Insulating adhesive and battery

Abstract

The present disclosure relates to the technical field of batteries, in particular to an insulating adhesive and a battery comprising the insulating adhesive. The insulating adhesive at least comprises three molten zones, wherein a melting peak a1 of a first molten zone is 95°C to 115°C, a melting peak a2 of a second molten zone is 115°C to 130°C, a melting peak a3 of a third molten zone is 140°C to 165°C, and the temperature T3 of the melting peak a3 of the third molten zone and the temperature T1 of the melting peak a1 of the first molten zone satisfy the following relational expression: b=T3-T1, the unit of b being °C, and b being 25°C to 70°C. The insulating adhesive in the present disclosure has relatively good adhesion between layers and does not delaminate when soaked in an electrolytic solution, and also can exhibit a high-temperature venting capability during thermal runaway of a battery cell; and a battery comprising the insulating adhesive has a high safety performance, and the sealing performance of a sealing housing thereof is also good, such that leakage of the electrolytic solution from the sealing housing caused by delamination of the insulating adhesive does not occur.

Description

Insulating glue and battery Technical Field

[0001] The present disclosure relates to the technical field of batteries, and in particular to an insulating adhesive and a battery comprising the insulating adhesive.

[0002] Background of the Invention

[0003] Lithium-ion batteries, due to their high energy density, high voltage, and long cycle life, have been widely used in consumer electronics, electric vehicles, power tools, and other products. In recent years, with the increasing demand for fast charging and multiple discharge of battery cells, the requirements for the electrical performance and safety of battery cells during use have also been further strengthened. When the battery cell is fast charged, the current density is highest at the tab. During excessive discharge, the battery cell temperature rises sharply. At this time, the thermal contraction of the diaphragm causes a short circuit between the positive and negative electrodes, the decomposition of the SEI film, and a sharp increase in the internal temperature of the battery cell, which can cause the battery cell to ignite and explode. Therefore, preventing thermal runaway of the battery cell and improving the safety performance of lithium-ion batteries are crucial.

[0004] Summary of the Invention

[0005] The battery is composed of a positive electrode assembly, a negative electrode assembly, a separator, a packaging film, and an electrolyte. The battery cell shell needs to be connected to the outside world for conductivity, and the ear glue is heat-sealed with the aluminum-plastic film (packaging film) to form a sealed shell, thereby blocking moisture and air and ensuring the sealing performance of the battery cell. However, under long-term immersion in the electrolyte, the bonding strength between the ear glue layers decreases, and stratification occurs, causing the sealed shell to have an opening at the edge and leak, and water vapor enters the battery cell, thereby reducing the safety performance of the battery. In order to solve the above-mentioned technical problems existing in the prior art, the present disclosure provides an insulating glue and a battery including the insulating glue. The insulating glue disclosed in the present disclosure has good adhesion between the layers, and will not be delaminated when immersed in the electrolyte. At the same time, it can have the performance of high-temperature opening when the battery cell has thermal runaway; the battery including the insulating glue has high safety performance and good sealing performance of the sealed shell, and will not cause stratification of the insulating glue to cause leakage of the sealed shell.

[0006] In order to achieve the above-mentioned objectives, the first aspect of the present disclosure provides an insulating glue, wherein the insulating glue includes at least three melting regions, wherein the melting peak a1 of the first melting region is 95°C-115°C, the melting peak a2 of the second melting region is 115°C-130°C, and the melting peak a3 of the third melting region is 140°C-165°C, and the temperature T3 of the melting peak a3 of the third melting region and the temperature T1 of the melting peak a1 of the first melting region satisfy the following relationship: b=T3-T1, the unit of b is ℃, wherein b is 25°C-70°C.

[0007] In one embodiment, b is 40°C-60°C;

[0008] And / or, the insulating adhesive includes at least a first adhesive layer and a second adhesive layer, the second adhesive layer is located on a surface of one side of the first adhesive layer, the melting point of the first adhesive layer is 95°C-130°C, and the melting point of the second adhesive layer is 140°C-170°C.

[0009] In one embodiment, the insulating adhesive includes a third adhesive layer, the third adhesive layer being located on a surface of the second adhesive layer away from the first adhesive layer, and the insulating adhesive satisfies: a melting point of the second adhesive layer > a melting point of the third adhesive layer, and / or a melting point of the second adhesive layer > a melting point of the first adhesive layer;

[0010] And / or, the melting point of the third adhesive layer is 95° C.-130° C.;

[0011] And / or, the difference between the melting point of the third adhesive layer and the melting point of the first adhesive layer is -5°C to 25°C.

[0012] In one example, the melting point of the first adhesive layer includes a melting peak a1 of the first melting region and a melting peak a2 of the second melting region;

[0013] and / or, the melting point of the second adhesive layer includes the melting peak a3 of the third melting region;

[0014] And / or, the melting point of the third adhesive layer includes the melting peak a1 of the first melting region and the melting peak a2 of the second melting region.

[0015] A second aspect of the present disclosure provides a battery, which includes the insulating glue described in the first aspect.

[0016] In one embodiment, the battery includes a pole piece assembly and a packaging film, the pole piece assembly includes a pole piece and a pole piece conductive material, the pole piece includes a current collector and an active material layer located on one side or both sides of the current collector, the pole piece conductive material is located at one end of the current collector, the first end of the conductive material is a welding end, the welding end is welded to the current collector, the second end opposite to the first end is a protruding end, a glue coating area is formed between the welding end and the protruding end, an insulating glue is provided on the glue coating area, the insulating glue covers the surface of the conductive material, and the first glue layer in the insulating glue The surface away from the second adhesive layer is adjacent to the conductive material, the packaging film and the insulating adhesive are connected together to form a sealed shell, and the pole piece assembly is located in the enclosed space formed by the sealed shell, the packaging film includes an inner film layer connected to the second adhesive layer or the third adhesive layer in the insulating adhesive, a metal layer located on the surface of the inner film layer, and an outer film layer located on the surface of the metal layer, the inner film layer includes a first film layer directly connected to the second adhesive layer or the third adhesive layer in the insulating adhesive and a second film layer located on the surface of the first film layer, the melting point of the first film layer is 120°C-165°C, preferably 130°C-145°C;

[0017] and / or the difference between the melting point of the first film layer and the melting point of the second adhesive layer or the third adhesive layer is -5°C to 40°C;

[0018] and / or, the first film layer comprises modified polypropylene and / or propylene ethylene copolymer;

[0019] And / or, the modified polypropylene includes one or more of maleic anhydride modified polypropylene, metallocene modified polypropylene, ethylene propylene copolymer and silane coupling modified polypropylene.

