Lithium secondary battery module with enhanced safety

Abstract

The present invention relates to a lithium secondary battery and a lithium secondary battery module equipped with the same. The lithium secondary battery has the advantage of high safety because, by arranging a fire extinguishing member to be directly connected to the end of a sealing portion on the outside of a case in which an electrode assembly is housed, particularly at a high frequency of spark emission, it can weaken the force of the spark by inducing direct contact with the fire extinguishing member when a spark generated inside the secondary battery is emitted.

Description

Technology Field

[0001] The present invention relates to a lithium secondary battery module with enhanced safety. Background Technology

[0003] With technological advancements, interest in energy storage technology is growing, and as application fields expand to include mobile phones, camcorders, and laptop PCs, efforts to research and develop electrochemical devices are becoming increasingly concrete. Among electrochemical devices, the development of rechargeable batteries is becoming the focus of attention. In particular, lithium-ion batteries have an operating voltage of approximately 3.6V, which is larger than that of nickel-cadmium or nickel-hydrogen batteries widely used as power sources for electronic equipment. Furthermore, due to their high energy density per unit weight, their utilization is rapidly increasing. Recently, pouch-type rechargeable batteries, which consist of an electrode assembly and an electrolyte enclosed in a film pouch and sealed, have become widely adopted due to their advantages of being easy to apply to electrical products of various designs and allowing for volume reduction.

[0004] These secondary batteries are attracting attention as power sources for electric vehicles (EVs) and hybrid electric vehicles (HEVs), which are being proposed as solutions to address air pollution caused by conventional gasoline and diesel vehicles that use fossil fuels. Medium to large battery modules or battery packs used for these purposes must electrically connect multiple lithium secondary batteries to provide the output and capacity required by a specific device, and must be able to maintain a stable structure against external forces.

[0005] However, since secondary batteries pose a risk of explosion if overheated, ensuring safety is one of the critical tasks. Overheating of secondary batteries occurs due to various causes, one of which is when an overcurrent exceeding a limit flows through the battery. When an overcurrent flows, the secondary battery generates heat through Joule heating, causing the internal temperature of the secondary battery to rise rapidly. Furthermore, this rapid rise in temperature triggers a decomposition reaction of the electrolyte, causing a thermal runaway phenomenon, which eventually leads to the explosion of the secondary battery. Overcurrent occurs when a sharp metal object penetrates the secondary battery, when the insulation between the positive and negative electrodes is destroyed due to the shrinkage of the separator interposed between them, or when a rush current is applied to the secondary battery due to an abnormality in an externally connected charging circuit or load.

[0006] Furthermore, while the numerous secondary batteries included in medium-to-large battery modules or battery packs offer the advantage of high output compared to other batteries, they have the disadvantage of being vulnerable to safety issues due to a high risk of explosion, as described above. When the aforementioned medium-to-large battery modules or packs contain a large number of secondary batteries, the safety issue becomes even more serious.

[0008] Furthermore, in the case of pouch-type rechargeable batteries, if a spark occurs inside the battery, the flame typically penetrates the sealed end of the pouch. The spark emanating from the battery then propagates to adjacent rechargeable batteries mounted within the battery module or battery pack, causing flames. This poses a serious problem where the fire spreads to the entire device, such as an electric vehicle, in which the battery module or pack is used. Therefore, there is a growing need to block the spark and / or flames generated within the rechargeable battery from propagating to the outside, thereby enabling a faster and more sensitive response to explosions caused by flames or dangerous situations involving medium-to-large battery modules or packs. Prior art literature

[0010] Republic of Korea Published Patent Application No. 10-2017-0014309 The problem to be solved

[0011] Accordingly, the objective of the present invention is to provide a lithium secondary battery capable of weakening a flame generated when a fire occurs in a lithium secondary battery provided inside during use, and a lithium secondary battery module equipped with the same. means of solving the problem

[0013] In order to solve the aforementioned problem,

[0014] In one embodiment of the present invention,

[0015] An electrode assembly comprising an anode, a cathode, and a separator located between the anode and the cathode;

[0016] A case comprising an upper case and a lower case, wherein the edges of the upper case and the lower case are sealed to seal the interior; and

[0017] A lithium secondary battery is provided that includes a fire extinguishing member located outside the above case and containing a fire extinguishing agent.

