Secondary battery

Abstract

To provide a secondary battery capable of at least improving energy density of the battery and saving manufacturing cost.SOLUTION: The secondary battery includes an electrode member having a first electrode tab, and a top cover member including a top cover plate and an electrode post, the electrode post includes a base plate disposed on a side of the top cover plate facing the electrode member, and the first electrode tab is directly connected to the base plate. The above technical solution can at least improve the energy density of the battery and save the manufacturing cost.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to the field of battery technology, and more particularly to secondary batteries. [Background technology]

[0002] With the development of science and technology, secondary batteries are widely used in portable electronic devices such as mobile phones, digital video cameras, and laptop computers, and are expected to be widely applied in electric vehicles such as electric cars and electric bicycles, as well as large and medium-sized electric equipment such as power storage equipment, becoming an important technological means for solving issues such as the energy crisis and environmental pollution.

[0003] With the development of secondary battery technology, there is a demand for battery cells with ever higher energy density. Summary of the Invention [Problem to be solved by the invention]

[0004] SUMMARY OF THE INVENTION In view of the problems in the related art, the object of the present invention is to provide a secondary battery, which at least improves the energy density of the battery and saves the manufacturing cost. [Means for solving the problem]

[0005] The technical solution of the present invention is realized as follows:

[0006] In one aspect of the present invention, there is provided a secondary battery comprising an electrode member having a first electrode tab, a top cover plate and a top cover member comprising an electrode post, the electrode post comprising a base plate installed on the side of the top cover plate facing the electrode member, and the first electrode tab being directly connected to the base plate.

[0007] In some embodiments, the electrode post further includes an upper metal portion, which is connected to the base plate from the side of the top cover plate facing away from the electrode member through an opening in the top cover plate.

[0008] In some embodiments, the first electrode tab is directly connected to the base plate by ultrasonic welding.

[0009] In some embodiments, the first electrode tab is directly connected to the base plate by torque welding.

[0010] In some embodiments, the first electrode tab and the base plate are directly connected at one connection location, and the length of the connection location is parallel to the length of the top cover member.

[0011] In some embodiments, the material of the first electrode tab is aluminum.

[0012] In some embodiments, the top cover member further includes an insulating sealing member that passes through the opening and isolates the base plate and the upper metal portion from the top cover plate.

[0013] In some embodiments, the electrode post is a first electrode post, the top cover member further includes a second electrode post, the electrode member further has a second electrode tab, the second electrode tab and the first electrode tab are located on the same end surface of the electrode member, the second electrode post includes a base plate installed on the side of the top cover plate facing the electrode member, and the second electrode tab is directly connected to the base plate of the second electrode post.

[0014] In some embodiments, the electrode member is a first electrode member, and the secondary battery further includes a second electrode member having a first electrode tab and a second electrode tab, the first electrode tab and the second electrode tab of the second electrode member being directly connected to the base plate of the first electrode post and the base plate of the second electrode post, respectively.

[0015] In some embodiments, the secondary battery is a prismatic battery. [Effects of the Invention]

[0016] In an embodiment of the present invention, the electrode tabs are directly connected to the base plates of the electrode posts, eliminating the need for conventional connecting pieces, thereby reducing the weight of the battery. Furthermore, by eliminating the need for connecting pieces, the height of the electrode members that would otherwise be occupied by the connecting pieces in the thickness direction can be freed up, maximizing the use of the internal space of the housing. The saved internal space can be used to expand the size of the electrode members, thereby improving energy density. At the same time, by eliminating the need for connecting pieces, the process of welding the electrode members to the connecting pieces can be omitted, thereby reducing manufacturing costs. [Brief explanation of the drawings]

[0017] In order to more clearly describe the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings that need to be used in the embodiments. The drawings in the following description are only some embodiments of the present invention, and it is obvious to those skilled in the art that other drawings can be obtained based on these drawings without paying creative labor. [Figure 1] 2 is a schematic overhead view of a top cover member and an electrode member in the secondary battery according to the embodiment of the present invention. FIG. [Figure 2] 10 is a schematic cross-sectional view of an electrode post in a top cover member according to an embodiment of the present invention. FIG. [Figure 3A] 1 is a schematic diagram showing the shape of a welding head and a welding sheet of an ultrasonic welding machine that can be used to weld an electrode tab according to an embodiment of the present invention. FIG. [Figure 3B] 1 is a schematic diagram of a torque welding pin shape that can be used to weld electrode tabs according to an embodiment of the present invention. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0018] The following clearly and completely describes the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. It is clear that the described embodiments are only some embodiments of the present invention, and are not all embodiments. All other embodiments that a person skilled in the art can obtain based on the embodiments of the present invention fall within the protection scope of the present invention.

