KR20190032003A - Pouch-Type Secondary Battery Comprising Endothermic Material - Google Patents

Abstract

The present invention relates to a pouch-type secondary battery in which an electrode assembly having a structure in which a separator is interposed between an anode and a cathode is housed in a pouch-
The electrode assembly has a structure in which electrode leads are connected to electrode tabs protruded toward one side or both sides,
Wherein the electrode lead extends outside the pouch-shaped case,
And an endothermic pack containing a heat absorbing material between the electrode assembly receiving portion of the pouch-shaped case and the electrode assembly.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a pouch-type secondary battery including an endothermic material,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pouch-type secondary battery including a heat absorbing material, and more particularly, to a pouch-type secondary battery having a structure including a heat absorbing pack containing a heat absorbing material between an electrode assembly receiving part of a pouch- will be.

Lithium secondary batteries are classified into cylindrical, rectangular, and pouch type batteries depending on the shape of the case. The cylindrical battery and the prismatic battery are batteries having a structure in which an electrode assembly is mounted on a metal can, and the pouch-shaped battery is a battery having an electrode assembly mounted on a pouch-shaped case of an aluminum laminate sheet. Recently, a pouch type battery which can be stacked with a high degree of integration, has a high energy density per weight, and is inexpensive and easy to deform has recently attracted much attention.

The pouch-type battery is exposed to the outside of the battery due to its flexible casing. Specifically, ignition or explosion of the battery caused by internal short circuit, overcurrent exceeding the allowable current and voltage, exposure to high temperature, or dropping or deformation due to external impact may directly affect the user.

As an effort to secure the safety of the pouch type battery, Patent Document 1 discloses a battery pack having a fire suppression substance or a fire extinguishing agent inside or outside a module case in which a plurality of battery cells are stacked.

However, since the fire suppressing substance or the fire extinguishing agent is provided outside the battery cell, it is difficult to quickly suppress the temperature rise inside the battery cell.

Patent Document 2 discloses that a flame retardant, a flame retardant and / or a flame extinguishing agent for suppressing and delaying a fire caused by a failure of a battery cell are used, but the materials are distributed and conveyed through a distributor located outside the battery cell There is a problem that the volume of the battery housing increases in order to apply the distributor.

Patent Document 3 discloses a fire extinguishing device housed in a battery housing together with a lithium ion battery or a fire extinguishing device located outside a lid of a storage container of a power storage device. Patent Document 4 discloses, as an exterior of a battery cell, Discloses a battery pack having a structure in which a fire extinguisher tank is located, and it is difficult to quickly stabilize a deterioration phenomenon occurring inside a battery cell and a separate additional space is required.

As described above, there is a need for a technique capable of increasing the safety against the deterioration of the pouch type secondary battery without increasing the overall size of the battery cell, but a satisfactory solution has not been proposed yet.

Korean Patent Laid-Open Publication No. 2017-0061582 Korean Patent Laid-Open Publication No. 2014-0005323 Japanese Laid-Open Patent Publication No. 2014-144033 Japanese Laid-Open Patent Publication No. 2010-097836

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems and it is an object of the present invention to provide a pouch type battery pack including a pouch type battery case having an electrode assembly receiving part and a heat absorbing pack When the secondary battery is used, the heat absorbing material having a large heat capacity absorbs heat in a high-temperature environment due to abnormal use of the secondary battery, thereby lowering the internal temperature of the battery cell.

Further, by disposing the heat absorbing pack in a remaining space that is not utilized in the secondary battery case, deterioration of the secondary battery can be prevented without affecting the size of the entire secondary battery.

According to an aspect of the present invention, there is provided a pouch-

1. A pouch type secondary battery in which an electrode assembly having a structure in which a separator is interposed between an anode and a cathode is housed in a pouch-

The electrode assembly has a structure in which electrode leads are connected to electrode tabs protruded toward one side or both sides,

Wherein the electrode lead extends outside the pouch-shaped case,

And an endothermic pack that contains a heat absorbing material between the electrode assembly receiving portion of the pouch type case and the electrode assembly.

