Positive electrode sheet, battery, and power using device

Abstract

The application relates to a positive electrode tab, a battery and a power utilization device. The positive electrode tab comprises a positive electrode current collector and a positive electrode film layer arranged on at least one side of the positive electrode current collector, the positive electrode film layer comprising a positive electrode active material and a lyophilic polymer, the coating weight of the positive electrode film layer being greater than or equal to 300 mg / 1540.25 mm 2 .

Description

Technical Field

[0001] This application relates to a positive electrode, a battery, and an electrical device. Background Technology

[0002] Batteries have the characteristics of high capacity and long life, so they are widely used in electronic devices such as mobile phones, laptops, electric vehicles, electric cars, electric airplanes, electric ships, electric toy cars, electric toy ships, electric toy airplanes, and power tools, etc.

[0003] As batteries are used in a wider range of applications, the requirements for battery performance are becoming increasingly stringent. However, it is difficult to simultaneously improve cycle performance, power performance, and energy density, and further improvements are needed. Summary of the Invention

[0004] This application is made in view of the above-mentioned issues, and its purpose is to provide a positive electrode, a battery, and an electrical device.

[0005] In a first aspect, this application provides a positive electrode sheet, which includes a positive current collector and a positive electrode film layer disposed on at least one side of the positive current collector. The positive electrode film layer includes a positive active material and a hydrophilic polymer, and the coating weight of the positive electrode film layer is ≥300mg / 1540.25mm. 2 .

[0006] Therefore, according to the embodiments of this application, the coating weight of the positive electrode film is relatively high, resulting in a high energy density of the battery cell. However, due to the high coating weight and thickness, the polarization phenomenon at the positive electrode film is intensified, and the path for lithium ions to insert into or extract from the positive electrode active material is longer, leading to higher internal resistance and poorer power performance and cycle life. In contrast, the embodiments of this application add a hydrophilic polymer to the positive electrode film. The hydrophilic polymer has a high affinity with the electrolyte, which can improve the wetting rate of the electrolyte on the positive electrode film, reduce polarization, and mitigate interfacial side reactions, thereby improving cycle life. Since the hydrophilic polymer is configured to coat the electrolyte on the surface of the positive electrode active material particles, effective liquid storage points are formed on the surface of the positive electrode active material particles, thereby accelerating the migration rate of lithium ions and improving the power performance of the battery cell. Therefore, the embodiments of this application can simultaneously improve cycle performance, power performance, and energy density.

[0007] In some embodiments, the coating weight of the positive electrode film is 300 mg / 1540.25 mm. 2 Up to 500mg / 1540.25mm 2 .

[0008] In some embodiments, the positive electrode active material includes lithium phosphate; optionally, based on the total mass of the positive electrode active material, the mass content of lithium phosphate is ≥90%; further optionally, the coating weight of the positive electrode film layer is ≥400mg / 1540.25mm. 2 ; 400mg / 1540.25mm is optional. 2 Up to 500mg / 1540.25mm 2 Lithium-containing phosphates are the main active material for the positive electrode, resulting in a relatively high coating weight for the positive electrode film and a high energy density for the battery cell. The combination of lithium-containing phosphates can improve cycle life and power performance.

[0009] In some embodiments, the lithium-containing phosphate includes at least one of lithium iron phosphate, lithium manganese phosphate, lithium manganese iron phosphate, lithium nickel phosphate, lithium cobalt phosphate, and their respective modified compounds.

[0010] In some embodiments, the positive electrode active material includes a lithium-containing transition metal oxide; optionally, based on the total mass of the positive electrode active material, the mass content of the lithium-containing transition metal oxide is ≥90%. Further optionally, the coating weight of the positive electrode film is ≥300 mg / 1540.25 mm. 2 ; 300mg / 1540.25mm is optional. 2 Up to 500mg / 1540.25mm 2 Lithium-containing transition metal oxides are the main materials for positive electrode active materials, resulting in relatively high coating weight of the positive electrode film and high energy density of the battery cell. The combination of lithium-containing transition metal oxides and lithium-containing phosphates can improve cycle life and power performance.

[0011] In some embodiments, the lithium transition metal oxide includes at least one of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and their respective modified compounds.

[0012] In some embodiments, the mass content of the hydrophilic polymer is ≤5% based on the total mass of the positive electrode film; alternatively, the mass content of the hydrophilic polymer is ≤1%. When the mass content of the hydrophilic polymer is within the above range, the hydrophilic polymer, in combination with the positive electrode active material with a high coating weight, can form multiple liquid storage sites on the surface of the positive electrode active material particles, thereby improving the liquid storage capacity of the positive electrode film and improving the wettability of the electrolyte to the positive electrode active material in the positive electrode film, which is beneficial to improving the cycle performance and power performance of the battery cell.

[0013] In some embodiments, the positive electrode film layer includes multiple sublayers, with the coating weight of each sublayer decreasing progressively in the direction from the positive electrode current collector to the positive electrode film layer. This differentiated coating weight approach for the multiple sublayers helps to improve the polarization phenomenon of the positive electrode film layer and enhances the cycle performance of the battery cell.

[0014] In some embodiments, the multilayer sublayer includes a first layer and a second layer, the first layer being disposed on the surface of the positive current collector, the second layer being located on the side of the first layer away from the positive current collector, and the coating weight of the first layer being greater than the coating weight of the second layer.

[0015] In some embodiments, the mass content of the hydrophilic polymer in the first layer is greater than that in the second layer. When the mass content of the hydrophilic polymer is within the above range, the hydrophilic polymer can form multiple liquid storage sites on the surface of the positive electrode active material particles in each layer, thereby improving the liquid storage capacity of each layer and improving the wettability of the electrolyte to the positive electrode active material in the positive electrode film layer, which is beneficial to improving the cycle performance and power performance of the battery cell.

[0016] In some embodiments, the lyophilic polymer includes a fluorinated polymer, the crystallinity of which, as determined by differential scanning calorimetry, is Xc1%, where 0 < Xc1 ≤ 28.

[0017] The melting temperature of fluoropolymers is T m1 ℃, 0 < T m1 ≤130;

[0018] Further, optionally, the glass transition temperature of the fluorinated polymer is T. g1 ℃, -30≤T g1 ≤40;

[0019] Alternatively, the fluorinated polymer may include at least one of the compounds represented by formula (A1) to formula (AIII).

[0020]

[0021] In equations (AI) and (AII), R 11 R 12 R 13 and R 14 Each independently comprises a hydrogen atom, a fluorine atom, a chlorine atom, a bromine atom, a substituted or unsubstituted C1-C3 alkyl group, or a substituted or unsubstituted C1-C3 alkoxy group, and R 11 R 12 R 13 and R 14 At least one of them contains a fluorine atom;

[0022]

[0023] In equation (AIII), R 15 Includes single-bonded, substituted or unsubstituted C1-C3 alkyl groups;

[0024] p is a positive integer from 1 to 3;

[0025] n is a positive integer selected from 1000 to 30000.

[0026] Therefore, the fluorinated polymers in the embodiments of this application have relatively low crystallinity, melting temperature or glass transition temperature. Fluorinated polymers have a certain degree of activity above the glass transition temperature. Under the action of external force, they can buffer external energy through chain segment movement, which manifests a certain degree of flexibility. This can improve the problem of increased brittleness of the positive electrode sheet caused by thick coating. Furthermore, during the cycling process of the positive electrode sheet, it can act as a buffer for the charging and discharging process of the positive electrode active material, thereby improving cycle expansion and enhancing cycle performance.

[0027] In some embodiments, the hydrophilic polymer includes an ether polymer, which is formed into a sheet-like structure; the sheet-like structure is in (T m2 The elastic modulus G' - energy dissipation modulus G” curve was obtained by dynamic frequency scanning test at +20℃. The slope of the elastic modulus G' - energy dissipation modulus G” curve is K1, 1<K1<∞, T m2 ℃ represents the melting temperature of the ether polymer; optionally, 1 < K1 ≤ 100; further optionally, 1 < K1 ≤ 10;

[0028] Optionally, the glass transition temperature of the ether polymer is T. g2 ℃, -20≤T g2 ≤35;

[0029] Further optionally, the ether polymer includes at least one of the compounds shown in formula (BI) and formula (BII).

[0030]

[0031] In formula (BI), R 21 and R 22 Each independently comprises a hydrogen atom, a substituted or unsubstituted C1-C3 alkyl group, or a substituted or unsubstituted C1-C3 alkoxy group; R 23 Including substituted or unsubstituted C1-C5 alkylene groups;

[0032]

[0033] In formula (BII), R 24 To R 27Each 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 R 24 To R 27 At least one of them contains a substituted or unsubstituted C1-C3 alkoxy or ether group;

[0034] The degree of polymerization n of ether polymers is selected from positive integers from 1500 to 25000.

[0035] Therefore, when the ether polymer of this application meets the above-mentioned range, it can further reduce the molecular chain entanglement state, which is beneficial to the diffusion of solvent molecules in the electrolyte between molecular chains; and the ether polymer still maintains a certain molecular chain entanglement state, which can effectively store electrolyte and improve the cycle performance of battery cells.

[0036] In some embodiments, the hydrophilic polymer includes an ester polymer, which is formed into a sheet-like structure; the sheet-like structure is in (T m3 The elastic modulus G' - energy dissipation modulus G” curve was obtained by dynamic frequency scanning test at +20℃. The slope of the elastic modulus G' - energy dissipation modulus G” curve is K2, 1<K2<∞, T m3 ℃ represents the melting temperature of the ester polymer; optionally, 1 < K2 ≤ 100; further optionally, 1 < K2 ≤ 10;

[0037] Optionally, the glass transition temperature of the ester polymer is T. g3 ℃, -20≤T g3 ≤35;

[0038] Further, optionally, the ester polymer includes at least one of the compounds shown in formula (CI) to formula (CIII).

[0039]

[0040] In formula (CI), R 31 R 32 and R 33 Each independently comprises a hydrogen atom, or a substituted or unsubstituted C1-C8 alkyl group; R 34 Including substituted or unsubstituted C1-C8 alkyl groups, or substituted or unsubstituted C1-C8 hydroxyalkyl groups;

[0041]

[0042] In formula (CII), R 35 Includes substituted or unsubstituted C2-C6 methylene groups; optionally, R 35 Each independently includes substituted or unsubstituted C2-C4 methylene groups;

[0043]

[0044] In equation (CIII), R 36 R 37 and R 38 Each independently comprises a hydrogen atom, or a substituted or unsubstituted C1-C8 alkyl group; R 39 Including substituted or unsubstituted C1-C8 alkyl groups;

[0045] Optionally, R 36 R 37 and R 38 Each independently comprises a hydrogen atom and a substituted or unsubstituted C1-C4 alkyl group;

[0046] The degree of polymerization n of ester polymers is selected from positive integers from 800 to 20000.

[0047] Therefore, when the ester polymers of this application meet the above-mentioned range, the molecular chain entanglement state can be further reduced, which is beneficial to the diffusion of solvent molecules in the electrolyte between molecular chains; and the ether polymers still maintain a certain molecular chain entanglement state, which can effectively store electrolyte and improve the cycle performance of battery cells.

[0048] In some embodiments, the hydrophilic polymer includes an aldehyde-ketone polymer, which is formed into a sheet-like structure; the sheet-like structure is in (T m4 The elastic modulus G' - energy dissipation modulus G” curve was obtained by dynamic frequency scanning test at +20℃. The slope of the elastic modulus G' - energy dissipation modulus G” curve is K3, 0.8≤K3<∞, T m4 °C represents the melting temperature of the aldehyde-ketone polymer; optionally, 0.8 ≤ K3 ≤ 100; further optionally, 0.8 ≤ K3 ≤ 10;

[0049] Optionally, the glass transition temperature of the aldehyde-ketone polymer is T. g4 ℃, -20≤T g4 ≤35;

[0050] Further, optionally, the aldehyde-ketone polymer includes at least one of the compounds shown in formula (DI) and formula (DII).

