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 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 making 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 connected with the positive and negative electrode tabs are wound with the diaphragm to form a battery cell, and then the battery cell is 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. At present, the connection method between the positive electrode tab and the positive electrode cap includes direct crimping method (i.e., tight contact method), but there are shortcomings. A gap is easily generated between the positive electrode tab and the cap. At the same time, external vibration or falling of the battery will cause the contact tightness between the positive electrode tab and the positive electrode cap to decrease, 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 protection welding of the positive ear and the positive cap explosion-proof assembly. The width of the positive ear and the explosion-proof assembly is 2-3.5mm, the thickness is 0.05-0.3mm, and the total flow guide 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 large currents of tens to hundreds of amperes at high rates, there is a problem of insufficient current-carrying cross section. Due to the 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] In order to solve the above technical problems, the technical solution of the present invention is: a positive electrode tab guide assembly, including a positive electrode cap and a positive electrode of a battery cell, wherein an upper positive electrode busbar is welded on the positive electrode cap, and a lower positive electrode busbar is welded on the positive electrode of the battery cell, and a conductive spring is crimped between the upper positive electrode busbar and the lower positive electrode busbar. After the upper positive electrode busbar, the conductive spring and the lower positive electrode busbar are crimped, the spring is in a compressed state, ensuring that the crimping force between the upper and lower busbars and the conductive spring remains constant, and the positive electrode of the battery cell is connected to the positive electrode cap through 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, the positive electrode upper busbar and the positive electrode lower busbar are all in the shape of a disc. The conductive spring is a horizontal closed circular ring spring. The circular ring spring is two concentric circular springs, the spacing between the two concentric circular ring springs is >0.2mm, the spring wire diameter of the circular ring spring is 0.15-0.5mm, the number of coils of the inner circular ring spring is 50-60, and the number of coils of the outer circular ring spring is 80-100, so as to improve the conductivity. The positive electrode upper busbar and the positive electrode lower busbar are both provided with grooves for accommodating the circular ring spring. The inner side of the groove is provided with a silver-plated layer, and the thickness of the silver-plated layer is 5-10um. The contact surface between the positive electrode upper busbar, the positive electrode lower busbar and the circular spring is a circular arch surface, and the circular arch surface of the upper and lower busbars covers the periphery of the circular spring, thereby increasing the contact area between the spring and the upper and lower busbars and reducing the contact resistance. The gap between the upper busbar and the lower busbar is 0.3-1.3mm. The conduction cross section of the upper and lower busbars is greater than 10mm. 2 The above greatly improves the flow capacity of the positive electrode ear.

[0007] 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.

[0008] The positive electrode lower busbar is evenly distributed with long holes in the radial direction for convenient injection of electrolyte into the battery cell housing, and the conductive spring is made of chromium zirconium copper or brass to improve the fatigue resistance of the spring and ensure that the contact elastic force between the spring and the upper and lower contact surfaces of the positive electrode upper and lower busbars is constant.

[0009] Compared with the prior art, the positive electrode tab guide assembly comprises a positive electrode cap and a positive electrode of a battery cell, wherein an upper positive electrode busbar is welded on the positive electrode cap, a lower positive electrode busbar is welded on the positive electrode of the battery cell, and a conductive spring is crimped between the upper positive electrode busbar and the lower positive electrode busbar. After the upper positive electrode busbar, the conductive spring and the lower positive electrode busbar are crimped, the spring is in a compressed state, which ensures that the crimping force between the upper and lower busbars and the conductive spring remains constant, and the positive electrode of the battery cell is connected to the positive electrode cap through the lower positive electrode busbar, the conductive spring and the upper positive electrode busbar. The conductive cross section of the positive electrode tab is increased by the combined structure of the upper and lower positive electrode busbars and the conductive spring, and the current conduction capacity of the positive electrode tab is increased. From the perspective of reducing the internal resistance of the battery tab, the discharge rate of the lithium battery is increased. Compared with the prior art, the discharge rate of the lithium battery obtained by 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, and the discharge rate is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 This is an enlarged structural diagram of a longitudinal section of a positive electrode tab flow guide assembly according to the first embodiment;

[0011] Figure 2 1 is a schematic diagram of the structure of the busbar on the positive electrode in the first embodiment;

[0012] Figure 3 This is a schematic diagram of the structure of the positive electrode lower busbar in the first embodiment;

[0013] Figure 4 This is a schematic diagram of a double-ring spring structure in Embodiment 1;

