Electrode plate, secondary battery and electric equipment

Abstract

The invention provides an electrode plate, a secondary battery and electric equipment. The electrode pole piece comprises a current collector, an active material layer arranged on the surface of the current collector and at least one functional layer, wherein the functional layer is arranged on the edge of the current collector, and the functional layer and the active material layer are arranged on the same layer; the functional layer comprises an insulating layer and a bonding layer which is arranged on the surface, deviating from the current collector, of the insulating layer, and the bonding layer comprises a plurality of bonding structures which are arranged at intervals. The functional layer in the edge area of the pole piece of the electrode can realize the bonding of the diaphragm and the pole piece, the bonding strength and stability are relatively high, and the risk of short circuit caused by the contact between the positive electrode and the negative electrode in the battery can be effectively reduced.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to electrode plates, secondary batteries and electrical equipment. Background Art

[0002] Laminated batteries generally include a positive electrode, a negative electrode, and a separator between the positive and negative electrodes. In order to prevent the positive and negative electrodes from short-circuiting due to misaligned contact during assembly and subsequent processes, adhesives are generally applied to the separator surface to fix the separator and the negative electrode. However, adhesives can cause blockage in the pore structure of the separator, affecting the transmission of active ions and causing an increase in the internal resistance of the battery; or, they can cause the edges of the pole pieces to burst and crack, and are difficult to use in thick electrodes. Summary of the invention

[0003] In view of this, the embodiments of the present application provide an electrode plate, a secondary battery and an electrical device. The functional layer in the edge region of the electrode plate can achieve bonding between the diaphragm and the plate, and the bonding strength and stability are both high, and the risk of short circuit caused by contact between the positive electrode and the negative electrode in the battery can be effectively reduced.

[0004] In a first aspect, an embodiment of the present application provides an electrode plate, comprising a current collector, an active material layer disposed on a surface of at least one side of the current collector, and at least one functional layer; wherein the functional layer is disposed at the edge of the current collector, and the functional layer and the active material layer are disposed in the same layer;

[0005] The functional layer includes an insulating layer and a bonding layer disposed on a surface of the insulating layer away from the current collector, and the bonding layer includes a plurality of bonding structures arranged at intervals.

[0006] The functional layer arranged at the edge of the current collector has both insulation and bonding functions. During the shaping process of the battery cell, the bonding layer contacts the diaphragm and adheres to the diaphragm under the pressure applied by the battery cell shaping process. The bonding structures in the bonding layer are distributed at intervals, and deformation buffer areas are left between the bonding structures. Even if the bonding structure is deformed when bonding with the diaphragm, the risk of diffusion to the active material layer and the diaphragm is small, which is beneficial to the structural stability of the internal structure of the battery and the performance of the battery. The presence of the insulating layer can prevent direct contact between the positive and negative pole pieces, and improve the assembly yield and safety performance of the battery.

[0007] In addition, the special structural design of the bonding layer allows the electrode plate to avoid large-area coating of the adhesive slurry used in related technologies during the preparation process, thereby fundamentally avoiding the interpenetration of the adhesive slurry and the active material layer slurry, thereby reducing the risk of edge bursting and cracking of the electrode plate and improving the structural stability of the electrode plate itself.

[0008] In some embodiments of the present application, in the stacking direction of the functional layer and the current collector, the size of the functional layer is x μm, the size of the active material layer is y μm, and 10 μm≤yx≤50 μm.

[0009] In some embodiments of the present application, the thickness of the insulating layer is 50 μm to 300 μm; and / or,

[0010] Along the direction from the functional layer to the active material layer, the size of the insulating layer is 0.1 cm to 1 cm.

[0011] In some embodiments of the present application, the distance between two adjacent bonding structures is 300 μm to 1000 μm; and / or,

[0012] In the stacking direction of the functional layer and the current collector, the size of the bonding structure is 2 μm to 5 μm, and the maximum size of the orthographic projection of the bonding structure is 100 μm to 500 μm.

[0013] In some embodiments of the present application, the material of the bonding structure includes a polymer, and the glass transition temperature of the polymer is -20°C to 100°C;

[0014] The polymer includes a polymer of one or more of methyl methacrylate, butyl methacrylate, and hexyl octyl acrylate.