[0020] In one example, the heat sealing tension between the packaging film and the insulating adhesive is Y±0.5, in N / mm, and the temperature of the battery is T, in °C. Then the battery satisfies the following relationship: Y=-0.04572×T+5.779, where T is 20°C-125°C.

[0021] Through the above technical solution, the present disclosure has at least the following advantages compared with the prior art:

[0022] The insulating adhesive disclosed herein includes at least three melting regions, and the melting peaks of the three melting regions are limited to a specific range. At the same time, by limiting the temperature difference between the melting peak of the first melting region (the lowest temperature region) and the melting peak of the third melting region (the highest temperature region), the adhesion between the layers of the insulating adhesive is improved, and at the same time, the insulating adhesive has the performance of a high-temperature opening, thereby ensuring that the battery does not leak when thermal runaway does not occur. When thermal runaway occurs, the melting of the insulating adhesive can provide a heat dissipation channel for the battery, thereby improving the safety performance of the battery.

[0023] Other features and advantages of the present disclosure will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] FIG1 shows a DSC graph of the insulating adhesive of Example I-1 of the present disclosure.

[0025] FIG2 is a schematic diagram showing the structure of the insulating adhesive comprising two adhesive layers in the present disclosure.

[0026] FIG3 is a schematic diagram showing the structure of the insulating adhesive including three adhesive layers in the present disclosure.

[0027] FIG4 is a schematic structural diagram of a pole piece assembly in the present disclosure. DETAILED DESCRIPTION

[0028] The following is a detailed description of the specific embodiments of the present disclosure. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present disclosure and are not intended to limit the present disclosure. In this article, unless otherwise specified, data ranges include endpoints.

[0029] In a first aspect of the present disclosure, an insulating adhesive is provided, wherein the insulating adhesive includes at least three melting regions, wherein a melting peak a1 of the first melting region is 95°C-115°C, a melting peak a2 of the second melting region is 115°C-130°C, and a melting peak a3 of the third melting region is 140°C-165°C, and a temperature T3 of the melting peak a3 of the third melting region and a temperature T1 of the melting peak a1 of the first melting region satisfy the following relationship: b=T3-T1, where the unit of b is ℃, and b is 25°C-70°C.

[0030] FIG1 is a DSC graph of the insulating adhesive disclosed herein. As can be seen from FIG1 , the insulating adhesive includes at least three melting regions.

[0031] The inventors of the present disclosure have discovered through research that the tab glue in the prior art is prone to stratification when immersed in electrolyte, causing leakage at the edge opening of the sealed shell. This is because the tab glue in the prior art has two melting areas, and the temperature difference between the melting peaks of the two melting areas is large, which makes the adhesion between the glue layers in the tab glue low, and it is easy to stratify when immersed in electrolyte.

[0032] In order to improve the adhesion between the layers of the insulating adhesive and at the same time make the insulating adhesive have the performance of high-temperature opening, the insulating adhesive disclosed in the present invention includes at least three melting regions, and the melting peaks of the three melting regions are limited to a specific range, the melting peak a1 of the first melting region is 95°C-115°C (for example, 95°C, 100°C, 105°C, 110°C, 115°C), the melting peak a2 of the second melting region is 115°C-130°C (for example, 115°C, 118°C, 120°C, 122°C, 125°C, 128°C, 13 0°C), the melting peak a3 of the third melting region is 140°C-165°C (for example, 140°C, 145°C, 150°C, 155°C, 160°C, 165°C), and the temperature T3 of the melting peak a3 of the third melting region and the temperature T1 of the melting peak a1 of the first melting region satisfy the following relationship: b=T3-T1, where the unit of b is °C, wherein b is 25°C-70°C (for example, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C). In the present disclosure, the melting peak refers to the melting endothermic peak.

[0033] The insulating adhesive disclosed herein includes at least three melting regions, and when the melting peaks of the three melting regions are confined within the aforementioned specific range, the temperatures of the melting peaks of the three melting regions indicate the presence of a second melting region between the first and third melting regions, which have a larger temperature difference. The melting peak a2 of the second melting region has a smaller temperature difference than the melting peak a1 of the first melting region, and the melting peak a2 of the second melting region has a smaller temperature difference than the melting peak a1 of the third melting region. The transition of the second melting region connects the lower-temperature first melting region with the higher-temperature third melting region, thereby improving the bonding performance between the layers of the insulating adhesive layer and preventing delamination of the insulating adhesive when immersed in electrolyte. Furthermore, when the melting peak a1 of the first melting region is confined within the aforementioned specific range, the first melting region has a lower Vicat transition point and a lower heat deformation temperature. Compared to conventional tab adhesives, the first melting region is more susceptible to thermal deformation at the same ambient temperature. This ensures that when the battery experiences thermal runaway (when the battery temperature reaches 100-120°C), the insulating adhesive melts to form a heat dissipation channel, thereby improving battery safety. At the same time, when the difference b between the temperature T3 of the melting peak a3 of the third melting region and the temperature T1 of the melting peak a1 of the first melting region is limited to a specific range, the crystallization peaks between the molecules between the adhesive layers of the insulating adhesive can be made closer, the cross-linking degree between the molecules is increased, and the crystallinity between the materials of the adhesive layers is increased, thereby improving the bonding performance between the adhesive layers and making the adhesive layers more tightly bonded, avoiding stratification during the electrolyte immersion process, resulting in an excessively high water vapor transmission rate, thereby avoiding the problem of battery swelling and leakage. At the same time, it can also prevent the insulating adhesive from being excessively melted, thereby avoiding the metal layer in the battery packaging film from being too close to the conductive material in the battery, causing a short circuit.

[0034] In the present disclosure, by defining the melting region of the insulating adhesive, the melting peak of the melting region, and the difference between the melting peak temperatures, the insulating adhesive has achieved higher bonding performance and high-temperature opening performance than the prior art. To further enhance the effect, one or more of these technical features may be further optimized.

[0035] In one embodiment, b is 40° C.-60° C. Limiting b to the above specific range can further improve the bonding performance of the insulating adhesive and further improve the safety performance of the battery.

