An electrode tab adhesive structure and a lithium ion battery

Abstract

The application belongs to the technical field of batteries, and particularly relates to a tab gluing structure, which comprises a current collector and a coating layer coated on the surface of the current collector, and the tab body has groove positions on two surfaces; a tab is fixed in the groove position; the upper and lower surfaces of the tab of one of the tab bodies are pasted with tab position protection adhesive paper, and the surface of the other tab body is pasted with tab protection adhesive paper; after winding, the tab protection adhesive paper is located on the surface of the tab position protection adhesive paper, and the two are separated by the diaphragm of the battery; one of the tab position protection adhesive paper and the tab protection adhesive paper covers the tab, and the other of the tab position protection adhesive paper and the tab protection adhesive paper covers the groove position. By optimizing the tab gluing structure, the overall thickness of the battery cell can be reduced, so that the energy density of the battery is improved. In addition, the application also discloses a lithium ion battery.

Description

Technical Field

[0001] This invention belongs to the technical field of batteries, specifically relating to an electrode adhesive structure and a lithium-ion battery. Background Technology

[0002] Lithium-ion batteries are widely used in power fields such as electric vehicles and consumer fields such as mobile phones, watches, tablets, and laptops because of their advantages such as high specific energy, strong range, long cycle life, wide operating range, short charging time, and ability to discharge at high current.

[0003] With the rapid development of battery applications, higher demands are being placed on lithium batteries, which are gradually evolving towards higher energy density and faster charging speeds. To improve charging speed, consumer battery cells are gradually shifting from conventional structures to centrally located tabs and multi-tab structures. Currently, multiple layers of adhesive tape are attached to the positive and negative electrodes, each approximately 12µm thick. The thickness at the electrode tab location is about 48µm greater than in other locations. When the positive and negative electrodes are close together, the adhesive tape overlaps, resulting in a 96µm increase in thickness at the thickest point of the cell, severely reducing the cell's volumetric energy density. Summary of the Invention

[0004] One of the objectives of this invention is to address the shortcomings of existing technologies by providing an electrode bonding structure. By optimizing the electrode bonding structure, the overall thickness of the battery cell can be reduced, thereby increasing the energy density of the battery.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] An electrode adhesive structure includes at least two electrode bodies, each including a current collector and a coating applied to the surface of the current collector. Each electrode body has grooves on both sides. A tab is fixed to one of the grooves. Protective adhesive paper is adhered above and below the tab on one of the electrode bodies, and protective adhesive paper is correspondingly adhered to the surface of the other electrode body. After winding, the protective adhesive paper is positioned on the surface of the tab-position protective adhesive paper, and the two are separated by a battery separator. One of the tab-position protective adhesive paper and the other covers the tab, while the other covers the groove.

[0007] Preferably, the slots are symmetrically arranged on both sides of the electrode body, and the thickness of the tab is less than the thickness of the electrode body.

[0008] Preferably, one of the electrode bodies is a positive electrode and the other electrode body is a negative electrode. The tab protection paper on the positive electrode corresponds to the tab protection paper on the negative electrode. The tab protection paper on the positive electrode covers the slot of the negative electrode. The length and width of the tab protection paper on the positive electrode are greater than those of the tab protection paper on the negative electrode.

[0009] Preferably, the tab protection paper on the negative electrode plate corresponds to the tab protection paper on the positive electrode plate, the tab protection paper on the negative electrode plate covers the tab on the positive electrode plate, and the length and width of the tab protection paper on the negative electrode plate are smaller than those of the tab protection paper on the positive electrode plate.

[0010] Preferably, the thickness of both the tab protective paper and the tab protective paper is less than the thickness of the electrode body.

[0011] Preferably, the slot includes a bottom and a sidewall, the sidewall extending upward from the bottom, the bottom being a current collector exposed on the surface of the electrode body, and the coating surrounding the sidewall.

[0012] Preferably, the tab portion is embedded in the groove, and the thickness of the tab is less than the thickness of the coating.

[0013] Preferably, the current collector is one of metal foil and composite foil, the current collector of the positive electrode is one of aluminum foil and composite aluminum foil, and the current collector of the negative electrode is one of copper foil and composite copper foil.

[0014] Preferably, the coating is an active material layer.

