Secondary battery, battery pack, and electronic device
By setting up an island-like rubber layer on the separator of the secondary battery, the problem of difficulty in electrolyte infiltration is solved, the safety and electrochemical performance of the battery are improved, and high energy density is maintained.
Patent Information
- Application Number
- CN202421416125.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-06-19
- Publication Date
- 2025-06-13
- Estimated Expiration
- 2034-06-19
AI Technical Summary
The winding tension of the electrode sheet and separator of the electrode assembly in the existing secondary batteries is large, resulting in a small hierarchy distance between the positive and negative electrode sheets, which in turn aggravates the difficulty of electrolyte infiltration and affects the safety and electrochemical performance of the battery.
By providing a glue layer on the first and second diaphragms, the glue layer directly faces the positive electrode sheet, and the glue layer is distributed in an island-like manner similar to a sponge, increasing the spacing between the positive electrode sheet and the base film, thereby storing more electrolytes and improving the infiltration of the electrolyte.
While maintaining a high energy density, the infiltration of the electrolyte on the positive electrode sheet is improved, stress concentration during the charge and discharge cycle is alleviated, and safety and electrochemical performance of the battery are improved.
Smart Images
Figure CN222980558U_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the field of batteries, and more specifically, provides a secondary battery, a battery pack, and an electronic device. Background Art
[0002] Currently, electrochemical devices are increasingly widely used. For example, secondary batteries (such as lithium-ion batteries) are applied to electronic devices such as vehicles, energy storage, mobile phones, tablet computers, wearable devices, mobile power supplies, electronic cigarettes, digital products, power tools, power devices, and energy storage devices, and are particularly important in the new energy field. Currently, in existing secondary batteries, the winding tension of the electrode sheets and the separator of the electrode assembly is relatively large, resulting in a small layer spacing between the positive and negative electrode sheets, thereby exacerbating the difficulty of electrolyte infiltration. Correspondingly, the poor infiltration of the secondary battery will affect the safety performance and electrochemical performance of the battery. Therefore, improving the infiltration of the secondary battery is one of the problems that need to be overcome by the secondary battery at present. Summary of the Utility Model
[0003] In view of the above problems in the prior art, the present application provides a secondary battery, a battery pack, and an electronic device, which can at least improve the infiltration of the secondary battery while maintaining a high energy density.
[0004] According to one aspect of the present application, a secondary battery is provided, including: an electrode assembly formed by winding a first separator, a positive electrode sheet, a second separator, and a negative electrode sheet after laminating; the first separator includes a first base film and a coating located on the first base film, the second separator includes a second base film and a coating located on the second base film, the coatings on the sides of the first separator and the second separator facing the positive electrode sheet include adhesive layers, and a heat-resistant layer is provided on the side of one of the first separator and the second separator facing the positive electrode sheet; or no heat-resistant layer is provided on the sides of the first separator and the second separator facing the positive electrode sheet, and a heat-resistant layer is provided on the side of one of the first separator and the second separator facing the negative electrode sheet.
[0005] In some embodiments, the positive electrode sheet includes concave and convex surfaces on opposite sides, the adhesive layer of the first separator faces the convex surface of the positive electrode sheet, and the adhesive layer of the second separator faces the concave surface of the positive electrode sheet.
[0006] In some embodiments, the adhesive layer includes a polyvinylidene fluoride layer.
[0007] In some embodiments, the heat-resistant layer directly contacts one of the first base film and the second base film.
[0008] In some embodiments, the coating on the side of the first separator facing the negative electrode sheet includes a heat-resistant layer, and the heat-resistant layer directly contacts the negative electrode sheet.
[0009] In some embodiments, the coating on the side of the second separator facing the negative electrode sheet includes an adhesive layer.
[0010] In some embodiments, the coating on the side of the second separator facing the negative electrode sheet further includes a heat-resistant layer located between the second base film and the adhesive layer.
[0011] In some embodiments, the secondary battery is a cylindrical battery.
[0012] An embodiment of the present application further provides a battery pack, including the secondary battery of any one of the above.
[0013] An embodiment of the present application further provides an electronic device, including at least one of the secondary battery and the battery pack of any one of the above.
