Title of Invention: Pouch-type battery cell with venting part and method for manufacturing same
technical field
[One]
This application claims the benefit of priority based on Korean Patent Application No. 2019-0166594 dated December 13, 2019, and all contents disclosed in the literature of the Korean patent application are incorporated as a part of this specification.
[2]
The present invention relates to a pouch-type battery cell having a venting part attached thereto and a method for manufacturing the same, and specifically, it is possible to open and close the outer surface of the pouch-type battery case so that gas can be smoothly discharged when the internal pressure of the pouch-type battery cell is increased. It relates to a pouch-type battery cell with a venting part attached thereto and a method for manufacturing the same.
background
[3]
Lithium secondary batteries, which are reusable and have a high energy density, are attracting attention as a new energy source with eco-friendly characteristics because they can dramatically reduce the use of fossil fuels and do not generate by-products from the use of energy.
[4]
The lithium secondary battery may be classified into a pouch-type battery cell made of a laminate sheet, a cylindrical battery cell made of a metal can, or a prismatic battery cell, depending on the type and shape of the exterior material, and the electrode assembly is a jelly-roll type electrode assembly according to the shape. , it is divided into a stack type electrode assembly, a stack/folding type electrode assembly, and a lamination/stack type electrode assembly.
[5]
Since the pouch-type lithium secondary battery is easy to manufacture in various sizes, light and has high energy density, it is used as a power source for electric vehicles or hybrid vehicles requiring high output and high capacity energy sources.
[6]
The pouch-type lithium secondary battery is manufactured by accommodating an electrode assembly and an electrolyte in a pouch-type battery case made of a laminate sheet, and then sealing the outer periphery of the battery case by heating and pressing.
[7]
In the lithium secondary battery, gas is not only generated by the decomposition reaction of the electrolyte during the activation process during the manufacturing process, but also the internal pressure is increased by the gas generated inside the battery cell even in the charging and discharging process and in an abnormal use environment.
[8]
Since such an increase in internal pressure can cause an explosion of a battery cell, research is being conducted to ensure safety by discharging gas to the outside before the explosion stage of the battery.
[9]
In this regard, Patent Document 1 relates to a battery module to which a valve member including a breathable film made of a Teflon-based resin is added, wherein the valve member is made of a breathable film made of PTFE material, and the breathable film is formed on the housing cover. It is a structure fixed by a support member at the lower side of the vent hole.
[10]
That is, Patent Document 1 discloses only a valve member applied to a battery module housing, but does not disclose a venting member applicable to a pouch-type battery cell.
[11]
Patent Document 2 relates to a secondary battery having a structure that discharges gas inside the case through a communication path inside the protrusion formed integrally with the case. .
[12]
As described above, the pouch-type battery cell has a structure in which gas is smoothly discharged when the internal pressure of the pouch-type battery cell is increased without increasing the external size of the battery case in the pouch-type battery cell, and the battery can be continuously used after the gas is discharged. And there is a high need for a manufacturing method thereof.
[13]
(Prior art literature)
[14]
(Patent Document 1) Korean Patent Publication No. 2012-0009592 (2012.02.02)
[15]
(Patent Document 2) Korean Patent Publication No. 2018-0038880 (2018.04.17)
DETAILED DESCRIPTION OF THE INVENTION
technical challenge
[16]
An object of the present invention is to provide a pouch-type battery cell attached to the inside of an opening formed in a pouch-type battery case, and a venting part in a form that can be opened and closed is attached, and a method for manufacturing the same .
means of solving the problem
[17]
A pouch-type battery cell with a venting part according to the present invention for achieving this object is a pouch-type battery case made of a laminate sheet, an electrode assembly accommodated inside the pouch-type battery case, and internal gas of the pouch-type battery case It may include a venting part for discharging the battery, the pouch-type battery case has an opening, and the opening may be opened and closed by a venting part attached to the inside of the opening.
