Voltage-reduced lithium battery and manufacturing method thereof

Abstract

To provide a voltage-reduced lithium battery and a manufacturing method thereof, reducing one layer steel shell or soft shell, reducing a material cost, and achieving high strength in connection between a first metal shell and a second metal shell.SOLUTION: There are provided a voltage-reduced lithium battery and a manufacturing method thereof. The voltage-reduced lithium battery includes a circuit assembly 1, a resin frame 2, a wound battery cell assembly 3, a first metal shell 4, a second metal shell 5, an insulating seal 6 and an insulating sheath 7. The circuit assembly and the resin frame are provided in the first metal shell, and the wound battery cell assembly is provided in the second metal shell. The first metal shell and the second metal shell are in vertical butt connection and fixed by circumferential welding. The insulating seal seals the second metal shell, and the insulating sheath covers the first metal shell and the second metal shell. In the present application, an upper end of the second metal shell is completely sealed by the first metal shell and the insulating seal, and an electrolyte can be thus effectively prevented from leaking.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present application relates to the technical field of lithium batteries, and in particular to step-down lithium batteries and methods for manufacturing the same. [Background technology]

[0002] A Chinese patent application with publication number CN208225957U and title "Rechargeable Lithium Battery with Micro USB Interface" discloses a constant-voltage lithium battery in which a constant-voltage protection assembly maintains a constant output voltage while the battery is outputting electrical energy, while simultaneously providing charging protection, discharging protection, overcurrent protection, and short-circuit protection to meet the user's voltage usage needs. In this application, the single lithium battery cells are soft-pack lithium battery cells or hard-shell lithium battery cells, which require an external steel shell, resulting in high costs. The top and bottom covers are ultrasonically welded and then embedded into the steel shell, resulting in low connection strength with the steel shell and susceptibility to damage, leaving room for improvement. Summary of the Invention

[0003] The present invention provides a low-voltage lithium battery and a manufacturing method thereof to solve the technical problems of the conventional low-voltage lithium battery, such as high cost and easy damage.

[0004] In one aspect, the present application provides a step-down lithium battery comprising a circuit assembly, a resin frame, a wound battery cell assembly, a first metal shell, a second metal shell, an insulating seal, and an insulating outer casing, wherein the circuit assembly and the resin frame are disposed within the first metal shell, the resin frame is for fixing the circuit assembly, the wound battery cell assembly is disposed within the second metal shell, the first metal shell and the second metal shell are butted together and fixed by full-circumference welding, the insulating seal is disposed between the first metal shell and the second metal shell and for sealing the second metal shell, and the insulating outer casing is wrapped around the outside of the first metal shell and the second metal shell.

[0005] In this application, by using the above technical solution, the wound battery cell assembly is directly placed inside the second metal shell, and the resin frame and circuit assembly are sealed inside the first metal shell. The upper end of the second metal shell is then completely sealed by the first metal shell and insulating seal. The first and second metal shells are butted together vertically to control the vertical movement range of the wound battery cell assembly. An insulating seal is placed between the first and second metal shells and then fixed by full-circumference welding. The connection between the first and second metal shells is strong, durable, and has good sealing performance, effectively preventing electrolyte leakage. An insulating outer shell covers the welded area, preventing a poor user experience. The resin frame serves as an insulator, preventing unnecessary contact between the circuit assembly and the first metal shell, preventing short circuits, and ensuring electrical safety. By providing only a single steel shell on the exterior of the wound battery cell assembly, the need for a single steel shell or soft shell is eliminated compared to conventional technologies, reducing material costs.

[0006] Preferably, a contracted portion is provided at the lower end of the first metal shell, and a portion of the insulating seal is sandwiched between the contracted portion and the second metal shell.

[0007] Preferably, one or more annular bulges are provided on the outer ring surface of the insulating seal to improve the sealing performance between the insulating seal and the second metal shell, and a horizontal seal portion extends inward from the bottom of the insulating seal, and the horizontal seal portion is attached to the underside of the first metal shell to improve the sealing performance between the insulating seal and the first metal shell.

