Current collector, current collector manufacturing process, sodium ion battery and assembly method

Abstract

This invention relates to the field of power battery technology, and particularly to a current collector, a current collector manufacturing process, a sodium-ion battery, and an assembly method. The current collector connects the negative electrode tab of a sodium-ion all-tab battery to a steel casing. It includes an aluminum sheet, a nickel sheet, and a nickel block. The aluminum sheet has mounting holes, and the nickel sheet is stacked and fixed to the aluminum sheet to form a nickel-aluminum composite layer. The nickel block is inserted into the mounting holes and fixedly connected to the nickel sheet. The current collector is composed of aluminum and nickel sheets. The aluminum sheet can be welded to the aluminum electrode tab, and the nickel sheet can be resistance welded to the steel casing, achieving a stable connection between the aluminum electrode tab and the steel casing. The nickel block inserted into the mounting holes on the aluminum sheet and fixedly connected to the nickel sheet not only improves the stability of the connection between the aluminum and nickel sheets and increases the current carrying capacity, but also indirectly increases the local thickness of the nickel sheet, which is beneficial for resistance welding between the nickel sheet and the steel casing.

Description

Technical Field

[0001] This invention relates to the field of power battery technology, and in particular to a current collector, a current collector manufacturing process, a sodium-ion battery, and an assembly method. Background Technology

[0002] When assembling a lithium-ion full-tab battery, the current collector is usually placed in the center of the battery tab end face. Then, the current collector is welded to the battery tab as a whole using resistance welding. The other side of the current collector is connected to the terminal (positive or negative terminal) by welding. Then, through the connection of the battery tab, current collector, and terminal, the electrical energy of the cell is led out to the positive or negative terminal of the battery.

[0003] Sodium-ion batteries and lithium-ion batteries operate on similar principles, primarily using sodium salts as electrode materials. Sodium salts are more abundant and cheaper than lithium salts. Based on the abundance of materials and the availability of readily available production equipment and processes, sodium-ion batteries are considered a promising energy storage option. Furthermore, due to their similar structure and principles to lithium-ion batteries, many structural features can be mutually adopted. For sodium-ion steel-cased batteries, to achieve a more uniform current distribution within the battery, a structure similar to lithium-ion steel-cased batteries can be adopted, employing a full-tab structure. Due to the special properties of sodium, aluminum foil can be used as the tab and current collector for the negative electrode. Aluminum has a cost advantage over copper (copper foil is commonly used as the tab and current collector in aluminum-ion batteries). However, aluminum's low melting point makes it difficult to directly apply the nickel current collector used in lithium-ion full-tab steel-cased batteries to connect the cell and the steel casing (negative electrode). Therefore, how to effectively connect the aluminum tabs to the steel casing is a crucial problem that needs to be solved in the research of sodium-ion full-tab steel-cased batteries. Summary of the Invention

[0004] One of the objectives of this invention is to provide a current collector that enables effective connection between the negative electrode tab and the steel casing in a sodium-ion all-tab battery.

[0005] To achieve this objective, the present invention adopts the following technical solution:

[0006] A current collector, used to connect the negative electrode tab of a sodium-ion all-tab battery to a steel shell, includes an aluminum sheet, a nickel sheet, and a nickel block. The aluminum sheet has mounting holes, and the nickel sheet is stacked and fixed with the aluminum sheet to form a nickel-aluminum composite layer. The nickel block is inserted into the mounting holes and fixed to the nickel sheet.

[0007] Optionally, the aluminum sheet is provided with a plurality of first bosses protruding toward the side away from the nickel sheet, and the first bosses are arranged around the mounting hole.

[0008] Optionally, the nickel sheet is provided with a plurality of second protrusions, and the back sides of the first protrusion and the second protrusions form grooves. The grooves formed on the back sides of the first protrusions match the shape and size of the second protrusions, and the second protrusions are placed one-to-one in the grooves formed on the back sides of the first protrusions.

[0009] Optionally, the nickel-aluminum composite layer is further provided with a plurality of through holes, which are arranged around the mounting hole.

[0010] Optionally, a limiting stop edge is also provided around the surface of the aluminum sheet facing away from the nickel sheet.

