Insulating adhesive, tab assembly, battery cell, and electric device
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2025-02-06
- Publication Date
- 2026-08-13
Smart Images
Figure CN2025075971_13082026_PF_FP_ABST
Abstract
Description
Insulating adhesive, electrode assemblies, battery cells and electrical equipment Technical Field
[0001] This application relates to the field of energy storage technology, and in particular to an insulating adhesive, a tab assembly, a battery cell, and an electrical device. Background Technology
[0002] With the continuous updating and development of lithium-ion battery technology, the application fields of lithium-ion batteries are also expanding. As a result, the safety of battery cells is receiving increasing public attention. Battery leakage can easily lead to safety accidents, which poses a certain obstacle to the development of lithium-ion batteries. How to solve the problem of battery cell safety is a difficult problem that the lithium-ion battery industry cannot avoid. Summary of the Invention
[0003] In view of this, it is necessary to provide an insulating adhesive, tab assembly, battery cell, and electrical device to improve packaging reliability.
[0004] This application provides an insulating adhesive comprising a surface layer. The surface layer has a melt index of 4 g / 10 min to 20 g / 10 min at 230°C and a load of 2.16 kg, and a number-average molecular weight (Mn) of 10,000 g / mol to 130,000 g / mol. If the number-average molecular weight of the surface layer is less than 10,000 g / mol, the melt viscosity is too low, which is not conducive to processing and molding, and may lead to excessively high fluidity after melting, reducing the encapsulation reliability of the battery cell under normal temperature conditions. If the number-average molecular weight of the surface layer is greater than 130,000 g / mol, the melt viscosity is too high, which is not conducive to processing and molding, and may lead to increased brittleness of the surface layer, making it prone to cracking under external force. By limiting the number-average molecular weight (Mn) of the surface layer to 10,000 g / mol to 130,000 g / mol, the encapsulation reliability of the battery cell under normal temperature conditions and the mechanical strength of the insulating adhesive are improved. By setting the number-average molecular weight of the surface layer, it is beneficial to control the melt index of the surface layer at 230℃ and 2.16kg load, improve the fluidity of the surface layer after melting, thereby expanding the overflow clumps formed after the surface layer melts, reducing leakage caused by voids and / or air bubbles, improving the encapsulation pull force of the insulating adhesive under normal temperature conditions, and improving the encapsulation reliability of the battery cell under normal temperature conditions. Furthermore, the improved fluidity of the surface layer allows the battery cell to quickly form a pressure relief channel after expansion, improving heat dissipation efficiency and thus enhancing the safety performance of the battery cell.
[0005] In one or more of the above optional embodiments, the melt flow index of the surface layer at 230°C and 2.16 kg load is 6 g / 10 min to 14 g / 10 min, which easily meets the high temperature fluidity requirements and the sealing thickness is easy to control, further improving the packaging reliability and safety performance of the battery cell under normal temperature conditions.
[0006] In one or more of the above optional embodiments, the melt flow index of the surface layer at 230°C and 2.16 kg load is 7.1 g / 10 min to 12 g / 10 min, which makes it easier to meet the high temperature fluidity requirements, and the sealing thickness is easier to control, further improving the packaging reliability and safety performance of the battery cell under normal temperature conditions.
[0007] In one or more of the above optional embodiments, the surface layer has at least a first melting point and a second melting point. The range of the first melting point A is 50℃≤A≤120℃, and the range of the second melting point B is 120℃<B≤170℃. By setting multiple melting point ranges, the surface layer can melt within the temperature range of the first melting point and the second melting point, effectively controlling the melting pressure relief point of the battery cell and improving the heat dissipation efficiency of the battery cell.
[0008] In one or more of the above optional embodiments, the surface layer includes a first crystallinity and a second crystallinity, wherein the first crystallinity is 1%-30% and the second crystallinity is 0.01%-5%. Materials with a high first crystallinity have stronger intermolecular forces and a higher melting point. Materials with a low second crystallinity have weaker intermolecular forces; as the temperature rises, these low-crystallinity components preferentially melt, disrupting the ordered structure. Since these low-crystallinity components are uniformly distributed in the surface layer, their melting accelerates the collapse and melting of the overall surface layer structure. This facilitates controlling the melting of the surface layer within the temperature range of the first and second melting points, effectively regulating the melting and pressure relief point of the battery cell.
[0009] In one or more of the above optional embodiments, the crystallinity of the insulating adhesive is 2%-35%. If the crystallinity of the insulating adhesive is less than 2%, the fluidity after melting is too high, which can easily lead to leakage of the battery cell; if the crystallinity of the insulating adhesive is greater than 35%, the fluidity after melting is low, which affects the formation of rapid pressure relief channels, reduces heat dissipation efficiency, and is not conducive to improving the safety performance of the battery cell. By limiting the total crystallinity of the insulating adhesive to 2%-35%, it is beneficial to control the melting of the insulating adhesive within the temperature range of the first melting point and the second melting point, effectively regulate the melting pressure relief point of the insulating adhesive, facilitate the rapid formation of pressure relief channels in the battery cell, improve heat dissipation efficiency and safety performance, and improve the sealing reliability of the battery cell.
[0010] In one or more of the above optional embodiments, the insulating adhesive includes a base layer, and a surface layer is connected to at least one side of the base layer along the thickness direction of the base layer. The melting point of the base layer is greater than that of the surface layer. The melting point of the base layer is greater than 200°C, which supports the surface layer and reduces the risk of short circuit caused by the melting of the base layer, resulting in contact between the metal layer of the tab and the cell housing or the electrode sheets of different polarities. This is beneficial to improving the insulation of the insulating adhesive.
[0011] In one or more of the above optional embodiments, the melt flow index of the base layer at 230°C and 2.16kg load is 0.1g / 10min-5g / 10min. This reduces the fluidity of the base layer to support the surface layer. The low melt flow index of the base layer helps to reduce the appearance of the exposed insulating adhesive due to heat curling and deformation. At the same time, it is easy to generate Joule heat during the electrode conduction process. The high melting point and low melt flow index of the base layer play a good insulating role and are conducive to improving the sealing performance of the battery cell.