That is, since the pouch-type secondary battery of the present invention includes a heat absorbing material inside the pouch-type case, when the temperature of the battery rises due to normal or abnormal operation of the secondary battery, .

In general, in a pouch type secondary battery, a plurality of positive electrode tabs and negative electrode tabs are connected to one electrode lead, and the electrode leads extend outside the battery case. The electrode tabs and the electrode leads are bent while being connected to each other, . As such, due to the presence of the electrode tabs and the electrode lead coupling portions, a space is necessarily formed between the electrode assembly and the outer peripheral surface of the electrode assembly receiving portion. The spacing space is not particularly used except for the electrode tab and the electrode lead coupling portion. When the heat absorbing pack containing the heat absorbing material is placed at such a position, there is no need to enlarge the size of the battery case, so space utilization can be increased and the problem of the capacity of the secondary battery being lowered can be prevented, There are advantages to be able to.

The endothermic material can be converted into a non-flammable gas by reacting with the flammable gas generated in the battery cell, thereby providing a secondary battery with improved safety.

In one specific example, the heat absorbing pack may be located at one side or both sides of the electrode tab and the electrode lead coupling portion. As the heat absorbing pack including the endothermic material is contained in the battery cell, It is more preferable that the heat absorbing pack is located on both sides of the electrode tab and the electrode lead coupling portion.

The pouch type case may include an upper case and a lower case, and the heat absorbing pack may have a structure connected to the upper case and the lower case.

Specifically, the outer circumferential surface of the heat absorbing pack may be connected to the upper case and the lower case by thermal fusion. When the pressure in the battery increases due to the generation of gas in the secondary battery, the upper case and the lower case are expanded, and the heat absorbing pack connected to the upper case and the lower case also expands.

The endothermic pack may be formed with a preliminary cutting line at a portion connected to the upper case and / or the lower case and adjacent to the heat absorbing pack. The heat absorbing pack is expanded together with the expansion of the upper case and the lower case, The preliminary cutting line is ruptured by the expansion of the pouch type case, and the heat absorbing material carried in the heat absorbing pack is discharged.

The endothermic material discharged from the heat absorbing pack is chemically reacted by an endothermic reaction, thereby reducing the temperature inside the battery and preventing thermal runaway due to abnormal operation of the secondary battery.

In another specific example, the heat absorbing pack needs to discharge the heat absorbing material for suppressing the high temperature phenomenon of the secondary battery to the outside before the pouch case expands and the preliminary cutting line is ruptured. For example, The heat absorbing pack may have a structure in which a heat absorbing material on a powder is embedded in a case made of a polymer resin having a melting temperature of 60 ° C to 80 ° C.

Accordingly, when the temperature of the secondary battery reaches 60 to 80 캜, the heat absorbing pack may be a structure in which the endothermic material is discharged to the outside of the case as the case made of the polymer resin is melted.

The endothermic material may be at least one member selected from the group consisting of sodium hydrogencarbonate, potassium hydrogencarbonate, ammonium monophosphate, potassium carbonate, urea, and halogen compounds, and the halogen compound may be C ₆ F ₁₂ O.

Specifically, an endothermic reaction that absorbs heat occurs during the chemical reaction between the potassium hydrogen carbonate and the urea, and the temperature inside the battery cell can be reduced by the chemical reaction.

In another specific example, the pouch type secondary battery may have a structure in which the positive electrode terminal and the negative electrode terminal protrude in the same direction, or the positive electrode terminal and the negative electrode terminal may protrude in opposite directions, The heat absorbing pack may have a structure in which the heat absorbing pack is located on both sides of the electrode tab and the electrode lead coupling portion protruding to one side or the negative electrode tab protruded to one side and the negative electrode tab protruded on both sides of the positive electrode lead coupling portion, And may be positioned on both sides of the negative electrode lead coupling portion.

The present invention also provides a battery pack including the pouch type secondary battery.

