KR101551999B1 - Secondary battery and fabricating method of the same, and cell moudle with the same - Google Patents

Abstract

The present invention relates to a technique capable of stably molding a pouch structure, and more particularly, to a pouch type molding machine for continuously forming a pouch in a pouch of a secondary battery to secure moldability and fairness, Process. ≪ / RTI >

Description

TECHNICAL FIELD [0001] The present invention relates to a secondary battery and a method of manufacturing the same, and a middle- or large-sized battery module including the secondary battery.

The present invention relates to a technique capable of stable molding of a pouch structure and a secondary battery produced thereby.

In recent years, lithium secondary batteries, which are chargeable and dischargeable and light in weight and have high energy density and high output density, are widely used as energy sources for wireless mobile devices. In addition, Hybrid Electric Vehicle (HEV), Plug-in Hybrid Electric Vehicle (PHEV), Battery Electric Vehicle (BEV), and Electric Vehicle ), And electric vehicles (EVs). Lithium secondary batteries are attracting attention as power sources for such internal combustion engine alternatives.

The lithium secondary battery is classified into a lithium ion battery using a liquid electrolyte and a lithium polymer battery using a polymer electrolyte depending on the type of the electrolyte. The lithium secondary battery is classified into a cylindrical type, a square type, or a pouch type depending on the shape of the outer case accommodating the electrode assembly.

Among them, the pouch type is composed of a metal layer (foil) and a multi-layered film composed of a synthetic resin layer coated on the upper and lower surfaces of the metal layer. Thus, It is possible to reduce the weight of the battery and it is possible to change to various forms.

The pouch exterior member is composed of an upper casing member and a lower casing member which are formed by folding a middle portion of the rectangular casing member with respect to the longitudinal direction of one side thereof. The lower casing member is formed with a space portion for receiving the electrode assembly through press working . A variety of electrode assemblies having a structure in which a plate-like anode, a separator, and a cathode are laminated are accommodated in the space portion of the lower casing. Then, an electrolyte is injected into the pouch-shaped secondary battery, and the pouch-shaped secondary battery is formed in a sealed form when the rim of the peripheral portion of the lower casing member is closely contacted with the edge of the corresponding upper casing member.

FIG. 1 schematically shows a general structure of a typical conventional pouch-type secondary battery as an exploded perspective view.

1, the pouch type secondary battery 1 includes an electrode assembly 10, electrode taps 31 and 32 extending from the electrode assembly 10, electrodes 32 and 33 welded to the electrode taps 31 and 32, Leads 51 and 52, and a battery case 20 for housing the electrode assembly 1. [

The electrode assembly 10 is a power generation element in which an anode and a cathode are sequentially stacked with a separation membrane interposed therebetween, and has a stacked or stacked / folded structure. The electrode tabs 31 and 32 extend from the respective electrode plates of the electrode assembly 10 and the electrode leads 51 and 52 are formed by a plurality of electrode tabs 31 and 32 extending from each electrode plate, Respectively, and a part of the battery case 20 is exposed to the outside. An insulating film 53 is attached to portions of the upper and lower surfaces of the electrode leads 51 and 52 in order to increase the degree of sealing with the battery case 20 and at the same time to ensure an electrically insulated state.

In addition, since a plurality of anode and cathode taps 31 and 32 are integrally combined to form a welded portion, the inner upper end of the battery case 20 is spaced apart from the upper end surface of the electrode assembly 10 by a predetermined distance, The negative taps 31 and 32 are bent in a substantially V shape (the joint between the electrode taps and the electrode lead is also referred to as V-forming 41 and 42). The battery case 20 is made of an aluminum laminate sheet, provides a space for accommodating the electrode assembly 10, and has a pouch shape as a whole. The secondary battery has a structure in which the electrode assembly 10 is housed in the housing portion of the battery case 20 and an electrolyte (not shown) is injected into the battery case 20 and then the outer periphery of the battery case 20 contacting the upper and lower laminate sheets And then heat-sealed.