[0015] In some embodiments of the present application, the insulating layer includes inorganic particles and a binder, the particle size of the inorganic particles is 0.5 μm to 5 μm; and / or the mass proportion of the inorganic particles in the insulating layer is 90% to 99%.

[0016] In some embodiments of the present application, the material of the inorganic particles includes one or more of alumina, boehmite, titanium dioxide, zirconium dioxide, magnesium hydroxide and aluminum hydroxide;

[0017] And / or, the binder comprises carboxymethyl cellulose.

[0018] In some embodiments of the present application, a pole ear is further included, wherein the pole ear is adjacent to the current collector and is disposed close to the functional layer.

[0019] A second aspect of an embodiment of the present application provides a secondary battery, including the electrode plate provided in an embodiment of the present application.

[0020] A third aspect of the embodiments of the present application provides an electrical device, including the secondary battery provided in the embodiments of the present application.

[0021] In some implementations of the present application, the electrical device includes an electronic device, and the secondary battery supplies power to the electronic device. Since the secondary battery provided in the embodiment of the present application is used for power supply, the electrical device has a good market prospect.

[0022] In some embodiments of the present application, the above-mentioned electrical equipment includes but is not limited to vehicles, or 3C electronic consumer products such as mobile phones, laptops, tablets, smart watches, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A schematic structural diagram of a cross section of an electrode plate provided in one embodiment of the present application;

[0024] Figure 2 A top view of a functional layer in an electrode plate provided in an embodiment of the present application;

[0025] Figure 3A A top view of an electrode sheet provided in another embodiment of the present application;

[0026] Figure 3B A top view of an electrode sheet provided in yet another embodiment of the present application;

[0027] Figure 3C A top view of an electrode sheet provided in yet another embodiment of the present application;

[0028] Figure 3D A top view of an electrode plate provided in yet another embodiment of the present application.

[0029] Explanation of the accompanying drawings: 1-electrode pole piece; 10-current collector; 20-active material layer; 30-functional layer; 301-insulating layer; 302-bonding layer; 321-bonding structure; 40-ear. DETAILED DESCRIPTION

[0030] See also Figure 1-Figure 2 The present application embodiment provides an electrode plate 1, comprising a current collector 10, an active material layer 20 disposed on the surface of at least one side of the current collector 10, and at least one functional layer 30; wherein the functional layer 30 is disposed at the edge of the current collector 10, and the functional layer 30 and the active material layer 20 are disposed in the same layer;

[0031] The functional layer 30 includes an insulating layer 301 and a bonding layer 302 disposed on a surface of the insulating layer 301 facing away from the current collector 10 . The bonding layer 302 includes a plurality of bonding structures 321 arranged at intervals.

[0032] The functional layer 30 arranged at the edge of the current collector 10 has both insulating and bonding functions. During the shaping process of the battery cell, the bonding layer 302 contacts the diaphragm and adheres to the diaphragm under the pressure applied by the battery cell shaping process; and the bonding structures 321 in the bonding layer 302 are distributed at intervals, and a deformation buffer area is left between the bonding structures 321. Even if the bonding structure 321 is deformed when bonding with the diaphragm, the risk of diffusion between the active material layer 20 and the diaphragm is small, which is beneficial to the structural stability of the internal structure of the battery and the performance of the battery. Considering that the sizes of the positive and negative pole pieces in the battery are not necessarily exactly the same, there is a risk of direct contact between the positive and negative pole pieces during stacking or subsequent shaping and under extreme working conditions, and the presence of the insulating layer 301 can prevent direct contact between the positive and negative pole pieces, thereby improving the assembly yield and safety performance of the battery.

[0033] In addition, the special structural design of the adhesive layer 302 allows the electrode plate 1 to avoid the large-area coating of the adhesive slurry used in the related art during the preparation process, thereby fundamentally avoiding the interpenetration of the adhesive slurry and the active material layer 20 slurry, thereby reducing the risk of edge bursting and cracking of the electrode plate, and improving the structural stability of the electrode plate 1 itself. Furthermore, compared with the solutions in the related art, which need to increase the thickness of the adhesive coating to match the thick active material layer 20, resulting in cracking of the adhesive coating, the electrode plate 1 provided in the embodiment of the present application can flexibly adjust the thickness of the functional layer 30 when it is necessary to match the thick active material layer 20, and it will not crack even if the thickness of the adhesive layer 302 is increased.

