KR20230063193A - Secondary battery containing spark block member - Google Patents

Abstract

The present invention relates to a secondary battery having a spark blocking means, the secondary battery comprising: an electrode assembly; And a cell case into which the electrode assembly is inserted, wherein the cell case has a structure in which a spark blocking member is disposed inside the case junction, and the spark blocking member is bent in a zigzag shape to fill the inside of the case where the junction is located. When an event in which a cell case is opened due to a short circuit of the battery, overcharging, overcurrent, etc. occurs, sparks generated in the secondary battery are prevented from being exposed to the outside.

Description

Secondary battery having a spark blocking member {Secondary battery containing spark block member}

The present invention relates to a secondary battery having a spark blocking means, and more specifically, to a secondary battery that increases safety by reducing external exposure of sparks generated in the secondary battery when an event in which a cell case is opened due to ignition or explosion of the secondary battery occurs. it's about

Recently, interest in energy storage technology is increasing. Efforts for research and development of electrochemical devices are becoming more and more specific as the fields of application are expanded to mobile phones, camcorders, notebook PCs, and even the energy of electric vehicles. Electrochemical devices are the field that is attracting the most attention in this respect, and among them, the development of secondary batteries capable of charging and discharging has become the focus of attention. and battery design research and development.

Recently, secondary batteries have been widely used in IT products, automobile fields, energy storage fields, etc., and are attracting attention as an energy source in the spotlight. In the field of IT products, secondary batteries can be used continuously for a long time, and miniaturization and light weight are required. In the field of automobiles, high power, durability, and stability to eliminate the risk of explosion are required. The energy storage field is to store surplus power produced by wind power, solar power, etc., and as it is used in a fixed type, secondary batteries under more relaxed conditions can be applied. In particular, lithium secondary batteries have been researched and developed since the early 1970s, and in 1990, lithium ion batteries using carbon as an anode instead of lithium metal were developed and put into practical use. As a characteristic, it has the highest sales elongation rate among secondary batteries and is 30 to 40% lighter than nickel-hydrogen batteries, enabling weight reduction. In addition, the lithium secondary battery has the highest unit cell voltage (3.0 to 3.7V) and excellent energy density among existing secondary batteries, so it may have characteristics optimized for mobile devices.

However, a large current flows in the secondary battery due to a short circuit, or a chemical reaction is initiated due to overcharging or overcurrent to generate gas and heat, which may lead to swelling and explosion of the secondary battery.

When the swelling or explosion of the secondary battery as described above occurs, the secondary battery sealing part is opened due to the combustible gas and carbon dioxide generated from the electrode active material of the secondary battery, the electrolyte, and the spark generated together increases the probability of flame occurrence.

In particular, when secondary batteries are used as a power source for electric vehicles, medium or large-sized battery modules or battery packs made up of multiple secondary batteries have the advantage of high output compared to other batteries, but have a high risk of explosion, so it is difficult to solve the safety problem. very important.

In particular, when a fire occurs in a modular secondary battery, the flame is easily propagated to the surrounding secondary battery and the outside of the module, and eventually the fire spreads to the entire electric vehicle. Therefore, it is very important to block the propagation of the flame to the outside of the secondary battery.

The present invention has been devised to solve the above problems, and an object of the present invention is to reduce external exposure of sparks generated in a secondary battery when an event in which a cell case is opened due to a short circuit, overcharge, overcurrent, etc. It is to provide a secondary battery.

In order to solve the above problems,

In one embodiment, the present invention

electrode assembly; and

Including a cell case into which the electrode assembly is inserted,

The cell case has a spark blocking member disposed inside the case joint,

The spark blocking member provides a secondary battery having a structure bent in a zigzag shape so as to face the inner surface of the cell case provided with the joint.

In this case, the spark blocking member may include a mesh layer made of one or more of metal fibers, metal wires, and carbon fibers.

