Pouch-type secondary battery

Abstract

A pouch-type secondary battery is provided, comprising: an electrode assembly; a battery case including a receiving portion for housing the electrode assembly and a platform portion formed along the circumference of the receiving portion; electrode leads connected to the electrode assembly and protruding through the platform portion to the outside of the battery case; a lead membrane disposed between the electrode leads and the battery case; and a gas guiding membrane disposed between the electrode leads and the lead membrane, wherein the platform portion includes a sealing portion, the sealing portion being a portion of the platform portion sealed along the circumference of the receiving portion, and the lead membrane comprises inorganic particles. Because the inorganic particles are contained within the lead membrane through which gas passes, the pouch-type secondary battery can have improved gas emission performance.

Description

Technical Field

[0001] Cross-reference to related applications

[0002] This application claims the benefit of priority to Korean Patent Application No. 10-2024-0066764, filed on May 22, 2024, which is incorporated herein by reference in its entirety. Technical Field

[0003] This invention relates to pouch-type secondary batteries, and more specifically to pouch-type secondary batteries comprising a gas guiding membrane and a lead membrane containing inorganic particles. Background Technology

[0004] Secondary batteries are used in a wide range of categories, including: small products such as digital cameras, P-DVD players, MP3 players, mobile phones, PDAs, portable gaming devices, power tools, and electric bicycles; large products requiring high power such as electric vehicles and hybrid vehicles; power storage devices for storing surplus or renewable energy; and backup power storage devices. Secondary batteries include nickel-cadmium batteries, nickel-metal hydride batteries, lithium-ion batteries, and lithium-ion polymer batteries.

[0005] Secondary batteries can be manufactured by housing an electrode assembly in which positive, negative, and spacers are alternately stacked in a battery case, injecting electrolyte, and then sealing the battery case. Depending on the material of the case housing the electrode assembly, secondary batteries are classified into pouch-type and can-type secondary batteries. Specifically, pouch-type batteries can be manufactured by pressing a flexible pouch film laminate to form a cup-shaped portion, then housing the electrode assembly within the receiving space inside the cup-shaped portion, and sealing the portion.

[0006] When bag-type secondary batteries are handled at high temperatures, overcharged, or short-circuited, gas may be generated inside the bag. When the gas pressure inside the bag increases, the bag may release gas, potentially leading to an explosion or ignition.

[0007] To overcome the aforementioned limitations, different types of gas emission components have been studied, and there is a growing need for gas emission components designed to manage gas emissions, external moisture intrusion, and electrolyte leakage; gas emission components with high internal pressure tolerance but low operating pressure; and gas emission components that also exhibit high durability. Summary of the Invention

[0008] Technical issues

[0009] One aspect of the present invention provides a pouch-type secondary battery having a gas emission function provided by a gas guiding membrane. The pouch-type secondary battery includes inorganic particles in the lead membrane through which gas can directly permeate, and thus can remove HF gas generated by moisture, thereby preventing corrosion of the electrode leads and increasing the gas emission rate.

[0010] Technical solution

[0011] [1] According to one aspect of the present invention, a pouch-type secondary battery is provided, the pouch-type secondary battery comprising: an electrode assembly; a battery case including a receiving portion for receiving the electrode assembly and a platform portion formed along the periphery of the receiving portion; electrode leads connected to the electrode assembly and protruding to the outside of the battery case via the platform portion; a lead film disposed between the electrode leads and the battery case; and a gas guiding film disposed between the electrode leads and the lead film, wherein the platform portion includes a sealing portion, wherein a portion of the platform portion is sealed along the periphery of the receiving portion, and the lead film comprises inorganic particles.

[0012] [2] The present invention provides a pouch-type secondary battery according to [1] above, wherein a gas-permeable portion formed on the outside of the sealing portion and a gas channel formed to connect the gas-permeable portion to the interior of the battery box via the sealing portion can be provided at the interface between the lead film and the gas guiding film.

[0013] [3] The present invention provides a pouch-type secondary battery according to [1] and / or [2] above, wherein when gas is generated inside the battery case, the interface between the lead film and the gas guiding film is opened to allow the generated gas to be discharged to the outside through the gas channel via the lead film on the gas permeable portion.

[0014] [4] The present invention provides a pouch-type secondary battery according to at least one of [1] to [3] above, wherein the lead film may have a structure in which a pouch adhesive layer, a core layer and a lead adhesive layer are sequentially stacked, and inorganic particles may be disposed in at least one layer selected from the group consisting of the core layer and the lead adhesive layer.

[0015] [5] The present invention provides a pouch-type secondary battery according to at least one of [1] to [4] above, wherein the lead film may have a structure in which a pouch adhesive layer, a core layer and a lead adhesive layer are sequentially stacked, and inorganic particles may be disposed in the core layer.

[0016] [6] The present invention provides a pouch-type secondary battery according to at least one of [1] to [5] above, wherein inorganic particles may also be disposed in the lead adhesive layer.

[0017] [7] The present invention provides a pouch-type secondary battery according to at least one of [1] to [6] above, wherein the inorganic particles may include at least one selected from the group consisting of CaCO3, Ca(OH)2, CaCl2, CaO, KOH, NaOH and Na2CO3.

[0018] [8] The present invention provides a pouch-type secondary battery according to at least one of [1] to [7] above, wherein the amount of inorganic particles may include 1 wt% to 20 wt% relative to the total weight of the lead film.

[0019] [9] The present invention provides a pouch-type secondary battery according to at least one of [1] to [8] above, wherein the lead film can be configured such that one end protruding to the outside of the battery case protrudes further than one end of the gas guiding film protruding to the outside of the battery case and is in direct contact with the electrode leads.

[0020]

[10] The present invention provides a pouch-type secondary battery according to at least one of [1] to [9] above, wherein the gas guiding membrane may have a structure in which an adhesive resin layer and a permeable resin layer are stacked from the upper surface of the electrode leads.

[0021]

[11] The present invention provides a pouch-type secondary battery according to

[10] above, wherein the adhesive resin layer may comprise at least one selected from the group consisting of acid-modified polypropylene (PPa) and acid-modified polyethylene (Pea).

[0022]

[12] The present invention provides a pouch-type secondary battery according to

[10] and / or

[11] above, wherein the permeable resin layer may include at least one selected from the group consisting of polyimide (PI) and polytetrafluoroethylene (PTFE).

[0023]

[13] The present invention provides a pouch-type secondary battery according to at least one of

[10] to

[12] above, wherein the ratio (D1 / D2) of the thickness of the adhesive resin layer (D1) to the thickness of the permeable resin layer (D2) can be 0.4 to 2.0.

[0024]

[14] The present invention provides a pouch-type secondary battery according to at least one of

[10] to

[13] above, wherein an end of the adhesive resin layer protruding to the outside of the battery case may protrude further than an end of the permeable resin layer protruding to the outside of the battery case.

[0025] Beneficial effects

[0026] The pouch-type secondary battery according to this specification has the function of venting gas through a gas-permeable portion and gas channel formed between a gas guiding membrane and a lead membrane. Furthermore, the lead membrane includes inorganic particles, allowing gas to directly permeate through the lead membrane into the gas-permeable portion, thus removing HF gas generated by moisture and preventing corrosion of the electrode leads. This is also expected to improve the durability of the pouch-type secondary battery. In addition, the inclusion of inorganic particles in the lead membrane increases the membrane porosity, and therefore increases the gas emission rate without increasing moisture permeation, thereby improving gas emission performance and thus providing a pouch-type secondary battery with enhanced safety. Attached Figure Description

[0027] The following figures accompanying this document illustrate preferred embodiments of the invention by way of example, and together with the following detailed description of the invention, are intended to enable a further understanding of the technical concepts of the invention, and therefore the invention should not be construed as being limited to the contents of these figures.