[0034] In the embodiment of the present application, the electrode plate 1 can be a positive electrode plate or a negative electrode plate. In some specific embodiments, the electrode plate 1 is a negative electrode plate.

[0035] In the embodiment of the present application, the active material layer 20 and the functional layer 30 may be disposed on one side of the electrode plate 1, or on both sides of the electrode plate 1. The above are all considered as the protection scope of the present application.

[0036] In the embodiment of the present application, the insulating layer 301 and the active material layer 20 may be arranged adjacent to each other, or a certain gap may be left between them.

[0037] In the embodiments of this application, please refer to Figure 3A-3D, taking the orthographic projection of the active material layer 20 as a rectangle as an example, the functional layer 30 may be disposed on one side of the active material layer 20; the functional layer 30 may be disposed on both sides of the active material layer 20 (specifically, the functional layer 30 may be disposed on the opposite sides of the active material layer 20, or the functional layer 30 may be disposed on the adjacent two sides of the active material layer 20); or the functional layer 30 may be disposed on three sides of the active material layer 20; or the functional layer 30 may be disposed around the periphery of the active material layer 20. This application does not limit this, and technicians in the field can make a choice according to actual production needs.

[0038] It is understandable that the electrode plate 1 may also be provided with a tab 40. In some embodiments of the present application, the electrode plate 1 includes a tab 40, the tab 40 is adjacent to the current collector 10, and the tab 40 is provided close to the functional layer 30. Figure 3A As shown, in some specific embodiments, an active material layer 20 and a functional layer 30 are disposed on one side of the current collector 10, and the functional layer 30 is disposed close to the tab 40. The tab 40 can be welded to the current collector 10 or integrally formed with the current collector 10.

[0039] For the convenience of description, the stacking direction of the functional layer 30 and the current collector 10 is defined as the first direction. In some embodiments of the present application, in the stacking direction of the functional layer 30 and the current collector 10 (that is, in the first direction), the size of the functional layer 30 is xμm, the size of the active material layer 20 is yμm, and 10μm≤yx≤50μm. In the embodiment of the present application, the size of the functional layer 30 in the first direction refers to the distance from the highest point of the bonding structure 321 in the first direction to the surface of the current collector 10; the size of the active material layer 20 in the first direction is essentially the thickness of the active material layer 20. Controlling yx within the range of 10μm-50μm is conducive to the bonding of the electrode plate 1 and the diaphragm in the battery cell shaping process, and is also conducive to saving space inside the battery cell and improving the volume energy density of the battery. Specifically, yx can be, for example, 10μm, 15μm, 20μm, 25m, 30μm, 35μm, 40μm, 45μm, 50μm, etc.

[0040] In some embodiments of the present application, the thickness of the insulating layer 301 is 50 μm to 300 μm. The thickness of the insulating layer 301 can be adjusted according to the thickness of the active material layer 20 and the size of the bonding structure 321. Controlling the thickness of the insulating layer 301 within the above range is also conducive to the performance of the insulating performance. Specifically, the thickness of the insulating layer 301 can be, for example, 50 μm, 80 μm, 100 μm, 120 μm, 150 μm, 180 μm, 200 μm, 220 μm, 250 μm, 280 μm, 300 μm, etc.

[0041] In some embodiments of the present application, the size (L) of the insulating layer 301 in the direction from the functional layer 30 to the active material layer 20 is 0.1 cm to 1 cm. That is, the width of the insulating layer 301 is 0.1 cm to 1 cm. In this way, it can be used to carry a sufficient amount of bonding structure 321 to improve the peeling strength between the electrode plate 1 and the diaphragm, and can also provide sufficient buffer area for the misalignment of the electrode plate 1, and help to ensure the energy density of the battery. Specifically, in the direction from the functional layer 30 to the active material layer 20, the lateral size of the insulating layer 301 can be, for example, 0.1 cm, 0.2 cm, 0.3 cm, 0.4 cm, 0.5 cm, 0.6 cm, 0.7 cm, 0.8 cm, 0.9 cm, 1.0 cm, etc.

[0042] In some embodiments of the present application, the insulating layer 301 includes inorganic particles and a binder. The inorganic particles have good insulation properties, and the presence of the binder facilitates the molding of the insulating layer 301 and maintains the structural stability of the insulating layer 301. In some specific embodiments, the material of the inorganic particles includes one or more of alumina, boehmite, titanium dioxide, zirconium dioxide, magnesium hydroxide, and aluminum hydroxide.