[0019] Many current secondary batteries (e.g., prismatic aluminum-cased batteries) use connectors as a bridge or intermediary between the electrode components (also known as bare cells) and the top cover or casing, and the electrode components must be connected to the top cover or casing through the connectors. However, because the connectors themselves have a certain thickness, they take up space within the electrode components inside the secondary battery, limiting improvements in the battery's energy density. The thickness of connectors currently widely used on the market is typically 0.5 to 3 mm, which results in a 1% reduction in energy density when calculated based on a connector thickness of 1 mm and a battery casing height of 100 mm.

[0020] An embodiment of the present invention provides a secondary battery. As shown in FIG. 1 , the secondary battery 100 may include a first electrode member 110, which may include a main body 111, a first electrode tab 112, and a second electrode tab 114. The main body 111 may be formed by stacking and winding a first electrode plate (e.g., a positive electrode plate), a second electrode plate (e.g., a negative electrode plate), and a diaphragm positioned between the first and second electrode plates, with the diaphragm serving as an insulator between the first and second electrode plates. The first electrode tab 112 and the second electrode tab 114 may be formed by foil material (also referred to as a current collector) of the uncoated active material of the first and second electrode plates. In some embodiments, the first electrode tab 112 and the second electrode tab 114 each include a multilayer foil material.

[0021] In this embodiment, the secondary battery 100 is a prismatic battery. The body 111 has a generally flat rectangular structure. The body 111 may have an axial direction D1 and may be formed by winding a first electrode plate, a second electrode plate, and a diaphragm around the axial direction D1. The axial direction D1 of the body 111 may correspond to its height direction. The body 111 has two opposite end surfaces along the axial direction D1. The second electrode tab 114 and the first electrode tab 112 are both located on the same end surface of the first electrode member 110. The secondary battery 100 may further include a second electrode member 130 similar to the first electrode member 110. The second electrode member 130 has a body 131 and first and second electrode tabs 132 and 134 located on the same end surface of the body 131. In this embodiment, the first electrode tabs 112, 132 of the first electrode member 110 and the second electrode member 130 are assumed to be positive electrode tabs, and the second electrode tabs 114, 134 of the first electrode member 110 and the second electrode member 130 are assumed to be negative electrode tabs.

[0022] The secondary battery 100 may further include a top cover member 150, which may include a top cover plate 151, a first electrode post 152, and a second electrode post 154. The first electrode tab 112 and the second electrode tab 114 of the first electrode member 110 are located on an end surface of the first electrode member 110 adjacent to the top cover member 150. The first electrode tab 132 and the second electrode tab 134 of the second electrode member 130 are located on an end surface of the second electrode member 130 adjacent to the top cover member 150. It should be understood that the first electrode member 110 and the second electrode member 130 may be housed in a housing (not shown), and the top cover member 150 may be used to seal an opening of the housing.

[0023] In some embodiments, at least one electrode tab of at least one electrode member is connected to a corresponding electrode post using a method described herein. In the embodiment of FIG. 1 , the first electrode tab 112 and the second electrode tab 114 of the first electrode member 110 and the first electrode tab 132 and the second electrode tab 134 of the second electrode member 130 can all be connected to the corresponding first electrode post 152 and the second electrode post 154 using a method described herein. The structures of the first electrode post 152 and the second electrode post 154 can be similar or identical. Below, the embodiments of the present invention will be described mainly in terms of the structure of the first electrode post 152 and the connection between the first electrode tab 112 of the first electrode member 110 and the first electrode post 152.

[0024] 2 is a cross-sectional schematic view of a first electrode post 152 in a top cover member 150 according to an embodiment of the present invention. Directions X, Y, and Z in FIGS. 1 and 2 are perpendicular to each other. As shown in FIG. 2, the top cover member 150 may include a top cover plate 151 and a first electrode post 152. The first electrode post 152 may further include a base plate 152A installed on the side of the top cover plate 151 facing the first electrode member 110 (see FIG. 1).

[0025] As shown in FIGS. 1 and 2 , the first electrode tab 112 of the first electrode member 110 can be directly connected to the base plate 152A of the first electrode post 152. By directly connecting the first electrode tab 112 to the base plate 152A of the first electrode post 152, the weight of the battery can be reduced because an existing connecting piece is not used. Furthermore, by not using a connecting piece, the height of the electrode member, which is otherwise occupied in the direction of the thickness of the connecting piece, can be freed up, maximizing the use of the internal space of the housing. The saved internal space can be used to increase the size of the electrode member, thereby improving energy density. At the same time, by not using a connecting piece, the process of welding the electrode member and the connecting piece can be omitted, thereby reducing manufacturing costs. Currently, the thickness of connecting pieces commonly used on the market is typically 0.5 to 3 mm. Assuming a connecting piece thickness of 1 mm and a height of the electrode member of 100 mm, the energy density of the electrode member can be improved by 1% by not using a connecting piece.