[0015] A second objective of this invention is to provide a lithium-ion battery, including the aforementioned electrode adhesive structure. The beneficial effects of this invention are that by reducing the width of the protective adhesive paper at the negative electrode tab position, the protective adhesive paper only covers the tab of the negative electrode sheet, not the entire slot, which helps to reduce the thickness of the battery cell. Simultaneously, the width of the protective adhesive paper corresponding to the negative electrode tab position is also reduced, which helps to reduce the area of ​​the electrode sheet covered by the adhesive paper, resulting in a larger area for lithium ion insertion / extraction. This allows positive lithium ions to successfully insert into the negative electrode, leading to a larger cell capacity. Combined with the reduction in cell thickness, this improves the energy density of the battery. Attached Figure Description

[0016] The features, advantages and technical effects of exemplary embodiments of the present invention will now be described with reference to the accompanying drawings.

[0017] Figure 1 This is a schematic diagram of the electrode sheet before winding according to the present invention.

[0018] Figure 2This is a schematic diagram of the electrode sheet after winding according to the present invention.

[0019] The reference numerals in the attached figures are explained as follows:

[0020] 11-Current collector; 12-Coating; 10-Positive electrode; 20-Negative electrode;

[0021] 2-slot;

[0022] 3-Earthrottle;

[0023] 4 - Protective adhesive tape for tabs; 5 - Protective adhesive tape for tabs. Detailed Implementation

[0024] If certain terms are used in the specification and claims to refer to specific components, those skilled in the art will understand that hardware manufacturers may use different names to refer to the same component. This specification and claims do not distinguish components based on differences in name, but rather on differences in function. The term "comprising" as used throughout the specification and claims is an open-ended term and should be interpreted as "comprising but not limited to." "Approximately" means that within an acceptable margin of error, those skilled in the art can solve the technical problem and substantially achieve the technical effect within a certain margin of error.

[0025] Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be interpreted as indicating or implying relative importance.

[0026] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0027] The following is in conjunction with the appendix Figures 1-2 The present invention will be described in further detail, but this is not intended to limit the invention.

[0028] The electrode adhesive structure includes: at least two electrode bodies, including a current collector 11 and a coating 12 coated on the surface of the current collector 11, with grooves 2 on both sides of the electrode body; tabs 3, fixed to the grooves 2; tab protective paper 4 is pasted above and below the tab 3 of one electrode body, and tab protective paper 5 is correspondingly pasted on the surface of the other electrode body. After winding, the tab protective paper 5 is located on the surface of the tab protective paper 4, and the two are separated by the battery separator. One of the tab protective paper 4 and the tab protective paper 5 covers the tab 3, and the other of the tab protective paper 4 and the tab protective paper 5 covers the groove 2.

[0029] Because existing positive and negative electrode sheets are covered with various adhesive films, each layer of adhesive film is about 12µm thick. The thickness of the cell tab is about 48µm thicker than other locations. When the positive and negative tabs are close together, the adhesive film weighs down and reduces the volumetric energy density of the cell. Therefore, by reducing the width of the protective adhesive film 4 at the negative electrode tab position, the protective adhesive film 4 only covers the tab 3 of the negative electrode sheet 20 and does not cover the entire slot 2, which helps to reduce the thickness of the cell. At the same time, the width of the protective adhesive film 5 corresponding to the protective adhesive film 4 at the negative electrode tab position is also reduced, which helps to reduce the area of ​​the electrode sheet covered by the adhesive film. This results in a larger area for lithium ion insertion and extraction, allowing positive lithium ions to be successfully inserted into the negative electrode, resulting in a larger cell capacity. Combined with the reduction in cell thickness, this improves the energy density of the battery.

[0030] In this design, slots 2 are symmetrically arranged on both sides of the electrode body, and the thickness of tabs 3 is less than the thickness of the electrode body. One electrode body is a positive electrode 10, and the other electrode body is a negative electrode 20. The tab protective paper 4 on the positive electrode 10 corresponds to the tab protective paper 5 on the negative electrode 20. The tab protective paper 5 on the positive electrode 10 covers the slot 2 of the negative electrode 20. The length and width of the tab protective paper 5 on the positive electrode 10 are greater than those of the tab protective paper 4 on the negative electrode 20. In addition, the tab protective paper 4 on the negative electrode 20 corresponds to the tab protective paper 5 on the positive electrode 10. The tab protective paper 5 on the negative electrode 20 covers the tabs 3 on the positive electrode 10. The length and width of the tab protective paper 5 are less than those of the tab protective paper 4 on the positive electrode 10. Specifically, the thickness at the edge of the negative electrode tab is increased to the thickness of two layers of tab protective paper 5. The thickness at the negative electrode slot is the thickness of two layers of tab protective paper 5 + the thickness of the negative electrode tab - the thickness of the negative electrode sheet. Because the thickness of the negative electrode tab is less than the thickness of the negative electrode sheet, the thickest part around the negative electrode tab is the thickness of the negative electrode sheet coating covered by the two layers of tab protective paper 5. Compared with the existing structure, the overall thickness of the cell is reduced, and the width of the tab protective paper 4 and tab protective paper 5 is reduced compared with the existing structure, resulting in a larger area for lithium ion insertion / extraction and a larger cell capacity. Therefore, the cell capacity density of this invention is higher. Since cell capacity density = cell capacity * voltage plateau / (cell length * cell width * cell thickness), the increase in cell capacity and the decrease in cell thickness lead to an increase in cell energy density.

