Pole piece and battery cell with same

Abstract

The utility model relates to the technical field of batteries, particularly provides a pole piece and a battery cell with the pole piece, and aims to solve the problem that in the prior art, the pole piece cannot be effectively fixed relative to a diaphragm, so that the pole piece and the diaphragm are easy to displace relative to each other, and the battery is short-circuited or even on fire. In order to achieve the purpose, a bonding layer is arranged at the edge of the pole piece, the area of the bonding layer is A1, the area of the pole piece is A2, and A1 / A2 is larger than or equal to 1.99% and smaller than or equal to 3.98%. According to the lithium ion battery, the bonding layer with a smaller area is arranged on the pole piece, and the diaphragm and the pole piece can be firmly bonded together through the bonding layer, so that the safety performance of the lithium ion battery is ensured, the electrical performance of the lithium ion battery is not influenced, the operation is simple and convenient, and the production efficiency can be effectively improved.

Description

Technical Field

[0001] The utility model relates to the technical field of batteries, and specifically provides a pole piece and a battery core having the pole piece. Background Art

[0002] Lithium-ion batteries are widely used due to their high energy density, high output voltage, and high output power. Their application areas have spread across consumer electronics, new energy vehicles, and energy storage. Lithium-ion battery cells are divided into wound cells and laminated cells according to different processing techniques. Laminated cells are widely used due to their high energy density, flexible size, and simple manufacturing process.

[0003] However, for stacked cells, since the diaphragm, positive electrode and negative electrode are simply stacked together, the electrode is very likely to slide and shift when squeezed or vibrated, causing misalignment between the electrode and the diaphragm. During the charging and discharging process of lithium-ion batteries, the diaphragm shrinks and the electrode shifts, which can easily lead to the diaphragm not being able to completely cover the electrode, resulting in direct contact between adjacent electrode pieces and short circuits, causing the risk of lithium-ion batteries catching fire or even exploding, posing a greater safety risk.

[0004] Accordingly, the art needs a new technical solution to solve the above problems. Utility Model Content

[0005] The utility model aims to solve the above technical problem, that is, to solve the problem in the prior art that displacement between the pole piece and the diaphragm causes a battery short circuit or even a fire.

[0006] In the first aspect, the utility model provides a pole piece, the pole piece includes a base layer and an adhesive layer, the adhesive layer is arranged at the edge of the base layer, and the area of ​​the adhesive layer is A 1 , the area of ​​the base layer is A 2 , where 1.99%≤A 1 / A 2 ≤3.98%.

[0007] By setting an adhesive layer at the edge of the base layer, the diaphragm and the pole piece can be firmly bonded together through the adhesive layer. In this way, even if extrusion or vibration occurs, the pole piece and the diaphragm can be firmly bonded together, and there will be no relative displacement between the pole piece and the diaphragm, which can effectively prevent the pole piece from moving. Even if the diaphragm undergoes thermal contraction, there will be no problem of short circuit or even fire caused by direct contact of the pole piece, thereby effectively improving the safety performance of the lithium-ion battery. In addition, the area ratio range of the adhesive layer and the base layer is limited. On the one hand, it can prevent the area of ​​the adhesive layer from being too large to affect the passage of lithium ions, thereby affecting the electrical performance of the battery and increasing the cost. On the other hand, it can prevent the area of ​​the adhesive layer from being too small, resulting in poor adhesion between the pole piece and the diaphragm, and the pole piece and the diaphragm are easily separated, and then the pole piece and the diaphragm are easily misaligned, resulting in short circuits or even fires. The above-mentioned ratio range can maximize the electrical performance and optimize the cost on the basis of ensuring the stability of the structure.

[0008] In an optional technical solution of the above-mentioned pole piece, the pole piece further includes an active material layer, and the active material layer is arranged between the base layer and the bonding layer.

[0009] By arranging the adhesive layer on the surface of the active material layer away from the base layer, on the one hand, the area of ​​the active material layer can be avoided from being reduced, thereby improving the electrical performance of the battery. On the other hand, the thickness of the adhesive layer is thinner, which can reduce the material used in the adhesive layer to reduce costs. At the same time, it can fully contact with the diaphragm to ensure the bonding force between the electrode and the diaphragm, effectively preventing short circuits caused by misalignment of the electrode and the diaphragm.

