KR101449787B1 - Secondary battery with improved safety - Google Patents

Abstract

The present invention relates to an electrode assembly; Pouch type exterior material; Wherein the separator is formed of a polymer material that is melted at a temperature of 70 degrees or more. The pouch type secondary battery according to claim 1, wherein the separator is made of a polymer material. The present invention relates to a pouch-type secondary battery including a flame retardant in a pouch and having improved safety, wherein the flame retardant does not affect the operation and performance of the battery at normal times and is designed to be applied only in an emergency, And provides an improvement effect.

Description

[0001] The present invention relates to a 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.

Typically, in terms of the shape of a battery, there is a high demand for a prismatic secondary battery and a pouch-type secondary battery which can be applied to products such as mobile phones with a small thickness, and has advantages such as high energy density, discharge voltage, There is a high demand for lithium secondary batteries such as lithium ion batteries and lithium ion polymer batteries.

Meanwhile, a nickel-hydrogen secondary battery has been widely used as a unit cell (battery cell) of a middle- or large-sized battery pack. However, recently, a lithium secondary battery that provides a high power-to-capacity ratio has been researched.

The lithium secondary battery is a candidate for a unit cell of a middle- or large-sized battery pack due to various advantages as described above. Generally, a lithium secondary battery using a combustible non-aqueous electrolyte has a dendrite, The temperature inside the battery rises and explosion or fire occurs due to flammable gas caused by the decomposition reaction of the electrolytic solution, combustible gas resulting from reaction between the electrolyte and the electrode, generation of oxygen by decomposition of the anode, and the like. I have a problem.

In addition, the polyethylene used as a separator between the anode and the cathode starts to melt when the temperature of the battery rises and reaches 120 to 130 캜. Shrinkage occurs due to contraction of the separator due to contact between the anode and cathode at the edge. Therefore, heat is generated by a large amount of current flow, the temperature rises, and eventually the battery ignites.

In order to solve such a problem, a method of easily discharging the electrolyte solution together with carbon dioxide when the temperature of the battery rises abnormally by pressurizing and charging the electrolytic solution with carbon dioxide has been searched. However, the electrolyte is sucked into the internal pores of the separation membrane or the electrode The gas pressure alone can not be easily released to the outside, so that the risk of battery ignition due to decomposition of the electrolytic solution is still not solved.

In the case of a middle- or large-sized battery pack in which a plurality of unit cells are electrically connected to each other for the purpose of high power and large capacity, the above-described ignition is a serious risk factor that hinders safety. Therefore, there is a need for a secondary battery capable of preventing the above-described problems.

The present invention relates to a pouch-type secondary battery including a flame retardant in a pouch and having improved safety, wherein a position and a method of containing the flame retardant are diversified so that the flame retardant does not normally affect the operation and performance of the battery, The present invention provides a secondary battery which can exhibit both performance improvement and safety improvement of a battery.

According to an aspect of the present invention, there is provided an electrode assembly comprising: an electrode assembly; Pouch type exterior material; And an isolation part including an additive.

At this time, the additive may be any one of a flame retardant and a foaming agent.

The separator may be formed of a polymer material melted at a temperature of 70 ° C or higher.

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

In addition, the isolation portion is formed on the inner surface of the pouch-type sheathing material.

At this time, the separator may be coated with an additive on the inner surface of the pouch-type casing, and thereafter the isolation member is coated thereon.

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

Further, the pouch-type sheathing material may further include an additive inlet port connected to the isolation portion.

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.

The halogen-based flame retardant may be at least one selected from the group consisting of tribromophenoxyethane, tetrabromobisphenol-A (TBBA), octabromodiphenyl ether (OBDPE), brominated epoxy, brominated polycarbonate oligomer, chlorinated paraffin, chlorinated polyethylene, And chlorine-based flame retardants.

