Prismatic secondary battery having venting device

Abstract

The disclosed invention relates to a prismatic secondary battery in which an electrode terminal is provided on a cap plate on an upper surface, a venting device is provided on a bottom surface of a housing, and an electrode assembly is accommodated in the housing. In one embodiment, an upper structure filling the space between the electrode assembly and the cap plate is provided in the housing.

Description

Prismatic secondary battery equipped with a venting device

[0001] The present invention relates to a prismatic secondary battery.

[0002] This application claims the benefit of priority based on Korean Patent Application No. 10-2025-0004741 filed on January 13, 2025, and all contents disclosed in the document of said Korean patent application are incorporated herein as part of this specification.

[0003] Unlike primary batteries, secondary batteries are rechargeable and allow for both miniaturization and high capacity, leading to research and development in various directions. The demand for secondary batteries as an energy source is increasing rapidly due to the growing technological development and demand for mobile devices, as well as the rise of electric vehicles and energy storage systems in line with the contemporary need for environmental protection.

[0004] Secondary batteries are classified into coin-type, cylindrical-type, prismatic-type, and pouch-type batteries based on the shape of the battery case. In secondary batteries, the electrode assembly mounted inside the battery case is a power generation device capable of charging and discharging, consisting of a stacked structure of electrodes and separators. The electrode assembly can be roughly classified into a jelly roll type, which is wound with a separator interposed between sheet-type positive and negative electrodes coated with active material; a stack type, which is sequentially stacked with multiple positive and negative electrodes interposed by a separator; and a stack and folding type, which is formed by winding stack-type unit cells with a long separator.

[0005] Prismatic secondary batteries offer relatively high energy density, but this raises concerns regarding structural stability, which remains a challenge to be addressed. For example, a technology has been disclosed that aims to suppress the increase in electrical resistance by minimizing the welding points connecting the terminals and the internal electrode assembly; as an example of this, one may refer to Korean Patent Publication No. 2019-0102816.

[0006] The present invention provides a prismatic secondary battery equipped with an auxiliary mechanism that activates the venting device to operate smoothly when a thermal event occurs.

[0007] However, the technical problems of the present invention are not limited to those described above, and other unmentioned problems will be clearly understood by a person skilled in the art from the description of the invention below.

[0008] The present invention relates to a prismatic secondary battery having an electrode terminal provided on a cap plate on the upper surface and a venting device provided on the lower surface of a housing, and accommodating an electrode assembly inside the housing. In one embodiment, an upper structure is provided inside the housing to fill the space between the electrode assembly and the cap plate.

[0009] The above upper structure may be an injection-molded product made of resin material.

[0010] The above upper structure may be made of an electrically insulating resin material.

[0011] In one embodiment, the upper structure may be filled with a foamed refractory material inside.

[0012] The above-mentioned foamed refractory agent can form an insulating layer by foam expansion due to heat when the temperature inside the housing exceeds a preset temperature.

[0013] In one embodiment, the inner bottom surface of the housing may be provided with a lower structure that surrounds the venting device and supports the electrode assembly, and the lower structure has a plurality of through holes formed therein.

[0014] The above-mentioned lower structure may be provided with a protective film made of an insulating material on the surface in contact with the electrode assembly.

[0015] The above protective film may rupture when an external pressure corresponding to the operating pressure of the venting device is applied, or may melt when the temperature inside the housing exceeds a preset temperature.

[0016] The above-mentioned lower structure is an arch-shaped structure that surrounds the venting device and can be supported by contacting a part of the bottom surface of the electrode assembly.

[0017] The above-mentioned lower structure is a folded structure that surrounds the venting device and can support the electrode assembly by contacting a part or the entire bottom surface.

[0018] The upper structure is partially equipped with an electrical conductor and can electrically connect the electrode lead of the electrode assembly and the electrode terminal of the cap plate.

[0019] The upper structure is made of a gas-impermeable material, so that gas generated from the electrode assembly can be blocked from coming into contact with the electrode terminal.