[0010] In an optional technical solution of the above-mentioned pole piece, two adhesive layers are provided and are located at both ends of the active material layer.

[0011] In the optional technical solution of the above-mentioned pole piece, the thickness of the bonding layer is H 1 , where 5μm≤H 1 ≤10μm; and / or, the width of the adhesive layer is W 1 , where 2mm≤W 1 ≤25mm.

[0012] In the optional technical solution of the above-mentioned pole piece, 5mm≤H 1 ≤10mm.

[0013] In an optional technical solution of the above-mentioned pole piece, the pole piece further includes an active material layer arranged on the base layer, and the adhesive layer is arranged on the base layer and is located on one side of the active material layer.

[0014] By arranging the adhesive layer on the base layer and being located on at least one side of the active material layer along the first direction, on the one hand, the adhesive layer can be prevented from blocking the active material layer, thereby not affecting the passage of lithium ions, thereby ensuring the electrical performance of the battery; on the other hand, the base layer and the diaphragm can be bonded and fixed, making them more stable and having higher bonding strength.

[0015] In the optional technical solution of the above-mentioned electrode, the thickness of the bonding layer is greater than the thickness of the active material layer, and the thickness of the bonding layer is H 2 , where 50μm≤H 2 ≤80μm.

[0016] In the optional technical solution of the above-mentioned pole piece, the width of the bonding layer is W 2 , where 2mm≤W 2 ≤25mm.

[0017] In the optional technical solution of the above-mentioned pole piece, 5mm≤W 2 ≤10mm.

[0018] In a second aspect, the utility model further provides a battery cell, which comprises a diaphragm and a pole piece as described in any of the above schemes, wherein the adhesive layer is fixedly connected to the diaphragm.

[0019] It should be noted that the battery cell has all the technical effects of the pole piece described in any of the aforementioned schemes, which will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings, in which:

[0021] Figure 1 It is a cross-sectional schematic diagram of the pole piece and the diaphragm of the first embodiment of the utility model;

[0022] Figure 2 It is a cross-sectional schematic diagram of a pole piece and a diaphragm in the second embodiment of the utility model;

[0023] Figure 3 It is a top view of the pole piece of the first embodiment of the utility model;

[0024] Figure 4 It is a structural diagram of the base layer and the tab of the first embodiment of the utility model.

[0025] List of reference numerals:

[0026] 1. diaphragm; 2. pole piece; 21. base layer; 22. active material layer; 23. pole ear; 3. bonding layer; x, first direction; y, second direction; z, third direction. DETAILED DESCRIPTION

[0027] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the protection scope of the present invention.

[0028] It should be noted that in the description of the present invention, the terms "left" and "right" and other terms indicating directions or positional relationships are based on the directions or positional relationships shown in the drawings, which are only for the convenience of description, and do not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0029] In addition, it should be noted that in the description of this application, unless otherwise clearly specified and limited, the term "connection" 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 it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For those skilled in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0030] The laminated battery cell usually includes a positive electrode sheet, a negative electrode sheet and a separator. The positive electrode sheet and the negative electrode sheet are arranged alternately, and a separator is arranged between each positive electrode sheet and the negative electrode sheet. In order to prevent lithium precipitation, the size of the negative electrode sheet is usually larger than the size of the positive electrode sheet. In order to prevent the positive electrode sheet and the negative electrode sheet from contacting each other when the separator undergoes thermal contraction, the size of the separator is usually larger than the size of the negative electrode sheet. Based on this, during the operation of the lithium-ion battery, if the positive electrode sheet and the negative electrode sheet are misaligned and the separator undergoes thermal contraction, the positive electrode sheet and the negative electrode sheet will easily contact each other and short-circuit, thereby causing the battery to catch fire or even explode. The pole piece of the utility model is provided with an adhesive layer thereon, and the pole piece and the separator are firmly bonded together by the adhesive layer, thereby solving the problem of easy misalignment between the pole piece and the separator, and between the pole pieces, thereby avoiding the situation of internal short circuit or even fire in the battery, and effectively improving the safety performance of the lithium-ion battery.

[0031] Refer to the following Figures 1 to 4 To illustrate possible implementation methods of the pole piece and the battery cell of the utility model.

