A battery current collector and a battery

Abstract

The application relates to the technical field of batteries, in particular to a battery current collecting disc and a battery. The battery current collecting disc comprises copper, and the battery current collecting disc comprises an electric connection part used for realizing electric connection of a cell tab and an electrode terminal; a color parameter of a surface of the electric connection part used for connection with the cell tab and / or the electrode terminal comprises L1 and a1, L1 is a value of an L channel in a Lab color space, a1 is a value of an a channel in the Lab color space, wherein S=L1*a1, 900<=S<=2500. By controlling the product S of L1 and a1 of the surface of the electric connection part within a proper range, the reflection can be reduced, the quality and stability of welding can be improved, and the structural strength of the battery current collecting disc can be ensured.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of batteries, in particular to a battery current collecting disc and a battery. BACKGROUND

[0002] A battery, for example, a cylindrical battery, comprises a shell, an end cover, a battery cell and a current collecting disc, the end cover is fixedly connected with an open end of the shell to enclose a sealed cavity, the battery cell is located in the sealed cavity, and the current collecting disc is arranged at least one end of the battery cell, and the current collecting disc is used to connect the tab of the battery cell and the end cover or the shell. The connection between the current collecting disc and the tab is usually achieved by laser welding technology.

[0003] Among them, the preparation material of the current collecting disc is generally metal, for example, copper, because the reflectivity of copper is relatively high, part of the laser light source will be reflected during laser welding, resulting in the temperature and energy of the remaining light source not being concentrated, thereby affecting the welding effect. SUMMARY

[0004] The present application discloses a battery current collecting disc and a battery, which are used to solve the problem of poor welding effect caused by high reflectivity of the current collecting disc.

[0005] To achieve the above-mentioned purpose, the present application provides the following technical solutions:

[0006] In a first aspect, the present application provides a battery current collecting disc, which comprises copper, and the battery current collecting disc comprises an electrical connection part, which is used to realize the electrical connection between the tab of the battery cell and the electrode terminal; the color parameters of the surface of the electrical connection part for connecting with the tab of the battery cell and / or with the electrode terminal include L1 and a1, L1 is the value of the L channel in the Lab color space, and a1 is the value of the a channel in the Lab color space, wherein S=L1x a1, 900≤S≤2500.

[0007] The battery current collecting disc provided by the present application, wherein the larger L1 is, the higher the glossiness of the surface of the electrical connection part is, and the reflection is serious. In order to reduce L1, specific treatment can be performed, such as cleaning and passivating the surface of the electrical connection part or chemical etching, etc., to reduce the glossiness of the surface of the electrical connection part, thereby reducing reflection, but L1 cannot be too small, and specific treatment of the electrical connection part will cause the structural strength and mechanical properties of the battery current collecting disc to deteriorate, thereby increasing the risk of fracture of the battery current collecting disc during welding. In addition, the reflection degree of the surface of the electrical connection part can also be improved by adjusting the color of the battery current collecting disc, and by comprehensively controlling the product S of L1 and a1 within a suitable range, the reflection is reduced, the quality and stability of welding are improved, and the structural strength of the battery current collecting disc is ensured.

[0008] In a second aspect, the application provides a battery, which comprises a shell, an end cover, an electrode core, and the battery current collector of the first aspect. The shell and the end cover surround to form a cavity accommodating the electrode core and the battery current collector. The electrode core comprises an electrode core tab, and the shell comprises an electrode terminal. The electrical connection part is electrically connected with the electrode core tab and the electrode terminal, respectively.

