Battery cell and preparation method therefor, and electric device

Abstract

Embodiments of the present application disclose a battery cell and a preparation method therefor, and an electric device. While improving the cycle life and battery capacity of the battery cell, the risk of detachment of an active material film layer of an electrode sheet can be reduced. The battery cell comprises a solid-state electrolyte layer and an electrode sheet, the electrode sheet comprises a composite current collector and an active material film layer, the active material film layer is provided on at least one side surface of the composite current collector, and the active material film layer comprises a sulfide electrolyte; and the composite current collector comprises a current collector body and a primer coating, the primer coating is provided on at least one side surface of the current collector body, the primer coating comprises a primer, and the primer has a solubility parameter S in a low-polarity solvent satisfying: 15(J / cm3)1 / 2≤S≤19(J / cm3)1 / 2, wherein a polarity parameter P' of the low-polarity solvent satisfies: 0<P'≤2.5.

Description

Battery cells and their preparation methods, and electrical devices

[0001] Cross-references to related applications

[0002] This application claims priority to Chinese Patent Application No. 202510120765.7, filed on January 24, 2025, entitled “Battery Cell and Method for Preparation Thereof, Electrical Device”, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application relates to the field of battery technology, and more specifically, to a battery cell, a method for preparing the same, and an electrical device thereof. Background Technology

[0004] The development of battery technology must consider multiple design factors simultaneously, such as energy density, cycle life, discharge capacity, charge / discharge rate, safety, and reliability. Solid-state electrolytes are non-flammable, non-corrosive, non-volatile, and leak-free, making all-solid-state batteries extremely safe. However, the solid nature of the electrolyte leads to poor compatibility at the electrode / electrolyte interface, affecting ion transport and thus impacting the cycle life, capacity, and other performance characteristics of solid-state batteries.

[0005] To improve the cycle life and capacity of solid-state batteries, appropriate solid electrolytes are added to the active material film layer of the electrodes to increase the transport of metal ions. For example, in sulfide solid-state batteries, sulfide electrolytes are added to the active material film layer to improve cycle life and capacity. However, to avoid side reactions of the sulfide electrolyte, low-polarity solvents are used as solvents for the active material slurry, and correspondingly, low-polarity polymers are used as binders. These binders have weak adhesion, resulting in poor adhesion between the active material film layer and the current collector, poor structural stability of the electrode, and in severe cases, detachment of the active material film layer. Therefore, how to improve the cycle life and capacity of solid-state batteries while reducing the risk of active material film layer detachment is a pressing problem that needs to be solved. Summary of the Invention

[0006] This application is made in view of the above-mentioned problems, and its purpose is to provide a solution that reduces the risk of active material film layer shedding from the electrode while improving the cycle life and battery capacity of solid-state batteries.

[0007] To achieve the above objectives, this application provides a battery cell, a method for preparing the same, and an electrical device thereof.

[0008] In a first aspect, a battery cell is provided, comprising: a solid electrolyte layer and a pole piece; the pole piece includes a composite current collector and an active material film layer, the active material film layer is disposed on at least one surface of the composite current collector, and the active material film layer includes a sulfide electrolyte; the composite current collector includes a current collector body and a primer coat, the primer coat is disposed on at least one surface of the current collector body, the primer coat includes a primer adhesive, and the solubility parameter S of the primer adhesive in a low-polarity solvent satisfies: 15 (J / cm 3 ) 1 / 2 ≤S≤19 (J / cm 3 ) 1 / 2 , wherein the polarity parameter P' of the low-polarity solvent satisfies: 0 < P' ≤ 2.5.

[0009] In an embodiment of the present application, a sulfide electrolyte is added to the active material film layer of the pole piece to increase the transport of metal ions in the electrode, and the performance such as the cycle life and battery capacity of the battery can be improved. At the same time, a primer coat is provided between the active material film layer of the pole piece and the current collector body. The solubility parameter S of the primer adhesive in the primer coat in a low-polarity solvent (the polarity parameter P' of the solvent satisfies: 0 < P' ≤ 2.5) satisfies: 15 (J / cm 3 ) 1 / 2 ≤S≤19 (J / cm 3 ) 1 / 2 . Thus, during the preparation of the pole piece, when the slurry of the active material film layer is coated on the primer coat, the primer adhesive will partially infiltrate into the slurry of the active material film layer. After drying, the side of the active material film layer close to the current collector is infiltrated with the primer adhesive and bonded to the current collector through the primer adhesive, increasing the bonding stability between the active material film layer and the current collector and reducing the risk of the active material film layer peeling off. Therefore, the technical solution of the present application can reduce the risk of the active material film layer peeling off the pole piece while improving the cycle life and battery capacity of the solid-state battery.

[0010] In a possible implementation manner, the primer adhesive includes at least one of a low-polarity rubber material, a low-polarity plastic material, a functionalized styrene-diene copolymer, and a derivative of the functionalized styrene-diene copolymer.

[0011] The above materials have good compatibility in low-polarity solvents. When used as a primer adhesive, they can be well compatible with the low-polarity solvents in active material film layer slurry, so that the dried active material film layer is infiltrated with the primer adhesive, increasing the bonding stability between the active material film layer and the current collector and reducing the risk of the active material film layer peeling off.

[0012] In a possible implementation manner, the low-polarity rubber material includes at least one of natural rubber, ethylene propylene diene monomer rubber, polyisobutylene, styrene-butadiene rubber, and hydrogenated styrene-butadiene rubber.

[0013] In one possible implementation, the low-polarity plastic material includes at least one of cyclic olefin copolymers and ethylene-α-olefin copolymers.

[0014] In one possible implementation, the functionalized styrene-diolefin copolymer includes at least one of the following: (styrene-butadiene-styrene) triblock copolymer, (polystyrene-(ethylene-butene copolymer)-polystyrene) triblock copolymer, hydrogenated (styrene-isoprene-styrene) triblock copolymer, fluorobutadiene-styrene copolymer, methoxy-functionalized butadiene-styrene copolymer, fluoropentylene-styrene copolymer, methoxy-functionalized pentylene-styrene copolymer, hydrogenated fluorobutadiene-styrene copolymer, hydrogenated methoxy-functionalized butadiene-styrene copolymer, hydrogenated fluoropentylene-styrene copolymer, and hydrogenated methoxy-functionalized pentylene-styrene copolymer.

[0015] In one possible implementation, the base coating further includes a conductive agent, which includes at least one of conductive carbon black, carbon nanotubes, and carbon fibers.

[0016] Adding conductive agents to the base coating can increase the conductivity of the electrode and improve its electronic conductivity, thereby improving the cycle performance and lifespan of the battery.

[0017] In one possible implementation, the mass ratio of the primer to the conductive agent in the base coating layer ranges from 1:9 to 8:2.

[0018] By setting the mass ratio of the primer and the conductive agent within a suitable range, the bonding stability between the active material film and the current collector can be improved, as can the conductivity of the electrode, which is beneficial to improving the overall performance of the battery.

[0019] In one possible implementation, the thickness L of the undercoat layer satisfies: 0.1 μm ≤ L ≤ 10 μm.

