Positive electrode sheet, positive electrode sheet manufacturing process and lithium-ion battery

Abstract

The present invention relates to a positive electrode sheet, a positive electrode sheet manufacturing process and a lithium-ion battery. A positive electrode sheet comprises: a substrate; a tab protruding from the edge of the substrate; an active material layer, the surface of the substrate partially covers the active material layer, and the edge of the substrate is exposed; a first insulating layer wrapped around the edge of the substrate; and a second insulating layer provided on the surface of the tab. A manufacturing process for the above-mentioned positive electrode sheet comprises: coating the active material layer and the second insulating layer on the surface of the substrate respectively, and exposing the edge of the substrate; cutting and forming the tab on the substrate having the active material layer and the second insulating layer; coating the first insulating layer on the edge of the substrate. A lithium-ion battery comprises: the above-mentioned positive electrode sheet; a negative electrode sheet, the width of the negative electrode sheet is smaller than the width of the positive electrode sheet; and a separator provided between the positive electrode sheet and the negative electrode sheet. The above-mentioned electrode sheet, electrode sheet manufacturing process and lithium-ion battery can effectively reduce the risk of overlap between the positive electrode sheet and the negative electrode sheet.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium batteries, and in particular to a positive electrode sheet, a positive electrode sheet manufacturing process and a lithium ion battery. Background Art

[0002] The wound lithium-ion battery generally consists of a positive electrode sheet, a separator and a negative electrode sheet that need to be wound and assembled into a battery cell, and then undergo subsequent processing steps to form a finished lithium-ion battery. Before winding, the positive electrode sheet and the negative electrode sheet need to be prepared first.

[0003] In the process of preparing the positive electrode sheet, the substrate needs to be cut and sliced, and the edges of the substrate need to be cut to form the tabs. When the substrate is cut and the tabs are cut on the substrate, burrs will be generated at the cuts of the substrate. When the positive and negative electrode sheets are wound, the exposed burrs of the substrate can easily cause the positive and negative electrode sheets to overlap and short-circuit, affecting the safety of lithium-ion batteries. Summary of the invention

[0004] Based on this, it is necessary to provide a positive electrode sheet, a positive electrode sheet manufacturing process and a lithium-ion battery to address the problem of easy overlapping and short circuiting of positive and negative electrode sheets when they are wound.

[0005] A positive electrode sheet, comprising:

[0006] Base material;

[0007] The tab is protruding from the edge of the substrate;

[0008] An active material layer, wherein the surface of the substrate is partially covered with the active material layer, and the edge of the substrate is exposed;

[0009] A first insulating layer wrapped around the edge of the substrate; and

[0010] The second insulating layer is arranged on the surface of the tab.

[0011] The above-mentioned positive electrode sheet has the edge of the substrate wrapped with a first insulating layer, and the surface of the tab is also provided with a second insulating layer, which can better ensure the insulation effectiveness of the edge and tab of the positive electrode sheet, avoid the exposure of burrs on the edge of the positive electrode sheet and cause short circuit between the positive and negative electrode sheets, and at the same time effectively reduce the risk of overlap between the positive electrode tab and the negative electrode tab, thereby ensuring the safety of product use.

[0012] In one embodiment, the substrate includes a first surface, a second surface and a first end surface. The first end surface is connected between the first surface and the second surface. The first surface and the second surface are arranged opposite to each other. The edge of the substrate includes the first end surface. In this embodiment, the first insulating layer covers the first end surface, effectively preventing the burrs generated by cutting the pole ear from being exposed on the first end surface, thereby avoiding the overlap of the positive and negative pole sheets and causing an internal short circuit.

[0013] In one embodiment, the edge of the substrate further includes a first edge of the first surface and / or a second edge of the second surface. In this embodiment, the first edge of the first surface and / or the second edge of the second surface are effectively prevented from being exposed, so as to further effectively avoid the positive and negative electrode sheets from overlapping and causing an internal short circuit.

[0014] In one embodiment, the edge of the active material layer is connected to the edge of the first insulating layer. In this embodiment, there is no gap at the junction of the active material layer and the first insulating layer, which increases the bonding force at the junction of the active material layer and the first insulating layer, and prevents the substrate from being exposed due to a gap at the junction of the active material layer and the first insulating layer, thereby preventing the substrate from being damaged.

[0015] In one embodiment, the first insulating layer is planar on the side with the tab. In this embodiment, the insulation of the edge of the substrate is effectively guaranteed and the space occupied is small.

[0016] In one embodiment, the first insulating layer is curved on the side with the pole ear and is convexly arranged toward the edge away from the substrate. In this embodiment, the first insulating layer has a redundant portion relative to the edge of the substrate. The existence of the redundant portion can increase the pressure-bearing space, avoid external pressure from damaging the edge of the substrate, and help extend the service life of the substrate.