[0008] Preferably, the bottom wall of the first metal shell has a fastening hole, a metal screw is provided in the fastening hole, and the metal screw is fixed to the fastening hole with a plastic nut. The horizontal seal extends between the metal screw and the bottom wall of the first metal shell to insulate the metal screw from the first metal shell. The metal screw is for sealing the fastening hole. The circuit assembly preferably includes a PCB board, a low-voltage positive cap, a high-voltage positive connecting piece, a low-voltage positive elastic connector, and a negative metal dome, and the low-voltage positive elastic connector, high-voltage positive connecting piece, and negative metal dome are all welded to the PCB board. The negative metal dome is in elastic contact with the first metal shell. The high-voltage positive connecting piece is in elastic contact with an upper end of the metal screw. The positive tab of the wound battery cell assembly is welded to a lower end of the metal screw, and the negative tab is welded to the second metal shell. The low-voltage positive cap is attached to a plastic frame, and the low-voltage positive elastic connector is in elastic contact with the low-voltage positive cap.

[0009] Preferably, the low voltage positive elastic connector is a metal dome, a spring or an elastic thimble.

[0010] Preferably, the circuit assembly further comprises a charging interface, the charging interface is welded to the PCB board, and the first metal shell and the insulating outer cover are both provided with holes at corresponding positions.

[0011] Preferably, the resin frame comprises an upper frame and a lower frame, the upper frame and the lower frame are fixed by a snap fit, and the PCB board is fixed between the upper frame and the lower frame.

[0012] Preferably, the first metal shell has a spinning edge at its upper end for pressing the resin frame inward, and positive and negative electrode insulating sheets are further provided above or below the spinning edge, with a portion of the upper surface of the positive and negative electrode insulating sheets being covered with an insulating outer skin.

[0013] Preferably, the wound battery cell assembly comprises a wound battery cell, an upper insulating sheet, and a lower insulating sheet, the positive electrode tab passes through a central hole in the upper insulating sheet and has an end welded to the lower surface of the rivet connection component, and the negative electrode tab wraps around from the side to the bottom surface of the wound battery cell and has an end welded to the bottom wall of the second metal shell.

[0014] In another aspect, the present application provides a method for manufacturing a method of a medical device comprising: S1: fitting an insulating seal onto the lower end of the first metal shell, and fastening metal screws and resin nuts to fastening holes in the first metal shell; S2: fixing the circuit assembly to a resin frame, and then inserting them into a first metal shell, so that the high-voltage positive connection piece of the circuit assembly is elastically contacted with the metal screw, and the negative metal dome of the circuit assembly is elastically contacted with the first metal shell; S3: placing the low-voltage positive electrode cap in a resin frame, making the low-voltage positive electrode cap elastically contact the low-voltage positive elastic connector, creating a spinning edge on the upper end of the first metal shell, and pressing the resin frame and the low-voltage positive electrode cap into the first metal shell; S4: inserting the wound battery cell assembly into a second metal shell and welding a positive electrode tab of the wound battery cell assembly to a bottom surface of the metal screw; S5: press-fitting the insulating seal and the lower end of the first metal shell into the second metal shell, and performing full-circumferential welding on the first metal shell and the second metal shell; There is further provided a method for manufacturing the above-mentioned step-down lithium battery, including: S6 providing an insulating outer shell, performing heat shrinking, and enclosing the insulating outer shell on the first metal shell and the second metal shell.

[0015] In summary, the present application includes at least one of the following beneficial technical effects:

[0016] 1. In this application, the upper end of the second metal shell is completely sealed by the first metal shell and the insulating seal, resulting in good sealing performance and effectively preventing electrolyte leakage. By providing only one layer of steel shell on the outside of the wound battery cell assembly, the number of steel shells or soft shells required can be reduced compared to the prior art, thereby reducing material costs.

[0017] 2. An insulating seal is provided between the first metal shell and the second metal shell, and then they are fixed by full-circumference welding, so the connection between the first metal shell and the second metal shell is strong and not easily damaged.