[0009] In the battery provided by the application, when the battery current collector and the electrode core tab or the electrode terminal are welded, the color parameter L1 of the surface of the electrical connection part is reduced by a specific treatment, such as chemical corrosion of copper, so as to reduce the glossiness of the electrical connection part of the battery current collector and further reduce the reflection phenomenon. However, L1 cannot be too small, which will cause the structural strength and mechanical properties of the battery current collector to be poor. In addition, the color of the battery current collector can also be adjusted to improve the reflection degree of the surface of the electrical connection part. By comprehensively controlling the product S of L1 and a1 within a suitable range, the reflection is reduced, the welding quality and stability are improved, the structural strength of the battery current collector is ensured, and thus the welding quality and stability are improved, and the performance of the battery is further improved. BRIEF DESCRIPTION OF DRAWINGS

[0010] Figure 1 FIG. 1 is a structural schematic diagram of a battery current collector according to an embodiment of the application;

[0011] Figure 2 FIG. 2 is a structural schematic diagram of a battery current collector according to another embodiment of the application;

[0012] Figure 3 FIG. 3 is a side view of the battery current collector according to an embodiment of the application;

[0013] Figure 4 FIG. 4 is a side view of the battery current collector according to another embodiment of the application;

[0014] Figure 5 FIG. 5 is a structural schematic diagram of a battery current collector according to another embodiment of the application;

[0015] Figure 6 FIG. 6 is a structural schematic diagram of a battery according to an embodiment of the application;

[0016] Figure 7 FIG. 7 is a structural schematic diagram of a battery according to another embodiment of the application;

[0017] Figure 8 FIG. 8 is a structural schematic diagram of a switching piece according to an embodiment of the application.

[0018] FIG. 1 is a structural schematic diagram of a battery current collector according to an embodiment of the application;

[0019] 10 - battery; 11 - housing; 12 - end cap. DETAILED DESCRIPTION

[0020] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work are within the scope of protection of the present application.

[0021] In order to facilitate the understanding of the technical solutions in the present application, the application scenarios of the current collector plate will be described first.

[0022] The battery includes a battery cell, an end cap and a housing for packaging the battery cell, the end cap is fastened at the opening of the housing to form a receiving cavity for packaging the battery cell, the battery cell includes a tab, and the current collector plate is arranged at least at one end of the battery cell, and the current collector plate is used to connect the tab of the battery cell and the end cap or the housing. The connection between the current collector plate and the tab is usually achieved by laser welding technology. The material of the current collector plate is generally metal, such as copper, because the reflectivity of copper is relatively high, part of the laser light source will be reflected during the laser welding process, resulting in that the temperature and energy of the remaining light source are not concentrated, thereby affecting the welding effect.

[0023] Therefore, in the embodiments of the present application, a battery current collector plate is provided, Figure 1 FIG. 1 is a structural schematic diagram of a battery current collector plate according to an embodiment of the present application, Figure 2 FIG. 2 is a structural schematic diagram of a battery current collector plate according to another embodiment of the present application, Figure 3 FIG. 3 is a side view of a battery current collector plate according to an embodiment of the present application, Figure 4 FIG. 4 is a side view of a battery current collector plate according to another embodiment of the present application, with reference to Figures 1 to 4 The battery current collector plate includes copper, and the battery current collector plate includes an electrical connection part, which is used to realize the electrical connection between the tab of the battery cell and the electrode terminal. The color parameters of the surface of the electrical connection part for connecting with the tab of the battery cell and / or with the electrode terminal include L1 and a1, L1 is the numerical value of the L channel in the Lab color space, and a1 is the numerical value of the a channel in the Lab color space, wherein S = L1 x a1, 900 ≤ S ≤ 2500.

[0024] Lab is a device-independent color model, which is composed of three elements (or channels) of L (Luminosity) and a, b related to color. The value range of L is 0 to 100, and L = 50 is equivalent to 50% black. The value range of a is +127 to 128, and +127a is red, gradually changing to 128a, which is green. All colors are composed of the three values. The channels of the target Lab value are denoted as L1, a1, and b1.