[0017] In one embodiment, the viscosity of the first insulating layer is greater than that of the second insulating layer. In this embodiment, the adhesion between the first insulating layer and the edge of the substrate can be effectively enhanced to prevent the first insulating layer from falling off the edge of the substrate.

[0018] In one embodiment, the second insulating layer is spaced apart from the edge of the substrate. In this embodiment, the first insulating layer and the second insulating layer are prevented from overlapping each other, thereby preventing the positive electrode sheet from being too thick and affecting normal use of the positive electrode sheet.

[0019] A manufacturing process of the above-mentioned positive electrode sheet comprises:

[0020] The active material layer and the second insulating layer are respectively coated on the surface of the substrate, and the edge of the substrate is exposed;

[0021] Cutting and forming a tab on the substrate having the active material layer and the second insulating layer;

[0022] The first insulating layer is coated on the edge of the substrate.

[0023] In the manufacturing process of the positive electrode sheet, the first insulating layer is applied after the tab is cut on the substrate, which can effectively prevent the burrs on the first end surface caused by cutting the tab from being exposed, thereby avoiding the overlap of the positive and negative electrode sheets and causing an internal short circuit. A second insulating layer is also provided on the surface of the tab, which can effectively reduce the risk of overlap between the positive and negative tabs and ensure the safety of the product.

[0024] A lithium-ion battery, comprising:

[0025] The above-mentioned positive electrode sheet;

[0026] Negative electrode;

[0027] The separator is provided between the positive electrode sheet and the negative electrode sheet.

[0028] The above-mentioned lithium-ion battery can effectively reduce the risk of overlapping of the positive electrode sheet and the negative electrode sheet by providing the above-mentioned positive electrode sheet, thereby ensuring the safety of product use. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is an axonometric view of a positive electrode sheet in one embodiment;

[0030] Figure 2 for Figure 1 A front view of the positive electrode sheet shown;

[0031] Figure 3 is a side view of a positive electrode sheet in one embodiment;

[0032] Figure 4 is a side view of a positive electrode sheet in another embodiment;

[0033] Figure 5 for Figure 1 The manufacturing process flow chart of the positive electrode sheet is shown.

[0034] Reference numerals:

[0035] 100, substrate; 101, edge; 110, first surface; 111, first edge; 120, second surface; 121, second edge; 130, first end face; 200, pole ear; 300, active material layer; 400, first insulating layer; 500, second insulating layer; 301, edge of active material layer; 401, edge of first insulating layer; 402, first insulating layer on the side with pole ear. DETAILED DESCRIPTION

[0036] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention, so the present invention is not limited by the specific embodiments disclosed below.

[0037] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0038] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0039] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0040] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0041] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used herein are for illustrative purposes only and are not intended to be the only implementation method.

[0042] At present, lithium-ion batteries, as a green and environmentally friendly battery, have the advantages of high energy density, high operating voltage, high safety performance and long service life, and have been widely used in electronic devices such as mobile phones, digital cameras and electric vehicles. With the increasing demand for green energy and environmental protection, energy storage and utilization, lithium-ion batteries have become a bottleneck in solving the development of new energy.

[0043] There are many types of lithium-ion batteries, but wound lithium-ion batteries are widely used. Wound lithium-ion batteries include a shell, a battery cell and an electrolyte. The electrolyte is poured into the shell, and the battery cell is placed in the shell loaded with the electrolyte.

[0044] The battery cell includes stacked positive electrode sheets, separators and negative electrode sheets. Generally, the positive electrode sheets and negative electrode sheets need to be prepared first, and then the positive electrode sheets, separators and negative electrode sheets are wound and assembled into a battery cell, and then subsequent processing steps such as hot and cold pressing, formation, shaping, and capacity testing are carried out to form a finished lithium-ion battery.

[0045] Before winding, the positive electrode sheet and the negative electrode sheet need to be prepared. In the process of preparing the electrode sheet, generally, the active material layer 300 and the insulating material are first coated on the surface of the substrate 100, and then the edge of the substrate 100 is cut to form the electrode ear 200, and then the substrate 100 is cut into multiple electrode pieces by cutting.

[0046] Since the edges of the cut substrate 100 are not protected by insulating materials, during the winding and assembly process of the positive and negative electrode sheets, the burrs on the edges of the substrate 100 caused by cutting can easily cause short circuits, and the positive and negative electrode ears 200 can also easily overlap, resulting in internal short circuits, which reduces the qualified rate of the product and makes the lithium-ion battery very likely to catch fire or even explode due to internal short circuits during operation, posing a great safety hazard.