[18]
The venting part may have a structure in which a pore-formed first layer and a pore-free second layer are stacked.
[19]
The first layer and the second layer may be made of the same material.
[20]
The material may be polytetrafluoroethylene (PTFE).
[21]
The pouch-type battery case may include an outer resin layer, a metal layer, and an inner resin layer, and a venting part may be attached to contact the first layer and the inner resin layer.
[22]
While a portion of the inner resin layer is cured in a state that melts into the pores of the first layer, the inner resin layer and the first layer may be combined.
[23]
The venting part may be attached to an adjacent part of the sealing part of the pouch-type battery case.
[24]
The pouch-type battery case includes a first battery case having an electrode assembly accommodating part and a second battery case coupled to the first battery case to seal the pouch-type battery case, and the venting part includes a central portion of the first battery case and It may be attached to at least one of the central portions of the second battery case.
[25]
On the other hand, the present invention provides a method for manufacturing the pouch-type battery cell, specifically, the method for manufacturing the pouch-type battery cell comprises the steps of: (a) preparing a laminate sheet having an opening, (b) in the opening It may include the steps of attaching a venting part, (c) manufacturing the pouch-type battery case by molding the laminate sheet, and (d) accommodating and sealing the electrode assembly in the pouch-type battery case.
[26]
The venting part may have a structure in which a first layer having pores and a second layer having no pores are stacked.
[27]
The first layer and the second layer may be made of the same material.
[28]
The material may be polytetrafluoroethylene (PTFE).
[29]
The present invention also provides a battery pack including the pouch-type battery cell.
Brief description of the drawing
[30]
1 is a perspective view of a pouch-type battery cell in which a venting part is formed according to a first embodiment.
[31]
2 is a perspective view of a pouch-type battery cell in which a venting part is formed according to a second embodiment.
[32]
FIG. 3 is a partially enlarged view of a vertical cross-sectional view taken along line AA′ of FIG. 1 .
[33]
4 is an SEM photograph of the first layer of the venting part.
[34]
5 is an SEM photograph of the second layer of the venting part.
[35]
6 is another embodiment of FIG. 3 .
[36]
7 is an SEM photograph of a pouch-type battery case and a venting portion overlapped and combined.
Modes for carrying out the invention
[37]
Hereinafter, embodiments in which those of ordinary skill in the art to which the present invention pertains can easily practice the present invention will be described in detail with reference to the accompanying drawings. However, in the detailed description of the principle of operation of the preferred embodiment of the present invention, if it is determined that a detailed description of a related well-known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.
[38]
In addition, the same reference numerals are used throughout the drawings for parts having similar functions and functions. Throughout the specification, when it is said that a part is connected to another part, it includes not only a case in which it is directly connected, but also a case in which it is indirectly connected with another element interposed therebetween. In addition, the inclusion of a certain component does not exclude other components unless otherwise stated, but means that other components may be further included.
[39]
Descriptions that limit or add elements are applicable to all inventions unless there are special limitations, and are not limited to specific inventions.
[40]
[41]
The present invention will be described along with detailed examples according to the drawings.
[42]
1 is a perspective view of a pouch-type battery cell in which a venting part is formed according to a first embodiment.
[43]
Referring to FIG. 1 , the pouch-type battery cell 100 accommodates an electrode assembly and an electrolyte in a pouch-type battery case made of a laminate sheet and has an outer periphery sealed.
[44]
The electrode assembly may be a unidirectional electrode assembly in which the positive electrode lead 101 and the negative electrode lead 102 protrude in one direction, or, unlike shown in FIG. 1, a bidirectional electrode in which the positive electrode lead and the negative electrode lead protrude in different directions. It may be an assembly.
[45]
The pouch-type battery case 110 is combined with the first battery case 111 in which the electrode assembly accommodating part 113 is formed and the first battery case 111 to seal the pouch-type battery case 110 ( 112), an opening is formed in the center of the second battery case 112, and a venting part 130 is attached to the inside of the opening.