The phosphorus flame retardant may be selected from the group consisting of phosphoric acid, ammonium phosphate, phosphine oxide, phosphine oxide diols, phosphites, phosphonates, triaryl phosphate, And may be at least one member selected from the group consisting of alkyldiaryl phosphate, trialkyl phosphate and resorcinol bisdiphenyl phosphate (RDP).

The nitrogen-based flame retardant may be one or more 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.

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

At this time, the battery pack includes a power tool; An electric vehicle selected from the group consisting of Electric Vehicle (EV), Hybrid Electric Vehicle (HEV), and Plug-in Hybrid Electric Vehicle (PHEV); E-bike; E-scooter; Electric golf cart; Electric truck; And an electric commercial vehicle may be used as one or more power sources.

The present invention relates to a pouch-type secondary battery including a flame retardant in a pouch and having improved safety, wherein the flame retardant does not affect the operation and performance of the battery at normal times and is designed to be applied only in an emergency, And provides an improvement effect.

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

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

An electrode assembly; Pouch type exterior material; And an isolation portion including the additive.

In general, the additives such as the flame retardant are added to the inside of the pouch-type secondary battery in order to absorb the gas, lower the temperature and prevent the ignition of the battery when the dangerous situation such as heat generation, ignition, .

However, when the additive such as the flame retardant is contained in the pouch, it may be mixed with an electrolyte solution or penetrate into the electrode assembly, thereby deteriorating performance and life of the battery. In order to solve such a problem, when the additive such as the flame retardant is inserted into the pouch and inserted into the pouch, the additive does not act quickly in an emergency due to abnormal behavior of the battery, I can not do it.

Therefore, in the present invention, the additive such as the flame retardant is interposed in the separator capable of releasing at a high temperature and does not affect the operation of the battery at normal times. However, in an emergency such as heat generation or ignition, The additive can be applied directly to the inside of the cell so that the occurrence of a dangerous situation can be quickly prevented.

To this end, the isolation portion of the present invention is formed of a polymer material that melts at a temperature of 70 ° C or higher.

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

When the internal temperature of the secondary battery is higher than the above temperature, the temperature may rapidly rise. To prevent this, an additive such as a flame retardant, a gas absorbent and a coolant is applied at a temperature of about 70 ° C to prevent ignition or explosion .

The type of the polymer melted at a temperature of 70 ° C or higher is not particularly limited and can be freely selected by those skilled in the art, and 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 ° C, the quenching portion of the battery in an emergency can be quickly released, making it difficult for the additive to be applied to the inside of the battery. The polymer having a melting point within the above temperature range is not particularly limited and may be variously applied. Specific examples thereof include polymers such as polyethylene and polypropylene.

Meanwhile, the additives included in the secondary battery of the present invention may be variously formed according to the purpose desired, and two or more may be mixed and contained in the separator.

In an embodiment of the present invention, the additive may include a flame retardant.

The flame retardant prevents the secondary battery from burning even if the temperature of the secondary battery rises rapidly, thereby preventing the occurrence of a larger fire.

The flame retardant that can be used in the present invention is not particularly limited, and known materials can be used.

For example, the flame retardant may be at least one selected from the group consisting of a halogen flame retardant, a phosphorus flame retardant, a nitrogen flame retardant, and an inorganic compound flame retardant, but is not limited thereto.

More specifically, the halogen-based flame retardants include tribromophenoxyethane, tetrabromobisphenol-A (TBBA), octabromophenyl ether (OBDPE), brominated epoxy, brominated polycarbonate oligomer, chlorinated paraffin, chlorinated polyethylene And an alicyclic chlorine-based flame retardant, and the like.

The phosphorus flame retardant may be at least one selected from the group consisting of ammonium phosphate, phosphine oxide, phosphine oxide diols, phosphites, phosphonates, triaryl phosphate, At least one selected from the group consisting of alkyldiaryl phosphate, trialkyl phosphate and resorcinol bisdiphenyl phosphate (RDP) can be used,

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

As the inorganic flame retardant, 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 may be used. It is not.