[0036] In one embodiment, the insulating adhesive includes at least a first adhesive layer and a second adhesive layer, the second adhesive layer being located on a surface of one side of the first adhesive layer, and the melting point of the first adhesive layer being 95°C-130°C (e.g., 95°C, 100°C, 105°C, 110°C, 115°C, 120°C, 125°C, 130°C). In this disclosure, the melting point refers to the temperature corresponding to the peak value of the melting endothermic peak during heating.

[0037] In one embodiment, the melting point of the first adhesive layer is 100° C.-110° C.

[0038] In one embodiment, the melting point of the second adhesive layer is 140°C-170°C (e.g., 140°C, 145°C, 150°C, 155°C, 160°C, 165°C, 170°C). Limiting the melting point of the second adhesive layer to this specific range can prevent the second adhesive layer from excessively melting during the heating process of the sealing head, which could result in contact between the conductive material and the metal layer of the packaging film, causing a short circuit.

[0039] In one embodiment, the melting point of the second adhesive layer is 155° C.-165° C.

[0040] As shown in FIG. 2 , the insulating adhesive 4 includes two adhesive layers, a first adhesive layer 41 and a second adhesive layer 42 , wherein the second adhesive layer 42 is located on a surface of one side of the first adhesive layer 41 .

[0041] In one example, the melting point of the first adhesive layer includes a melting peak a1 of the first melting region and a melting peak a2 of the second melting region.

[0042] In one example, the melting point of the second adhesive layer includes the melting peak a3 of the third melting region.

[0043] When the insulating adhesive comprises two adhesive layers, the insulating adhesive includes three melting regions: the first adhesive layer includes a first melting region and a second melting region, and the second adhesive layer includes a third melting region. In this case, because the first adhesive layer includes the second melting region, the temperature difference between the melting peaks of the first and second adhesive layers is small. Therefore, the insulating adhesive comprising two adhesive layers has high adhesion between the adhesive layers, and the insulating adhesive does not delaminate when immersed in the electrolyte.

[0044] The width of the first adhesive layer and the width of the second adhesive layer can be the same or different. In the present disclosure, as shown in FIG4 , the width direction a of the adhesive layer is perpendicular to the direction in which the adhesive layer is wound.

[0045] In one example, the width of the second adhesive layer is smaller than the width of the first adhesive layer.

[0046] In one example, the insulating adhesive includes a third adhesive layer, which is located on a surface of the second adhesive layer away from the first adhesive layer. The insulating adhesive satisfies: the melting point of the second adhesive layer is greater than the melting point of the third adhesive layer, and / or the melting point of the second adhesive layer is greater than the melting point of the first adhesive layer.

[0047] In one example, the insulating adhesive satisfies the following conditions: the melting point of the second adhesive layer is greater than the melting point of the third adhesive layer, and the melting point of the second adhesive layer is greater than the melting point of the first adhesive layer. When the melting points of the first adhesive layer, the second adhesive layer, and the third adhesive layer in the insulating adhesive satisfy the above-mentioned specific relationship, compared with conventional ear glue, the first adhesive layer and the third adhesive layer have a low heat deformation temperature (low melting point). At the same temperature, the first adhesive layer and the third adhesive layer are more susceptible to heat deformation. The third adhesive layer and the inner layer of the packaging film adjacent to the third adhesive layer are hot-melted and then cooled and recrystallized, which can improve intermolecular cross-linking and enhance the bonding strength between the insulating adhesive and the inner layer of the packaging film, thereby preventing leakage from the edge sealing opening during battery cell dropping and high-frequency vibration. At the same time, the high-temperature layer of the second adhesive layer (with a higher melting point) can prevent excessive melting and avoid the metal layer of the packaging film being too close to the conductive material, causing a short circuit. When the battery cell reaches a high temperature of 100-120°C (at this time, thermal runaway occurs in the battery cell), the first adhesive layer and the conductive material, and the third adhesive layer and the inner layer of the packaging film melt first, and the heat sealing tension suddenly decreases, so that the packaging film at the conductive material and the insulating adhesive covering the surface of the conductive material melt opening form a heat dissipation channel, thereby improving the safety performance of the battery. That is, when the battery cell has not experienced thermal runaway, the insulating glue and the packaging film, as well as the insulating glue and the conductive material, are tightly bonded, providing a closed space for the battery cell. When the battery cell has experienced thermal runaway, the first and third layers of the insulating glue melt first, and the bonding force between the insulating glue and the packaging film and the conductive material at the conductive material site is greatly reduced, so that the thermal impact caused by thermal runaway inside the battery cell can break open the sealing position of the conductive material to form an opening, providing a heat dissipation channel for the battery cell, thereby preventing thermal runaway of the battery cell and improving the safety performance of the battery.

[0048] According to a specific embodiment, the melting point of the third adhesive layer is 95°C-130°C (e.g., 95°C, 100°C, 105°C, 110°C, 115°C, 120°C, 125°C, 130°C). Limiting the melting point of the third adhesive layer to this specific range can enhance the metal affinity of the third adhesive layer, thereby improving the bonding performance between the third adhesive layer and the inner film of the packaging film.

[0049] In one embodiment, the melting point of the third adhesive layer is 100° C.-125° C.

[0050] In one embodiment, the difference h between the melting point of the third adhesive layer and the melting point of the first adhesive layer is between -5°C and 25°C (e.g., -5°C, -3°C, 0°C, 3°C, 5°C, 10°C, 15°C, 20°C, 25°C). When the difference between the melting point of the third adhesive layer and the melting point of the first adhesive layer is limited to the above-mentioned specific range, the melting and thermal deformation of the first and third adhesive layers are substantially synchronized. At the same temperature, the packaging film is more likely to melt and cool and crystallize with the third adhesive layer, and the bonding strength is stronger, thereby improving the room-temperature sealing performance of the battery cell. At the same time, when the battery cell experiences thermal runaway at high temperature, the interface between the first adhesive layer and the conductive material and the fusion interface between the third adhesive layer and the packaging film can melt first, thereby reducing the tensile force of the overall sealing interface between the packaging film and the conductive material, making the interface more easily open, providing a heat dissipation channel, and preventing battery fire.

[0051] It is understood that the melting point of the third adhesive layer may be higher than the melting point of the first adhesive layer, or the melting point of the third adhesive layer may be lower than the melting point of the first adhesive layer. When the difference between the melting point of the third adhesive layer and the melting point of the first adhesive layer is a negative value, it indicates that the melting point of the third adhesive layer is lower than the melting point of the first adhesive layer; when the difference between the melting point of the third adhesive layer and the melting point of the first adhesive layer is a positive value, it indicates that the melting point of the third adhesive layer is higher than the melting point of the first adhesive layer.

