Pouch-type battery case and lithium secondary battery including same

Abstract

The soft package type battery shell comprises a base layer, a gas barrier layer and a sealant layer which are sequentially stacked, and the sealant layer comprises a particle type fire extinguishing agent. The particulate fire extinguishing agent includes one or more selected from the group consisting of a first fire extinguishing component including sodium bicarbonate, a second fire extinguishing component including calcium bicarbonate, a third fire extinguishing component including ammonium phosphate, and a fourth fire extinguishing component including urea, to provide a pouch type battery case having improved safety.

Description

Technical Field

[0001] This disclosure relates to a pouch battery casing and a lithium secondary battery including the pouch battery casing, and more specifically, to a pouch battery casing with improved safety and a lithium secondary battery including the pouch battery casing. Background Technology

[0002] Typically, rechargeable batteries include nickel-cadmium batteries, nickel-metal hydride batteries, lithium-ion batteries, and lithium-ion polymer batteries. These rechargeable batteries are used in small products (e.g., digital cameras, P-DVD players, MP3 players, mobile phones, PDAs, portable gaming devices, power tools, and electric bicycles), large products requiring high power (e.g., electric vehicles and hybrid vehicles), power storage devices for storing surplus generated electricity or renewable energy, and power storage devices for backup power.

[0003] To manufacture this secondary battery, the positive and negative electrodes are first formed by coating the positive and negative current collectors with an active electrode slurry, and then stacking the positive and negative electrodes on both sides of a separator to form an electrode assembly with a predetermined shape. The electrode assembly is then housed in a battery casing, followed by the injection of electrolyte and sealing.

[0004] Based on the material of the casing housing the electrode assembly, secondary batteries are classified into pouch batteries and can batteries. Pouch batteries house the electrode assembly in a pouch made of a flexible polymer material. Can batteries house the electrode assembly in a casing made of a material such as metal or plastic.

[0005] A cup portion is formed by pressing a flexible pouch film laminate to manufacture a pouch (which serves as the casing for a pouch-type secondary battery). When the cup portion is formed, electrode assemblies are housed within the receiving space of the cup portion, and the sealing portion is sealed to manufacture the secondary battery.

[0006] Typically, pouch cell casings are formed from multiple layers. For example, a polymer film of polyethylene terephthalate is laminated on one surface of a gas barrier layer made of metal, and a sealant layer is laminated on the other surface of the gas barrier layer. However, in the case of a typical pouch cell casing, due to the higher density and larger capacity of the battery, the size needs to be increased, resulting in a deeper molding depth. This leads to high tensile stress caused by expansion, thus increasing the risk of explosion. Summary of the Invention

[0007] Technical issues To address the aforementioned issues, this disclosure provides a pouch battery housing that additionally incorporates a solid-phase particulate fire extinguishing agent into its membrane-layered structure to respond to the risk of explosion. This allows for the early activation of the fire extinguishing function when the battery malfunctions, preventing thermal runaway and explosion, thereby enhancing safety.

[0008] The problems to be solved by this disclosure are not limited to those described above, and other problems not mentioned below will be apparent to those skilled in the art from the following description.

[0009] Technical solution [1] The soft-pack battery casing according to an embodiment of the present disclosure includes a base layer, a gas barrier layer and a sealant layer stacked in sequence, wherein the sealant layer includes a particulate fire extinguishing agent, wherein the particulate fire extinguishing agent includes one or more selected from a first fire extinguishing component containing sodium bicarbonate, a second fire extinguishing component containing calcium bicarbonate, a third fire extinguishing component containing ammonium phosphate and a fourth fire extinguishing component containing urea.

[0010] [2] In the above [1], the content of particulate extinguishing agent can be from 10 wt% to 90 wt% based on the total weight of the sealant layer.

[0011] [3] In [1] and / or [2] above, the sealant layer may include particulate extinguishing agent as a filler, and the particulate extinguishing agent may have an average particle size D of less than 1 μm. 50 .

[0012] [4] In any one or more of [1] to [3] above, the sealant layer may include a first sealant layer configured to contact the gas barrier layer, a fire extinguishing agent layer comprising a particulate fire extinguishing agent and configured to contact the first sealant layer, and a second sealant layer configured to contact the fire extinguishing agent layer.

[0013] [5] In any one or more of [1] to [4] above, the pouch battery housing may include: a cup portion having a recessed shape to accommodate an electrode assembly; and a sealing portion formed along the periphery of the cup portion, wherein the particulate extinguishing agent is contained in the area excluding the sealing portion.

[0014] [6] In any one or more of [1] to [5] above, the particulate extinguishing agent may be contained in the cup portion in such a way that the width between the extinguishing agent and the sealing portion is equal to or greater than the width of the sealing portion.

[0015] [7] In any one or more of [1] to [6] above, the base layer may have a multilayer structure comprising two or more layers formed of polymers that are different from each other, and the particulate extinguishing agent is also contained in one or more layers selected from the plurality of layers.

