Cover plate and battery

Abstract

The utility model relates to the technical field of batteries, and discloses a cover plate and a battery. The cover plate comprises a cover plate body provided with a pole hole, the cover plate body comprises a first metal layer and a second metal layer which are stacked, the hardness of the first metal layer is larger than that of the second metal layer, and the heat conductivity coefficient of the second metal layer is larger than that of the first metal layer; at least part of the pole is arranged in the pole hole; the annular piece and the pole are arranged in an insulated mode, the annular piece comprises a limiting part, a welding part and a transition part, the limiting part is used for limiting the pole, the welding part is connected with the second metal layer in a welded mode, the transition part is connected with the limiting part and the welding part, and the annular piece and the second metal layer are made of the same material; the ratio of the thickness T1 of the first metal layer to the thickness T2 of the second metal layer is 0.1-12.5. The cover plate body is made of two different metals, so that the overall strength of the cover plate is relatively high, the condition of pole connection failure caused by welding of the pole and the shell is avoided, and the performance of the battery is ensured.

Description

TECHNICAL FIELD

[0001] The utility model relates to battery technology field, concretely relates to cover plate and battery. BACKGROUND

[0002] A battery is a device that converts chemical energy into electrical energy, and it is composed of one or more cells, each cell including a positive electrode, a negative electrode, and an electrolyte. When the battery is connected to a circuit, a chemical reaction occurs within the cell, causing electrons to flow from the negative electrode to the positive electrode, thereby generating an electric current.

[0003] Currently, batteries can be divided into two categories: primary batteries and secondary batteries, also known as rechargeable batteries, which can recover their charge after discharging through charging. Common types of secondary batteries include lead-acid batteries, nickel-cadmium batteries, nickel-hydrogen batteries, and lithium-ion batteries, with lithium-ion batteries widely used in smartphones, laptops, and electric vehicles due to their high energy density and lightweight.

[0004] A lithium-ion battery typically includes a housing, a cover plate, and a pole. The cover plate is usually made of aluminum, which has relatively low strength. When the pole is connected to the housing through welding, the overall strength of the cover plate is weak, which can easily lead to connection failure of the pole, thereby reducing the current transmission efficiency of the battery and possibly causing unstable battery operation, affecting the performance of the battery. SUMMARY

[0005] Therefore, the utility model provides a cover plate and a battery to solve the problem of connection failure of the pole caused by the aluminum cover plate.

[0006] In a first aspect, the utility model provides a cover plate, which includes: a cover plate body provided with a pole hole, the cover plate body including a first metal layer and a second metal layer, the first metal layer and the second metal layer being stacked in the thickness direction of the cover plate, the hardness of the first metal layer being greater than that of the second metal layer, and the thermal conductivity of the second metal layer being greater than that of the first metal layer; a pole at least partially disposed in the pole hole; a ring-shaped part insulated from the pole, the ring-shaped part including a limiting portion, a welding portion, and a transition portion, the limiting portion being used to limit the pole, the welding portion being welded to the second metal layer, and the transition portion being used to connect the limiting portion and the welding portion, and the material of the ring-shaped part being the same as that of the second metal layer; wherein the ratio of the thickness T1 of the first metal layer to the thickness T2 of the second metal layer is 0.1-12.5.

[0007] In a second aspect, the utility model also provides a battery, which includes: the above-mentioned cover plate; a housing having an opening for mounting the cover plate; and a cell disposed in the housing.

[0008] Beneficial effects: the cover plate body adopts two different metals, the overall strength of the cover plate is higher, thereby avoiding the situation that the pole post connection fails when the pole post is welded with the shell, thereby ensuring the performance of the battery. The material of the annular piece is the same as that of the second metal layer, and the melting point is the same, which facilitates the welding of the annular piece on the second metal layer. At the same time, the thermal conductivity coefficient of the second metal layer is greater than that of the first metal layer. In the process of using the battery, the heat generated by the pole post is transmitted to the second metal layer through the annular piece, so that the heat of the pole post is quickly transmitted to the cover plate, thereby heat-dissipating the pole post. It can prevent the pole post from overheating, thereby avoiding the problems of performance decline, thermal runaway and shortening of service life caused by too high temperature.