[0020] The above-mentioned foamed refractory agent can terminate the electrochemical reaction by filling the space inside the housing during foam expansion, thereby discharging gas and electrolyte to the outside through the venting device.

[0021] The above-mentioned substructure may be formed of a metal material having structural rigidity.

[0022] The above venting device includes a ruptured disc with a notch machined into a plate-shaped member made of metal material, and the notch portion can be broken and developed when the internal pressure of the housing increases.

[0023] A battery pack according to one embodiment of the present invention may include the prismatic secondary battery.

[0024] An automobile according to one embodiment of the present invention may include the battery pack.

[0025] In the prismatic secondary battery of the present invention, when a large amount of gas is generated in an electrode assembly immersed in an electrolyte due to the occurrence of a thermal event such as thermal runaway, the gas is prevented from flowing toward the electrode terminals by the upper structure filling the space between the electrode assembly and the cap plate and flows toward the venting device below. Accordingly, the pressure of the gas acts rapidly on the venting device, thereby causing the venting device to operate at the beginning of the thermal event.

[0026] In addition, by significantly reducing the high-temperature gas flowing into the electrode terminals where current is concentrated, problems such as flames rising above the prismatic secondary battery are prevented or suppressed.

[0027] Considering these points, the prismatic secondary battery of the present invention, equipped with an upper structure that fills the space between the electrode assembly and the cap plate, has improved safety in the event of a thermal event.

[0028] However, the technical effects obtainable through the present invention are not limited to those described above, and other unmentioned effects will be clearly understood by a person skilled in the art from the description of the invention below.

[0029] The following drawings attached to this specification illustrate embodiments of the present invention and serve to further enhance understanding of the technical concept of the present invention together with the description of the invention provided below; therefore, the present invention should not be interpreted as being limited only to the matters described in such drawings.

[0030] FIG. 1 is a perspective view illustrating the external appearance of a prismatic secondary battery according to one embodiment of the present invention.

[0031] FIG. 2 is a cross-sectional view taken along the line "AA" of FIG. 1.

[0032] FIG. 3 is a cross-sectional view according to another embodiment of the upper structure of FIG. 2.

[0033] FIG. 4 is a cross-sectional view of a prismatic secondary battery according to another embodiment of the present invention.

[0034] FIG. 5 is a cross-sectional view of a prismatic secondary battery according to another embodiment of the present invention.

[0035] FIG. 6 is a perspective view illustrating an example of a substructure provided in the prismatic secondary battery of FIG. 5.

[0036] FIG. 7 is a perspective view illustrating another example of a substructure.

[0037] FIG. 8 is a cross-sectional view of a prismatic secondary battery to which the lower structure of FIG. 7 is applied.

[0038] FIG. 9 is a perspective view of a battery pack including a prismatic secondary battery according to an embodiment of the present invention and an automobile.

[0039] In parts of the attached drawings, corresponding components are given the same reference numerals. Those skilled in the art understand that the drawings are intended to illustrate elements simply and clearly and are not necessarily drawn to scale. For example, to aid in understanding various embodiments, the dimensions of some elements depicted in the drawings may be exaggerated compared to others. Additionally, elements of known technology that are useful or essential in commercially viable embodiments may often be omitted so as not to hinder the spirit of the various embodiments of the present invention.

[0040] The present invention is capable of various modifications and may have various embodiments, and specific embodiments are to be described below.

[0041] However, this is not intended to limit the invention to specific embodiments, and it should be understood that it includes all modifications, equivalents, and substitutions that fall within the spirit and scope of the invention.

[0042] In the present invention, terms such as "comprising" or "having" are intended to specify the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not excluding in advance the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0043] Furthermore, in the present invention, when a part such as a layer, film, region, or plate is described as being "on" another part, this includes not only cases where it is "immediately above" the other part, but also cases where there is another part in between. Conversely, when a part such as a layer, film, region, or plate is described as being "under" another part, this includes not only cases where it is "immediately below" the other part, but also cases where there is another part in between. Additionally, in the present application, being "placed on" may include cases where it is placed on the lower part as well as on the upper part.

