Low-voltage lithium battery

Abstract

The present application relates to a low-voltage lithium battery, comprising: a circuit assembly, a plastic middle frame, a wound cell assembly, a metal housing, and an insulating outer sheath. The circuit assembly comprises a PCB, an outer conductive cap, and an inner conductive cap. A positive electrode copper ring and a negative electrode copper ring are arranged on the front side of the PCB. The positive electrode copper ring is electrically connected to the outer conductive cap, and the negative electrode copper ring is electrically connected to the metal housing. A high-voltage input copper ring is arranged on the back side of the PCB, and is electrically connected to the inner conductive cap. A positive tab of the wound cell assembly is electrically connected to the inner conductive cap, and a negative tab of the wound cell assembly is electrically connected to the metal housing. By providing the positive electrode copper ring, the negative electrode copper ring, and the high-voltage input copper ring on the PCB, the electrical connection between the wound cell assembly and the PCB and the electrical connection between a low-voltage output element and the PCB can be achieved without the use of conductive wires, improving the stability of electrical performance, simplifying the internal connection structure of the lithium battery, enhancing safety, and enabling industrialized production.

Description

A low-voltage lithium battery Technical Field

[0001] The present application relates to the technical field of lithium batteries, and in particular to a low-voltage lithium battery. Background Art

[0002] In a Chinese patent application with publication number CN203787480U and titled “A Variable Voltage Cylindrical Battery Device,” a low-voltage lithium battery is disclosed. The high voltage (3.0-4.2V) of the lithium battery is converted to a low voltage of 1.5V through a voltage drop circuit board, thereby replacing common alkaline batteries and nickel-metal hydride batteries. It can be manufactured in sizes such as AA batteries and AA batteries and can be widely used in various devices such as remote controls, electric toys, electric toothbrushes, shavers, wireless microphones, doorbells, etc. Lithium batteries have the advantages of no memory effect, high energy density, and long service life. Their versatility is greatly improved after the voltage drop. However, the structure provided in this application is unreasonable, and the stability of the electrical performance is not high. It can only be regarded as a conceptual innovation and is difficult to industrialize.

[0003] A Chinese patent application with publication number CN204966611U, titled "A 1.5V Constant Voltage Lithium-ion Battery," discloses a step-down circuit that can constantly output a low voltage of 1.5V and achieve the same-port charge and discharge function. However, the specific assembly structure is not disclosed in detail, making it difficult to industrialize.

[0004] Summary of the Invention

[0005] In order to solve the technical problems of the industrialization of existing low-voltage lithium batteries, the present invention provides a low-voltage lithium battery.

[0006] The technical solution provided in this application is as follows: A low-voltage lithium battery, comprising a circuit assembly, a plastic middle frame, a wound cell assembly, a metal shell and an insulating outer skin, wherein the circuit assembly, the plastic middle frame and the wound cell assembly are arranged in the metal shell in sequence from top to bottom, and the insulating outer skin is covered on the outside of the metal shell, the circuit assembly comprises a PCB board, an outer conductive cap and an inner conductive cap, the front of the PCB board is provided with a positive copper ring and a negative copper ring, the positive copper ring is electrically connected to the outer conductive cap, and the negative copper ring is electrically connected to the metal shell, the back of the PCB board is provided with a high-voltage input copper ring, the high-voltage input copper ring is electrically connected to the inner conductive cap, the positive pole ear of the wound cell assembly is electrically connected to the inner conductive cap, and the negative pole ear is electrically connected to the metal shell.

[0007] The PCB board in the circuit assembly of the present application is also provided with necessary circuits such as a step-down circuit, a voltage stabilizing circuit, a charging circuit, and an over-discharge protection circuit. The outer conductive cap serves as the positive electrode of the battery, and the metal shell serves as the negative electrode of the battery, which can stably output a low voltage and realize the same-port charging and discharging function. At the same time, an outer conductive cap and an inner conductive cap are provided. By providing a positive copper ring, a negative copper ring, and a high-voltage input copper ring on the PCB board, the circuit connection between the wound battery cell assembly and the PCB board, and the circuit connection between the low-voltage output element and the PCB board are realized. No conductive cables are used, the electrical performance is more stable, and the internal connection structure of the lithium battery is simplified, which is less prone to problems, safer, and can be industrialized and mass-produced.

