Battery cell and method for producing the same, battery, electric device

Abstract

This application provides a battery cell, its preparation method, a battery, and an electrical device. The battery cell includes: a positive electrode sheet, which includes a positive current collector and a positive active material layer; and a negative electrode sheet, which includes a negative current collector. The surface of the negative current collector has a first region and a second region adjacent to each other along a first direction, wherein the size of the second region in the first direction is larger than the size of the positive active material layer. The surface of the first region of the negative electrode sheet is provided with a first coating, which includes metal nanoparticles. The technical solution of this application is beneficial for detecting the overhang region of the battery cell, thereby improving the reliability of the battery.

Description

Technical Field

[0001] This application relates to the field of batteries, and more specifically, to a battery cell and its preparation method, a battery, and an electrical device. Background Technology

[0002] With increasing environmental pollution, the new energy industry is attracting more and more attention. Within the new energy industry, battery technology is a crucial factor in its development.

[0003] Battery technology has been developing rapidly in recent years. Due to the unique structure of batteries, computed tomography (CT) is often used to detect internal defects in individual cells non-destructively. Overhang (the portion of the negative electrode extending beyond the positive electrode active material) is a crucial aspect of battery defect detection, and its detection is essential for the reliability of individual cells. Therefore, improving CT imaging contrast to detect overhang in individual cells and thus enhance battery reliability is a pressing technical problem that needs to be solved. Summary of the Invention

[0004] This application is made in view of the above-mentioned problems, and its purpose is to provide a battery cell to enhance CT imaging contrast, detect the overhang region of the battery cell, and improve the reliability of the battery.

[0005] To achieve the above objectives, this application provides a battery cell and its preparation method, a battery, and an electrical device.

[0006] In a first aspect, a battery cell is provided, comprising: a positive electrode sheet, the positive electrode sheet including a positive current collector and a positive active material layer; and a negative electrode sheet, the negative electrode sheet including a negative current collector, the surface of the negative current collector having a first region and a second region disposed adjacent to each other along a first direction, the size of the second region being larger than the size of the positive active material layer in the first direction; wherein, the surface of the first region of the negative electrode sheet is provided with a first coating, the first coating comprising metal nanoparticles.

[0007] In this embodiment, the surface of the negative electrode current collector has a first region and a second region disposed adjacent to each other along a first direction. The size of the second region in the first direction is larger than the size of the positive electrode active material layer, allowing the first region to at least partially replace the overhang region. A first coating comprising metal nanoparticles is disposed on the surface of the first region, which is beneficial for enhancing CT imaging contrast and CT imaging signals. Therefore, the technical solution of this application is advantageous for detecting overhang regions and improving battery reliability.

[0008] In one possible implementation, in a first direction, the first region is distributed on both sides of the second region. This allows the first coating to be applied to both first regions, making it easier to detect overhangs and improving the reliability of individual battery cells.

[0009] In one possible implementation, the metal nanoparticles include at least one of the following: silver nanoparticles, tungsten nanoparticles, iron oxide nanoparticles, cobalt nanoparticles, and nickel nanoparticles. Optionally, the metal nanoparticles include at least one of iron oxide nanoparticles, cobalt nanoparticles, and nickel nanoparticles.

[0010] In the above technical solutions, metal nanoparticles have high atomic numbers and strong X-ray absorption capabilities, which can significantly hinder X-ray propagation and enhance CT imaging contrast. Among them, iron oxide nanoparticles, cobalt nanoparticles, and nickel nanoparticles have high elemental abundance, which can reduce production costs.

[0011] In one possible implementation, the particle size of a single metal nanoparticle is 1 nm to 200 nm. Alternatively, the particle size of a single metal nanoparticle is 3 nm to 50 nm.

[0012] In the above technical solution, metal nanoparticles of different sizes have different absorption and scattering abilities for X-rays. When the metal nanoparticles are within the above range, they can provide better CT enhancement effects.

[0013] In one possible implementation, the size of the metal nanoparticle aggregates is 20 nm to 5000 nm. Alternatively, the size of the metal nanoparticle aggregates is 20 nm to 2000 nm.

[0014] In the above technical solution, metal nanoparticles existing in the form of aggregates, within the above size range, can improve the contrast of CT imaging.

[0015] In one possible implementation, the first coating further includes a binder and a dispersant; based on the total mass of the first coating, the mass content A of the metal nanoparticles is 30 wt% to 97.5 wt%, the mass content B of the binder is 2 wt% to 50 wt%, and the mass content C of the dispersant is 0.5 wt% to 20 wt%.