[0016] [8] A lithium secondary battery according to another embodiment of the present disclosure includes the above-described pouch battery casing and an electrode assembly housed within the pouch battery casing.

[0017] Beneficial effects According to embodiments of the present disclosure, the pouch battery casing can respond to the risk of explosion by additionally including solid fire extinguishing components in the membrane stack structure of the pouch battery casing, thereby triggering the fire extinguishing function in advance when the battery is malfunctioning, preventing thermal runaway and explosion, and improving safety.

[0018] Specifically, the pouch battery casing includes a solid-phase particulate fire extinguishing agent. Specifically, the solid-phase particulate fire extinguishing agent is included in the inner layer of the pouch film laminate rather than in the gas barrier layer, thereby triggering the fire extinguishing function in advance when the battery exhibits abnormal behavior. Furthermore, by using solid materials, problems such as the fire extinguishing component in the lower casing failing to perform fire extinguishing operations and leaking to the outside when abnormal behavior occurs, or the fire extinguishing component penetrating into the pouch as in the case of a liquid fire extinguishing component that is more fluid than a solid fire extinguishing component, thereby causing side reactions with the electrolyte or a decrease in concentration, can be prevented in advance. Attached Figure Description

[0019] Figure 1 This is a cross-sectional view of a pouch-type battery casing that includes particulate fire extinguishing agent as a filler, according to the present disclosure.

[0020] Figure 2 It is a plan view of a lithium secondary battery including a pouch-type battery casing according to this disclosure.

[0021] Figure 3 It is based on Figure 2 An exploded view of the assembly of a lithium secondary battery.

[0022] Figure 4 It is a plan view of a lithium secondary battery including a pouch-type battery casing according to this disclosure.

[0023] Figure 5 It shows along Figure 4 The vertical cross-sectional view of the soft-pack battery casing taken by line S-S'. Detailed Implementation

[0024] The advantages and features of this disclosure and its implementation will be illustrated by the following embodiments described with reference to the accompanying drawings. However, this disclosure may be embodied in different forms and should not be construed as limiting it to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of this disclosure to those skilled in the art. Furthermore, this disclosure is limited only by the scope of the claims. Throughout the specification, the same reference numerals refer to the same elements.

[0025] Unless otherwise defined, all terms used herein (including technical and scientific terms) shall be used in the sense that would be normally understood by one of ordinary skill in the art to which this disclosure pertains. Furthermore, unless specifically defined, terms as defined in commonly used dictionaries are not to be interpreted ideally or excessively.

[0026] The terminology used herein is for the purpose of describing embodiments and is not intended to limit this disclosure. In this specification, the singular forms include the plural forms unless the context clearly indicates otherwise. As used herein, the terms “comprising” and / or “including” are intended to include the described elements and do not exclude the possibility of the presence or addition of one or more other elements.

[0027] In the following, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.

[0028] In this specification, unless otherwise stated, when a part is referred to as including a certain element, it means that the part may also include another element, without excluding another element.

[0029] In this specification, the upper part of the drawings may be referred to as the "upper part" or "upper side" of the configuration shown in the drawings, and its lower part may be referred to as the "lower part" or "lower side". Furthermore, in the drawings, the portion other than the portion between the upper and lower parts of the illustrated configuration, or the portion other than the upper and lower parts, may be referred to as the "side" or "lateral side". The aforementioned relative terms such as "upper part", "upper side", etc., may be used to describe the relationship between the components shown in the drawings, but this disclosure is not limited by such terminology.

[0030] In this specification, the direction toward the interior space of a structure may be referred to as "inner side," and the direction protruding into the exterior space of an opening may be referred to as "outer side." The aforementioned relative terms such as "inner side," "outer side," etc., may be used to describe the relationship between the components shown in the accompanying drawings, but this disclosure is not limited by such terminology.

[0031] In this specification, the description of "A and / or B" means A, or B, or A and B.

[0032] In this specification, when a component is referred to as being connected to another component, it includes not only the case where the one component is directly connected to the other component, but also the case where there is another component between the one component and the other component, and the one component is connected to the other component.

[0033] In this specification, unless otherwise expressly stated, the term "average particle size" refers to the particle size corresponding to the average weight percentage in the particle size distribution curve, and is expressed as a weight percentage (wt%). The average particle size can be measured using an electron microscope or an optical microscope after cutting a sample of the pouch cell battery casing.

[0034] In this specification, each of the pouch battery casing and the lithium secondary battery includes one or more of the technical features and / or technical configurations described below, and the technical features and / or technical configurations may be combined in various ways.

[0035] Soft-pack battery casing According to an embodiment of the present disclosure, the soft-pack battery casing includes a base layer, a gas barrier layer, and a sealant layer stacked in sequence. The sealant layer includes a particulate fire extinguishing agent, wherein the particulate fire extinguishing agent includes one or more selected from a first fire extinguishing component containing sodium bicarbonate, a second fire extinguishing component containing calcium bicarbonate, a third fire extinguishing component containing ammonium phosphate, and a fourth fire extinguishing component containing urea.

