Tab and method for manufacturing the same

Abstract

The present application relates to a tab and a manufacturing method thereof. The tab comprises: a body made of a metal material; and a coating coated on at least one surface of the body, the coating comprising a material having a higher specific heat than the body, wherein the coating extends a predetermined distance from an edge of the body close to a membrane region into the body without completely covering the body.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and more specifically to a tab and a method for manufacturing the tab. Background Art

[0002] The tab is one of the components of the battery (such as a secondary battery) cell, used to conduct electricity and transmit electrons. At present, the main material of the negative tab is copper, and the main material of the positive tab is aluminum. The cylindrical tabs are flattened and then laser welded with the collector plate. The collector plate and the top cover are self-contained, thus forming an electronic path from the bare cell to the tab to the collector plate to the top cover pole.

[0003] However, there are defects in flattening the cylinder. For example, after flattening, the heat dissipation inside the bare cell slows down, exhaust is difficult, and the temperature of the tab is high. Especially for the negative electrode, the increase in temperature during high-rate discharge will create safety risks. This application has made improvements in response to but not limited to the above factors. Summary of the invention

[0004] To this end, the present application proposes a new type of pole ear, which has a large specific heat. Under the same heat condition, its temperature rises very slowly, thereby reducing the pole ear temperature (especially the temperature of the negative pole ear) during battery discharge (especially high-rate discharge). In addition, the pole ear of the present application can also absorb harmful gases generated inside the battery cell, thereby reducing the internal pressure of the battery cell and thus improving the safety performance of the battery cell.

[0005] According to the first aspect of the present application, a tab is provided, comprising: a body made of a metal material; and a coating coated on at least one surface of the body, the coating comprising a material having a higher specific heat than the body, wherein the coating extends a predetermined distance from the edge of the body close to the membrane region into the body without completely covering the body. In this embodiment, the tab of the present application can effectively reduce the temperature of the tab, and thereby improve the safety performance of the battery cell, without using external devices, increasing its weight and volume, and reducing the energy density of the battery cell.

[0006] According to another embodiment, the coating includes a gas absorbing material and a binder. The tab obtained in this embodiment can not only effectively reduce the temperature of the tab, but also more efficiently absorb the gas generated inside the battery cell, thereby more efficiently reducing the internal pressure of the battery cell, thereby further improving the safety performance of the battery cell.

[0007] According to another embodiment, the gas absorbing material accounts for 80%-90% of the total mass of the coating, and the adhesive accounts for 10%-20% of the total mass of the coating. In this embodiment, the obtained tab not only has a coating with sufficient adhesive force, but also can effectively reduce the temperature of the tab, and can more efficiently absorb the gas generated inside the battery cell, thereby more efficiently reducing the internal pressure of the battery cell, and thus further improving the safety performance of the battery cell.

[0008] According to another embodiment, the gas absorption material includes any one or more of NaOH, CaO, CaOH, Na2O, and activated carbon, and the binder includes PVDF. The tabs obtained in this embodiment can not only effectively reduce the temperature of the tabs, but also more efficiently absorb the gas (such as CO2, etc.) generated inside the battery cell, thereby more efficiently reducing the internal pressure of the battery cell, and thereby further improving the safety performance of the battery cell.

[0009] According to another embodiment, the thickness of the coating is less than 1.5 μm. Therefore, in this embodiment, the coating will not be too thick to cause a decrease in the conductivity of the tab and a waste of materials, and can provide sufficient effects of reducing the tab temperature and the pressure in the battery cell, thereby further improving the safety performance of the battery cell.

[0010] According to another embodiment, the thickness of the coating is between 0.5-1.3 μm. Therefore, in this embodiment, the coating will not be too thick to cause a decrease in the conductivity of the tab and a waste of materials, and can provide a better effect of reducing the tab temperature and the pressure in the battery cell, thereby further improving the safety performance of the battery cell.

[0011] According to another embodiment, the thickness of the coating is 1 μm. Therefore, in this embodiment, the coating will not be too thick to cause a decrease in the conductivity of the tab and a waste of materials, and can provide the best effect of reducing the tab temperature and the pressure in the battery cell, thereby further improving the safety performance of the battery cell.

[0012] According to another embodiment, the predetermined distance is between 0.5-3 mm. Thus, in this embodiment, the coating will not occupy too much area of ​​the tab to affect welding, nor will it adversely affect the flow area (a reduction in the flow area will lead to excessive current and increased temperature), thereby avoiding safety risks. At the same time, the coating can provide a better effect of reducing the tab temperature and reducing the pressure in the battery cell, thereby further improving the safety performance of the battery cell.