[0018] At this time, the case includes a sealing portion that is bent by fusing the edges of the upper case and the lower case, and a fire extinguishing member may be connected to the end of the sealing portion.

[0019] Specifically, the sealing portion is folded and positioned on one side of the case, and the fire extinguishing member is positioned on the other side of the case where the sealing portion is positioned;

[0020] The fire extinguishing member is folded and positioned on one side of the upper or lower surface of the case, and the fire extinguishing member may be positioned on the upper or lower surface of the case where the sealing portion is positioned.

[0021] In addition, the sealing portion may have a shape that is bent two or more times.

[0022] In addition, the fire extinguishing member may comprise a fire extinguishing agent; and an outer material that accommodates the fire extinguishing agent.

[0023] Here, the exterior material includes an opening for introducing a fire extinguishing agent into the interior, and the opening may be connected to the end of the sealing part so that the fire extinguishing agent comes into contact with the end of the case sealing part.

[0024] In addition, the above-mentioned fire extinguishing agent may undergo a phase change into a gaseous state at a temperature of 100 to 300°C.

[0025] Specifically, the fire extinguishing agent may include one or more of halogenated carbons, halogenated ketones, halogenated alkanes, and inert gases.

[0027] Furthermore, in one embodiment of the present invention,

[0028] A lithium secondary battery according to the present invention as described above; and

[0029] A lithium secondary battery module having a housing in which the above-mentioned lithium secondary battery is mounted is provided. Effects of the invention

[0031] The lithium secondary battery according to the present invention has the advantage of high safety, as the force of a spark can be weakened by inducing direct contact with the extinguishing member when a spark generated inside the secondary battery is emitted, by arranging the extinguishing member to be directly connected to the end of the sealing portion, which is located outside the case where the electrode assembly is housed, particularly where the frequency of spark emission is high. Brief explanation of the drawing

[0033] FIG. 1 is an exploded view showing the structure of a lithium secondary battery according to the present invention before assembly. FIGS. 2 and FIGS. 4 are perspective views illustrating the exterior of a lithium secondary battery according to the present invention. Figure 3 is a cross-sectional view showing a schematic cross-sectional structure according to AA of Figure 2. FIG. 5 is a cross-sectional view showing the structure of the sealing portion and the extinguishing member of a lithium secondary battery according to the present invention. Specific details for implementing the invention

[0034] The present invention is capable of various modifications and may have various embodiments, and specific embodiments are to be described in detail in the detailed description.

[0035] However, this is not intended to limit the invention to specific embodiments, and it should be understood that it includes all modifications, equivalents, and substitutions that fall within the spirit and scope of the invention.

[0036] In the present invention, terms such as "comprising" or "having" are intended to specify the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not excluding in advance the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0037] Furthermore, in the present invention, when a part such as a layer, film, region, or plate is described as being "on" another part, this includes not only cases where it is "immediately above" the other part, but also cases where there is another part in between. Conversely, when a part such as a layer, film, region, or plate is described as being "under" another part, this includes not only cases where it is "immediately below" the other part, but also cases where there is another part in between. Additionally, in the present application, being "placed on" may include cases where it is placed on the lower part as well as on the upper part.

[0038] In addition, although terms indicating directions such as up, down, left, and right have been used in this invention, these terms are used merely for convenience of explanation, and it is obvious to those skilled in the art that they may vary depending on the position of the object or the position of the observer.

[0039] In addition, in the present invention, "flame" or "spark" is a particle having mass and energy, which may be generated in the positive composite layer when a short circuit occurs inside the battery cell during the use of the secondary battery module.