[0032] like Figures 1 to 4As shown, the battery cell includes a diaphragm 1 and a pole piece 2, and the pole piece 2 includes a base layer 21. An adhesive layer 3 is provided on at least part of the edge of the base layer 21, and the diaphragm 1 and the base layer 21 can be bonded together through the adhesive layer 3. In this case, even if the battery cell is squeezed or vibrated, the pole piece 2 and the diaphragm 1 can be firmly bonded together, and there will be no relative displacement between the pole piece 2 and the diaphragm 1, or between the pole pieces 2. Moreover, since the edges of the diaphragm 1 and the pole piece 2 are bonded together, even if the diaphragm 1 undergoes thermal shrinkage, the diaphragm 1 will be located between two adjacent pole pieces 2, thereby effectively avoiding the occurrence of short circuits or even fires caused by direct contact between the positive and negative pole pieces. The adhesive layer 3 of the utility model is only provided at the edge of the base layer 21, wherein the area of ​​the adhesive layer is A. 1 , the area of ​​the base layer 21 is A 2 , A 1 With A 2 The ratio range is 1.99% to 3.98%. It can be seen that the bonding layer 3 only occupies a very small area of ​​the pole piece 2, and basically will not affect the lithium ion conduction path during the operation of the lithium ion battery, that is, it will basically not block the lithium ion conduction path and will not affect the dynamic performance of the lithium ion battery. In addition, since the amount of glue used is small, the production cost of the lithium ion battery will not be increased due to the use of glue. The pole piece 2 and the diaphragm 1 are firmly bonded together directly by bonding, which is simple to operate, simplifies the production process, and improves production efficiency. At the same time, limiting the area within the above-mentioned ratio range can not only achieve a stable bonding and fixation between the pole piece 2 and the diaphragm 1, prevent it from detaching and causing short circuits, but also reduce the area occupied by the bonding layer 3, and prevent the bonding layer 3 from being too large, which will cause the electrical performance of the battery to decrease. Therefore, the above-mentioned range can achieve the maximization of the battery electrical performance on the basis of ensuring structural stability.

[0033] It should be noted that the electrode 2 includes an electrode ear 23 disposed at one end of the base layer 21. Figures 1 to 4 As shown, in this embodiment, the base layer 21 is a rectangle. In other embodiments, the base layer 21 may also be other geometric shapes, which are not specifically limited here. Further, the area of ​​the base layer 21 is specifically the area of ​​the plane where the base layer 21 is located in the first direction x and the second direction y, such as Figure 4 Further, the area A of the adhesive layer 3 1 is the area of ​​the adhesive layer 3 in the plane where the first direction x and the second direction y are located, such as Figure 3 shown.

[0034] It should be noted that the electrode sheet 2 provided with the adhesive layer 3 may be a positive electrode sheet or a negative electrode sheet, that is, the adhesive layer 3 may be provided only on the positive electrode sheet or only on the negative electrode sheet.

[0035] Preferably, at least part of the edges of the positive and negative electrodes are provided with an adhesive layer 3, so that the battery cells can be arranged alternately in the manner of diaphragm 1, negative electrode, diaphragm 1, positive electrode, diaphragm 1, negative electrode, diaphragm 1, etc. After being stacked, regardless of whether extrusion or vibration occurs, each diaphragm 1, negative electrode and positive electrode can maintain its initial position, thereby better avoiding the occurrence of internal short circuit or even fire in the lithium-ion battery due to misalignment, thermal shrinkage and the like, and effectively improving the safety performance of the lithium-ion battery. At the same time, because the adhesive layer 3 is only provided at the edges of the positive and negative electrodes, it only occupies a very small part of the positive and negative electrodes, saving production costs while not affecting the dynamic performance of the lithium-ion battery.

[0036] For the convenience of explanation, unless it is specifically stated that it is a positive electrode sheet or a negative electrode sheet, other contents related to the electrode sheet 2 are applicable to both positive electrode sheets and negative electrode sheets.

[0037] like Figure 1 and Figure 2 As shown, the electrode sheet 2 is roughly rectangular, and includes a base layer 21 and an active material layer 22 disposed on the base layer. The base layer 21 is aluminum foil or copper foil. For example, the base layer 21 of the positive electrode sheet is aluminum foil, and the base layer 21 of the negative electrode sheet is copper foil. The active material layer 22 is also roughly rectangular, and is located in the middle area of ​​the base layer 21. Its size along the second direction y is roughly the same as the size of the base layer 21 in the second direction y. The size of the active material layer 21 along the first direction x is less than or equal to the size of the base layer 21 along the first direction x. When the size of the active material layer 21 in the first direction x is less than the size of the base layer 21 in the first direction x, the base layer 21 includes at least two rectangular block areas located on the left and right sides of the active material layer 22 in addition to the active material layer 22.

