Lithium secondary battery and method for manufacturing the same

Abstract

The present invention provides a lithium secondary battery and a method for manufacturing the same. [Solution] The lithium battery includes a voltage regulation circuit assembly 1, a plastic frame 2, a first metal case 3, a lithium-ion cell 4, and an insulating outer sheath 5. The lithium-ion cell includes a wound cell assembly, a high-voltage positive electrode cap assembly, and a second metal case. An annular rolling slot is provided on the upper part of the second metal case, dividing the second metal case into a main body and a shrinkable portion. The shrinkable portion of the second metal case is embedded within the first metal case, and the outer surfaces of the first and second metal cases are flush. [Effects] This invention significantly reduces the product defect rate by manufacturing complete and independent lithium-ion cells, then performing chemical formation and capacity grading, and selecting and placing the approved lithium batteries into the first metal case. The first and second metal cases are easy to disassemble, making maintenance convenient.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium batteries, and particularly to lithium secondary batteries and their manufacturing methods.

Background Art

[0002] A low-voltage lithium battery converts the high voltage of a lithium battery to a low voltage of 1.5V through a voltage drop circuit board, is manufactured according to sizes such as AA batteries and AAA batteries, and can replace ordinary alkaline batteries and nickel-metal hydride batteries.

[0003] Chinese Patent Application Publication CN118315645A discloses a step-down lithium battery, but since it adopts the process of performing chemical conversion after packaging, it is inevitable that defective products that do not meet the capacity requirements will occur in the subsequent capacity grading process, and it is impossible to disassemble the lithium battery without destroying it after packaging, and it is difficult to reuse the voltage adjustment circuit assembly with high internal value, leaving room for improvement.

Summary of the Invention

Problems to be Solved by the Invention

[0004] In order to solve the technical problem that existing low-voltage lithium batteries adopt the process of performing chemical conversion after packaging, resulting in the occurrence of defective products in the subsequent capacity grading process, the present invention provides a lithium secondary battery and its manufacturing method.

Means for Solving the Problems

[0005] In one aspect, the present invention provides the following technical solutions. A lithium secondary battery, The device includes a voltage regulation circuit assembly, a plastic frame, a first metal case, a lithium-ion cell, and an insulating sheath, wherein the voltage regulation circuit assembly and the plastic frame are housed within the first metal case, and the plastic frame is used to secure the voltage regulation circuit assembly; the lithium-ion cell includes a wound cell assembly, a high-voltage positive electrode cap assembly, and a second metal case, wherein an annular rolling slot is provided on the upper part of the second metal case, and the wound cell assembly is housed within the second metal case. The first metal case is positioned and restricted by an annular rolling slot, and the second metal case is divided by the annular rolling slot into a lower main body and an upper shrinkable part, the outer diameter of the first metal case is the same as the outer diameter of the main body of the second metal case, the inner diameter of the first metal case is the same as the outer diameter of the shrinkable part of the second metal case, the shrinkable part of the second metal case is embedded in the first metal case, the outer surfaces of the first metal case and the second metal case are flush, and the insulating sheath covers the outside of the first metal case and the second metal case.

[0006] By employing the above technical solution, the voltage regulation circuit assembly of the lithium secondary battery of the present invention is provided with necessary circuits such as a step-down circuit, a voltage stabilization circuit, a charging circuit, and an over-discharge protection circuit, which are electrically connected to the lithium-ion cell. The low-voltage positive electrode cap acts as the positive electrode of the battery, and the second metal case acts as the negative electrode of the battery, thereby enabling a stable output of low voltage.

[0007] This invention provides a method for manufacturing complete and independent lithium-ion cells, then performing chemical formation and capacity grading, selecting the approved lithium cells, and placing them in the first metal case. This solves the technical problem in the prior art of lithium batteries not meeting capacity requirements, significantly reducing the product defect rate. Furthermore, when the shrink portion of the second metal case is embedded in the first metal case and the dimensions are appropriate, the outer wall of the shrink portion of the second metal case and the inner wall of the first metal case fit together tightly, generating a large static friction force that effectively prevents the first and second metal cases from separating. Moreover, the insulating sheath covering the outside of the first and second metal cases further ensures that the first and second metal cases cannot separate, thus guaranteeing the integrity of the lithium battery. If a defect is found during detection, the first and second metal cases can be separated after removing the insulating sheath, making disassembly very easy. If there is a problem with the lithium-ion cell, the lithium-ion cell can be replaced; if there is a problem with the voltage regulation circuit assembly, the voltage regulation circuit assembly can be replaced; and the defective voltage regulation circuit assembly can be reused after maintenance. Of course, electrical performance can be checked before applying the insulating sheath, and the insulating sheath can be applied to lithium batteries that pass the check, thus avoiding unnecessary wear of the insulating sheath.

