Ether-based polymers, electrode sheets, and related battery cells, batteries, and power consumption devices.

Abstract

To suppress the degradation of battery cell cycle performance caused by insufficient liquid storage capacity of the electrode sheet's active material, and to improve battery cell performance. [Solution] This application provides an ether-based polymer, an electrode sheet, and related battery cells, batteries, and power consumption devices. The ether-based polymer is added to a first solvent at 45°C to form an ether-based polymer system, which is left to stand at 45°C for 8 hours and then at 25°C for 24 hours or more, after which it is filtered through a 200-mesh filter, and the remaining filtrate is the first substance, the mass n of the ether-based polymer is in units of g, the mass m of the first substance is in units of g, and the ether-based polymer and the first substance satisfy 5 ≤ m / n ≤ 1000. When the ether-based polymer is applied to a battery cell, the cycle performance of the battery cell can be further improved.

Description

[Technical Field]

[0001] This application relates to the field of batteries, and more particularly to ether-based polymers, electrode sheets, and related battery cells, batteries, and power consumption devices. [Background technology]

[0002] Battery cells have characteristics such as high capacity and long lifespan, and are therefore widely used in electronic devices such as mobile phones, laptops, electric scooters, electric vehicles, electric aircraft, electric boats, electric vehicle toys, electric boat toys, electric aircraft toys, and power tools.

[0003] As batteries are used in an increasing number of applications, the demands on battery cell performance are becoming increasingly stringent. Improving the safety performance of battery cells typically involves optimizing and improving the performance of the electrode sheets within the battery cell. However, currently, electrode sheets often have poor liquid storage capacity for their active materials, which can lead to a decrease in the battery cell's cycle performance when applied to battery cells. [Overview of the project]

[0004] This application has been made in view of the above-mentioned problems and aims to provide an ether-based polymer, an electrode sheet, and related battery cells, batteries, and power consumption devices.

[0005] A first aspect of the present application provides an ether-based polymer for use in battery cells, wherein the ether-based polymer is added to a first solvent at 45°C to form an ether-based polymer system; the ether-based polymer system is allowed to stand at 45°C for 8 hours, then allowed to stand at 25°C for 24 hours or more, and then filtered through a 200-mesh filter, and the residual filtered residue is taken as a first substance, the mass of the ether-based polymer is n with a unit of g, the mass of the first substance is m with a unit of g, and the ether-based polymer satisfies 5≦m / n≦1000. When the ether-based polymer satisfies the above condition, the cycling performance and storage performance of the battery cell can be further improved.

[0006] In this way, the ether-based polymer according to the present application enables expansion of molecular chains within the high safe operating temperature range of a secondary battery, while promoting attraction and physical bonding between the molecular chains of the ether-based polymer and the solvent in the electrolyte, and contributing to bonding of the molecular chains of the ether-based polymer to the solvent, so that the electrolyte can be stored in the active material layer. Within the low safe operating temperature range of a secondary battery, the ether-based polymer may become immobile, and the ether-based polymer can adhere to the surface of the active material while maintaining a state of locking the electrolyte in the space and environment where the ether-based polymer is located, which improves the liquid storage capacity of the active material layer and enhances the impregnation performance of the electrolyte into the active material layer. As a result, the cycling performance of the secondary battery using the ether-based polymer can be improved.

[0007] In some embodiments, 10≦m / n≦1000, and optionally 10≦m / n≦50. When the ether-based polymer satisfies the above condition, the cycling performance of the battery cell can be further improved.

[0008] In some embodiments, the first solvent comprises a cyclic carbonate solvent and / or a chain carbonate solvent, Optionally, the cyclic carbonate solvent comprises one or more selected from the group consisting of ethylene carbonate (EC), vinylene carbonate (VC), fluoroethylene carbonate (FEC), difluoroethylene carbonate (DFEC), vinyl ethylene carbonate (VEC) and dioctyl carbonate (CC), Optionally, the chain carbonate solvent comprises one or more selected from the group consisting of dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), diphenyl carbonate (DPC), methyl allyl carbonate (MAC) and polycarbonate (VA).

[0009] In some embodiments, a sheet-like structure is produced from the ether-based polymer, and for the sheet-like structure, (T m +20)°C, a dynamic frequency scanning test is performed to obtain an elastic modulus G'-loss elastic modulus G'' curve, wherein a slope K of the elastic modulus G'-loss elastic modulus G'' curve satisfies 1<K<∞, and T m (°C) represents a melting temperature of the ether-based polymer.

[0010] In this way, when the ether-based polymer according to the present application satisfies the above range, the entanglement between molecular chains is further reduced, which facilitates the dispersion of solvent molecules in the electrolyte between the molecular chains. In addition, since the ether-based polymer still maintains the entanglement between molecular chains to a certain extent, it can lock solvent molecules in-situ inside the polymer, reduce the risk of the ether-based polymer dissolving in the electrolyte, and improve the stability of polymer performance. Furthermore, the ether-based polymer contributes to forming a protective layer on the surface of an active material, improves the performance of a solid-liquid interface, suppresses side reactions between the active material and the electrolyte, and improves the cycle performance of a battery cell.

[0011] In some embodiments, the glass transition temperature Tg of the ether polymer is in °C, -100 ≤ Tg ≤ 50, and optionally -80 ≤ Tg ≤ 30. A lower glass transition temperature of the ether polymer makes the molecular chain segments more flexible, allowing adjacent molecular chains to be cleaved more easily, thereby improving the impregnation of the electrolyte into the active material by more readily forming an in-situ gel, and consequently improving the cycle performance of the battery cell.

[0012] In some embodiments, the ether polymer comprises a structural unit represented by formula (I), [ka] 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, and R3 comprises a substituted or unsubstituted C1-C5 methylene group, and 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.

[0013] In some embodiments, the ether polymer comprises at least one of the structural units represented by formula (I-1) to formula (I-8). [ka]

[0014] In some embodiments, the ether polymer comprises a structural unit represented by formula (II), [ka] In formula (II), each of R4 to R7 independently comprises 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 an ether group, and optionally each of R4 to R7 independently comprises 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 an ether group.

[0015] In some embodiments, the ether polymer comprises at least one structural unit represented by formula (II-1) to formula (II-7). [ka]

[0016] In some embodiments, n is selected from a positive integer between 1500 and 25000, and / or the molecular weight of the ether polymer is 1.2 × 10⁻⁶. 5 g / mol ~ 1.0 × 10 6 The concentration is g / mol. When the molecular weight of a polymer is within the above range, it can exhibit a certain degree of solubility in the electrolyte, while at the same time becoming less likely to completely dissolve or disperse in the electrolyte, making it easier to control the distribution and dispersion on the surface of the active material. Furthermore, the flexibility of the polymer's molecular chains is further increased, the forces between molecular chains are weakened, and solvent molecules in the electrolyte contribute to cleaving the molecular chains and entering between them, becoming encapsulated within the molecular chains. As a result, active ions can more easily enter the active material via the solvent, allowing for smooth and rapid movement.

[0017] A second aspect of this application provides a positive electrode sheet comprising a positive electrode current collector and a positive electrode film layer provided on the positive electrode current collector, wherein the positive electrode film layer comprises a positive electrode active material and an ether-based polymer, and the ether-based polymer comprises an ether-based polymer described in any embodiment of the first aspect of this application.

