KR20130024596A - Secondary battery with improved safety - Google Patents

Abstract

PURPOSE: A pouch type secondary battery is provided to improve the performance of a battery and to improve the stability of a battery by comprising a flame retardant inside a pouch. CONSTITUTION: A pouch type secondary battery comprises an electrode assembly(16), a pouch type exterior material(10), and an additive(102) containing separated part(104). The additive is a flame retardant or a foaming agent. The separated part is formed of a polymer material which can be melted at 70°C or higher. The polymer material is polyethylene or polypropylene. The separated part is formed on the inner surface of the pouch type exterior. The pouch type exterior comprises a main inlet which is connected to the separated part.

Description

Secondary battery with improved safety

The present invention relates to a secondary battery comprising a flame retardant.

As technology development and demand for mobile devices are increasing, the demand for batteries as energy sources is rapidly increasing, and accordingly, a lot of researches on batteries capable of meeting various demands have been conducted.

Representatively, there is a high demand for square and pouch type secondary batteries that can be applied to products such as mobile phones with a thin thickness in terms of shape of batteries, and high energy density, discharge voltage, and output stability in terms of materials. There is a high demand for lithium secondary batteries such as lithium ion batteries, lithium ion polymer batteries and the like.

On the other hand, nickel-hydrogen secondary batteries have been widely used as unit cells (battery cells) of medium and large battery packs. Recently, lithium secondary batteries that provide high output / capacity as in small battery packs have been studied.

Lithium secondary batteries are a strong candidate as unit cells of medium and large battery packs due to various advantages as described above. However, lithium secondary batteries using a flammable non-aqueous electrolyte are generally dendrite grown by lithium ions at a negative electrode when overcharged. This causes a short, which causes the internal temperature of the battery to rise and a flammable gas due to the decomposition reaction of the electrolyte, a flammable gas due to the reaction of the electrolyte and the electrode, and an explosion due to the generation of oxygen due to the decomposition of the anode. I have a problem.

In addition, the polyethylene used as a separator between the positive electrode and the negative electrode starts to melt when the temperature of the battery rises to 120 to 130 ° C. As a result of the shrinkage of the separator, a short occurs due to contact between the negative electrode and the positive electrode at the corner. Therefore, a large amount of current flow generates heat to increase the temperature and eventually undergoes a process of ignition of the battery.

In order to solve this problem, a method of pressurizing and charging the electrolyte with carbon dioxide to expel the electrolyte with carbon dioxide easily when the temperature of the battery rises abnormally has been sought. However, the electrolyte may be sucked into the inner pores of the separator or inside the electrode. In this case, the gas pressure alone is not easily released to the outside, so the risk of battery ignition due to decomposition of the electrolyte is still not solved.

In the medium and large battery packs in which a plurality of unit cells are electrically connected for the purpose of high output capacity, such a fire is a very serious risk factor that impairs safety. Therefore, the need for a secondary battery capable of preventing the above problems has emerged.

The present invention is a pouch type secondary battery having improved safety by including a flame retardant inside the pouch, by varying the location and method of containing the flame retardant, the flame retardant does not affect the operation and performance of the normal battery, can be applied only in an emergency It is an object of the present invention to provide a secondary battery capable of expressing both performance improvement and safety improvement of the battery.

The present invention to solve the above problems the electrode assembly; Pouch type exterior materials; It provides a pouch-type secondary battery comprising a; containing an isolation portion containing an additive.

In this case, the additive may be any one of a flame retardant and a blowing agent.

In addition, the isolation portion is characterized in that formed of a polymer material that is melted at a temperature of 70 ℃ or more.

The polymer material may be any one of polyethylene and polypropylene.

In addition, the isolator is characterized in that formed on the inner surface of the pouch-shaped packaging material.

In this case, the separator may be to coat an additive on the inner surface of the pouch-type exterior material and then to coat the isolation member thereon.

In addition, the isolation unit may be a separate implant.

In addition, the pouch-type packaging material may further include an additive inlet connected to the isolation part.

