Positive pole lug diversion assembly

Abstract

The invention relates to the technical field of lithium battery manufacturing, in particular to an anode tab diversion assembly. The battery comprises a positive electrode cap and a battery cell positive electrode, a positive electrode upper confluence sheet is welded on the positive electrode cap, a positive electrode lower confluence sheet is welded on the battery cell positive electrode, and a conductive spring is crimped between the positive electrode upper confluence sheet and the positive electrode lower confluence sheet. The spring is in a compressed state after the positive upper confluence sheet, the conductive spring and the positive lower confluence sheet are crimped, so that the crimping force between the upper and lower confluence sheets and the conductive spring is kept constant, and the positive electrode of the battery cell is connected with the positive cap through the positive lower confluence sheet, the conductive spring and the positive upper confluence sheet. Through the combined structure of the positive electrode upper and lower confluence sheets and the conductive spring, the conduction cross section of the positive electrode tab is improved, the current conduction capability of the positive electrode tab is improved, the obtained lithium battery positive electrode tab diversion structure is highly stable and reliable, and the discharge rate of the lithium battery is high.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium battery manufacturing, and in particular to a positive electrode tab flow guide assembly. Background Art

[0002] Lithium batteries have high energy density, long cycle life, and good safety performance. They are currently widely used in portable devices, electric vehicles, energy storage and other industries.

[0003] In the process of manufacturing lithium batteries, the positive electrode tab is generally connected to the positive electrode sheet, and the negative electrode tab is connected to the negative electrode sheet; then the positive and negative electrode sheets with the positive and negative electrode tabs connected are wound with the separator to form a battery cell. The battery cell is then placed in the battery case, the negative electrode tab is connected to the bottom of the battery case, and the positive electrode tab is connected to the positive electrode cap. Currently, the method of connecting the positive electrode tab and the positive electrode cap includes direct crimping (i.e., tight contact method), but there are shortcomings. A gap is easily formed between the positive electrode tab and the cap. At the same time, external vibration or falling of the battery can reduce the contact tightness between the positive electrode tab and the positive electrode cap, resulting in increased contact resistance. There is also a direct welding method to connect the positive ear and the positive cap. The patent application number is 201110030497.8, which discloses the use of inert gas shielded welding of the positive ear and the positive cap explosion-proof combination. The width of the positive ear and the explosion-proof combination is 2-3.5mm, the thickness is 0.05-0.3mm, and the total conduction cross-section is 1mm. 2 This process ensures the reliability of the welding point, but the conducting cross-section is relatively small. For long-term discharge of high currents of tens to hundreds of amperes at high rates, there is an issue of insufficient current-carrying cross-section. Due to the limited internal space of the battery and the flexibility of the tab, it is difficult to significantly increase the conducting cross-section of the positive tab. Summary of the Invention

[0004] In view of the above technical defects, the present invention solves the technical problem of small conduction cross-section of the positive electrode tab and provides a positive electrode tab conduction assembly with large conduction cross-section and high reliability.

[0005] To solve the above-mentioned technical problems, the present invention provides a technical solution: a positive electrode tab guide assembly comprising a positive electrode cap and a battery cell positive electrode, wherein the positive electrode cap is welded with an upper positive electrode busbar, the positive electrode cell is welded with a lower positive electrode busbar, and a conductive spring is crimped between the upper and lower positive electrode busbars. After the upper positive electrode busbar, the conductive spring, and the lower positive electrode busbar are crimped together, the spring is in a compressed state, ensuring that the crimping force between the upper and lower busbars and the conductive spring remains constant. The battery cell positive electrode is connected to the positive electrode cap via the lower positive electrode busbar, the conductive spring, and the upper positive electrode busbar.