[0016] In the above technical solution, the mass content A of the metal nanoparticles is 30wt% to 97.5wt%, which is beneficial to enhance the contrast of the Overhang region in CT imaging; the mass content B of the binder is 2wt% to 50wt%, so that the first coating has a suitable adhesion force with the current collector, which can reduce the risk of the first coating falling off from the current collector; the mass content C of the dispersant is 0.5wt% to 20wt%, which helps to improve the dispersibility of the material, reduce agglomeration, and make the coating uniformly distributed in the first region.

[0017] In one possible implementation, the thickness d of the first coating is between 0.05 μm and 60 μm. When the thickness d of the first coating is not less than 0.05 μm, the first coating has a suitable thickness, which is beneficial for improving the detection of Overhang in the first region, enhancing the contrast of CT, and improving the reliability of the battery cell. When the thickness d of the first coating does not exceed 60 μm, it is beneficial for reducing the space occupied by the first coating, thereby facilitating the assembly of the battery cell.

[0018] In one possible implementation, an insulating layer is disposed on the surface of the first coating. The insulating layer includes one of the following: an organic polymer insulating material, an inorganic insulating material, and a composite material.

[0019] In the above technical solution, an insulating layer is provided on the surface of the first coating, which can reduce the catalytic oxidation of the electrolyte by metal nanoparticles.

[0020] In one possible implementation, a second coating is provided on the surface of the second region of the negative electrode sheet. The second coating includes at least one of a functional coating and a negative electrode active material layer. In the above technical solution, when a functional coating is provided on the surface of the second region of the negative electrode sheet, the first region can be identified during CT imaging of the battery cell in a negative electrode-free system, improving the reliability of the battery. When a negative electrode active material layer is provided in the second region of the negative electrode sheet, and a first coating is provided on the surface of the first region, the positive electrode active material layer and the first region can be effectively identified, facilitating the detection of overhang.

[0021] In one possible implementation, the thickness dl of the second coating satisfies: dl ≤ 50 μm, optionally dl ≤ 20 μm. When the thickness dl of the second coating is ≤ 20 μm, no thicker film layer can support CT detection and imaging. Setting the first coating in the first region can enhance the contrast of CT imaging and detect overhang.

[0022] In one possible implementation, the negative electrode current collector is an aluminum foil current collector. When the negative electrode current collector is an aluminum foil, a coating is applied to the surface of the first region. This can improve the problem of the aluminum foil's weak absorption of X-rays and relatively low image contrast, thereby enhancing the contrast of the CT scan and facilitating the detection of overhang.

[0023] In a second aspect, a method for preparing a battery cell is provided, comprising: providing a positive electrode sheet and a negative electrode sheet to prepare the battery cell; wherein the positive electrode sheet includes a positive current collector and a positive active material layer; the negative electrode sheet includes a negative current collector, the surface of which has a first region and a second region disposed adjacent to each other along a first direction, the size of the second region being larger than the size of the positive active material layer in the first direction; wherein the surface of the first region of the negative electrode sheet is provided with a first coating, the first coating comprising metal nanoparticles.

[0024] The above-mentioned method for preparing negative electrode sheets is relatively simple and has low complexity. Furthermore, when the prepared negative electrode sheets are applied to battery cells, they can enhance CT imaging contrast and CT imaging signals, which is beneficial for detecting overhang regions and improving battery reliability.

[0025] In one possible implementation, providing the negative electrode sheet includes mixing metal nanoparticles, a binder, and a dispersant to obtain a first slurry; and covering a first region with the first slurry to form a first coating. The first coating also contains a binder and a dispersant to provide suitable adhesion between the first coating and the current collector, thereby reducing the risk of the first coating detaching from the current collector and helping to ensure uniform distribution of the coating in the first region.

[0026] In one possible implementation, covering the first region with the first slurry includes applying the first slurry to the first region using physical vapor deposition, chemical vapor deposition, or electroplating. A thin first coating can be prepared using physical vapor deposition, chemical vapor deposition, or electroplating.

[0027] In one possible implementation, covering the first region with the first slurry includes: applying the first slurry to the first region using extrusion coating, gravure coating, or microgravure coating.

[0028] Thirdly, a battery is provided, comprising a battery cell according to the first aspect and any possible implementation thereof, and / or a battery cell obtained by a preparation method according to the second aspect and any possible implementation thereof.

[0029] Fourthly, an electrical device is provided, including the battery of the third aspect. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the structure of an electrode sheet according to an embodiment of this application.

[0031] Figure 2 This is a schematic diagram of the structure of an electrode sheet according to an embodiment of this application.