[0018] 3. The resin frame plays an insulating role, preventing unnecessary contact between the circuit assembly and the first metal shell, preventing short circuits and ensuring electrical safety. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 1 is a perspective view of the step-down lithium battery according to the embodiment of the present application. [Figure 2] FIG. 2 is a schematic diagram of a half cross-sectional structure of the step-down lithium battery according to an embodiment of the present application. [Figure 3] FIG. 3 is an enlarged view of part A in FIG. [Figure 4] FIG. 4 is a schematic half-sectional structural view of the step-down lithium battery according to the embodiment of the present application taken from another angle. [Figure 5] FIG. 5 is an enlarged view of part B in FIG. [Figure 6] FIG. 6 is a schematic diagram of the overall assembly operation of the step-down lithium battery according to the embodiment of the present application. [Figure 7] FIG. 7 is a schematic diagram of an assembly operation for inserting a wound battery cell assembly into a second metal shell according to an embodiment of the present application. [Figure 8] FIG. 8 is a schematic diagram of an assembly operation in which components such as a circuit assembly and a resin frame are inserted into a first metal shell in an embodiment of the present application. [Figure 9] FIG. 9 is a structural schematic diagram of the circuit assembly in an embodiment of the present application. [Figure 10] FIG. 10 is a structural schematic diagram of the insulating seal in the embodiment of the present application. [Figure 11] FIG. 11 is a structural schematic diagram of sealing the fastening hole with a metal screw according to an embodiment of the present application. [Figure 12] FIG. 12 is a schematic diagram of the operation of welding the positive electrode tab to the metal screw in an embodiment of the present application. [Figure 13] FIG. 13 is a schematic diagram of the operation of inserting the first metal shell and the insulating seal into the second metal shell in the embodiment of the present application. [Figure 14] FIG. 14 is a schematic diagram illustrating the full-circumferential welding of the first metal shell and the second metal shell according to an embodiment of the present application. DETAILED DESCRIPTION OF THE INVENTION

[0020] The present application will now be described in more detail with reference to FIGS.

[0021] 1 to 5, this application discloses a step-down lithium battery, specifically an AAA battery, including a circuit assembly 1, a resin frame 2, a wound battery cell assembly 3, a first metal shell 4, a second metal shell 5, an insulating seal 6, and an insulating outer jacket 7. The circuit assembly 1 and the resin frame 2 are disposed within the first metal shell 4, and the resin frame 2 is used to secure the circuit assembly 1. The wound battery cell assembly 3 is disposed within the second metal shell 5. The first metal shell 4 and the second metal shell 5 are butted together and secured by full-circumference welding. The insulating seal 6 is disposed between the first metal shell 4 and the second metal shell 5 to seal the second metal shell 5. The insulating outer jacket 7 is wrapped around the first metal shell 4 and the second metal shell 5.

[0022] The insulating outer shell 7 is preferably made of a PVC material and is wrapped around the first metal shell 4 and the second metal shell 5 by heat shrinkage, thereby achieving the dual function of insulating and covering the circumferential welded portion 100 .

[0023] 6 and 8, a contracted portion 41 is provided at the bottom end of the first metal shell 4, and a portion of the insulating seal 6 is sandwiched between the contracted portion 41 and the second metal shell 5. The first metal shell 4 and the second metal shell 5 have the same outer diameter, making it impossible to provide an insulating seal 6. However, the provision of the contracted portion 41 allows the insulating seal 6 to be fitted onto the contracted portion 41. After the insulating seal 6 is pressed in, the sealing effect is improved and electrolyte leakage can be effectively prevented. In addition, one or more annular bulges 61 are provided on the outer ring surface of the insulating seal 6 to improve the sealing between the insulating seal 6 and the second metal shell 5. A horizontal seal 62 extends inward from the bottom of the insulating seal 6, and the horizontal seal 62 is attached to the underside of the first metal shell 4 to improve the sealing between the insulating seal 6 and the first metal shell 4.