[0040] In addition, in the present invention, "flame" may refer to a form of flame that develops in terms of size or scale when a spark generated inside a secondary battery comes into contact with gas inside the battery and external air, particularly oxygen (O2).

[0042] The present invention will be described in more detail below.

[0044] lithium secondary battery

[0045] In one embodiment of the present invention,

[0046] An electrode assembly comprising an anode, a cathode, and a separator located between the anode and the cathode;

[0047] A case comprising an upper case and a lower case, wherein the edges of the upper case and the lower case are sealed to seal the interior; and

[0048] A lithium secondary battery is provided that includes a fire extinguishing member located outside the above case and containing a fire extinguishing agent.

[0050] The lithium secondary battery according to the present invention is configured such that when a spark occurs outside, particularly inside, a case in which an electrode assembly is housed, the spark is emitted at a high frequency at the end of a joint portion of the case, thereby allowing the spark to pass directly through the spark when it is emitted outside the case. By doing so, the lithium secondary battery can reduce the force of the spark, thereby providing the advantage of preventing the spark from propagating to adjacent battery cells or developing into a flame upon contact with the air outside the case.

[0051] As shown in FIG. 1, the lithium secondary battery according to the present invention includes a case (120) in which an electrode assembly (110) is accommodated, and the case (120) includes an upper case (121) and a lower case (122), and the edges (123) of each case (121 and 122) may have a sealing portion (not shown) having a folded structure formed by fusing, and the end of the sealing portion (not shown) may be connected to a fire extinguishing member (not shown).

[0052] At this time, the case (120) may include a receiving portion (125a and / or 125b) that accommodates an electrode assembly (110) in one or more of the upper case (121) and the lower case (122), and the edge (123) extending in the circumferential direction of the receiving portion (125a and / or 125b) may include a sealing portion (not shown) at the end that seals the electrode assembly (110) by fusing electrode leads (127a and 127b) with the electrode leads (127a and 127b) drawn out to the outside.

[0053] As an example, the above-described caisson may include an upper case and a lower case, wherein the upper case is provided in a plate-like shape overall, and the lower case may be provided with a receiving portion having a central area formed concavely so as to accommodate an electrode assembly. In this case, the receiving portion of the lower pouch may be formed to correspond to the height and width of the electrode assembly.

[0054] FIGS. 2 to 4 are perspective and cross-sectional views illustrating the exterior and cross-sectional structure of a lithium secondary battery according to the present invention. Referring to FIGS. 2 to 4, the case may form sealing portions (224 and 324) that are fused and mutually sealed at the edges of the upper case (221 and 321) and the lower case (222 and 322).

[0055] At this time, the sealing portion (224 and 324) immediately after sealing may be extended outwardly to the side of the case (220 and 320) in which the electrode assembly (210 and 320) is housed, that is, to the left side (LS), right side (RS), upper side (HS), and lower side (BS) of the secondary battery, and the sealing portion (224 and 324) extended in this way may be folded at least 180° and provided in a folded form parallel to the outer side of the case (i.e., the outer side expressed as the left side (LS), right side (RS), upper side (HS) and / or lower side (BS)).

[0056] As one example, the case (220 and 320) may include a sealing portion (224 and 324) that is fused at edges (223 and 323) and bent at least twice at 90 to 180°, and the sealing portion (224 and 324) may be positioned to contact the upper surface (H), outer sides (RS, LS, HS and BS) and / or lower surface (L) of the case.

[0057] As described above, the present invention can effectively prevent the leakage of electrolyte or the penetration of moisture into the case by folding the sealed portions (224 and 324) of the edges (223 and 323) of the case to form sealing portions, and has the advantage of excellent heat dissipation effect as the volume occupied by the sealing portions (224 and 324) can be minimized.

[0058] Additionally, the sealing portions (224 and 324) may be positioned on the side of the case among the upper surface (H), side (RS, LS, HS and BS) and lower surface (L) of the case, and may be arranged to be bent outward from the center of the side, that is, to make contact with one edge of the side, and the fire extinguishing member (230 and 330) may be positioned on the other side of the case where the sealing portions (224 and 324) are positioned.

