Electrode assembly, battery and electric device

Abstract

The utility model provides an electrode assembly, a battery and an electric device, and relates to the technical field of batteries. The electrode assembly comprises a positive plate, a negative plate and a diaphragm, the diaphragm comprises a diaphragm body and a ceramic layer arranged on the diaphragm body, bonding layers are arranged on the surface, away from the ceramic layer, of the diaphragm body and the surface, away from the diaphragm body, of the ceramic layer, and the positive plate is connected with the ceramic layer through the bonding layer. And the negative plate is connected with the diaphragm body through the bonding layer. The electrode assembly can well ensure the interface performance.

Description

Technical Field

[0001] This application relates to the field of battery technology, and more specifically, to an electrode assembly, a battery, and an electrical device. Background Technology

[0002] Sodium-ion batteries, as an emerging battery technology, have received widespread attention worldwide in recent years. With their similar working principle to lithium-ion batteries and advantages of low cost and high safety, sodium-ion batteries are becoming a rising star in the field of energy storage.

[0003] During cycling, sodium-ion batteries produce gas due to internal chemical reactions. Gas accumulation and temperature rise can cause the electrode components to expand, leading to changes in internal battery pressure. This may cause a deterioration in the interface performance of the electrode components, resulting in sodium deposition, which affects battery performance and battery safety. Utility Model Content

[0004] The purpose of this application includes, for example, providing an electrode assembly that can better guarantee interface performance.

[0005] The purpose of this application also includes providing a battery that can better guarantee the interface performance of the electrode assembly.

[0006] The purpose of this application also includes providing an electrical device that can better guarantee the interface performance of the electrode assembly.

[0007] The embodiments of this application can be implemented as follows:

[0008] An embodiment of this application provides an electrode assembly including a positive electrode, a negative electrode, and a separator. The separator includes a separator body and a ceramic layer disposed on the separator body. An adhesive layer is disposed on the surface of the separator body facing away from the ceramic layer and the surface of the ceramic layer facing away from the separator body. The positive electrode is connected to the ceramic layer through the adhesive layer, and the negative electrode is connected to the separator body through the adhesive layer.

[0009] Optionally, the electrode assembly satisfies: 0.12T b ≤T a ≤0.24T b , among which, T a T is the thickness of the adhesive layer. b The thickness of the electrode assembly is given.

[0010] Optionally, the thickness of the adhesive layer is 2-5 μm.

[0011] Optionally, the adhesive layer includes an adhesive and an additive, wherein the adhesive is polyvinylidene fluoride and the additive includes a dispersant and a wetting agent.

[0012] Optionally, the positive electrode sheet includes a positive electrode aluminum foil, a positive electrode active coating, and an insulating coating. The positive electrode active coating and the insulating coating are disposed on two opposite surfaces of the positive electrode aluminum foil. On any surface of the positive electrode aluminum foil, the insulating coating is disposed around the edge of the positive electrode active coating and is connected to the positive electrode active coating.

[0013] Optionally, the positive electrode active coating includes a positive electrode active material, a conductive agent, and a binder, wherein the positive electrode active material is a sodium ion layered oxide, and the insulating coating includes one of alumina and boehmite.

[0014] Optionally, the negative electrode sheet includes a negative electrode aluminum foil and a negative electrode active coating, wherein the negative electrode active coating is disposed on both opposite surfaces of the negative electrode aluminum foil;

[0015] The negative electrode active coating includes a negative electrode active material, a conductive agent, and a binder. The negative electrode active material includes one of hard carbon, soft carbon, or mesophase carbon microspheres.

[0016] Optionally, the diaphragm body is made of polyethylene or polypropylene, and the ceramic layer includes an adhesive and one of alumina and burlite.

[0017] This application also provides a battery, including a housing, a top cover, and the electrode assembly, wherein the housing has a receiving cavity inside, the electrode assembly is disposed in the receiving cavity, and the top cover is connected to the housing to close the receiving cavity.

[0018] This application also provides an electrical device, including the battery described above.

[0019] The beneficial effects of the electrode assembly, battery, and power device provided in this application include, for example, ensuring better interface performance of the electrode assembly. The electrode assembly includes a positive electrode, a negative electrode, and a separator. The separator includes a separator body and a ceramic layer disposed on the separator body. An adhesive layer is disposed on the surface of the separator body facing away from the ceramic layer and on the surface of the ceramic layer facing away from the separator body. The positive electrode is connected to the ceramic layer through the adhesive layer, and the negative electrode is connected to the separator body through the adhesive layer. Because the positive electrode is connected to the ceramic layer through the adhesive layer, and the negative electrode is connected to the separator body through the adhesive layer, the positive electrode and the ceramic layer, and the negative electrode and the separator body, are tightly bonded, preventing the electrode assembly from becoming loose and improving the interface performance of the electrode assembly. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the electrode assembly in an embodiment of this application.