[0043] In some embodiments of the present application, the particle size of the inorganic particles is 0.5 μm to 5 μm. This is beneficial to regulating the thickness of the insulating layer 301 and facilitating the preparation of the insulating layer 301. Specifically, the particle size of the inorganic particles can be, for example, 0.5 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, or 5 μm.

[0044] In some embodiments of the present application, the mass proportion of inorganic particles in the insulating layer 301 is 90%-99%, and the mass proportion of the binder in the insulating layer 301 is 1%-10%. Specifically, the mass proportion of inorganic particles in the insulating layer 301 can be, for example, 90%, 92%, 95%, 98%, etc., and the mass proportion of the binder in the insulating layer 301 can be, for example, 1%, 2%, 5%, 8%, 10%, etc.

[0045] In some embodiments of the present application, the binder in the insulating layer 301 includes but is not limited to carboxymethyl cellulose. Carboxymethyl cellulose has a large surface tension, which can reduce the risk of interpenetration between the slurry of the insulating layer 301 and the slurry of the active material layer 20 during the preparation of the electrode plate 1, and is beneficial to the structural stability of the electrode plate 1 and the performance of the electrochemical performance.

[0046] In some embodiments of the present application, along the stacking direction of the functional layer 30 and the current collector 10 (that is, in the first direction), the size of the bonding structure 321 is 2 μm to 5 μm. In other words, the height of the bonding structure 321 is 2 μm to 5 μm. In this way, the bonding performance of the bonding layer 302 is good and easy to prepare. Specifically, the size of the bonding structure 321 in the first direction can be, for example, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm, etc.

[0047] In some embodiments of the present application, the maximum size of the orthographic projection of the bonding structure 321 in the first direction is 100 μm to 500 μm. Similarly, in this way, the bonding performance of the bonding layer 302 is better and easy to prepare. Specifically, the maximum lateral size of the orthographic projection of the bonding structure 321 in the first direction can be, for example, 100 μm, 150 μm, 200 μm, 250 μm, 300 μm, 350 μm, 400 μm, 450 μm, 500 μm, etc. In an embodiment of the present application, the orthographic projection of the bonding structure 321 in the first direction can be a circle, an ellipse, a multi-deformation, an irregular shape, etc. For example, when the orthographic projection of the bonding structure 321 in the first direction is a circle, the above maximum size is the diameter of the circle.

[0048] In some embodiments of the present application, the distance d between two adjacent bonding structures 321 is 300μm to 1000μm. In this way, the bonding performance of the bonding layer 302 is better and the cost is lower. In the embodiment of the present application, among the multiple bonding structures 321, the distance between any two adjacent bonding structures 321 can be equal or unequal. Specifically, the distance between two adjacent bonding structures 321 can be, for example, 300μm, 400μm, 500μm, 600μm, 700μm, 800μm, 900μm, 1000μm, etc.

[0049] In some embodiments of the present application, the material of the bonding structure 321 includes a polymer, and the glass transition temperature of the polymer is -20°C to 100°C. In this way, the bonding structure 321 can be dried using a blower at room temperature, without the need for oven baking, and is easy to prepare, and it can be bonded to the diaphragm under the conditions commonly used in the shaping process of the battery cell (normal temperature, pressure of 0.5MPa-1MPa), saving process and energy. Specifically, the glass transition temperature of the polymer can be, for example, -20°C, -10°C, 0°C, 10°C, 20°C, 50°C, 80°C, 100°C, etc. In some embodiments of the present application, the material of the bonding structure 321 includes, but is not limited to, one or more polymers of methyl methacrylate, butyl methacrylate, and hexyl octyl acrylate. The bonding structure 321 containing the above-mentioned materials can be bonded to any known diaphragm in the field and the surface of the aforementioned insulating layer 301. In the embodiment of the present application, normal temperature refers to 25±3°C.

[0050] In some embodiments of the present application, the preparation of the electrode plate 1 may include:

[0051] An active material layer and an insulating layer are formed on the surface of the current collector, and a bonding layer is formed on the surface of the insulating layer facing away from the current collector.

[0052] In the embodiment of the present application, the formation of the insulating layer includes: coating an insulating slurry on the surface of the current collector.