[0047] Based on the above problems, some solutions propose to use mechanical or manual burr removal. For example, the mechanical force of roller rolling is used to remove burrs. This mechanical burr removal method is difficult, and its burr removal effect is directly related to the material of the roller, the sharpness of the rolling cut and the surface quality, and the positioning accuracy is not high. In addition, this mechanical burr removal method is very easy to produce secondary burrs, which limits the burr removal effect and makes it difficult to achieve the desired effect. The roller is easy to wear after long-term use, and the cut is very easy to blunt, causing the entire burr removal process to fail. The loading method used by this burr removal and rolling machine is to manually place the pole pieces one by one in the fixture and start the burr removal and rolling machine, that is, put one piece after another after processing. This requires a dedicated employee to operate, and the burr removal effect and efficiency are directly related to the employee's operation and proficiency, which is time-consuming, labor-intensive and difficult to control. Traditional mechanical burr removal or manual burr removal cannot effectively remove micron-level burrs, and can only effectively remove millimeter-level burrs. Since the burrs cannot be completely removed, the problem of short circuit between the positive and negative electrodes during the electrode winding and assembly process cannot be effectively solved.

[0048] Based on the above problems, some solutions propose to apply insulating glue around the pole piece, that is, the insulating glue is applied during the coating process of the pole piece, and the pole piece is cut after the insulating glue is cured. However, the end face of the pole piece after cutting is not covered with insulating glue, and the end face burrs produced by cutting will still cause the positive and negative pole pieces to short-circuit during winding, causing a micro-short circuit of the battery; and there is no insulation protection on the pole ear, and there is still a risk of overlap between the positive and negative pole ears during the winding assembly process, which does not effectively solve the problem of easy short-circuit of the positive and negative pole pieces during the winding assembly process of the above-mentioned pole piece.

[0049] There are two types of burrs generated when the positive electrode of lithium-ion batteries is cut. One is the longitudinal burr, which is generally 7-15 microns in length, and the transverse burr is 20-60 microns in length. As the energy density requirements of lithium-ion batteries are getting higher and higher, the thickness of the diaphragm has gradually decreased from 32 microns to 16 microns. The longitudinal burr may penetrate the diaphragm, so the burr must be controlled to half the thickness of the diaphragm, that is, within 8 microns. However, the current slitting machines, whether they are top-level domestic equipment or imported slitting machines from Japan and South Korea, cannot meet this requirement 100%. The burrs contribute greatly to the short circuit explosion of the battery, and self-discharge is basically caused by burrs. Therefore, how to effectively avoid the internal short circuit of the wound lithium-ion battery caused by the end face burrs and the short circuit of the pole ear is an urgent problem to be solved.

[0050] Based on the above considerations, in order to solve the problem that the positive electrode sheet and the negative electrode sheet are very likely to overlap and short-circuit during the winding process, the inventors conducted in-depth research and designed a positive electrode sheet that can reduce the risk of short circuit with the negative electrode sheet.

[0051] like Figure 1 and Figure 2As shown, the positive electrode sheet in one embodiment includes a substrate 100, a tab 200, an active material layer 300, a first insulating layer 400 and a second insulating layer 500. The tab 200 is protruding from the edge 101 of the substrate 100, the surface of the substrate 100 partially covers the active material layer 300 and exposes the edge 101 of the substrate 100, the first insulating layer 400 is wrapped around the edge 101 of the substrate 100, and the second insulating layer 500 is disposed on the surface of the tab 200.

[0052] Through the above arrangement, in the positive electrode sheet, the edge 101 of the substrate 100 is wrapped with the first insulating layer 400, and the surface of the tab 200 is also provided with the second insulating layer 500, which can better ensure the insulation effectiveness of the edge 101 of the substrate 100 and the tab 200, avoid the burrs on the edge 101 of the substrate 100 being exposed and causing the positive and negative electrode sheets to short-circuit, and at the same time effectively reduce the risk of overlapping of the positive and negative tabs, thereby ensuring the safety of product use.

[0053] It should be noted that the substrate 100 of the positive electrode sheet here is a cut substrate 100, which can be wound with the negative electrode sheet after covering the first insulating layer 400 and the second insulating layer 500. The active material layer 300 is a substance containing active material and also has a certain insulating effect.

[0054] In a specific embodiment, the substrate 100 may be copper foil or aluminum foil. However, since the dyne value of aluminum foil is relatively low, the surface tension of the aqueous slurry coated on the surface of the aluminum foil is relatively large and the leveling property is relatively poor, so in this embodiment, aluminum foil may be preferably used as the substrate.

[0055] In this embodiment, the tab 200 and the substrate 100 are an integrally formed structure with good integrity and high mechanical strength, and the connection between the tab 200 and the substrate 100 is not easy to separate. In other embodiments, the tab 200 and the substrate 100 can also be a split structure, and the tab 100 is attached to the edge 101 of the substrate 100 by pressing.