[0018] A third aspect of this application provides a negative electrode sheet comprising a negative electrode current collector and a negative electrode film layer provided on the negative electrode current collector, wherein the negative electrode film layer comprises a negative electrode active material and an ether-based polymer, and the ether-based polymer comprises an ether-based polymer described in any embodiment of the first aspect of this application.

[0019] A fourth aspect of this application provides a battery cell comprising a positive electrode sheet and a negative electrode sheet, wherein the positive electrode sheet comprises a positive electrode sheet described in any embodiment of the second aspect of this application, and / or the negative electrode sheet comprises a negative electrode sheet described in any embodiment of the third aspect of this application.

[0020] A fifth aspect of this application provides a battery comprising the battery cell described in the fourth aspect of this application.

[0021] A sixth aspect of this application provides a power consumption device comprising the battery described in the fifth aspect of this application.

[0022] To more clearly explain the technical concept of the embodiments of this application, the drawings necessary for the embodiments of this application will be briefly described below, and the drawings described below represent only a few embodiments of this application. It will be obvious to those skilled in the art that other drawings can be derived from these drawings without requiring any creative effort. [Brief explanation of the drawing]

[0023] [Figure 1] This is a schematic diagram of one embodiment of the battery cell of this application. [Figure 2] Figure 1 is a schematic exploded view of an embodiment of the battery cell. [Figure 3] This is a schematic diagram of one embodiment of the battery module of this application. [Figure 4] This is a schematic diagram of one embodiment of the battery pack of this application. [Figure 5] Figure 4 is a schematic exploded view of an embodiment of the battery pack shown. [Figure 6]This is a schematic diagram of one embodiment of a power consumption device equipped with the battery cell of the present application as a power source.

[0024] Drawings are not always drawn to actual scale. [Modes for carrying out the invention]

[0025] The following describes in detail embodiments of the ether polymer, electrode sheet, and related battery cells, batteries, and power consumption devices disclosed in this application. However, unnecessary details may be omitted. For example, detailed descriptions of already well-known matters and redundant descriptions of substantially identical configurations may be omitted. This is to avoid the following description becoming unnecessarily verbose and to facilitate understanding for those skilled in the art. The accompanying drawings and the following description are provided to enable those skilled in the art to fully understand this disclosure and are not intended to limit the subject matter described in the claims.

[0026] The “range” disclosed in this application is defined by a lower limit and an upper limit, and a given range is defined by selecting one lower limit and one upper limit, which define the boundary values ​​of a particular range. The range thus defined may include endpoints, or may include endpoints, but can be combined arbitrarily, that is, any lower limit and any upper limit can be combined to form a single range. For example, if the ranges 60-120 and 80-110 are given for a particular parameter, it can be understood that the ranges 60-110 and 80-120 are also assumed. Also, if 1 and 2 are given as the minimum range values ​​and 3, 4 and 5 as the maximum range values, all ranges including 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5 can be assumed. In this application, unless otherwise specified, the numerical range “a-b” represents an abbreviated expression for any combination of real numbers within the range a-b, where both a and b are real numbers. For example, the numerical range "0 to 5" means that all real numbers within the range "0 to 5" are listed herein, and "0 to 5" is merely an abbreviated representation of combinations of these numbers. Also, when a parameter is described as an integer of 2 or more, it is equivalent to disclosing that the parameter is an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0027] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined with each other to form new technical solutions. Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form new technical solutions.

[0028] Unless otherwise specified, all steps of this application may be performed sequentially or randomly, but it is preferable that they be performed sequentially. For example, if the method includes steps (a) and (b), it may include steps (a) and (b) performed sequentially, or steps (b) and (a) performed sequentially. For example, if 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 steps (a), (c) and (b), or steps (c), (a) and (b).

[0029] Unless otherwise specified, the terms “includes” or “equipment” as used in this application may mean open inclusion or closed inclusion. For example, “includes” and “equipment” may mean including or providing other components not listed, or they may mean including or providing only the listed components.

[0030] Unless otherwise specified, the term "or" in this application has an inclusive meaning. For example, the phrase "A or B" means "A, B, or both A and B." More specifically, the condition "A or B" includes any of the following: 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).

[0031] In this application, the terms "multiple" and "multiple types" mean two or more or two or more types.

[0032] The term "alkyl group" includes both linear and branched alkyl groups. For example, an 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 may include 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. If substituted, the substituent includes a fluorine atom.

[0033] 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 examples, the alkoxy group may include a methoxy group, an ethoxy group, or a propoxy group. Furthermore, the alkoxy group may be optionally substituted.

[0034] The term "halogen atom" refers to atoms such as fluorine, chlorine, and bromine.

[0035] The term "hydrogen" refers to 1H (practium, H), 2H (deuterium, D), or 3H (tritium, T). In each example, "hydrogen" may also be 1H (practium, H).

[0036] The secondary battery comprises a positive electrode sheet, a negative electrode sheet, and an electrolyte. The electrolyte impregnates the positive and negative electrode sheets, enabling the smooth movement of active ions between them.

[0037] The electrode sheets (e.g., a positive electrode sheet and / or a negative electrode sheet) include a current collector and an active material layer provided on at least one surface of the current collector, the active material layer having a void structure through which the electrolyte diffuses from the surface of the active material into the active material layer, thereby impregnating the active material layer with the electrolyte and allowing active ions to move smoothly from the positive electrode sheet to the negative electrode sheet.

[0038] In related technologies, the active material layer often has poor affinity with the electrolyte, resulting in poor impregnation of the electrolyte into the active material layer and a decrease in the liquid storage capacity of the active material layer. When secondary batteries are used, transported, or assembled as modules, external pressure can be applied, causing the electrolyte within the active material layer to be pushed out. As a result, reabsorption of the electrolyte becomes increasingly difficult, which can lead to a decrease in the capacity of the secondary battery and a deterioration in its cycle performance.

[0039] In view of this, in the embodiments of this application, in order to improve the liquid storage capacity of the electrode sheet, an ether-based polymer is added to the electrode sheet to increase the affinity between the electrode sheet and the electrolyte, thereby improving the impregnation of the electrolyte into the electrode sheet, and as a result the cycle performance of the secondary battery using the ether-based polymer is improved. Ether-based polymers

[0040] A first aspect of this application provides an ether-based polymer. The ether-based polymer is used in a battery cell and is added to a first solvent at 45°C to form an ether-based polymer system. The ether-based polymer system undergoes a two-stage standing process, being left to stand at 45°C for 8 hours and then at 25°C for 24 hours or more, after which a portion of it is converted in situ to a gel-like substance. Subsequently, the ether-based polymer system is filtered through a 200-mesh filter, and the remaining filtrate is the first substance. After filtering the ether-based polymer system through a 200-mesh filter, the mobile phase solvent is removed by filtration, and the remaining substance becomes the first substance. The mass n of the ether-based polymer is in units of g, and the mass m of the first substance is in units of g. The ether-based polymer and the first substance satisfy 5 ≤ m / n ≤ 1000, optionally 10 ≤ m / n ≤ 1000, and optionally 10 ≤ m / n ≤ 50. For example, m / n may be a range consisting of 5, 10, 20, 25, 28, 30, 32, 35, 40, 50, 80, 100, 200, 500, 1000, or any two of the above values.

[0041] For example, based on the mass of the ether polymer system, the range of the mass content ratio of the ether polymer to the first solvent is 1:100 to 1:10, for example, 3:50.

[0042] For example, the first solvent is the same as or similar to the solvent in the electrolyte, and the first solvent may include a carbonate-based solvent. For example, the carbonate-based solvent includes cyclic carbonate solvents and / or linear carbonate solvents.

