Current collector, method for manufacturing the same, electrode tab, electrode assembly, and secondary battery

Abstract

This application relates to a current collector and its preparation method, an electrode, an electrode assembly, and a secondary battery. The current collector includes: a substrate layer; a conductive layer disposed on at least one surface of the substrate layer, the conductive layer including a plurality of conductive regions and a tab region sequentially arranged along a predetermined direction; wherein the resistance per unit length of all the conductive regions decreases along the predetermined direction, and the resistance per unit length of the conductive region adjacent to the tab region is greater than the resistance per unit length of the tab region. The current collector of this application can reduce the heat generated at the tab and the conductive regions, effectively lowering the temperature at the tab, improving the temperature uniformity of different areas of the secondary battery, improving the overall performance and service life of the secondary battery, and eliminating safety hazards.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to current collectors and their preparation methods, electrodes, electrode assemblies and secondary batteries. Background Technology

[0002] A current collector is a structure or component that collects electric current.

[0003] Currently, most rechargeable batteries use a portion of the current collector as a tab, which is directly connected to the terminal of the battery cell or connected through an adapter structure.

[0004] During the cyclic charging and discharging of a secondary battery, the current density is greater closer to the tab on the electrode plate, and the current density is greatest at the tab. This causes a large amount of Joule heat to be generated at the tab, resulting in a local temperature rise in the secondary battery, which affects the overall performance and service life of the secondary battery, and may even bring safety hazards. Summary of the Invention

[0005] Therefore, it is necessary to provide a current collector and its preparation method, an electrode, an electrode assembly, and a secondary battery, which can solve the overheating problem caused by excessive local current density in the current collector, improve the overall performance and service life of the secondary battery, and eliminate safety hazards.

[0006] In a first aspect, this application provides a current collector, the current collector comprising:

[0007] Matrix layer;

[0008] A conductive layer is disposed on at least one surface of the substrate layer, the conductive layer comprising a plurality of conductive regions and a tab region arranged sequentially along a preset direction;

[0009] Among them, the resistance per unit length of all the conductive regions decreases along a preset direction, and the resistance per unit length of the conductive region adjacent to the tab region is greater than the resistance per unit length of the tab region.

[0010] The current collector according to the first aspect of this application has at least the following beneficial effects:

[0011] The current collector of this application, by setting the conductive layer into multiple conductive regions and a tab region distributed in the same direction, and making the resistance per unit length of all the conductive regions decrease in the same direction, with the resistance per unit length of the conductive regions adjacent to the tab region being greater than or equal to the resistance per unit length of the tab region, forms a secondary battery with electrodes having this current collector. The tab is formed by processing the tab region. In this way, the resistance of the current collector is lower the closer it is to the tab, thus significantly reducing the heat generated at the tab during the cyclic charging and discharging of the secondary battery. Moreover, compared to a current collector with uniform resistance, the above-mentioned design of the resistance per unit length of the current collector decreasing towards the tab allows for a greater reduction in heat generation in the area closer to the tab, maximizing the reduction in heat generation at the tab. This effectively matches the overcurrent requirements of different areas of the current collector near the tab, thereby reducing the temperature difference between different areas of the secondary battery, improving the temperature uniformity of different areas of the secondary battery, enhancing the overall performance and service life of the secondary battery, and eliminating safety hazards.

[0012] In some embodiments, the cross-sectional area of ​​all the conductive regions increases along the preset direction, and the cross-sectional area of ​​the conductive region adjacent to the tab region is less than or equal to the cross-sectional area of ​​the tab region. This better matches the overcurrent requirements of different areas of the current collector near the tab, thereby reducing the temperature difference between different areas of the secondary battery and improving the temperature uniformity of different areas of the secondary battery.

[0013] In some embodiments, the thickness of all the conductive regions increases along the preset direction, and the thickness of the conductive regions adjacent to the tab region is less than or equal to the thickness of the tab region. Thus, the area resistance of the current collector closer to the tab region is lower, thereby reducing the heat generated at the tab and the conductive regions during the cyclic charging and discharging of the secondary battery, effectively lowering the temperature at the tab.

[0014] In some embodiments, the resistivity of all the conductive regions decreases along the preset direction, and the resistivity of the conductive regions adjacent to the tab region is greater than or equal to the resistivity of the tab region. Thus, by configuring the tab region and each conductive region to be made of different materials, the resistivity of each conductive region and the tab region can satisfy the aforementioned relationship. In a secondary battery formed with this current collector, the resistance of the current collector decreases as it approaches the tab. This significantly reduces the heat generated at the tab and the conductive regions during the cyclic charging and discharging of the secondary battery, effectively lowering the temperature at the tab and preventing excessively high temperatures at the tab from affecting the performance and lifespan of the secondary battery.

[0015] In some embodiments, in all the conductive regions, the resistance per unit length of at least one conductive region decreases along a predetermined direction. This makes the resistance variation along the predetermined direction more consistent across all conductive regions, better matching the overcurrent requirements of different areas on the current collector, and further improving the temperature uniformity of the secondary battery.

[0016] Secondly, this application provides a method for preparing a current collector, which includes the following steps: providing a substrate layer and a conductive layer; bonding the conductive layer to at least one surface of the substrate layer; processing the conductive layer to divide it into a plurality of conductive regions and tab regions arranged sequentially along a predetermined direction, such that the thickness of all the conductive regions increases along the predetermined direction, and the thickness of the conductive regions adjacent to the tab regions is less than or equal to the thickness of the tab regions, thereby obtaining a current collector.

[0017] In some embodiments, the step of processing the conductive layer includes: etching the conductive layer using a physical etching process.

[0018] In some embodiments, after processing the conductive layer, the method further includes the following step: passivating all the conductive regions and the tab regions.

[0019] Thirdly, this application also provides a method for preparing a current collector, which includes the following steps: providing a substrate layer; sequentially depositing a plurality of metal layers with different resistivities on at least one surface of the substrate layer along a predetermined direction to obtain a conductive layer, such that the conductive layer includes a plurality of conductive regions and tab regions arranged sequentially along the predetermined direction, and the resistivity of all the conductive regions decreases along the predetermined direction, and the resistivity of the conductive region adjacent to the tab region is greater than or equal to the resistivity of the tab region; obtaining a current collector.

[0020] Fourthly, this application provides an electrode 11, which includes: an active material layer, a tab, and a current collector as described in any of the above embodiments. The active material layer is disposed on the surface of the conductive layer away from the substrate layer, and the tab is formed from the tab region.

[0021] Fifthly, this application provides an electrode assembly, which includes a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode; wherein the positive electrode and / or the negative electrode is the electrode of the above solution.

[0022] Sixthly, this application provides a secondary battery that includes the electrode assembly described above.

[0023] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0024] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiments below. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0025] Figure 1 This is a schematic diagram of the structure of an electrode in the prior art;

[0026] Figure 2 This is a schematic diagram of the current collector structure according to an embodiment of this application;

[0027] Figure 3 This is a top view of the current collector according to an embodiment of this application;

[0028] Figure 4 for Figure 3 Schematic cross-sectional view of the current collector along the AA surface. Figure 1 ;

[0029] Figure 5 This is a schematic cross-sectional view of the current collector according to an embodiment of this application. Figure 2 ;

[0030] Figure 6 This is a schematic cross-sectional view of the current collector according to an embodiment of this application. Figure 3 ;

[0031] Figure 7 This is a schematic cross-sectional view of the current collector according to an embodiment of this application. Figure 4 ;

[0032] Figure 8 This is a schematic cross-sectional view of the current collector according to an embodiment of this application. Figure 5 ;

[0033] Figure 9 This is a schematic cross-sectional view of the current collector according to an embodiment of this application. Figure 6 ;

[0034] Figure 10 This is another top view of the current collector according to an embodiment of this application;

[0035] Figure 11 This is a schematic flowchart of the current collector preparation method according to an embodiment of this application;

[0036] Figure 12 This is another schematic flowchart illustrating the preparation method of the current collector according to an embodiment of this application;

[0037] Figure 13 This is a schematic diagram of the structure of a secondary battery according to an embodiment of this application.

[0038] Explanation of reference numerals in the attached drawings: Secondary battery 1; Electrode assembly 10; Electrode 11; Tab 11a; Housing 20; End cap 30; Current collector 100; Substrate layer 110; Conductive layer 120; Conductive region 121; First conductive region 121a; Second conductive region 121b; Third conductive region 121c; Fourth conductive region 121d; Tab region 122; Preset direction X; Length direction Y; Thickness direction Z. Detailed Implementation

[0039] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0040] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0041] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0042] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0043] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0044] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0045] In the description of the embodiments of this application, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0046] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0047] Currently, rechargeable batteries are not only used in energy storage systems for hydropower, thermal power, wind power, and solar power plants, but also widely used in electric vehicles such as electric bicycles, electric motorcycles, and electric cars, as well as in military equipment and aerospace. With the continuous expansion of battery applications, market demand is also constantly increasing.