[0044]

[0045] Conventional prismatic secondary batteries have high energy density, so their housings are designed to be thick for safety. However, given the thickness of the housing, if a thermal event such as thermal runaway occurs and leads to an explosion, the damage can be severe. Therefore, prismatic secondary batteries are equipped with a venting device to prevent or suppress explosions, and to enhance the safety of these batteries, the smooth operation of the venting device must be guaranteed with high reliability.

[0046] Taking these points into consideration, the present invention provides a prismatic secondary battery equipped with an auxiliary mechanism that activates the venting device to operate smoothly when a thermal event occurs.

[0047]

[0048] The present invention relates to a prismatic secondary battery having an electrode terminal provided on a cap plate on the upper surface and a venting device provided on the lower surface of a housing, and accommodating an electrode assembly inside the housing. In one embodiment, an upper structure is provided inside the housing to fill the space between the electrode assembly and the cap plate.

[0049] In the prismatic secondary battery of the present invention, when a large amount of gas is generated in an electrode assembly immersed in an electrolyte due to the occurrence of a thermal event such as thermal runaway, the gas is prevented from flowing toward the electrode terminals by the upper structure filling the space between the electrode assembly and the cap plate and flows toward the venting device below. Accordingly, the pressure of the gas acts rapidly on the venting device, thereby causing the venting device to operate at the beginning of the thermal event.

[0050] In addition, by significantly reducing the high-temperature gas flowing into the electrode terminals where current is concentrated, problems such as flames rising above the prismatic secondary battery are prevented or suppressed.

[0051] Considering these points, the prismatic secondary battery of the present invention, equipped with an upper structure that fills the space between the electrode assembly and the cap plate, has improved safety in the event of a thermal event.

[0052] Hereinafter, an embodiment of the prismatic secondary battery (10) of the present invention will be described with reference to the attached drawings. For reference, the directions of front, back, up, down, left, and right used to specify relative positions in the following description are intended to aid in understanding the invention, and unless otherwise specifically defined, the directions shown in the drawings are used as the reference.

[0053]

[0054] [First embodiment]

[0055] FIG. 1 is a perspective view illustrating the external shape of a prismatic secondary battery (10) according to an embodiment of the present invention. The illustrated prismatic secondary battery (10) includes a housing (100) which is cuboidal in shape and open on its upper surface, an electrode assembly (130) housed within the housing (100), and a cap plate (110) which serves as a cover closing the upper surface of the housing (100) and is equipped with a pair of electrode terminals (112) for a positive electrode and a negative electrode. An electrolyte (140) into which the electrode assembly (130) is immersed is injected into the housing (100), and the cap plate (110) may be provided with an injection port (142) into which the electrolyte (140, see FIG. 2) is injected. Additionally, a venting device (120, see FIG. 2) is provided on the bottom surface of the housing (100).

[0056] The prismatic secondary battery (10) of FIG. 1 is an example, and the prismatic secondary battery (10) of the present invention is based on having an electrode terminal (112) disposed on the upper surface of a housing (100) and a venting device (120) provided on the lower surface of the housing (100). It does not matter whether the electrode assembly (130) is a jelly roll type, a stack type, or a stack and folding type, and it does not matter if the form factor, such as the width, thickness, and height of the cuboid, is different. However, the upper and lower positional relationship mentioned above is relative, reflecting the direction of illustration, and in some cases, the present invention may also be applied to a prismatic secondary battery (10) in which a pair of electrode terminals (112) and a venting device (120) are disposed separately on opposite surfaces.

[0057] FIG. 2 is a cross-sectional view taken along the line "AA" of FIG. 1. A pair of electrode terminals (112) provided on the cap plate (110) are electrically connected to a pair of electrode leads (132) provided on the electrode assembly (130). And, a venting device (120) is provided on the bottom surface of the housing (100).

