Large cylindrical lithium ion battery capable of improving thermal runaway

Abstract

The invention discloses a large cylindrical lithium ion battery capable of improving thermal runaway, and relates to the technical field of large cylindrical steel shell lithium batteries, the large cylindrical lithium ion battery capable of improving thermal runaway comprises a lithium ion battery capable of improving thermal runaway, a roll core and a shell bottom are arranged in the lithium ion battery capable of improving thermal runaway, and the large cylindrical lithium ion battery capable of improving thermal runaway further comprises a negative collector plate and a positive collector plate, according to the lithium ion battery capable of improving thermal runaway, the pressure relief nick is designed at the positive electrode end cap, and the pressure relief nick is designed at the negative electrode end shell bottom, so that compared with a traditional nick punched and formed by a punching machine, the nick machining method has the advantages that the good planeness of the shell bottom can be ensured by a machining method for removing materials; according to a traditional punching and nicking method, original materials at nicks move towards the edges of the nicks, so that the shell bottom is concave and convex, and finally, when a terminal client PACK welds a bus bar, a gap exists between the terminal client PACK and the shell bottom, and the welding quality can be affected badly.

Description

Technical Field

[0001] This invention relates to the field of large cylindrical steel-cased lithium battery technology, and more particularly to a large cylindrical lithium-ion battery that can improve thermal runaway. Background Technology

[0002] In existing technologies, large cylindrical steel-cased lithium batteries are susceptible to mechanical damage from abuse such as squeezing or puncture, which can cause structural deformation and rupture the separator. Electrical abuse, such as overcharging or over-discharging, can lead to the growth of lithium dendrites that puncture the separator. Thermal abuse can cause extreme internal temperatures that melt the separator. These extreme abuse processes can cause short circuits within the cell, ultimately leading to thermal runaway and dangerous consequences such as fire and explosion, endangering life and property. To prevent thermal runaway under abuse, large cylindrical steel-cased batteries typically incorporate a VENT (Voltage-Relief Device) at the cap's explosion-proof vent. When a short circuit occurs within the cell, the increased internal pressure due to gas generation opens the VENT groove at the cap to release pressure and prevent explosion. However, large cylindrical batteries have high energy density and capacity. When thermal runaway occurs, rapid internal gas generation and pressure increase can cause the VENT at the cap to fail in time, leading to cap failure, cap ejection, and the internal pressure causing the core to be ejected, resulting in fire and explosion.

[0003] Therefore, this invention proposes a large cylindrical lithium-ion battery that can improve thermal runaway and solve the above-mentioned problems. Summary of the Invention

[0004] The purpose of this application is to provide a large cylindrical lithium-ion battery that can improve thermal runaway, thereby solving the problems mentioned in the background art.

[0005] To achieve the above objectives, this application provides the following technical solution: a large cylindrical lithium-ion battery that can improve thermal runaway, comprising a lithium-ion battery for improving thermal runaway, wherein the lithium-ion battery for improving thermal runaway has a core and a bottom shell, and the large cylindrical lithium-ion battery for improving thermal runaway further includes: A negative current collector is disposed at the bottom of a lithium-ion battery to improve thermal runaway.

[0006] By incorporating the above structure, the thermal management performance of the lithium-ion battery with thermal runaway prevention can be effectively enhanced by introducing a negative current collector and placing it at the bottom of the battery. In the event of thermal runaway, the negative current collector can assist in heat dissipation, reduce heat accumulation, and thus slow down the rate of pressure increase inside the battery, avoiding the risk of fire or explosion caused by thermal runaway.

[0007] Preferably, the lithium-ion battery for improving thermal runaway has a cap on top, and a positive terminal VENT is provided on the top of the cap. The bottom of the lithium-ion battery for improving thermal runaway has a negative terminal VENT, and the opening pressure of the negative terminal VENT is greater than that of the positive terminal VENT.

