Preparation method of high-safety battery structure and battery structure

Abstract

This invention discloses a method for preparing a high-safety battery structure and the battery structure itself, comprising the following steps: S1, placing an insulating layer between a cover and a pressure plate, assembling it, and then heating it to melt the insulating layer, thereby tightly adhering it to the cover and pressure plate; followed by cooling to fuse the insulating layer with the cover and pressure plate to form a cap assembly; S2, placing an electrode assembly into a housing, and electrically connecting the two electrodes of the electrode assembly to the pressure plate and housing of the cap assembly respectively, obtaining a semi-finished product; S3, placing the semi-finished product in a vacuum environment for baking and dehumidification, during which the pressure in the vacuum environment cycles between vacuum and atmospheric pressure; S4, injecting electrolyte into the housing; S5, welding and sealing the cap assembly to the housing in an environment with a relative humidity of less than 1%. This invention, by connecting the housing and the sidewall of the cap assembly to reduce the wall thickness, increases the volume of the accommodating cavity and the electrolyte filling amount, effectively improving the battery energy density.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and in particular to a method for preparing a high-safety battery structure and the battery structure thereof. Background Technology

[0002] Rechargeable lithium-ion batteries are widely used in handheld electronic devices, such as button batteries in mobile phones and Bluetooth headsets. In smaller, more sophisticated devices, battery volumetric energy density is a key consideration, such as hearing aids, wireless Bluetooth headsets, electronic watches, and endoscopy equipment.

[0003] Traditional button batteries typically use a double-cylinder upper and lower casing, which are overlapped and nested together, with a sealing insulating layer in between. Due to the limited overall volume of the button battery, and the thickness of the upper and lower casings and the sealing insulating layer, the overall size can only be maintained by compressing the battery cavity, thus limiting the battery's energy density. Furthermore, traditional button batteries often use a compression-type semi-sealed method, resulting in poor sealing reliability and risks of leakage, affecting storage performance and lifespan. Under thermal abuse, traditional steel-cased button batteries are prone to explosion due to their structural limitations, posing a serious safety hazard.

[0004] Therefore, improving the battery's sealing reliability and explosion-proof safety while increasing the battery's energy density within a limited volume is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing a high-safety battery structure and the battery structure itself, thereby solving the aforementioned problems in the prior art.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: In a first aspect, the present invention provides a method for preparing a high-safety battery structure, comprising the following steps: S1. Place the insulating layer between the cover and the pressure plate, assemble and heat it to make the insulating layer melt, so that it fits tightly with the cover and the pressure plate. Then cool it to fuse the insulating layer with the cover and the pressure plate to form a cap assembly. S2. Place the electrode assembly into the housing, and electrically connect the two electrodes of the electrode assembly to the pressure plate of the cap assembly and the housing respectively to obtain a semi-finished product; S3. The semi-finished product is placed in a vacuum environment for baking and dehumidification. During the baking process, the pressure in the vacuum environment cycles between a vacuum state and an atmospheric pressure state. The switch from a vacuum state to an atmospheric pressure state is achieved by filling the vacuum environment with dry gas. S4. Inject electrolyte into the housing; S5. In an environment with a relative humidity of less than 1%, the cap assembly is welded and sealed to the housing to complete the preparation of the battery structure.

[0007] Furthermore, in step S1, the heating causes the insulating layer to reach a melting temperature of 150±20°C.

[0008] Furthermore, in step S3, the baking time is 10 hours, the vacuum pressure is 30±10Pa, and the time interval between cycle switching is 1 hour.

[0009] Furthermore, in step S5, the welding is laser welding.

[0010] Furthermore, the insulating layer is made of three layers of polypropylene material.

[0011] Furthermore, both the cover and the pressure plate are made of metal.

[0012] Secondly, the present invention also provides a high-safety battery structure, which is prepared by the method for preparing the high-safety battery structure.

[0013] Furthermore, the cover has an opening, and the pressure plate has a boss that extends out of the opening.

[0014] Furthermore, the housing has an upper end face, the cover extends with a connecting wall, the connecting wall has a lower end face, and the upper end face is connected to the lower end face.