However, in the case of the battery case made of the aluminum laminate sheet in the above-described process, the electrode assembly 10 is disposed on the sheet divided into the upper and lower portions, and then, In general, a mold at room temperature forms a forming cup. However, in this process, the edge of the forming cup is subjected to a lot of stress, and the strain of this part is larger than that of the other parts. Particularly, when the thickness of the electrode assembly is increased to increase the capacity of the cell, the depth of the forming cup must be deepened. Such an excessive deformation may cause a crack in which the polymer film is broken at the edge portion of the pouch, . The generation of such cracks is caused by excessive stress concentrated on the local part. Particularly, destruction of the polymer layer of the upper and lower sheets forming the pouch leads to corrosion of the aluminum sheet, shortening the life of the final cell.

The present invention has been conceived to solve the above-mentioned problems, and an object of the present invention is to provide a pouch type secondary battery which is capable of forming a packaging material by molding the upper and lower sheets, The present invention provides a reliable secondary battery by eliminating the occurrence of cracks due to deformation of the sheet member.

As a means for solving the above-mentioned problems, the present invention implements a pulse process for ensuring moldability and fairness by continuously implementing a heat pressing and cooling process in a pouch forming process of a secondary battery do.

More specifically, the present invention relates to a process for forming an electrode assembly in which an electrode assembly is accommodated between mutually opposing first and second sheets, and a pulse-type forming process for forming the first and second sheets by applying a heating condition and a cooling condition And a process for producing the secondary battery including the process. In this case, in the pulse forming step, the heating conditions are heated to a temperature of 60 to 200 DEG C to mold the first sheet and the second sheet, and after the heating condition is performed, And cooling the sheet by applying a cooling condition at room temperature to the second sheet.

The secondary battery manufactured by the manufacturing process according to the present invention is characterized in that the accommodating portion of the electrode assembly disposed in a structure interposed between the first sheet and the second sheet, and the fusion of the first sheet and the second sheet, And the density of the polymer layer forming the side surface of the receiving portion is in the range of 0.7 to 0.9 of the density of the sealing portion.

In this case, the first sheet and the second sheet in the above-described secondary battery may have a structure in which at least two polymer layers are provided on one surface of the metal layer or on the other surface opposite to the one surface. May be configured as a material having a higher melting point than other polymer layers.

According to the present invention, by introducing a step of heating the molding die and cooling the molding die continuously at a normal temperature in the molding step of molding the upper and lower sheets forming the packaging material in the step of manufacturing the pouch type secondary battery, It is possible to realize a reliable secondary battery.

Particularly, it is possible to improve the moldability by molding due to heating, and then to recover the state of the polymer layer constituting the flexible sheet through the cooling process, thereby preventing a decline in the fairness due to friction .

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing a structure of a conventional pouch type secondary battery. FIG.
2 is a block diagram showing a manufacturing process of a secondary battery according to the present invention.
3 is a conceptual diagram of a main part showing a structure of a secondary battery according to the present invention.
Fig. 4 shows the structure of a sheet constituting the pouch according to the present invention.
5 and 6 are a schematic sectional view and an exploded perspective view showing the structure of a secondary battery according to the present invention.
7 shows an actual image of an edge portion of a pouch to which the manufacturing process according to the present invention is applied.

Hereinafter, the configuration and operation according to the present invention will be described in detail with reference to the accompanying drawings. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the following description with reference to the accompanying drawings, the same reference numerals denote the same elements regardless of the reference numerals, and redundant description thereof will be omitted. The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another.

FIG. 2 is a process block diagram showing a manufacturing process of a secondary battery according to the present invention.

Referring to the drawings, the manufacturing process of a secondary battery according to the present invention includes a process of receiving an electrode assembly between first and second sheets facing each other, and applying a heating condition and a cooling condition, And a pulsed forming step of forming the second sheet. Herein, the pulse type molding step is defined as a step of repeating heating and cooling. Specifically, in the present invention, the temperature of the mold is raised from a normal temperature at the initial stage of the process to a specific temperature for molding, So that the subsequent process can be enhanced.