[0024] In this application, the wound battery cell assembly 3 is directly placed within the second metal shell 5, and the resin frame 2 and circuit assembly 1 are sealed within the first metal shell 4. The first metal shell 4 and the second metal shell 5 are then completely sealed at the top end by the first metal shell 4 and insulating seal 6. The first metal shell 4 and the second metal shell 5 are butted together vertically to control the vertical movement range of the wound battery cell assembly 3. The insulating seal 6 is then placed between the first metal shell 4 and the second metal shell 5 and then secured by full-circumference welding. The connection between the first metal shell 4 and the second metal shell 5 is strong, durable, and has good sealing performance, effectively preventing electrolyte leakage. The insulating outer shell 7 covers the full-circumference weld 100, preventing any impact on the user experience. The resin frame 2 serves as an insulator, preventing unwanted contact between the circuit assembly 1 and the first metal shell 4, preventing short circuits, and ensuring electrical safety. By providing only one layer of steel shell on the outside of the wound battery cell assembly 3, one layer of steel shell or soft shell is eliminated compared to the prior art, and material costs are reduced.

[0025] The Chinese patent application, publication number CN117673498A, entitled "Low-Voltage Lithium Battery," discloses an industrializable low-voltage lithium battery in which, in actual production, a roll groove is first machined into the metal shell, a wound battery cell assembly is fixed inside the metal shell, and then a resin middle frame and circuit assembly are placed inside the metal shell by pulling out the positive tab and welding it to the bottom wall of the inner conductive cap. Due to the constraints of the above processing process, particularly because the upper end of the wound battery assembly is inserted deep into the metal shell, a long positive tab is required. Once the lithium battery is assembled, the positive tab is confined to a narrow space, making it impossible to control its radial position, potentially causing contact with the inner wall of the metal shell and resulting in a serious safety risk.

[0026] 3 and 11, a stopper hole 42 is provided in the bottom wall of the first metal shell 4, a metal screw 8 is provided in the stopper hole 42, and the metal screw 8 is fixed to the stopper hole 42 by a resin nut 9. The horizontal seal portion 62 extends between the metal screw 8 and the bottom wall of the first metal shell 4 and serves to insulate the metal screw 8 from the first metal shell 4. The metal screw 8 is also used to seal the stopper hole 42 so that the electrolyte cannot permeate into the first metal shell 4 through the stopper hole 42.

[0027] 3 and 9, the circuit assembly 1 includes a PCB board 11, a low-voltage positive cap 12, a high-voltage positive connection piece 13, a low-voltage positive elastic connector 14, and a negative metal dome 15, all of which are welded to the PCB board 11. The negative metal dome 15 is in elastic contact with the first metal shell 4, the high-voltage positive connection piece 13 is in elastic contact with the upper end of the metal screw 8, the positive tab 31 of the wound battery cell assembly 3 is welded to the lower end of the metal screw 8, and the negative tab 32 is welded to the second metal shell 5. The low-voltage positive cap 12 is mounted in a resin frame 2, and the low-voltage positive elastic connector 14 is in elastic contact with the low-voltage positive cap 12. The metal screw 8 passes through the fastening hole 42 in the first metal shell 4, is insulated from the first metal shell 4, and, through its own conductivity, electrically connects the high-voltage positive connection piece 13 and the positive tab 31, thereby providing a high-voltage power input to the circuit assembly 1.

[0028] 5 and 8, the charging interface 16 and PCB board 11 are both arranged vertically, and the low-voltage positive electrode cap 12 is placed on the resin frame 2 and is not directly welded to the PCB board 11. Therefore, a low-voltage positive elastic connector 14 is provided on the PCB board 11. The low-voltage positive elastic connector 14 contacts the inner wall of the low-voltage positive electrode cap 12, achieving a low-voltage positive output of 1.5V. The low-voltage positive elastic connector 14 may be a metal dome, a spring, or an elastic thimble.

