Electrode sheet and related battery cells, 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 aldehyde ketone polymer. The active material layer satisfies the following formulas (1) to (3). The aldehyde ketone polymer, as a constituent of the active material layer, forms uniform high-wet points within the active material layer, uniformly improving the wetting performance of the active material layer and increasing the liquid absorption rate of the entire active material layer, thereby improving the cycle performance of the battery cell. JPEG2025530786000020.jpg37161

Description

[Technical Field]

[0001] The present application relates to the field of batteries, and in particular to electrode 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 cars, electric toy boats, electric toy airplanes, and power tools.

[0003] As the range of battery applications expands, the requirements for battery cell performance are also becoming increasingly stringent. To improve the safety performance of battery cells, it is common to optimize the performance of electrode sheets in battery cells. However, the active materials in current electrode sheets have poor liquid absorption properties, which results in poor cycle performance when used in battery cells. Summary of the Invention

[0004] The present application has been made in view of the above-mentioned problems, and its purpose is to provide an electrode sheet and a related battery cell, battery, and power consuming device.

[0005] A first aspect of the present application provides an electrode sheet, the 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 contains an active material and an aldehyde ketone polymer, and the active material layer satisfies the following formulas (1) to (3): JPEG2025530786000002.jpg37161In equations (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 compressed density of the active material, and its unit is g / cm3 and v represents the liquid absorption rate of the active material layer, and its unit is mg / s, d represents the diameter of the capillary in the capillary test of the active material layer, and its unit is mm, h represents the height of the liquid surface in the capillary, and its unit is mm, ρ represents the density of the electrolyte in the capillary test, and its unit is g / cm 3 and t represents the time during which the electrolyte is absorbed in the capillary, and its unit is s.

[0006] Thus, the aldehyde-ketone polymer of the present application can be introduced into the manufacturing process of the active material layer to form a uniform high wettability 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.

[0007] In some embodiments, the active material includes a positive electrode active material, and the active material layer satisfies 1.00 < v / λ < 4.00, preferably 1.20 ≤ v / λ ≤ 3.80.

[0008] <� In some embodiments, the active material includes a positive electrode active material, and based on the mass of the active material layer, the mass percentage of the aldehyde-ketone polymer is A%, and 0.1 ≤ A ≤ 1.5. When the mass percentage of the aldehyde-ketone polymer is within the above range, the liquid absorption capacity of the positive electrode active material layer can be significantly improved.

[0009] In some embodiments, the active material includes a negative electrode active material, and the active material layer satisfies 3.00 < v / λ < 50.00, preferably 3.40 ≤ v / λ ≤ 30.00.

[0010] In some embodiments, the active material includes a negative electrode active material, and the mass percentage of the aldehyde ketone polymer is B%, based on the mass of the active material layer, and 0.2≦B≦5.0 When the mass percentage of the aldehyde ketone polymer is in the above range, the liquid absorption capacity of the negative electrode active material layer can be significantly improved.

[0011] In some embodiments, the aldehyde ketone polymer is prepared as a sheet-like structure, and the sheet-like structure is subjected to a (T m A dynamic frequency scan test is performed at 20°C (+20°C) to obtain a G'-G'' curve, and the slope K of the G'-G'' curve is 0.8≦K<∞, preferably 0.8≦K≦100, and more preferably 0.8≦K≦10. m °C indicates the melting temperature of the aldehyde ketone polymer.

[0012] Therefore, when the polymer of the present application satisfies the above range, the entanglement state between molecular chains is further reduced, facilitating the diffusion of solvent molecules in the electrolyte between the molecular chains. Furthermore, since the polymer still maintains a certain degree of entanglement between molecular chains, it can lock the solvent molecules in situ within the polymer, reducing the risk of the polymer being dissolved in the electrolyte and improving the stability of the polymer's performance. Furthermore, the polymer contributes to forming a protective layer on the surface of the active material, improving the performance of the solid-liquid interface, suppressing side reactions 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 Tg of the aldehyde ketone polymer is −100≦Tg≦50, expressed in °C, and preferably −80≦Tg≦30. The aldehyde ketone polymer has a relatively low glass transition temperature, which allows the molecular chain segments to have better flexibility, adjacent molecular chains to open more easily, and allows in-situ gel formation to occur more easily, thereby improving the infiltration of the electrolyte into the active material layer and improving the cycle performance of the battery cell.

[0014] In some embodiments, the aldehyde ketone polymer comprises a structural unit shown in formula (I): [ka] In formula (I), R1 includes a single bond or a substituted or unsubstituted C1-C6 methylene group, and R2 includes a hydrogen atom or a substituted or unsubstituted C1-C6 alkyl group, and preferably, R1 includes a single bond or a substituted or unsubstituted C1-C2 methylene group, and R2 includes a hydrogen atom or a substituted or unsubstituted C1-C3 alkyl group.

[0015] In some embodiments, the aldehyde ketone polymer comprises at least one structural unit represented by formula (I-1) through formula (I-6): [ka]

[0016] In some embodiments, the aldehyde ketone polymer comprises a structural unit shown in formula (II): [ka] In formula (II), R3 to R6 each independently comprise a hydrogen atom, a hydroxyl 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; r and s each independently comprise an integer of 0 to 5, and at least one of r and s is selected from a positive integer; Preferably, R3 to R6 each independently comprise a hydrogen atom, a hydroxyl 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.

[0017] In some embodiments, the aldehyde ketone polymer comprises at least one structural unit represented by formula (II-1) through formula (II-4): [ka]

[0018] In some embodiments, n is selected from a positive integer between 500 and 15,000, and / or the molecular weight of the aldehyde ketone polymer is 1.2×10 5 g / mol ~ 1.0 × 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 completely dissolved or dispersed in the electrolyte, which is advantageous for adjusting the distribution and dispersion of the polymer on the surface of the active material, and it can further improve the flexibility of the polymer molecular chains, and the interaction force between the molecular chains is relatively weak, which is advantageous for the solvent molecules in the electrolyte to open the molecular chains and enter between them to be enveloped by them, which is advantageous for the active ions to enter the active material through the solvent and realize the smooth and rapid movement of the active ions.