[0048] A secondary battery typically includes an electrode assembly, a casing, and other functional components. The electrode assembly is the part of the secondary battery where the chemical reaction takes place; it is mainly formed by winding or stacking positive and negative electrode plates.

[0049] See Figure 1 This is illustrated as an electrode 11 of an electrode assembly, which can be either a positive or negative electrode. Figure 1In the diagram, the arrows within the box indicate current density. The applicant has discovered that in wound or stacked electrode assemblies, a portion of the current collector is typically used as the tab 11a, or the tab 11a is directly welded to the current collector. During the charging and discharging process of the secondary battery, the area of ​​the electrode 11 with the aforementioned current collector closer to the tab 11a has a higher current density, with the highest current density at the tab 11a. This results in a large amount of Joule heat being generated at the tab 11a, causing a localized temperature rise in the secondary battery, affecting its overall performance and lifespan, and even posing safety hazards.

[0050] Therefore, to address the issue of excessive local current density in the current collector of the electrode assembly causing localized overheating and affecting the overall performance and lifespan of the secondary battery, see [reference needed]. Figure 2 and Figure 3 After in-depth research, the applicant proposes a current collector 100, which includes a substrate layer 110 and a conductive layer 120.

[0051] The conductive layer 120 is disposed on at least one surface of the substrate layer 110. The conductive layer 120 includes a plurality of conductive regions 121 and tab regions 122 sequentially disposed along a predetermined direction X. Moreover, the resistance per unit length of all conductive regions 121 decreases along the predetermined direction X, and the resistance per unit length of the conductive region 121 adjacent to the tab region 122 is greater than or equal to the resistance per unit length of the tab region 122.

[0052] It should be noted that in the current collector 100 provided in the application embodiment, the preset direction X refers to the width direction of the conductive layer 120 or the current collector 100. The length direction of the conductive layer 120 and the substrate layer 110 is the length direction Y shown in the figure. The thickness direction of the conductive layer 120 and the substrate layer 110 is the thickness direction Z shown in the figure.

[0053] The substrate layer 110 is a supporting structure for the current collector 100, and its function is to provide support and load for the conductive layer 120.

[0054] When the current collector 100 of this embodiment is used to fabricate the electrode 11 of the electrode assembly, the materials of the substrate layer 110 and the conductive layer 120 can be selected according to the polarity of the electrode 11. During the fabrication of the electrode 11, active material is coated on the surface of all conductive areas 121 of the conductive layer 120, while no active material is coated on the tab area 122. At this time, the tab 11a can be processed by cutting the tab area 122 to form tabs 11a of square, trapezoidal, semi-circular, or other shapes. During the charging and discharging process of the secondary battery, the positive and negative active materials react with the electrolyte to output current through the tab 11a.

[0055] The current collector 100 in this embodiment of the application is referred to as... Figure 3Multiple conductive regions 121 refer to two or more conductive regions 121. That is, along a preset direction X, there are sequentially a first conductive region 121a, a second conductive region 121b, ..., an nth conductive region, where n≥2. The decreasing trend of the resistance per unit length of all conductive regions 121 along the preset direction X means that the resistance per unit length R1 of the first conductive region 121a, the resistance per unit length R2 of the second conductive region 121b, ..., the resistance per unit length Rn of the nth conductive region gradually decreases.

[0056] The width of the first conductive region 121a (i.e., the length along the preset direction X), the width of the second conductive region 121b, ..., the width of the nth conductive region can be equal or unequal.

[0057] For example, in one embodiment, the width of the first conductive region 121a, the width of the second conductive region 121b, ..., the width of the nth conductive region are all equal;

[0058] Alternatively, in one embodiment, the width of the first conductive region 121a, the width of the second conductive region 121b, ..., the width of the nth conductive region decreases.

[0059] Similarly, the conductive region 121 adjacent to the tab region 122 is the nth conductive region, and the resistance Rn per unit length of the nth conductive region is greater than or equal to the resistance R0 per unit length of the tab region 122. Likewise, the width of the nth conductive region can be equal to or different from the width of the tab region 122.

[0060] It should be understood that if a manufacturing error causes a sudden change in the resistance per unit length of a certain conductive region 121 in the middle of all conductive regions 121 (i.e., the resistance per unit length of that conductive region is greater than that of the adjacent conductive regions), it should also be understood as falling within the scope of this application.

[0061] The current collector 100 of this application is configured with a conductive layer 120 consisting of multiple conductive regions 121 and tab regions 122 distributed in the same direction. The resistance per unit length of all conductive regions 121 decreases in the same direction, and the resistance per unit length of conductive regions 121 adjacent to tab regions 122 is greater than or equal to the resistance per unit length of tab regions 122. A secondary battery is formed by electrodes with the current collector 100, and the tab 11a is formed by processing tab regions 122. In this way, the resistance of the area of ​​the current collector 100 closer to the tab 11a is smaller. During the cyclic charging and discharging of the secondary battery, the heat generated at the tab 11a is reduced to a large extent, and the heat generated at the conductive regions 121 is also reduced. This effectively lowers the temperature at the tab 11a and improves the problem of local overheating of the secondary battery caused by excessive local current density in the current collector 100.

[0062] Furthermore, during the cyclic charging and discharging of the secondary battery, the current generated by the reaction between the positive and negative active materials gradually converges towards the area near the tab 11a. The closer the area is to the tab 11a, the greater the current is formed. Compared to a current collector with uniform resistance, the design of the resistance per unit length of the current collector 100 decreasing towards the tab 11a allows for a greater reduction in heat generation towards the tab 11a, maximizing the reduction in heat generation at the tab 11a. This effectively matches the overcurrent requirements of different areas of the current collector 100 near the tab 11a, thereby reducing the temperature difference between different areas of the secondary battery, improving the temperature uniformity of different areas of the secondary battery, enhancing the overall performance and lifespan of the secondary battery, and eliminating safety hazards.

[0063] In some embodiments of this application, see Figure 4 The cross-sectional area of ​​all conductive regions 121 increases along the preset direction X, and the cross-sectional area of ​​conductive regions 121 adjacent to tab regions 122 is less than or equal to the cross-sectional area of ​​tab regions 122.

[0064] Similarly, all conductive regions 121, i.e., along the preset direction X, sequentially have a first conductive region 121a, a second conductive region 121b, ..., an nth conductive region, where n≥2, and their corresponding cross-sectional areas are S1, S2, ..., Sn, respectively. That is, the cross-sectional area of ​​all conductive regions 121 increases along the preset direction X when S1 < S2 < ... < Sn.

[0065] See Figure 5 Taking n=4 as an example, let the cross-sectional area of ​​the first conductive region 121a be S1, the cross-sectional area of ​​the second conductive region 121b be S2, the cross-sectional area of ​​the third conductive region 121c be S3, the cross-sectional area of ​​the fourth conductive region 121d be S4, and the cross-sectional area of ​​the tab region 122 be S0. Then S1<S2<S3<S4≤S0. In this way, during the cyclic charging and discharging of the secondary battery, the current density passing through the tab region 122 and all conductive regions 121 can be relatively reduced, thereby reducing the heat generated in the tab region 122 and all conductive regions 121, and realizing the control of the internal heat of the secondary battery.

[0066] Similarly, compared to a current collector with a uniform cross-sectional area, the current collector 100 with the above design can reduce the current density in the region closer to the tab 122, with the reduction in current density in the tab 122 reaching its maximum. Correspondingly, the heat generation in the region closer to the tab 11a is reduced more significantly, with the reduction in heat generation at the tab 11a reaching its maximum. This better matches the overcurrent requirements of different regions of the current collector 100 near the tab 11a, thereby reducing the temperature difference in different regions of the secondary battery and improving the temperature uniformity in different regions of the secondary battery.

[0067] It should be noted that, in this application, the materials used to manufacture all conductive regions 121 and tab regions 122 are preferably the same, in order to better improve the temperature uniformity of different areas of the secondary battery.

[0068] In this application, S1, S2, ..., Sn and S0 are preferably arranged in an arithmetic progression to better balance the overcurrent requirements of different regions of the current collector 100 near the tab 11a. Furthermore, the value of n can be as large as possible to minimize the difference in cross-sectional area between adjacent conductive regions, resulting in more consistent resistance changes across all conductive regions. This ensures a larger current output at the tab 11a, while also improving the temperature uniformity of different regions of the secondary battery, thereby enhancing the overall performance and lifespan of the secondary battery and eliminating safety hazards.

[0069] Of course, the difference between adjacent values ​​of S1, S2, ..., Sn and S0 can also be unequal, which can also improve the temperature uniformity of different regions of the secondary battery, but the effect is reduced compared to the method of equal difference.