[0038] It should be noted that the dimensions of the active material layer 22 along the first direction x and the second direction y may be smaller than the dimensions of the base layer 21 along the first direction x and the second direction y, that is, the width and length of the active material layer 22 are smaller than the width and length of the base layer 21. In this case, the area on the base layer 21 except the active material layer 22 is roughly a U-shaped area distributed along the circumference of the active material layer 22.

[0039] In this embodiment, the first direction x is approximately Figure 1 and Figure 2 The horizontal left and right direction shown in FIG, that is, the length direction of the pole piece 2, and the second direction y is approximately Figure 3 and Figure 4 The left and right directions shown in FIG. 1 are the width directions of the pole piece 2, and the third direction z is approximately Figure 1 and Figure 2 The up-down direction in the figure is the thickness direction of the pole piece 2.

[0040] The following describes possible implementations of the adhesive layer 3 of the present application in combination with Embodiment 1 and Embodiment 2.

[0041] Embodiment 1:

[0042] like Figure 1 , 3 and 4, and in accordance with Figure 1 In the orientation shown, the portion of the base layer 21 located on the left side of the active material layer 22 is used to form the tab 23. Specifically, after the battery cell is assembled, the portion of the base layer 21 located on the left side of the active material layer 22 stacked together can form the tab 23 by kneading or other methods. The adhesive layer 3 is disposed on the surface of the active material layer 22 away from the base layer 21, and in the first direction x, the adhesive layer 3 is located at the edge of the active material layer 22 close to the tab side (approximately Figure 1 The left end of the active material layer 22 in the middle) and the edge of the side opposite to the electrode ear side (roughly Figure 1 In other words, the adhesive layer 3 is arranged at the left and right ends of the active material layer 22 along the first direction of the active material layer 22. In this way, when assembling the battery cell, the diaphragm 1 is covered on the surface of the pole piece 2, and the diaphragm 1 and the pole piece 2 can be bonded together through the adhesive layer 3 arranged on the left and right ends of the active material layer 22 on the pole piece 2, which is easy to operate and has a high production effect. In the assembled battery cell, each pole piece 2 and the diaphragm 1 are neatly stacked in one direction, and will not be misaligned with each other when subjected to pressure or vibration, thereby improving the safety performance of the lithium-ion battery.

[0043] It should be noted that the adhesive layer 3 may be disposed only at the left end of the active material layer 22 in the first direction x, or only at the right end of the active material layer 22 in the first direction x. Obviously, the adhesive layer may also be disposed at the left end and / or the right end of the active material layer 22 in the second direction y.

[0044] In a possible implementation manner, the thickness of the adhesive layer 3 is H 1 , where 5μm≤H 1 ≤10μm.

[0045] It should be noted that when the adhesive layer 3 is entirely disposed on the active material layer 22, in order to prevent the improvement of the space utilization rate and the bonding strength between the diaphragm 1 and the pole piece 2, the thickness of the adhesive layer 3 needs to be further limited. By limiting the above range, the adhesive layer 3 can not only firmly bond the diaphragm 1 and the pole piece 2 together, and has a bonding function, but also will not block the lithium ion conduction path, thereby ensuring the dynamic performance of the lithium ion battery. At the same time, it will not increase the thickness of the battery cell too much, and will not increase the space required for the battery cell, which can effectively improve the space utilization rate and energy density of the lithium ion battery. Through such a setting method, it is possible to better take into account the bonding function and the electrical performance of the lithium ion battery.

[0046] In a possible implementation manner, the size of the adhesive layer 3 along the first direction is W. 1 , the W 1 The range is 2mm≤W 1 ≤25mm. Within this width range, the bonding surface between the diaphragm 1 and the electrode 2 is large enough to better bond the two together. The bonding force between the two will not be insufficient due to the bonding surface being too small, nor will the bonding surface be too large to cover too many active material layers 22, thereby affecting the electrical performance of the lithium-ion battery.

[0047] Preferably, the dimension W of the adhesive layer 3 along the first direction is 1 The range is 5mm≤W 1 ≤10 mm, the adhesive layer 3 within this range can better balance the adhesive function and the battery performance of the lithium-ion battery.