Specifically, a process (an in-line process) of loading the first sheet and the second sheet forming the pouch of the secondary battery and inserting the electrode assembly therebetween is performed first. In this case, the first sheet and the second sheet may have a structure in which a polymer is laminated on a metal layer. The metal layer maintains a proper thickness, prevents water vapor and gas from penetrating from the outside to the inside, and prevents leakage of the electrolytic solution. Examples of the material constituting the metal layer include alloys of iron (Fe), carbon (C), chromium (Cr) and manganese (Mn), iron (Fe), carbon (C), chromium (Cr) and nickel Alloy, aluminum (Al), copper (Cu), or an equivalent thereof may be used, but is not limited thereto. However, when the metal layer is made of a material containing iron, the mechanical strength is strengthened, and when the material is made of aluminum, flexibility is improved. Normally, an aluminum metal sheet is preferably used. The polymer layer may be formed of a mixture of any one selected from among PE, urethane, PET, PI, NY, PP, CPP, and fluorine resins, or a mixture of two or more materials.

Next, the molding process according to the present invention is carried out using a mold with respect to the outer portion of the first sheet and the second sheet, that is, the outer portion of the region where the electrode assembly is received. In this case, the forming process according to the present invention is preferably performed in a pulse-type forming process, that is, a heat-pressing process in which the temperature of the mold is raised by supplying a heat source to the mold, followed by pressing. In this case, the heating condition for heating the mold is preferably performed by heating the mold at a temperature of 60 ° C to 200 ° C to mold the first and second sheets. If the heating is performed at a temperature higher than 200 deg. C, the polymer layer formed on the sheet itself may not be heated. So that the moldability can not be maintained.

Particularly, the pulse-type forming process according to the present invention is characterized in that the process of completing the molding at the same time as the application of the heating condition described above and then performing the cooling process at the normal temperature can be continued. In this case, the cooling condition for cooling may be performed by cooling the formed first and second sheets in an environment of 15 ° C to 25 ° C, or by cooling the mold itself to 15 ° C to 25 ° C, . ≪ / RTI >

In general, in the pulse forming process according to the present invention, heating and cooling are performed on the outer periphery of the region where the electrode assembly is accommodated by using the mold after the electrode assembly is disposed between the first sheet and the second sheet, Can be compressed into a process of forming a forming depth. Thus, the flexibility of the polymer layer forming each sheet is increased, thereby facilitating the deformation and increasing the limit of the molding. Thus, the stress applied to the local area constituting the pouch can be reduced, thereby preventing the pouch from being destroyed. Generally, if the process is carried out while securing ductility in the heated state, the polymer layer in the heated state is stretched, but the frictional force of the polymer layer of the pouch is increased. There is a problem that it is impossible to proceed with the subsequent process because it does not slip when it is transferred to the process. In order to solve this problem, it is necessary to lower the temperature again so as to improve the fairness such as transferability to the pouch.

Fig. 3 is a conceptual sectional view showing a schematic structure of a secondary battery after a molding process which is manufactured by the manufacturing process according to the present invention.

As shown in the drawing, the secondary battery manufactured according to the present invention has the receiving portion X of the electrode assembly 130, which is disposed between the first sheet 110 and the second sheet 120, And a sealing portion (Y) which is a fusion region of the first sheet and the second sheet, which is an outer periphery of the accommodation portion, wherein the density of the polymer layer forming the side surface of the accommodation portion is in the range of 0.7 to 0.9 times the density of the sealing portion It can be implemented with a satisfactory structure. Particularly, as described above, the density of the polymer layer in the portion forming the side portions (edge portions a1 and a2) is in the range of 0.7 to 0.9 times the density of the polymer layer in the sealing portion Y It is more preferable to be implemented with a satisfactory structure. The cracks generated due to the molding occur locally in the above-mentioned bending portion. According to the processing method according to the present invention, such a problem can be solved.

That is, in the molding process for the pouch, the force applied to the local portion is very strong in the conventional molding technique, so that the strength and density of the stretched portion are remarkably lower than those of the other portions, so that a crack occurs in which the metal layer in the pouch is exposed , The process according to the present invention makes it possible to maintain the thickness, strength and density of a certain polymer layer even when the side portions A and B of the accommodating portion X in which the electrode assembly is accommodated are elongated, It is possible to provide a constant thickness and strength without being influenced by an external process after stretching in the cooling process.

The first sheet or the second sheet according to the present invention can utilize a structure in which a polymer layer is formed on a metal layer. More specifically, the first sheet or the second sheet has a structure in which a metal layer And may be composed of a plurality of coating layers coated on opposite sides.

