A needle for injecting liquid into a button cell and a method of injecting liquid into a button cell

Abstract

This invention patent belongs to the field of lithium batteries and relates to a button cell electrolyte injection needle and injection method. It includes a dispensing point and an injection point. The dispensing point is cylindrical, and the injection point is conical, with a sealed structure at its lowest point. The dispensing point and injection point are fixedly connected at a junction. The conical inclined surface of the injection point has multiple injection holes, with one-third of the surface area of ​​the conical structure having injection holes, and the other two-thirds being un-holeed. The injection needle is tilted at a certain angle to the bare cell plane for electrolyte injection, which ensures a large injection area while preventing electrolyte overflow from the casing. This invention, combining the injection needle and injection method, solves problems such as insufficient electrode wetting, poor overall wetting effect, electrolyte splashing, electrolyte contamination of casing and equipment surfaces, and electrolyte loss.

Description

Technical Field

[0001] This invention belongs to the field of lithium batteries, specifically relating to a button battery injection needle and injection method. Background Technology

[0002] Lithium-ion button batteries possess excellent performance characteristics such as long lifespan, high energy density, and small size, and are widely used in various small devices such as Bluetooth headsets. Due to their small size and limited electrolyte volume, the electrolyte filling process for the wound bare cells is crucial. The effectiveness of electrode wetting determines subsequent electrical performance; poor electrode wetting can lead to higher internal resistance or shorter cycle life. Current designs of the filling needles and methods often result in insufficient electrode wetting, poor overall wetting, or electrolyte splashing, causing losses and contamination of the casing and equipment surfaces.

[0003] There are generally two types of bare cell structures for button batteries: wound and stacked. Larger button batteries and those designed to improve production efficiency typically use a wound structure. The traditional electrolyte injection method involves a conical, single-hole injection needle positioned directly against the side of the bare cell (perpendicular to the winding direction). The center of the bare cell has a hole (a remnant of the winding needle), with a diameter approximately equal to the needle's diameter. This injection needle and different injection methods can produce two results: First, when the injection needle is directly against the hole, the electrolyte is injected quickly. However, the bare cell has significant surface tension, and the layers are tightly packed. Due to gravity, it is difficult for the electrolyte to penetrate the electrodes from the bottom. Second, when the injection needle is directly against the side of the bare cell, the single-hole needle delivers a larger flow rate per unit time, creating a greater impact force on the bare cell. This causes significant collisions between the electrolyte and the injection surface, resulting in electrolyte splashing, contaminating the casing and equipment surfaces, or causing electrolyte loss. Summary of the Invention

[0004] The purpose of this invention is to provide a button battery injection needle and injection method, which solves problems such as insufficient electrode wetting, poor overall wetting effect, electrolyte splashing, contamination of casing and equipment surfaces, and electrolyte loss.

[0005] The technical solution provided by this invention is as follows:

[0006] A button battery liquid injection needle includes a liquid inlet and a liquid injection outlet. The liquid inlet is cylindrical, and the liquid injection outlet is conical. The lowermost end of the liquid injection outlet is a sealed structure. The liquid inlet and the liquid injection outlet are fixedly connected by a junction. The conical inclined surface of the liquid injection outlet is provided with multiple liquid injection holes. One-third of the surface area of ​​the conical structure of the liquid injection outlet is provided with liquid injection holes, while the other two-thirds of the surface area is not provided with liquid injection holes.

[0007] The present invention also provides a method for injecting electrolyte into a button battery, characterized in that the electrolyte is injected using the button battery injection needle as described in claim 1, the injection needle being positioned on the side of the bare cell with an injection hole, occupying 1 / 3 of the surface area of ​​the conical structure, during injection, the electrolyte is injected from the supply point into the injection point, and the electrolyte collected at the injection point is discharged through the injection hole, the injection point being at a 45° angle to the bare cell.

[0008] Furthermore, the height distance between the liquid injection point and the bare battery cell is 2-4 mm, and the distance between the foremost tip of the conical liquid injection point and the left edge of the casing is 7-9 mm.

[0009] Furthermore, the inner and outer surfaces of the liquid supply point and the liquid injection point are coated with Teflon.

[0010] Furthermore, the injection holes are of uniform size and are evenly distributed on the conical inclined surface at the injection point.

[0011] Furthermore, the diameter of the injection hole is 0.1 mm; the distance between the injection holes is 0.2 mm.

[0012] Furthermore, the diameter of the junction is the same as the diameter of the liquid inlet.

[0013] Furthermore, the diameter of the liquid inlet is 2 mm.

[0014] Furthermore, the height of the liquid inlet is 30-50 mm; the height of the liquid injection outlet is 14.82 mm.

