Tab adhesive and pouch cell

Abstract

This utility model discloses an electrode tab adhesive and a soft-pack battery. The electrode tab adhesive includes a PP-modified layer, a metal-modified layer, and a base layer. The PP-modified layer is used for bonding with the aluminum-plastic film, and its melting point is P1. The metal-modified layer is used for bonding with the metal electrode tab, and its melting point is P2. The base layer is located between the PP-modified layer and the metal-modified layer, and its melting point is P3, where P3 > P1 and P3 > P2. Therefore, during the processing of the soft-pack battery, the PP-modified layer and the metal-modified layer can melt first at a relatively low temperature to achieve good bonding with the corresponding components, while the base layer remains relatively stable. This avoids the delamination or micro-cracks between the base layer and the PP-modified layer and the metal-modified layer caused by the simultaneous high-temperature melting of multiple layers, improving the overall stability and reliability of the electrode tab adhesive structure, thereby reducing the risk of leakage in the soft-pack battery and improving the battery's performance and lifespan.

Description

Technical Field

[0001] This utility model relates to the field of battery technology, and in particular to an electrode tab adhesive and a soft-pack battery. Background Technology

[0002] In pouch cells, the sealing connection between the tabs and the aluminum-plastic film relies on the hot-melt encapsulation of the tab adhesive. The tab adhesive, after being heated and melted, bonds to the inner polypropylene (PP) layer of the aluminum-plastic film and the tabs, forming a stable sealed structure that ensures the isolation of the cell's internal environment. However, due to the significant difference in surface energy between the metal tabs (such as aluminum or nickel-plated copper) and the PP layer of the aluminum-plastic film, the bonding strength between the tab adhesive and both is uneven. This asymmetry in interfacial bonding strength, during the thermal cycling of the battery, can easily lead to interfacial delamination or microcracks due to the mismatch in the coefficient of thermal expansion (CTE) between the metal tabs and the polymer material. This can result in electrolyte leakage or external moisture intrusion, affecting the battery's safety and cycle life.

[0003] In some technologies, to improve this problem, the tab adhesive uses a composite structure formed by hot-melt welding of a PP layer and a metalophilic modified PP layer, thereby improving the adhesion between the tab adhesive and the metal tab and the PP layer. However, when used in pouch batteries, both the PP layer and the metalophilic modified PP layer need to be melted at high temperatures during the pouch battery manufacturing process, which can easily lead to delamination or microcracks between the PP layer and the metalophilic modified PP layer, still affecting the safety and cycle life of the battery. Utility Model Content

[0004] This invention aims to solve at least one of the technical problems existing in the prior art. To this end, this invention proposes an electrode tab adhesive that can reduce the risk of leakage in pouch batteries, thereby improving battery safety and cycle life.

[0005] This invention also provides a soft-pack battery comprising the aforementioned tab adhesive.

[0006] The tab adhesive according to a first aspect of the present invention includes: a PP-friendly modified layer, a metal-friendly modified layer, and a base layer.

[0007] The PP-friendly modified layer is used to bond with the PP layer in the aluminum-plastic film, and the melting point of the PP-friendly modified layer is P1; the metal-friendly modified layer is used to bond with the metal tabs, and the melting point of the metal-friendly modified layer is P2; the base layer is located between the PP-friendly modified layer and the metal-friendly modified layer, and is heat-fused to the PP-friendly modified layer and the metal-friendly modified layer respectively, and the melting point of the base layer is P3, where P3 > P1 and P3 > P2.