In the pouch type secondary battery according to the present invention, the additive may be a flame retardant.

Further, the flame retardant may be one or more selected from the group consisting of a halogen flame retardant, a phosphorus flame retardant, a nitrogen flame retardant, and an inorganic compound flame retardant.

In addition, the halogen flame retardant is tribromo phenoxyethane, tetrabromobisphenol-A (TBBA), octabromo diphenyl ether (OBDPE), brominated epoxy, brominated polycarbonate oligomo, chlorinated paraffin, chlorinated polyethylene and alicyclic It may be one or more selected from the group consisting of chlorine-based flame retardants.

The phosphorus flame retardant is ammonium phosphate, phosphine oxide, phosphine oxide diols, phosphites, phosphonates, triaryl phosphate, alkyl It may be one or more selected from the group consisting of diaryl phosphate (alkyldiaryl phosphate), trialkyl phosphate (trialkyl phosphate) and resorcinol bisdiphenyl phosphate (RDP).

In addition, the nitrogen-based flame retardant may be one or more selected from the group consisting of melamine, melamine phosphate and melamine cyanurate.

In addition, the inorganic compound flame retardant may be one or more selected from the group consisting of aluminum hydroxide, magnesium hydroxide, barium hydroxide, antimony oxide, tin hydroxide, tin oxide, molybdenum oxide, zirconium compound, borate and calcium salt.

The present invention further provides a battery module comprising at least one pouch type secondary battery, and further provides a battery pack including the battery module.

In this case, the battery pack includes a power tool; Electric vehicles selected from the group consisting of electric vehicles (EVs), hybrid electric vehicles (HEVs), and plug-in hybrid electric vehicles (PHEVs); E-bike; E-scooter; Electric golf carts; Electric trucks; And it may be used as one or more power sources selected from the group consisting of electric commercial vehicles.

The present invention is a pouch type secondary battery having improved safety by including a flame retardant inside the pouch, the flame retardant does not affect the operation and performance of the battery in normal, it is designed to be applied only in an emergency to improve both the performance and safety of the battery Provides an improvement effect.

1 is an exploded perspective view of a conventional pouch type secondary battery.
2 is a cross-sectional view of an embodiment of a pouch type secondary battery according to the present invention.
3 and 4 are cross-sectional views of another embodiment of the pouch type secondary battery according to the present invention.

The present invention relates to a secondary battery containing an additive such as a flame retardant,

An electrode assembly; Pouch type exterior materials; It provides a pouch-type secondary battery comprising a; comprising an isolation comprising the additive.

In general, the additive such as the flame retardant is inside the pouch-type secondary battery in order to absorb gas or lower the temperature and prevent ignition of the battery when a dangerous situation such as heat generation, ignition, gas generation due to abnormal behavior of the battery occurs. Include.

However, when the additive such as the flame retardant is included in the pouch, there is a problem in that it is mixed with the electrolyte or the like and penetrates into the electrode assembly to reduce the performance of the battery and shorten the lifespan. In addition, in order to solve such a problem, when the additive such as the flame retardant is inserted into a separate implant, and interposed inside the pouch, the additive is difficult to act quickly in an emergency due to an abnormal behavior of a battery, thereby rapidly evolving the occurrence of a dangerous situation. It can't be done and it becomes a problem.

Therefore, the present invention interposes the additive such as the flame retardant at a high temperature and is separated from the normal operation of the battery, but does not affect the operation of the battery, but in an emergency situation such as heat generation or fire, the isolation part is released such as a flame retardant. Additives can be applied directly inside the cell, helping to prevent the occurrence of dangerous situations quickly.

To this end, the isolation portion of the present invention is to be formed of a polymer material that is melted at a temperature of 70 ℃ or more.

Accordingly, when the temperature inside the secondary battery is 70 ° C. or higher, the polymer forming the isolation portion is melted, and the isolation of the additive contained in the secondary is released, so that the secondary battery can be directly applied to the inside of the pouch type secondary battery.