[0019] A second aspect of the present application provides a battery cell including the electrode sheet according to any of the embodiments of the first aspect of the present application.

[0020] A third aspect of the present application provides a battery including the battery cell according to the second aspect of the present application.

[0021] A fourth aspect of the present application provides a power consuming device including a battery according to the third aspect of the present application. In order to more clearly explain the technical solutions of the embodiments of the present application, the following briefly introduces the drawings required in 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 obtain other drawings based on the drawings without any creative efforts. [Brief explanation of the drawings]

[0022] [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. The drawings are not necessarily drawn to scale. DETAILED DESCRIPTION OF THE INVENTION

[0023] Hereinafter, embodiments specifically disclosing the electrode sheet and the associated battery cell, battery, and power consumption device of the present application will be described in detail. However, unnecessary detailed description may be omitted. For example, detailed description of well-known matters or redundant description 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.

[0024] The "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 endpoints, 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 represented by the abbreviation 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 included herein, and "0 to 5" is an abbreviation for combinations of these numerical values. Furthermore, expressing a parameter as 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.

[0025] Unless otherwise specified, all embodiments and optional embodiments of the present application may be combined with each other to form a new technical solution. Unless otherwise specified, all technical features and optional technical features of the present application may be combined with each other to form a new technical solution.

[0026] Unless otherwise specified, all steps in this application may be performed in order or randomly, but are preferably performed in order. For example, a method including steps (a) and (b) may mean that the method includes steps (a) and (b) performed in order, or that the method includes 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.

[0027] Unless otherwise specified, the terms "comprise" and "include" used in this application mean open-ended and may also be closed-ended. For example, "comprise" and "include" can mean further "comprising" or "including" other unlisted components, or "comprising" or "including" only the listed components.

[0028] 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 conditions are met for "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).

[0029] In this application, the terms "plurality" and "plural types" mean two or more than two.

[0030] The term "alkyl group" encompasses straight-chain and branched 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. The alkyl group may also be optionally substituted. When substituted, the substituent may include a fluorine atom.

[0031] The term "alkoxy group" refers to a group in which an alkyl group and an oxygen atom are connected 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. In addition, the alkoxy group may be optionally substituted.

[0032] The term "hydroxyalkyl group" refers to a group in which a hydroxyl 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 a hydroxymethyl group, a hydroxyethyl group, a hydroxypropyl group, a hydroxybutyl group, etc. Furthermore, the hydroxyalkyl group may be optionally substituted.

[0033] The term "halogen atom" means a fluorine atom, a chlorine atom, a bromine atom, and the like.

[0034] The term "hydrogen" refers to 1H (protium, H), 2H (deuterium, D), or 3H (tritium, T). In each embodiment, "hydrogen" may be 1H (protium, H).

[0035] The battery cell includes an electrode assembly and an electrolyte, and the electrode assembly includes a positive electrode sheet, a negative electrode sheet, and a separator disposed between the positive and negative electrode sheets. The electrode assembly has a gap-pore structure, and the electrolyte infiltrates into the electrode assembly. The driving force for infiltration is mainly capillary force, which is a spontaneous infiltration process. The current collector barrier in the electrode sheet allows the electrolyte to infiltrate from the end face of the electrode assembly through the separator into the electrode assembly. The gaps between the layers of the electrode assembly act as a current guide, and the separator acts as a current divider. The steps in which the electrolyte solution permeates the interior of the electrode assembly include: (1) the electrolyte solution is transported between the electrode sheet and the separator by capillary force; (2) the electrolyte solution preferentially permeates into the pores of the separator (the permeation rate of the electrolyte solution in the separator is much faster than that in the active material layer of the electrode sheet); and (3) the electrolyte solution diffuses through the separator to the surfaces of the positive and negative electrode sheets on both sides and permeates into the pores of the active material layer.

[0036] In the related art, the affinity between the electrode sheet and the electrolyte is poor, the wettability of the electrode sheet is poor, the diffusion rate of the electrolyte from the surface of the active material layer to the inside of the active material layer is slow, and the liquid absorption performance of the active material is poor, which results in a deterioration of the cycle performance of the battery cell.

[0037] Therefore, in an embodiment of the present application, from the viewpoint of improving the liquid absorption rate of the active material layer, it is expected that the material in the active material layer, for example, an aldehyde ketone polymer, is improved to increase the liquid absorption rate and thereby improve the cycle performance of the battery cell. Electrode sheet

[0038] According to a first aspect, there is provided 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 aldehyde ketone polymer. The electrode sheet may be a positive electrode sheet and / or a negative electrode sheet, and accordingly, 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.

[0039] The electrode sheet may be obtained by applying the slurry to a current collector, drying the slurry, and cold-pressing the slurry. Alternatively, the electrode sheet may be derived from a battery cell, and the battery cell may be disassembled, and the electrode sheet soaked in the electrolyte may be removed from the battery cell and vacuum-dried at 100°C for 12 hours to obtain the electrode sheet, which may then be used for electrode sheet tests such as liquid absorption rate.

[0040] Aldehyde ketone polymers can be synthesized by emulsion polymerization, suspension polymerization, bulk polymerization, solution polymerization, and other methods. Alternatively, if the aldehyde ketone polymer is derived from a battery cell, the battery cell is disassembled, and the electrode sheet soaked in the electrolyte is removed. The active material of the resulting electrode sheet is peeled from the current collector by external force to form a powder sample. This powder is then added to dimethyl carbonate (DMC) and stirred at 500 rpm for 8 hours at 80°C. After stirring is complete, the mixture is allowed to stand at room temperature for 10 minutes. The supernatant is then removed and dried at 80°C for 12 hours to obtain the aldehyde ketone polymer. The resulting aldehyde ketone polymer may contain a small amount of lithium salt, but this does not generally affect infrared testing or precipitation value testing. To ensure the accuracy of the aldehyde ketone polymer, the lithium salt can be separated by further washing at room temperature with DMC.