[0008] The tab adhesive according to the embodiments of this utility model has at least the following beneficial effects:

[0009] In this embodiment, the PP-affinity modified layer and the metal-affinity modified layer can improve the adhesion between the tab adhesive and the PP layer and metal tabs in the aluminum-plastic film, reducing interfacial delamination or microcracks caused by thermal expansion coefficient mismatch during battery charge-discharge thermal cycling, reducing the risk of electrolyte leakage or external moisture intrusion, and improving battery safety and cycle life. Furthermore, a base layer with a higher melting point is provided between the PP-affinity modified layer and the metal-affinity modified layer. Therefore, when the tab adhesive of this embodiment is used in a pouch battery, during the pouch battery processing, the PP-affinity modified layer and the metal-affinity modified layer can melt first at a relatively low temperature to achieve good adhesion with the corresponding components, while the base layer remains relatively stable. This avoids the delamination or microcracks between the base layer and the PP-affinity modified layer and the metal-affinity modified layer caused by multiple layers melting at high temperatures simultaneously, improving the overall stability and reliability of the tab adhesive structure, thereby reducing the risk of pouch battery leakage and ultimately improving battery performance and lifespan.

[0010] According to some embodiments of the present invention, in a first direction, the tab adhesive includes a first end and a second end facing away from each other. The tab adhesive includes a weakening region and an adhesive region. The strength of the weakening region is less than the strength of the adhesive region. The weakening region extends from the first end to the second end along the first direction. The tab adhesive includes two adhesive regions, which are respectively connected to both sides of the weakening region in a second direction. The tab adhesive can be folded with the weakening region as a crease so that the two adhesive regions respectively adhere to the two surfaces of the tab in the direction behind itself.

[0011] The first direction, the second direction, and the thickness direction of the tab adhesive are set perpendicularly to each other.

[0012] According to some embodiments of this utility model, the weakening region has a weakening groove, which is recessed along the thickness direction of the tab adhesive and extends from the first end to the second end; or...

[0013] The weakening region also has multiple weakening holes, which are spaced apart along the first direction.

[0014] According to some embodiments of the present invention, the PP-friendly modified layer has a first mounting groove, and both the base layer and the metal-friendly modified layer are located within the first mounting groove.

[0015] According to some embodiments of the present invention, the metalophilic modified layer located in the bonding area has a second mounting groove for inserting the electrode tab, and each inner wall of the second mounting groove is heat-fused to the electrode tab.

[0016] According to some embodiments of the present invention, the PP-friendly modified layer further includes a positioning part, the positioning part having a positioning surface, the positioning surface being used to abut against the cut edge of the sealing structure in the aluminum-plastic film to limit the size of the tab adhesive protruding from the sealing structure.

[0017] According to some embodiments of the present invention, in the first direction, the distance between the positioning surface and the first end is L, where 0 < L ≤ 0.2 mm.

[0018] According to some embodiments of the present invention, the surface of the base layer facing the PP-modified layer further has a first receiving groove, and a portion of the PP-modified layer is embedded in the first receiving groove; and / or,

[0019] The surface of the base layer facing the metalophilic modified layer also has a second receiving groove, into which a portion of the metalophilic modified layer is embedded.

[0020] A pouch battery according to a second aspect of the present invention includes: a casing, a battery cell, and tab adhesive according to the first aspect of the present invention.

[0021] The outer casing includes a packaging body and multiple edge sealing structures. The packaging body has a receiving cavity. The edge sealing structures are connected to the packaging body and include two edge sealing portions distributed along their own thickness direction. Each edge sealing portion has a PP layer, and the PP layers of the two edge sealing portions are heat-fused together. The battery cell includes a battery cell body and a tab. The battery cell body is located within the receiving cavity. The tab is connected to the battery cell body and extends from the edge sealing structures. The tab includes a sealing portion located between the two edge sealing portions. The tab adhesive covers the sealing portion, and the PP-affinity modified layer is heat-fused to the PP layer, and the metal-affinity modified layer is heat-fused to the tab.