[0028] Figure 1 This is an exploded view of a pouch-type secondary battery according to an embodiment of this specification;

[0029] Figure 2 This is a cross-sectional view of a sealed pouch-type secondary battery;

[0030] Figure 3 yes Figure 2 An example of an enlarged cross-sectional view of a portion of box A shows the state before the interface between the lead film and the gas guiding film is opened;

[0031] Figure 4 yes Figure 2 An example of an enlarged cross-sectional view of a portion of box A, specifically showing the lead film in a state before the interface between the lead film and the gas guiding film is opened;

[0032] Figure 5 yes Figure 2 An example of an enlarged cross-sectional view of a portion of box A, specifically showing the lead film in a state before the interface between the lead film and the gas guiding film is opened;

[0033] Figure 6 yes Figure 2 An example of an enlarged cross-sectional view of a portion of frame A shows the state in which the interface between the lead wire membrane and the gas guiding membrane is open;

[0034] Figure 7 yes Figure 2 Another example of an enlarged cross-sectional view of a portion of box A shows the state before the interface between the lead film and the gas guiding film is opened;

[0035] Figure 8 yes Figure 2 Another example of an enlarged cross-sectional view of a portion of box A shows the state before the interface between the lead film and the gas guiding film is opened;

[0036] Figure 9 yes Figure 2 An example of a top-view perspective view of a portion of frame A along direction B.

[0037] Figure 10 yes Figure 2 Another example of a top-view perspective of a portion of frame A along direction B. Detailed Implementation

[0038] The advantages and features of the invention described herein, as well as the methods for achieving these advantages and features, can be more readily understood from the following detailed description with reference to the accompanying drawings and embodiments. However, the invention may be embodied in different forms, and these embodiments are provided only to make the invention thorough and complete and to fully convey the scope of the invention to those skilled in the art, and therefore the invention is limited only by the scope of the appended claims. Throughout the specification, the same reference numerals denote the same elements.

[0039] Unless otherwise defined, all terms used herein (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Unless explicitly and specifically defined, terms as defined in commonly used dictionaries shall not be interpreted ideally or excessively.

[0040] The terminology used herein is not intended to limit the invention, but rather to describe embodiments. As used herein, singular terms are intended to include plural forms as well, unless the context clearly indicates otherwise. The meaning of “comprising” and / or “including” as used herein does not exclude the presence or addition of one or more other components besides those mentioned.

[0041] As used herein, when an element “includes” a component, it may indicate that the element does not exclude another component, but may also include another component, unless there is an explicit description to the contrary.

[0042] As used in this article, the description “A and / or B” means either A or B or A and B.

[0043] As used herein, unless otherwise indicated, “%” indicates wt%.

[0044] In one aspect of this specification, a pouch-type secondary battery includes: an electrode assembly; a battery case including a receiving portion for accommodating the electrode assembly and a platform portion formed along the periphery of the receiving portion; electrode leads connected to the electrode assembly and protruding through the platform portion to the outside of the battery case; a lead membrane disposed between the electrode leads and the battery case; and a gas guiding membrane disposed between the electrode leads and the lead membrane, wherein the platform portion includes a sealing portion, wherein a portion of the platform portion is sealed along the periphery of the receiving portion, and the lead membrane comprises inorganic particles.

[0045] Typically, the gas emission performance of a gas guiding membrane is determined by the properties of the materials that constitute the membrane. These material properties may specify moisture permeability, electrolyte leakage prevention, and gas permeability, which also varies depending on the material. Therefore, the materials constituting the gas guiding membrane are the determining factors.

[0046] Regardless of the material, factors that can improve gas emission performance include the area of ​​the gas-permeable portion formed on the gas guiding membrane and the width of the gas channels formed on the gas guiding membrane connecting the inside of the battery box to the gas-permeable portion, thereby improving gas emission performance, water permeability performance, and electrolyte leakage prevention performance.

[0047] When using battery cells with materials that inevitably generate a large amount of gas, there may be limitations in the materials and design of the gas guiding membrane to vent the gas generated inside the pouch cell. Furthermore, pouch cells with gas venting capabilities and gas guiding membranes are inherently susceptible to damage in preventing moisture penetration and protecting electrode leads from corrosion caused by hydrofluoric acid gas (HF gas) generated during side reactions of the electrolyte.

[0048] This specification provides a pouch-type secondary battery that significantly improves durability and safety by including inorganic particles in the lead membrane that allows gas to directly permeate to the outside and continuously contact the generated gas, thereby preventing corrosion of the electrode leads caused by internally generated HF gas, while further improving gas emission performance and limiting moisture permeation.

[0049] First, the various components of the pouch-type secondary battery of the present invention will be described in more detail with reference to the accompanying drawings.

[0050] Figure 1 This is an exploded view of a pouch-type secondary battery 100 according to an embodiment of this specification, and Figure 2 This is a cross-sectional view of a sealed pouch-type secondary battery 100. Figure 2 For ease of understanding, some components of the pouch-type secondary battery 100 are not provided. For example... Figure 1 and Figure 2As shown, the pouch-type secondary battery 100 of the present invention includes a battery box 110, an electrode assembly 160, an electrode lead 180, a lead film 190, and a gas guiding film 200.

[0051] (1) Battery box

[0052] On one hand, the battery case 110 may internally house the electrode assembly 160. The battery case 110 may be fabricated by molding a pouch film laminate. In this case, the pouch film laminate may include a base layer, a gas barrier layer, and a sealant layer. In the pouch film laminate, the base layer, the gas barrier layer, and the sealant layer may be stacked sequentially.

[0053] A base layer is formed on the outermost layer of the bag film laminate to protect the secondary battery from external friction and impact. The base layer is made of polymer, which also allows the electrode assembly to be electrically insulated from the outside.

[0054] The base layer can be made of at least one material selected from the group consisting of: polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, polyvinyl chloride, acrylic polymers, polyacrylonitrile, polyimide, polyamide, cellulose, aromatic polyamide, nylon, polyester, poly(p-phenylenebenzodioxazole), polyarylate, Teflon, and glass fiber. Preferably, the base layer can be made of polyethylene terephthalate (PET), nylon, or combinations thereof, which have abrasion resistance and heat resistance.

[0055] The base layer can have a single-film structure made of any material. Alternatively, the base layer can have a composite film structure in which two or more materials are formed as layers.

[0056] The substrate can have a thickness of 5 μm to 50 μm, particularly 7 μm to 40 μm, and even more particularly 25 μm to 38 μm. When the thickness of the substrate meets the above range, the external insulation is excellent and the entire bag is not thick, and therefore, the energy density of the secondary battery relative to its volume can be excellent.

[0057] A gas barrier layer is stacked between the base layer and the sealant layer to ensure the mechanical strength of the bag, prevent the entry and exit of external gases or moisture from the secondary battery, and prevent electrolyte leakage from the inside of the battery box.