[0043] Examples of cyclic carbonate solvents include one or more of the following: ethylene carbonate (EC), vinylene carbonate (VC), fluoroethylene carbonate (FEC), difluoroethylene carbonate (DFEC), vinylethylene carbonate (VEC), and dioctyl carbonate (CC).

[0044] Examples of linear carbonate solvents include one or more of the following: dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), diphenyl carbonate (DPC), methyl allyl carbonate (MAC), and polycarbonate (VA).

[0045] Optionally, the first solvent may also contain lithium salts or electrolyte additives such as lithium hexafluoride phosphate, vinylene carbonate (VC), or fluorovinylene carbonate (FEC).

[0046] In this application, m / n is also called the precipitation value and represents the ability of the ether polymer and solvent to convert into a gel-like substance.

[0047] The first substance mainly consists of a gel-like substance formed from an ether-based polymer and a first solvent, in which the molecular structure of the ether-based polymer remains largely unchanged.

[0048] In some embodiments, the first substance is dried at 80°C for 12 hours to remove the first solvent from the first substance, and then detected by infrared spectroscopy (IR) or tested by nuclear magnetic resonance (NMR). The first substance after drying mainly contains the aforementioned ether-based polymer.

[0049] Within the high safe operating temperature range of a secondary battery, the ether-based polymer enables the unfolding of molecular chains, promotes attraction and physical bonding between the molecular chains of the ether-based polymer and the solvent in the electrolyte, and contributes to the bonding of the molecular chains of the ether-based polymer with the solvent, so that the electrolyte can be stored in the active material layer. Within the low safe operating temperature range of a secondary battery, the ether-based polymer may become immobile. The ether-based polymer can adhere to the surface of the active material while maintaining the state of locking the electrolyte in the space and environment where the ether-based polymer is located, improve the liquid storage capacity of the active material layer, and enhance the impregnation of the electrolyte into the active material layer. As a result, the cycling performance of the secondary battery using the ether-based polymer can be improved.

[0050] In the present application, by increasing the temperature, within the safe operating temperature range of the battery cell, the molecular chains of the ether-based polymer can be unfolded, and the attraction and physical bonding between the molecular chains of the ether-based polymer and the solvent can be promoted. At room temperature, the activity of molecular chain segments of the ether-based polymer decreases, the ether-based polymer adheres to the surface of the active material while keeping the electrolyte locked in the space environment where the ether-based polymer is located, forming an in-situ gel-like state, which improves the liquid storage capacity of the active material and enhances the cycling performance.

[0051] In some embodiments, a sheet-like structure is produced from the ether-based polymer, and the sheet-like structure is subjected to (T m +20)°C to conduct a dynamic frequency scanning test, so as to obtain an elastic modulus G'-loss elastic modulus G'' curve. The slope K of the elastic modulus G'-loss elastic modulus G'' curve satisfies 1 < K < ∞, 1 < K ≤ 100, and optionally 1 < K ≤ 10. T m (°C) represents the melting temperature of the ether-based polymer.

[0052] Specifically, the manufacturing process of the sheet-like structure is as follows. The polymer is vacuum-dried at 80°C for 12 h. The dried polymer is hot-rolled into a sheet by a flat plate vulcanizer, wherein the hot-rolling temperature is (T m +20)°C, the rolling thickness is 1 to 2 mm, the rolling time is 2 min, and the rolling pressure is 8 MPa. After rolling for 2 min, the sample is taken out, placed on another vulcanizer of the same model and cold-rolled, wherein 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 fixed size. For example, the sheet-like structure may be a wafer with a thickness of 1 to 2 mm and a diameter of 25 mm, and may also be manufactured according to the standard sample specifications required by the test equipment.

[0053] According to the conclusion of classical linear viscoelasticity, for polymers, especially linear polymers, the elastic modulus G'-loss modulus G'' in the terminal region (the range where the angular velocity is close to the maximum value) of the elastic modulus G'-loss modulus G'' curve conforms to the frequency dependence, and the longest chain of the polymer affects the viscoelastic behavior.

[0054] Specifically, the procedure of the dynamic frequency scanning test is as follows. A dynamic frequency scanning test is performed using a TA-AR 2000EX rotational rheometer (TA Instruments, USA), the diameter of the parallel plate is 25 mm, and the thickness is 0.9 mm. To ensure that the test is carried out in the linear viscoelastic region, the strain during the dynamic frequency scanning test is 2%, and the test temperature is (T m +20)°C, the frequency scanning range of the test is 500rad / s≦w 2 ≦0.05rad / s, so as to obtain data in the low frequency region as much as possible.

[0055] Dynamic frequency scanning tests can characterize the degree of entanglement between molecular chains during solid-phase melting (molten state). Compared to linear or short-branched structures, long-branched structures, network-like structures, and low-crosslinking structures exhibit a higher degree of entanglement, showing behavior of detachment from the chain ends, and the polymer exhibits solid-phase behavior. If the polymer according to this application satisfies the above range, it further reduces the entanglement state between molecular chains, contributing to the dispersion of solvent molecules in the electrolyte between 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, reduce the risk of the polymer dissolving in the electrolyte, and improve the stability of the polymer's performance. In addition, 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.

[0056] In some embodiments, the glass transition temperature Tg of the ether polymer is in °C, -100 ≤ Tg ≤ 50, and optionally -80 ≤ Tg ≤ 30.

[0057] The glass transition temperature is the transition temperature at which the movement of the chain segments of an ether polymer changes from freezing to unfreezing. The glass transition temperature has some influence on the flexibility of the molecular chains of the ether polymer; that is, the lower the glass transition temperature, the better the flexibility of the molecular chains of the ether polymer at room temperature, while the higher the glass transition temperature, the worse the flexibility of the molecular chains at room temperature. The glass transition temperature can be measured by differential scanning calorimetry (DSC), and the measurement procedure is as follows: A 0.5g to 0.8g sample is placed in a crucible and, under a nitrogen gas atmosphere, the sample is subjected to a temperature rise and fall treatment at a heating rate of 10°C / min, from an initial temperature 20°C lower than the material's intrinsic Tg to a cutoff temperature 20°C higher than the material's intrinsic Tm. During the treatment, the actual glass transition temperature Tg and melt temperature Tm of the material are determined based on the material's heat absorption / desorption peak values ​​or transition point.

[0058] In ether-based polymers, a lower glass transition temperature results in better flexibility of the molecular chain segments, making adjacent molecular chains more easily cleaved. For example, the glass transition temperature of an ether-based polymer may be in the range of -100°C, -90°C, -80°C, -60°C, -30°C, 0°C, 30°C, 50°C, or any two of the above values.

[0059] In some embodiments, the ether polymer comprises a structural unit represented by formula (I), [ka] 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, and R3 comprises a substituted or unsubstituted C1-C5 methylene group, and 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.

[0060] For example, the ether polymer contains at least one structural unit represented by formula (I-1) to formula (I-8). [ka]

[0061] In some embodiments, the ether polymer comprises a structural unit represented by formula (II), [ka] In formula (II), each of R4 to R7 independently comprises 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 an ether group. Optionally, R4 to R7 each independently contain 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 contains a substituted or unsubstituted C1-C2 alkoxy group or an ether group.