[0012] In one or more of the above optional embodiments, the number average molecular weight of the base layer is at least 70,000 g / mol, which is beneficial to improving the insulation and mechanical strength of the insulating adhesive and reducing damage to the sealing part during the drop process.
[0013] In one or more of the above optional embodiments, the surface layer must satisfy at least one of the following conditions: weight-average molecular weight Mw: 100,000 g / mol - 800,000 g / mol. If the weight-average molecular weight of the surface layer is less than 100,000 g / mol, the mechanical strength of the surface layer is low; if the weight-average molecular weight of the surface layer is greater than 800,000 g / mol, the melt viscosity of the surface layer is too high, which is not conducive to flow. By limiting the weight-average molecular weight Mw of the surface layer to 100,000 g / mol - 800,000 g / mol, the packaging reliability of the battery cell under normal temperature conditions and the mechanical strength of the surface layer are improved. It is beneficial to control the melting point and melt flow index of the surface layer, effectively regulating the melting pressure relief point of the battery cell; Mw / Mn: 3-10, which improves the polydispersity index of the material, broadens the melting point range of the surface layer, increases the proportion of particles in the low melting point range, and adjusts the melt flow index, which is beneficial to increase the fluidity of the material at high temperatures. After reaching the melting point, the surface layer melts rapidly, the surface layer structure collapses to form a pressure relief channel, and the heat dissipation efficiency of the battery cell is improved.
[0014] In one or more of the above optional embodiments, the insulating adhesive satisfies at least one of the following conditions: the surface layer accounts for 30%-44% of the thickness of the insulating adhesive; during the encapsulation process, two second adhesive layers are bonded along the thickness direction of the cell housing and have a first thickness; the portion of the insulating adhesive extending on both sides along the width direction of the tab is bonded and has a second thickness; the insulating adhesive and the tab located on both sides of the thickness direction of the tab have a third thickness; reducing the thickness difference between the first, second, and third thicknesses is beneficial to improving the encapsulation reliability of the cell under normal temperature conditions and is also beneficial to pressure relief; the insulating adhesive includes a base layer, and along the thickness direction of the base layer, at least one side of the base layer is connected to the surface layer; the base layer accounts for 6%-20% of the thickness of the insulating adhesive; this is beneficial to reducing the presence of pore channels in the cell and reducing the risk of leakage and short circuit; the insulating adhesive includes a first adhesive layer, which connects the base layer and the surface layer; the thickness of the first adhesive layer is 1% to 4% of the thickness of the insulating adhesive; this improves the connection strength between the base layer and the surface layer and the encapsulation reliability of the cell under normal temperature conditions.
[0015] An embodiment of this application provides a tab assembly, including a tab and an insulating adhesive as described in any of the above embodiments, wherein the insulating adhesive is disposed on both sides of the tab.
[0016] The embodiments of this application provide a battery cell, including a battery cell housing, an electrode assembly, tabs, and insulating adhesive as described in any of the above embodiments. The battery cell housing includes a main body and a sealing part. The electrode assembly is disposed within the main body. The tabs are connected to the electrode assembly and extend out of the sealing part. The insulating adhesive is disposed on both sides of the tabs and connected to the battery cell housing. The surface layer is bonded to the battery cell housing or the tabs.
[0017] In one or more of the above optional embodiments, the tab includes a first section, a second section, and a third section. At least a portion of the first section is connected to the electrode assembly. The second section is bent and connected to the first section; the second section occupies 5%-70% of the cell thickness. The third section is bent and connected to the second section, with a portion of the third section extending beyond the sealing portion. This helps reduce the risk of the tab breaking during a drop, and the insulating adhesive reduces the risk of short circuits caused by the second section contacting the metal layer of the cell casing or electrodes of different polarities.
[0018] In one or more of the above optional embodiments, at 25°C, the tensile force between the insulating adhesive and the sealing part and / or the electrode tab is in the range of 5N / mm-10N / mm. This improves the encapsulation tensile force and encapsulation reliability of the battery cell under normal temperature conditions.
[0019] In one or more of the above optional embodiments, at 95°C, the tensile force between the insulating adhesive and the sealing part and / or the electrode tab ranges from 0.2 N / mm to 2 N / mm. Under operating conditions at 95°C, the battery cell's encapsulation reliability still meets requirements, reducing the occurrence of leakage.
[0020] In one or more of the above optional embodiments, at 120°C, the tensile force between the insulating adhesive and the sealing part and / or the tab ranges from 0.01 N / mm to 0.2 N / mm. This further facilitates the rapid formation of a pressure relief channel after the cell expands, improves heat dissipation efficiency, and thus enhances the safety performance of the cell.
[0021] In one or more of the above optional embodiments, the sealing part includes two second adhesive layers, the sealing part includes a first region that does not overlap with the insulating adhesive, the two second adhesive layers located in the first region are bonded together, the insulating adhesive includes a base layer that connects the surface layer, in the first region, twice the thickness of the base layer is less than the sum of the thicknesses of the two second adhesive layers, or, the sum of the thicknesses of the base layers on both sides of the electrode tab is less than the sum of the thicknesses of the two second adhesive layers, thereby reducing the presence of pore channels in the battery cell housing and reducing the risk of leakage and short circuit.
[0022] In one or more of the above optional embodiments, the sealing part further includes an overflow ball, which is located between the tab and the second adhesive layer. The length of the overflow ball along the direction of the tab is 0.1mm-0.5mm, which increases the sealing width and helps to improve the packaging pull force and packaging reliability of the battery cell under normal temperature conditions.
[0023] Embodiments of this application provide an electrical device including the battery cell from any of the above embodiments. Attached Figure Description
[0024] Figure 1 shows a schematic diagram of the electrode assembly in some embodiments.
[0025] Figure 2 shows a partial schematic diagram of the battery cell in some embodiments.
[0026] Figure 3 shows a cross-sectional schematic diagram of the battery cell in some embodiments.
[0027] Figure 4 shows a schematic diagram of the electrical equipment in some embodiments.
