Cylindrical full-tab battery and method of manufacturing the same

Abstract

The application discloses a cylindrical full-tab battery and a preparation method thereof, and belongs to the technical field of secondary batteries.The cylindrical full-tab battery comprises a current collecting cover, a full-tab winding core, positive and negative tab ends provided at two axial ends of the full-tab winding core, and a cylindrical conductive shell with an open end, wherein one of the tab ends is welded to the current collecting cover, the cylindrical conductive shell is closed at the open end and is isolated by an insulating ring, and the other tab end of the full-tab winding core is welded to the closed end of the cylindrical conductive shell.The application can improve the product performance and the production efficiency.

Description

Technical Field

[0001] This invention relates to a technology in the field of secondary batteries, specifically a cylindrical all-tab battery and its preparation method. Background Technology

[0002] Cylindrical batteries excel in many aspects, including battery consistency, energy density, and durability, and are widely used in various fields. In particular, cylindrical all-tab batteries offer high power performance and have even broader application scenarios. Therefore, the structural design and manufacturing requirements for cylindrical batteries are also quite high.

[0003] The current collector cover structure of cylindrical batteries includes insulating components and electrode welding adapters. Battery manufacturing requires complex processes such as flattening or folding the electrodes, welding the adapters, bending the adapters, and sealing the welds. This significantly impacts production efficiency. The flattening process easily wrinkles the separator, leading to self-discharge and short circuits. The folding process requires additional equipment for laser cutting and stacking the electrodes, increasing costs. Furthermore, laser cutting of the electrodes easily generates welding slag, causing internal short circuits and self-discharge. Both flattening and folding require welding to the flattened / folded surfaces and the current collector adapters, which can easily burn the separator and leave residual welding slag, leading to internal short circuits and self-discharge. Additionally, the electrode welding process also easily generates metallic welding slag. These are major culprits for self-discharge, short circuits, poor battery consistency, and reduced durability in cylindrical batteries.

[0004] The present invention is made to address the aforementioned problems existing in the prior art. Summary of the Invention

[0005] To address the aforementioned shortcomings of existing technologies, this invention proposes a cylindrical all-tab battery and its preparation method, which can improve product performance and production efficiency.

[0006] This invention relates to a cylindrical all-tab battery, comprising:

[0007] collector cover;

[0008] Fully paddle winding core; the fullly paddle winding core is provided with a positive pole lug end and a negative pole lug end at both ends of the axial direction, one of the pole lug ends being welded to the current collector cover; preferably, the welded part is covered with insulating tape to protect the weld point and prevent short circuit;

[0009] A cylindrical conductive shell with one open end and the other closed end is used for core insertion and electrolyte filling; the cylindrical conductive shell is set at the open end and closed at the current collector cover and is isolated and insulated by an insulating ring, and is welded to the other end of the full-pole core at the closed end.

[0010] In some preferred embodiments, the current collection cover includes a conductive cover body and a current collection ring;

[0011] A liner is fixed inside the conductive cover, forming a closed space between the two. The liner is equipped with an explosion-proof structure.

[0012] The current collector ring is fixedly connected to the conductive cover and sealed by a sealing element.

[0013] In some preferred embodiments, the explosion-proof structure includes a pressure relief hole and an explosion-proof plate. The pressure relief hole is disposed on the liner, and the explosion-proof plate is disposed on the side of the pressure relief hole away from the enclosed space. The diameter of the pressure relief hole is designed according to the battery capacity and explosion-proof pressure. When the explosion-proof plate bursts under pressure, it releases pressure to the outside of the enclosed space through the pressure relief hole, thereby preventing the battery from exploding. Preferably, the liner is welded to one end of the all-tab core.

[0014] In some preferred embodiments, the width of the tab end welded to the manifold cap matches the width of the manifold ring. Preferably, the width of the tab end is the same as that of the manifold ring; preferably, the thickness of the manifold ring is 0.3 to 0.5 mm, for example, 0.3 mm, 0.4 mm, 0.5 mm, etc.