[0020] By setting the thickness of the base coating within the aforementioned range, the adhesion between the current collector and the active material film can be effectively improved, while avoiding excessive overall thickness of the electrode sheet, thereby controlling the overall volume of the battery cell within a suitable range.

[0021] In one possible implementation, the active material film layer further includes the primer.

[0022] In a possible implementation, the active material film layer further includes a binder, and the binder includes at least one of ethylene-propylene rubber, ethylene-α-olefin copolymer, ethylene-cycloolefin copolymer, polybutadiene, polyisoprene, polyisobutene, styrene-butadiene rubber, (styrene-butadiene-styrene) triblock copolymer, (styrene-isoprene-styrene) triblock copolymer, hydrogenated styrene-butadiene rubber, hydrogenated (styrene-butadiene-styrene) triblock copolymer, and hydrogenated (styrene-isoprene-styrene) triblock copolymer.

[0023] In a possible implementation, the electrode is a positive electrode.

[0024] In a second aspect, a method for preparing a battery cell is provided, including: providing a solid electrolyte and an electrode to prepare the battery cell; wherein, providing the electrode includes: mixing a primer and a first solvent to obtain a primer layer slurry; coating the primer layer slurry on at least one side surface of a current collector body to provide a composite current collector; mixing a sulfide electrolyte and a second solvent to obtain an active material film layer slurry, and the polarity parameter P' of the second solvent satisfies: 0 < P' ≤ 2.5; coating the active material film layer slurry on at least one side surface of the composite current collector to provide the electrode; wherein, the solubility parameter S of the primer in the second solvent satisfies: 15 (J / cm 3 ) 1 / 2 ≤ S ≤ 19 (J / cm 3 ) 1 / 2 .

[0025] In the embodiments of the present application, the solubility parameter S of the primer in the second solvent satisfies:​​​​​​​​​​​​​In one possible implementation, the second solvent includes at least one of alkane solvents and benzene solvents; the alkane solvent includes at least one of pentane, hexane, heptane, octane, nonane, decane, undecane, dodecane, tridecane, tetradecane, pentadecane, cycloalkanes, and bicycloalkanes; the benzene solvent includes at least one of toluene, xylene, trimethylbenzene, and tetrahydronaphthalene.

[0028] In one possible implementation, the primer comprises at least one of a low-polarity rubber material, a low-polarity plastic material, a functionalized styrene-diolefin copolymer, and a derivative of a functionalized styrene-diolefin copolymer.

[0029] The above-mentioned materials have good compatibility in low-polarity solvents. When used as a primer, they can be well compatible with the low-polarity solvents in the active material film slurry, so that the dried active material film is impregnated with the primer, which can increase the bonding stability between the active material film and the current collector and reduce the risk of the active material film falling off.

[0030] In one possible implementation, the low-polarity rubber material includes at least one of natural rubber, EPDM rubber, polyisobutylene, styrene-butadiene rubber, and hydrogenated styrene-butadiene rubber.

[0031] In one possible implementation, the low-polarity plastic material includes at least one of cyclic olefin copolymers and ethylene-α-olefin copolymers.

[0032] In one possible implementation, the functionalized styrene-diolefin copolymer includes at least one of the following: (styrene-butadiene-styrene) triblock copolymer, (polystyrene-(ethylene-butene copolymer)-polystyrene) triblock copolymer, hydrogenated (styrene-isoprene-styrene) triblock copolymer, fluorobutadiene-styrene copolymer, methoxy-functionalized butadiene-styrene copolymer, fluoropentylene-styrene copolymer, methoxy-functionalized pentylene-styrene copolymer, hydrogenated fluorobutadiene-styrene copolymer, hydrogenated methoxy-functionalized butadiene-styrene copolymer, hydrogenated fluoropentylene-styrene copolymer, and hydrogenated methoxy-functionalized pentylene-styrene copolymer.

[0033] In one possible implementation, the solid content W of the slurry in the base coating layer satisfies: 1% ≤ W ≤ 50%.

[0034] Thirdly, an electrical device is provided, comprising a battery cell as described in the first aspect and any possible implementation thereof, and / or a battery cell obtained by the preparation method of the second aspect. Attached Figure Description

[0035] 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.

[0036] Figure 1 is a schematic diagram of the structure of an electrode sheet according to an embodiment of this application;

[0037] Figure 2 is a schematic diagram of a battery cell according to an embodiment of this application;

[0038] Figure 3 is a schematic diagram of a method for preparing a battery cell according to an embodiment of this application;

[0039] Figure 4 is a schematic diagram of a battery according to an embodiment of this application;

[0040] Figure 5 is a schematic diagram of an electrical device according to an embodiment of this application. Detailed Implementation

[0041] The battery cell and its preparation method, as well as the embodiments of the electrical device, of this application have been described in detail with reference to the accompanying drawings. 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 making the following description unnecessarily lengthy and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0042] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in the description of this application is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms "comprising" and "having," and any variations thereof, in the description, claims, and accompanying drawings of this application are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the description, claims, or accompanying drawings of this application are used to distinguish different objects, not to describe a specific order or hierarchy.

[0043] In this application, the reference to "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this application can be combined with other embodiments.

[0044] 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 a 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 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 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: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" 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 "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0045] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0046] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0047] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates 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.

[0048] In this embodiment of the application, the battery cell can be a secondary battery, which refers to a battery cell that can be recharged to activate the active materials and continue to be used after the battery cell has been discharged.

[0049] The battery cell can be a lithium-ion battery, sodium-ion battery, sodium-lithium-ion battery, lithium metal battery, sodium metal battery, lithium-sulfur battery, magnesium-ion battery, etc., and the embodiments of this application are not limited to this.

[0050] In some embodiments, the battery cell in this application can be a metal battery. Specifically, the metal battery may include lithium metal secondary batteries, sodium metal batteries, or magnesium metal batteries, etc. This application does not limit this.

[0051] The development of battery technology must consider multiple design factors simultaneously, such as energy density, cycle life, discharge capacity, charge / discharge rate, safety, and reliability. Solid-state electrolytes (SSEs) are non-flammable, non-corrosive, non-volatile, and leak-free, resulting in all-solid-state batteries with extremely high safety. The structure of an all-solid-state battery includes a positive electrode, an electrolyte, and a negative electrode. The solid electrolyte acts as a separator, hindering electron transport while conducting metal ions, significantly simplifying the battery construction process. Although there are virtually no side reactions involving the decomposition of the solid electrolyte at the electrode material interface, the solid nature of the electrolyte results in poor compatibility at the electrode / electrolyte interface, affecting ion transport and thus impacting the cycle life, battery capacity, and other performance characteristics of the solid-state battery.

[0052] To improve the cycle life and capacity of solid-state batteries, appropriate solid electrolytes are added to the active material film layer of the electrodes to increase the transport of metal ions. For example, in sulfide solid-state batteries, sulfide electrolytes are added to the active material film layer to improve cycle life and capacity. However, during electrode fabrication, to avoid side reactions of the sulfide electrolyte, low-polarity solvents are used as solvents for the active material slurry, and correspondingly, low-polarity polymers are used as binders. These binders have weak adhesion, and under high-temperature drying conditions, they tend to float away from the current collector, resulting in poor adhesion between the active material film layer and the current collector. During subsequent electrode die-cutting, the edges of the active material film layer detach from the current collector, leading to substandard electrode quality, wasted materials, and increased production costs. Therefore, how to improve the cycle life and capacity of solid-state batteries while reducing the risk of active material film detachment is a pressing issue that needs to be addressed.

