An electrode plate, a method for manufacturing the same, a battery, a battery pack, and an electric device

Abstract

This invention provides an electrode sheet and its preparation method, a battery, a battery pack, and an electrical device. The electrode sheet includes a current collector, a first sub-active material layer, and a second sub-active material layer; the first sub-active material layer is located on at least one side of the current collector; the second sub-active material layer is located on the side of the first sub-active material layer opposite to the current collector; the first sub-active material layer includes a non-fluorinated binder, and the second active material layer includes a fluorinated binder; the non-fluorinated binder includes a rubber-based binder. The electrode sheet of this invention has high electronic conductivity and ionic conductivity, which can improve the rate performance and cycle performance of the battery.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and in particular to an electrode sheet and its preparation method, a battery, a battery pack, and an electrical device. Background Technology

[0002] Solid-state batteries, with their high safety and high energy density, are regarded as the core direction of the next generation of energy storage technology and are widely used in electric vehicles, large-scale energy storage systems and aerospace and other fields with extremely high requirements for energy density and safety performance.

[0003] However, compared to traditional liquid batteries, solid-state batteries use solid electrolyte materials, which results in lower electronic and ionic conductivity, severely limiting their rate performance and cycle life, and restricting their applications.

[0004] Therefore, there is an urgent need for a method to improve the rate performance and cycle performance of solid-state batteries in order to expand their applications. Summary of the Invention

[0005] This invention provides an electrode sheet and its preparation method, a battery, a battery pack, and an electrical device. The electrode sheet has high electronic conductivity and ionic conductivity, which can improve the rate performance and cycle performance of the battery.

[0006] This invention provides an electrode sheet comprising a current collector, a first sub-active material layer, and a second sub-active material layer;

[0007] The first sub-active material layer is located on at least one side of the current collector;

[0008] The second sub-active material layer is located on the side of the first sub-active material layer away from the current collector;

[0009] The first sub-active material layer includes a non-fluorinated binder, and the second sub-active material layer includes a fluorinated binder;

[0010] The non-fluorinated adhesives include rubber-based adhesives.

[0011] In some embodiments of the present invention, the non-fluorinated adhesive comprises 0.1 to 5 parts by mass in the first sub-active material layer;

[0012] And / or, the fluorinated binder is present in the second sub-active material layer in a mass fraction of 0.5 to 10 parts.

[0013] In some embodiments of the present invention, the fluorinated adhesive includes one or more of polyvinylidene fluoride, polytetrafluoroethylene, polyvinylidene fluoride-hexafluoropropylene, polychlorotrifluoroethylene, ethylene-chlorotrifluoroethylene copolymer, ethylene-tetrafluoroethylene copolymer, polyvinyl fluoride, and fluorinated ethylene propylene copolymer.

[0014] And / or, the non-fluorinated adhesive includes one or more of styrene-butadiene rubber, nitrile rubber, and hydrogenated nitrile rubber.

[0015] In some embodiments of the present invention, the first sub-active material layer includes a first solid electrolyte material and a first active material;

[0016] The second sub-active material layer includes a second solid electrolyte material and a second active material;

[0017] The electrode plate satisfies A1≥A2 and / or B1≤B2;

[0018] Wherein, A1 is the mass fraction of the first active material in the first sub-active material layer, in parts;

[0019] A2 represents the mass fraction of the second active material in the second sub-active material layer, expressed in parts.

[0020] B1 represents the mass fraction of the first solid electrolyte material in the first sub-active material layer, expressed in parts.

[0021] B2 represents the mass fraction of the second solid electrolyte material in the second sub-active material layer, expressed in parts.

[0022] In some embodiments of the present invention, 80 parts ≤ A1 ≤ 95 parts;

[0023] And / or, 75 parts ≤ A2 ≤ 95 parts;

[0024] And / or, 5 parts ≤ B1 ≤ 20 parts;

[0025] And / or, 5 parts ≤ B2 ≤ 25 parts.

[0026] In some embodiments of the present invention, the first solid electrolyte material and the second solid electrolyte material are each independently selected from one or more of oxide solid electrolytes, sulfide solid electrolytes, and polymer solid electrolytes. Preferably, the sulfide solid electrolyte includes Li3PS4 and Li7P3S. 11 Li 11 GeP2S 12 Li6PS5Cl, Li7P2S8I, Li 10 SnP2S 12 Li 3 .25 Ge 0 .25 P0 .75 One or more of S4;

[0027] And / or, the first active material and the second active material are each independently selected from one or more of lithium iron phosphate, lithium cobalt oxide, lithium manganese oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, and lithium nickel cobalt aluminum oxide.

[0028] In some embodiments of the present invention, the thickness of the first sub-active material layer is less than or equal to the thickness of the second sub-active material layer.

[0029] In some embodiments of the present invention, the electrode includes a positive electrode.

[0030] In some embodiments of the present invention, the electrode includes a negative electrode.

[0031] This invention also provides a method for preparing the electrode as described above, comprising the following steps:

[0032] A first slurry comprising a non-fluorinated binder is coated onto at least one side of the current collector, and a first drying treatment is performed to obtain a first sub-active material layer.

[0033] The electrode sheet is obtained by coating a second slurry, including a fluorine-based binder, onto the side of the first sub-active material layer away from the current collector and then performing a second drying process.

[0034] The non-fluorinated adhesives include rubber-based adhesives.

[0035] This invention also provides a battery comprising the electrode sheet as described above, or the electrode sheet prepared by the method described above.

[0036] This invention also provides a battery pack comprising at least two batteries as described above.

[0037] This invention also provides an electrical device, including the battery as described above or the battery pack as described above.

[0038] The present invention provides an electrode sheet and its preparation method, a battery, a battery pack, and an electrical device. By dividing the active material layer into two sub-active material layers, and using a rubber-based binder in the sub-active material layer near the current collector and a fluorine-based binder in the sub-active material layer away from the current collector, the electronic conductivity and ionic conductivity of the electrode sheet can be improved, thereby improving the rate performance and cycle performance of the battery. Attached Figure Description

[0039] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0040] Figure 1 This is a schematic diagram of the structure of a positive electrode sheet provided in an embodiment of the present invention.

[0041] Explanation of reference numerals in the attached figures

[0042] 1: Positive current collector; 21: First sub-positive active material layer; 22: Second sub-positive active material layer.