[0015] Furthermore, the insulating layer is an insulating ring, the width of which is greater than the overlap width of the pressure plate and the cover, and the overlap width of the pressure plate and the cover is 0.5mm-10mm.

[0016] Compared with the prior art, the beneficial technical effects of the present invention are as follows: The high-safety battery structure fabrication method and battery structure of this invention, by butt-welding the shell and cap assembly on the sidewalls, effectively reduces the sidewall thickness compared to the multi-layer overlapping structure of traditional button batteries. This increases the volume of the internal cavity of the shell, increases the electrolyte filling amount, and significantly improves the battery's energy density, solving the technical problem of difficulty in increasing energy density within a limited volume. The cap assembly employs a melt-cooling integrated process, placing the insulating layer between the cap and the pressure plate. Heating the insulating layer until it reaches a molten state, tightly adhering it to the metal cap and pressure plate, and then cooling it to fuse it into one piece. This integrated structure eliminates the interface defects present in traditional extrusion sealing or adhesive sealing, significantly improving sealing reliability. When the battery's internal temperature rises due to abnormal conditions such as thermal abuse, the insulating layer will melt again, forming an irreversible physical gap between the cover and the pressure plate, allowing the internal gas to be released, thus achieving active and irreversible explosion-proof pressure relief. At the same time, a dynamic pressure cycle baking process is used before electrolyte injection, placing the semi-finished product in a vacuum environment, with the pressure cycling between vacuum and atmospheric pressure. When switching from vacuum to atmospheric pressure, dry gas is introduced to achieve rapid pressurization. This process can more thoroughly remove moisture from the battery, effectively avoiding electrolyte decomposition and electrode corrosion. After electrolyte injection, laser welding is performed in an ultra-dry environment with a relative humidity of less than 1%, minimizing the impact of moisture on the sealing interface. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic flowchart of the preparation method of the high-safety battery structure in Embodiment 1 of the present invention; Figure 2 This is a three-dimensional structural diagram of the high-safety battery structure of Embodiment 2 of the present invention; Figure 3 This is a cross-sectional view of the high-safety battery structure of Embodiment 2 of the present invention; Figure 4 This is an exploded view of the high-safety battery structure of Embodiment 2 of the present invention.

[0019] Explanation of reference numerals in the attached drawings: 10, housing; 11, receiving cavity; 12, upper end face; 20, cap assembly; 21, cover; 211, opening; 212, connecting wall; 22, pressure plate; 221, boss; 23, insulating layer; 30, electrode assembly; 31, positive electrode; 32, negative electrode. Detailed Implementation

[0020] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0021] In the description of this invention, it should be understood that the terms "length," "width," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and 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, and therefore should not be construed as a limitation 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 or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0022] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral 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 according to the specific circumstances.

[0023] The technical solutions provided by the various embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0024] Example 1 like Figure 1 As shown, the preparation method of the high-safety battery structure in this embodiment 1 includes the following steps: S1. Place the insulating layer between the cover and the pressure plate, assemble and heat it to make the insulating layer melt, so that it fits tightly with the cover and the pressure plate. Then cool it to fuse the insulating layer with the cover and the pressure plate to form a cap assembly.

[0025] In one embodiment, as needed, a cover, pressure plate, and housing are pre-stamped using a mold for later use; a sheet-like insulating layer of sealing insulating adhesive is made using a mold of the appropriate shape for later use; and electrode assemblies of the appropriate shape and size are made for later use as needed.

[0026] Specifically, the prepared insulating layer is placed between the cover and the pressure plate, the cover and the pressure plate are then assembled, and finally combined together using jigs and other means to form a cap assembly.

[0027] The specific process parameters are set as shown in Table 1: Table 1

[0028] S2. Place the electrode assembly into the housing, and electrically connect the two electrodes of the electrode assembly to the pressure plate of the cap assembly and the housing respectively to obtain a semi-finished product.

[0029] Specifically, the electrode assembly is placed in the housing, with the positive electrode electrically connected to the boss and the negative electrode electrically connected to the housing.

[0030] Electrical connections are made using resistance welding or laser welding.