[0032] Figure 3 This is a schematic diagram of the structure of an electrode sheet with an insulating layer in one embodiment of this application.

[0033] Figure 4 This is a schematic diagram of the structure of an electrode sheet with a negative active material layer in one embodiment of this application.

[0034] Figure 5 This is a schematic diagram of the structure of an electrode with a functional coating in one embodiment of this application.

[0035] Figure 6 This is a schematic diagram of a method for preparing a battery cell according to an embodiment of this application.

[0036] Figure 7 This is a schematic diagram of a battery cell according to an embodiment of this application.

[0037] Figure 8 This is a schematic diagram of a battery according to one embodiment of this application.

[0038] Figure 9 This is a schematic diagram of an electrical device according to one embodiment of this application.

[0039] Explanation of reference numerals in the attached figures:

[0040] 1. Electrode; 110. Positive current collector; 111. Positive active material layer; 120. Negative current collector; 1201. First region; 1202. Second region; 121. First coating; 123. Insulating layer; 124. Negative active material layer; 125. Functional coating; 3. Battery cell; 31. Housing; 32. End cap assembly; 33. Electrode assembly; 34. Connecting member; 322. Electrode terminal; 331. Tab; 4. Battery; 5. Electrical device. Detailed Implementation

[0041] The following detailed description, with appropriate reference to the accompanying drawings, discloses embodiments of the battery cell, its manufacturing method, the battery, and the power-consuming device of this application. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided for the purpose of enabling those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0042] 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.

[0043] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0044] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0045] 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.

[0046] The development of battery technology must consider multiple design factors simultaneously, such as energy density, cycle life, discharge capacity, charge / discharge rate, and reliability. The design of the electrodes within a battery cell is crucial to its reliability. A battery cell includes a positive electrode and a negative electrode. The negative electrode has an area extending beyond the active material layer of the positive electrode; this area is called the overhang region. To ensure control over fluctuations and misalignment during manufacturing, the dimensions of both the positive and negative electrodes need to allow for additional area. This ensures that the active material area of ​​the negative electrode is not narrower than that of the positive electrode in the battery product. Furthermore, during manufacturing, process inspections are necessary to promptly confirm whether the battery's overhang meets preset requirements or is within controlled tolerances. CT imaging technology is typically used for equipment inspection, issuing alarms and screening out cells with abnormalities to ensure that the cells are overhang-compliant samples.

[0047] In some implementations, since sodium-ion battery anodes do not form Li-Al alloys that cause current collector pulverization, aluminum foil can be used as the anode substrate, and the thickness of the anode sheet can be further reduced to improve energy density. However, when aluminum foil is used as the anode substrate, aluminum has weak X-ray absorption, resulting in relatively low image contrast and unclear imaging under CT scans. Furthermore, the lack of a thick film layer on the anode allows for CT detection and imaging, making it difficult to distinguish between the positive and negative electrodes after CT imaging. This makes overhang detection difficult and is detrimental to improving the reliability of individual battery cells.

[0048] In view of this, in one embodiment of this application, a battery cell is provided, comprising: a positive electrode sheet, the positive electrode sheet including a positive current collector and a positive active material layer; and a negative electrode sheet, the negative electrode sheet including a negative current collector, the surface of the negative current collector having a first region and a second region disposed adjacent to each other along a first direction, the size of the second region being larger than the size of the positive active material layer in the first direction; wherein, a first coating is disposed on the surface of the first region of the negative electrode sheet, the first coating comprising metal nanoparticles. Thus, the first coating disposed in the first region of the negative electrode sheet, and the coating containing metal nanoparticles, wherein the metal nanoparticles have a high atomic number and strong absorption capacity for X-rays, can significantly hinder the propagation of X-rays. Furthermore, the metal nanoparticles can generate a strong electromagnetic field, increasing the contrast of imaging; the metal nanoparticles can also enhance CT imaging signals through their surface plasmon resonance effect, thereby facilitating the detection of overhangs and improving the reliability of the battery cell.

[0049] In addition, the following description, with appropriate reference to the accompanying drawings, will illustrate the battery cell, its manufacturing method, the battery, and the power-consuming device of this application.

[0050] [Battery cell]

[0051] In one embodiment of this application, a battery cell is provided.

[0052] Typically, a battery cell includes a positive electrode, a negative electrode, an electrolyte, and a separator. During charging and discharging, active ions move back and forth between the positive and negative electrodes, inserting and releasing. The electrolyte acts as a conductor of ions between the positive and negative electrodes. The separator, positioned between the positive and negative electrodes, primarily prevents short circuits while allowing ions to pass through.