[0043] The accompanying drawings have illustrated specific embodiments of the invention, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the invention in any way, but rather to illustrate the concept of the invention to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0045] Currently, solid-state battery electrodes suffer from low electronic and ionic conductivity. The inventors, through research on traditional electrodes, discovered that increasing the electrode loading to improve energy density in solid-state batteries leads to prolonged electron and active metal ion transport paths within the electrode, thus limiting the performance of the active materials. Furthermore, unlike liquid electrolytes, solid electrolytes in solid-state batteries struggle to establish continuous electron and active metal ion transport paths, resulting in limited improvement in rate performance and cycle life.

[0046] Therefore, the inventors started by addressing the problem of low electronic and ionic conductivity in the electrodes of solid-state batteries, and attempted to improve the rate performance and cycle performance of solid-state batteries.

[0047] Based on this, embodiments of the present invention provide an electrode sheet, including a current collector, a first sub-active material layer, and a second sub-active material layer; the first sub-active material layer is located on at least one side of the current collector; the second sub-active material layer is located on the side of the first sub-active material layer opposite to the current collector; the first sub-active material layer includes a non-fluorinated binder, and the second active material layer includes a fluorinated binder; the non-fluorinated binder includes a rubber-based binder.

[0048] When the electrode sheet of the present invention has the above-described structure and composition, it has both high electronic conductivity and ionic conductivity, which can improve the rate performance and cycle performance of the battery.

[0049] The inventors analyzed that the reason why the electrode of the present invention can improve the rate performance and cycle performance of the battery is that the improvement of the rate performance and cycle performance is closely related to the electronic conductivity and ionic conductivity of the electrode. In the electrode of the present invention, the first sub-active material layer is in direct contact with the current collector. The present invention uses a rubber-based non-fluorinated adhesive with high bonding strength and good flexibility, which can more firmly anchor the active material in the first sub-active material layer and form a dense and stable conductive network. This results in a high peel force of the active material layer, which can significantly reduce the contact resistance between the active material and the current collector, thereby improving the electron transfer efficiency from the current collector to the active material. The second sub-active material layer is located on the outer layer. By using a fluorinated adhesive, the CF bond in the fluorinated adhesive has less hindrance to Li⁺ transport, thereby better promoting the migration rate of active metal ions in the active material layer. Therefore, the electrode of the present invention achieves synergistic optimization of electron and ion transport paths, reduces charge transfer impedance, and enables the electrode to maintain efficient electrochemical reaction kinetics under high-rate charge and discharge, thereby significantly improving the rate performance and cycle performance of the battery.

[0050] The embodiments of the present invention can test the non-fluorinated binder in the first sub-active material layer and the fluorinated binder in the second sub-active material layer using conventional testing methods and instruments. For example, testing can be performed using methods such as ICP and TGA.

[0051] Specifically, when using ICP testing, the following method can be adopted: First, scrape a certain mass of powder from the surface of the positive electrode sheet and perform ICP testing. Based on the characteristic elements of each component and the ICP test results, obtain the type of binder in the first sub-active material layer. Then, perform ICP testing on the entire positive electrode sheet. Similarly, based on the characteristic elements of each component and the ICP test results, and subtract the content of each component in the first sub-active material layer obtained earlier, obtain the type of binder in the first sub-active material layer.

[0052] When using TGA for testing, the following method can be used: Based on the thermal decomposition temperature and range of each component, the binder type of the first sub-active material layer and the second sub-active material layer can be obtained. Specifically, the entire positive electrode sheet is subjected to TGA testing, and the binder type of the first sub-active material layer and the second sub-active material layer can be obtained by comparing the temperature corresponding to the inflection point of the change in the mass of the positive electrode sheet with the known thermal decomposition temperature of the binder.

[0053] It should be clarified that the mass fractions in the embodiments of the present invention can be based on grams or kilograms, but are not limited to this. Taking the mass fractions in grams as an example, one part can be 1g.

[0054] In some embodiments of the present invention, the non-fluorinated binder comprises 0.1 to 5 parts by mass in the first sub-active material layer, which is beneficial for further improving the electronic conductivity of the electrode and the peel strength of the active material layer, thereby better improving the rate performance and cycle performance of the battery. For example, the non-fluorinated binder comprises, for example, 0.1, 0.5, 1, 2, 3, 4, 5 parts by mass in the first sub-active material layer, or any combination thereof.

[0055] In some embodiments, the fluorinated binder is present in the second sub-active material layer at a mass fraction of 0.5 to 10 parts, which is beneficial for further improving the ionic conductivity of the electrode, thereby better improving the rate performance and cycle performance of the battery. The mass fraction of the fluorinated binder in the second sub-active material layer is, for example, 0.5 parts, 1 part, 3 parts, 6 parts, 8 parts, 10 parts, or any combination thereof.

[0056] In some embodiments of the present invention, the fluorinated binder includes one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP), polychlorotrifluoroethylene, ethylene-chlorotrifluoroethylene copolymer, ethylene-tetrafluoroethylene copolymer, polyvinyl fluoride, and fluorinated ethylene propylene copolymer, which is beneficial to further improve the ionic conductivity of the electrode, thereby better improving the rate performance and cycle performance of the battery.

[0057] In some embodiments, the non-fluorinated binder includes one or more of styrene-butadiene rubber (SBR), nitrile rubber (NBR), and hydrogenated nitrile rubber (HNBR), which is beneficial for further improving the electronic conductivity of the electrode and can further improve the peel force of the active material layer, thereby better improving the rate performance and cycle performance of the battery.

[0058] In some embodiments of the present invention, the first sub-active material layer includes a first solid electrolyte material and a first active material; the second sub-active material layer includes a second solid electrolyte material and a second active material; the electrode satisfies A1≥A2 and / or B1≤B2; wherein, A1 is the mass fraction of the first active material in the first sub-active material layer; A2 is the mass fraction of the second active material in the second sub-active material layer; B1 is the mass fraction of the first solid electrolyte material in the first sub-active material layer; and B2 is the mass fraction of the second solid electrolyte material in the second sub-active material layer.