[0031] Specifically, the parameters for resistance welding are shown in Table 2: Table 2

[0032] S3. The semi-finished product is placed in a vacuum environment for baking and dehumidification. During the baking process, the pressure in the vacuum environment cycles between vacuum and atmospheric pressure. The switch from vacuum to atmospheric pressure is achieved by filling the vacuum environment with dry gas.

[0033] The specific parameters are shown in Table 3: Table 3

[0034] S4. Inject electrolyte into the casing.

[0035] S5. In an environment with a relative humidity of less than 1%, weld the cap assembly to the casing to seal it, thereby completing the preparation of the battery structure.

[0036] Specifically, laser welding is used to weld the contact surfaces of the cover and the shell in an environment with a relative humidity of less than 1% to complete the battery encapsulation.

[0037] The parameters for laser welding are shown in Table 4: Table 4

[0038] Specifically, after S4, the process also includes: activation, formation, and capacity testing of the welded battery to complete battery manufacturing. Activation refers to allowing the battery cells to fully saturate with electrolyte after injection; formation refers to pre-charging the battery to activate it; and capacity testing refers to testing the battery's capacity.

[0039] Table 5 shows a performance comparison between the battery prepared using this invention and a traditional button battery: Table 5

[0040] The high-safety battery structure preparation method of this embodiment 1 involves placing an insulating layer between the cover and the pressure plate, then assembling, heating, and cooling the cover and the pressure plate to form a cap assembly. The two electrodes of the electrode assembly are then electrically connected to the cap assembly and the housing, respectively. Finally, electrolyte is injected into the housing, and the cap assembly and the housing are welded and sealed to complete the battery structure preparation. Compared to the multi-layered sidewalls of traditional button batteries, this method reduces the wall thickness and effectively increases the volume of the cavity, thereby increasing the electrolyte filling amount and effectively improving the battery energy density.

[0041] Example 2 like Figures 2 to 4 As shown, the high-safety battery structure of this embodiment 2 is prepared by the preparation method of the high-safety battery structure described above. Specifically, it includes a housing 10, a cap assembly 20 and an electrode assembly 30. The housing 10 has a receiving cavity 11, and the electrode assembly 30 is placed in the receiving cavity 11. The receiving cavity 11 is also filled with electrolyte (not shown in the figure). The electrode assembly 30 has two electrodes, one of which is electrically connected to the cap assembly 20 and the other electrode is electrically connected to the housing 10. The housing 10 and the cap assembly 20 are connected to the side wall after being combined.

[0042] In one embodiment, the electrode includes a positive electrode 31 and a negative electrode 32, wherein the positive electrode 31 is electrically connected to the cap assembly 20 or the housing 10, and the negative electrode 32 is electrically connected to the housing 10 or the cap assembly 20. Preferably, the positive electrode 31 is electrically connected to the cap assembly 20, and the negative electrode 32 is electrically connected to the housing 10.

[0043] In this embodiment 2, the battery structure has a receiving cavity 11 inside the housing 10, and the electrode assembly 30 is placed in the receiving cavity 11. The receiving cavity 11 is also filled with electrolyte. The electrode assembly 30 has two electrodes, one of which is electrically connected to the cap assembly 20, and the other electrode is electrically connected to the housing 10. The housing 10 and the cap assembly 20 are connected at the side wall after being combined to achieve a seal. Compared with the multi-layered side walls of traditional button batteries, the wall thickness is reduced, which can effectively increase the volume of the receiving cavity 11 to increase the amount of electrolyte filling, thereby effectively improving the battery energy density.

[0044] Specifically, the electrolyte uses existing technology, which will not be described in detail here.

[0045] In one embodiment, the cap assembly 20 includes a cap body 21, a pressure plate 22, and an insulating layer 23. The insulating layer 23 is located between the cap body 21 and the pressure plate 22. The cap body 21 has an opening 211, and the pressure plate 22 has a boss 221 that extends out of the opening 211. The housing 10 is connected to the cap body 21.

[0046] Specifically, an insulating layer 23 is disposed between the cover 21 and the pressure plate 22 to provide insulation and sealing. Both the cover 21 and the pressure plate 22 are made of metal. The cover 21, pressure plate 22, and insulating layer 23 are heated by high-frequency induction heating, causing the insulating layer 23 to melt and adhere tightly to the cover 21 and pressure plate 22. After cooling, they fuse together, resulting in excellent sealing and insulation. In other embodiments, a heating block or heating device can be used to heat the cap assembly 20 at a constant temperature to achieve the same effect, or a combination of the two heating methods can be used.