[0053] In view of this, this application provides a battery cell, the electrode of which includes a composite current collector and an active material film layer. The active material film layer is disposed on at least one surface of the composite current collector, and the active material film layer includes a sulfide electrolyte. The composite current collector includes a current collector body and a base coating layer. The base coating layer is disposed on at least one surface of the current collector body, and the base coating layer includes a base adhesive. The solubility parameter S of the base adhesive in a low polarity solvent satisfies: 15 (J / cm³). 3 ) 1 / 2 ≤S≤19(J / cm 3 ) 1 / 2, wherein the polarity parameter P' of the low-polarity solvent satisfies: 0 < P' ≤ 2.5. In the technical solution of the present application, a sulfide electrolyte is added to the active material film layer of the electrode sheet to increase the transport of metal ions in the electrode, and the performance such as the cycle life and battery capacity of the battery can be improved. At the same time, a bottom coating is provided between the active material film layer of the electrode sheet and the current collector body, and the solubility parameter S of the bottom coating adhesive in the low-polarity solvent satisfies: 15 (J / cm 3 ) 1 / 2 ≤ S ≤ 19 (J / cm 3 ) 1 / 2 . Thus, during the preparation of the electrode sheet, when the slurry of the active material film layer is coated on the bottom coating, the bottom coating adhesive will partially infiltrate into the slurry of the active material film layer. After drying, the side of the active material film layer close to the composite current collector is infiltrated with the bottom coating adhesive, and is bonded to the current collector body through the bottom coating adhesive, increasing the bonding stability between the active material film layer and the current collector body and reducing the risk of the active material film layer peeling off.

[0054] [Battery cell]

[0055] An embodiment of the present application provides a battery cell, which includes a solid electrolyte layer and an electrode sheet.

[0056] The electrode sheet of the present application can be a negative electrode sheet and / or a positive electrode sheet. The battery cell of the present application is a solid-state battery cell, and the solid electrolyte layer can be disposed between the positive electrode sheet and the negative electrode sheet.

[0057] FIG. 1 is a schematic structural diagram of an electrode sheet according to an embodiment of the present application. For example, as shown in FIG. 1, the electrode sheet 1 includes a composite current collector 10 and an active material film layer 11 provided on at least one side surface of the composite current collector 10.

[0058] The composite current collector 10 has two side surfaces opposite to each other along its own thickness direction. Among them, the active material film layer 11 can be provided on one side surface of the composite current collector 10, or can be provided on both side surfaces of the composite current collector 10. As an example, as shown in FIG. 1, the active material film layer 11 is provided on both side surfaces of the composite current collector 10.

[0059] The active material film layer 11 includes a sulfide electrolyte.

[0060] Adding a sulfide electrolyte to the active material film layer 11 can increase the transport of metal ions in the electrode, which is beneficial to improving the performance such as the cycle life and battery capacity of the battery.

[0061] For example, the sulfide electrolyte may include LiSPCl. In this embodiment, the volume average particle size of LiSPCl ranges from 100 nm to 100 μm. For example, the sulfide electrolyte may be LiSPCl with a volume average particle size of 600 nm.

[0062] As shown in Figure 1, the composite current collector 10 includes a current collector body 101 and a base coating 102, with the base coating 102 disposed on at least one side surface of the current collector body 101.

[0063] The current collector body 101 has two opposing surfaces along its thickness direction. The base coating 102 can be disposed on one surface of the current collector body 101 or on both surfaces. As an example, as shown in FIG1, the base coating 102 is disposed on both surfaces of the current collector body 101.

[0064] It should be noted that in this embodiment, when both sides of the composite current collector 10 are provided with an active material film layer 11, both sides of the current collector body 101 need to be provided with a base coating layer 102.

[0065] As an example, electrode 1 is a positive electrode, current collector body 101 can be aluminum foil, and active material film layer 11 (also called positive electrode film layer) includes positive electrode active material.

[0066] For example, the positive electrode active material includes a lithium phosphate with an olivine structure, which includes one or more of lithium iron phosphate, lithium manganese iron phosphate, lithium iron phosphate, and lithium titanate.

[0067] The positive electrode active material may include one or more of the following: a layered lithium-containing transition metal oxide and a spinel-structured lithium salt.

[0068] Layered lithium-containing transition metal oxides can include ternary materials such as lithium nickel cobalt manganese oxide and lithium-rich manganese-based materials. For example, ternary materials can be LiNi. 0.8 Co 0.1 Mn 0.1 O2, LiNi 0.6 Co 0.2 Mn 0.2 O2. For example, other metallic elements can be doped into ternary materials to improve certain properties. For instance, Zr, Al, and other materials can be doped.

[0069] Lithium-containing phosphates with an olivine structure may also include one or more of lithium manganese phosphate and lithium iron manganese phosphate.

[0070] Spinel-structured lithium salts can include lithium manganese oxide.

[0071] As an example, electrode 1 is a negative electrode, current collector body 101 can be copper foil, and active material film layer 11 (also called negative electrode film layer) includes negative electrode active material.

[0072] The base coating 102 includes a base adhesive, the solubility parameter S of which in a low-polarity solvent satisfies: 15 (J / cm³). 3 ) 1 / 2 ≤S≤19(J / cm 3 ) 1 / 2 .

[0073] The polarity parameter of a solvent is a parameter that characterizes the magnitude of its polarity. It refers to the relative positions of the centers of positive and negative charges in the molecule. If the centers of positive and negative charges coincide, the molecule is nonpolar; if the centers of positive and negative charges do not coincide, the molecule is polar. The larger the polarity parameter, the greater the polarity of the solvent.

[0074] The polarity parameters of a solvent can be reflected by measuring physical quantities such as its dielectric constant, refractive index, and surface tension. These physical quantities can indirectly reflect the magnitude of the solvent's polarity.

[0075] As an example, the polarity parameter of a solvent can be calculated using standardized probe molecules (such as nitrobenzene, aniline, etc.) interacting with the solvent, through spectral or thermodynamic data. For instance, the polarity parameter of the test solvent can be calculated by measuring the spectral shift (such as the change in absorption or emission wavelength) of the probe molecule in the test solvent.

[0076] In this embodiment, the polarity parameter P' of the low-polarity solvent satisfies: 0 <P’≤2.5。

[0077] For example, the polarity parameter P' of the low polarity solvent can be 0.5, 1, 1.2, 1.5, 1.7, 2, 2.3, 2.5, or its value can be within the range obtained by any combination of the above two values.

[0078] In this embodiment, the solubility parameter (SP) is a physical constant that measures the compatibility of liquid materials (including rubber, since rubber is liquid under processing conditions). Its physical meaning is the square root of the material's cohesive energy density.

[0079] For example, the solubility parameter S of the primer in a low-polarity solvent can be 15 (J / cm³). 3 ) 1 / 2 16 (J / cm) 3 ) 1 / 2 17 (J / cm) 3 ) 1 / 2 17.5 (J / cm) 3 ) 1 / 2 18 (J / cm)3 ) 1 / 2 18.5 (J / cm) 3 ) 1 / 2 19 (J / cm) 3 ) 1 / 2 , or its value is within the range obtained by combining any two of the above values.