[0048] It should be noted that the thickness H of the adhesive layer 3 is 1 Roughly Figure 1 The dimension in the third direction z.

[0049] In a possible implementation, the adhesive layer 3 is formed by coating the adhesive on the surface of the active material layer 22 by spraying, and the shape of the adhesive layer 3 can be a rectangle distributed along the width direction of the active material layer 22, or a rectangle distributed along the length direction of the active material layer 22. The length direction of the active material layer 22 is approximately Figure 1 In the horizontal direction shown in FIG, the width direction of the active material layer 22 is approximately Figure 1 The direction shown in FIG. 3 is perpendicular to the paper surface. Obviously, the shape of the adhesive layer 3 can also be a square, a parallelogram, an irregular shape or other possible shapes.

[0050] It should be noted that the adhesive layer 3 can also be formed by coating the adhesive on the surface of the active material layer 22 by dispensing or extrusion coating.

[0051] The glue can be one of the commonly used oil-soluble polyvinylidene fluoride, oil-soluble polyethylene oxide, oil-soluble polyurethane, water-based polyvinylidene fluoride, styrene-butadiene rubber, polyacrylic acid, and polyvinyl alcohol.

[0052] Preferably, when the electrode 2 is a positive electrode, the glue is preferably oil-soluble polyvinylidene fluoride.

[0053] Preferably, when the electrode sheet 2 is a negative electrode sheet, the glue is preferably styrene-butadiene rubber.

[0054] Through the above-mentioned setting method, the adhesive layer 3 formed by coating the glue having the above-mentioned components on the active material layer 22 of the positive / negative electrode sheet has a good bonding effect. At the same time, the glue having this component will not affect the effective components in the active material layer 22 on the positive / negative electrode sheet, that is, it will not affect the battery performance of the lithium-ion battery.

[0055] It should be noted that the glue can obviously also be other components, for example, a mixture of polyvinylidene fluoride, polyacrylamide, polyacrylic acid, one of carboxymethyl cellulose, styrene-butadiene rubber, polyurethane, nitrocellulose, one of polyvinyl acetate, and boehmite, etc. Without departing from the basic principles of the present application, those skilled in the art can flexibly select the specific composition of the above-mentioned glue according to the specific application scenario, as long as it can bond the diaphragm 1 and the electrode 2 together.

[0056] Based on the structure in the above-mentioned embodiment 1, further description will be given below in combination with the following specific examples and comparative example 1.

[0057] Embodiment 101:

[0058] The thickness H of each adhesive layer 3 1 5μm, width W 1 It is 8mm.

[0059] Embodiment 102:

[0060] The thickness H of each adhesive layer 3 1 10μm, width W 1 It is 8mm.

[0061] Embodiment 103:

[0062] The thickness H of each adhesive layer 3 1 9μm, width W 1 is 25mm.

[0063] Embodiment 104:

[0064] The thickness H of each adhesive layer 3 1 9μm, width W 1 is 5mm.

[0065] Embodiment 105:

[0066] The thickness H of each adhesive layer 3 1 9μm, width W 1 is 10mm.

[0067] Embodiment 106:

[0068] The thickness H of each adhesive layer 3 1 10μm, width W 1 is 10mm.

[0069] Embodiment 2:

[0070] like Figure 2 As shown, in the first direction x, the base layer 21 is located on one side of the active material layer 22 (approximately Figure 2 The base layer 21 shown in the figure is located on the left side of the active material layer 22) and has a tab 23, which means that after the battery cell is assembled, the tabs 23 stacked together can form the tabs of the battery cell by kneading or the like. The adhesive layer 3 is arranged on the base layer 21 and on the side of the base layer 21 opposite to the tab 23 (approximately Figure 2 The edge of the active material layer 22 is on the right side, and the thickness H of the adhesive layer 3 is 2 Greater than the thickness of the active material layer 22. In this way, when assembling the battery cell, the diaphragm 1 is covered on the surface of the pole piece 2, and the diaphragm 1 and the pole piece 2 can be bonded together by the adhesive layer 3 arranged on the pole piece 2 in the first direction x, where the base layer 21 is located on the left side of the active material layer 22 and the base layer 21 is located on the right side of the active material layer 22. The operation is simple and the production effect is high. In the assembled battery cell, each pole piece 2 and the diaphragm 1 are neatly stacked in one direction, and will not be misaligned with each other when subjected to pressure or vibration, thereby improving the safety performance of the lithium-ion battery. Moreover, under this arrangement, the adhesive layer 3 is arranged on the base layer 21 except for the area where the active material layer 22 is arranged, and the active material layer 22 is not arranged therein, that is, the adhesive layer 3 is completely separated from the active material layer 22, and the arrangement of the adhesive layer 3 will not affect the lithium ion conduction path at all, and will not affect the dynamic performance of the lithium-ion battery at all. That is, by arranging the adhesive layer 3 on the left side of the active material layer 22 on the base layer 21 in the first direction x and on the right side of the active material layer 22, the adhesion between the electrode 2 and the diaphragm 1 can be ensured while avoiding affecting the electrical performance of the lithium-ion battery.