[0058] The gas barrier layer can be formed of a metal, and specifically of an aluminum alloy film. When an aluminum alloy film is used to form the gas barrier layer, the gas barrier layer can have a predetermined level of mechanical strength and is also lightweight, and can complement the electrochemical properties caused by the electrode components and electrolyte, and provide heat dissipation. The aluminum alloy film can include metallic elements other than aluminum (Al), for example, it can include at least one selected from the group consisting of iron (Fe), copper (Cu), chromium (Cr), manganese (Mn), nickel (Ni), magnesium (Mg), silicon (Si), and zinc (Zn).

[0059] The gas barrier layer can have a thickness of 40 μm to 100 μm, specifically 50 μm to 90 μm, and more specifically 55 μm to 85 μm. When the thickness of the gas barrier layer meets the above range, the moldability and gas barrier performance are excellent when molding the cup-shaped portion.

[0060] When the battery case containing the electrode assembly is sealed, the sealant layer thermally bonds together at the sealing portion to completely seal the interior of the battery case. For this purpose, the sealant layer can be formed of a material with excellent heat-sealing strength.

[0061] The sealant layer can be formed of a material possessing insulating, corrosion-resistant, and sealing properties. Specifically, the sealant layer is in direct contact with the electrode components and / or electrolyte inside the battery compartment, and therefore can be formed of a material possessing insulating and corrosion-resistant properties. Furthermore, the sealant layer should completely seal the interior of the battery compartment and prevent material movement between the interior and exterior, and therefore can be formed of a material with high sealing properties (e.g., excellent heat-sealing strength). To ensure such insulating, corrosion-resistant, and sealing properties, the sealant layer can be formed of a polymer material.

[0062] The sealant layer may be made of at least one material selected from the group consisting of polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, polyvinyl chloride, acrylic polymers, polyacrylonitrile, polyimide, polyamide, cellulose, aromatic polyamide, nylon, polyester, poly(p-phenylenebenzodioxazole), polyarylate, Teflon, and glass fiber, and may preferably be made of polyolefin-based resins such as polypropylene (PP) and / or polyethylene (PE). In this case, polypropylene may include cast polypropylene (CPP), acid-modified polypropylene (PPa), polypropylene-ethylene copolymer, and / or polypropylene-butene-ethylene terpolymer.

[0063] The sealant layer can have a thickness of 30 μm to 130 μm, particularly 50 μm to 120 μm, and even more particularly 70 μm to 100 μm. When the thickness of the sealant layer meets the above range, it has the effect of ensuring both the sealing strength of the sealed portion and the formability of the bag film laminate.

[0064] Meanwhile, the bag film laminate can be drawn, molded, or stretched using a punch or the like to manufacture the battery case 110. Therefore, the battery case 110 may include a cup-shaped portion 122 and a receiving portion 124. The receiving portion 124 is a place for receiving electrode assemblies and may indicate the receiving space formed in the shape of a bag inside the cup-shaped portion 122 when the cup-shaped portion 122 is formed.

[0065] On one hand, the battery box 110 may include, for example, Figure 1 The first box 120 and the second box 130 are shown. The first box 120 may include a receiving portion 124 capable of accommodating the electrode assembly 160, and the second box 130 may cover the receiving portion 124 from above to prevent the electrode assembly 160 from separating to the outside of the battery box 110. The first box 120 and the second box 130 may be as follows: Figure 1 The invention is shown to be manufactured in such a way that one side of the first box 120 and one side of the second box 130 can be connected to each other, but the embodiments of the invention are not limited thereto, and the first box 120 and the second box 130 can be manufactured differently, for example, by being manufactured separately from each other.

[0066] On the other hand, when forming cup-shaped portions in a bag film laminate, two adjacent symmetrical cup-shaped portions 122 and 132 can be drawn and molded in one bag film laminate. In this case, cup-shaped portions 122 and 132 can be formed in the first box 120 and the second box 130, respectively, as shown. Figure 1 As shown in the diagram, after the electrode assembly 160 is housed in the receiving portion 124 within the cup-shaped portion 122 of the first housing 120, the bridging portion 140 formed between the two cup-shaped portions 122 and 132 can be folded so that the two cup-shaped portions 122 and 132 face each other. In this case, the cup-shaped portion 132 of the second housing 130 can accommodate the electrode assembly 160 from above. Therefore, the two cup-shaped portions 122 and 132 accommodate one electrode assembly 160, and thus can accommodate a thicker electrode assembly 160 than when only one cup-shaped portion 122 is present. Furthermore, one edge of the secondary battery 100 is formed by folding the battery case 110, and therefore, the number of edges to be sealed can be reduced when a sealing process is performed later. Therefore, the processing speed of the pouch-type secondary battery 100 can be increased, and the number of sealing processes can be reduced.

[0067] The battery case 110 can be sealed while housing the electrode assembly 160, exposing a portion of the electrode leads 180, i.e., the terminal portion, which will be described later. Specifically, when the electrode leads 180 are connected to the electrode tabs 170 of the electrode assembly 160 and a lead film 190 is formed on a portion of the electrode leads 180, the electrode assembly 160 can be housed in a receiving portion 124 disposed in the cup-shaped portion 122 of the first case 120, and the second case 130 can cover the receiving portion 124 from above. Electrolyte is then injected into the receiving portion 124, and a portion of the platform portion 150 formed along the periphery of the first case 120 and the second case 130 can be sealed to form a sealing portion (not shown).

[0068] The sealing portion can be used to seal the receiving portion 124. Specifically, the sealing portion can seal the receiving portion 124 by forming a platform portion 150 along the periphery of the receiving portion 124.

[0069] The sealing temperature can be between 180°C and 250°C, particularly between 200°C and 250°C, and even more particularly between 210°C and 240°C. When the sealing temperature meets the numerical range described above, the battery box 110 can achieve sufficient sealing strength through thermal bonding.

[0070] (2) Electrode assembly

[0071] On one hand, the electrode assembly 160 can be inserted into the battery case 110 and sealed through the battery case 110 after electrolyte injection.

[0072] The positive electrode, the separator, and the negative electrode can be stacked sequentially to form an electrode assembly 160. Specifically, the electrode assembly 160 may include two types of electrodes, namely a positive electrode and a negative electrode, and a separator sandwiched between the electrodes to insulate them from each other.

[0073] The positive and negative electrodes can have structures in which an active material slurry is applied, respectively, to an electrode current collector in the form of a metal foil or mesh comprising aluminum and copper. Typically, granular active material, auxiliary conductors, binders, and conductive materials are stirred with an added solvent to form a slurry. The solvent can be removed in subsequent processing.

[0074] A slurry containing electrode active materials, binders, and / or conductive materials is applied to positive and negative current collectors to manufacture positive and negative electrodes, and the positive and negative electrodes are stacked on both sides of a separator, thereby allowing the electrode assembly 160 to be manufactured into a predetermined shape. The type of electrode assembly 160 may include, but is not limited to, stacked, wound, and stacked-folded types.

[0075] Electrode assembly 160 may include electrode tabs 170.

[0076] Electrode tab 170 is connected to each of the positive and negative electrodes of electrode assembly 160 and protrudes outward from electrode assembly 160, thus serving as a path for electrons to move between the interior and exterior of the electrode assembly. The current collector included in electrode assembly 160 may have a portion to which electrode active material is applied and an end portion to which no electrode active material is applied, i.e., an uncoated portion. Electrode tab 170 can be formed by cutting the uncoated portion or by connecting individual conductive members to the uncoated portion by means of ultrasonic welding, etc. Figure 1 As shown, electrode tab 170 can protrude from electrode assembly 160 in different directions, but is not limited thereto, and can be formed to protrude in various directions, such as protruding from one side in the same direction.