When the temperature inside the secondary battery is higher than the above temperature, a sudden increase in temperature may occur. Therefore, additives such as a flame retardant, a gas absorbent, and a coolant are applied at a temperature of about 70 ° C. to prevent fire or explosion. To prevent it.

The type of polymer to be melted at a temperature of 70 ° C. or higher is not particularly limited and may be freely selected by those skilled in the art. Preferably, the melting temperature of the polymer is 250 ° C., more preferably 180 ° C. or lower. If the melting temperature of the polymer exceeds 200 ℃ because the emergency isolation of the battery is quickly released because the additive is difficult to apply into the battery. If the polymer having a melting point within the temperature range as described above is not particularly limited and may be applied in various ways, specific examples may use a polymer such as polyethylene or polypropylene.

Meanwhile, the additive included in the secondary battery of the present invention may be variously configured according to the required purpose, and two or more may be mixed and included in the isolation unit.

In one embodiment of the present invention may be to include a flame retardant of the additive.

The flame retardant serves to prevent a large fire from occurring by preventing the secondary battery from burning well even when the temperature of the secondary battery rises sharply.

The flame retardant which can be used by this invention is not specifically limited, A well-known material can be used.

For example, the flame retardant may be one or more selected from the group consisting of halogen-based flame retardants, phosphorus-based flame retardants, nitrogen-based flame retardants and inorganic compound flame retardants, but is not limited thereto.

More specifically, the halogen-based flame retardant is tribromo phenoxyethane, tetrabromobisphenol-A (TBBA), octabromo diphenyl ether (OBDPE), brominated epoxy, brominated polycarbonate oligomo, chlorinated paraffin, chlorinated polyethylene And alicyclic chlorine-based flame retardant and the like can be used one or more selected from the group consisting of,

The phosphorus-based flame retardants include ammonium phosphate, phosphine oxide, phosphine oxide diols, phosphites, phosphonates, triaryl phosphate, One or more selected from the group consisting of alkyldiaryl phosphate, trialkyl phosphate, resorcinol bisdiphenyl phosphate (RDP), etc. may be used,

The nitrogen-based flame retardant may be used at least one selected from the group consisting of melamine, melamine phosphate and melamine cyanurate,

The inorganic compound flame retardant may be one or more selected from the group consisting of aluminum hydroxide, magnesium hydroxide, barium hydroxide, antimony oxide, tin hydroxide, tin oxide, molybdenum oxide, zirconium compound, borate and calcium salt, but is not limited thereto. It doesn't happen.

Among the flame retardants listed above, an inorganic compound flame retardant is preferably used. The inorganic compound flame retardant is decomposed by heat, releasing incombustible gases such as water, carbon dioxide, sulfur dioxide, and hydrogen chloride and causing an endothermic reaction, thereby lowering the temperature of the battery. It is excellent because it dilutes the flammable gas to prevent the access of oxygen and reduces the production of cooling and pyrolysis products by the endothermic reaction, so that the flame retardant effect is also excellent.

In the present invention, if the additive such as a flame retardant is contained in the pouch by isolating the specific polymer material, the isolation form, the location of the interposition in the pouch, etc. are not particularly limited, and those skilled in the art can easily modify it according to the shape and size of the battery. can do.

Hereinafter, various embodiments of the present invention will be described with reference to the drawings.

The pouch-type secondary battery according to the present invention can form an isolation part including an additive such as the flame retardant agent on the inner surface of the pouch-type sheathing material so that the implementation of a compact secondary battery and an additive agent in an emergency can be effectively applied.

2 is a cross-sectional view of a pouch-type secondary battery according to an embodiment of the present invention, which is a secondary battery in which an isolation part 100 including an additive or the like is directly formed on the surface of the pouch-type exterior material 10.

That is, in the pouch type secondary battery including the electrode assembly 16 and the electrode leads 12 and 14 as shown in FIG. 2, an additive 102 such as a flame retardant is first applied to an inner surface of the pouch type exterior material to form a coating film. After that, by coating and drying the polymer material for forming the isolation portion thereon, additives such as the flame retardant may be separated from the electrode assembly, the electrolyte, and the like.