[0006] Further: In the above-mentioned positive electrode tab guide assembly, the positive electrode cap, positive electrode upper busbar, and positive electrode lower busbar are all disc-shaped. The conductive spring is a horizontal closed circular ring spring with an elliptical longitudinal cross-section. The spring with an elliptical longitudinal cross-section has each spring coil in the same inclination direction, preventing the spring from tilting in inconsistent directions when subjected to upward and downward forces, thereby ensuring consistent spring compression force across the entire coil. The circular springs are two concentric rings with a spacing greater than 0.2 mm. The spring wire diameter of the circular springs is 0.15-0.5 mm, with the inner ring having 50-60 coils and the outer ring having 80-100 coils to improve conductivity. The positive electrode upper busbar and the positive electrode lower busbar are both provided with grooves to accommodate the circular springs. The inner side of the groove is coated with a silver layer with a thickness of 5-10 μm. The contact surface between the positive upper and lower busbars and the annular spring is an arched surface. The arched surface of the upper and lower busbars covers the outer periphery of the annular spring, increasing the contact area between the spring and the upper and lower busbars and reducing the contact resistance. The gap between the positive upper and lower busbars is 0.3-1.3mm. The guide cross section of the upper and lower busbars of the positive electrode is greater than 10mm. 2 The above greatly improves the flow capacity of the positive electrode ear.

[0007] A positioning ring is installed in the hollow space of the inner ring spring. The upper end of the positioning ring is aligned with the center of the positive upper busbar, and the lower end of the positioning ring is aligned with the center of the positive lower busbar. Insulating rings are installed on the outside of the positive upper and lower busbars. The positioning rings ensure the concentricity of the upper and lower busbars and prevent eccentricity during installation. Insulating rings are installed on the outside of the positive upper and lower busbars to prevent the positive electrode of the battery cell from short-circuiting with the battery cell casing (negative electrode) through the upper and lower busbars during installation.

[0008] Or: In the above-mentioned positive electrode tab guide assembly, the conductive spring is a vertical upright spring, the wire diameter of the upright spring is 0.15-0.5mm, and the number of coils of the upright spring is 4-7.

[0009] The lower positive busbar is radially distributed with elongated holes to facilitate electrolyte injection into the cell housing. The conductive spring is made of chromium-zirconium copper or brass to enhance the spring's fatigue resistance and ensure a constant contact force between the spring and the upper and lower positive busbars.

[0010] Compared to the prior art, the aforementioned positive electrode tab guide assembly comprises a positive electrode cap and a battery cell positive electrode. The positive electrode cap is welded with an upper positive electrode busbar, and the positive electrode is welded with a lower positive electrode busbar. A conductive spring is crimped between the upper and lower positive electrode busbars. After the upper positive electrode busbar, the conductive spring, and the lower positive electrode busbar are crimped together, the spring is compressed, ensuring a constant crimping force between the upper and lower busbars and the conductive spring. The battery cell positive electrode is connected to the positive electrode cap via the lower positive electrode busbar, the conductive spring, and the upper positive electrode busbar. The combined structure of the upper and lower positive electrode busbars and the conductive spring increases the conductive cross-section of the positive electrode tab, improving its current conduction capability. This, in turn, reduces the internal resistance of the battery tab and increases the discharge rate of the lithium battery. Compared to the prior art, the discharge rate of the lithium battery obtained using this technology is increased by 3-6 times. Therefore, the beneficial technical effect of the present invention is that the positive electrode tab guide structure is highly stable and reliable, with a high discharge rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 This is an enlarged structural diagram of a longitudinal section of a positive electrode tab guide assembly in accordance with a first embodiment;

[0012] Figure 2 Schematic diagram of the structure of the busbar on the positive electrode in the first embodiment;

[0013] Figure 3 Schematic diagram of the structure of the positive electrode lower busbar in the first embodiment;

[0014] Figure 4 This is a schematic diagram of a double-ring spring structure in the first embodiment;

[0015] Figure 5 This is an enlarged structural diagram of a longitudinal section of a positive electrode tab flow guide assembly according to a second embodiment;

[0016] Figure 6 yes Figure 5 Schematic diagram of the top view of the structure after uncovering the busbar on the positive electrode;

[0017] Figure 7 This is an enlarged structural diagram of a longitudinal section of a positive electrode tab guide assembly according to a sixth embodiment;

[0018] Figure 8 This is an enlarged structural diagram of a longitudinal section of a positive electrode tab guide assembly according to a seventh embodiment;