[0029] 6, the circuit assembly 1 further includes a charging interface 16, specifically a TYPE-C interface, although other standard interfaces may also be used. The charging interface 16 is welded to the PCB board 11. The first metal shell 4 and the insulating outer shell 7 are provided with holes 43 and 71 at corresponding positions. The first metal shell 4 and the second metal shell 5 are used as a common negative electrode.

[0030] 8, the resin frame 2 includes an upper frame 21 and a lower frame 22, which are fixed together by snap fitting, and the PCB board 11 is fixed between the upper frame 21 and the lower frame 22. Of course, the upper frame 21 and the lower frame 22 may be fixed together by other methods, such as ultrasonic welding or adhesive bonding.

[0031] 3 and 5, the first metal shell 4 is provided with a spinning edge 44 at its upper end for pressing the resin frame 2 inward, and the positive and negative electrode insulating sheets 10 are further provided below the spinning edge 44 (the spinning edge 44 may be provided above, as long as the spinning edge 44 and the low-voltage positive electrode cap 12 do not overlap and are not short-circuited), which effectively prevents the positive and negative electrode insulating sheets 10 from coming off, and a portion of the upper surface of the positive and negative electrode insulating sheets 10 is also covered with the insulating outer skin 7, further preventing the positive and negative electrode insulating sheets 10 from coming off.

[0032] 7, the wound battery cell assembly 3 includes a wound battery cell 33, an upper insulating sheet 34, and a lower insulating sheet 35. The positive electrode tab 31 passes through the center hole of the upper insulating sheet 34, and its end is welded to the underside of the metal screw 8. The negative electrode tab 32 is wrapped around the side to the bottom of the wound battery cell 33, and its end is welded to the bottom wall of the second metal shell 5. In the present application, the wound battery cell assembly 33 is directly placed inside the second metal shell 5, which eliminates the need for an additional cover shell and reduces costs compared to the soft-pack or hard-shell lithium battery cells used in the prior art.

[0033] The specific connection principle of the circuit in this application is: the positive electrode tab 31 of the wound battery cell assembly 3 is connected to the PCB board 11 via the metal screw 8 and the high-voltage positive connection piece 13, and the negative electrode tab 32 of the wound battery cell assembly 3 is connected to the PCB board 11 via the second metal shell 5, the first metal shell 4 and the negative metal dome 15. After the circuit voltage step-down process on the PCB board 11, the low-voltage positive electrode cap 12 outputs a 1.5V positive voltage, and the second metal shell 5 outputs the negative electrode of the lithium battery.

[0034] The method for manufacturing the step-down lithium battery of this embodiment is as follows: S1: fitting the insulating seal 6 onto the lower end of the first metal shell 4, and fixing the metal screw 8 and the resin nut 9 to the fastening hole 42 of the first metal shell 4; (S2) fixing the circuit assembly 1 to the resin frame 2, and then inserting them together into the first metal shell 4, so that the high-voltage positive connection piece 13 of the circuit assembly 1 is elastically contacted with the metal screw 8, and the negative metal dome 15 of the circuit assembly 1 is elastically contacted with the first metal shell 4; S3, in which a low-voltage positive electrode cap 12 is placed in a resin frame 2, the low-voltage positive electrode cap 12 is brought into elastic contact with a low-voltage positive elastic connector 14, a positive and negative electrode insulating sheet 10 is attached to the low-voltage positive electrode cap 12, a spinning edge 44 is formed on the upper end of a first metal shell 4, and the resin frame 2, the low-voltage positive electrode cap 12, and the positive and negative electrode insulating sheet 10 are pressed into the first metal shell 4, so that the positive and negative electrode insulating sheet 10 can prevent a short circuit between the spinning edge 44 and the low-voltage positive electrode cap 12; (S4) inserting the wound battery cell assembly 3 into the second metal shell 5 and welding the positive electrode tab 31 of the wound battery cell assembly 3 to the bottom surface of the metal screw 8; S5: press-fitting the insulating seal 6 and the lower end of the first metal shell 4 into the second metal shell 5, and performing full-circumferential welding on the first metal shell 4 and the second metal shell 5; and S6 of covering the insulating outer shell 7, performing heat shrinkage, and enclosing the insulating outer shell 7 in the first metal shell 4 and the second metal shell 5.

