KR20170089206A - Manufacturing Apparatus for Battery Case Capable of Mounting Electrode Assembly of High Capacity Therein - Google Patents

Abstract

The present invention provides an apparatus for manufacturing a battery case for a secondary battery, which comprises: a fixing jig having an opening formed in a shape corresponding to the receiving portion on the plane and configured to closely fix the upper surface and the lower surface of a sheet along an outer periphery of the sheet; and a punch for pressing the sheet downward through the opening to form the receiving portion in a state in which the sheet is fixed by the fixing jig, wherein the punch has an elongation expanding part having a relatively low surface friction coefficient on at least one surface in close contact with the sheet to prevent cracks from being generated due to frictional force with respect to the sheet upon downward pressurization.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an apparatus for manufacturing a battery case capable of accommodating a large-

The present invention relates to an apparatus for manufacturing a battery case capable of accommodating a large-capacity electrode assembly.

2. Description of the Related Art [0002] As technology development and demand for mobile devices have increased, the demand for secondary batteries as energy sources has rapidly increased. In particular, lithium secondary batteries having high energy density and discharge voltage among secondary batteries have been researched and commercialized have.

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

Such a secondary battery can be classified into a cylindrical battery cell, a prismatic battery cell, and a pouch-shaped battery cell depending on its shape. Among them, a pouch-type battery cell which can be stacked with a high degree of integration, has a high energy density per unit weight, and is inexpensive and easy to deform is attracting much attention.

The pouch type secondary battery has a structure in which an electrode assembly and an electrolyte are embedded in a storage space formed in the shape of an electrode assembly on a laminate sheet by using a flexible laminate sheet as a battery case.

On the other hand, secondary batteries are being used as energy sources even in small mobile devices or household appliances, where electric power, such as electric cars, hybrid vehicles, and electric power storage devices, are required to be large. Therefore, the demand for a secondary battery of a large capacity is drastically increased as compared with the conventional small capacity secondary battery.

The charge / discharge capacity of the secondary battery is proportional to the width of the electrode plate and the number of the electrode plates, and the thickness of the electrode assembly increases as the width and number of the electrode plates increase.

Correspondingly, the shape of the battery case is also required to have a form of a deep receiving portion so that the electrode assembly having a relatively large thickness can be housed.

Generally, a method is used in which the laminate sheet is stretched to a desired depth by using a punch which presses the sheet downward while the laminate sheet is fixed.

However, due to the limit of ductility of the laminate sheet and the frictional force applied when the punch is pressed, external defects such as pin-holes or cracks are generated on the outer surface of the drawn laminate sheet at a certain depth or more For this reason, there is a problem that it is difficult to form the depth of the receiving part deeply so that the electrode assembly can be accommodated in a large capacity.

Therefore, there is a high need for a battery case manufacturing apparatus which can form the above-described technical problem, that is, the depth of the housing portion can be deepened but does not cause external defects.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems of the prior art and the technical problems required from the past.

Specifically, it is an object of the present invention to provide a battery case manufacturing apparatus which can form a depth of a receiving portion deep, but does not cause external defects based on a low frictional force of a punch with respect to a laminate sheet.

According to an aspect of the present invention,

A battery case manufacturing apparatus for forming a housing portion for mounting a secondary battery electrode assembly on a laminate sheet,

A fixing jig having an opening in a shape corresponding to the accommodating portion in a plan view and configured to closely fix the upper surface and the lower surface of the sheet along the outer periphery of the sheet; And

A punch for pressing the sheet downward through the opening to form a receiving portion in a state where the sheet is fixed by the fixing jig;

And,

Wherein the punch is formed on at least one surface of the sheet, wherein the sheet has a relatively low coefficient of surface friction and is in close contact with a sheet to prevent cracks due to frictional force with the sheet upon downward pressing.

Generally, the frictional force formed in a state in which the laminate sheet and the punch are in close contact acts as a load on the stretched laminate sheet, so that a low ductility is formed in a region where these sheets and the punch are in close contact with each other.

Therefore, when a pressing force stronger than the ductility formed by the frictional force is applied, the sheet is forcibly stretched but a crack is generated on the outer surface.

For this reason, the downward pressing force of the punch must be set to a very limited value, and the depth of the receiving portion is determined by the downward pressing force of the punch, so it should be set within a range where no crack occurs.

Therefore, in the manufacturing apparatus according to the present invention, the punch which is pressed in a state of being in tight contact with the laminate sheet is provided with the stretch expanding portion having a low coefficient of friction, so that the deterioration of the inherent ductility of the laminate sheet is minimized at the portion where the sheet and the punch are in close contact, It is possible to form the depth of the receiving portion relatively deep.

In one specific example of this, the punch includes a first state in which a part of the sheet fixed to the fixing jig is stretched in a pressing direction when the punch is pressed downward, and a second state in which a sheet in close contact with the punch is stretched toward the fixing jig In combination, forming a housing portion;

The stretch extending portion can induce stretching expansion of the sheet by a low frictional resistance against the sheet in the second state.

In order to facilitate understanding of the stretching expansion concept of the laminate sheet, a more detailed description will be given with reference to FIGS. 1, 3 and 4.

Referring to these drawings, in the first state, the laminate sheet 10 fixed to the fixing jig 120 is brought into close contact with the side surface of the punch 110 while being stretched along the pressing direction of the punch 110. In this state, if the pressing of the punch 110 is continued, the punch 110 can be further stretched in the pressing direction from the side surface of the punch 110, which can be stretched to the limit within a range where cracks are not induced.

In the second state, the laminate sheet 10 which is in close contact with the lower surface of the punch 110 is stretched in the direction perpendicular to and opposed to the pressing direction of the punch 110. As described above, And the stretching in the 2-state are mutually combined to form the housing part.