[0008] Preferably, a rolling groove is provided inwardly on the upper portion of the metal shell to limit the movement of the wound battery core assembly in the metal shell and also to support the plastic middle frame.

[0009] Preferably, the metal shell is provided with a spun edge inwardly for pressing the plastic middle frame, and positive and negative electrode separators are also pasted above the spun edge, and the upper surface of the positive and negative electrode separators is also wrapped by an insulating outer skin.

[0010] Preferably, the inner wall of the plastic middle frame is provided with a flange edge for supporting the PCB board.

[0011] Preferably, a potting compound is provided between the inner conductive cap and the plastic middle frame to form a seal to isolate the electrolyte.

[0012] Preferably, the circuit assembly further includes an elastic ring, which includes a base ring and lift tabs evenly distributed around the base ring. The back of the base ring is welded to the negative copper ring through a patch, and the lift tabs are elastically crimped to the spun edge of the metal shell.

[0013] Preferably, the outer conductive cap and the inner conductive cap are both soldered on the PCB board through patch welding.

[0014] Preferably, the electronic components on the PCB are centrally arranged inside the outer conductive cap and the inner conductive cap.

[0015] Preferably, the wound battery cell assembly includes a wound battery cell, an upper separator and a lower separator, the positive electrode tab passes through the center hole of the upper separator, and the end is welded to the lower surface of the inner conductive cap; the negative electrode tab is wound from the side of the wound battery cell to the bottom surface, and the end is welded to the bottom wall of the metal shell.

[0016] In summary, this application includes at least one of the following beneficial technical effects:

[0017] 1. The PCB board in the circuit assembly of this application is also equipped with necessary circuits such as a step-down circuit, a voltage stabilization circuit, a charging circuit, and an over-discharge protection circuit. The external conductive cap serves as the positive electrode of the battery, and the metal casing serves as the negative electrode of the battery. It can stably output low voltage and realize the same-port charging and discharging function.

[0018] 2. This application is equipped with an outer conductive cap and an inner conductive cap, and a positive copper ring, a negative copper ring, and a high-voltage input copper ring are set on the PCB board. No conductive cables are used, and the electrical performance is more stable;

[0019] 3. This application simplifies the internal connection structure of lithium batteries, making them less prone to problems, safer, and capable of industrialization and large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] FIG1 is a perspective view of a low-voltage lithium battery according to an embodiment of the present application;

[0021] FIG2 is a schematic diagram of a half-section structure of a low-voltage lithium battery according to an embodiment of the present application;

[0022] Figure 3 is an enlarged view of point A in Figure 2;

[0023] Figure 4 is an enlarged view of point B in Figure 2;

[0024] FIG5 is a front perspective view of the PCB board according to an embodiment of the present application;

[0025] FIG6 is a perspective view of the back side of the PCB board according to an embodiment of the present application;

[0026] FIG7 is a perspective view of a wound battery cell assembly according to an embodiment of the present application;

[0027] FIG8 is a schematic diagram of the assembly of the circuit assembly according to an embodiment of the present application;

[0028] FIG9 is a schematic diagram of the assembly of the circuit assembly and the plastic middle frame according to an embodiment of the present application;

[0029] FIG10 is a front perspective view of the assembled circuit assembly and the plastic middle frame according to an embodiment of the present application;

[0030] FIG11 is a rear perspective view of the assembled circuit assembly and the plastic middle frame according to an embodiment of the present application;

[0031] FIG12 is a schematic diagram of the circuit assembly and the plastic middle frame after glue is dispensed in an embodiment of the present application.