The method of applying the additive such as the flame retardant to the inner surface of the pouch-type exterior material is not particularly limited, for example, by dispersing the additive such as the flame retardant in water or an organic solvent and applying to a desired portion to form a coating film and drying As the coating method, conventionally known coating methods such as an immersion coating method, a roller coating method, a spray coating method, and a doctor blade coating method can be used without particular limitation.

After forming and drying the coating film of the additive, by applying a polymer for forming the isolation portion on the surface of the additive and dried to form a separator so that the additive is not eluted by the electrolyte or the like.

As described above, it is preferable to use a polymer that is melted at a temperature of 70 ° C. or higher as described above, and specific examples thereof may include a polymer such as polyethylene or polypropylene, and the method of forming a coating film may include forming the additive coating film. However, the present invention is not limited thereto.

Meanwhile, the isolation part including the additive such as the flame retardant may be formed as a separate implant and may be interposed in the pouch type secondary battery.

FIG. 3 injects an additive 112 such as a flame retardant into a separate implant 114 so that an additive such as a flame retardant may be contained separately from an electrode assembly and an electrolyte.

In this case, the implant is formed of a polymer that is melted at a temperature of 70 ° C. or higher. As described above, the type is not particularly limited and may be freely selected by those skilled in the art, but specific examples thereof include a polymer such as polyethylene or polypropylene. Can be.

As in the case of Figure 3, when manufacturing a separate implant containing an additive and including it inside the pouch-type secondary battery, the manufacturing process of the battery can be easily and simplified, there is an advantage that the manufacturing time can be saved .

In another embodiment of the present invention, as shown in FIG. 4, the additive inlet 126 may be further formed in the pouch-type exterior material.

In the above embodiment, to form the isolation portion 124 having a space that may include an additive such as a flame retardant on the inner surface of the pouch-type packaging 10.

After storing and sealing the electrode assembly using the pouch-type exterior material 10, an additive 122 such as a flame retardant may be injected into the isolation part 124 through the additive injection hole 126. When the injection is all finished, the additive inlet is sealed. Such a method is advantageous when an additive such as a flame retardant is liquid, and has an advantage of shortening the manufacturing time of a battery.

The separator is also formed of a polymer that is melted at a temperature of 70 ℃ or more.

The present invention may further provide a battery module or a battery pack including a plurality of pouch type secondary batteries as described above. The battery module or the battery pack may be used as a power source for a small device, and the battery safety is greatly improved, and it is preferable to be used as a power source for a medium and large device.

The medium to large device includes a power tool; Electric vehicles such as Electric Vehicle (EV), Hybrid Electric Vehicle (HEV) and Plug-in Hybrid Electric Vehicle (PHEV); Electric two-wheeled vehicles such as E-bikes or E-scooters; Electric golf carts; Electric trucks; And an electric commercial vehicle, but are not limited thereto.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the scope of the present invention is not limited by the following Examples.

Example

Aluminum hydroxide was dispersed in the organic solvent N-methyl pyrrolidone as a flame retardant to prepare a composition containing the flame retardant.

After applying the flame-retardant-containing composition to the surface of the pouch-shaped packaging material by the roller coating method, the temperature is raised to 50 ℃ to dry the solvent, and then coated and dried polyethylene polymer on the same method, using the pouch-type packaging material To prepare a secondary battery.

Comparative example

Secondary battery as in Example 1, except that the flame retardant and blowing agent are not included.

Experimental Example

(One) Hot box  Experiment

After increasing the temperature of the secondary battery of Examples and Comparative Examples from room temperature to 160 ℃ at a rate of 5 ℃ / min, and maintained for 1 hour.

Then, the temperature of each secondary battery was measured and shown in Table 1 below.

(2) Cycling stability evaluation at high temperature

Cycling stability at 100 ° C of secondary batteries of Examples and Comparative Examples was evaluated, and the results are shown in Table 1.