[0036] In the following text, refer to Figure 1 The following will describe in detail the pouch battery housing and each layer included in the pouch battery housing according to the present disclosure.

[0037] Figure 1 It is a cross-sectional view of a pouch-type battery housing 100 containing a first fire extinguishing component in a sealant layer, and shows the housing including particulate fire extinguishing agent as filler.

[0038] like Figure 1 As shown, the soft-pack battery casing 100 includes a base layer 110, a gas barrier layer 120, and a sealant layer 130.

[0039] (1) A sealant layer including the first extinguishing component The sealant layer 130 is joined by hot pressing, thereby sealing the battery housing, and the sealant layer 130 is located in the innermost layer of the pouch battery housing 100.

[0040] The sealant layer 130 is the surface that comes into contact with the electrolyte and electrode assembly after being molded into the battery housing. Therefore, the sealant layer 130 needs to have insulating properties and corrosion resistance, and the sealant layer 130 needs to completely seal the interior to prevent the movement of substances between the interior and the exterior. Therefore, the sealant layer 130 needs to have high sealing properties.

[0041] The sealant layer 130 may be made of a polymer material, such as one or more selected from polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, polyvinyl chloride, acrylic polymers, polyacrylonitrile, polyimide, polyamide, cellulose, aromatic polyamide, nylon, polyester, polyparaphenylene benzobisazole, polyarylate, and polytetrafluoroethylene (Teflon). Among the above materials, polypropylene (PP) is particularly preferred, as it has excellent mechanical properties (e.g., tensile strength, stiffness, surface hardness, abrasion resistance, and heat resistance) and excellent chemical properties (e.g., corrosion resistance).

[0042] The sealant layer 130 may comprise polypropylene, cast polypropylene (CPP), acid-modified polypropylene, polypropylene-butene-ethylene copolymer, or a combination thereof.

[0043] The sealant layer 130 may have a single-layer structure or a multi-layer structure comprising two or more layers made of different polymer materials.

[0044] The sealant layer can have a total thickness of 60 μm to 100 μm, preferably 60 μm to 90 μm, and more preferably 60 μm to 80 μm. If the sealant layer is too thin, the sealing durability and insulation properties may be reduced; if it is too thick, the flexibility may be reduced, and the total thickness of the flexible film laminate may increase, resulting in a decrease in energy density relative to volume.

[0045] The sealant layer 130 includes a granular extinguishing agent, which comprises one or more of a first extinguishing component containing sodium bicarbonate, a second extinguishing component containing calcium bicarbonate, a third extinguishing component containing ammonium phosphate, and a fourth extinguishing component containing urea. Specifically, the granular extinguishing agent may contain at least one of NaHCO3, KHCO3, NH4H2PO4, and KC2N2H3O3. Preferably, the granular extinguishing agent may contain NaHCO3 and / or KHCO3. In the event of a fire, the granular extinguishing agent can react with high heat and prevent the flame from spreading from the inside and outside of the electrode assembly.

[0046] Based on the total weight of the sealant layer, the content of the granular extinguishing agent can be from 10 wt% to 90 wt%, preferably from 15 wt% to 75 wt%, and more preferably from 25 wt% to 65 wt%.

[0047] If the content of granular fire extinguishing agent is too low, the fire extinguishing effect may be reduced. If the content is too high, the total thickness of the battery cell may increase due to the increase in the total thickness of the pouch battery casing, which may reduce the energy density and may result in poor formability when molding the pouch film laminate.

[0048] The granular extinguishing agent 140 may have a spherical shape, a rod shape or an irregular shape, and its shape is not particularly limited. The granular extinguishing agent 140 may be dispersed in the sealant layer 130 in the form of filler.

[0049] Particulate fire extinguishing agent 140 can have an average particle size D of less than 1.0 μm. 50 The preferred diameter is 0.1 μm to 0.8 μm, and more preferably 0.2 μm to 0.6 μm. Particulate fire extinguishing agent 140 with a size of 1.0 μm or less can be used to prevent excessive increase in the total thickness of the battery cells. The particulate fire extinguishing agent can be prepared by injecting it into the molten polymer during the extrusion of the polymer forming the sealant layer, and this method is not particularly limited.

[0050] As a method of including fire extinguishing components in a flexible laminate, methods such as forming a fire extinguishing agent layer and placing it at random positions between the laminates, or injecting the fire extinguishing component into a capsule to form a separate layer and placing that layer at random positions between the laminates, can be considered. In the case of forming a separate layer with the fire extinguishing component, the total thickness of the flexible laminate inevitably increases, which may be a factor that degrades formability (e.g., causing cracks at corners when stretching the flexible laminate into a shell).

[0051] Increasing the thickness of the pouch film laminate can prevent battery expansion caused by gases generated within it. However, in practice, since expansion prevention should be controlled by the electrode components or electrolyte included within the pouch, increasing the thickness of the pouch film laminate to suppress expansion would only increase the stress on the electrode components within the pouch casing. This would require the pouch film laminate to be designed to allow expansion within the gaps between the individual cells in the battery pack. Therefore, from a battery performance perspective, any additional layers besides those required for configuring the layers used in the pouch film laminate are undesirable.