[0059] When the electrode in this embodiment of the invention meets the above conditions, the electronic conductivity and ionic conductivity are further improved, thereby enhancing the rate performance and cycle performance of the battery. Specifically, in the first sub-active material layer near the current collector, using a higher proportion of active material (A1 > A2) and a lower proportion of solid electrolyte material (B1 < B2) than the first sub-active material layer, or using the same proportion of active material and solid electrolyte material as the second sub-active material layer (A1 = A2, B1 = B2), facilitates the construction of a higher density electronic conductivity pathway, enhances the electrical contact between the active material and the current collector, and better reduces the internal resistance of electron transport. In the outer second sub-active material layer, by increasing the content of solid electrolyte material, the active metal ion conduction capacity of this region is better enhanced, providing a more continuous and efficient transport channel for ions, further improving the ionic conductivity of the electrode, and thus better improving the rate performance and cycle performance of the battery.

[0060] The embodiments of the present invention further improve the electronic conductivity of the electrode by controlling the values ​​of A1, A2, B1, and B2, thereby better improving the rate performance and cycle performance of the battery.

[0061] In some embodiments, 80 parts ≤ A1 ≤ 95 parts, for example, the value of A1 is a range of 80 parts, 85 parts, 90 parts, 95 parts, or any two of them.

[0062] In some embodiments, 75 parts ≤ A2 ≤ 95 parts, for example, the value of A2 is a range of 75 parts, 80 parts, 85 parts, 90 parts, 95 parts, or any two of them.

[0063] In some embodiments, 5 parts ≤ B1 ≤ 20 parts, for example, the value of B1 is a range of 5 parts, 10 parts, 15 parts, 20 parts, or any two of them.

[0064] In some embodiments, 5 parts ≤ B2 ≤ 25 parts, for example, the value of B2 is a range of 5 parts, 10 parts, 15 parts, 20 parts, 25 parts, or any two of them.

[0065] The values ​​of A1, A2, B1, and B2 can be tested using conventional testing methods and instruments in the art. For example, the ICP method can be used, specifically including the following steps: After the battery is fully discharged, it is disassembled, and the electrode is separated to obtain a sample of the first sub-active material layer on the upper layer of the battery electrode; the first sub-active material layer sample is subjected to acid wet digestion, volume determination, and then the content of each characteristic element is tested using inductively coupled plasma optical emission spectroscopy (ICP-OES) to determine the content of the first sub-active material in the first sub-active material layer sample. Samples including the first and second sub-active material layers are obtained, and the entire electrode material is subjected to acid wet digestion, volume determination, and the content of each characteristic element is tested using inductively coupled plasma optical emission spectroscopy (ICP-OES) to determine the content of the positive electrode active material in the entire electrode. Then, the content of the first sub-active material in the first sub-active material layer sample is subtracted to obtain the content of the second sub-active material in the second sub-active material layer sample. The mass fraction testing of the first and second solid electrolyte materials is performed similarly.

[0066] This invention further enhances both the electronic and ionic conductivity of the electrode by controlling the specific selection of the first and second solid electrolyte materials. In one specific embodiment, the first and second solid electrolyte materials are each independently selected from one or more of oxide solid electrolytes, sulfide solid electrolytes, and polymer solid electrolytes. Preferably, the battery is a lithium-ion battery, and the sulfide solid electrolyte includes Li3PS4 and Li7P3S. 11 Li 11 GeP2S 12 Li6PS5Cl, Li7P2S8I, Li 10 SnP2S 12 Li 3 .25 Ge 0 .25 P 0 .75 One or more of S4.

[0067] In some embodiments, when the electrode is a positive electrode, that is, the first active material is the first positive electrode active material and the second active material is the second positive electrode active material, the first active material and the second active material are each independently selected from one or more of lithium iron phosphate, lithium cobalt oxide, lithium manganese oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, and lithium nickel cobalt aluminum oxide, which can further improve the electronic conductivity and ionic conductivity of the electrode, thereby better improving the rate performance and cycle performance of the battery.

[0068] To further improve both the electronic and ionic conductivity of the electrode, this invention also controls the thickness of the first sub-active material layer and the second sub-positive electrode active material layer. When the thickness of the first sub-active material layer is less than or equal to the thickness of the second sub-active material layer, the battery rate can be further improved. In some embodiments, the thickness of the first sub-active material layer is greater than or equal to 30 μm; the thickness of the second sub-active material layer is greater than or equal to 30 μm.

[0069] The thicknesses of the first and second sub-active material layers can be tested using conventional testing methods and instruments in the art, such as SEM. Specifically, the following method can be used: After fully discharging the battery, disassemble it, separate the electrode sheets, obtain a cross-section of the electrode sheets, and use SEM to test the thicknesses of the first and second sub-active material layers in the cross-section. When the thicknesses are not uniform, the average thickness of the cross-section in different fields of view is taken.

[0070] In some embodiments of the present invention, the electrode includes a positive electrode.

[0071] In some embodiments of the present invention, the electrode includes a negative electrode.

[0072] That is, in embodiments of the present invention, only the positive electrode or the electrode may have the above-described structure and composition, or both the positive and negative electrodes may have the above-described composition. It should be noted that the negative electrode generally does not contain solid electrolyte material.

[0073] In some embodiments, the positive electrode sheet is a common positive electrode sheet (i.e., it does not distinguish between the molecular active material layer and the type of binder). The positive electrode sheet includes a positive current collector and a positive active layer located on at least one side of the positive current collector. Specifically, the positive active layer can be provided on one side in the thickness direction of the positive current collector, or positive active layers can be provided on both opposite sides in the thickness direction of the positive current collector.

[0074] The positive electrode active layer includes a positive electrode active material, a conductive agent and a binder, and a solid electrolyte material. In the positive electrode active layer, the mass fraction of the conductive agent can be 0.5% to 15%, for example, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 8%, 10%, 13%, 15%, or any combination thereof. The mass fraction of the binder can be 0.5% to 15%, for example, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 8%, 10%, 13%, 15%, or any combination thereof.

[0075] In some embodiments, the battery is a sodium-ion battery, and the positive electrode active material includes, but is not limited to, one or a combination of transition metal oxides, polyanionic compounds, organic compounds, and Prussian blue materials. The transition metal oxides may be, but are not limited to, NaMO2 (M may be Fe, Co, Ni, Mn, etc.); the polyanionic compounds may be, but are not limited to, Na3V2(PO4)3, NaFePO4, Na2FePO4F, etc.; the Prussian blue materials may be, but are not limited to, Na2Fe(CN)6, etc.; and the organic compounds may be, but are not limited to, sodium terephthalic acid salts, etc.