[46]
The venting part 130 has a circular shape in plan view, and since the size of the opening formed in the pouch-type battery case 110 is larger than the diameter, it blocks the opening of the pouch-type battery case from the inside.
[47]
Although not shown in FIG. 1 , in addition to the central portion of the second battery case 112 , a venting portion may be further formed in the central portion of the first battery case 111 , or a venting portion may be formed only in the central portion of the first battery case. can
[48]
When the pouch-type battery case 110 expands due to a gas generated by a side reaction inside the pouch-type battery cell 100, the central portions of the first battery case and the second battery case are most inflated and inflated. pressure can be concentrated. In this case, as the difference between the gas pressure of the venting part and the external pressure of the pouch-type battery cell increases, the gas may be discharged through the pores of the venting part.
[49]
That is, when the venting unit according to the present invention has no or small difference in pressure between the internal pressure and the external pressure of the pouch-type battery cell, gas is not discharged and the inflow of external substances into the battery cell is blocked. When the pressure difference between the inside and the outside of the battery cell is 0.1 atm or more, the internal gas is discharged through the first layer and the second layer of the venting part due to the atmospheric pressure difference. Thereafter, when the pressure difference between the inside and the outside of the pouch-type battery cell is 0.1 atm or less or disappears as the gas is discharged to some extent, the process in which the gas discharge is blocked again may be performed reversibly.
[50]
2 is a perspective view of a pouch-type battery cell in which a venting part is formed according to a second embodiment.
[51]
Referring to FIG. 2 , the pouch-type battery cell 200 has a different configuration, except that the position of the venting part 230 is different from the position of the venting part 130 formed in the pouch-type battery cell of FIG. 1 . It is the same as the description of FIG. 1 .
[52]
The venting part 230 of FIG. 2 has a structure in which three spaced apart venting parts 230 are attached to an adjacent part of the sealing part 215 .
[53]
The radius of the venting part 230 shown in FIG. 2 is smaller than the radius of the venting part 210 shown in FIG. The number, size and position of the parts can be selectively applied.
[54]
3 is a partially enlarged view of a vertical cross-sectional view taken along line AA′ of FIG. 1 , and specifically shows the structure of a pouch-type battery case to which a venting unit is attached according to the present invention.
[55]
Referring to FIG. 3 , the pouch-type battery case 110 includes an outer resin layer 110a, a metal layer 110b and an inner resin layer 110c.
[56]
Since the outer resin layer serves to protect the battery cell from the outside, it must have excellent resistance from the external environment, and excellent tensile strength and weather resistance compared to the thickness are required, for example, polyethylene terephthalate (PET), Polyester-based resins such as polybutylene terephthalate (PBT) and polyethylene naphthalate (PEN), polyolefin-based resins such as polyethylene (PE) and polypropylene (PP), polystyrene-based resins such as polystyrene, poly A vinyl chloride-based resin, a polyvinylidene chloride-based resin, etc. may be used. These materials may be used alone or in combination of two or more, and ONy (stretched nylon film) may be additionally used.
[57]
Aluminum (Al) or an aluminum alloy may be used for the metal layer to exhibit a function of improving the strength of the battery case in addition to the function of preventing the inflow of foreign substances such as gas and moisture or leakage of the electrolyte, and the aluminum alloy is, for example, For example, alloy numbers 8079, 1N30, 8021, 3003, 3004, 3005, 3104, 3105, etc. may be mentioned, and these may be used alone or in combination of two or more.
[58]
The inner resin layer has heat-sealability (thermal adhesiveness), has low hygroscopicity to the electrolyte to suppress the penetration of the electrolyte, and a polymer resin that does not expand or erode by the electrolyte may be used, preferably poly Propylene, acid-modified polypropylene, or combinations thereof may be used.