[0022] The soft-pack battery according to the embodiments of the present invention has at least the following beneficial effects:

[0023] The tab adhesive adopted in the first aspect embodiment improves the adhesion between the tab adhesive and the PP layer and metal-friendly modified layer in the tab adhesive, thereby reducing interfacial delamination or microcracks caused by thermal expansion coefficient mismatch during battery charge-discharge thermal cycling, reducing the risk of electrolyte leakage or external moisture intrusion, and improving battery safety and cycle life. Furthermore, a base layer with a higher melting point is provided between the PP-friendly modified layer and the metal-friendly modified layer. Therefore, during the processing of the pouch battery, the PP-friendly modified layer and the metal-friendly modified layer can melt first at a relatively low temperature to achieve good adhesion with the corresponding components, while the base layer remains relatively stable. This avoids the generation of delamination or microcracks between the base layer and the PP-friendly and metal-friendly modified layers caused by the simultaneous high-temperature melting of multiple layers, improving the overall stability and reliability of the tab adhesive structure, thereby reducing the risk of leakage in the pouch battery and ultimately improving battery performance and lifespan.

[0024] According to some embodiments of this utility model, the electrode tab further has a third receiving groove, and a portion of the metalophilic modified layer is embedded in the third receiving groove; and / or,

[0025] The tab also includes several protrusions that are embedded in the metalophilic modified layer.

[0026] Additional aspects and advantages of this invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0027] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein:

[0028] Figure 1 This is a schematic diagram of the structure of the first type of tab adhesive according to the first aspect of this utility model;

[0029] Figure 2 for Figure 1 A sectional view;

[0030] Figure 3 This is a schematic diagram of the structure of the second type of tab adhesive according to the first aspect of this utility model;

[0031] Figure 4 This is a schematic diagram of the structure of the third type of tab adhesive according to the first aspect of this utility model;

[0032] Figure 5 This is a cross-sectional view of the fourth type of tab adhesive according to the first aspect of this utility model;

[0033] Figure 6 This is a cross-sectional view of the fifth type of tab adhesive according to the first aspect of this utility model;

[0034] Figure 7 for Figure 6 A schematic diagram of the folded earplugs;

[0035] Figure 8 This is a cross-sectional view of the sixth type of tab adhesive according to the first aspect of this utility model;

[0036] Figure 9 For the extreme ear and Figure 8 A schematic diagram of the folded structure of the middle pole ear glue;

[0037] Figure 10 This is a cross-sectional view of the seventh type of tab adhesive according to the first aspect of this utility model;

[0038] Figure 11 This is a schematic diagram of the structure of the eighth type of tab adhesive according to the first aspect of this utility model;

[0039] Figure 12 This is a cross-sectional view of the tab adhesive and the tab in the first type of soft-pack battery according to the second aspect embodiment of this utility model;

[0040] Figure 13 This is a cross-sectional view of the tab adhesive and the tab in the second type of soft-pack battery according to the second aspect of this utility model.

[0041] Figure label:

[0042] PP modified layer 100, first mounting groove 110, positioning part 120, top surface 121;

[0043] Metal-friendly modified layer 200, second mounting groove 210;

[0044] The base layer is 300mm, the first receiving groove is 310mm, and the second receiving groove is 320mm.

[0045] Bonding area 400;

[0046] The weakening zone is 500, and the weakening groove is 510.

[0047] The first end is 600, the second end is 700.

[0048] The tab is 800, the third receiving groove is 810, and the protrusion is 820. Detailed Implementation

[0049] The embodiments of this utility model are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this utility model, and should not be construed as limiting this utility model.

[0050] In the description of this utility model, it should be understood that the directional descriptions, such as up, down, front, back, left, right, etc., indicate the directional or positional relationship based on the directional or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0051] In the description of this utility model, "several" means one or more, "multiple" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0052] In the description of this utility model, unless otherwise explicitly defined, terms such as "setting," "installation," and "connection" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this utility model in conjunction with the specific content of the technical solution.

[0053] In pouch cells, the sealing connection between the tabs and the aluminum-plastic film relies on the hot-melt encapsulation of the tab adhesive. The tab adhesive, after being heated and melted, bonds to the inner polypropylene (PP) layer of the aluminum-plastic film and the tabs, forming a stable sealed structure that ensures the isolation of the cell's internal environment. However, due to the significant difference in surface energy between the metal tabs (such as aluminum or nickel-plated copper) and the PP layer of the aluminum-plastic film, the bonding strength between the tab adhesive and both is uneven. This asymmetry in interfacial bonding strength, during the thermal cycling of the battery, can easily lead to interfacial delamination or microcracks due to the mismatch in the coefficient of thermal expansion (CTE) between the metal tabs and the polymer material. This can result in electrolyte leakage or external moisture intrusion, affecting the battery's safety and cycle life.