[0025] It can be understood that when L1 is larger, the brightness and glossiness of the surface of the electrical connection part are higher, and the reflected laser energy increases, resulting in unstable laser beams, affecting the continuity and stability of the welding process. In order to reduce L1, specific treatments such as cleaning, passivation, or chemical etching of the surface of the electrical connection part can be used to reduce the glossiness of the surface of the electrical connection part, thereby reducing the reflection. However, excessive treatment may cause the structural strength and mechanical properties of the battery current collector to deteriorate, increasing the risk of fracture of the battery current collector during welding; in addition, the color of the battery current collector can also be controlled, for example, the a1 value of the surface of the electrical connection part is reduced, that is, the color of the surface of the electrical connection part is darkened, to improve the degree of reflection of the surface of the electrical connection part. By comprehensively controlling the product S of L1 and a1 within a suitable range, the reflection is reduced, the welding quality and stability are improved, and the structural strength of the battery current collector is ensured, reducing the impact on welding.

[0026] The electrode terminal is used to realize the electrical connection between the battery and the external circuit. Specifically, the electrode terminal can be a pole provided on the battery shell, or the battery shell can also be directly used as the electrode terminal. The electrode terminal includes a positive electrode terminal and a negative electrode terminal.

[0027] The electrode tab includes a positive electrode tab and a negative electrode tab. The positive electrode tab and the negative electrode tab can be located on the same side of the electrode core, or the positive electrode tab and the negative electrode tab can be located on the two sides of the electrode core. When the positive electrode tab and the negative electrode tab are located on the same side of the electrode core, the battery current collector is located on the side of the electrode core close to the electrode tab, and as shown in FIG. 1, the battery current collector includes a positive current collector, a negative current collector, and an insulating plate. The positive current collector is used for electrical connection between the positive electrode tab and the positive electrode terminal, and the negative current collector is used for electrical connection between the negative electrode tab and the negative electrode terminal. The insulating plate is arranged between the positive current collector and the negative current collector to insulate the positive current collector and the negative current collector. Figure 1

[0028] It can be understood that the shape and size of the battery current collector are set according to the type and size of the battery. For example, when the battery is a cylindrical battery, as shown in FIG. 2, the battery current collector is a ring-shaped current collector. Figure 1 ​As shown, the shape of the battery current collector can be circular, and the shapes of the positive current collector, the negative current collector and the insulating plate can be fan-shaped. The sizes of the three can be designed according to actual needs.

[0029] In an optional embodiment of the present embodiment, the material for preparing the battery current collector includes copper, which means that the material for preparing the battery current collector can be pure copper or a copper alloy.

[0030] In an optional embodiment of the present embodiment, 1100≤S≤2000. When S is in the above range, the battery current collector has better welding effect and structural strength.

[0031] In the formula, 60≤L1≤90. Exemplarily, L1 can be 60, 62, 64, 66, 70, 75, 80, 85, 90 or any other value between 60 and 90. When L1 is too large, the reflection is serious, and the welding effect is poor when the battery current collector and the tab or the electrode terminal of the battery cell are electrically connected. On the contrary, when L1 is too small, although the reflection phenomenon is alleviated, the structural strength of the battery current collector cannot be guaranteed.

[0032] In the formula, 12≤a1≤32. Exemplarily, a1 can be 12, 16, 18, 20, 22, 24, 26, 28, 32 or any other value between 14 and 32.

[0033] In an optional embodiment of the present embodiment, 70≤L1≤85 and 14≤a1≤25. When L1 and a1 satisfy the above conditions, the battery current collector has better welding effect and higher structural strength.

[0034] Figure 5 FIG. 1 is a structural schematic diagram of a battery current collector according to another embodiment of the present application. As shown in FIG. 1, the battery current collector includes a passivation region, and at least one surface of the passivation region is provided with a passivation layer. The passivation region is the electric connection part in the present application. In the present application, the ratio of the area of the passivation region to the area of the battery current collector is not limited, and can be set according to actual needs, as long as the area for welding is provided with the passivation layer. Figure 5 It should be noted that the preparation method of the passivation layer is not limited in the present application. Exemplarily, the passivation layer can be prepared by chemical etching or cleaning passivation. When the passivation layer is prepared by chemical etching, the following steps are included:

[0035] 1) The battery current collector is subjected to surface pretreatment to remove oil stains, oxides or other impurities on the surface of the battery current collector, so as to ensure the quality of the passivation layer.