[0014] In the above technical solution of the present application, both the first separator and the second separator include an adhesive layer facing the positive electrode sheet. Since the adhesive layer is distributed in an island-like manner similar to a sponge, the distance between the positive electrode sheet and the first base film and the second base film is increased, and more electrolyte can be stored, thereby at least improving the wetting of the electrolyte on the positive electrode sheet. In addition, the settings of the heat-resistant layers on the first separator and the second separator are different, and factors such as the energy density of the secondary battery can be more comprehensively considered to more flexibly set the first separator and the second separator. Furthermore, since the adhesive layer increases the distance between the positive electrode sheet and the first base film and the second base film, this increase in distance can also relieve the stress concentration caused by the expansion of the electrode sheet during the charge and discharge cycles of the secondary battery. BRIEF DESCRIPTION OF THE DRAWINGS
[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings. It should be noted that according to the standard practice of the industry, the components are not drawn to scale and are only for illustrative purposes. In fact, for the sake of clarity in discussion, the size of each component can be increased or decreased arbitrarily.
[0016] Figure 1 A schematic diagram of a vehicle according to an embodiment of the present application is shown.
[0017] Figure 2 A cross-sectional view of a secondary battery according to an embodiment of the present application is shown.
[0018] Figure 3 A top view schematic diagram of an electrode assembly according to an embodiment of the present application is shown.
[0019] Figure 4 A schematic diagram showing according to an embodiment of the present application Figure 3 An enlarged schematic diagram of a region of the first separator of the electrode assembly.
[0020] Figure 5Shows the Figure 3 magnified schematic view of the area of the second separator of the electrode assembly.
[0021] Figure 6 Shows the cross-sectional schematic view of the electrode assembly according to an embodiment of the present application.
[0022] Figure 7 Shows the Figure 3 magnified schematic view of the area of the first separator of the electrode assembly according to another embodiment of the present application.
[0023] Figure 8 Shows the Figure 3 magnified schematic view of the area of the first separator of the electrode assembly according to another embodiment of the present application.
[0024] Figure 9 Shows the Figure 3 magnified schematic view of the area of the second separator of the electrode assembly according to another embodiment of the present application.
[0025] Figure 10 Shows the three-dimensional schematic view of the secondary battery according to an embodiment of the present application. Detailed Description
[0026] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art belong to the scope of protection of the present application.
[0027] The following disclosure provides many different embodiments or examples for implementing different features of the provided subject matter. Specific examples of components and arrangements will be described below to simplify the present invention. Of course, these are only examples and are not intended to limit the present invention. For example, in the following description, forming the first component above or on the second component may include embodiments where the first component and the second component are in direct contact, and may also include embodiments where additional components are formed between the first component and the second component such that the first component and the second component may not be in direct contact. Moreover, the present invention may repeat reference numerals and / or letters in various examples. This repetition is only for the sake of simplicity and clarity and does not itself indicate the relationship between the various embodiments and / or configurations discussed.
[0028] In addition, without conflict, the embodiments in this application and the features in the embodiments can be combined with each other. The following will describe this application in detail with reference to the accompanying drawings and in combination with the embodiments. It should be understood that the specific structures shown in the drawings are only for illustrative purposes for easy explanation and are not intended to limit this application. When describing a specific figure, other structures not described shown in the figure can be set according to actual needs and are not intended to limit this application.
[0029] When the following content involves the adhesive layer and the heat-resistant layer, the descriptions of first, second, third... are used to distinguish their different positions, such as on different sides of the base film or provided on different base films.
[0030] With the increasing shortage of fossil resources, due to the environmental friendliness of lithium-ion batteries, lithium-ion batteries have become the main power source of new energy vehicles, and currently there is a trend that new energy vehicles are gradually replacing fuel vehicles. At present, due to the advantages of high assembly efficiency and low production cost of cylindrical batteries, cylindrical batteries are widely used in the field of new energy vehicles.
