A battery and a method of manufacturing the same

Abstract

The application discloses a battery and a manufacturing method thereof, and the battery comprises a positive current collector layer, which is a composite structure with dense normal layers and porous functional layers alternately distributed formed on an aluminum foil substrate through electric field assisted selective etching, a positive electrode sheet coated with positive active material aluminum powder and subjected to formation treatment, and a top cover assembly and a bottom cover assembly connected with the positive and negative electrodes through full-tab cross-section laser welding and full-tab end face laser welding respectively; the manufacturing method comprises the steps of preparing a composite positive current collector layer, coating active material, assembling a battery cell, laser welding and packaging, etc. The specific surface area and ion transmission efficiency are greatly improved through the composite current collector layer structure, the internal resistance and temperature rise are reduced by combining the optimized full-tab welding process, so that the rate performance, cycle stability and thermal safety of the battery are significantly improved, and the battery is suitable for the manufacturing of high-power long-life batteries such as electric vehicles and energy storage systems.

Description

Technical Field

[0001] This invention relates to the field of battery manufacturing technology, specifically to a battery and its preparation method. Background Technology

[0002] With the rapid development of electric vehicles, energy storage devices, and high-performance electronic products, higher requirements are being placed on the energy density, power density, cycle life, and safety of batteries. The positive electrode current collector, as a key connecting component between the battery's positive electrode active material and the external circuitry, directly affects the battery's interfacial impedance, ion transport efficiency, and structural stability. Traditional current collectors are mostly flat aluminum foils with limited surface area, resulting in high interfacial impedance and impacting high-rate performance.

[0003] Meanwhile, the internal connection structure of the battery, including the connection method between the terminals, current collectors, and the outer casing, also has a significant impact on the battery's internal resistance, thermal management, and cycle life. Existing welding structures often suffer from problems such as small welding area, long distance between the tabs and the weld points, and insufficient structural strength, resulting in high internal resistance, significant temperature rise, and shortened lifespan.

[0004] Therefore, there is an urgent need for a battery design and fabrication method that can both improve the electrochemical performance of the current collector and optimize the internal connection structure. Summary of the Invention

[0005] The purpose of this invention is to provide a battery and its preparation method, which achieves high rate performance, low internal resistance, high cycle stability and good thermal management capability by combining a positive electrode current collector with a composite structure and an optimized welding structure.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a battery and a method for preparing the same, comprising:

[0007] The positive current collector layer is a composite structure formed on an aluminum foil substrate by electric field-assisted selective etching, which consists of a dense conventional layer and a porous functional layer with periodic alternating distribution. The surface of the porous functional layer has an aluminum oxide protective layer.

[0008] The positive electrode sheet is made by coating the positive current collector layer with a positive active material;

[0009] Negative electrode plate;

[0010] Electrolyte;

[0011] shell;

[0012] The top cover assembly includes a positive electrode connecting piece, a positive electrode post, a positive electrode top cover, and a sealing structure. The positive electrode connecting piece is connected to the positive electrode current collector by laser welding of the cross-section of the full electrode tab.

[0013] The bottom cover assembly includes a negative current collector, a negative bottom cover, and a sealing structure. The negative current collector is connected to the negative electrode sheet by laser welding of the end face of the tab.

[0014] In this invention, the dense conventional layer and the porous functional layer of the positive electrode current collector are arranged alternately.

[0015] In this invention, the positive electrode connecting piece is provided with a laser-penetrating welding groove, which is used to achieve a large-area welding connection with the positive electrode current collector.

[0016] In this invention, the negative electrode current collector is provided with an electrode current penetration welding groove, which is used to achieve a large-area welding connection with the negative electrode sheet.

[0017] In this invention, the top cover assembly further includes a filling sealing ring, a positive electrode separator, and an end cap. The end cap has a groove, and the positive electrode separator is embedded in the groove.

[0018] A method for preparing a battery includes the following steps:

[0019] Step 1: Prepare the composite positive electrode current collector, including:

[0020] a. Symmetrically attach shielding electrodes with an insulating layer to both sides of the aluminum foil;

[0021] b. Connect isostatic electrodes and apply an electric field to form a conventional layer in the shielded area;

[0022] c. Chemical corrosion is carried out under the action of an electric field to form a porous functional layer in the unshielded area;

[0023] Step 2: Apply high-purity nano-sized aluminum powder, the positive electrode active material, to a designated area of ​​the positive electrode current collector to form an electrode. Then, perform high-voltage formation treatment on the electrode to make a positive electrode sheet. Oxidize the porous functional layer to form a surface aluminum oxide protective layer.

[0024] Step 3: Assemble the positive electrode, separator, and negative electrode into a battery cell;

[0025] Step 4: Connect the positive current collector layer of the battery cell to the positive connecting piece in the top cover assembly using laser welding of the cross section of the full-tab;

[0026] Step 5: Connect the negative electrode plate of the battery cell to the negative current collector in the bottom cover assembly using laser welding on the end face of the tabs;

[0027] Step 6: Weld the top cover assembly and bottom cover assembly to the outer casing, inject electrolyte, and seal.