[0080] In this embodiment, the solubility parameter S of the primer in the low polarity solvent satisfies the above conditions. Therefore, the primer has good compatibility in the low polarity solvent. During the preparation of the electrode, when the slurry of the active material film layer 11 is coated onto the primer layer 102, the primer is immersed in the slurry of the active material film layer 11. After drying, the side of the active material film layer 11 near the composite current collector 10 is immersed in the primer and is bonded to the current collector body 101 through the primer, which increases the bonding stability between the active material film layer 11 and the current collector body 101 and reduces the risk of the active material film layer 11 falling off.

[0081] For example, low-polarity solvents may include alkane solvents or benzene solvents. Alkane solvents include pentane, hexane, heptane, octane, nonane, decane, undecane, dodecane, tridecane, tetradecane, pentadecane, cycloalkanes, and bicycloalkanes; benzene solvents include toluene, xylene, trimethylbenzene, and tetrahydronaphthalene.

[0082] In some embodiments, the primer includes at least one of a low-polarity rubber material, a low-polarity plastic material, a functionalized styrene-diolefin copolymer, and a derivative of a functionalized styrene-diolefin copolymer.

[0083] Specifically, low-polarity rubber materials include at least one of natural rubber, EPDM rubber, polyisobutylene, styrene-butadiene rubber, and hydrogenated styrene-butadiene rubber.

[0084] Specifically, low-polarity plastic materials include at least one of cyclic olefin copolymers and ethylene-α-olefin copolymers.

[0085] Specifically, functionalized styrene-diolefin copolymers include at least one of the following: (styrene-butadiene-styrene) triblock copolymers, (polystyrene-(ethylene-butene copolymer)-polystyrene) triblock copolymers, hydrogenated (styrene-isoprene-styrene) triblock copolymers, fluorobutadiene-styrene copolymers, methoxy-functionalized butadiene-styrene copolymers, fluoropentylene-styrene copolymers, methoxy-functionalized pentylene-styrene copolymers, hydrogenated fluorobutadiene-styrene copolymers, hydrogenated methoxy-functionalized butadiene-styrene copolymers, hydrogenated fluoropentylene-styrene copolymers, and hydrogenated methoxy-functionalized pentylene-styrene copolymers.

[0086] As an example, the primer is styrene-butadiene rubber (SBR), and the low-polarity solvent in the active material film layer 11 slurry is toluene, with a polarity parameter of 2.4. The solubility parameter S of SBR in toluene is 17.4 (J / cm³). 3 ) 1 / 2 .

[0087] In this embodiment, a sulfide electrolyte is added to the active material film layer 11 of the electrode to increase the transport of metal ions in the electrode, thereby improving the cycle life and capacity of the battery. Simultaneously, a base coating layer 102 is provided between the active material film layer 11 of the electrode and the current collector body. The solubility parameter S of the base coating adhesive in the base coating layer 102 in a low-polarity solvent satisfies: 15 (J / cm³). 3 ) 1 / 2 ≤S≤19(J / cm 3 ) 1 / 2 Thus, during the preparation of the electrode, when the slurry of the active material film layer 11 is coated onto the base coating layer 102, the base coating adhesive will partially wet into the slurry of the active material film layer 11. After drying, the side of the active material film layer 11 closest to the current collector is wetted with the base coating adhesive, and it is bonded to the current collector through the base coating adhesive, which increases the bonding stability between the active material film layer 11 and the current collector and reduces the risk of the active material film layer 11 falling off.

[0088] In some embodiments, the base coating 102 further includes a conductive agent, which includes at least one of conductive carbon black, carbon nanotubes, and carbon fibers.

[0089] Adding a conductive agent to the base coating 102 can increase the conductivity of the electrode and improve its electronic conductivity, thereby improving the cycle performance and lifespan of the battery.

[0090] In some embodiments, the mass ratio of the primer adhesive to the conductive agent in the primer layer 102 ranges from 1:9 to 8:2.

[0091] For example, the mass ratio of the primer to the conductive agent can be 1:9, 1:8, 1:6, 1:5, 1:3, 1:2, 1:1, 2:1, 3:1, 8:2, or a ratio within the range obtained by any combination of the above two ratios.

[0092] By setting the mass ratio of the base coating adhesive and the conductive agent within a suitable range, the bonding stability between the active material film layer 11 and the composite current collector 10 can be improved, as can the conductivity of the electrode 1, which is beneficial to improving the overall performance of the battery.

[0093] In some embodiments, as shown in FIG1, the thickness of the base coating 102 is L, where L satisfies: 0.1μm≤L≤10μm.

[0094] For example, L can be 0.1μm, 0.5μm, 1μm, 2μm, 5μm, 7μm, 9μm, 10μm, or a value within the range obtained by any combination of the above two values.

[0095] In this embodiment, the thickness of the base coating 102 is set within the above-mentioned range. This effectively improves the adhesion between the current collector and the active material film layer 11 while avoiding excessive thickness of the electrode sheet, thereby controlling the overall volume of the battery cell within a suitable range.

[0096] In some embodiments, the active material film layer 11 further includes an undercoat.

[0097] In this embodiment, due to the solubility of the base coating adhesive in low polar solvents, during the preparation of the electrode, when the slurry of the active material film layer 11 is coated onto the base coating layer 102, the base coating adhesive will partially infiltrate into the slurry of the active material film layer 11. After the slurry of the active material film layer 11 is dried at high temperature to obtain the active material film layer 11, the active material film layer 11 contains the base coating adhesive.

[0098] In some embodiments, the active material membrane layer 11 further includes an adhesive, which includes at least one of the following: ethylene propylene rubber, ethylene-α-olefin copolymer, ethylene-cycloolefin copolymer, polybutadiene, polyisoprene, polyisobutylene, styrene-butadiene rubber, (styrene-butadiene-styrene) triblock copolymer, (styrene-isoprene-styrene) triblock copolymer, hydrogenated styrene-butadiene rubber, hydrogenated (styrene-butadiene-styrene) triblock copolymer, and hydrogenated (styrene-isoprene-styrene) triblock copolymer.

[0099] In this embodiment, the binder in the active material film layer 11 and the primer in the base layer 102 can be of the same type of material or different types of material; this application does not limit this.

[0100] 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. The battery cell can be a lithium-ion battery, a lithium-sulfur battery, a sodium-ion battery, a magnesium-ion battery, etc.

[0101] Figure 2 is a schematic diagram of a battery cell according to an embodiment of this application. For example, as shown in Figure 2, the battery cell 3 is a square battery cell. The battery cell 3 includes a housing 31, an end cap assembly 32, and an electrode assembly 33 disposed in the housing 31.

[0102] The electrode assembly 33 can be made from a positive electrode, a negative electrode, and a solid electrolyte layer through a winding process or a stacking process.

[0103] The end cap assembly 32 includes electrode terminals 322, as shown in FIG2. The end cap assembly 32 includes two electrode terminals 322, one of which is a positive electrode terminal and the other is a negative electrode terminal.