[0052] When forming a pouch, the total thickness of the pouch increases by more than 50%, which may significantly degrade the pouch's formability. For example, during stretch forming, the pouch may rupture due to excessive tension applied to the corners. On the other hand, the pouch battery casing according to embodiments of this disclosure includes a particulate extinguishing agent in the sealant layer and is characterized by including a solid extinguishing agent. Unlike liquid extinguishing agents, if the extinguishing component is solid, there is an advantage that: there is no possibility of problems caused by the liquid phase permeating from the sealant layer into the pouch and mixing with the electrolyte, and in the event of abnormal battery behavior, such as when the casing is damaged, there is no possibility of the extinguishing agent leaking to the outside and failing to perform extinguishing work.

[0053] The pouch battery casing includes a granular fire extinguishing agent in the sealant layer, allowing for immediate fire suppression in the event of abnormal battery behavior. This suppresses heat generated in the early stages, preventing explosions caused by thermal runaway and significantly enhancing safety. Conversely, if no fire extinguishing component is present within the pouch, based on the gas barrier layer—for example, if the sealant layer itself contains no fire extinguishing component, but rather the base layer outside the gas barrier layer—fire suppression will only occur after sufficient heat has accumulated in the gas barrier layer. In this case, the energy may have increased too much to be suppressed by the fire extinguishing component, potentially making it difficult to prevent an explosion due to thermal runaway. Therefore, to suppress abnormal battery behavior by initiating fire suppression before thermal runaway occurs, it is preferable to include a granular fire extinguishing agent in the sealant layer, which is located as an inner layer, rather than the gas barrier layer.

[0054] (2) Gas barrier layer A gas barrier layer 120 is stacked between the base layer 110 and the sealant layer 130 to ensure the mechanical strength of the pouch, prevent gases, moisture, etc. from entering from the outside of the pouch battery casing, and prevent electrolyte from leaking from the inside of the pouch battery casing.

[0055] The gas barrier layer 120 can be formed of metal, specifically, it can be formed of an aluminum alloy thin film. Using an aluminum alloy thin film to form the gas barrier layer ensures a predetermined level of mechanical strength, reduces weight, enhances the electrochemical properties of the electrode assembly and electrolyte, and ensures heat dissipation. The aluminum alloy thin film can contain metallic elements other than aluminum, such as one or more selected from iron (Fe), copper (Cu), chromium (Cr), manganese (Mn), nickel (Ni), magnesium (Mg), silicon (Si), and zinc (Zn).

[0056] The thickness of the gas barrier layer 120 can be from 40 μm to 100 μm, preferably from 50 μm to 90 μm, and more preferably from 55 μm to 85 μm. If the thickness of the gas barrier layer meets the above range, the formability and gas barrier performance are excellent when molding the cup portion.

[0057] (3) Grassroots A base layer 110 is formed on the outermost layer of the flexible film laminate 100 to protect the secondary battery from external friction and impact. The base layer 110 is made of a polymer to electrically insulate the electrode assembly from external sources. The base layer 110 can be made of one or more materials selected from polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, polyvinyl chloride, acrylic polymers, polyacrylonitrile, polyimide, polyamide, cellulose, aromatic polyamide, nylon, polyester, poly(p-phenylenebenzodioxazole), polyarylate, polytetrafluoroethylene, and glass fiber. Among the above materials, the base layer 110 can be made of polyethylene terephthalate (PET), nylon, or combinations thereof, which have abrasion resistance and heat resistance.

[0058] The base layer 110 may have a single-layer structure having a single layer formed of one material. Alternatively, the base layer 110 may have a multi-layer structure in which two or more materials form layers respectively.

[0059] The thickness of the base layer 110 can be from 5 μm to 50 μm, preferably from 7 μm to 50 μm, and more preferably from 7 μm to 40 μm. If the thickness of the base layer 110 meets the above range, the soft-pack laminate can have excellent external insulation properties, and the entire soft pack is not thick, so that the energy density of the secondary battery relative to its volume can be excellent.

[0060] The base layer 110 may include fire extinguishing components. If the base layer 110 has a multi-layered structure, the fire extinguishing components may be included in one or more layers selected from these layers, and may be included in the same form as those included in the aforementioned sealant layers. In this case, the advantage is that, in addition to thermal runaway caused by abnormal behavior of the battery within the pouch, fire extinguishing operations are more reliably triggered if the battery casing is damaged by an externally applied impact.

[0061] The pouch battery housing 100 described above can be manufactured using methods known in the art for manufacturing pouch battery housings. For example, the pouch battery housing of this disclosure can be manufactured by attaching a base layer 110 to the upper surface of a gas barrier layer 120 with an adhesive, forming a sealant layer 130 on the lower surface of the gas barrier layer 120 by co-extrusion or adhesive layer, and then manufacturing the pouch film thus produced into a pouch battery housing by cup molding. However, the embodiments of this disclosure are not limited thereto, and the methods for including particulate extinguishing agents are the same as described above.