[0062] In some embodiments, the ether polymer comprises at least one structural unit represented by formula (II-1) to formula (II-7). [ka]

[0063] The monomers used in the above-mentioned ether polymers are multi-membered rings, for example, structures with six or fewer members, or short-chain monomers, which contribute to polymerization to form a high-content -O- structure. Such types of structures have a low degree of entanglement, which contributes to improved flexibility of the molecular chain, allowing the molecular chain to fully unfold in the electrolyte, and as a result, the interfacial performance of the active material is further improved.

[0064] The polymers described above are merely some examples of the structural groups of the main molecular chains, and in embodiments of this application, polymers 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.).

[0065] The polymer groups relating to this application can be detected using infrared spectroscopy (IR). Specifically, the polymer is tested using a Thermo Nicolet Nexus 670 attenuated total reflectance-Fourier transform infrared spectrophotometer (FTIR-ATR), and then tested in accordance with GB / T 6040-2002, where the test range is 600-4000 cm⁻¹. -1 The reproducibility is ±2cm. -1 The resolution is 4cm -1 It is higher, with a penetration depth of 0.2–0.6 μm.

[0066] The structure of the polymer relating to this application can be tested by nuclear magnetic resonance (NMR). Specifically, 1H NMR and 13C NMR are performed using a Varian Mercury Plus-400 nuclear magnetic resonance spectrometer, where the test temperature is 20°C, TMS is the internal standard, CDCl3 is the solvent, and the proton resonance frequency is 400 MHz.

[0067] The type of monomer in the polymer relating to this application (particularly applicable to monomers that make up a small proportion of the polymer) can be measured by a pyrolysis gas chromatograph-mass spectrometer, and the measurement steps are specifically as follows: A 0.5 mg sample is accurately weighed and placed in a sample cup, fixed to a supply rod, and then loaded into a pyrolysis meter mounted near the GC (gas chromatograph) supply port. When the temperature of the pyrolysis meter reaches the set temperature, the supply button is pressed to rapidly drop the sample cup into the center of the pyrolysis meter. The volatile components are then instantaneously gasified in an inert gas N2 atmosphere, transported to a gas chromatograph column with a carrier gas for separation, and finally detected using a flame ionization detector (FID) or mass spectrometer (MS) to obtain a gas chromatograph or total ion chromatogram.

[0068] If the above groups are substituted, the substituents may include one or more of the following: nitrile group (-CN), nitro group, sulfonyl group, carboxyl group, ester group, chlorine atom, fluorine atom, and bromine atom. The above substituents are high-pressure resistant substituents and further contribute to the stabilization of the polymer structure.

[0069] In some embodiments, n is chosen from positive integers between 1500 and 25000.

[0070] n is an optional positive integer chosen from 3000 to 18000.

[0071] In some embodiments, the molecular weight of the polymer is 1.2 × 10⁻⁶. 5 g / mol ~ 1.0 × 10 6It is g / mol.

[0072] When the molecular weight of the polymer is within the above range, it is possible to ensure that the polymer dissolves to some extent in the electrolyte while being difficult to completely dissolve or disperse in the electrolyte, making it easier to control the distribution and dispersion on the surface of the active material. Furthermore, the flexibility between the molecular chains of the polymer is further increased, the forces between the molecular chains are weakened, and solvent molecules in the electrolyte contribute to cleaving the molecular chains and entering between them, becoming encapsulated within the molecular chains. As a result, active ions can more easily enter the active material via the solvent and move smoothly and rapidly. For example, the molecular weight of the polymer is 1.2 × 10⁻⁶. 5 g / mol, 2 × 10⁻⁶ 5 g / mol, 5 × 10 5 g / mol, 8 × 10 5 g / mol, 1 × 10⁻⁶ 6 It may be g / mol, or a range consisting of any two of the above values.

[0073] The molecular weight of ether polymers is known in this field and can be measured using common equipment and methods in this field. It can be tested by gel permeation chromatography (GPC), and the specific test steps are as follows: Add 20 ml of deionized water to an appropriate amount of sample (a sample concentration sufficient to ensure 8% to 12% light shielding), and simultaneously perform external sonication for 5 minutes (53 kHz / 120 W) to ensure complete dispersion of the sample. Then, measure the sample according to the GB / T19077-2016 / ISO13320:2009 standard.

[0074] Alternatively, the test is performed using a multi-angle laser scattering detector (MALLS), specifically a system (Wyatt Technology Corporation, USA) combining GPC, a Dawn Heleos II multi-angle laser scattering detector, an Optilab T-rEX refractive index (RI) detector, and a Visco Star II viscometer. The test is performed at 30°C with tetrahydrofuran as the mobile phase at a flow rate of 1.0 ml / min, and the SEC-SAMLL data is processed using the commercial software ASTRA6 to obtain molecular weight parameters. Positive electrode sheet

[0075] A second aspect of this application provides a positive electrode sheet comprising a positive electrode current collector and a positive electrode film layer provided on the positive electrode current collector, wherein the positive electrode film layer comprises a positive electrode active material and an ether-based polymer, and the ether-based polymer comprises an ether-based polymer described in any embodiment of the first aspect of this application.

[0076] For example, the positive electrode current collector has two opposing surfaces in the thickness direction, and the positive electrode film layer is provided on one or both of the two opposing surfaces of the positive electrode current collector.

[0077] Electrode sheets can be manufactured by applying a slurry to a current collector, drying it, and cold pressing it. Alternatively, electrode sheets can be derived from battery cells, obtained by disassembling the battery cell, removing the electrode sheet impregnated in electrolyte from the battery cell, and vacuum drying the electrolyte-impregnated electrode sheet for 12 hours under conditions of 100°C. These can be used for testing the electrolyte absorption rate of the electrode sheet.

[0078] Ether polymers can be synthesized by methods such as emulsion polymerization, suspension polymerization, bulk polymerization, and solution polymerization. Alternatively, ether polymers can be derived from battery cells. These can be obtained by disassembling the battery cell, removing the electrode sheet impregnated in the electrolyte, detaching the active material from the electrode sheet from the current collector by external force to prepare a powder sample, adding the prepared powder sample to dimethyl carbonate (DMC), stirring at 80°C and 500 rpm for 8 hours, letting it stand at room temperature for 10 minutes, collecting the supernatant, and drying it at 80°C for 12 hours. The obtained ether polymer may contain small amounts of lithium salt, which have little effect on infrared and precipitation tests. However, to ensure high accuracy, the ether polymer may be further washed with DMC at room temperature to separate the lithium salt.

[0079] In some embodiments, the positive electrode active material layer satisfies the following equation, λ=1-P1 / P2 formula (1) v = π × (d / 2) 2 ×h×(ρ / t) Equation (2) v / λ>1.00 Equation (3) In formulas (1) to (3), λ represents the porosity of the positive electrode active material layer, P1 represents the actual compressed density of the positive electrode active material layer, and its unit is g / cm³. 3 And, P2 represents the true compressible density of the positive electrode active material, and its unit is g / cm³. 3 And, v represents the liquid absorption rate of the positive electrode active material layer, and its unit is mg / s. d represents the diameter of the capillary in the capillary test of the positive electrode active material layer, and its unit is mm. h represents the liquid level height inside the capillary tube, and its unit is mm. ρ represents the density of the electrolyte in the capillary test, and its unit is g / cm³. 3 And, t represents the time it takes for the electrolyte solution in the capillary tube to be absorbed, and its unit is s.

[0080] In this application, the actual compressive density P1 refers to the ratio of the mass to the thickness of the positive electrode active material layer per unit area in the electrode sheet. The actual compressive density is determined by the force of the roll press after coating the electrode sheet, and its unit is g / cm³. 3 The test procedure is as follows: A sample of electrode sheet with a certain area S is taken, the mass M of the positive electrode active material layer is weighed, the thickness D of the positive electrode active material layer is measured, and the actual compressed density is calculated as M / (S×D).