In addition, the spark blocking member is provided with a coating layer containing a fire extinguishing agent on the surface; It may have a structure in which a fire extinguishing sheet containing a fire extinguishing agent and/or a heat insulating sheet are inserted into the inner surface bent in a zigzag shape.

In addition, the junction part of the cell case may include a weak part having lower bonding strength than the other side of the junction part at one side of the junction part.

In addition, the weak part of the joining portion may be joined with a sealing member, and the other joining parts may be joined by thermal fusion. Accordingly, the weak part may be alternately formed with a thermally fused portion and a joined portion with the sealing member.

In addition, the spark blocking member may have a structure in which a zigzag bending structure is unfolded when an end portion is coupled to the case joint portion and the joint portion is opened.

In addition, the spark blocking member may have a structure in which both ends are disposed on the upper and lower surfaces of the electrode assembly in the direction in which the electrodes are stacked so that when the junction is opened, the opening is unfolded in a bag shape coupled to the inside of the case.

In addition, the cell case may be a pouch type case.

Furthermore, the present invention, in one embodiment,

Provided is a secondary battery module including the secondary battery of the present invention described above.

The secondary battery equipped with the spark blocking means according to the present invention is disposed in a structure in which the mesh layer is bent in a zigzag shape inside the junction of the cell case, and an event in which the cell case is opened due to a short circuit, overcharging, or overcurrent of the secondary battery may occur In this case, by configuring the bending structure of the mesh layer to unfold, an effect of preventing sparks generated in the secondary battery from being exposed to the outside is provided.

Furthermore, the secondary battery provides an effect of reducing the risk of flame propagation and explosion in the battery module by preventing a flame from being generated due to a spark of a combustible gas generated in the battery.

1 is a cross-sectional view of a secondary battery according to an embodiment of the present invention.
2 is a cross-sectional view showing a secondary battery according to the present invention in which an event occurs.
3 is a side perspective view of a secondary battery according to the present invention in which an event occurs.
4 is a cross-sectional view showing the structure of a conventional secondary battery in which a metal mesh layer is introduced into a cell case.
5 is a cross-sectional view of a secondary battery having a spark blocking member in which fire extinguishing sheets are stacked.

Since the present invention can have various changes and various embodiments, specific embodiments will be described in detail in the detailed description.

However, this is not intended to limit the present invention to specific embodiments, and should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention.

In the present invention, the term "comprises" or "has" is intended to designate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, but one or more other features It should be understood that the presence or addition of numbers, steps, operations, components, parts, or combinations thereof is not precluded.

Further, in the present invention, when a part such as a layer, film, region, plate, etc. is described as being “on” another part, this includes not only the case where it is “directly on” the other part, but also the case where another part is present in the middle thereof. . Conversely, when a part such as a layer, film, region, plate, or the like is described as being “under” another part, this includes not only being “directly under” the other part, but also the case where there is another part in the middle. In addition, in the present application, being disposed "on" may include the case of being disposed not only on the upper part but also on the lower part.

Hereinafter, the present invention will be described in more detail.

secondary battery

In one embodiment, the present invention

electrode assembly; and

Including a cell case into which the electrode assembly is inserted,

The cell case has a spark blocking member disposed inside the case joint,

The spark blocking member provides a secondary battery having a structure bent in a zigzag shape so as to face the inner surface of the cell case provided with the joint.

1 is a cross-sectional view of a secondary battery according to an embodiment of the present invention.

The secondary battery 1 according to the present invention may be composed of a lithium secondary battery or a nickel-hydrogen secondary battery capable of charging and discharging. As a secondary battery using an alkaline aqueous solution, it has a large capacity per unit volume, so it can be used not only as an energy source for electric vehicles (EVs) and hybrid vehicles (HEVs), but also for various fields such as energy storage. In addition, the lithium secondary battery uses a metal oxide such as LiCoO2 as a cathode active material and a carbon material as an anode active material, and the electrode assembly 10 in which a porous polymer separator 11 is placed between the anode 12 and the cathode 13 is inserted into the cell case 20, and a non-aqueous electrolyte containing a lithium salt such as LiPF6 is introduced into the cell case. During charging, lithium ions from the positive electrode active material are released and inserted into the carbon layer of the negative electrode 12, and during discharging, lithium ions from the carbon layer are released and inserted into the positive electrode active material. 13) serves as a medium for lithium ions to move between them.