[0077] (3) Electrode leads

[0078] On one hand, the electrode lead 180 can supply power to the outside of the secondary battery 100. The electrode lead 180 can be connected to the electrode tab 170 of the electrode assembly 160 by spot welding or the like.

[0079] Electrode lead 180 can be connected to electrode assembly 160 and can protrude to the outside of battery case 110 via sealing portion 151. Specifically, one end of electrode lead 180 can be connected to electrode assembly 160, particularly electrode tab 170, and the other end of electrode lead 180 can protrude to the outside of battery case 110 via platform portion 150.

[0080] Electrode leads 180 may include a positive lead 182 and a negative lead 184. The positive lead 182 has one end connected to a positive contact 172 and extends in the direction in which the positive contact 172 protrudes. The negative lead 184 has one end connected to a negative contact 174 and extends in the direction in which the negative contact 174 protrudes. The other ends of both the positive lead 182 and the negative lead 184 may protrude to the outside of the battery case 110. Therefore, the power generated inside the electrode assembly 160 can be supplied to the outside. Furthermore, the positive contact 172 and the negative contact 174 are each formed to protrude in different directions, and therefore, the positive lead 182 and the negative lead 184 may also extend in different directions. The positive lead 182 and the negative lead 184 may be made of different materials. In other words, the positive electrode lead 182 can be made of the same aluminum (Al) material as the positive electrode current collector, and the negative electrode lead 184 can be made of the same copper (Cu) or nickel (Ni) coated copper material as the negative electrode current collector. The portion of the electrode lead 180 protruding outside the battery case 110 can be used as a terminal portion and electrically connected to an external terminal.

[0081] The side of electrode lead 180 that is in direct contact with lead film 190 and / or gas guiding film 200 may be coated with at least one of the following: chromium (Cr), nickel (Ni), aluminum oxide (Al2O3), zirconium (Zr)-based anhydrous oxide salts, and titanium (Ti)-based anhydrous oxide salts. In this case, corrosion resistance to electrolyte solutions and adhesion to lead film 190 and / or gas guiding film 200 can be ensured.

[0082] (4) Lead film

[0083] On one hand, the lead film 190 prevents the power generated by the electrode assembly 160 from flowing through the electrode leads 180 to the battery case 110 and allows the battery case 110 to remain sealed. For this purpose, the lead film 190 can be formed of a non-conductor with non-conductive properties, in which electricity cannot flow well. Typically, relatively thin insulating tapes that are easy to attach to the electrode leads 180 and / or the gas guiding film 200 are widely used with respect to the lead film 190; however, embodiments of the invention are not limited to this, and therefore any component capable of insulating the electrode leads 180 can be used.

[0084] The lead film 190 can be configured to surround the outer peripheral surfaces of the electrode lead 180 and the gas guiding film 200. Specifically, the electrode lead 180 and the gas guiding film 200 are in contact with each other on one side, and in this case, at least a portion of the electrode lead 180 and the gas guiding film 200 can be surrounded by the lead film 190. The lead film 190 can be disposed within the sealing portion 151 in which the first box 120 and the second box 130 of the battery box 110 are thermally fused, and the electrode lead 180 and the gas guiding film 200 can be adhered to the battery box 110.

[0085] On one hand, the lead film 190 can be configured such that one end of the lead film 190 protruding outside the battery case 110 protrudes further outward than one end of the gas guiding film 200, and in particular, the adhesive resin layer 210, which will be described later, so as to directly contact the electrode leads 180. Therefore, when the lead film 190 is formed to protrude further outward than one end of the gas guiding film 200 from the battery case 110, the adhesion between the electrode leads 180 and the gas guiding film 200, as well as between the electrode leads 180 and the lead film 190, is strong, thereby preventing a decrease in durability due to increased internal pressure, and easily ensuring the area of ​​the gas permeable portion 230 on the gas guiding film 200, thereby achieving stable gas emission.

[0086] The lead film 190 can be disposed between the electrode lead 180 and / or the gas guiding film 200 and the battery compartment 110. For example, as Figure 2As shown, the lower box 110, lead film 190, electrode lead 180, gas guiding film 200, lead film 190 and upper box 110 can be stacked and arranged in this order in the platform section 150.

[0087] Figures 3 to 5 Is with Figure 2 The enlarged cross-sectional view corresponding to box A shows the lead film 190 including inorganic particles 191. Referring to these figures, the inorganic particles 191 in the lead film 190 will be described.

[0088] Reference Figure 3 According to an embodiment of the present invention, the pouch-type secondary battery includes inorganic particles 191 in the lead film 190. Additionally, the lead film 190 can be as follows: Figure 4 and Figure 5 It has a multilayer structure including at least one layer, as in the example. Specifically, the lead film 190 may include a bag adhesive layer 1901, a core layer 1902 and a lead adhesive layer 1903 stacked in sequence.

[0089] Inorganic particles 191 may be included in at least one layer selected from the group consisting of core layer 1902 and lead adhesive layer 1903, and preferably may be included in core layer 1902. Additionally, as Figure 4 As shown, inorganic particles 191 may be included in the core layer 1902, and additionally may also be included in the lead adhesive layer 1903, and for example, as Figure 5 As shown, inorganic particles 191 can be included in two layers within the lead film 190. However, it may be desirable to exclude inorganic particles from the bag adhesive layer 1901. When the bag adhesive layer also includes inorganic particles, gas venting performance is further improved, but the seal strength is reduced. Therefore, to improve the inherent durability of the battery, which depends on the adhesion between the battery case and the lead film, it may be desirable to exclude inorganic particles from the bag adhesive layer. When inorganic particles 191 are included in the lead film 190, they can be used to increase the porosity of the lead film 190, thereby allowing for better gas venting, and since inorganic particles can absorb hydrofluoric acid gas, a significant improvement in the function of preventing electrode lead corrosion caused by hydrofluoric acid gas generated inside the battery can also be expected.

[0090] The inorganic particles may include at least one selected from the group consisting of, for example, CaCO3, Ca(OH)2, CaCl2, CaO, KOH, NaOH, and Na2CO3, and preferably CaCO3, Ca(OH)2, CaCl2, and / or CaO, and more preferably CaCO3, Ca(OH)2, and / or CaO. When such inorganic particles are applied, the absorption performance for hydrofluoric acid gas may be excellent.

[0091] Additionally, the lead film may contain 1 wt% to 20 wt% of inorganic particles relative to its total weight. Preferably, it may contain 2 wt% to 18 wt%, 3 wt% to 17 wt%, or 5 wt% to 15 wt% of inorganic particles. When contained within these ranges, the inorganic particles provide the advantage of excellent removal of moisture or hydrofluoric acid gas without impairing the flexibility of the lead film. Furthermore, when the inorganic particles are contained in at least one of the three layers of the lead film, they may contain 5 wt% to 15 wt%, preferably 6 wt% or more, 7 wt% or more, relative to the total weight of each included layer. They may also contain 14 wt% or less, 13 wt% or less of inorganic particles. Containing inorganic particles within this range can contribute to the improvement and maintenance of the aforementioned performance.