[0013] According to another embodiment, the predetermined distance is 2 mm. Thus, in this embodiment, the coating will not occupy too much area of ​​the tab to affect welding, nor will it adversely affect the flow area (a reduction in the flow area will lead to excessive current and increased temperature), thereby avoiding safety risks. At the same time, the coating can provide a better effect of reducing the tab temperature and reducing the pressure in the battery cell, thereby further improving the safety performance of the battery cell.

[0014] According to another embodiment, the coating is coated on both the front and back sides of the body. In this embodiment, considering that a certain space generally remains between the bare cell and the outer shell when the bare cell is encased, the front coating can absorb the gas in the residual space, while the back coating can absorb the gas in the bare cell. In this way, the coating on both sides can provide a better effect of reducing the temperature of the tabs and reducing the pressure inside and outside the cell, thereby further improving the safety performance of the cell.

[0015] According to another embodiment, the main body is made of copper, nickel, copper-plated nickel or aluminum. The tab obtained in this embodiment can be used as a positive tab or a negative tab, depending on the different main materials thereof. For example, the main body of the positive tab can be made of aluminum, while the main body of the negative tab can be made of copper, nickel, copper-plated nickel, etc.

[0016] According to a second aspect of the present application, a method for manufacturing a tab is provided, comprising: using a metal material to manufacture a tab body; using a material having a higher specific heat than the metal material to manufacture a coating slurry; coating the slurry on at least one surface of the tab body to form a coating, wherein the coating extends a predetermined distance from the edge of the body close to the membrane region to the inside of the body without completely covering the body; and drying the coated tab body. In this embodiment, the tab manufactured can effectively reduce the temperature of the tab, thereby improving the safety performance of the battery cell, without using external devices, increasing its weight and volume, and reducing the energy density of the battery cell.

[0017] According to one embodiment, the coating comprises a gas absorbing material and a binder, and the gas absorbing material comprises any one or more of NaOH, CaO, CaOH, Na2O, and activated carbon, and the binder comprises PVDF. The tabs obtained in this embodiment can not only effectively reduce the temperature of the tabs, but also at least partially absorb the harmful gases generated inside the battery cell, thereby reducing the internal pressure of the battery cell, and thus further improving the safety performance of the battery cell.

[0018] According to another embodiment, the gas absorbing material accounts for 80%-90% of the total mass of the coating, and the adhesive accounts for 10%-20% of the total mass of the coating. In this embodiment, the obtained tab not only has a coating with sufficient adhesive force, but also can effectively reduce the temperature of the tab, and can more efficiently absorb the gas generated inside the battery cell, thereby more efficiently reducing the internal pressure of the battery cell, and thus further improving the safety performance of the battery cell.

[0019] According to another embodiment, the thickness of the coating is between 0.5 and 1.5 μm. Therefore, in this embodiment, the coating will not be too thick to cause a decrease in the conductivity of the tab and a waste of materials, and can provide sufficient effects of reducing the tab temperature and the pressure in the battery cell, thereby further improving the safety performance of the battery cell.

[0020] According to another embodiment, the thickness of the coating is between 0.5-1.3 μm. Therefore, in this embodiment, the coating will not be too thick to cause a decrease in the conductivity of the tab and a waste of materials, and can provide a better effect of reducing the tab temperature and the pressure in the battery cell, thereby further improving the safety performance of the battery cell.

[0021] According to another embodiment, the thickness of the coating is 1 μm. Therefore, in this embodiment, the coating will not be too thick to cause a decrease in the conductivity of the tab and a waste of materials, and can provide the best effect of reducing the tab temperature and the pressure in the battery cell, thereby further improving the safety performance of the battery cell.

[0022] According to another embodiment, the predetermined distance is between 0.5-3 mm. Thus, in this embodiment, the coating will not occupy too much area of ​​the tab to affect welding, nor will it adversely affect the flow area (a reduction in the flow area will lead to excessive current and increased temperature), thereby avoiding safety risks. At the same time, the coating can provide a better effect of reducing the tab temperature and reducing the pressure in the battery cell, thereby further improving the safety performance of the battery cell.

[0023] According to another embodiment, the predetermined distance is 2 mm. Thus, in this embodiment, the coating will not occupy too much area of ​​the tab to affect welding, nor will it adversely affect the flow area (a reduction in the flow area will lead to excessive current and increased temperature), thereby avoiding safety risks. At the same time, the coating can provide a better effect of reducing the tab temperature and reducing the pressure in the battery cell, thereby further improving the safety performance of the battery cell.

[0024] According to another embodiment, the coating is coated on both the front and back sides of the body. In this embodiment, considering that a certain space generally remains between the bare cell and the outer shell when the bare cell is encased, the front coating can absorb the gas in the residual space, while the back coating can absorb the gas in the bare cell. In this way, the coating on both sides can provide a better effect of reducing the temperature of the tabs and reducing the pressure inside and outside the cell, thereby further improving the safety performance of the cell.