[0052] In one example, the melting point of the third adhesive layer includes a melting peak a1 of the first melting region and a melting peak a2 of the second melting region.

[0053] As shown in FIG. 3 , the insulating adhesive 4 includes three adhesive layers, and the third adhesive layer 43 is located on a surface of the second adhesive layer 42 away from the first adhesive layer 41 .

[0054] When the insulating adhesive comprises three adhesive layers, the insulating adhesive comprises three melting regions: the first adhesive layer comprises a first melting region and a second melting region, the second adhesive layer comprises a third melting region, and the third adhesive layer comprises a first melting region and a second melting region. In this case, both the first and third adhesive layers comprise a second melting region, and the temperature difference between the melting peaks of the first, third, and second adhesive layers is small. Therefore, the insulating adhesive comprising three adhesive layers has high adhesion between the adhesive layers, and the insulating adhesive does not delaminate when immersed in electrolyte.

[0055] In one example, the first adhesive layer includes a first modified resin.

[0056] In one example, the first modified resin includes one or more of maleic anhydride modified polypropylene, acrylic acid modified polypropylene, metallocene modified polypropylene, propylene-ethylene copolymer, and butene-propylene copolymer.

[0057] In one embodiment, the first modified resin includes a first modified resin A1 and a first modified resin A2, wherein the melting point d1 of the first modified resin A1 is 95°C ≤ d1 ≤ 115°C, and the melting point d2 of the first modified resin A2 is 115°C < d2 ≤ 130°C. Based on the total weight of the first adhesive layer, the weight content of the first modified resin A1 is ≥ 50wt% (for example, 50wt%, 50.5wt%, 55wt%, 60wt%). %, 65wt%, 70wt%, 75wt%, 80wt%, 85wt%, 90wt%, 95wt%, 100wt%), and the weight content of the first modified resin A2 is ≤50wt% (for example, 0wt%, 0.5wt%, 1wt%, 5wt%, 10wt%, 15wt%, 20wt%, 25wt%, 30wt%, 35wt%, 40wt%, 45wt%, 49.5wt%, 50wt%). When the weight content of the first modified resin A1 in the first adhesive layer is 100wt%, it means that the first adhesive layer is the first modified resin A1. When the weight content of the first modified resin A2 in the first adhesive layer is 0wt%, it means that the first modified resin A2 does not exist in the first adhesive layer.

[0058] From the melting points of the first modified resin A1 and the first modified resin A2, it can be seen that the melting point of the first adhesive layer includes the melting peak a1 of the first melting region and the melting peak a2 of the second melting region.

[0059] In one example, the third adhesive layer includes a second modified resin.

[0060] In one example, the second modified resin is selected from one or more of maleic anhydride modified polypropylene, acrylic acid modified polypropylene, metallocene modified polypropylene, propylene-ethylene copolymer, and butene-propylene copolymer.

[0061] In one embodiment, the third adhesive layer includes a second modified resin, the third adhesive layer includes a second modified resin C1 and a second modified resin C2, wherein the melting point f1 of the second modified resin C1 is 95°C ≤ f1 ≤ 115°C, and the melting point f2 of the second modified resin C2 is 115°C < f2 ≤ 130°C. Based on the total weight of the third adhesive layer, the weight content of the second modified resin C1 is ≥ 50wt% (for example, 50wt%, 50.5wt%, 55wt%). %, 60wt%, 65wt%, 70wt%, 75wt%, 80wt%, 85wt%, 90wt%, 95wt%, 100wt%), and the weight content of the second modified resin C2 is ≤50wt% (for example, 0wt%, 0.5wt%, 1wt%, 5wt%, 10wt%, 15wt%, 20wt%, 25wt%, 30wt%, 35wt%, 40wt%, 45wt%, 49.5wt%, 50wt%). When the weight content of the second modified resin C1 in the third adhesive layer is 100wt%, it means that the third adhesive layer is the second modified resin C1. When the weight content of the second modified resin C2 in the third adhesive layer is 0wt%, it means that the second modified resin C2 is not present in the third adhesive layer.

[0062] From the melting points of the second modified resin C1 and the second modified resin C2, it can be seen that the melting point of the third adhesive layer includes the melting peak a1 of the first melting region and the melting peak a2 of the second melting region.

[0063] The width of the first adhesive layer, the width of the second adhesive layer, and the width of the third adhesive layer may be the same or different.

[0064] In one example, the width of the second adhesive layer is smaller than the width of the first adhesive layer, and / or the width of the second adhesive layer is smaller than the width of the first adhesive layer.

[0065] In one example, the second layer of adhesive includes one or more of polypropylene, block polypropylene and copolymer polypropylene; wherein the block polypropylene includes alternating propylene and ethylene segments and / or alternating butene and propylene segments, and the copolymer polypropylene includes ethylene and / or butene and propylene copolymers.

[0066] A second aspect of the present disclosure provides a battery, which includes the insulating glue described in the first aspect.

[0067] In one embodiment, the battery includes a pole piece assembly and a packaging film, the pole piece assembly includes a pole piece and a pole piece conductive material, the pole piece includes a current collector and an active material layer located on one side or both sides of the current collector, the pole piece conductive material is located at one end of the current collector, the first end of the conductive material is a welding end, the welding end is welded to the current collector, the second end opposite to the first end is a protruding end, a glue coating area is formed between the welding end and the protruding end, an insulating glue is provided on the glue coating area, the insulating glue covers the surface of the conductive material, and the insulating glue is provided on the surface of the conductive material. The surface of the first adhesive layer in the insulating adhesive away from the second adhesive layer is adjacent to the conductive material, the packaging film and the insulating adhesive are connected together to form a sealed shell, and the pole piece assembly is located in the enclosed space formed by the sealed shell, the packaging film includes an inner film layer connected to the second adhesive layer or the third adhesive layer in the insulating adhesive, a metal layer located on the surface of the inner film layer, and an outer film layer located on the surface of the metal layer, the inner film layer includes a first film layer directly connected to the second adhesive layer or the third adhesive layer in the insulating adhesive and a second film layer located on the surface of the first film layer, and the melting point of the first film layer is 120°C-165°C.