[0056] In a specific embodiment, the active material layer 300 includes an active substance, a second binder, a conductive agent and a second solvent. The active slurry is obtained by mixing and stirring the above raw materials. The active slurry is then coated on the surface of the substrate 100 and dried to form the active material layer 300.

[0057] The active material includes at least one of lithium nickel cobalt manganese oxide, lithium iron phosphate, lithium nickel oxide, lithium nickel manganese oxide and lithium nickel iron manganese oxide. The active material is divided into positive electrode active material and negative electrode active material, that is, the positive electrode active material is used in the active material slurry of the positive electrode sheet, and the negative electrode active material is used in the active material slurry of the negative electrode sheet.

[0058] The preparation method of the active material slurry of the positive electrode sheet is specifically as follows: the active material, the binder (such as polyvinylidene fluoride), and the conductive carbon black are mixed, and the mixture containing the positive electrode active material is uniformly dispersed by high-speed stirring. In the mixture, the solid component contains 90wt% of lithium iron phosphate, 5wt% of polyvinylidene fluoride, and 5wt% of conductive carbon black. The mixture uses N-methylpyrrolidone as a solvent to prepare the positive electrode active material slurry, and the solid content in the slurry is 40wt%.

[0059] The preparation method of the active material slurry of the negative electrode sheet is specifically as follows: the active material, artificial graphite, a binder (such as styrene butadiene latex), sodium carboxymethyl cellulose and conductive carbon black are mixed, and the mixture containing the negative electrode active material is uniformly dispersed by high-speed stirring. In the mixture, the solid components include 95wt% of artificial graphite, 1.5wt% of sodium carboxymethyl cellulose, 1.5wt% of conductive carbon black, and 2wt% of styrene butadiene latex. Water is used as a solvent to prepare the negative electrode active material slurry, and the solid content in the slurry is 50wt%.

[0060] In a specific embodiment, the material of the first insulating layer 400 and the second insulating layer 500 can be polymer, inorganic oxide particles or a mixture of the two.

[0061] In this embodiment, the first insulating layer 400 is an insulating colloid, for example, the insulating colloid is at least one of oil-based epoxy resin, bismaleimide resin, water-based polyvinylidene fluoride, and polyimide. The second insulating layer 500 can be an insulating coating or material, for example, a metal oxide particle coating, the material composition of which specifically includes metal oxide particles, polyvinylidene fluoride and N-methylpyrrolidone, and the material of the metal oxide particles can be selected from aluminum oxide, titanium dioxide, zinc oxide, magnesium oxide and a combination thereof.

[0062] Specifically, in the coating process of the electrode, a relatively thin first insulating layer 400 is evenly coated on the edge 101 of the substrate 100 by a coating device. After drying in the oven of the coating machine, the coating is cured and tightly adhered to the edge 101 of the substrate 100, and partially covers the edge 101 of the substrate 100. In order to obtain a better first insulating layer 400, the content of solid matter in the first insulating layer 400 can be controlled within the range of 20 to 40%. Figure 1 As shown, the substrate 100 includes a first surface 110 , a second surface 120 and a first end surface 130 . The first end surface 130 is connected to the first surface 110 and the second surface 120 respectively, and the first surface 110 and the second surface 120 are disposed opposite to each other.

[0063] It should be noted here that the first surface 110 and the second surface 120 are disposed opposite to each other, which means that the first surface 110 and the second surface 120 are located on different sides of the substrate 100 .

[0064] In one embodiment, if Figure 1 As shown, the edge portion 101 of the substrate 100 includes a first end surface 130 .

[0065] In this embodiment, the first insulating layer 400 covers the first end surface 130, effectively preventing the first end surface 130 from being exposed to burrs generated by cutting the tab 200, thereby avoiding internal short circuit caused by overlapping of the positive and negative electrode sheets.

[0066] In another embodiment, Figure 1 As shown, the side portion 101 of the substrate 100 includes not only the first end surface 130 , but also the first edge 111 of the first surface 110 .

[0067] In this embodiment, the first surface 110 is at least partially covered with the active material layer 300 to leave the first edge 111, the first edge 111 is not covered with the active material layer 300, and the first insulating layer 400 covers the first edge 111. Through this arrangement, the first end surface 130 and the first edge 111 are effectively prevented from being exposed, so as to further effectively avoid the positive and negative electrode sheets from overlapping and causing an internal short circuit.

[0068] In another embodiment, Figure 1 As shown, the edge portion 101 of the substrate 100 includes not only the first end surface 130 , but also the second edge 121 of the second surface 120 .