[0035] The manufacturing method of the present application has a rational process, a high yield, and is suitable for industrialization and mass production.

[0036] In this application, a first metal shell 4 and a second metal shell 5 are provided, a circuit assembly 1 and a resin frame 2 are provided within the first metal shell 4, and a wound battery cell assembly 3 is provided within the second metal shell 5. Because the upper end of the wound battery cell assembly 3 is located shallowly within the second metal shell 5, the required length of the positive electrode tab 31 is shortened, and although the radial position cannot be controlled, the length is not so long that it would contact the inner wall of the metal shells, preventing a short circuit. In addition, a horizontal seal portion 62 extends inward from the bottom of the insulating seal 6, covering the underside of the first metal shell 4 and preventing the positive electrode tab 31 from contacting the underside of the first metal shell 4, preventing a short circuit. This completely eliminates the risk of a short circuit between the positive electrode tab 31 and the metal shells.

[0037] All of the above are preferred embodiments of the present application, and do not limit the protection scope of the present application, so that any equivalent modifications made based on the structure, shape and principle of the present application shall fall within the protection scope of the present application. [Explanation of symbols]

[0038] 1. Circuit assembly 11. PCB board 12. Low voltage positive cap 13. High voltage positive connection piece 14. Low voltage positive elastic connector 15. Negative electrode metal dome 16. Charging interface 2. Resin frame 21. Upper frame 22, bottom frame 3. Wound battery cell assembly 31. Positive electrode tab 32, negative electrode tab 33. Wound battery cell 34. Upper insulation sheet 35. Lower insulation sheet 4. First metal shell 41, contraction section 42, stopper hole 43. Open hole 44. Spinning Edge 5. Second metal shell 6. Insulation seal 61. Annular bulge 62, horizontal seal part 7. Insulating outer jacket 71. Open hole 8. Metal screws 9. Resin nuts 10. Positive and negative electrode insulating sheet 100, full circumference welded area.

Claims

1. A step-down lithium battery, The battery pack comprises a circuit assembly (1), a resin frame (2), a wound battery cell assembly (3), a first metal shell (4), a second metal shell (5), an insulating seal (6), and an insulating outer skin (7), wherein the circuit assembly (1) and the resin frame (2) are provided within the first metal shell (4), the resin frame (2) is for fixing the circuit assembly (1), the wound battery cell assembly (3) is provided within the second metal shell (5), the first metal shell (4) and the second metal shell (5) are butted together and fixed by full-circumference welding, the insulating seal (6) is provided between the first metal shell (4) and the second metal shell (5) and for sealing the second metal shell (5), and the insulating outer skin (7) is wrapped around the outside of the first metal shell (4) and the second metal shell (5). A step-down lithium battery characterized by:

2. A contracted portion (41) is provided at the lower end of the first metal shell (4), and a portion of the insulating seal (6) is sandwiched between the contracted portion (41) and the second metal shell (5).

2. The step-down lithium battery according to claim 1.

3. The outer annular surface of the insulating seal (6) is provided with one or more annular bulges (61) to improve the sealing performance between the insulating seal (6) and the second metal shell (5), and a horizontal seal portion (62) extends inward from the bottom of the insulating seal (6), and the horizontal seal portion (62) is attached to the underside of the first metal shell (4) to improve the sealing performance between the insulating seal (6) and the first metal shell (4).