[0059] As an example, FIG. 5 is a cross-sectional view illustrating the cross-sectional structure of a secondary battery (400) having a sealing portion (424) formed on an upper side (HS). Referring to FIG. 5, the secondary battery (400) is provided with a sealing portion (424) on a side (e.g., an upper side (HS), etc.), wherein the sealing portion (424) is positioned on the upper side (HS) adjacent to the upper case and can provide a space on the other side adjacent to the lower case, and a fire extinguishing member (430) can be placed in the space thus provided. To this end, the welding portion (411) of the electrode assembly (41) may be formed at one end of the electrode assembly (410), and accordingly, an electrode tab (e.g., positive electrode tab (426a)) and an electrode lead (e.g., positive electrode lead (427a)) electrically connected to the welding portion (411) may also be located at one end of the electrode assembly (41) and the case (42).

[0060] In addition, the sealing portion (224 and 324) may be positioned on the upper surface (H) or lower surface (L) of the case among the upper surface (H), side surfaces (RS, LS, HS and BS) and lower surface (L) of the case, and may be positioned so as to be bent and contacted on the outer side, that is, one edge of the upper surface or lower surface, and the extinguishing member (230 and 33) may be positioned adjacent to one edge of the upper surface (H) or lower surface (L) of the case where the sealing portion (224 and 324) is positioned.

[0061] Furthermore, the fire extinguishing member may be provided with a fire extinguishing agent and an outer material that accommodates the fire extinguishing agent, and the outer material may not only include an opening to introduce the fire extinguishing agent into the interior, but also, through direct connection with the end of the sealing portion of the case, preemptively contact the fire extinguishing agent when a spark generated inside the case is released to the outside, thereby weakening the force of the spark.

[0062] Here, the shape of the outer material is not particularly limited as long as the opening is structured to be directly connected to the end of the sealing portion, but specifically, it may have a pouch shape or a container shape, and since the internal temperature and / or volume may increase when flames emitted from inside the case come into contact with the fire extinguishing agent, it may be made of a material with high temperature resistance and volumetric fluidity.

[0063] As an example, the outer material may include a metal compound containing one or more metals selected from tungsten (W), tantalum (Ta), molybdenum (Mo), iridium (Ir), silicon (Si), vanadium (V), zinc (Zn), aluminum (Al), and titanium (Ti). Specifically, the metal compound may be in the form of a pouch comprising an elastic resin layer in which particles of a metal compound with high high temperature resistance, such as tungsten (W), tantalum (Ta), molybdenum (Mo), iridium (Ir), silicon (Si), vanadium (V), aluminum oxide (Al2O3), titanium dioxide (TiO2), silicon oxide (SiO2), vanadium oxide (V2O3), zinc oxide (ZnO), and tungsten oxide (WO3), are dispersed.

[0064] Furthermore, the aforementioned fire extinguishing agent may be used regardless of whether it is in powder, liquid, or gaseous form, as long as it is a type of fire extinguishing agent commonly used for conventional fire suppression, and various fire extinguishing agents applied in the industry may be utilized. Regarding the principle of extinguishing, suffocation extinguishing, cooling extinguishing, or extinguishing utilizing both of these principles may all be applicable.

[0065] Specifically, the above-mentioned fire extinguishing agent may be a substance with excellent fire extinguishing performance that has a main component not restricted in production and use by the Montreal Protocol, is in a liquid state at room temperature, and undergoes a phase change to a gaseous state at a specific temperature, for example, 100 to 300°C.