[0058] The venting device (120) is a device corresponding to a safety valve that ruptures to relieve internal pressure when pressure exceeding a safety level is applied inside the prismatic secondary battery (10). For example, if an abnormality such as thermal runaway occurs, causing the electrode assembly (130) to overheat and generate a large amount of gas, the pressure inside the housing (100) rises significantly, and at this time, the venting device (120) may be opened for safety. Various specifications may be applied to the venting device (120), and for example, it may include a rupture disc made of a thin plate-shaped member made of metal material with a notch processed. When the internal pressure of the sealed prismatic secondary battery (10) rises, tensile deformation occurs throughout the thin plate due to that pressure, and the rupture disc opens by tearing the notched part which has weak strength, thereby relieving the excessive internal pressure of the prismatic secondary battery (10).

[0059] In order for the venting device (120) to operate smoothly and accurately in a set pressure environment, the pressure inside the housing (100) must act quickly on the venting device (120). However, since gas has the property of rising due to buoyancy, high-temperature gas moves first toward the cap plate (110). The electrode terminal (112) of the prismatic secondary battery (10) where a thermal event has occurred may overheat due to current concentration, and if the gas reacts with the high-temperature electrode terminal (112) and causes ignition, explosion, etc., structural collapse of the prismatic secondary battery (10) may occur before the venting device (120) operates. Therefore, it is necessary to design the venting device (120) to operate in a timely manner by taking into account such gas movement and temperature distribution in order to maintain the structural stability of the prismatic secondary battery (10).

[0060] In order for the venting device (120) to operate quickly and accurately, the present invention provides an upper structure (200) that fills the space between the electrode assembly (130) and the cap plate (110) inside the housing (100). By the upper structure (200) occupying the space between the electrode assembly (130) and the cap plate (110), it blocks the flow of gas moving toward the cap plate (110) when a thermal event occurs. Accordingly, the gas flow flows downward, and the internal pressure of the housing (100) acts quickly on the venting device (120). In this structural context, the upper structure (200) helps to activate the venting device (120) more efficiently.

[0061] The upper structure (200) may be an injection-molded product made of resin material and may be made of an electrically insulating resin material. Since the upper structure (200) has electrical insulation, the insulation structure between the electrode assembly (130) and the cap plate (110) can be further strengthened.

[0062] Also, the upper structure (200) may be gas impermeable. By preventing the upper structure (200) from passing gas, contact between the electrode terminal (112) and the gas can be effectively suppressed.

[0063] FIG. 3 is a cross-sectional view according to another embodiment of the upper structure (200) illustrated in FIG. 2. Referring to FIG. 3, the upper structure (200) according to this embodiment may partially be provided with an electrical conductor (201). The electrical conductor (201) may be made of a metal material with excellent conductivity and may relay an electrical connection between the electrode lead (132) of the electrode assembly (130) and the electrode terminal (112) of the cap plate (110).

[0064] For example, the electrode lead (132) and the electrode terminal (112) may have a structure in which they are not physically in direct contact or welded. In this case, an electrical conductor (201) partially included in the upper structure (200) may form an electrical connection path by being electrically connected to the electrode lead (132) and the electrode terminal (112). This increases the freedom of placement of the electrode lead (132) and improves the efficiency of the assembly process.

[0065]

[0066] [Second embodiment]

[0067] FIG. 4 is a cross-sectional view of a prismatic secondary battery (10) according to another embodiment of the present invention. In the embodiment of FIG. 4, the upper structure (200) is filled with a foamed refractory agent (210) inside.

[0068] The foamed refractory agent (210) has the characteristic of foaming when exposed to heat, and can maintain a solid state without fluidity under normal conditions. When a high temperature is applied to the upper structure (200) due to a thermal event, this foamed refractory agent (210) causes foaming due to the heat. When a high temperature is applied, the foamed refractory agent (210) expands to a volume tens of times larger, bursting the thin wall surface of the upper structure (200) and ejecting, thereby forming an insulating layer around the cap plate (110). This foaming expansion occurs when the temperature inside the housing (100) exceeds a preset temperature, leading to the formation of an insulating layer. The expanded insulating layer can delay heat transfer to the cap plate (110) for a certain period of time, thereby suppressing problems such as flames ejecting from the top of the prismatic secondary battery (10).