[0009] The ratio of the thickness T1 of the first metal layer to the thickness T2 of the second metal layer is in the range of 0.1-12.5, which not only ensures the heat dissipation effect and avoids the thermal runaway of the battery, but also ensures the structural strength of the cover plate and the effective connection between the annular piece and the cover plate body, thereby improving the reliability and stability of the battery. BRIEF DESCRIPTION OF DRAWINGS

[0010] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the drawings needed in the following specific embodiments or prior art description will be briefly introduced. Obviously, the drawings in the following description are some embodiments of the present application, and those skilled in the art can also obtain other drawings according to these drawings without creative labor.

[0011] Figure 1 It is a perspective view of a battery according to an embodiment of the present application.

[0012] Figure 2 It is a perspective view of a battery according to an embodiment of the present application. Figure 1 It is a top view of the battery shown in the figure.

[0013] Figure 3 It is a top view of the battery shown in the figure. Figure 2 It is an A-A sectional view of the battery shown in the figure.

[0014] Figure 4 It is an A-A sectional view of the battery shown in the figure. Figure 3 It is a structure schematic view of the right side of the pole post shown in the figure.

[0015] Figure 5 It is a structure schematic view of the left side of the pole post shown in the figure. Figure 3 It is a structure schematic view of the left side of the pole post shown in the figure.

[0016] Figure 6 It is a partial sectional view of the cover plate of another battery according to an embodiment of the present application.

[0017] BRIEF DESCRIPTION OF DRAWINGS

[0018] 1, cover plate body; 101, first metal layer; 1011, sunken part; 102, second metal layer; 1021, convex step; 103, ring-shaped piece; 1031, limiting part; 1032, welding part; 1033, transition part;

[0019] 2, pole; 201, convex ring;

[0020] 3, upper insulating piece; 301, peripheral part;

[0021] 4, shell. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical scheme and advantages of the embodiments of the utility model clearer, the technical scheme in the embodiments of the utility model will be described clearly and completely in combination with the drawings in the embodiments of the utility model. Obviously, the described embodiments are part of the embodiments of the utility model, rather than all the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by those skilled in the art without creative labor belong to the protection scope of the utility model.

[0023] The embodiments of the utility model will be described below in combination with Figures 1 to 6 The embodiments of the utility model.

[0024] According to the embodiments of the utility model, on the one hand, a cover plate is provided, which comprises a cover plate body 1, a pole 2 and a ring-shaped piece 103. The cover plate body 1 is provided with a pole hole. The cover plate body 1 comprises a first metal layer 101 and a second metal layer 102. The first metal layer 101 and the second metal layer 102 are stacked in the thickness direction of the cover plate. The hardness of the first metal layer 101 is greater than that of the second metal layer 102. The thermal conductivity of the second metal layer 102 is greater than that of the first metal layer 101. The pole 2 is at least partially arranged in the pole hole. The ring-shaped piece 103 is insulated from the pole 2. The ring-shaped piece 103 comprises a limiting part 1031, a welding part 1032 and a transition part 1033. The limiting part 1031 is used for limiting the pole 2. The welding part 1032 is welded to the second metal layer 102. The transition part 1033 is used for connecting the limiting part 1031 and the welding part 1032. The material of the ring-shaped piece 103 is the same as that of the second metal layer 102. The ratio of the thickness T1 of the first metal layer 101 to the thickness T2 of the second metal layer 102 is 0.1-12.5.

[0025] The cover plate body 1 is made of two different metals, the overall strength of the cover plate is higher, thereby avoiding the situation that the connection of the pole 2 is invalid when the pole 2 is welded with the shell 4, thereby ensuring the performance of the battery. The material of the annular part 103 is the same as that of the second metal layer 102, and the melting point is the same, which facilitates the welding of the annular part 103 on the second metal layer 102. At the same time, the thermal conductivity of the second metal layer 102 is greater than that of the first metal layer 101. During the use of the battery, the heat generated by the pole 2 is transmitted to the second metal layer 102 through the annular part 103, so that the heat of the pole 2 is quickly transmitted to the cover plate, thereby heat dissipation of the pole 2, which can prevent the pole 2 from overheating, thereby avoiding the problems of performance decline, thermal runaway and shortening of service life caused by high temperature.