[0068] As shown in Figure 4, the electrode assembly includes a electrode and a electrode conductive material. The electrode includes a current collector 1 and an active material layer 2 located on one side or both sides of the current collector 1. The electrode conductive material 3 is located at one end of the current collector 1. The first end of the conductive material 3 is a welding end 311, and the welding end 311 is welded to the current collector 1. The second end opposite to the first end is a probe end 312. A glue coating area is formed between the welding end and the probe end. An insulating glue 4 is provided on the glue coating area. The insulating glue 4 covers the surface of the conductive material 3. The surface of the first glue layer 41 in the insulating glue away from the second glue layer 42 is adjacent to the conductive material 3.

[0069] In one example, the electrode sheet includes a positive electrode sheet and / or a negative electrode sheet.

[0070] In one example, the positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer located on one side or both sides of the positive electrode current collector.

[0071] In one example, the positive electrode current collector includes aluminum or an aluminum alloy.

[0072] In one example, the negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer located on one side or both sides of the negative electrode current collector.

[0073] In one example, the negative electrode current collector includes nickel, nickel-plated copper, a nickel alloy, or a copper alloy.

[0074] In one example, the inner film layer includes one or more of polypropylene, ethylene propylene copolymer, maleate-modified polypropylene, and butene propylene copolymer.

[0075] In one example, the metal layer includes aluminum, copper, or stainless steel.

[0076] In one embodiment, the outer film layer is a protective layer and includes one or more of polyamide (PA), polyethylene terephthalate (PET) and polyethylene naphthalate (PEN).

[0077] In one example, the melting point of the first film layer is 120°C-165°C (e.g., 120°C, 125°C, 130°C, 135°C, 140°C, 145°C, 150°C, 155°C, 160°C, 165°C).

[0078] In one example, the melting point of the first film layer is 130°C-145°C.

[0079] In one embodiment, the difference between the melting point of the first film layer and the melting point of the third adhesive layer is -5°C to 40°C (for example, -5°C, -3°C, 0°C, 3°C, 5°C, 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, 40°C). When the difference between the melting point of the first film layer and the melting point of the third adhesive layer falls within the above-mentioned specific range, at the same heat sealing temperature, the melting points of the first film layer and the third adhesive layer are low and relatively close, and recrystallization after heat melting occurs, which increases intermolecular crosslinking and bonding strength between the two, thereby improving the safety performance of the battery cell and preventing leakage caused by edge sealing openings during battery cell drops or high-frequency vibrations.

[0080] It is understood that the melting point of the first film layer may be higher than the melting point of the third adhesive layer, or the melting point of the first film layer may be lower than the melting point of the third adhesive layer. When the difference between the melting points of the first film layer and the third adhesive layer is a negative value, it indicates that the melting point of the first film layer is lower than the melting point of the third adhesive layer; when the difference between the melting points of the first film layer and the third adhesive layer is a positive value, it indicates that the melting point of the first film layer is higher than the melting point of the third adhesive layer.

[0081] In one example, the insulating adhesive satisfies: the melting point of the second adhesive layer is greater than the melting point of the third adhesive layer, and the melting point of the second adhesive layer is greater than the melting point of the first adhesive layer, and the difference between the melting point of the third adhesive layer and the melting point of the first adhesive layer is -5°C to 25°C, and the difference between the melting point of the first film layer and the melting point of the third adhesive layer is -5°C to 40°C.

[0082] In one example, the first film layer includes modified polypropylene and / or propylene ethylene copolymer.

[0083] In one example, the modified polypropylene includes one or more of maleic anhydride modified polypropylene, metallocene modified polypropylene, ethylene propylene copolymer, and silane coupling modified polypropylene.

[0084] In one example, the heat sealing tension between the packaging film and the insulating adhesive is Y±0.5, expressed in N / mm, and the temperature of the battery is T, expressed in °C. The battery satisfies the following relationship: Y=-0.04572×T+5.779, where T is 20°C-125°C (for example, 20°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 125°C). It can be seen from the above relationship that the heat-sealing tension Y between the packaging film and the insulating adhesive decreases with increasing temperature. Therefore, when thermal runaway occurs in the battery cell, the heat-sealing tension between the packaging film and the insulating adhesive is already very small (for example, when the battery temperature T is 110°C, Y = -0.04572×110+5.779 = 0.7498N / mm, and the heat-sealing tension is 0.7498±0.5). At this time, the heat generated inside the battery cell is sufficient to break the connection between the packaging film and the insulating adhesive, thereby providing a channel for heat diffusion and improving the safety performance of the battery.

[0085] The heat seal tensile force between the packaging film and the insulating adhesive can be Y ± 0.5, in N / mm. Because the measured value of the heat seal tensile force between the packaging film and the insulating adhesive varies depending on the sampling location, a tolerance of ± 0.5 is added to Y to ensure consistency with actual conditions.

[0086] It should be noted that the numerical expressions such as "first", "second", and "third" in this disclosure are only used to distinguish different substances or usage methods, and do not represent a difference in order.

[0087] The present disclosure will be described in detail below through examples. The examples described in this disclosure are only a portion of the examples of the present disclosure, not all of the examples. Based on the examples in this disclosure, all other examples obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this disclosure.

[0088] Example I is used to illustrate the insulating adhesive disclosed herein.

[0089] Example 1-1

[0090] The first adhesive layer comprises: 80 parts by weight of the first modified resin A1 (maleic anhydride-modified polypropylene, melting point d1 of 105.4°C) and 20 parts by weight of the first modified resin A2 (propylene copolymer, melting point d2 of 120.8°C).

[0091] The composition of the second adhesive layer: copolymerized polypropylene (melting point 161.5° C.), 100 parts by weight.

[0092] The insulating adhesive has a two-layer structure, and the melting point of the first adhesive layer is 105.4°C & 120.8°C (that is, the first adhesive layer includes a first melting region and a second melting region, wherein the melting peak temperature T1 of the first melting region is 105.4°C, and the melting peak temperature T2 of the second melting region is 120.8°C);

[0093] The melting point of the second adhesive layer is 161.5° C. (ie, the second adhesive layer includes a third melting region, and the temperature T3 of the melting peak of the third melting region is 161.5° C.).

[0094] Example I-2 group

[0095] This set of examples is used to illustrate the effects of changing b by changing the ratio of monomers of maleic anhydride-modified polypropylene in the first subbing layer to change T1 and / or by changing the ratio of monomers of copolymerized polypropylene in the second subbing layer to change T3.

[0096] This example group was carried out with reference to Example I-1, except that b was changed by changing T1 and / or T3, as shown in Table I-1.