[0071] It should be noted that, in the first direction x, the adhesive layer 3 arranged on the left side can cover the entire area of ​​the base layer 21 located on the left side of the active material layer 22, and the adhesive layer 3 arranged on the right side of the active material layer 22 can also cover the entire area, or can be arranged only at a position away from the active material layer 22 or close to the active material layer 22. Obviously, the adhesive layer 3 can also be arranged only on the left side of the active material layer 22. When the base layer 21 has a U-shaped area without the active material layer 22, the adhesive layer 3 can also be arranged in the area on the base layer 21 located on one side or both sides of the active material layer 22 in the second direction y.

[0072] In a possible implementation manner, the thickness of the adhesive layer 3 is H 2 , where 50μm≤H 2 ≤80μm. Within this thickness range, the thickness of the bonding layer 3 is greater than the thickness of the active material layer 22. In this case, when assembling the battery cell, the diaphragm 1 is covered on the surface of the electrode 2, and then the diaphragm 1 and the electrode 2 can be firmly bonded together through the bonding layer 3.

[0073] In a possible implementation manner, the size of the adhesive layer 3 in the first direction x is W. 2 , the W 2 The range is 2mm≤W 2 ≤25mm. Within this width range, the bonding surface between the diaphragm 1 and the pole piece 2 is large enough to better bond the two together. The bonding force between the two will not be insufficient due to the bonding surface being too small, thereby ensuring the bonding between the diaphragm 1 and the pole piece 2.

[0074] Preferably, W 2 The range is 5mm≤W 2 ≤10 mm. The adhesive layer 3 within this range can better take into account the setting of the adhesive layer 3 and the bonding between the diaphragm 1 and the pole piece 2.

[0075] It should be noted that the thickness H of the adhesive layer 3 is 2 Roughly Figure 2 The dimension of the middle adhesive layer 3 along the vertical direction, ie, the third direction z.

[0076] In a possible implementation, the adhesive layer 3 is formed by coating the adhesive on the base layer 21 by extrusion coating, and the shape of the adhesive layer 3 can be a rectangle distributed along the width direction of the base layer 21, or a rectangle distributed along the length direction of the base layer 21. Obviously, the shape of the adhesive layer 3 can also be other possible shapes such as a square, a parallelogram, an irregular shape, etc.

[0077] It should be noted that the adhesive layer 3 can also be formed by coating glue on the base layer 21 by dispensing or spraying.

[0078] The glue solution includes an adhesive and boehmite, wherein the adhesive is one of the currently commonly used polyvinylidene fluoride, polyacrylamide, polyacrylic acid, carboxymethyl cellulose, styrene-butadiene rubber, polyurethane, nitrocellulose, polyvinyl acetate, and polyolefin.

[0079] Preferably, when the electrode sheet 2 is a positive electrode sheet, the adhesive is polyacrylic acid.

[0080] Preferably, when the electrode sheet 2 is a negative electrode sheet, the adhesive is polyolefin.

[0081] Through the above-mentioned setting method, the glue having the above-mentioned components can quickly form an adhesive layer 3 with sufficient thickness and strong adhesion at the edge of the base layer 21 of the positive / negative electrode, which can better bond the diaphragm 1 and the electrode 2 together and has a better bonding effect.