[0054] In some technologies, to improve this problem, the tab adhesive uses a composite structure formed by hot-melt welding of a PP layer and a metalophilic modified PP layer, thereby improving the adhesion between the tab adhesive and the metal tab and the PP layer. However, when used in pouch batteries, both the PP layer and the metalophilic modified PP layer need to be melted at high temperatures during the pouch battery manufacturing process, which can easily lead to delamination or microcracks between the PP layer and the metalophilic modified PP layer, still affecting the safety and cycle life of the battery.

[0055] In view of the above background, this utility model proposes an electrode tab adhesive that can reduce the risk of leakage in pouch batteries, thereby improving battery safety and cycle life. (See reference...) Figure 1 and Figure 2The tab adhesive of this embodiment includes: a PP-friendly modified layer 100, a metal-friendly modified layer 200, and a base layer 300.

[0056] The PP-compatible modified layer 100 is used for bonding with the PP layer in the aluminum-plastic film. The melting point of the PP-compatible modified layer 100 is P1. The PP-compatible modified layer 100 is made of materials such as maleic anhydride-grafted polypropylene (PP-g-MAH) or ethylene-butyl acrylate-styrene copolymer (EAA). Among them, the PP-g-MAH material introduces polar groups by grafting maleic anhydride onto the polypropylene backbone, giving it excellent affinity for PP materials. It can form a strong chemical bond or physical entanglement with the PP layer in the aluminum-plastic film, effectively improving the bonding strength. The EAA material has good flexibility and adhesive properties, and has excellent adhesion to non-polar materials such as PP. It can be tightly bonded to the PP layer of the aluminum-plastic film in a hot-melt state to form a stable adhesive interface, and can maintain good adhesive stability within the operating temperature range of lithium batteries.

[0057] The metalophilic modified layer 200 is used for bonding with the metal tab 800. The metalophilic modified layer 200 has a melting point of P2 and is made, for example, of polyurethane (PU) or acrylic-modified epoxy resin. PU contains various polar groups, exhibiting strong adsorption and wettability to metal surfaces, enabling it to form a strong bond with the metal tab 800. Furthermore, polyurethane possesses good flexibility, abrasion resistance, and chemical corrosion resistance, protecting the metal tab 800 from electrolyte corrosion and maintaining a stable bond in the complex electrochemical environment of a lithium battery. As for acrylic-modified epoxy resin, epoxy resin itself has good adhesion to metals; after acrylic modification, not only is the bond strength improved, but the curing speed and flexibility are also enhanced. The cross-linked structure formed after curing tightly encapsulates the metal tab 800, providing reliable electrical insulation and mechanical protection, while resisting chemical corrosion from inside the lithium battery.

[0058] The base layer 300 is located between the PP-modified layer 100 and the metalophilic modified layer 200, and is heat-fused to both layers respectively. The melting point of the base layer 300 is P3, where P3 > P1 and P3 > P2. The base layer 300 is made of materials such as polyethylene terephthalate (PET) or polyphenylene sulfide (PPS). PET has a high melting point and good mechanical strength, maintaining a stable structure at high temperatures and preventing deformation or melting during the heat fusion of the PP-modified layer 100 and the metalophilic modified layer 200. Furthermore, after appropriate surface treatment, PET can form a good physical or chemical bond with the PP-modified layer 100 and the metalophilic modified layer 200, enhancing the overall stability of the tab adhesive structure. PPS has a high melting point and strong chemical stability, maintaining stable performance during the high-temperature processing and long-term use of lithium batteries. After PPS is hot-melted and welded with the PP-friendly modified layer 100 and the metal-friendly modified layer 200, a high-strength connection interface can be formed, which effectively improves the overall strength and reliability of the tab adhesive, while also having good flame retardancy and improving the safety of lithium batteries.