[0062] The total thickness of the pouch battery casing can be from 160 μm to 200 μm, preferably from 180 μm to 200 μm. If the thickness of the pouch battery casing meets the above range, the molding depth can be increased, while minimizing the reduction in battery housing space and the deterioration of sealing durability caused by the increase in battery casing thickness.

[0063] Lithium secondary batteries According to another embodiment of this disclosure, a lithium secondary battery is provided, which includes the above-described pouch-type battery casing and an electrode assembly housed within the pouch-type battery casing.

[0064] Figure 2 This is a plan view of an example of a lithium secondary battery 200 including a pouch-type battery casing 210.

[0065] The pouch battery casing 210 may include: a cup portion 240 having a recessed shape to accommodate an electrode assembly 260; and a sealing portion 251 formed along the periphery of the cup portion 240. The sealing portion 251 is... Figure 3 The area marked by the shaded line pattern is located in the platform portion 250 and can be formed by sealing all or part of the platform portion 250. In addition, the cup portion 240 can be molded to have a recessed shape for receiving the electrode assembly 260, which can be electrically connected to the electrode terminals, and the electrode terminals can be electrically connected to the electrode leads 280 stretched to the outside.

[0066] Figure 3 It includes according to Figure 2 An exploded view of the assembly of the lithium secondary battery 200, including the electrode assembly 260 and the pouch-type battery housing 210 therein.

[0067] like Figure 3As shown, the lithium secondary battery 200 according to this disclosure may include a pouch-type battery casing 210 and an electrode assembly 260 housed within the pouch-type battery casing 210. The electrode assembly 260 may be formed by stacking a positive electrode, a separator, and a negative electrode, and may include electrode tabs 270, electrode leads 280, and lead films 290. The lithium secondary battery 200 can be manufactured by injecting electrolyte into the pouch-type battery casing 210 while the electrode assembly 260 is housed within the pouch-type battery casing 210, and then sealing the platform portion 250.

[0068] The interior of the pouch cell battery casing 210 can accommodate the electrode assembly 260. The pouch cell battery casing 210 can be manufactured by molding a pouch film laminate. Since the detailed configuration and physical properties of the pouch film laminate are the same as described above, its specific description will be omitted.

[0069] In order to manufacture the pouch battery housing 210, the pouch film laminate is stretched and formed by stamping or the like to form a cup portion 240 including a pouch-shaped receiving space 241, thereby receiving the electrode assembly 260.

[0070] like Figure 3 As shown, the pouch battery housing 210 may include an upper housing and a lower housing. In an embodiment, the lower housing may have a cup portion 240 to include a receiving space 241 capable of receiving an electrode assembly 260, and the upper housing may cover the receiving space 241 from above to prevent the electrode assembly 260 from being separated from the outside of the pouch battery housing 210. The upper and lower housings may be manufactured to be connected to each other on one side, but are not limited thereto, and the upper and lower housings may be manufactured in various ways, such as being separate from each other and manufactured separately. Thus, sealing portions may be formed on three sides, or sealing portions may be formed on all four sides, and the cup portion may exist only in the lower housing.

[0071] The pouch-type battery housing 210 can be sealed when housing the electrode assembly 260, leaving a portion of the electrode leads 280 (i.e., the terminal portion) exposed. Specifically, when the electrode leads 280 are connected to the electrode tabs 270 of the electrode assembly 260 and a lead film 290 is formed on a portion of the electrode leads 280, the electrode assembly 260 can be housed in a housing space 241 provided in the cup portion 240 of the lower housing, and the upper housing can cover the housing space 241 from above. Subsequently, an electrolyte can be injected into the housing space 241, and the platform portions 250 formed at the edges of the upper and lower housings can be sealed. The electrolyte is used to move lithium ions generated by the electrochemical reaction of the electrodes during the charging / discharging of the lithium secondary battery 200, and may comprise a non-aqueous organic electrolyte solution, which is a mixture of lithium salt and organic solvent or a polymer using a polymer electrolyte. Furthermore, the electrolyte may comprise a sulfide-based, oxide-based, or polymer-based solid electrolyte, and the solid electrolyte may have flexibility that allows it to be easily deformed by external force.

[0072] The pouch-type battery casing may have a cup-shaped recess for accommodating electrode assemblies and a sealing portion formed along the periphery of the cup-shaped recess, wherein the solid extinguishing agent may be contained in the area excluding the sealing portion. That is, the sealing portion may be characterized by not containing the extinguishing agent.

[0073] Figure 4 This is a plan view of a lithium secondary battery 200 including a pouch-type battery casing 210 according to an embodiment of the present disclosure.