[0051]

[0052] In formula (DI), R 41 Including single-bonded, substituted, or unsubstituted C1-C6 methylene groups; R 42 Includes hydrogen atoms, substituted or unsubstituted C1-C6 alkyl groups;

[0053]

[0054] In formula (DII), R 43 To R 46 Each of these components independently includes 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;

[0055] r and s are each independently selected from integers from 0 to 5, and at least one of r and s is selected from positive integers;

[0056] The degree of polymerization n of aldehyde-ketone polymers is selected from positive integers from 500 to 15000.

[0057] Therefore, when the aldehyde-ketone polymer of this application meets the above-mentioned range, it can further reduce the molecular chain entanglement state, which is beneficial to the diffusion of solvent molecules in the electrolyte between molecular chains; and, the ether polymer still maintains a certain molecular chain entanglement state, which can effectively store electrolyte and improve the cycle performance of battery cells.

[0058] In some embodiments, the molecular weight of the hydrophilic polymer is 2.0 × 10⁻⁶. 5 g / mol up to 1.2 × 10 6 g / mol.

[0059] Secondly, this application proposes a battery that includes a positive electrode as described in any embodiment of the first aspect of this application.

[0060] Thirdly, this application proposes an electrical device including a battery as described in the second aspect of this application. Attached Figure Description

[0061] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the drawings without creative effort.

[0062] Figure 1 This is a schematic diagram of one embodiment of the positive electrode sheet of this application.

[0063] Figure 2 This is a schematic diagram of one embodiment of the battery cell of this application.

[0064] Figure 3 yes Figure 2 An exploded view of the implementation method of the battery cell.

[0065] Figure 4 This is a schematic diagram of one embodiment of the battery module of this application.

[0066] Figure 5 This is a schematic diagram of one embodiment of the battery pack of this application.

[0067] Figure 6 yes Figure 5 An exploded view of an embodiment of the battery pack shown.

[0068] Figure 7 This is a schematic diagram of one embodiment of an electrical device that uses the battery cell of this application as a power source.

[0069] The accompanying drawings may not be drawn to scale.

[0070] The annotations in the attached figures are explained as follows:

[0071] 1. Battery pack; 2. Upper casing; 3. Lower casing; 4. Battery module;

[0072] 5. Battery cell; 51. Housing; 52. Electrode assembly;

[0073] 53. Cover plate;

[0074] 6. Electrical appliances;

[0075] 7. Positive electrode plate; 71. Positive current collector; 721. First layer; 722. Second layer. Detailed Implementation

[0076] The following detailed description, with appropriate reference to the accompanying drawings, specifically discloses embodiments of the positive electrode, battery, and power-consuming device of this application. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided for the purpose of enabling those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0077] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of the particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60 to 120 and 80 to 110 are listed for a specific parameter, it is also expected that ranges of 60 to 110 and 80 to 120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4, and 2 to 5. In this application, unless otherwise stated, the numerical range "a to b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0 to 5" means that all real numbers between "0 and 5" have been listed in this article; "0 to 5" is just a shortened representation of these numerical combinations. In addition, when a parameter is stated as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0078] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0079] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0080] Unless otherwise specified, all steps of this application may be performed sequentially or randomly, preferably sequentially. For example, if the method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, if the method may also 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 it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0081] In the embodiments of this application, the terms "multiple" or "multi-type" refer to two or more kinds.

[0082] The term "alkyl" encompasses both straight-chain and branched alkyl groups. For example, alkyl groups can be C1 to C5 alkyl, C1 to C4 alkyl, C1 to C3 alkyl, or C1 to C2 alkyl. In some embodiments, alkyl groups include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, etc. Additionally, alkyl groups may optionally be substituted. When substituted, the substituents include fluorine atoms.

[0083] The term "alkoxy group" refers to a group in which an alkyl group is bonded to an oxygen atom by a single bond. For example, an alkoxy group can be a C1-C5 alkoxy group, a C1-C3 alkoxy group, or a C1-C2 alkoxy group. In some embodiments, an alkoxy group may include a methoxy group, an ethoxy group, or a propoxy group. Additionally, an alkoxy group may optionally be substituted.

[0084] The term "halogen atom" refers to fluorine atoms, chlorine atoms, bromine atoms, etc.

[0085] The term "hydrogen" refers to 1H (protium, H), 2H (deuterium, D), or 3H (tritium, T). In various embodiments, "hydrogen" may be 1H (protium, H).

[0086] A battery comprises electrode components and an electrolyte. The electrode components include a positive electrode, a negative electrode, and a separator. The positive electrode includes a positive electrode film layer containing positive active material, which provides active ions. The negative electrode includes a negative electrode film layer containing negative active material. The separator is positioned between the positive and negative electrodes, primarily preventing short circuits between them while allowing active ions to pass freely and form a closed circuit. To increase the battery's energy density, the coating weight of the positive electrode film layer can be increased.

[0087] However, as the coating weight increases, the polarization phenomenon at the positive electrode film layer intensifies, and the power performance and cycle life deteriorate significantly, making it difficult to simultaneously improve cycle performance, power performance and energy density.

[0088] In view of the above problems, this application proposes a positive electrode sheet, which includes a positive current collector and a positive electrode film layer disposed on at least one side of the positive current collector. The coating weight of the positive electrode film layer is relatively high, for example, ≥300mg / 1540.25mm. 2 This improves the energy density of individual battery cells. The positive electrode film also includes a hydrophilic polymer, which has a high affinity for the electrolyte, thus enhancing the affinity between the positive electrode and the electrolyte. The hydrophilic polymer stores the electrolyte on the surface of the active material particles of the positive electrode, improving the electrolyte storage capacity of the positive electrode. The wettability of the electrolyte on the film is significantly improved, which can reduce concentration polarization. When the positive electrode is used in a battery, it can significantly improve the power performance and cycle life of the battery.

[0089] The technical solution of this application will now be described in detail.

[0090] Positive electrode sheet

[0091] In a first aspect, this application provides a positive electrode sheet, which includes a positive current collector and a positive electrode film layer disposed on at least one side of the positive current collector. The positive electrode film layer includes a positive active material and a hydrophilic polymer, and the coating weight of the positive electrode film layer is ≥300mg / 1540.25mm. 2 .

[0092] The coating weight of the positive electrode film is relatively high, resulting in a high energy density for the battery cell. However, due to the high coating weight and thickness, polarization at the positive electrode film is intensified, and the path for lithium ions to insert into or extract from the positive electrode active material is longer, leading to higher internal resistance and poorer power performance and cycle life. In this embodiment, a hydrophilic polymer is added to the positive electrode film. The hydrophilic polymer has a high affinity for the electrolyte, which can improve the wetting rate of the electrolyte on the positive electrode film, reduce polarization, and mitigate interfacial side reactions, thereby improving cycle life. Since the hydrophilic polymer is configured to coat the electrolyte on the surface of the positive electrode active material particles, effective electrolyte storage points are formed on the surface of the particles, thereby accelerating the migration rate of lithium ions and improving the power performance of the battery cell.

[0093] Therefore, the embodiments of this application can simultaneously improve cycle performance, power performance and energy density.

[0094] In this embodiment, the coating weight of the positive electrode film layer has a meaning known in the art and can be tested using equipment and methods known in the art. For example, take a positive electrode sheet that has been coated on one side and cold-pressed (if it is a positive electrode sheet coated on both sides, the positive electrode film layer on one side can be wiped off first), cut it into a small circular piece with an area of ​​S1, weigh it, and record its weight as M1. Then wipe off the positive electrode film layer of the above-weighed positive electrode sheet, weigh the positive current collector, and record it as M0. The coating weight of the positive active material layer = (weight of the positive electrode sheet M1 - weight of the positive current collector M0) / S1.

[0095] In the embodiments of this application, the coating weight of the positive electrode film is relatively high, for example, ≥300mg / 1540.25mm. 2 ; 300mg / 1540.25mm is optional. 2 Up to 500mg / 1540.25mm 2 The coating weight of the positive electrode film can be 300 mg / 1540.25 mm. 2 310mg / 1540.25mm 2 320mg / 1540.25mm 2 330mg / 1540.25mm 2 340mg / 1540.25mm 2 350mg / 1540.25mm2 360mg / 1540.25mm 2 370mg / 1540.25mm 2 380mg / 1540.25mm 2 390mg / 1540.25mm 2 400mg / 1540.25mm 2 410mg / 1540.25mm 2 420mg / 1540.25mm 2 430mg / 1540.25mm 2 440mg / 1540.25mm 2 450mg / 1540.25mm 2 460mg / 1540.25mm 2 470mg / 1540.25mm 2 480mg / 1540.25mm 2 490mg / 1540.25mm 2 500mg / 1540.25mm 2 Or a range consisting of any two of the above values.

[0096] In some embodiments, the positive electrode active material may include, but is not limited to, at least one of lithium phosphate and lithium transition metal oxide and their respective modified compounds. The modified compound may be doped or coated. Doping modification may involve adding a dopant element, such as a transition metal, to the compound. Coating modification may involve surface coating with materials such as carbon, i.e., forming a carbon coating layer on the outer surface of the particles.

[0097] In the embodiments of this application, when the mass content of lithium phosphate is ≥90% based on the total mass of the positive electrode active material, lithium phosphate is used as the main material of the positive electrode active material, and the positive electrode active material is defined herein as a lithium phosphate system; in this case, the mass content of lithium phosphate can reach 100%.

[0098] Examples of lithium phosphates may include, but are not limited to, at least one of lithium iron phosphate, lithium iron phosphate and carbon composites, lithium manganese phosphate, lithium manganese phosphate and carbon composites, lithium manganese iron phosphate, lithium manganese iron phosphate and carbon composites, lithium nickel phosphate, lithium cobalt phosphate, and their respective modified compounds.

[0099] In some embodiments, lithium phosphates include those with the molecular formula L x A y Me a M b P 1-c X cY z Compounds and their modified compounds, wherein 0.5≤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; L includes one or more of Li and Na; A includes one or more of Na, K, and Mg; Me includes one or more of Mn, Fe, Co, and Ni; M includes one or more of B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, and Ce; X includes one or more of S, Si, Cl, B, C, and N; Y includes one or more of O and F. For example, lithium phosphates include LiFePO4, LiMnPO4, and LiFe 0.5 Mn 0.5 PO4, LiFe 0.6 Mn 0.4 PO4, LiFe 0.7 Mn 0.3 One or more of PO4, LiNiPO4 and LiCoPO4.

[0100] In some embodiments, when the positive electrode active material is a lithium phosphate system, the coating weight of the positive electrode film is ≥400mg / 1540.25mm. 2 Available in 400mg / 1540.25mm. 2 Up to 500mg / 1540.25mm 2 .

[0101] When lithium phosphate is used as the main material of the positive electrode active material, combined with high coating weight, the energy density of the battery cell can be improved while its cycle performance can also be significantly improved. Furthermore, when lithium phosphate is used in combination with hydrophilic polymers, the hydrophilic polymers can form liquid storage points on the surface of the lithium phosphate material, effectively improving the wetting performance of the electrolyte on the lithium phosphate material, thereby further improving the cycle performance and power performance of the battery cell.

[0102] In this embodiment of the application, when the mass content of lithium transition metal oxide is ≥90% based on the total mass of the positive electrode active material, the lithium transition metal oxide is used as the main material of the positive electrode active material. The positive electrode active material is defined herein as a lithium transition metal oxide system. In this case, the mass content of lithium transition metal oxide can reach 100%.

[0103] Examples of lithium transition metal oxides may include, but are not limited to, at least one of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and their respective modified compounds.

[0104] In some embodiments, lithium-containing transition metal oxides include those with the molecular formula L x A y Ni a Co b Mn c M (1-a-b-c) Y z Compounds and their modified compounds, wherein 0.5≤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; L includes one or more of Li and Na; A includes one or more of Na, K, and Mg; M includes one or more of B, Mg, Al, Si, 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; Y includes one or more of O and F. For example, lithium-containing transition metal oxides include LiCoO2, LiNiO2, LiMnO2, LiMn2O4, and LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2(NCM333), LiNi 0.5 Co 0.2 Mn 0.3 O2(NCM523), LiNi 0.6 Co 0.2 Mn 0.2 O2(NCM622), LiNi 0.8 Co 0.1 Mn 0.1 O2(NCM811), LiNi 0.85 Co 0.15 Al 0.05 At least one of O2.