[0041] The active material layer satisfies the following formulas (1) to (3). JPEG2025530786000007.jpg37161In equations (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 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 its unit is mg / s, d represents the diameter of the capillary in a capillary test of the active material layer, and its unit is mm; h represents the height of the liquid surface in the capillary, and its unit is mm; ρ indicates the density of the electrolyte in the capillary test, and its unit is g / cm 3 and t indicates the time it takes for the electrolyte to be absorbed in the capillary, and its unit is s.

[0042] In the present application, the actual compressed density P1 is 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 with which the electrode sheet is roll-pressed after being coated, and its unit is g / cm. 3 The specific test steps are to take an electrode sheet with a certain area S, weigh the mass M of its active material layer, and measure the thickness D of the active material layer, and the actual compressed density is M / (S×D).

[0043] In the present application, the true compressed density P2 refers to the density of the active material itself in the active material layer. For example, if the active material is a negative electrode active material, such as graphite, 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.

[0044] Taking a positive electrode active material as an example, this specifically means taking a mass of a certain "actual volume of the solid material (not including open pores, closed pores, and interparticle pores)" in a compacted state, obtaining the true volume V through testing, and then determining the true compressed density based on P = m / V, which can be tested in accordance with GB / T24586-2009. Specifically, the test steps are as follows:

[0045] 1) Pretreatment: Place a clean, dry sample cup on the balance, clear it, and add the powder sample to the sample cup, occupying approximately half of the sample cup volume. Record the mass of the sample.

[0046] 2) Place the sample cup containing the sample in the true density tester, seal the test system, and use the program to infuse helium gas into the test cup, 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.

[0047] Here, the volume of the sample cup is 3.5 cm 3 ,Analysis gas: Helium gas.

[0048] In formula (1), the porosity λ of the active material layer can be calculated from the actual compressed density and the true compressed density.

[0049] in particular, JPEG2025530786000008.jpg7114

[0050] Here, V1 represents the volume of the active material layer per mass m, and its unit is cm 3 and V2 represents the volume occupied by the active material particles in the active material layer at mass m, and its unit is cm 3 is. m represents the mass of the active material layer, and its unit is g.

[0051] Equation (2) can express the rate at which a certain point on the electrode sheet almost completely absorbs the liquid (e.g., electrolyte) in the capillary within a unit time. In this application, the certain point on the electrode sheet is a region of the electrode sheet having a certain area, which corresponds to the cross-sectional area of ​​the capillary.

[0052] In the present application, the method for detecting the liquid absorption rate of the electrode sheet includes: Adsorbing a predetermined amount of electrolyte with the capillary; The capillary is brought into contact with the electrode sheet, and the test electrode sheet absorbs the electrolyte in the capillary by capillary action. After a predetermined time t has elapsed, the height h of the electrolyte absorbed in the capillary is recorded, the amount of the electrolyte absorbed is calculated based on the height h of the electrolyte level and diameter d of the capillary and the density ρ of the electrolyte, and the liquid absorption rate v of the electrode sheet is quantitatively calculated based on the ratio of the amount of the electrolyte absorbed to the predetermined time length t.

[0053] 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.

[0054] The capillaries have capillary channels that allow them to directly adsorb the electrolyte by capillary action without requiring an external drive unit to provide suction. In this way, the amount of electrolyte adsorbed can be more accurately controlled when adsorbing by capillary action. Meanwhile, the electrode sheet absorbs the electrolyte by its own capillary action. When the capillaries are in contact with the electrode sheet to be tested, the electrode sheet draws out the electrolyte from the capillaries, and when they are not in contact, the electrolyte in the capillaries does not flow out. This allows the amount of electrolyte absorbed by the capillaries to accurately indicate that the electrode sheet has absorbed a corresponding volume of electrolyte, further improving the accuracy of the test results and enabling quantitative calculation of the absorption rate of the electrode sheet.

[0055] In the present application, the standard electrolyte solution is used as the test sample for the test, and the specific components of the electrolyte solution can be referred to in the examples.

[0056] Equation (3) shows the liquid absorption rate of the electrode sheet at a porosity λ and can be used to express the liquid absorption rate of the electrode sheet.

[0057] The aldehyde ketone polymer of the present application, when introduced during the manufacturing process of the active material layer, forms uniform high infiltration points inside the active material layer, uniformly improves the infiltration performance of the active material layer, increases the liquid absorption rate of the entire active material layer, and improves the cycle performance of a battery cell using the electrode sheet.

[0058] Preferably, 1.00 <v / λ<50.00である。

[0059] In some embodiments, the aldehyde ketone polymer is prepared as a sheet-like structure, and a dynamic frequency scan test is performed on the sheet-like structure at (Tm+20)°C to obtain a G'-G" curve, where the slope K of the G'-G" curve is 0.8≦K<∞, 0.8≦K≦100, and preferably 0.8≦K≦10. Tm°C indicates the melting temperature of the aldehyde ketone polymer.

[0060] Specifically, the manufacturing process for the sheet-like structure is as follows: The polymer is vacuum-dried at 80°C for 12 hours. The dried polymer is hot-rolled into a sheet in a flat vulcanizer, where the hot-rolling temperature is set to (Tm+20)°C, the rolling thickness is 1-2 min, the rolling time is 2 min, and the pressure is 8 MPa. After rolling for 2 min, the sample is removed and placed in another vulcanizer of the same model for cold rolling, where the cold-rolling pressure is 10 MPa. A circular die with a diameter of 25 mm is used to obtain a polymer wafer (sheet-like structure) of a certain size. For example, the sheet-like structure may be a wafer with a thickness of 1-2 mm and a diameter of 25 mm, but samples may also be manufactured according to the sample specifications required for the testing equipment.

[0061] According to classical linear viscoelasticity, for polymers, especially linear polymers, the elastic modulus G'-loss modulus G'' curve in the terminal region (the range where the angular velocity is close to the maximum value) conforms to the frequency dependence, and the longest chain of the polymer influences the viscoelastic behavior.