[0026] In some embodiments, the first electrode tab 112 and the base plate 152A of the first electrode post 152 are directly connected at the connection position 190. The base plate 152A of the first electrode post 152 can overlap and be directly connected to the first electrode tab 112 in the region of the connection position 190. The connection position 190 can have a rectangular bird's-eye view shape. The length direction (Y direction) of the connection position 190 is parallel to the length direction of the top cover member 150.

[0027] Specifically, the first electrode post 152 may further include an upper metal portion 152B, which is connected to the base plate 152A from the side of the top cover plate 151 facing away from the first electrode member 110 (see FIG. 1) through an opening 151v in the top cover plate 151. In the vertical direction Z passing through the opening 151v, the projection of the base plate 152A may completely cover the opening 151v, i.e., the size of the base plate 152A is larger than the size of the opening 151v.

[0028] The upper metal portion 152B may include a first metal portion 1521 and a second metal portion 1522 connected between the first metal portion 1521 and the base plate 152A. The size of the first metal portion 1521 is also larger than the size of the opening 151v, and the size of the second metal portion 1522 is smaller than the size of the opening 151v. The second metal portion 1522 penetrates the opening 151v, so that the upper metal portion 152B may have a T-shaped cross-section. In some embodiments, the material of the base plate 152A of the first electrode post 152 may be pure aluminum, pure copper, nickel-plated copper, an alloy, or the like. The thickness of the base plate 152A may be within a range of 0.5 mm to 3 mm. In some embodiments, the upper metal portion 152B and the base plate 152A may be connected as a single unit by riveting, press forming, machining, integral friction welding, or the like, and may penetrate the opening 151v of the top cover plate 151 to achieve an internal and external conductive connection.

[0029] The top cover member 150 may further include an insulating sealing member 160 that penetrates the opening 151v and isolates the base plate 152A and the upper metal portion 152B from the top cover plate 151. Specifically, the insulating sealing member 160 may include an insulating member 162 and a sealing ring 164 on the insulating member 162. The insulating member 162 may be made of, for example, insulating plastic.

[0030] A welding method can be used to achieve a direct connection between the first electrode tab 112 and the base plate 152A. One prior art technique involves using an ultrasonic welding process to weld the inherently loose electrode tab foil material of the electrode member together, and then using a laser welding process to weld the electrode tab to the top cover or housing. However, when using a conventional laser welding process to weld the electrode tab to the top cover or housing, the electrode tab at the welded portion melts after reaching its melting point during laser welding. When the electrode tab changes from a liquid phase to a solid phase, the thermal expansion and cold contraction of the material can lead to breakage of the foil material.

[0031] According to some embodiments of the present invention, the first electrode tab 112 can be directly connected to the base plate 152A by ultrasonic welding. In some embodiments, the power range of the ultrasonic welder used can be 3000 W to 9000 W. In some embodiments, the ultrasonic welding parameters used can be energy 200 to 800 J, amplitude 20% to 70%, air pressure 0.1 to 0.6 MPa, and welding time 0.2 to 0.7 s. The shape of the welding head and welding sheet 200 of the usable ultrasonic welder can be spherical (as shown in FIG. 3A). In some embodiments, the shape of the welding head and welding sheet 200 of the ultrasonic welder can also be diamond-shaped (e.g., as shown in FIG. 3B, which is shown as a square). It should be understood that the above-mentioned ultrasonic welding power ranges, parameters, welding head, and welding sheet shapes are merely exemplary.

[0032] According to some other embodiments of the present invention, the first electrode tab 112 can be directly connected to the base plate 152A by torque welding. In some embodiments, the power range of the torque welding machine used is 1200 W to 9000 W. In some embodiments, the torque welding parameters used are energy 200 to 800 J, torque 20% to 70%, air pressure 0.1 to 0.6 MPa, and welding time 0.2 to 0.7 s. The shape of the torque welding pin 300 of a usable torque welding machine can be spherical (as shown in FIG. 3A). In some embodiments, the shape of the torque welding pin 300 can also be diamond-shaped (for example, as shown in FIG. 3B, which is shown as a square). It should be understood that the above-mentioned torque welding power range, parameters, and welding pin shape are merely exemplary.

[0033] 1 and 2, by welding the first electrode member 110 and the base plate 152A of the first electrode post 152 by ultrasonic welding or torque welding, the use of a laser welding process can be avoided, the melting point of the electrode tab material is not reached, melting of the electrode tab is not caused, and breakage of the electrode tab due to the transition between liquid and solid phases is not caused. In addition, the connection strength of the ultrasonic welding or torque welding is also guaranteed, and a strong connection between the electrode member and the base plate 152A of the electrode post is ensured.