[0028] Explanation of key component symbols: Insulating adhesive 100, Base layer 10, Surface layer 20, First adhesive layer 30, Electrode assembly 200, Electrode 210, First section 211, Second section 212, Third section 213, Cell 300, Cell housing 310, Main body 310a, Sealing part 310b, Second adhesive layer 311, Metal layer 312, Outer layer 313, Electrode assembly 320, First electrode 321, Second electrode 322, Separating membrane 323, First area 301, Electrical equipment 400
[0029] The following specific embodiments will further illustrate this application in conjunction with the above-described accompanying drawings. Detailed Implementation
[0030] The following specific embodiments are exemplary and not limiting, and are intended to provide a basic understanding of this application, and are not intended to identify key or decisive elements of this application or limit the scope of protection. As long as there is no structural conflict, the technical features mentioned in the various embodiments can be combined in any manner.
[0031] When a component is considered to be "located" on another component, it can be directly on the other component or may also be interspersed with other components. When a component is considered to be "connected" to another component, it can be directly connected to the other component or may also be interspersed with other components.
[0032] Unless otherwise defined, the term "multiple" in this document, when used to describe the number of components, specifically means that the component is two or more.
[0033] Some embodiments of this application will now be described with reference to the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.
[0034] Please refer to Figures 1 to 3. This application provides an insulating adhesive 100, including a base layer 10 and a surface layer 20. The surface layer 20 is connected to at least one side of the base layer 10 along the thickness direction of the base layer 10.
[0035] Optionally, a surface layer 20 is connected to one side of the base layer 10 along the thickness direction of the base layer 10.
[0036] Optionally, a surface layer 20 is connected to both sides of the base layer 10 along the thickness direction. This application uses the example of a base layer 10 having a surface layer 20 connected to both sides for illustration.
[0037] In some embodiments, the melt flow index of surface layer 20 at 230°C and a load of 2.16 kg is 4 g / 10 min to 20 g / 10 min. If the melt flow index of surface layer 20 at 230°C and a load of 2.16 kg is less than 4 g / 10 min, the surface layer 20 becomes too fluid after melting, which is not conducive to expanding the overflow clumps formed after the surface layer 20 melts, reducing the encapsulation pull force and encapsulation reliability of cell 300 under normal temperature conditions, and also affecting the rapid formation of pressure relief channels after the cell 300 expands, reducing heat dissipation efficiency and hindering the improvement of the safety performance of cell 300. If the melt flow index of surface layer 20 at 230°C and a load of 2.16 kg is greater than 20 g / 10 min, the surface layer 20 becomes too fluid after melting, affecting the sealing performance of cell 300 and easily leading to leakage of cell 300.
[0038] Optionally, the melt flow index of the surface layer 20 at 230°C and 2.16 kg load can be any one or any combination of two of the following: 4 g / 10 min, 5 g / 10 min, 6 g / 10 min, 7 g / 10 min, 8 g / 10 min, 9 g / 10 min, 10 g / 10 min, 11 g / 10 min, 12 g / 10 min, 13 g / 10 min, 14 g / 10 min, 15 g / 10 min, 16 g / 10 min, 17 g / 10 min, 18 g / 10 min, 19 g / 10 min, and 20 g / 10 min.
[0039] In some embodiments, the number-average molecular weight Mn of the surface layer 20 is 10,000 g / mol to 130,000 g / mol. If the number-average molecular weight of the surface layer 20 is less than 10,000 g / mol, the melt viscosity of the surface layer 20 is too low, which is not conducive to processing and molding, and may easily lead to excessive fluidity of the surface layer 20 after melting, reducing the packaging reliability of the battery cell 300 under normal temperature conditions. If the number-average molecular weight of the surface layer 20 is greater than 130,000 g / mol, the melt viscosity of the surface layer 20 is too high, which is not conducive to processing and molding, and may easily lead to increased brittleness of the surface layer 20, making it prone to cracking under external force.
[0040] Optionally, the number-average molecular weight of the surface layer 20 is any one or any combination of 10,000 g / mol, 20,000 g / mol, 30,000 g / mol, 40,000 g / mol, 50,000 g / mol, 60,000 g / mol, 70,000 g / mol, 80,000 g / mol, 90,000 g / mol, 100,000 g / mol, 110,000 g / mol, 120,000 g / mol, and 130,000 g / mol.
[0041] By setting the number-average molecular weight of surface layer 20, it is beneficial to control the melt index of surface layer 20 at 230℃ and 2.16kg load, improve the fluidity of surface layer 20 after melting, thereby expanding the overflow clumps formed after surface layer 20 melts, reducing leakage caused by voids and / or air bubbles, improving the encapsulation pull force of insulating adhesive 100 under normal temperature conditions, and improving the encapsulation reliability of battery cell 300 under normal temperature conditions. Furthermore, the improved fluidity of surface layer 20 allows battery cell 300 to quickly form pressure relief channels after expansion, improving heat dissipation efficiency and thus enhancing the safety performance of battery cell.
[0042] In some embodiments, the melt flow index of the surface layer 20 at 230°C and 2.16 kg load is 6 g / 10 min to 14 g / 10 min, which easily meets the high-temperature fluidity requirements and the sealing thickness is easy to control, further improving the packaging reliability and safety performance of the battery cell under normal temperature conditions.
[0043] In some embodiments, the melt flow index of the surface layer 20 at 230°C and 2.16 kg load is 7.1 g / 10 min to 12 g / 10 min, which makes it easier to meet the high-temperature fluidity requirements and the sealing thickness is easier to control, further improving the packaging reliability and safety performance of the battery cell under normal temperature conditions.
[0044] In some embodiments, the melt flow index of the base layer 10 at 230°C and a load of 2.16 kg is 0.1 g / 10 min to 5 g / 10 min. This reduces the fluidity of the melt in the base layer 10 to support the surface layer 20, which is beneficial to improving the sealing of the battery cell 300 and the insulation of the insulating adhesive 100. The low melt flow index of the base layer 10 helps to reduce the appearance of the exposed part of the insulating adhesive 100 due to heat curling and deformation. At the same time, Joule heat is easily generated during the conduction process of the electrode tab. The high melting point and low melt flow index of the base layer 10 provide good insulation.
[0045] Optionally, the melt flow index of the base layer 10 at 230℃ and 2.16kg load can be any one or any combination of two of the following: 0.1g / 10min, 1g / 10min, 2g / 10min, 3g / 10min, 4g / 10min, and 5g / 10min.