[0097] Example 1-3 group

[0098] Example I-3a

[0099] The composition of the first adhesive layer is as follows: refer to the first adhesive layer in Example I-1;

[0100] The composition of the second adhesive layer is as follows: refer to the second adhesive layer in Example I-1;

[0101] The third adhesive layer comprises 80 parts by weight of the second modified resin C1 (maleic anhydride modified polypropylene, melting point f1 is 105.4° C.) and 20 parts by weight of the second modified resin C2 (propylene copolymer, melting point f2 is 120.8° C.).

[0102] The insulating adhesive has a three-layer structure, and the first adhesive layer is made by referring to the first adhesive layer in Example I-1;

[0103] The second adhesive layer is prepared by referring to the second adhesive layer in Example I-1;

[0104] The melting points of the third adhesive layer are 105.4°C and 120.8°C (i.e., the third adhesive layer includes a first melting region and a second melting region, wherein the melting peak temperature T1 of the first melting region is 105.4°C, and the melting peak temperature T2 of the second melting region is 120.8°C). See Table I-1 for details.

[0105] Example I-3b

[0106] The same procedure is carried out as in Example I-3a, except that T1 is changed by changing the ratio of monomers of maleic anhydride-modified polypropylene in the first adhesive layer and T2 is changed by changing the ratio of monomers of propylene-ethylene copolymer. For details, see Table I-1.

[0107] Example I-3c

[0108] The process was carried out with reference to Example I-3a, except that the weight content of the maleic anhydride-modified polymer having a melting point d1 of 105.4°C in the first adhesive layer was adjusted to 100%, and the weight content of the propylene copolymer having a melting point f2 of 120.8°C in the third adhesive layer was adjusted to 100%. For details, see Table I-1.

[0109] Example I-3d

[0110] The process was carried out with reference to Example I-3b, except that the weight content of the maleic anhydride-modified polymer having a melting point d1 of 95.2°C in the first adhesive layer was adjusted to 100%, and the weight content of the propylene copolymer having a melting point f2 of 130.5°C in the third adhesive layer was adjusted to 100%. For details, see Table I-1.

[0111] Example 1-3e

[0112] The same procedure is carried out as in Example I-3d, except that d1 is changed by changing the ratio of the monomers of maleic anhydride-modified polypropylene in the first adhesive layer, and f1 is changed by changing the ratio of the monomers of maleic anhydride-modified polypropylene in the third adhesive layer. For details, see Table I-1.

[0113] Comparative Example I-1

[0114] The same process is carried out as in Example I-3c, except that the insulating adhesive does not include a third adhesive layer. For details, see Table I-1.

[0115] Table I-1a

[0116] Table I-1b

[0117] - means it does not exist;

[0118] h represents the difference between the melting point of the third adhesive layer and the melting point of the first adhesive layer.

[0119] Preparation Example I-1

[0120] (1) Positive electrode assembly

[0121] The positive electrode active material (97.6 parts by weight of lithium cobalt oxide), the conductive agent (1.35 parts by weight of conductive carbon black), the binder (1.05 parts by weight of PVDF) and the solvent (NMP) are stirred and evenly mixed, and then coated on the surfaces of both sides of the positive electrode current collector (aluminum foil with a thickness of 10 μm) to form a positive electrode active material layer; it is dried and roll-pressed to obtain a positive electrode sheet, and the area of ​​the positive electrode sheet not coated with the positive electrode active material layer can be welded with the positive electrode conductive material.

[0122] The positive electrode conductive material was aluminum. The first end of the positive electrode conductive material served as a welding end, which was welded to the positive electrode current collector. The second end, opposite the first end, served as a protruding end. A glue-coated region was formed between the welding end and the protruding end. Insulating adhesive was applied to the glue-coated region, covering the surface of the positive electrode conductive material. The surface of the first adhesive layer, distal from the second adhesive layer, was adjacent to the positive electrode conductive material. The length of the positive electrode conductive material at the welding end of the positive electrode current collector was 30 mm. The insulating adhesive used was the same as that used in Example 1 and Comparative Example I-1, with specifications of 0.1 mm thick, 6 mm wide, and 2.5 mm wide per side.

[0123] (2) Negative electrode sheet assembly: The negative electrode active material (97 parts by weight of graphite), conductive agent (1.5 parts by weight of conductive carbon black), binder (1.5 parts by weight of styrene-butadiene rubber) and solvent (deionized water) are uniformly mixed and then coated on both sides of the negative electrode base fluid (copper foil with a thickness of 10 μm); it is dried and rolled to obtain a negative electrode sheet. The area of ​​the negative electrode sheet not coated with the negative electrode active material layer can be welded with the negative electrode conductive material.

[0124] The negative electrode conductive material is copper-plated nickel. The first end of the negative electrode conductive material is a welding end, which is welded to the negative electrode current collector. The second end opposite to the first end is a protruding end. A glue coating area is formed between the welding end and the protruding end. An insulating glue is provided on the glue coating area. The insulating glue covers the surface of the negative electrode conductive material. The surface of the first glue layer in the insulating glue away from the second glue layer is adjacent to the negative electrode conductive material. The length of the negative electrode conductive material at the negative electrode current collector welding end is 30 mm. The insulating glue uses the insulating glue of Example I and Comparative Example I-1, respectively, with specifications of 0.1 mm thick, 6 mm wide, and 2.5 mm wide on one side.

[0125] (3) Diaphragm

[0126] Polyethylene substrate with a thickness of 7 μm.

[0127] (4) Electrolyte

[0128] In an argon-filled glove box (H2O <0.1ppm, O2 <0.1ppm), the organic solvent is mixed thoroughly, and then the fully dried lithium salt is quickly added. After dissolving, the additive is added to obtain the desired electrolyte. The electrolyte comprises 10 parts by weight of the lithium salt, 85 parts by weight of the organic solvent (40 parts by weight of ethylene carbonate (EC), 40 parts by weight of diethyl carbonate (DEC), and 5 parts by weight of fluoroethylene carbonate (FEC)), and 5 parts by weight of the additive (PS).

[0129] (5) Packaging film

[0130] Aluminum-plastic film.

[0131] (6) Preparation of batteries

[0132] The positive electrode sheet assembly of step (1), the negative electrode sheet assembly of step (2) and the separator of step (3) are stacked in the order of positive electrode sheet assembly, separator and negative electrode sheet assembly, and then wound to obtain a battery cell; the battery cell is placed in the packaging film of step (5), the electrolyte of step (4) is injected into the packaging film, and the lithium ion battery is obtained through vacuum packaging, standing, forming, shaping, sorting and other processes.