Specifically, the battery pack may be used as a power source for devices requiring high-temperature safety, long cycle characteristics, and high rate characteristics. Examples of such devices include a mobile device, a wearable device A power tool powered by an electric motor; An electric vehicle including an electric vehicle (EV), a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), and the like; An electric motorcycle including an electric bike (E-bike) and an electric scooter (E-scooter); An electric golf cart; And an energy storage system, but the present invention is not limited thereto.

The structure of these devices and their fabrication methods are well known in the art, and a detailed description thereof will be omitted herein.

As described above, the pouch type secondary battery according to the present invention has a structure in which a heat absorbing pack containing a heat absorbing material is disposed between an electrode assembly receiving part inside the battery case and the electrode assembly, and a high temperature When the phenomenon occurs, the temperature inside the battery cell can be rapidly lowered by the endothermic material discharged from the heat absorbing pack.

In addition, since the heat absorbing pack is disposed in an unused space inside the case of the pouch type secondary battery, an additional space is not required and the size of the secondary battery can be prevented from increasing.

In addition, the flammable gas can be converted into a non-flammable gas to further enhance safety. In the manufacturing process of the conventional pouch-type secondary battery, the heat absorbing pack can be manufactured by positioning the heat absorbing pack in the battery cell and then sealing the same. There is no need to change the process for the application.

1 is a plan view of a pouch type secondary battery according to an embodiment.
FIG. 2 is a partial vertical sectional view taken along the line A-A 'in FIG.
Fig. 3 is a partially enlarged view of the heat absorbing pack portion of Fig. 2. Fig.
4 is a schematic view showing a state in which the heat absorbing pack of FIG. 3 is ruptured.
5 is a plan view of a pouch type secondary battery according to another embodiment.
6 is a graph showing voltage and temperature changes according to an SOC according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the detailed description of known functions and configurations incorporated herein will be omitted when it may unnecessarily obscure the subject matter of the present invention.

The same reference numerals are used for portions having similar functions and functions throughout the drawings. Throughout the specification, when a part is connected to another part, it includes not only a case where it is directly connected but also a case where the other part is indirectly connected with another part in between. In addition, the inclusion of an element does not exclude other elements, but may include other elements, unless specifically stated otherwise.

The present invention will be described in detail with reference to the drawings.

1 schematically shows a plan view of a pouch type secondary battery according to one embodiment.

Referring to FIG. 1, the pouch-type secondary battery 100 has an electrode assembly receiving portion 107 in which the electrode assembly 101 is located. The positive electrode tab 102a is connected to the positive electrode lead 102b and the negative electrode tab 105a is connected to the negative electrode tab 105a. The negative electrode tab 105a is protruded to the lower end of the electrode assembly 101, Is connected to the negative electrode lead 105b. The positive electrode lead 102b and the negative electrode lead 105b extend to the outside of the battery case and a space 103 is formed between the electrode assembly 101 and the outer periphery 103 of the electrode assembly housing portion 107, d are formed.

In the space d, a heat absorbing pack 110 having an electrode tab, an electrode lead coupling portion and a heat absorbing material is disposed.

The pouch type secondary battery 100 shown in FIG. 1 has a structure in which the positive electrode tab 102a and the negative electrode tab 105a are protruded in opposite directions to each other. However, when the positive electrode tab and the negative electrode tab protrude in the same direction, ≪ / RTI >

Although the heat absorbing pack 110 is shown only on the right side of the connection portion of the positive electrode tab 102a and the positive electrode lead 102b, it may be further disposed on the left side, and the negative electrode tab 105a and the negative electrode lead 105b And may be selectively positioned on the left and right sides of the coupling portion.

Fig. 2 schematically shows a part of a vertical section taken along the line A-A 'in Fig. 1 and in the direction of arrows in Fig. 1, and Fig. 3 is an enlarged view of the heat absorbing pack portion in Fig.

2 and 3, the pouch-type case includes an upper case 111 and a lower case 112, and the upper case 111 and the lower case 112 are respectively provided with an electrode assembly receiving part, The periphery is sealed with the lead film 113 interposed therebetween.