[0046] In some embodiments, the number average molecular weight of the base layer 10 is at least 70,000 g / mol, which is beneficial to improving the insulation and mechanical strength of the insulating adhesive 100 and reducing damage to the sealing part during drop.
[0047] In some embodiments, the surface layer 20 has at least a first melting point and a second melting point. The first melting point A is in the range of 50°C ≤ A ≤ 120°C, and the second melting point B is in the range of 120°C < B ≤ 170°C. By setting multiple melting points, the surface layer 20 can melt within the temperature range of the first and second melting points, effectively controlling the melting pressure relief point of the battery cell 300 and improving the heat dissipation efficiency of the battery cell 300.
[0048] Optionally, the first melting point can be any one or any combination of two of the following: 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, and 120°C.
[0049] Optionally, the second melting point can be any one or any combination of two of the following: 120.1°C, 125°C, 130°C, 135°C, 140°C, 145°C, 150°C, 155°C, 160°C, 165°C, and 170°C.
[0050] In some embodiments, the melting point of the base layer 10 is higher than that of the surface layer 20. The melting point of the base layer 10 is greater than 200°C, which supports the surface layer 20 and reduces the risk of short circuit caused by the melting of the base layer 10 leading to contact between the tab 210 and the metal layer 312 of the cell housing 310 or the electrode sheets of different polarities. This is beneficial to improving the insulation of the insulating adhesive 100.
[0051] In some embodiments, the melting point of the base layer 10 is 220°C ≤ A ≤ 500°C, which further reduces the risk of short circuit caused by melting and is beneficial to improving the safety of the battery cell 300.
[0052] Optionally, the melting point of the base layer 10 can be any one or any combination of two of the following: 220℃, 230℃, 240℃, 250℃, 260℃, 270℃, 280℃, 290℃, 300℃, 310℃, 320℃, 330℃, 340℃, 350℃, 360℃, 370℃, 380℃, 390℃, 400℃, 410℃, 420℃, 430℃, 440℃, 450℃, 460℃, 470℃, 480℃, 490℃, and 500℃.
[0053] In some embodiments, the surface layer 20 includes a first crystallinity and a second crystallinity. The first crystallinity is 1%-30%, and the second crystallinity is 0.01%-5%. Materials with a high first crystallinity have stronger intermolecular interactions and a higher melting point. Materials with a low second crystallinity have weaker intermolecular interactions. As the temperature rises, these low-crystallinity components preferentially melt, and the ordered structure is destroyed. Since these low-crystallinity components are uniformly distributed in the surface layer 20, their melting accelerates the collapse and melting of the surface layer 20 structure. This facilitates controlling the melting of the surface layer 20 within the temperature range of the first and second melting points, effectively regulating the melting and pressure relief point of the battery cell 300.
[0054] Optionally, the first degree of crystallinity can be a range of any one or any two of the following: 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, and 30%.
[0055] Optionally, the second degree of crystallinity can be 0.01%, 0.03%, 0.05%, 0.07%, 0.09%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2.0%, 2.1%, 2.2%, or 2. A range consisting of any one or any two of the following: 3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, 3.0%, 3.1%, 3.2%, 3.3%, 3.4%, 3.5%, 3.6%, 3.7%, 3.8%, 3.9%, 4.0%, 4.1%, 4.2%, 4.3%, 4.4%, 4.5%, 4.6%, 4.7%, 4.8%, 4.9%, and 5.0%.
[0056] In some embodiments, the crystallinity of the insulating adhesive 100 is 2%-35%, which is beneficial for controlling the melting and pressure relief point of the battery cell 300.
[0057] Optionally, the crystallinity of the insulating adhesive 100 can be any one or any combination of 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, and 35%.
[0058] In some embodiments, the weight-average molecular weight (Mw) of the surface layer 20 is 100,000 g / mol to 800,000 g / mol. If the weight-average molecular weight of the surface layer 20 is less than 100,000 g / mol, the mechanical strength of the surface layer 20 is low; if the weight-average molecular weight of the surface layer 20 is greater than 800,000 g / mol, the melt viscosity of the surface layer 20 is too high, which is not conducive to flow. By limiting the weight-average molecular weight (Mw) of the surface layer 20 to 100,000 g / mol to 800,000 g / mol, the packaging reliability of the cell 300 under normal temperature conditions and the mechanical strength of the surface layer 20 are improved. This is beneficial for controlling the melting point and melt flow index of the surface layer 20, and effectively regulating the melting pressure relief point of the cell 300.
[0059] Optionally, the weight-average molecular weight Mw of the surface layer 20 is any one or any combination of 100,000 g / mol, 200,000 g / mol, 300,000 g / mol, 400,000 g / mol, 500,000 g / mol, 600,000 g / mol, 700,000 g / mol, and 800,000 g / mol.
[0060] In some embodiments, Mw / Mn: 3-10, which improves the polydispersity index of the material, broadens the melting point range of the surface layer 20, increases the proportion of particles in the low melting point range, and adjusts the melt index, which is beneficial to increase the fluidity of the material at high temperatures, allowing it to melt rapidly after reaching the melting point. The surface layer 20 structure collapses to form a pressure relief channel, thereby improving the heat dissipation efficiency of the battery cell 300.
[0061] Optionally, the ratio of Mw / Mn can be any one of 3, 4, 5, 6, 7, 8, 9, 10 or any combination of two of them.
[0062] In some embodiments, the insulating adhesive 100 is made of at least one of polyolefin resins, acid-modified polyolefin resins, polyethylene, polypropylene, ethylene elastomers, and styrene elastomers.
[0063] In some embodiments, the thickness of the base layer 10 is 6% to 20% of the thickness of the insulating adhesive 100. If the thickness of the base layer 10 is too small (less than 6%), the tabs covered by the base layer 10 are easily exposed, leading to a short circuit. If the thickness of the base layer 10 is too large (greater than 20%), it affects the encapsulation pull force of the cell 300 under normal temperature conditions, easily causing pore channels and leakage. By limiting the thickness of the base layer 10 to 6% to 20% of the thickness of the insulating adhesive 100, it is beneficial to reduce the occurrence of pore channels in the cell 300, thereby reducing the risk of leakage and short circuits.