[0031] The electrode assembly of the cylindrical battery is relatively large in size, and in order to ensure a high margin of the electrode assembly group (the diameter of the electrode assembly divided by the inner diameter of the outer shell, and currently the group margin can be greater than 97%), the winding stress of the electrode sheet and the separator is usually relatively large, which will result in a small layer distance between the positive and negative electrode sheets, thus exacerbating the difficulty of electrolyte infiltration, further increasing the process difficulty and affecting the processing efficiency, and the electrode cores with poor infiltration are extremely prone to lithium plating, posing a great potential safety hazard. Further, in the radial direction of the cylindrical battery, the stress is relatively small at positions closer to the center and the outer surface, while the stress is relatively large at positions far from the center and the outer surface, and the layer distance between the positive and negative electrode sheets is relatively small, so the infiltration of the electrolyte is relatively poor, and thus the distribution of the electrolyte in the radial direction is uneven. In addition, due to the action of gravity, the electrolyte is mainly concentrated at the bottom of the cylindrical battery, so the distribution of the electrolyte in the vertical direction is also uneven. This uneven distribution of the electrolyte will also affect the electrical performance and safety performance of the cylindrical battery. The existing methods for improving battery infiltration mainly include adding wetting agents to the electrode sheet or improving the liquid injection process, but adding wetting agents to the electrode sheet usually deteriorates the electrochemical performance of the battery, and improving the liquid injection process may prolong the liquid injection time and thus affect the processing efficiency. However, in the prior art, few improvements to battery infiltration are made from the perspective of the separator. In addition, the two separators in the cylindrical battery in the prior art are generally the same, which is disadvantageous for the setting of the battery.
[0032] The inventors of the present application have found that by making the first separator 104 of the electrode assembly include an adhesive layer 108 on the first surface 106s1 of the first base film 106 facing the positive electrode tab 128, and the second separator 110 include an adhesive layer 114 on the first surface 110s1 of the second base film 112 facing the positive electrode tab 128, and by making both the adhesive layers 108 and 114 directly face the positive electrode tab, since the adhesive layers 108 and 114 are distributed in a sponge-like island pattern on the first surface 106s1 of the first base film 106 and the first surface 110s1 of the second base film 110 respectively, the distance between the positive electrode tab and the first base film 106 and the second base film 110 is increased, and more electrolyte can be stored, thereby at least improving the wetting of the positive electrode tab 125 by the electrolyte. In addition, a heat-resistant layer is provided on one side of the first separator 104 and the second separator 110 facing the positive electrode tab 128; or no heat-resistant layer is provided on one side of the first separator 104 and the second separator 110 facing the positive electrode tab 128 and a heat-resistant layer is provided on one side of the first separator 104 and the second separator 110 facing the negative electrode tab 130, and the heat-resistant layer is in direct contact with one of the first base film 106 and the second base film 112, that is, by setting the first separator 104 and the second separator 110 differently, factors such as the energy density of the secondary battery 100 can be more comprehensively considered to more flexibly set the first separator 104 and the second separator 110. In addition, since the adhesive layers 108 and 114 increase the distance between the positive electrode tab and the first base film 106 and the second base film 110, this increase in distance can also relieve the stress concentration caused by the expansion of the electrode tab during the charge and discharge cycles of the secondary battery 100.
[0033] According to one aspect of the present application, an electronic device is provided. For the convenience of description, in the following description, the electronic device is taken as a vehicle as an example for illustration. It is not difficult to understand that the electronic device provided by the present application is not limited to a vehicle, and the electronic device can be a vehicle, a mobile phone, a portable device, a laptop computer, a ship, a spacecraft, an electric toy, an electric tool, and so on. Figure 1 A schematic diagram of a vehicle 1000 according to an embodiment of the present application is shown. Refer to Figure 1 , inside the vehicle 1000, a battery pack 1002 is provided, and the battery pack 1002 can be provided at the bottom or the head or the tail of the vehicle body 1001. The battery pack 1002 can be used for power supply of the vehicle 1000. For example, the battery pack 1002 can be used as the operating power source of the vehicle 1000.
[0034] Further, the vehicle 1000 may further include a controller and a motor. The controller is used to control the battery pack 1002 to supply power to the motor. For example, it is used for the working power requirements during the start, navigation, and driving of the vehicle 1000. The battery pack 1002 mentioned in the embodiments of the present application may include one or more secondary batteries described below to provide higher voltage and capacity. When there are multiple secondary batteries, the multiple batteries are connected in series, parallel, or in a hybrid connection through a busbar component. The secondary battery 100 in the battery pack 1002 may be a cylindrical battery, a square battery, etc., and the embodiments of the present application do not limit this.