[0019] Among them, 1 is the positive electrode cap, 2 is the positive electrode of the battery cell, 3 is the upper busbar of the positive electrode, 4 is the lower busbar of the positive electrode, 5 is the conductive spring, 6 is the groove, 7 is the positioning ring, 8 is the insulating ring, 9 is the long hole, 10 is the inner ring spring, and 11 is the outer ring spring. DETAILED DESCRIPTION

[0020] The main purpose of this invention is to increase the conductive cross-section of the positive electrode tab by combining upper and lower positive electrode busbars with a conductive spring, thereby improving the current conduction capacity of the positive electrode tab. This, in turn, reduces the internal resistance of the battery tab and increases the discharge rate of the lithium battery. The conductive spring serves as an intermediate current carrier, which not only serves as a flow-conducting cross-section but also maintains a certain elastic force between the contact surface of the upper and lower positive electrode busbars and the spring, effectively solving the problem of loose connection of the battery positive electrode tab caused by various reasons.

[0021] Implementation method 1: Figure 1-4 A positive electrode tab guide assembly includes a positive electrode cap 1 and a battery cell positive electrode 2. The positive electrode cap is welded with a positive electrode upper busbar 3, and the positive electrode lower busbar 4 is welded with a positive electrode lower busbar 4. A conductive spring 5 is crimped between the positive electrode upper busbar 3 and the positive electrode lower busbar 4. The positive electrode cap 1, the positive electrode upper busbar 3, and the positive electrode lower busbar 4 are all disc-shaped. The conductive spring is a horizontal closed circular ring spring. The circular ring springs are two concentric circular springs with a spacing of >0.2mm. The spring wire diameter of the circular ring spring is 0.15-0.5mm. The inner circular ring spring 10 has 50-60 turns, and the outer circular ring spring 11 has 80-100 turns. The positive electrode upper busbar 3 and the positive electrode lower busbar 4 are both provided with grooves 6 for accommodating the circular springs. A silver-plated layer is provided on the inner side of the groove, and the thickness of the silver-plated layer is 5-10um. The gap between the upper busbar of the positive electrode and the lower busbar of the positive electrode is 0.3-1.3mm. The lower busbar of the positive electrode is evenly distributed in the radial direction with long strip holes 9 for convenient injection of electrolyte into the battery cell casing, and the conductive spring is made of chromium zirconium copper or brass. In all embodiments of the present invention, the positive electrode cap includes a top cap and a bottom sheet. For ease of understanding, the positive electrode cap 1 of the present invention is identified by the sheet pointing to the bottom surface of the positive electrode cap.

[0022] Implementation 2: The positive electrode tab guide assembly of the above implementation 1 is selected and applied to lithium iron batteries. The upper and lower busbars of the positive electrode are made of chromium zirconium copper with a thickness of 0.25mm. The inner ring spring has 10 inner rings with 68 turns, the outer ring spring has 11 turns with 97 turns, the wire diameter is 0.25mm, and the wire surface is silver-plated with 8um. The calculated conductive cross section is 16.2mm. 2, which is much larger than the conductive cross-section of the positive pole ear of a normal lithium iron battery, effectively reducing the pole ear resistance, thereby increasing the discharge rate of the lithium iron battery. The elastic force of the circular spring combination structure is used to ensure that the contact surface between the upper and lower positive electrode tabs and the spring maintains a moderate pressing force, effectively solving the problem of loosening of the pole ear pressing surface caused by battery cell vibration, falling, etc. Taking the 26550 type lithium iron battery as an example, the conventional positive pole ear connecting piece has a width of 3-5mm, a thickness of 0.2-0.4mm, a flow guide cross-section of less than 2mm2, and a discharge rate of no more than 1C (the capacity of the battery in this embodiment is referred to as 1C). The horizontal double circular ring spring of this embodiment has a flow cross-section of 16.2mm2, and a flow guide cross-section much larger than the conventional guide piece connection method, which effectively reduces the pole ear resistance and the discharge rate can reach 5C.

[0023] In fact, according to the actual application of the battery, in order to increase the conduction cross-section of the positive electrode tab, the present invention can also adopt the following implementation mode, and the discharge rate of the resulting lithium battery reaches 3C-6C, as detailed below:

[0024] Implementation method three: Different from implementation methods one and two, the annular springs are one, three, or four concentric ring springs, etc., which are determined according to the area size of the positive electrode cap 1, the positive electrode upper busbar 3 and the positive electrode lower busbar 4.