The electrode assembly is composed of a positive electrode 13, a negative electrode 12, and a separator 11, and those commonly used in manufacturing lithium ion secondary batteries may all be used.

In addition, the secondary battery 1 may be formed of a pouch-type secondary battery or a prismatic secondary battery including an electrode assembly 10 and a pouch-type case that surrounds and seals the electrode assembly 10 .

On the other hand, the cell case 20 may be used by insulating the surface of a thin metal plate such as an aluminum thin plate, and the insulation treatment is a heat-sealing layer of a modified polypropylene, for example, CPP (Casted Polypropylene), which is a polymer resin. It is applied to form, and a resin material such as nylon or polyethylene terephthalate (PET) may be formed on the outer surface thereof. This structure has been described as an embodiment of a lithium secondary battery, and in the present invention, this structure can be appropriately changed, selected, and applied by those skilled in the art according to the shape and type of the battery.

When manufacturing a secondary battery, a degassing process generally involves inserting the electrode assembly 10 into the cell case 20, sealing the cell case 20, injecting electrolyte, and discharging gas generated through the initial charge/discharge process. goes through When the cell case 20 is sealed, the upper case 21 and the lower case 22 may be fused using heat or bonded using a sealing member to form the junction 23 . When thermally fused and/or bonded to a sealing member, the entire contacting portion of the upper case 21 and the lower case 22 is fused and/or bonded to completely block the flow of air inside and outside the cell case 20 . For example, in a pouch-type secondary battery, when the upper case 21 and the lower case 22 are completely separated, four surfaces of the upper case and the lower case in contact are thermally fused and/or bonded with a sealing member; When one surface of the upper case 21 and the lower case 22 are integrally formed, the three surfaces may be thermally fused and/or bonded to a sealing member.

In general, since the junction 23 connecting the battery case 20 with a sealing member is relatively weak, when swelling occurs due to a short circuit, overcurrent, or overcharging of the battery, the junction 23 is opened and trapped in the battery gas is released Specifically, the cell case of the secondary battery may include a weak portion (not shown) having a relatively low bonding strength compared to other joints heat-sealed to one side of the joint portion 23 due to a sealing member. Excessive pressure within the battery due to gas generated within the battery may be prevented, and the cell case 20 may be opened in a desired direction when an event occurs.

The weak part adjusts the joint strength to be weaker than other joint parts; The other joints may be joined by thermal fusion and the weak parts may be joined using a sealing member. When the weak parts are joined with a sealing member and the other joints are formed by welding, there is an advantage in that the weak parts can be formed more easily. . In addition, the weak part may include a structure in which a portion of the thermally fused joint portion and a portion of the joint portion joined by the sealing member are alternately formed.

2 is a cross-sectional view showing a secondary battery according to the present invention in which an event occurs, and FIG. 3 is a side perspective view of the secondary battery according to the present invention in which an event occurs.

Specifically, the secondary battery generates flammable gas due to a short circuit, overcharge, or overcurrent inside, and when the increased pressure inside the cell case 20 exceeds a certain level, the junction 23 is opened. The spark blocking member 30 expands to the outside of the secondary battery while pushing the zigzag structure of the spark blocking member 30 bent more than twice, specifically, more than three times or three to five times. Accordingly, the increased pressure inside the secondary battery 1 is lowered.

As one example, as shown in FIG. 1 , the spark blocking member 30 may have a structure in which a zigzag bending structure is unfolded when one end is coupled to a case junction and the junction is opened.