[0064] Optionally, the thickness of the base layer 10 can be any one of 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, or 20% of the thickness of the insulating adhesive 100.
[0065] In some embodiments, the thickness of the surface layer 20 is 30% to 44% of the thickness of the insulating adhesive 100. If the thickness of the surface layer 20 is too small (less than 30%), it affects the connection strength of the surface layer 20. If the excess adhesive clumps formed after the surface layer 20 melts are too small, it reduces the encapsulation pull force and reliability of the cell 300 under normal temperature conditions. Furthermore, the pressure relief channel formed by the melting of the surface layer 20 is reduced, which is detrimental to pressure relief. During the encapsulation process, along the thickness direction of the cell housing 310, two second adhesive layers 311 are bonded and have a first thickness. The portions of the insulating adhesive 100 extending along both sides of the tab 210 width direction are bonded and have a second thickness. The insulating adhesive 100 located on both sides of the tab 210 thickness direction and the tab 210 itself have a third thickness. If the thickness of the surface layer 20 is too large (greater than 44%), the large thickness difference affects the encapsulation reliability. By limiting the thickness of the surface layer 20 to 30% to 44% of the thickness of the insulating adhesive 100, the thickness difference between the first thickness, the second thickness and the third thickness is reduced, which is beneficial to improving the encapsulation reliability of the battery cell under normal temperature conditions and is also beneficial to pressure relief.
[0066] Optionally, the thickness of the surface layer 20 is any one of 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, or 44% of the thickness of the insulating adhesive 100.
[0067] In some embodiments, the insulating adhesive 100 includes a first adhesive layer 30, the thickness of which is 1% to 4% of the thickness of the insulating adhesive 100. If the first adhesive layer 30 is less than 1% of the thickness of the insulating adhesive 100, the connection strength between the base layer 10 and the surface layer 20 is low. If the first adhesive layer 30 is greater than 4% of the thickness of the insulating adhesive 100, the thickness of the insulating adhesive 100 increases, increasing the thickness difference between the first, second, and third thicknesses, which can easily affect the encapsulation reliability of the battery cell 300 under normal temperature conditions. By limiting the thickness of the first adhesive layer 30 to 1% to 4% of the thickness of the insulating adhesive 100, the thickness difference between the first, second, and third thicknesses is reduced, thereby improving the connection strength between the base layer 10 and the surface layer 20 and the encapsulation reliability of the battery cell 300 under normal temperature conditions.
[0068] Please refer to Figure 1. One embodiment of this application provides a tab assembly 200, including a tab 210 and an insulating adhesive 100 as described in any of the above embodiments, wherein the insulating adhesive 100 connects to the tab 210.
[0069] In some embodiments, the tab 210 is disposed between two insulating adhesives 100 along the thickness direction of the tab 210.
[0070] Referring to Figures 2 and 3, one embodiment of this application provides a battery cell 300, including a battery cell housing 310, an electrode assembly 320, tabs 210, and insulating adhesive 100. The electrode assembly 320 is disposed within the battery cell housing 310, and the tabs 210 are connected to the electrode assembly 320 and extended from the battery cell housing 310. Along the thickness direction of the tabs 210, the tabs 210 are disposed between two insulating adhesives 100. The insulating adhesive 100 is located between the tabs 210 and the battery cell housing 310, and the surface layer 20 is bonded to either the battery cell housing 310 or the tabs 210.
[0071] In some embodiments, the cell housing 310 may be a packaging bag encapsulated with an encapsulation film (such as an aluminum-plastic film), that is, the cell 300 is a soft-pack cell.
[0072] In some embodiments, the cell housing 310 includes a second adhesive layer 311, a metal layer 312, and an outer layer 313 stacked together. The metal layer 312 is disposed between the second adhesive layer 311 and the outer layer 313, and the outer layer 313 is located as the outermost layer of the cell housing 310. The outer layer 313 can be a nylon layer or a composite layer of polyester resin (PET) and nylon, providing protection against pollution, corrosion, and external damage. The metal layer 312 can include one of aluminum and steel, providing waterproofing, barrier properties, and shaping of the cell housing 310. The second adhesive layer 311 is a heat-sealing layer, which can include a polymer, including one of polypropylene and polyethylene. It is used to seal the cell housing 310 by hot pressing and to separate the metal layer 312 from the electrode assembly 320, reducing the risk of electrolyte leakage and corrosion of the metal layer 312 within the cell housing 310.
[0073] In some embodiments, the cell housing 310 includes a main body portion 310a and a sealing portion 310b, with the main body portion 310a connected to the sealing portion 310b. An electrode assembly 320 is disposed on the main body portion 310a, and an electrode tab 210 extends from the sealing portion 310b out of the cell housing 310.
[0074] In some embodiments, the electrode assembly 320 includes a first electrode 321, a second electrode 322, and a separator 323, wherein the separator 323 is disposed between the first electrode 321 and the second electrode 322. The separator 323 is used to prevent the first electrode 321 and the second electrode 322 from directly contacting each other, thereby reducing the risk of short circuit between the first electrode 321 and the second electrode 322.
[0075] In some embodiments, the electrode assembly 320 is a wound structure, wherein the first electrode 321, the separator 323, and the second electrode 322 are sequentially stacked and then wound to form the electrode assembly 320. In other embodiments, the electrode assembly 320 can also be a stacked structure, wherein the first electrode 321, the separator 323, and the second electrode 322 are sequentially stacked to form an electrode assembly unit, and multiple electrode assembly units are then stacked to form the electrode assembly 320. In some embodiments, the first electrode 321 is a negative electrode or a positive electrode, and the second electrode 322 is an electrode with the opposite polarity to the first electrode 321.
[0076] In some embodiments, the tab 210 includes a first segment 211, a second segment 212, and a third segment 213. At least a portion of the first segment 211 is connected to a first electrode 321 or a second electrode 322. The second segment 212 is bent to connect to the first segment 211. The third segment 213 is bent to connect to the second segment 212, and a portion of the third segment 213 extends out of the sealing portion 310b. A portion of the third segment 213 extends out of the insulating adhesive 100 for connection with other components for energy transfer.
[0077] In some embodiments, the first segment 211 is welded to the first electrode 321 or the second electrode 322. The welding method includes laser welding, ultrasonic welding, etc.