[0028] In this invention, in step a, the shielding electrodes are arranged in strips or grids, and the surface insulating layer is aluminum oxide.

[0029] In this invention, the chemical corrosion in step c uses a mixed acid solvent, which includes one or more of hydrochloric acid, sulfuric acid, and nitric acid.

[0030] In this invention, the oxidation process in step two further includes the electrode being oxidized in a formation tank using a formation solution and a pulsed high-voltage power supply, followed by heat treatment at 550°C.

[0031] In this invention, the welding in steps four and five is performed using pulsed laser or continuous laser welding, with a weld depth of 0.5-1.2 mm and a weld width of 0.8-1.5 mm.

[0032] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0033] This invention constructs a porous / dense composite structure on the current collector layer through electric field-assisted selective corrosion, which significantly improves the specific surface area and ion transport efficiency, reduces interfacial impedance, and enhances rate performance and cycle stability. At the same time, the laser welding structure of the entire tab section greatly increases the welding area, shortens the current path, reduces internal resistance and temperature rise, and improves battery power output and thermal safety. The composite current collector layer and the optimized welding structure work synergistically to improve the overall performance of the battery. Attached Figure Description

[0034] Figure 1 This is a block diagram illustrating the battery fabrication method of the present invention. Detailed Implementation

[0035] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "horizontal," "vertical," "top," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, 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 of the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0037] refer to Figure 1The following embodiments are for illustrative purposes only and are not intended to limit the scope of protection of the present invention.

[0038] Example 1:

[0039] Manufacturing of cylindrical lithium-ion batteries

[0040] Step 1: Prepare the composite positive current collector layer; prepare aluminum foil and shielding electrode. Select high-purity aluminum foil with a thickness of 15μm as the working electrode. The shielding electrode is a graphite sheet with a width of 1mm and a thickness of 0.5mm. The surface is coated with an aluminum oxide insulating layer of about 5μm thickness by anodizing process.

[0041] Aluminum foil, as the substrate for the positive electrode current collector, has good conductivity and ductility; the aluminum oxide layer that shields the electrode surface can prevent it from being eroded during subsequent corrosion processes, while ensuring electrical insulation positioning between it and the aluminum foil.

[0042] The shielding electrodes are symmetrically attached to both sides of the aluminum foil with an equal center-to-center spacing of 2mm and fixed with precision clamps. The symmetrical arrangement of the shielding electrodes can form a uniform shielding area in the subsequent electric field, thereby precisely controlling the position and shape of the corrosion area and realizing the periodic design of the structure.

[0043] An electric field is applied to form a conventional layer. An aluminum foil with a shielded electrode attached is placed between two graphite isostatic electrodes. The electrodes are electrically connected to the aluminum foil. A DC voltage is applied, and the isostatic electric field causes the unshielded area to be in a high potential state, while the shielded area remains at a low potential due to the shielding effect, forming a "potential partition". This provides a physical basis for subsequent selective corrosion. Graphite electrodes have the characteristics of uniform conductivity and corrosion resistance, making them suitable as electrostatic field carriers.

[0044] Chemical etching forms a porous functional layer. The entire device is immersed in an etching solution at 40°C for 90 seconds. In this embodiment, the volume ratio of hydrochloric acid, nitric acid, and water is 1:1:8.

[0045] Under the influence of an electric field, ions in the corrosive solution migrate directionally to the high potential region, i.e. the unshielded part, which accelerates the dissolution of aluminum and forms a porous structure composed of micron / nano-scale pores, significantly increasing the specific surface area. The shielded region has a low potential and a very slow corrosion rate, maintaining a dense structure and forming a mechanical support layer.

[0046] Thus, a composite positive current collector layer with alternating distribution of "dense conventional layer - porous functional layer" was obtained.

[0047] Step 2: Preparation of the positive electrode sheet

[0048] Lithium iron phosphate (LiFePO4), conductive carbon black and PVDF binder were mixed in a mass ratio of 94:3:3 to form a slurry, which was then uniformly coated onto the porous functional layer region of the current collector layer.

[0049] The sample is removed, and high-purity nano-sized aluminum powder, the positive electrode active material, is coated onto the designated area of ​​the positive electrode current collector to form an electrode. The electrode is then subjected to high-voltage formation treatment to form a positive electrode sheet. The porous functional layer is then oxidized to form a surface aluminum oxide protective layer.

[0050] After drying at 110℃ and rolling, a positive electrode sheet is obtained. The porous structure provides a larger active material loading area and a shorter lithium-ion diffusion path, which is beneficial to improving the battery's capacity and rate performance.

[0051] Step 3: Assemble the battery

[0052] In the cell fabrication process, the positive electrode sheet, polyethylene separator, and graphite negative electrode sheet are sequentially wound into a cylindrical cell. The tabs extending from the positive current collector are then connected to the first positive electrode connecting piece in the top cover assembly. A pulsed laser is used to perform full tab cross-section welding through a pre-set laser penetration welding groove. Full tab welding significantly increases the effective welding area and reduces contact resistance. The laser penetration welding groove design allows for controllable welding depth, ensuring connection strength and achieving positive electrode welding.