[0053] Figure 1 This is a schematic diagram of the structure of an electrode sheet according to an embodiment of this application. The electrode sheet 1 includes a positive electrode sheet and a negative electrode sheet. A positive electrode active material layer 111 is disposed on the surface of the positive current collector 110 in the positive electrode sheet. The negative electrode sheet has a first region 1201 and a second region 1202 disposed adjacent to each other along a first direction on the surface of the negative current collector 120. The size of the second region 1202 is larger than the size of the positive electrode active material layer 111 in the first direction. The first direction is... Figure 1 The x-direction.

[0054] A first coating 121 is disposed on the surface of the first region 1201 of the negative electrode sheet, and the negative electrode current collector 120 has two opposing surfaces along its thickness direction. The first coating 121 can be disposed on one surface of the negative electrode current collector 120 or on both surfaces of the negative electrode current collector 120. As an example, such as... Figure 1 As shown, the first coating 121 is disposed on one side surface of the negative electrode current collector 120.

[0055] The negative electrode sheet has a first region 1201 and a second region 1202 disposed adjacent to each other along a first direction on the surface of the negative electrode current collector 120. This can include situations where the first region 1201 is disposed at one end of the negative electrode current collector 120; or, as... Figure 2 As shown, the first region 1201 is distributed on both sides of the second region 1202. In this way, the first region is set in the overhang area, which is conducive to better detection of overhang and improves the reliability of the battery cell.

[0056] The first coating 121 includes metal nanoparticles. These metal nanoparticles have a high atomic number and strong X-ray absorption capacity, which can enhance CT imaging contrast, facilitate the detection of overhangs, and improve battery safety.

[0057] In some embodiments, the metal nanoparticles include at least one of silver nanoparticles, tungsten nanoparticles, iron oxide nanoparticles, cobalt nanoparticles, and nickel nanoparticles, wherein the iron oxide nanoparticles include magnetic iron oxide and γ-Fe2O3.

[0058] The aforementioned metal nanoparticles have high atomic numbers and high elemental abundance, thus achieving both enhanced CT imaging contrast and low cost.

[0059] In some embodiments, the particle size of a single metal nanoparticle is 1 nm to 200 nm, for example, the particle size of a single metal nanoparticle is 20 nm, 50 nm, 100 nm or any value within the above range.

[0060] In the above embodiments, the metal nanoparticles in the first coating 121 have a suitable particle size, which helps to optimize the imaging contrast of CT.

[0061] Optionally, the particle size of a single metal nanoparticle can be 3 nm to 50 nm, for example, 5 nm, 13 nm, 25 nm, 45 nm, or any value within the above range. The contrast of CT imaging is related to the size of the metal nanoparticles; by selecting an appropriate particle size, the CT imaging effect can be enhanced.

[0062] In some embodiments, the size of the metal nanoparticle aggregates is 20 nm to 5000 nm, for example 25 nm, 100 nm, 2000 nm or any value within the above range.

[0063] Optionally, the size of the metal nanoparticle aggregates is 20 nm to 2000 nm, for example, 25 nm, 100 nm, 1000 nm, or any value within the above range. Because metal nanoparticles have a high specific surface area and generally exist in aggregate form, within the above range, they are beneficial for better enhancement of CT imaging and improved overhang detection capabilities.

[0064] In some embodiments, the first coating includes a binder and a dispersant; based on the total mass of the first coating, the mass content A of the metal nanoparticles is 30 wt% to 97.5 wt%, the mass content B of the binder is 2 wt% to 50 wt%, and the mass content C of the dispersant is 0.5 wt% to 20 wt%.

[0065] Optionally, the binder includes at least one of polyacrylic acid-polyacrylonitrile copolymer, polyacrylate-polyacrylonitrile copolymer, polyether acrylate, polyacrylic acid, polyacrylonitrile, gelatin, chitosan, and sodium alginate.

[0066] In some embodiments, the dispersant comprises hydrogenated nitrile rubber.

[0067] A can be 40wt%, 60wt%, 80wt% or any value within the above range, B can be 15wt%, 30wt%, 45wt% or any value within the above range, and C can be 5wt%, 10wt%, 15wt% or any value within the above range.

[0068] Based on the total mass of the first coating, the mass content A of the metal nanoparticles is 30wt% to 97.5wt%, which is beneficial for forming a uniform and dense first coating 121 in the first region 1201 of the negative electrode current collector 120.

[0069] Based on the total mass of the first coating, the mass content B of the adhesive is 2wt% to 50wt%, so that the first coating 121 has a suitable adhesive force with the current collector 120, which can reduce the risk of the first coating 121 falling off the current collector 120.