[0105] During the charging and discharging process, active ions such as Li undergo insertion / extraction and consumption, resulting in varying molar Li content in the battery cell at different discharge states. In the embodiments of this application regarding the positive electrode active material, the molar Li content refers to the initial state of the material, i.e., the state before feeding. After charge-discharge cycles, the molar Li content may change when the positive electrode active material is applied to the battery system.

[0106] In the embodiments of this application, the molar content of oxygen (O) in the positive electrode active materials is only a theoretical value. Oxygen release from the crystal lattice will cause the molar content of oxygen (O) to change. In reality, the molar content of oxygen (O) will fluctuate.

[0107] In some embodiments, when the positive electrode active material is a lithium-containing transition metal oxide system, the coating weight of the positive electrode film is ≥300mg / 1540.25mm. 2 Available in 300mg / 1540.25mm. 2 Up to 400mg / 1540.25mm 2 .

[0108] When lithium-containing transition metal oxides (LMMOs) are used as the main positive electrode active material, high coating weight can improve the energy density of individual battery cells. When LMOs are used in combination with hydrophilic polymers, the hydrophilic polymers can form electrolyte reservoirs on the surface of the LMO material, effectively improving the wetting performance of the electrolyte and thus further improving the cycle performance and power performance of the battery cells. The hydrophilic polymers adhering to the surface of the LMO material can also enhance its structural stability to a certain extent, reducing the risk of structural collapse and further improving the cycle performance of the battery cells.

[0109] The positive electrode film has a layered structure, which can be a single layer or a multilayer structure. When the positive electrode film has a multilayer structure, it can include multiple sublayers, such as two, three, four, or five sublayers. The types of positive active materials in each sublayer can be the same or different. The mass content of the positive active materials in each sublayer can be the same or different. The coating weight of each sublayer can be the same or different.

[0110] In some implementations, the coating weight of the multilayer sublayers decreases progressively in the direction from the positive current collector to the positive electrode film layer. This can be understood as the sublayer closest to the positive current collector having the largest coating weight, and the sublayer furthest from the positive current collector having the smallest coating weight. This progressive decrease can be linear or gradient-based. For example, when the multilayer sublayer includes three or more sublayers, the coating weight of the multilayer sublayers can satisfy a linear relationship or a gradient-based decrease relationship.

[0111] Multi-layer sub-layers can be set by multi-layer coating, which helps to achieve thick coating. The multi-layer sub-layers adopt a differentiated coating weight method, especially the coating weight of the multi-layer sub-layers decreases step by step, which enables lithium ions to migrate quickly from the sub-layer farthest from the positive electrode current collector to the sub-layer closest to the positive electrode current collector. This is beneficial to improve the polarization phenomenon of the positive electrode film and improve the cycle performance of the battery cell.

[0112] like Figure 1 As shown, exemplarily, the positive electrode 7 includes a positive current collector 71 and a positive electrode film layer disposed on two surfaces of the positive current collector 71. The positive electrode film layer includes multiple sub-layers, including a first layer 721 and a second layer 722. The first layer 721 is disposed on the surface of the positive current collector 71, and the second layer 722 is located on the side of the first layer 721 away from the positive current collector 71. The coating weight of the first layer 721 is greater than the coating weight of the second layer 722. The use of a double-layer coating for the first layer 721 and the second layer 722 helps to achieve thick coating. The use of differentiated coating weights for the multiple sub-layers, with the coating weight of the first layer 721 being greater than that of the second layer 722, is beneficial to improve the polarization phenomenon of the positive electrode film layer and enhance the cycle performance of the battery cell.

[0113] In some embodiments, based on the total mass of the positive electrode film, the mass content of the hydrophilic polymer is >0% and ≤5%; optionally, the mass content of the hydrophilic polymer is ≤1%. When the mass content of the hydrophilic polymer is within the above range, the hydrophilic polymer, in combination with the positive electrode active material with a high coating weight, can form multiple liquid storage sites on the surface of the positive electrode active material particles, thereby improving the liquid storage capacity of the positive electrode film and improving the wettability of the electrolyte to the positive electrode active material in the positive electrode film, which is beneficial to improving the cycle performance and power performance of the battery cell.

[0114] For example, the mass content of the hydrophilic polymer can be 0.05%, 0.08%, 0.10%, 0.11%, 0.12%, 0.15%, 0.16%, 0.18%, 0.20%, 0.22%, 0.25%, 0.28%, 0.30%, 0.32%, 0.35%, 0.38%, 0.40%, 0.42%, 0.45%, 0.48%, 0.50%, 0.55%, 0.58%, 0.60%, 0.70%, 0.80%, 0.90%, 0.95%, 1%, 1.1%, 1.2%, 1.3%. %, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2.0%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, 3.0%, 3.1%, 3.2%, 3.3%, 3.4%, 3.5%, 3.6%, 3.7%, 3.8%, 3.9%, 4.0%, 4.1%, 4.2%, 4.3%, 4.4%, 4.5%, 4.6%, 4.7%, 4.8%, 4.9%, 5.0%, or a range consisting of any two of the above values.

[0115] In this application, the polymer mass content has a meaning known in the art and can be detected using equipment and methods known in the art. For example, it can be detected using thermogravimetric analysis (TGA) according to JYT014-1996. Specifically, based on the mass loss of the electrode during the heating process, a mass-temperature curve, i.e., a TG curve, is plotted. The mass loss corresponding to the polymer decomposition temperature is read as the total mass of the polymer in the electrode, thereby calculating the polymer mass content and coating weight. During the test, the following temperature rise program can be used in a nitrogen atmosphere: 5℃ / min, RT~500℃; 10℃ / min, 500~600℃; constant temperature at 600℃ for 10 min, then end.

[0116] When the positive electrode film layer comprises multiple sublayers, the mass content of the hydrophilic polymer in each sublayer is >0%, and the mass content of the hydrophilic polymer is ≤5%; alternatively, it can be ≤1%; further alternatively, it can be ≤0.5%. The mass content of the hydrophilic polymer in the sublayer can increase accordingly with the increase of the coating weight of the sublayer. When the mass content of the hydrophilic polymer is within the above range, the hydrophilic polymer can form multiple liquid storage sites on the surface of the positive electrode active material particles in each layer, improve the liquid storage capacity of each layer, improve the wettability of the electrolyte to the positive electrode active material in the positive electrode film layer, thereby helping to improve the cycle performance and power performance of the battery cell.

[0117] For example, the mass content of the hydrophilic polymer in each sublayer can be 0.05%, 0.08%, 0.10%, 0.11%, 0.12%, 0.15%, 0.16%, 0.18%, 0.20%, 0.22%, 0.25%, 0.28%, 0.30%, 0.32%, 0.35%, 0.38%, 0.40%, 0.42%, 0.45%, 0.48%, 0.50%, 0.55%, 0.58%, 0.60%, 0.70%, 0.80%, 0.90%, 0.95%, 1%, 1.1%, 1.2%, etc. 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2.0%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, 3.0%, 3.1%, 3.2%, 3.3%, 3.4%, 3.5%, 3.6%, 3.7%, 3.8%, 3.9%, 4.0%, 4.1%, 4.2%, 4.3%, 4.4%, 4.5%, 4.6%, 4.7%, 4.8%, 4.9%, 5.0%, or a range consisting of any two of the above values.

[0118] In some embodiments, the hydrophilic polymer may include at least one of fluorinated polymers, ether polymers, ester polymers, and aldehyde-ketone polymers. The hydrophilic polymer is configured to coat the surface of the active material with an electrolyte, thereby forming effective electrolyte storage points on the surface of the active material and improving the electrolyte storage capacity of the electrode. The specific types of hydrophilic polymers will be described below.

[0119] [Fluoropolymers]

[0120] In some embodiments, the hydrophilic polymer may include a fluorinated polymer.

[0121] In some embodiments, the crystallinity of the fluorinated polymer, as determined by differential scanning calorimetry, is X. c1 %, 0 < X c1 ≤28.

[0122] In some embodiments, the melting temperature of the fluoropolymer is T. m1 ℃, 0 < T m1 ≤130.

[0123] In some embodiments, the glass transition temperature of the fluorinated polymer is T. g1 ℃, -30≤T g1 ≤40.

[0124] Crystallization refers to the process by which atoms, ions, or molecules in a material arrange themselves in a specific spatial order to form an ordered structure. The conformation of hydrophilic polymers during crystallization is determined by both intramolecular and intermolecular factors. Intermolecular forces affect the packing density between molecular chains. Crystallinity X C1 The degree of crystallinity in a material is characterized by differential scanning calorimetry (DSC). Specifically, the testing procedure is as follows: Take 0.5g to 0.8g of sample, place the sample in a crucible, and subject the sample to heating and cooling at a nitrogen atmosphere, with a heating rate of 10℃ / min from the intrinsic temperature of the material (T0). g1 The initial temperature is 20°C lower than the material's intrinsic temperature. m1 The cutoff temperature for a process increasing from ℃ to 20℃ is determined by the actual glass transition temperature T of the material, based on the peak values ​​of heat absorption and release or the transition point during the process. g1 ℃ and melting temperature T m1 ℃, etc.

[0125] Therefore, fluorinated polymers have relatively low crystallinity, melting temperature or glass transition temperature. Fluorinated polymers have a certain degree of activity above the glass transition temperature. Under the action of external force, they can buffer external energy through chain segment movement, which manifests as a certain degree of flexibility. This can improve the problem of increased brittleness of the positive electrode sheet caused by thick coating. In addition, during the cycling process of the positive electrode sheet, it can act as a buffer for the charging and discharging process of the positive electrode active material, thereby improving cycle expansion and improving cycle performance.

[0126] For example, the crystallinity of the fluorinated polymer, as measured by differential scanning calorimetry, can be 5%, 10%, 15%, 20%, 25%, 28%, or a range of any two of the above values.

[0127] For example, the melting temperature of the fluoropolymer can be 10°C, 20°C, 50°C, 70°C, 90°C, 100°C, 120°C, 130°C, or any combination of two of the above values.

[0128] For example, the glass transition temperature of the fluoropolymer can be -30°C, -25°C, -20°C, -15°C, -10°C, -5°C, 0°C, 5°C, 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, or a range of any two of the above values.

[0129] In some embodiments, the fluorinated polymer includes at least one of the compounds represented by formula (A1) to formula (AII).

[0130]

[0131] In equations (AI) and (AII), R 11 R 12 R 13 and R 14 Each independently comprises a hydrogen atom, a fluorine atom, a chlorine atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted alkoxy group, and R 11 R 12 R 13 and R 14 At least one of them contains a fluorine atom.

[0132] Optionally, R 11 R 12 R 13 and R 14 Each of them independently includes a hydrogen atom, a fluorine atom, a chlorine atom, a substituted or unsubstituted C1-C10 alkyl group, or a substituted or unsubstituted C1-C10 alkoxy group.

[0133] Optionally, R 11 R 12 R 13 and R 14 Each of them independently includes a hydrogen atom, a fluorine atom, a chlorine atom, a substituted or unsubstituted C1-C3 alkyl group, or a substituted or unsubstituted C1-C3 alkoxy group.

[0134] Further optional, R 11 R 12 R 13 and R14 Each of these atoms independently includes a hydrogen atom, a fluorine atom, a chlorine atom, a methyl group, a fluoromethyl group, a methoxy group, or a perfluoromethoxy group.

[0135] In some embodiments, the degree of polymerization n of the fluoropolymer is selected from positive integers from 1000 to 30000, such as 1000, 2000, 3000, 4000, 5000, 6000, 7000, 8000, 9000, 10000, 11000, 12000, 13000, 14000, 15000, 16000, 17000, 18000, 19000, 20000, 21000, 22000, 23000, 24000, 25000, 26000, 27000, 28000, 29000, or a range of any two of the above values.