[0070] Furthermore, it is understood that the method of setting the cross-sectional area of ​​all conductive regions 121 to increase along a preset direction X can be achieved by changing the length or thickness of the conductive regions 121. For example, by controlling the length of all conductive regions 121 to be equal, and only making the thickness of all conductive regions 121 increase along the preset direction X, the effect of the cross-sectional area of ​​all conductive regions 121 increasing along the preset direction X can be achieved. Of course, the thickness of all conductive regions 121 can also be controlled to be equal, and only making the thickness of all conductive regions 121 increase along the preset direction X, which can also achieve the effect of the cross-sectional area of ​​all conductive regions 121 increasing along the preset direction X. Similarly, the cross-sectional area of ​​the tab region 122 can also be designed by changing its length and thickness, which will not be elaborated here.

[0071] In some embodiments of this application, the thickness of all conductive regions 121 increases along a preset direction X, and the thickness of the conductive region 121 adjacent to the tab region 122 is less than or equal to the thickness of the tab region 122.

[0072] Similarly, all conductive regions 121, i.e., along the preset direction X, sequentially include a first conductive region 121a, a second conductive region 121b, ..., an nth conductive region 121c, where n ≥ 2, and their corresponding thicknesses are H1, H2, ..., Hn, respectively. That is, the thickness of all conductive regions 121 increases along the preset direction X when H1 < H2 < ... < Hn.

[0073] The thickness of the tab region 122 is H0. The thickness of the conductive region 121 adjacent to the tab region 122 is less than or equal to the thickness of the tab region 122, which means Hn≤H0.

[0074] See Figure 5 Taking n=3 as an example, the current collector 100 is stepped. The thickness of the first conductive region 121a is H1, the thickness of the second conductive region 121b is H2, the thickness of the third conductive region 121c is H3, and the thickness of the tab region 122 is H0. Then H1 < H2 < H3 < H0. At the same time, in this embodiment, the lengths of the first conductive region 121a, the second conductive region 121b, the third conductive region 121c, and the tab region 122 are controlled to be equal, and the materials of the first conductive region 121a, the second conductive region 121b, the third conductive region 121c, and the tab region 122 are controlled to be the same. At this time, the cross-sectional area of ​​the first conductive region 121a, the second conductive region 121b, the third conductive region 121c, and the tab region 122 can be increased sequentially, and the resistance of the first conductive region 121a, the second conductive region 121b, the third conductive region 121c, and the tab region 122 can be decreased sequentially.

[0075] Thus, the resistance of the current collector 100 is smaller as it gets closer to the tab region 122. This significantly reduces the heat generated at the tab 11a and the heat generated in the conductive region 121 during the cycle of charging and discharging of the secondary battery, effectively lowering the temperature at the tab 11a.

[0076] Furthermore, in the aforementioned current collector 100, since the thickness of all conductive regions 121 gradually increases along the predetermined direction X, and the thickness of the tab region 122 is the largest, when the current collector 100 is used to make the electrode 11, the thickness of the active material coated on the surface of all conductive regions 121 gradually decreases along the predetermined direction X. This reduces the current generated per unit length of active material coating. During the cyclic charging and discharging process of the secondary battery, the current generated by the reaction of the positive and negative active materials gradually converges towards the area closer to the tab 11a. On the one hand, this will gradually reduce the current increase in the area closer to the tab 11a. On the other hand, the resistance in the area closer to the tab 11a will also gradually decrease, thus the reduction in heat generation in the area closer to the tab 11a is greater. The reduction in heat generation in the tab 11a reaches its maximum, better matching the overcurrent requirements of different areas of the current collector 100 near the tab 11a, further reducing the temperature difference between different areas of the secondary battery, improving the temperature uniformity of different areas of the secondary battery, improving the overall performance and service life of the secondary battery, and eliminating safety hazards.

[0077] According to some embodiments of this application, see Figure 6 The thickness of all conductive regions 121 increases linearly along the preset direction X, that is, the line connecting all conductive regions 121 is an oblique line, and the tilt angle of the oblique line relative to the substrate layer 110 is greater than 0° and less than 90°.

[0078] At this point, the width of each conductive region 121 can be understood as a unit length, so that the cross-sectional area of ​​all conductive regions 121 increases linearly along the preset direction X. Compared to the case where all conductive regions 121 and the tab region 122 have equal thickness, the above arrangement can make the reduction in current density passing through all conductive regions 121 tend to be equal, ensuring that a larger current can be output at the tab 11a, while also better improving the temperature uniformity of different areas of the secondary battery.

[0079] In some embodiments of this application, the thickness of the entire conductive region 121 increases along a predetermined direction X, which may be further specified in the following embodiments:

[0080] In one embodiment, see Figure 7 The thickness of all conductive regions 121 increases along a preset direction X. Each conductive region 121 is a straight segment with approximately equal width. Adjacent conductive regions 121 are smoothly transitioned by rounded corners. The tab region 122 is also a straight segment. The tab region 122 and its adjacent conductive region 121 are also smoothly transitioned by rounded corners. The thickness of the tab region 122 is greater than the thickness of its adjacent conductive region 121.

[0081] In one embodiment, see Figure 8 All conductive areas 121 have a first conductive area 121a and a second conductive area 121b along a preset direction X. The first conductive area 121a is a straight section, the second conductive area 121b is an arc section, and the tab area 122 is a straight section. The first conductive area 121a and the second conductive area 121b are rounded, and the tab area 122 and the second conductive area 121b are rounded.

[0082] In one embodiment, see Figure 9 All conductive regions 121 sequentially include a first conductive region 121a, a second conductive region 121b, a third conductive region 121c, and a fourth conductive region 121d along a preset direction X. The first conductive region 121a, the second conductive region 121b, the third conductive region 121c, and the fourth conductive region 121d are all straight line segments inclined at the same angle relative to the substrate layer 110, and the tab region 122 is a flat segment. It can be understood that in this embodiment, the thickness of each conductive region increases along the preset direction X.

[0083] It is easy to understand that in the above embodiments, the thickness of all conductive regions 121 increases along the preset direction X, and the thickness of the conductive regions 121 adjacent to the tab region 122 is less than or equal to the thickness of the tab region 122. In this way, the current density passing through the tab region 122 and all conductive regions 121 can be relatively reduced, thereby reducing the heat generated in the tab region 122 and all conductive regions 121, and reducing the temperature difference in different areas of the secondary battery, thereby improving the temperature uniformity in different areas of the secondary battery.

[0084] According to some embodiments of this application, see Figure 10 The resistivity of all conductive regions 121 decreases along a preset direction X, and the resistivity of conductive regions 121 adjacent to tab regions 122 is greater than or equal to the resistivity of tab regions 122.

[0085] Similarly, all conductive regions 121, i.e., along a predetermined direction X, sequentially include a first conductive region 121a, a second conductive region 121b, ..., an nth conductive region 121c, where n ≥ 2. The resistivities of the first conductive region 121a, the second conductive region 121b, ..., the nth conductive region 121c are ρ1, ρ2, ..., ρn, respectively, and the resistivity of the tab region 122 is ρ0. Therefore, the resistivity of all conductive regions 121 decreasing along the predetermined direction X means ρn < ... < ρ2 < ρ1, and the resistivity of a conductive region 121 adjacent to the tab region 122 being greater than or equal to the resistivity of the tab region 122 means ρ0 ≤ ρn. Preferably, the thickness and width of all conductive regions 121 and the tab region 122 are set to be equal, thus better balancing the temperature of the tab region 122 and different conductive regions 121.

[0086] It is easy to understand that by configuring the tab region 122 and each conductive region 121 to be made of different materials, the resistivity of each conductive region 121 and the tab region 122 can satisfy the aforementioned relationship. The secondary battery formed by the electrode with the current collector 100 can make the resistance of the current collector 100 smaller as it gets closer to the tab 11a. In this way, the heat generated at the tab 11a and the heat generated in the conductive region 121 can be reduced to a large extent during the cyclic charging and discharging of the secondary battery, effectively reducing the temperature at the tab 11a and preventing the temperature at the tab 11a from being too high, which would affect the performance and service life of the secondary battery.

[0087] Furthermore, it is understood that when designing and processing the current collector 100, the method of controlling the different thicknesses of different conductive regions 121 and the method of controlling the different materials of different conductive regions 121 can be combined to process the conductive layer 120 accordingly, so as to obtain a current collector 100 that satisfies the following conditions: the resistance per unit length of all conductive regions 121 decreases along the preset direction X, and the resistance per unit length of the conductive region 121 adjacent to the tab region 122 is greater than or equal to that of the tab region 122 per unit length.

[0088] For example, the thickness gradient design of multiple conductive regions 121 near the tab region 122 along a preset direction X is adopted, so that the thickness of the conductive regions 121 in this part increases along the preset direction X, and the thickness of the conductive regions 121 adjacent to the tab region 122 is less than or equal to the thickness of the tab region 122. At the same time, the material of the multiple conductive regions 121 near the tab region 122 along the preset direction X is changed, so that each conductive region 121 in this part is made of different materials, so that the resistivity of the conductive regions 121 in this part decreases along the preset direction X. In this way, multiple processing and forming methods are provided, which can form current collectors 100 with different structures and shapes that meet the requirements, providing multiple options for the fabrication of the electrode 11.