[0062] The dynamic frequency scan test procedure is as follows: The dynamic frequency scan test is performed using a TA-AR 2000EX rotational rheometer (TA Instruments, USA), with a parallel plate diameter of 25 mm and a thickness of 0.9 mm. To ensure that the test is performed in the linear viscoelastic region, the strain during the dynamic frequency scan test is 2%, the test temperature is Tm + 20°C, and the frequency scan range of the test is 500 rad / s≦w 2 ≦0.05 rad / s, thereby enabling data to be acquired in the lowest possible frequency range.

[0063] Dynamic frequency sweep testing can reveal the degree of entanglement between molecular chains during solid-phase melting (molten state). Compared to linear or short-branched structures, long-branched, network, and low-crosslinked structures have a higher degree of entanglement, exhibiting behavior that deviates from the linear ends, resulting in solid-phase behavior of the polymer. When the polymer of the present application satisfies the above range, the entanglement between molecular chains is further reduced, facilitating the diffusion of solvent molecules in the electrolyte between the molecular chains. Furthermore, because the polymer still maintains a certain degree of entanglement between molecular chains, it can lock solvent molecules in situ within the polymer, reducing the risk of the polymer being dissolved in the electrolyte and improving the stability of the polymer's performance. Furthermore, the polymer contributes to forming a protective layer on the surface of the active material, improving the performance of the solid-liquid interface, suppressing side reactions between the active material and the electrolyte, and improving the cycle performance and storage performance of the battery cell.

[0064] In some embodiments, the aldehyde ketone polymer has a glass transition temperature Tg in °C of -100 < Tg < 50, preferably -80 < Tg < 30.

[0065] The glass transition temperature (Tg) is the temperature at which an aldehyde ketone polymer segment transitions from frozen to mobile. The Tg has a certain effect on the flexibility of the aldehyde ketone polymer molecular chain. The lower the Tg, the better the flexibility of the aldehyde ketone polymer molecular chain at room temperature. The higher the Tg, the worse the flexibility of the molecular chain at room temperature. The Tg can be measured by differential scanning calorimetry (DSC). The measurement procedure is as follows: A 0.5-0.8 g sample is placed in a crucible and heated in a nitrogen gas atmosphere at a rate of 10°C / min from an initial temperature 20°C lower than the intrinsic Tg to a cutoff temperature 20°C higher than the intrinsic Tm. During this process, the actual Tg and Tm of the material are determined based on the heat absorption / dissipation peak or transition point of the material.

[0066] The aldehyde ketone polymer has a relatively low glass transition temperature, which allows the molecular chain segments to be more flexible, allowing adjacent molecular chains to open more easily, and allowing in-situ gel formation to occur more easily, thereby improving the infiltration of the electrolyte into the active material layer and improving the cycle performance of the battery cell. For example, 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 above values.

[0067] In some embodiments, the aldehyde ketone polymer comprises a structural unit shown in formula (I): [ka] In formula (I), R1 includes a single bond or a substituted or unsubstituted C1-C6 methylene group, and R2 includes a hydrogen atom or a substituted or unsubstituted C1-C6 alkyl group, and preferably, R1 includes a single bond or a substituted or unsubstituted C1-C2 methylene group, and R2 includes a hydrogen atom or a substituted or unsubstituted C1-C3 alkyl group.

[0068] For example, the aldehyde ketone polymer includes at least one of the structural units represented by formula (I-1) to formula (I-6). [ka]

[0069] Illustratively, the aldehyde ketone polymer comprises a structural unit shown in formula (II). [ka] In formula (II), R3 to R6 each independently comprise a hydrogen atom, a hydroxyl 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; r and s each independently comprise an integer of 0 to 5, and at least one of r and s is selected from positive integers; preferably, R3 to R6 each independently comprise a hydrogen atom, a hydroxyl 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.

[0070] In some embodiments, the aldehyde ketone polymer comprises at least one of the structural units represented by formula (II-1) through formula (II-4). [ka]

[0071] The above-mentioned aldehyde ketone polymer has a low degree of entanglement between molecular chains, which contributes to improving the flexibility of the molecular chains and allows the molecular chains to spread sufficiently in the electrolyte, thereby further improving the interfacial performance of the active material.

[0072] 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.).

[0073] The groups of the polymer of the present application can be detected by infrared spectroscopy IR, specifically, the polymer is tested by Thermo Nicolet Nexus 670 attenuated total reflection infrared Fourier transform infrared spectrometer (FTIR-ATR), and then the test is performed in accordance with the standard GB / T6040-2002, the test range is ATR method 600-4000 cm -1 , Reproducibility: ±2cm -1 , resolution: 4cm -1 Higher penetration depth: 0.2-0.6 μm.

[0074] The structure of the polymer of the present application can be determined by nuclear magnetic resonance NMR, specifically, by H NMR and C NMR using a Varian Mercury Plus-400 nuclear magnetic resonance instrument, the measurement temperature is 20°C, TMS is the internal standard, CDCl3 is the solvent, and the proton resonance frequency is 400 MHz.

[0075] The types of monomers in the polymers of the present invention (especially those monomers present in small proportions in the polymer) can be determined by a combination of pyrolysis, gas chromatography, and mass spectrometry. The measurement steps are as follows: 0.5 mg of sample is precisely weighed and placed in a sample cup, which is then attached to a feed rod and inserted into a pyrolyzer attached near the GC (gas chromatograph) feed port. When the temperature of the pyrolyzer reaches the set temperature, the feed button is pressed to rapidly allow the sample cup to freely fall into the core of the pyrolysis furnace. Volatile components are then instantly gasified in an inert N2 atmosphere, carried into a gas chromatograph column by a carrier gas, and separated. Finally, the components are detected using a flame ionization detector (FID) or a mass spectrometer (MS) to obtain a gas chromatogram or total ion chromatogram.

[0076] When the above groups are substituted, the substituents may include one or more of a nitrile group (-CN), a nitro group, a sulfonyl group, a carboxyl group, an ester group, a chlorine atom, a fluorine atom, and a bromine atom. The above substituents are high-pressure resistant substituents, which further contribute to stabilizing the structure of the polymer.

[0077] In some embodiments, n is selected from a positive integer of 500 to 15,000.

[0078] Preferably, n is selected from positive integers of 500 to 10,000.