[0136] Optionally, when substituted, the substituent may include one or more of the following: nitrile (-CN), nitro, sulfonic acid, sulfonyl, amide, carboxyl, ester, and halogen atom. The halogen atom may include fluorine, bromine, etc., and may be a fluorine atom.

[0137] In some embodiments, the fluoropolymer includes at least one of the compounds represented by formula (AIII).

[0138]

[0139] In equation (AIII), R 15 Includes single bonds, substituted or unsubstituted alkyl groups; when substituted, the substituents include fluorine atoms.

[0140] In some embodiments, when substituted, the substituent may include one or more of the following: nitrile (-CN), nitro, sulfonic acid, sulfonyl, amide, carboxyl, ester, and halogen atom.

[0141] Optionally, R 15 Includes single-bonded, substituted or unsubstituted C1-C3 alkyl groups.

[0142] In some implementations, p is selected from positive integers from 1 to 3, such as 1, 2, or 3.

[0143] In some embodiments, the degree of polymerization n of the fluoropolymer is selected from positive integers from 1000 to 30000, such as 1000, 2000, 3000, 4000, 5000, 6000, 7000, 8000, 9000, 10000, 11000, 12000, 13000, 14000, 15000, 16000, 17000, 18000, 19000, 20000, 21000, 22000, 23000, 24000, 25000, 26000, 27000, 28000, 29000, or a range of any two of the above values.

[0144] In some embodiments, the fluorinated polymer includes at least one of the compounds shown in formula (AI-1) to the compounds shown in formula (AI-11).

[0145]

[0146] In some embodiments, the fluorinated polymer includes at least one of the compounds shown in formula (AII-1) to formula (AII-5).

[0147]

[0148] In some embodiments, the fluorinated polymer includes at least one of the compounds shown in formula (AIII-1) to formula (AIII-3).

[0149]

[0150]

[0151] For example, fluorinated polymers include one or more of the following: perfluoroethylene (PTFE), polyvinylidene fluoride (PVDF), perfluoroethylene-propylene copolymer (FEP), perfluoroalkoxy polymer (PFA), perfluoropolyether (PFPE), polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP), polyvinylidene fluoride-trifluoroethylene copolymer (PVDF-TrFE), and perfluoro(1-butenyl vinyl ether) polymer (CYTOP).

[0152] Optionally, the fluorinated polymer includes one or more of the following: perfluoroethylene (PTFE), polyvinylidene fluoride (PVDF), perfluoroethylene propylene copolymer (FEP), polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP), and polyvinylidene fluoride-trifluoroethylene copolymer (PVDF-TrFE).

[0153] The aforementioned fluorinated polymers can be derived from one or more of the following monomers: fluorinated cyclohexane, fluorinated vinylidene, 1,2-difluoroethylene, vinylidene fluoride, trifluoroethylene, trifluorochloroethylene, tetrafluoroethylene, hexafluoropropylene, 3,3,3-trifluoropropylene, trifluoropropylene, tetrafluoropropylene, and pentafluoropropylene. Optionally, the aforementioned fluorinated polymers can be derived from at least two of the following monomers: fluorinated cyclohexane, fluorinated vinylidene, 1,2-difluoroethylene, vinylidene fluoride, trifluoroethylene, trifluorochloroethylene, tetrafluoroethylene, hexafluoropropylene, 3,3,3-trifluoropropylene, trifluoropropylene, tetrafluoropropylene, and pentafluoropropylene.

[0154] In embodiments of this application, the polymer can also be obtained by copolymerizing the above-mentioned structural groups with small amounts of other types of structural groups (e.g., olefin compounds, ester monomers, nitrile monomers such as acrylonitrile, amide monomers such as acrylamide, acrylic acid, etc.). These small amounts of monomers have relatively poor hydrophilic properties; copolymerizing the monomers of the above-mentioned fluorinated polymer with these monomers can improve the swelling ratio and compressive modulus of the hydrophilic polymer.

[0155] In some embodiments, the molecular weight of the hydrophilic polymer is 2 × 10⁻⁶. 5 g / mol up to 1.2 × 10 6 g / mol.

[0156] For example, the molecular weight of the hydrophilic polymer can be 2 × 10⁻⁶. 5 g / mol, 5×10 5 g / mol, 8×10 5 g / mol, 1×10 6 g / mol, 1.2×10 6 g / mol or a range consisting of any two of the above values.

[0157] [Ether polymers]

[0158] In some embodiments, the hydrophilic polymer includes ether polymers.

[0159] In some embodiments, the ether polymer is formed into a sheet-like structure; the sheet-like structure is in (T m2 The elastic modulus G' - energy dissipation modulus G” curve was obtained by dynamic frequency scanning test at +20℃. The slope of the elastic modulus G' - energy dissipation modulus G” curve is K1, 1<K1<∞, T m2 °C indicates the melting temperature of ether polymers.

[0160] Specifically, the preparation process of the sheet-like structure is as follows: The ether polymer is vacuum dried at 80°C for 12 hours. The dried ether polymer is then hot-pressed into thin sheets using a flat vulcanizing machine, with the hot-pressing temperature set to (T...). m2The temperature is +20℃, the calendering thickness is 1-2 min, the calendering time is 2 min, and the pressure is 8 MPa. After calendering for 2 min, the sample is removed and placed on another vulcanizing machine of the same model for cold pressing at a pressure of 10 MPa. Polymer discs (sheet-like structures) of a fixed size can be obtained using a circular mold with a diameter of 25 mm. For example, the sheet-like structure can be a disc with a thickness of 1-2 mm and a diameter of 25 mm; it can also be prepared according to the sample standard required by the testing equipment.

[0161] According to the conclusions of classical linear viscoelasticity, for polymers, especially linear polymers, the elastic modulus G'-energy dissipation modulus G” curve exhibits frequency dependence in the terminal region (the range approaching the maximum angular velocity), and the longest chain of the polymer plays a role in viscoelastic behavior.

[0162] The specific steps of the dynamic frequency scanning test are as follows: A TA-AR2000EX rotational rheometer (TA Instruments, USA) is used for the dynamic frequency scanning test. The parallel plate diameter is 25mm and the thickness is 0.9mm. To ensure the test is conducted within the linear springback region, the strain is 2% during the dynamic frequency scanning test, and the test temperature is T. m2 +20℃, test frequency sweep range: 500rad / s≤w 2 ≤0.05rad / s, so as to obtain data in the lowest possible frequency range.

[0163] Dynamic frequency scanning tests can characterize the degree of molecular chain entanglement during solid-state melting (molten state). Compared to linear or short-branched structures, long-branched, network, and low-crosslinked structures exhibit high entanglement and deviate from linear end-effector behavior, while ether polymers exhibit solid-state behavior. When the ether polymers of this application meet the above-mentioned range, the molecular chain entanglement state can be further reduced, which is beneficial for the diffusion of solvent molecules between molecular chains in the electrolyte. Furthermore, the ether polymers still maintain a certain degree of molecular chain entanglement, effectively storing electrolyte and improving the cycle performance of the battery cells.

[0164] In some implementations, 1 < K1 ≤ 100; alternatively, 1 < K1 ≤ 10. For example, K1 can be 1.01, 1.1, 2, 5, 10, 15, 20, 30, 50, 100, 200, 500, 1000, 5000, 10000 or a range of any two of the above values.

[0165] In some embodiments, the glass transition temperature of the ether polymer is T. g2 ℃, -20≤T g2≤35. For example, the glass transition temperature of the ether polymer can be -20℃, -15℃, -10℃, -5℃, -0℃, 5℃, 10℃, 15℃, 20℃, 25℃, 30℃, 35℃, or a range of any two of the above values. Ether polymers exhibit a certain degree of mobility above their glass transition temperature. Under external force, they can buffer external energy through chain segment movement, demonstrating a certain degree of flexibility. This can mitigate the increased brittleness of the positive electrode sheet caused by thick coatings, and further, during the cycling process of the positive electrode sheet, it can act as a buffer for the charging and discharging process of the positive electrode active material, thereby improving cycle expansion and enhancing cycle performance.

[0166] In some embodiments, the ether polymer includes compounds represented by formula (BI).

[0167]

[0168] In formula (BI), R 21 and R 22 Each independently comprises a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted alkoxy group; R 23 This includes single bonds, substituted or unsubstituted methylene groups.

[0169] Optionally, R 21 and R 22 Each of them independently includes a hydrogen atom, a substituted or unsubstituted C1-C10 alkyl group, or a substituted or unsubstituted C1-C10 alkoxy group.

[0170] Optionally, R 21 and R 22 Each of them independently includes a hydrogen atom, a substituted or unsubstituted C1-C3 alkyl group, or a substituted or unsubstituted C1-C3 alkoxy group.

[0171] Optionally, R 23 Includes single-bonded, substituted or unsubstituted C1-C10 methylene groups.

[0172] Optionally, R 23 This includes single-bonded, substituted, or unsubstituted C1-C5 methylene groups.

[0173] For example, the ether polymer includes at least one of the compounds shown in formula (BI-1) to formula (BI-8).

[0174]

[0175]

[0176] In some embodiments, the ether polymer includes compounds represented by formula (BII).

[0177]

[0178] In formula (BII), R 24 To R 27 Each independently comprises a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, or an ether group, and R 24 To R 27 At least one of them contains a substituted or unsubstituted alkoxy or ether group.

[0179] Optionally, R 24 To R 27 Each of them independently includes a hydrogen atom, a substituted or unsubstituted C1-C10 alkyl group, a substituted or unsubstituted C1-C10 alkoxy group, or an ether group.

[0180] Optionally, R 24 To R 27 Each of these groups independently includes a hydrogen atom, a substituted or unsubstituted C1-C3 alkyl group, a substituted or unsubstituted C1-C3 alkoxy group, or an ether group.

[0181] In some embodiments, the ether polymer includes at least one of the compounds shown in formula (BII-1) to formula (BII-7).

[0182]

[0183] The polymers described above are merely examples of structural groups in the main molecular chains. In embodiments of this application, the polymers may also be obtained by copolymerizing the above structural groups with small amounts of other types of structural groups (e.g., olefin compounds, ester monomers, nitrile monomers such as acrylonitrile, amide monomers such as acrylamide, acrylic acid, etc.).

[0184] When the above groups are substituted, the substituents may include one or more of the following: nitrile (-CN), nitro, sulfonic acid, sulfonyl, amide, carboxyl, ester, and halogen atom. The halogen atom may include at least one of the following: fluorine atom and bromine atom; alternatively, it may be a fluorine atom.

[0185] In some embodiments, the degree of polymerization n of the ether polymer is selected from a positive integer from 1500 to 25000, such as 1500, 2000, 3000, 4000, 5000, 6000, 7000, 8000, 9000, 10000, 11000, 12000, 13000, 14000, 15000, 16000, 17000, 18000, 19000, 20000, 21000, 22000, 23000, 24000, 25000, or a range of any two of the above values.

[0186] Optionally, the degree of polymerization n of the ether polymer is selected from a positive integer from 3000 to 18000.

[0187] In some embodiments, the molecular weight of the hydrophilic polymer is 2 × 10⁻⁶. 5 g / mol up to 1.2 × 10 6 g / mol. For example, the molecular weight of the polymer can be 2 × 10⁻⁶ g / mol. 5 g / mol, 5×10 5 g / mol, 8×10 5 g / mol, 1×10 6 g / mol, 1.2×10 6 g / mol or a range consisting of any two of the above values.

[0188] [Ester polymers]

[0189] In some embodiments, the hydrophilic polymer includes ester polymers.

[0190] In some embodiments, the ester polymer is formed into a sheet-like structure; the sheet-like structure is in (T m3 The elastic modulus G' - energy dissipation modulus G” curve was obtained by dynamic frequency scanning test at +20℃. The slope of the elastic modulus G' - energy dissipation modulus G” curve is K2, 1<K1<∞, T m3 °C represents the melting temperature of ester polymers.