[0026] Further, the thickness T1 of the first metal layer 101 is also Figure 4 the vertical dimension of the first metal layer 101, and the thickness T2 of the second metal layer 102 is also Figure 4 the vertical dimension of the second metal layer 102. If the ratio of the thickness T1 of the first metal layer 101 to the thickness T2 of the second metal layer 102 is too small, the strength of the cover plate body 1 is low, which is easy to cause the welding connection between the annular part 103 and the cover plate body 1 to be invalid, resulting in damage to the pole assembly; if the ratio of the thickness T1 of the first metal layer 101 to the thickness T2 of the second metal layer 102 is too large, it is not conducive to the heat dissipation of the pole and the cover plate, which is easy to cause the heat accumulation of the pole, thereby causing the thermal runaway of the battery, affecting the charge rate of the battery.

[0027] Therefore, the ratio of the thickness T1 of the first metal layer 101 to the thickness T2 of the second metal layer 102 is in the range of 0.1-12.5, which not only ensures the heat dissipation effect and avoids the thermal runaway of the battery, but also ensures the structural strength of the cover plate and the effective connection between the annular part 103 and the cover plate body 1, thereby improving the reliability and stability of the battery.

[0028] It should be noted that the pole assembly includes the pole 2 and the annular part 103.

[0029] In one embodiment, as shown in Figure 4 and Figure 5 The first metal layer 101 is arranged above the second metal layer 102. The first metal layer has a large hardness and is arranged above the second metal layer 102, so that the structural strength of the cover plate body 1 is large, which can better resist external impact and pressure, and reduce the risk of damage to internal parts of the battery caused by collision or falling.

[0030] Furthermore, the ratio of the thickness T1 of the first metal layer 101 to the thickness T2 of the second metal layer 102 is 0.1-12. Since the thermal conductivity of the first metal layer 101 is low, the first metal layer 101 on top is not conducive to the heat dissipation of the electrode post 2, which can easily cause heat accumulation in the electrode post 2, leading to thermal runaway of the battery and affecting the charging rate of the battery.

[0031] Therefore, when T1 / T2 is in the range of 0.1-12, on the one hand, it is beneficial to the heat dissipation of the terminal post 2 and the cover plate, thereby increasing the charging rate of the battery; on the other hand, it ensures the structural strength of the cover plate body 1, thereby improving the overall performance, safety and service life of the battery.

[0032] Preferably, T1 / T2 is 0.1, 0.5, 0.8, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12.

[0033] It is understood that in another embodiment, such as Figure 6 As shown, the first metal layer 101 is disposed below the second metal layer 102. The second metal layer 102 has a higher thermal conductivity. Distributing the second metal layer 102 above the first metal layer 101 facilitates heat dissipation for the electrode post 2 and the cover plate, thereby improving the battery's charging rate. Furthermore, the ratio of the thickness T1 of the first metal layer 101 to the thickness T2 of the second metal layer 102 is 0.15-12.5. The second metal layer 102 has lower hardness, resulting in lower structural strength of the cover plate body 1, which cannot effectively resist external impacts and pressures, increasing the risk of damage to internal battery components due to collisions or drops. Therefore, a T1 / T2 ratio within the range of 0.15-12.5 ensures the structural strength of the cover plate body 1, better resisting external impacts and pressures, reducing the risk of damage to internal battery components due to collisions or drops, and improving the overall performance, safety, and lifespan of the battery.

[0034] In one embodiment, on the side near the annular member 103, the second metal layer 102 protrudes from the first metal layer 101 and is provided with a protruding step 1021. The welding portion 1032 is welded to the upper surface of the protruding step 1021. The welding area between the welding portion 1032 and the protruding step 1021 is relatively large, which can significantly enhance the welding strength between the welding portion 1032 and the second metal layer 102, improve the connection reliability, facilitate welding, and reduce welding difficulty.