[0022] Icons: 100 - Electrode assembly; 110 - Positive electrode sheet; 111 - Positive electrode aluminum foil; 112 - Positive electrode active coating; 120 - Negative electrode sheet; 121 - Negative electrode aluminum foil; 122 - Negative electrode active coating; 130 - Separator; 131 - Separator body; 132 - Ceramic layer; 140 - Adhesive layer. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0024] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0025] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0026] In the description of this application, it should be noted that if terms such as "upper," "lower," "inner," or "outer" are used to indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship that the utility model product is usually placed in during use, they are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0027] Furthermore, the terms "first" and "second" are used only to distinguish descriptions and should not be interpreted as indicating or implying relative importance.

[0028] It should be noted that, where there is no conflict, the features in the embodiments of this application can be combined with each other.

[0029] As disclosed in the background section, sodium-ion batteries exhibit gas production during cycling due to internal chemical reactions. Gas accumulation and temperature increases cause electrode component expansion, leading to changes in internal battery pressure. This can deteriorate the interface performance of the electrode components, resulting in sodium deposition and impacting battery performance and safety. Embodiments of this application provide a battery that at least addresses the aforementioned technical problems.

[0030] Please refer to Figure 1 The battery provided in the embodiments of this application includes an electrode assembly 100, a housing and a top cover. The housing has a receiving cavity inside, the electrode assembly 100 is disposed in the receiving cavity, and the top cover is connected to the housing to close the receiving cavity.

[0031] The electrode assembly 100 includes a positive electrode 110, a negative electrode 120, and a separator 130. The separator 130 includes a separator body 131 and a ceramic layer 132 disposed on the separator body 131. An adhesive layer 140 is disposed on the surface of the separator body 131 facing away from the ceramic layer 132 and the surface of the ceramic layer 132 facing away from the separator body 131. The positive electrode 110 is connected to the ceramic layer 132 through the adhesive layer 140, and the negative electrode 120 is connected to the separator body 131 through the adhesive layer 140.

[0032] The electrode assembly 100 is formed by winding or stacking a positive electrode 110, a separator 130, and a negative electrode 120. An adhesive layer 140 is applied to the separator 130 by roller coating or spraying. The adhesive layer 140 disposed on the surface of the separator body 131 away from the ceramic layer 132 is the first adhesive layer, and the adhesive layer 140 disposed on the surface of the ceramic layer 132 away from the separator body 131 is the second adhesive layer. The negative electrode 120 is disposed on the side of the first adhesive layer away from the separator body 131, and the positive electrode 110 is disposed on the side of the second adhesive layer away from the ceramic layer 132. The first adhesive layer bonds the negative electrode 120 and the separator body 131, and the second adhesive layer bonds the positive electrode 110 and the ceramic layer 132.

[0033] Because the first adhesive layer bonds the negative electrode 120 and the separator body 131, and the second adhesive layer bonds the positive electrode 110 and the ceramic layer 132, the positive electrode 110 and the ceramic layer 132, and the negative electrode 120 and the separator body 131 are bonded more tightly, and the electrode assembly 100 is less likely to become loose inside, thereby improving the interface performance of the electrode assembly 100.

[0034] In the electrode assembly 100, adhesive layers 140 are provided on both sides of the diaphragm 130 near the interior of the electrode assembly 100, while the outermost diaphragm 130 in the electrode assembly 100 does not contact the electrode sheet, and no adhesive layer 140 is provided there.

[0035] The top cover is equipped with a positive terminal, a negative terminal, an explosion-proof valve, and a liquid injection port. The positive terminal 110 is equipped with a positive tab, and the negative terminal 120 is equipped with a negative tab. The positive tab is directly connected to the positive terminal or connected through an adapter plate, and the negative tab is directly connected to the negative terminal or connected through an adapter plate.

[0036] In this embodiment, the electrode assembly 100 satisfies: 0.12T b ≤T a ≤0.24T b , among which, T a The thickness of the adhesive layer 140 is in μm, T b The thickness of electrode assembly 100 is in mm. The thickness of the first adhesive layer and the second adhesive layer are equal, both being T. a T b The thickness is the sum of the thickness of all the positive electrode 110, separator 130 and negative electrode 120 in the electrode assembly 100.