[0191] Specifically, the preparation process of the sheet-like structure is similar to that of ether polymers, and will not be described in detail here. When the ester polymers of this application meet the above-mentioned range, they can further reduce the molecular chain entanglement state, which is beneficial to the diffusion of solvent molecules in the electrolyte between the molecular chains; and, the ester polymers still maintain a certain molecular chain entanglement state, which can effectively store electrolyte and improve the cycle performance of the battery cells.

[0192] In some implementations, 1 < K2 ≤ 100; alternatively, 1 < K2 ≤ 10. For example, K2 can be 1.01, 1.1, 2, 5, 10, 15, 20, 30, 50, 100, 200, 500, 1000, 5000, 10000 or a range of any two of the above values.

[0193] In some embodiments, the glass transition temperature of the ester polymer is T. g3 ℃, -20≤T g3≤35; For example, the glass transition temperature of ester polymers can be -20℃, -15℃, -10℃, -5℃, -0℃, 5℃, 10℃, 15℃, 20℃, 25℃, 30℃, 35℃, or any combination of two of the above values. Ester polymers exhibit a certain degree of mobility above their glass transition temperature. Under external force, they can buffer external energy through chain segment movement, demonstrating a certain degree of flexibility. This can mitigate the increased brittleness of the positive electrode sheet caused by thick coatings, and can also act as a buffer during the charging and discharging process of the positive electrode active material during cycling, thereby improving cycle expansion and enhancing cycle performance.

[0194] In some embodiments, the ester polymer includes compounds represented by formula (CI).

[0195]

[0196] In formula (CI), R 31 R 32 and R 33 Each independently comprises a hydrogen atom, or a substituted or unsubstituted alkyl group; R 34 This includes substituted or unsubstituted alkyl groups, or substituted or unsubstituted hydroxyalkyl groups.

[0197] Optionally, R 31 R 32 and R 33 Each of them independently includes a hydrogen atom or a substituted or unsubstituted C1-C10 alkyl group.

[0198] Optionally, R 31 R 32 and R 33 Each of them independently includes a hydrogen atom or a substituted or unsubstituted C1-C8 alkyl group.

[0199] In some implementations, R 34 This includes substituted or unsubstituted C1-C10 alkyl groups, or substituted or unsubstituted C1-C10 hydroxyalkyl groups.

[0200] In some implementations, R 34 This includes substituted or unsubstituted C1-C8 alkyl groups, or substituted or unsubstituted C1-C8 hydroxyalkyl groups.

[0201] In some implementations, R 31 This includes hydrogen atoms, or substituted or unsubstituted methyl groups.

[0202] In some implementations, R 32 and R 33 Each of them independently contains a hydrogen atom.

[0203] By way of example, the ester polymer includes at least one of the compounds shown in formula (CI-1) to the compounds shown in formula (CI-15).

[0204]

[0205]

[0206] In some embodiments, the ester polymer includes compounds represented by formula (CII).

[0207]

[0208] In formula (CII), R 35 This includes substituted or unsubstituted methylene groups.

[0209] Optionally, R 35 This includes substituted or unsubstituted C1-C10 methylene groups.

[0210] Optionally, R 35 This includes substituted or unsubstituted C2-C6 methylene groups.

[0211] Optionally, R 35 This includes substituted or unsubstituted C2-C4 methylene groups.

[0212] By way of example, the ester polymer includes at least one of the compounds shown in formula (CII-1) to the compounds shown in formula (CII-5).

[0213]

[0214]

[0215] In some embodiments, the ester polymer includes compounds represented by formula (CIII).

[0216]

[0217] In equation (CIII), R 36 R 37 and R 38 Each independently comprises a hydrogen atom, or a substituted or unsubstituted C1-C8 alkyl group; R 39 Including substituted or unsubstituted C1-C8 alkyl groups;

[0218] Optionally, R 36 R 37 and R 38 Each of them independently includes a hydrogen atom and a substituted or unsubstituted C1-C4 alkyl group.

[0219] By way of example, the ester polymer includes at least one of the compounds shown in formula (CIII-1) to the compounds shown in formula (CIII-5).

[0220]

[0221] The above-mentioned polymers are merely examples of structural groups in the main molecular chains. In the embodiments of this application, the hydrophilic polymers can also be obtained by copolymerizing the above-mentioned structural groups with a small amount of other types of structural groups (such as olefin compounds, ester monomers, nitrile monomers such as acrylonitrile, amide monomers such as acrylamide, acrylic acid, etc.).

[0222] When the above groups are substituted, the substituents may include one or more of the following: nitrile (-CN), nitro, sulfonic acid, sulfonyl, amide, carboxyl, ester, and halogen atom.

[0223] In some embodiments, the degree of polymerization n of the ester polymer is selected from positive integers from 800 to 20000, such as 800, 1000, 1500, 2000, 3000, 4000, 5000, 6000, 7000, 8000, 9000, 10000, 11000, 12000, 13000, 14000, 15000, 16000, 17000, 18000, 19000, 20000, or a range of any two of the above values.

[0224] In some embodiments, the degree of polymerization n of the ester polymer is selected from a positive integer from 1000 to 15000.

[0225] In some embodiments, the molecular weight of the hydrophilic polymer is 2 × 10⁻⁶. 5 g / mol up to 1.2 × 10 6 g / mol.

[0226] For example, the molecular weight of the hydrophilic polymer can be 2 × 10⁻⁶. 5 g / mol, 5×10 5 g / mol, 8×10 5 g / mol, 1×10 6 g / mol, 1.2×10 6 g / mol or a range consisting of any two of the above values.

[0227] [Aldehyde-ketone polymers]

[0228] In some embodiments, the hydrophilic polymer includes aldehyde-ketone polymers.

[0229] In some embodiments, the aldehyde-ketone polymer is formed into a sheet-like structure; the sheet-like structure is in (T m4The elastic modulus G' - energy dissipation modulus G” curve was obtained by dynamic frequency scanning test at +20℃. The slope of the elastic modulus G' - energy dissipation modulus G” curve is K3, 0.8≤K3<∞, T m4 °C indicates the melting temperature of the aldehyde-ketone polymer.

[0230] Specifically, the preparation process of the sheet-like structure is similar to that of ether polymers, and will not be described in detail here. When the aldehyde-ketone polymer of this application meets the above-mentioned range, it can further reduce the molecular chain entanglement state, which is beneficial to the diffusion of solvent molecules in the electrolyte between the molecular chains; and, the aldehyde-ketone polymer still maintains a certain molecular chain entanglement state, which can effectively store electrolyte and improve the cycle performance of the battery cell.

[0231] In some implementations, 0.8 ≤ K3 ≤ 100; alternatively, 0.8 ≤ K3 ≤ 10. For example, K3 can be 0.8, 0.85, 0.9, 1, 1.01, 1.1, 2, 5, 10, 15, 20, 30, 50, 100, 200, 500, 1000, 5000, 10000, or a range of any two of the above values.

[0232] In some embodiments, the glass transition temperature of the aldehyde-ketone polymer is T. g4 ℃, -20≤T g4 ≤35; For example, the glass transition temperature of the aldehyde-ketone polymer can be -20℃, -15℃, -10℃, -5℃, -0℃, 5℃, 10℃, 15℃, 20℃, 25℃, 30℃, 35℃, or any combination of two of the above values. Aldehyde-ketone polymers exhibit a certain degree of activity above their glass transition temperature. Under external force, they can buffer external energy through chain segment movement, demonstrating a certain degree of flexibility. This can mitigate the increased brittleness of the positive electrode sheet caused by thick coatings, and further, during the cycling process of the positive electrode sheet, it can act as a buffer for the charging and discharging process of the positive electrode active material, thereby improving cycle expansion and enhancing cycle performance.

[0233] In some embodiments, the aldehyde-ketone polymer comprises compounds represented by formula (DI).

[0234]

[0235] In formula (DI), R 41 Including single-bonded, substituted, or unsubstituted C1-C6 methylene groups; R 42 Includes hydrogen atoms, substituted or unsubstituted C1-C6 alkyl groups.

[0236] Optionally, R 41 This includes single-bonded, substituted, or unsubstituted C1-C2 methylene groups.

[0237] Optionally, R42 Includes hydrogen atoms, substituted or unsubstituted C1-C3 alkyl groups.

[0238] In the embodiments of this application, a single bond indicates that the group does not exist, and the atoms on both sides of the group are connected by a single bond, such as R. 41 It is a single bond, representing R. 41 The carbon atoms on both sides are connected by single bonds.

[0239] By way of example, the aldehyde-ketone polymer includes at least one of the compounds shown in formula (DI-1) to the compounds shown in formula (DI-6).

[0240]

[0241] For example, aldehyde-ketone polymers include compounds represented by formula (DII).

[0242]

[0243] In formula (DII), R 43 To R 46 Each independently includes 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 from 0 to 5, and at least one of r and s is selected from a positive integer.

[0244] Optionally, R 43 To R 46 Each of these components independently includes a hydrogen atom, a hydroxyl group, a substituted or unsubstituted C1-C3 alkyl group, a substituted or unsubstituted C1-C2 hydroxyalkyl group, or a substituted or unsubstituted C1-C2 alkoxy group.

[0245] In some embodiments, the aldehyde-ketone polymer includes at least one of the compounds shown in formula (DII-1) to formula (DII-4).

[0246]

[0247]

[0248] The polymers described above are merely examples of structural groups in the main molecular chains. In embodiments of this application, the polymers can also be obtained by copolymerizing the above structural groups with other types of structural groups (such as olefin compounds, enol compounds, acrylonitrile compounds, etc.).

[0249] When the above groups are substituted, the substituents may include one or more of the following: nitrile (-CN), nitro, sulfonic acid, sulfonyl, amide, carboxyl, ester, and halogen atom. The halogen atom may include at least one of the following: fluorine, bromine, and chlorine.

[0250] In some embodiments, the degree of polymerization n of the aldehyde-ketone polymer is selected from positive integers from 500 to 15000, such as 500, 800, 1000, 1500, 2000, 3000, 4000, 5000, 6000, 7000, 8000, 9000, 10000, 11000, 12000, 13000, 14000, 15000, or a range of any two of the above values.

[0251] Optionally, the degree of polymerization n of the aldehyde-ketone polymer is selected from a positive integer from 500 to 10000.

[0252] In some embodiments, the molecular weight of the aldehyde-ketone polymer is 1.2 × 10⁻⁶. 5 g / mol up to 1.2 × 10 6 g / mol.

[0253] For example, the molecular weight of the aldehyde-ketone polymer can be 1.2 × 10⁻⁶. 5 g / mol, 2×10 5 g / mol, 5×10 5 g / mol, 8×10 5 g / mol, 1×10 6 g / mol, 1.0×10 6 g / mol, 1.2×10 6 g / mol or a range consisting of any two of the above values.

[0254] In some embodiments, the hydrophilic polymer can be a homopolymer or a copolymer. In addition to the monomers mentioned above that can form fluorinated polymers, ether polymers, ester polymers and aldehyde-ketone polymers, the monomers of the hydrophilic polymer can also include olefin monomers, etc.

[0255] The relevant parameters of the hydrophilic polymer in the embodiments of this application can be detected using the following methods:

[0256] The groups of the hydrophilic polymer in the embodiments of this application can be detected by infrared spectrophotometry (IR). Specifically, the hydrophilic polymer is tested using a Thermo Nicolet Nexus 670 attenuated total reflectance Fourier transform infrared spectrometer (FTIR-ATR), and then tested according to standard GB / T6040-2002. The test range is 600–4000 cm⁻¹ using the ATR method. -1 Repeatability: ±2cm -1 Resolution: better than 4cm -1 ; Transmission depth 0.2~0.6μm.

[0257] The structure of the lyophilic polymer in the embodiments of this application can be determined by nuclear magnetic resonance (NMR). Specifically, 1H NMR and 13C NMR are performed on a Varian Mercury Plus-400 NMR spectrometer at a test temperature of 20°C, with TMS as an internal standard, CDCl3 as a solvent, and a proton resonance frequency of 400MHz.