[0104] The battery cell 3 also includes a current collector 34, which is used to connect the tab 332 and the electrode terminal 322 of the electrode assembly 33. For example, in the case of a positive electrode in this embodiment, one current collector 34 is used to connect the tab and the positive electrode terminal of the positive electrode, and another current collector 34 is used to connect the tab and the negative electrode terminal of the negative electrode.

[0105] In some embodiments, the battery cell 3 includes an electrode assembly 33, which includes an electrode assembly body 331 and a tab 332 extending from the electrode assembly body 331.

[0106] In some embodiments, individual battery cells can be assembled into a battery module. The number of individual battery cells contained in a battery module can be one or more, and the specific number can be selected by those skilled in the art based on the application and capacity of the battery module.

[0107] [Positive electrode plate]

[0108] The positive electrode includes a positive current collector and a positive electrode film layer disposed on at least one surface of the positive current collector, the positive electrode film layer including a positive electrode active material.

[0109] As an example, the positive current collector has two surfaces opposite each other in its own thickness direction, and the positive electrode film layer is disposed on either or both of the two opposite surfaces of the positive current collector.

[0110] In some embodiments, the positive electrode current collector may be a metal foil or a composite positive electrode current collector. For example, aluminum foil may be used as the metal foil. The composite positive electrode current collector may include a polymer material substrate and a metal layer formed on at least one surface of the polymer material substrate. The composite positive electrode current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0111] In some embodiments, the positive electrode active material may be a known battery positive electrode active material. As an example, the positive electrode active material may include at least one of the following materials: lithium phosphates with an olivine structure, lithium transition metal oxides, and their respective modified compounds. However, this application is not limited to these materials, and other conventional materials that can be used as battery positive electrode active materials may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium transition metal oxides include, but are not limited to, lithium cobalt oxides (such as LiCoO2), lithium nickel oxides (such as LiNiO2), lithium manganese oxides (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxides, lithium manganese cobalt oxides, lithium nickel manganese oxides, and lithium nickel cobalt manganese oxides (such as LiNi). 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also known as NCM) 333 LiNi 0.5 Co 0.2 Mn 0.3 O2 (also known as NCM) 523 LiNi 0.5 Co 0.25 Mn 0.25 O2 (also known as NCM) 211 LiNi 0.6 Co 0.2 Mn 0.2 O2 (also known as NCM) 622 LiNi 0.8 Co 0.1 Mn 0.1 O2 (also known as NCM) 811 ), lithium nickel cobalt aluminum oxide (such as LiNi) 0.85 Co 0.15 Al 0.05 At least one of O2 and its modified compounds. Examples of lithium phosphates with an olivine structure include, but are not limited to, lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), lithium iron phosphate and carbon composites, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate and carbon composites, lithium manganese iron phosphate, and lithium manganese iron phosphate and carbon composites.

[0112] In some embodiments, the positive electrode film layer may optionally include a binder. As an example, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resin.

[0113] In some embodiments, the positive electrode film may optionally include a conductive agent. As an example, the conductive agent may include at least one selected from superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0114] In some embodiments, the positive electrode sheet can be prepared by dispersing the above-mentioned components for preparing the positive electrode sheet, such as positive active material, conductive agent, binder and any other components, in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry onto the positive electrode current collector, and then obtaining the positive electrode sheet after drying, cold pressing and other processes.

[0115] During the charging and discharging process of a battery, Li undergoes insertion / extraction and consumption, resulting in varying molar Li content at different discharge states. In the examples of cathode materials in this application, the molar Li content refers to the initial state of the material, i.e., the state before feeding. When the cathode material is applied to the battery system, the molar Li content changes after charge-discharge cycles.

[0116] In the examples of cathode materials in this application, the molar content of O is only a theoretical value. Oxygen release from the crystal lattice will cause changes in the molar content of oxygen, and the actual molar content of O will fluctuate.

[0117] [Negative electrode plate]

[0118] The negative electrode sheet includes a negative current collector and a negative electrode film layer disposed on at least one surface of the negative current collector, the negative electrode film layer including a negative electrode active material.

[0119] As an example, the negative electrode current collector has two surfaces opposite each other in its own 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.

[0120] In some embodiments, the negative electrode current collector may be a metal foil or a composite negative electrode current collector. For example, copper foil may be used as the metal foil. The composite negative electrode current collector may include a polymer material substrate and a metal layer formed on at least one surface of the polymer material substrate. The composite negative electrode current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0121] In some embodiments, the negative electrode film layer may optionally include a binder. The binder may be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0122] In some embodiments, the negative electrode film may optionally include a conductive agent. The conductive agent may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0123] In some embodiments, the negative electrode film may optionally include other additives, such as thickeners (e.g., sodium carboxymethyl cellulose (CMC-Na)).

[0124] In some embodiments, the negative electrode sheet can be prepared by dispersing the components used to prepare the negative electrode sheet, such as the negative electrode active material, conductive agent, binder and any other components, in a solvent (e.g., deionized water) to form a negative electrode slurry; coating the negative electrode slurry onto the negative electrode current collector, and then obtaining the negative electrode sheet after drying, cold pressing and other processes.

[0125] [Electrolytes]

[0126] The electrolyte plays a role in conducting ions between the positive and negative electrode plates.

[0127] In this case, the electrolyte in the battery cell is a solid electrolyte. The solid electrolyte is placed between the positive electrode and the negative electrode, which not only plays the role of conducting ions, but also acts as an isolator to hinder electron transport.

[0128] Positive electrode, negative electrode and electrolyte can be made into electrode assembly by winding process or stacking process.

[0129] [Preparation methods for battery cells]

[0130] Figure 3 is a schematic diagram of a method for preparing a battery cell according to an embodiment of this application. Referring to Figure 3, the method 300 for preparing a battery cell may include the following steps.

[0131] Step 310: Provide a solid electrolyte and an electrode to prepare a battery cell.

[0132] Providing the electrode includes the following steps:

[0133] a) Mix the primer and the first solvent to obtain the primer slurry.

[0134] b) Apply the slurry of the primer layer to the surface of at least one side of the current collector body to provide a composite current collector.

[0135] c) The sulfide electrolyte and the second solvent are mixed to obtain a slurry of the active material film layer, wherein the polarity parameter P' of the second solvent satisfies: 0 <P’≤2.5。

[0136] d) Apply a slurry of the active material film layer to the surface of at least one side of the composite current collector to provide an electrode.

[0137] The solubility parameter S of the primer in the second solvent satisfies: 15 (J / cm³). 3 ) 1 / 2 ≤S≤19(J / cm 3 ) 1 / 2 .

[0138] In this embodiment, the solubility parameter S of the primer adhesive in the second solvent satisfies: 15 (J / cm³). 3 ) 1 / 2 ≤S≤19(J / cm 3 ) 1 / 2 In this way, during the preparation of the electrode, when the slurry of the active material film is coated onto the base coating, the base coating adhesive will partially wet into the slurry of the active material film. After drying, the side of the active material film closest to the current collector is wetted with the base coating adhesive, and it is bonded to the current collector through the base coating adhesive, which increases the bonding stability between the active material film and the current collector and reduces the risk of the active material film falling off.

[0139] In some embodiments, the first solvent includes at least one of alkane solvents and benzene solvents.