[0031] In the electrode adhesive structure according to the present invention, the thickness of the tab protective paper 4 and the tab protective paper 5 is less than the thickness of the electrode body, so as to avoid the tab protective paper 4 and the tab protective paper 5 being too thick and affecting the overall thickness of the battery cell.

[0032] In the electrode adhesive structure according to the present invention, the groove 2 includes a bottom and sidewalls, the sidewalls extending upward from the bottom, the bottom being a current collector 11 exposed on the surface of the electrode body, and the coating 12 surrounding the sidewalls. Specifically, the groove 2 has four sidewalls, the four sidewalls and the bottom surrounding the groove 2, the bottom being the exposed current collector 11, and the electrode tab 3 welded to the current collector 11.

[0033] In the electrode adhesive structure according to the present invention, the tab 3 is partially embedded in the groove 2, and the thickness of the tab 3 is less than the thickness of the coating 12, which helps to reduce the overall thickness of the battery cell.

[0034] In the electrode adhesive structure according to the present invention, the current collector 11 is one of metal foil and composite foil; the current collector 11 of the positive electrode 10 is one of aluminum foil and composite aluminum foil; and the current collector 11 of the negative electrode 20 is one of copper foil and composite copper foil. However, the present invention is not limited to these, and other conductive materials may also be used. The composite foil can be understood as a composite foil with a metal and polymer film sandwich structure.

[0035] In the electrode adhesive structure according to the present invention, coating 12 is an active material layer. In some embodiments, coating 12 is divided into a positive electrode coating and a negative electrode coating. Specifically, the positive electrode coating includes lithium cobalt oxide, conductive carbon black, and binder polyvinylidene fluoride, etc., and the negative electrode coating includes graphite and conductive carbon black, thickener sodium carboxymethyl cellulose, binder styrene-butadiene rubber, etc.

[0036] Lithium-ion batteries, including the aforementioned electrode adhesive structure.

[0037] Specifically, the battery cell includes a positive electrode 10, a negative electrode 20, a separator, and tabs 3. The positive electrode 10 includes aluminum foil, a positive active layer, and a positive electrode slot. The negative electrode 20 includes copper foil, a negative active layer, and a negative electrode slot. The positive electrode tabs are located at the positive electrode slots, and the negative electrode tabs are located at the negative electrode slots. The slots are covered with adhesive tape, which includes protective adhesive tape 4 for the negative electrode tabs, protective adhesive tape 5 for the positive electrode tabs on the negative electrode 20, and protective adhesive tape 4 for the positive electrode tabs on the positive electrode 10.

[0038] Two electrodes of opposite polarity are stacked on top of each other, forming the positive electrode 10 and the negative electrode 20 of the battery, respectively. To prevent short circuits between the positive and negative electrodes, a separator is provided between each pair of adjacent electrodes, and the electrodes of opposite polarity are electrically isolated by the separator. At least one of the electrodes can be the electrode adhesive structure described above.

[0039] At least two electrodes may include a first electrode and a second electrode, the first electrode and the second electrode having opposite polarities, and the first electrode and the second electrode being stacked on top of each other.

[0040] Specifically, the first electrode can be a positive electrode 10 and the second electrode can be a negative electrode 20; or, the first electrode can be a negative electrode 20 and the second electrode can be a positive electrode 10, without any restrictions.

[0041] In some examples, the battery cell can be a wound cell. There is one first electrode and one second electrode, and the first electrode, the separator, and the second electrode are sequentially stacked and wound around a center point to form a wound structure.