[0258] The polymer monomer type of the lyophilic polymer in this application (especially suitable for monomers with a small proportion in the polymer) can be determined by pyrolysis-gas chromatography-mass spectrometry. The specific testing steps are as follows: Accurately weigh 0.5 mg of sample and put it into a sample cup. After fixing it to the injection rod, insert it into the pyrolyzer installed near the GC (gas chromatography) injection port. After the pyrolyzer temperature reaches the set temperature, press the injection button. The sample cup will fall rapidly into the core of the pyrolysis furnace through free fall. In the inert gas N2 atmosphere, the volatile components will instantly vaporize and be carried into the gas chromatography column by the carrier gas for separation. Finally, it will be detected by flame ionization detector (FID) or mass spectrometer (MS) to obtain a gas chromatogram or total ion chromatogram.

[0259] The molecular weight of the hydrophilic polymer in the embodiments of this application has a meaning known in the art and can be determined using commonly used equipment and methods in the art. It can be tested by gel permeation chromatography (GPC) according to GB / T21863-2008. The specific test steps are as follows: take an appropriate amount of the sample to be tested (the sample concentration should be 8%-12% opacity), add 20 ml of deionized water, and simultaneously incubate for 5 min (53 kHz / 120 W) to ensure that the sample is completely dispersed. Then, the sample is measured according to GB / T19077-2016 / ISO 13320:2009.

[0260] In some embodiments, the positive current collector has two surfaces opposite each other in its thickness direction, and the positive electrode film layer can be disposed on either or both of the two opposite surfaces of the positive current collector.

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

[0262] In some embodiments, the positive electrode film layer may optionally include a positive electrode conductive agent. This application does not impose particular limitations on the type of positive electrode conductive agent. As an example, the positive electrode conductive agent includes one or more combinations selected from superconducting carbon, conductive carbon black, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. In some embodiments, the mass percentage of the positive electrode conductive agent is less than 5% based on the total mass of the positive electrode film layer.

[0263] In some embodiments, the positive electrode film layer may optionally include a positive electrode binder. This application does not impose particular limitations on the type of positive electrode binder. As an example, the positive electrode binder may include one or more combinations selected from polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resins. In some embodiments, the mass percentage of the positive electrode binder is less than 5% based on the total mass of the positive electrode film layer. Compared to the crystallinity of the fluorinated polymers in this application, the positive electrode binder has a higher crystallinity.

[0264] The positive electrode film is typically formed by coating a positive electrode slurry onto a positive electrode current collector, followed by drying and cold pressing. The positive electrode slurry is usually formed by dispersing the positive electrode active material, a hydrophilic polymer, an optional conductive agent, an optional binder, and any other components in a solvent and stirring until homogeneous. The solvent can be N-methylpyrrolidone (NMP), but is not limited to it. Of course, the preparation of the positive electrode sheet is not limited to the above methods; the preparation methods described earlier can also be used.

[0265] battery cell

[0266] Secondly, this application also proposes a battery cell. The battery cell includes a positive electrode as described in any embodiment of the first aspect of this application, which can effectively improve the energy density, cycle performance, and power performance of the battery cell.

[0267] [Negative electrode plate]

[0268] In some embodiments, the electrode assembly includes a negative electrode sheet, which includes a negative current collector and a negative electrode film layer disposed on at least one side of the negative current collector, the negative electrode film layer including a negative electrode active material.

[0269] The negative electrode active material may be any negative electrode active material known in the art for use in battery cells. As an example, the negative electrode active material may include, but is not limited to, at least one of natural graphite, artificial graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate. Silicon-based materials may include at least one of elemental silicon, silicon oxide, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. Tin-based materials may include at least one of elemental tin, tin oxide, and tin alloys.

[0270] In some embodiments, the negative electrode current collector has two surfaces opposite each other in its thickness direction, and the negative electrode film layer is disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0271] In some embodiments, the negative electrode film layer may optionally include a negative electrode conductive agent. This application does not impose particular limitations on the type of negative electrode conductive agent. As an example, the negative electrode conductive agent may include at least one selected from superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. In some embodiments, the mass percentage of the negative electrode conductive agent is ≤5% based on the total mass of the negative electrode film layer.

[0272] In some embodiments, the negative electrode film layer may optionally include a negative electrode binder. This application does not impose particular limitations on the type of negative electrode binder. As an example, the negative electrode binder may include at least one of styrene-butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, waterborne acrylic resins (e.g., polyacrylic acid PAA, polymethacrylic acid PMAA, sodium polyacrylate PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS). In some embodiments, the mass percentage of the negative electrode binder is ≤5% based on the total mass of the negative electrode film layer.

[0273] In some embodiments, the negative electrode film may optionally include other additives. As an example, other additives may include thickeners, such as sodium carboxymethyl cellulose (CMC), PTC thermistor materials, etc. In some embodiments, the mass percentage of other additives is ≤2% based on the total mass of the negative electrode film.

[0274] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. As an example of a metal foil, copper foil may be used. The composite current collector may include a polymer substrate and a metal material layer formed on at least one surface of the polymer substrate. As an example, the metal material may include at least one of copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. As an example, the polymer substrate may include at least one of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0275] The negative electrode film is typically formed by coating a negative electrode slurry onto a negative electrode current collector, followed by drying and cold pressing. The negative electrode slurry is usually formed by dispersing the negative electrode active material, optional conductive agent, optional binder, and other optional additives in a solvent and stirring until homogeneous. The solvent can be N-methylpyrrolidone (NMP) or deionized water, but is not limited to these. Of course, the preparation of the negative electrode sheet is not limited to the above methods; the preparation methods described earlier can also be used.

[0276] The negative electrode sheet does not exclude other additional functional layers besides the negative electrode film layer. For example, in some embodiments, the negative electrode sheet of this application further includes a conductive undercoat layer (e.g., composed of a conductive agent and an adhesive) sandwiched between the negative electrode current collector and the negative electrode film layer and disposed on the surface of the negative electrode current collector. In other embodiments, the negative electrode sheet of this application further includes a protective layer covering the surface of the negative electrode film layer.

[0277] [Isolation membrane]

[0278] In some implementations, the battery cell includes a separator.

[0279] In some embodiments, the separator includes a substrate.

[0280] In some embodiments, the separator includes a substrate and a coating disposed on at least one surface of the substrate.

[0281] The embodiments of this application do not have particular limitations on the material of the substrate. Any known substrate with good chemical and mechanical stability can be selected, such as at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The substrate can be a single-layer film or a multi-layer composite film. When the substrate is a multi-layer composite film, the materials of each layer can be the same or different.

[0282] In some embodiments, the coating may also include heat-resistant fillers. Further, the heat-resistant fillers may include at least one of inorganic particles and organic particles.

[0283] In some embodiments, the decomposition temperature of the heat-resistant filler can be above 200°C, thereby giving the heat-resistant filler good thermal stability and resistance to decomposition, which can further improve the heat resistance of the separator.

[0284] Inorganic particles possess high thermal stability and are not easily decomposed. Optionally, the inorganic particles include at least one of the following: inorganic particles with a dielectric constant of 5 or higher, inorganic particles with ionic conductivity but without ion storage, and inorganic particles capable of undergoing electrochemical reactions.

[0285] Optionally, inorganic particles with a dielectric constant of 5 or higher include boehmite, alumina, zinc oxide, silicon oxide, titanium oxide, zirconium oxide, barium oxide, calcium oxide, magnesium oxide, nickel oxide, tin oxide, cerium oxide, yttrium oxide, hafnium oxide, aluminum hydroxide, magnesium hydroxide, silicon carbide, boron carbide, aluminum nitride, silicon nitride, boron nitride, magnesium fluoride, calcium fluoride, barium fluoride, barium sulfate, magnesium aluminum silicate, lithium magnesium silicate, sodium magnesium silicate, bentonite, hydropyrite, zirconium titanate, barium titanate, Pb(Zr,Ti)O3 (abbreviated as PZT), and Pb 1-m La m Zr 1-n Ti n O3 (abbreviated as PLZT, 0 < m < 1, 0 < n < 1), Pb (Mg3Nb) 2 / 3 The coating comprises at least one of PbTiO3 (PMN-PT) and its modified inorganic particles. Optionally, the modification of each inorganic particle can be chemical modification and / or physical modification. Chemical modification methods include coupling agent modification (e.g., using silane coupling agents, titanate coupling agents, etc.), surfactant modification, polymer grafting modification, etc. Physical modification methods can include mechanical dispersion, ultrasonic dispersion, high-energy treatment, etc. Modification treatment can reduce the agglomeration of inorganic particles, thereby enabling them to form a more stable and uniform spatial network structure with nanocellulose; in addition, by selecting coupling agents, surfactants or polymers with specific functional groups to modify inorganic particles, it is also helpful to improve the wetting characteristics of the coating to the electrolyte and improve the adhesion strength between the coating and the substrate.

[0286] Optionally, inorganic particles that are ion-conductive but do not store ions include Li3PO4 and lithium titanium phosphate (Li). x1 Ti y1 (PO4)3, Lithium aluminum titanium phosphate (Li) x2 Al y2 Ti z1 (PO4)3、(LiAlTiP) x3 O y3 Type glass, lithium lanthanum titanate (Li) x4 La y4 TiO3, lithium germanium thiophosphate (Li) x5 Gey5 P z2 S w Lithium nitride (Li) x6 N y6 SiS2 type glass Li x7 Si y7 S z3 and P2S5 type glass Li x8 P y8 S z4 At least one of the following: 0 < x1 < 2, 0 < y1 < 3, 0 < x2 < 2, 0 < y2 < 1, 0 < z1 < 3, 0 < x3 < 4, 0 < y3 < 13, 0 < x4 < 2, 0 < y4 < 3, 0 < x5 < 4, 0 < y5 < 1, 0 < z2 < 1, 0 < w < 5, 0 < x6 < 4, 0 < y6 < 2, 0 < x7 < 3, 0 < y7 < 2, 0 < z3 < 4, 0 < x8 < 3, 0 < y8 < 3, 0 < z4 < 7. This can further improve the ion transport characteristics of the separator.

[0287] Organic particles have good thermal stability and are not easily decomposed, which can improve the heat resistance of the separator. At the same time, when the internal temperature of the battery cell reaches the melting point of the organic particles due to overcharging, abuse, or thermal abuse, the organic particles can melt and be drawn into the micropores of the substrate by capillary action, thus playing a role in closing the pores and breaking the circuit, which helps to ensure that the battery cell has high safety performance.

[0288] In some embodiments, the organic particles include, but are not limited to, at least one of the following: polyethylene particles, polypropylene particles, polystyrene particles, melamine resin particles, phenolic resin particles, polyester particles (e.g., polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate), polyimide particles, polyamide-imide particles, polyarylamide particles, polyphenylene sulfide particles, polysulfone particles, polyethersulfone particles, polyetheretherketone particles, polyaryletherketone particles, and copolymers of butyl acrylate and ethyl methacrylate (e.g., crosslinked polymers of butyl acrylate and ethyl methacrylate).

[0289] In some embodiments, the coating also includes an adhesive. This application does not impose any particular limitation on the type of adhesive; any known material with good adhesion can be selected. As an example, the adhesive includes at least one of aqueous acrylic resins (e.g., homopolymers of acrylic acid, methacrylic acid, sodium acrylate monomers, or copolymers with other comonomers), polyvinyl alcohol, isobutylene-maleic anhydride copolymers, and polyacrylamide.

[0290] Optionally, the binder content in the coating is <30%, based on the mass of the coating.

[0291] Electrolyte

[0292] In some implementations, the battery cell includes an electrolyte.

[0293] During the charging and discharging process of a single battery cell, active ions repeatedly insert and extract between the positive and negative electrode plates, while the electrolyte acts as a conductor for these active ions. This application does not impose any particular restrictions on the type of electrolyte; it can be selected according to actual needs.