[0008] Optionally, the first metal case and the second metal case are fixedly connected by spot welding, or the lower edge of the first metal case contracts inward to form a contraction opening, thereby defining the contraction portion of the second metal case.

[0009] Optionally, the voltage regulation circuit assembly includes a low-voltage positive electrode cap, a PCB board, a charging port, a high-voltage positive electrode dome, a negative electrode dome, and elastic ejector pins, the charging port, high-voltage positive electrode dome, negative electrode dome, and elastic ejector pins all mounted on the PCB board, the plastic frame and the low-voltage positive electrode cap are defined by the top wall of a first metal case, a positive / negative electrode gasket is further provided between the low-voltage positive electrode cap and the top wall of the first metal case, and the first metal case has a through portion at the top. A through hole is provided, a first charging escape hole is provided on the side, the low-voltage positive electrode cap protrudes from the through hole, the charging escape hole is used to expose the charging port of the voltage regulation circuit assembly, the elastic ejector pin abuts against the inner wall of the low-voltage positive electrode cap, the negative electrode dome abuts against the inner wall of the first metal case, the high-voltage positive electrode dome abuts against the high-voltage positive electrode cap assembly, the first metal case and the second metal case are conductive in contact, and a second charging escape hole is provided at a corresponding position on the side of the insulating sheath.

[0010] Optionally, the plastic frame includes an attached upper frame and a lower frame, with the PCB board fixed between the upper frame and the lower frame.

[0011] Optionally, the plastic frame is attached to the inner wall of the first metal case via adhesive.

[0012] Optionally, the plastic frame is provided to be movable vertically within the first metal case, and the high-voltage positive electrode dome is further used to bring the plastic frame into contact with the top wall of the first metal case.

[0013] Optionally, the low-pressure positive electrode cap is attached to the plastic frame via adhesive, and the positive and negative electrode gaskets are attached to the plastic frame and the low-pressure positive electrode cap via adhesive.

[0014] Optionally, a protruding vertical guide strip is provided on the outer surface of the plastic frame to reduce frictional force with the inner wall of the first metal case.

[0015] Optionally, the negative electrode dome is provided with an outwardly protruding projection, which contacts the inner wall of the first metal case via the projection, thereby reducing the frictional force with the inner wall of the first metal case.

[0016] In another aspect, further technical solutions provided in this application are as follows: A method for manufacturing the lithium secondary battery, The wound cell assembly is placed inside the second metal case, an annular rolling slot is created in the upper part of the second metal case, the negative electrode tag of the wound cell assembly is welded to the bottom wall of the second metal case, the positive electrode tag is welded to the high-voltage positive electrode cap assembly, electrolyte is injected, the high-voltage positive electrode cap assembly is placed inside the second metal case, a shrinkage section is created in the upper part of the second metal case, and the upper edge of the second metal case Spinning Edge Step S1 involves fabricating a lithium-ion cell by fixing a high-voltage positive electrode cap assembly within the shrink section, and performing chemical conversion and capacity grading on the lithium-ion cell. Step S2 involves fixing the voltage regulation circuit assembly to the plastic frame and then assembling it together into the first metal case. Step S3 involves embedding the upper end of the lithium-ion cell into the first metal case, The process includes step S4, which involves covering the insulating sheath, performing heat shrinkage, and enclosing the insulating sheath around the first metal case and the lithium-ion cell. [Effects of the Invention]

[0017] In summary, this application includes at least one beneficial technical effect: 1. The lithium secondary battery of this invention is equipped with a voltage regulation circuit assembly and can stably output a low voltage. 2. This application can solve the technical problem that the lithium batteries in the prior art do not meet the capacity requirements by manufacturing complete and independent lithium-ion cells, and then performing formation and capacity grading, selecting qualified lithium batteries and placing them in the first metal case, and can greatly reduce the defective rate of products. 3. By the tight fitting of the outer wall of the contraction part of the second metal case and the inner wall of the first metal case, a large static friction force is generated, which can preferably prevent the first metal case and the second metal case from separating, further ensure that the insulating outer skin cannot separate the first metal case and the second metal case, guarantee the integrity of the lithium battery, and make the disassembly of the first metal case and the second metal case very convenient.