[0011] The second objective of this invention is to provide a process for manufacturing a manifold as described above, specifically including the following steps:

[0012] A number of mounting holes are punched in batches on aluminum plates using a stamping process.

[0013] Several nickel blocks are stamped from a first nickel plate using a stamping process, and the size of the nickel blocks is the same as the size of the mounting holes.

[0014] The nickel block is fixed to the second nickel plate according to the distribution pattern of the mounting holes on the aluminum plate;

[0015] The aluminum plate is placed on the second nickel plate, and the nickel blocks pass through the mounting holes opened on the aluminum plate one by one. The aluminum plate and the second nickel plate are pressed together by repeated hot pressing to form a nickel-aluminum composite plate.

[0016] The manifold is stamped off the nickel-aluminum composite plate using a stamping process.

[0017] Optionally, the nickel block and the second nickel plate are connected and fixed by hot pressing.

[0018] Optionally, the thickness of the first nickel plate is greater than the thickness of the second nickel plate.

[0019] The third objective of this invention is to provide a sodium-ion battery, comprising a steel casing, a battery cell, and a current collector as described above. The battery cell includes an aluminum negative electrode sheet, on which an aluminum tab is disposed. The aluminum tab is welded to the aluminum sheet, and the steel casing is welded to the nickel sheet.

[0020] The fourth objective of this invention is to provide an assembly method for assembling the aforementioned sodium-ion battery, characterized by comprising the following steps:

[0021] Flatten the tabs of the rolled battery cell, cover the current collector with one end of the negative electrode of the battery cell, and weld the aluminum tabs to the aluminum sheet using laser welding. After welding, place the battery cell and the current collector together inside the steel shell, with the current collector in contact with the bottom of the steel shell. The welding head of the resistance welding passes through the center hole and mounting hole of the battery cell and abuts against the nickel block, welding the nickel sheet to the inner end face of the steel shell, so that the nickel sheet is welded and fixed to the steel shell. Then, complete the connection of the positive current collector to the positive electrode of the battery cell and the steel shell according to the normal battery assembly sequence.

[0022] The beneficial effects of this invention are as follows: The current collector in this invention is composed of aluminum sheets and nickel sheets. The aluminum sheets can be welded to aluminum tabs, and the nickel sheets can be resistance welded to the steel shell, achieving a stable connection between the aluminum tabs and the steel shell. The nickel block inserted into the mounting holes on the aluminum sheets and fixed to the nickel sheets not only improves the stability of the connection between the aluminum sheets and the nickel sheets and increases the current carrying capacity, but also indirectly increases the local thickness of the nickel sheets, which is beneficial for resistance welding between the nickel sheets and the steel shell. The current collector manufacturing method in this invention can process the current collectors in batches, improving the production efficiency of the current collectors. The sodium-ion battery using this current collector can adopt a full tab structure, making the current distribution inside the battery more uniform. The assembly method in this invention can flexibly adopt different welding methods according to the structural composition of the sodium-ion battery, improving the assembly efficiency of the sodium-ion battery. Attached Figure Description

[0023] Figure 1 This is a three-dimensional structural diagram of the collector disk in an embodiment of the present invention;

[0024] Figure 2 This is an exploded structural diagram of the collector disk in an embodiment of the present invention;

[0025] Figure 3 This is a top view of the collector disk in an embodiment of the present invention;

[0026] Figure 4 This is a bottom view of the collector disk in an embodiment of the present invention;

[0027] Figure 5 This is a side view of the collector disk in an embodiment of the present invention;

[0028] Figure 6 This is a flowchart illustrating the processing of the mounting holes in an embodiment of the present invention;

[0029] Figure 7 This is a flowchart illustrating the processing of nickel blocks in an embodiment of the present invention;

[0030] Figure 8 This is a schematic diagram of the installation structure of the nickel block and the second nickel plate in an embodiment of the present invention;

[0031] Figure 9This is a schematic diagram of the stamping process of the manifold in an embodiment of the present invention.

[0032] In the diagram, 1. Aluminum sheet; 2. Nickel sheet; 3. Mounting hole; 4. Nickel block; 5. First boss; 6. Groove; 7. Permeation hole;

[0033] 10. Aluminum plate; 20. First nickel plate; 30. Second nickel plate. Detailed Implementation

[0034] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0035] In the description of this invention, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0036] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0037] In the description of this embodiment, the terms "upper," "lower," "left," and "right," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention. In addition, the terms "first" and "second" are used only for distinction in description and have no special meaning.