[0015] In some preferred embodiments, the full-electrode core includes a first diaphragm, a first electrode sheet, a second diaphragm, and a second electrode sheet stacked and wound together. One of the first and second electrode sheets serves as a positive electrode sheet, having a positive active material region and a positive blank region; the other serves as a negative electrode sheet, correspondingly having a negative active material region and a negative blank region. The positive blank region serves as the positive electrode tab end in the wound full-electrode core, and the negative blank region serves as the negative electrode tab end. The welding connection between the tab end and the current collector cover and the closed end of the conductive shell can be either a welding connection of the outermost ring of the tab end to the aforementioned structure, or a welding connection of the entire blank region of the tab end to the aforementioned structure. A complete welding connection is beneficial for improving conductivity; preferably, electromagnetic pulse welding is used to improve welding quality and avoid welding defects.

[0016] More preferably, the axial widths of the positive electrode tab and the negative electrode tab are 1 to 10 mm, respectively. For example, the width of the positive electrode tab is 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, etc., and the width of the negative electrode tab is 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, etc.

[0017] Preferably, the conductive shell is made of stainless steel or aluminum alloy; the conductive cover is made of carbon steel with a nickel-plated surface and a thickness of 0.5 to 1 mm; the liner is made of aluminum sheet with a thickness of 0.5 mm; and the seal is made of polypropylene.

[0018] This invention relates to a method for preparing the above-mentioned cylindrical all-tab battery, comprising the following steps:

[0019] Preparation of the all-polar ear roll core: Prepare two electrode substrates according to the design dimensions. Coat the positive electrode active material and negative electrode active material on the two electrode substrates respectively to form the first electrode sheet and the second electrode sheet. One of the first electrode sheet and the second electrode sheet serves as the positive electrode sheet and has a positive electrode active material area and a positive electrode blank area. The other serves as the negative electrode sheet and has a corresponding negative electrode active material area and a negative electrode blank area. Stack them in the order of the first diaphragm, the first electrode sheet, the second diaphragm, and the second electrode sheet. The positive electrode active material area and the negative electrode active material area overlap vertically. The positive electrode blank area and the negative electrode blank area are set on both sides of the overlapping part. Then, wind them to obtain the all-polar ear roll core.

[0020] Cell grooving: The core is grooved after being placed into the housing;

[0021] Positive electrode tab welding: The positive electrode tab of the full-pole core is fixed to the current collector by electromagnetic pulse welding;

[0022] Negative electrode tab welding: The negative electrode tab of the full-pole core is fixed to the cylindrical conductive shell by electromagnetic pulse welding;

[0023] Add electrolyte: Inject electrolyte through the gap between the top of the cylindrical conductive shell and the current collector cover;

[0024] Closed-end sealing: After adding electrolyte, seal the cylindrical conductive shell and the current collector cap;

[0025] Formation: The closed-encapsulated battery is formed to obtain a cylindrical all-tab battery.

[0026] In some preferred embodiments, the process parameters for electromagnetic pulse welding are: welding current of 200–1000 kA, voltage of 10–16 kV, and frequency of 10–15 kHz. For example, welding currents of 200 kA, 300 kA, 400 kA, 500 kA, 600 kA, 700 kA, 800 kA, 900 kA, and 1000 kA; voltages of 10 kV, 11 kV, 12 kV, 13 kV, 14 kV, 15 kV, and 16 kV; and frequencies of 10 kHz, 11 kHz, 12 kHz, 13 kHz, 14 kHz, and 15 kHz.

[0027] In some preferred embodiments, the electrolyte injection pressure is 0.1–0.9 kgf / m³. 2 For example, a pressure of 0.1 kgf / m 2 0.2 kgf / m 2 0.3 kgf / m 2 0.4 kgf / m 20.5 kgf / m 2 0.6 kgf / m 2 0.7 kgf / m 2 0.8 kgf / m 2 0.9 kgf / m 2 wait.

[0028] The theoretical values ​​for the injection port area, maximum current-conducting surface area, maximum heat-conducting surface area, and maximum current of the cylindrical all-tab battery are calculated as follows (area units are all in mm). 2 ):

[0029] Injection port area S1=π×D1 2 / 4, D1 is the inner diameter of the conductive shell;

[0030] The maximum current-conducting area S2 of the positive electrode is the area connected to the positive electrode tab end, S2=π×D2×T, where D2 is the diameter of the outermost full tab circular surface of the positive electrode, and T is the thickness of the current collector ring;

[0031] The maximum conductive surface area of ​​the negative electrode is S3 = S1;

[0032] The maximum heat-conducting surface area of ​​the positive electrode is S4 = S2;

[0033] The maximum heat-conducting surface area of ​​the negative electrode is S5 = S3;

[0034] According to GB 4706.1-1992 / 1998 "Safety of Household and Similar Electrical Appliances" and battery design requirements, the current carrying capacity of aluminum is taken as 7.5A / mm². 2 The current carrying capacity of copper is taken as 11.5A / mm. 2 Therefore, the maximum current that the aluminum substrate of the cylindrical all-tab battery can theoretically carry is S2×7.5A, and the maximum current that the copper substrate can theoretically carry is S3×11.25A.