[0076] In some embodiments, the battery is a lithium-ion battery, and the positive electrode active material may include LiCoO2, LiNiO2, or LiCo. x Ni 1-x O2 (0≤x≤1), LiCo x Ni 1-x-y Al y O2 (0≤x≤1, 0≤y≤1), LiMn2O4, LiFe x Mn y M z O4 (M is one or more of Al, Mg, Ga, Cr, Co, Ni, Cu, Zn or Mo, 0≤x≤1, 0≤y≤1, 0≤z≤1, x+y+z=1), Li 1＋ x L 1－y－z M y N z O2 (L, M, N are one or more of Li, Co, Mn, Ni, Fe, Al, Mg, Ga, Ti, Cr, Cu, Zn, Mo, F, I, S, B, -0.1≤x≤0.2, 0≤y≤1, 0≤z≤1, 0≤y+z≤1), LiFePO4, Li3V2(PO4)3, Li3V3(PO4)3, LiVPO4F, Li2CuO2, Li5FeO4, and metal sulfides and oxides (such as TiS2, V2S3, FeS, FeS2, LiMS) x (M is at least one of the transition metal elements such as Ti, Fe, Ni, Cu, Mo, etc., 1≤x≤2.5), TiO2, Cr3O8, V2O5, MnO2, etc.

[0077] In some embodiments, the battery is a potassium-ion battery, and the positive electrode active material includes, but is not limited to, one or more of the following: Prussian blue analogues, layered transition metal oxides, polyanionic compounds (such as KFeSO4F, KVPO4F), organic compounds (such as potassium terephthalate), sulfides (such as K2FeS2), phosphates (such as K3V2(PO4)3), potassium manganese oxides (such as KMnO4 derivatives), potassium cobalt oxides (such as KCoO2), and potassium nickel oxides (such as KNiO2).

[0078] In this embodiment of the invention, the conductive agent in the positive electrode active layer can be a conventional conductive material in the art. For example, the conductive agent in the positive electrode active layer may include one or more of conductive carbon black, conductive graphite, carbon nanotubes (CNTs), carbon fibers, graphene, acetylene black, and Ketjen black.

[0079] The embodiments of the present invention may employ conventional positive current collectors in the art, for example, positive current collectors may include aluminum foil.

[0080] In some embodiments, the positive electrode has the structure described above, such as... Figure 1 As shown, the electrode is a positive electrode, which includes a positive current collector 1, a first sub-positive active material layer 21, and a second sub-positive active material layer 22. The first sub-positive active material layer 21 includes a positive active material (first positive active material), a solid electrolyte, a conductive agent, and a non-fluorinated binder. The second sub-positive active material layer 22 includes a positive active material (second positive active material), a solid electrolyte, a conductive agent, and a fluorinated binder. When the first and second active materials are positive active materials, their specific selection is as described above.

[0081] In some embodiments, the negative electrode sheet is a common negative electrode sheet (i.e., regardless of the molecular active material layer and the type of binder). The negative electrode sheet includes a negative current collector and a negative active material layer located on at least one side surface of the negative current collector. Specifically, the negative active material layer may be provided on one side surface of the negative current collector, or negative active material layers may be provided on both opposite sides of the negative current collector in the thickness direction.

[0082] Specifically, the negative electrode active material layer may include a negative electrode active material, a conductive agent, and a fluorine-based binder, all of which can be conventional materials in the art. For example, the negative electrode active material may include one or more of graphite, silicon, and silicon-carbon, and the conductive agent may include one or more of conductive carbon black, carbon nanotubes (CNTs), acetylene black, graphene, Ketjen black, and carbon fiber.

[0083] In some embodiments, the negative electrode sheet has the above-described structure (i.e., the negative electrode sheet includes a negative current collector, a first sub-negative active material layer, and a second sub-negative active material layer; the first sub-negative active material layer is located on at least one side of the negative current collector; the second sub-negative active material layer is located on the side of the first sub-negative active material layer away from the negative current collector; the first sub-negative active material layer includes a non-fluorinated binder, and the second sub-negative active material layer includes a fluorinated binder; the non-fluorinated binder includes a rubber-based binder). When the first active material and the second active material are negative electrode active materials, their specific selection is as described above.

[0084] The embodiments of the present invention may employ conventional negative electrode current collectors in the art, for example, negative electrode current collectors include copper foil.

[0085] This invention also provides a method for preparing the above-mentioned electrode, comprising the following steps: coating a first slurry including a non-fluorinated binder onto at least one side of a current collector, performing a first drying treatment to obtain a first sub-active material layer; coating a second slurry including a fluorinated binder onto the side of the first sub-active material layer away from the current collector, performing a second drying treatment to obtain the electrode; the non-fluorinated binder includes a rubber-based binder.

[0086] The present invention, through the above-described electrode preparation method, can produce an electrode with both high electronic conductivity and ionic conductivity, thereby improving the rate performance and cycle performance of the battery. Specifically, the electrode prepared by the above-described electrode preparation method includes a current collector, a first sub-active material layer, and a second sub-active material layer; the first sub-active material layer is located on at least one side of the current collector; the second sub-active material layer is located on the side of the first sub-active material layer opposite to the current collector; the first sub-active material layer includes a non-fluorinated binder, and the second sub-active material layer includes a fluorinated binder; the non-fluorinated binder includes a rubber-based binder.

[0087] The embodiments of the present invention do not impose special limitations on the processing time and temperature of the first drying process and the processing time and temperature of the second drying process, and can be selected according to the actual situation.

[0088] In some embodiments of the present invention, the second drying process further includes rolling the electrode sheet after the second drying process. The embodiments of the present invention do not impose special limitations on the pressure of the rolling process, and can select it according to the actual situation.

[0089] In this embodiment of the invention, the thickness of the first sub-active material layer and the thickness of the second sub-active material layer can be controlled by the thickness of the slurry on the current collector during coating and the pressure of the rolling process.