[0079] In some embodiments, the molecular weight of the polymer is 1.2×10 5 g / mol ~ 1.0 × 10 6 g / mol.

[0080] When the molecular weight of the polymer is within the above range, the polymer exhibits a certain solubility in the electrolyte and is unlikely to be completely dissolved or 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, the flexibility of the polymer molecular chains 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 and enter between them and be enveloped by them, which is advantageous for the active ions to enter the active material through the solvent and realize smooth and rapid migration 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 g / mol or a range consisting of any two of the above values.

[0081] The molecular weight of aldehyde ketone polymers is a known value in the art and can be measured using equipment and methods commonly used in the art, such as gel permeation chromatography (GPC). The specific test steps are to take an appropriate amount of sample to be measured (ensure that the sample concentration is 8%-12% and the light shielding degree is 8%), add 20 ml of deionized water, and simultaneously apply ultrasonic waves (53 KHz / 120 W) outside for 5 minutes to completely disperse the sample, and then measure the sample according to GB / T19077-2016 / ISO 13320:2009 standard.

[0082] Alternatively, the test was performed using a multi-angle laser light scattering (MALLS) analyzer, specifically, a GPC combined with a DawnHeleos II multi-angle laser light scattering analyzer, an Optilab T-rEX refractive index (RI) detector, and a Visco Star II viscometer (Wyatt Technology Corporation, USA). The test was performed at 30°C using tetrahydrofuran as the mobile phase at a flow rate of 1.0 ml / min. The SEC-SAMLL data was processed using the commercially available software ASTRA6 to obtain molecular weight parameters.

[0083] If the aldehyde ketone polymer in the embodiment of the present application further satisfies one or more of the following conditions, the cycle performance of the battery cell can be further improved.

[0084] In some embodiments, the aldehyde ketone polymer is added to a first solvent at 45°C to form an aldehyde ketone polymer system, and the aldehyde ketone polymer system is allowed to stand at 45°C for 8 hours and then at 25°C for 24 hours or more. After undergoing these two-stage standing treatments, a portion or all of the aldehyde ketone polymer system is converted in situ into a gel-state substance. The aldehyde ketone polymer system is then filtered through a 200-mesh filter, leaving a first substance. The mass of the aldehyde ketone polymer is n (g), the mass of the first substance is m (g), and the ratios of the aldehyde ketone polymer and the first substance satisfy 5≦m / n≦1000, preferably 10≦m / n≦1000, and more preferably 10≦m / n≦50. Illustratively, 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 foregoing values.

[0085] Illustratively, based on the mass of the aldehyde ketone polymer system, the ratio of the mass content of the aldehyde ketone polymer to the mass content of the first solvent ranges from 1:100 to 1:10, for example, 3:50.

[0086] For example, the first solvent may be the same as or similar to the solvent of the electrolyte, and may include a carbonate-based solvent, such as a cyclic carbonate solvent and / or a linear carbonate solvent.

[0087] Examples of cyclic carbonate solvents include one or more of ethylene carbonate EC, vinylene carbonate VC, fluoroethylene carbonate FEC, difluoroethylene carbonate DFEC, vinylethylene carbonate VEC, and dioctyl carbonate CC.

[0088] 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 VA.

[0089] Preferably, the first solvent may contain both a lithium salt and an electrolyte additive, such as lithium hexafluorophosphate, vinylene carbonate (VC), or fluoroethylene carbonate (FEC).

[0090] In this application, m / n is also referred to as the sedimentation value, which represents the ability of the aldehyde ketone polymer and solvent to be converted into a gel-state material.

[0091] The first substance mainly includes a gel-state substance formed by the aldehyde ketone polymer and the first solvent, and in such a gel-state substance, the molecular structure of the aldehyde ketone polymer remains almost unchanged.

[0092] In some embodiments, the first material is dried at 80° C. for 12 hours to remove the first solvent in the first material, and then detected by infrared spectroscopy (IR) or nuclear magnetic resonance (NMR) testing is performed, and the main component of the first material after drying is the aforementioned aldehyde ketone polymer.

[0093] In this application, by increasing the temperature, the aldehyde ketone polymer molecular chains are expanded within the safe operating temperature range of the battery cell, promoting mutual attraction and physical bonding between the aldehyde ketone polymer molecular chains and the solvent, thereby improving the liquid absorption capacity.At room temperature, the activity of the aldehyde ketone polymer molecular segments decreases, allowing them to adhere to the surface of the active material, locking the electrolyte in the spatial environment of the aldehyde ketone polymer and forming an in-situ gel-like state, improving the liquid locking capacity and cycle performance. Positive electrode sheet

[0094] 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, and the positive electrode active material layer includes a positive electrode active material and an aldehyde ketone polymer. In the present application, the aldehyde ketone polymer includes the aforementioned aldehyde ketone polymer.

[0095] For example, the positive electrode current collector has both surfaces facing each other in its thickness direction, and the positive electrode active material layer is provided on either one or both of the two surfaces of the positive electrode current collector.

[0096] In some embodiments, 1.00 < v / λ < 4.00, preferably 1.20 ≤ v / λ ≤ 3.80, more preferably 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 consisting of any two of the above numerical values.

[0097] In some embodiments, based on the mass of the positive electrode active material layer, the mass percentage of the aldehyde ketone polymer is A%, where 0.1 ≤ A ≤ 1.5.

[0098] When the mass percentage of the aldehyde ketone polymer is within the above range, the liquid absorption capacity of the positive electrode active material layer can be significantly improved. Exemplarily, the mass percentage A% of the aldehyde ketone polymer may be 0.1%, 0.2%, 0.5%, 0.8%, 1.0%, 1.2%, 1.5% or a range consisting of any two of the above numerical values.

[0099] 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 known in the art for use in battery cells. 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).

[0100] 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. Preferably, y=0. Specifically, the layered positive electrode active material is lithium cobalt oxide (LCO), lithium nickel oxide (LNO), lithium manganese oxide (LMO), LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2(NCM333), LiNi 0.8 Co 0.1 Mn 0.1 O2(NCM811) and LiNi 0.5 Co 0.2 Mn 0.3 It may also contain one or more of O2 (NCM523).