[0089] According to some embodiments of this application, in all conductive regions 121, the resistance per unit length of at least one conductive region 121 decreases along a predetermined direction X.

[0090] In one embodiment, see Figure 9 The thickness of two adjacent conductive regions is not equal, the thickness of each conductive region increases along the preset direction X, and the width and length of each conductive region are equal, so that the resistance per unit length of each conductive region decreases along the preset direction X, and the thickness of two adjacent conductive regions is not equal.

[0091] In this way, the resistance of all conductive areas 121 can change more consistently along the preset direction X, better matching the overcurrent requirements of different areas on the current collector 100, and further improving the temperature uniformity of the secondary battery.

[0092] According to some embodiments of this application, a cooling layer is provided between the substrate layer 110 and the conductive layer 120, and the specific heat capacity of the cooling layer is greater than that of the conductive layer 120.

[0093] Specifically, in some embodiments, the cooling layer covers the surface of the substrate layer 110 near the conductive layer 120, and the conductive layer 120 covers the surface of the cooling layer away from the substrate layer 110, that is, the substrate layer 110, the cooling layer and the conductive layer 120 are stacked.

[0094] It is understandable that a cooling layer is provided between each conductive region 121 and the substrate layer 110, and between the tab region 122 and the substrate layer 110. By utilizing the large specific heat capacity of the cooling layer, some of the heat generated on each conductive region 121 and the tab region 122 can be absorbed by the cooling layer, effectively reducing the temperature at the tab of the secondary battery, eliminating safety hazards, and improving the service life of the secondary battery.

[0095] Of course, in other embodiments, during the charging and discharging process of the secondary battery, the positive and negative active materials react with the electrolyte to output current at the tab 11a, i.e., on the current collector 100. The closer the current collector is to the tab region 122, the greater the current density, resulting in more Joule heat being generated in the area of ​​the current collector 100 closer to the tab region 122, and thus a higher temperature in that area. Moreover, the temperature rise is more significant in the conductive area closer to the tab region 122 compared to the conductive area farther away from the tab region 122.

[0096] Based on this, a cooling layer can be disposed between the tab region 122 and the substrate layer 110, and the material of the cooling layer can be a material with a large specific heat capacity, such as glass fiber. In this way, by utilizing the large specific heat capacity of the cooling layer, some of the heat generated on the tab region 122 can be absorbed by the cooling layer, effectively reducing the temperature at the tab of the secondary battery. Furthermore, a corresponding cooling layer can also be disposed between the conductive region 121 near the tab region 122 and the substrate layer 110, thereby reducing the temperature of the area of ​​the current collector 100 near the tab region 122 to a certain extent. Combined with the aforementioned method of setting the resistance of the area of ​​the current collector 100 closer to the tab region 122 to be smaller, the temperature uniformity of different areas of the secondary battery can be further improved.

[0097] In addition, in other embodiments of this application, a thermally conductive layer is provided between the substrate layer 110 and the conductive layer 120, and the thermally conductive layer has excellent thermal conductivity, that is, the thermal conductivity of the thermally conductive layer is better than that of the substrate layer 110 and the conductive layer 120.

[0098] Specifically, the thermally conductive layer can be made of metals with excellent thermal conductivity, such as gold or silver. The thermally conductive layer can be disposed between the tab region 122 and the substrate layer 110. Utilizing the excellent thermal conductivity of the thermally conductive layer, it can promptly conduct some of the heat generated on the tab region 122 to other, lower-temperature areas of the current collector, reducing the heat locally accumulated in the tab region 122 within the secondary battery, lowering the temperature of the tab region 122, and further improving the temperature uniformity of different areas of the secondary battery.

[0099] Of course, a thermally conductive layer with good thermal conductivity can also be provided between the conductive region 121 near the tab region 122 and the substrate layer 110. Through the thermal conductivity of the thermally conductive layer, the heat accumulated in the area near the tab region 122 on the current collector 100 can be transferred to other areas on the current collector 100 in a timely manner. In this way, the temperature uniformity of different areas of the secondary battery can also be improved.

[0100] According to some embodiments of this application, see Figure 11 This application provides a method for preparing a current collector 100, comprising the following steps:

[0101] S10, providing a substrate layer 110 and a conductive layer 120;

[0102] S20. The conductive layer 120 is laminated onto at least one surface of the substrate layer 110;

[0103] S30. The conductive layer 120 is processed to divide the conductive layer 120 into multiple conductive regions 121 and tab regions 122 arranged sequentially along a preset direction X, and the thickness of all conductive regions 121 increases along the preset direction X. The thickness of the conductive region 121 adjacent to the tab region 122 is less than or equal to the thickness of the tab region 122, thereby obtaining the current collector 100.

[0104] It should be noted that the substrate layer 110 in step S10 refers to a film layer made of polymer material, and its thickness is not limited and can be selected according to actual needs.

[0105] The conductive layer 120 in step S10 refers to the metal foil layer commonly used in the current collector 100. The material of the conductive layer 120 can be, but is not limited to, metals such as silver, copper, gold, aluminum, zinc, and nickel, or composite materials such as silver-copper alloys, cadmium-copper alloys, chromium-copper alloys, zirconium-copper alloys, aluminum-magnesium alloys, aluminum-magnesium-silicon alloys, and aluminum-zirconium alloys. When the current collector 100 is a positive electrode current collector, the conductive layer 120 is preferably aluminum foil; when the current collector 100 is a negative electrode current collector, the conductive layer 120 is preferably copper foil.

[0106] In addition, it should be noted that the thickness of the conductive layer 120 in step S10 is not limited and can be selected according to actual needs. Its thickness ranges from 0 to 15 μm, and the length and width of the substrate layer 110 and the conductive layer 120 are approximately equal.

[0107] In S20, the composite process used to laminate the conductive layer 120 onto the surface of the substrate layer 110 is not limited, and a hot-pressing composite process known in the art can be used. Furthermore, depending on actual needs, the corresponding conductive layer 120 can be laminated onto both surfaces of the substrate layer 110 along the thickness direction Z. Alternatively, the corresponding conductive layer 120 can be laminated onto one of the two surfaces of the substrate layer 110, while the other surface is formed with the corresponding conductive layer 120 using a vacuum deposition or electroplating process.

[0108] In S30, the conductive layer 120 can be pre-divided into multiple conductive regions 121 and tab regions 122 arranged sequentially along a preset direction X, according to actual needs. The length of each conductive region 121 and tab region 122 is controlled to be equal, and the width of each conductive region 121 and tab region 122 can be controlled to be equal or unequal according to actual needs. Then, all conductive regions 121 are processed and thinned sequentially by region, so that the thickness of all conductive regions 121 increases along the preset direction X, and the thickness of the conductive region 121 adjacent to the tab region 122 is less than or equal to the thickness of the tab region 122, thereby obtaining the current collector 100.

[0109] In S30, the conductive layer 120 can also be directly thinned to obtain the current collector 100 that meets the requirements.

[0110] The above-mentioned method for preparing the current collector 100 involves dividing the conductive layer 120 into multiple conductive regions 121 and tab regions 122 arranged sequentially along a predetermined direction X, and increasing the thickness of all conductive regions 121 along the predetermined direction X. The thickness of the conductive regions 121 adjacent to the tab region 122 is less than or equal to the thickness of the tab region 122. This allows the current collector 100 to have a lower regional resistance closer to the tab region 122. As a result, the heat generated at the tab 11a and the conductive regions 121 are significantly reduced during the cyclic charging and discharging of the secondary battery. This effectively lowers the temperature at the tab 11a, better matches the overcurrent requirements of different regions of the current collector 100 near the tab 11a, further reduces the temperature difference between different regions of the secondary battery, improves the temperature uniformity of different regions of the secondary battery, enhances the overall performance and service life of the secondary battery, and eliminates safety hazards.

[0111] According to some embodiments of this application, the steps for processing the conductive layer 120 include:

[0112] S31. The conductive layer 120 is etched using a physical etching process.

[0113] In step S31, the physical etching process is preferably a laser etching process, that is, a laser etching machine is used to process and thin the conductive layer 120 according to a preset shape or partition.

[0114] It should be noted that, compared with chemical thinning processes such as chemical etching or electrochemical etching, the above-mentioned method for preparing the current collector 100 uses a physical etching process to thin the conductive layer 120, which is more efficient and can more precisely control the thickness of each conductive area 121. For example, using a laser etching machine to thin the conductive layer 120 does not require fixture positioning and shaping, and can etch the conductive layer 120 into a preset shape, reducing the complexity of the thinning process of the conductive layer 120 and also reducing environmental pollution.

[0115] According to some embodiments of this application, after processing the conductive layer 120, the following steps are also included:

[0116] S32. Passivate all conductive regions 121 and tab regions 122.

[0117] In step S32, after all the conductive areas 121 and the tab areas 122 are processed into a preset thickness or preset shape, a passivation device is used to passivate all the conductive areas 121 and the tab areas 122, so that a thin passivation film is formed on the surface of the conductive areas 121 and the tab areas 122 to isolate external air, water vapor and other corrosive media, avoid corrosion of the conductive areas 121 and the tab areas 122, and ensure the structural stability of the current collector 100.