[0035] By adopting the structural design of this invention, the maximum current-conducting surface area, maximum heat-conducting surface area, and maximum current of the cylindrical battery can be made closer to the theoretical values.

[0036] Technical effect

[0037] Compared with the prior art, the present invention has the following technical effects:

[0038] 1) The two ends of the all-tab core are welded to the current collector and the conductive shell respectively, eliminating the need for flattening and cutting processes. Compared with the process of flattening, cutting and welding the current collector, the maximum current conduction area and maximum heat conduction area of ​​the cylindrical all-tab battery are closer to the theoretical value. Through full-section current conduction of the positive and negative electrodes, the charge and discharge rate, thermal conductivity, heat conduction area and current conduction area of ​​the battery are maximized.

[0039] 2) Electromagnetic pulse welding is used, which avoids the problems of internal short circuits and self-discharge caused by welding slag during the welding of electrode tabs by laser welding and other methods, as well as the problems of internal short circuits and self-discharge caused by separator burns and residual welding slag during the flattening and stacking of electrode sheets; thus greatly improving the self-discharge and short circuit phenomenon of the battery, and improving product consistency and safety.

[0040] 3) When sealing, mechanical grooving is used to seal the battery, avoiding the short circuit caused by residual welding slag due to welding sealing.

[0041] 4) During the manufacturing process, liquid can be injected into the gap between the current collector and the conductive shell. The electrolyte is injected under pressure through a large-area injection channel, which improves production efficiency.

[0042] 5) The explosion-proof structure of the positive electrode current collector improves the safety of the large cylindrical battery;

[0043] 6) It reduces the number of processes such as kneading or cutting and folding, and bending of the tabs, simplifying the production process, effectively reducing production costs, and making it suitable for large-scale production. Attached Figure Description

[0044] Figure 1 This is an exploded view of the battery structure in Example 1;

[0045] Figure 2 This is a schematic diagram of the electrode structure in Example 1;

[0046] Figure 3 This is a schematic diagram of the all-polar lug core structure in Example 1;

[0047] Figure 4 This is a schematic diagram of the flow collection cover structure in Example 1;

[0048] 1. Cylindrical wound core with full tabs; 2. Positive current collector cover; 3. Conductive housing; 4. Insulating ring;

[0049] 11. Positive electrode plate; 12. Negative electrode plate; 13. Diaphragm; 14. Positive electrode tab; 15. Negative electrode tab;

[0050] 21. Conductive cover; 22. Current collector ring; 23. Sealing ring; 24. Liner; 25. Pressure relief hole; 26. Explosion-proof plate;

[0051] 101. Coating area; 102. Blank area. Detailed Implementation

[0052] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. Experimental methods not specified in the embodiments were performed according to conventional methods and conditions.

[0053] This embodiment fabricates a 40140-15Ah cylindrical all-tab sodium-ion battery, including an all-tab cylindrical core 1, a positive electrode current collector 2, and a conductive casing 3, as shown below. Figure 1 As shown. The battery materials involved are the same as those used in commercially available 40140-15Ah cylindrical sodium-ion batteries.

[0054] The specific parameters of a commercially available standard 40140-15Ah cylindrical sodium-ion battery are as follows:

[0055] I. Positive Electrode: ① The positive electrode active material is layered sodium oxide, with a specific capacity of 125–130 mAh / g; ② The thickness of the aluminum foil for the positive electrode current collector is 8–10 μm; ③ The surface density of the single-sided coating on the positive electrode sheet is 20–24 mg / cm³. 2 The compacted density is 3.0–3.2 mg / cm³. 3 ④ The thickness of the positive electrode aluminum or copper busbar is 0.2–0.3 mm, the width is 12–15 mm, and the maximum current-carrying area is 2.4–4.5 mm². 2 ;