[0035] Figure 2 A cross-sectional view of the secondary battery 100 according to an embodiment of the present application is shown. Although Figure 2 the secondary battery 100 is shown as a cylindrical battery in [reference], it is not difficult to understand that the secondary battery 100 in the embodiments of the present application is not limited to a cylindrical battery. Figure 3 A top view schematic diagram of the electrode assembly 102 according to an embodiment of the present application is shown. Figure 4 and Figure 5 respectively show enlarged schematic diagrams of the regions 140 and 150 of the first separator 104 and the second separator 110 of the electrode assembly 102 according to an embodiment of the present application. With reference to Figures 2 to 5As shown, in some embodiments, the secondary battery 100 includes an electrode assembly 102, which is formed by winding a first separator 104, a positive electrode tab 128, a second separator 110, and a negative electrode tab 130 in a stacked manner. The first separator 104 includes a first base film 106 and a coating located on the first base film 106. The second separator 110 includes a second base film 112 and a coating located on the second base film 112. The coatings on the sides of the first separator 104 and the second separator 110 facing the positive electrode tab 128 include adhesive layers 108 and 114. A heat-resistant layer is provided on the side of one of the first separator 104 and the second separator 110 facing the positive electrode tab 128; or there is no heat-resistant layer on the sides of the first separator 104 and the second separator 110 facing the positive electrode tab 128, and a heat-resistant layer is provided on the side of one of the first separator 104 and the second separator 110 facing the negative electrode tab 130. The heat-resistant layer directly contacts one of the first base film 106 and the second base film 112. The first surface 106s1 of the first base film 106 and the first surface 112s1 of the second base film 112 both face the positive electrode tab 128. The adhesive layers 108 and 114 both directly face the positive electrode tab 128. Accordingly, the adhesive layer 108 serves as the outermost layer of the first separator 104 facing the positive electrode tab 128, and the adhesive layer 114 serves as the outermost layer of the second separator 110 facing the positive electrode tab 128. In the secondary battery 100 of the embodiments of the present application, the adhesive layer 108 is provided on the first surface 106s1 of the first base film 106 of the first separator 104 facing the positive electrode tab 128, and the adhesive layer 114 is provided on the first surface 112s1 of the second base film 112 of the second separator 110 facing the positive electrode tab 128. By making the adhesive layers 108 and 114 both directly face the positive electrode tab 128, since the adhesive layers 108 and 114 are distributed in an island-like manner similar to a sponge on the first surface 106s1 of the first base film 106 and the first surface 112s1 of the second base film 112 respectively, the distance between the positive electrode tab 128 and the first base film 106 and the second base film 110 is increased, and this island-like distribution can also store more electrolyte, thereby at least improving the wetting of the electrolyte on the positive electrode tab 128. In addition, the provision of the adhesive layers 108 and 114 can also make the distribution of the electrolyte more uniform. In some embodiments, both the adhesive layers 108 and 114 are polyvinylidene fluoride layers.
[0036] The positive electrode tab 128 includes concave and convex surfaces on opposite sides. The adhesive layer 108 of the first separator 104 faces the convex surface of the positive electrode tab 128, and the adhesive layer 114 of the second separator 110 faces the concave surface of the positive electrode tab 128. That is to say, corresponding adhesive layers 108 and 114 are provided on both the convex surface side and the concave surface side of the positive electrode tab 128 to increase the distance from the first base film 106 and the second base film 110, and improve the wetting of the electrolyte on the positive electrode tab 128.
[0037] To further illustrate that the adhesive layers 108 and 114 face the positive electrode tab 128, Figure 6 FIG. Figure 6 shows a cross-sectional schematic view of the electrode assembly 102 according to an embodiment of the present application. The positive electrode tab 128 of the electrode assembly 102 includes a positive current collector 1211 and a positive active material layer coated on the positive current collector 1211. A first coated area 1212 coated with the positive active material layer and a first uncoated area 1213 not coated with the positive active material layer are formed on the positive current collector 1211. The first coated area 1212 and the first uncoated area 1213 are arranged along the axial direction of the electrode assembly 102. The first uncoated area 1213 extends to the outside of the first separator 104 and the second separator 110 at one end in the height direction of the secondary battery 100, and bends towards the axis of the electrode assembly 102 to form a stacked positive electrode tab 125. The negative electrode tab 130 includes a negative current collector 1231 and a negative active material layer coated on the negative current collector 1231. A second coated area 1232 coated with the negative active material layer and a second uncoated area 1233 not coated with the negative active material layer are formed on the negative current collector 1231. The second coated area 1232 and the second uncoated area 1233 are arranged along the axial direction of the electrode assembly 102. The second uncoated area 1233 extends to the outside of the first separator 104 and the second separator 110 at the other end in the height direction of the secondary battery 100, and bends towards the axis of the electrode assembly 102 to form a stacked negative electrode tab 124; the first separator 104 and the second separator 110 are disposed between the positive electrode tab 128 and the negative electrode tab 130 to isolate the positive active material layer and the negative active material layer. Taking the lithium-ion secondary battery 100 as an example, the material of the positive current collector 1211 can be aluminum, the positive active material layer includes a positive active material, and the positive active material can be lithium cobaltate, lithium iron phosphate, ternary lithium, lithium manganate, etc. The material of the negative current collector 1231 can be copper, the negative active material layer includes a negative active material, and the negative active material can be carbon or silicon, etc.
