Step-down lithium battery and its manufacturing method

Abstract

A step-down lithium battery and a manufacturing method thereof are provided, which eliminates the need for a single steel shell or soft shell, reduces material costs, and increases the strength of the connection between a first metal shell and a second metal shell. [Solution] A step-down lithium battery and its manufacturing method are provided, which 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 cover 7, the circuit assembly and the resin frame are disposed within the first metal shell, the wound battery cell assembly is disposed within the second metal shell, the first metal shell and the second metal shell are butted together vertically and fixed by full-circumference welding, the insulating seal seals the second metal shell, and the insulating outer cover is wrapped around the first metal shell and the second metal shell. In this application, the upper end of the second metal shell is completely sealed by the first metal shell and the insulating seal, effectively preventing electrolyte leakage.

Description

[Technical field]

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

[0002] The 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 during the battery output of electric energy, and at the same time, includes charging protection, discharging protection, overcurrent protection and short circuit protection to meet the voltage usage needs of users. In this application, the single lithium battery cell is a soft-pack lithium battery cell or a hard-shell lithium battery cell, which needs to be further fitted with a steel shell, which is expensive. The top and bottom covers are embedded in the steel shell after being ultrasonically welded, and the connection strength with the steel shell is low and easily damaged, which needs to be improved. Summary of the Invention

[0003] The present invention provides a step-down lithium battery and a method for manufacturing the same, in order to solve the technical problems of the high cost and easy damage of the conventional low-voltage lithium battery.

[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 skin, wherein the circuit assembly and the resin frame are provided within the first metal shell, the resin frame is for fixing the circuit assembly, the wound battery cell assembly is provided within the second metal shell, the first metal shell and the second metal shell are butted together above and below and fixed by full-circumference welding, the insulating seal is provided between the first metal shell and the second metal shell and is for sealing the second metal shell, and the insulating outer skin 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 in the second metal shell, the resin frame and the circuit assembly are sealed in the first metal shell, and then the upper end of the second metal shell is completely sealed by the first metal shell and the insulating seal. The first metal shell and the second metal shell are butted up and down to control the vertical movement range of the wound battery cell assembly. 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 that the connection between the first metal shell and the second metal shell is strong, not easily damaged, has good sealing performance, and can effectively prevent electrolyte leakage. The insulating outer shell covers the welded parts, so that the user experience is not affected. The resin frame plays an isolation role, and can prevent unnecessary contact between the circuit assembly and the first metal shell, prevent short circuits, and ensure electrical safety. By providing only one layer of steel shell on the outside of the wound battery cell assembly, one layer of steel shell or soft shell is reduced compared to the conventional technology, and the material cost is reduced.

[0006] Preferably, a contracted portion is provided at a 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, the outer ring surface of the insulating seal is provided with one or more annular bulges 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, a fastening hole is provided in the bottom wall of the first metal shell, a metal screw is provided in the fastening hole, the metal screw is fixed to the fastening hole by a plastic nut, the horizontal seal portion extends between the metal screw and the bottom wall of the first metal shell to insulate the metal screw from the first metal shell, and the metal screw is for sealing the fastening hole, the circuit assembly includes a PCB board, a low-voltage positive cap, a high-voltage positive connection piece, a low-voltage positive elastic connector, and a negative metal dome, the low-voltage positive elastic connector, the high-voltage positive connection piece, and the 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 connection 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 the lower end of the metal screw, and the negative tab is welded to the second metal shell, the low-voltage positive cap is mounted on 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 an open hole 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 a resin frame inward, positive and negative electrode insulating sheets are further provided above or below the spinning edge, and a portion of the upper surface of the positive and negative electrode insulating sheets is covered by 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 of the upper insulating sheet and has an end welded to the lower surface of the rivet connection part, 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 producing a method for manufacturing a semiconductor device comprising: S1: fitting an insulating seal onto a lower end of a first metal shell, and fixing a metal screw and a resin nut to a fastening hole of the first metal shell; S2: fix the circuit assembly to the resin frame, and then insert them into the first metal shell together, 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 cap in a resin frame, elastically contacting the low-voltage positive cap with the low-voltage positive elastic connector, forming a spinning edge on the upper end of the first metal shell, and pressing the resin frame and the low-voltage positive 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-circumference 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: providing an insulating outer shell, performing heat shrinking, and encasing the insulating outer shell with the first metal shell and the second metal shell S6.

[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, which has good sealing performance and can effectively prevent 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 in the prior art is reduced, and material costs are reduced.