[0038] Figures 1-5The image shown is a collector plate according to a partial embodiment of the present invention. The collector plate includes an aluminum sheet 1, a nickel sheet 2, and a nickel block 4. The aluminum sheet 1 and the nickel sheet 2 are rolled or hot-pressed to form a nickel-aluminum composite layer. The aluminum sheet 1 has a mounting hole 3, and the nickel block 4 is inserted into the mounting hole 3 and fixed to the nickel sheet 2. The mounting hole 3 and the nickel block 4 are the same size, and their specific shape is not limited in this embodiment. They can be set to shapes such as circular, square, or other shapes.

[0039] In this embodiment, the current collector is constructed by stacking and fixing aluminum sheet 1 and nickel sheet 2 together using hot pressing or rolling. When connecting the aluminum tabs and the steel shell, aluminum sheet 1 is welded to the aluminum tabs, and nickel sheet 2 is welded to the steel shell. Since aluminum sheet 1 and the aluminum tabs are made of the same material and have the same melting point, the welding effect is good. Similarly, nickel sheet 2 and the steel shell have similar melting points, resulting in good welding. The welding of the current collector to the steel shell is performed after the battery cell is installed in the steel shell. The current collector and the steel shell can only be welded using resistance welding. Due to the limitations of the stacking and fixing method (hot pressing) for aluminum sheet 1 and nickel sheet 2, the thickness of both aluminum sheet 1 and nickel sheet 2 cannot be too thick. Resistance welding utilizes the resistance heat generated by the current passing through the workpiece and the contact area. The method of heating the welded parts locally with heat and applying pressure as a heat source has certain requirements on the thickness of the weldment. The nickel block 4 inserted into the mounting hole 3 serves as the contact point for resistance welding. The presence of the nickel block 4 is equivalent to locally increasing the thickness of the nickel sheet 2, which can be connected to the steel shell by resistance welding. At the same time, the presence of the nickel block 4 also improves the stability of the connection between the aluminum sheet 1 and the nickel sheet 2, resulting in good current flow. The nickel block 4 is set in the mounting hole 3, and during the resistance welding connection between the nickel sheet 2 and the steel shell, the resistance weld directly contacts the nickel block 4 and the steel shell, rather than directly contacting the aluminum sheet 1. The aluminum sheet 1 is less likely to produce spatter, reducing the possibility of battery short circuits or poor welding, and improving the welding yield.

[0040] To avoid increasing the thickness of the entire current collector and taking up extra internal battery space due to the presence of nickel block 4, nickel block 4 does not protrude from aluminum sheet 1. In this embodiment, the end face of nickel block 4 inserted into mounting hole 3 is flush with the side surface of aluminum sheet 1 facing away from nickel sheet 2.

[0041] The aluminum sheet 1 has multiple first protrusions 5 protruding away from the nickel sheet 2 for welding to the flattened aluminum electrode tab. These first protrusions 5 surround the mounting hole 3. Since the flattened aluminum electrode tab has low flatness, the first protrusions 5 ensure sufficient contact between the aluminum electrode tab and the aluminum sheet 1, preventing incomplete welding. Specifically, the first protrusions 5 are formed by stamping. After rolling or hot pressing, the nickel sheet 2 has multiple second protrusions formed simultaneously with the first protrusions 5. Grooves 6 are formed on the back of both the first and second protrusions, and the shape and size of the grooves 6 on the back of the first protrusions 5 match those of the second protrusions. Each second protrusion is placed in a corresponding groove 6 on the back of the first protrusion 5. The grooves 6 further improve the connection stability between the nickel sheet 2 and the aluminum sheet 1.

[0042] To facilitate electrolyte penetration, the manifold is also provided with multiple penetration holes 7, which are arranged around the mounting hole 3.

