Pole piece

Abstract

The utility model relates to the technical field of new energy, particularly provides a pole piece, and aims to solve the problems that a bonding layer on the conventional pole piece is high in cost, large in size and instable in bonding with a diaphragm. Therefore, the pole piece comprises a current collector, an active material layer arranged on the current collector and a first bonding layer, the first bonding layer is located on one side of the active material layer and comprises a first part and a second part, the first part is located between the active material layer and the second part, and the second part is located between the active material layer and the second part. The thickness of the second part is smaller than that of the first part. The thickness of the second part is smaller than that of the first part, so that the bending resistance of the region of the current collector coated on the second part is reduced, and the current collector is bent, so that the first bonding layer and the diaphragm are stably bonded and fixed, the structural stability is enhanced, the material consumption of the first bonding layer can be reduced, and the product cost is reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of new energy, and specifically provides a pole piece. Background Art

[0002] With the development of society and the enhancement of environmental awareness, people's demand for new energy is increasing, which has led to the rapid development of lithium battery technology.

[0003] Lithium batteries usually include a positive electrode sheet, a separator and a negative electrode sheet arranged in sequence. During the manufacturing or use of lithium batteries, the separator and the positive electrode sheet or the negative electrode sheet are easy to move relative to each other, causing the positive electrode sheet and the negative electrode sheet to short-circuit after misaligned contact, affecting the safety of battery use. In order to improve the safety of the battery, a glue layer is usually set on one side of the active material layer of the positive electrode sheet or the negative electrode sheet, and then the glue layer is bonded to the separator to achieve the position fixation of the two. However, the thickness of the existing glue layer close to the active material layer is the same as that of the part away from the active material layer, which not only causes the part of the electrode sheet away from the active material layer (usually the edge of the electrode sheet) to have a greater bending resistance, making it unable to bend smoothly toward the separator to affect the bonding and fixing effect with the separator, but also leads to an increase in the material used for the glue layer, increasing the product cost.

[0004] Therefore, this field 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 that the adhesive layer on the existing pole piece is high in cost, large in volume and unstable in bonding with the diaphragm.

[0006] In a first aspect, the utility model provides a pole piece, comprising a current collector, an active material layer arranged on the current collector, and a first adhesive layer, wherein the first adhesive layer is located on one side of the active material layer, the first adhesive layer comprises a first part and a second part, the first part is located between the active material layer and the second part, and the thickness of the second part is less than the thickness of the first part.

[0007] In the case of adopting the above technical solution, the thickness of the second part is smaller than the thickness of the first part, so that the bending resistance of the area coated with the second part on the current collector is reduced, and then the current collector can be bent smoothly so that the first bonding layer and the diaphragm are firmly bonded and fixed, thereby enhancing the structural stability. In addition, the material used in the second part can be reduced, and the product cost can be reduced. At the same time, the burrs of the remaining pole pieces can contact the first bonding layer after piercing the diaphragm to prevent the burrs from contacting the current collector to cause a short circuit, thereby causing unnecessary safety hazards.

[0008] In the preferred technical solution of the above-mentioned pole piece, the second part includes a first surface, and the first surface is a curved surface.

[0009] In a preferred technical solution of the above pole piece, the thickness of the second portion gradually decreases along the first direction.

[0010] In the preferred technical solution of the above-mentioned pole piece, the thickness of the first part is t 1 , where 10 μm ≤ t 1 ≤80 microns; and / or, the thickness of the second portion is t 2 , where 5 microns ≤ t 2 ≤50 microns.

[0011] In the preferred technical solution of the above-mentioned pole piece, the width of the first part is w 1 , where 1 mm ≤ w 1 ≤20 mm; and / or, the width of the second portion is w 2 , where 0.1 mm ≤ w 2 ≤20 mm.

[0012] In the preferred technical solution of the above-mentioned pole piece, 1 mm ≤ w 1 ≤10 mm; and / or, 1 mm ≤w 2 ≤5 mm.

[0013] In the preferred technical solution of the above-mentioned pole piece, the length of the first part is L 1 , the length of the second part is L 2 , where L 1 >L 2 .