[0090] In this embodiment of the invention, the positive electrode sheet is a common positive electrode sheet, which can be prepared by conventional methods in the art, such as by coating. Specifically, the components used to form the positive electrode active layer, such as the positive electrode active material, conductive agent, and non-fluorinated binder, can be dispersed in a solvent, such as xylene, to prepare a positive electrode slurry. This slurry is then coated onto the surface of the positive electrode current collector, and after drying, rolling, and other processes, the positive electrode sheet is obtained. The coating, drying, and rolling processes involved are conventional operations for preparing positive electrode sheets using the coating method, and are not particularly limited thereto.

[0091] In practice, a slurry containing positive electrode active material can be prepared under a dew point of ≤-45℃; conventional coating equipment in the field, such as continuous coating equipment, can be used to coat the slurry containing positive electrode active material onto the surface of the positive electrode current collector.

[0092] In some embodiments, the positive electrode sheet has the aforementioned structure and composition, namely, the positive electrode sheet includes a positive current collector, a first sub-positive active material layer, and a second sub-positive active material layer; the first sub-positive active material layer is located on at least one side of the positive current collector; the second sub-positive active material layer is located on the side of the first sub-positive active material layer opposite to the positive current collector; the first sub-positive active material layer includes a non-fluorinated binder, and the second sub-positive active material layer includes a fluorinated binder; the non-fluorinated binder includes a rubber-based binder.

[0093] At this time, the above-mentioned positive electrode sheet can be prepared by the following method: coating a first positive electrode slurry including a non-fluorinated binder onto at least one side of the positive electrode current collector, and performing a first drying treatment to obtain a first sub-positive electrode active material layer; coating a second positive electrode slurry including a fluorinated binder onto the side of the first sub-positive electrode active material layer away from the current collector, and performing a second drying treatment to obtain the positive electrode sheet; the non-fluorinated binder includes a rubber-based binder.

[0094] Specifically, the first positive electrode slurry also includes a first solid electrolyte material, a first positive electrode active material, a conductive agent, and a binder, the specific selection of which is as described above and will not be repeated here.

[0095] In this embodiment of the invention, the negative electrode sheet is a common negative electrode sheet, which can be prepared by conventional methods in the art, such as by coating. Specifically, the components used to form the negative electrode active material layer, such as the negative electrode active material, solid electrolyte material, conductive agent, and binder, can be dispersed in a solvent, such as xylene, to prepare a negative electrode slurry. This slurry is then coated onto the negative electrode current collector, and after drying, rolling, and other processes, the negative electrode sheet is obtained. The coating, drying, and rolling processes involved are conventional operations for preparing negative electrode sheets using the coating method, and are not particularly limited thereto.

[0096] In practice, a slurry containing negative electrode active material can be prepared under a dew point of ≤-45℃; conventional coating equipment in the field, such as continuous coating equipment, can be used to coat the slurry containing negative electrode active material onto the surface of the negative electrode current collector.

[0097] In some embodiments, the negative electrode sheet has the aforementioned structure and composition, namely, the negative electrode sheet includes a negative electrode current collector, a first sub-negative electrode active material layer, and a second sub-negative electrode active material layer; the first sub-negative electrode active material layer is located on at least one side of the negative electrode current collector; the second sub-negative electrode active material layer is located on the side of the first sub-negative electrode active material layer opposite to the negative electrode current collector; the first sub-negative electrode active material layer includes a non-fluorinated binder, and the second sub-negative electrode active material layer includes a fluorinated binder; the non-fluorinated binder includes a rubber-based binder.

[0098] At this time, the above-mentioned negative electrode sheet can be prepared by the following method: coating a first negative electrode slurry including a non-fluorinated binder onto at least one side of the negative electrode current collector, and performing a first drying treatment to obtain a first sub-negative electrode active material layer; coating a second negative electrode slurry including a fluorinated binder onto the side of the first sub-negative electrode active material layer away from the current collector, and performing a second drying treatment to obtain the negative electrode sheet; the non-fluorinated binder includes a rubber-based binder.

[0099] Specifically, the first negative electrode slurry also includes a first negative electrode active material, a conductive agent, and a binder, the specific selection of which is as described above and will not be repeated here.

[0100] In this embodiment of the invention, the temperature and time of the first drying treatment and the second drying treatment are not specifically limited, and can be selected according to specific circumstances.

[0101] In this embodiment of the invention, the battery cell can be packaged using conventional housing materials in the art, such as flexible packaging materials like aluminum-plastic film, but is not limited thereto.

[0102] This invention also provides a battery comprising the aforementioned adhesive film or the aforementioned components. The battery of this invention has advantages corresponding to the aforementioned electrode sheets, which will not be elaborated upon here.

[0103] The battery in this embodiment of the invention can be a lithium-ion battery (such as a lithium-ion power battery), a potassium-ion battery, a sodium-ion battery, or other novel energy storage batteries, preferably a lithium-ion battery.

[0104] In detail, in all-solid-state battery systems, the CF bonds in fluorine-based binders offer less resistance to Li⁺ transport, thereby better promoting the migration rate of active metal ions within the active material layer. Therefore, electrodes with the aforementioned structure can better improve their ionic conductivity.

[0105] Generally, a battery includes an electrolyte, a cell, and a casing for encapsulating the cell. The cell includes a positive electrode, a negative electrode, and an electrolyte (which can be a solid electrolyte membrane) located between the positive and negative electrodes. The cell can be a stacked cell, meaning it is composed of alternating layers of positive, electrolyte, and negative electrodes; or it can be a wound cell, meaning it is composed of stacked positive, electrolyte, and negative electrodes wound together. Specifically, the battery in this embodiment of the invention is a solid-state battery.

[0106] The solid-state battery in this embodiment of the invention also includes a solid electrolyte membrane disposed between the positive electrode and the negative electrode.

[0107] The embodiments of the present invention do not impose special limitations on the preparation of solid electrolyte membranes, and the selection can be made according to the actual situation. The solid electrolyte membrane includes solid electrolyte materials, and the selection of solid electrolyte materials is as described above and will not be repeated here.

[0108] In some embodiments of the present invention, the electrode can be a composite electrode, that is, a composite electrode obtained by combining a solid electrolyte membrane with a positive electrode or a negative electrode.

[0109] In some embodiments, the composite electrode can be prepared by coating a solid electrolyte slurry, including a solid electrolyte material, onto one side surface of the electrode and drying it to obtain the composite electrode. Alternatively, the solid electrolyte slurry can be continuously coated onto a release film and then dried to obtain a solid electrolyte film, which can then be laminated with the electrode to obtain the composite electrode.