[0059] Specifically, in this embodiment, the PP-friendly modified layer 100 and the metal-friendly modified layer 200 can improve the adhesion performance between the tab adhesive and the PP layer and metal tab 800 in the aluminum-plastic film, reduce the interface delamination or microcracks caused by the mismatch of thermal expansion coefficients during battery charging and discharging thermal cycling, reduce the risk of electrolyte leakage or external moisture intrusion, and improve the safety and cycle life of the battery. Based on this, a base layer 300 with a higher melting point is provided between the PP-friendly modified layer 100 and the metal-friendly modified layer 200. Therefore, when the tab adhesive of this embodiment is used in a pouch battery, during the pouch battery processing, the PP-friendly modified layer and the metal-friendly modified layer 200 can melt first at a relatively low temperature to achieve good adhesion with the corresponding components, while the base layer 300 remains relatively stable. This avoids the generation of delamination or micro-cracks between the base layer 300 and the PP-friendly modified layer 100 and the metal-friendly modified layer 200 due to the simultaneous high-temperature melting of multiple layers, thereby improving the stability and reliability of the overall structure of the tab adhesive, reducing the risk of leakage in the pouch battery, and thus improving the battery performance and service life.

[0060] Reference Figures 3 to 5 In some embodiments, in the first direction, the tab adhesive includes a first end 600 and a second end 700 facing away from each other, and the tab adhesive includes a weakening region 500 and an adhesive region 400 (e.g., ...). Figure 3 As shown), the strength of the weakened region 500 is less than the strength of the adhesive region 400. The weakened region 500 extends along a first direction from the first end 600 to the second end 700. For example, the weakened region 500 has a weakening groove 510 (as shown). Figure 4 and Figure 5As shown, the weakening groove 510 is recessed along the thickness direction of the tab adhesive, and extends from the first end 600 to the second end 700. Alternatively, the weakening region 500 may also have a plurality of weakening holes, which are spaced apart along the first direction. The tab adhesive includes two bonding regions 400, which are respectively connected to both sides of the weakening region 500 in the second direction (the first direction, the second direction, and the thickness direction of the tab adhesive are perpendicular to each other). The tab adhesive can be folded along the weakening region 500 so that the two bonding regions 400 respectively bond to the two surfaces of the tab 800 in the direction behind itself. Therefore, when the tab adhesive of this embodiment is used to process a soft-pack battery, the tab adhesive can be folded along the weakening region 500 during processing to ensure that the two bonding regions 400 are tightly attached to the surface of the tab 800, thereby improving the bonding strength and making the tab adhesive of this embodiment more convenient to use.

[0061] It should be noted that, Figure 3 The dashed line should not be interpreted as the actual outline of the tab adhesive; it is only used to more clearly show the positions of the weakening zone 500 and the bonding zone 400.

[0062] Furthermore, it is understandable that existing pouch batteries, due to their ring-shaped structure, typically require the tab sleeve to be first bonded to the tab 800 during processing, followed by the placement of the battery cell within the aluminum-plastic film. Due to processing and installation errors in the aluminum-plastic film and battery cell, the dimensions of the tab sleeve protruding from the sealing edge are difficult to control precisely. Moreover, because bending the tab sleeve protrusion 820° is difficult, an excessively large protrusion can lead to the tab sleeve occupying a large portion of the pouch battery, thus reducing its energy density. In this embodiment, however, the tab 800 is covered by folding. Therefore, during processing, it is unnecessary to pre-connect the tab sleeve to the tab 800. This allows for control of the distance between the tab sleeve protruding from the sealing edge, preventing the protruding tab sleeve from becoming too large and improving the battery's energy density. Specifically, the edge sealing structure (such as the top edge sealing) includes two edge sealing layers formed by aluminum-plastic film. Each edge sealing layer includes a nylon layer, an aluminum layer, and a PP layer. During processing, before heat sealing the edge sealing structure, the tab adhesive of this embodiment is first placed on the PP layer of one edge sealing layer, and the size of the tab adhesive protruding from the cut edge of that edge sealing layer is controlled. Then, the battery cell is placed in the pre-punched recess in the aluminum-plastic film, and the tab 800 is extended to the tab adhesive. The tab adhesive is then folded to cover the tab 800. Finally, the PP layer of the other edge sealing layer is heat-pressed and bonded to it, ensuring a tight bond between the tab adhesive and the edge sealing structure. It can be understood that during processing, the tab adhesive can be pre-placed on the edge sealing structure to control the size of the tab adhesive protruding from the edge sealing structure, thereby controlling the size of the tab adhesive protruding from the edge sealing structure after heat sealing. This avoids the tab adhesive protruding too much, thus reducing the increase in the size of the soft-pack battery caused by the tab adhesive, and ultimately improving the energy density of the soft-pack battery.