As another example, the spark blocking member 30 has both ends disposed on the upper and lower surfaces of the electrode assembly in the direction in which the electrodes are stacked as shown in FIG. It may have a structure that unfolds into a shape.

Since the gas discharged from the secondary battery contains a large amount of combustible components, it is highly likely to explode when a temperature higher than the ignition point occurs. There is a high possibility that a spark will occur due to a short circuit inside the secondary battery where the junction is opened due to an event in which the cell case is opened due to a short circuit, overcharge, or overcurrent. On contact, a temperature above the ignition point is formed and explodes.

The spark blocking member 30 of the present invention covers the outer surface of the cell case by completely unfolding the bending structure to the outside of the cell case when an event of opening the cell case of the secondary battery occurs; Alternatively, since the opening is spread in a bag shape combined with the inside of the case, it is possible to prevent direct contact between the external air (specifically, oxygen) and the spark of the secondary battery. As shown in FIG. Compared to the introduced case, the possibility of explosion can be significantly lowered. In addition, since the spark blocking member is formed in a zigzag-shaped bending structure, when an event occurs, it is possible to prevent sparks from coming into contact with external air, similar to the case where the spark blocking member is formed in multiple layers.

Meanwhile, the spark blocking member 30 is preferably made of an incombustible material, and may include a mesh layer made of one or more of metal fibers, metal wires, and carbon fibers.

Specifically, the spark blocking member 30 may include copper, aluminum, cast iron, Monel (Ni+Cu), stainless steel, etc. alone or in combination with metal fibers or metal wires, or carbon fibers. .

As an example, the spark blocking member 30 may be a mesh layer made of stainless steel fibers or a mesh layer made of carbon fibers.

Furthermore, the spark blocking member 30 may include an extinguishing agent. Specifically, the spark blocking member 30 is provided with a coating layer containing a fire extinguishing agent on the surface; It may have a structure in which a fire extinguishing sheet containing an extinguishing agent is inserted into an inner surface bent in a zigzag shape.

As one example, the spark blocking member 30 may include a coating layer 41 containing a fire extinguishing agent as shown in FIG. 5, and the coating layer constitutes a spark blocking member in a coating composition containing a fire extinguishing agent. It may be formed by immersing the mesh layer to be immersed, or by applying the coating composition to the surface of the mesh layer.

At this time, the coating composition may have a configuration including a fire extinguishing agent and a polymer resin, wherein the polymer resin is flame retardant polyvinylidene fluoride-hexafluoropropylene, polyvinylidene fluoride-trichloroethylene, polymethyl Methacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinyl acetate, polyethylene-vinyl acetate copolymer, polyethylene oxide, cellulose acetate, cellulose acetate butylate, cellulose acetate propionate, cyanoethyl pullulan, cyanide Any one selected from the group consisting of noethyl polyvinyl alcohol, cyanoethyl cellulose, cyanoethyl sucrose, pullulan, carboxyl methyl cellulose, acrylonitrile-styrene-butadiene copolymer, polyimide, and mixtures thereof can be used. However, it is not limited thereto.

As another example, the spark blocking member 30 may have a structure in which a fire extinguishing sheet containing an extinguishing agent is inserted into an inner surface bent in a zigzag shape, and the fire extinguishing sheet is inside the spark blocking member 30. One or more can be inserted into That is, one sheet of fire extinguishing sheet may be inserted into the bent inner side of the spark blocking member 30; A plurality of fire extinguishing sheets may be included by inserting one fire extinguishing sheet between the bent inner sides.