[0036]

[0037] ​2) passivation treatment, soaking the passivation area in a passivation solution, or forming a passivation layer on at least one surface of the passivation area by electrochemical means. Among them, the commonly used passivation solution includes but is not limited to chromate, nitrate, phosphate.

[0038] 3) cleaning and drying, cleaning the battery current collector with clean water to remove the residual passivation solution on the surface of the battery current collector, and then drying the battery current collector to prevent moisture from remaining.

[0039] Among them, the adjustment mode of L1 and a1 in the present application is not limited, specifically, L1 can be adjusted by passivation time, and the value of a1 can be adjusted by passivation solution concentration.

[0040] It can be understood that the passivation area can have only one surface provided with a passivation layer, for example, the surface of the passivation area connected with the electrode tab is provided with a passivation layer, or the surface of the passivation area connected with the electrode terminal is provided with a passivation layer. Of course, the passivation area can also be provided with a passivation layer on both relatively arranged surfaces.

[0041] Among them, only one surface of the passivation area is provided with a passivation layer, which can improve the structural strength of the battery current collector, avoid corrosion of both surfaces of the battery current collector, and increase the risk of damage such as fracture of the battery current collector due to the low structural strength of the battery current collector.

[0042] In order to avoid that the surface of the passivation area is chemically corroded to cause the structural strength of the battery current collector to be too low, the ratio ρ of the thickness of the passivation layer to the thickness of the battery current collector ranges from 0.04 to 0.6. Among them, the thickness of the passivation layer is calculated by using a scanning electron microscope or a film thickness meter.

[0043] It can be understood that when ρ is too large, the passivation layer is too thick, that is, the corrosion intensity of the surface of the battery current collector is large, the structural strength of the battery current collector is weak, and the risk of fracture of the battery current collector increases, and moreover, the too thick passivation layer will affect the overcurrent of the battery current collector. On the contrary, when ρ is too small, the passivation layer is too thin, the corrosion degree of the surface of the battery current collector is low, the glossiness is high, and the reflection phenomenon is weakly improved.

[0044] Among them, the battery current collector can only include the passivation area, that is, the entire surface of the battery current collector is covered with the passivation layer, or the battery current collector can include the passivation area and the non-passivation area, that is, part of the surface of the battery current collector is covered with the passivation layer. Figure 5 As shown in the figure, the battery current collector also includes a non-passivation area connected with the passivation area, that is, part of the surface of the battery current collector is covered with an electrical connection part, avoiding chemical corrosion of the entire surface of the battery current collector, and only the surface of the area used for electrical connection with the electrode tab or the electrode terminal is chemically corroded, which can not only reduce the reflection phenomenon during laser welding, but also ensure that the battery current collector as a whole has high structural strength.

[0045] When the battery current collecting disc includes the non-passivation region, the ratio ρ of the thickness of the passivation layer to the thickness of the battery current collecting disc ranges from 0.057 to 0.6. The non-passivation region has a higher structural strength, thereby ensuring that the overall structural strength of the battery current collecting disc is higher, and thus the thickness of the passivation layer of the passivation region can be set to be thicker to improve the light reflection phenomenon of the electrical connection part.

[0046] In an optional embodiment of the present application, the area ratio r of the passivation region to the non-passivation region ranges from 0.1 to 0.9. When r is less than 0.1, the area of the electrical connection part is too small, the welding area is insufficient, and the overflow area is insufficient. Conversely, when r is greater than 0.9, the area of the electrical connection part is too large, the area of the region on the surface of the battery current collecting disc subjected to chemical corrosion is too large, and the structural strength of the battery current collecting disc is poor.

[0047] It can be understood that the shape of the passivation region is not limited in the present application, and the shape of the passivation region can be circular, square, or sector, etc., and is set according to actual needs.

[0048] When the thickness of the battery current collecting disc is less than or equal to 0.4 mm, 900≤S≤2000.