[0008] Furthermore, the positive and negative VENTs are machined with grooves by removing material through mechanical processing. A custom-made forming milling cutter is used, with the positive VENT positioned at the top and its opening pressure lower than that of the negative VENT. This design allows the positive terminal to release pressure first when thermal runaway occurs in the lithium-ion battery designed to improve thermal runaway, ensuring the gradual release of internal pressure and reducing the risk of rupture caused by excessive instantaneous pressure. The negative VENT has a higher opening pressure, which can further release pressure under greater pressure, thus enhancing the safety of the lithium-ion battery designed to improve thermal runaway.

[0009] Preferably, the negative extreme VENT notch shape is C-shaped.

[0010] Furthermore, the groove is C-shaped with a connecting section to ensure that the steel sheet remains connected to the bottom of the casing after the groove is detonated, preventing it from bursting out and causing safety hazards. The negative end VENT uses a C-shaped groove, which helps optimize the pressure relief process. When the internal pressure of the battery increases, the C-shaped groove can effectively guide the pressure release path, improve the stability and safety of pressure relief, and prevent battery explosion or fire caused by the inability to release pressure in time.

[0011] Preferably, the negative current collector is disc-shaped, connected to the negative end of the winding core, and connected to the bottom of the lithium-ion battery casing to improve thermal runaway.

[0012] Furthermore, when the cell experiences thermal runaway, the bottom groove opens, and the negative current collector acts to block the core and prevent it from being ejected, effectively preventing the core from exploding. The negative current collector is connected to the negative end of the core and to the bottom of the casing, which helps improve the overall structural stability of the battery. It also helps the heat dissipation function of the negative current collector to be better utilized when thermal runaway occurs, reducing the accumulation of heat inside the battery.

[0013] Preferably, the negative current collector is provided with two circular holes and two arc-shaped grooves.

[0014] Furthermore, when thermal runaway occurs, the bottom of the casing is opened, and the sub-circular holes and arc grooves effectively increase the exhaust area, which can effectively relieve pressure. The negative current collector is equipped with two circular holes and two arc grooves. The ingenious design can effectively increase the heat dissipation area of ​​the negative current collector, thereby improving the thermal management capability of the battery during operation. When the battery is working, it can better disperse heat and reduce the probability of thermal runaway.

[0015] Preferably, both the negative current collector and the shell bottom are provided with negative current collector and shell bottom welds, and the negative current collector and shell bottom welds adopt a three-segment spiral overlapping form.

[0016] Furthermore, the use of a three-segment spiral overlapping weld pattern can achieve effective melting depth and width, thereby firmly and reliably welding the bottom of the casing to the negative current collector. This welding design ensures a more stable connection between the negative current collector and the bottom of the casing, reduces potential welding defects during the welding process, and improves the structural safety and reliability of the battery. In particular, it ensures that the battery structure is not prone to breakage during thermal runaway.

[0017] Preferably, the lithium-ion battery for improving thermal runaway is model 40135, with a height of 135mm, a diameter of φ40.2mm, a capacity of 20Ah, a positive terminal VENT opening pressure design of 1.9±0.2Mpa, and a negative terminal VENT opening pressure design of 2.9±0.4Mpa.

[0018] Furthermore, the lithium-ion battery model 40135, which improves thermal runaway, has a higher capacity, and the opening pressure of the positive and negative terminals VENT has been carefully designed to better cope with abnormal situations such as internal short circuits. In the event of an internal short circuit or thermal runaway, the battery can release gas pressure more quickly and effectively, avoiding fires or explosions caused by excessive pressure.

[0019] Preferably, the negative current collector is made of nickel-plated copper, with a diameter of φ38.5mm and a thickness of 0.3mm. The weld depth between the negative current collector and the bottom of the shell is 0.1mm, the weld width is 0.2mm, and the welding tensile force is ≥200N.

[0020] Furthermore, the negative current collector is made of nickel-plated copper, and the welding process is strictly controlled to ensure the strength of the weld joint and good electrical connection performance. The use of nickel-plated copper can enhance the conductivity of the negative current collector and improve its corrosion resistance. Compared with the traditional stamping method, the grooves made by machining to remove material can better maintain the flatness of the bottom of the shell and reduce gap problems in the welding process, thereby improving the welding quality and the overall reliability of the battery.