[0101] 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, 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 one or more of LiFePO4, LiMnPO4, LiNiPO4, and LiCoPO4.

[0102] For example, the general formula of the positive electrode active material having a spinel structure is Li x A y Mn a M 2-a Y z where 0≦x≦2, 0≦y≦1, and 0.9≦x+y≦2, 0.5≦a≦2, 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 1.9O4, Li2Mn2O4 and Li 1.5 Mn2O4.

[0103] In some embodiments, the positive electrode current collector may be a metal foil sheet or a composite current collector. Examples of the metal foil sheet 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 include one or more combinations selected from aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, and the polymeric material base layer may include one or more combinations selected from polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0104] In some embodiments, the positive electrode active material layer may further include a positive electrode conductive agent, if necessary. The type of positive electrode conductive agent in the present application 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 particles, 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.

[0105] In some embodiments, the positive electrode active material layer may further include a positive electrode binder, if necessary. In the present application, the type of positive electrode binder is not particularly limited. For example, the positive electrode binder may include one or a combination of polyvinylidene fluoride (PVDF). In some embodiments, the mass percentage of the positive electrode binder is 5% or less, based on the total mass of the positive electrode active material layer. The crystallinity of the positive electrode binder is higher than that of the aldehyde ketone polymer described above in the present application. The melting temperature of the positive electrode binder is higher than that of the aldehyde ketone polymer described above in the present application.

[0106] 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 aldehyde ketone 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). Negative electrode sheet

[0107] 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, the negative electrode active material layer including a negative electrode active material and an aldehyde ketone polymer. In the present application, the aldehyde ketone polymer includes the aforementioned aldehyde ketone polymer.

[0108] For example, the negative electrode current collector has opposite surfaces facing each other in the thickness direction thereof, and the negative electrode active material layer is provided on one or both of the opposing surfaces of the negative electrode current collector.

[0109] In some embodiments, 3.00 < v / λ < 50.00, and preferably, 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 consisting of any two of the above numerical values.

[0110] In some embodiments, based on the mass of the negative electrode active material layer, the mass percentage of the aldehyde ketone polymer is B%, and 0.2 ≤ B ≤ 5.0. When the mass percentage of the aldehyde ketone 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 aldehyde ketone 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%, 5.0% or a range consisting of any two of the above numerical values.

[0111] In some embodiments, the negative electrode current collector can use a metal foil sheet or a composite current collector. For example, a copper foil can be adopted as the metal foil sheet. The composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base. The composite current collector can be formed by forming a metal material (such as copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material base (such as a base of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0112] In some embodiments, the negative electrode active material may be a battery negative electrode active material known in the art. 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 elemental silicon, silicon-oxygen compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be at least one selected from elemental tin, tin oxycompounds, and tin alloys. However, the present application is not limited to these materials, and other conventional materials used as negative electrode active materials in batteries may also be used. These negative electrode active materials may be used alone or in combination.

[0113] In some embodiments, the negative electrode active material layer may further include a negative electrode binder, if necessary. 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 aldehyde ketone polymer described above in the present application. The melting temperature of the negative electrode binder is higher than that of the aldehyde ketone polymer described above in the present application.

[0114] In some embodiments, the negative electrode active material layer may further include a conductive agent, if necessary, which may be at least one selected from superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0115] In some embodiments, the negative electrode active material layer may further contain other auxiliary agents, such as a thickener (for example, sodium carboxymethylcellulose (CMC-Na)), as needed.

[0116] In some embodiments, the components for producing the negative electrode sheet, such as the negative electrode active material, the aldehyde ketone 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 after steps such as drying and cold pressing. This allows the negative electrode sheet to be produced. Battery cell

[0117] According to a second aspect, the present application provides a battery cell including a positive electrode sheet, a negative electrode sheet, a separator disposed between the positive electrode sheet and the negative electrode sheet, and an electrolyte. The battery cell may be a lithium-ion battery or the like.

[0118] 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, and the negative electrode sheet may be a conventional electrode sheet.

[0119] 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, and the positive electrode sheet may be a conventional electrode sheet.

[0120] 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. [Electrolyte]

[0121] The battery cell further includes an electrolyte, which serves to conduct ions between the positive electrode sheet and the negative electrode sheet. The type of electrolyte in the present application is not particularly limited and can be selected according to needs. The electrolyte may be, for example, liquid, gel, or all-solid.

[0122] In some embodiments, the electrolyte uses an electrolytic solution, which includes an electrolyte salt and a solvent.

[0123] Exemplarily, the lithium salt may include one or a combination of more selected from lithium hexafluorophosphate (LiPF), lithium tetrafluoroborate (LiBF), lithium perchlorate (LiClO), lithium hexafluoroarsenate (LiAsF), lithium bisfluorosulfonylimide (LiFSI), lithium bistrifluoromethanesulfonylimide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorooxalatoborate (LiDFOB), lithium bisoxalatoborate (LiBOB), lithium difluorophosphate (LiPOF), lithium difluorodisalophosphate (LiDFOP), and lithium tetrafluorooxalophosphate (LiTFOP).

[0124] Exemplary organic solvents may include one or more selected from 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).

[0125] In some embodiments, the electrolyte solution may further contain additives as needed. For example, the additives may include a negative electrode film-forming additive, a positive electrode film-forming additive, or an additive that improves 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. [Separator]

[0126] In some embodiments, the battery cell further includes a separator. The type of separator in the present application is not particularly limited, and any known porous structure separator having good chemical stability and mechanical stability can be selected.

[0127] 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.

[0128] In some embodiments, the positive electrode sheet, separator, and negative electrode sheet can be formed into an electrode assembly by a winding or lamination process.

[0129] The shape of the battery cell of the present application 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.

[0130] In some embodiments, as shown in FIGS. 1 and 2 , the exterior may include a case 51 and a cover plate 53. The case 51 includes a bottom plate and a side plate connected to the bottom plate, and a storage chamber is formed by the bottom plate and the side plate. The case 51 has an opening communicating with the storage chamber, and the cover plate 53 covers the opening to close the storage chamber. 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 sealed in the storage chamber. An electrolyte is impregnated into the electrode assembly 52. ​​The number of electrode assemblies 52 included in the battery cell 5 may be one or more types and may be adjusted according to needs.