[0035] Furthermore, along the length of the cover plate, the length L1 of the protruding step 1021 is 0.4mm-8mm. The length L1 of the protruding step 1021 is also... Figure 5The lateral dimension of the protruding step 1021. If the length L1 of the protruding step 1021 is too small, the welding area between the welding part 1032 and the second metal layer 102 will be small, affecting the welding strength and thus failing to ensure the heat dissipation of the pole post 2; if the length L1 of the protruding step 1021 is too large, the pole post 2 and the cover plate will easily overlap, which will easily cause insulation failure.

[0036] Therefore, the length L1 of the protruding step 1021 is in the range of 0.4mm-8mm. On the one hand, it ensures that the welding area between the welding part 1032 and the first metal layer 101 is of appropriate size, thereby ensuring the welding strength and facilitating the heat dissipation of the pole post 2. On the other hand, it avoids the overlap between the pole post 2 and the cover plate, ensuring the insulation effect between the cover plate and the pole post 2.

[0037] Preferably, L1 is 0.4mm, 0.6mm, 0.8mm, 1mm, 1.2mm, 2mm, 2.4mm, 3mm, 4mm, 5mm, 6mm, 7mm or 8mm.

[0038] In one embodiment, along the thickness direction of the cover plate, the upper surface of the weld portion 1032 is lower than the upper surface of the first metal layer 101. After the weld portion 1032 is welded to the cover plate body 1, weld lines and weld slag are formed, preventing the weld lines and weld slag from protruding from the upper surface of the cover plate and ensuring that there is no interference during battery pack assembly.

[0039] Furthermore, along the thickness direction of the cover plate, the height difference T5 between the upper surface of the welded portion 1032 and the upper surface of the first metal layer 101 is 0.2mm-2.5mm. If the height difference T5 is too small, it cannot be guaranteed that the weld line and weld slag will not protrude from the upper surface of the cover plate, which may easily cause interference with other components during battery pack assembly; if the height difference T5 is too large, the thickness of the recessed portion 1011 will be too thin, affecting the structural strength of the cover plate body 1.

[0040] Therefore, a height difference T5 within the range of 0.2mm-2.5mm not only ensures that the welding lines and slag do not protrude from the upper surface of the cover plate, and that the battery packaging does not interfere with other components, but also ensures that the thickness of the recessed part 1011 is appropriate, thus guaranteeing the structural strength of the cover plate body 1 and improving the overall performance, safety and service life of the battery.

[0041] Preferably, T5 is 0.2mm, 0.4mm, 0.6mm, 0.8mm, 1mm, 1.2mm, 1.4mm, 1.6mm, 1.8mm, 2mm or 2.5mm.

[0042] In one embodiment, the portion of the first metal layer 101 near the welding portion 1032 has a recessed portion 1011. The recessed portion 1011 can reduce the thickness of part of the first metal layer 101, thereby achieving rapid heat dissipation of the electrode post 2 and thus avoiding thermal runaway of the battery.

[0043] In one embodiment, T1 is 0.2mm-2.5mm, and T2 is 0.2mm-2mm. If the thickness of T1 is too large or the thickness of T2 is too small, it will hinder heat dissipation between the terminal and the cover plate, easily causing heat accumulation in the terminal and leading to thermal runaway of the battery, thus affecting the battery's charging rate. If the thickness of T1 is too small or the thickness of T2 is too large, the strength of the cover plate body 1 will be low, easily causing the welding connection between the annular part 103 and the cover plate body 1 to fail, resulting in damage to the terminal assembly.

[0044] Therefore, a T1 range of 0.2mm-2.5mm and a T2 range of 0.2mm-2mm not only ensure heat dissipation and prevent battery thermal runaway, but also guarantee the structural strength of the cover plate and ensure the effective connection between the annular part 103 and the cover plate body 1, thereby improving the reliability and stability of the battery.

[0045] Preferably, T1 is 0.2mm, 0.3mm, 0.4mm, 0.8mm, 1mm, 1.2mm, 1.6mm, 1.8mm, 2mm or 2.5mm, and T2 is 0.2mm, 0.3mm, 0.4mm, 0.8mm, 1mm, 1.2mm, 1.6mm, 1.8mm or 2mm.