Brief Description of the Drawings

[0018] [Figure 1] It is a perspective view of the lithium battery according to Embodiment 1 of this application. [Figure 2] It is a schematic diagram of the semi-sectional structure of the lithium battery according to Embodiment 1 of this application. [Figure 3] It is an enlarged view of part A in FIG. 2. [Figure 4] It is a schematic diagram of the semi-sectional structure of the lithium battery according to Embodiment 1 of this application from another angle. [Figure 5] It is an enlarged view of part B in FIG. 4. [Figure 6] It is a diagram showing the assembly operation of the voltage adjustment circuit assembly and the plastic frame in Embodiment 1 of this application. [Figure 7] It is a diagram showing the assembly operation of incorporating the voltage adjustment circuit assembly and the plastic frame into the first metal case in Embodiment 1 of this application. [Figure 8] It is a diagram showing the assembly operation of incorporating the wound cell assembly into the second metal case in Embodiment 1 of this application. [Figure 9] It is a schematic diagram of manufacturing an annular rolling slot on the top of the second metal case in Embodiment 1 of this application. [Figure 10]This figure shows the assembly operation of incorporating the high-voltage positive electrode cap assembly into the second metal case in Embodiment 1 of the present application. [Figure 11] This is a schematic diagram showing how a shrinkage section is created on the upper part of the second metal case in Embodiment 1 of the present application. [Figure 12] This is a schematic diagram showing how a spinning edge is fabricated on the upper part of the second metal case in Embodiment 1 of the present application. [Figure 13] This figure shows the assembly operation of incorporating the lithium-ion cell into the first metal case in Embodiment 1 of the present application. [Figure 14] This figure shows the assembly operation in Embodiment 1 of the present invention, where an insulating sheath is covered and then heat-shrunk. [Figure 15] This figure shows the assembly process of incorporating the voltage regulation circuit assembly and plastic frame into the first metal case in Embodiment 2 of the present invention. [Figure 16] This is a comparison diagram of the voltage regulation circuit assembly and plastic frame before and after expansion and contraction in Embodiment 2 of the present application. [Figure 17] This is a perspective view of the lithium battery according to Embodiment 3 of the present application. [Figure 18] This is a magnified view of area C in Figure 17 (showing the voltage regulation circuit assembly and plastic frame in a compressed state). [Figure 19] This is a schematic diagram showing how to rotate the charging port to a hidden position. [Figure 20] This figure shows the assembly process of incorporating the voltage regulation circuit assembly and plastic frame into the first metal case in Embodiment 3 of the present invention. [Explanation of Symbols]

[0019] 1. Voltage regulation circuit assembly, 11. Low-voltage positive electrode cap, 12. PCB board, 13. Charging port, 14. High-voltage positive electrode dome, 15. Negative electrode dome, 151. Protrusion, 16. Elastic ejector pin, 17. Positive and negative electrode gaskets, 2. Plastic frame, 21. Upper frame, 22. Lower frame, 23. Vertical guide strip, 24. Annular teeth, 3. First metal case, 31. Through hole, 32. First charging escape hole, 4. Lithium-ion cell, 41. Winding cell assembly, 42. High-voltage positive electrode cap assembly, 43. Second metal case, 431. Annular rolling slot, 432. Main body, 433. Shrinkage part, 434. Spinning Edge 5. Insulating sheath, 51. Second charging escape hole. [Modes for carrying out the invention]

[0020] The present invention will be described in more detail below with reference to Figures 1 to 20.