[0066] Examples of such fire extinguishing agents include halogenated carbons such as fluorine carbon, fluorine chlorine carbon, fluorine bromine carbon, fluorine iodine carbon, and iodofluorocarbon (FIC-217I1 or FIC-13I1);

[0067] Halogenated alkanes such as 2-iod-1,1,1,2,3,3,3-heptafluoropropane (HFC-227ea), 1,1,1,2,2-pentafluoroethane (CF3CF3H, HFC-125), 1,1,1,2,3,3,3-heptafluoropropane (CF3CHFCF3), chlorotetrafluoroethane (CHClFCF3), 1-chloro-1,2,2,2-tetrafluoroethane (C2HClF4), and 2-chloro-1,1,1,2-tetrafluoroethane (CHClFCF3, HCFC-124);

[0068] Dodecafluoro-2-methylpentan-3-one(FK-5-1-12, CF3CF2C(O)CF(CF3)2)), decafluorocyclohexanone(perfluorocyclohexanone), CF3CF2C(O)CF(CF3)2(-1,1,1,2,4,4,5,5,5-nonafluoro-2-trifluoromethyl-butan-3-one), (CF3)2CFC(O)CF(CF3)2(-1,1,1,2,4,5,5,5,6,6,6-octafluoro-2,4,-bis(trifluoromethyl)pentan-3-one), CF3CF2C(O)CF2CF2CF3, CF3C(O)CF(CF3)2, 1,1,1,3,3,4,4,5,5,6,6,7,7,8,8,8-hexadodecafluorooctane-2-one(CF3CF2CF2CF2CF2CF2C(O)CF3), 1,1,1,3,4,4,4-heptafluoro-3-trifluoromethylbutan-2-one(CF3C(O)CF(CF3)2), 1,1,1,2,4,4,5,5-octafluoro-2-trifluoromethylpentan-3-one(HCF2CF2C(O)CF(CF3)2), 1,1,1,2,4,4,5,5,6,6,6-undecafluoro-2-trifluoromethylhexane-3-one(CF3CF2CF2C(O)CF(CF3)2), 1-chloro-,1,1,3,4,4,4-hexafluoro-3-trifluoromethyl-butan-2-one((CF3)2CFC(O)CF2Cl), 1,1,1,2,2,4,4,5,5,6,6,6-dodecafluorohexane-3-one(CF3CF2C(O)CF2CF2CF3), 1,1,1,5,5,5-hexafluoropentane-2-4-dione(CF3C(O)CH2C(O)CF3), 1,1,1,2,5,6,6,6-octafluoro-2,5-bis(trifluoromethyl)hexane-3,4-dione((CF3)2CFC(O)C(O)C(O)CF(CF3)2), 1,1,1,2,2,3,3,5,5,6,6,7,7,7,-tetradecafluoroheptan-4-one(CF3CF2CF2C(O)CF2CF2CF3), 1,1,1,3,3,4,4,4-octafluorobutal-2-one(CF3C(O)CF2CF3), 1,1,2,2,4,5,5,5-octafluoro-1-trifluoromethoxy-4-trifluoromethylpentan-3-one(CF3OCF2CF2C(O)CF(CF3)2), 1,1,1,2,4,4,5,5,6,6,7,7,7,Halogenated ketones such as tridecafluoro-2-trifluoromethylheptane-3-one (CF3CF2CF2CF2C(O)CF(CF3)2), 1,1,1,2,2,3,4,5,5,5-decafluoro-3-methoxy-4-(trifluoromethyl)pentane; and,

[0069] It may include inert gases such as nitrogen gas (N2), argon gas (Ar), etc., either alone or in a mixed form.

[0070] As an example, the above-mentioned fire extinguishing agent may be one having the chemical formula CpHqOrXs (wherein p, q, r and s are integers from 0 to 20, and X is one or more of Br, I and F), and as an example, Novec 1230 of 3M may be used.