[0046] In one embodiment, the thickness T3 of the annular member 103 is 0.2mm-2mm. A larger thickness T3 increases weight, cost, and space requirements. A smaller thickness T3 may not provide sufficient mechanical support, especially under significant impact or vibration, potentially leading to loosening or damage to the connection.

[0047] Therefore, the thickness T3 of the annular part 103 is in the range of 0.2mm-2mm. On the one hand, it can provide sufficient mechanical support to ensure a more solid connection between the pole post 2 and the cover plate body 1. On the other hand, it will not significantly increase the weight or occupy too much space, thus ensuring space utilization.

[0048] Preferably, T3 is 0.2mm, 0.3mm, 0.4mm, 0.8mm, 1mm, 1.2mm, 1.6mm, 1.8mm or 2mm.

[0049] In one embodiment, the first metal layer 101 is made of steel, and the second metal layer 102 is made of aluminum. Steel has good structural strength, and aluminum has good heat dissipation performance, thereby ensuring the structural strength and heat dissipation performance of the cover plate body 1.

[0050] Furthermore, T1 is 0.2mm-2mm and T2 is 0.2mm-1.6mm. That is, when T1 and T2 are within a suitable range, the material properties of the first metal layer 101 and the second metal layer 102 are better, thereby improving the structural strength and heat dissipation performance of the cover plate body 1.

[0051] In one embodiment, such as Figure 4 and Figure 5 As shown, the lower end of the pole post 2 has an outwardly protruding ring 201 on its outer peripheral wall, and a portion of the limiting part 1031 extends above the ring 201. The distance L2 between the outer peripheral surface of the ring 201 and the inner peripheral surface of the limiting part 1031 is 0.1mm-5mm.

[0052] Furthermore, when the outer diameter of the convex ring 201 is a fixed value, if L2 is small, the limiting ability of the limiting part 1031 is limited and it cannot effectively press the pole post 2; if L2 is large, the limiting part 1031 is close to the pole post 2, and it is easy for the limiting part to penetrate the upper insulating part 3 and contact the pole post 2 and conduct electricity, which poses a great safety risk.

[0053] Therefore, the distance L2 between the outer peripheral surface of the convex ring 201 and the inner peripheral surface of the limiting part 1031 is in the range of 0.1mm-5mm, which not only ensures the limiting ability of the limiting part 1031, but also ensures that the limiting part 1031 and the pole post 2 have a certain distance, thereby improving the safety of the battery.

[0054] Preferably, L2 is 0.1mm, 0.2mm, 0.8mm, 1mm, 1.2mm, 1.6mm, 1.8mm, 2mm, 2.2mm, 2.4mm, 3mm, 3.6mm, 4mm or 5mm.

[0055] In one embodiment, such as Figure 4 and Figure 5 As shown, the ratio of the thickness T3 of the annular component 103 to the thickness T2 of the second metal layer 102 is 0.1-10.

[0056] Furthermore, if the ratio of the thickness T3 of the annular member 103 to the thickness T2 of the second metal layer 102 is small, the strength of the weld between the annular member 103 and the second metal layer 102 is low, and the weld between the annular member 103 and the second metal layer 102 is easily damaged by vibration or impact. The limiting ability of the limiting part 1031 of the annular member 103 with a smaller thickness is limited, and it cannot effectively press the pole post 2. If the ratio of the thickness T3 of the annular member 103 to the thickness T2 of the second metal layer 102 is large, the strength of the weld between the annular member 103 and the second metal layer 102 is also low, and the weld between the annular member 103 and the second metal layer 102 is easily damaged by vibration or impact. The limiting ability of the annular member 103 is easily affected by the structural strength of the weld between the annular member 103 and the second metal layer 102.

[0057] Therefore, the ratio of the thickness T3 of the annular component 103 to the thickness T2 of the second metal layer 102 is in the range of 0.1-10. This not only ensures the structural strength of the welded joint between the annular component 103 and the second metal layer 102, but also ensures effective pressing of the electrode post 2, thereby improving the overall reliability of the battery.

[0058] Preferably, T3 / T2 is 0.1, 0.2, 0.6, 0.8, 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10.