[0110] Generally, the aforementioned solid-state battery includes a cell and a casing for encapsulating the cell. A solid electrolyte membrane is located between the positive and negative electrodes of the solid-state battery and is assembled within the cell inside the casing. The negative electrode includes a negative electrode sheet, and the positive electrode includes a positive electrode sheet. The cell can be a stacked cell, meaning it is composed of alternating layers of a positive electrode sheet, a solid electrolyte membrane, and a negative electrode sheet; or it can be a wound cell, meaning it is composed of stacked positive electrode sheets, a solid electrolyte membrane, and a negative electrode sheet, which are then wound together.

[0111] This invention also provides a battery pack comprising at least two of the aforementioned batteries, which has advantages corresponding to the aforementioned electrode plates, and will not be described in detail hereafter.

[0112] Generally, a battery pack includes multiple batteries as individual cells, which are connected to form the battery pack. These batteries can be electrically connected using methods conventional in the art, such as series connection, parallel connection, or a combination of these connection methods, without any particular limitation.

[0113] This invention also provides an electrical device including the battery described above. This electrical device has advantages corresponding to the electrode plates described above, which will not be elaborated further.

[0114] The electrical equipment used in the embodiments of the present invention can be conventional electrical equipment in the art, such as power equipment (e.g., electric vehicles, electric cars), electronic equipment (e.g., mobile phones, tablets, laptops, digital cameras, etc.), wearable devices (e.g., watches, bracelets, VR glasses, etc.), energy storage power stations, etc., and there are no particular limitations on this.

[0115] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0116] Example 1

[0117] The positive electrode sheet in this embodiment is prepared by the following method:

[0118] A first slurry, comprising a non-fluorinated binder (specifically 95 parts NCM811 (ternary cathode active material, i.e., the first active material), 5 parts LPSCl (solid electrolyte material), 1 part NBR (non-fluorinated binder), 1 part SBR (non-fluorinated binder), and 5 parts SuperP (conductive agent), with xylene as the solvent), is coated onto one side of the current collector. After a first drying treatment, a first sub-active material layer is obtained. A second slurry, comprising a fluorinated binder (specifically 87 parts NCM811 (ternary cathode active material, i.e., the second active material), 13 parts LPSCl, 5 parts PVDF-HFP (fluorinated binder), and 5 parts SuperP, with butyl butyrate as the solvent), is coated onto the side of the first sub-active material layer opposite to the current collector (the positive electrode current collector is coated with carbon aluminum foil). After a second drying treatment and a roll forming treatment, a positive electrode sheet is obtained. The first drying treatment is performed at a temperature of 100°C for 1 hour; the second drying treatment is performed at a temperature of 100°C for 1 hour.

[0119] The thickness of the first sub-active material layer, the thickness of the second sub-active material layer, and other parameters are shown in Table 1.

[0120] Example 2

[0121] This embodiment is basically the same as Embodiment 1, except that the first slurry in this embodiment includes 94 parts NCM811, 6 parts LPSCl, 1 part NBR, 1 part SBR, and 5 parts SuperP, and the second slurry includes 88 parts NCM811, 12 parts LPSCl, 5 parts PVDF-HFP, and 5 parts SuperP. This embodiment also controls the thickness of the second slurry during coating to control the thickness of the second sub-active material layer.

[0122] Example 3

[0123] This embodiment is basically the same as Embodiment 1, except that the second slurry in this embodiment includes 83 parts NCM811, 17 parts LPSCl, 5 parts PVDF-HFP, and 5 parts SuperP. This embodiment also controls the thickness of the second slurry during coating to control the thickness of the second sub-active material layer.

[0124] Example 4

[0125] This embodiment is basically the same as Embodiment 1, except that the first slurry in this embodiment includes 95 parts NCM811, 5 parts LPSCl, 2 parts NBR, 2 parts SBR and 5 parts SuperP, and the second slurry includes 85 parts NCM811, 5 parts LPSCl, 7 parts PVDF-HFP and 5 parts SuperP.

[0126] Example 5

[0127] This embodiment is basically the same as Embodiment 1, except that the first slurry in this embodiment includes 95 parts Ni88 (ternary cathode active material), 5 parts LPSCl, 1 part NBR, 1 part SBR and 5 parts SuperP; the second slurry includes 87 parts NCM811, 13 parts LPSCl, 5 parts PTFE and 5 parts SuperP.

[0128] Example 6

[0129] This embodiment is basically the same as Embodiment 1, except that the first slurry in this embodiment includes 95 parts NCM811, 5 parts LPSCl, 5 parts SBR and 5 parts SuperP; the second slurry includes 87 parts NCM811, 13 parts LPSCl, 10 parts PVDF-HFP and 5 parts SuperP.

[0130] Example 7

[0131] This embodiment is basically the same as Embodiment 1, except that the first slurry in this embodiment includes 95 parts NCM811, 5 parts LPSCl, 0.05 parts NBR, 0.05 parts SBR and 5 parts SuperP; the second slurry includes 87 parts NCM811, 13 parts LPSCl, 0.5 parts PVDF-HFP and 5 parts SuperP.

[0132] Example 8

[0133] This embodiment is basically the same as Embodiment 1, except that the first slurry in this embodiment includes 90 parts NCM811, 5 parts LPSCl, 1 part NBR, 1 part SBR and 5 parts SuperP; the second slurry includes 95 parts NCM811, 5 parts LPSCl, 5 parts PVDF-HFP and 5 parts SuperP.

[0134] Example 9

[0135] This embodiment is basically the same as Embodiment 1, except that the first slurry in this embodiment includes 95 parts NCM811, 5 parts LPSCl, 1 part NBR, 1 part SBR, and 5 parts SuperP; the second slurry includes 80 parts NCM811, 20 parts LPSCl, 5 parts PVDF-HFP, and 5 parts SuperP. This embodiment also controls the thickness of the first and second slurries during coating to control the thickness of the first and second sub-active material layers.

[0136] Example 10

[0137] This embodiment is basically the same as Embodiment 1, except that the first slurry in this embodiment includes 95 parts NCM811, 5 parts LPSCl, 3 parts NBR, 2.5 parts SBR and 5 parts SuperP; the second slurry includes 87 parts NCM811, 13 parts LPSCl, 5 parts PVDF-HFP and 5 parts SuperP.