Of the flame retardants listed above, it is preferable to use an inorganic compound flame retardant. The inorganic compound flame retardant is decomposed by heat and releases an incombustible gas such as water, carbon dioxide, sulfur dioxide or hydrogen chloride to induce an endothermic reaction. It is excellent because it dilutes the combustible gas to prevent oxygen from approaching and reduces the generation of cooling and pyrolysis products by the endothermic reaction and also has excellent flame retarding effect.

The present invention is not particularly limited as long as the additive such as a flame retardant is isolated from the specific polymer material and incorporated into the pouch. The shape of the pouch, the shape of the pouch, and the like are not particularly limited. 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.

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

2, the pouch-type secondary battery including the electrode assembly 16 and the electrode leads 12 and 14 is formed by applying an additive 102 such as a flame retardant to the inner surface of the pouch-type casing material to form a coating film An additive such as a flame retardant may be isolated from an electrode assembly and an electrolyte solution by applying a polymer material for forming an isolation part thereon and drying the polymer material.

The method of applying the additives such as the above flame retardant agent to the inner surface of the pouch type exterior material is not particularly limited. For example, a method of dispersing an additive such as a flame retardant agent in water or an organic solvent, As the application method, conventionally known application methods such as immersion coating method, roller coating method, spray coating method and doctor blade coating method can be used without any particular limitation.

After the coating film of the additive is formed and dried, a polymer for forming an isolation part is coated on the surface of the additive and dried to form a separation film so that the additive is not eluted by the electrolyte solution or the like.

As described above, the polymer is preferably a polymer that melts at a temperature of 70 ° C or higher. Specific examples thereof include polymers such as polyethylene and polypropylene. Methods for forming a coating film include a method of forming the additive coating film But is not limited thereto.

Meanwhile, the separator including the additive such as the flame retardant may be formed as a separate implant and may be interposed inside the pouch-type secondary battery.

3, an additive 112 such as a flame retardant is injected into a separate implant 114 so that an additive such as a flame retardant can be isolated from the electrode assembly and the electrolyte.

At this time, the implant is formed of a polymer that melts at a temperature of 70 ° C or higher. As described above, the type of the implant is not particularly limited and can be freely selected by those skilled in the art. For example, a polymer such as polyethylene or polypropylene may be used .

As in the case of FIG. 3, when a separate implant including the additive is prepared and contained in the pouch type secondary battery, the manufacturing process of the battery can be simplified and simplified, and the manufacturing time can be saved .

As another embodiment of the present invention, an additive injection port 126 may be further formed on the pouch type outer casing as shown in FIG.

In this embodiment, the insulator 124 having a space capable of containing an additive such as a flame retardant is formed on the inner surface of the pouch-type sheathing material 10.

After the electrode assembly or the like is housed and sealed by using the pouch-type sheathing material 10, the additive 122 such as a flame retardant may be injected into the isolation portion 124 through the additive injection hole 126. When the injection is completed, the additive injection port is sealed. Such a method is advantageous when the additive such as a flame retardant is a liquid, and has an advantage of shortening the manufacturing time of the battery.

The isolator may also be formed of a polymer that melts at a temperature of 70 ° C or higher.

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 can be used not only as a power source for a small device but also as a power source for a medium and large-sized device because the safety of the battery is greatly improved.

The middle- or large-sized device includes a power tool; Electric vehicles such as Electric Vehicle (EV), Hybrid Electric Vehicle (HEV) and Plug-in Hybrid Electric Vehicle (PHEV); Electric motorcycle such as E-bike or E-scooter; Electric golf cart; Electric truck; And an electric commercial vehicle, but the present invention is 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 an organic solvent N-methylpyrrolidone with a flame retardant to prepare a composition containing a flame retardant.