[0021] Example 1 Referring to Figures 1 to 5, this embodiment discloses a lithium secondary battery comprising a voltage regulation circuit assembly 1, a plastic frame 2, a first metal case 3, a lithium-ion cell 4, and an insulating sheath 5. This embodiment is specifically an AAA battery (size 4 battery), but the present application is not limited to AAA batteries.

[0022] Referring to Figures 4, 6, and 7, the voltage regulation circuit assembly 1 and the plastic frame 2 are housed within a first metal case 3, and the plastic frame 2 is used to secure the voltage regulation circuit assembly 1. The plastic frame 2 includes a fixed upper frame 21 and a lower frame 22, and the PCB board 12 is fixed between the upper frame 21 and the lower frame 22. The plastic frame 2 effectively prevents the PCB board 12 from short-circuiting by contacting the first metal case 3, and also secures the PCB board 12 more firmly, preventing it from changing position.

[0023] Referring to Figure 12, the lithium-ion cell 4 includes a wound cell assembly 41, a high-voltage positive electrode cap assembly 42, and a second metal case 43, wherein an annular rolling slot 431 is provided at the top of the second metal case 43, the wound cell assembly 41 is provided inside the second metal case 43 and its position is restricted by the annular rolling slot 431, and the second metal case 43 is divided by the annular rolling slot 431 into a lower body portion 432 and an upper contracted portion 433.

[0024] Referring to Figures 3, 5, and 13, the outer diameter of the first metal case 3 is the same as the outer diameter of the main body portion 432 of the second metal case 43, the inner diameter of the first metal case 3 is the same as the outer diameter of the shrink portion 433 of the second metal case 43, the shrink portion 433 of the second metal case 43 is embedded in the first metal case 3, the outer surfaces of the first metal case 3 and the second metal case 43 are flush, and the insulating sheath 5 covers the outside of the first metal case 3 and the second metal case 43.

[0025] Referring to Figures 3, 5, and 6, the voltage regulation circuit assembly 1 includes a low-voltage positive electrode cap 11, a PCB board 12, a charging port 13, a high-voltage positive electrode dome 14, a negative electrode dome 15, and elastic ejector pins 16, the charging port 13, the high-voltage positive electrode dome 14, the negative electrode dome 15, and the elastic ejector pins 16 are all provided on the PCB board 12, the plastic frame 2 and the low-voltage positive electrode cap 11 are defined by the top wall of the first metal case 3, a positive / negative electrode gasket 17 is further provided between the low-voltage positive electrode cap 11 and the top wall of the first metal case 3, and the first metal case 3 has a through hole 31 at its top and a first charging escape hole 32 on its side, the low-voltage positive electrode cap 11 protrudes from the through hole 31, the charging escape hole is used to expose the charging port 13 of the voltage adjustment circuit assembly 1, the elastic ejector pin 16 abuts against the inner wall of the low-voltage positive electrode cap 11, the negative electrode dome 15 abuts against the inner wall of the first metal case 3, the high-voltage positive electrode dome 14 abuts against the high-voltage positive electrode cap assembly 42, the first metal case 3 and the second metal case 43 are conductive in contact, and a second charging escape hole 51 is provided at a corresponding position on the side of the insulating sheath 5. The positive and negative electrode gaskets 17 are used to prevent short circuits between the low-voltage positive electrode cap 11 and the first metal case 3 and to ensure electrical safety.

[0026] In this embodiment, since the plastic frame 2 is attached to the inner wall of the first metal case 3 via adhesive, it is possible to prevent the plastic frame 2 from rotating inside the first metal case 3 and to avoid misalignment that would prevent the charging port 13 from being fully exposed.

[0027] The method for manufacturing a lithium secondary battery described in this embodiment is: The wound cell assembly 41 is placed inside the second metal case 43, an annular rolling slot 431 is formed in the upper part of the second metal case 43, the negative electrode tag of the wound cell assembly 41 is welded to the bottom wall of the second metal case 43, the positive electrode tag is welded to the high-voltage positive electrode cap assembly 42, electrolyte is injected, the high-voltage positive electrode cap assembly 42 is placed inside the second metal case 43, a shrinkage section 433 is created in the upper part of the second metal case 43, and the upper edge of the second metal case 43 Spinning Edge Step S1 involves fabricating 434, fixing the high-voltage positive electrode cap assembly 42 within the shrink portion 433 to form a lithium-ion cell 4, and performing chemical conversion and capacity grading on the lithium-ion cell 4. Step S2 involves fixing the voltage regulation circuit assembly 1 to the plastic frame 2 and then assembling it together into the first metal case 3. Step S3 involves embedding the upper end of the lithium-ion cell 4 into the first metal case 3, The process includes step S4, which involves covering the insulating outer sheath 5, performing heat shrinkage, and enclosing the insulating outer sheath 5 in the first metal case 3 and the lithium-ion cell 4.