[0138] Example 11

[0139] This embodiment is basically the same as Embodiment 1, except that the first slurry in this embodiment includes 95 parts NCM811, 5 parts LPSCl, 0.05 parts NBR, 0.04 parts SBR and 5 parts SuperP; the second slurry includes 87 parts NCM811, 13 parts LPSCl, 5 parts PVDF-HFP and 5 parts SuperP.

[0140] Example 12

[0141] This embodiment is basically the same as Embodiment 1, except that the first slurry in this embodiment includes 95 parts NCM811, 5 parts LPSCl, 1 part NBR, 1 part SBR and 5 parts SuperP; the second slurry includes 87 parts NCM811, 13 parts LPSCl, 11 parts PVDF-HFP and 5 parts SuperP.

[0142] Example 13

[0143] This embodiment is basically the same as Embodiment 1, except that the first slurry in this embodiment includes 95 parts NCM811, 5 parts LPSCl, 1 part NBR, 1 part SBR and 5 parts SuperP; the second slurry includes 87 parts NCM811, 13 parts LPSCl, 0.4 parts PVDF-HFP and 5 parts SuperP.

[0144] Example 14

[0145] The negative electrode sheet in this embodiment is prepared by the following method:

[0146] A first slurry, comprising a non-fluorinated binder (specifically 95 parts SiC (silicon-carbon) (negative electrode active material, i.e., the first active material), 5 parts LPSCl (solid electrolyte material), 2 parts NBR (non-fluorinated binder), 2 parts SBR (non-fluorinated binder), and 5 parts SuperP (conductive agent), with xylene as the solvent), is coated onto both sides of a current collector (a negative electrode current collector copper foil). After a first drying treatment, a first sub-active material layer is obtained. A second slurry, comprising a fluorinated binder (specifically 85 parts SiC (silicon-carbon) (negative electrode active material, i.e., the second active material), 15 parts LPSCl, 4 parts PVDF-HFP (fluorinated binder), and 5 parts SuperP, with butyl butyrate as the solvent), is coated onto the side of the first sub-active material layer away from the current collector. After a second drying treatment and a roll forming treatment, a negative electrode sheet is obtained. The first drying treatment is performed at a temperature of 100°C for 1 hour; the second drying treatment is performed at a temperature of 100°C for 1 hour.

[0147] Comparative Example 1

[0148] This comparative example is basically the same as Example 1, except that the first slurry in this comparative example includes 90 parts NCM811, 10 parts LPSCl, 2 parts NBR, 2 parts SBR and 5 parts SuperP, and the second slurry includes 95 parts NCM811, 5 parts LPSCl, 4 parts NBR, 3 parts SBR and 5 parts SuperP.

[0149] Comparative Example 2

[0150] This comparative example is basically the same as Example 1, except that the positive electrode slurry in this comparative example includes 90 parts Ni88, 10 parts LPSCl (solid electrolyte material), 2 parts NBR, 2 parts SBR, and 5 parts SuperP. The above positive electrode slurry is coated on both sides of the positive electrode current collector to obtain a positive electrode sheet. The positive electrode sheet prepared in this embodiment of the invention does not have a layered structure.

[0151] Comparative Example 3

[0152] This comparative example is basically the same as Example 1, except that the first slurry in this example includes 90 parts NCM811, 10 parts LPSCl, 4 parts PVDF-HFP and 5 parts SuperP, and the second slurry includes 90 parts NCM811, 90 parts LPSCl, 7 parts PVDF-HFP and 5 parts SuperP.

[0153] Comparative Example 4

[0154] This comparative example is basically the same as Example 16, except that the first slurry in this comparative example includes 95 parts SiC (silicon-carbon), 2 parts NBR, 2 parts SBR and 5 parts SuperP, and the second slurry includes 85 parts SiC (silicon-carbon), 2 parts NBR, 2 parts SBR and 5 parts SuperP.

[0155] The mass fractions of the binder in the first sub-active material layer (hereinafter referred to as the binder of the first sub-active material layer in the table), the mass fractions of the binder in the second sub-active material layer (hereinafter referred to as the binder of the second sub-active material layer in the table), A1, A2, B1, B2, the thickness of the first sub-active material layer, and the thickness of the second sub-active material layer of the electrode sheets in the above embodiments and comparative examples are shown in Table 1.

[0156]

[0157] Test case

[0158] Preparation of solid electrolyte membrane: Add 95 parts LPSCl and 5 parts NBR binder to a xylene solution and stir until a stable and homogeneous solution is obtained. Continuously coat this solution onto a release membrane and then dry it to obtain the solid electrolyte membrane.

[0159] Battery performance testing: A solid electrolyte layer was first pre-pressed using a PEEK mold at 150 MPa. Then, indium foil, lithium copper foil, and the positive electrode sheets from Examples 1-13 and Comparative Examples 1-3 were assembled sequentially at the top and bottom of the solid electrolyte layer (the indium foil and lithium copper foil were on the same side of the solid electrolyte layer, and the positive electrode sheet was on the other side). The solid electrolyte layer was then cold-pressed using a pressing machine at 300 MPa. After tightening the bolts, the solid-state mold battery was obtained (this step was performed in an inert atmosphere). A charge / discharge rate test of 0.1 C-2 C was then conducted at 25 °C. The test results (2 C / 0.1 C capacity retention) are shown in Table 2.