The composition containing the flame retardant material was applied to the surface of the pouch-type facer by roller coating method, and then the temperature was raised to 50 캜 to dry the solvent. Then, the polyethylene polymer was applied and dried by the same method, and then the pouch- To prepare a secondary battery.

Comparative Example

The same secondary battery as in Example 1 except that the flame retardant and the foaming agent were not included.

Experimental Example

(One) Hot box  Experiment

The secondary batteries of Examples and Comparative Examples were heated from room temperature to 160 캜 at a rate of 5 캜 / minute and then held for 1 hour.

Thereafter, the temperature of each of the secondary batteries was measured and described in Table 1 below.

(2) Evaluation of cycling stability at high temperature

The cycling stability of the secondary batteries of Examples and Comparative Examples at 100 캜 was evaluated, and the results are shown in Table 1.

160 ° C, after 1 hour Temperature (° C) 5 cycles
Reduced volume after lapse (%) 10 cycles
Reduced volume after lapse (%) 20 cycles
Reduced volume after lapse (%) Secondary battery Example 90 0.4% 3% 7% Comparative Example 150 2 % 10% 20%

As shown in Table 1, it was confirmed that the temperature of the surface of the Examples was much lower than that of the Comparative Example even when left for a long time at a high temperature, and the cycling stability at a high temperature was also excellent.

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

10: Pouch type exterior material,
12, 14: electrode lead,
16: electrode assembly,
102, 112, 122: additive,
104, 114, 124: an isolation portion,
126: Additive inlet port

Claims (17)

An electrode assembly; Pouch type exterior material; And an insulating part including an additive, the pouch type secondary battery comprising:
Wherein the separator is formed by coating an additive on the inner surface of the pouch-type sheathing material and coating an insulating member thereon. The method according to claim 1,
Wherein the additive is any one of a flame retardant and a foaming agent. The method according to claim 1,
Wherein the separator is formed of a polymer material that melts at a temperature of 70 ° C or higher. The method of claim 3,
Wherein the polymer material is one of polyethylene and polypropylene. delete delete delete The method according to claim 1,
Wherein the pouch-type sheathing material further comprises an additive injection port connected to the isolation portion. 3. The method of claim 2,
Wherein the additive is a flame retardant. 10. 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-based flame retardant is selected from the group consisting of tribromophenoxyethane, tetrabromobisphenol-A (TBBA), octabromodiphenyl ether (OBDPE), brominated epoxy, brominated polycarbonate oligomer, chlorinated paraffin, chlorinated polyethylene and alicyclic chlorinated flame retardant Wherein the pouch type secondary battery is at least one selected from the group consisting of: 11. The method of claim 10,
The phosphorus flame retardant may be selected from the group consisting of phosphoric acid, ammonium phosphate, phosphine oxide, phosphine oxide diols, phosphites, phosphonates, triaryl phosphate, Wherein the secondary battery is at least one selected from the group consisting of alkyldiaryl phosphate, trialkyl phosphate, and resorcinol bisdiphenyl phosphate (RDP). 11. The method of claim 10,
Wherein the nitrogen-based flame retardant is at least one selected from the group consisting of melamine, melamine phosphate, and melamine cyanurate. 11. The method of claim 10,
Wherein the inorganic compound flame retardant is at least one selected from the group consisting of aluminum hydroxide, magnesium hydroxide, barium hydroxide, antimony oxide, tin hydroxide, tin oxide, molybdenum oxide, zirconium compounds, borates and calcium salts. A battery module comprising at least one pouch type secondary battery according to any one of claims 1 to 4 and 8 to 14. A battery pack comprising the battery module according to claim 15. 17. The method of claim 16,
The battery pack may include a power tool; An electric vehicle selected from the group consisting of Electric Vehicle (EV), Hybrid Electric Vehicle (HEV), and Plug-in Hybrid Electric Vehicle (PHEV); E-bike; E-scooter; Electric golf cart; Electric truck; And an electric commercial vehicle is used as at least one power source.

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