[0028] The manufacturing method described in this application has a rational process, a high yield, is industrializable, and is particularly suitable for mass production.

[0029] The specific connection principle of the circuit of this invention is as follows: The positive electrode tab of the wound cell assembly 41 is welded to the lower surface of the high-voltage positive electrode cap assembly 42 and connected to the PCB board 12 via the high-voltage positive electrode dome 14; the negative electrode tab of the wound cell assembly 41 is welded to the bottom wall of the second metal case 43 and connected to the PCB board 12 via the second metal case 43, the first metal case 3 and the negative electrode dome 15; after the PCB board 12 is subjected to circuit step-down processing, a low positive electrode voltage is output from the low-voltage positive electrode cap 11 and the negative electrode voltage of the lithium battery is output from the second metal case 43.

[0030] The voltage regulation circuit assembly 1 of the lithium secondary battery of the present invention is provided with necessary circuits such as a step-down circuit, a voltage stabilization circuit, a charging circuit, and an over-discharge protection circuit, and is electrically connected to the lithium-ion cell 4. By using the low-voltage positive electrode cap 11 as the positive electrode of the battery and the second metal case 43 as the negative electrode of the battery, a low voltage can be stably output.

[0031] This invention provides a method for manufacturing complete and independent lithium-ion cells 4, then performing chemical formation and capacity grading, selecting the acceptable lithium cells, and placing them in the first metal case 3. This solves the technical problem in the prior art of lithium batteries not meeting capacity requirements and significantly reduces the product defect rate. When the shrink portion 433 of the second metal case 43 is embedded in the first metal case 3 and the dimensions are appropriate, the outer wall of the shrink portion 433 of the second metal case 43 and the inner wall of the first metal case 3 fit together tightly, generating a large static friction force that effectively prevents the first metal case 3 and the second metal case 43 from separating. Furthermore, the insulating sheath 5 covering the outside of the first metal case 3 and the second metal case 43 further ensures that the first metal case 3 and the second metal case 43 cannot separate, thus guaranteeing the integrity of the lithium battery. If a defect is found during detection, the first metal case 3 and the second metal case 43 can be separated by removing the insulating sheath 5, making disassembly very easy. If there is a problem with the lithium-ion cell 4, the lithium-ion cell 4 can be replaced, and if there is a problem with the voltage regulation circuit assembly 1, the voltage regulation circuit assembly 1 can be replaced. The defective voltage regulation circuit assembly 1 can also be reused after maintenance. Of course, electrical performance pass detection can be performed before applying the insulating sheath 5, and the insulating sheath 5 can be applied to lithium batteries that pass the detection, thus avoiding unnecessary wear of the insulating sheath 5.

[0032] In this embodiment, if further structural strength of the lithium battery case is required, the connection between the first metal case 3 and the second metal case 43 can be strengthened. For example, the first metal case 3 and the second metal case 43 can be fixedly connected by spot welding, or the lower edge of the first metal case 3 can contract inward to form a contraction opening, thereby defining the contraction portion 433 of the second metal case 43. Both methods are feasible, only impair the ease of attachment and detachment, and can be reasonably selected according to the user's usage scenario.

[0033] Example 2 Because the ends of cylindrical batteries must contact the negative electrode elastic element of the external battery chamber to achieve electrical connection, the negative electrode elastic element may deform or the spring may come loose, which can easily lead to poor electrical contact in cylindrical batteries.