[0025] According to another embodiment, the main body is made of copper, nickel, copper-plated nickel or aluminum. The tab obtained in this embodiment can be used as a positive tab or a negative tab, depending on the different main materials thereof. For example, the main body of the positive tab can be made of aluminum, while the main body of the negative tab can be made of copper, nickel, copper-plated nickel, etc.

[0026] According to a third aspect of the present application, there is provided a battery cell comprising a tab according to the first aspect of the present application, wherein the tab is integrated into the battery cell by flattening and welding to a current collecting plate. In this embodiment, the obtained battery cell adopts the tab of the first aspect of the present application, so that the temperature of the tab is lowered compared with the temperature of the existing tab, and the gas inside and outside the battery cell is also absorbed, thereby improving the safety performance of the battery cell.

[0027] According to the fourth aspect of the present application, a secondary battery including a battery cell according to the fourth aspect of the present application is provided. In this embodiment, the obtained secondary battery adopts the battery cell according to the third aspect of the present application, so that the temperature of the battery cell tab is lower than that of the existing tab, and the gas inside and outside the battery cell is also absorbed, thereby improving the safety performance of the secondary battery.

[0028] According to the fifth aspect of the present application, an electrical device using the secondary battery according to the fourth aspect of the present application as a power source is provided. In this embodiment, the obtained battery cell uses the secondary battery according to the fourth aspect of the present application, so that the temperature of the battery cell tab is lower than that of the existing tab, and the gas inside and outside the battery cell is also absorbed, thereby improving the safety performance of the electrical device.

[0029] A brief summary of one or more aspects is given above to provide a basic understanding of these aspects. This summary is not an exhaustive overview of all conceived aspects, and is neither intended to identify the key or critical elements of all aspects nor to define the scope of any or all aspects. Its only purpose is to give some concepts of one or more aspects in a simplified form as a prelude to a more detailed description that will be given later. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The above features and advantages of the present application can be better understood after reading the detailed description of the embodiments of the present application in conjunction with the following drawings. In the drawings, the components are not necessarily drawn to scale, and components with similar related properties or features may have the same or similar reference numerals.

[0031] Figure 1 is a schematic diagram of a tab according to an embodiment of the present application;

[0032] Figure 2 and Figure 3 is a schematic diagram of an example battery cell according to one embodiment of the present application.

[0033] Figure 4 is a schematic diagram of a secondary battery according to one embodiment of the present application.

[0034] Figure 5 yes Figure 4 An exploded view of a secondary battery is shown.

[0035] Figure 6 This is a schematic diagram of an embodiment of a device using the secondary battery of the present application as a power source.

[0036] Description of reference numerals:

[0037] 100 tab; 101 body; 102 coating; 201 tab body; 202 coating; 203 membrane area; 301 tab; 303 bare cell; 5 secondary battery; 51 shell; 52 electrode assembly; 53 top cover assembly; 600 device. DETAILED DESCRIPTION

[0038] The present application is described in detail below in conjunction with the accompanying drawings and specific embodiments. Note that the aspects described below in conjunction with the accompanying drawings and specific embodiments are only exemplary and should not be construed as limiting the scope of protection of the present application in any way.

[0039] "Scope" disclosed herein is defined in the form of lower limit and upper limit, and a given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a particular range. The scope defined in this way can be including end values ​​or not including end values, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a scope. For example, if the scope of 60-120 and 80-110 is listed for a particular parameter, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range values ​​1 and 2 are listed, and if the maximum range values ​​3, 4 and 5 are listed, the following scope can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In this application, unless otherwise specified, the numerical range "ab" represents the abbreviation of any real number combination between a and b, wherein a and b are real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" are listed in this document, and "0-5" is just an abbreviation of these numerical combinations. In addition, when a parameter is expressed as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0040] In this application, unless otherwise specified, all embodiments and preferred embodiments mentioned herein can be combined with each other to form a new technical solution.

[0041] In this application, unless otherwise specified, all technical features and preferred features mentioned herein can be combined with each other to form a new technical solution.

[0042] In the present application, unless otherwise specified, all steps mentioned herein may be performed sequentially or randomly, but are preferably performed sequentially. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), which means that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0043] In this application, unless otherwise specified, the terms "include" and "comprising" mentioned herein may be open-ended or closed-ended. For example, the terms "include" and "comprising" may mean that other components not listed may also be included or only the listed components may be included or only the listed components may be included.

[0044] In the description herein, unless otherwise specified, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, any of the following conditions satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0045] Tab

[0046] Reference now Figure 1 , which shows a schematic diagram of a tab according to an embodiment of the present application. Figure 1 As shown, the tab 100 includes a main body 101 and a coating 102 coated on at least one surface of the main body 101. In one embodiment, the main body 101 may be made of a metal material, such as copper, aluminum, nickel, copper-plated nickel, etc. When used as a negative electrode tab, the main body 101 may be made of copper, nickel or copper-plated nickel; when used as a positive electrode tab, the main body 101 may be made of aluminum. Those skilled in the art will understand that the tab 100 can be used as a negative electrode tab or a positive electrode tab according to the material of its main body, and the shape, size, etc. of the tab 100 can be selected as needed (for example, a copper foil several microns thick can be used as the main body of the negative electrode tab), which will not be repeated here.

