indicates the actual compressed density of the active material layer, and its unit is g / cm ３ and P ２ indicates the true compressed density of the active material, and its unit is g / cm ３ and v represents the liquid absorption rate of the active material layer, and is expressed in mg / s. d represents the diameter of a capillary tube provided in the active material layer in a capillary test, and is expressed in mm; h represents the liquid level in the capillary tube, and is expressed in mm; ρ indicates the density of the electrolyte in the capillary test, and its unit is g / cm ３ and t represents the time it takes for the electrolyte to be absorbed in the capillary, and is expressed in s; Extreme sheet.

2. the active material includes a positive electrode active material, the active material layer satisfies 1.00<v / λ<4.00, and optionally satisfies 1.20≦v / λ≦3.80; The electrode sheet according to claim 1 .

3. the active material includes a positive electrode active material, the mass percentage of the ether-based polymer relative to the mass of the active material layer is A %, However, 0.1≦A≦1.

5. The electrode sheet according to claim 1 or 2.

4. the active material includes a negative electrode active material, The active material layer satisfies 3.00<v / λ<50.00, and optionally satisfies 3.40≦v / λ≦30.

00. The electrode sheet according to claim 1 .

5. the active material includes a negative electrode active material, the mass percentage of the ether-based polymer relative to the mass of the active material layer is B %, However, 0.2≦B≦5.

0. The electrode sheet according to claim 1 or 4.

6. producing a sheet-like structure using the ether-based polymer; The sheet-like structure is (T ｍ +20°C, a dynamic frequency scan test is performed to obtain a G'-G" curve, the slope of the G'-G" curve is K, where 1<K<∞, optionally 1<K≦100, and further optionally 1<K≦10; T ｍ ° C. indicates the melting temperature of the ether-based polymer; The electrode sheet according to any one of claims 1 to 5.

7. The glass transition temperature of the ether-based polymer is Tg, expressed in ° C., and is −100≦Tg≦50, and optionally −80≦Tg≦30; The electrode sheet according to any one of claims 1 to 6.

8. The ether-based polymer contains a structural unit represented by formula (I): 【Chemical 1】 In formula (I), R １ and R ２ each independently contains a hydrogen atom, a substituted or unsubstituted C1 to C3 alkyl group, or a substituted or unsubstituted C1 to C3 alkoxy group, and R ３ comprises a substituted or unsubstituted C1-C5 methylene group; Optionally, R １ and R ２ each independently contain a hydrogen atom, a substituted or unsubstituted C1-C2 alkyl group, and / or R ３ includes a single bond, a substituted or unsubstituted C1-C4 methylene group; The electrode sheet according to any one of claims 1 to 7.

9. The ether-based polymer contains at least one structural unit selected from the structural units represented by formulas (I-1) to (I-8), 【Chemistry 2】 The electrode sheet according to claim 8.

10. The ether-based polymer contains a structural unit represented by formula (II), 【Chemistry 3】 In formula (II), R ４ -R ７ each independently contains 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 ４ ~R ７ at least one of comprises a substituted or unsubstituted C1-C3 alkoxy group or ether group; Optionally, R ４ ~R ７ 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 ４ ~R ７ at least one of which contains a substituted or unsubstituted C1-C2 alkoxy or ether group; The electrode sheet according to any one of claims 1 to 9.

11. The ether-based polymer contains at least one structural unit selected from the structural units represented by formulas (II-1) to (II-7), 【Chemistry 4】 The polar sheet according to claim 10.

12. n is selected from a positive integer between 1500 and 25000, and / or The molecular weight of the ether polymer is 1.2×10 ５ g / mol to 1.0×10 ６ g / mol or less, 12. The electrode sheet according to any one of claims 8 to 11.

13. A battery cell comprising the electrode sheet according to any one of claims 1 to 12.

14. A battery comprising the battery cell of claim 13.

15. 15. A power consuming device comprising the battery of claim 14.

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