4 shows a sectional structure of a first sheet or a second sheet according to the present invention. In general, an outer resin layer 121 formed on one surface of a metal layer 122 and an inner resin layer 123 ). However, the present invention is not limited thereto, and each resin layer may be formed of a plurality of layers.

Particularly, in a structure similar to the auxiliary resin layer 124 added to the resin layer in direct contact with the metal layer 122 such as the external resin layer 121 or the internal resin layer 123, May be implemented as a material having a higher melting point of the remaining auxiliary resin layer. In the drawing, a structure in which the internal resin layer 123 is laminated will be described.

That is, in the case of the resin layer contacting the metal layer 122, it can be constituted as a material having a melting point 20 to 30 ° C higher than that of the other sub resin layer. In this case, the layer having a relatively lower melting point is melted first to increase the sealing property in the hot pressing process according to the present invention, and the layer directly facing the metal layer does not melt and the metal layer is directly contacted with each other . That is, it is possible to suppress the contact between the metal layers and improve the insulation characteristic.

Particularly, in this case, it is preferable that the total internal thickness of the inner resin layer formed on the inner side of the metal layer is within a range of 20 to 100 mu m. When the internal resin layer is thinner than 20 탆, a fatal defect occurs which causes a decrease in the sealing strength and a deterioration of the insulation characteristic as the resin layer is pushed and the thickness is reduced at the time of sealing. Further, when the internal resin layer is thicker than 100 탆, there arises a problem that battery performance is deteriorated due to an increase in the moisture permeation area with respect to the internal resin layer. The inner resin layer may be at least one material selected from a polyolefin resin, a polyurethane resin and a polyimide resin, but may be at least one selected from the group consisting of PET (polyethylene terephthalate), Ny (nylon), PAN (peroxyacetyl nitrate) Resin may be used.

Figs. 5 and 6 illustrate examples of a structure (double cup) for simultaneously molding a first sheet and a second sheet applied to a middle- or large-sized module other than a structure for molding only the second sheet described in Fig. That is, when the first sheet 110 and the second sheet 120 are formed, the above-described process according to the present invention can be directly applied. That is, after arranging the first sheet 110 and the second sheet 120, a heat source is supplied to the mold, and the temperature of the mold is heated to 60 ° C to 200 ° C to form the first and second sheets , Cooling the first sheet and the second sheet in an environment at 15 ° C to 25 ° C, or performing a cooling process in which the temperature of the mold itself To 15 [deg.] C to 25 [deg.] C, followed by cold pressing.

It goes without saying that the advantageous effect of the present invention, which can be realized in the molding of the above-described structure in Fig. 3, can also be realized in the double cup.

3 is different from the structure of FIG. 3 in that the sides C and D of the housing portion for housing the electrode assembly 130 are both formed in the first sheet and the second sheet, The density of the polymer layer forming the edge portions (b1, b2) in the sealing portion (Y) may be 0.7 to 0.9 times the density of the sealing portion (Y) Can be significantly reduced. This can be confirmed through an actual processed photograph of FIG. 7 to be described later.

Thereafter, the electrode assembly 130 is disposed in the formed first sheet 110 and the second sheet 120, and then the receiving sheet 130 between the first sheet 110 and the second sheet 120, And a sealing process is performed.

FIG. 7 is a graph showing the relationship between the thickness of the first sheet 110 and the thickness of the second sheet 120 according to the present invention when the pulsed forming process is applied to the first sheet 110 and the second sheet 120 according to the present invention and the forming depth is sequentially increased to 3 mm, 4 mm, 4.5 mm, There is shown a photograph of a product after an actual process in which cracks are not generated in the bent portion (edge portion) and the surfaces of the inner side and the outer side of the edge portion are smoothly formed .

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the present invention is not limited thereto.

Example

An aluminum foil metal foil layer was formed on an inner layer made of a CPP film having a thickness of 40 mu m and a polyethylene terephthalate polymer was used for the aluminum metal layer to form a first resin layer having a thickness of 20 mu m. Next, a 20 mu m-thick internal resin second layer made of CPP (unleaded polypropylene) was formed on the internal resin first layer. Next, a nylon layer serving as an outer layer was laminated on the opposite surface of the aluminum metal layer on which the first resin layer was formed to produce a pouch exterior member.