[0140] For example, alkane solvents include at least one of pentane, hexane, heptane, octane, nonane, decane, undecane, dodecane, tridecane, tetradecane, pentadecane, cycloalkanes, and bicycloalkanes.

[0141] For example, benzene solvents include at least one of toluene, xylene, trimethylbenzene, and tetrahydronaphthalene.

[0142] In some embodiments, the second solvent includes at least one of alkane solvents and benzene solvents.

[0143] For example, alkane solvents include at least one of pentane, hexane, heptane, octane, nonane, decane, undecane, dodecane, tridecane, tetradecane, pentadecane, cycloalkanes, and bicycloalkanes.

[0144] For example, benzene solvents include at least one of toluene, xylene, trimethylbenzene, and tetrahydronaphthalene.

[0145] In the embodiments of this application, the first solvent and the second solvent may be the same type of solvent or different types of solvent, and this application does not limit this.

[0146] In some embodiments, the primer includes at least one of a low-polarity rubber material, a low-polarity plastic material, a functionalized styrene-diolefin copolymer, and a derivative of a functionalized styrene-diolefin copolymer.

[0147] Specifically, low-polarity rubber materials include at least one of natural rubber, EPDM rubber, polyisobutylene, styrene-butadiene rubber, and hydrogenated styrene-butadiene rubber.

[0148] Specifically, low-polarity plastic materials include at least one of cyclic olefin copolymers and ethylene-α-olefin copolymers.

[0149] Specifically, functionalized styrene-diolefin copolymers include at least one of the following: (styrene-butadiene-styrene) triblock copolymers, (polystyrene-(ethylene-butene copolymer)-polystyrene) triblock copolymers, hydrogenated (styrene-isoprene-styrene) triblock copolymers, fluorobutadiene-styrene copolymers, methoxy-functionalized butadiene-styrene copolymers, fluoropentylene-styrene copolymers, methoxy-functionalized pentylene-styrene copolymers, hydrogenated fluorobutadiene-styrene copolymers, hydrogenated methoxy-functionalized butadiene-styrene copolymers, hydrogenated fluoropentylene-styrene copolymers, and hydrogenated methoxy-functionalized pentylene-styrene copolymers.

[0150] In some embodiments, the solid content W of the primer slurry satisfies: 1% ≤ W ≤ 50%.

[0151] For example, W can be 1%, 5%, 7%, 10%, 15%, 20%, 30%, 40%, 45%, 50%, or a value within the range obtained by any combination of the above two values.

[0152] [Battery]

[0153] This application provides a battery, including the battery cells described in the above embodiments. Figure 4 is a schematic diagram of a battery according to an embodiment of this application. As shown in Figure 4, the battery 5 may include multiple battery cells (not shown in the figure).

[0154] Battery cells 3 can be directly assembled into battery 5, or they can be first assembled into battery modules, and then multiple battery modules can be assembled into battery 5.

[0155] [Electrical appliances]

[0156] This application provides an electrical device, including the battery described in the above embodiments.

[0157] The technical solutions described in the embodiments of this application are applicable to various battery-powered devices.

[0158] Electrical devices can include vehicles, mobile phones, portable devices, laptops, ships, spacecraft, electric toys, and power tools, etc. Vehicles can be gasoline-powered cars, natural gas-powered cars, or new energy vehicles; new energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc. Spacecraft include airplanes, rockets, space shuttles, and spacecraft, etc. Electric toys include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Power tools include metal cutting power tools, grinding power tools, assembly power tools, and railway power tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, etc. This application does not impose any special limitations on the above-mentioned electrical devices.

[0159] For ease of explanation, the following embodiments will use a vehicle as an example of an electrical device.

[0160] For example, as shown in Figure 5, which is a structural schematic diagram of a vehicle 7 according to one embodiment of this application, the vehicle 7 can be a gasoline-powered vehicle, a natural gas-powered vehicle, or a new energy vehicle. The new energy vehicle can be a pure electric vehicle, a hybrid electric vehicle, or a range-extended electric vehicle, etc. A motor 4, a controller 6, and a battery 5 can be installed inside the vehicle 7. The controller 6 is used to control the battery 5 to supply power to the motor 4. For example, the battery 5 can be installed at the bottom, front, or rear of the vehicle 7. The battery 5 can be used to power the vehicle 7; for example, the battery 5 can serve as the operating power source for the vehicle 7's electrical system, such as meeting the power requirements for starting, navigation, and operation of the vehicle 7. In another embodiment of this application, the battery 5 can not only serve as the operating power source for the vehicle 7 but also as the driving power source for the vehicle 7, replacing or partially replacing gasoline or natural gas to provide driving power to the vehicle 7.

[0161] 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.

[0162] [Examples and Comparative Examples]

[0163] 1. Preparation of positive electrode sheet

[0164] Positive electrode plate 1:

[0165] (1) Mix the base coating natural rubber (NR), conductive agent conductive carbon black and solvent toluene in a mass ratio of 3.5:1.5:95 and stir evenly to form a base coating slurry. Apply the base coating slurry to both sides of the aluminum foil using a 10μm wire rod and bake at 100℃ for 1 hour to form a composite current collector.

[0166] (2) The positive electrode active material nickel cobalt manganese ternary material (NCM811), the sulfide electrolyte LiSPCl with a volume average particle size of 600 nm, the conductive carbon black and the binder (polystyrene-(ethylene-butene copolymer)-polystyrene) triblock copolymer (SEBS) are mixed in a mass ratio of 80:17:1.5:1.5 and added to the solvent toluene. The mixture is stirred evenly to form a slurry of active material film layer. The above active material film layer slurry is coated on both sides of the above composite current collector. After cold pressing and cutting, the positive electrode sheet 1 is obtained.

[0167] Positive electrode 2: The preparation of positive electrode 2 is similar to that of positive electrode 1, except that the mass ratio of the base coating NR, conductive agent conductive carbon black and solvent in positive electrode 2 is 2.5:2.5:95.

[0168] Positive electrode 3-11: The preparation of positive electrode 3-11 is similar to that of positive electrode 2, except that the base coating adhesive in positive electrode 3-11 is ethylene propylene diene monomer (EPDM), polyisobutylene (PIB), styrene-butadiene rubber (SBR), (styrene-butadiene-styrene) triblock copolymer (SBS), hydrogenated styrene-butadiene rubber (HSBR), SEBS, hydrogenated (styrene-isoprene-styrene) triblock copolymer (SEPS), cyclic olefin copolymer (COC), and ethylene-α-olefin copolymer (POE).

[0169] Positive electrode 12: The preparation of positive electrode 12 is similar to that of positive electrode 2, except that the base coating of positive electrode 12 is polyacrylic acid (PAA).

[0170] Positive electrode 13: The positive active material NCM811, the sulfide electrolyte LiSPCl with a volume average particle size of 600 nm, the conductive carbon black and the binder polyacrylate are mixed in a mass ratio of 80:17:1.5:1.5 and then added to the solvent toluene. The mixture is stirred evenly to form a slurry of active material film layer. The above active material film layer slurry is coated on both sides of the aluminum foil. After cold pressing and cutting, the positive electrode 13 is obtained.