[0025] Implementation method 4: Figure 5 、 6 Unlike the first embodiment, the conductive spring is a vertical spring with a wire diameter of 0.15-0.5 mm and 4-7 coils. This also increases the conduction cross-section of the positive electrode tab, and the resulting lithium battery has a discharge rate of up to 3C.

[0026] Embodiment 5: Unlike Embodiments 1 and 2, the circular ring spring has an elliptical longitudinal cross-section. This elliptical cross-section allows each spring coil to tilt in the same direction, preventing inconsistent tilting when the spring is subjected to vertical forces, thereby ensuring consistent spring compression force across the coils.

[0027] Implementation method six: Figure 7 , which is different from the fifth embodiment, a positioning ring 7 is provided in the hollow space of the inner circular ring spring 10. The upper end of the positioning ring is aligned with the center of the positive upper busbar 3, and the lower end of the positioning ring is aligned with the center of the positive lower busbar 4. The positioning ring 7 ensures the concentricity of the upper and lower busbars and prevents eccentricity during installation of the upper and lower busbars.

[0028] Implementation method seven: Figure 8The difference from the sixth embodiment is that an insulating ring 8 is provided on the outside of the positive upper busbar 3 and the positive lower busbar 4 to prevent the positive electrode of the battery cell from short-circuiting with the battery cell casing (negative electrode) through the busbar during installation.

[0029] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A positive electrode tab guide assembly, comprising a positive electrode cap (1) and a battery cell positive electrode (2), characterized in that: A positive electrode upper busbar (3) is welded on the positive electrode cap, a positive electrode lower busbar (4) is welded on the battery cell positive electrode (2), and a conductive spring (5) is crimped between the positive electrode upper busbar (3) and the positive electrode lower busbar (4).

2. The positive electrode tab flow guide assembly according to claim 1, characterized in that: The positive electrode cap (1), the positive electrode upper busbar (3) and the positive electrode lower busbar (4) are all disc-shaped.

3. The positive electrode tab flow guide assembly according to claim 2, characterized in that: The conductive spring is a horizontal closed circular ring spring, and the longitudinal section of the circular ring spring is elliptical.

4. The positive electrode tab flow guide assembly according to claim 3, characterized in that: The circular springs are two concentric ring springs, the distance between the two concentric ring springs is greater than 0.2mm, the spring wire diameter of the circular springs is 0.15-0.5mm, the number of coils of the inner ring spring is 50-60, and the number of coils of the outer ring spring is 80-100.

5. The positive electrode tab flow guide assembly according to claim 4, characterized in that: The positive electrode upper busbar (3) and the positive electrode lower busbar (4) are both provided with a groove (6) for accommodating a circular ring spring.

6. The positive electrode tab flow guide assembly according to claim 5, characterized in that: A silver plating layer is provided on the inner side of the groove, and the thickness of the silver plating layer is 5-10 μm; the gap between the positive electrode upper busbar and the positive electrode lower busbar is 0.3-1.3 mm.

7. The positive electrode tab flow guide assembly according to claim 3, characterized in that: A positioning ring (7) is provided in the hollow space of the inner circular ring spring, the upper end of the positioning ring faces the center of the positive upper busbar (3), and the lower end of the positioning ring faces the center of the positive lower busbar (4), and an insulating ring (8) is provided outside the positive upper busbar (3) and the positive lower busbar (4).

8. The positive electrode tab flow guide assembly according to claim 1, characterized in that: The conductive spring is a vertical upright spring.

9. The positive electrode tab flow guide assembly according to claim 8, characterized in that: The diameter of the upright spring wire is 0.15-0.5 mm, and the number of the upright spring coils is 4-7.

10. The positive electrode tab flow guide assembly according to claim 8 or 9, characterized in that: The positive electrode lower busbar is evenly provided with long strip holes (9) in the radial direction for facilitating the injection of electrolyte into the battery cell housing, and the conductive spring is made of chromium zirconium copper or brass.

Images