[0069] Additionally, the expansion of the foamed refractory material (210) can rapidly increase the pressure acting on the venting device (120) as the insulation layer fills the internal space of the housing (100), thereby promoting the rapid operation of the venting device (120). Furthermore, the expansion of the foamed refractory material (210) can serve to rapidly discharge not only gas but also the electrolyte (140) through the venting device (120) located at the bottom of the housing (100) after the venting device (120) has operated. Due to the rapid discharge of the electrolyte (140), the electrochemical reaction inside the housing (100) that caused the thermal event can be rapidly terminated.

[0070]

[0071] [Third Embodiment]

[0072] FIG. 5 is a cross-sectional view of a prismatic secondary battery (10) according to another embodiment of the present invention, and FIG. 6 is a perspective view illustrating an example of a lower structure (300) provided in the prismatic secondary battery (10) of FIG. 5. In the embodiments of FIG. 5 and FIG. 6, a lower structure (300) is provided on the inner bottom surface of the housing (100) to surround a venting device (120) and support an electrode assembly (130). Here, a plurality of through holes (310) are formed in the lower structure (300).

[0073] Since the venting device (120) is located on the bottom surface of the housing (100), the electrode assembly (130) may cover part or all of the venting device (120). If the electrode assembly (130) covers the venting device (120), the gas pressure may not be able to properly act on the venting device (120). The lower structure (300) forms a space around the venting device (120) where the gas pressure can act, thereby allowing the gas pressure to act on the venting device (120). For example, since a plurality of through holes (310) are formed in the lower structure (300), the gas pressure does not hinder the act of the venting device (120).

[0074] The lower structure (300) may be provided with a protective film (320) made of an insulating material on the surface in contact with the electrode assembly (130). Considering structural rigidity and durability, the lower structure (300) may be made of a metal material. In this case, insulation treatment of the lower structure (300) supporting the electrode assembly (130) may be required. The protective film (320) made of an insulating material provides electrical insulation to the lower structure (300) made of a metal material.

[0075] However, since the ventilation may be reduced if the protective film (320) covers the through hole (310) that provides ventilation to the lower structure (300), the protective film (320) may have multiple holes that communicate with the multiple through hole (310). Alternatively, to avoid problems such as time and cost associated with the drilling of the protective film (320), the part covering the through hole (310) may be naturally ruptured by pressure when an external pressure corresponding to the operating pressure of the venting device (120) is applied, or a protective film (320) made of a material that melts when the temperature inside the housing (100) exceeds a preset temperature may be applied.

[0076] The lower structure (300) illustrated exemplarily in FIG. 6 is composed of an arched structure (302) that surrounds the venting device (120). By forming the lower structure (300) in an arched shape that is resistant to external pressure, the electrode assembly (130) can be firmly supported, and the venting device (120) can be safely protected even when the internal pressure of the housing (100) rises significantly due to the occurrence of a thermal event.

[0077] An arched lower structure (300) supports a part of the electrode assembly (130) by contacting it. FIG. 7 is a perspective view showing another example of a lower structure (300), FIG. 8 is a cross-sectional view of a prismatic secondary battery (10) to which the lower structure (300) of FIG. 7 is applied, and the exemplary lower structure (300) of FIG. 7 and FIG. 8 can support a part of the bottom surface or the entire bottom surface of the electrode assembly (130) by contacting it.

[0078] The lower structure (300) of FIGS. 7 and 8 has two opposing corners that are bent. These bent parts serve as legs for the lower structure (300), and a lower structure (300) of this form can be called a bent structure (304). The bent structure of the lower structure (300) also forms a space where gas pressure can act around the venting device (120). Additionally, by designing the length of the lower structure (300) to correspond to the full length (or full width) of the electrode assembly (130), it can be supported by contacting the entire bottom surface of the electrode assembly (130). By increasing the contact area, the load acting on the lower structure (300) can be distributed, thereby improving the structural stability of the lower structure (300).

[0079] In the same way, a plurality of through holes (310) are formed in the lower structure (300) of the folded structure, and a protective film (320) made of an insulating material can be provided on the surface in contact with the electrode assembly (130).