[0053] In some embodiments of the present application, the solid content of the insulating paste is 30wt%-60wt%. In this way, the viscosity of the insulating paste can be controlled within a suitable range, which is conducive to the preparation and molding of the insulating layer. Specifically, the solid content of the insulating paste can be, for example, 30wt%, 35wt%, 40wt%, 45wt%, 50wt%, 55wt%, 60wt%, etc.

[0054] In some embodiments of the present application, the room temperature viscosity of the insulating slurry is 2500mpa·s-4000mpa·s. This is conducive to the preparation and molding of the insulating layer. Specifically, the room temperature viscosity of the insulating slurry can be, for example, 2500mpa·s, 2800mpa·s, 3000mpa·s, 3200mpa·s, 3500mpa·s, 3800mpa·s, 4000mpa·s, etc. In the embodiments of the present application, the test method of the room temperature viscosity of the insulating slurry can refer to the national standard: GB / T1904-2005.

[0055] In some embodiments of the present application, the active material layer and the insulating layer may be obtained by simultaneous coating or separately coating. The coating method may be extrusion coating. In some specific embodiments of the present application, the insulating layer and the active material layer are formed simultaneously. Specifically, the insulating layer slurry and the active material layer slurry may be simultaneously coated on a preset area on the current collector, for example, using a double coating head.

[0056] In some embodiments of the present application, the bonding structure can be prepared by a piston-type spot coating method. The spot coating process can prevent the insulating layer slurry from interpenetrating with the active material layer or the active material layer slurry, thereby effectively reducing the risk of edge bursting and cracking of the pole piece. Specifically, the bonding layer slurry is spot coated on a preset area of ​​the insulating layer by a piston-type spot coating method, and the coating head is installed at the outlet of the oven and equipped with a small blower.

[0057] In some embodiments of the present application, the solid content of the bonding layer slurry is 40wt%-60wt%. In this way, the viscosity of the bonding layer slurry can be controlled within a suitable range, which is conducive to the preparation and molding of the bonding structure. Specifically, the solid content of the bonding layer slurry can be, for example, 40wt%, 42wt%, 45wt%, 48wt%, 50wt%, 52wt%, 55wt%, 58wt%, 60wt%, etc.

[0058] In some embodiments of the present application, the room temperature viscosity of the bonding layer slurry is 200mpa·s-300mpa·s. This is conducive to the preparation and molding of the bonding structure. Specifically, the room temperature viscosity of the bonding layer slurry can be, for example, 200mpa·s, 220mpa·s, 250mpa·s, 280mpa·s, 300mpa·s, etc. In the embodiments of the present application, the test method of the room temperature viscosity of the bonding layer slurry can refer to the national standard: GB / T1904-2005.

[0059] In the embodiments of the present application, the active material layer may be any positive electrode active material layer or negative electrode active material layer known in the art and applicable to a corresponding type of secondary battery.

[0060] In some embodiments of the present application, the active material layer is a negative electrode active material layer, that is, the electrode plate is a negative electrode plate.

[0061] In the embodiments of the present application, the above-mentioned current collector can be any current collector known in the art.

[0062] The embodiment of the present application also provides a secondary battery, comprising the aforementioned electrode plate provided in the embodiment of the present application.

[0063] In some embodiments of the present application, at least part of the negative electrode sheets in the secondary battery are provided in the embodiments of the present application, and the positive electrode sheets are any electrode sheets known in the art. In other embodiments, at least part of the positive electrode sheets in the secondary battery are provided in the embodiments of the present application, and the negative electrode sheets are any electrode sheets known in the art. In still other embodiments, at least part of the positive electrode sheets in the secondary battery are provided in the embodiments of the present application, and at least part of the negative electrode sheets are provided in the embodiments of the present application.

[0064] In the embodiments of the present application, the secondary battery includes but is not limited to any known secondary battery such as a lithium ion battery, a sodium ion battery, and a magnesium ion battery.

[0065] In some embodiments of the present application, the secondary battery includes a positive electrode sheet, a negative electrode sheet and a separator, the separator is located between the positive electrode sheet and the negative electrode sheet, and a part of the separator is bonded to the positive electrode sheet and / or the negative electrode sheet through a bonding layer. The separator can be a separator known in the industry, for example, a single-layer polypropylene (PP) film, a single-layer polyethylene (PE) film, a double-layer film PP / PE, a double-layer film PP / PP, a triple-layer PP / PE / PP, or a polymer separator, or a non-woven fabric, etc.