[0092] Simultaneously, the bag adhesive layer 1901 can be a layer in direct contact with the battery case 110, particularly the sealant layer of the battery case 110. The bag adhesive layer 1901 can include, but is not limited to, polypropylene or polyolefin elastomer (POE). Specifically, the polymer contained in the bag adhesive layer 1901 can be a copolymer. The melting point of the bag adhesive layer 1901 containing the copolymer can be controlled within the aforementioned numerical range, and the bag adhesive layer 1901 has a melting point similar to that of the polymer in the sealant layer of the battery case 110, which is better for ensuring sealable processability. The bag adhesive layer 1901 can have a thickness of 40 μm to 100 μm, specifically 40 μm to 80 μm, more specifically 40 μm to 60 μm. When the thickness of the bag adhesive layer 1901 meets the aforementioned numerical range, it has the effect of ensuring that the residual amount of polymer (e.g., polypropylene) is sufficient to obtain the sealing strength between the electrode leads and the battery case 110.

[0093] The core layer 1902 may be a layer placed at the center of the lead film 190. The core layer 1902 may include, but is not limited to, additives such as polypropylene, polyolefin elastomer (POE), and / or colorants. In particular, the polymer contained in the core layer 1902 may be a homopolymer. When a homopolymer is included in the core layer 1902, the melting point of the core layer 1902 can be controlled within the aforementioned numerical range, and heat-induced deformation can be minimized, which is better for ensuring insulation. The core layer 1902 may have a thickness of 40 μm to 70 μm, particularly 50 μm to 70 μm, and more particularly 60 μm to 70 μm. When the thickness of the core layer 1902 meets the aforementioned numerical range, deformation caused by heat applied during fusion and sealing can be prevented, thereby providing a robust design effect in ensuring insulation.

[0094] The lead adhesive layer 1903 is in direct contact with the electrode lead 180 and can be used to adhere the lead film 190 to the electrode lead 180. The lead adhesive layer 1903 can comprise any material that readily adheres to the electrode lead 180. Specifically, the metal adhesive layer can comprise an acid-modified polyolefin. For example, the lead adhesive layer 1903 can comprise at least one of acid-modified polypropylene (PPa), acid-modified polyethylene (PEa), and plasma-treated polypropylene (PP), but is not limited thereto. The lead adhesive layer 1903 can have a thickness of 50 μm to 80 μm, particularly 50 μm to 75 μm, and more particularly 60 μm to 75 μm. When the thickness of the lead adhesive layer 1903 meets the above numerical range, the effect is to prevent pinholes and leakage at the edge portions during the fusion between the electrode lead and the lead film.

[0095] (5) Gas guiding membrane

[0096] On one hand, the gas guiding membrane 200 is used to discharge gas from the inside of the battery compartment 110 to the outside. For example... Figure 2 As shown, the gas guiding membrane 200 of the present invention can be disposed between the electrode lead 180 and the lead film 190. In this case, in the region between the electrode lead 180 and the lead film 190 where the gas guiding membrane 200 is disposed, the electrode lead 180 and the lead film 190 may not be in direct contact, while in the region where the gas guiding membrane 200 is not disposed, the electrode lead 180 and the lead film 190 may be in direct contact.

[0097] In the following text, reference will be made to Figure 3 and Figure 6 The gas guiding membrane 200 of the present invention will be described in more detail. Figure 3 The diagram shows the state of the pouch cell before the interface between the gas guiding membrane 200 and the lead membrane 190 is opened. Figure 4 This shows the state after the interface between the gas guiding membrane 200 and the lead membrane 190 has been opened.

[0098] like Figure 3 and Figure 6As shown, the interface between the gas guiding membrane 200 and the lead membrane 190 is typically closed, and when the pressure inside the battery case 110 increases due to gas generation, the interface between the gas guiding membrane 200 and the lead membrane 190 opens, thereby forming a gas emission path 300. Gas inside the battery case 110 can move along the gas emission path 300 and then pass through the lead membrane 190 to be discharged to the outside of the bag. Therefore, the pressure inside the battery case 110 can be reduced to prevent the secondary battery 110 from exploding or igniting. In this case, the lead membrane 190 comprises inorganic particles 191, and thus can increase the gas emission rate, effectively prevent moisture penetration, and prevent corrosion of the electrode leads by absorbing internally generated hydrofluoric acid gas.

[0099] At the same time, such as Figure 3 and Figure 4 As shown, the gas guiding membrane 200 of the present invention includes an adhesive resin layer 210 in contact with the electrode lead 180 and a permeable resin layer 220 disposed on the adhesive resin layer 210.

[0100] The adhesive resin layer 210 contacts the electrode lead 180 and can be used to adhere the gas guiding membrane 200 to the electrode lead 180.

[0101] On the one hand, such as Figure 3 and Figure 7 As shown, the adhesive resin layer 210 of the gas guiding membrane 200 can be formed to extend further than the permeable resin layer 220 in the outward direction of the battery case. Therefore, when the adhesive resin layer 210 is formed to protrude further outward from one end of the permeable resin layer 220, the adhesion between the electrode lead 180 and the gas guiding membrane 200 is strong, thereby preventing a decrease in durability due to increased internal pressure and frequent opening of the lead membrane 190 and the gas guiding membrane 200, and easily ensuring the area of ​​the gas permeable portion 230 on the permeable resin layer 220, thereby achieving stable gas emission.

[0102] Alternatively, as in the above Figure 8 As described, the lead film 190 can be configured such that one end protruding outward from the battery case 110 protrudes further than one end of the gas guiding film 200 protruding outward from the battery case 110, thereby directly contacting the electrode lead 180. For example... Figure 7 As shown, the adhesive resin layer 210 can be configured such that one end protruding to the outside of the battery case 110 protrudes further than one end of the permeable resin layer 220 protruding to the outside of the battery case 110, but the lead film 190 does not directly contact the electrode lead 180, but contacts the adhesive resin layer 210.

[0103] Compared to the case where the lead wire 190 is not configured such that one end protrudes further outward from the battery case 110 than the permeable resin layer 220 of the gas guiding membrane 200, but is instead disposed on the permeable resin layer 220 of the gas guiding membrane 200, as Figure 3 , Figure 7 or Figure 8 The arrangement of the lead membrane 190, electrode leads 180, and gas guiding membrane 200 is more advantageous in ensuring durability and the area of ​​the permeable portion 230. Most preferably, the arrangement can be as follows: Figure 3 Same as in the middle, but Figure 7 or Figure 8 The structure has no performance drawbacks; the only differences may lie in the design or manufacturing process.

[0104] The adhesive resin layer 210 may comprise any material that readily adheres to the electrode leads 180. Specifically, the adhesive resin layer 210 may comprise a modified polyolefin resin. When the adhesive resin layer 210 comprises a modified polyolefin resin, the adhesive strength between the gas guiding membrane 200 and the electrode leads 180 is improved, and therefore, even when the pouch-type secondary battery is stored in a high-temperature environment, the gas guiding membrane 200 is prevented from detaching from the electrode leads 180 and being pushed out of the pouch, or electrolyte leakage from inside the pouch is prevented.

[0105] The adhesive resin layer 210 may include at least one of an acid-modified polyolefin or a silane-modified polyolefin.