The electrode assembly includes a positive electrode 114 and a negative electrode 115 laminated in an alternating arrangement and a separation membrane (not shown) interposed between the positive electrode 114 and the negative electrode 115. The positive electrode 114 has, at one end, The tabs 102a protrude and the positive electrode tabs 102a are connected to the positive electrode lead 102b.

The heat absorbing pack 110 is positioned on the side of the positive electrode tab 102a and the positive electrode lead 102b coupling portion 119 and the heat absorbing pack 110 is connected to the upper case 111 and the lower case 112.

The heat absorbing pack 110 is thermally welded to the upper case 111 and the lower case 112 by a thermoplastic resin 120 having adhesiveness or an adhesive thermoplastic resin is not added, The case itself may be made of a thermoplastic resin and may be connected to the upper case 111 and the lower case 112 by thermal fusion.

A preliminary cutting line 121 is formed at a portion connected to the upper case 111 and the lower case 112 in the heat absorbing pack 110. The preliminary cutting line 121 is connected to the upper case 111 and the lower case 112 112, or may be formed in a horizontal direction at the center of the heat absorbing pack.

A heat absorbing material 118 is embedded in the heat absorbing pack 110 so that the case of the heat absorbing pack 110 can be discharged to the outside of the case when the case is melted or cut and ruptured. The endothermic material 118 may be a solid, powder, gel, liquid, or the like.

Fig. 4 schematically shows a state in which the pouch-type case of Fig. 3 is inflated and the heat absorbing pack is ruptured.

4, when the inner pressure of the pouch-type case is increased and the upper case 111 and the lower case 112 are respectively expanded outward, the heat absorbing packs (not shown) connected to the upper case 111 and the lower case 112 110 expand together with the battery case, and when a certain critical point is exceeded, the portion of the preliminary cutting line 21 is ruptured and the heat absorbing material 118 supported inside is expanded.

5 is a plan view of a pouch type secondary battery according to another embodiment.

Referring to FIG. 5, the pouch-type secondary battery 200 is formed with an electrode assembly receiving portion 207 in which an electrode assembly 201 is located. The positive electrode tab 202a protrudes from the upper end of the electrode assembly 201 and the negative electrode tab 205a protrudes from the lower end of the electrode assembly 201. The positive electrode tab 202a is connected to the positive electrode lead 202b, Is connected to the negative electrode lead 205b. The positive electrode lead 202b and the negative electrode lead 205b extend to the outside of the battery case and a space is formed between the electrode assembly 201 and the outer periphery 203 of the electrode assembly housing portion where the electrode lead extends .

The electrode tap and the electrode lead coupling portion are located in the spacing space and the both ends of the coupling portion of the positive electrode tab 202a and the positive electrode lead 202b and the coupling portion of the negative electrode tab 202a and the negative electrode lead 205a are provided with endothermic The pack 210 is located.

In order to quickly lower the temperature inside the pouch-type secondary battery, it is advantageous that the heat absorbing pack is embedded in the battery case in a plurality of numbers.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings, but it should be understood that the scope of the present invention is not limited thereto.

<Examples>

An electrode assembly in which a positive electrode terminal and a negative electrode terminal were formed in mutually opposite directions was housed in a pouch-shaped battery case. The endothermic pack containing the potassium hydrogencarbonate and the element having the endothermic property is placed on the both sides of the positive electrode tab and the positive electrode lead connecting portion which are the spaces between the periphery of the electrode assembly receiving portion and the electrode assembly and then the electrolyte is injected and the battery case is sealed, Type secondary battery.

<Comparative Example>

A pouch-type secondary battery was fabricated in the same manner as in Example 1, except that the heat absorbing pack was not placed inside the pouch-shaped battery case.

<Experimental Example>

Charging was performed on the pouch type secondary battery manufactured in Examples and Comparative Examples so that the SOC was 100% to 181% in the range of about 4.2 V to 8.5 V. The voltage value according to the SOC and the temperature change at the time of overcharging are measured and shown in FIG.