[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. 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 isolation role, preventing unnecessary contact between the circuit assembly and the first metal shell, preventing short circuits, and ensuring electrical safety. [Brief description of the drawings]

[0019] [Figure 1] FIG. 1 is a perspective view of the step-down lithium battery according to an embodiment of the present application. [Diagram 2] FIG. 2 is a schematic half-sectional view of the step-down lithium battery according to an embodiment of the present application. [Diagram 3] FIG. 3 is an enlarged view of part A in FIG. [Figure 4] FIG. 4 is a schematic half-sectional structural diagram of the step-down lithium battery according to the embodiment of the present application from another angle. [Diagram 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 an embodiment of the present application. [Figure 14] FIG. 14 is a schematic diagram of a first metal shell and a second metal shell being fully welded together in an embodiment of the present application. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

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

[0021] 1 to 5, the present application discloses a step-down lithium battery, specifically a AAA battery, comprising 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 cover 7. The circuit assembly 1 and the resin frame 2 are disposed within the first metal shell 4, and the resin frame 2 is for fixing 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 fixed by full circumference welding. The insulating seal 6 is disposed between the first metal shell 4 and the second metal shell 5, and is for sealing the second metal shell 5. The insulating outer cover 7 is wrapped around the outside of the first metal shell 4 and the second metal shell 5.

[0022] The insulating outer jacket 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 shrinking, thereby performing the dual function of insulating and covering the circumferential welded portion 100 .

[0023] 6 and 8, a contraction portion 41 is provided at the lower end of the first metal shell 4, and a part of the insulating seal 6 is sandwiched between the contraction portion 41 and the second metal shell 5. The first metal shell 4 and the second metal shell 5 have the same outer diameter, so that the insulating seal 6 cannot be provided. However, by providing the contraction portion 41, the insulating seal 6 can be fitted onto the contraction portion 41. After the insulating seal 6 is pressed in, the sealing effect is improved and leakage of electrolyte 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 performance between the insulating seal 6 and the second metal shell 5. 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 lower surface of the first metal shell 4 to improve the sealing performance between the insulating seal 6 and the first metal shell 4.

[0024] In this application, the wound battery cell assembly 3 is directly placed in the second metal shell 5, the resin frame 2 and the circuit assembly 1 are sealed in the first metal shell 4, and then the upper end of the second metal shell 5 is completely sealed by the first metal shell 4 and the insulating seal 6. The first metal shell 4 and the second metal shell 5 are butted up and down to control the vertical movement range of the wound battery cell assembly 3. The insulating seal 6 is provided between the first metal shell 4 and the second metal shell 5, and then fixed by full-circumference welding. The connection between the first metal shell 4 and the second metal shell 5 is strong, not easily damaged, has good sealing performance, and can effectively prevent electrolyte leakage. The insulating outer shell 7 covers the full-circumference welding point 100, so as not to affect the user's experience. The resin frame 2 plays the role of isolation, preventing unnecessary 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 with publication number CN117673498A and title "Low-Voltage Lithium Battery" discloses an industrializable low-voltage lithium battery in which, in actual production, a resin middle frame and a circuit assembly can be placed in the metal shell, as long as a roll groove is first processed in the metal shell, a wound battery cell assembly is fixed in the metal shell, and then the positive tab is pulled out and welded to the bottom wall of the inner conductive cap. Due to the constraints of the above processing steps, especially since the upper end of the wound battery assembly is inserted deeply into the metal shell, a long positive tab is required, and when the lithium battery is assembled, the positive tab is restricted in a narrow space and its radial position cannot be controlled, and it may contact the inner wall of the metal shell, causing a short circuit and resulting in serious safety risks.

[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, and the low-voltage positive elastic connector 12, the high-voltage positive connection piece 13, and the negative metal dome 15 are all 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 on 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, providing a high voltage power input to the circuit assembly 1.

[0028] 5 and 8, the charging interface 16 and the PCB board 11 are both vertically arranged, and the low-voltage positive cap 12 is arranged on the resin frame 2 and is not directly welded to the PCB board 11, so that the PCB board 11 is provided with a low-voltage positive elastic connector 14. The low-voltage positive elastic connector 14 contacts the inner wall of the low-voltage positive cap 12, and a low-voltage positive output of 1.5V is realized. 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, which is specifically a TYPE-C interface, and 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 cover 7 are both 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, 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. Of course, the upper frame 21 and the lower frame 22 may be fixed by other methods, such as ultrasonic welding, adhesion with an adhesive, etc.

[0031] 3 and 5, the first metal shell 4 has 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 (they 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 by the insulating outer skin 7, which further prevents 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 an end is welded to the lower surface of the metal screw 8. The negative electrode tab 32 is wound from the side to the bottom of the wound battery cell 33, and an end is welded to the bottom wall of the second metal shell 5. The present application directly places the wound battery cell assembly 33 in the second metal shell 5, which does not require a cover shell and is less costly than the soft-pack lithium battery cell or hard-shell lithium battery cell used in the prior art.