[0081] In this application, the true compressive density P2 refers to the density of the positive electrode active material itself in the positive electrode active material layer, and specifically, in a dense state, it refers to the mass per unit "actual volume of solid material (excluding open and closed pores and interparticle voids)". The true volume V can be determined by test, and the true compressive density can be calculated based on P=m / V and tested in accordance with GB / T24586-2009. The test procedure is as follows:

[0082] 1) Pre-treatment: Place a clean, dry sample cup on a scale, set it to zero, and add the powder sample to the sample cup until it is approximately half the volume of the sample cup. Record the mass of the sample. 2) The true compressible density is calculated by placing the sample cup containing the sample in the true density analyzer, sealing the test system, introducing helium gas according to the program, detecting the gas pressure in the sample chamber and expansion chamber, and then calculating the true volume based on Boyle's Law (PV=nRT).

[0083] Here, the volume of the sample cup is 3.5 cm³. 3 Therefore, the analytical gas is helium gas.

[0084] According to equation (1), the porosity λ of the active material layer can be calculated from the actual compressive density and the true compressive density.

[0085] Specifically, λ = (V1 - V2) / V1 = 1 - V2 / V1 = 1 - (m / V1) / (m / V2) = 1 - P1 / P2 Here, V1 represents the volume of the positive electrode active material layer for mass m, and its unit is cm. 3 And, V2 represents the volume of active particles in the positive electrode active material layer at mass m, and its unit is cm. 3 And, m represents the mass of the positive electrode active material layer, and its unit is g.

[0086] Equation (2) can represent the rate at which a point on the electrode sheet absorbs the liquid (e.g., electrolyte) in the capillary tube almost completely within a unit time. In this application, a point on the electrode sheet means a region of the electrode sheet having a certain area corresponding to the cross-sectional area of ​​the capillary tube.

[0087] In this application, the method for detecting the liquid absorption rate of an electrode sheet is: Using a capillary tube, draw up a predetermined amount of electrolyte solution, The capillary tube is brought into contact with the electrode sheet so that the electrode sheet awaiting measurement absorbs the electrolyte solution inside the capillary tube through capillary action. The method includes recording the liquid level height h of the electrolyte absorbed from the capillary tube after a predetermined time t has elapsed, calculating the amount of electrolyte absorbed based on the liquid level height h and diameter d of the capillary tube and the density ρ of the electrolyte, and quantitatively calculating the absorption rate v of the electrode sheet based on the ratio of the absorbed amount to the predetermined time t.

[0088] For example, 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.

[0089] By having a capillary channel, the capillary does not require a driving force for liquid absorption from an external driving means, and can directly suck the electrolyte solution by capillary action. In this way, when sucking the electrolyte solution by capillary action, the amount of sucked electrolyte can be accurately controlled. On the other hand, since the electrode sheet absorbs the electrolyte solution by its own capillary action, the electrolyte solution in the capillary is sucked out by the electrode sheet only when the electrode sheet waiting for measurement comes into contact with the capillary, and stops flowing out when the electrode sheet is separated from the capillary. Therefore, it is possible to accurately reflect that the electrode sheet has absorbed a corresponding volume of electrolyte according to the absorbed amount of electrolyte in the capillary, further improve the accuracy of test results, and quantitatively calculate the absorption rate of the electrolyte solution by the electrode sheet.

[0090] In the present application, a test is carried out using a standard electrolyte solution as a test sample, and for the specific blending components of the electrolyte solution, reference can be made to the blending components of the electrolyte solution in the examples.

[0091] Formula (3) shows the liquid absorption rate of the electrode sheet at a porosity λ, and can be used to represent the liquid absorption rate of the electrode sheet.

[0092] The ether-based polymer according to the present application is introduced in the manufacturing process of the active material layer, can uniformly form regions with high impregnation inside the active material layer, uniformly improves the impregnation property of the active material layer, improves the liquid absorption rate of the entire active material layer, and as a result, improves the cycle performance of a battery cell using the electrode sheet.

[0093] Optionally, 1.00<v / λ<50.00.

[0094] 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. For example, 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.

[0095] In some embodiments, based on the mass of the positive electrode active material layer, the mass content A (%) of the ether polymer is 0.1 ≤ A ≤ 1.5.

[0096] When the mass content of the ether-based polymer is within the above range, the interfacial performance of the positive electrode active material layer can be significantly improved. For example, the mass content of the ether-based polymer may be in the range of 0.1%, 0.2%, 0.5%, 0.8%, 1.0%, 1.2%, 1.5%, or any two of the above values.

[0097] The positive electrode film layer includes a positive electrode active material, and as the positive electrode active material, a positive electrode active material for battery cells known in the art can be used. For example, the positive electrode active material may include at least one of the following materials: layered positive electrode active materials (e.g., ternary materials, lithium nickelate / sodium, lithium cobaltate / sodium, lithium manganate / sodium, lithium-rich / sodium-rich layered and rock salt phase layered materials), olivine-type phosphate active materials, and spinel-structured positive electrode active materials (e.g., spinel lithium manganate, spinel nickel manganate, lithium-rich spinel lithium manganate, and nickel manganate).

[0098] For example, the general formula for a layered cathode active material is Li x A y Ni a Co b Mn c M (1-a-b-c) Y zThe equation is given by 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, 1.8≦z≦3.5, A is one or more selected from Na, K, and Mg, M is one or more 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 selected from O and F. Optionally, y=0. Specifically, the layered cathode active materials are lithium cobalt oxide (LCO), lithium nickel oxide (LNO), lithium manganese oxide (LMO), and 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 contain one or more types of O2(NCM523).

[0099] For example, the general formula for olivine-type phosphate active material is Li x A y Me a M b P 1-c X c Y zIn the formula, 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 selected from Na, K, and Mg, Me is one or more selected from Mn, Fe, Co, and Ni, M is one or more 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 selected from S, Si, Cl, B, C, and N, and Y is one or more selected from O and F. Specifically, the olivine-type phosphate active material includes one or more of LiFePO4, LiMnPO4, LiNiPO4, and LiCoPO4.

[0100] For example, the general formula for a positive electrode active material with a spinel structure is Li x A y Mn a M 2-a Y z In the formula, 0≦x≦2, 0≦y≦1, and 0.9≦x+y≦2, 0.5≦a≦2, 3≦z≦5, A is selected from one or more of Na, K, and Mg, M is selected from one or more of 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 selected from one or more of O and F. Specifically, the positive electrode active material of the 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 Contains one or more types of Mn2O4.

[0101] In some embodiments, a metal foil or a composite current collector can be used as the positive electrode current collector. Examples of metal foils include aluminum foil and aluminum alloy foil. The composite current collector may include a polymer material substrate and a metal material layer formed on at least one surface of the polymer material substrate. For example, the metal material may include one or more combinations selected from aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys, and the polymer material substrate may include one or more combinations selected from polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0102] In some embodiments, the cathode film layer optionally further comprises a cathode conductive agent. In this application, the type of cathode conductive agent is not particularly limited, and for example, the cathode conductive agent includes one or more selected from superconducting carbon, conductive carbon black, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. In some embodiments, the mass content of the cathode conductive agent is 5% or less based on the total mass of the cathode film layer.