[0106] Acid-modified polyolefins refer to polyolefin resins that have been grafted with acid. For example, acid-modified polyolefins can be obtained by reacting an unsaturated carboxylic acid with a polyolefin resin to introduce carboxyl groups (grafting modification). In this case, the unsaturated carboxylic acid can include the concept of carboxylic anhydride, and the carboxyl group can include the concept of a carboxylic anhydride group. The unsaturated carboxylic acid reacting with the polyolefin resin can include, but is not limited to, at least one selected from the group consisting of maleic acid, fumaric acid, itaconic acid, citraconic acid, pentenepic acid, tetrahydrophthalic acid, aconitic acid, maleic anhydride, itaconic anhydride, pentenepic anhydride, citraconic anhydride, aconitic anhydride, norbornene anhydride, and tetrahydrophthalic acid. In particular, the application of maleic anhydride is preferred to improve the adhesion between the gas guiding membrane 200 and the electrode lead 180. Acid-modified polyolefins can include, but are not limited to, at least one selected from the group consisting of acid-modified polypropylene (PPa) and acid-modified polyethylene (PEa).

[0107] Silane-modified polyolefins refer to polyolefin resins grafted with unsaturated silane compounds. Silane-modified polyolefins may have a structure in which unsaturated silane compounds are grafted copolymerized to the polyolefin resin as the main chain. Silane-modified polyolefin-based resins may include, but are not limited to, at least one selected from the group consisting of silane-modified polypropylene resins and silane-modified ethylene-vinyl acetate copolymers.

[0108] The adhesive resin layer 210 can be modified, and examples of modification treatments include ion implantation, plasma treatment, irradiation, heat treatment, etc., with treatments that alter the bond structure of the polymer layer being preferred. These modification treatments can be performed individually or in combination of two or more types. The modified adhesive resin layer 210 may include, but is not limited to, plasma-treated polypropylene (PP).

[0109] The adhesive resin layer 210 can have a thickness of 5 μm to 130 μm, particularly 30 μm to 120 μm, and even more particularly 30 μm to 80 μm. When the thickness of the adhesive resin layer 210 meets the above numerical range, the adhesive resin layer 210 melts within a specified production time (cycle time), and therefore, the gas guiding film 200 and the electrode lead 180 can be easily fused together.

[0110] The permeable resin layer 220 may be a layer that contacts the lead film 190.

[0111] The permeable resin layer 220 may include, but is not limited to, at least one of polytetrafluoroethylene (PTFE) or polyimide (PI). In particular, when polyimide is included in the permeable resin layer 220, the adhesive force between the permeable resin layer 220 and the lead film 190 is reduced, and therefore, when the pressure inside the housing 110 increases, a gas venting path 300 can preferably be formed.

[0112] The thickness of the permeable resin layer 220 can be from 40 μm to 100 μm, particularly from 40 μm to 90 μm, and even more particularly from 45 μm to 75 μm. When the thickness of the permeable resin layer 220 meets the above range, the permeable resin layer 220 will not melt during the sealing process, and when the pressure inside the housing 110 increases, the interface between the permeable resin layer 220 and the lead membrane 190 can be lifted to form a gas venting path 300.

[0113] Meanwhile, the ratio (D1 / D2) of the thickness of the adhesive resin layer (D1) to the thickness of the permeable resin layer (D2) can be 0.4 to 2.0, specifically 0.4 to 1.5, and more specifically 0.4 to 1.0. When the ratio (D1 / D2) meets the above numerical range, after the pressure inside the housing 110 increases, the interface between the permeable resin layer 220 and the lead membrane 190 is lifted to form a gas emission path, and the adhesive strength between the gas guiding membrane 200 and the electrode lead 180 can also be improved.

[0114] On one hand, the gas emission path 300 formed by opening the interface between the gas guiding membrane 200 and the lead membrane 190 may include: a gas permeable portion 230 formed on the outside of the sealing portion 151; and at least one gas channel 240 formed such that the gas permeable portion 230 and the interior of the battery box 110 are connected to each other via the sealing portion 151.

[0115] Additionally, the gas guiding membrane 200 may have at least one gas channel 240, preferably at least two gas channels, and there is no limitation on the number of channels. However, considering the processability and ease of use in the production of the gas guiding membrane, it may be desirable to form at least two gas channels 240.

[0116] Figure 9 and Figure 10 According to the embodiment, the electrode lead 180 and lead film 190, i.e., when viewed from direction B. Figure 2 A top perspective view of a portion of box A in the figure, wherein the platform portion 150 of the battery case 110 is omitted, and the sealing portion 151, as a sealing portion, is depicted as a region. As described above, the gas guiding film 200 is disposed on the electrode leads 180 and can be stacked in the order of adhesive resin layer 210 and permeable resin layer 220. The lead film 190 is disposed on the gas guiding film 200, and the platform portion 150 of the battery case 110 is disposed on the lead film 190, thereby forming an encapsulation structure, and the sealing portion 151 can be formed by sealing on the platform portion 150.

[0117] Reference Figure 9When the interface opens due to increased internal pressure of the pouch-type secondary battery, the gas guiding membrane 200 and the lead membrane 190 form a gas discharge path 300. A gas-permeable portion 230 for gas to permeate through is formed on the outside of the sealing portion 151, thereby allowing gas trapped through the gas channel 240 to be discharged through the lead membrane 190, and the gas channel 240 forms a path through the sealing portion 151 connecting the gas-permeable portion 230 to the interior of the battery compartment 110, thereby enabling gas to move to the gas-permeable portion 230. The gas channel 240 can be formed as a single unit, in which case the gas channel can have, for example, Figure 9 The "ㅜ" shape shown can form two gas channels 240, in which case the channels can have the following characteristics: Figure 10 The shape shown is "ㅠ".

[0118] In this configuration, the gas-permeable portion 230 and the gas channel 240 can be distinguished by a dividing line horizontal to the width direction of the electrode lead 180, which is formed in... Figure 9 or Figure 10 The point where the angle of the extension line of the gas channel 240 relative to the straight line in the length direction of the electrode lead 180 outside the sealing part 151 changes in the top perspective perspective, and the internal region of the battery box 110 can be defined as the gas channel 240, while the external region can be defined as the gas permeation part 230.

[0119] The gas guiding membrane can have a gas emission coefficient (C) of 10 to 25 as defined by Equation 1 below. R ).

[0120] [Formula 1]

[0121] C R = 2 (S) A / W L )+W P

[0122] In Equation 1, W P W is the total width (mm) of at least one gas channel. L It is the width of the electrode lead (mm), and S A It is the area of ​​the permeable portion (mm²) 2 ).

[0123] The gas emission coefficient is a value designed based on the dimensions of the gas guiding membrane, independent of the membrane material, and is characterized by taking into account the area of ​​the permeable portion, the width of the gas channel, and the width of the electrode leads. A larger permeable portion area and a wider gas channel are advantageous for the gas emission rate; however, conversely, from the perspective of preventing moisture penetration and electrolyte leakage, larger dimensions are more likely to cause complex problems. Furthermore, when the area of ​​the permeable portion on the gas guiding membrane increases relative to the width of the electrode leads, the increase in gas emission performance is insufficient to justify the increase in the permeable portion area, making it an unsuitable design when considering the possibility of moisture penetration and electrolyte leakage. Moreover, when the width of the gas channel increases relative to the area of ​​the permeable portion, a complex relationship is formed where the gas emission rate increases and the operating pressure decreases, but moisture penetration occurs.

[0124] In other words, gas guiding membranes with a large gas permeable area exhibit excellent performance. However, to improve gas emission performance, prevent moisture penetration, and prevent electrolyte leakage, the area of ​​the gas permeable portion needs to be increased within the limitations of the electrode lead width and the gas channel width. Therefore, a gas guiding membrane according to an embodiment of the present invention, having a gas emission coefficient as defined by Equation 1, has a rapid gas emission rate, can prevent electrolyte leakage and moisture penetration, and can operate at low internal pressure.