Comparative Example

In the above embodiment, a pouch outer cover made of a conventional inner layer / metal layer / outer layer not including a metal oxide film was manufactured and a molding process was performed using a general mold.

Experimental Example

A conventional electrode assembly was placed in the pouch exterior member manufactured in the above examples and comparative examples, and the electrode assembly was heated and molded at a temperature of 100 캜, followed by cooling at room temperature. Then, the insulating properties and the defective ratio due to cracking of the pouch material were evaluated as follows. The results are shown in Table 1 below.

Total manufactured index Insulated battery Number of cracks Good battery Example 100 3 3 94 Comparative Example 100 25 20 55

Insulation characteristics: The resistance between the aluminum, which is the metal layer of the packaging material of the finished battery, and the negative electrode of the battery was measured using a mega- ohmmeter. The resistance was evaluated as poor when the resistance was less than 10Mohm.

Cracking: The defect was evaluated by the presence of micro cracks generated through visual inspection.

As can be seen from the results of Table 1, it can be seen that the generation of cracks and the occurrence of insulation defects are improved in the case of the present invention.

The electrode assembly according to the present invention includes a jelly-roll (wound type) electrode assembly having a long sheet-like anode and a cathode wound with a separator interposed therebetween, a plurality of positive electrodes and cathodes And a stacked (laminated) electrode assembly in which a separator is interposed therebetween. The stacked structure and the stacked / folded structure are preferable. Since the stacked structure is well known in the art, a description thereof will be omitted herein. Details of the stack / folding structure of the electrode assembly are disclosed in Korean Patent Application Publication Nos. 2001-0082058, 2001-0082059 and 2001-0082060, the contents of which are incorporated herein by reference. Lt; / RTI >

Hereinafter, specific materials and constitutional characteristics of the constituent elements of the electrode assembly applied to the embodiments of the present invention will be described.

Anode structure

In the present invention, the unit electrode is divided into a positive electrode and a negative electrode, and the pull cell and the bi-cell are manufactured by mutually coupling the positive electrode and the negative electrode with a separator interposed therebetween. The anode is prepared, for example, by applying a mixture of a cathode active material, a conductive material and a binder on a cathode current collector, followed by drying and pressing. If necessary, a filler may be further added to the mixture.

[Anode collector]

The cathode current collector generally has a thickness of 3 to 500 mu m. Such a positive electrode current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the battery. Examples of the positive electrode current collector include stainless steel, aluminum, nickel, titanium, sintered carbon, aluminum or stainless steel A surface treated with carbon, nickel, titanium, silver or the like may be used. The current collector may have fine irregularities on the surface thereof to increase the adhesive force of the cathode active material, and various forms such as a film, a sheet, a foil, a net, a porous body, a foam, and a nonwoven fabric are possible.

[Cathode active material]

The cathode active material may be a lithium secondary battery, for example, a layered compound such as lithium cobalt oxide (LiCoO ₂ ) or lithium nickel oxide (LiNiO ₂ ), or a compound substituted with one or more transition metals; Lithium manganese oxides such as Li _{1 + x} Mn _{2 - x} O ₄ (where x is 0 to 0.33), LiMnO ₃ , LiMn ₂ O ₃ and LiMnO ₂ ; Lithium copper oxide (Li ₂ CuO ₂ ); Vanadium oxides such as LiV ₃ O ₈ , LiFe ₃ O ₄ , V ₂ O ₅ and Cu ₂ V ₂ O ₇ ; Formula _{LiNi 1 - x M x O 2} ( where, the M = Co, Mn, Al, Cu, Fe, Mg, B or Ga, x = 0.01 ~ 0.3 Im) Ni site type lithium nickel oxide which is represented by; Formula _{LiMn 2 - x M x O 2} ( where, M = Co, Ni, Fe , Cr, and Zn, or Ta, x = 0.01 ~ 0.1 Im) or Li ₂ Mn ₃ MO ₈ (where, M = Fe, Co, Ni, Cu, or Zn); LiMn ₂ O _{4 in} which a part of Li in the formula is substituted with an alkaline earth metal ion; Disulfide compounds, Fe ₂ (MoO ₄ ) ₃ , and the like, but are not limited thereto.