[0069] In this embodiment, the second surface 120 is at least partially covered with the active material layer 300 to leave the second edge 121, the second edge 121 is not covered with the active material layer 300, and the first insulating layer 400 covers the second edge 121. Through this arrangement, the first end surface 130 and the second edge 121 are effectively prevented from being exposed, so as to further effectively avoid the overlap of the positive and negative electrode sheets and cause an internal short circuit.

[0070] In another embodiment, Figure 1 As shown, the edge portion 101 of the substrate 100 includes a first end surface 130 , a first edge 111 of the first surface 110 , and a second edge 121 of the second surface 120 .

[0071] In this embodiment, the second surface 120 is at least partially covered with the active material layer 300 to leave the second edge 121, the second edge 121 is not covered with the active material layer 300, and the first insulating layer 400 covers the second edge 121. At the same time, the first surface 110 is at least partially covered with the active material layer 300 to leave the first edge 111, the first edge 111 is not covered with the active material layer 300, and the first insulating layer 400 covers the first edge 111. Through this arrangement, the first end face 130, the first edge 111 and the second edge 121 are effectively prevented from being exposed, so as to further effectively avoid the overlap of the positive and negative electrode sheets and cause an internal short circuit.

[0072] The inventors have noticed that the substrate 100 is easily exposed at the junction of the active material layer 300 and the first insulating layer 400. Based on the above considerations, Figure 2 As shown, the edge 301 of the active material layer 300 is connected to the edge 401 of the first insulating layer 400 .

[0073] By connecting the edge 301 of the active material layer 300 with the edge 401 of the first insulating layer 400, as Figure 2 As shown, there is no gap between the active material layer 300 and the first insulating layer 400, the bonding force between the active material layer 300 and the first insulating layer 400 is increased, and the gap between the active material layer 300 and the first insulating layer 400 is prevented from exposing the substrate 100 and causing damage to the substrate 100.

[0074] For example, Figure 2 As shown, in the embodiment where the edge 101 of the substrate 100 includes the first end surface 130, the first insulating layer 400 is wrapped around the first end surface 130. One edge 401 of the first insulating layer 400 wrapped around the first end surface 130 is connected to the edge 301 of the active material layer 300 on the first surface 110, and the other edge 401 of the first insulating layer 400 wrapped around the first end surface 130 is connected to the edge 301 of the active material layer 300 on the second surface 120.

[0075] Combination Figure 2 As shown, in the embodiment where the edge 101 of the substrate 100 includes the first end surface 130 and the first edge 111 of the first surface 110, the first insulating layer 400 is wrapped around the first end surface 130 and the first edge 111 of the first surface 110. The edge 401 of the first insulating layer 400 wrapped around the first edge 111 is connected to the edge 301 of the active material layer 300 on the first surface 110, and the other edge 401 of the first insulating layer 400 wrapped around the first end surface 130 is connected to the edge 301 of the active material layer 300 on the second surface 120.

[0076] Combination Figure 2As shown, in an embodiment where the edge 101 of the substrate 100 includes the first end surface 130, the first edge 111 of the first surface 110, and the second edge 121 of the second surface 120, the first insulating layer 400 is wrapped around the first end surface 130, the first edge 111 of the first surface 110, and the second edge 121 of the second surface 120. The edge 401 of the first insulating layer 400 wrapped around the first edge 111 is connected to the edge 301 of the active material layer 300 on the first surface 110, and the edge 401 of the first insulating layer 400 wrapped around the second edge 121 is connected to the edge 301 of the active material layer 300 on the second surface 120.

[0077] Here, since in this embodiment, the first insulating layer 400 is an insulating colloid, the first insulating layer 400 needs to be dried and cured before it can be firmly adhered to the edge 101 of the substrate 100. After the first insulating layer 400 is coated on the edge 101 of the substrate 100, before the first insulating layer 400 is dried and cured, the edge 301 of the first insulating layer 400 can be made to penetrate into the edge 401 of the first insulating layer 400 to form an insulating colloid-active material mixed layer, so that the edge 301 of the active material layer 300 is connected to the edge 401 of the first insulating layer 400.

[0078] For example, Figure 2 As shown, in the embodiment where the edge 101 of the substrate 100 includes the first end surface 130, the first insulating layer 400 is wrapped around the first end surface 130. One edge 401 of the first insulating layer 400 wrapped around the first end surface 130 penetrates into the edge 301 of the active material layer 300 on the first surface 110, and the other edge 401 of the first insulating layer 400 wrapped around the first end surface 130 penetrates into the edge 301 of the active material layer 300 on the second surface 120 and is connected.