[0118] According to some embodiments of this application, in S30, the obtained current collector 100 can be cut so that the width of the current collector 100 meets the actual requirements.

[0119] According to some embodiments of this application, see Figure 10 and Figure 12 This application also provides a method for preparing a current collector 100, comprising the following steps:

[0120] S40, providing a substrate layer 110;

[0121] S50. A plurality of metal layers with different resistivity are sequentially deposited on at least one surface of the substrate layer 110 along a preset direction X to obtain a conductive layer 120, such that the conductive layer 120 includes a plurality of conductive regions 121 and tab regions 122 arranged sequentially along the preset direction X, and the resistivity of all conductive regions 121 decreases along the preset direction X, and the resistivity of the conductive regions 121 adjacent to the tab regions 122 is greater than or equal to the resistivity of the tab regions 122.

[0122] S60, Obtain current collector 100.

[0123] It should be noted that the substrate layer 110 in step S40 refers to a film layer made of polymer material, and its thickness is not limited and can be selected according to actual needs.

[0124] In S50, multiple metal layers with different resistivities correspond one-to-one with multiple conductive regions 121 and tab regions 122. The materials of the metal layers can be, but are not limited to, metals such as silver, copper, gold, aluminum, zinc, and nickel, or composite materials such as silver-copper alloys, cadmium-copper alloys, chromium-copper alloys, zirconium-copper alloys, aluminum-magnesium alloys, aluminum-magnesium-silicon alloys, and aluminum-zirconium alloys. It should be understood that the different metal materials of each metal layer result in different resistivities for each conductive region 121 and tab region 122, and the resistivity of all conductive regions 121 decreases along a predetermined direction X. The resistivity of the conductive region 121 adjacent to the tab region 122 is greater than or equal to the resistivity of the tab region 122.

[0125] In addition, in some preferred embodiments, the length, width and thickness of all conductive regions 121 and tab regions 122 are equal, that is, all conductive regions 121 and tab regions 122 are cuboid in shape of the same size, so that the entire conductive layer 120 is a whole cuboid in shape.

[0126] In step S50, multiple metal layers with different resistivities are sequentially deposited on at least one surface of the substrate layer 110 along a predetermined direction X. This can be achieved by coating, magnetron sputtering, vacuum evaporation, or by directly hot-pressing the individual metal layers onto the surface of the substrate layer 110. Furthermore, depending on actual needs, multiple metal layers can be deposited on both surfaces of the substrate layer 110 along the thickness direction Z, so that both surfaces of the substrate layer 110 along the thickness direction Z have a conductive layer 120 that meets the requirements.

[0127] The current collector 100 prepared by the above method, through the deposition of metal layers with different resistivities on the surface of the substrate layer 110, i.e., by changing the material of different metal layers, results in a conductive layer 120 that includes multiple conductive regions 121 arranged sequentially along a predetermined direction X and a tab region 122. This ensures that the resistivity of all conductive regions 121 decreases along the predetermined direction X, and the resistivity of the conductive regions 121 adjacent to the tab region 122 is greater than or equal to the resistivity of the tab region 122. The secondary battery formed with the electrode of this current collector 100 allows the resistance of the current collector 100 to be lower closer to the tab 11a. This significantly reduces the heat generated at the tab 11a and the conductive regions 121 during the cyclic charging and discharging of the secondary battery, effectively lowering the temperature at the tab 11a and preventing excessively high temperatures at the tab 11a from affecting the performance and lifespan of the secondary battery.

[0128] In addition, in some embodiments, before depositing the corresponding metal layer on the surface of the substrate layer 110 in S50, the substrate layer 110 can be cleaned in advance. The two surfaces of the substrate layer 110 can be cleaned by using particle source cleaning to remove impurities such as oil on the surface of the substrate layer 110 and ensure the cleanliness of the surface of the substrate layer 110.

[0129] In S50, after a conductive layer 120 that meets the requirements is deposited on the surface of the substrate layer 110, a passivation device can be used to passivate all conductive areas 121 and tab areas 122, so that a thin passivation film is formed on the surface of conductive areas 121 and tab areas 122 to isolate external air, water vapor and other corrosive media, prevent conductive areas 121 and tab areas 122 from being corroded, and ensure the structural stability of current collector 100.

[0130] According to some embodiments of this application, this application provides an electrode 11. The electrode 11 includes: an active material layer, a tab 11a, and a current collector 100 as described in any of the above embodiments. The active material layer is disposed on the surface of the conductive layer 120 away from the substrate layer 110, and the tab 11a is formed by the tab region 122.

[0131] It is understood that the active material layer refers to the active material coated on the surface of all conductive areas 121. The material can be selected based on the polarity of the electrode 11. For example, when the electrode 11 is a positive electrode, the material of the active material layer can be, but is not limited to, lithium cobalt oxide, lithium manganese oxide, lithium nickel oxide, lithium iron phosphate, ternary materials, etc. When the electrode 11 is a negative electrode, the material of the active material layer can be, but is not limited to, graphite, silicon oxide, etc.

[0132] The tab region 122 is not coated with active material. The tab region 122 can be cut by die-cutting process to form the tab 11a.

[0133] Because of the current collector 100 with the above-mentioned scheme, the secondary battery formed by the electrode 11 has a lower resistance in the area of ​​the current collector 100 closer to the tab 11a. In this way, the heat generated at the tab 11a and the heat generated in the conductive area 121 can be reduced to a large extent during the cyclic charging and discharging of the secondary battery, effectively reducing the temperature at the tab 11a. Moreover, it can well match the overcurrent demand of different areas of the current collector 100 near the tab 11a, thereby reducing the temperature difference between different areas of the secondary battery, improving the temperature uniformity of different areas of the secondary battery, improving the overall performance and service life of the secondary battery, and eliminating safety hazards.

[0134] According to some embodiments of this application, see Figure 13 This application provides an electrode assembly 10, which includes a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode; wherein the positive electrode and / or the negative electrode is the electrode of the above solution.

[0135] It should be noted that the electrode assembly 10 of this application may be a wound structure or a stacked structure.

[0136] According to some embodiments of this application, see Figure 13 This application provides a secondary battery 1, which includes the electrode assembly 10 mentioned above. The secondary battery 1 refers to the smallest unit constituting a battery. For example... Figure 1 As shown, the secondary battery 1 also includes a casing 20, an end cap 30, and other functional components.

[0137] The secondary batteries disclosed in this application can be used, but are not limited to, in electrical devices such as vehicles, ships, or aircraft. A power system comprising such an electrical device can be constructed using the secondary batteries disclosed in this application.

[0138] In a battery system, there can be multiple secondary batteries, which can be connected in series, parallel, or a combination thereof. A combination connection means that multiple secondary batteries are connected in both series and parallel configurations. Multiple secondary batteries can be directly connected in series, parallel, or a combination thereof, and then the entire assembly is housed within a casing. Alternatively, the battery can consist of multiple secondary batteries first connected in series, parallel, or a combination thereof to form battery modules, which are then connected in series, parallel, or a combination thereof to form a single unit housed within a casing. The battery may also include other structures; for example, it may include a busbar component for electrical connection between the multiple secondary batteries. The secondary batteries can be cylindrical, flat, cuboid, or other shapes.

[0139] To make the objectives, technical solutions, and advantages of this application clearer and more concise, the following specific embodiments are used for illustration, but this application is by no means limited to these embodiments. The embodiments described below are merely preferred embodiments of this application and can be used to describe this application, but should not be construed as limiting the scope of this application. It should be noted that any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

[0140] To better illustrate this application, the following description, in conjunction with specific embodiments, further explains its content. The following are specific embodiments.

[0141] Comparative Example 1

[0142] 1. Preparation of positive electrode current collector

[0143] An 8µm thick PET film (substrate layer) is placed in the vacuum chamber of a crucible-type aluminizing machine, and the internal vacuum level is maintained at 6*10. -3 At Pa, aluminum in the crucible is melted, and an aluminum foil current collector is obtained by depositing 2µm aluminum layers (conductive layers) on both sides (thickness direction) of the PET film by vapor deposition. The aluminum layer (conductive layer) has a size of 4900mm*145mm*2µm.

[0144] 2. Preparation of negative electrode current collector

[0145] An 8µm thick PET film (substrate layer) was placed in the vacuum chamber of a magnetron sputtering coating machine, and the internal vacuum level was increased to 6*10. -3 At Pa, argon gas is introduced into the chamber to adjust the chamber vacuum to 1 Pa, and the magnetron sputtering power supply is turned on to start sputtering Cu. A copper foil current collector is obtained by depositing a 2µm thick copper layer (conductive layer) on both sides (thickness direction) of the PET film. The specifications of the copper layer (conductive layer) are 5200mm*151mm*2µm (length*width*thickness).