[0049] In an optional embodiment of the present application, the insulation resistance R of the electrical connection part ranges from 1.5 to 3.5 GΩ. For example, R can be 1.5, 1.8, 2.0, 2.2, 2.4, 2.6, 2.8, 3.0, 3.5, or any other value between 1.5 and 3.5. The insulation resistance R of the electrical connection part is measured by an internal resistance tester.

[0050] Based on the same technical concept, the present application also provides a battery, Figure 6 FIG. 1 is a structural schematic diagram of a battery according to an embodiment of the present application. Figure 6 The battery includes a shell, an end cover, a battery cell, and a battery current collecting disc according to various possible embodiments of the present application. The shell and the end cover form a cavity accommodating the battery cell and the battery current collecting disc. The battery cell includes a cell tab, and the end cover includes an electrode terminal. The electrical connection part is electrically connected to the cell tab and the electrode terminal, respectively.

[0051] Because the battery current collecting disc in the present application can reduce the light reflection phenomenon during laser welding, improve the quality and stability of welding, and the performance of the battery in the present application is also improved.

[0052] The battery cell includes a positive electrode sheet, a negative electrode sheet, and a separator. The separator is arranged between the positive electrode sheet and the negative electrode sheet. The positive electrode sheet, the negative electrode sheet, and the separator form the battery cell through winding or stacking. The positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer. The negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer. The positive electrode current collector is not particularly limited as long as it has electrical conductivity and does not cause adverse chemical changes in the battery. Specifically, the positive electrode current collector can be made of stainless steel, aluminum, nickel, titanium, baked carbon, or aluminum or stainless steel treated on the surface with at least one of carbon, nickel, titanium, silver, or the like. The negative electrode current collector is made of copper, stainless steel, nickel, titanium, or the like. In specific embodiments, the positive electrode current collector can be aluminum, and the negative electrode current collector can be copper. The positive electrode active material layer includes a positive electrode active material, and the positive electrode active material includes a nickel-cobalt-manganese ternary material, a lithium iron phosphate material, a lithium manganese iron phosphate material, or the like. The negative electrode active material layer includes a negative electrode active material, and the negative electrode active material includes artificial graphite, natural graphite, a silicon-based material, or the like. Therefore, the battery in the present application includes, but is not limited to, a lithium ion battery, a nickel-hydrogen battery, a nickel-cadmium battery, an alkaline dry battery, or the like.

[0053] The battery cell tab can be a separate conductive member that is electrically connected to the battery cell tab. The battery cell tab can also be cut from the positive electrode current collector or the negative electrode current collector.

[0054] In an optional aspect of the present application, the battery cell tab includes a positive electrode tab and a negative electrode tab. When the positive electrode tab and the negative electrode tab are located on the same side of the battery cell, 1000≤S≤2100, so that the battery current collector has better welding effect.

[0055] The battery can be a cylindrical battery or a quadrangular prism battery. For example, when the battery cell is a cylindrical battery cell, 1100≤S≤1800. The cylindrical battery includes two opposite end faces and a peripheral side face. The positive electrode tab and the negative electrode tab can be led out from one of the end faces. Since the diameter of the cylindrical battery is limited, the area where the positive electrode tab and the negative electrode tab can be arranged is limited. Therefore, the battery current collector of the cylindrical battery needs to have better welding effect to achieve overcurrent. In the present application, S is controlled within 1100-1800 to effectively reduce the reflection phenomenon during welding, thereby improving the welding effect.

[0056] Figure 7 FIG. 1 is a structural schematic diagram of a battery according to another embodiment of the present application, Figure 8 FIG. 2 is a structural schematic diagram of a switching piece according to an embodiment of the present application, referring to Figure 7 and Figure 8, when the battery is a quadrangular prism battery, the battery current collector plate can be a transition piece, and the transition piece is welded with the cell tab and the pole respectively. Among them, the cell tab can be arranged at the end along the height direction of the cell, or can be arranged at the end along the length direction of the cell. When the cell tab is arranged at the end along the length direction of the cell, the transition piece includes a first connecting piece and a second connecting piece connected with the first connecting piece, the first connecting piece and the second connecting piece form an included angle, the first connecting piece is welded with the cell tab, and the second connecting piece is welded with the pole.