[0034] In an embodiment in which the first electrode tab 112 is a positive electrode tab, the material of the first electrode tab 112 can be aluminum. In such an embodiment, the material of the second electrode tab 114, which is a negative electrode tab, can be copper. In some embodiments, the number of foil layers of the positive electrode tab and the negative electrode tab can each be 20 to 100 layers, with the foil material (aluminum foil) of the single-layer positive electrode tab having a thickness of 10 to 15 μm per layer and the foil material (copper foil) of the single-layer negative electrode tab having a thickness of 4 to 8 μm per layer.

[0035] As described above, when the electrode tab is welded to the top cover or housing using a conventional laser welding process, laser welding forms a molten pool after the weld reaches its melting point. However, the aluminum used in the positive electrode tab has a relatively high expansion coefficient, and as the molten pool melts and solidifies, the aluminum material changes from liquid to solid, causing volume changes due to thermal expansion and cooling contraction, which can lead to fracture of the foil material. By using ultrasonic welding or torque welding to weld the first electrode member 110 to the base plate 152A of the first electrode post 152, the aluminum material does not reach its melting point, causing the electrode tab to melt, and preventing the electrode tab from breaking due to the transition between liquid and solid phases.

[0036] Furthermore, because the top cover member 150 requires the insulating sealing member 160 to isolate the base plate 152A and the upper metal portion 152B from the top cover plate 151, if welding is performed using a laser welding process, the amount of heat generated by the laser welding is relatively large, causing the insulating member 162, which provides insulation within the insulating sealing member 160, and the sealing ring 164, which provides sealing within the first electrode post 152, to melt, thereby affecting the insulating and sealing effects. By using ultrasonic welding or torque welding to weld the first electrode tab 112 to the base plate 152A of the first electrode post 152, the temperature during the welding process can be reduced, preventing the insulating member 162 and the sealing ring 164 from melting and deteriorating the insulating and sealing effects.

[0037] The above-described embodiments are merely preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included within the scope of protection of the present invention. [Industrial Applicability]

[0038] The secondary battery of the present invention can be applied to the field of battery technology. [Explanation of symbols]

[0039] 100: Secondary battery 110: First electrode member 111: Main body 112: First electrode tab 114: Second electrode tab 130: Second electrode member 131: Main body 132: First electrode tab 134: Second electrode tab 150: Top cover material 151: Top cover plate 152: First electrode post 152A: Base plate 152B: Upper metal part 151v:Aperture 1521:First Metal Department 1522:Second metal part 154: Second electrode post 160: Insulating sealing material 162: Insulating material 164: Sealing ring 190: Connection position 200: Welding head seat for ultrasonic welding machine 300: Torque welding pin D1: Axial direction X, Y, Z: direction

Claims

1. an electrode member having a first electrode tab; a top cover member including a top cover plate and electrode posts; The electrode post has a base plate installed on the side of the top cover plate facing the electrode member, and the first electrode tab is directly connected to the base plate.

2. 2. The secondary battery of claim 1, wherein the electrode post has an upper metal portion, and the upper metal portion is connected to the base plate from the side of the top cover plate facing away from the electrode member by passing through an opening in the top cover plate.

3. The secondary battery according to claim 1 , wherein the first electrode tab is directly connected to the base plate by ultrasonic welding.

4. The secondary battery according to claim 1 , wherein the first electrode tab is directly connected to the base plate by torque welding.

5. 2. The secondary battery according to claim 1, wherein the first electrode tab and the base plate are directly connected at one connection position, and the length of the connection position is parallel to the length of the top cover member.

6. 2. The secondary battery according to claim 1, wherein the material of the first electrode tab is aluminum.

7. The secondary battery of claim 2 , wherein the top cover member further comprises an insulating sealing member that penetrates the opening and isolates the base plate and the upper metal part from the top cover plate.

8. the electrode post is a first electrode post; the top cover member further includes a second electrode post; the electrode member further includes a second electrode tab; the second electrode tab and the first electrode tab are located on the same end surface of the electrode member; the second electrode post includes a base plate disposed on a side of the top cover plate facing the electrode member; The secondary battery according to claim 1 , wherein the second electrode tab is directly connected to the base plate of the second electrode post.

9. the electrode member is a first electrode member, A secondary battery further comprising a second electrode member having a first electrode tab and a second electrode tab, 9. The secondary battery of claim 8, wherein the first electrode tab and the second electrode tab of the second electrode member are directly connected to the base plate of the first electrode post and the base plate of the second electrode post, respectively.

10. The secondary battery according to claim 1 , wherein the secondary battery is a prismatic battery.

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