Referring to FIG. 6, when the SOC reaches 170%, the temperature of the battery cell reaches about 56 ° C, and gas venting is started. When the charged state continued, the pouch type secondary battery of the Example was measured to have a temperature rise up to about 70 캜, followed by cooling to about 50 캜.

This is because the secondary battery of the embodiment includes an endothermic pack including a heat absorbing material therein, so that the endothermic material starts to be discharged at a high temperature and at the time of swelling of the battery case, and heat is absorbed by the chemical reaction of the endothermic material And it is judged that it is lowered without increasing more than 70 ° C.

However, in the pouch type secondary battery of the comparative example, the temperature suddenly rises after the point of gas venting, and the explosion occurs due to thermal runaway as it increases to 100 ° C or higher.

This is because the secondary battery of the comparative example can not control the thermal runaway phenomenon because it does not include a member capable of removing heat upon reaching a high temperature environment.

As described above, the pouch-type secondary battery according to the present invention includes a heat absorbing pack containing a heat absorbing material inside a battery case, and when a gas is generated due to a chemical reaction occurring inside the battery cell and a high temperature environment is reached, And the endothermic pack is ruptured by the heat absorbing layer to release the endothermic material. As a result, the pouch type secondary battery can be prevented from explosion due to thermal runaway, thereby providing a secondary battery with improved safety.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

100, 200: Pouch type secondary battery
101, 201: electrode assembly
102a, 202a: positive electrode tab
102b, 202b: anode lead
103, 203: electrode assembly receiving part and the periphery
105a, 205a:
105b, 205b: cathode lead
107, 207: electrode assembly housing part
110, 210: heat absorption pack
111: upper case
112: Lower case
113: lead film
114: anode
115: cathode
118: Endothermic material
119: electrode tab and electrode lead coupling portion
120: thermoplastic resin
121: preliminary cutting line
AA ': vertical cutting line
d: Space between the electrode assembly and the outer periphery of the electrode assembly receiving part

Claims (11)

1. A pouch type secondary battery in which an electrode assembly having a structure in which a separator is interposed between an anode and a cathode is housed in a pouch-
The electrode assembly has a structure in which electrode leads are connected to electrode tabs protruded toward one side or both sides,
Wherein the electrode lead extends outside the pouch-shaped case,
And an endothermic pack enclosing a heat absorbing material between the electrode assembly receiving portion of the pouch-shaped case and the electrode assembly. The pouch type secondary battery according to claim 1, wherein the heat absorbing pack is located at one side or both sides of the electrode tab and the electrode lead coupling part. The pouch type secondary battery according to claim 1, wherein the pouch type case comprises an upper case and a lower case, and the heat absorbing pack is connected to the upper case and the lower case. The pouch type secondary battery according to claim 3, wherein the outer circumferential surface of the heat absorbing pack and the upper case and the lower case are connected by heat fusion. The pouch-type secondary battery according to claim 3, wherein the heat absorbing pack has a preliminary cutting line formed in a portion connected to the upper case and / or the lower case and a neighboring portion. The pouch type secondary battery according to claim 5, wherein the preliminary cutting line ruptures due to expansion of the pouch type case. The pouch type secondary battery according to claim 1, wherein the heat absorbing pack has a structure in which a heat absorbing material on a powder is embedded in a case made of a polymer resin having a melting temperature of 60 ° C to 80 ° C. [8] The pouch type secondary battery according to claim 7, wherein the heat absorbing pack is made of a polymer resin and the endothermic material is discharged to the outside of the case as the case is melted. The pouch type secondary battery according to claim 1, wherein the endothermic material is at least one selected from the group consisting of sodium hydrogencarbonate, potassium hydrogencarbonate, ammonium monophosphate, potassium carbonate, urea, and halogen compounds. The pouch type secondary battery according to claim 9, wherein the halogen compound is C ₆ F ₁₂ O. A battery pack comprising the pouch type secondary battery according to any one of claims 1 to 10.

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