[0082] It should be noted that the glue can obviously also be one of an oil-soluble polyvinylidene fluoride solution, an oil-soluble polyethylene oxide solution, an oil-soluble polyurethane solution, an aqueous polyvinylidene fluoride emulsion, a styrene-butadiene rubber emulsion, a polyacrylic acid aqueous solution, and a polyvinyl alcohol aqueous solution. Without departing from the basic principles of the present application, those skilled in the art can flexibly select the specific composition of the above-mentioned glue according to the specific application scenario, as long as it can bond the diaphragm 1 and the pole piece 2 together.

[0083] It should be noted that the adhesive layer 3 may also be partially disposed on the edge of the active material layer 22 and partially disposed on the edge of other regions on the base layer 21 except the active material layer 22. Of course, it is also possible that the adhesive layer 3 is disposed on the edge of the active material layer 22 and the edge of other regions on the base layer 21 except the active material layer 22. Without departing from the basic principles of the present application, those skilled in the art may flexibly select the specific manner of the adhesive layer 3 according to the specific application scenario, as long as the diaphragm 1 and the pole piece 2 can be bonded together by the adhesive layer 3 disposed on the edge of the pole piece 2.

[0084] Based on the structure in the above-mentioned embodiment 2, further description will be given below in combination with the following specific examples.

[0085] Embodiment 201:

[0086] The thickness H of each adhesive layer 3 2 40μm, width W 2 It is 6mm.

[0087] Embodiment 202:

[0088] The thickness H of each adhesive layer 3 2 50μm, width W 2 It is 6mm.

[0089] Embodiment 203:

[0090] The thickness H of each adhesive layer 3 2 50μm, width W 2 It is 8mm.

[0091] Embodiment 204:

[0092] The thickness H of each adhesive layer 3 2 50μm, width W 2 is 2mm.

[0093] Embodiment 205:

[0094] The thickness H of each adhesive layer 3 2 50μm, width W 2 is 5mm.

[0095] In summary, the utility model provides an adhesive layer at the edge of the positive electrode sheet and / or the negative electrode sheet, and the positive electrode sheet and the negative electrode sheet can be firmly bonded together through the adhesive layer, effectively avoiding the occurrence of short circuit or even fire. In addition, the adhesive layer in the utility model will not increase the DC internal resistance of the battery cell, thereby better ensuring the power characteristics of the lithium-ion battery.

[0096] Of course, the above-mentioned replaceable implementations, as well as the replaceable implementations and the preferred implementations, can be used in a cross-coordinated manner to combine new implementations to suit more specific application scenarios.

[0097] In addition, those skilled in the art will appreciate that, although some embodiments described herein include certain features included in other embodiments but not other features, the combination of features of different embodiments is meant to be within the scope of the present invention and form different embodiments. For example, in the claims of the present invention, any one of the claimed embodiments may be used in any combination.

[0098] So far, the technical solution of the present invention has been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

Claims

1. A pole piece, characterized in that: The pole piece includes a base layer and an adhesive layer, wherein the adhesive layer is arranged at the edge of the base layer, the area of ​​the adhesive layer is A1, and the area of ​​the base layer is A2, wherein 1.99%≤A1 / A2≤3.98%.

2. The pole piece according to claim 1, characterized in that: The pole piece further includes an active material layer, and the active material layer is arranged between the base layer and the adhesive layer.

3. The pole piece according to claim 2, characterized in that: The adhesive layers are provided in two and are located at two ends of the active material layer.

4. The pole piece according to claim 2, characterized in that: The thickness of the adhesive layer is H1, wherein 5 μm≤H1≤10 μm; and / or, The width of the adhesive layer is W1, wherein 2mm≤W1≤25mm.

5. The pole piece according to claim 4, characterized in that: in, 5mm≤W1≤10mm.

6. The pole piece according to claim 1, characterized in that: The pole piece further includes an active material layer disposed on the base layer, and the adhesive layer is disposed on the base layer and is located on one side of the active material layer.

7. The pole piece according to claim 6, characterized in that: The thickness of the adhesive layer is greater than the thickness of the active material layer, and the thickness of the adhesive layer is H2, wherein 50 μm≤H2≤80 μm.

8. The pole piece according to claim 7, characterized in that: The width of the adhesive layer is W2, wherein 2mm≤W2≤25mm.

9. The pole piece according to claim 8, characterized in that: in, 5mm≤W2≤10mm.

10. A battery cell, characterized in that: The battery cell comprises a diaphragm and a pole piece as claimed in any one of claims 1 to 9, and the adhesive layer is fixedly connected to the diaphragm.

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