[0063] Reference Figure 5 Based on the above embodiments, the PP-friendly modified layer 100 has a weakening groove 510, meaning the base layer 300 does not penetrate the PP-friendly modified layer 100. Therefore, when folding the tab adhesive, the outer layer of the tab adhesive can be covered by the PP-friendly modified layer 100, ensuring the adhesion strength between it and the PP layer of the sealing structure. Similarly, in some embodiments, the metal-friendly modified layer 200 has a weakening groove 510; the dimensions of which will not be described in detail.

[0064] Reference Figure 4 In some embodiments, the PP-modified layer 100 has a weakening groove 510, which is a V-shaped groove, and the end faces of the PP-modified layer 100 on both sides in the second direction are inclined surfaces. Therefore, during the folding process, the edge of the tab 800 forms a side with gradually decreasing thickness. Thus, when the tab adhesive is bonded to the edge sealing structure, the side can fit more tightly into the gap formed by the two edge sealing parts, thereby improving the bonding effect and improving the sealing performance of the edge sealing structure.

[0065] Reference Figure 11 Based on the above embodiments, the PP-modified layer 100 further includes a positioning part 120. The positioning part 120 has a positioning surface, which is used to abut against the cut edge of the sealing structure in the aluminum-plastic film to limit the size of the tab adhesive protruding from the sealing structure. Therefore, during installation, the positioning surface of the positioning part 120 can be abutted against the cut surface of the sealing structure, thereby precisely controlling the size of the tab adhesive protruding from the sealing structure without human judgment, thus improving processing efficiency and product consistency. Exemplarily, in some embodiments, in the first direction, the distance between the positioning surface and the first end 600 is L, where 0 < L ≤ 0.2 mm, and L is, for example, 0.05 mm, 0.1 mm, 0.15 mm, or 0.2 mm. Therefore, the size of the tab adhesive protruding from the cut surface of the sealing structure after heat sealing is greater than 0 and less than 0.2 mm. Specifically, the requirement of a value greater than 0 is to avoid short circuits caused by the tab 800 being exposed on the cut surface of the sealing structure. A value less than 0.2mm is to prevent the tab adhesive from occupying too much space, affecting the overall battery size and energy density. In other words, when using the tab adhesive of this embodiment in a pouch battery, energy density is ensured while avoiding the risk of short circuits.

[0066] Reference Figure 6 and Figure 7 Based on the above embodiments, the PP-friendly modified layer 100 has a first mounting groove 110, and the base layer 300 and the metal-friendly modified layer 200 are both located within the first mounting groove 110. Therefore, after folding the tab adhesive of this embodiment to cover the tab 800, the outermost layer of the tab adhesive is made of the PP-friendly modified layer 100, thereby making the hot-press bonding between the tab adhesive and the sealing structure more secure, further reducing the risk of leakage of the soft-pack battery, and thus improving the safety and service life of the battery.

[0067] It should be noted that, Figure 8 The dashed line should not be interpreted as the actual outline of the tab adhesive; it is only used to more clearly show the positions of the weakening zone 500 and the bonding zone 400.