[0079] Combination Figure 2 As shown, in the embodiment where the edge 101 of the substrate 100 includes the first end surface 130 and the first edge 111 of the first surface 110, the first insulating layer 400 is wrapped around the first end surface 130 and the first edge 111 of the first surface 110. The edge 401 of the first insulating layer 400 wrapped around the first edge 111 penetrates to the edge 301 of the active material layer 300 on the first surface 110, and the edge 401 of the first insulating layer 400 wrapped around the first end surface 130 penetrates to the edge 301 of the active material layer 300 on the second surface 120.

[0080] Combination Figure 2As shown, in an embodiment where the edge 101 of the substrate 100 includes the first end surface 130, the first edge 111 of the first surface 110, and the second edge 121 of the second surface 120, the first insulating layer 400 is wrapped around the first end surface 130, the first edge 111 of the first surface 110, and the second edge 121 of the second surface 120. The edge 401 of the first insulating layer 400 wrapped around the first edge 111 penetrates to the edge 301 of the active material layer 300 of the first surface 110, and the edge 401 of the first insulating layer 400 wrapped around the second edge 121 penetrates to the edge 301 of the active material layer 300 of the second surface 120.

[0081] exist Figure 3 In one embodiment shown, the first insulating layer 400 is planar on a side 402 where the tab 200 is located.

[0082] In this embodiment, if Figure 3 As shown, the first insulating layer 400 can effectively cover the edge 101 of the substrate 100, effectively ensuring the insulation of the edge 101 of the substrate 100 and occupying a small space.

[0083] Since the first insulating layer 400 is wrapped around the edge 101 of the substrate 100, its withstand voltage performance needs to be improved to prevent damage to the substrate 100. Based on the above considerations, the inventors have conducted in-depth research and have found that Figure 4 In another embodiment shown, the first insulating layer 400 is curved on a side 402 where the tab 200 is located and is protruding toward a direction away from the edge 101 of the substrate 100 .

[0084] In this embodiment, if Figure 4 As shown, the first insulating layer 400 has a redundant portion relative to the edge 101 of the substrate 100 . The existence of the redundant portion can increase the pressure-bearing space, prevent the edge 101 of the substrate 100 from being damaged by external pressure, and help extend the service life of the substrate 100 .

[0085] In other embodiments, the first insulating layer 400 may also be in other irregular shapes on the side 402 where the tab 200 is located and may be protruding toward a direction away from the edge 101 of the substrate 100 .

[0086] The inventors noticed that Figure 2 As shown, the second insulating layer 500 covers the surface of the tab 200, and the first insulating layer 400 is wrapped around the edge 101 of the substrate 100. The first insulating layer 400 is easier to fall off than the second insulating layer 500. Based on the above considerations, in one embodiment, the viscosity of the first insulating layer 400 is greater than that of the second insulating layer 500.

[0087] In this embodiment, a first insulating layer 400 with stronger adhesion is used to enhance the adhesion between the first insulating layer 400 and the edge 101 of the substrate 100, thereby preventing the first insulating layer 400 from falling off the edge 101 of the substrate 100; at the same time, a second insulating layer 500 with less adhesion than the first insulating layer 400 is used to meet the use requirements of the second insulating layer 50 adhering to the surface of the tab 200, which is beneficial to reduce costs and simplify processes.

[0088] The inventors also noticed that Figure 2 As shown, the tab 200 is protruding from the edge 101 of the substrate 100, the edge 101 of the substrate 100 is wrapped with a first insulating layer 400, and a second insulating layer 500 is provided on the surface of the tab 200. If the first insulating layer 400 and the second insulating layer 500 overlap, the thickness of the positive electrode sheet will be too thick. Based on the above considerations, in one embodiment, Figure 2 As shown, the second insulating layer 500 is spaced apart from the edge 101 of the substrate 100 .

[0089] In this embodiment, if Figure 2 As shown, there is a gap between the second insulating layer 500 and the edge 101 of the substrate 100 to prevent the first insulating layer 400 and the second insulating layer 500 from overlapping each other, thereby preventing the positive electrode sheet from being too thick and affecting normal use of the positive electrode sheet.

[0090] In this embodiment, if Figure 2 As shown in FIG. 1 , the distance between the second insulating layer 500 and the edge 101 of the substrate 100 is at least 0.5 mm. Here, the distance refers to the distance between the second insulating layer 500 and the edge 101 of the substrate 100. Figure 2 The spacing distance in the Y direction shown can ensure the insulation effectiveness of the tab 200 and prevent the second insulating layer 500 from overlapping with the first insulating layer 400.

[0091] In this embodiment, if Figure 1 As shown, the width of the first insulating layer 400 is 0.5-2.5 mm, and the width of the second insulating layer 500 is 2.5-3 mm.