[0047] Preferably, both the cover 21 and the pressure plate 22 are made of stainless steel, which has high strength and good corrosion resistance.

[0048] Furthermore, in practical applications, when high temperatures are generated inside the battery structure, the insulating layer 23 reaches a molten state, and a gap is formed between the cover 21 and the pressure plate 22. The gas inside the battery structure flows out along the gap, reducing the possibility of explosion and achieving an explosion-proof effect.

[0049] In one embodiment, the housing 10 has an upper end face 12, the cover 21 extends with a connecting wall 212, the connecting wall 212 has a lower end face (not shown in the figure), and the upper end face 12 is connected to the lower end face.

[0050] Specifically, the cover 21 extends with a connecting wall 212, which has a lower end face. The upper end face 12 is connected to the lower end face, and the connecting wall 212 and the shell 10 form a good weld line. The upper end face 12 and the lower end face are welded together to achieve a sealed connection. This battery structure is laser welded from the side, which can effectively improve the yield. Preferably, butt welding is used to increase the volume of the battery cavity 11. The welding is done by laser, and the specific welding parameters are as follows: welding current is 15-50A, pulse width is 0.5-5ms, frequency / duty cycle is 40 / 50%, start-up speed is 10-25mm / s, processing speed is 5-200mm / s, acceleration is 5-20mm / s², and spot diameter is 0.1-0.5mm.

[0051] In one embodiment, the thickness of the connecting wall 212 is the same as the thickness of the housing 10, so that the contact surfaces of the two are aligned, thereby improving the welding effect between the cover 21 and the housing 10 and the sealing effect.

[0052] In one embodiment, the specific thickness of the housing 10 can be set as needed and is not specifically limited here. Preferably, the thickness of the housing 10 is 0.1mm-0.25mm.

[0053] In one embodiment, the insulating layer 23 is an insulating ring, the width of which is greater than the overlap width of the pressure plate 22 and the cover 21.

[0054] Specifically, the insulating ring is designed as an annular shape that fits into the cover 21 and the pressure plate 22. The width of the insulating ring is greater than the overlap width of the pressure plate 22 and the cover 21 to achieve good insulation. In addition, the insulating ring cannot cover the area of ​​the boss 221.

[0055] Preferably, the insulating layer 23 is made of three layers of polypropylene material, which has good insulation and sealing properties.

[0056] In one embodiment, the overlap width between the pressure plate 22 and the cover 21 is 0.5mm-10mm, and the overlap width is the width of the battery sealing line.

[0057] Specifically, the thickness of the overlap width between the pressure plate 22 and the cover 21 can be set as needed and is not specifically limited here. Preferably, the overlap width is 0.5mm-10mm.

[0058] In one embodiment, the housing 10 is cylindrical, and its cross-section is circular, elliptical, square, or heart-shaped, etc., to be applied to different scenarios.

[0059] In one embodiment, the electrodes include a positive electrode 31 and a negative electrode 32, the positive electrode 31 being made of aluminum foil and the negative electrode 32 being made of copper foil.

[0060] Specifically, the positive electrode 31 and the negative electrode 32 are separated by a battery separator, and the electrode assembly 30 is formed by spiral winding or stacking. The electrode assembly 30 realizes the energy storage function. Here, the battery separator refers to a thin film made of plastics such as polypropylene.

[0061] Specifically, an active material is uniformly coated on both sides of an aluminum foil with a thickness of 0.016-0.06 mm as the positive electrode 31. An active material is uniformly coated on both sides of a copper foil with a thickness of 0.012-0.06 mm as the negative electrode 32. The active material includes lithium cobalt oxide, lithium titanate, or graphite, etc. Lithium cobalt oxide and lithium titanate are used for the positive electrode 31, and graphite is used for the negative electrode 32.

[0062] Preferably, the positive electrode 31 is electrically connected to the boss 221, and the negative electrode 32 is electrically connected to the bottom of the housing 10 to form an electrical cycle. The boss 221 is used to output electrical energy to the outside.