[0072] Meanwhile, the above case includes a gas barrier layer and a sealant layer, and may further include a surface protection layer as the outermost layer formed on the gas barrier layer. The gas barrier layer is intended to block the entry and exit of gas, and primarily uses an aluminum foil. The sealant layer is located at the innermost layer and can come into contact with the contents, i.e., the cell. Additionally, considering wear resistance and heat resistance, the surface protection layer may primarily use materials such as nylon resin. The above case is manufactured by processing a laminated film into a pouch or container shape, accommodates an electrode assembly equipped with a positive electrode, a negative electrode, and a separator, and injects an electrolyte. After the battery components are embedded in this manner, the sealant layers are heat-bonded to each other at the opening of the case to seal it. At this time, since the sealant layer comes into contact with the cell components, it must possess insulation properties as well as electrolyte resistance, and must have high sealing performance to ensure airtightness from the outside. The sealing area formed by the heat-bonding of the sealant layers must have excellent heat-bonding strength. Generally, polyolefin resins such as polypropylene (PP) or polyethylene (PE) are used for the sealant layer. In particular, polypropylene (PP) is primarily used as the sealant layer for pouches due to its excellent mechanical properties, such as tensile strength, stiffness, surface hardness, and impact resistance, as well as its resistance to electrolytes.

[0073] In addition, the plurality of secondary battery cells mounted in the above case can be applied without particular limitation as long as they are lithium secondary battery cells that are commonly used in the industry and capable of charging and discharging.

[0074] Meanwhile, the plurality of secondary battery cells mounted in the above case may be applied without particular limitation as long as they are lithium secondary battery cells capable of charging and discharging that are commonly used in the industry. Specifically, the secondary battery cell may be a pouch-type unit cell, and the pouch-type unit cell may be embedded in a state in which an electrode assembly is connected to electrode leads formed outside the outer casing.

[0075] Here, the electrode assembly is not shown in detail for the convenience of the drawing, but,

[0076] The electrode assembly comprises an anode, a cathode, and a separator located between the anode and the cathode, wherein the anode and the cathode each include electrode tabs. The electrode assembly may be a stacked type formed by interposing a separator between the stacked anode and cathode, or a jelly-roll type in which one anode and one cathode are wound with a separator in between; however, the scope of the present invention is not limited to such forms of electrode assemblies. Additionally, the anode may be formed by coating an anode active material onto a current collector plate made of aluminum (Al), and the cathode may be formed by coating a cathode active material onto a current collector plate made of copper (Cu). The electrode tabs include an anode tab corresponding to a region of the anode where the anode active material is not coated, and a cathode tab corresponding to a region of the cathode where the cathode active material is not coated.

[0077] The electrode leads are thin plate-shaped metals attached to the electrode tabs and extend outwardly to the electrode assembly, and include an anode lead attached to the anode tab and a cathode lead attached to the cathode tab. These anode leads and cathode leads may extend in different directions depending on the formation locations of the anode tabs and cathode tabs, or they may extend in the same direction.

[0078] The lithium secondary battery according to the present invention has the advantage of high safety of the secondary battery because, by having the configuration described above, it can weaken the force of the spark by inducing direct contact with the extinguishing member when the spark generated inside the secondary battery is released.

[0080] Lithium secondary battery module

[0081] Furthermore, in one embodiment of the present invention,

[0082] The lithium secondary battery of the present invention described above; and

[0083] A lithium secondary battery module having a housing in which the above-mentioned lithium secondary battery is mounted is provided.

[0085] The secondary battery module according to the present invention is equipped with the lithium secondary battery of the present invention described above, and has the advantage of high safety because it can weaken the force of the spark by inducing direct contact with a extinguishing member when a spark generated inside the secondary battery is released.

[0086] At this time, the lithium secondary batteries may be housed in a module case in a state where n or more (n is an integer greater than or equal to 2) are electrically connected. Specifically, the secondary battery cells may be electrically connected by adjusting the number of secondary battery cells (n) to 2 to 100, 2 to 50, 2 to 40, 10 to 35, 20 to 30, or 5 to 20, depending on the application of the battery module, and the electrical connection may be in series and / or parallel, and if necessary, a method in which series and parallel are mixed may be used.

[0087] In addition, the above secondary battery module can be used as a power source for medium-to-large devices requiring high temperature stability, long cycle characteristics, and high rate characteristics. Specific examples of such medium-to-large devices include power tools that are powered by an electric motor; electric vehicles including electric vehicles (EVs), hybrid electric vehicles (HEVs), and plug-in hybrid electric vehicles (PHEVs); electric two-wheeled vehicles including electric bicycles (E-bikes) and electric scooters (E-scooters); electric golf carts; and power storage systems. More specifically, hybrid electric vehicles (HEVs) can be cited, but are not limited thereto.