[0014] In the preferred technical solution of the above-mentioned pole piece, the first adhesive layer is fixedly connected to the current collector.

[0015] In a preferred technical solution of the above-mentioned pole piece, the pole piece further includes a second adhesive layer, the second adhesive layer is connected to the current collector, and the active material layer is located between the first adhesive layer and the second adhesive layer.

[0016] In the preferred technical solution of the above-mentioned pole piece, the second adhesive layer includes a third part and a fourth part, the third part is located between the active material layer and the fourth part, and the thickness of the fourth part is smaller than the thickness of the third part. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings, in which:

[0018] Figure 1 It is a structural schematic diagram of the pole piece of the utility model;

[0019] Figure 2 yes Figure 1A cross-sectional view of the pole piece of the utility model along line AA is shown;

[0020] Figure 3 It is a structural schematic diagram of another embodiment of the pole piece of the utility model.

[0021] List of reference numerals:

[0022] 100-pole piece; 1, current collector; 11-body; 12-ear; 2-active material layer; 3-first bonding layer; 31-first part; 32-second part; 321-first surface; 4-second bonding layer; 41-third part; 42-fourth part; 421-third surface. DETAILED DESCRIPTION

[0023] 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.

[0024] It should be noted that in the description of the present invention, the terms "inside", "outside", "upper", "lower", "top", "bottom", "left", "right", "front", "back" 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 on the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0025] In addition, it should be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "set", "connect", and "install" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0026] Specifically, see first Figure 1 and Figure 2 , Figure 1 It is a schematic diagram of the structure of the pole piece of the utility model. Figure 2 yes Figure 1 The cross-sectional view of the pole piece of the present invention along the AA line is shown.

[0027] like Figure 1 and Figure 2 As shown, the pole piece 100 of the present invention includes a current collector 1 , an active material layer 2 disposed on the current collector 1 , and a first adhesive layer 3 disposed on the current collector 1 and on one side of the active material layer 2 .

[0028] Specifically, when the electrode 100 is a positive electrode, the current collector 1 is made of aluminum foil material; when the electrode 100 is a negative electrode, the current collector 1 is made of copper foil material. Through the above limitations, the current collector 1 can be applicable to different electrode sheets to meet the needs of different application scenarios or environments.

[0029] Furthermore, the pole piece 100 further includes a body 11 and a pole ear 12 located on one side of the body 11. The body 11 and the pole ear 12 can be integrally formed or can be fixedly connected to each other by welding or the like, and the connection method between the two can be set as required.

[0030] Specifically, the body 11 is preferably rectangular, and in other embodiments, the body 11 may also be a polygon or other geometric shape, which will not be repeated here. Similarly, the tab 12 is preferably rectangular, and in other embodiments, the tab 12 may also be a polygon or other geometric shape.

[0031] More specifically, the pole ear 12 and the body 11 are arranged along a first direction. In this embodiment, the first direction is preferably the length direction of the pole piece 100. Figure 1 The up and down directions in .

[0032] More specifically, the size of the body 11 in the second direction is greater than the size of the tab 12 in the second direction, thereby reducing the material cost of the tab 12 and reducing the cost of the entire battery. In this embodiment, the second direction is the width direction of the pole piece 100. Figure 1 The left and right direction in .

[0033] Preferably, the active material layer 2 is coated on the current collector 1 , and specifically, the active material layer 2 is coated on the surface of the body 11 .

[0034] Specifically, in order to improve the energy density, the active material layer 2 is provided with two layers and is respectively located on both sides of the current collector 1, so that the current collector 1 is sandwiched between the two layers of active material layers 2, thereby effectively improving the space utilization and the energy density of the battery.

[0035] Preferably, the first adhesive layer 3 is bonded to the current collector 1, thereby achieving a fixed connection between the first adhesive layer 3 and the current collector 1. In this embodiment, in the first direction, the first adhesive layer 3 is located on one side of the active material layer 2 and is close to the active material layer 2, which is conducive to bonding and fixing the area on one side of the active material layer 2 to the diaphragm.