[0133] Test Example I-1

[0134] 1. Hot box test

[0135] (1) 130℃ hot box test

[0136] At 25°C±3°C, discharge at 0.2C to a cutoff voltage of 3.0V and allow to rest for 10 minutes. Then charge at 0.5C constant current and constant voltage to a maximum voltage of 4.2V with a cutoff current of 0.02C. At 25°C±3°C, test the fully charged voltage, internal resistance, and thickness. Place the fully charged cell in a test chamber and heat it up at a rate of (5±2)°C / min. When the chamber temperature reaches 130°C±2°C, maintain this temperature for 60 minutes. After the test, observe whether the cell ignites. If it ignites, it fails; if it does not, it passes. Each sample is tested ten times, and the results are expressed as "number of passes / 10." For example, "10 / 10" means all 10 tests passed, and "5 / 10" means 5 out of 10 tests passed.

[0137] (2) 135℃ hot box test

[0138] At 25°C±3°C, discharge at 0.2C to a cutoff voltage of 3.0V and allow to rest for 10 minutes. Then charge at 0.5C constant current and constant voltage to a maximum voltage of 4.2V with a cutoff current of 0.02C. At 25°C±3°C, test the fully charged voltage, internal resistance, and thickness. Place the fully charged cell in a test chamber and heat it up at a rate of (5±2)°C / min. When the chamber temperature reaches 135°C±2°C, maintain this temperature for 60 minutes. After the test, observe whether the cell ignites. If it ignites, it fails; if it does not, it passes. Each sample is tested ten times, and the results are expressed as "number of passes / 10." For example, "10 / 10" means all 10 tests passed, and "5 / 10" means 5 out of 10 tests passed.

[0139] (3) 140℃ hot box test

[0140] At 25°C±3°C, discharge at 0.2C to a cutoff voltage of 3.0V and allow to rest for 10 minutes. Then charge at 0.5C constant current and constant voltage to a maximum voltage of 4.2V with a cutoff current of 0.02C. At 25°C±3°C, test the fully charged voltage, internal resistance, and thickness. Place the fully charged cell in a test chamber and heat it up at a rate of (5±2)°C / min. When the chamber temperature reaches 140°C±2°C, maintain this temperature for 60 minutes. After the test, observe whether the cell ignites. If it ignites, it fails; if it does not, it passes. Each sample is tested ten times, and the results are expressed as "number of passes / 10." For example, "10 / 10" means all 10 tests passed, and "5 / 10" means 5 out of 10 tests passed.

[0141] 2. Whole machine drop test

[0142] After installing the battery, discharge it at 0.2C to a cutoff voltage of 3.0V at 25°C±3°C and let it rest for 10 minutes. Then charge it at 0.5C constant current and constant voltage to 50% SOC. Drop it onto granite from a height of 1.5m 20 times on the tab surface. If the cell opens, it fails; if it doesn't, it passes. Each sample is tested ten times, and the results are expressed as "number of passes / 10." For example, "10 / 10" means all 10 tests passed, and "5 / 10" means 5 out of 10 tests passed.

[0143] 3. Sealing test

[0144] At 25°C ± 3°C, discharge at 0.2C to the lower voltage limit (3V), let it stand for 10 minutes, place the battery in a 25°C constant temperature box, and fully charge it (100% SOC) at a constant current of 0.7C. The cut-off current is 0.02C. After full charge, store the battery cell in a 60°C & 95RH (humidity) environment. Test the battery body thickness every 3D. If the expansion rate exceeds 10%, it is considered a failure; if the expansion rate does not exceed 10%, it is considered a pass. Record the pass rate of the battery cell within 30D. Each sample is tested ten times in total, and the results are expressed as "pass number / 10". For example, "10 / 10" means that all 10 tests passed, and "5 / 10" means that 5 out of 10 tests passed.

[0145] 4. Opening test

[0146] At 25°C ± 3°C, discharge at 0.2C to a lower voltage of 3V, let stand for 10 minutes, then place the battery in a 25°C constant temperature chamber and fully charge (100% SOC) at a constant current of 0.7C with a cut-off current of 0.02C. After fully charging, place the battery in 120°C and 130°C environments, respectively. Observe the battery top for 2 minutes to see if it opens or if the electrolyte leaks. Opening or leaking indicates a pass, while no opening or no electrolyte leaking indicates a fail. Each sample is tested ten times, and the results are expressed as "pass number / 10." For example, "10 / 10" means all 10 tests passed, and "5 / 10" means 5 out of 10 tests passed.

[0147] The batteries obtained from Example I and Comparative Example I-1 were subjected to a sealing test, a whole-unit drop test, and a 135° C. hot box test. The results obtained from Example I and Comparative Example I-1 are recorded in Table I-2.

[0148] Table I-2

[0149] As can be seen from Table I-2, it can be seen from the comparative examples and the examples that the batteries made of the insulating adhesive of the examples have improved sealing test pass rates, significantly improved whole machine drop test pass rates, and significantly improved 135°C hot box test pass rates, indicating that the insulating adhesive of the present invention improves the bonding performance and high-temperature opening performance of the insulating adhesive by limiting the melting area of ​​the insulating adhesive and the melting peak and the difference between the melting peak temperatures of the melting area.

[0150] Example II group is used to illustrate the insulating adhesive and packaging film of the present disclosure.

[0151] Example II-1

[0152] The same process was carried out as in Example I-1, except that the melting point of the first film layer in the selected packaging film was 140.8° C., as shown in Table II-1.

[0153] Example II-2

[0154] The same process was carried out as in Example I-1, except that the melting point of the first film layer in the selected packaging film was 120.3° C., as shown in Table II-1.

[0155] Example II-3

[0156] The same process was carried out as in Example I-1, except that the melting point of the first film layer in the selected packaging film was 165.6° C., as shown in Table II-1.

[0157] The batteries obtained in Example II were subjected to a sealing test, a whole-unit drop test, a 130° C. hot box test, and a 140° C. hot box test. The results obtained in Example II are recorded in Table II-1.