[0066] In some embodiments of the present application, an electrolyte is also included between the positive electrode plate and the negative electrode plate.

[0067] The present application also provides an electric device, including the secondary battery provided in the present application. In some embodiments of the present application, the electric device includes an electronic device, and the secondary battery supplies power to the electronic device. Since the electric device is powered by the secondary battery provided in the present application, the electric device has a good market prospect.

[0068] In some embodiments of the present application, the above-mentioned electrical equipment includes but is not limited to vehicles, or 3C electronic consumer products such as mobile phones, laptops, tablets, smart watches, etc.

[0069] The technical solution of the present application is further illustrated by multiple embodiments below.

[0070] Example 1

[0071] A negative electrode sheet, comprising a current collector and a negative electrode active material layer with a thickness of 230 μm arranged on the surface of the current collector, and a functional layer arranged on one side of the negative electrode active material, wherein the functional layer comprises an insulating layer and a bonding layer arranged in a stacked manner, the bonding layer is arranged away from the current collector, and the bonding layer comprises a plurality of bonding structures;

[0072] The insulating layer is composed of alumina particles with a particle size of 0.8 μm and a binder (carboxymethyl cellulose), with the mass proportion of alumina particles being 9% and the mass proportion of alumina particles being 91%; the size of the insulating layer is 0.5 cm along the direction from the functional layer to the negative electrode active material layer. The thickness of the insulating layer is 200 μm.

[0073] The material of the bonding structure is polymethyl methacrylate, the glass transition temperature is -20°C, the distance between two adjacent bonding structures is 300 μm, the orthographic projection of the bonding structure in the first direction is a circle with a diameter of 100 μm, and the height of the bonding structure is 2.5 μm.

[0074] Among them, the above-mentioned insulating layer and negative electrode active material layer are extrusion coated on the current collector simultaneously. In the insulating slurry, the mass proportion of carboxymethyl cellulose is 9%, the solid content of the insulating slurry is 42%, the solvent is water, and the viscosity at room temperature is 3000 MPa·s; the solid content of the bonding layer slurry is 45%, and the viscosity at room temperature is 200 MPa·s.

[0075] Example 2

[0076] The difference from Example 1 is that the insulating layer is composed of boehmite particles with a particle size of 0.5 μm and a binder (carboxymethyl cellulose), the mass proportion of aluminum oxide particles is 6%, and the mass proportion of boehmite particles is 94%; the size of the insulating layer along the direction from the functional layer to the negative electrode active material layer is 0.5 cm. The thickness of the insulating layer is 200 μm.

[0077] The material of the bonding structure is polymethyl methacrylate particles, the glass transition temperature is -40°C, the distance between two adjacent bonding structures is 300μm, the positive projection of the bonding structure in the first direction is a circle with a diameter of 100μm, and the height of the bonding structure is 2.0μm. Among them, the above-mentioned insulating layer and the negative electrode active material layer are extruded and coated on the current collector simultaneously. In the insulating slurry, the mass proportion of carboxymethyl cellulose is 6%, the solid content of the insulating slurry is 40%, the solvent is water, and the viscosity at room temperature is 3500mpa·s; the solid content of the bonding layer slurry is 45%, and the viscosity at room temperature is 200mpa·s.

[0078] Example 3

[0079] The difference from Example 1 is that in the bonding layer, the distance between two adjacent bonding structures is 1000 μm.

[0080] Example 4

[0081] The difference from Example 1 is that in the bonding layer, the distance between two adjacent bonding structures is 750 μm.

[0082] Example 5

[0083] The difference from Example 1 is that in the bonding layer, the distance between two adjacent bonding structures is 1100 μm.

[0084] Example 6

[0085] The difference from Example 1 is that, in the bonding layer, the orthographic projection of the bonding structure in the first direction is a circle with a diameter of 500 μm.

[0086] Example 7

[0087] The difference from Example 1 is that in the bonding layer, the height of the bonding structure is 5 μm.

[0088] Example 8

[0089] The difference from Example 1 is that in the bonding layer, the height of the bonding structure is 1 μm.

[0090] In order to highlight the beneficial effects of the embodiments of the present application, the following comparative examples are provided.