[0057] The battery current collector plate and the battery in the application are specifically described below through examples and comparative examples.

[0058] Examples 1-11

[0059] The color parameter of the surface of the electrical connection part of the battery current collector plate of examples 1-11, which is welded with the cell tab, satisfies S = L1 x a1, 900 ≤ S ≤ 2500.

[0060] Comparative examples 1-2

[0061] The color parameter S = L1 x a1 of the surface of the electrical connection part of the battery current collector plate of comparative examples 1-2, which is welded with the cell tab, does not satisfy 900 ≤ S ≤ 2500.

[0062] The color parameters L1 and a1 of the surface of the electrical connection part of the battery current collector plate of examples 1-11 and comparative examples 1-2, which is welded with the cell tab, are measured and calculated by using a color difference meter;

[0063] The tensile strength of the electrical connection part of the battery current collector plate of examples 1-11 and comparative examples 1-2 is tested by using a tension testing machine.

[0064] The welding yield of the batteries of examples 1-11 and comparative examples 1-2 is tested, and the testing method of the welding yield includes the following steps:

[0065] 100 batteries are welded, and whether each battery is welded to fail is detected;

[0066] Welding yield = number of batteries without welding failure / 100;

[0067] Among them, welding failure refers to at least one of the following situations: the surface of the electrical connection part can be directly observed to have reflection under the laser mirror, or virtual welding occurs when the battery current collector plate and the cell tab or the electrode terminal are welded.

[0068] The welding yield of the batteries of examples 1-11 and comparative examples 1-2, the test data of the tensile strength of the electrical connection part, and the specific values of the color parameters are shown in the following table 1.

[0069] Table 1

[0070]

[0071] When the color parameters L1 of the surface of the electrical connection portion of the battery tab of Examples 1-4 satisfy the preferred range 70≤L1≤85, a1 satisfy the preferred range 14≤a1≤25, and S satisfy the preferred range 1100≤S≤2000, the battery tab welding yield is greater than or equal to 97.5%, and the tensile strength of the electrical connection portion is greater than or equal to 169.6N. Therefore, the reflection phenomenon of the electrical connection portion of the battery satisfying the above conditions is weakened, and the battery tab maintains a relatively high tensile strength, and has a higher structural stability.

[0072] When the color parameters L1 of the surface of the electrical connection portion of the battery tab of Examples 5-6 satisfy the range 60≤L1≤90, but do not satisfy the preferred range 70≤L1≤85, a1 satisfy the range 12≤a1≤32, but do not satisfy the preferred range 14≤a1≤25, and S satisfy the preferred range 1100≤S≤2000, the battery tab welding yield is greater than or equal to 95.3%, and the tensile strength of the electrical connection portion is greater than or equal to 165.7N. Compared with Examples 1-4, the welding yield and the tensile strength of the battery tab of Examples 5-6 slightly decrease.

[0073] When the color parameters L1 of the surface of the electrical connection portion of the battery tab of Examples 7-8 satisfy the preferred range 70≤L1≤85, a1 satisfy the preferred range 14≤a1≤25, and S satisfy the range 900≤S≤2500, but do not satisfy the preferred range 1100≤S≤2000, the battery tab welding yield is greater than or equal to 92.8%, and the tensile strength of the electrical connection portion is greater than or equal to 158.9N. Compared with Examples 1-4, the welding yield and the tensile strength of the battery tab of Examples 7-8 slightly decrease.