[59]
In one preferred example, in the pouch-type battery case according to the present invention, the thickness of the outer coating layer is 5 μm to 40 μm, the thickness of the metal layer is 20 μm to 150 μm, and the thickness of the inner resin layer is 10 μm to 50 μm. When the thickness of each layer of the laminate sheet is too thin, it is difficult to expect a barrier function and strength improvement for the material. On the contrary, if it is too thick, workability is deteriorated and the thickness of the sheet is increased, so it is not preferable.
[60]
The venting unit 130 according to the present invention has a structure in which a porous first layer 131 and a porous second layer 132 are stacked, and the first layer 131 and the second layer 132 are stacked. Silver is made of the same material in that it is made of polytetrafluoroethylene (PTFE).
[61]
The PTFE has excellent electrolyte resistance, heat resistance, and hydrophobicity, and thus may be used as a material for a venting part attached to the inside of a pouch-type battery case.
[62]
In the venting part 130 , the first layer 131 has a structure in which pores are formed, whereas the second layer 132 has a shape in which pores are not formed.
[63]
In this regard, FIG. 4 is an SEM photograph of the first layer of the venting part, and FIG. 5 is an SEM photograph of the second layer of the venting part.
[64]
4 and 5 , it can be seen that the first layer of FIG. 4 has a structure in which open pores are communicated between the inside and the outside, and the second layer of FIG. 5 has a curved surface but no pores are formed. form can be seen. However, since the second layer is made of a PTFE material, gas may be discharged through a minute gap formed between the polymers.
[65]
That is, the inner resin layer of the pouch-type battery case melts into the pores of the first layer of the venting part so that the venting part can be stably attached to the inner surface of the pouch-type battery case, and the gas formed inside the pouch-type battery case may be discharged to the outside through the first layer and the second layer of the venting unit.
[66]
On the other hand, PTFE has a melting point of 327 °C, which is different from that of polypropylene (PP), which is mainly used as an inner resin layer of a pouch-type battery case, at about 160 °C.
[67]
Therefore, when heating and pressurizing the venting part of the PTFE material to attach it to the inner resin layer made of PP, if the heating temperature is a temperature enough to melt the PTFE, the PP may be damaged. On the other hand, when the PP is not damaged but heated to a temperature sufficient to melt the PP, since the PTEF does not melt, it is difficult to bond with each other.
[68]
Accordingly, in the present invention, a structure is used in which the venting part is attached to the pouch-type battery case so that the first layer 131 having pores is in contact with the inner resin layer 110c of the pouch-type battery case. When the portion where the pouch-type battery case and the venting part overlap to be attached to the battery case is heated and pressurized at a high temperature, a part of the internal resin layer 110c is melted into the pores of the first layer 131 and cured While being coupled, the internal resin layer 110c is anchored with respect to the first layer 131 .
[69]
6 is another embodiment of FIG. 3 and specifically shows the structure of a pouch-type battery case to which a venting part according to the present invention is attached.
[70]
Referring to FIG. 6 , the pouch-type battery case 310 has an outer resin layer 310a, an adhesive layer 310d, a metal layer 310b, an adhesive layer 310d, and an inner resin layer 310c from top to bottom in the drawing. As a laminated structure, there is a difference in that an adhesive layer is additionally introduced between the outer resin layer and the metal layer, and between the metal layer and the inner resin layer, compared to the pouch-type battery case shown in FIG. 3 . That is, due to the addition of the adhesive layer, in the pouch-type battery case of FIG. 6 , the adhesion between the respective layers may be improved compared to the pouch-type battery case of FIG. 3 .
[71]
The venting part 330 includes a first layer 331 with pores and a second layer 332 without pores, and the first layer 331 is attached to the inner resin layer 310c.
[72]
Therefore, when the overlapping portions are heated and pressed in order to couple the venting part and the pouch-type battery case 310, the inner resin layer 310c melts and moves to the pores of the first layer 331, anchoring ( bonding by anchoring).