[0131] The method for manufacturing the battery cell of the present application is well 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 wound or stacked to form an electrode assembly, which can then be placed in a housing and dried. The electrode assembly can then be infused with an electrolyte, and the battery cell can be obtained through processes such as vacuum sealing, standing, chemical conversion, and shaping.

[0132] In some embodiments of the present application, the battery cells of the present application can 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.

[0133] 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.

[0134] Preferably, the battery module 4 further includes a housing having an accommodating space, and the plurality of battery cells 5 are accommodated in the accommodating space.

[0135] 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.

[0136] 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 a plurality of 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 closed space for accommodating the battery modules 4. The plurality of battery modules 4 may be arranged in the battery box in any manner.

[0137] Both the battery module and the battery pack can be examples of the battery of the present application. power consumption equipment

[0138] According to a third aspect, the present application provides a power consuming device including at least one of the battery cell, battery module, and battery pack of the present application. The battery cell, battery module, and battery pack may be used as a power source for the power consuming device or as an energy storage unit 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.

[0139] A power consuming device can be configured as a battery cell, a battery module, or a battery pack depending on its needs. FIG. 6 is a schematic diagram of an exemplary power consuming device. The power consuming device 6 may be a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, etc. 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. Another exemplary power consuming device may be a mobile phone, a tablet computer, a laptop, etc. Such a power consuming device is usually required to be thin, and may adopt a battery cell as its power source. Example

[0140] The following examples of the present application are described. The examples described below are illustrative and are intended only to interpret the present application and should not be understood as limitations on the present application. Unless specific techniques or conditions are specified in the examples, the techniques, conditions, or product instructions described in the literature in this field are used. Unless the manufacturer is specified, the reagents or equipment used are all commercially available, ordinary products. Example 1 (1) Manufacturing of positive electrode sheets

[0141] As the positive electrode current collector, an aluminum foil having a thickness of 12 μm was used.

[0142] A positive electrode slurry was prepared using an aldehyde ketone polymer, a positive electrode active material (LiFePO4), carbon black as a conductive agent, and polyvinylidene fluoride (PVDF) and N-methylpyrrolidone (NMP) as binders. The mass ratio of the aldehyde ketone 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, edge-cut, cut, and divided into stripes. The positive electrode sheet was then dried in a vacuum at 85°C for 4 hours to prepare a positive electrode sheet. (2) Manufacturing of negative electrode sheets

[0143] A copper foil with a thickness of 8 μm was used as the negative electrode current collector.

[0144] Aldehyde ketone 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 were uniformly mixed in a weight ratio of 2.5:94:0.5:2:1:100 to prepare a negative electrode slurry. The negative electrode slurry was applied to a copper foil current collector and dried at 85°C. After that, the foil was cold pressed, edge-cut, cut, and divided into stripes. The negative electrode sheet was then dried at 120°C under vacuum for 12 hours to prepare a negative electrode sheet. (3) Electrolyte production

[0145] 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 obtain an electrolyte with a lithium salt concentration of 1 mol / L. (4) Lithium-ion battery manufacturing

[0146] 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, and the separator was placed between the positive electrode sheet and the negative electrode sheet to serve as an insulator. The stack was then wound to obtain an electrode assembly. The electrode assembly was placed in an outer can, dried, and then an electrolyte was injected. After vacuum sealing, standing, chemical conversion, and shaping, a lithium-ion battery was obtained. Comparative Example 1

[0147] A lithium ion battery was manufactured in a manner similar to that of Example 1, but unlike Example 1, no aldehyde ketone polymer was added to the positive electrode sheet of Comparative Example 1, and no aldehyde ketone polymer was added to the negative electrode sheet of Comparative Example 1. Comparative Example 2

[0148] A lithium ion battery was manufactured in a similar manner to Example 1, but unlike Example 1, the aldehyde ketone polymer material in the positive electrode sheet and negative electrode sheet of Comparative Example 2 was changed. Examples 2 to 4

[0149] Lithium ion batteries were produced in a similar manner to Example 1, but unlike Example 1, the aldehyde ketone polymer materials in the positive electrode sheets and negative electrode sheets of Examples 2 to 4 were changed. Example 5

[0150] A lithium ion battery was manufactured in a manner similar to that of Example 1, except that, unlike Example 1, an aldehyde ketone polymer was added to the positive electrode sheet of Example 5, and no aldehyde ketone polymer was added to the negative electrode sheet of Example 5. Examples 6 to 9

[0151] Lithium ion batteries were produced in a similar manner to Example 1, but unlike Example 1, the content of the aldehyde ketone polymer in the positive electrode sheets of Examples 6 to 9 was adjusted. Examples 10 to 12

[0152] Lithium ion batteries were produced in a similar manner to Example 1, but unlike Example 1, the content of the aldehyde ketone polymer in the negative electrode sheets of Examples 10 to 12 was adjusted.

[0153] The data for the examples and comparative examples are shown in Table 1. Test part 1. Lithium-ion battery capacity retention test

[0154] 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 further charged at a constant voltage of 4.25V until the current reached 0.05C, allowed to stand for 5 minutes, and then discharged at 1C to 2.8V, with the resulting capacity designated as the initial capacity C0. The same batteries were repeatedly charged and the discharge capacity Cn of the batteries after n cycles was recorded. The battery's capacity retention after each cycle was calculated as Pn = Cn / C0 * 100%, and a spot diagram of the battery's capacity retention versus cycle number was obtained by plotting the 1200 point values ​​P1, P2...P1200 as the ordinate and the corresponding cycle number as the abscissa.

[0155] In this test process, the first cycle corresponds to n=1, the second cycle corresponds to n=2, ... the 1200th cycle corresponds to n=1200. For example, the capacity retention data of the battery corresponding to Example 1 in Table 1 is data measured after 1200 cycles under the above test conditions, i.e., the P1200 value. The test process for Comparative Example 1 and other Examples is the same as above.