[0047] In one embodiment, the coating 102 may include a material having a higher specific heat than the body 101. It will be understood by those skilled in the art that specific heat, also known as specific heat capacity, refers to the amount of heat required to raise the temperature of 1 kg of a homogeneous substance by 1K without phase change and chemical change. For example, in the case where the tab 100 is to be used as a negative tab and therefore copper is used as the body 101, the coating 102 may include a material having a higher specific heat than copper; in the case where the tab 100 is to be used as a positive tab and therefore aluminum is used as the body 101, the coating 102 may include a material having a higher specific heat than aluminum. In this embodiment, the tab 100 can effectively reduce the temperature of the tab, thereby improving the safety performance of the battery cell, without using external devices, increasing its weight and volume, and reducing the energy density of the battery cell.

[0048] In another embodiment of the present application, considering that various gases may be generated in the battery cell, the material of the coating 102 may include a gas absorbing material and an adhesive. The adhesive can adhere the coating 102 to the main body 101, and the gas absorbing material can absorb the gas generated in the battery cell, and further increase the specific heat of the coating 102 and reduce the pressure in the battery cell. In a preferred embodiment, the coating 102 may include an oxide and / or hydroxide of an alkali metal and / or an alkaline earth metal as a gas absorbing material, and the adhesive includes PVDF. For example, the coating 102 may include any one or more of NaOH, CaO, CaOH, and Na2O. In another preferred embodiment, the coating 102 may include activated carbon as a gas absorbing material.

[0049] In another embodiment of the present application, the material of the coating 102 may be selected depending on the composition of the gas generated inside the battery cell. For example, in the case where a large amount of CO is generated in the battery cell, the material of the coating 102 may preferably include activated carbon, which can increase the specific heat of the tab 100 so that its temperature does not rise too quickly, and can absorb the CO in the battery cell to reduce the pressure inside the battery cell; in the case where a large amount of CO2 is generated in the battery cell, the material of the coating 102 may preferably include Na2O, which can increase the specific heat of the tab 100 so that its temperature does not rise too quickly, and can react with CO2 to generate Na2CO3 (which further increases the specific heat of the tab 100) and reduce the pressure inside the battery cell at the same time. Therefore, in another embodiment of the present application, the coating 102 may include various suitable materials mixed in any suitable proportion, such as a mixture of Na2O and activated carbon, a mixture of Na2O and CaO and activated carbon, any other suitable gas absorbing material, and the like. In these embodiments, the tab 100 can not only effectively reduce the temperature of the tab, but also efficiently absorb the gases (such as CO2, ethylene, hydrogen, etc.) generated inside the battery cell, thereby efficiently reducing the internal pressure of the battery cell and further improving the safety performance of the battery cell.

[0050] According to another embodiment, in order to ensure that the pole ear 100 not only has a coating with sufficient adhesion, but also can effectively reduce the temperature of the pole ear and more efficiently absorb the gas generated inside the battery cell, thereby more efficiently reducing the internal pressure of the battery cell, and thereby further improving the safety performance of the battery cell, the gas absorption material accounts for 80%-90% of the total mass of the coating 102, and the adhesive accounts for 10%-20% of the total mass of the coating 102.

[0051] According to another embodiment of the present application, further considering the conductivity of the tab 100, the thickness of the coating 102 may be less than 1.5 μm. Preferably, the thickness of the coating 102 may be between 0.5 and 1.3 μm. More preferably, the thickness of the coating 102 may be 1 μm. Thus, in this embodiment, the coating will not be too thick to cause a decrease in the conductivity of the tab and a waste of materials, and at the same time, it can provide sufficient effects of reducing the tab temperature and reducing the pressure in the battery cell, thereby further improving the safety performance of the battery cell.

[0052] In another embodiment of the present application, the coating 102 does not completely cover the main body 101. Figure 1 In this embodiment, the coating 102 is coated on the edge of the main body 101 close to the membrane area, extending into the main body by a predetermined distance d, without completely covering the main body 101. Further according to this embodiment, the coating 102 extends from the edge of the main body 101 close to the membrane area into the main body 101 by a predetermined distance (i.e., the width of the coating 102) between 0.5-3 mm. Figure 1 As shown, the predetermined distance d can be between 0.5-3 mm. In a preferred embodiment, the predetermined distance d can be 2 mm. This will be shown and described in more detail below in relation to 2-3. Thus, in this embodiment, the coating will not occupy too much of the lug area to affect welding, nor will it adversely affect the flow area (a reduction in the flow area will result in excessive current and increased temperature), thereby avoiding safety risks. At the same time, the coating can provide a better effect of reducing the lug temperature and reducing the pressure in the battery cell, thereby further improving the safety performance of the battery cell.