[0294] Electrolytes consist of electrolyte salts and solvents. The types of electrolyte salts and solvents are not specifically limited and can be selected according to actual needs.

[0295] As an example, the electrolyte salt may include, but is not limited to, at least one of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorooxalate borate (LiDFOB), lithium dioxalate borate (LiBOB), lithium difluorophosphate (LiPO2F2), lithium difluorodioxalate phosphate (LiDFOP), and lithium tetrafluorooxalate phosphate (LiTFOP).

[0296] As an example, the solvent may include, but is not limited to, at least one of ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butyl ester carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), methyl ethyl sulfone (EMS), and diethyl sulfone (ESE).

[0297] In some embodiments, the electrolyte may optionally include additives. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery performance, such as additives that improve battery overcharge performance, additives that improve battery high-temperature performance, and additives that improve battery low-temperature power performance.

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

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

[0300] In some embodiments, the outer packaging of the battery cell can be a rigid shell, such as a hard plastic shell, an aluminum shell, or a steel shell. The outer packaging of the battery cell can also be a flexible package, such as a pouch. The material of the flexible package can be plastic, such as at least one of polypropylene (PP), polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0301] This application does not impose any particular limitation on the shape of the battery cell; it can be cylindrical, square, or any other arbitrary shape. Figure 2 The example shown is a square-structured battery cell 5.

[0302] In some embodiments, such as Figure 2 and Figure 3 As shown, the outer packaging may include a housing 51 and a cover plate 53. The housing 51 may include a base plate and side plates connected to the base plate, the base plate and side plates forming a receiving cavity. The housing 51 has an opening communicating with the receiving cavity, and the cover plate 53 is used to cover the opening to close the receiving cavity. The positive electrode sheet, negative electrode sheet, and separator may be formed into an electrode assembly 52 through a winding process or a stacking process. The electrode assembly 52 is encapsulated in the receiving cavity. Electrolyte is immersed in the electrode assembly 52. ​​The number of electrode assemblies 52 contained in a single battery cell 5 may be one or more, and can be adjusted according to requirements.

[0303] The method for preparing the battery cell of this application is well known. In some embodiments, a positive electrode, a separator, a negative electrode, and an electrolyte can be assembled to form a battery cell. As an example, the positive electrode, separator, and negative electrode can be formed into an electrode assembly through a winding process or a stacking process. The electrode assembly is placed in an outer packaging, dried, and then injected with electrolyte. After vacuum sealing, settling, formation, and shaping processes, a battery cell is obtained.

[0304] In some embodiments of this application, the battery cells according to this application can be assembled into a battery module. The number of battery cells contained in the battery module can be one or more, and the specific number can be adjusted according to the application and capacity of the battery module.

[0305] Figure 4 This is a schematic diagram of battery module 4 as an example. Figure 4 As shown, in battery module 4, multiple battery cells 5 can be arranged sequentially along the length of battery module 4. Of course, they can also be arranged in any other manner. Furthermore, these multiple battery cells 5 can be fixed in place using fasteners.

[0306] Optionally, the battery module 4 may also include a housing with a receiving space in which multiple battery cells 5 are received.

[0307] In some embodiments, the battery modules described above can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be adjusted according to the application and capacity of the battery pack.

[0308] Both battery module 4 and battery pack can be used as specific examples of batteries in the embodiments of this application.

[0309] Figure 5 and Figure 6 This is a schematic diagram of battery pack 1 as an example. Figure 5 and Figure 6 As shown, the battery pack 1 may include a battery box and multiple battery modules 4 disposed within the battery box. The battery box includes an upper body 2 and a lower body 3. The upper body 2 covers the lower body 3, forming a closed space for accommodating the battery modules 4. The multiple battery modules 4 can be arranged in any manner within the battery box.

[0310] Electrical appliances

[0311] Thirdly, this application provides an electrical device, which includes at least one of the battery cell, battery module, and battery pack described in this application. The battery cell, battery module, and battery pack can be used as the power source for the electrical device or as the energy storage unit of the electrical device. The electrical device can be, but is not limited to, mobile devices (e.g., mobile phones, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc. In some embodiments, the battery cell includes an injection hole for injecting electrolyte; when the battery cell is applied to the electrical device, the injection hole is located at the bottom of the battery cell in the vertical direction. Since the amount of free electrolyte in the battery cell is extremely small, or even non-existent, placing the injection hole at the bottom of the battery cell in the vertical direction can improve the reliability of the battery cell, thereby improving the reliability of the electrical device.

[0312] Electrical devices can be equipped with individual battery cells, battery modules, or battery packs depending on their usage requirements. Figure 7 This is a schematic diagram of an example electrical device. The electrical device 6 is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. To meet the high power and high energy density requirements of this electrical device, a battery pack 1 or a battery module can be used. Another example electrical device could be a mobile phone, tablet, laptop, etc. These devices typically require a slim and lightweight design, and can use individual battery cells as their power source.

[0313] Example

[0314] The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0315] Example 1: Preparation of Lithium-ion Batteries

[0316] (1) Preparation of the positive electrode sheet:

[0317] A positive electrode slurry was prepared by mixing a hydrophilic polymer, a positive electrode active material, a conductive agent (carbon black), and a binder (polyvinylidene fluoride (PVDF)) in an N-methylpyrrolidone (NMP) mixture at a mass ratio of 0.2:97.3:2:0.5.

[0318] The positive electrode slurry is coated onto the current collector aluminum foil and dried at 85°C, then cold-pressed. After edge trimming, cutting, and slitting, it is dried under vacuum at 85°C for 4 hours to produce the positive electrode sheet. The binder, polyvinylidene fluoride (PVDF), has a crystallinity of 48%.

[0319] (2) Preparation of negative electrode sheet:

[0320] Artificial graphite (negative electrode active material), carbon black (conductive agent), styrene-butadiene rubber (SBR) (binder), and sodium carboxymethyl cellulose (CMC) (thickener) were added to deionized water in a weight ratio of 95:3:1:1 and mixed evenly to prepare a negative electrode slurry. The negative electrode slurry was coated onto a copper foil current collector and dried at 85°C. Then, it was cold-pressed, trimmed, cut into sheets, and slit. Finally, it was dried under vacuum at 120°C for 12 hours to prepare the negative electrode sheet.

[0321] (3) Preparation of electrolyte:

[0322] The electrolyte consists of a non-aqueous organic solvent and a lithium salt. The non-aqueous organic solvent consists of ethylene carbonate EC and ethyl methyl carbonate (EMC) (volume ratio 3:7), and the lithium salt consists of 1 mol / L LiPF6.

[0323] (4) Preparation of lithium-ion batteries:

[0324] Using polyethylene film (PE) as a separator, the positive electrode, separator, and negative electrode are stacked in sequence, with the separator acting as a separator between the positive and negative electrode. The electrode assembly is then wound to obtain an electrode assembly. The electrode assembly is placed in an outer packaging shell, dried, and then injected with electrolyte. After vacuum sealing, settling, formation, and shaping, a lithium-ion battery is obtained.

[0325] Examples 2 to 6

[0326] Lithium-ion batteries were prepared using a method similar to that of Example 1. The difference from Example 1 is that the types of hydrophilic polymers were adjusted in Examples 2 to 6.

[0327] Examples 7 to 10

[0328] Lithium-ion batteries were prepared using a method similar to that of Example 1, except that the amount of hydrophilic polymer used in Examples 7 to 10 was adjusted.

[0329] Examples 11 to 15

[0330] Lithium-ion batteries were prepared using a method similar to that of Example 1, except that the types of active materials were adjusted in Examples 11 to 15.

[0331] Comparative Example 1 and Comparative Example 3

[0332] Lithium-ion batteries were prepared using a method similar to that of Example 1, except that a hydrophilic polymer was not used in Comparative Example 1.

[0333] (1) Preparation of the positive electrode sheet:

[0334] A positive electrode slurry was prepared by mixing the positive electrode active material, conductive carbon black, and binder polyvinylidene fluoride (PVDF) with N-methylpyrrolidone (NMP). The mass ratio of the positive electrode active material, conductive carbon black, and PVDF in the positive electrode slurry was 97.5:2:0.5. The positive electrode slurry was coated onto a current collector aluminum foil, dried at 85°C, and then cold-pressed. After edge trimming, cutting, and slitting, it was dried under vacuum at 85°C for 4 hours to form the positive electrode sheet. The crystallinity of the binder polyvinylidene fluoride (PVDF) was 48%.

[0335] Comparative Example 2 and Comparative Example 4

[0336] Lithium-ion batteries were prepared using a method similar to that of Example 1. The difference between Comparative Examples 2 and 4 is that the types of polymers were adjusted.

[0337] Examples 16 and 17

[0338] Lithium-ion batteries were prepared using a method similar to that of Example 1. The difference from Example 1 is that the positive electrode film in Examples 16 and 17 was coated with a double layer.

[0339] Test section

[0340] 1. Lithium-ion battery capacity retention test

[0341] The lithium-ion batteries prepared in the examples and comparative examples were charged at a constant current of 0.5C to V1 at room temperature, left to stand for 30 minutes, and then discharged at 0.5C to V2. The resulting capacity was recorded as the initial capacity C0. The above steps were repeated for the same battery, and the discharge capacity Cn of the battery after the nth cycle was recorded. The battery capacity retention rate after each cycle was Pn = Cn / C0 * 100%. A dot plot of battery capacity retention rate versus cycle number was obtained with 2000 points (P1, P2...P2000) as the ordinate and the corresponding cycle number as the abscissa. Here, V1 represents the upper limit of battery voltage, and V2 represents the lower limit of battery usage.

[0342] In this test, the first cycle corresponds to n=1, the second cycle to n=2, and so on, up to the 2000th cycle, which corresponds to n=2000. For example, the battery capacity retention rate data corresponding to Example 1 in Table 1 is the data measured after 2000 cycles under the above test conditions, i.e., the value of P2000. The test process for Comparative Example 1 and other examples is the same as above.

[0343] In the above test procedure, V1 and V2 are determined based on the type of positive electrode active material in the battery:

[0344] The positive electrode active material is LiFePO4 with V1 = 2.0V and V2 = 3.65V;

[0345] The positive electrode active material is LiNi 0.5 Co 0.2 Mn 0.3 O2, LiNi 0.8 Co 0.1 Mn 0.1 O2, LiNi 0.9 Co 0.05 Mn 0.05 The values ​​of O2 are V1 = 2.8V and V2 = 4.25V.

[0346] The positive electrode active material is LiMn 0.5 Fe 0.5 PO4, LiMn 0.4 Fe 0.6 The voltages of PO4 are V1 = 2.0V and V2 = 4.1V.

[0347] 2. Energy density of a single battery cell

[0348] In this application, the energy density of a single battery cell is defined in a way known in the art, specifically referring to the gravimetric energy transferred during each charge / discharge cycle, typically expressed in Wh / kg. When calculating energy density, only the mass of the film layer in the electrode plates can be considered; alternatively, the mass of the battery cell itself can be considered, meaning that in addition to the film layer mass, the mass of other components must also be taken into account. These other components are all components of the battery cell except for the film layer, such as the positive electrode current collector, negative electrode current collector, separator, electrolyte, electrode leads, insulating tape, and aluminum casing. This application considers the mass of the single battery cell when calculating energy density.

[0349] In the embodiments of this application, the energy density of the battery cell can be detected using equipment and methods known in the art. For example, after the battery cell is shipped, it is charged at a constant current of 1 / 3C to V1, then charged at a constant voltage to 0.05C, and left to stand for 30 minutes; then it is discharged at 1 / 3C to V2, and the discharge capacity D0 is recorded; the mass M0 of the battery cell is weighed, and the energy density of the battery cell is D0 / M0. Wherein, V1 is the upper limit of the battery voltage, and V2 is the lower limit of battery use, with specific values ​​as above.

[0350] Test Results

[0351] The test results are shown in Table 1.