[0032] Explanation of the accompanying reference numerals: 1. Circuit assembly; 11. PCB board; 111. Positive copper ring; 112. Negative copper ring; 113. High-voltage input copper ring; 12. Outer conductive cap; 13. Inner conductive cap; 14. Elastic ring; 141. Base ring; 142. Warping piece; 2. Plastic middle frame; 21. Flange edge; 3. Wound battery cell assembly; 31. Positive electrode tab; 32. Negative electrode tab; 33. Wound battery cell; 34. Upper separator; 35. Lower separator; 4. Metal shell; 41. Rolling groove; 42. Spinning edge; 5. Insulating outer skin; 6. Positive and negative separators; 7. Potting glue; 100. Spinning knife. DETAILED DESCRIPTION

[0033] The present application is further described in detail below with reference to Figures 1-12.

[0034] Referring to Figures 1 to 4, an embodiment of the present application discloses a low-voltage lithium battery, comprising a circuit assembly 1, a plastic middle frame 2, a wound cell assembly 3, a metal casing 4, and an insulating outer shell 5. The circuit assembly 1, plastic middle frame 2, and wound cell assembly 3 are sequentially arranged from top to bottom within the metal casing 4, with the insulating outer shell 5 covering the outside of the metal casing 4. The circuit assembly 1 comprises a PCB 11, an outer conductive cap 12, and an inner conductive cap 13. The front of the PCB 11 is provided with a positive copper ring 111 and a negative copper ring 112. The positive copper ring 111 is electrically connected to the outer conductive cap 12, and the negative copper ring 112 is electrically connected to the metal casing 4. The back of the PCB 11 is provided with a high-voltage input copper ring 113, which is electrically connected to the inner conductive cap 13. The positive electrode tab 31 of the wound cell assembly 3 is electrically connected to the inner conductive cap 13, and the negative electrode tab 32 is electrically connected to the metal casing 4.

[0035] In this embodiment, the wound battery cell assembly 3 can select the common ternary wound battery cell assembly or iron phosphate wound battery cell assembly on the market. Of course, other types of wound battery cell assemblies can also be selected. The voltage range is between 3.0-4.2V. After the voltage drop through the PCB board 11, it is preferably output 1.5V. Other voltage values ​​can also be output according to actual needs, such as 1.2V, 2.0V, etc. Since the various functional circuits on the PCB board 11 are already existing technologies, this application has no substantial improvement on this, so it will not be described in detail here. The insulating outer skin 5 of this application is preferably PVC material, which has the characteristics of heat shrinkage and can be tightly wrapped around the metal shell 4 by blowing hot air. The PCB board 11 of the present application is characterized in that a positive copper ring 111 and a negative copper ring 112 are provided on the front, and a high-voltage input copper ring 113 is provided on the back. The positive copper ring 111 serves as the low-voltage output positive pole, the high-voltage input copper ring 113 serves as the high-voltage input positive pole, and the negative copper ring 112 serves as the common negative pole. These three copper rings are electrically connected to external conductive components to realize high-voltage input and low-voltage output functions without the need to arrange any conductive cables.

[0036] 3 , the circuit assembly 1 further includes an elastic ring 14 , which includes a base ring 141 and lifters 142 evenly distributed around the base ring 141 . The back of the base ring 141 is soldered to the negative copper ring 112 via a patch. The lifters 142 are elastically crimped with the spun edge 42 of the metal housing 4 . The elastic crimping can prevent the metal housing 4 from being loosely crimped with the negative copper ring 112 on the PCB board 11 or from being damaged.