[0038] With reference to Figure 3 and Figure 6As shown, generally speaking, considering the energy density, active material layers are coated on both opposite sides of the positive electrode plate 128 and the negative electrode plate 130. At the same time, the capacity of the positive electrode plate 128 is set to be less than that of the negative electrode plate 130 to avoid lithium precipitation on the negative electrode plate 130. Therefore, it is necessary to ensure that the ratio of the capacity of the positive electrode plate 128 to the capacity of the negative electrode plate 130 (hereinafter referred to as CB) is greater than 1. Since the capacity of the positive electrode plate 128 is set to be less than that of the negative electrode plate 130, the areal density of the positive active material layer is smaller. Correspondingly, the gap between the positive electrode plate 130 and the separator after winding is less, and thus the difficulty of the electrolyte infiltrating the positive electrode plate is greater. Therefore, in the embodiments of the present application, the adhesive layer 108 of the first separator 104 is set to face the positive electrode plate 128 directly, so as to increase the distance between the first base film 106 and the positive electrode plate 128. At the same time, the adhesive layer 114 of the second separator 110 is set to face the positive electrode plate 128 directly, so as to increase the distance between the second base film 112 and the positive electrode plate 128, thereby improving the infiltration of the positive electrode plate 128 with a smaller areal density.
[0039] Return reference Figure 4 As shown, in some embodiments, the first separator 104 further includes a heat-resistant layer 115 located between the first base film 106 and the adhesive layer 108. Generally speaking, in the prior art, the separator is usually a very thin PP (polypropylene) or PE (polyethylene), etc. During the battery cycle or when the battery is abnormal, the heat generated may cause the separator to thermally contract, resulting in the risk of short circuit due to the contact between the positive and negative electrode plates. In the embodiments of the present application, by making the first separator 104 include the heat-resistant layer 115 located between the first base film 106 and the adhesive layer 108, since the inorganic particles in the heat-resistant layer 115 have good heat resistance, the presence of the heat-resistant layer 115 can improve the heat resistance of the first separator 104, thereby reducing the risk of short circuit between the positive electrode plate 128 and the negative electrode plate 130. In Figure 3 As shown in the embodiments, the heat-resistant layer 115 can be in direct contact with the adhesive layer 108. Generally speaking, the adhesion of the inorganic particles in the heat-resistant layer 115 is poor. By setting the adhesive layer 108 to be in direct contact with the heat-resistant layer 115, the detachment of the heat-resistant layer 115 can be prevented. In some embodiments, the heat-resistant layer 115 can include at least one of alumina, boehmite, titanium oxide, etc. In this embodiment, the side of the second separator 110 facing the positive electrode plate 128 as Figure 5 shown does not include a heat-resistant layer, and correspondingly, the second base film 112 is in direct contact with the adhesive layer 114.
[0040] However, the heat-resistant layer 115 is optional. In some other embodiments, the side of the first separator 104 facing the positive electrode tab 128 may not include the heat-resistant layer 115. Correspondingly, the first base film 106 is in direct contact with the adhesive layer 108. In this embodiment, the second separator 110 further includes a heat-resistant layer between the second base film 112 and the adhesive layer 114, and the heat-resistant layer is in direct contact with the second base film 112. By including a heat-resistant layer between the second base film 112 and the adhesive layer 114 in the second separator 110, the heat resistance of the second separator 110 can be improved. In some embodiments, this heat-resistant layer may also include at least one of alumina, boehmite, titanium oxide, etc.