[0037] When the electrode assembly 100 is relatively thick, the radius of its R-corner portion is large. If the adhesive layer 140 is also thick, the gap between the electrode and the separator 130 will be too large, resulting in significant impedance and potentially causing sodium deposition. Conversely, if the adhesive layer 140 is too thin, the adhesion between the electrode and the separator 130 will be insufficient. Therefore, the thickness T of the adhesive layer 140 is... a Limited to a reasonable range, namely 0.12T b ≤T a ≤0.24T b This not only makes it less likely to cause sodium precipitation, but also ensures a more thorough bond between the electrode and the diaphragm 130.

[0038] In this embodiment, the thickness T of the adhesive layer 140 is... a It is 2-5μm.

[0039] For example, the thickness T of the adhesive layer 140 a The thickness T of the adhesive layer 140 is 2μm, 3μm, 4μm or 5μm. a In the case of 2-5μm, the thickness T of the adhesive layer 140 a Within a reasonable range, it is not easy to cause sodium precipitation problems, and it also ensures sufficient adhesion between the electrode and the diaphragm 130.

[0040] Furthermore, the adhesive strength of the adhesive layer 140 has a significant impact on battery performance. During battery operation, the adhesive layer 140 should not detach from the separator 130. After the electrode assembly 100 undergoes hot pressing, the separator 130 is bonded to the positive and negative electrode sheets 120 via the adhesive layer 140. The adhesive layer 140 satisfies the following conditions: f1 > f2, and f1 > f3, where f1 is the adhesive force between the adhesive layer 140 and the separator 130, f2 is the adhesive force between the adhesive layer 140 and the positive electrode sheet 110, and f3 is the adhesive force between the adhesive layer 140 and the negative electrode sheet 120. The units of f1, f2, and f3 are all N / m. The adhesive force between the adhesive layer 140 and the separator 130 is controlled by the coating coverage of the adhesive layer 140. The greater the coating coverage of the adhesive layer 140 on the separator 130, the greater the adhesive force. The adhesive force between the adhesive layer 140 and the positive and negative electrode sheets 120 is achieved through the hot pressing process of the electrode assembly 100.

[0041] In this embodiment, the adhesive layer 140 includes an adhesive and an additive. The adhesive is polyvinylidene fluoride, and the additive includes a dispersant and a wetting agent.

[0042] It should be noted that polyvinylidene fluoride, or PVDF for short, is a standard binder used in batteries; dispersants are mainly used to improve the dispersion of active materials and conductive agents in electrode materials, reduce particle agglomeration, and optimize slurry viscosity; wetting agents are mainly used to improve the wettability and uniformity of the coating, reduce defects in production, and directly improve the performance and reliability of the battery by improving coating quality.

[0043] In this embodiment, the positive electrode sheet 110 includes a positive electrode aluminum foil 111, a positive electrode active coating 112, and an insulating coating. The positive electrode active coating 112 and the insulating coating are provided on both opposite surfaces of the positive electrode aluminum foil 111. On any surface of the positive electrode aluminum foil 111, the insulating coating is provided around the edge of the positive electrode active coating 112, and the insulating coating is connected to the positive electrode active coating 112.

[0044] On any surface of the positive electrode aluminum foil 111, the area of ​​the positive electrode aluminum foil 111 located outside the insulating coating is the empty foil area, which is used to form the electrode tab.

[0045] By setting an insulating coating at the edge of the positive electrode active coating 112, the safety and stability of the battery are improved and short circuits are prevented.

[0046] In this embodiment, the positive electrode active coating 112 includes a positive electrode active material, a conductive agent, and a binder. The positive electrode active material is a sodium ion layered oxide, and the insulating coating includes one of alumina and boehmite.

[0047] The general structural formula of sodium ion layered oxides is NaxMO2, where M is one or more transition metals.

[0048] In other embodiments, the positive electrode active material may be other active materials besides sodium ion layered oxides, and the insulating coating may include both alumina and boehmite.

[0049] In this embodiment, the negative electrode sheet 120 includes a negative electrode aluminum foil 121 and a negative electrode active coating 122. The negative electrode active coating 122 is provided on both opposite surfaces of the negative electrode aluminum foil 121. The negative electrode active coating 122 includes a negative electrode active material, a conductive agent and a binder. The negative electrode active material includes one of hard carbon, soft carbon and mesophase carbon microspheres.