[0059] Furthermore, the annular component 103 and the second metal layer 102 are formed separately. By separately forming the annular component 103 and the second metal layer 102 and then welding them together, the processing difficulty is reduced, thereby saving costs.

[0060] In one embodiment, such as Figure 4 and Figure 5 Figure 4 Figure 5 As shown, the cover plate also includes an upper insulating member 3, which is disposed between the pole post 2 and the annular member 103. The thickness T4 of the portion of the upper insulating member 3 located between the limiting part 1031 and the convex ring 201 is 0.2mm-2mm. The upper insulating member 3 is made of insulating material, which can isolate the pole post 2 and the cover plate body 1, prevent short circuits between the pole post 2 and the cover plate body 1, and ensure electrical isolation between the pole post 2 and the cover plate body 1.

[0061] Furthermore, if the thickness T4 of the portion of the upper insulating member 3 located between the limiting part 1031 and the convex ring 201 is small, the pole post 2 and the limiting part 1031 are prone to short circuit due to vibration or impact, posing a greater safety risk. If the thickness T4 of the portion of the upper insulating member 3 located between the limiting part 1031 and the convex ring 201 is large, the height of the limiting part 1031 and the overall thickness of the upper insulating member 3 will be increased, occupying a large amount of vertical space, which will affect the space utilization rate inside the battery pack.

[0062] Therefore, the thickness T4 of the portion of the upper insulating member 3 located between the limiting part 1031 and the convex ring 201 is between 0.2mm and 2mm. This not only ensures the isolation of the pole post 2 and the limiting part 1031 and prevents short circuits between the pole post 2 and the cover plate body 1, but also controls the height of the limiting part 1031 and the overall thickness of the upper insulating member 3, thus occupying less space and improving the space utilization of the battery pack.

[0063] Preferably, T4 is 0.2mm, 0.3mm, 0.4mm, 0.8mm, 1mm, 1.2mm, 1.6mm, 1.8mm or 2mm.

[0064] In one embodiment, the upper side of the upper insulating member 3 extends along the outer side of the limiting portion 1031 to form a peripheral portion 301 surrounding the limiting portion 1031. The upper insulating member 3 encloses the limiting portion 1031, which can effectively limit the limiting portion 1031 and prevent it from shifting or deforming during use. This helps to ensure that the relative position between the battery terminal 2 and other components remains stable and avoids loosening of the connection due to vibration or impact.

[0065] Specifically, the cross-sectional shape of the annular component 103 is similar to a "Z" shape, which not only facilitates fixing on the second metal layer 102, but also facilitates pressing the pole post 2. The structure of the annular component 103 is simple and easy to implement.

[0066] It should be noted that the units for T1, T2, T3, L1, L2, T4, and T5 are all mm.

[0067] According to an embodiment of the present invention, another aspect provides a battery, comprising: the aforementioned cover plate, housing 4, and battery cell, wherein the housing 4 has an opening for mounting the cover plate; and the battery cell is disposed within the housing 4.

[0068] In one embodiment, the material of the housing 4 is the same as that of the first metal layer 101, and the housing 4 is welded to the first metal layer 101 of the cover plate. The housing 4 and the first metal layer 101 have the same melting point, which facilitates welding of the housing 4 to the cover plate and achieves an effective connection between the housing 4 and the cover plate.

[0069] Furthermore, the first metal layer 101 is made of steel, the casing 4 is made of steel, and the second metal layer 102 is made of aluminum. Both the casing 4 and the first metal layer 101 are made of steel, which has better strength properties, resulting in greater structural strength for the cover plate body 1 and the casing 4. This allows them to better withstand external impacts and pressures, reducing the risk of damage to internal battery components due to collisions or drops. The second metal layer 102 is made of aluminum, which has better heat dissipation properties, facilitating heat dissipation for the terminals 2 and the cover plate, and improving the battery's charging rate.