[0171] Positive electrode 14: The preparation of positive electrode 14 is similar to that of positive electrode 13, except that the binder in positive electrode 14 is SEBS.

[0172] Positive electrode 15: The preparation of positive electrode 15 is similar to that of positive electrode 14. The difference is that in positive electrode 15, the mass ratio of positive active material NCM811, sulfide electrolyte LiSPCl with a volume average particle size of 600 nm, conductive carbon black and binder SEBS is 76.5:17:1.5:5.

[0173] [Example 1]

[0174] (1) Positive electrode plate

[0175] The positive electrode sheet is the positive electrode sheet 1 prepared as described above.

[0176] (2) Preparation of solid electrolyte layer

[0177] A sulfide solid electrolyte LiSPCl with a volume average particle size of 10 μm and a binder polyisobutylene are mixed at a mass ratio of 98:2 and then added to a solvent toluene. The mixture is stirred evenly to form a solid electrolyte slurry. The solid electrolyte content in the solid electrolyte slurry is 50%. The solid electrolyte slurry is uniformly coated on the positive electrode 1 and dried to obtain a solid electrolyte layer.

[0178] (3) Preparation of negative electrode sheet

[0179] Silicon-carbon composite material, conductive carbon black, binder carboxymethyl cellulose (CMC), and solvent water are mixed in a mass ratio of 95:2:3:100 and stirred evenly. The slurry is then coated on both sides of a copper foil. After drying, cold pressing, and cutting, the negative electrode sheet is obtained.

[0180] (4) Preparation of battery cell: The above positive electrode 1, solid electrolyte layer and negative electrode are stacked in sequence to obtain electrode assembly; the electrode assembly is placed in outer packaging to obtain stacked battery cell.

[0181] The battery cells of Examples 2-11 and Comparative Examples 1-4 are prepared using methods similar to those of the battery cell of Example 1, except that different positive electrode plates are used (positive electrode plate 1-11 is used in Examples 1-11, and positive electrode plate 12-15 is used in Comparative Examples 1-4), as detailed in Table 1. Performance parameters of Examples 1-11 and Comparative Examples 1-4 are shown in Table 1.

[0182] Table 1. Product parameters and performance parameters of Examples 1-11 and Comparative Examples 1-4

[0183] In Table 1, S represents the solubility parameter of the primer in a low-polarity solvent. In the embodiments and comparative examples of this application, the low-polarity solvent used is toluene, and the polarity parameter P' of toluene is 2.4; A represents the mass ratio of the primer to the conductive agent and conductive carbon black in the primer layer; P represents the mass percentage of the binder based on the total mass of the active material film layer; adhesion refers to the adhesion between the primer layer and the active material film layer; whether or not it can be demolded refers to whether the active material film layer has detached (or partially detached) from the current collector.

[0184] A comparison of the results from Examples 1-11 and Comparative Example 1 shows that the solubility parameter S of the primer in a low-polarity solvent is set to satisfy: 15 (J / cm³). 3 ) 1 / 2 ≤S≤19(J / cm 3 ) 1 / 2 The active material film layer has a large adhesion to the current collector, which can improve the adhesion stability between the active material film layer and the current collector, and the active material film layer did not fall off.

[0185] A comparison of the results from Examples 1-11 and Comparative Example 2 shows that when a high-polarity binder is used in the active material film layer, the adhesion between the active material film layer and the current collector is strong, and the adhesion between the active material film layer and the current collector is good. However, the cycle performance of the solid-state battery deteriorates accordingly, and the capacity drops drastically. The technical solution of this application, by setting a base coating layer and setting the solubility parameter S of the base coating adhesive in a low-polarity solvent to satisfy: 15 (J / cm³) 3 ) 1 / 2 ≤S≤19(J / cm 3 ) 1 / 2 This allows for improved cycle life and capacity retention of the battery while ensuring good adhesion between the active material film and the current collector and reducing the risk of active material film detachment.

[0186] A comparison of the results from Examples 1-11 and Comparative Example 3 shows that the solubility parameter S of the base coating and the base adhesive in the low-polarity solvent satisfies: 15 (J / cm³). 3 ) 1 / 2 ≤S≤19(J / cm 3 ) 1 / 2 The active material film layer has a large adhesion to the current collector, which can improve the adhesion stability between the active material film layer and the current collector, and the active material film layer did not fall off.

[0187] A comparison of the results from Examples 1-11 and Comparative Example 4 shows that while increasing the content of low-polarity binder in the active material film layer can increase the adhesion between the active material film layer and the current collector, it leads to a deterioration in the battery's cycle performance and a significant decrease in battery capacity. The technical solution of this application, by setting a base coating layer and setting the solubility parameter S of the base coating adhesive in a low-polarity solvent to satisfy: 15 (J / cm³) 3 ) 1 / 2 ≤S≤19(J / cm 3 ) 1 / 2 This allows for improved cycle life and capacity retention of the battery while ensuring good adhesion between the active material film and the current collector and reducing the risk of active material film detachment.

[0188] The following is a brief description of the testing methods for the physicochemical and performance parameters involved in the embodiments of this application. It should be understood that the following testing methods are only examples, and other testing methods known in the art can also be used for testing.

[0189] 1. Adhesion test

[0190] Using a universal testing machine, perform the test according to the following steps:

[0191] a. Prepare a long strip of steel plate to be used as the substrate for the tape.

[0192] b. Adhere one side of the double-sided coated tape to the surface of the steel plate, and use a roller with a diameter of 4.5cm to fully press the tape to ensure good adhesion.

[0193] c. After cutting the positive electrode sheet to the same width as the tape, stick it to the other adhesive side of the double-sided coated tape, and use a roller with a diameter of 4.5cm to press the tape firmly again.

[0194] d. Install the 180° peel fixture on the peel testing machine. Place the sample fixed to the steel plate on the lower fixture, ensuring that the sample is aligned with the fixture.

[0195] e. Use the upper clamp to fix the other end of the positive electrode plate, so that the adhesive side of the tape is pulled up at a 180° angle to the stretching side.

[0196] f. Set the speed of the peel tester to 300 mm / min.

[0197] g. Start the testing machine and begin peeling the tape at the set speed. During the peeling process, the testing machine will record data on the peeling force and peeling distance.

[0198] 2. Whether demolding is required during die cutting

[0199] You can visually inspect whether the membrane layer of the material has detached (or partially detached) from the composite current collector.

[0200] 3. Discharge capacity test

[0201] (1) First-cycle discharge capacity

[0202] The battery cell was charged to 4.25V at a current of 0.1C, then charged to 0.05C at a constant voltage of 4.25V, left to stand for 10 minutes, and then discharged to 2.5V at a current of 0.1C, left to stand for 10 minutes to obtain the first discharge capacity.

[0203] (2) Capacity after 100 cycles

[0204] After repeating the above process 100 times, the discharge capacity after 100 cycles is obtained.

[0205] 4. Testing of solubility parameter S

[0206] The solubility parameters of the polymer were tested using thin-layer chromatography (TLC). This involved dissolving the polymer in a series of (mixed) solvents with known solubility parameters, spotting and scaling the solvent on the TLC plate, and using these solvents as the developing solvent. The displacements at the same time points were recorded. An x-y graph was plotted between the "(mixed) solvent solubility parameters" and the "displacement," and the graph was fitted. The x-value corresponding to the highest point (maximum y-value) of the fitted curve was taken as the solubility parameter of the polymer. In this application, the polymer is a primer.