[0068] Reference Figure 8 and Figure 9In some embodiments, the metalophilic modified layer 200 located in the bonding region 400 has a second mounting groove 210. The second mounting groove 210 is used for the tab 800 to extend into, and each inner wall of the second mounting groove 210 is thermally welded to the tab 800. This not only increases the connection area between the tab adhesive and the tab 800, thereby increasing the bonding force between them, but also allows the tab adhesive to better adhere to the surface of the tab 800, preventing gaps between them and improving the sealing performance. Therefore, when the tab 800 of this embodiment is used in a pouch battery, it not only improves the bonding strength between the tab adhesive and the tab 800, but also enhances the sealing performance of the pouch battery, thereby improving battery safety and lifespan.

[0069] Reference Figure 10 In some embodiments, the surface of the base layer 300 facing the PP-modified layer 100 also has a first receiving groove 310, and a portion of the PP-modified layer 100 is embedded in the first receiving groove 310. This not only increases the contact area between the PP-modified layer 100 and the base layer 300 to enhance the adhesion effect, but also forms an interlocking structure, further reducing the possibility of separation at the interface between the PP-modified layer 100 and the base layer 300, ensuring the stability of the tab adhesive in long-term use. Similarly, in some embodiments, the surface of the base layer 300 facing the metal-modified layer 200 also has a second receiving groove 320, and a portion of the metal-modified layer 200 is embedded in the second receiving groove 320. This will not be described in detail here.

[0070] A pouch battery according to a second aspect of the present invention includes: a casing, a battery cell, and tab adhesive according to a first aspect embodiment. The casing includes a packaging body and multiple sealing structures. The packaging body has a receiving cavity. The sealing structures are connected to the packaging body and include two sealing portions distributed along their thickness direction. Each sealing portion has a PP layer, and the PP layers of the two sealing portions are heat-fused together. The battery cell is, for example, a wound battery cell or a stacked battery cell. The battery cell includes a battery cell body and tabs 800. The battery cell body is located within the receiving cavity. The tabs 800 are connected to the battery cell body and extend from the sealing structures. The tabs 800 include a sealing portion located between the two sealing portions. The tab adhesive covers the sealing portion, and a PP-affinity modified layer 100 is heat-fused to the PP layer, and a metal-affinity modified layer 200 is heat-fused to the tabs 800.

[0071] Specifically, the PP-friendly modified layer 100 and the metal-friendly modified layer 200 in the tab adhesive can improve the adhesion between the tab adhesive and the PP layer and metal tab 800 in the aluminum-plastic film, reducing interfacial delamination or microcracks caused by thermal expansion coefficient mismatch during battery charge-discharge thermal cycling, reducing the risk of electrolyte leakage or external moisture intrusion, and improving battery safety and cycle life. Furthermore, a base layer 300 with a higher melting point is provided between the PP-friendly modified layer 100 and the metal-friendly modified layer 200. Therefore, during the processing of the pouch battery, the PP-friendly modified layer and the metal-friendly modified layer 200 can melt first at a relatively low temperature to achieve good adhesion with the corresponding components, while the base layer 300 remains relatively stable. This avoids the generation of delamination or microcracks between the base layer 300 and the PP-friendly modified layer 100 and the metal-friendly modified layer 200 caused by the simultaneous high-temperature melting of multiple layers, improving the overall stability and reliability of the tab adhesive structure, thereby reducing the risk of pouch battery leakage and ultimately improving battery performance and lifespan.

[0072] It should be noted that this embodiment adopts all the beneficial effects of the first aspect embodiment. Therefore, the soft-pack battery of this embodiment includes all the beneficial effects brought by the first aspect embodiment, which will not be repeated here.

[0073] Reference Figure 12 and Figure 13 In some embodiments, the tab 800 also has a third receiving groove 810 (e.g., Figure 12 As shown, a portion of the metalophilic modified layer 200 is embedded in the third receiving groove 810, thereby increasing the contact area between the metalophilic modified layer 200 and the tab 800 to enhance the adhesion effect, thereby improving the sealing performance of the pouch battery, reducing the risk of leakage, and ultimately improving the overall safety and lifespan of the pouch battery. Similarly, in some embodiments, the tab 800 also includes several protrusions 820 (such as...). Figure 13 As shown), the protrusion 820 is embedded into the metal-friendly modified layer 200.