[0041] In some embodiments, the first base film 106 and the second base film 112 may be the same or different. In a preferred embodiment, the first base film 106 and the second base film 112 are the same. By making the first base film 106 and the second base film 112 the same, the properties of the two base films are consistent, so that the performance of the secondary battery 100 is better. In some embodiments, the materials of the first base film 106 and the second base film 112 may be at least one of high-density polyethylene, low-density polyethylene, linear low-density polyethylene, ultra-high molecular weight polyethylene, and polypropylene.
[0042] Figure 7 An enlarged schematic view of the region 140 of the first separator 104 of the electrode assembly 102 according to another embodiment of the present application is shown. Refer to Figure 7 and Figure 3 As shown, in some embodiments, the first base film 106 further includes a second surface 106s2 opposite to the first surface 106s1 of the first base film 106. It is not difficult to understand that the second surface 106s2 faces the negative electrode tab 130. The first separator 104 may further include a heat-resistant layer 117 on the second surface 106s2 of the first base film 106, and the heat-resistant layer 117 directly faces the negative electrode tab 130. The heat-resistant layer 117 may have the same material and thickness as the heat-resistant layer 115. In some embodiments, for the consideration of energy density and cost, the first separator 104 may also not include the heat-resistant layer 117. In some embodiments where the first separator 104 includes the heat-resistant layer 117, the heat-resistant layer 117 constitutes the outermost layer of the first separator 104 (i.e., directly facing the negative electrode tab 130) or as Figure 8 shown, the first separator 104 further includes an adhesive layer 118 on the heat-resistant layer 117. It is not difficult to understand that in this case, the adhesive layer 108 constitutes the outermost layer on the other side of the first separator 104.
[0043] In Figure 8In the illustrated embodiment, the glue layer 118 may have the same material and thickness as the glue layer 108 (or the glue layer 114 of the second separator 110). In this embodiment, the glue layer 108 and the glue layer 118 respectively constitute the outermost layers on opposite sides of the first separator 104 (i.e., directly facing the positive electrode plate 128 and the negative electrode plate 130, respectively). In other embodiments, the glue layer increases the distance between the electrode plate and the base film, which will affect the energy density. In addition, the cost of the glue layer is relatively high. Therefore, for considerations of energy density and cost, the first separator 104 may not include the third glue layer 118.
[0044] Figure 9 FIG. 1 is an enlarged schematic diagram of a region 150 of a second separator 110 of an electrode assembly 102 according to another embodiment of the present application. Figure 9 As shown, in some embodiments, the second base film 112 also includes a second surface 112s2 opposite to the first surface 112s1 of the second base film 112. It is not difficult to understand that the second surface 112s2 faces the negative electrode sheet 130. The second separator 110 may also include a heat-resistant layer (inorganic material layer) 119 located on the second surface 112s2 of the second base film 112, and the heat-resistant layer 119 directly faces the negative electrode sheet 130. In a further embodiment, the second separator 110 may also include a glue layer (binder layer) 120 located on the heat-resistant layer 119. The glue layer 120 may have the same material and thickness as the first glue layer 108 (or the second glue layer 114 of the second separator 110). The heat-resistant layer 119 may have the same material and thickness as the heat-resistant layer 115. In this case, the glue layer 114 and the glue layer 120 respectively constitute the outermost layers on the opposite sides of the second separator 110. In other embodiments, for considerations of energy density and cost, the second diaphragm 110 may not include at least one of the heat-resistant layer 119 and the glue layer 120. In some embodiments, the heat-resistant layer 119 constitutes the outermost layer of the second diaphragm 110. It is not difficult to understand that in this case, the second diaphragm 110 may not include the glue layer 120, and the glue layer 114 and the heat-resistant layer 119 respectively constitute the outermost layers on opposite sides of the second diaphragm 110.
[0045] In the embodiments of the present application, the thickness of each adhesive layer is in the range of 2-6 μm, and the thickness of each heat-resistant layer is in the range of 1-5 μm.