The conductive material is usually added in an amount of 1 to 50% by weight based on the total weight of the mixture including the cathode active material. Such a conductive material is not particularly limited as long as it has electrical conductivity without causing chemical changes in the battery, for example, graphite such as natural graphite or artificial graphite; Carbon black such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, and summer black; Conductive fibers such as carbon fiber and metal fiber; Metal powders such as carbon fluoride, aluminum, and nickel powder; Conductive whiskey such as zinc oxide and potassium titanate; Conductive metal oxides such as titanium oxide; Conductive materials such as polyphenylene derivatives and the like can be used.

The binder is a component that assists in bonding of the active material and the conductive material and bonding to the current collector, and is usually added in an amount of 1 to 50 wt% based on the total weight of the mixture containing the cathode active material. Examples of such binders include polyvinylidene fluoride, polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene , Polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene butylene rubber, fluorine rubber, various copolymers and the like.

The filler is optionally used as a component for suppressing the expansion of the anode, and is not particularly limited as long as it is a fibrous material without causing a chemical change in the battery. Examples of the filler include olefin polymers such as polyethylene and polypropylene; Fibrous materials such as glass fibers and carbon fibers are used.

Cathode structure

The negative electrode is prepared by applying, drying and pressing an anode active material on an anode current collector, and may optionally further include a conductive material, a binder, a filler, and the like as described above.

[Cathode collector]

The negative electrode current collector is generally made to have a thickness of 3 to 500 mu m. Such an anode current collector is not particularly limited as long as it has electrical conductivity without causing chemical changes in the battery, and examples of the anode current collector include copper, stainless steel, aluminum, nickel, titanium, sintered carbon, a surface of copper or stainless steel A surface treated with carbon, nickel, titanium, silver or the like, an aluminum-cadmium alloy, or the like can be used. In addition, like the positive electrode collector, fine unevenness can be formed on the surface to enhance the bonding force of the negative electrode active material, and it can be used in various forms such as films, sheets, foils, nets, porous bodies, foams and nonwoven fabrics.

[Negative electrode active material]

The negative electrode active material may include, for example, carbon such as non-graphitized carbon or graphite carbon; _{Li x Fe 2 O 3 (0≤x≤1} ), Li x WO 2 (0≤x≤1), Sn x Me 1 - x Me 'y O z (Me: Mn, Fe, Pb, Ge; Me' : Metal complex oxides such as Al, B, P, Si, Group 1, Group 2, Group 3 elements of the periodic table, Halogen, 0 < x &lt; Lithium metal; Lithium alloy; Silicon-based alloys; Tin alloy; _{SnO, SnO 2, PbO, PbO} 2, Pb 2 O 3, Pb 3 O 4, Sb 2 O 3, Sb 2 O 4, Sb 2 O 5, GeO, GeO 2, Bi 2 O 3, Bi 2 O 4, and Bi ₂ O ₅ ; Conductive polymers such as polyacetylene; Li-Co-Ni-based materials and the like can be used.

[Separation membrane]

The pull cells are placed on a separator sheet having a long length, and then the separator sheet is wound on the overlapped portion. The pull cells are stacked so that the positive and negative electrodes face each other with the separator film interposed therebetween. The separator sheet may have an extended length to wrap the electrode assembly once after winding, and the outermost end of the separator sheet may be heat-sealed or tape-fixed. For example, a heat welding machine or a hot plate is brought into contact with a separator sheet to be finished, so that the separator sheet itself is melted and fixed by heat. This ensures stable interfacial contact between the bar electrode and the separator sheet to keep the pressure constant.

The separation membrane interposed between the anode and the cathode of the separator sheet or cell is not particularly limited as long as it exhibits insulation and has a porous structure capable of moving ions, and the separation membrane and the separation membrane sheet may be the same material or not It is possible.

The separator or separator sheet may be a thin insulating film having high ion permeability and mechanical strength. The separator or separator sheet generally has a pore diameter of 0.01 to 10 mu m, 300 mu m. Examples of the separator or separator sheet include olefin polymers such as polypropylene, which is resistant to chemicals and hydrophobic; A sheet or nonwoven fabric made of glass fiber, polyethylene or the like is used. When a solid electrolyte such as a polymer is used as an electrolyte, the solid electrolyte may also serve as a separation membrane. Preferably, a multilayer film produced by a polyethylene film, a polypropylene film, or a combination of these films, or a film made of polyvinylidene fluoride, polyethylene oxide, polyacrylonitrile, or poly A polyvinylidene fluoride hexafluoropropylene copolymer or the like, or a polymer film for a gel-type polymer electrolyte.