[0014] Figure 5 This is an enlarged structural diagram of the longitudinal section of the positive electrode tab guide assembly of the second embodiment;

[0015] Figure 6 yes Figure 5 A schematic diagram of the top view of the structure after uncovering the busbar on the positive electrode;

[0016] 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 long hole, 8 is the inner ring spring, and 9 is the outer ring spring. DETAILED DESCRIPTION

[0017] The main purpose of the present invention is to improve the conduction cross section of the positive electrode tab by combining the positive electrode upper and lower busbars with the conductive spring, and improve the current conduction capacity of the positive electrode tab, and from the perspective of reducing the internal resistance of the battery tab, improve the discharge rate of the lithium battery. The conductive spring is used as an intermediate current carrier, which can maintain a certain elastic force between the positive electrode upper and lower busbars and the spring contact surface while serving as a flow guide cross section, effectively solving the problem of loose connection of the battery positive electrode tab caused by various reasons.

[0018] Implementation method 1: Figure 1-4 A positive electrode tab guide assembly comprises a positive electrode cap 1 and a positive electrode 2 of a battery cell, wherein an upper positive electrode busbar 3 is welded on the positive electrode cap, a lower positive electrode busbar 4 is welded on the positive electrode 2 of the battery cell, and a conductive spring 5 is crimped between the upper positive electrode busbar 3 and the lower positive electrode busbar 4. The positive electrode cap 1, the upper positive electrode busbar 3 and the lower positive electrode busbar 4 are all disc-shaped. The conductive spring is a horizontal closed circular ring spring. The circular ring spring is two concentric circular springs, and the spacing between the two concentric circular ring springs is >0.2mm. The spring wire diameter of the circular ring spring is 0.15-0.5mm, the number of turns of the inner circular ring spring 8 is 50-60, and the number of turns of the outer circular ring spring 9 is 80-100. The upper positive electrode busbar 3 and the lower positive electrode busbar 4 are both provided with a groove 6 for accommodating the circular ring spring. The inner side of the groove is provided with a silver-plated layer, 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 holes 7 for convenient injection of electrolyte into the battery cell housing, and the conductive spring is made of chromium zirconium copper or brass.

[0019] 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 number of inner rings of the circular spring is 68, the number of outer rings is 97, 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 ear of a normal lithium iron battery, effectively reducing the ear resistance, thereby increasing the discharge rate of the lithium iron battery. The elastic force of the circular spring combination structure is utilized to ensure that the contact surface between the upper and lower positive electrode plates and the spring maintains a certain crimping force, effectively solving the problem of loosening of the ear crimping surface caused by battery cell vibration, falling, etc. Taking the 26550 type lithium iron battery as an example, the conventional positive ear connecting piece has a width of 3-5mm, a thickness of 0.2-0.4mm, a flow conduction 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 16.2mm 2 The guide cross-section is much larger than the conventional guide plate connection method, which effectively reduces the pole ear resistance and the discharge rate can reach 5C.

[0020] In fact, according to the actual application of the battery, in order to increase the flow conduction cross-section of the positive electrode tab, the present invention can also adopt the following implementation mode, and the discharge rate of the obtained lithium battery reaches 3C-5C, as described in detail as follows:

[0021] Embodiment 3: Different from embodiment 1, the annular springs are 1, 3, or 4 concentric springs, etc., which are determined according to the area sizes of the positive electrode cap 1, the positive electrode upper busbar 3, and the positive electrode lower busbar 4.

[0022] Implementation method 4: Figure 5 , 6 , which is different from the first embodiment, 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.

[0023] 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 principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

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

2. The positive electrode tab flow guide assembly according to claim 1, Features: The positive electrode cap (1), the positive electrode upper busbar (3) and the positive electrode lower busbar (4) are all in the shape of a disc.

3. The positive electrode tab flow guide assembly according to claim 2, Features: The conductive spring is a horizontal closed ring spring.

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

5. The positive electrode tab flow guide assembly according to claim 4, Features: 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, Features: A silver-plated layer is provided on the inner side of the groove, and the thickness of the silver-plated layer is 5-10 um.

7. The positive electrode tab flow guide assembly according to claim 6, Features: The gap between the positive electrode upper busbar and the positive electrode lower busbar is 0.3-1.3 mm.

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

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

10. The positive electrode tab flow guide assembly according to claim 8 or 9, Features: The positive electrode lower busbar is evenly distributed in the radial direction with long holes (7) for conveniently injecting electrolyte into the battery cell shell, and the conductive spring is made of chromium zirconium copper or brass.

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