[0207] 5. Confirmation of the primer coating

[0208] The primer material in the primer layer can be purified by extraction to separate the primer from other materials in the primer layer, and then the primer can be characterized by nuclear magnetic resonance spectroscopy to determine the specific type of primer.

[0209] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A battery cell, characterized in that, include: Solid electrolyte layer and electrode; The electrode includes a composite current collector and an active material film layer, wherein the active material film layer is disposed on at least one surface of the composite current collector, and the active material film layer includes a sulfide electrolyte. The composite current collector includes a current collector body and a base coating. The base coating is disposed on at least one surface of the current collector body. The base coating includes a base adhesive, and the solubility parameter S of the base adhesive in a low-polarity solvent satisfies: 15 (J / cm³). 3 ) 1 / 2 ≤S≤19(J / cm 3 ) 1 / 2 Wherein, the polarity parameter P' of the low-polarity solvent satisfies: 0 <P’≤2.5。 2. The battery cell according to claim 1, characterized in that, The primer includes at least one of low-polarity rubber material, low-polarity plastic material, functionalized styrene-diolefin copolymer, and derivatives of functionalized styrene-diolefin copolymer.

3. The battery cell according to claim 2, characterized in that, The low-polarity rubber material includes at least one of natural rubber, EPDM rubber, polyisobutylene, styrene-butadiene rubber, and hydrogenated styrene-butadiene rubber.

4. The battery cell according to claim 2 or 3, characterized in that, The low-polarity plastic material includes at least one of cyclic olefin copolymers and ethylene-α-olefin copolymers.

5. The battery cell according to any one of claims 2 to 4, characterized in that, The functionalized styrene-diolefin copolymers include at least one of the following: (styrene-butadiene-styrene) triblock copolymers, (polystyrene-(ethylene-butene copolymer)-polystyrene) triblock copolymers, hydrogenated (styrene-isoprene-styrene) triblock copolymers, fluorobutadiene-styrene copolymers, methoxy-functionalized butadiene-styrene copolymers, fluoropentylene-styrene copolymers, methoxy-functionalized pentylene-styrene copolymers, hydrogenated fluorobutadiene-styrene copolymers, hydrogenated methoxy-functionalized butadiene-styrene copolymers, hydrogenated fluoropentylene-styrene copolymers, and hydrogenated methoxy-functionalized pentylene-styrene copolymers.

6. The battery cell according to any one of claims 1 to 5, characterized in that, The base coating also includes a conductive agent, which includes at least one of conductive carbon black, carbon nanotubes, and carbon fibers.

7. The battery cell according to claim 6, characterized in that, In the base coating layer, the mass ratio of the base adhesive to the conductive agent ranges from 1:9 to 8:

2.

8. The battery cell according to any one of claims 1 to 7, characterized in that, The thickness L of the base coating layer satisfies: 0.1μm≤L≤10μm.

9. The battery cell according to any one of claims 1 to 8, characterized in that, The active material film layer also includes the primer.

10. The battery cell according to any one of claims 1 to 9, characterized in that, The active material membrane layer further includes an adhesive, which includes at least one of the following: ethylene propylene rubber, ethylene-α-olefin copolymer, ethylene-cycloolefin copolymer, polybutadiene, polyisoprene, polyisobutylene, styrene-butadiene rubber, (styrene-butadiene-styrene) triblock copolymer, (styrene-isoprene-styrene) triblock copolymer, hydrogenated styrene-butadiene rubber, hydrogenated (styrene-butadiene-styrene) triblock copolymer, and hydrogenated (styrene-isoprene-styrene) triblock copolymer.

11. The battery cell according to any one of claims 1 to 10, characterized in that, The electrode is a positive electrode.

12. A method for preparing a single battery cell, characterized in that, The preparation method includes: A solid electrolyte and electrodes are provided to prepare the battery cell; The electrode sheet provided includes: The primer and the first solvent are mixed to obtain the slurry of the primer layer; The slurry of the base coating is applied to the surface of at least one side of the current collector body to provide a composite current collector; A sulfide electrolyte and a second solvent are mixed to obtain a slurry for the active material film layer. The polarity parameter P' of the second solvent satisfies: 0 <P’≤2.5; A slurry of the active material film layer is applied to the surface of at least one side of the composite current collector to provide the electrode. Wherein, the solubility parameter S of the primer in the second solvent satisfies: 15 (J / cm³) 3 ) 1 / 2 ≤S≤19(J / cm 3 ) 1 / 2 .

13. The preparation method according to claim 12, characterized in that, The first solvent includes at least one of alkane solvents and benzene solvents; The alkane solvents include at least one of pentane, hexane, heptane, octane, nonane, decane, undecane, dodecane, tridecane, tetradecane, pentadecane, cycloalkanes, and bicycloalkanes; The benzene-based solvent includes at least one of toluene, xylene, trimethylbenzene, and tetrahydronaphthalene.

14. The preparation method according to claim 12 or 13, characterized in that, The second solvent includes at least one of alkane solvents and benzene solvents; The alkane solvents include at least one of pentane, hexane, heptane, octane, nonane, decane, undecane, dodecane, tridecane, tetradecane, pentadecane, cycloalkanes, and bicycloalkanes; The benzene-based solvent includes at least one of toluene, xylene, trimethylbenzene, and tetrahydronaphthalene.

15. The preparation method according to any one of claims 12 to 14, characterized in that, The primer includes at least one of low-polarity rubber material, low-polarity plastic material, functionalized styrene-diolefin copolymer, and derivatives of functionalized styrene-diolefin copolymer.

16. The preparation method according to claim 15, characterized in that, The low-polarity rubber material includes at least one of natural rubber, EPDM rubber, polyisobutylene, styrene-butadiene rubber, and hydrogenated styrene-butadiene rubber.

17. The preparation method according to claim 15 or 16, characterized in that, The low-polarity plastic material includes at least one of cyclic olefin copolymers and ethylene-α-olefin copolymers.

18. The preparation method according to any one of claims 15 to 17, characterized in that, The functionalized styrene-diolefin copolymers include at least one of the following: (styrene-butadiene-styrene) triblock copolymers, (polystyrene-(ethylene-butene copolymer)-polystyrene) triblock copolymers, hydrogenated (styrene-isoprene-styrene) triblock copolymers, fluorobutadiene-styrene copolymers, methoxy-functionalized butadiene-styrene copolymers, fluoropentylene-styrene copolymers, methoxy-functionalized pentylene-styrene copolymers, hydrogenated fluorobutadiene-styrene copolymers, hydrogenated methoxy-functionalized butadiene-styrene copolymers, hydrogenated fluoropentylene-styrene copolymers, and hydrogenated methoxy-functionalized pentylene-styrene copolymers.

19. The preparation method according to any one of claims 12 to 18, characterized in that, The solid content W of the slurry for the base coating layer satisfies: 1% ≤ W ≤ 50%.

20. An electrical appliance, characterized in that, include: The battery cell according to any one of claims 1 to 11, and / or the battery cell obtained by the preparation method according to any one of claims 12 to 19.

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