[0036] Specifically, the first bonding layer 3 is preferably a ceramic material, a polymer material, or a composite material. The composite material here is a composite of a ceramic material and a polymer material, wherein the ceramic material includes silica, boehmite, alumina, titanium dioxide, an ion conductor, etc., and the polymer material includes PVDF (polyvinylidene fluoride), PAA (polyacrylic acid), PI (polyimide), EVA (ethylene-vinyl acetate copolymer), acrylate, PE (polyethylene), ethylene-acrylate copolymer, polyurethane, SBR (styrene-butadiene rubber), SBS (styrene-butadiene-styrene block copolymer), etc. In other embodiments, the first bonding layer 3 may also be other materials, which will not be repeated here.

[0037] More specifically, the first bonding layer 3 includes a first part 31 and a second part 32, and the first part 31 and the second part 32 are arranged along the first direction, that is, the first part 31 is between the second part 32 and the active material layer 2, and the second part 32 and the first part 31 are respectively bonded to the current collector 1 to achieve a fixed connection between the first part 31 and the second part 32 and the current collector 1.

[0038] More specifically, the first portion 31 and the second portion 32 may be integrally formed or separately provided, and the user may select the setting according to the needs.

[0039] Preferably, the first part 31 and the second part 32 are bonded to the current collector 1 in the following cases: the first part 31 and the second part 32 are both bonded to the body 11; or, the first part 31 is entirely bonded to the body 11 and the second part 32 is entirely bonded to the tab 12; or, the first part 31 and the second part 32 are both bonded to the tab 12; or, the first part 31 is bonded to the body 11 and the second part 32 is bonded to both the body 11 and the tab 12; or, the second part is bonded to the tab 12 and the first part 31 is bonded to both the body 11 and the tab 12. In this embodiment, the first part 31 is bonded to the body 11 and the second part 32 is bonded to the tab 12.

[0040] More preferably, the thickness of the second portion 32 is smaller than the thickness of the first portion 31 .

[0041] Specifically, since the thickness of the first adhesive layer 3 is usually smaller than the thickness of the active material layer 2, there is a gap between the first adhesive layer 3 and the diaphragm, and the diaphragm needs to be bonded and fixed to the first adhesive layers 3 of the pole pieces on both sides thereof at the same time. In order to eliminate the gap, the first adhesive layers 3 of the pole pieces 100 on both sides of the diaphragm need to be bent toward the diaphragm to be bonded and fixed to the diaphragm.

[0042] Furthermore, by setting the thickness of the second part 32 to be smaller than the thickness of the first part 31, the bending resistance of the area on the current collector 1 coated with the second part 32 can be reduced, so that it can be bent smoothly and then bonded to the diaphragm. In addition, the setting of the first bonding layer 3 can make the burrs on the remaining pole pieces contact with the first bonding layer 3 after piercing the diaphragm, so as to prevent the burrs from contacting the current collector 1 to produce a short circuit, causing unnecessary safety hazards, and improving the safety of the battery.

[0043] Furthermore, along the first direction, the thickness of the second portion 32 gradually decreases.

[0044] Specifically, by gradually reducing the thickness of the second portion 32 , the bending resistance of the region of the current collector 1 away from the active material layer 2 is gradually reduced, and thus it is easier to bend to contact the separator, so that the first bonding layer 3 is firmly bonded and fixed to the separator.

[0045] Preferably, the second portion 32 is located on the pole ear 12, so that after multiple pole pieces 100 and diaphragms are stacked in sequence, the pole ears 12 of the multiple pole pieces 100 can be smoothly bent and gathered together for welding, thereby reducing the difficulty of bending and improving the structural stability.

[0046] Preferably, the second part 32 includes a first surface 321 and a second surface, the second surface is bonded and fixed to the current collector 1, so that the second part 32 is firmly fixed on the current collector 1, and the first surface 321 is a curved surface, thereby facilitating the molding of the second part 32, improving the molding efficiency, and can be firmly bonded and fixed to the diaphragm.

[0047] More preferably, the curved surface is preferably a curved surface that is convex in the middle region toward the direction away from the current collector 1, which not only reduces the difficulty of the manufacturing process, but also can achieve stable bonding and fixation with the diaphragm, thereby improving the structural stability.