Here, the fire extinguishing sheet may have a form in which the fire extinguishing agent is uniformly dispersed in a polymer resin exhibiting flame retardancy. Specifically, the fire extinguishing sheet is polyvinylidene fluoride-hexafluoropropylene, polyvinylidene fluoride-trichloroethylene, polymethyl methacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinyl Acetate, Polyethylene-Vinyl Acetate Copolymer, Polyethylene Oxide, Cellulose Acetate, Cellulose Acetate Butyrate, Cellulose Acetate Propionate, Cyanoethyl Pullulan, Cyanoethyl Polyvinyl Alcohol, Cyanoethyl Cellulose, Cyanoethyl Sucrose, Pullulan The fire extinguishing agent may be uniformly dispersed in a polymer resin including any one selected from the group consisting of ran, carboxyl methyl cellulose, acrylonitrile-styrene-butadiene copolymer, polyimide, and mixtures thereof.

In addition, the fire extinguishing agent included in the coating composition and the fire extinguishing sheet may be used without particular limitation as long as it is used as a fire extinguishing agent for a secondary battery in the art. Specifically, the fire extinguishing agent is preferably a material with a small volume change according to temperature change. Non-limiting examples of such materials include nitrogen gas, alkylene glycols such as ethylene glycol or propylene glycol, 1,3-propanediol, ferrocene aldehydes or ketone compounds, or ferrocene carboxylic acid compounds and derivatives thereof, or ferrocene alcohols, phenols or ethers. ferrocene derivatives such as compounds, or ferrocene hydrocarbon compounds, or nitrogen-containing ferrocene compounds, or sulfur-containing or phosphorus-containing ferrocene compounds, or silicon-containing ferrocene compounds, or heterocyclic ferrocene compounds; Capric acid, dodecanoic acid, tetradecanoic acid, hexadecanoic acid, heptadecanoic acid, octadecanoic acid , eicosanoic acid, docosanoic acid, hexacosanoic acid, hentriacontylic acid, dotriacontanoic acid, crotonic acid, oleic acid, heptadecenoic acid , hexadecenoic acid, hexadienic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, pimelic acid acid), suberic acid, sebacic acid, brassylic acid, hexadecanedioic acid, cis-crotonic acid, trans-crotonic acid (trans-crotonic acid), 2-hydroxypropionic acid, 2-hydroxybutanedioic acid, 2,3-dihydroxybutanedioic acid, 2 -hydroxy-1,2,3-propanetricarboxylic acid (2-hydroxy-1,2,3-propanetricarboxylic acid), 3-phenyl-2-propenoic acid (3-phenyl-2-propenoic acid), 2- Organic acid compounds such as 2-hydroxybenzoic acid, 3,4,5-trihydroxy benzoic acid, benzoic acid or methylguanidoacetic acid ; Dodecafluoro-2-methylpentan-3-one, decafluoro-2-methylbutan-3-one, 1,1,1,3,3,4,4,5,5,5-decafluoro Pentan-2-one, 1,1,1,2,2,4,4,5,5,5-decafluoropentan-3-one, 1,1,1,4,4,5,5,5 -Octafluoro-3-bis(trifluoromethyl)-pentan-2-one, dodecafluoro-4-methylpentan-2-one, dodecafluoro-3-methylpentan-2-one, dodecane It may include one or a mixture of two or more selected from the group consisting of compounds such as capuoro-3,3-(dimethyl)butan-2-one and dodecafluorohexan-3-one, but are limited thereto It is not.

In addition, the spark blocking means 30 may have a structure in which an insulating sheet is inserted into an inner surface bent in a zigzag shape.

The heat insulating sheet is for preventing heat from a secondary battery in which an event in which a cell case is opened is not transmitted to the outside, and is made of polyester, polyamide, polyether sulfone, polyetherimide, polyimide, polyamideimide, and polyamide siloxane. , polyurethane, polystyrene, polycarbonate, polymethyl methacrylate, and the like. In addition, the heat insulation sheet may also play a role of enabling the thermal stability and performance of the battery to be maintained by absorbing heat generated during charging and discharging of the secondary battery in which no event has occurred.