[0352] Table 1

[0353]

[0354] In Table 1, the monomer content of 85% vinylidene fluoride + 15% perfluoropropylene indicates that, based on the total mass of the monomers, the mass content of vinylidene fluoride is 85% and the mass content of perfluoropropylene is 15%.

[0355] A crystallinity of " / " indicates that the polymer may be in an amorphous state and has no obvious crystallinity.

[0356] A melting temperature of " / " indicates that the polymer may be in an amorphous state and has no obvious melting temperature.

[0357] Table 2

[0358]

[0359] In Table 2, the content of the hydrophilic polymer in the positive electrode sheet is 0.2%, which means that the mass content of the hydrophilic polymer is 0.2% based on the total mass of the positive electrode film.

[0360] The amount of hydrophilic polymer added to the positive electrode is 0.00%, which means that no hydrophilic polymer was added to the positive electrode film layer.

[0361] As shown in Table 2, the positive electrode sheets of Comparative Examples 1 and 3 did not contain hydrophilic polymers. During the lithium-ion battery cycle, the thick coating of the positive electrode sheet in the lithium-ion battery resulted in poor wetting of the positive electrode film layer, which easily led to polarization and other problems, thus deteriorating the cycle performance and power performance of the lithium-ion battery.

[0362] Although polymers were added to the electrodes in Comparative Examples 2 and 4, the polymers had poor hydrophilicity, resulting in low liquid retention efficiency and high impedance, which would degrade the battery dynamics performance.

[0363] This application embodiment adds a hydrophilic polymer to the positive electrode sheet. The hydrophilic polymer has a high affinity with the electrolyte, which can improve the wetting rate of the electrolyte onto the positive electrode film, reduce polarization and interfacial side reactions, thereby improving cycle life. Since the hydrophilic polymer is configured to coat the electrolyte on the surface of the positive electrode active material particles, effective liquid storage points are formed on the surface of the positive electrode active material particles, thereby accelerating the migration rate of lithium ions and improving the power performance of the battery cell.

[0364] Table 3

[0365]

[0366] In Table 3, both Examples 16 and 17 used hydrophilic polymer A in the positive electrode film layer.

[0367] The positive electrode active material in Example 16 includes LiFePO4.

[0368] The positive electrode active material in Example 17 includes LiNi 0.8 Co 0.1 Mn 0.1 O2.

[0369] As shown in Tables 2 and 3, compared to the single-layer coating of Example 1, Examples 16 and 17 employ a double-layer coating, with the positive electrode film layer comprising a first layer and a second layer, which is more conducive to achieving a higher coating weight through thick coating. The difference in coating weight between the first and second layers, combined with the difference in the mass content of the hydrophilic polymer, results in better electrolyte wetting in each layer, which is beneficial for improving the cycle performance and power performance of the lithium-ion battery.

[0370] Although illustrative embodiments have been demonstrated and described, those skilled in the art should understand that the above embodiments should not be construed as limiting the present application, and that changes, substitutions and modifications can be made to the embodiments without departing from the spirit, principles and scope of the present application.

Claims

1. A positive electrode sheet comprising a positive electrode current collector and a positive electrode film layer disposed on at least one side of the positive electrode current collector, the positive electrode film layer comprising a positive electrode active material and a lyophilic polymer, the positive electrode film layer having a coating weight of > 300 mg / 1540.25 mm 2 ; The lyophilic polymer comprises at least one of a fluorinated polymer, an ether polymer, an ester polymer, and an aldehyde-ketone polymer, said fluoropolymer having a crystallinity Xc1% measured by differential scanning calorimetry, 0 < Xc1≤ 28; said fluoropolymer having a melting temperature Tm °C, 0 < Tm≤ 130; m1 m1 130.​ The ether-based polymer is made into a sheet structure; the sheet structure is tested by dynamic frequency scanning at (T m2 +20) °C to obtain an elastic modulus G'-dissipation modulus G'' curve, the slope of the elastic modulus G'-dissipation modulus G'' curve is K1,1 < K1 < ∞, T m2 °C represents the melting temperature of the ether-based polymer; The ester polymer is made into a sheet structure; the sheet structure is tested by dynamic frequency scanning at (T m3 +20) °C to obtain an elastic modulus G'-dissipation modulus G'' curve, the slope of the elastic modulus G'-dissipation modulus G'' curve is K2,1 < K2 < ∞, T m3 °C represents the melting temperature of the ester polymer; The aldehyde ketone polymer is made into a sheet structure; the sheet structure is tested by dynamic frequency scanning at (T m4 +20) °C to obtain an elastic modulus G'-dissipation modulus G" curve, the slope of the elastic modulus G'-dissipation modulus G" curve is K3, 0.8≤K3<∞, T m4 °C represents the melting temperature of the aldehyde ketone polymer.

2. The cathode sheet of claim 1, wherein, The coating weight of the positive electrode film layer is 300 mg / 1540.25 mm 2 up to 500 mg / 1540.25 mm 2 .

3. The cathode sheet of claim 1, wherein, The positive electrode active material comprises a lithium-containing phosphate.

4. The cathode sheet of claim 3, wherein, The mass content of the lithium-containing phosphate is ≥ 90% based on the total mass of the positive electrode active material.

5. The cathode sheet of claim 3, wherein, The coating weight of the positive electrode film layer is ≥ 400 mg / 1540.25 mm 2 .

6. The cathode sheet of claim 5, wherein, The coating weight of the positive electrode film layer is 400 mg / 1540.25 mm 2 up to 500 mg / 1540.25 mm 2 .

7. The cathode sheet of Claim 3, wherein, The lithium-containing phosphate comprises at least one of lithium iron phosphate, lithium manganese phosphate, lithium manganese iron phosphate, lithium nickel phosphate, lithium cobalt phosphate, and a modified compound of each thereof.

8. The cathode sheet of Claim 1, wherein, The positive electrode active material comprises a lithium-containing transition metal oxide.

9. The cathode electrode plate of claim 8, wherein, The mass content of the lithium-containing transition metal oxide is ≥ 90% based on the total mass of the positive electrode active material.

10. The cathode sheet of Claim 9, wherein, The coating weight of the positive electrode film layer is ≥ 300 mg / 1540.25 mm 2 .

11. The cathode sheet of Claim 10, wherein, The coating weight of the positive electrode film layer is 300 mg / 1540.25 mm 2 up to 500 mg / 1540.25 mm 2 .

12. The cathode sheet of Claim 8, wherein, The lithium transition metal oxide comprises at least one of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and a modified compound of each thereof.

13. The cathode sheet of Claim 1, wherein, The mass content of the lyophilic polymer is ≤ 5% based on the total mass of the positive electrode film layer.

14. The cathode sheet of claim 13, wherein, The mass content of the lyophilic polymer is ≤ 1%.

15. The cathode sheet of Claim 1, wherein, The positive electrode film layer comprises a plurality of sub-layers, and the coating weight of the plurality of sub-layers gradually decreases from the positive electrode current collector to the positive electrode film layer.

16. The cathode sheet of claim 15, wherein, The plurality of sub-layers comprises a first layer and a second layer, the first layer is arranged on the surface of the positive electrode current collector, and the second layer is located on the side of the first layer away from the positive electrode current collector, and the coating weight of the first layer is greater than that of the second layer.

17. The cathode sheet of Claim 16, wherein, The mass content of the lyophilic polymer in the first layer is greater than that in the second layer.

18. The cathode sheet of Claim 1, wherein, The glass transition temperature of the fluoropolymer is T g1 °C, -30 ≤ T g1 ≤ 40.

19. The cathode sheet of Claim 1, wherein, The fluorinated polymer comprises at least one of a compound represented by formula (AI) to a compound represented by formula (AIII), Formula (AI), Formula (AII), In formula (AI) and formula (AII), R 11 , R 12 , R 13 , and R 14 each independently include a hydrogen atom, a fluorine atom, a chlorine atom, a bromine atom, a substituted or unsubstituted C1-C3 alkyl group, or a substituted or unsubstituted C1-C3 alkoxy group, and R 11 , R 12 , R 13 , and R 14 at least one of which includes a fluorine atom; formula (AIII), In formula (AIII), R 15 including a single bond, substituted or unsubstituted C1-C3alkyl; p is a positive integer selected from 1 to 3; n is a positive integer selected from 1000 to 30000.

20. The cathode sheet of Claim 1, wherein, 1＜K1≤100。 21. The cathode sheet of Claim 20, wherein, 1＜K1≤10。 22. The cathode sheet of Claim 1, wherein, The ether-based polymer has a glass transition temperature of T g2 °C, -20 ≤ T g2 ≤ 35.

23. The cathode sheet of Claim 1, wherein, The ether polymer comprises at least one of a compound represented by formula (BI) and a compound represented by formula (BII), Formula (BI), In formula (BI), R 21 and R 22 each independently includes a hydrogen atom, a substituted or unsubstituted C1-C3 alkyl group, or a substituted or unsubstituted C1-C3 alkoxy group; R 23 includes a substituted or unsubstituted C1-C5 alkylene group; Formula (BII), In formula (BII), R 24 to R 27 each independently includes a hydrogen atom, a substituted or unsubstituted C1-C3 alkyl group, a substituted or unsubstituted C1-C3 alkoxy group, or an ether group, and R 24 to R 27 at least one of which includes a substituted or unsubstituted C1-C3 alkoxy group or an ether group; The polymerization degree n of the ether polymer is a positive integer selected from 1500 to 25000.

24. The cathode sheet of Claim 1, wherein, 1＜K2≤100。 25. The cathode sheet of Claim 24, wherein, 1＜K2≤10。 26. The cathode sheet of Claim 1, wherein, The glass transition temperature of the ester polymer is T g3 °C, -20 ≤ T g3 ≤ 35.

27. The cathode sheet of Claim 1, wherein, The ester polymer comprises at least one of a compound represented by formula (CI) to a compound represented by formula (CIII), Formula (CI), In formula (CI), R 31 , R 32 , and R 33 each independently include a hydrogen atom, or a substituted or unsubstituted C1-C8alkyl group; R 34 includes a substituted or unsubstituted C1-C8alkyl group, or a substituted or unsubstituted C1-C8hydroxyalkyl group; Formula (CII), In formula (CII), R 35 including substituted or unsubstituted C2-C6alkylene; Formula (CIII), In formula (CIII), R 36 , R 37 , and R 38 each independently include a hydrogen atom, or a substituted or unsubstituted C1-C8alkyl group; R 39 includes a substituted or unsubstituted C1-C8alkyl group. The polymerization degree n of the ester polymer is a positive integer selected from 800 to 20000.

28. The cathode sheet of Claim 27, wherein, R 35 each independently includes substituted or unsubstituted C2-C4alkylene.

29. The cathode sheet of Claim 27, wherein, R 36 , R 37 , and R 38 each independently comprises a hydrogen atom, a substituted or unsubstituted C1-C4alkyl group.

30. The cathode sheet of Claim 1, wherein, 0.8≤K3≤100。 31. The cathode sheet of Claim 30, wherein, 0.8≤K3≤10。 32. The cathode sheet of Claim 1, wherein, The glass transition temperature of the aldehyde ketone polymer is T g4 °C, -20 ≤ T g4 ≤ 35.

33. The cathode sheet of Claim 1, wherein, The aldehyde-ketone polymer comprises at least one of a compound represented by formula (DI) and a compound represented by formula (DII), Formula (DI), In formula (DI), R 41 including a single bond, substituted or unsubstituted C1-C6alkylene; R 42 including a hydrogen atom, substituted or unsubstituted C1-C6alkyl; Equation (DII), In formula (DII), R 43 to R 46 each independently includes 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 an integer selected from 0 to 5, and at least one of r and s is a positive integer; The polymerization degree n of the aldehyde-ketone polymer is a positive integer selected from 500 to 15000.

34. The cathode sheet of Claim 1, wherein, The lyotropic polymer has a molecular weight of 2.0 x 10 5 g / mol to 1.2 x 10 6 g / mol.

35. A battery comprising the positive electrode sheet according to any one of claims 1 to 34.

36. An electrical device comprising the battery according to claim 35.

Images