[0048] Preferably, the thickness of the first portion 31 is t 1 , where 10 μm ≤ t 1 ≤80 microns; and / or, the thickness of the second portion 32 is t 2 , where 5 microns ≤ t 2 ≤50 microns. Specifically, Figure 2 As shown, the thickness of the first portion 31 is t 1 , by 1The thickness of the first portion 31 is limited to 10 microns to 80 microns. On the one hand, it can prevent the first portion 31 from being too thin, which leads to ineffective and comprehensive contact with the diaphragm, affecting the stability of the bonding between the pole piece 100 and the diaphragm. On the other hand, it can prevent the first portion 31 from being too thick, which leads to protrusion of the active material layer 2, occupying too much space and increasing costs. The above range can be limited to the optimal cost reduction and improve the competitiveness of the product on the basis of ensuring the stable bonding between the pole piece 100 and the diaphragm. More preferably, 20 microns ≤ t 1 ≤40 microns.

[0049] More specifically, Figure 2 As shown, the thickness of the second part is t 2 , by 2 The thickness of the second portion 32 is limited to 5 microns to 50 microns. On the one hand, it can prevent the second portion 32 from being too thin, which may result in ineffective and comprehensive contact with the diaphragm, affecting the stability of the bonding between the pole piece 100 and the diaphragm. On the other hand, it can prevent the second portion 32 from being too thick, which may increase the cost and affect the bending of the current collector 1 to be bonded and fixed with the diaphragm, affecting the stability of the structure. More preferably, t 2 is 10 microns.

[0050] Preferably, the width of the first portion 31 is w 1 , where 1 mm ≤ w 1 ≤20 mm; and / or, the width of the second portion 32 is w 2 , where 0.1 mm ≤ w 2 ≤20 mm.

[0051] Specifically, Figure 1 As shown, by limiting the width of the first portion 31 to between 1 mm and 20 mm, on the one hand, it can prevent the first portion 31 from being too wide, which will lead to increased costs and occupy too much volume, and on the other hand, it can prevent the first portion 31 from being too narrow, which will affect the bonding effect between the diaphragm and the pole piece 100 and affect the structural stability. More preferably, 1 mm ≤ w 1 ≤10mm, which can further optimize the above effects, reduce costs and further optimize the stabilization effect.

[0052] More specifically, Figure 1 As shown, by limiting the width of the second portion 32 to 0.1 mm to 20 mm, on the one hand, it can prevent the second portion 32 from being too wide, which will lead to increased costs and occupy too much volume, and on the other hand, it can prevent the second portion 32 from being too narrow, which will affect the bonding effect between the diaphragm and the pole piece 100 and affect the structural stability. More preferably, 1 mm ≤ w 2 ≤5mm, which can further optimize the above effects, reduce costs and further optimize the stabilization effect.

[0053] Preferably, if Figure 1 As shown, the length of the first portion 31 is L 1 , the length of the second portion 32 is L 2 , where L 1 >L 2 .

[0054] Specifically, the length of the first portion 31 is greater than the length of the second portion 32 , thereby reducing the material used in the first adhesive layer 3 and lowering the cost.

[0055] Preferably, the first adhesive layer 3 is fixedly connected to the current collector 1 .

[0056] Specifically, the first adhesive layer 3 is bonded and fixed to the current collector 1. In other embodiments, the first adhesive layer 3 and the current collector 1 may also be connected in other ways, which will not be described in detail. More specifically, the side of the first portion 31 facing away from the second portion 32 is attached to the side of the active material layer 2, thereby achieving a fixed connection between the two.

[0057] Preferably, the pole piece 100 further includes a second adhesive layer 4 , the second adhesive layer 4 is connected to the current collector 1 , and the active material layer 2 is located between the first adhesive layer 3 and the second adhesive layer 4 .