[0053] although Figure 1 The coating 102 is shown to be continuously coated on the entire length of the main body, but in another embodiment of the present application, the coating 102 may not be continuous, but may be segmented or occupy only a portion of the entire length of the main body.

[0054] Although as mentioned above, the specific range of the width and thickness of the coating 102 is given in the present application, this is only for illustrative purposes. The coating 102 can have any suitable thickness and width without affecting the integration of the tab body and the battery cell and the coating can provide sufficient high specific heat performance.

[0055] It will be appreciated that the body 101 of the tab 100 is generally a metal foil, such as Figure 1A view of the front side of the tab is given. In one embodiment of the present application, the same is true for the back side of the tab, that is, the coating 102 is coated on both the front and back sides of the main body 101. In this embodiment, considering that a certain space generally remains between the bare cell and the outer shell when the bare cell is shelled, the front coating can absorb the gas in the residual space, while the back coating can absorb the gas in the bare cell. In this way, the coating on both sides can provide a better effect of reducing the temperature of the tab and reducing the pressure inside and outside the cell, thereby further improving the safety performance of the cell.

[0056] Manufacturing method of tab

[0057] The following describes a method for manufacturing a tab according to an embodiment of the present application. In one embodiment, the manufacturing method of the present application may include using a metal material to make a tab body. Figure 1 In one embodiment, the body 101 may be made of copper, aluminum, nickel, copper-plated nickel, etc. For example, a copper foil of suitable size (e.g., a copper foil of 6 μm thick and 10 mm wide, and its length is any suitable length depending on the size of the required battery cell) may be used to make the tab body. It will be understood that the shape, size, etc. of the tab may be selected as needed. For example, the tab may generally be made of metal foil (such as a rectangular metal foil), which will not be described in detail here.

[0058] In another embodiment, the manufacturing method of the present application may further include using a material having a higher specific heat than the above-mentioned metal material to make a coating slurry. For example, the coating material may be made into a sol, a solvent may be added, any one or more of a film aid, a hardener, an anti-scratch agent, a wetting agent, a thickener, a surfactant, etc. may be added, and the slurry may be made by mixing evenly. It will be understood that the preparation of the coating slurry may be carried out in any suitable manner, which will not be described in detail herein.

[0059] In one embodiment, the material of the coating slurry may include a gas absorbing material. These gas absorbing materials can absorb the gas generated in the battery cell, and further increase the specific heat of the coating and reduce the pressure in the battery cell. In a preferred embodiment, the gas absorbing material may include oxides and / or hydroxides of alkali metals and / or alkaline earth metals, and / or activated carbon. For example, the gas absorbing material may include any one or more of NaOH, CaO, CaOH, Na2O, activated carbon, and the binder includes PVDF. In another embodiment of the present application, the material of the coating slurry may be selected depending on the composition of the gas generated inside the battery cell. For example, in the case where a large amount of CO is generated in the battery cell, the material of the coating slurry may preferably include activated carbon, which can increase the specific heat of the tab to prevent its temperature from rising too quickly, and absorb the CO in the battery cell to reduce the pressure inside the battery cell; in the case where a large amount of CO2 is generated in the battery cell, the material of the coating slurry may preferably include Na2O, which can increase the specific heat of the tab to prevent its temperature from rising too quickly, and react with CO2 to generate Na2CO3 (which further increases the specific heat of the tab) and reduce the pressure inside the battery cell. Thus, in another embodiment of the present application, the coating slurry may include various suitable materials mixed in any suitable proportion, such as a mixture of Na2O and activated carbon, a mixture of Na2O and CaO and activated carbon, and the like.

[0060] For example, the gas absorbing material accounts for 80%-90% of the total mass of the coating, and the adhesive accounts for 10%-20% of the total mass of the coating. In this embodiment, the obtained tab not only has a coating with sufficient adhesive force, but also can effectively reduce the temperature of the tab, and can more efficiently absorb the gas generated inside the battery cell, thereby more efficiently reducing the internal pressure of the battery cell, and thus further improving the safety performance of the battery cell.

[0061] For example, the gas absorbing material accounts for 80%-90% of the total mass of the coating, and the binder accounts for 10%-20% of the total mass of the coating (for example, the gas absorbing material and the binder may account for 85% and 15% of the mass of the coating, respectively, and so on). After obtaining the desired above-mentioned mixture, it can be made into a coating slurry (i.e., forming a solution) by using a suitable solvent (for example, various suitable organic solvents, such as NMP (N-methylpyrrolidone), acetone, etc.). It will be understood that the binder can be any suitable binder, such as a polymer binder (for example, PVDF).