[0089] The present invention will be explained in more detail below through examples and experimental examples.

[0090] However, the following examples and experimental examples are merely illustrative of the present invention, and the content of the present invention is not limited to the following examples and experimental examples.

[0092] Examples 1–5. Manufacturing of secondary batteries

[0093] A plate-shaped upper case and a lower case equipped with a receiving portion were prepared. In this case, the upper case and the lower case were used to have a cross-sectional structure of a polypropylene (PP) layer / aluminum (Al) / biaxially stretched nylon (ONY) layer / polyethylene terephthalate (PET) layer.

[0094] Then, an electrode assembly with an electrode tab and a lead terminal connected was placed in the receiving portion of the lower case, and after the lead terminal was drawn out to the outside of the case, the edges of the upper case and the lower case were heat-fused to seal them.

[0095] After heat fusion, the fused edges were bent to form a sealing portion, and the number of bends and the position of the formed sealing portion were adjusted as shown in Table 1 below. Here, the position of the sealing portion was placed on the outside of the case, specifically on the top surface (H) or side surface (specifically, left side (LS), right side (RS), top side (HS), and bottom side (BS)) of the case as shown in FIG. 4. In addition, when the sealing portion was located on the side surface, it was positioned so as to be placed at one end adjacent to the upper case, and when it was located on the top surface, it was positioned at the edge adjacent to the side surface.

[0096] Subsequently, a lithium secondary battery was manufactured by joining a pouch-type fire extinguishing member filled with a fire extinguishing agent so that the opening covered the end of the sealing part. At this time, an elastic resin-based pouch with zinc oxide particles dispersed inside was used as the pouch, and the fire extinguishing member was positioned on the other side of the sealing part.

[0097] Number of bends in the sealing part Sealing part location Example 1 1 time One end of RS and LS on the case side Example 2 2nd time One end of RS and LS on the case side Example 3 2nd time One side of the case, specifically the HS and BS Example 4 2nd time One end of RS, LS, HS, and BS among the case sides Example 5 2nd time One end adjacent to RS and LS among the upper surface (H) of the case

[0099] Comparative Example 1. Manufacture of a lithium secondary battery

[0100] A lithium secondary battery was manufactured in the same manner as in Example 1, except that it was not equipped with a fire extinguishing member.

[0102] Comparative Example 2. Manufacture of a lithium secondary battery

[0103] A lithium secondary battery was manufactured in the same manner as in Example 1, except that the position of the fire extinguishing member was adjusted so that it was located inside the case.

[0105] Experimental Example.

[0106] To evaluate the safety of the secondary battery according to the present invention, the following experiment was performed.

[0108] In order to apply heat to the secondary batteries, a heating pad was attached to the secondary batteries produced in the examples and comparative examples. Then, each produced secondary battery was fully charged, and the heating pad attached to the secondary battery was heated at a rate of 7°C / min.

[0109] When the temperature rises, heat transfer between the secondary batteries is gradually induced, causing sparks to be generated from each installed secondary battery. These sparks are released outside the secondary battery case and come into contact with air, causing a flame to form. Here, the safety of the secondary battery was evaluated by measuring the time taken from the start of the temperature rise until a flame forms outside the secondary battery case. The results are shown in Table 2 below.

[0110] Time required from charging to flame generation Example 1 61 seconds Example 2 65 seconds Example 3 68 seconds Example 4 77 seconds Example 5 64 seconds Comparative Example 1 29 seconds Comparative Example 2 53 seconds

[0112] As shown in Table 2 above, it can be seen that the safety of the secondary battery according to the present invention is improved by introducing a fire extinguishing member at the end of the sealing portion formed on the outside where the case is joined.