[0046] Figure 10 FIG. 1 is a perspective schematic diagram of a secondary battery 100 according to an embodiment of the present application. Figure 2 , Figure 3 and Figure 10As shown, the secondary battery 100 further includes a housing 200. The electrode assembly 102 is accommodated within the housing 200, and the housing 200 may contain one or more electrode assemblies 102. The housing 200 includes an end wall 202 and a side wall 204 surrounding the end wall 202. As long as a stable sealing and electrical connection relationship can be formed, the connection between the end wall 202 and the side wall 204 can be achieved in various ways, such as integral stamping, integral casting, or split welding. The surrounding of the side wall 204 is not limited. It can surround in a cylindrical or prismatic shape, or along any other closed-loop contour that can match the end wall 202. In this embodiment, the outer edge of the end wall 202 is circular, and the side wall 204 surrounds the outer edge of the end wall 202 in a cylindrical shape, and a circular opening 206 is formed at one end of the side wall 204 facing away from the end wall 202. An accommodation cavity is formed within the housing 200 surrounded by the end wall 202 and the side wall 204 for accommodating the electrode assembly 102, electrolyte, and other necessary battery components. Specifically, the diameter size of the housing 200 can be determined according to the specific size of the electrode assembly 102, such as 18 mm, 21 mm, 46 mm, etc. The material of the housing 200 can be various, such as copper, iron, aluminum, steel, aluminum alloy, etc. In order to prevent the housing 200 from rusting during long-term use, an anti-rust material such as metallic nickel can also be plated on the surface of the housing 200.
[0047] Furthermore, referring to Figure 2 As shown, in the present utility model, if the positive electrode tab 125 faces the end wall 202 or the opening 206, then the negative electrode tab 124 faces the other end of the housing 200. In Figure 2 the embodiment shown, the positive electrode tab 125 faces the end wall 202 and is electrically connected to the terminal post 208 to make the terminal post 208 positively charged. The negative electrode tab 124 faces the opening 206, and the housing 200 is electrically connected to the negative electrode tab 124, thereby being negatively charged. However, in other embodiments, the negative electrode tab 124 can also be connected to the terminal post 208, and the positive electrode tab 125 can be connected to the housing 200. A cover plate 212 is sealed and installed on the opening 206; the shape of the outer edge of the cover plate 212 corresponds to the shape of the opening 206 and is connected to the side wall 204 to seal the opening 206. The installation method of the cover plate 212 includes but is not limited to mechanical sealing or welding sealing. In this embodiment, the cover plate 212 is sealed and plugged on the opening 206 by means of mechanical sealing.
[0048] It should be understood that the various features of the embodiments of the present application can be replaced and combined. The above are only the preferred embodiments of the present application and are not intended to limit the present application. Any combination of the embodiments, as well as any modification, equivalent replacement, improvement, etc. made to the embodiments, shall be included within the protection scope of the present application.
Claims
1. A secondary battery, characterized in that: include: An electrode assembly formed by stacking and winding a first separator, a positive electrode sheet, a second separator and a negative electrode sheet; The first diaphragm includes a first base film and a coating layer on the first base film, and the second diaphragm includes a second base film and a coating layer on the second base film. The coating on the side of the first diaphragm and the second diaphragm facing the positive electrode sheet comprises a glue layer, A heat-resistant layer is provided on one side of the first diaphragm and the second diaphragm facing the positive electrode plate; or both the first diaphragm and the second diaphragm have no heat-resistant layer on one side facing the positive electrode plate and a heat-resistant layer is provided on one side of the first diaphragm and the second diaphragm facing the negative electrode plate.
2. The secondary battery according to claim 1, characterized in that: The positive electrode plate includes a concave surface and a convex surface on opposite sides, the glue layer of the first separator faces the convex surface of the positive electrode plate, and the glue layer of the second separator faces the concave surface of the positive electrode plate.
3. The secondary battery according to claim 1, characterized in that: The adhesive layer includes a polyvinylidene fluoride layer.
4. The secondary battery according to claim 1, characterized in that: The heat-resistant layer directly contacts one of the first base film and the second base film.
5. The secondary battery according to claim 1, characterized in that: The coating on the side of the first separator facing the negative electrode plate includes a heat-resistant layer, and the heat-resistant layer directly contacts the negative electrode plate.
6. The secondary battery according to claim 1, characterized in that: The coating on the side of the second separator facing the negative electrode plate includes a glue layer.
7. The secondary battery according to claim 6, characterized in that: The coating on the side of the second separator facing the negative electrode plate includes a heat-resistant layer located between the second base film and the glue layer.
8. The secondary battery according to claim 1, characterized in that: The secondary battery is a cylindrical battery.
9. A battery pack, characterized in that: A secondary battery comprising any one of claims 1 to 8.
10. An electronic device, characterized in that: The invention comprises at least one of the secondary battery according to any one of claims 1 to 8 and the battery pack according to claim 9.