[0015] Furthermore, the lowest point of the injection site has a smooth curved surface structure.

[0016] Beneficial effects

[0017] This invention is simple and effective, reducing splashing during electrolyte injection, minimizing contamination of casing and equipment surfaces, and preventing electrolyte loss. It also increases the injection area and effectively improves the wetting effect on the electrodes of bare battery cells. Attached Figure Description

[0018] Figure 1 Overall structural diagram of a button cell;

[0019] Figure 2 A front view of the injection needle of this invention;

[0020] Figure 3 Side view of the injection needle of the present invention;

[0021] Figure 4 Diagram of the injection method of this invention;

[0022] Figure 5 Diagram of injection method for Group 1;

[0023] Figure 6 Diagram of injection method for Group 2.

[0024] Attached reference numerals: 1. Small casing; 2. Bare cell; 3. Center hole (needle winding position); 4. Large casing; 5. Tab; 6. Liquid supply point; 7. Junction point; 8. Liquid injection hole; 9. Liquid injection point. Detailed Implementation

[0025] The present invention will now be further described with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and should not be construed as limiting the scope of protection of the present invention.

[0026] Example 1

[0027] A button battery electrolyte injection needle includes a liquid inlet 6 and an electrolyte filling outlet 9. Both the liquid inlet 6 and the electrolyte filling outlet 9 are made of stainless steel with a Teflon coating. The liquid inlet 6 is cylindrical with a diameter of 2 mm and a height S1 of 30-50 mm. The electrolyte filling outlet 9 is conical with a height S2 of 14.82 mm. The lowermost end of the electrolyte filling outlet 9 has a smooth curved surface and a sealed structure. The liquid inlet 6 and the electrolyte filling outlet 9 are fixedly connected by a junction 7, the diameter of which is the same as that of the liquid inlet. The maximum diameter of the junction 7 is 2 mm. Multiple electrolyte filling holes 8 of uniform size are provided on the conical inclined surface of the electrolyte filling outlet 9. The diameter of each electrolyte filling hole 8 is 0.1 mm, and the distance between the holes is 0.2 mm. A front view is shown below. Figure 2 As shown.

[0028] Example 2

[0029] The difference between this embodiment and Embodiment 1 is that: one-third of the surface area of ​​the conical structure at the injection point 9 is provided with injection holes, while the other two-thirds of the surface area is not provided with injection holes; that is, injection holes are provided at the 120° cross-section of the conical body, as shown in the side view below. Figure 3 As shown, during liquid injection, the 120° section with the liquid injection hole is positioned at a certain angle directly facing the bare cell to perform large-area liquid injection on the bare cell.

[0030] Example 3

[0031] Taking the 1254 button cell as an example, the diameter of the bare cell is approximately 10.8mm, and the upper surface area is 91.56mm². 2 The diameter of the small casing carrying the bare battery cell is 11.70 mm, and the surface area of ​​the casing is 107.46 mm². 2Assuming the injection area covers a 10.5mm bare cell diameter, and the injection angle is 45° (i.e., the angle between the injection needle and the bare cell plane is 45°), then the generatrix length of the conical injection needle is 10.5 / con45° = 10.5 / 0.707 = 14.85mm. The maximum diameter of the injection needle is 2mm. The side of the injection needle directly facing the bare cell, approximately 1 / 3 of the conical area, occupies about 120° of the cone. Therefore, the injection area is 14.85 * 3.14 * 1 / 3 = 15.54mm². 2 This ensures that the electrolyte injection area is as large as possible while preventing electrolyte from overflowing from the small casing, because the height of the bare cell here is about 0.2 to 0.3 mm higher than the small casing.

[0032] Injection method: The injection needle is tilted at a certain angle to the bare cell plane for injection. This ensures that the injection area is as large as possible and prevents the electrolyte from overflowing from the small casing.

[0033] During electrolyte injection, electrolyte is injected from the supply port 6 into the injection port 9. The electrolyte collected at the injection port 9 is discharged through the injection hole 8. The injection hole 8, which has multiple holes, is directly opposite the bare battery cell 2. The injection port 9 and the bare battery cell 2 are at a 45° angle. The height distance S3 between the injection port 9 and the bare battery cell 2 is approximately 2-4 mm. The front end of the cone-shaped part of the injection port is approximately 7-9 mm from the left edge S4 of the casing. The specific injection method is as follows: Figure 4 As shown. This injection needle design and injection method solves the problems of insufficient electrode wetting, poor overall wetting effect, and electrolyte splashing, which can contaminate the casing and equipment surface or cause electrolyte loss.

[0034] This embodiment uses the 1254 button battery as an example, but it is not limited to 1254. It includes various models such as 0854, 0954, 1054, 1154, 1354, 1454, and 1240.