[0074] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments, and various changes can be made within the scope of knowledge possessed by those skilled in the art without departing from the spirit of the present invention. Furthermore, in the description of the present invention, the reference to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicates that the specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any suitable manner in one or more embodiments or examples.

Claims

1. An electrode adhesive, characterized in that, include: A PP-friendly modified layer is used to bond with the PP layer in the aluminum-plastic film, wherein the melting point of the PP-friendly modified layer is P1; A metalophilic modified layer is used for bonding with metal tabs, wherein the melting point of the metalophilic modified layer is P2; The base layer is located between the PP-friendly modified layer and the metal-friendly modified layer, and is heat-fused to the PP-friendly modified layer and the metal-friendly modified layer respectively. The melting point of the base layer is P3, where P3 > P1 and P3 > P2.

2. The tab adhesive according to claim 1, characterized in that, In a first direction, the tab adhesive includes a first end and a second end facing away from each other. The tab adhesive includes a weakening region and an adhesive region. The strength of the weakening region is less than the strength of the adhesive region. The weakening region extends from the first end to the second end along the first direction. The tab adhesive includes two adhesive regions, which are respectively connected to both sides of the weakening region in the second direction. The tab adhesive can be folded with the weakening region as a crease so that the two adhesive regions respectively adhere to two surfaces of the tab in the direction behind itself. The first direction, the second direction, and the thickness direction of the tab adhesive are set perpendicularly to each other.

3. The tab adhesive according to claim 2, characterized in that, The weakening region has a weakening groove, which is recessed along the thickness direction of the tab adhesive and extends from the first end to the second end; or... The weakening region also has multiple weakening holes, which are spaced apart along the first direction.

4. The tab adhesive according to claim 2, characterized in that, The PP-friendly modified layer has a first mounting groove, and both the base layer and the metal-friendly modified layer are located within the first mounting groove.

5. The tab adhesive according to claim 2, characterized in that, The metalophilic modified layer located in the bonding area has a second mounting groove for inserting the tab, and the inner walls of the second mounting groove are heat-fused to the tab.

6. The tab adhesive according to claim 2, characterized in that, The PP-modified layer further includes a positioning part, which has a positioning surface for contacting the cut edge of the sealing structure in the aluminum-plastic film to limit the size of the tab adhesive protruding from the sealing structure.

7. The tab adhesive according to claim 6, characterized in that, In the first direction, the distance between the positioning surface and the first end is L, where 0 < L ≤ 0.2 mm.

8. The tab adhesive according to claim 1, characterized in that, The surface of the base layer facing the PP-modified layer also has a first receiving groove, into which a portion of the PP-modified layer is embedded; and / or, The surface of the base layer facing the metalophilic modified layer also has a second receiving groove, into which a portion of the metalophilic modified layer is embedded.

9. A pouch battery, characterized in that, include: The outer casing includes a packaging body and multiple sealing structures. The packaging body has a receiving cavity. The sealing structures are connected to the packaging body. Each sealing structure includes two sealing portions distributed along its own thickness direction. Each sealing portion has a PP layer. The PP layers of the two sealing portions are heat-fused together. A battery cell includes a battery cell body and a tab. The battery cell body is located within the receiving cavity. The tab is connected to the battery cell body and extends from the sealing structure. The tab includes a sealing portion located between two sealing portions. The tab adhesive according to any one of claims 1 to 8, wherein the tab adhesive covers the sealing portion, and the PP-friendly modified layer is hot-melt welded to the PP layer, and the metal-friendly modified layer is hot-melt welded to the tab.

10. The soft-pack battery according to claim 9, characterized in that, The tab also has a third receiving groove, into which a portion of the metalophilic modified layer is embedded; and / or, The tab also includes several protrusions that are embedded in the metalophilic modified layer.

Images