[0034] Referring to Figures 15 and 16, Embodiment 2 of the lithium secondary battery of the present invention differs from Embodiment 1 in that the plastic frame 2 is provided so as to be able to move up and down within the first metal case 3, with a movement distance of D, and the high-voltage positive electrode dome 14 is further used to bring the plastic frame 2 into contact with the top wall of the first metal case 3. By increasing the height of the low-voltage positive electrode cap 11 by 1 to 4 mm, the entire lithium battery of the present invention becomes 1 to 4 mm longer than a conventional lithium battery. When installed in the battery chamber, the low-voltage positive electrode cap 11 is compressed and shrinks, so it does not affect the installation of the lithium battery, but the installation effect of the lithium battery becomes tighter, and if the negative electrode elastic element of the battery chamber deforms or loses elasticity, the low-voltage positive electrode cap 11 will shrink only in part or not shrink at all, thereby filling the space where the elasticity of the negative electrode elastic element of the battery chamber is lacking and ensuring good electrical contact.

[0035] In this embodiment, the low-voltage positive electrode cap 11 is attached to the plastic frame 2 via adhesive, and the positive and negative electrode gaskets 17 are attached to the plastic frame 2 and the low-voltage positive electrode cap 11 via adhesive. In this way, the low-voltage positive electrode cap 11, the plastic frame 2, and the entire voltage regulation circuit assembly can move up and down without falling apart.

[0036] Referring to Figure 15, the high-voltage positive electrode dome 14 needs to have an appropriate elasticity, and must have sufficient elasticity to push up the low-voltage positive electrode cap 11, the plastic frame 2, and the voltage adjustment circuit assembly 1, but the elasticity should not be too strong, as too much elasticity can make it difficult to install in the battery compartment. In order for the plastic frame 2 to move freely up and down, and the frictional force with the inner wall of the first metal case 3 must be kept as small as possible. For this reason, the present invention is improved as follows: firstly, a vertical guide strip 23 is provided protruding from the outer surface of the plastic frame 2, which significantly reduces the contact area between the two, thereby reducing the frictional force with the inner wall of the first metal case 3; secondly, a projection 151 is provided on the negative electrode dome 15 that protrudes outward, and the projection 151 contacts the inner wall of the first metal case 3, similarly reducing the contact area between the two, thereby reducing the frictional force with the inner wall of the first metal case 3. Other structures and beneficial effects are the same as in Example 1, so a detailed explanation is omitted here.

[0037] Example 3 Referring to Figures 17 to 20, the difference from Embodiment 2 is that the plastic frame 2 can not only move up and down within the first metal case 3, but can also rotate within the first metal case 3. In this way, when the charging port 13 rotates by a certain angle, it is hidden within the first metal case 3, the appearance of the lithium battery becomes more aesthetically pleasing, the charging port 13 is effectively protected, and safety is improved.

[0038] Referring to Figure 20, the low-voltage positive electrode cap 11 is relatively smooth, small in volume, and not easy to twist manually. Therefore, in this embodiment, an annular tooth 24 is provided on the upper frame 21 of the plastic frame 2, located on the upper edge of the charging port 13. By moving the annular tooth 24, the plastic frame 2 rotates to conceal the charging port 13. Normally, when the low-voltage positive electrode cap 11 is not compressed, the annular tooth 24 is not exposed. However, when the low-voltage positive electrode cap 11 is compressed, the annular tooth 24 moves downward and becomes exposed. At this time, it can be manipulated with a fingernail, toothpick, screwdriver, etc., to expose or conceal the charging port 13, thus achieving the technical effect described above. Other structures and beneficial effects are the same as in Embodiment 2, so a detailed explanation is omitted here.

[0039] The above are all preferred embodiments of the present application and do not limit the scope of protection of the present application. Equivalent changes made by the structure, shape, and principle of the present application are all included within the scope of protection of the present application.

Claims

1. Lithium secondary battery, The device includes a voltage regulation circuit assembly, a plastic frame, a first metal case, a lithium-ion cell, and an insulating sheath, wherein the voltage regulation circuit assembly and the plastic frame are housed within the first metal case, and the plastic frame is used to secure the voltage regulation circuit assembly; the lithium-ion cell includes a wound cell assembly, a high-voltage positive electrode cap assembly, and a second metal case, wherein an annular rolling slot is provided on the upper part of the second metal case, and the wound cell assembly is housed within the second metal case, and the annular A lithium secondary battery characterized in that the position of the first metal case is restricted by an annular rolling slot, the second metal case is divided into a lower main body and an upper shrinkable portion by an annular rolling slot, the outer diameter of the first metal case is the same as the outer diameter of the main body of the second metal case, the inner diameter of the first metal case is the same as the outer diameter of the shrinkable portion of the second metal case, the shrinkable portion of the second metal case is embedded in the first metal case, the outer surfaces of the first metal case and the second metal case are flush, and the insulating sheath covers the outside of the first metal case and the second metal case.