[0113] Specifically, in the lithium secondary battery of the embodiment according to the present invention, by introducing a fire extinguishing member containing a fire extinguishing agent into a sealing part formed on the outside of the case, it was found that it takes more than 60 seconds for a flame to occur on the outside due to a flame generated inside the case.

[0114] On the other hand, it was confirmed that for the comparative example lithium secondary battery that does not have a fire extinguishing element or has it inside the case, it takes less than 55 seconds for a flame to occur outside the secondary battery case.

[0115] This means that when a hydration element is provided at the end of the sealing portion—a joint of the case where the frequency of flame release is high when a flame occurs inside the case—on the exterior of the lithium secondary battery case, the flame released to the outside comes into direct contact with the extinguishing agent of the extinguishing element, thereby weakening its force and causing a delay in the occurrence of a flame from the outside.

[0116] From these results, it can be seen that the safety of the secondary battery according to the present invention is improved because the force of the flame can be significantly weakened by arranging the extinguishing member to be directly connected to the outer end of the sealing portion, which is the outer side where the electrode assembly is accommodated, particularly where the frequency of flame emission is high.

[0118] Although the present invention has been described above with reference to preferred embodiments, those skilled in the art or those with ordinary knowledge in the relevant technical field will understand that various modifications and changes can be made to the present invention without departing from the spirit and technical scope of the invention as set forth in the claims below.

[0119] Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification, but should be determined by the claims. Explanation of the symbols

[0121] 100, 200, 300, and 400: Lithium secondary battery 110, 210, and 410: Electrode assemblies 120, 220, and 320: Case 121, 221, 321, and 421: Upper case 122, 222, 322, and 422: Lower case 123, 223, and 323: Case edges 125a and 125b: Reception section 126b: Negative tab 127a, 227a, 327a, and 427a: Positive leads 127b. 227b and 327b: Cathode lead 224, 324, and 424: Sealing parts 230, 330 and 430: Fire extinguishing member 411: Welding section H: Top surface L: If RS: Right side LS: Left side HS: Upper side BS: Lower side

Claims

Claim 1 An electrode assembly comprising a positive electrode, a negative electrode, and a separator located between the positive electrode and the negative electrode; a case comprising an upper case and a lower case, wherein the edges of the upper case and the lower case are sealed to seal the interior; and a fire extinguishing member located outside the case and comprising a fire extinguishing agent; wherein the case comprises a sealing portion formed by fusing the edges of the upper case and the lower case and folding the sealing portion, and the fire extinguishing member is connected to the end of the sealing portion. Claim 2 delete Claim 3 In claim 1, the above-mentioned sealing portion is a lithium secondary battery that is bent two or more times. Claim 4 A lithium secondary battery according to claim 1, wherein the sealing portion is folded and disposed on one side of the case side, and the fire extinguishing member is disposed on the other side of the case side where the sealing portion is disposed. Claim 5 A lithium secondary battery according to claim 1, wherein the sealing portion is folded and disposed on one side of the upper or lower surface of the case, and the fire extinguishing member is disposed on the upper or lower surface of the case where the sealing portion is disposed. Claim 6 In claim 1, the fire extinguishing member comprises a fire extinguishing agent; and a lithium secondary battery having an outer casing that accommodates the fire extinguishing agent. Claim 7 In claim 6, the above-mentioned exterior material includes an opening for introducing a fire extinguishing agent into the interior, and the opening is connected to the end of the sealing portion so that the fire extinguishing agent comes into contact with the end of the case sealing portion, thereby forming a lithium secondary battery. Claim 8 In claim 1, the fire extinguishing agent is a lithium secondary battery that undergoes a phase change to a gaseous state at a temperature of 100 to 300°C. Claim 9 In paragraph 1, the fire extinguishing agent is a lithium secondary battery comprising one or more of halogenated carbons, halogenated ketones, halogenated alkanes, and inert gases. Claim 10 A lithium secondary battery according to claim 1; and a lithium secondary battery module having a housing on which the lithium secondary battery is mounted.

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