[0050] In other embodiments, the negative electrode active material includes two or more of hard carbon, soft carbon, and mesophase carbon microspheres.

[0051] In this embodiment, the diaphragm body 131 is made of polyethylene or polypropylene, and the ceramic layer 132 includes an adhesive and one of alumina and burlite.

[0052] It should be noted that polyethylene and polypropylene are commonly used substrates for the diaphragm 130, and the diaphragm body 131 is composed of at least one multilayer composite of polyethylene and polypropylene; the ceramic layer 132 includes an adhesive and alumina, or includes an adhesive and borosilicate, wherein the adhesive may be polyvinylidene fluoride.

[0053] The beneficial effects of the battery in this application are illustrated by examples and comparative examples:

[0054] Example 1: The battery has a width of 73mm, a length of 174mm, and a height of 207mm. Each battery contains four parallel electrode assemblies 100. The electrode assembly 100 has a width of 16.6mm, a length of 170mm, and a height of 207mm. The thickness of the separator body 131 in the electrode assembly 100 is 9μm.

[0055] During battery manufacturing, a ceramic layer 132 with a thickness of 3μm is first applied to one side of the separator body 131 using a coating machine. Then, an adhesive coating machine is used to coat the separator 130. By setting the parameters of the adhesive coating machine, a 3μm thick adhesive layer 140 is applied to both sides of the separator 130. The adhesive layer 140 covers 20% of the total area of ​​the separator body 131, achieving an adhesion force of 3±0.2 N / m between the adhesive layer 140 and the separator body 131. The adhesion force can be measured using a tensile testing machine. The battery is then manufactured using a combination of positive electrode 110, separator 130, and negative electrode 120. The electrodes are stacked in sequence and then wound to form electrode assembly 100. Then, hot pressing is performed at a pressure of 5 tons, a temperature of 90°C, and a time of 40 seconds. This makes the adhesion force between the adhesive layer 140 and the positive and negative electrode sheets 120 2.5±0.2N / m. After hot pressing, the adhesive layer 140 on the separator 130 is in a molten state, which can firmly bond the electrode sheets on both sides of the separator 130. Then, the electrode assembly 100 is inserted into the shell, welded to the cover plate, wrapped with Mylar film, and finally sealed and welded. After sealing and welding, the battery needs to be baked. After baking, processes such as liquid injection, formation, and capacity testing are performed.

[0056] Example 2: Example 2 is basically the same as Example 1, except that the thickness of the adhesive layer 140 in Example 2 is 4.5 μm.

[0057] Example 3: Example 3 is basically the same as Example 1, except that the thickness of the adhesive layer 140 in Example 3 is 2μm.

[0058] Comparative Example 1: The difference between Comparative Example 1 and Example 1 is that the electrode assembly 100 in Comparative Example 1 adopts a conventional structure and does not have an adhesive layer 140 on both sides of the diaphragm 130.

[0059] Comparative Example 2: The difference between Comparative Example 2 and Example 1 is that the thickness of the adhesive layer 140 in Comparative Example 2 is 6 μm.

[0060] Comparative Example 3: The difference between Comparative Example 3 and Example 1 is that the thickness of the adhesive layer 140 in Comparative Example 3 is 1 μm.

[0061] Twenty sets of batteries were prepared using the above-described examples and comparative examples, and cycle tests were conducted on the batteries under identical conditions. The test results are as follows:

[0062] After 100 cycles, no expansion was observed in the battery prepared in Example 1. After disassembly, no sodium deposition was observed inside the battery, and the tested internal resistance was 0.186 mΩ.

[0063] After 100 cycles, no expansion was observed in the battery prepared in Example 2. After disassembly, no sodium deposition was observed inside the battery, and the internal resistance was measured to be 0.191 mΩ.

[0064] After 100 cycles, no expansion was observed in the battery prepared in Example 3. After disassembly, no sodium deposition was observed inside the battery, and the tested internal resistance was 0.182 mΩ.

[0065] The battery prepared in Comparative Example 1 showed significant expansion after 100 cycles. After disassembly, severe sodium deposition was found inside the battery, and the measured internal resistance was 0.268 mΩ.

[0066] After 100 cycles, the battery prepared in Comparative Example 2 showed slight expansion. After disassembly, sodium was deposited at the R-corner inside the battery, and the internal resistance was measured to be 0.237 mΩ.