[0103] In some embodiments, the positive electrode film layer optionally further comprises a positive electrode adhesive. In this application, the type of positive electrode adhesive is not particularly limited, and for example, the positive electrode adhesive includes one or more selected from polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylic ester resins. In some embodiments, the mass content of the positive electrode adhesive is 5% or less based on the total mass of the positive electrode film layer.

[0104] The positive electrode film layer is generally formed by applying a positive electrode slurry onto a positive electrode current collector, drying the slurry, and performing cold pressing. The positive electrode slurry is generally formed by dispersing a positive electrode active material, an optional conductive agent, an optional adhesive and other optional components in a solvent and uniformly stirring the mixture. The solvent may be N-methylpyrrolidone (NMP), but is not limited thereto.

[0105] Negative electrode sheet A third aspect of the present application provides a negative electrode sheet comprising a negative electrode current collector and a negative electrode film layer provided on the negative electrode current collector, wherein the negative electrode film layer comprises a negative electrode active material and an ether-based polymer, and the ether-based polymer comprises the ether-based polymer described in any one of the embodiments of the first aspect of the present application.

[0106] For example, the negative electrode current collector has two surfaces opposing each other in its thickness direction, and the negative electrode film layer is provided on either one or both of the two opposing surfaces of the negative electrode current collector.

[0107] In some embodiments, the negative electrode active material layer satisfies the following formula: v / λ>1.00 Formula (4) In formula (4): λ represents the porosity of the negative electrode active material layer; v represents the liquid absorption rate of the negative electrode active material layer, and the unit thereof is mg / s.

[0108] For the detection methods of λ and v, they are as described in the section regarding the positive electrode active material layer, and will not be repeated herein.

[0109] In some embodiments, 3.00<v / λ<50.00, and optionally 3.40≦v / λ≦30.00. For example, 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 composed 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 content B (%) of the ether-based polymer is 0.2 ≤ B ≤ 5.0.

[0111] When the mass content of the ether-based polymer is within the above range, the interfacial performance of the negative electrode active material layer can be significantly improved. For example, the mass content of the ether-based polymer may be in the range of 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 any two of the above values.

[0112] In some embodiments, a metal foil or a composite current collector can be used as the negative electrode current collector. Copper foil can be used as an example of a metal foil. A composite current collector may include a polymer material substrate and a metal layer formed on at least one surface of the polymer material substrate. A composite current collector may be formed by providing a metal material (e.g., copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys) on a polymer material substrate (e.g., a substrate such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE)).

[0113] In some embodiments, negative electrode active materials known in the art for battery cells can be used as negative electrode active materials. For example, the negative electrode active material may include at least one of natural graphite, artificial 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 oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloy materials. The tin-based material may be at least one selected from elemental tin, tin oxide compounds, and tin alloy materials. This application is not limited to these materials, and other conventional materials usable as negative electrode active materials for batteries may be used. These negative electrode active materials may be used individually or in combination of two or more.

[0114] In some embodiments, the negative electrode film layer optionally further comprises a negative electrode adhesive. The negative electrode adhesive 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), polymethyl methacrylate (PMAA), and carboxymethyl chitosan (CMCS).

[0115] In some embodiments, the negative electrode film layer optionally further comprises a conductive agent. The conductive agent may be at least one selected from superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0116] In some embodiments, the negative electrode film layer may optionally further contain other additives such as a thickening agent (e.g., sodium carboxymethylcellulose (CMC-Na)).

[0117] In some embodiments, a negative electrode sheet can be manufactured by the following method: A negative electrode sheet can be manufactured by dispersing the above-mentioned components for manufacturing a negative electrode sheet, such as a negative electrode active material, the ether-based polymer, a conductive agent, an adhesive, and other optional components in a solvent (e.g., deionized water) to form a negative electrode slurry, applying this negative electrode slurry onto a negative electrode current collector, drying it, and performing processes such as cold pressing.

[0118] battery cell A fourth aspect of this application provides a battery cell comprising a positive electrode sheet, a negative electrode sheet, and a separator provided between the positive electrode sheet and the negative electrode sheet. The battery cell may be a lithium-ion battery or the like.

[0119] In some embodiments, the positive electrode sheet may be a positive electrode sheet according to any embodiment of the second aspect of this application, thereby improving the cycle performance of the battery cell. A conventional negative electrode sheet may be used as the negative electrode sheet.

[0120] In some other embodiments, the negative electrode sheet may be a negative electrode sheet according to any embodiment of the third aspect of this application, thereby improving the cycle performance of the battery cell. A conventional positive electrode sheet may be used as the positive electrode sheet.

[0121] In yet another embodiment, the positive electrode sheet may be a positive electrode sheet according to any embodiment of the second aspect of this application, and the negative electrode sheet may be a negative electrode sheet according to any embodiment of the third aspect of this application, thereby improving the cycle performance of the battery cell.

[0122] [Electrolyte] The battery cell further includes an electrolyte that plays a role in conducting ions between the positive electrode sheet and the negative electrode sheet. The type of electrolyte is not particularly limited in this application and may be selected according to the needs. For example, the electrolyte may be liquid, gel-like, or all-solid.

[0123] In some embodiments, an electrolyte solution is used as the electrolyte. The electrolyte solution comprises an electrolyte salt and a solvent.

[0124] For example, the lithium salt may include one or a combination of several selected from lithium hexafluoride phosphate (LiPF6), lithium tetraborate tetrafluoride (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoride arsenate (LiAsF6), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorooxalate borate (LiDFOB), lithium bis(oxalato)borate (LiBOB), lithium difluorophosphate (LiPO2F2), lithium difluorodisoxalate phosphate (LiDFOP), and lithium tetrafluorooxalate phosphate (LiTFOP).

[0125] For example, the organic solvent may include one or a combination of several 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).

[0126] In some embodiments, the electrolyte optionally further comprises additives. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve some performance of the battery, such as the battery's overcharge performance, high-temperature performance, or low-temperature output performance.

[0127] [Separator] In some embodiments, the battery cell further includes a separator. In this application, the type of separator is not particularly limited, and any known porous structure separator having excellent chemical and mechanical stability can be selected.

[0128] In some embodiments, the separator material may include one or more combinations selected from glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may be a single-layer film or a multilayer composite film. If the separator is a multilayer composite film, the materials of each layer may be the same or different.

[0129] In some embodiments, an electrode assembly can be manufactured by performing a winding process or a lamination process on a positive electrode sheet, a separator, and a negative electrode sheet.

[0130] In this application, 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 having a rectangular structure as an example.

[0131] In some embodiments, as shown in Figures 1 and 2, the exterior structure may include a case 51 and a cover plate 53. The case 51 may include a bottom plate and side plates connected to the bottom plate, and the bottom plate and side plates surround and form a housing cavity. The case 51 has an opening that communicates with the housing cavity, and the cover plate 53 covers the opening to seal the housing cavity. The electrode assembly 52 can be manufactured by performing a winding process and / or a lamination process on a positive electrode sheet, a negative electrode sheet, and a separator. The electrode assembly 52 is packaged in the housing cavity. The electrolyte is impregnated into the electrode assembly 52. ​​The number of electrode assemblies 52 contained in the battery cell 5 may be one or more and can be increased or decreased according to the needs.