[0070] Based on the total mass of the first coating, the mass content C of the dispersant is 0.5wt% to 20wt%, so that the first coating 121 can be uniformly distributed in the first region 1201, enhancing the contrast of CT imaging.

[0071] In some embodiments, the thickness d of the first coating is 0.05 μm to 60 μm. For example, the thickness d of the first coating is 0.03 μm, 0.6 μm, 10 μm, 30 μm, or any value within the above range.

[0072] When the first coating 121 is disposed on one side surface of the first region 1201 along the thickness direction of the negative electrode current collector 120, the thickness of the first coating 121 is not less than 0.05 μm, so that the first coating 121 can uniformly and densely cover the first region 1201 of the negative electrode current collector 120; when the thickness of the first coating 121 is not greater than 60 μm, it is beneficial to reduce the space occupied by the first coating 121 and to facilitate the processing of the battery.

[0073] Figure 3 This is a schematic diagram of the structure of an electrode with an insulating layer in one embodiment of this application. In some embodiments, an insulating layer 123 is provided on the surface of the first coating 121. In this way, the catalytic oxidation of the electrolyte by the metal nanoparticles is avoided, and the insulating layer 123 is provided on the surface of the first coating 121 for physical isolation and insulation treatment, thereby increasing the selectivity of the metal nanoparticles.

[0074] In some embodiments, the insulating layer comprises one of the following: an organic polymer insulating material, an inorganic insulating material, or a composite material.

[0075] Optionally, the organic polymer insulating material includes at least one of polyamide, polyterephthalate, polyimide, polyethylene, polypropylene, polystyrene, polyvinyl chloride, acrylonitrile-butadiene-styrene copolymer, polybutylene terephthalate, poly(p-phenylene terephthalamide), polypropylene, polyoxymethylene, epoxy resin, phenolic resin, polytetrafluoroethylene, polyvinylidene fluoride, silicone rubber, and polycarbonate. The inorganic insulating material includes at least one of alumina, silicon carbide, and silicon dioxide. The composite material includes at least one of epoxy resin glass fiber reinforced composite material and polyester resin glass fiber reinforced composite material.

[0076] In some embodiments, a second coating is provided on the surface of the second region of the negative electrode sheet, the second coating including at least one of a functional coating and a negative electrode active material layer.

[0077] Figure 4 This is a schematic diagram of the structure of an electrode sheet having a negative electrode active material layer in one embodiment of this application. In some embodiments, a negative electrode active material layer 124 is disposed on the surface of the second region 1202 of the negative electrode sheet.

[0078] Figure 5 This is a schematic diagram of an electrode sheet with a functional coating according to one embodiment of the present application. In some embodiments, a functional coating 125 is provided on the surface of the second region 1202 of the negative electrode sheet.

[0079] Optionally, the negative electrode can be without a negative electrode.

[0080] In the aforementioned negative electrode sheet, a first coating 121 is provided on the surface of the first region 1201, which is beneficial for detecting overhang and improving the reliability of the battery cell.

[0081] In some embodiments, the negative electrode current collector is an aluminum foil current collector. When the negative electrode current collector is an aluminum foil, the first coating 121 is provided on the surface of the first region 1201, which is beneficial to improve the CT imaging contrast when the negative electrode sheet is an aluminum foil and improve the reliability of the battery cell.

[0082] In some embodiments, the thickness dl of the second coating satisfies: dl ≤ 50 μm, optionally, dl ≤ 20 μm. For example, dl is 10 μm, 15 μm, 20 μm, or any value within the above range. When dl ≤ 20 μm, no thicker film layer can support CT detection and imaging. When the first coating 121 is provided on the surface of the first region 1201, it is beneficial to improve the CT imaging contrast when the negative electrode sheet is too thin and improve the reliability of the battery cell.

[0083] [Preparation methods for battery cells]

[0084] Figure 6This is a schematic diagram of a method for preparing a single battery cell according to an embodiment of this application. Method 2 can be used to prepare the electrode 1 in the above embodiment. Method 2 includes the following steps.

[0085] Step 210: Provide positive and negative electrode sheets to prepare a single battery cell;

[0086] The positive electrode includes a positive current collector 110 and a positive active material layer 111;

[0087] The negative electrode sheet includes a negative current collector 120. The surface of the negative current collector 120 has a first region 1201 and a second region 1202 disposed adjacent to each other along a first direction. The size of the second region 1202 in the first direction is larger than the size of the positive active material layer 111.