[0078] In some embodiments, the length of the second segment 212 along the thickness direction of the cell 300 is 5%-70% of the thickness of the cell 300. This helps reduce the risk of breakage of the tab 210 during a drop, and the insulating adhesive 100 reduces the risk of short circuits caused by contact between the second segment 212 and the metal layer 312 of the cell housing 310 or electrodes of different polarities. Optionally, the length of the second segment 212 is any one of 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, and 70% of the thickness of the cell 300.
[0079] In some embodiments, along the thickness direction of the cell housing 310, the sealing portion 310b includes two second adhesive layers 311. Along the thickness direction of the cell housing 310, the sealing portion 310b includes a first region 301 that does not overlap with the insulating adhesive 100. The two second adhesive layers 311 located in the first region 301 are bonded together. The thickness of the base layer 10 is less than twice the sum of the thicknesses of the two second adhesive layers 311 after hot pressing, or the sum of the thicknesses of the base layers 10 on both sides of the tab 210 is less than the sum of the thicknesses of the two second adhesive layers 311. Because the base layer 10 has a high melting point, it is not easily melted during the encapsulation process. If the thickness of the base layer 10 is too large, it will not melt after encapsulation, easily creating pore channels that lead to leakage. External moisture can easily enter the interior of the cell housing 310, easily causing a short circuit. By setting the thickness of the base layer 10 to be less than half the sum of the thicknesses of the two second adhesive layers 311 after hot pressing, the occurrence of pore channels in the cell housing 310 is reduced, lowering the risk of leakage and short circuits.
[0080] In some embodiments, the sum of the thickness of the insulating adhesive 100 and the thickness of the second adhesive layer 311 is less than the sum of the thicknesses of the two second adhesive layers 311, further reducing the presence of pore channels in the cell housing 310 and lowering the risk of leakage and short circuit.
[0081] In some embodiments, the sealing portion 310b includes an overflow ball (not shown). When the sealing portion 310b is hot-pressed, at least a portion of the surface layer 20 melts and forms an overflow ball. The overflow ball is located between the tab 210 and the second adhesive layer 311. The length of the overflow ball along the direction of extension of the tab 210 is 0.1mm-0.5mm, which increases the sealing width and is beneficial to improving the encapsulation pull force of the insulating adhesive 100 under normal temperature conditions and the encapsulation reliability of the cell 300 under normal temperature conditions.
[0082] Optionally, the length of the overflow colloid along the direction of the tab 210 can be any one or any combination of 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, and 0.5 mm.
[0083] In some embodiments, at 25°C, the tensile force between the insulating adhesive 100 and the sealing portion 310b and / or the tab 210 ranges from 5 N / mm to 10 N / mm, improving the encapsulation tensile force of the insulating adhesive 100 under normal temperature conditions and enhancing the encapsulation reliability of the battery cell under normal temperature conditions. A tensile force exceeding 10 N / mm can easily cause the packaging bag to rupture.
[0084] Optionally, at 25°C, the tensile force between the insulating adhesive 100 and the sealing part 310b and / or the tab 210 can be any one or any combination of two of the following: 5 N / mm, 5.5 N / mm, 6 N / mm, 6.5 N / mm, 7 N / mm, 7.5 N / mm, 8 N / mm, 8.5 N / mm, 9 N / mm, 9.5 N / mm, and 10 N / mm.
[0085] In some embodiments, at 95°C, the tensile force between the insulating adhesive 100 and the sealing portion 310b and / or the tab 210 ranges from 0.2 N / mm to 2 N / mm. Under operating conditions at 95°C, the encapsulation reliability of the cell 300 still meets the requirements, reducing the occurrence of leakage.
[0086] Optionally, at 95°C, the tensile force between the insulating adhesive 100 and the sealing portion 310b and / or the tab 210 can be any one or any combination of 0.2 N / mm, 0.3 N / mm, 0.4 N / mm, 0.5 N / mm, 0.6 N / mm, 0.7 N / mm, 0.8 N / mm, 0.9 N / mm, 1.0 N / mm, 1.1 N / mm, 1.2 N / mm, 1.3 N / mm, 1.4 N / mm, 1.5 N / mm, 1.6 N / mm, 1.7 N / mm, 1.8 N / mm, 1.9 N / mm, and 2.0 N / mm.
[0087] In some embodiments, at 120°C, the tensile force between the insulating adhesive 100 and the sealing portion 310b and / or the tab 210 ranges from 0.01 N / mm to 0.2 N / mm, which further facilitates the rapid formation of a pressure relief channel after the cell expands, improves heat dissipation efficiency, and thus enhances the safety performance of the cell.
[0088] Optionally, at 120°C, the tensile force between the insulating adhesive 100 and the sealing part 310b and / or the tab 210 can be any one or any combination of 0.01, 0.02, 0.03 N / mm, 0.04 N / mm, 0.05 N / mm, 0.06 N / mm, 0.07 N / mm, 0.08 N / mm, 0.09 N / mm, 0.1 N / mm, 0.11 N / mm, 0.12 N / mm, 0.13 N / mm, 0.14 N / mm, 0.15 N / mm, 0.16 N / mm, 0.17 N / mm, 0.18 N / mm, 0.19 N / mm, and 0.2 N / mm.
[0089] The present application will be further described below through specific embodiments.
[0090] 1. Method for testing the ratio of air bubbles to porosity:
[0091] Sulfuric acid and hydrofluoric acid were used to corrode and remove the metal layer 312 and outer layer 313 above the insulating adhesive 100, respectively, exposing the second adhesive layer 311. The proportion of the area of bubbles and pores to the total area of the insulating adhesive 100 was determined by CCD observation and measurement.
[0092] 2. Number-average molecular weight test method:
[0093] Gel permeation chromatography (GPC), a high-performance liquid chromatography technique, is used to determine molecular weight distribution by separating polymer chains of different molecular weights. The surface layer is peeled off from the insulating adhesive to obtain surface and base layer samples. Tetrahydrofuran (THF) solvent is selected to dissolve the sample and prepare a solution of appropriate concentration (typically 0.1-1 mg / mL). The sample solution is filtered using a 0.45 μm filter membrane to remove insoluble matter and particles. The test temperature is set to 30 °C, and the flow rate to 1 mL / min. The injection volume is set to 100 μL. The response signal of each molecular weight component is recorded using a detector. The detection signal is converted to molecular weight using a calibration curve, and the number-average molecular weight (Mn), weight-average molecular weight (Mw), and polydispersity index (PDI) are calculated.