[0043] Optionally, multiple first protrusions 5 (second protrusions) and permeation holes 7 are alternately arranged around the mounting hole 3 to ensure uniform permeation of the electrolyte. The mounting hole 3 is located at the center of the aluminum sheet 1. The area of ​​the first protrusions 5 (second protrusions) should be set as large as possible. The shape of the first protrusions 5, the second protrusions and the permeation holes 7 are not limited in this embodiment. For example, the first protrusions 5 and the second protrusions can be set as arcs bending towards the outer periphery of the nickel-aluminum composite layer or arcs bending towards the center of the nickel-aluminum composite layer, or U-shaped or W-shaped, etc., while the permeation holes 7 can be set as teardrop-shaped.

[0044] A limiting flange is also provided around the surface of the aluminum sheet 1 facing away from the nickel sheet 2. The limiting flange can limit the position of the battery cell, so that the first protrusion 5 is aligned with the aluminum electrode tab, preventing the battery cell or current collector from shifting, causing welding misalignment, or preventing the battery cell from being unable to enter the shell due to radial displacement of the current collector. Specifically, the limiting flange can be set as a continuous ring structure, or it can be set as arc segments spaced apart along the circumference of the aluminum sheet 1. The shape of the ring structure or arc segments is adapted to the shape of the battery cell. In this embodiment, in order to reduce the processing difficulty, the limiting flange is set as a circular ring structure, formed by stamping, and the limiting flange should be as thin as possible to increase the space occupied by the battery cell in the steel shell and improve the space utilization rate.

[0045] refer to Figures 6-9 As shown, another embodiment of the present invention also proposes a manufacturing process for a collector plate, which is used to manufacture the aforementioned collector plate, and specifically includes the following steps:

[0046] A number of mounting holes 3 are punched in batches on aluminum plate 10 using a stamping process;

[0047] Several nickel blocks 4 are stamped on the first nickel plate 20 using a stamping process. The size of the nickel blocks 4 is the same as the size of the mounting holes 3.

[0048] According to the distribution pattern of mounting holes 3 on aluminum plate 10, nickel block 4 is fixed on second nickel plate 30 by hot pressing;

[0049] An aluminum plate 10 is placed on a second nickel plate 30, and nickel blocks 4 pass through mounting holes 3 on the aluminum plate 10 one by one. After repeated hot pressing, the aluminum plate 10 and the second nickel plate 30 are hot pressed together to form a nickel-aluminum composite plate.

[0050] The permeation hole 7, the first boss 5 (second boss) and the limiting stop are stamped using a stamping process, and the collector plate is stamped down according to the preset size of the collector plate.

[0051] For example, the mounting hole 3 is a square hole. The thickness of the first nickel plate 20 is slightly greater than the thickness of the aluminum plate 10, that is, the thickness of the nickel block 4 is greater than the depth of the mounting hole 3. During the hot pressing process, the nickel block 4 inserted into the mounting hole 3 can undergo a certain deformation and have an interference fit with the aluminum plate 10. The end face of the nickel block 4 inserted into the mounting hole 3 is flush with the side surface of the aluminum sheet 1 that is away from the nickel sheet 2, which improves the connection stability between the aluminum sheet 1 and the nickel sheet 2.

[0052] In other embodiments, the nickel block 4 and the second nickel plate 30 can also be welded by laser welding.

[0053] Using the above manufacturing process, mass production of manifolds can be achieved with high production efficiency.

[0054] In another embodiment of the present invention, a sodium-ion battery is provided, including a steel casing, a cell and the aforementioned current collector. The current collector can be manufactured using the aforementioned manufacturing process. The cylindrical battery can adopt a full tab structure. Its cell includes an aluminum negative electrode sheet with aluminum tabs disposed on it. The aluminum tabs are welded to the aluminum sheet 1, while the steel casing is welded to the nickel sheet 2.

[0055] An embodiment of the present invention also proposes an assembly method for the above-mentioned sodium-ion battery. First, the aluminum tabs of the rolled battery cell are flattened, and the current collector is placed on one end of the negative electrode of the battery cell. The limiting edge limits the battery cell. Then, the aluminum tabs and aluminum sheet 1 are welded to the groove 6 by laser welding. After welding, the battery cell and the current collector are placed together in the steel shell. The current collector contacts the bottom of the steel shell. The welding head of the resistance welding passes through the center hole of the battery cell and the mounting hole 3 and abuts against the nickel block 4. The nickel sheet 2 and the inner end face of the steel shell are welded to fix the nickel sheet 2 to the steel shell. Then, the connection between the positive current collector, the positive electrode of the battery cell, and the steel shell is completed according to the normal battery assembly sequence.