[73]
On the other hand, even if the venting part is attached to the outside of the opening of the pouch-type battery case, the gas discharge effect can be achieved when the gas internal pressure is increased. Since there is a problem that hydrofluoric acid generated by the side reaction of the electrolyte corrodes the metal layer made of aluminum, it is not preferable.
[74]
7 shows an SEM photograph of the pouch-type battery case and the overlapping venting part.
[75]
Referring to FIG. 7 , the pouch-type battery case includes an outer resin layer 410a, a metal layer 410b, and an inner resin layer 410c. The venting part 430 has a structure in which a first layer 431 and a second layer 432 are stacked.
[76]
The outer resin layer 410a has a structure in which a PET layer, an adhesive layer, a nylon layer, and an adhesive layer are sequentially stacked from the outside to the inside, the metal layer 410b is a layer made of aluminum, and the inner resin layer 410c is made of polypropylene and It may be a combination of acid-modified polypropylene, or an unstretched polypropylene film.
[77]
The venting part 430 is made of a PTFE material and includes a first layer 431 having pores and a second layer 432 made of a PTFE material and not having pores.
[78]
In a state before the pouch-type battery case and the venting unit are combined, the total thickness of the outer resin layer may be 33.1 μm, the thickness of the metal layer may be 41.4 μm, and the thickness of the inner resin layer may be 80 μm.
[79]
The inner resin layer may be manufactured in the form of extruding each of polypropylene and acid-modified polypropylene to a metal layer, and laminating the inner resin layer together with a metal layer and an outer resin layer to manufacture a pouch-type battery case, The thickness of the polypropylene may be 40 μm and the thickness of the acid-modified polypropylene may be 40 μm.
[80]
Alternatively, the inner resin layer may be in the form of a non-stretched polypropylene (CPP) film having a thickness of 80 μm, and the non-stretched polypropylene film is attached to the metal layer using an adhesive, and laminated with the external resin layer to form a pouch. A type battery case can be manufactured.
[81]
When the pouch-type battery case and the venting part are combined by heating and pressing, the polypropylene of the inner resin layer melts and enters the pores of the first layer, and as shown in FIG. 7, the thickness of the inner resin layer is reduced to 12.2 μm, The pores are not visible in the first layer 431 .
[82]
That is, it can be confirmed that the adhesion is uniformly made in the entire part as the internal resin layer is introduced into the pores of the first layer and anchored, and the venting part is stably attached to the inside of the pouch-type battery case.
[83]
The temperature for bonding the first layer and the inner resin layer is 180° C. to 220° C., the pressure is 0.05 MPa to 0.5 MPa, and the pressing time can be selectively applied within the range of 1 second to 5 seconds.
[84]
In one specific example, when gas is generated due to a side reaction of the electrolyte occurring inside the pouch-type battery cell, the internal pressure of the pouch-type battery cell becomes higher than the external atmospheric pressure, and the opening and the venting portion formed in the pouch-type battery case A gas may be discharged through the first layer and the second layer.
[85]
Therefore, the pouch-type battery cell according to the present invention discharges the internal gas through the venting unit when the internal pressure of the battery cell increases, and when it becomes the same as the external atmospheric pressure of the battery cell, the gas emission is blocked and the process of preventing the inflow of external moisture It can be done reversibly.
[86]
On the other hand, as a method for manufacturing a pouch-type battery cell according to the present invention, (a) preparing a laminate sheet having an opening, (b) attaching a venting part to the opening, (c) molding the laminate sheet It may include manufacturing a pouch-type battery case, and (d) accommodating and sealing the electrode assembly in the pouch-type battery case.
[87]
That is, the pouch-type battery cell has an opening formed before molding, and it is preferable in consideration of process convenience to mold the electrode assembly housing part with a vent part attached to the opening.
[88]
However, if necessary, the step (b) may be performed between the steps (c) and (d), or between the steps (c) and (d), an opening is formed in the laminate sheet and vented The step of attaching the part may proceed.