[0074] Reference Figure 4 The particulate extinguishing agent (shaded area) in the sealant layer can be formed in areas other than the sealing portion 251, that is, in a part of the cup portion 240 and the platform portion 250, and the sealing portion 251 may not contain the particulate extinguishing agent. If the extinguishing component in the sealant layer is also included in the portion to be sealed, the sealing temperature during sealing will trigger the extinguishing operation, resulting in an increased sealing time, which may deteriorate the processability or the sealing performance.

[0075] like Figure 4 As shown, the granular extinguishing agent can be contained in the sealant layer corresponding to the cup portion in such a way that the width of the gap between the extinguishing portion and the seal portion is equal to or greater than the width A-A'' of the seal portion, and the granular extinguishing agent can be included starting from the portion separated from the seal portion by the gap A-A'. That is, the gap A-A' can be greater than or equal to the gap A-A'', and in this case, a pouch-type battery housing can be provided that maximizes the effectiveness of the fire extinguishing operation without affecting the sealing performance.

[0076] Figure 5 It is along Figure 4 The image shows a cross-sectional view of the pouch-type battery casing taken along line S-S'. The cup portion 240 has a flat portion 242, a portion of which houses an electrode assembly; and an inclined portion 243, which connects to the platform portion 250 from the flat portion 242 and is formed by molding, wherein a portion of the entire platform portion 250 can be sealed to form a sealing portion 251. [The image is] from... Figure 5 The extinguishing agent is granular starting from the right side of line A, and preferably starting from the portion separated by at least gaps A and A''. Therefore, solid extinguishing components can also be provided in the platform portion 250, the inclined portion 243, and the flat portion 242. Preferably, at least the flat portion 242 can contain solid extinguishing components.

[0077] In the following text, refer to Figure 3 Further description of the lithium secondary battery 200.

[0078] Electrode assembly 260 can be formed by alternately stacking electrodes and separators. Specifically, positive and negative electrodes are manufactured by coating a slurry obtained by mixing electrode active materials, binders, and / or conductive materials onto positive and negative current collectors, and positive and negative electrodes are stacked on both sides of the separator, respectively, to form electrode assembly 260 in a predetermined shape. Electrode assembly 260 can be inserted into pouch cell housing 210, and then sealed by pouch cell housing 210 after electrolyte is injected into it. In embodiments, the type of electrode assembly 260 may include, but is not limited to, stacked, wound, stacked and folded types, etc.

[0079] Electrode assembly 260 may include two types of electrodes (positive and negative) and a separator between the electrodes to insulate them from each other. The positive and negative electrodes may each have an active material slurry coated onto the electrode current collector in the form of a metal foil or mesh containing aluminum and copper. Typically, the slurry can be formed by stirring granular active material, auxiliary conductors, binders, conductive materials, etc., with solvent added. The solvent can be removed in a subsequent process.

[0080] Electrode terminals 270 can be connected to each of the positive and negative electrodes of electrode assembly 260 and can protrude from electrode assembly 260 to the outside, serving as a path for electron movement between the inside and outside of electrode assembly 260. The electrode current collector of electrode assembly 260 can consist of a portion coated with electrode active material and a terminal portion without electrode active material (i.e., an uncoated portion). Electrode terminals 270 can be formed by cutting the uncoated portion, or by connecting individual conductive components to the uncoated portion via ultrasonic welding or the like. Figure 3 As shown, the electrode tab 270 can protrude from the electrode assembly 260 in different directions, but is not limited to them, and can protrude in various directions, such as protruding side by side in the same direction from one side of the electrode assembly 260.

[0081] Electrode leads 280 can supply power to the outside of the secondary battery 200. Electrode leads 280 can be connected to electrode terminals 270 of the electrode assembly 260 by spot welding or the like. At least a portion of the electrode lead 280 can be surrounded by a lead film 290. In an embodiment, one end of the electrode lead 280 can be connected to the electrode terminal 270, and the other end can protrude to the outside of the pouch battery housing 210. The electrode lead 280 may include: a positive electrode lead 282, one end of which is connected to the positive electrode terminal 272 and extends in the direction of protrusion of the positive electrode terminal 272; and a negative electrode lead 284, one end of which is connected to the negative electrode terminal 274 and extends in the direction of protrusion of the negative electrode terminal 274.

[0082] Both the positive electrode lead 282 and the negative electrode lead 284 can protrude to the outside of the pouch cell housing 210. Therefore, the power generated within the electrode assembly 260 can be supplied to the outside. Furthermore, since the positive electrode tab 272 and the negative electrode tab 274 are each formed to protrude in various directions, the positive electrode lead 282 and the negative electrode lead 284 can also extend in various directions. In an embodiment, the positive electrode lead 282 and the negative electrode lead 284 can be made of different materials. That is, the positive electrode lead 282 and the positive current collector can be made of the same material, aluminum (Al), and the negative electrode lead 284 and the negative current collector can be made of the same material, copper (Cu) or copper coated with nickel (Ni). The portion of the electrode lead 280 protruding to the outside of the pouch cell housing 210 can serve as a terminal portion and be electrically connected to an external terminal.