[0132] The method for manufacturing a battery cell according to this application is a known method. In some embodiments, the battery cell is assembled from a positive electrode sheet, a separator, a negative electrode sheet, and an electrolyte. For example, an electrode assembly can be manufactured by performing a winding process and / or a lamination process on the positive electrode sheet, separator, and negative electrode sheet, then placing this electrode assembly in an outer structure, injecting the electrolyte after drying, and performing processes such as vacuum packaging, settling, chemical conversion, and shaping to manufacture the battery cell.

[0133] In some embodiments of this application, a battery module can be assembled using the battery cells relating to this application. The number of battery cells included in the battery module may be multiple, and can be specifically increased or decreased depending on the application and capacity of the battery module.

[0134] Figure 3 is a schematic diagram of an example battery module 4. As shown in Figure 3, in the battery module 4, the multiple battery cells 5 may be arranged sequentially along the length of the battery module 4. Of course, they may be arranged in any other manner. Furthermore, the multiple battery cells 5 may be fixed together by fasteners.

[0135] Optionally, the battery module 4 may further include a housing having a housing space for accommodating multiple battery cells 5.

[0136] In some embodiments, a battery pack can be assembled using the above-described battery modules. The number of battery modules included in the battery pack can be increased or decreased depending on the application and capacity of the battery pack.

[0137] Both the battery module 4 and the battery pack can be specific examples of the battery of this application.

[0138] Figures 4 and 5 are schematic diagrams of an example battery pack 1. As shown in Figures 4 and 5, the battery pack 1 may include a battery box and a plurality of battery modules 4 provided inside the battery box. The battery box includes an upper housing 2 and a lower housing 3, the upper housing 2 being provided so as to cover the lower housing 3 and forming a sealed space for housing the battery modules 4. The plurality of battery modules 4 may be arranged in any way within the battery box.

[0139] power consumption equipment A fifth aspect of this application provides a power consumption device equipped with at least one of the battery cells, battery modules, and battery packs relating to this application. The battery cells, battery modules, and battery packs may be used as a power source for the power consumption device or as an energy storage means for the power consumption device. The power consumption device may be, but is not limited to, portable devices (e.g., mobile phones, laptop computers, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), trains, ships and satellites, energy storage systems, etc.

[0140] A power consumption device can be configured with a battery cell, battery module, or battery pack depending on its usage needs. Figure 6 is a schematic diagram of an example power consumption device. This power consumption device 6 is a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, etc. To meet the requirements for high output and high energy density of this power consumption device, a battery pack 1 or a battery module can be used. Another example of a power consumption device may be a mobile phone, a tablet computer, a laptop computer, etc. Since such power consumption devices generally require a thin design, a battery cell can be used as the power source.

[0141] Examples The following describes embodiments of this application. The embodiments described below are for illustrative purposes only and should not be understood as limiting this application. Unless otherwise specified, any specific techniques or conditions in the embodiments are the same as those described in the art or in the specifications. Unless the manufacturer is specified, the reagents and equipment used are all commercially available common products.

[0142] Example 1 (1) Manufacturing of positive electrode sheets A 12 μm thick aluminum foil was used as the positive electrode current collector. A positive electrode slurry was prepared by adding an ether-based polymer, LiFePO4 (a positive electrode active material), carbon black (a conductive agent), and polyvinylidene fluoride (PVDF) (an adhesive) to 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 aluminum foil, which served as a current collector, dried at 85°C, then cold-pressed, trimmed, cut, and stripped. Subsequently, a positive electrode sheet was produced by drying under vacuum at 85°C for 4 hours.

[0143] (2) Manufacturing of negative electrode sheets A copper foil with a thickness of 8 μm was used as the negative electrode current collector. A negative electrode slurry was prepared by uniformly mixing an ether polymer, artificial graphite (anode active material), carbon black (conductive agent), styrene-butadiene rubber (SBR) (adhesive), sodium hydroxymethylcellulose (CMC) (thickener), and deionized water in a weight ratio of 2.5:94:0.5:2:1:100. The negative electrode slurry was applied to copper foil (current collector), dried at 85°C, then cold-pressed, trimmed, cut, and stripped, and finally dried under vacuum at 120°C for 12 hours to produce a negative electrode sheet.

[0144] (3) Manufacturing of electrolyte Under conditions with a water content of less than 10 ppm, an electrolyte solvent was prepared by mixing ethylene carbonate (EC) and ethyl methyl carbonate (EMC), both non-aqueous organic solvents, in a volume ratio of 3:7. Subsequently, this mixed solvent was mixed with the lithium salt LiPF6 to produce an electrolyte with a lithium salt concentration of 1 mol / L.

[0145] (4) Manufacturing of lithium-ion batteries 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 so that the separator was positioned between the positive electrode sheet and the negative electrode sheet to provide isolation, and then wound up to create the electrode assembly. The fabricated electrode assembly was placed in an outer case, dried, and then the electrolyte was injected. A lithium-ion battery was manufactured by performing processes such as vacuum packaging, settling, chemical conversion, and shaping.

[0146] Comparative Example 1 In Comparative Example 1, a lithium-ion battery was manufactured in the same manner as in Example 1, except that neither the positive electrode sheet nor the negative electrode sheet contained an ether-based polymer.

[0147] Comparative Example 2 In Comparative Example 2, a lithium-ion battery was manufactured in the same manner as in Example 1, except that the material of the ether-based polymer in the positive electrode sheet and the negative electrode sheet was changed.

[0148] Examples 2 to 4 In Examples 2 to 4, lithium-ion batteries were manufactured in the same manner as in Example 1, except that the material of the ether-based polymer in the positive electrode sheet and the negative electrode sheet was changed.

[0149] Example 5 In Example 5, a lithium-ion battery was manufactured in the same manner as in Example 1, except that the positive electrode sheet contained an ether-based polymer, while the negative electrode sheet did not.

[0150] Examples 6 to 9 In Examples 6 to 9, lithium-ion batteries were manufactured in the same manner as in Example 1, except that the content of the ether-based polymer in the positive electrode sheet was changed.

[0151] Examples 10 to 12 In Examples 10 to 12, lithium-ion batteries were manufactured in the same manner as in Example 1, except that the content of the ether-based polymer in the negative electrode sheet was changed.

[0152] The data for the examples and comparative examples are shown in Table 1.

[0153] Exam Section 1. Testing the capacity retention rate of lithium-ion batteries The lithium-ion batteries manufactured in the examples and comparative examples were charged to 4.25V at room temperature using a multi-stage charging method equivalent to 1.2C (stepcharge), then charged at a constant voltage of 4.25V until the current reached 0.05C, left for 5 minutes, and then discharged to 2.8V at 0.33C. In this case, the obtained capacity was defined as the initial capacity C0, and the initial clamping force of the lithium-ion battery was set to 100,000 (N). The above steps were repeated for the same battery, and the discharge capacity Cn of the battery after the nth cycle was recorded. In this case, the battery capacity retention rate Pn after each cycle was Pn = Cn / C0 * 100%, and by using the values ​​of 200 points including P1, P2...P200 as the vertical coordinate and the corresponding number of cycles as the horizontal coordinate, a graph showing the corresponding battery capacity retention rate and number of cycles for the ether-based polymers in the examples and comparative examples can be obtained.

[0154] In this test process, the first cycle corresponds to n=1, the second cycle to n=2, ... the 200th cycle to n=200. For example, the battery capacity retention rate data corresponding to Example 1 shown in Table 1 is the data measured after 200 cycles under the above test conditions, i.e., the P200 value. The test process for Comparative Example 1 and the other examples is the same as the process described above.