It is preferable that the separation membrane has an adhesive function by heat fusion to form a pull cell or a bi-cell, and the separator sheet does not necessarily have such a function. However, in order to facilitate the winding process, .

In addition, in the present invention, in order to construct a pull cell or a bi-cell, an electrode is disposed in one separator, and the electrode is wound in one direction or wound in a zigzag direction. However, the present invention is not limited thereto. It is also possible to adopt a structure in which a lamination is performed in the form of a stacked layer with a separate separation film interposed between the electrodes.

The secondary battery according to the present invention can be applied not only to a middle- or large-sized battery module having a unit battery, but also to a battery pack including a battery module, including 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; An e-scooter; Electric golf cart; Electric truck; And an electric commercial vehicle.

The middle- or large-sized battery module is configured to provide a large-capacity large-capacity battery by connecting a plurality of unit cells in a serial manner or a serial / parallel manner, which is well known in the art and thus will not be described herein.

In the foregoing detailed description of the present invention, specific examples have been described. However, various modifications are possible within the scope of the present invention. The technical idea of the present invention should not be limited to the embodiments of the present invention but should be determined by the equivalents of the claims and the claims.

110: first sheet
120: second sheet
121: outer resin layer
122: metal layer
123: internal resin layer
124: auxiliary resin layer
130: electrode assembly
X: receptacle
Y: sealing part
A, B:

Claims (16)

A first sheet and a second sheet including a metal layer and a polymer layer and an electrode assembly between the first sheet and the second sheet facing each other;
A pulse type molding step of forming an accommodation space by molding an outer periphery of the region where the electrode assembly of the first sheet or the second sheet is accommodated by applying a heating condition and a cooling condition; And
And a sealing step of injecting an electrolytic solution into the accommodation space and forming a sealing part on an outer periphery of the first sheet and the second sheet,
Wherein the density of the polymer layer forming the side surface of the accommodation space portion is in the range of 0.7 to 0.9 of the sealing density.
The method according to claim 1,
In the pulse-type molding step,
Wherein the heating condition is a step of forming the first sheet or the second sheet by heating the temperature of the mold to 60 to 200 占 폚.
The method of claim 2,
In the pulse-type molding step,
After the heating condition is performed,
And cooling the first sheet or the second sheet by applying a cooling condition at room temperature to the first sheet or the second sheet.
delete The method according to claim 1,
Wherein the polymer layer
And a mixture of at least one selected from the group consisting of PE, urethane, PET, PI, NY, PP, CPP and fluorine resin.
The method of claim 3,
In the step of applying the cooling condition,
Wherein the temperature of the mold is lowered to 15 ° C to 25 ° C, followed by cooling and compression.
delete A secondary battery produced by the manufacturing method according to any one of claims 1 to 3, and 5 to 6.
delete The method of claim 8,
Wherein the first sheet and the second sheet are stacked,
Wherein at least two polymer layers are provided on one surface of the metal layer or on the other surface opposite to the one surface.
The method of claim 10,
The polymer layer, which is in contact with the metal layer of the polymer layer,
Wherein the second polymer layer is formed of a material having a higher melting point than the other polymer layers.
The method of claim 11,
The polymer layer, which is in contact with the metal layer of the polymer layer,
And a melting point higher than that of the other polymer layer by 20 占 폚 to 30 占 폚.
The method of claim 10,
Wherein the polymer layer has a total thickness within a range of 20 to 100 mu m.
The method of claim 8,
Wherein the electrode assembly comprises one of a winding type, a stack type, and a stack / folding type structure.
The method of claim 10,
The metal layer may include,
An alloy of iron (Fe), carbon (C), chromium (Cr) and manganese (Mn), an alloy of iron (Fe), carbon (C), chromium (Cr) and nickel (Ni) (Cu) or an equivalent thereof.
A middle- or large-sized battery module comprising a secondary battery according to claim 8 as a unit battery.

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