[0158] Table II-1

[0159] As can be seen from Table II-1, the examples show that the batteries made of the insulating adhesive and packaging film of the examples have a high passing rate in the sealing test and a high passing rate in the whole-machine drop test, indicating that the battery has a good sealing effect and can provide a closed space for the battery when thermal runaway does not occur; the 130°C and 140°C hot box tests have a high passing rate, indicating that when thermal runaway occurs, the battery can be opened in time to provide heat dissipation for the battery, thereby improving the safety performance of the battery.

[0160] The preferred embodiments of the present disclosure are described in detail above, but the present disclosure is not limited thereto. Within the technical concept of the present disclosure, various simple variations of the technical solution of the present disclosure may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed by the present disclosure and fall within the scope of protection of the present disclosure.

Claims

1. An insulating adhesive, wherein, The insulating adhesive comprises at least three melting regions. Among them, the melting peak a1 of the first melting region is 95°C - 115°C, the melting peak a2 of the second melting region is 115°C - 130°C, and the melting peak a3 of the third melting region is 140°C - 165°C. The temperature T3 of the melting peak a3 of the third melting region and the temperature T1 of the melting peak a1 of the first melting region satisfy the following relational expression: b = T3 - T1, where the unit of b is °C, and b is 25°C - 70°C.

2. The insulating adhesive according to claim 1, wherein, b is 40°C - 60°C; And / or, the insulating adhesive comprises at least a first adhesive layer and a second adhesive layer. The second adhesive layer is located on the surface of one side of the first adhesive layer. The melting point of the first adhesive layer is 95°C - 130°C, and the melting point of the second adhesive layer is 140°C - 170°C.

3. The insulating adhesive according to claim 1 or 2, wherein, The insulating adhesive comprises a third adhesive layer. The third adhesive layer is located on the surface of the second adhesive layer away from the first adhesive layer. The insulating adhesive satisfies that the melting point of the second adhesive layer > the melting point of the third adhesive layer, and / or the melting point of the second adhesive layer > the melting point of the first adhesive layer.

4. The insulating adhesive according to claim 3, wherein The melting point of the third adhesive layer is 95°C - 130°C; And / or, the difference between the melting point of the third adhesive layer and the melting point of the first adhesive layer is -5°C to 25°C.

5. The insulating adhesive according to any one of claims 1-4, wherein, The melting point of the first adhesive layer includes the melting peak a1 of the first melting region and the melting peak a2 of the second melting region; And / or, the melting point of the second adhesive layer includes the melting peak a3 of the third melting region.

6. The insulating adhesive according to any one of claims 3-5, wherein, The melting point of the third adhesive layer includes the melting peak a1 of the first melting region and the melting peak a2 of the second melting region.

7. The insulating adhesive according to any one of claims 1-6, wherein, The first adhesive layer comprises a first modified resin. The first modified resin comprises a first modified resin A1 and a first modified resin A2. Among them, the melting point d1 of the first modified resin A1 is 95°C ≤ d1 ≤ 115°C, and the melting point d2 of the first modified resin A2 is 115°C < d2 ≤ 130°C. Then, based on the total weight of the first adhesive layer, the weight content of the first modified resin A1 is ≥ 50wt%, and the weight content of the first modified resin A2 is ≤ 50wt%.

8. The insulating glue according to any one of claims 3-7, wherein, The third adhesive layer comprises a second modified resin. The third adhesive layer comprises a second modified resin C1 and a second modified resin C2. Among them, the melting point f1 of the second modified resin C1 is 95°C ≤ f1 ≤ 115°C, and the melting point f2 of the second modified resin C2 is 115°C < f2 ≤ 130°C. Then, based on the total weight of the third adhesive layer, the weight content of the second modified resin C1 is ≥ 50wt%, and the weight content of the second modified resin C2 is ≤ 50wt%.

9. The insulating adhesive according to claim 7 or 8, wherein, The first modified resin includes one or more of maleic anhydride modified polypropylene, acrylic acid modified polypropylene, metallocene modified polypropylene, propylene - ethylene copolymer, and butene - propylene copolymer; And / or, the second adhesive layer includes one or more of polypropylene, block polypropylene, and copolymerized polypropylene; among them, the block polypropylene includes alternating propylene - ethylene segments and / or alternating butene - propylene segments, and the copolymerized polypropylene includes ethylene - propylene copolymerization and / or butene - propylene copolymerization.

10. The insulating adhesive according to claim 8 or 9, wherein The second modified resin includes one or more of maleic anhydride modified polypropylene, acrylic acid modified polypropylene, metallocene modified polypropylene, propylene-ethylene copolymer, and butene-propylene copolymer.

11. A battery, characterized in that, The battery includes the insulating adhesive according to any one of claims 1-10.

12. The battery according to claim 11, wherein, The battery includes a pole piece assembly and a packaging film. The pole piece assembly includes a pole piece and a pole piece conductive material. The pole piece includes a current collector and an active material layer located on one or both surfaces of the current collector. The pole piece conductive material is located at one end of the current collector. The first end of the conductive material is a welding end, and the welding end is welded to the current collector. The second end opposite to the first end is a protruding end. A glue application area is formed between the welding end and the protruding end. An insulating adhesive is provided on the glue application area. The insulating adhesive covers the surface of the conductive material. The surface of the first glue layer of the insulating adhesive away from the second glue layer is adjacent to the conductive material. The packaging film is connected to the insulating adhesive to form a sealed shell. The pole piece assembly is located in a closed space formed by the sealed shell. The packaging film includes an inner film layer connected to the second glue layer or the third glue layer of the insulating adhesive, a metal layer located on the surface of the inner film layer, and an outer film layer located on the surface of the metal layer. The inner film layer includes a first film layer directly connected to the second glue layer or the third glue layer of the insulating adhesive and a second film layer located between the first film layer and the metal layer. The melting point of the first film layer is 120°C - 165°C, preferably 130°C - 145°C.

13. The battery according to claim 12, wherein, The difference between the melting point of the first film layer and the melting point of the second glue layer or the third glue layer is -5°C to 40°C; And / or, the first film layer includes modified polypropylene and / or propylene-ethylene copolymer.

14. The battery according to claim 13, wherein, The modified polypropylene includes one or more of maleic anhydride modified polypropylene, metallocene modification, ethylene-propylene copolymer, and silane coupling modified polypropylene.

15. The battery according to any one of claims 12-14, wherein, If the heat seal tensile force between the packaging film and the insulating adhesive is Y ± 0.5, with the unit of N / mm, and the temperature of the battery is T, with the unit of °C, then the battery satisfies the following relationship: Y = -0.04572 × T + 5.779, where T is 20°C - 125°C.

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