[0083] Examples and Comparison Examples The present disclosure will be described in more detail below with reference to specific examples. However, the examples below are for illustrative purposes only and are not intended to limit the scope of the disclosure. It will be apparent to those skilled in the art that various changes and modifications may be made without departing from the scope and spirit of the present disclosure, and that such changes and modifications are within the scope of the appended claims.

[0084] Example 1 On one surface of an aluminum alloy film having a width of 266 mm, a length of 50 m, and a thickness of 60 μm, a polyethylene terephthalate film having a width of 266 mm, a length of 50 m, and a thickness of 12 μm and a nylon film having a width of 266 mm, a length of 50 m, and a thickness of 25 μm are laminated. On the other surface of the aluminum alloy film, cast polypropylene (CPP) having a width of 266 mm, a length of 50 m, and a thickness of 50 μm is laminated to manufacture a flexible film laminate having a polyethylene terephthalate / nylon / aluminum alloy film / cast polypropylene structure.

[0085] At this point, during extrusion, an average particle size (D) is injected into the cast polypropylene. 50 The NaHCO3 is approximately 0.7 μm (equivalent to 30 wt% of its total weight), which includes fire extinguishing components.

[0086] Here, polyethylene terephthalate and nylon are the base layers, aluminum alloy film is the gas barrier layer, and cast polypropylene is the sealant layer.

[0087] The manufactured soft-pack film laminate is mounted on a double-cup molding machine equipped with a mold and a punch. The manufactured soft-pack film laminate is then stretched and molded by lowering the punch at a pressure of 0.5 MPa and a rate of 20 mm / min, so that the molding depth is 9.6 mm, in order to manufacture a soft-pack battery casing.

[0088] Example 2 In addition to injecting the average particle size (D) into the cast polypropylene during extrusion, 50 The pouch cell housing is manufactured in the same manner as in Example 1, with approximately 0.7 μm (equivalent to 30 wt% based on its total weight) of KHCO3.

[0089] Example 3 During extrusion, in addition to casting the polypropylene, polyethylene terephthalate is also injected with an average particle size (D). 50 The KHCO3 is approximately 0.7 μm thick (equivalent to 30 wt% of its total weight), which allows the polyethylene terephthalate layer and the cast polypropylene layer to contain fire extinguishing components, thus manufacturing the pouch battery casing in the same manner as in Example 1.

[0090] Comparison Example 1 Except that the cast polypropylene does not contain fire extinguishing components, the pouch battery casing is manufactured in the same manner as in Example 1.

[0091] Comparison Example 2 Except that the cast polypropylene does not contain fire extinguishing components, but only polyethylene terephthalate contains fire extinguishing components, the pouch battery casing is manufactured in the same manner as in Example 1.

[0092] Comparison Example 3 In addition to injecting NaHCO3 into a capsule with a diameter of about 10 μm and using the capsule to create a fire extinguishing layer with a thickness of about 50 μm between the nylon and aluminum alloy film to create a soft-pack film laminate, the soft-pack battery casing is manufactured in the same manner as in Example 1.

[0093] Compare Example 4 Except for injecting NaHCO3 into a capsule with a diameter of about 10 μm and using the capsule to create a fire extinguishing layer with a thickness of about 50 μm between an aluminum alloy film and a cast polypropylene film to manufacture a soft-pack film laminate, the soft-pack battery casing is manufactured in the same manner as in Example 1.

[0094] Experimental Example 1 The pouch-type battery casings manufactured in the example and comparative examples were applied to the following lithium secondary batteries and evaluated as follows. The results are shown in Table 1. Here, the experimental results are shown in Table 1 below. In Table 1, "◎" indicates very good, "○" indicates good, "△" indicates fair, and "X" indicates poor.

[0095] Manufacturing of lithium secondary batteries A positive electrode slurry was prepared by mixing positive electrode active material (NCM65 1520), conductive material (Li-435), and PVDF binder (KF9700, Ad-c01) in N-methylpyrrolidone at a weight ratio of 96.5:1.5:2.0. The positive electrode slurry was coated on one surface of an aluminum current collector, dried at 140°C, and then rolled to manufacture the positive electrode.

[0096] In the case of the negative electrode, a slurry is prepared by mixing the negative electrode active material, conductive material and binder, in which natural graphite and artificial graphite are mixed in a ratio of 5:5, and in a weight ratio of 95.6:0.9:3.4. The slurry is coated on a copper current collector, and then dried and rolled to manufacture the negative electrode.

[0097] An electrode assembly is manufactured by inserting a separator between the positive and negative electrodes, which are respectively manufactured by the above method. The electrode assembly is then placed inside the battery casing of each of the example and comparative examples. An electrolyte solution is then injected into the battery casing to manufacture a single battery cell. The electrolyte solution is prepared by dissolving 0.7M LiPF6 in a mixed organic solvent in which ethylene carbonate (EC), propylene carbonate (PC), and ethyl methyl carbonate (EMC) are mixed at a volume ratio of 2:1:7.