[0056] II. Negative Electrode: ① The active material of the negative electrode is hard carbon, with a specific capacity of 280–300 mAh / g; ② The thickness of the aluminum foil for the negative electrode current collector is 8–10 μm; ③ The surface density of the single-sided coating of the positive electrode sheet is 9–11 mg / cm³. 2 The compacted density is 0.9–1.0 mg / cm³. 3 ④ The current-carrying area for negative electrode penetration soldering is 15-30 mm². 2 ;

[0057] III. Diaphragm: Diaphragm thickness 10-15 μm;

[0058] IV. Electrolyte: The amount of electrolyte is 3-4 g / Ah;

[0059] V. Housing: Stainless steel or aluminum housing, φ40mm×140~142mm;

[0060] VI. Individual cell: ① Specifications: φ40mm×140mm, ② Nominal capacity: 15Ah, ③ Operating voltage: 1.5~3.95V, ④ Nominal voltage: 3.0V, ⑤ Energy density: 110~120Wh / kg, ⑥ Discharge rate: 1~3C.

[0061] like Figure 1 , Figure 2 and Figure 3As shown, the cylindrical core 1 with full tabs of the present invention is formed by stacking and winding diaphragm 13, negative electrode 12, diaphragm 13, positive electrode 11, and diaphragm 13. The positive electrode 11 and the negative electrode 12 are provided with a coating area 101 and a blank area 102. The positive electrode coating area is coated with a positive active material, and the negative electrode coating area is coated with a negative active material. After winding, the blank area serves as the tab end of the full tab core. After winding, the positive electrode tab end 14 and the negative electrode tab end 15 are located at the two ends of the axial direction of the full tab core, and the height of the tab end is 3mm.

[0062] The cylindrical multi-layer full-pole core electrode welding of the present invention first welds the positive electrode tab end 14 to the positive electrode current collector 2, and then welds the negative electrode tab end 15 to the conductive shell 3. The welding method is electromagnetic pulse welding, with a welding current of 200kA, a voltage of 11kV, and a frequency of 10kHz.

[0063] The positive current collector cover 2 includes a conductive cover body 21 and a current collector ring 22, which are fixedly connected and sealed by a sealing ring 23; a liner 24 is fixed inside the conductive cover body 21, and the conductive cover body 21 protrudes relative to the liner 24 to form a closed space between the two; a pressure relief hole 25 is provided on the liner 24, and an explosion-proof sheet 26 is provided on the side of the pressure relief hole 25 away from the closed space.

[0064] An insulating ring 4 is fitted after welding the positive electrode tab 14 to the positive electrode current collector 2 to isolate the positive and negative electrodes and prevent short circuits between them. The electromagnetic pulse welding method used does not damage the core of the full-tab welding, avoiding problems such as diaphragm damage and the generation of metal particles caused by other welding methods. This overcomes the battery short circuits or self-discharges caused by these methods, improving the battery's safety performance. Furthermore, the welding of the positive and negative electrodes provides the maximum current-conducting and heat-conducting area, thereby improving the battery's high-rate and long-cycle life performance.

[0065] The grooving described in this invention involves grooving the positive current collector cover 2 and the conductive housing 3 after the negative electrode tab 15 is welded to the conductive housing 3. During grooving, a positioning device is installed at the positive electrode end to prevent the inner core of the conductive housing from moving axially. After grooving, mechanical sealing is performed. The grooving and mechanical sealing processes are designed based on the end face diameter of the positive current collector cover and the inner diameter of the housing.

[0066] The cylindrical all-tab battery of this invention uses 0.3 kgf / m 2 Pressure injection.

[0067] 2000 40140-15Ah cylindrical all-tab sodium-ion batteries manufactured in this embodiment were compared with 2000 40140-15Ah cylindrical sodium-ion batteries prepared using the flattening-welding process:

[0068] 1) The welding short-circuit rate was reduced from 300ppm to 5ppm, and the battery self-discharge rate was reduced from 200ppm to 50ppm;

[0069] 2) Battery parameters and performance are shown in Tables 1, 2 and 3.

[0070] Table 1. Parameters and performance (average values) of 40140-15Ah cylindrical sodium-ion battery using the flattening-welding process.