[0088] The surface of the first region 1201 of the negative electrode sheet is provided with a first coating 121, which includes metal nanoparticles.

[0089] In the above technical solution, a first coating 121 is provided on the first region 1201 of the negative electrode current collector 120, and the first coating 121 includes metal nanoparticles, which is beneficial to enhance CT imaging contrast, detect overhang, and improve the reliability of the battery cell.

[0090] In some embodiments, metal nanoparticles, a binder, and a dispersant are mixed to obtain a first slurry; the first slurry is then applied to a first region 1201 to form the first coating 121.

[0091] In some embodiments, covering the first slurry onto the first region 1201 includes: covering the first slurry onto the first region 1201 using physical vapor deposition, chemical vapor deposition, or electroplating. Physical vapor deposition, performed in a vacuum environment, can form a metal nanoparticle coating on a substrate surface. Ion plating can form a uniform metal nanoparticle coating on a porous metal foil, and the coating has strong adhesion. For example, a cathode ion plating apparatus can be used, with argon or nitrogen as a protective gas, to generate metal ions and nanoparticles using a metal as a target, and ion-plating nano-metals onto the substrate surface.

[0092] In the above method, a relatively thin first coating 121 can be achieved, with a thickness d of 0.05 μm to 1 μm.

[0093] Optionally, covering the first region with the first slurry includes: applying the first slurry to the first region 1201 using extrusion coating, gravure coating, or micro-gravure coating. The slurry is placed in the material trough of an extrusion coating machine, and the coating quality and thickness are controlled by controlling the discharge depth and width of the extrusion coating machine, followed by drying in an oven.

[0094] In the above method, the thickness d of the first coating 121 is 0.5μm to 30μm, which can achieve precise control of coating and adapt to different coating thickness requirements.

[0095] [Positive electrode plate]

[0096] 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.

[0097] As an example, the positive current collector has two surfaces opposite each other in its own thickness direction, and the positive electrode film layer can be disposed on either or both of the two opposite surfaces of the positive current collector.

[0098] Optionally, the positive current collector can be a metal foil or a composite current collector. For example, aluminum foil can be used as the metal foil. The composite 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 current collector can 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.).

[0099] In the embodiments of this application, the positive electrode active material includes octahedral transition metal oxides and prismatic transition metal oxides. The octahedral transition metal oxides include, but are not limited to, Na. 0.95 Mn 0.33 Fe 0.33 Ni 0.33 O2. Prismatic transition metal oxides, including but not limited to Na. 2 / 3 Mg 1 / 4 Mn 3 / 4 O2.

[0100] Optionally, the positive electrode active material may also include positive electrode active materials known in the art for sodium-ion batteries. For example, the positive electrode active material may also include one or more of polyanionic compounds and Prussian blue compounds. As an example, polyanionic compounds may be compounds having sodium ions, transition metal ions, and tetrahedral anionic units, such as sodium iron phosphate (NaFePO4) and sodium vanadium phosphate (Na3V2(PO4)3). Prussian blue compounds may be compounds having sodium ions, transition metal ions, and cyanide ions. However, this application is not limited to these materials, and other materials that can be used as positive electrode active materials for sodium-ion batteries may also be used. These positive electrode active materials may be used alone or in combination of two or more materials.

[0101] Optionally, the positive electrode film layer may also 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.

[0102] Optionally, the positive electrode film layer includes a conductive agent. As an example, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0103] 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., NMP) to form a positive electrode slurry; coating the positive electrode slurry onto a positive current collector, and then obtaining the positive electrode sheet after drying, cold pressing and other processes.

[0104] [Negative electrode plate]

[0105] In some embodiments, the negative electrode sheet may include 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 comprising a negative electrode active material.

[0106] In some embodiments, the sodium-ion battery is a sodium metal battery, meaning the negative electrode of the sodium-ion battery is also the negative current collector. In other words, the negative current collector directly serves as the negative electrode of the battery, and this type of sodium-ion battery can also be called a "negative electrode-free battery." During charging, sodium ions released from the positive electrode deposit onto the negative current collector to form a sodium metal negative electrode, in which sodium metal is the negative electrode active material. In other embodiments, for the normal use of the negative electrode or to facilitate the deposition of sodium metal on the negative current collector, a conductive film layer (functional coating) can be provided on the negative current collector.

[0107] 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.

[0108] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer substrate and a metal layer formed on at least one surface of the polymer substrate. The composite 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 substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0109] In some embodiments, the negative electrode active material may be a negative electrode active material known in the art for use in batteries. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate, etc. The silicon-based material may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, this application is not limited to these materials, and other conventional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0110] 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).