[0092] Here, length refers to the Figure 1 The dimensions in the X direction are shown, and the width direction refers to the Figure 1 The dimension in the Y direction is shown, and the thickness direction refers to the dimension along Figure 1 Dimensions in the Z direction are shown.

[0093] In other embodiments, the distance between the second insulating layer 500 and the edge 101 of the substrate 100 , the width of the first insulating layer 400 , and the width of the second insulating layer 500 may be adjusted according to actual conditions.

[0094] Please refer to Figure 5 , a manufacturing process of the positive electrode sheet in one embodiment comprises the following steps:

[0095] S10, coating the active material layer 300 and the second insulating layer 500 on the surface of the substrate 100 respectively, and exposing the edge 101 of the substrate 100;

[0096] S20, cutting and forming the tab 200 on the substrate 100 having the active material layer 300 and the second insulating layer 500;

[0097] S30 , coating the first insulating layer 400 on the edge 101 of the substrate 100 .

[0098] Through the above arrangement, the first insulating layer 400 is applied after the tab 200 is cut on the substrate 100, which can effectively prevent the first end surface 130 from being exposed to burrs caused by cutting and trimming the tab 200, thereby avoiding the positive and negative electrode sheets from overlapping and causing internal short circuits. The second insulating layer 500 is also provided on the surface of the tab 200, which can effectively reduce the risk of overlapping the positive tab 200 and the negative tab, and ensure the safety of the product.

[0099] like Figure 5 In the illustrated embodiment, step S11 is further included before step S10 , specifically: S11 , cutting the substrate 100 of the positive electrode sheet by cutting.

[0100] like Figure 5 In the illustrated embodiment, in step S10, coating the surface of the substrate 100 with the active material layer 300 and coating the surface of the substrate 100 with the second insulating layer 500 can be performed simultaneously, or coating the surface of the substrate 100 with the active material layer 300 and coating the surface of the substrate 100 with the second insulating layer 500 can also be performed in sequence.

[0101] In a specific embodiment, in the process of coating the second insulating layer 500 on the surface of the substrate 100, multiple substrates 100 can be placed in a processing station at one time, and then the second insulating layer 500 can be coated on the surfaces of the multiple substrates 100 at one time, and the subsequent processing steps can be performed after the second insulating layer 500 is dried on the surface of the substrate 100. Through this processing technology, the processing efficiency can be effectively improved.

[0102] In a specific embodiment, in the process of coating the active material layer 300 on the surface of the substrate 100, multiple substrates 100 can be placed in a processing station at one time, and then the active material layer 300 can be coated on the surface of multiple substrates 100 at one time, and the subsequent processing steps can be performed after the active material layer 300 is dried on the surface of the substrate 100. Through this processing technology, the processing efficiency can be effectively improved and the time required for processing can be shortened.

[0103] like Figure 5In the illustrated embodiment, in step S30 , when coating the first insulating layer 400 on the edge 101 of the substrate 100 , the connection between the substrate 100 and the tab 200 needs to be avoided.

[0104] In a specific implementation, the first insulating layer 400 can be coated by any one of brush coating, spray coating, dip coating, and extrusion coating.

[0105] In this embodiment, the first insulating layer 400 is an insulating glue, and subsequent processing steps need to be performed after the first insulating layer 400 is solidified on the edge 101 of the substrate 100 .

[0106] like Figure 5 In the illustrated embodiment, when the first insulating layer 400 is coated on the edge 101 of the substrate 100, the edge 301 of the active material layer 300 needs to be connected to the edge 401 of the first insulating layer 400. Through this operation method, there is no gap at the junction of the active material layer 300 and the first insulating layer 400, which increases the bonding force at the junction of the active material layer 300 and the first insulating layer 400, and prevents the substrate 100 from being exposed due to a gap at the junction of the active material layer 300 and the first insulating layer 400, causing damage to the substrate 100.

[0107] Since the first insulating layer 400 is an insulating colloid in this embodiment, the first insulating layer 400 needs to be dried and cured before it can be firmly adhered to the edge 101 of the substrate 100. After the first insulating layer 400 is coated on the edge 101 of the substrate 100, before the first insulating layer 400 is dried and cured, the edge 301 of the first insulating layer 400 can be made to penetrate into the edge 401 of the first insulating layer 400 to form an insulating colloid-active material mixed layer, so that the edge 301 of the active material layer 300 is connected to the edge 401 of the first insulating layer 400.

[0108] For example, Figure 2 As shown, in the embodiment where the edge 101 of the substrate 100 includes the first end surface 130, the first insulating layer 400 is wrapped around the first end surface 130. One edge 401 of the first insulating layer 400 wrapped around the first end surface 130 penetrates into the edge 301 of the active material layer 300 on the first surface 110, and the other edge 401 of the first insulating layer 400 wrapped around the first end surface 130 penetrates into the edge 301 of the active material layer 300 on the second surface 120 and is connected.