[0042] In other examples, the battery cell can be a laminated cell. There are multiple first electrodes and multiple second electrodes, which are sequentially and alternately stacked in the same direction. A separator is provided between each adjacent first and second electrode to provide electrical insulation between them.

[0043] Example 1

[0044] Preparation of negative electrode:

[0045] A negative electrode slurry is prepared by mixing graphite with conductive carbon black, thickener sodium carboxymethyl cellulose (CMC), and binder styrene-butadiene rubber (SBR) in a mass ratio of 96:2.0:1.0:1.0. The slurry is then uniformly coated onto copper foil current collector 11 and dried at 90°C. The dried electrode sheet is then rolled and slit. The slit electrode sheet is laser-cleaned to obtain corresponding grooves. The length of the laser-cleaned groove is 20 mm and the width is 11 mm. After laser cleaning, electrode tabs are welded onto the electrode sheet, and protective adhesive paper 4 is attached to the tab position. The length of the protective adhesive paper 4 is 23 mm and the width is 12 mm. The protective adhesive paper 4 completely covers the groove 2, thus forming a lithium-ion battery negative electrode sheet 20.

[0046] Preparation of positive electrode:

[0047] Lithium cobalt oxide, conductive carbon black, and polyvinylidene fluoride binder are mixed evenly at a mass ratio of 96:2.5:1.5 to prepare a lithium-ion battery positive electrode slurry with a preset viscosity. The slurry is coated onto aluminum foil current collector 11 and dried at 110°C. The dried electrode sheet is then laser-cleaned. The laser cleaning tank 2 is 20mm long and 11mm wide. The laser-cleaned electrode sheet is then rolled, trimmed, and slit. After slitting, it is dried at 110°C under vacuum for 4 hours. The tabs are then welded, and protective adhesive paper 4 is applied to the tab positions to form the lithium-ion battery positive electrode sheet 10. The protective adhesive paper 4 is 27mm long and 20mm wide, and it completely covers the tank 2.

[0048] Electrolyte preparation:

[0049] Lithium hexafluorophosphate (LiPF6) was dissolved in a mixed solvent consisting of ethylene carbonate (EC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC) in a mass ratio of 1:2:1 to obtain an electrolyte with a concentration of 1 mol / L.

[0050] The fabrication of lithium-ion batteries:

[0051] The positive electrode 10, separator, and negative electrode 20 are wound into a battery cell. After winding, the protective adhesive paper 4 for the negative electrode tab covers the entire negative electrode slot, and the protective adhesive paper 5 for the positive electrode tab covers the protective adhesive paper 4 for the negative electrode tab. The protective adhesive paper 4 for the negative electrode tab covers the entire positive electrode slot. The separator is located between the positive electrode 10 and the negative electrode 20. The positive electrode is led out by spot welding with aluminum tabs, and the negative electrode is led out by spot welding with nickel tabs. Then, the battery cell is placed in an aluminum-plastic packaging bag, the electrolyte is injected, and after processes such as encapsulation, formation, and capacity testing, a lithium-ion battery is manufactured.

[0052] Example 2

[0053] Unlike Example 1, in this example, the length of the protective adhesive paper 4 for the negative electrode tab and the protective adhesive paper 5 for the positive electrode tab on the negative electrode sheet 20 are changed to 19mm and the width is changed to 9mm. The protective adhesive paper 4 for the negative electrode tab completely covers the negative electrode tab but does not cover the negative electrode slot. After winding, the protective adhesive paper 5 for the positive electrode tab on the negative electrode sheet 20 only covers the positive electrode tab and does not cover the positive electrode slot.

[0054] The other structures are the same as in Example 1, and will not be described again here.

[0055] Example 3

[0056] Unlike Example 2, in this example, the length of the protective adhesive paper 4 for the positive electrode tab is changed to 23mm and the width is changed to 17mm. The protective adhesive paper 4 for the positive electrode tab completely covers the positive electrode slot, and the protective adhesive paper 5 for the negative electrode tab on the positive electrode plate 10 covers the negative electrode slot.

[0057] The other structures are the same as in Example 2, and will not be described again here.