[0125] Preferably, the gas emission coefficient can be 11 or greater, 12 or greater, 13 or greater, or 14 or greater, and can also be 24 or less, 23 or less, 22 or less, or 21 or less. When the gas emission coefficient meets the above ranges, a gas guiding membrane that can meet the requirements of waterproof performance, electrolyte leakage prevention performance, and gas emission performance can be realized.

[0126] On the one hand, the area of ​​the permeable portion of the gas guiding membrane (S) A ) and the width of the electrode leads (W) L The ratio of (S) A / W L The diameter can be from 1.7 mm to 7.5 mm, preferably 1.9 mm or larger, 2.2 mm or larger, 2.5 mm or larger, or 2.7 mm or larger, and is also preferably 7.0 mm or smaller, 6.5 mm or smaller, 6.0 mm or smaller, 5.5 mm or smaller, or 5.0 mm or smaller.

[0127] On the one hand, the total width of the gas channels in the gas guiding membrane (W) P The width of the gas channels in the gas guiding membrane can be from 6 mm to 20 mm. Preferably, the total width of the gas channels in the gas guiding membrane (W) PThe diameter can be 7 mm or larger, 8 mm or larger, 9 mm or larger, or 10 mm or larger, and can be 18 mm or smaller, 16 mm or smaller, 15 mm or smaller, or 14 mm or smaller.

[0128] On the one hand, the gas emission coefficient of the gas guiding membrane can be defined as "the area of ​​the permeable portion (S)". A ) and the width of the electrode leads (W) L The ratio of (S) A / W L ")" and "the sum of the widths of the gas channels (W)" P The sum of the permeable portion of the electrode leads and the width of the gas channels is, in other words, when the sum of the areas of the permeable portions of the leads and the width of the gas channels are within a range of mutually suitable values, i.e. when the sums are kept within a suitable range to complement each other, this may be advantageous in terms of gas emission performance, prevention of moisture penetration, and prevention of electrolyte leakage.

[0129] Furthermore, when batteries become larger and are designed as modules and battery packs, various variables may exist, such as the battery cell itself becoming larger or multiple small battery cells being assembled. However, regarding the gas emission coefficient, it can be reflected by the size of the battery cell through the width of the electrode leads. Based on the amount of gas produced, an appropriate design point is determined in a triple trade-off between gas emission rate, moisture permeation, and operating pressure.

[0130] Therefore, the pouch-type secondary battery described in this specification—equipped with the aforementioned gas guiding membrane and including inorganic particles in the gas-permeable lead membrane—is able to release gas at an extremely high rate under low operating pressure, effectively preventing electrolyte leakage and moisture penetration, and minimizing corrosion caused by gas, moisture penetration, or electrolyte leakage, thereby improving durability to extend service life, maintaining battery cell operating performance through continuous gas release, and reducing the risk of expansion-related explosions, thereby ensuring safety.

[0131] electrolytes

[0132] On one hand, the pouch-type secondary battery 100 may also include an electrolyte (not shown) injected into the battery case 110. The electrolyte is used to move lithium ions generated by an electrochemical reaction at the electrodes during charging / discharging of the secondary battery 100, and may include a non-aqueous organic electrolyte solution as a mixture of lithium salt and organic solvent, or a polymer electrolyte. Additionally, the electrolyte may include a sulfide-based solid electrolyte, an oxide-based solid electrolyte, or a polymer-based solid electrolyte, and such solid electrolyte may be flexible and therefore easily deformable under external force.

[0133] Battery box

[0134] In one aspect, a battery case including a pouch-type secondary battery is provided. The battery case may include the pouch-type secondary battery and a package containing the pouch-type secondary battery. The pouch-type secondary battery may be configured to charge and release electrical energy, and in this case, the pouch-type secondary battery may be a secondary battery according to the embodiments described above in this specification.

[0135] To increase the capacity or voltage of the battery box, multiple pouch-type secondary batteries can be configured. These multiple pouch-type secondary batteries can be arranged in a predetermined manner, such as stacking them in one direction, but there are no particular restrictions on the arrangement method.

[0136] The package can be configured to house the secondary battery and protect it from external contamination or impact. For example, the package can have a shell shape, but there are no particular restrictions on the structure or shape of the package, as long as it can accommodate the secondary battery.

[0137] In addition, for the operation or safety of the battery box according to embodiments of the present invention, components performing predetermined functions may be installed in the package. For example, the package may also be equipped with connectors or busbars to electrically connect the secondary battery to the outside, and with vent plugs to connect the inside and outside of the package.

[0138] The battery box can be used to include, for example, battery modules or battery packs, and can include a package and battery cells, wherein multiple secondary batteries are housed within the package.

[0139] Electrical installations

[0140] In one aspect, an electrical device including a battery compartment is provided. The battery compartment can be included in the electrical device and serves as a power source for the electrical device.

[0141] Electrical installations can be at least any type of medium- or large-scale installation, such as: power tools; electric vehicles, including electric vehicles (EVs), hybrid vehicles, and plug-in hybrid electric vehicles (PHEVs); or electrical storage systems.

[0142] The invention will be described in more detail below through specific embodiments. However, the examples shown below are merely for understanding the invention, and the scope of the invention is not limited thereto. It will be apparent to those skilled in the art that various modifications and alterations can be made within the scope and technical range of the invention, and that such modifications and alterations fall within the scope of the claims included herein.

[0143] Examples and Comparison Examples

[0144] Example 1

[0145] (1) Manufacturing of the battery box

[0146] A polyethylene terephthalate (PET) film with a width of 266 mm, a length of 50 m, and a thickness of 12 μm, and a nylon film with a width of 266 mm, a length of 50 m, and a thickness of 25 μm are stacked on one side of an aluminum alloy film with a width of 266 mm, a length of 50 m, and a thickness of 60 μm. A polypropylene film with a width of 266 mm, a length of 50 m, and a thickness of 80 μm is stacked on the other side to prepare a bag film laminate with a structure of polyethylene terephthalate / nylon / aluminum alloy film / polypropylene film.

[0147] In this case, polyethylene terephthalate film and nylon film are the base layer, aluminum alloy film is the gas barrier layer, and polypropylene film is the sealant layer.

[0148] Molded bag film laminates are used to manufacture battery boxes that include housing and sealing portions.

[0149] (2) Manufacturing of pouch-type secondary batteries

[0150] The negative electrode, positive electrode, and porous polyethylene separator are assembled using a stacking method, and then the negative electrode, positive electrode, and porous polyethylene separator are laminated to manufacture the electrode assembly. Electrode leads are then connected to the electrode assembly.

[0151] LiPF6 was dissolved in a solvent (EC:EMC:DMC = 3:3:4 volume ratio) to 1.0 M to prepare the electrolyte. The electrode assembly was housed in a battery case, with the front ends of the electrode leads protruding to the outside and injected with the electrolyte.

[0152] A 40 μm thick acid-modified polypropylene film (adhesive resin layer) and a 50 μm thick polytetrafluoroethylene film (permeable resin layer) are stacked on the upper surface of the electrode leads to form a gas guiding film.

[0153] Then, a 200 μm thick lead film is stacked on each of the lower surface of the electrode leads and the upper surface of the gas guiding membrane. The lead film may include a 75 μm thick lead adhesive layer containing copolymer polypropylene and acid-modified polypropylene, a 65 μm thick core layer containing homopolymer polypropylene, and a 60 μm thick bag adhesive layer containing copolymer polypropylene, and 8 wt% CaCO3 as inorganic particles are disposed in the core layer relative to the total weight of the core layer to form the lead film.