[0094] 3. The specific method for hot box testing is as follows:
[0095] Adjust the furnace temperature to 25℃, place the lithium-ion cell sample inside the furnace and let it stand for 5 minutes; charge it to 3.0V with 0.2C DC; let it stand for 10 minutes; then charge it to 4.5V with 0.7C constant current, and then charge it to 0.025C constant voltage; let it stand for 10 minutes; take a photo before testing, measure the internal resistance of the voltage, and attach the temperature sensing wire to the surface of the cell. Then place the sample into the heating furnace chamber and raise the temperature to the target temperature (e.g., 130℃) at a rate of 5±2℃ / min and hold it at that temperature for 60 minutes. Take a photo after testing and measure the internal resistance of the voltage. If the cell does not catch fire or explode, it indicates that it has passed the hot box test. The highest temperature that can be passed is defined as the hot box window of the cell.
[0096] 4. Packaging pull force test method:
[0097] Take a sealing part and an electrode assembly with a width of 8mm. Adhere the sealing part to the electrode assembly. Clamp the battery cell housing at one end of the tensile testing machine and clamp the electrode at the other end of the tensile testing machine. Adjust the tensile testing machine to the test temperature at 10℃ / min. After holding the temperature for 30s, stretch the two ends of the tensile testing machine at 180 degrees and a tensile speed of 175mm / min until it breaks. Record the maximum tensile force of the tensile testing machine.
[0098] 5. Melt flow index test method:
[0099] Peel the surface layer off the insulating adhesive to obtain surface layer and base layer samples. Take approximately 2-10 grams of sample, the exact weight depending on the melt flow index (MFR) of the material and the testing conditions. Using a melt flow indexer, break the sample into small particles to ensure uniformity. Set the test temperature (230°C) and load (2.16 kg). Place the sample into the barrel of the melt flow indexer. Heat to 230°C, ensuring the sample is completely melted. Apply a load of 2.16 kg, allowing the molten material to pass through a standard die. Record the weight of material passing through the die within a specified time. Melt Flow Index (MFR) = Weight of material passing through the die (g) / Test time (min).
[0100] 6. High-temperature internal stress testing method:
[0101] After being fully charged at 1C, the lithium-ion battery is placed in a specially designed fixture. The fixture's length and width are the same as the battery's dimensions, but its thickness is 2% greater. The battery is then stored for 8 hours in a test environment at 95±2℃. The fixture restricts the expansion of the cell in the thickness direction, causing internal pressure to impact the sealing area. If the lithium-ion battery does not catch fire, explode, smoke, or leak, it passes the test. This test characterizes the reliability of the packaging under the most stringent high-temperature testing conditions.
[0102] 7. Withstand voltage test:
[0103] Using one probe pressed against the positive and negative electrode tabs 210, and another probe piercing the conductive aluminum layer of the cell housing 310, a voltage of 100V and a pressure of 0.35Mpa on the surface of the cell 300 are applied between the two probes. If the resistance value is required to be >20MΩ, it is considered to pass.
[0104] 8. Short test:
[0105] The battery was pre-charged to 100% SOC. The sample was placed in a test environment of 55±5℃. After the cell surface temperature reached the test temperature, it was left to stand for 30 minutes. The positive and negative terminals of the sample were shorted using a load resistor of 80±20mΩ.
[0106] The test ends when one of the following conditions is met: no fire, no explosion; then it passes.
[0107] 1) The test lasts for 24 hours;
[0108] 2) The surface temperature of the battery cell drops to 20% below its peak value;
[0109] 9. Test methods for crystallinity and melting point:
[0110] The surface layer was peeled off from the insulating adhesive to obtain surface layer and base layer samples. Approximately 1-3 mg of sample was placed in a crucible and tested using a STA449F3 thermal analyzer at a temperature range of 25-800℃, a scan rate of 0.1-50 K / min, and under inert gas N2 conditions.
[0111] Preparation method of insulating adhesive 100: First, prepare surface layer 20. Particles with different melting points are mixed and stirred in a high-speed mixer at 25°C for 60 minutes. The mixture is then melt-extruded and granulated in a progressive temperature range of 170°C-250°C. The granules are dried at 80°C and conveyed to a screw extruder through a vacuum feeder. The mixture is then melt-plasticized in a progressive temperature range of 180°C-250°C at 10MPa. Finally, it is co-extruded and cast through a die at 230°C and 5MPa. The mixture is cooled to room temperature and then rolled into a master roll. It is then cured at room temperature for 24 hours.
[0112] Then, a solvent-based adhesive (first adhesive layer 30) is applied to one side of the base layer 10, dried in an oven at 80°C, and laminated with the surface layer 20 at 100°C and 1 MPa. A solvent-based adhesive (first adhesive layer 30) is applied to the other side of the base layer 10, dried in an oven at 80°C, and laminated with another surface layer 20 at 100°C and 1 MPa. The mixture is then cured at 60°C for 5 days. The insulating adhesive 100 is formed through rough and fine cutting.
[0113] The withstand voltage test was conducted in groups of 1000 cells 300. Among the qualified cells 300 that passed the withstand voltage test, 100 cells 300 were grouped together for bubble and porosity tests, short tests, high temperature internal stress tests, and hot box tests.
[0114] Table 1
[0115] As can be seen from Examples 1-1 to 1-15 in Table 1, the number average molecular weight of surface layer 20 is 10000g / mol-130000g / mol. When surface layer 20 is at 230℃ and under a load of 2.16kg, the melt index is 4g / 10min-20g / 10min. Cell 300 passes the hot box test at higher temperatures, with low bubble and porosity ratios and high pass rate in high-temperature internal stress tests. This is beneficial to improving the packaging reliability of cell 300, and it is also beneficial to quickly form a pressure relief channel after cell expansion, thereby improving heat dissipation efficiency and ultimately improving the safety performance of the cell.