[0062] Next, the manufacturing method of the present application may include coating the slurry on at least one surface of the tab body to form a coating. It will be appreciated that any suitable coating process may be used, such as blade coating, cast coating, extrusion coating, roller coating, spray coating, powder coating, and the like. Taking gravure coating in roller coating as an example, the gravure roller may be first immersed in the slurry; as the gravure roller rotates, the slurry on the roller surface is scraped off with a scraper, leaving only the slurry in the pits; and when the gravure roller is turned to a position in contact with the tab body, the slurry in the pits is transferred to the surface of the tab body under the action of the pressure roller.

[0063] In one embodiment of the present application, considering that a certain space generally remains between the bare cell and the outer shell when the bare cell is encased, the coating can be coated on both the front and back sides of the body. Thus, the front coating can absorb the gas in the residual space, while the back coating can absorb the gas in the bare cell. In this way, the coating on both sides can provide a better effect of reducing the temperature of the tabs and reducing the pressure inside and outside the cell, thereby further improving the safety performance of the cell.

[0064] According to another embodiment of the present application, in order to prevent the coating from being too thick, which may lead to a decrease in the conductivity of the tab and material waste, and to provide sufficient effect of reducing the tab temperature and the pressure in the battery cell, the thickness of the coating may be less than 1.5 μm. Preferably, the thickness of the coating may be between 0.5 and 1.3 μm. More preferably, the thickness of the coating 102 may be 1 μm.

[0065] In another embodiment of the present application, in order to prevent the coating from occupying too much area of ​​the tab and affecting welding, and also from adversely affecting the flow area (a reduction in the flow area will lead to excessive current and increased temperature), thereby avoiding safety risks, the coating may not completely cover the main body of the tab, such as from Figure 1 In this embodiment, the coating is applied to the edge of the main body near the membrane area and extends into the main body by a predetermined distance without completely covering the main body. Further according to this embodiment, the coating extends from the edge of the main body near the membrane area to the main body by a predetermined distance (i.e., the width of the coating) between 0.5-3 mm. Figure 1 As shown, the predetermined distance d can be between 0.5-3 mm. In a preferred embodiment, the predetermined distance d can be 2 mm. This will be described below in relation to Figure 2-3 shown and described in more detail.

[0066] Although as mentioned above, a specific range of the width and thickness of the coating is given in this application, this is only for illustrative purposes. The coating can have any suitable thickness and width without affecting the integration of the tab body and the battery cell and the coating can provide sufficient high specific heat performance.

[0067] Finally, the manufacturing method of the present application may include drying the coated tab body to obtain the tab. In one embodiment, the drying may be performed at 100° C. for 1 hour. Of course, any other suitable drying process, drying machine, drying temperature, drying time, etc. may be used. As just one example, in an embodiment in which a coating slurry having a mass ratio of Na2O to a binder of 9:1 is used, the coating may be applied on at least one surface of the tab by drying the solvent (e.g., NMP).

[0068] In this way, the present application can obtain a new type of pole ear, which can be assembled in a battery cell, thereby preventing the temperature of the battery cell from rising too high and / or too quickly during use, and can reduce the pressure inside the battery cell, while extending the life of the battery cell.

[0069] Battery Cell

[0070] For example, refer to Figure 2-3 , which shows a schematic diagram of an example battery cell according to an embodiment of the present application. Here, Figure 2 It is a schematic position diagram of the uncoated tab body 201, the coating 202, and the film area 203 before being rolled into a cylindrical battery cell; Figure 3 After the cylindrical battery is rolled, the tab 301 (such as Figure 1 Schematic diagram of the position of the tab 100) and the bare cell 303.

[0071] exist Figure 2 In FIG. 1 , different grayscales are used to show the uncoated tab body 201, the coating 202, and the film area 203. It can be seen that the coating 202 represents the portion of the tab body coated with the coating material, which is close to the film area 203 and does not completely cover the tab body.

[0072] Figure 3 FIG. 2 shows a schematic diagram of the position of the tab 201 relative to the bare cell 203 after the bare cell 203 is rolled. Of course, for the sake of simplicity, Figure 2 Only the tabs 201 and the bare cell 203 are shown. Those skilled in the art will appreciate that the cell may also include any other suitable components, such as positive and negative electrode covers, insulating glue, metal shells, various fasteners, etc., which will not be described in detail here.

[0073] Secondary battery

[0074] In one embodiment of the present application, a secondary battery is provided, which can be a lithium ion secondary battery, a potassium ion secondary battery, a sodium ion secondary battery, a lithium sulfur battery, etc., and is particularly preferably a lithium ion secondary battery. The secondary battery of the present application includes Figure 3 The battery cells shown.