[0071] Maximum width of positive end face busbar (mm) Positive electrode copper busbar thickness (mm) <![CDATA[Maximum current-carrying area of the positive electrode, mm 2 > Maximum design current A at the positive terminal Negative extreme surface penetration diameter (mm) Negative electrode penetration solder joint diameter (mm) <![CDATA[Maximum current-carrying area of the negative electrode, mm 2 > Maximum design current A of negative electrode Measured current A (3C) at positive and negative terminals 16.0 0.25 4 45 36.0 0.25 28.4 319.5 45

[0072] Table 2. Parameters and performance (average values) of the 40140-15Ah cylindrical sodium-ion battery of this invention.

[0073] Positive busbar diameter (mm) Positive electrode aluminum busbar thickness (mm) <![CDATA[Maximum current-carrying area of the positive electrode, mm 2 > Maximum design current A at the positive terminal Positive busbar diameter (mm) Positive busbar thickness (mm) <![CDATA[Maximum current-carrying area of the negative electrode, mm 2 > Maximum design current A of negative electrode Measured current A (14C) at positive and negative terminals 39.0 0.3 36.7 275.5 39.0 0.3 36.7 413.3 210

[0074] Table 3 Comparison of rate discharge temperature rise of 40140-15Ah cylindrical sodium-ion batteries using this process and the flattening-welding process (average values)

[0075]

[0076] Compared with the flattening-welding process, the charge / discharge rate of this invention is increased from 3C in the comparative example to 14C in the embodiment. The measured current of the positive and negative electrodes is increased from 14.08% of the theoretical value to 50.81% of the maximum design current of the negative electrode, indicating that the maximum current-conducting area of ​​this invention is closer to the theoretical value and has better battery performance. The theoretical heat conduction of 275.5² / (45÷11.25×7.5)²=84.33 is significantly improved, which can significantly improve battery performance, extend battery life and improve battery safety. In addition, under the same charge / discharge rate, the capacity retention rate remains unchanged, while the temperature rise limit is reduced, resulting in better safety.

[0077] It should be emphasized that the above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any way. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for preparing a cylindrical all-tab battery, characterized in that, Includes the following steps: Preparation of the all-polar ear core: Positive and negative active materials are coated on two electrode substrates respectively to form a first electrode sheet and a second electrode sheet. One of the first and second electrode sheets serves as the positive electrode sheet, with a positive active material area and a positive blank area, while the other serves as the negative electrode sheet, with a corresponding negative active material area and a negative blank area. The first diaphragm, the first electrode sheet, the second diaphragm, and the second electrode sheet are stacked in the order of stacking, with the positive and negative active material areas overlapping vertically, and the positive and negative blank areas located on both sides of the overlapping area. The all-polar ear core is then wound. Cell grooving: The core is grooved after being placed into the housing; Positive electrode tab welding: The positive electrode tab of the full-pole core is welded and fixed to the current collector cover by electromagnetic pulse welding. After the positive electrode tab is welded to the current collector cover, an insulating ring is put on it. Negative electrode tab welding: The negative electrode tab of the full-pole core is welded and fixed to the cylindrical conductive shell by electromagnetic pulse welding; Adding electrolyte: After welding the positive and negative electrode tabs, inject electrolyte through the gap between the cylindrical conductive shell and the current collector cover; Closed-end sealing: After adding electrolyte, seal the cylindrical conductive shell and the current collector cap; Formation: The closed-loop encapsulation of the battery is formed to obtain a cylindrical all-tab battery; The process parameters for electromagnetic pulse welding are: welding current of 200-1000kA, voltage of 10-16kV, and frequency of 10-15kHz.

2. The preparation method according to claim 1, characterized in that, The pressure of the added electrolyte is 0.1–0.9 kgf / m³. 2 .

3. The preparation method according to claim 1, characterized in that, The manifold includes: Conductive cover: A liner is fixed inside the conductive cover, forming a closed space between the two, and the liner is provided with an explosion-proof structure; Current collector ring: The current collector ring is fixedly connected to the conductive cover and sealed by a sealing element.

4. The preparation method according to claim 3, characterized in that, The explosion-proof structure includes a pressure relief hole and an explosion-proof plate. The pressure relief hole is located on the lining, and the explosion-proof plate is located on the side of the pressure relief hole away from the enclosed space.

5. The preparation method according to claim 3, characterized in that, The liner is welded to the end of the first electrode of the full-electrode winding core.

6. The preparation method according to claim 1, characterized in that, The width of the tab end that is welded to the manifold cover is the same as the width of the manifold ring.

7. A cylindrical all-tab battery, characterized in that, It is prepared by any one of the preparation methods described in claims 1 to 6.

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