[0037] Referring to Figure 3, the outer conductive cap 12 and the inner conductive cap 13 are both soldered to the PCB board 11 through patch welding. First, the connection strength is good and the fixation is reliable. Second, the cross-sectional area of ​​the connection is large, the resistance is small, and the conductivity is good. The electronic components on the PCB board 11 are preferably concentratedly arranged inside the outer conductive cap 12 and the inner conductive cap 13. First, the electronic components are arranged reasonably, making full use of the internal space of the outer conductive cap 12 and the inner conductive cap 13. Second, the outer conductive cap 12 and the inner conductive cap 13 are strong and can play a protective role. The electronic components will not come into contact with the outside world and will not be damaged. Third, they have a sealing effect to prevent water and dust from entering, thereby increasing the service life of the PCB board 11. The electronic components in the inner conductive cap 13 of this application are three-in-one step-down chips, which belong to the existing technology and have the advantages of high integration and small size. The design of the PCB board 11 is easier. The electronic components in the outer conductive cap 12 are inductors, capacitors, resistors and other components. Furthermore, because the outer conductive cap 12 is exposed and in contact with the outside world, it is susceptible to impact, requiring a stronger fixed connection. Therefore, a flange is provided on the outer conductive cap 12. The flange has a certain width, several times the wall thickness of the outer conductive cap 12, thus providing a large contact area with the positive copper ring 111, ensuring a secure fixation and impact resistance. Since the inner conductive cap 13 is not exposed and is not subject to external impact, the strength requirement is slightly lower, so a flange is not required.

[0038] 7 , the wound cell assembly 3 includes a wound cell 33, an upper separator 34 and a lower separator 35. The positive electrode tab 31 extends from the center hole of the upper separator 34 and is welded to the lower surface of the inner conductive cap 13 at its end. The negative electrode tab 32 is wound from the side of the wound cell 33 to the bottom surface and is welded to the bottom wall of the metal shell 4 at its end.

[0039] The specific connection principle of the circuit is as follows: the positive electrode tab 31 of the wound battery cell assembly 3 is connected to the PCB board 11 through the inner conductive cap 13 and the high-voltage input copper ring 113, and the negative electrode tab 32 of the wound battery cell assembly 3 is connected to the PCB board 11 through the metal shell 4, the elastic ring 14, and the negative copper ring 112. After the circuit on the PCB board 11 is reduced in voltage, the positive electrode of the lithium battery is output from the positive copper ring 111 and the outer conductive cap 12, and the negative electrode of the lithium battery is output from the negative copper ring 112, the elastic ring 14, and the metal shell 4.

[0040] Referring to Figure 3 , the metal shell 4 has an inwardly extending groove 41 on its upper portion, which is used to restrict movement of the wound battery cell assembly 3 within the metal shell 4 and also to support the plastic midframe 2. The metal shell 4 has an inwardly extending spun edge 42 for compressing the plastic midframe 2. Positive and negative electrode separators 6 are affixed above the spun edge 42. These separators prevent dust and other debris from entering between the elastic ring 14 and the outer conductive cap 12, preventing a short circuit between the two. Portions of the upper surface of the separators 6 are also wrapped by an insulating outer sheath 5, further securing them.

[0041] This application directly places the wound cell 33 within the metal housing 4, eliminating the need for a housing compared to conventional soft-pack or hard-shell lithium cells, resulting in lower costs. Rolling grooves 41 seal the wound cell assembly 3, preventing electrolyte leakage. The spun edge 42 at the top compresses and seals the plastic midframe 2, achieving an integrated seal.

[0042] Referring to Figure 3 , the inner wall of the plastic middle frame 2 is provided with a flange 21 for supporting the PCB 11. A potting compound 7 is also provided between the inner conductive cap 13 and the plastic middle frame 2 to form a seal, isolating the electrolyte and preventing it from contacting the PCB 11 and causing corrosion, which could lead to premature failure of the PCB 11. By controlling the thickness and cross-sectional shape of the potting compound 7, the potting compound 7 can be given a specific strength. If an internal fault occurs within the wound battery cell assembly 3, the temperature and pressure will rise. When a certain threshold is reached, the potting compound 7 can be broken through to release pressure, preventing an overpressure explosion in the lithium battery.

[0043] The insulating outer sheath 5 is preferably made of PVC material and is wrapped around the metal shell 4 by heat shrinking.