[0053] The tabs extending from the negative electrode sheet are connected to the negative current collector in the bottom cover assembly. Laser welding of the entire tab end face is performed via a current-through welding groove to achieve negative electrode welding. This structure shortens the current path, reduces internal resistance, and improves the battery's power output and heat dissipation performance.

[0054] The top cover assembly and bottom cover assembly are welded and sealed to the steel shell, 1M LiPF6 electrolyte is injected, and finally sealed and allowed to stand to soak, thus completing the encapsulation and electrolyte injection.

[0055] The first charge-discharge activation was performed at 0.05C, followed by capacity sorting and internal resistance testing.

[0056] Example 2: Fabrication of a Square Power Battery

[0057] The difference between this embodiment and Embodiment 1 lies in the following parameter adjustments to further optimize the high-power performance of the battery:

[0058] The width of the shielding electrodes was adjusted to 0.5 mm, and the spacing was adjusted to 3 mm to form a denser porous area.

[0059] The etching solution was changed to a 10wt% sulfuric acid solution, the etching temperature was 50℃, and the etching time was 120 seconds.

[0060] The oxidation treatment was carried out in air at 350°C for 50 minutes.

[0061] The welding method is continuous laser peripheral welding, with a weld depth of 1.0 mm and a weld width of 1.2 mm.

[0062] The positive electrode active material is a high-nickel ternary material.

[0063] Narrower shielding electrodes and wider spacing design can further increase the active area while maintaining structural strength; the slow sulfuric acid corrosion rate is conducive to forming a more uniform pore structure; continuous laser welding is suitable for large-area connection of square batteries, improving the overall structural integrity and thermal management capabilities.

[0064] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A battery, characterized in that, include: The positive current collector layer is a composite structure formed on an aluminum foil substrate by electric field-assisted selective etching, which consists of a dense conventional layer and a porous functional layer with periodic alternating distribution. The surface of the porous functional layer has an aluminum oxide protective layer. The positive electrode sheet is made by coating the positive current collector layer with a positive active material; Negative electrode plate; Electrolyte; shell; The top cover assembly includes a positive electrode connecting piece, a positive electrode post, a positive electrode top cover, and a sealing structure. The positive electrode connecting piece is connected to the positive electrode current collector by laser welding of the cross-section of the full electrode tab. The bottom cover assembly includes a negative current collector, a negative bottom cover, and a sealing structure. The negative current collector is connected to the negative electrode sheet by laser welding of the end face of the tab.

2. The battery according to claim 1, characterized in that, The dense conventional layer and the porous functional layer of the positive electrode current collector are arranged alternately.

3. A battery according to claim 1, characterized in that, The positive electrode connecting piece is provided with a laser-penetrating welding groove, which is used to achieve a large-area welding connection with the positive electrode current collector.

4. A battery according to claim 1, characterized in that, The negative electrode current collector is provided with an electrode current penetration welding groove, which is used to achieve a large-area welding connection with the negative electrode sheet.

5. A battery according to claim 1, characterized in that, The top cover assembly also includes a filling sealing ring, a positive electrode separator, and an end cap. The end cap has a groove, and the positive electrode separator is embedded in the groove.

6. A method for preparing a battery, characterized in that, Includes the following steps: Step 1: Prepare the composite positive electrode current collector, including: a. Symmetrically attach shielding electrodes with an insulating layer to both sides of the aluminum foil; b. Connect isostatic electrodes and apply an electric field to form a conventional layer in the shielded area; c. Chemical corrosion is carried out under the action of an electric field to form a porous functional layer in the unshielded area; Step 2: Apply high-purity nano-sized aluminum powder, the positive electrode active material, to a designated area of ​​the positive electrode current collector to form an electrode. Then, perform high-voltage formation treatment on the electrode to make a positive electrode sheet. Oxidize the porous functional layer to form a surface aluminum oxide protective layer. Step 3: Assemble the positive electrode, separator, and negative electrode into a battery cell; Step 4: Connect the positive current collector layer of the battery cell to the positive connecting piece in the top cover assembly using laser welding of the cross section of the full-tab; Step 5: Connect the negative electrode plate of the battery cell to the negative current collector in the bottom cover assembly using laser welding on the end face of the tabs; Step 6: Weld the top cover assembly and bottom cover assembly to the outer casing, inject electrolyte, and seal.

7. The method for preparing a battery according to claim 6, characterized in that, In step a, the shielding electrodes are arranged in strips or grids, and the surface insulating layer is aluminum oxide.

8. The manufacturing method according to claim 6, characterized in that, The chemical corrosion in step c uses a mixed acid solvent, which includes one or more of hydrochloric acid, sulfuric acid, and nitric acid.

9. The manufacturing method according to claim 6, characterized in that, The oxidation process in step two further includes oxidizing the electrode in a formation tank using a formation solution and a pulsed high-voltage power supply, followed by heat treatment at 550°C.

10. The manufacturing method according to claim 6, characterized in that, The welding in steps four and five is performed using pulsed laser or continuous laser welding, with a weld depth of 0.5-1.2 mm and a weld width of 0.8-1.5 mm.

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