[0080] FIG. 9 is a drawing for explaining a battery pack and a vehicle according to an embodiment of the present invention.

[0081] One embodiment of the present invention provides a battery pack (20) including the prismatic secondary battery. Since the battery pack (20) includes the secondary battery having high capacity, high rate capability and cycle capability, it can be used as a power source for medium-to-large devices selected for electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, and power storage systems.

[0082] The battery pack (20) and the vehicle (V) according to the present embodiment are equipped with the prismatic secondary battery (10) of the prior embodiment, thereby enabling the realization of a battery pack (20) and a vehicle (V) that possess all the advantages of the prismatic secondary battery (10) of the prior embodiment.

[0083] In addition, it goes without saying that the above battery pack (20) may also be provided in other devices, mechanisms, and facilities, such as power storage devices using secondary batteries, in addition to the above vehicle (V).

[0084]

[0085] The present invention has been described above through drawings and embodiments. However, the configurations described in the drawings or embodiments described in this specification are merely one embodiment of the present invention and do not represent all technical concepts of the present invention; therefore, it should be understood that various equivalents and modifications that can replace them may exist at the time of filing this application.

Claims

1. A prismatic secondary battery having electrode terminals provided on a cap plate on the upper surface, a venting device provided on the lower surface of the housing, and an electrode assembly accommodated inside the housing, A prismatic secondary battery having an upper structure that fills the space between the electrode assembly and the cap plate inside the housing.

2. In Paragraph 1, The above upper structure is, A prismatic secondary battery that is an injection-molded product made of resin material.

3. In Paragraph 2, The above upper structure is, A prismatic secondary battery made of an electrically insulating resin material.

4. In Paragraph 1, The above upper structure is, Prismatic secondary battery filled with foamed refractory material inside.

5. In Paragraph 4, The above-mentioned foamed refractory agent is, A prismatic secondary battery that forms an insulating layer by foam expansion caused by heat when the temperature inside the housing exceeds a preset temperature.

6. In Paragraph 1, On the inner bottom surface of the above housing, A rectangular secondary battery having a lower structure that surrounds the venting device and supports the electrode assembly, wherein a plurality of through holes are formed in the lower structure.

7. In Paragraph 6, The above substructure is, A prismatic secondary battery having a protective film of insulating material on the surface in contact with the electrode assembly.

8. In Paragraph 7, The above protective film is, A prismatic secondary battery that ruptures the portion covering the plurality of through holes when an external pressure corresponding to the operating pressure of the venting device is applied, or melts when the temperature inside the housing exceeds a preset temperature.

9. In Paragraph 6, The above substructure is, A rectangular secondary battery having an arch-shaped structure surrounding the venting device and supporting it by contacting a part of the bottom surface of the electrode assembly.

10. In Paragraph 6, The above substructure is, A rectangular secondary battery having a folded structure that surrounds the venting device and supports by contacting a part or the entire bottom surface of the electrode assembly.

11. In Paragraph 1, The above upper structure is partially equipped with an electrical conductor, and A prismatic secondary battery that electrically connects the electrode lead of the electrode assembly and the electrode terminal of the cap plate.

12. In Paragraph 1, A prismatic secondary battery, wherein the upper structure is made of a gas-impermeable material to block gas generated in the electrode assembly from coming into contact with the electrode terminal.

13. In Paragraph 4, A prismatic secondary battery in which the above-mentioned foamed refractory agent fills the space inside the housing upon foam expansion, thereby discharging gas and electrolyte to the outside through the venting device to terminate the electrochemical reaction.

14. In Paragraph 6, A prismatic secondary battery, wherein the above-mentioned substructure is formed of a metal material having structural rigidity.

15. In Paragraph 1, The above venting device comprises a ruptured disc having a notch machined in a plate-shaped member made of metal material, and the notch portion is broken and opened when the internal pressure of the housing increases, a prismatic secondary battery.

16. A battery pack comprising the above-mentioned prismatic secondary battery of claim 1.

17. An automobile comprising the battery pack of claim 16.

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