[0070] Although embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A cover plate, characterized in that The cover plate body (1) is provided with a pole hole, and the cover plate body (1) comprises a first metal layer (101) and a second metal layer (102), the first metal layer (101) and the second metal layer (102) are arranged in a stacking manner along the thickness direction of the cover plate, the hardness of the first metal layer (101) is greater than that of the second metal layer (102), and the thermal conductivity of the second metal layer is greater than that of the first metal layer (101). The pole (2) is arranged at least partially in the pole hole. An annular part (103) is arranged in an insulating manner between the pole (2), the annular part (103) comprises a limiting part (1031), a welding part (1032) and a transition part (1033), the limiting part (1031) is used for limiting the pole (2), the welding part (1032) is welded and connected with the second metal layer (102), the transition part (1033) is used for connecting the limiting part (1031) and the welding part (1032), and the material of the annular part (103) is the same as that of the second metal layer (102). The ratio of the thickness T1 of the first metal layer (101) to the thickness T2 of the second metal layer (102) is 0.1-12.

5. The first metal layer (101) is arranged above the second metal layer (102).

2. The cover sheet of claim 1, wherein The ratio of the thickness T1 of the first metal layer (101) to the thickness T2 of the second metal layer (102) is 0.1-12.

3. The cover sheet of claim 2, wherein, On one side close to the annular part (103), the second metal layer (102) is arranged with a protruding step (1021) protruding from the first metal layer (101), and the welding part (1032) is welded and connected with the upper surface of the protruding step (1021).

4. The cover sheet of claim 2, wherein, Along the length direction of the cover plate, the length L1 of the protruding step (1021) is 0.4mm-8mm.

5. The cover plate of claim 4, wherein, Along the thickness direction of the cover plate, the upper surface of the welding part (1032) is lower than the upper surface of the first metal layer (101).

6. The cover sheet of claim 2, wherein, Along the thickness direction of the cover plate, the height difference T5 between the upper surface of the welding part (1032) and the upper surface of the first metal layer (101) is 0.2mm-2.5mm.

7. The cover sheet of claim 6, wherein, The first metal layer (101) is arranged below the second metal layer (102).

8. The cover sheet of claim 1, wherein The ratio of the thickness T1 of the first metal layer (101) to the thickness T2 of the second metal layer (102) is 0.15-12.

5.

9. The cover sheet of claim 8, wherein, The T1 is 0.2mm-2.5mm.

10. The cover sheet of claim 1, wherein The T2 is 0.2mm-2mm.

11. The cover sheet of claim 1, wherein The thickness T3 of the annular part (103) is 0.2mm-2mm.

12. The cover sheet of claim 1, wherein The material of the first metal layer (101) is steel, and the material of the second metal layer (102) is aluminum.

13. The cover sheet of claim 1, wherein The T1 is 0.2mm-2mm, and the T2 is 0.2mm-1.6mm.

14. The cover sheet of claim 13, wherein, The ratio of the thickness T3 of the annular part (103) to the thickness T2 of the second metal layer (102) is 0.1-10.

15. The cover sheet of claim 1, wherein ​ 16. The cover sheet of claim 1, wherein The outer peripheral wall of the lower end of the pole (2) has a convex ring (201) protruding outward, the part of the limiting portion (1031) extends above the convex ring (201), and the distance L2 between the outer peripheral surface of the convex ring (201) and the inner peripheral surface of the limiting portion is 0.1-5mm.

17. The cover sheet of claim 16, wherein, The cover plate further comprises an upper insulating member (3) arranged between the pole (2) and the annular member (103), and the thickness T4 of the part of the upper insulating member (3) between the limiting portion (1031) and the convex ring (201) is 0.2-2mm.

18. The cover sheet of claim 17, wherein, The upper side of the upper insulating member (3) extends along the outside of the limiting portion (1031) to form a peripheral portion (301) surrounding the limiting portion (1031).

19. A battery, characterized by Comprise: The cover plate of any one of claims 1-18; A shell (4) having an opening for mounting the cover plate; An electric core arranged in the shell (4).

20. The battery of claim 19, wherein, The material of the shell (4) is the same as that of the first metal layer (101), and the shell (4) is welded to the first metal layer (101) of the cover plate.

21. The battery of claim 20, wherein, The material of the first metal layer (101) is steel, the material of the shell (4) is steel, and the material of the second metal layer (102) is aluminum.

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