[0146] 3. Preparation of positive electrode sheet

[0147] The positive electrode active material (ternary nickel-cobalt-manganese alloy, NCM811), conductive agent (acetylene black), and binder (polyvinylidene fluoride, PVDF)) were mixed uniformly at a mass ratio of 97:2:1 and added to the solvent N-methylpyrrolidone (NMP) to prepare a positive electrode slurry. The positive electrode slurry was then uniformly coated onto one surface of the aforementioned aluminum foil current collector (excluding the tab area). After drying at 85°C, it was cold-pressed to complete the single-sided coating of the positive electrode sheet. The other side was then coated using the same method. After coating, the tab area of ​​the aluminum foil current collector was cut and shaped to form tabs, producing a lithium-ion battery positive electrode sheet (excluding the tab area) with dimensions of 4900mm*126mm*128µm (length*width*thickness).

[0148] 4. Negative electrode preparation

[0149] A negative electrode slurry is prepared by mixing graphite (the negative electrode active material), acetylene black (the conductive agent), sodium carboxymethyl cellulose (CMC) (the thickener), and styrene-butadiene rubber (SBR) (the binder) in a water solvent at a mass ratio of 96:2:1:1. The negative electrode slurry is then uniformly coated onto one surface of a copper foil current collector, dried at 85°C, and cold-pressed to complete the single-sided coating of the negative electrode sheet. The other side is then coated using the same method (excluding the tab area of ​​the copper foil current collector). After coating, the tab area of ​​the copper foil current collector is cut to form tabs, resulting in a lithium-ion battery negative electrode sheet with dimensions of 5200mm*130mm*125µm (length*width*thickness) (excluding the tab area).

[0150] 5. Diaphragm preparation

[0151] Using polyethylene microporous film as the porous separator film substrate, inorganic alumina powder, polyvinylpyrrolidone, and acetone solvent are mixed evenly in a weight ratio of 3:1.5:5.5 to form a slurry, which is then coated on one side of the substrate and dried to obtain the separator film.

[0152] 6. Electrolyte preparation

[0153] Lithium hexafluorophosphate was dissolved in a mixed solvent of ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate (the volume ratio of ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate was 1:2:1) to obtain a lithium-ion battery electrolyte.

[0154] 7. Preparation of secondary batteries

[0155] The above-mentioned positive electrode sheet, negative electrode sheet and separator are wound together to obtain a bare cell. Then, after processes such as encapsulation, liquid injection, formation and degassing, a lithium-ion battery is produced.

[0156] In the positive current collector of Comparative Example 1, the conductive layer 120 includes a first conductive region 121a, a second conductive region 121b, and a tab region 122 along a preset direction X. The resistance per unit length of the first conductive region 121a, the second conductive region 121b, and the tab region 122 are R1, R2, and R0, respectively, and R1=R2=R0, that is, R2 / R1=R0 / R2=1, which means that the resistance of the conductive layer 120 is uniform.

[0157] Example 1

[0158] It is basically the same as Comparative Example 1, except that:

[0159] The type of positive current collector in Example 1 is as follows: Figure 10 The aluminum foil current collector shown includes a conductive layer 120 in which a first conductive region 121a, a second conductive region 121b, and a tab region 122 along a predetermined direction X. The resistances per unit length of the first conductive region 121a, the second conductive region 121b, and the tab region 122 are R1, R2, and R0, respectively. In Example 1, R1 is equal to R1 in Comparative Example 1. In Example 1, R2 / R1 = 0.92, and R0 / R2 = 0.91, meaning the resistances per unit length of the first conductive region 121a, the second conductive region 121b, and the tab region 122 decrease along the predetermined direction X.

[0160] Comparative Example 2

[0161] It is basically the same as Comparative Example 1, except that:

[0162] In the positive current collector of Comparative Example 2, the conductive layer 120 includes a first conductive region 121a, a second conductive region 121b, a third conductive region 121c, and a tab region 122 along a preset direction X. The resistance per unit length of the first conductive region 121a, the second conductive region 121b, the third conductive region 121c, and the tab region 122 are R1, R2, R3, and R0, respectively. In Comparative Example 2, R1 is equal to R1 in Comparative Example 1. In Comparative Example 2, R1=R2=R3=R0, that is, R2 / R1=R3 / R2=R0 / R3=1, which means that the resistance of the conductive layer 120 is uniform.

[0163] Example 2

[0164] It is basically the same as Comparative Example 1, except that:

[0165] The type of positive current collector in Example 2 is as follows: Figure 3 The aluminum foil current collector is shown. In the conductive layer 120 of the positive electrode current collector, the conductive layer includes a first conductive region 121a, a second conductive region 121b, a third conductive region 121c, and a tab region 122 along a predetermined direction X. The resistance per unit length of the first conductive region 121a, the second conductive region 121b, the third conductive region 121c, and the tab region 122 are R1, R2, R3, and R0, respectively. In Example 2, R1 is equal to R1 in Comparative Example 1. In Example 2, R2 / R1 = 0.967, R3 / R2 = 0.966, and R0 / R3 = 0.964, meaning the resistance per unit length of the first conductive region 121a, the second conductive region 121b, the third conductive region 121c, and the tab region 122 decreases along the predetermined direction X.

[0166] Using the secondary battery 1 prepared in the above comparative examples and embodiments, during the preparation process, thermocouples for temperature monitoring were arranged at the cross-sectional positions of the first conductive region 121a, the second conductive region 121b, the third conductive region 121c, and the tab region 122 of the conductive layer of the positive electrode current collector. The temperature at the cross-sectional position of the tab region 122 corresponds to the temperature at the tab. After the secondary battery 1 was fabricated, it was charged and discharged using a current of 0.5C. Temperature changes at test points were continuously collected during the charging and discharging process, and the highest temperatures of the first conductive region 121a, the second conductive region 121b, the third conductive region 121c, and the tab were recorded. The highest temperatures corresponding to the first conductive region 121a, the second conductive region 121b, and the third conductive region 121c were calculated to be T1, T2, and T3, respectively, and the highest temperature at the tab was T0. Specific results are shown in Table 1 (temperature unit: °C).

[0167] Table 1

[0168] Group R2 / R1 R0 / R2 R3 / R2 R0 / R3 T1 T2 T3 T0 Comparative Example 1 1 1 / / 35.2 38.3 / 43.5 Example 1 0.92 0.91 / / 35.2 37.1 / 40.3 Comparative Example 2 1 1 1 1 35.2 37.2 39.6 43.5 Example 2 0.967 / 0.966 0.964 35.2 36.3 38.1 40.9

[0169] As can be seen from Table 1, compared with Comparative Example 1, Examples 1 and 2 show that by setting the conductive layer into multiple conductive regions 121 and tab regions 122 distributed along the width direction, and making the resistance per unit length of all conductive regions 121 decrease along the width direction, the heat at the tab can be effectively reduced, the temperature at the tab can be lowered, and the temperature of each conductive region 121 can also be lowered.

[0170] Meanwhile, comparing Examples 1 and 2 with Comparative Examples 1 and 2 respectively, it can be seen that the temperature difference between each conductive area and the tab in Examples 1 and 2 is smaller, which improves the temperature uniformity of different areas of the secondary battery.

[0171] Comparative Example 3

[0172] It is basically the same as Comparative Example 1, except that:

[0173] In the positive current collector of Comparative Example 3, the conductive layer 120 includes a first conductive region 121a, a second conductive region 121b, and a tab region 122 along a predetermined direction X. The cross-sectional areas of the first conductive region 121a, the second conductive region 121b, and the tab region 122 are S1, S2, and S0, respectively, and S1 = S2 = S0 = 9.8 mm. 2 At this point, the resistance of the conductive layer 120 remains uniform.

[0174] Example 3

[0175] It is basically the same as Comparative Example 1, except that:

[0176] The type of positive current collector in Example 3 is as follows: Figure 10 The aluminum foil current collector shown, i.e., the conductive layer 120 of the positive electrode current collector, includes a first conductive region 121a, a second conductive region 121b, and a tab region 122 along a predetermined direction X. The cross-sectional areas of the first conductive region 121a, the second conductive region 121b, and the tab region 122 are S1 = 9.8 mm². 2 S2=10.8mm 2 And S0=12.3mm 2 That is, the cross-sectional area of ​​the first conductive region 121a, the second conductive region 121b, and the tab region 122 increases along a preset direction X, so that the resistance per unit length of the first conductive region 121a, the second conductive region 121b, and the tab region 122 decreases along the preset direction X.

[0177] Comparative Example 4

[0178] It is basically the same as Comparative Example 1, except that:

[0179] In the positive current collector of Comparative Example 4, the conductive layer 120 includes a first conductive region 121a, a second conductive region 121b, a third conductive region 121c, and a tab region 122 along a predetermined direction X. The cross-sectional areas of the first conductive region 121a, the second conductive region 121b, the third conductive region 121c, and the tab region 122 are S1, S2, S3, and S0, respectively, where S1 = S2 = S3 = S0 = 9.8 mm. 2 At this point, the resistance of the conductive layer 120 remains uniform.