160 ℃, after 1 hour (℃) 5 cycles
Volume Decrease After Elapsed 10 cycles
Volume Decrease After Elapsed 20 cycles
Volume Decrease After Elapsed Secondary battery Example 90 0.4% 3% 7% Comparative example 150 2 % 10% 20%

As shown in Table 1, even if left for a long time at a high temperature in the case of the Example was confirmed that the temperature of the surface is very low compared to the comparative example, it was confirmed that also excellent cycling stability at high temperature.

Therefore, it was confirmed that the safety of the secondary battery including the additive such as the flame retardant of the present invention was improved.

10: pouch type exterior material,
12, 14: electrode lead,
16: electrode assembly,
102, 112, 122: additives,
104, 114, 124: isolation,
126: additive inlet

Claims (17)

Electrode assembly; Pouch type exterior materials; Pouch-type secondary battery comprising; an isolation unit comprising an additive. The method of claim 1,
The additive is a pouch type secondary battery, characterized in that any one of the flame retardant, foaming agent. The method of claim 1,
The isolation part pouch type secondary battery, characterized in that formed of a polymer material that is melted at a temperature of 70 ℃ or more. The method of claim 3, wherein
The polymer material is a pouch type secondary battery, characterized in that any one of polyethylene, polypropylene. The method of claim 1,
The isolation unit is a pouch type secondary battery, characterized in that formed on the inner surface of the pouch-type exterior material. The method of claim 5, wherein
The isolation part is a pouch-type exterior material, characterized in that the coating the insulating member thereon after coating the additive on the inner surface of the pouch-type exterior material. The method of claim 1,
The isolation part pouch type secondary battery, characterized in that the separate implant. The method of claim 1,
Wherein the pouch-type sheathing material further comprises an additive injection port connected to the isolation portion. The method of claim 2,
The additive is a pouch type secondary battery, characterized in that the flame retardant. The method of claim 9,
Wherein the flame retardant is at least one selected from the group consisting of a halogen-based flame retardant, a phosphorus flame retardant, a nitrogen-based flame retardant, and an inorganic compound flame retardant. 11. The method of claim 10,
The halogen flame retardant is tribromo phenoxyethane, tetrabromobisphenol-A (TBBA), octabromo diphenyl ether (OBDPE), brominated epoxy, brominated polycarbonate oligomo, chlorinated paraffin, chlorinated polyethylene and cycloaliphatic chlorine flame retardant Pouch type secondary battery, characterized in that at least one selected from the group consisting of. 11. The method of claim 10,
The phosphorus flame retardant is ammonium phosphate, phosphine oxide, phosphine oxide diols, phosphites, phosphonates, triaryl phosphate, alkyl Pouch type secondary battery, characterized in that at least one selected from the group consisting of diaryl phosphate (alkyldiaryl phosphate), trialkyl phosphate (trialkyl phosphate) and resorcinol bisdiphenyl phosphate (RDP). 11. The method of claim 10,
The nitrogen-based flame retardant pouch type secondary battery, characterized in that at least one selected from the group consisting of melamine, melamine phosphate and melamine cyanurate. 11. The method of claim 10,
The inorganic compound flame retardant is a pouch type secondary battery, characterized in that at least one selected from the group consisting of aluminum hydroxide, magnesium hydroxide, barium hydroxide, antimony oxide, tin hydroxide, tin oxide, molybdenum oxide, zirconium compound, borate and calcium salt. A battery module comprising at least one pouch type secondary battery according to claim 1. A battery pack comprising the battery module according to claim 15. 17. The method of claim 16,
The battery pack includes a power tool; Electric vehicles selected from the group consisting of electric vehicles (EVs), hybrid electric vehicles (HEVs), and plug-in hybrid electric vehicles (PHEVs); E-bike; E-scooter; Electric golf carts; Electric trucks; And a battery pack, characterized in that used as one or more power sources selected from the group consisting of electric commercial vehicles.

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