[0063] The high-safety battery structure of this embodiment 2 has the characteristics of low manufacturing cost and good sealing performance, while it can increase the volume of the battery cavity and can also have a variety of shapes.

[0064] The high-safety battery structure fabrication method and battery structure of this invention, by butt-welding the shell and cap assembly on the sidewalls, effectively reduces the sidewall thickness compared to the multi-layer overlapping structure of traditional button batteries. This increases the volume of the internal cavity of the shell, increases the electrolyte filling amount, and significantly improves the battery's energy density, solving the technical problem of difficulty in increasing energy density within a limited volume. The cap assembly employs a melt-cooling integrated process, placing the insulating layer between the cap and the pressure plate. Heating the insulating layer until it reaches a molten state, tightly adhering it to the metal cap and pressure plate, and then cooling it to fuse it into one piece. This integrated structure eliminates the interface defects present in traditional extrusion sealing or adhesive sealing, significantly improving sealing reliability. When the battery's internal temperature rises due to abnormal conditions such as thermal abuse, the insulating layer will melt again, forming an irreversible physical gap between the cover and the pressure plate, allowing the internal gas to be released, thus achieving active and irreversible explosion-proof pressure relief. At the same time, a dynamic pressure cycle baking process is used before electrolyte injection, placing the semi-finished product in a vacuum environment, with the pressure cycling between vacuum and atmospheric pressure. When switching from vacuum to atmospheric pressure, dry gas is introduced to achieve rapid pressurization. This process can more thoroughly remove moisture from the battery, effectively avoiding electrolyte decomposition and electrode corrosion. After electrolyte injection, laser welding is performed in an ultra-dry environment with a relative humidity of less than 1%, minimizing the impact of moisture on the sealing interface.

[0065] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for preparing a high-safety battery structure, characterized in that, Includes the following steps: S1. Place the insulating layer between the cover and the pressure plate, assemble and heat it to make the insulating layer melt, so that it fits tightly with the cover and the pressure plate. Then cool it to fuse the insulating layer with the cover and the pressure plate to form a cap assembly. S2. Place the electrode assembly into the housing, and electrically connect the two electrodes of the electrode assembly to the pressure plate of the cap assembly and the housing respectively to obtain a semi-finished product; S3. The semi-finished product is placed in a vacuum environment for baking and dehumidification. During the baking process, the pressure in the vacuum environment cycles between a vacuum state and an atmospheric pressure state. The switch from a vacuum state to an atmospheric pressure state is achieved by filling the vacuum environment with dry gas. S4. Inject electrolyte into the housing; S5. In an environment with a relative humidity of less than 1%, the cap assembly is welded and sealed to the housing to complete the preparation of the battery structure.

2. The method for preparing the high-safety battery structure according to claim 1, characterized in that, In step S1, the heating causes the insulating layer to reach a melting temperature of 150±20℃.

3. The method for preparing the high-safety battery structure according to claim 1, characterized in that, In step S3, the baking time is 10 hours, the vacuum pressure is 30±10Pa, and the time interval between cycle switching is 1 hour.

4. The method for preparing the high-safety battery structure according to claim 1, characterized in that, In step S5, the welding is laser welding.

5. The method for preparing the high-safety battery structure according to claim 1, characterized in that, The insulating layer is made of three layers of polypropylene material.

6. The method for preparing a high-safety battery structure according to any one of claims 1-5, characterized in that, Both the cover and the pressure plate are made of metal.

7. A high-safety battery structure, characterized in that, The high-safety battery structure is prepared by any one of claims 1-6.

8. The high-safety battery structure according to claim 7, characterized in that, The cover has an opening, and the pressure plate has a boss that extends out of the opening.

9. The high-safety battery structure according to claim 7, characterized in that, The shell has an upper end face, the cover extends with a connecting wall, the connecting wall has a lower end face, and the upper end face is connected to the lower end face.

10. The high-safety battery structure according to claim 7, characterized in that, The insulating layer is an insulating ring, the width of which is greater than the overlap width of the pressure plate and the cover, and the overlap width of the pressure plate and the cover is 0.5mm-10mm.

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