[0111] 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.

[0112] In some embodiments, the negative electrode film may optionally include other additives, such as thickeners (e.g., sodium carboxymethyl cellulose (CMC-Na)).

[0113] 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 obtaining the negative electrode sheet after drying, cold pressing and other processes; or the negative electrode slurry can be disposed on at least one surface of the negative electrode current collector by methods such as physical vapor deposition (PVD), spin coating, electroplating, chemical vapor deposition (CVD).

[0114] [Electrolytes]

[0115] The electrolyte acts as a conductor of ions between the positive and negative electrodes. This application does not impose specific restrictions on the type of electrolyte; it can be selected according to requirements. For example, the electrolyte can be liquid, gel, or entirely solid.

[0116] In some embodiments, the electrolyte is an electrolyte solution. The electrolyte solution includes an electrolyte salt and a solvent.

[0117] Optionally, the electrolyte salts include NaPF6, NaBCl4, NaSO3CF3, and Na(CH3)C6H4SO3, etc.

[0118] Optionally, the solvent includes carbonate or ether solvents. Carbonate solvents include cyclic ethylene carbonate (EC), propylene carbonate (PC), fluoroethylene carbonate (FEC), and chain-like dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (EMC), etc.; ether solvents include ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, tetrahydrofuran, 1,3-dioxane, etc.

[0119] Optionally, the electrolyte may also include additives. For example, additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives that can improve certain battery performance, such as additives that improve battery overcharge performance, additives that improve battery high-temperature or low-temperature performance, etc.

[0120] [Isolation membrane]

[0121] In some embodiments, the secondary battery also includes a separator. This application does not impose any particular limitation on the type of separator; any known porous separator with good chemical and mechanical stability can be selected.

[0122] In some embodiments, the material of the separator can be selected from at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0123] In some implementations, the positive electrode, negative electrode, and separator can be fabricated into an electrode assembly using a winding or stacking process.

[0124] [Battery Device]

[0125] In some embodiments, the secondary battery may include an outer packaging. This outer packaging may be used to encapsulate the electrode assembly and electrolyte described above.

[0126] In some embodiments, the outer packaging of the secondary battery can be a hard shell, such as a hard plastic shell, an aluminum shell, or a steel shell. The outer packaging of the secondary battery can also be a soft pack, such as a pouch. The material of the soft pack can be plastic; examples of plastics include polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0127] This application does not impose any particular limitation on the shape of the secondary battery; it can be cylindrical, square, or any other arbitrary shape. For example, Figure 7 This is a square-structured battery cell 3, used as an example.

[0128] In some implementations, refer to Figure 7 The battery cell 3 includes a housing 31, an end cap assembly 32, and an electrode assembly 33 disposed within the housing 31. The housing 31 may include a base plate and side plates connected to the base plate, the base plate and side plates forming a receiving cavity. The housing 31 has an opening communicating with the receiving cavity, and the end cap assembly 32 can be closed by covering the opening. The end cap assembly 32 includes electrode terminals 322, such as... Figure 7 As shown, 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. The electrode assembly 33 is encapsulated within the receiving cavity. Electrolyte is immersed in the electrode assembly 33. The positive electrode sheet, negative electrode sheet, and separator can be formed into the electrode assembly 33 by a winding process or a stacking process. The battery cell 3 also includes a connecting member 34, which is used to connect the tabs 331 and the electrode terminals 322 of the electrode assembly 33. The number of electrode assemblies 33 contained in the battery cell 3 can be one or more, and those skilled in the art can select according to specific practical needs.

[0129] In some implementations, the secondary batteries can be assembled into a battery module, and the number of secondary batteries contained in the battery module can be one or more, the specific number of which can be selected by those skilled in the art according to the application and capacity of the battery module.

[0130] Figure 8 Battery 4 is used as an example. (See reference...) Figure 8 In battery 4, multiple battery cells 3 can be arranged sequentially along the length of battery 4. Of course, they can also be arranged in any other manner. Furthermore, these multiple battery cells 3 can be fixed in place using fasteners.

[0131] Optionally, the battery 4 may also include a housing with a receiving space in which multiple battery cells 3 are housed.

[0132] In some embodiments, the battery modules described above can also be assembled into a battery / battery pack. The number of battery modules contained in the battery pack can be one or more, and the specific number can be selected by those skilled in the art according to the application and capacity of the battery pack.

[0133] [Electrical appliances]

[0134] In addition, this application also provides an electrical device, which includes at least one of the secondary battery, battery module, or battery pack provided in this application. The secondary battery, battery module, or battery pack can be used as a power source for the electrical device, or as an energy storage unit for the electrical device. The electrical device may include, but is not limited to, mobile devices (e.g., mobile phones, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.