[0067] The battery prepared in Comparative Example 3 showed significant expansion after 100 cycles. After disassembly, sodium was deposited inside the battery, and the internal resistance was measured to be 0.243 mΩ.

[0068] As can be seen from the above embodiments and comparative examples, the performance of the battery can be significantly improved by setting an adhesive layer on both sides of the separator 130. However, the thickness of the adhesive layer needs to be controlled within a certain range. If the adhesive layer is too thick, sodium is easily deposited at the R-corner inside the battery. If the adhesive layer is too thin, it will lead to insufficient adhesion.

[0069] Embodiments of this application also provide an electrical device, including the battery described above. For example, the electrical device can be a vehicle, ship, spacecraft, etc. Vehicles can be gasoline-powered vehicles or new energy vehicles; new energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc.; spacecraft include airplanes, rockets, space shuttles, and spacecraft, etc. Embodiments of this application do not impose special limitations on the aforementioned electrical device.

[0070] In summary, the embodiments of this application provide an electrode assembly 100, a battery, and an electrical device. By providing an adhesive layer 140, the bonding force between the positive electrode 110 and the separator 130, and between the separator 130 and the negative electrode 120, is improved. This improved bonding force between the electrode and the separator 130 prevents the internal structure of the electrode assembly 100 from becoming loose, thereby improving the cycle performance and safety performance of the battery. By controlling the relationship between the thickness of the adhesive layer 140 and the thickness of the electrode assembly 100, the problems of excessively large R-angle gaps due to an excessively thick adhesive layer 140, and insufficient bonding force due to an excessively thin adhesive layer 140 are avoided. By controlling the bonding force between the adhesive layer 140 and the separator 130, the bonding force between the adhesive layer 140 and the positive electrode 110, and the bonding force between the adhesive layer 140 and the negative electrode 120, the phenomenon of the adhesive layer 140 detaching from the separator 130 during battery operation can be prevented.

[0071] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. An electrode assembly, characterized by, The battery comprises a positive electrode sheet, a negative electrode sheet and a separator, the separator comprises a separator body and a ceramic layer arranged on the separator body, the surface of the separator body away from the ceramic layer and the surface of the ceramic layer away from the separator body are both provided with a bonding layer, the positive electrode sheet is connected with the ceramic layer through the bonding layer, and the negative electrode sheet is connected with the separator body through the bonding layer.

2. The electrode assembly of claim 1, wherein, The electrode assembly satisfies: 0.12T b ≤ T a ≤ 0.24T b , where T a is the thickness of the adhesive layer, and T b is the thickness of the electrode assembly.

3. The electrode assembly of claim 1, wherein, The thickness of the bonding layer is 2-5 microns.

4. The electrode assembly of claim 1, wherein, The bonding layer comprises a binder and an auxiliary agent, the binder is polyvinylidene fluoride, and the auxiliary agent comprises a dispersing agent and a wetting agent.

5. The electrode assembly of claim 1, wherein, The positive electrode sheet comprises a positive electrode aluminum foil, a positive electrode active coating layer and an insulating coating layer, the opposite surfaces of the positive electrode aluminum foil are both provided with the positive electrode active coating layer and the insulating coating layer, on any surface of the positive electrode aluminum foil, the insulating coating layer is arranged around the edge of the positive electrode active coating layer, and the insulating coating layer is connected with the positive electrode active coating layer.

6. The electrode assembly of claim 5, wherein, The positive electrode active coating layer comprises a positive electrode active material, a conductive agent and a binder, the positive electrode active material is sodium ion layered oxide, and the insulating coating layer comprises one of alumina and bohemite.

7. The electrode assembly of claim 1, wherein, The negative electrode sheet comprises a negative electrode aluminum foil and a negative electrode active coating layer, the opposite surfaces of the negative electrode aluminum foil are both provided with the negative electrode active coating layer. The negative electrode active coating layer comprises a negative electrode active material, a conductive agent and a binder, the negative electrode active material comprises one of hard carbon, soft carbon and mesocarbon microbead.

8. The electrode assembly of claim 1, wherein, The separator body is made of polyethylene or polypropylene material, and the ceramic layer comprises a binder and one of alumina and bohemite.

9. A battery, characterized by The battery comprises a shell, a top cover and the electrode assembly of any one of claims 1-8, the shell is internally provided with a containing cavity, the electrode assembly is arranged in the containing cavity, and the top cover is connected with the shell to close the containing cavity.

10. An electrical device, characterized by The battery comprises the battery of claim 9.

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