[0155] 2. Testing the DC impedance of lithium-ion batteries The lithium-ion batteries manufactured in the examples and comparative examples were charged to 4.25V at 25°C using a multi-stage charging method equivalent to 1.2C. Further charging was performed at a constant voltage of 4.25V until the current reached 0.05C, after which the batteries were left for 5 minutes and the voltage V1 was recorded. Next, the batteries were discharged at 1 / 3C for 30 seconds, the voltage V2 was recorded, and the internal resistance DCR1 after the first cycle was calculated based on (V2-V1) / 1 / 3C. The above steps were repeated for the same batteries, and simultaneously, the internal resistance DCRn (n=1, 2, 3…200) after the nth cycle was recorded. Using the values ​​of 200 points, including DCR1, DCR2, DCR3…DCR200, as the vertical coordinate and the corresponding cycle number as the horizontal coordinate, a graph showing the corresponding battery discharge DCIR and cycle number for the ether-based polymers in the examples and comparative examples was obtained.

[0156] In this test process, the first cycle corresponds to n=1, the second cycle to n=2, and so on, until the 200th cycle corresponds to n=200. For example, as shown in Table 1, the rate of increase in the internal resistance of the battery in Example 1 is (DCRn - DCR1) / DCR1 * 100%, and the test process for Comparative Example 1 and the other examples is the same as the process described above. The data shown in Table 1 were measured after 200 cycles under the above test conditions.

[0157] Test results [Table 1]

[0158] In Table 1, 100% oxirane means that the mass content of oxirane is 100%, based on the total mass of monomer 1 and monomer 2.

[0159] 80% oxirane means that the mass content of oxirane is 80% based on the total mass of monomer 1 and monomer 2, and 20% oxirane-2-ethyl carboxylate means that the mass content of oxirane-2-ethyl carboxylate is 20% based on the total mass of monomer 1 and monomer 2.

[0160] According to Table 1, compared to Comparative Example 1, the embodiment of this application improves the cycle performance of the lithium-ion battery by adding the ether-based polymer according to this application to the positive electrode sheet and / or negative electrode sheet. Compared to Comparative Example 2, in the embodiment of this application, when 5 ≤ m / n ≤ 1000, and especially when 10 ≤ m / n ≤ 50 is satisfied, the arrangement of molecular chains tends to become sparser, the forces acting between molecular chains are small, adjacent molecular chains are easily cleaved, and a highly flexible molecular chain structure is formed by segmental motion due to intramolecular rotation, and as a result, the cycle performance of the lithium-ion battery can be significantly improved.

[0161] While this application has been described above with reference to preferred embodiments, various modifications and replacements of components are possible without departing from the spirit of this application. In particular, the technical features described in each embodiment can be combined in any way, provided that there is no structural inconsistency. This application is not limited to the specific embodiments disclosed herein, but includes all technical ideas included in the claims. [Explanation of symbols]

[0162] 1 Battery pack, 2 Upper housing, 3 Lower housing, 4 Battery module, 5 Battery cell, 51 Case, 52 Electrode assembly, 53 Cover plate, 6 Power consumption device.

Claims

1. An ether-based polymer used in battery cells, The ether-based polymer is added to the first solvent at 45°C to form an ether-based polymer system. The ether-based polymer system is left to stand at 45°C for 8 hours, then at 25°C for 24 hours or more, and then filtered through a 200-mesh filter. The remaining filtrate is taken as the first substance. The ether polymer has a mass n in units of g, the mass m of the first substance has a mass m in units of g, and the ether polymer and the first substance satisfy 5 ≤ m / n ≤ 1000.

2. The ether-based polymer according to claim 1, wherein 10 ≤ m / n ≤ 1000, and optionally 10 ≤ m / n ≤ 50.

3. The first solvent includes a cyclic carbonate solvent and / or a linear carbonate solvent. The cyclic carbonate solvent may optionally include one or more of the following: ethylene carbonate (EC), vinylene carbonate (VC), fluoroethylene carbonate (FEC), difluoroethylene carbonate (DFEC), vinylethylene carbonate (VEC), and dioctyl carbonate (CC). The ether polymer according to claim 1 or 2, wherein the linear carbonate solvent optionally comprises one or more of dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), diphenyl carbonate (DPC), methyl allyl carbonate (MAC), and polycarbonate (VA).

4. A sheet-like structure is manufactured from the ether-based polymer, and (T m By performing a dynamic frequency scanning test at +20°C, an elastic modulus G'-loss elastic modulus G'' curve is obtained, and the slope K of the elastic modulus G'-loss elastic modulus G'' curve is 1 < K < ∞, T m The ether-based polymer according to any one of claims 1 to 3, wherein (°C) represents the melting temperature of the ether-based polymer.

5. The ether polymer according to any one of claims 1 to 4, wherein the glass transition temperature Tg of the ether polymer is in °C, -100 ≤ Tg ≤ 50, and optionally -80 ≤ Tg ≤ 30.

6. The ether-based polymer comprises a structural unit represented by formula (I), 【Chemistry 1】 In formula (I), R 1 and R 2 Each independently comprises a hydrogen atom, a substituted or unsubstituted C1-C3 alkyl group, or a substituted or unsubstituted C1-C3 alkoxy group, R 3 It contains substituted or unsubstituted C1-C5 methylene groups, Optional, R 1 and R 2 Each independently comprises a hydrogen atom, a substituted or unsubstituted C1-C2 alkyl group, and / or R 3 The ether polymer according to any one of claims 1 to 5, comprising single-bonded, substituted, or unsubstituted C1 to C4 methylene groups.

7. The ether polymer according to claim 6, wherein the ether polymer comprises at least one structural unit represented by formula (I-1) to formula (I-8). 【Chemistry 2】

8. The aforementioned ether-based polymer includes a structural unit represented by formula (II), 【Transformation 3】 In formula (II), R 4 to R 7 each independently represent 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 to R 7 comprises at least one selected from a substituted or unsubstituted C1 to C3 alkoxy group or an ether group, Optional, R 4 ~R 7 Each independently comprises 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 The ether polymer according to any one of claims 1 to 7, wherein at least one of the groups comprises a substituted or unsubstituted C1-C2 alkoxy group or an ether group.

9. The ether polymer according to claim 8, wherein the ether polymer comprises at least one of the structural units represented by formula (II-1) to formula (II-7). 【Chemistry 4】

10. n is selected from a positive integer between 1500 and 25000, and / or The molecular weight of the ether polymer is 1.2 × 10⁻⁶. 5 g / mol~1.0×10 6 An ether-based polymer according to any one of claims 6 to 9, wherein the concentration is g / mol.

11. A positive electrode sheet comprising a positive electrode current collector and a positive electrode film layer provided on the positive electrode current collector, The positive electrode film layer comprises a positive electrode active material and an ether-based polymer, wherein the ether-based polymer comprises the ether-based polymer described in any one of claims 1 to 10, in a positive electrode sheet.

12. A negative electrode sheet comprising a negative electrode current collector and a negative electrode film layer provided on the negative electrode current collector, The negative electrode film layer comprises a negative electrode active material and an ether-based polymer, wherein the ether-based polymer comprises the ether-based polymer described in any one of claims 1 to 10, in a negative electrode sheet.

13. A battery cell comprising a positive electrode sheet and a negative electrode sheet, The positive electrode sheet includes and / or the positive electrode sheet described in claim 11. The battery cell wherein the negative electrode sheet includes the positive electrode sheet described in claim 12.

14. A battery comprising the battery cell described in claim 13.

15. A power consumption device comprising the battery described in claim 14.

Images