[0075] The shape of the secondary battery of the present application can be cylindrical, square or any other shape. Figure 4 The secondary battery 5 is a square structure as an example. Figure 5 Shows Figure 4 The exploded view of the secondary battery 5 is shown in FIG. 5 . The outer package may include a shell 51 and a cover plate 53. The shell 51 may include a bottom plate and a side plate connected to the bottom plate. The bottom plate and the side plate enclose a receiving cavity. The shell 51 has an opening connected to the receiving cavity. The cover plate 53 can be covered on the opening to close the receiving cavity. The positive electrode sheet, the negative electrode sheet and the isolation film can be formed into an electrode assembly 52 through a winding process or a lamination process. The electrode assembly is encapsulated in the receiving cavity, and the electrolyte is infiltrated in the electrode assembly 52. ​​The number of electrode assemblies 52 contained in the secondary battery 5 can be one or more.

[0076] Electrical Devices

[0077] In one embodiment of the present application, the electrical device of the present application includes at least one of the secondary battery, battery module, or battery pack of the present application, and the secondary battery, battery module, or battery pack can be used as a power source of the electrical device, and can also be used as an energy storage unit of the electrical device. The electrical device includes but is not limited to mobile digital devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.

[0078] Figure 6 The device 600 is used as an example. The device 600 is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. In order to meet the requirements of the device for high power and high energy density, a battery pack or a battery module can be used.

[0079] As another example, the device may be a mobile phone, a tablet computer, a laptop computer, etc. The device is usually required to be thin and light, and the secondary battery of the present application (such as Figure 5 The secondary battery shown in the figure) is used as the power source.

[0080] Example

[0081] As an illustration, the present application verifies the beneficial effects of the electrode tab of the present application through the following set of tests (in the test, the electrode tab of the present application is used as a negative electrode tab, and its main body is made of copper).

[0082] Comparative example: a 6μm thick copper foil without any coating is used as a cylindrical negative electrode ear, which is flattened by a flattening device, put into a shell, welded to a current collector, glued, welded to a top cover, injected, formed, aged, etc., and assembled into a battery cell.

[0083] Example 1: A mixture of Na2O and PVDF with a mass ratio of 9:1 is used, and this mixture is added to NMP to form a solution (i.e., slurry); a 6μm thick copper foil is used and gravure coating is used to coat both sides of the copper foil with a 0.5μm thick Na2O coating, and dried as a cylindrical negative electrode tab (at this time, the Na2O coating includes Na2O and PVDF with a mass ratio of 9:1). The coating position is 2mm away from the lower edge of the tab (i.e., the edge close to the membrane area). After flattening with a flattening device, shelling, current collector welding, glue sticking, top cover welding, liquid injection, formation, aging, etc., it is assembled into a battery cell.

[0084] Embodiment 2: The thickness of the Na2O coating is 1 μm, and the rest is the same as that of Embodiment 1.

[0085] Embodiment 3: The thickness of the Na2O coating is 1.5 μm, and the rest is the same as that of Embodiment 1.

[0086] Example 4-6: The Na2O in the coating material is replaced with activated carbon, and the rest is the same as Example 1-3.

[0087] Example 7-9: The coating material is changed to Na2O, conductive carbon, and PVDF in a mass ratio of 8:1:1, and the rest is the same as Example 1-3.

[0088] Example 10-12: The coating material is changed to activated carbon, conductive carbon, and PVDF in a mass ratio of 8:1:1, and the rest is the same as Example 1-3.

[0089] Example 13: The coating material is changed to Na2O, activated carbon, conductive carbon, and PVDF in a mass ratio of 4:4:1:1, and the rest is the same as Example 1.

[0090] In the tests related to the comparative examples and Examples 1-13, the tab temperature, the internal pressure of the battery cell, and the capacity retention rate of the battery cell were measured. It can be understood that the measurement of these parameters can be easily made by those skilled in the art.

[0091] As an illustration, the lug temperature is tested here by implanting a temperature-sensitive wire into the battery cell and connecting the temperature-sensitive wire to an external temperature sensor. In the test, the applicant drilled a hole on the non-engraved area of ​​the battery cell top cover at a position that was not blocked by the adapter and the lug. The inner diameter of the hole may depend on the number of temperature-sensitive wires implanted in the battery cell; the burrs at the drilling site were polished, the top cover was cleaned, and particulate matter was removed to avoid short circuits in the battery cell; the perforated top cover and the battery cell were laser soft-connected and welded; and the prepared temperature-sensitive wire was implanted into the surface of the battery cell through the drilling. Subsequently, the lug temperature can be obtained through the implanted temperature-sensitive wire.