[0180] Example 4

[0181] It is basically the same as Comparative Example 1, except that:

[0182] The type of positive current collector in Example 4 is as follows: Figure 5 The aluminum foil current collector shown, i.e., the conductive layer 120 of the positive electrode current collector, includes a first conductive region 121a, a second conductive region 121b, a third conductive region 121c, and a tab region 122 along a predetermined direction X. The cross-sectional areas of the first conductive region 121a, the second conductive region 121b, the third conductive region 121c, and the tab region 122 are S1 = 9.8 mm². 2 S2=10.3mm 2 S3=11.3mm 2 And S0=12.7mm 2 That is, the cross-sectional areas of the first conductive region 121a, the second conductive region 121b, the third conductive region 121c, and the tab region 122 increase along a preset direction X, so that the resistance per unit length of the first conductive region 121a, the second conductive region 121b, the third conductive region 121c, and the tab region 122 decreases along the preset direction X.

[0183] Using the secondary battery 1 prepared in the above comparative examples and embodiments, during the preparation process, thermocouples for temperature monitoring were arranged at the cross-sectional positions of the first conductive region 121a, the second conductive region 121b, the third conductive region 121c, and the tab region 122 of the conductive layer of the positive electrode current collector. The temperature at the cross-sectional position of the tab region 122 corresponds to the temperature at the tab. After the secondary battery 1 was fabricated, it was charged and discharged using a current of 0.5C. Temperature changes at test points were continuously collected during the charging and discharging process, and the highest temperatures of the first conductive region 121a, the second conductive region 121b, the third conductive region 121c, and the tab were recorded. The highest temperatures corresponding to the first conductive region 121a, the second conductive region 121b, and the third conductive region 121c were calculated to be T1, T2, and T3, respectively, and the highest temperature at the tab was T0. Specific results are shown in Table 2 (cross-sectional area unit: mm). 2 Temperature unit: °C.

[0184] Table 2

[0185] Group S1 S2 S3 S0 T1(℃) T2(℃) T3(℃) T0(℃) Comparative Example 3 9.8 9.8 / 9.8 35.2 38.3 / 43.5 Example 3 9.8 10.8 / 12.3 35.2 37.4 / 40.4 Comparative Example 4 9.8 9.8 9.8 9.8 35.2 38.2 39.9 43.5 Example 4 9.8 10.3 11.3 12.7 35.2 37.7 38.7 39.8

[0186] As can be seen from Table 2, compared with Comparative Examples 3 and 4, Examples 3 and 4 show that by setting the conductive layer into multiple conductive regions 121 and tab regions 122 distributed along the width direction, and making the cross-sectional resistance of all conductive regions 121 increase along the width direction, and making the resistance per unit length of all conductive regions 121 decrease along the width direction, the heat at the tab can be effectively reduced, the temperature at the tab can be lowered, and the temperature of each conductive region 121 can also be lowered.

[0187] Meanwhile, comparing Examples 3 and 4 with Comparative Examples 3 and 4 respectively, it can be seen that the temperature difference between each conductive area and the tab in Examples 3 and 4 is smaller, which improves the temperature uniformity of different areas of the secondary battery.

[0188] Comparative Example 5

[0189] It is basically the same as Comparative Example 1, except that:

[0190] In the positive current collector of Comparative Example 5, the conductive layer 120 includes a first conductive region 121a, a second conductive region 121b, a third conductive region 121c, and a tab region 122 along a preset direction X. The first conductive region 121a, the second conductive region 121b, the third conductive region 121c, and the tab region 122 all have a length of 4900 mm, a width of 36.25 mm, and a thickness of 2 µm. At this time, the resistance of the conductive layer 120 is still uniform.

[0191] Example 5

[0192] It is basically the same as Comparative Example 1, except that:

[0193] The type of positive current collector in Example 5 is as follows: Figure 5 The aluminum foil current collector shown, specifically the conductive layer 120 of the positive electrode current collector, includes a first conductive region 121a, a second conductive region 121b, a third conductive region 121c, and a tab region 122 along a predetermined direction X. The lengths of the first conductive region 121a, second conductive region 121b, third conductive region 121c, and tab region 122 are all 4900 mm, the widths are all 36.25 mm, and the thicknesses are H1, H2, H3, and H0, respectively, where H1 = 2 µm, H2 = 2.1 µm, H3 = 2.3 µm, and H0 = 2.5 µm. The thicknesses of the first conductive region 121a, second conductive region 121b, third conductive region 121c, and tab region 122 increase along the predetermined direction X, causing the resistance per unit length of the first conductive region 121a, second conductive region 121b, third conductive region 121c, and tab region 122 to decrease along the predetermined direction X.

[0194] Comparative Example 6

[0195] It is basically the same as Comparative Example 1, except that:

[0196] In the positive current collector of Comparative Example 6, the conductive layer 120 includes a first conductive region 121a, a second conductive region 121b, a third conductive region 121c, a fourth conductive region 121d, and a tab region 122 along a preset direction X. The length of the first conductive region 121a, the second conductive region 121b, the third conductive region 121c, the fourth conductive region 121d, and the tab region 122 is 4900mm, the width is 29mm, and the thickness is 2µm. At this time, the resistance of the conductive layer 120 is still uniform.

[0197] Example 6

[0198] It is basically the same as Comparative Example 1, except that:

[0199] The type of positive current collector in Example 6 is as follows: Figure 4 The aluminum foil current collector shown is the conductive layer 120 of the positive electrode current collector. The conductive layer 120 includes a first conductive region 121a, a second conductive region 121b, a third conductive region 121c, a fourth conductive region 121d, and a tab region 122 along a preset direction X. The lengths of the first conductive region 121a, the second conductive region 121b, the third conductive region 121c, the fourth conductive region 121d, and the tab region 122 are all 4900mm, the widths are all 29mm, and the thicknesses are H1, H2, H3, H4, and H0, respectively, where H1=2µm, H2=2.1µm, H3=2.2µm, H4=2.3µm, and H0=2.5µm. At this time, the thickness of the first conductive region 121a, the second conductive region 121b, the third conductive region 121c, the fourth conductive region 121d, and the tab region 122 increases along the preset direction X, so that the resistance per unit length of the first conductive region 121a, the second conductive region 121b, the third conductive region 121c, the fourth conductive region 121d, and the tab region 122 decreases along the preset direction X.

[0200] Using the secondary battery 1 prepared in the above comparative examples and embodiments, during the preparation process, thermocouples for temperature monitoring were arranged at the cross-sectional positions of the first conductive region 121a, the second conductive region 121b, the third conductive region 121c, the fourth conductive region 121d, and the tab region 122 of the conductive layer of the positive electrode current collector. The temperature at the cross-sectional position of the tab region 122 corresponds to the temperature at the tab. After the secondary battery 1 was fabricated, it was charged and discharged using a current of 0.5C. Temperature changes at test points were continuously collected during the charging and discharging process, and the highest temperatures of the first conductive region 121a, the second conductive region 121b, the third conductive region 121c, the fourth conductive region 121d, and the tab were recorded. The highest temperatures corresponding to the first conductive region 121a, the second conductive region 121b, the third conductive region 121c, and the fourth conductive region 121d were T1, T2, T3, and T4, respectively, and the highest temperature at the tab was T0. Specific results are shown in Table 3 (thickness unit: µm; temperature unit: °C).

[0201] Table 3

[0202] Group H1 H2 H3 H4 H0 T1 T2 T3 T4 T0 Comparative Example 5 2µm 2µm 2µm / 2µm 35.2 38.2 39.9 / 43.5 Example 5 2µm 2.1µm 2.3µm / 2.5µm 35.2 37.3 38.9 / 41.0 Comparative Example 6 2µm 2µm 2µm 2µm 2µm 35.2 37.1 39.3 41.4 43.5 Example 6 2µm 2.1µm 2.2µm 2.3µm 2.5µm 35.2 36.5 37.9 38.6 40.3

[0203] As can be seen from Table 3, compared with Comparative Examples 5 and 6, Examples 5 and 6 show that by setting the conductive layer into multiple conductive regions 121 and tab regions 122 distributed along the width direction, and making the thickness resistance of all conductive regions 121 increase along the width direction, and making the resistance per unit length of all conductive regions 121 decrease along the width direction, the heat at the tab can be effectively reduced, the temperature at the tab can be lowered, and the temperature of each conductive region 121 can also be lowered.

[0204] Meanwhile, comparing Examples 5 and 6 with Comparative Examples 5 and 6 respectively, it can be seen that the temperature difference between each conductive area and the tab in Examples 5 and 6 is smaller, which improves the temperature uniformity of different areas of the secondary battery.

[0205] Comparative Example 7

[0206] It is basically the same as Comparative Example 1, except that:

[0207] In the positive current collector of Comparative Example 7, the conductive layer 120 includes a first conductive region 121a, a second conductive region 121b, and a tab region 122 along a preset direction X. The length, width, and thickness of the first conductive region 121a, the second conductive region 121b, and the tab region 122 are all equal, and they are all made of aluminum. Let the resistivity of the first conductive region 121a, the second conductive region 121b, and the tab region 122 be ρ1, ρ2, and ρ0, respectively, where ρ1=ρ2=ρ0, that is, ρ2 / ρ1=1, ρ0 / ρ2=1. At this time, the resistance of the conductive layer 120 is still uniform.