2. The lithium secondary battery according to claim 1, characterized in that the first metal case and the second metal case are fixedly connected by spot welding, or the lower edge of the first metal case shrinks inward to form a shrinkage opening, thereby defining the shrinkage portion of the second metal case.

3. The voltage regulation circuit assembly includes a low-voltage positive electrode cap, a PCB board, a charging port, a high-voltage positive electrode dome, a negative electrode dome, and elastic ejector pins, the charging port, high-voltage positive electrode dome, negative electrode dome, and elastic ejector pins are all provided on the PCB board, the plastic frame and the low-voltage positive electrode cap are defined by the top wall of a first metal case, a positive and negative electrode gasket is further provided between the low-voltage positive electrode cap and the top wall of the first metal case, the first metal case has a through hole at the top and a first charging port on the side A lithium secondary battery according to claim 1, characterized in that a relief hole is provided, the low-voltage positive electrode cap protrudes from the through hole, the charging relief hole is used to expose the charging port of the voltage regulation circuit assembly, the elastic ejector pin abuts against the inner wall of the low-voltage positive electrode cap, the negative electrode dome abuts against the inner wall of the first metal case, the high-voltage positive electrode dome abuts against the high-voltage positive electrode cap assembly, the first metal case and the second metal case are conductive in contact, and a second charging relief hole is provided at a corresponding position on the side of the insulating sheath.

4. The lithium secondary battery according to claim 3, wherein the plastic frame includes an attached upper frame and a lower frame, and the PCB board is fixed between the upper frame and the lower frame.

5. The lithium secondary battery according to claim 3, characterized in that the plastic frame is attached to the inner wall of the first metal case via an adhesive.

6. The lithium secondary battery according to claim 3, wherein the plastic frame is provided so as to be movable up and down within a first metal case, and the high-voltage positive electrode dome is further used to bring the plastic frame into contact with the top wall of the first metal case.

7. The lithium secondary battery according to claim 6, characterized in that the low-voltage positive electrode cap is attached to the plastic frame via an adhesive, and the positive and negative electrode gaskets are attached to the plastic frame and the low-voltage positive electrode cap via an adhesive.

8. The lithium secondary battery according to claim 6, characterized in that a protruding vertical guide strip is provided on the outer circumferential surface of the plastic frame to reduce frictional force with the inner wall of the first metal case.

9. The lithium secondary battery according to claim 6, characterized in that the negative electrode dome is provided with an outwardly protruding projection, which contacts the inner wall of the first metal case via the projection, thereby reducing the frictional force with the inner wall of the first metal case.

10. A method for manufacturing a lithium secondary battery according to any one of claims 1 to 9, Step S1 involves placing a wound cell assembly inside a second metal case, creating an annular rolling slot in the upper part of the second metal case, welding the negative electrode tag of the wound cell assembly to the bottom wall of the second metal case, welding the positive electrode tag to the high-pressure positive electrode cap assembly, injecting electrolyte, placing the high-pressure positive electrode cap assembly inside the second metal case, creating a shrinkage section in the upper part of the second metal case, creating a spinning section on the upper edge of the second metal case, fixing the high-pressure positive electrode cap assembly inside the shrinkage section to form a lithium-ion cell, and performing conversion and capacity grading on the lithium-ion cell. Step S2 involves fixing the voltage regulation circuit assembly to the plastic frame and then assembling it together into the first metal case. Step S3 involves embedding the upper end of the lithium-ion cell into the first metal case, A method for manufacturing a lithium secondary battery, characterized by including step S4 of covering an insulating outer sheath, performing heat shrinkage, and enclosing the insulating outer sheath in a first metal case and a lithium-ion cell.

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