[0154] Subsequently, under conditions of a sealing strip area of ​​200 mm x 10 mm, 220°C, and 0.27 MPa, the sealing portion of the battery box was sealed for 2 seconds and then placed at 60°C for 4 hours to manufacture a pouch-type secondary battery. In this case, the portion of the platform section in which the gas guiding film is formed has a structure in which the lower box / lead film / electrode lead / gas guiding film / lead film / upper box are stacked in sequence.

[0155] Example 2

[0156] The pouch-type secondary battery was manufactured in the same manner as in Example 1, except that, relative to the total weight of each layer, 8 wt% of CaCO3 was set as inorganic particles in each of the core layer of the lead film and the lead adhesive layer.

[0157] Comparison Example 1

[0158] The pouch-type secondary battery is manufactured in the same manner as in Example 1, except that a lead film without inorganic particles is applied.

[0159] Experimental Example 1: Measurement of Gas Emission Rate

[0160] The gas emission rates of the pouch cells manufactured in Example 1 and Example 2, as well as in Comparative Example 1, were measured.

[0161] Specifically, CO2 was injected into the pouch-type secondary battery using a pressure device from ITS to increase the pressure inside the bag to 1.5 atm and 2 atm, and the amount of gas emitted every 24 hours was measured over 72 hours. The results are shown in Table 1 below.

[0162] [Table 1]

[0163]

[0164] Referring to Table 1 above, it is determined that, compared to Comparative Example 1, Examples 1 and 2, which include inorganic particles, exhibit significantly improved gas emission rates. In particular, it is determined that the difference is even more pronounced at higher internal pressures, suggesting that Examples 1 and 2 may be more suitable for application in battery cells with high gas generation, and that even if not applied to batteries with high gas generation, Examples 1 and 2 may make a significant contribution to ensuring safety.

[0165] Experimental Example 2: Measurement of Water Permeability (HF Concentration Measurement)

[0166] HF concentration was measured for the pouch-type secondary batteries manufactured in Example 1 and Example 2, and Comparative Example 1, respectively, to assess moisture permeation.

[0167] The pouch cell was left to stand for 16 weeks at 60°C and 90% relative humidity. The cell was then opened and the HF concentration in the electrolyte was measured for evaluation. The results are shown in Table 2 below.

[0168] [Table 2]

[0169]

[0170] Referring to Table 2 above, it is determined that, compared to Comparative Example 1, Examples 1 and 2 show a reduction in moisture permeation. While the difference in effect may not be considered significant, it is generally observed that designs aimed at increasing gas emission rate or volume are always accompanied by an increase in moisture permeation. However, Examples 1 and 2 show improved gas emission performance compared to Comparative Example 1, without a simultaneous increase in moisture permeation, confirming that the pouch-type secondary battery according to embodiments of the present invention can improve gas emission performance without increasing moisture permeation.

[0171] Explanation of reference numerals in the attached figures

[0172] 100: Pouch-type secondary battery

[0173] 110: Battery Box

[0174] 120: First box

[0175] 122: Cup-shaped part

[0176] 124: Containment section

[0177] 130: Second box

[0178] 132: Cup-shaped part

[0179] 140: Bridging section

[0180] 150: Platform Section

[0181] 151: Sealing part

[0182] 160: Electrode assembly

[0183] 170: Electrode contacts

[0184] 172: Positive electrode connector

[0185] 174: Negative electrode connector

[0186] 180: Electrode lead

[0187] 182: Positive lead

[0188] 184: Negative lead

[0189] 190: Lead film

[0190] 191: Inorganic particles

[0191] 1901: Bag adhesive layer

[0192] 1902: Core

[0193] 1903: Lead adhesive layer

[0194] 200: Gas guiding membrane

[0195] 210: Adhesive resin layer

[0196] 220: Permeable resin layer

[0197] 230: Permeable portion

[0198] 240: Gas Channel

[0199] 300: Gas Emission Pathways

Claims

1. A pouch-type secondary battery, comprising: Electrode assembly; A battery case, the battery case including a receiving portion for accommodating the electrode assembly and a platform portion formed along the periphery of the receiving portion; Electrode leads, which are connected to the electrode assembly and protrude to the outside of the battery compartment via the platform portion; Lead film, the lead film being disposed between the electrode leads and the battery compartment; and A gas guiding membrane is disposed between the electrode lead and the lead film. The platform portion includes a sealing portion, in which a portion of the platform portion is sealed along the periphery of the receiving portion, and The lead film comprises inorganic particles.

2. The pouch-type secondary battery according to claim 1, wherein When the internal pressure of the battery box increases, the interface between the lead film and the gas guiding film is opened to form a gas emission path.

3. The pouch-type secondary battery according to claim 2, wherein The gas emission path includes: a gas-permeable portion formed on the outside of the sealing portion; and at least one gas channel formed to connect the gas-permeable portion to the interior of the battery box via the sealing portion.

4. The pouch-type secondary battery according to claim 1, wherein The lead film has a structure in which a bag adhesive layer, a core layer and a lead adhesive layer are sequentially stacked, and the inorganic particles are disposed in at least one layer selected from the group consisting of the core layer and the lead adhesive layer.

5. The pouch-type secondary battery according to claim 1, wherein The lead film has a structure in which a bag adhesive layer, a core layer and a lead adhesive layer are sequentially stacked, and the inorganic particles are disposed in the core layer.

6. The pouch-type secondary battery according to claim 5, wherein The inorganic particles are also disposed in the lead adhesive layer.

7. The pouch-type secondary battery according to claim 1, wherein The inorganic particles include at least one selected from the group consisting of CaCO3, Ca(OH)2, CaCl2, CaO, KOH, NaOH, and Na2CO3.

8. The pouch-type secondary battery according to claim 1, wherein The inorganic particles comprise an amount of 1 wt% to 20 wt% relative to the total weight of the lead film.

9. The pouch-type secondary battery according to claim 1, wherein The lead film is configured such that one end of the lead film protruding to the outside of the battery compartment protrudes further than one end of the gas guiding film protruding to the outside of the battery compartment, and is in direct contact with the electrode lead.

10. The pouch-type secondary battery according to claim 1, wherein The gas guiding membrane has a structure in which an adhesive resin layer and a permeable resin layer are stacked from the upper surface of the electrode leads.

11. The pouch-type secondary battery according to claim 10, wherein The adhesive resin layer comprises at least one selected from the group consisting of acid-modified polypropylene (PPa) and acid-modified polyethylene (Pea).

12. The pouch-type secondary battery according to claim 10, wherein The permeable resin layer comprises at least one selected from the group consisting of polyimide (PI) and polytetrafluoroethylene (PTFE).

13. The pouch-type secondary battery according to claim 10, wherein The ratio (D1 / D2) of the thickness of the adhesive resin layer (D1) to the thickness of the permeable resin layer (D2) is 0.4 to 2.

0.

14. The pouch-type secondary battery according to claim 10, wherein One end of the adhesive resin layer that protrudes outward from the battery box protrudes further than one end of the permeable resin layer that protrudes outward from the battery box.

15. A battery pack comprising: The pouch-type secondary battery according to claim 1; And a package for accommodating the pouch-type secondary battery.

Images