[0208] Example 7

[0209] It is basically the same as Comparative Example 1, except that:

[0210] The type of positive current collector in Example 7 is as follows: Figure 10 The current collector shown is the conductive layer 120 of the positive electrode current collector. The conductive layer 120 includes a first conductive region 121a, a second conductive region 121b, and a tab region 122 along a preset direction X. The length, width, and thickness of the first conductive region 121a, the second conductive region 121b, and the tab region 122 are all equal. The materials of the first conductive region 121a, the second conductive region 121b, and the tab region 122 are all different. The resistivity of the first conductive region 121a, the second conductive region 121b, and the tab region 122 are ρ1, ρ2, and ρ0, respectively. The ρ1 in Example 7 is equal to the ρ1 in Comparative Example 7, while ρ2 / ρ1 = 0.929 and ρ0 / ρ2 = 0.885. Thus, the resistance per unit length of the first conductive region 121a, the second conductive region 121b, and the tab region 122 still decreases along the preset direction X.

[0211] Comparative Example 8

[0212] It is basically the same as Comparative Example 1, except that:

[0213] In the positive current collector of Comparative Example 8, the conductive layer 120 includes a first conductive region 121a, a second conductive region 121b, a third conductive region 121c, and a tab region 122 along a preset direction X. The widths and thicknesses of the first conductive region 121a, the second conductive region 121b, the third conductive region 121c, and the tab region 122 are all equal, and they are all made of aluminum. Let the resistivity of the first conductive region 121a, the second conductive region 121b, the third conductive region 121c, and the tab region 122 be ρ1, ρ2, ρ3, and ρ0, respectively, where ρ1=ρ2=ρ3=ρ0, that is, ρ2 / ρ1=1, ρ3 / ρ2=1, and ρ0 / ρ3=1. At this time, the resistance of the conductive layer 120 is still uniform.

[0214] Example 8

[0215] The type of positive current collector in Example 8 is as follows: Figure 3The current collector shown is the conductive layer 120 of the positive electrode current collector. The conductive layer 120 includes a first conductive region 121a, a second conductive region 121b, a third conductive region 121c, and a tab region 122 along a preset direction X. The length, width, and thickness of the first conductive region 121a, the second conductive region 121b, the third conductive region 121c, and the tab region 122 are all equal. The materials of the first conductive region 121a, the second conductive region 121b, the third conductive region 121c, and the tab region 122 are all different. The resistivity of the first conductive region 121a, the second conductive region 121b, the third conductive region 121c, and the tab region 122 are ρ1, ρ2, ρ3, and ρ0, respectively. The ρ1 in Example 8 is equal to the ρ1 in Comparative Example 8, and ρ2 / ρ1 = 0.929, ρ3 / ρ2 = 0.923, and ρ0 / ρ3 = 0.875. Thus, the resistance per unit length of the first conductive region 121a, the second conductive region 121b, and the tab region 122 still decreases along the preset direction X.

[0216] Using the secondary battery 1 prepared in the above comparative examples and embodiments, during the preparation process, thermocouples for temperature monitoring were arranged at the cross-sectional positions of the first conductive region 121a, the second conductive region 121b, the third conductive region 121c, and the tab region 122 of the conductive layer of the positive electrode current collector. The temperature at the cross-sectional position of the tab region 122 corresponds to the temperature at the tab. After the secondary battery 1 was prepared, it was charged and discharged using a current of 0.5C. Temperature changes at test points were continuously collected during the charging and discharging process, and the highest temperatures of the first conductive region 121a, the second conductive region 121b, the third conductive region 121c, and the tab were recorded. The highest temperatures corresponding to the first conductive region 121a, the second conductive region 121b, and the third conductive region 121c were calculated to be T1, T2, and T3, respectively, and the highest temperature at the tab was T0. Specific results are shown in Table 4, where resistivity is in Ω·m and temperature is in °C.

[0217] Table 4

[0218] Group ρ2 / ρ1 ρ0 / ρ2 ρ3 / ρ2 T1 T2 T3 T0 Comparative Example 7 1 1 / 35.2 38.3 / 43.5 Example 7 0.929 0.885 / 35.2 37.6 / 40.8 Comparative Example 8 1 1 1 35.2 38.2 39.9 43.5 Example 8 0.929 0.923 0.875 35.2 37.4 38.5 40.1

[0219] As can be seen from Table 4, compared with Comparative Examples 7 and 8, Examples 7 and 8 show that by setting the conductive layer into multiple conductive regions 121 and tab regions 122 distributed along the width direction, and making the resistivity of all conductive regions 121 decrease along the width direction, the heat at the tab can be effectively reduced, the temperature at the tab can be lowered, and the temperature of each conductive region 121 can also be lowered.

[0220] Meanwhile, comparing Examples 7 and 8 with Comparative Examples 7 and 8 respectively, it can be seen that the temperature difference between each conductive area and the tab in Examples 7 and 8 is smaller, which improves the temperature uniformity of different areas of the secondary battery.

[0221] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and they should all be covered within the scope of the claims and specification of this application. In particular, as long as there is no structural conflict, the various technical features mentioned in the embodiments can be combined in any way. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A current collector (100), characterized in that, include: Matrix layer (110); A conductive layer (120) is disposed on at least one surface of the substrate layer (110), and the conductive layer (120) includes a plurality of conductive regions (121) and a tab region (122) arranged sequentially along a preset direction X. Among them, the resistance per unit length of all the conductive regions (121) decreases along the preset direction X, and the resistance per unit length of the conductive regions (121) adjacent to the tab region (122) is greater than or equal to the resistance per unit length of the tab region (122). The preset direction X refers to the width direction of the conductive layer (120) or the current collector (100).

2. The current collector (100) according to claim 1, characterized in that, The cross-sectional area of ​​all the conductive regions (121) increases along the preset direction X, and the cross-sectional area of ​​the conductive region (121) adjacent to the tab region (122) is less than or equal to the cross-sectional area of ​​the tab region (122).

3. The current collector (100) according to claim 1, characterized in that, The thickness of all the conductive regions (121) increases along the preset direction X, and the thickness of the conductive regions (121) adjacent to the tab region (122) is less than or equal to the thickness of the tab region (122).

4. The current collector (100) according to claim 1, characterized in that, The resistivity of all the conductive regions (121) decreases along the preset direction X, and the resistivity of the conductive regions (121) adjacent to the tab region (122) is greater than or equal to the resistivity of the tab region (122).

5. The current collector (100) according to any one of claims 1 to 4, characterized in that, In all the conductive regions (121), at least one conductive region (121) has a decreasing resistance per unit length along a predetermined direction X.

6. A method for preparing a current collector, used to prepare the current collector (100) according to any one of claims 1 to 5, characterized in that, Includes the following steps: A substrate layer (110) and a conductive layer (120) are provided. The conductive layer (120) is laminated to at least one surface of the substrate layer (110); The conductive layer (120) is processed to divide the conductive layer (120) into a plurality of conductive regions (121) and tab regions (122) arranged sequentially along a preset direction X, and the thickness of all the conductive regions (121) increases along the preset direction X, and the thickness of the conductive region (121) adjacent to the tab region (122) is less than or equal to the thickness of the tab region (122), thereby obtaining a current collector (100).

7. The method for preparing a current collector according to claim 6, characterized in that, The steps of processing the conductive layer (120) include: etching the conductive layer (120) using a physical etching process.

8. The method for preparing a current collector according to claim 7, characterized in that, After processing the conductive layer (120), the following steps are also included: All of the conductive regions (121) and the tab region (122) are passivated.

9. A method for preparing a current collector, used to prepare the current collector (100) according to any one of claims 1 to 5, characterized in that, Includes the following steps: Provide a matrix layer (110); Multiple metal layers with different resistivity are sequentially deposited along a predetermined direction X on at least one surface of the substrate layer (110) to obtain a conductive layer (120), such that the conductive layer (120) includes multiple conductive regions (121) and tab regions (122) arranged sequentially along the predetermined direction X, and the resistivity of all the conductive regions (121) decreases along the predetermined direction X, and the resistivity of the conductive region (121) adjacent to the tab region (122) is greater than or equal to the resistivity of the tab region (122); Obtain the current collector (100).

10. An electrode (11), characterized in that, include: The current collector (100) as described in any one of claims 1 to 5; An active material layer is disposed on the surface of the conductive layer (120) away from the substrate layer (110); The electrode (11a) is formed from the electrode region (122).

11. An electrode assembly (10), characterized in that, It includes a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode; Wherein, the positive electrode and / or the negative electrode are the electrodes as described in claim 10.

12. A secondary battery (1), characterized in that, Includes the electrode assembly (10) as described in claim 11.

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