[0109] Combination Figure 2As shown, in the embodiment where the edge 101 of the substrate 100 includes the first end surface 130 and the first edge 111 of the first surface 110, the first insulating layer 400 is wrapped around the first end surface 130 and the first edge 111 of the first surface 110. The edge 401 of the first insulating layer 400 wrapped around the first edge 111 penetrates to the edge 301 of the active material layer 300 on the first surface 110, and the edge 401 of the first insulating layer 400 wrapped around the first end surface 130 penetrates to the edge 301 of the active material layer 300 on the second surface 120.

[0110] Combination Figure 2 As shown, in an embodiment where the edge 101 of the substrate 100 includes the first end surface 130, the first edge 111 of the first surface 110, and the second edge 121 of the second surface 120, the first insulating layer 400 is wrapped around the first end surface 130, the first edge 111 of the first surface 110, and the second edge 121 of the second surface 120. The edge 401 of the first insulating layer 400 wrapped around the first edge 111 penetrates to the edge 301 of the active material layer 300 of the first surface 110, and the edge 401 of the first insulating layer 400 wrapped around the second edge 121 penetrates to the edge 301 of the active material layer 300 of the second surface 120.

[0111] Please refer to Figure 1 In one embodiment, the lithium-ion battery includes the above-mentioned positive electrode sheet, negative electrode sheet and isolation membrane, and the isolation membrane is arranged between the positive electrode sheet and the negative electrode sheet.

[0112] It is understood that the separator is an insulating material. By providing the separator between the positive electrode sheet and the negative electrode sheet, a short circuit between the positive electrode sheet and the negative electrode sheet can be prevented.

[0113] In a specific implementation, the positive electrode sheet, the negative electrode sheet and the separator need to be wound.

[0114] In a specific embodiment, by arranging the above-mentioned positive electrode sheet, the width of the positive electrode sheet is made greater than that of the negative electrode sheet, and the positive electrode sheet has better insulation protection, which effectively prevents the positive electrode sheet and the negative electrode sheet from overlapping during winding and causing a short circuit.

[0115] Specifically, in the positive electrode sheet in the present embodiment, the edge 101 of the positive electrode sheet substrate 100 is wrapped with a first insulating layer 400, and the surface of the tab 200 of the positive electrode sheet is also provided with a second insulating layer 500, which can better ensure the insulation effectiveness of the edge 101 and the tab 200 of the positive electrode sheet, avoid the burrs on the edge 101 of the positive electrode sheet being exposed and causing the positive and negative electrode sheets to short-circuit, and at the same time effectively reduce the risk of overlap between the positive electrode tab 200 and the negative electrode tab, thereby ensuring the safety of product use.

[0116] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0117] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A positive electrode sheet, characterized in that: include: Base material; A tab protrudes from the edge of the substrate; An active material layer, wherein the surface portion of the substrate covers the active material layer, and the edge of the substrate is exposed; A first insulating layer wrapped around the edge of the substrate; as well as The second insulating layer is arranged on the surface of the tab.

2. The positive electrode sheet according to claim 1, characterized in that: The substrate includes a first surface, a second surface and a first end surface. The first end surface is connected between the first surface and the second surface. The first surface and the second surface are arranged opposite to each other. The edge of the substrate includes the first end surface.

3. The positive electrode sheet according to claim 2, characterized in that: The edge of the substrate further includes a first edge of the first surface and / or a second edge of the second surface.

4. The positive electrode sheet according to claim 1, characterized in that: An edge of the active material layer is connected to an edge of the first insulating layer.

5. The positive electrode sheet according to claim 1, characterized in that: The first insulating layer is planar on the side where the pole tab is located.

6. The positive electrode sheet according to claim 1, characterized in that: The first insulating layer is in a curved shape on the side where the pole ear is located and is protruded toward a direction away from the edge of the substrate.

7. The positive electrode sheet according to claim 1, characterized in that: The viscosity of the first insulating layer is greater than that of the second insulating layer.

8. The positive electrode sheet according to claim 1, characterized in that: The second insulating layer is spaced apart from the edge of the substrate.

9. A process for manufacturing a positive electrode sheet according to any one of claims 1 to 8, characterized in that: include: The active material layer and the second insulating layer are respectively coated on the surface of the substrate, and the edge of the substrate is exposed; Cutting and forming a tab on the substrate having the active material layer and the second insulating layer; A first insulating layer is coated on the edge of the substrate.

10. A lithium ion battery, characterized in that: include: The positive electrode sheet according to any one of claims 1 to 8; Negative electrode; The isolation film is arranged between the positive electrode sheet and the negative electrode sheet.

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