[0074] The color parameter L1 of the surface of the electrical connection of the battery tab of Example 9 satisfies the range 60≤L1≤90, does not satisfy the preferred range 70≤L1≤85, al satisfies the preferred range 14≤al≤25, S satisfies the range 900≤S≤2500, the welding yield of the battery tab of Example 9 is equal to 91.30%, and the tensile strength of the electrical connection is greater than or equal to 154.3 N. The color parameter L1 of the surface of the electrical connection of the battery tab of Example 10 satisfies the preferred range 70≤L1≤85, al does not satisfy the preferred range 14≤al≤25, S satisfies the preferred range 900≤S≤2500, the welding yield of the battery tab of Example 10 is equal to 90.40%, and the tensile strength of the electrical connection is greater than or equal to 168.5 N. The color parameter L1 of the surface of the electrical connection of the battery tab of Example 11 does not satisfy the preferred range 70≤L1≤85, al does not satisfy the preferred range 14≤al≤25, S satisfies the preferred range 900≤S≤2500, the welding yield of the battery tab of Example 11 is equal to 89.50%, and the tensile strength of the electrical connection is greater than or equal to 162.1 N. Compared to Examples 1-8, the welding yield and the tensile strength of the battery tab of Examples 9-11 slightly decrease.

[0075] The product S of the color parameters L1 and al of the surface of the electrical connection of the battery tab of Comparative Example 1 is 780, which does not satisfy 900≤S≤2500, and the welding yield and the tensile strength of the battery tab of Comparative Example 1 significantly decrease.

[0076] The product S of the color parameters L1 and al of the surface of the electrical connection of the battery tab of Comparative Example 2 is 2848, which does not satisfy 900≤S≤2500, and the welding yield and the tensile strength of the battery tab of Comparative Example 2 significantly decrease.

[0077] It is apparent that a person skilled in the art can make various modifications and variations to the embodiments of the present application without departing from the spirit and scope of the present application. Thus, it is intended that such modifications and variations included within the scope of the present application as defined by the following claims and their equivalents.

Claims

1. A battery current collector, characterized by, The battery current collector comprises copper, and the battery current collector comprises an electrical connection part for realizing electrical connection between a cell tab and an electrode terminal. A color parameter of a surface of the electrical connection part for connection with the cell tab and / or with the electrode terminal comprises L1 and a1, L1 is a value of an L channel in a Lab color space, and a1 is a value of an a channel in the Lab color space, wherein S=L1×a1, 1600≤S≤2000. The battery current collector comprises a passivation region, at least one surface of the passivation region is provided with a passivation layer, and the passivation region forms the electrical connection part. A ratio ρ of a thickness of the passivation layer to a thickness of the battery current collector ranges from 0.04 to 0.

6.

2. The battery current collector of claim 1, wherein, 1750≤S≤2000。 3. The battery current collector of claim 1, wherein, 60≤L1≤90, 12≤a1≤32.

4. The battery current collector of claim 3, wherein, 70≤L1≤85, 14≤a1≤25.

5. The battery current collector of claim 1, wherein, The battery current collector further comprises a non-passivation region connected with the passivation region.

6. The battery current collector of claim 1, wherein, The ratio ρ of the thickness of the passivation layer to the thickness of the battery current collector ranges from 0.057 to 0.

6.

7. The battery current collector of claim 1, wherein, When the thickness of the battery current collector is less than or equal to 0.4 mm, 1600≤S≤2000.

8. The battery current collector of claim 1, wherein, An insulation resistance R of the electrical connection part is 1.5-3.5 GΩ.

9. A battery, characterized by The battery comprises a shell, an end cover, a cell, and the battery current collector according to any one of claims 1-8, the shell and the end cover surround to form a cavity accommodating the battery current collector and the cell, the cell comprises a cell tab, the shell comprises an electrode terminal, and the electrical connection parts are respectively electrically connected with the cell tab and the electrode terminal.

10. The battery of claim 9, wherein, The cell tab comprises a positive electrode tab and a negative electrode tab, and when the positive electrode tab and the negative electrode tab are located on the same side of the cell, 1600≤S≤2000.

11. The battery of claim 10, wherein, When the cell is a cylindrical cell, 1600≤S≤1800.

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