[0098] 1) Fire outbreak test The five battery cells manufactured above are assembled into a module, and a heating pad is attached to one of the battery cells to apply heat at a rate of 0.5°C / second. Observe whether the battery cell to which the heating pad is attached ignites. The longer the delay in the initial occurrence of ignition (fire or smoke), the better, and the results are evaluated in four stages.

[0099] 2) Thermal propagation delay test The five battery cells manufactured above were assembled into a module, and heat was applied to one battery cell at a rate of 0.5°C / second using a heating pad. The heat of adjacent battery cells was measured using thermocouples to confirm whether there was a time delay in heat propagation, and the results were evaluated in four stages.

[0100] 3) Penetration test A nail penetration test was conducted using a sharp type of nail to penetrate the aforementioned battery cell at a rate of 0.1 mm / s, and the time to initial ignition, flame size during ignition, and smoke volume were evaluated in four stages.

[0101] 4) Formability When manufacturing a pouch cell battery casing, during stretch molding to achieve a molding depth of 9.6 mm, it is checked whether cracks exist in the pouch film. Specifically, the case where no cracks occur is evaluated as ○, the case where cracks occur in the base layer on the surface is evaluated as △, and the case where the gas barrier layer is exposed or broken due to the occurrence of cracks is evaluated as X.

[0102] 5) Expansion stability: The lithium secondary battery was driven for 200 cycles, and then the thickness change of the lithium secondary battery was measured. Cases with a thickness change rate greater than 5% were evaluated as ○, and cases with a thickness change rate less than 5% were evaluated as X.

[0103] [Table 1] Referring to Table 1 above, it can be confirmed that, compared to the comparative examples, the examples exhibit superior safety in terms of fire outbreak and heat propagation due to energy accumulation, without affecting battery performance or moldability. On the other hand, it can be confirmed that comparative example 1 does not contain extinguishing agents, and therefore is significantly unstable in terms of fire or explosion safety, particularly posing a high risk of explosion due to rapid heat propagation. Furthermore, it can be confirmed that, as in comparative example 2, if the extinguishing agent is located on the outside of the pouch instead of on the gas barrier layer, the same results are obtained in the nail penetration test, an anomaly caused by external impact, but the extinguishing agent has little effect on fire outbreak and heat propagation. Moreover, in comparative examples 3 and 4, where a separate extinguishing agent layer is formed through capsule formation, cracks occur at the corners of the cup during molding due to the increased thickness of the pouch. Furthermore, it can be confirmed that if gas is generated inside the pouch, expansion should be allowed to a certain extent by the predetermined thickness of the gap between the battery cells in the battery pack, so as to reduce the stress applied to the electrode assembly and prevent the resulting performance degradation. However, in the cases of Comparative Examples 3 and 4, expansion is not allowed due to the increased thickness of the pouch, so there is a problem of greater stress applied to the electrode assembly inside the pouch.

[0104] [Explanation of reference numerals or symbols in the attached drawings] 100, 210: Soft-pack battery casing 110: Base layer; 120: Gas barrier layer 130: Sealant layer; 131: First sealant layer 132: Second sealant layer; 140: Granular extinguishing agent 200: Lithium secondary battery 240: Cup Section 241: Containment Space 242: Flat section 243: Inclined section 250: Platform section; 251: Sealing section 260: Electrode assembly; 270: Electrode connector. 280: Electrode lead; 290: Lead film

Claims

1. A pouch-type battery case comprising a base layer, a gas barrier layer, and a sealant layer sequentially laminated, wherein the sealant layer includes a particulate fire extinguishing agent, wherein the particulate fire extinguishing agent contains one or more selected from a first fire extinguishing component containing sodium bicarbonate, a second fire extinguishing component containing potassium bicarbonate, a third fire extinguishing component containing ammonium phosphate, and a fourth fire extinguishing component containing urea.

2. The pouch-type battery case according to claim 1, wherein The content of the particulate fire extinguishing agent is 10 wt% to 90 wt% based on the total weight of the sealant layer.

3. The pouch-type battery case according to claim 1, wherein The particulate fire extinguishing agent has an average particle diameter D of 1 μm or less 50 .

4. The pouch-type battery case according to claim 1, wherein The pouch-type battery case includes: a cup portion having a recessed shape to accommodate an electrode assembly; and a sealing portion formed along a periphery of the cup portion, wherein the particulate fire extinguishing agent is contained in an area other than the sealing portion.

5. The pouch-type battery case according to claim 4, wherein The particulate fire extinguishing agent is contained in the cup portion at a width equal to or greater than the width of the sealing portion, spaced apart from the sealing portion.

6. The pouch-type battery case according to claim 1, wherein The base layer has a multi-layer structure including two or more layers formed of different polymers from each other, and the particulate fire extinguishing agent is further contained in one or more layers selected from the plurality of layers. 7.A lithium secondary battery comprising: the pouch-type battery case according to any one of claims 1 to 6; and an electrode assembly accommodated in the pouch-type battery case.

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