[0156] 2. Lithium-ion battery DC impedance test

[0157] 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 further charged at a constant voltage of 4.25V until the current reached 0.05C. After 5 minutes of storage, the voltage V1 was recorded. The batteries were then discharged at 1C for 30 seconds, and the voltage V2 was recorded. This voltage was calculated as (V2 - V1) / 1 / 3C, giving 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) after the nth cycle (n = 1, 2, 3, ... 1200). A graph of the discharge DCIR versus cycle number for the batteries containing the aldehyde ketone polymers of the examples and comparative examples was plotted. The 1200-point values ​​(DCR1, DCR2, DCR3, ... DCR1200) were plotted on the ordinate and the corresponding cycle number on the abscissa.

[0158] In this test process, the first cycle corresponds to n=1, the second cycle corresponds to n=2, ... the 1200th cycle corresponds to n=1200. For example, in Table 1, the internal resistance increase rate of the battery of Example 1 = (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 is data measured after 1200 cycles under the above test conditions. Test Results

[0159] [Table 1-1] [Table 1-2]

[0160] In Table 1, 100% formaldehyde means that the mass percentage of formaldehyde is 100% based on the total mass of Monomer 1 and Monomer 2.

[0161] 30% polyvinyl alcohol means that the mass percentage of polyvinyl alcohol is 30% relative to the total mass of Monomer 1 and Monomer 2.

[0162] As can be seen from Table 1, compared to Comparative Example 1, in the Examples of the present application, the aldehyde ketone polymer of the present application is added to the positive electrode sheet and / or negative electrode sheet, and the aldehyde ketone polymer forms uniform high infiltration points inside the active material layer, uniformly improving the infiltration performance of the active material layer, thereby improving the liquid absorption rate of the entire active material layer, and improving the cycle performance of a battery cell using the electrode sheet.

[0163] 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.

[0164] Although the present application has been described above with reference to preferred embodiments, various modifications may be made without departing from the scope of the present application, and some of the components may be replaced with equivalents. In particular, as long as there is no structural contradiction, the technical features described in each embodiment may be arbitrarily combined. The present application is not limited to the specific embodiments disclosed above, but includes all technical solutions falling within the scope of the claims. [Explanation of symbols]

[0165] 1 battery pack 2 Upper case 3 Lower housing 4 Battery Module 5 battery cells 51 cases 52 Electrode Assembly 53 Cover plate 6 Power consumption equipment

Claims

1. a current collector and an active material layer provided on at least one surface of the current collector, The active material layer contains an active material and an aldehyde ketone polymer, and the active material layer satisfies the following formulas (1) to (3): 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 its unit is mg / s, d represents the diameter of the capillary in a capillary test of the active material layer, and its unit is mm; h represents the height of the liquid surface in the capillary, and its unit is 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 its unit is s; Electrode sheet.

2. 2. The electrode sheet according to claim 1, wherein the active material comprises a positive electrode active material, and the active material layer satisfies 1.00<v / λ<4.00, preferably 1.20≦v / λ≦3.

80.

3. 3. The electrode sheet according to claim 1, wherein the active material comprises a positive electrode active material, and the mass percentage of the aldehyde ketone polymer is A%, based on the mass of the active material layer, and 0.1≦A≦1.

5.

4. 2. The electrode sheet according to claim 1, wherein the active material comprises a negative electrode active material, and the active material layer satisfies 3.00<v / λ<50.00, preferably 3.40≦v / λ≦30.

00.

5. 5. The electrode sheet according to claim 1, wherein the active material includes a negative electrode active material, and the mass percentage of the aldehyde ketone polymer is B%, based on the mass of the active material layer, and 0.2≦B≦5.

0.

6. producing the aldehyde ketone polymer as a sheet-like structure; With respect to the sheet-like structure, (T m A dynamic frequency scan test is performed at 100°C (+20°C) to obtain a modulus of elasticity G'-loss modulus of elasticity G'' curve, and the slope K of the modulus of elasticity G'-loss modulus of elasticity G'' curve is 0.8≦K<∞, preferably 0.8≦K≦100, and more preferably 0.8≦K≦10. m The electrode sheet according to any one of claims 1 to 5, wherein °C indicates the melting temperature of the aldehyde ketone polymer.

7. The electrode sheet according to any one of claims 1 to 6, wherein the aldehyde ketone polymer has a glass transition temperature Tg in the range of -100≦Tg≦50, expressed in °C, and preferably in the range of -80≦Tg≦30.

8. The aldehyde ketone polymer comprises a structural unit represented by formula (I): 【Chemical 1】 In formula (I), R 1 contains a single bond, a substituted or unsubstituted C1-C6 methylene group, and R 2 contains a hydrogen atom, a substituted or unsubstituted C1 to C6 alkyl group, and preferably R 1 contains a single bond, a substituted or unsubstituted C1-C2 methylene group, and R 2 The electrode sheet according to any one of claims 1 to 7, wherein contains a hydrogen atom or a substituted or unsubstituted C1 to C3 alkyl group.

9. The electrode sheet according to claim 8, wherein the aldehyde ketone polymer contains at least one of structural units represented by formulas (I-1) to (I-6). 【Chemistry 2】

10. The aldehyde ketone polymer comprises a structural unit represented by formula (II): 【Chemistry 3】 In formula (II), R 3 ~R 6 each independently comprises a hydrogen atom, a hydroxyl 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 are each independently selected from integers of 0 to 5, and at least one of r and s is selected from a positive integer; Preferably, R 3 ~R 6 each independently contain a hydrogen atom, a hydroxyl 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. The electrode sheet according to any one of claims 1 to 9.

11. The electrode sheet according to claim 10, wherein the aldehyde ketone polymer contains at least one of a structural unit represented by formula (II-1) to a structural unit represented by formula (II-4). 【Chemistry 4】

12. n is selected from the group consisting of positive integers from 500 to 15,000, and / or The molecular weight of the aldehyde ketone polymer is 1.2×10 5 g / mol~1.0×10 6 The electrode sheet according to any one of claims 8 to 11, wherein the surface area is 100 μm or less.

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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