[0091] Comparative Example 1

[0092] The difference from Example 1 is that the negative electrode active material layer and the insulating adhesive layer are arranged on the surface of the current collector in the same layer; the insulating adhesive layer includes 89% by mass of boehmite particles, 2% of carboxymethyl cellulose, and 9% of hot melt adhesive. The thickness of the negative electrode active material layer is 230 μm, the thickness of the insulating adhesive layer is 200 μm, and the width is 0.5 cm.

[0093] Performance Testing

[0094] The negative electrode plates provided in the embodiments and comparative examples are bonded to the separators, specifically:

[0095] Example 1-Example 8 The negative electrode plate and the separator were bonded at 25° C. and a pressure of 1 MPa, and the peel strength was tested according to GB / T2792. The results are summarized in Table 1.

[0096] The negative electrode sheet of Comparative Example 1 cannot be bonded to the separator under the above conditions and needs to be hot-pressed and composited for 5 minutes at 100°C and 1 MPa to allow the separator to bond to the negative electrode sheet. The peel strength is then tested according to GB / T2792. The results are summarized in Table 1.

[0097] Table 1

[0098] Case Peel strength Example 1 1.0N / m Example 2 1.2N / m Example 3 0.6N / m Example 4 0.7N / m Example 5 0.5N / m Example 6 1.4N / m Example 7 1.3N / m Example 8 0.5N / m Comparative Example 1 0.4N / m

[0099] From the above data, it can be seen that the electrode sheet provided in the embodiment of the present application can be smoothly and stably bonded to the diaphragm under the conventional process conditions of battery cell shaping, and the peel strength is relatively high. In addition, when the relevant parameters of the bonding structure are within the range further recommended by the present application, the peel strength between the electrode sheet and the diaphragm is relatively higher.

[0100] The above is an exemplary embodiment of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made thereto without departing from the principles of the present application. These improvements and modifications are also considered to be within the scope of protection of the present application.

Claims

1. An electrode plate, characterized in that: It comprises a current collector, an active material layer and at least one functional layer arranged on at least one side surface of the current collector; wherein the functional layer is arranged at the edge of the current collector, and the functional layer and the active material layer are arranged in the same layer; The functional layer includes an insulating layer and a bonding layer disposed on a surface of the insulating layer away from the current collector, and the bonding layer includes a plurality of bonding structures arranged at intervals.

2. The electrode plate according to claim 1, characterized in that: In the stacking direction of the functional layer and the current collector, the size of the functional layer is x μm, the size of the active material layer is y μm, and 10 μm≤yx≤50 μm.

3. The electrode plate according to claim 1 or 2, characterized in that: The thickness of the insulating layer is 50 μm to 300 μm; and / or, Along the direction from the functional layer to the active material layer, the size of the insulating layer is 0.1 cm to 1 cm.

4. The electrode sheet according to any one of claims 1 to 3, characterized in that: The distance between two adjacent bonding structures is 300 μm to 1000 μm; and / or, In the stacking direction of the functional layer and the current collector, the size of the bonding structure is 2 μm to 5 μm, and the maximum size of the orthographic projection of the bonding structure is 100 μm to 500 μm.

5. The electrode sheet according to any one of claims 1 to 4, characterized in that: The material of the bonding structure includes a polymer, and the glass transition temperature of the polymer is -20°C to 100°C; The polymer includes a polymer of one or more of methyl methacrylate, butyl methacrylate, and hexyl octyl acrylate.

6. The electrode sheet according to any one of claims 1 to 5, characterized in that: The insulating layer comprises inorganic particles and a binder, wherein the particle size of the inorganic particles is 0.5 μm to 5 μm; and / or the mass proportion of the inorganic particles in the insulating layer is 90% to 99%.

7. The electrode plate according to claim 6, characterized in that: The material of the inorganic particles includes one or more of alumina, boehmite, titanium dioxide, zirconium dioxide, magnesium hydroxide and aluminum hydroxide; And / or, the binder comprises carboxymethyl cellulose.

8. The electrode plate according to any one of claims 1 to 7, characterized in that: It also includes a pole ear, which is adjacent to the current collector and is arranged close to the functional layer.

9. A secondary battery, characterized in that: It comprises the electrode plate as claimed in any one of claims 1 to 8.

10. An electrical device, characterized in that: Comprising the secondary battery as claimed in claim 9.

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