[0021] In summary, the technical effects and advantages of this invention are as follows: This invention designs pressure relief grooves at both the positive and negative terminals, with the pressure of the negative terminal groove being greater than that of the positive terminal groove. When the battery cell experiences thermal runaway due to misuse, the positive terminal groove opens first to release pressure. As the internal pressure of the battery cell continues to increase, the negative terminal groove then opens. This simultaneous pressure relief at both ends ensures that the battery does not catch fire or explode. The grooves on the bottom of the steel casing are machined by removing material. Compared to traditional stamping, the advantage of machined grooves is that the material removal process ensures a good flatness of the bottom. With traditional stamping, the original material at the groove will migrate to the edge of the groove, causing unevenness on the bottom. This gap between the current collector and the bottom when the PACK is soldered to the customer will negatively affect the soldering quality. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the structure of a lithium-ion battery for improving thermal runaway according to an embodiment of this application; Figure 2 This is an enlarged view of structure A in an embodiment of this application; Figure 3 This is an enlarged view of structure B in an embodiment of this application; Figure 4 This is an enlarged view of the C structure in an embodiment of this application; Figure 5 This is a schematic diagram of the negative electrode current collector in an embodiment of this application; Figure 6 This is a schematic diagram of the structure of the negative end VENT, negative current collector, and bottom weld bead in an embodiment of this application.

[0023] In the diagram: 1. Lithium-ion battery with improved thermal runaway; 2. Positive VENT; 3. Negative VENT; 4. Negative current collector; 5. Weld between negative current collector and bottom of the casing. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Example

[0025] refer to Figure 1-6 This embodiment proposes a large cylindrical lithium-ion battery that can improve thermal runaway, including a lithium-ion battery 1 for improving thermal runaway, wherein the lithium-ion battery 1 for improving thermal runaway has a core and a bottom shell, and the large cylindrical lithium-ion battery for improving thermal runaway also includes: The negative current collector 4 is located at the bottom of the lithium-ion battery 1 to improve thermal runaway.

[0026] As a preferred embodiment of this invention, the lithium-ion battery 1 with improved thermal runaway can effectively enhance its thermal management performance by introducing a negative current collector 4 and placing it at the bottom of the lithium-ion battery 1 with improved thermal runaway. In the event of thermal runaway, the negative current collector 4 can play a role in assisting heat dissipation, reducing heat accumulation, thereby reducing the rate of increase in internal pressure of the lithium-ion battery 1 with improved thermal runaway, and avoiding the risk of fire or explosion caused by thermal runaway.

[0027] In this embodiment, the top of the lithium-ion battery 1 with improved thermal runaway is provided with a cap, and the top of the cap is provided with a positive terminal VENT2. The bottom of the lithium-ion battery 1 with improved thermal runaway is provided with a negative terminal VENT3. The opening pressure of the negative terminal VENT3 is greater than that of the positive terminal VENT2. The positive terminal VENT2 and the negative terminal VENT3 are machined with grooves by removing material through mechanical processing. A customized forming milling cutter is used. The positive terminal VENT2 is set at the top, and its opening pressure is lower than that of the negative terminal VENT3. This design allows the positive terminal of the lithium-ion battery 1 with improved thermal runaway to release pressure first when thermal runaway occurs, ensuring the gradual release of internal pressure and reducing the risk of rupture caused by excessive instantaneous pressure. The negative terminal VENT3 has a higher opening pressure, which can play a further role in releasing pressure under greater pressure, thereby enhancing the safety of the lithium-ion battery 1 with improved thermal runaway.

[0028] In this embodiment, the negative terminal VENT3 has a C-shaped groove with a connecting section to ensure that the steel sheet remains connected to the bottom of the casing after the groove is detonated, preventing it from bursting out and causing safety hazards. The C-shaped groove of the negative terminal VENT3 helps optimize the pressure relief process. When the internal pressure of the battery increases, the C-shaped groove can effectively guide the pressure release path, improve the stability and safety of pressure relief, and prevent the battery from exploding or catching fire due to the inability to release pressure in time.