[0035] Example 4

[0036] Taking the 1254 model as an example, the liquid retention range of this model battery is 0.20±0.01g. The closer the liquid retention data is to the center value, the better, and the more obvious the wetting effect after disassembly of the electrode sheets, the better.

[0037] The final comparison results of different injection methods are shown in Table 1. Among them, the injection needle structure and injection method used in Group 3 have better electrode surface wettability, less electrolyte loss, and better electrolyte retention.

[0038] Group 1: The injection needle has a single hole vertical structure. The injection needle tip is perpendicular to the center hole of the bare cell, which is the position left by the winding needle. The electrolyte is injected quickly, but the bare cell has a large tension. The contact between each layer is relatively tight. Due to the effect of gravity, it is difficult for the electrolyte to penetrate the electrode plate from the bottom in reverse. The surface wettability of the electrode plate is poor.

[0039] Group 2: The injection needle has a single-hole vertical structure. The injection needle is perpendicular to the position between the center hole of the bare cell and the casing that carries the bare cell. The single-hole injection needle has a large flow rate per unit time, which creates a large impact on the bare cell. This causes a large collision between the electrolyte and the injection contact surface of the bare cell, resulting in electrolyte splashing, which contaminates the casing and equipment surface or causes electrolyte loss.

[0040] Group 3: The injection needle described in Example 2 is used. The injection needle has a multi-hole structure, and the injection method is to inject the liquid at a certain angle to the plane of the bare cell. This can ensure that the injection area is as large as possible and prevent the electrolyte from overflowing from the small shell.

[0041] During electrolyte injection, electrolyte is injected from the supply port 6 into the injection port 9. The electrolyte collected at the injection port 9 is discharged through the injection hole 8. The injection hole 8, which has multiple holes, is directly opposite the bare battery cell 2. The injection port 9 and the bare battery cell 2 are at a 45° angle. The height distance S3 between the injection port 9 and the bare battery cell 2 is approximately 2-4 mm. The front end of the cone-shaped part of the injection port is approximately 7-9 mm from the left edge S4 of the casing. The specific injection method is as follows: Figure 4 As shown. This injection needle design and injection method solves the problems of insufficient electrode wetting, poor overall wetting effect, and electrolyte splashing, which can contaminate the casing and equipment surface or cause electrolyte loss.

[0042] Group 1 and Group 2 are both single-hole injection needle structures (with only one injection hole), and the injection method is that the overall structure of the injection needle (i.e., one injection hole) is perpendicular to the structure of the bare cell. Group 3 is the injection needle of the present invention, and the injection method is different from the first two groups. Judging from the injection effect, i.e. the wetting effect and liquid retention of the electrode sheet, the wetting effect of the electrode sheet of the present invention is the most obvious, and the liquid retention is closest to the center value. The present invention has a great advantage.

[0043] Table 1

[0044]

[0045] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only one specific implementation case of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for injecting electrolyte into a button cell, characterized in that, Electrolyte injection is performed using a button battery injection needle, which includes a supply point and an injection point. The supply point is cylindrical, and the injection point is conical. The lowest point of the injection point has a closed, smooth curved surface structure. The supply point and the injection point are fixedly connected at a junction. The conical inclined surface of the injection point has multiple injection holes. One-third of the surface area of ​​the conical body has injection holes, while the other two-thirds of the surface area does not have injection holes. An injection hole is located on the side of the injection needle facing the bare battery cell. During injection, electrolyte is injected from the supply point into the injection point, and the electrolyte collected at the injection point is discharged through the injection hole. The injection point and the bare battery cell are at a 45° angle. The height distance between the injection point and the bare battery cell is 2-4 mm, and the distance from the front end of the conical body to the left edge of the casing is 7-9 mm.

2. The button battery electrolyte filling method according to claim 1, characterized in that, The inner and outer surfaces of the liquid inlet and liquid outlet are coated with Teflon.

3. The button battery electrolyte filling method according to claim 1, characterized in that, The injection holes are all the same size and are evenly distributed on the conical inclined surface at the injection point.

4. The button battery electrolyte filling method according to claim 1, characterized in that, The diameter of the injection hole is 0.1 mm; the distance between the injection holes is 0.2 mm.

5. The button battery electrolyte filling method according to claim 1, characterized in that, The diameter of the junction is the same as the diameter of the liquid inlet.

6. The button battery electrolyte filling method according to claim 1, characterized in that, The diameter of the liquid inlet is 2 mm.

7. The button battery electrolyte filling method according to claim 1, characterized in that, The height of the liquid inlet is 30-50 mm; the height of the liquid injection point is 14.82 mm.

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