[0033] The specific connection principle of the circuit of 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 step-down process on the PCB board 11, the 1.5V positive electrode voltage is output from the low voltage positive electrode cap 12, and the negative electrode of the lithium battery is output from the second metal shell 5.

[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 into the fastening hole 42 of the first metal shell 4; Fix the circuit assembly 1 to the resin frame 2, and then insert them together into the first metal shell 4, so that the high voltage positive connection piece 13 in the circuit assembly 1 is elastically contacted with the metal screw 8, and the negative metal dome 15 in the circuit assembly 1 is elastically contacted with the first metal shell 4 (S2); S3, in which the low-voltage positive cap 12 is placed in the resin frame 2, the low-voltage positive cap 12 is elastically contacted with the low-voltage positive elastic connector 14, the positive and negative insulating sheet 10 is attached to the low-voltage positive cap 12, a spinning edge 44 is made on the upper end of the first metal shell 4, and the resin frame 2, the low-voltage positive cap 12 and the positive and negative insulating sheet 10 are pressed into the first metal shell 4, and the positive and negative insulating sheet 10 can prevent a short circuit between the spinning edge 44 and the low-voltage positive cap 12; 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 (S4); (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-circumference welding on the first metal shell 4 and the second metal shell 5; and S6 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.

[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 in the first metal shell 4, and a wound battery cell assembly 3 is provided in the second metal shell 5. Since the upper end of the wound battery cell assembly 3 is located in a shallow position in the second metal shell 5, the length required for the positive electrode tab 31 is shortened, and the radial position cannot be controlled, but the length is not long enough to contact the inner wall of the metal shell, so that a short circuit does not occur. In addition, a horizontal seal portion 62 extends inward from the bottom of the insulating seal 6, covering the lower surface of the first metal shell 4 and preventing the positive electrode tab 31 from contacting the lower surface of the first metal shell 4, so that a short circuit does not occur, and thus the risk of a short circuit between the positive electrode tab 31 and the metal shell is thoroughly eliminated.

[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 be included in 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 plus elastic connector 15. Negative electrode metal dome 16. Charging interface 2. Resin frame 21. Upper frame 22, bottom frame 3. Winding 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, stop hole 43. Open hole 44. Spinning Edge 5. Second metal shell 6. Insulation seal 61. Annular bulge 62, horizontal seal part 7. Insulating outer shell 71. Open hole 8. Metal screws 9. Plastic nut 10. Positive and negative electrode insulation sheet 100, all-around 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 cover (7), 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 vertically 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 is for sealing the second metal shell (5), and the insulating outer cover (7) covers the outside of the first metal shell (4) and the second metal shell (5). A step-down lithium battery.

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 insulating seal (6) has one or more annular bulges (61) on its outer annular surface to improve the sealing performance between the insulating seal (6) and the second metal shell (5). The insulating seal (6) has a horizontal seal portion (62) extending radially inward as a bottom portion for the annular bulge (61). The horizontal seal portion (62) is bonded 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 cap (12), a high-voltage positive connection piece (13), a low-voltage positive elastic connector (14) and a negative metal dome (15), the low-voltage positive elastic connector (14), the high-voltage positive connection piece (13) and the negative metal dome (15) are all 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 on a resin frame (2), and the low-voltage positive elastic connector (14) is in elastic contact with the low-voltage positive 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), the charging interface (16) 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 a snap fit, 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. A spinning edge (44) is provided at the upper end of the first metal shell (4) for pressing the resin frame (2) against the inside of the first metal shell (4), 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 by 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 an end is welded to the lower surface of the metal screw (8), and the negative electrode tab (32) is wound from the side to the bottom of the wound battery cell (33) and an 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 producing the step-down lithium battery according to any one of claims 1 to 9, comprising the steps of: Step S1: fitting an insulating seal (6) onto the lower end of the first metal shell (4) and fastening a metal screw (8) and a resin nut (9) to a fastening hole (42) of the first metal shell (4); Step 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); Step S3: placing the low-voltage positive cap (12) in the resin frame (2), elastically contacting the low-voltage positive cap (12) with the low-voltage positive elastic connector (14), creating a spinning edge (44) on the upper end of the first metal shell (4), and pressing the resin frame (2) and the low-voltage positive cap (12) into the first metal shell (4); Step 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); Step 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-circumference welding on the first metal shell (4) and the second metal shell (5); and step 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 producing a step-down lithium battery comprising the steps of:

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