[89]
The venting part may have a structure in which a first layer having pores and a second layer without pores are stacked, and the first layer and the second layer may be made of PTFE.
[90]
Those of ordinary skill in the art to which the present invention pertains will be able to perform various applications and modifications within the scope of the present invention based on the above contents.
[91]
(Explanation of symbols)
[92]
100, 200: pouch-type battery cell
[93]
101: positive lead
[94]
102: negative lead
[95]
110, 310: pouch-type battery case
[96]
110a, 310a, 410a: outer resin layer
[97]
110b, 310b, 410b: metal layer
[98]
110c, 310c, 410c: inner resin layer
[99]
111: first battery case
[100]
112: second battery case
[101]
113: electrode assembly receiving part
[102]
130, 230, 330, 430: venting part
[103]
131, 331, 431: 1st floor
[104]
132, 332, 432: second floor
[105]
215: sealing part
[106]
310d: adhesive layer
Industrial Applicability
[107]
As described above, since the pouch-type battery cell according to the present invention has a structure in which a venting part is attached to the inside of the battery case, an increase in the size of the battery cell can be minimized by adding the venting part.
[108]
In addition, since gas discharge can be made immediately when the internal pressure of the battery cell is increased, the internal pressure of the battery cell can be maintained at a constant level.
[109]
In addition, the venting unit according to the present invention is not in the form of being broken while being opened, but since the opening and closing of the venting unit is possible to enable reversible use, the battery cell can be continuously used after exhaust.
Claims
[Claim 1]
a pouch-type battery case made of a laminate sheet; an electrode assembly housed in the pouch-type battery case; and a venting unit for discharging internal gas of the pouch-type battery case. Including, wherein the pouch-type battery case has an opening, wherein the opening is opened and closed by a venting part attached to the inside of the opening.
[Claim 2]
The pouch-type battery cell according to claim 1, wherein the vent part has a structure in which a pore-formed first layer and a pore-free second layer are stacked.
[Claim 3]
The pouch-type battery cell according to claim 2, wherein the first layer and the second layer are made of the same material.
[Claim 4]
The pouch-type battery cell according to claim 3, wherein the material is polytetrafluoroethylene (PTFE).
[Claim 5]
The pouch-type battery cell according to claim 2, wherein the pouch-type battery case includes an outer resin layer, a metal layer, and an inner resin layer, and a venting part is attached to contact the first layer and the inner resin layer.
[Claim 6]
The pouch-type battery cell according to claim 5, wherein the inner resin layer and the first layer are combined while a part of the inner resin layer is cured in a state that melts into the pores of the first layer.
[Claim 7]
The pouch-type battery cell according to claim 1, wherein the venting portion is attached to an adjacent portion of the sealing portion of the pouch-type battery case.
[Claim 8]
According to claim 1, wherein the pouch-type battery case comprises a first battery case formed with an electrode assembly accommodating part and a second battery case coupled to the first battery case to seal the pouch-type battery case, and the venting part is the first battery case. A pouch-type battery cell attached to at least one of the central portion of the first battery case and the central portion of the second battery case.
[Claim 9]
(a) preparing an apertured laminate sheet; (b) attaching a venting part to the opening; (c) manufacturing the pouch-type battery case by molding the laminate sheet; and (d) accommodating and sealing the electrode assembly in the pouch-type battery case; A method of manufacturing a pouch-type battery cell comprising a.
[Claim 10]
The method of claim 9, wherein the venting part has a structure in which a pore-formed first layer and a pore-free second layer are stacked.
[Claim 11]
The method of claim 10, wherein the first layer and the second layer are made of the same material.
[Claim 12]
The method of claim 11, wherein the material is polytetrafluoroethylene (PTFE).
[Claim 13]
A battery pack comprising the pouch-type battery cell according to any one of claims 1 to 8.