[0092] Also as an illustration, the internal pressure of the battery cell is measured here by leading the gas inside the battery cell to the pressure measuring device. In the test, first, by implanting a gas-producing nail (e.g., a plastic nail) into the battery cell, joining a pressure measuring tube filled with silicone oil to the gas-producing nail, and then assembling a pressure gauge filled with silicone oil to the pressure measuring tube, the gas pressure inside the battery cell can be measured by the sensor of the pressure gauge. It should be understood that any suitable pressure gauge can be used, such as a pressure gauge using a CKD PPX type pressure sensor. After the test device of the comparative example of the above embodiments is completed, the battery cell is charged to 4.25V at a room temperature of 25°C and an atmospheric pressure, and then discharged to 2.5V at 4C. In this charge and discharge process, the highest temperature and highest pressure measured are used as the measured lug temperature and the internal pressure of the battery cell during this charge and discharge process. The above charge and discharge process is repeated 1000 times, and the highest temperature and highest pressure measured are taken as the final lug temperature and the internal pressure of the battery cell. Those skilled in the art will understand that C refers to the cell capacity, and the charge and discharge rate = charge and discharge current / rated capacity, so 1 / 3C means that the current is one third of the rated current, 4C means that the current is four times the rated current, and so on.

[0093] In addition, the cell capacity is measured by discharging the cell after it is fully charged and recording the discharge time, and multiplying the discharge current by the time. In the test, the capacity retention rate is the percentage of the cell capacity measured after 1000 charge and discharge cycles of the cell to the capacity measured after the first charge and discharge cycle.

[0094] The measured results are shown in the following table:

[0095]

[0096]

[0097]

[0098] It can be seen from the above table that when the tab of the present application is used, the tab temperature, the internal pressure of the battery cell, and the capacity retention rate are all improved.

[0099] Therefore, the electrode tab of the present application can effectively reduce the temperature of the negative electrode tab, absorb the gas in the battery cell to reduce the internal pressure of the battery cell, and ultimately obtain an improved battery capacity retention rate, thereby extending the service life of the battery cell.

[0100] Those skilled in the art will appreciate that the operation sequence of the above steps is provided for illustrative purposes only, and the steps may be performed in various suitable sequences.

[0101] The previous description of the application is provided to enable any person skilled in the art to make or use the application. Various modifications to the application will be apparent to those skilled in the art, and the universal principles defined herein may be applied to other variations without departing from the spirit or scope of the application. Thus, the application is not intended to be limited to the examples and designs described herein, but should be granted the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A tab, comprising: A body made of metal material; as well as a coating applied to at least one surface of the body, the coating comprising a material having a higher specific heat than the body, The coating extends on the main body from an edge of the main body close to the membrane region toward the inside of the main body by a predetermined distance without completely covering the main body.

2. The tab according to claim 1, characterized in that: The coating includes a gas absorbing material and a binder.

3. The tab according to claim 2, characterized in that: The gas absorbing material accounts for 80% to 90% of the total mass of the coating, and the adhesive accounts for 10% to 20% of the total mass of the coating.

4. The electrode tab according to any one of claims 2 to 3, characterized in that: The gas absorption material includes any one or more of NaOH, CaO, CaOH, Na2O, and activated carbon, and the binder includes PVDF.

5. The electrode tab according to any one of claims 1 to 3, characterized in that: The thickness of the coating is below 1.5 μm.

6. The tab according to claim 5, characterized in that: The thickness of the coating is between 0.5 μm and 1.3 μm.

7. The electrode tab according to any one of claims 1 to 3, characterized in that: The predetermined distance is between 0.5 mm and 3 mm.

8. The electrode tab according to claim 7, characterized in that: The thickness of the coating is 1 μm, and / or the predetermined distance is 2 mm.

9. A method for manufacturing a tab, comprising: Use metal materials to make the tab body; Using a material having a higher specific heat than the metal material to prepare the coating slurry; Applying the slurry on at least one surface of the tab body to form a coating, wherein the coating extends a predetermined distance from an edge of the body close to the membrane region into the body without completely covering the body; and The coated tab body is dried.

10. The method according to claim 9, characterized in that The coating layer includes a gas absorbing material and a binder, wherein the gas absorbing material includes any one or more of NaOH, CaO, CaOH, Na2O, and activated carbon, and the binder includes PVDF.

11. The method according to claim 10, characterized in that The gas absorbing material accounts for 80% to 90% of the total mass of the coating, and the adhesive accounts for 10% to 20% of the total mass of the coating.

12. The method according to any one of claims 9 to 11, characterized in that: The thickness of the coating is between 0.5 μm and 1.5 μm, and / or the predetermined distance is between 0.5 mm and 3 mm.

13. The method according to claim 12, characterized in that The thickness of the coating is 1 μm, and / or the predetermined distance is 2 mm.

14. A battery cell comprising the tab according to any one of claims 1 to 8, wherein: The tabs are integrated into the cell by flattening and welding to the collector plates.

15. A secondary battery comprising the battery cell according to claim 14.

16. An electrical device using the secondary battery according to claim 15 as a power source.

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