[0056] The above assembly method fully considers the mutual constraints between the components during the assembly process of sodium-ion batteries, flexibly uses different welding methods to complete the assembly, and improves the assembly efficiency of sodium-ion batteries.

[0057] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art will be able to make various obvious changes, readjustments, and substitutions without departing from the scope of protection of the present invention. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A sodium-ion battery, characterized in that, The battery includes a steel casing, a battery cell, and a current collector. The battery cell includes an aluminum negative electrode plate with aluminum tabs disposed thereon. The current collector includes: An aluminum sheet (1) is provided with a mounting hole (3), which is located at the center of the aluminum sheet (1). Nickel sheet (2) is stacked and fixed with aluminum sheet (1) to form a nickel-aluminum composite layer; Nickel block (4), the nickel block (4) is inserted into the mounting hole (3) and fixed to the nickel sheet (2); The aluminum tab is welded to the aluminum sheet (1), and the steel shell is resistance welded to the nickel sheet (2).

2. The sodium-ion battery according to claim 1, characterized in that the aluminum sheet (1) is provided with a plurality of first bosses (5) protruding toward the side away from the nickel sheet (2), and the first bosses (5) are arranged around the mounting hole (3).

3. The sodium-ion battery according to claim 2, characterized in that a plurality of second protrusions are provided on the nickel sheet (2), and the back sides of the first protrusion (5) and the second protrusions form a groove (6), the groove (6) formed on the back side of the first protrusion (5) matches the shape and size of the second protrusion, and the second protrusions are placed in the groove (6) formed on the back side of the first protrusion (5) in a corresponding manner.

4. The sodium-ion battery according to any one of claims 1-3, characterized in that a plurality of permeation holes (7) are further provided through the nickel-aluminum composite layer, and the permeation holes (7) are arranged around the mounting hole (3).

5. The sodium-ion battery according to any one of claims 1-3, characterized in that a limiting stop is further provided around the surface of the aluminum sheet (1) facing away from the nickel sheet (2).

6. A process for manufacturing a manifold, used to manufacture a manifold as described in any one of claims 1-5, characterized in that, Specifically, the steps include the following: Using a stamping process, a number of mounting holes (3) are punched in batches on aluminum plate (10); Several nickel blocks (4) are stamped on the first nickel plate (20) using a stamping process. The size of the nickel blocks (4) is the same as the size of the mounting holes (3). According to the distribution pattern of the mounting holes (3) on the aluminum plate (10), the nickel block (4) is fixed on the second nickel plate (30); The aluminum plate (10) is placed on the second nickel plate (30), and the nickel blocks (4) pass through the mounting holes (3) opened on the aluminum plate (10) one by one. The aluminum plate (10) and the second nickel plate (30) are pressed together by repeated hot pressing to form a nickel-aluminum composite plate. The manifold is stamped off the nickel-aluminum composite plate using a stamping process.

7. The manifold manufacturing process according to claim 6, characterized in that, The nickel block (4) and the second nickel plate (30) are connected and fixed by hot pressing.

8. The manifold manufacturing process according to claim 7, characterized in that, The thickness of the first nickel plate (20) is greater than the thickness of the second nickel plate (30).

9. An assembly method for assembling a sodium-ion battery as described in any one of claims 1-5, characterized in that, Specifically, the steps include the following: Flatten the tabs of the rolled battery cell, cover the current collector with one end of the negative electrode of the battery cell, and weld the aluminum tabs and aluminum sheet (1) by laser welding. After welding, place the battery cell together with the current collector inside the steel shell. The current collector contacts the bottom of the steel shell. The welding head of the resistance welding passes through the center hole of the battery cell and the mounting hole (3) and abuts against the nickel block (4). Weld the nickel sheet (2) and the inner end face of the steel shell so that the nickel sheet (2) is welded and fixed to the steel shell. Then, complete the connection between the positive current collector, the positive electrode of the battery cell and the steel shell according to the normal battery assembly sequence.

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