[0058] Specifically, the second adhesive layer 4 is bonded to the current collector 1, thereby achieving a fixed connection between the second adhesive layer 4 and the current collector 1. The first adhesive layer 3 and the second adhesive layer 4 are respectively located on both sides of the active material layer 2, so that the parts of the current collector 1 located on both sides of the active material layer 2 can be firmly connected to the diaphragm, thereby enhancing the stability of the connection between the pole piece 100 and the diaphragm. In one embodiment, the cross-section of the second adhesive layer 4 is rectangular, that is, the thickness of the second adhesive layer 4 at one end close to the active material layer 2 and at the other end away from the active material layer 2 is the same. In another embodiment, as Figure 3 As shown, the second adhesive layer 4 includes a third portion 41 and a fourth portion 42, and the third portion 41 is located between the fourth portion 42 and the active material layer 2. Specifically, the third portion 41 and the fourth portion 42 are both bonded and fixed to the current collector 1. In other embodiments, the third portion 41 and the fourth portion 42 can also be fixedly connected to the current collector 1 in other ways, which will not be described here.

[0059] More specifically, the thickness of the third portion 41 is greater than the thickness of the fourth portion 42 , thereby reducing the bending resistance of the region of the current collector 1 coated with the fourth portion 42 , allowing it to bend smoothly to be bonded and fixed to the diaphragm, thereby improving the stability of the overall structure.

[0060] More specifically, in the first direction, the thickness of the fourth portion 42 gradually decreases. As a result, the bending resistance of the current collector 1 in the first direction, which is far away from the active material layer 2, gradually decreases, and it is easier to bend to contact the diaphragm, so that the first bonding layer 3 and the diaphragm are firmly bonded and fixed, the structural stability is improved, and the material used in the second bonding layer 4 is reduced to reduce costs and improve the market competitiveness of the product.

[0061] The fourth part 42 includes a third surface 421 and a fourth surface. The fourth surface is bonded and fixed to the current collector 1 to ensure that the fourth part 42 is firmly fixed to the current collector 1. The third surface 421 is a curved surface, which facilitates the molding of the fourth part 42, improves the molding efficiency, and can be firmly bonded and fixed to the diaphragm.

[0062] More preferably, the curved surface is preferably a curved surface that is convex in the middle region toward the direction away from the current collector 1, which not only reduces the difficulty of the manufacturing process, but also can achieve stable bonding and fixation with the diaphragm, thereby improving the structural stability.

[0063] On the other hand, the utility model further provides a battery cell, comprising the above-mentioned pole piece 100 .

[0064] 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 application and form different embodiments. For example, in the claims of the present application, any one of the claimed embodiments may be used in any combination.

[0065] 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 current collector, an active material layer arranged on the current collector and a first adhesive layer, the first adhesive layer is located on one side of the active material layer, the first adhesive layer includes a first part and a second part, the first part is located between the active material layer and the second part, and the thickness of the second part is less than the thickness of the first part.

2. The pole piece according to claim 1, characterized in that: The second portion includes a first surface, and the first surface is a curved surface.

3. The pole piece according to claim 1, characterized in that: Along the first direction, the thickness of the second portion gradually decreases.

4. The pole piece according to claim 1, characterized in that: The thickness of the first portion is t1, wherein 10 micrometers ≤ t1 ≤ 80 micrometers; and / or the thickness of the second portion is t2, wherein 5 micrometers ≤ t2 ≤ 50 micrometers.

5. The pole piece according to claim 1, characterized in that: The width of the first portion is w1, wherein 1 mm ≤ w1 ≤ 20 mm; and / or the width of the second portion is w2, wherein 0.1 mm ≤ w2 ≤ 20 mm.

6. The pole piece according to claim 5, characterized in that: 1 mm ≤ w1 ≤ 10 mm; and / or, 1 mm ≤ w2 ≤ 5 mm.

7. The pole piece according to claim 1, characterized in that: The length of the first portion is L1, and the length of the second portion is L2, wherein L1>L2.

8. The pole piece according to claim 1, characterized in that: The first adhesive layer is fixedly connected to the current collector.

9. The pole piece according to claim 8, characterized in that: The pole piece further includes a second adhesive layer, the second adhesive layer is connected to the current collector, and the active material layer is located between the first adhesive layer and the second adhesive layer.

10. The pole piece according to claim 9, characterized in that: The second adhesive layer includes a third portion and a fourth portion, the third portion is located between the active material layer and the fourth portion, and the thickness of the fourth portion is smaller than the thickness of the third portion.

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