3. The step-down lithium battery according to claim 2.

4. A stop hole (42) is provided in the bottom wall of the first metal shell (4), a metal screw (8) is provided in the stop hole (42), the metal screw (8) is fixed to the stop hole (42) by a resin nut (9), the horizontal seal portion (62) extends between the metal screw (8) and the bottom wall of the first metal shell (4) and serves to insulate the metal screw (8) from the first metal shell (4), and the metal screw (8) serves to seal the stop hole (42), The circuit assembly (1) comprises a PCB board (11), a low-voltage positive electrode cap (12), a high-voltage positive connection piece (13), a low-voltage positive elastic connector (14), and a negative electrode metal dome (15), the low-voltage positive elastic connector (14), the high-voltage positive connection piece (13), and the negative electrode metal dome (15) are all welded to the PCB board (11), the negative electrode metal dome (15) is in elastic contact with the first metal shell (4), the high-voltage positive connection piece (13) is in elastic contact with the upper end of the metal screw (8), the positive electrode tab (31) of the wound battery cell assembly (3) is welded to the lower end of the metal screw (8), and the negative electrode tab (32) is welded to the second metal shell (5), the low-voltage positive electrode cap (12) is mounted on a resin frame (2), and the low-voltage positive elastic connector (14) is in elastic contact with the low-voltage positive electrode cap (12).

4. The step-down lithium battery according to claim 3.

5. The low voltage positive elastic connector (14) is a metal dome, a spring or an elastic thimble.

5. The step-down lithium battery according to claim 4.

6. The circuit assembly (1) further comprises a charging interface (16), which is welded to the PCB board (11), and the first metal shell (4) and the insulating outer cover (7) are both provided with holes at corresponding positions.

5. The step-down lithium battery according to claim 4.

7. The resin frame (2) comprises an upper frame (21) and a lower frame (22), the upper frame (21) and the lower frame (22) are fixed by snap fitting, and the PCB board (11) is fixed between the upper frame (21) and the lower frame (22).

5. The step-down lithium battery according to claim 4.

8. The first metal shell (4) has a spinning edge (44) at its upper end for pressing the resin frame (2) inward, and a positive and negative electrode insulating sheet (10) is further provided above or below the spinning edge (44), and a part of the upper surface of the positive and negative electrode insulating sheet (10) is covered with an insulating outer skin (7).

2. The step-down lithium battery according to claim 1.

9. The wound battery cell assembly (3) comprises a wound battery cell (33), an upper insulating sheet (34) and a lower insulating sheet (35), the positive electrode tab (31) passes through the central hole of the upper insulating sheet (34) and its end is welded to the underside of the metal screw (8), and the negative electrode tab (32) is wrapped around the wound battery cell (33) from the side to the bottom and its end is welded to the bottom wall of the second metal shell (5).

5. The step-down lithium battery according to claim 4.

10. A method for manufacturing the step-down lithium battery according to any one of claims 1 to 9, comprising the steps of: S1: fitting an insulating seal (6) onto the lower end of the first metal shell (4) and fixing a metal screw (8) and a resin nut (9) to a fastening hole (42) of the first metal shell (4); S2: fixing the circuit assembly (1) to the resin frame (2), and then inserting them together into the first metal shell (4), so that the high-voltage positive connection piece (13) of the circuit assembly (1) is elastically contacted with the metal screw (8), and the negative metal dome (15) of the circuit assembly (1) is elastically contacted with the first metal shell (4); S3: placing a low-voltage positive electrode cap (12) in a resin frame (2), elastically contacting the low-voltage positive electrode cap (12) with a low-voltage positive elastic connector (14), forming a spinning edge (44) at the upper end of the first metal shell (4), and pressing the resin frame (2) and the low-voltage positive electrode cap (12) into the first metal shell (4); S4: inserting the wound battery cell assembly (3) into the second metal shell (5) and welding the positive electrode tab (31) of the wound battery cell assembly (3) to the bottom surface of the metal screw (8); S5: press-fitting the insulating seal (6) and the lower end of the first metal shell (4) into the second metal shell (5) and performing full-circumferential welding on the first metal shell (4) and the second metal shell (5); and S6 of covering the insulating outer shell (7), performing heat shrinkage, and encasing the insulating outer shell (7) in the first metal shell (4) and the second metal shell (5). A method for manufacturing a step-down lithium battery.

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