[0116] As can be seen from Examples 1-6 to 1-8 in Table 1, when the surface layer 20 is at 230°C and the melt index is 7.1g / 10min-12g / 10min under a load of 2.16kg, the high pass rate of the high temperature internal stress test is conducive to the cell 300 passing the hot box test at a higher temperature.
[0117] As can be seen from Examples 1-1 to 1-13 in Table 1, when the melting point of the base layer 10 is greater than 200°C, the pass rate of the withstand voltage test and the short test is high.
[0118] Referring to Figure 4, this application also provides an electrical device 400 employing the aforementioned battery cell 300. In one embodiment, the electrical device 400 of this application may be, but is not limited to, electronic devices, drones, backup power supplies, electric vehicles, electric motorcycles, electric-assisted bicycles, power tools, large household batteries, etc.
[0119] Those skilled in the art should recognize that the above embodiments are merely illustrative of this application and are not intended to limit this application. Any appropriate changes and variations made to the above embodiments within the spirit and essence of this application fall within the scope of this application's disclosure.
Claims
1. An insulating adhesive, characterized in that, Including the surface layer; The surface layer has a melt index of 4 g / 10 min to 20 g / 10 min at 230°C and a load of 2.16 kg, and the number-average molecular weight Mn of the surface layer is 10000 g / mol to 130000 g / mol.
2. The insulating adhesive as described in claim 1, characterized in that, The surface layer has a melt flow index of 6 g / 10 min to 14 g / 10 min at 230°C and a load of 2.16 kg.
3. The insulating adhesive as described in claim 2, characterized in that, The surface layer has a melt flow index of 7.1 g / 10 min to 12 g / 10 min at 230°C and a load of 2.16 kg.
4. The insulating adhesive according to any one of claims 1 to 3, characterized in that, The surface layer has at least a first melting point and a second melting point, wherein the range of the first melting point A is 50℃≤A≤120℃, and the range of the second melting point C is 120℃<B≤170℃.
5. The insulating adhesive according to any one of claims 1 to 4, characterized in that, The surface layer includes a first degree of crystallinity and a second degree of crystallinity, wherein the first degree of crystallinity is 1%-30% and the second degree of crystallinity is 0.01%-5%.
6. The insulating adhesive according to any one of claims 1 to 5, characterized in that, The crystallinity of the insulating adhesive is 2%-35%.
7. The insulating adhesive according to any one of claims 1 to 6, characterized in that, The insulating adhesive also includes a base layer, and the surface layer is connected to at least one side of the base layer along the thickness direction of the base layer. The melting point of the base layer is greater than the melting point of the surface layer, and the melting point of the base layer is greater than 200°C.
8. The insulating adhesive as described in claim 7, characterized in that, The melt flow index of the base layer at 230℃ and 2.16kg load is 0.1g / 10min-5g / 10min.
9. The insulating adhesive as described in claim 7, characterized in that, The number-average molecular weight of the base layer is at least 70,000 g / mol.
10. The insulating adhesive according to any one of claims 1 to 9, characterized in that, The surface layer must satisfy at least one of the following conditions: 1) Weight-average molecular weight Mw: 100,000 g / mol - 800,000 g / mol; 2) Mw / Mn: 3-10.
11. The insulating adhesive according to any one of claims 1 to 10, characterized in that, At least one of the following conditions must be met: 1) The surface layer accounts for 30%-44% of the thickness of the insulating adhesive; 2) The insulating adhesive includes a base layer, and the surface layer is connected to at least one side of the base layer along the thickness direction of the base layer. The base layer accounts for 6%-20% of the thickness of the insulating adhesive. 3) The insulating adhesive further includes a first adhesive layer, which connects the base layer and the surface layer, and the thickness of the first adhesive layer is 1% to 4% of the thickness of the insulating adhesive.
12. A tab assembly, characterized in that, It includes a tab and an insulating adhesive as described in any one of claims 1 to 11, wherein the insulating adhesive is disposed on both sides of the tab.
13. A battery cell, characterized in that, The battery cell includes a battery cell housing, an electrode assembly, tabs, and an insulating adhesive as described in any one of claims 1 to 11. The battery cell housing includes a main body and a sealing portion. The electrode assembly is disposed within the main body, and the tabs are connected to the electrode assembly and extend out of the sealing portion. The insulating adhesive is disposed on both sides of the tab and connected to the cell housing, and the surface layer is bonded to the cell housing and / or the tab.
14. The battery cell as described in claim 13, characterized in that, The electrode includes a first section, a second section, and a third section; At least a portion of the first segment is connected to the electrode assembly; The second section is bent and connected to the first section; the second section accounts for 5%-70% of the thickness of the battery cell; The third section is bent and connected to the second section, and a portion of the third section extends out of the sealing part.
15. The battery cell according to any one of claims 13 to 14, characterized in that, At 25°C, the tensile force between the insulating adhesive and the sealing part and / or the electrode tab is 5N / mm-10N / mm.
16. The battery cell according to any one of claims 13 to 15, characterized in that, At 95°C, the tensile force between the insulating adhesive and the sealing part and / or the electrode tab is 0.2 N / mm to 2 N / mm.
17. The battery cell according to any one of claims 13 to 16, characterized in that, At 120°C, the tensile force between the insulating adhesive and the sealing part and / or the electrode tab is 0.01 N / mm to 0.2 N / mm.
18. The battery cell according to any one of claims 13 to 17, characterized in that, The sealing portion includes two second adhesive layers, and the sealing portion includes a first region that does not overlap with the insulating adhesive. The two second adhesive layers located in the first region are bonded together. The insulating adhesive includes a base layer that connects the surface layer. In the first region, twice the thickness of the base layer is less than the sum of the thicknesses of the two second adhesive layers, or the sum of the thicknesses of the base layers on both sides of the tab is less than the sum of the thicknesses of the two second adhesive layers.
19. The battery cell as described in claim 18, characterized in that, The sealing part also includes an overflow glue ball, which is located between the electrode tab and the second adhesive layer, and the length of the overflow glue ball along the direction of extension of the electrode tab is 0.1mm-0.5mm.
20. An electrical appliance, characterized in that, Includes the battery cell as described in any one of claims 13 to 19.