By stacking the fire extinguishing sheet on the inside of the spark blocking means 30, it is possible to provide an effect of preventing the secondary battery from exploding or being excessively heated when an event in which the cell case of the secondary battery 1 is opened occurs. .

Meanwhile, the spark blocking member 30 may be disposed only at a portion where a weak portion is formed among the joint portions 23 of the cell case 20 . Since the cell case is opened through the weak portion when an event of opening the cell case of the secondary battery 1 occurs, when the spark blocking member 30 is formed only in the portion where the weak portion is formed, the manufacturing cost of the secondary battery can be reduced. may be more efficient.

Secondary battery module

In addition, in one embodiment of the present invention,

Provided is a secondary battery module including the secondary battery according to the present invention described above.

The secondary battery module according to the present invention includes the above-described secondary battery of the present invention, and prevents sparks generated in the secondary battery from being exposed to the outside even when an event in which a cell case is opened due to a short circuit, overcharging, or overcurrent of the battery occurs. Since this can be prevented, ignition and/or explosion of the secondary battery can be prevented. Therefore, since the secondary battery module according to the present invention has excellent safety when exposed to high temperatures, it can be used as a power source for medium or large-sized devices requiring high temperature stability, long cycle characteristics, and high rate characteristics. Specific examples of these medium-large devices include a power tool powered by an omniscient motor and moving; electric vehicles, including electric vehicles (EVs), hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and the like; electric two-wheeled vehicles including electric bicycles (E-bikes) and electric scooters (Escooters); electric golf carts; A power storage system may be mentioned, and more specifically, a hybrid electric vehicle (HEV) may be cited, but is not limited thereto.

Although the above has been described with reference to preferred embodiments of the present invention, those skilled in the art or those having ordinary knowledge in the art do not deviate from the spirit and technical scope of the present invention described in the claims to be described later. It will be understood that various modifications and changes can be made to the present invention within the scope.

Therefore, the technical scope of the present invention is not limited to the contents described in the detailed description of the specification, but should be defined by the claims.

1: secondary battery 10: electrode assembly
11: separator 12: negative electrode 13: positive electrode
20: cell case
21: upper case 22: lower case 23: junction
30: spark blocking member
31: fire extinguishing agent coating layer

Claims (12)

electrode assembly; and
Including a cell case into which the electrode assembly is inserted,
The cell case has a spark blocking member disposed inside the case joint,
The spark blocking member has a structure bent in a zigzag shape to face the inner surface of the cell case provided with the junction.
According to claim 1,
A secondary battery comprising a spark blocking member comprising a mesh layer composed of at least one of metal fibers, metal wires, and carbon fibers.
According to claim 1,
A secondary battery having a coating layer containing an extinguishing agent on the surface of the spark blocking member.
According to claim 1,
The spark blocking member is a secondary battery having a structure in which an extinguishing sheet containing an extinguishing agent is inserted into an inner surface bent in a zigzag shape.
According to claim 1,
The spark blocking member is a secondary battery having a structure in which an insulating sheet is inserted into an inner surface bent in a zigzag shape.
According to claim 1,
The secondary battery comprising: a weak portion at one side of the joint where the joint has a lower joint strength than the other side of the joint.
According to claim 6,
A secondary battery wherein weak parts of the junction are joined with a sealing member, and the remaining junctions are joined by thermal fusion.
According to claim 6,
A secondary battery in which a weak part is alternately formed with a heat-sealed part and a part joined by a sealing member.
According to claim 1,
The spark blocking member is a secondary battery having a structure in which a zigzag bending structure is unfolded when an end is coupled to a case junction and the junction is opened.
According to claim 1,
The spark blocking member has a structure in which both ends are disposed on the upper and lower surfaces of the electrode assembly in the direction in which the electrodes are stacked so that when the junction is opened, the opening is unfolded in a bag shape coupled to the inside of the case.
According to claim 1,
The cell case is a pouch type secondary battery.
A secondary battery module comprising the secondary battery according to claim 1.

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