[0135] As the electrical device, a secondary battery, battery module, or battery pack can be selected according to its usage requirements.

[0136] Figure 9 This is an example of an electrical device. This electrical device 5 is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. To meet the high power and high energy density requirements of the secondary battery for this electrical device, a battery pack or battery module can be used.

[0137] Another example device could be a mobile phone, tablet, or laptop. These devices typically require a slim and lightweight design and can use a rechargeable battery as their power source.

[0138] 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: The positive electrode sheet includes a positive current collector and a positive active material layer; The negative electrode sheet includes a negative current collector, the surface of which has a first region and a second region disposed adjacent to each other along a first direction, wherein the size of the second region in the first direction is larger than the size of the positive active material layer. The surface of the first region of the negative electrode sheet is provided with a first coating. The first coating comprises metal nanoparticles.

2. The battery cell according to claim 1, characterized in that, In the first direction, the first region is distributed on both sides of the second region.

3. The battery cell according to claim 1 or 2, characterized in that, The metal nanoparticles include at least one of the following: silver nanoparticles, tungsten nanoparticles, iron oxide nanoparticles, cobalt nanoparticles, and nickel nanoparticles.

4. The battery cell according to claim 3, characterized in that, The metal nanoparticles include at least one of iron oxide nanoparticles, cobalt nanoparticles, and nickel nanoparticles.

5. The battery cell according to any one of claims 1 to 4, characterized in that, The particle size of the metal nanoparticles is 1 nm to 200 nm.

6. The battery cell according to claim 5, characterized in that, The particle size of the metal nanoparticles is 3nm to 50nm.

7. The battery cell according to any one of claims 1 to 6, characterized in that, The size of the metal nanoparticle aggregates is 20 nm to 5000 nm.

8. The battery cell according to claim 7, characterized in that, The size of the metal nanoparticle aggregates is 20 nm to 2000 nm.

9. The battery cell according to any one of claims 1 to 8, characterized in that, The first coating also includes a binder and a dispersant; Based on the total mass of the first coating, the mass content A of the metal nanoparticles is 30wt% to 97.5wt%, the mass content B of the binder is 2wt% to 50wt%, and the mass content C of the dispersant is 0.5wt% to 20wt%.

10. The battery cell according to any one of claims 1 to 9, characterized in that, The thickness d of the first coating is 0.05μm to 60μm.

11. The battery cell according to any one of claims 1 to 10, characterized in that, An insulating layer is provided on the surface of the first coating.

12. The battery cell according to claim 11, characterized in that, The insulating layer includes one of the following: organic polymer insulating materials, inorganic insulating materials, and composite materials.

13. The battery cell according to any one of claims 1 to 12, characterized in that, The surface of the second region of the negative electrode sheet is provided with a second coating, the second coating including at least one of a functional coating and a negative electrode active material layer.

14. The battery cell according to claim 13, characterized in that, The thickness dl of the second coating satisfies: dl≤50μm.

15. The battery cell according to claim 14, characterized in that, dl≤20μm.

16. The battery cell according to any one of claims 1 to 15, characterized in that, The negative electrode current collector is an aluminum foil current collector.

17. A method for preparing a single battery cell, characterized in that, include: A positive electrode and a negative electrode are provided to prepare the battery cell; The positive electrode sheet includes a positive current collector and a positive active material layer; The negative electrode sheet includes a negative electrode current collector, and the surface of the negative electrode current collector has a first region and a second region disposed adjacent to each other along a first direction. The size of the second region in the first direction is larger than the size of the positive electrode active material layer. The surface of the first region of the negative electrode sheet is provided with a first coating, which includes metal nanoparticles.

18. The method according to claim 17, characterized in that, Providing the negative electrode sheet involves mixing the metal nanoparticles, a binder, and a dispersant to obtain a first slurry; The first slurry is applied to the first area to form the first coating.

19. The method according to claim 18, characterized in that, The step of covering the first slurry with the first region includes: covering the first slurry with the first region by means of physical vapor deposition, chemical vapor deposition or electroplating.

20. The method according to claim 18, characterized in that, The step of covering the first slurry onto the first area includes: applying the first slurry onto the first area using extrusion coating, gravure coating, or micro-gravure coating.

21. A battery, characterized in that, Includes battery cells as described in any one of claims 1-16, and / or battery cells prepared by the method as described in any one of claims 17-20.

22. An electrical appliance, characterized in that, Includes the battery as described in claim 21.

Images