[0029] In this embodiment, the negative current collector 4 is disc-shaped and connected to the negative end of the winding core. It is also connected to the bottom of the lithium-ion battery 1, which improves thermal runaway. When thermal runaway occurs in the cell, the bottom groove opens and the negative current collector 4 blocks the winding core to prevent it from being ejected, thus effectively preventing the winding core from exploding. The connection between the negative current collector 4 and the negative end of the winding core and the bottom of the casing helps to improve the overall structural stability of the battery. It also helps to better exert the heat dissipation effect of the negative current collector 4 when thermal runaway occurs, reducing the accumulation of heat inside the battery.

[0030] In this embodiment, the negative current collector 4 is provided with two circular holes and two arc-shaped grooves. When thermal runaway occurs, the bottom grooves open, and the secondary circular holes and arc-shaped grooves effectively increase the exhaust area, which can effectively relieve pressure. The negative current collector 4 is cleverly designed with two circular holes and two arc-shaped grooves, which can effectively increase the heat dissipation area of ​​the negative current collector 4, thereby improving the thermal management capability of the battery during operation. When the battery is working, it can better disperse heat and reduce the probability of thermal runaway.

[0031] In this embodiment, both the negative current collector 4 and the bottom of the casing are provided with negative current collector and bottom casing welds 5. The negative current collector and bottom casing welds 5 adopt a three-segment spiral overlapping form. The three-segment spiral overlapping weld form can achieve an effective melting depth and width, thereby firmly and reliably welding the bottom of the casing and the negative current collector 4. This welding design ensures that the connection between the negative current collector 4 and the bottom of the casing is more stable, reduces welding defects that may occur during the welding process, and improves the structural safety and reliability of the battery. Especially in the event of thermal runaway, it ensures that the battery structure is not prone to breakage.

[0032] In this embodiment, the lithium-ion battery 1 with improved thermal runaway is model 40135, with a height of 135mm, a diameter of φ40.2mm, and a capacity of 20Ah. The positive terminal VENT2 opening pressure is designed to be 1.9±0.2Mpa, and the negative terminal VENT3 opening pressure is designed to be 2.9±0.4Mpa. The lithium-ion battery 1 with improved thermal runaway is model 40135, which has a high capacity. Moreover, the opening pressures of the positive terminal VENT2 and the negative terminal VENT3 are carefully designed to better cope with abnormal situations such as internal short circuits. In the case of internal short circuits or thermal runaway, the battery can release gas pressure more quickly and effectively, avoiding fires or explosions caused by excessive pressure.

[0033] In this embodiment, the negative current collector 4 is made of nickel-plated copper, with a diameter of φ38.5mm and a thickness of 0.3mm. The weld depth between the negative current collector and the bottom of the casing 5 is 0.1mm, the weld width is 0.2mm, and the welding tensile force is ≥200N. The negative current collector 4 is made of nickel-plated copper, and the welding process is strictly controlled to ensure the strength of the weld joint and good electrical connection performance. The use of nickel-plated copper can enhance the conductivity of the negative current collector 4 and improve its corrosion resistance. Compared with the traditional stamping method, the grooves made by removing material through machining can better maintain the flatness of the bottom of the casing, reduce gap problems during the welding process, and thus improve the welding quality and the overall reliability of the battery.

[0034] The following table compares the conventional and experimentally prepared results:

[0035] Working principle: The bottom of the steel shell is machined with grooves by removing material through mechanical processing. A custom forming milling cutter is used. The steel shell is nickel-plated. The core is welded to the positive current collector and negative current collector 4. The positive end of the core is wrapped with high-temperature tape. The core is inserted into the shell, and bottom penetration welding is performed to weld the bottom of the shell to the negative current collector 4 of the core. The cell undergoes processes such as grooving, drying, electrolyte injection, cap welding, mechanical forming and sealing, cleaning, oiling and drying, heat shrinking and coding, formation, and the finished cell is off the production line. Selected cells are subjected to thermal runaway testing. By designing a positive end VENT2 pressure relief groove at the positive end cap of the lithium-ion battery 1 to improve thermal runaway, and simultaneously designing a negative end VENT3 pressure relief groove at the bottom of the shell, the rupture pressure of the negative end VENT3 groove at the bottom of the shell is greater than the pressure relief pressure of the positive end VENT2 groove at the cap. When the thermal runaway of the lithium-ion battery 1 is improved, the rupture pressure of the negative end VENT3 groove at the bottom of the shell is greater than the pressure relief pressure of the positive end VENT2 groove at the cap. When an internal short circuit occurs in lithium-ion battery 1, the internal gas pressure increases. The positive terminal VENT2 at the cap first releases pressure, and as the internal pressure of lithium-ion battery 1 continues to increase, the negative terminal VENT3 at the bottom of the casing ruptures to release pressure a second time. This quickly releases the internal pressure and prevents lithium-ion battery 1 from catching fire or exploding due to untimely internal gas depressurization. The grooves on the bottom of the casing are formed by mechanical processing to remove material. Compared with the traditional stamping process, the advantage of mechanical processing is that the material removal process can ensure a good flatness of the bottom of the casing. With the traditional stamping method, the original material at the groove will move towards the edge of the groove, causing the bottom of the casing to be uneven. When the end customer welds the busbar to the bottom of the casing, there will be a gap, which will have an adverse effect on the welding quality.

[0036] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A large cylindrical lithium-ion battery for improving thermal runaway, comprising a lithium-ion battery (1) for improving thermal runaway, wherein the lithium-ion battery (1) for improving thermal runaway has a core and a shell bottom, characterized in that, This large cylindrical lithium-ion battery, which can improve thermal runaway, also includes: A negative current collector (4) is disposed at the bottom of the lithium-ion battery (1) for improving thermal runaway.

2. The large cylindrical lithium-ion battery with improved thermal runaway according to claim 1, characterized in that, The lithium-ion battery (1) for improving thermal runaway is provided with a cap on top, and a positive terminal VENT (2) is provided on the top of the cap. The lithium-ion battery (1) for improving thermal runaway is provided with a negative terminal VENT (3) at the bottom. The opening pressure of the negative terminal VENT (3) is greater than that of the positive terminal VENT (2).

3. A large cylindrical lithium-ion battery with improved thermal runaway according to claim 1, characterized in that, The negative extreme VENT (3) has a C-shaped notch.

4. A large cylindrical lithium-ion battery with improved thermal runaway according to claim 1, characterized in that, The negative current collector (4) is disc-shaped and is connected to the negative end of the core. The negative current collector (4) is also connected to the bottom of the lithium-ion battery (1) which improves thermal runaway.

5. A large cylindrical lithium-ion battery with improved thermal runaway according to claim 1, characterized in that, The negative collector disk (4) is provided with two circular holes and two circular arc grooves.

6. A large cylindrical lithium-ion battery with improved thermal runaway according to claim 1, characterized in that, Both the negative current collector (4) and the shell bottom are provided with negative current collector and shell bottom weld (5), and the negative current collector and shell bottom weld (5) adopt a three-segment spiral overlapping form.

7. A large cylindrical lithium-ion battery with improved thermal runaway according to claim 1, characterized in that, The lithium-ion battery (1) for improving thermal runaway is model 40135, with a height of 135mm, a diameter of φ40.2mm, and a capacity of 20Ah. The positive terminal VENT (2) is designed to have an opening pressure of 1.9±0.2Mpa, and the negative terminal VENT (3) is designed to have an opening pressure of 2.9±0.4Mpa.

8. A large cylindrical lithium-ion battery with improved thermal runaway according to claim 1, characterized in that, The negative current collector (4) is made of copper plated with nickel, with a diameter of φ38.5mm and a thickness of 0.3mm. The weld depth (5) between the negative current collector and the bottom of the shell is 0.1mm, the weld width is 0.2mm, and the welding pull force is ≥200N.

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