[0160] Conductivity testing: A solid electrolyte layer was first pre-pressed using a PEEK mold at 150 MPa. Then, indium foil, lithium copper foil, and the positive electrode sheets from Examples 1-13 and Comparative Examples 1-3 were assembled sequentially at the top and bottom of the solid electrolyte layer (indium foil and lithium copper foil were on the same side of the solid electrolyte layer, and the positive electrode sheet was on the other side; during negative electrode assembly, the counter electrode was also indium foil and lithium copper foil). The assembly was then cold-pressed using a tablet press at 300 MPa. After tightening the bolts, a solid-state mold battery was obtained (this step was performed in an inert atmosphere). The negative electrode sheets from Examples 14 and Comparative Example 4 were then assembled with indium foil and lithium copper foil (the negative electrode sheet was on one side of the solid electrolyte layer, and the indium foil and lithium copper foil were on the other side) in the same manner to form a solid-state mold battery. EIS testing was performed at 25 °C, and the ionic and electronic conductivity of the electrodes were calculated after impedance analysis. Specifically, the distance between the x-coordinates of the inflection points of the diffusion portion slope abruptly and the high-frequency slope abruptly inflection points in the Nyquist impedance spectrum is used as 1 / 3R. ele +1 / 3R ion And by fitting the mid-frequency component with a straight line and using its intersection with the horizontal axis as R... ele ×R ion / (R ion +R ele The electronic and ionic impedance values ​​of the electrode are calculated based on these two values. Specifically, the corresponding ionic conductivity and electronic conductivity are calculated using σ=L / RA; where L is the thickness (cm) and A is the area (cm²) of the end face (i.e., the contact area between the electrode and the solid electrolyte layer). 2 R is the electronic or ionic impedance value (Ω). ele R is the electronic impedance value. ion The values ​​represent ionic impedance. The test results (ionic conductivity and electronic conductivity) are shown in Table 2.

[0161] Cyclic capacity retention test: (Positive electrode) At 25℃, charge at a constant current of 0.33C to 3.70V, then discharge at a discharge rate of 0.33C to 2.0V, repeating this charge-discharge cycle 100 times. Measure the discharge capacity Q1 at the first cycle and the discharge capacity Q at the 100th cycle. 100 .

[0162] (Negative electrode) At 25℃, it is discharged at a constant current rate of 0.33C to -0.059V, and then charged at a charging rate of 0.33C to 1.0V. This charge-discharge cycle is repeated 100 times. The charging capacity Q1 at the first cycle and the charging capacity Q at the 100th cycle are measured. 100 .

[0163] The capacity retention rate Q after 100 cycles is calculated using the following formula.

[0164] Capacity retention rate Q = Q 100 / Q1×100%. The test results (capacity retention rate over 100 laps) are shown in Table 2.

[0165]

[0166] As shown in the table, compared with the comparative example, the embodiments of the present invention, by adopting a layered design for the electrode, using a non-fluorinated binder in the first sub-active material layer close to the current collector and a fluorinated binder in the second sub-active material layer far from the current collector, can improve the ionic conductivity and electronic conductivity of the electrode, thereby improving the rate performance and cycle performance of the battery.

[0167] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An electrode sheet, characterized in that, It includes a current collector, a first sub-active material layer, and a second sub-active material layer; The first sub-active material layer is located on at least one side of the current collector; The second sub-active material layer is located on the side of the first sub-active material layer away from the current collector; The first sub-active material layer includes a non-fluorinated binder, and the second sub-active material layer includes a fluorinated binder; The non-fluorinated adhesives include rubber-based adhesives.

2. The electrode sheet according to claim 1, characterized in that, The non-fluorinated adhesive comprises 0.1 to 5 parts by mass in the first sub-active material layer; And / or, the fluorinated binder is present in the second sub-active material layer in a mass fraction of 0.5 to 10 parts.

3. The electrode sheet according to claim 1 or 2, characterized in that, The fluorinated adhesive includes one or more of the following: polyvinylidene fluoride, polytetrafluoroethylene, polyvinylidene fluoride-hexafluoropropylene, polychlorotrifluoroethylene, ethylene-chlorotrifluoroethylene copolymer, ethylene-tetrafluoroethylene copolymer, polyvinyl fluoride, and fluorinated ethylene propylene copolymer. And / or, the non-fluorinated adhesive includes one or more of styrene-butadiene rubber, nitrile rubber, and hydrogenated nitrile rubber.

4. The electrode sheet according to any one of claims 1-3, characterized in that, The first sub-active material layer includes a first solid electrolyte material and a first active material; The second sub-active material layer includes a second solid electrolyte material and a second active material; The electrode plate satisfies A1≥A2 and / or B1≤B2; Wherein, A1 is the mass fraction of the first active material in the first sub-active material layer, in parts; A2 represents the mass fraction of the second active material in the second sub-active material layer, expressed in parts. B1 represents the mass fraction of the first solid electrolyte material in the first sub-active material layer, expressed in parts. B2 represents the mass fraction of the second solid electrolyte material in the second sub-active material layer, expressed in parts.

5. The electrode sheet according to any one of claims 1-4, characterized in that, 80 copies ≤ A1 ≤ 95 copies; And / or, 75 parts ≤ A2 ≤ 95 parts; And / or, 5 parts ≤ B1 ≤ 20 parts; And / or, 5 parts ≤ B2 ≤ 25 parts.

6. The electrode sheet according to claim 4, characterized in that, The first solid electrolyte material and the second solid electrolyte material are each independently selected from one or more of oxide solid electrolytes, sulfide solid electrolytes, and polymer solid electrolytes. Preferably, the sulfide solid electrolyte includes Li3PS4 and Li7P3S. 11 Li 11 GeP2S 12 Li6PS5Cl, Li7P2S8I, Li 10 SnP2S 12 Li 3 .25 Ge 0 .25 P 0 .75 One or more of S4; And / or, the first active material and the second active material are each independently selected from one or more of lithium iron phosphate, lithium cobalt oxide, lithium manganese oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, and lithium nickel cobalt aluminum oxide.

7. The electrode sheet according to any one of claims 1-6, characterized in that, The thickness of the first sub-active material layer is less than or equal to the thickness of the second sub-active material layer.

8. The electrode sheet according to any one of claims 1-7, characterized in that, The electrode includes a positive electrode.

9. The electrode sheet according to any one of claims 1-3 and 7, characterized in that, The electrode includes a negative electrode.

10. A method for preparing an electrode according to any one of claims 1-9, characterized in that, Includes the following steps: A first slurry comprising a non-fluorinated binder is coated onto at least one side of the current collector, and a first drying treatment is performed to obtain a first sub-active material layer. The electrode sheet is obtained by coating a second slurry, including a fluorine-based binder, onto the side of the first sub-active material layer away from the current collector and then performing a second drying process. The non-fluorinated adhesives include rubber-based adhesives.

11. A battery, characterized in that, This includes the electrode sheet as described in any one of claims 1-9, or the electrode sheet prepared by the method described in claim 10.

12. A battery pack, characterized in that, It includes at least two batteries as described in claim 11.

13. An electrical appliance, characterized in that, Includes the battery of claim 11 or the battery pack of claim 12.

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