[0058] Table 1. Electrochemical performance of lithium-ion batteries prepared in Examples 1-3

[0059]

[0060] As can be seen from the table above, the thickness, cell capacity, and energy density of Examples 2 and 3 are all higher than those of Example 1. Specifically, compared with Example 1, Example 2 only reduces the width of the protective adhesive paper 4 for the negative electrode tab and the protective adhesive paper 5 for the positive electrode tab on the negative electrode sheet 20, so that it only covers the tabs, thus reducing the thickness of the cell. The width of the protective adhesive paper 4 for the positive electrode tab and the protective adhesive paper 5 for the negative electrode tab on the positive electrode sheet 10 remains unchanged, and the cell capacity does not change. Compared with Example 1, Example 3 not only reduces the width of the protective adhesive paper 4 for the negative electrode tab and the protective adhesive paper 5 for the positive electrode tab on the negative electrode sheet 20, but also reduces the width of the protective adhesive paper 4 for the positive electrode tab and the protective adhesive paper 5 for the negative electrode tab on the positive electrode sheet 10 according to the actual situation, so that they only need to cover the slots 2 on the positive and negative electrodes. While the cell thickness is reduced, the lithium insertion / extraction area of ​​the positive electrode sheet 10 is increased, and the cell capacity is increased.

[0061] Based on the disclosure and teachings of the foregoing specification, those skilled in the art can make changes and modifications to the above embodiments. Therefore, the present invention is not limited to the specific embodiments described above, and any obvious improvements, substitutions, or modifications made by those skilled in the art based on the present invention are within the scope of protection of the present invention. Furthermore, although some specific terms are used in this specification, these terms are only for convenience of explanation and do not constitute any limitation on the present invention.

Claims

1. An electrode adhesive bonding structure, characterized in that, include: At least two electrode bodies, including a current collector (11) and a coating (12) coated on the surface of the current collector (11), the electrode bodies having grooves (2) on both sides, the grooves (2) including a bottom and a sidewall, the sidewall extending upward from the bottom, the bottom being the current collector (11) exposed on the surface of the electrode body, the coating (12) surrounding the sidewall; The tab (3) is welded to the bottom of the slot (2) and is partially embedded in the slot (2); One of the electrode bodies has tab protection paper (4) pasted above and below the tab (3), and the other electrode body has tab protection paper (5) pasted on its surface. After winding, the tab protection paper (5) is located on the surface of the tab protection paper (4), and the two are separated by the battery separator. One of the tab protection paper (4) and the tab protection paper (5) covers the tab (3), and the other of the tab protection paper (4) and the tab protection paper (5) covers the slot (2). One of the electrode bodies is a positive electrode (10), and the other electrode body is a negative electrode (20). The tab protection paper (4) on the positive electrode (10) corresponds to the tab protection paper (5) on the negative electrode (20). The tab protection paper (5) on the positive electrode (10) covers the slot (2) of the negative electrode (20). The length and width of the tab protection paper (5) on the positive electrode (10) are greater than those of the tab protection paper (4) on the negative electrode (20). The tab protective paper (4) on the negative electrode (20) corresponds to the tab protective paper (5) on the positive electrode (10). The tab protective paper (5) on the negative electrode (20) covers the tab (3) on the positive electrode (10). The length and width of the negative electrode tab protective paper (5) are smaller than the tab protective paper (4) on the positive electrode (10). The tab protective paper (4) of the negative electrode (20) only covers the tab (3) of the negative electrode (20) and does not cover the slot (2) of the negative electrode (20). After winding, the tab protective paper (5) of the negative electrode (20) only covers the tab (3) of the positive electrode (10) and does not cover the slot (2) of the positive electrode (10).

2. The electrode adhesive bonding structure as described in claim 1, characterized in that: The slots (2) are symmetrically arranged on both sides of the electrode body, and the thickness of the tabs (3) is less than the thickness of the electrode body.

3. The electrode adhesive bonding structure as described in claim 1, characterized in that: The thickness of both the tab protective paper (4) and the tab protective paper (5) is less than the thickness of the electrode body.

4. The electrode adhesive bonding structure as described in claim 1, characterized in that: The thickness of the tab (3) is less than the thickness of the coating (12).

5. The electrode adhesive bonding structure as described in claim 1, characterized in that: The current collector (11) is one of metal foil and composite foil, the current collector (11) of the positive electrode (10) is one of aluminum foil and composite aluminum foil, and the current collector (11) of the negative electrode (20) is one of copper foil and composite copper foil.

6. The electrode adhesive bonding structure as described in claim 1, characterized in that: The coating (12) is an active material layer.

7. A lithium-ion battery, characterized in that: Includes the electrode adhesive structure as described in any one of claims 1-6.

Images