[0044] The implementation principle of the present application is as follows: the PCB board 11 in the circuit assembly 1 of the present application is also provided with necessary circuits such as a step-down circuit, a voltage stabilizing circuit, a charging circuit, and an over-discharge protection circuit. The outer conductive cap 12 serves as the positive electrode of the battery, and the metal shell 4 serves as the negative electrode of the battery, which can stably output a low voltage and realize the same-port charging and discharging function; an outer conductive cap 12 and an inner conductive cap 13 are provided at the same time, and a positive copper ring 111, a negative copper ring 112 and a high-voltage input copper ring 113 are provided on the PCB board 11 to realize the circuit connection between the wound battery cell assembly 3 and the PCB board 11, and the circuit connection between the low-voltage output element and the PCB board 11. No conductive cables are used, the electrical performance is more stable, and the internal connection structure of the lithium battery is simplified, which is less prone to problems and safer. The manufacturing method described in the present application has reasonable procedures, a high yield rate, and can be industrialized and mass-produced.

[0045] The above are all preferred embodiments of the present application, and are not intended to limit the scope of protection of the present application. Therefore, any equivalent changes made based on the structure, shape, and principle of the present application should be included in the scope of protection of the present application.

Claims

1. A low-voltage lithium battery, characterized in that: The invention comprises a circuit assembly (1), a plastic middle frame (2), a wound battery core assembly (3), a metal shell (4) and an insulating outer skin (5), wherein the circuit assembly (1), the plastic middle frame (2) and the wound battery core assembly (3) are sequentially arranged in the metal shell (4) from top to bottom, and the insulating outer skin (5) is covered on the outside of the metal shell (4). The circuit assembly (1) comprises a PCB board (11), an outer conductive cap (12) and an inner conductive cap (13), and a positive copper ring ( 111) and a negative copper ring (112), the positive copper ring (111) is electrically connected to the outer conductive cap (12), the negative copper ring (112) is electrically connected to the metal shell (4), a high-voltage input copper ring (113) is provided on the back of the PCB board (11), the high-voltage input copper ring (113) is electrically connected to the inner conductive cap (13), the positive pole tab (31) of the wound battery cell assembly (3) is electrically connected to the inner conductive cap (13), and the negative pole tab (32) is electrically connected to the metal shell (4).

2. The low-voltage lithium battery according to claim 1, characterized in that The upper portion of the metal shell (4) is provided with a rolling groove (41) inwardly, which is used to limit the movement of the wound battery core assembly (3) in the metal shell (4) and is also used to support the plastic middle frame (2).

3. The low-voltage lithium battery according to claim 2, characterized in that: The metal shell (4) is provided with a spun edge (42) inwardly for pressing the plastic middle frame (2). A positive and negative electrode separator (6) is also pasted above the spun edge (42), and a portion of the upper surface of the positive and negative electrode separator (6) is also wrapped by an insulating outer skin (5).

4. The low-voltage lithium battery according to claim 2, characterized in that: The inner wall of the plastic middle frame (2) is provided with a flange edge (21) for supporting the PCB board (11).

5. The low-voltage lithium battery according to claim 4, characterized in that: A potting compound (7) is also provided between the inner conductive cap (13) and the plastic middle frame (2) to form a seal to isolate the electrolyte.

6. The low-voltage lithium battery according to claim 3, characterized in that: The circuit assembly (1) further includes an elastic ring (14), the elastic ring (14) including a base ring (141) and lift tabs (142) uniformly arranged around the base ring (141), the back of the base ring (141) being welded to the negative electrode copper ring (112) through patch welding, and the lift tabs (142) being elastically pressed against the spun edge (42) of the metal shell (4).

7. The low-voltage lithium battery according to claim 1, characterized in that: The outer conductive cap (12) and the inner conductive cap (13) are both soldered on the PCB board (11) via patch welding.

8. The low-voltage lithium battery according to claim 7, characterized in that: The electronic components on the PCB board (11) are centrally arranged inside the outer conductive cap (12) and the inner conductive cap (13).

9. The low-voltage lithium battery according to claim 1, characterized in that: The wound battery cell assembly (3) comprises a wound battery cell (33), an upper separator (34) and a lower separator (35); the positive electrode tab (31) extends through the central hole of the upper separator (34) and is welded at its end to the lower surface of the inner conductive cap (13); the negative electrode tab (32) is wound from the side of the wound battery cell (33) to the bottom surface and is welded at its end to the bottom wall of the metal shell (4).

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