Here, in the second state, the sheet 10 positioned in the direction perpendicular to the pressing force of the punch 110 is stretched in both directions with respect to the center of the sheet 10, which is the region where the stretch is the largest in the laminate sheet 10 Since the area of the punch 110 which is in close contact with the punch 110 is relatively wide, the punch 110 has a lower ductility than the inherent ductility due to the frictional force with respect to the punch 110,

For this reason, it can be understood that the stretching portion 12 in the second state is a portion that is relatively susceptible to cracking, and thus the stretching length in the plane within the range in which cracks are not induced is the stretching length It is difficult to deeply form the depth of the receiving portion in a desired form.

Therefore, in order to deepen the depth of the receiving portion, the stretching length in the second state must be extended. The present invention is characterized in that the stretching expanding portion is in close contact with the sheet portion located in the vertical direction with respect to the pressing force of the punch, So that the generation of cracks is minimized while forming the housing part as deep as possible.

That is, in the present invention, the stretch expander is configured to induce stretch expansion of the sheet by a low frictional resistance to the sheet in the second state, and in the second state, the size of the stretch stretch induced by the stretch extension of the punch The receiving portion can be deeply formed.

In order to accomplish this, the punch includes a punch body having a size and shape corresponding to the receiving portion in a plan view, and the extending portion is formed on the lower surface of the punch body with respect to the pressing direction Lt; / RTI >

The increase in stretch size in the second state may be 1% to 10% of the area of the stretch extensions closely attached to the sheet.

As described above, the stretching expanding portion formed on the lower surface of the punch body can induce stretching expansion of the sheet on a relatively large sheet surface which is perpendicular to the pressing force of the punch. In addition, can do. Therefore, the portion of the sheet whose stretch size is increased in the second state may be the front face of the sheet closely attached to the stretch expanding portion.

The coefficient of friction of the extension portion for the sheet in the second state may be determined depending on the material of the extension portion and the material of the sheet adhered thereto. In order to derive the increase in the extension amount with respect to the area of the extension portion, The coefficient may be 0.01 to 0.05, which may be a dry friction coefficient.

The material constituting the stretching extender may be a polymer resin having a low coefficient of friction so that the stretch extender has a low coefficient of friction. Specifically, the material may be a teflon resin having a friction coefficient of 0.03 to 0.04. On the other hand, the material of the punch body may be a metal such as stainless steel.

In the present invention, the fixing jig includes: a die having an opening or a depressed portion in a shape corresponding to the receiving portion in a plan view and supporting the outer periphery of the lower surface of the sheet; And

A stripper having a through hole into which the punch can be introduced and pressing the outer periphery of the upper surface of the sheet to fix the die in close contact with the die;

.

Such a structure allows the punch to induce more precise sheet stretching because the stripper and the die press the sheet firmly in opposite directions to each other.

Meanwhile, in order to more smoothly perform drawing of the sheet, the present invention can have various structures as follows.

As an example, the edges of the elongate extension may be rounded. As another example, the elongate extension may be a structure in which chamfered corners are formed.

These shapes have a large area in which the contact area with the sheet is in contact with the sheet as compared with the vertex-shaped edge where the points are concentrated. Thus, when the punch exerts a force on the sheet with the same force, the punch makes more contact with the sheet than the vertex. Since the pressure is in inverse proportion to the width of the contact area when the force is the same, the above-mentioned shapes apply a little pressure to the sheet as compared with the vertex. For this reason, even if a deep housing part is formed in the laminate sheet, Can be prevented.

In the present invention, the laminate sheet means a sheet composed of an upper layer of a polymer resin, an intermediate layer of a barrier metal, and a lower layer of a polymer resin.

The upper layer of the polymer resin is a resin layer forming the outer surface of the battery case, and is required to have a tensile strength and weather resistance of not less than a predetermined value so as to have excellent resistance to the external environment. In this respect, polyethylene terephthalate (PET) and stretched nylon film may be used as the polymer resin of the resin outer layer.

The lower layer of the polymer resin may preferably be a polyolefin resin having a low heat absorbability (thermal adhesiveness) and low hygroscopicity in order to inhibit the penetration of an electrolyte solution, and which is not swollen or eroded by an electrolytic solution.

Aluminum may be used as the intermediate layer of the barrier metal so as to exhibit a function of improving the strength of the cell case in addition to the function of preventing the inflow or outflow of foreign substances such as gas, moisture and the like.

The present invention also provides a method of manufacturing a battery case using the above manufacturing apparatus,

(i) fixing and fixing a laminate sheet to a fixing jig;

(ii) pressing the sheet downward by a punch through the opening of the fixing jig to form a receiving portion; And

(iii) cutting the sheet having the housing part formed thereon and processing the sheet into a shape of a battery case.

Here, in step (ii), the pressing of the sheet may be performed one time or two or more times, and in detail, it may be performed twice so that the receiving part is formed by the first and second stepwise pressing methods.

The method of pressing the laminate stepwise in this manner can prevent wrinkles and creases from forming on the inner or outer surface of the sheet while partially dispersing and alleviating the stress inherent in the laminate sheet, .

The present invention also provides a battery case manufactured by the above method, wherein the battery case is sealed with the electrode assembly and the electrolyte sealed therein.

As described above, in the manufacturing apparatus according to the present invention, the punch which is pressed in a state of being closely attached to the laminate sheet is provided with a stretchable extension portion having a low coefficient of friction. In the region where the sheet and the punch are in close contact, It is possible to form the depth of the receiving portion relatively deep while suppressing the generation of cracks.

1 is a plan view of a manufacturing apparatus according to one embodiment of the present invention;
2 is a schematic view of a fixing jig;
Figs. 3 and 4 are schematic diagrams showing a process of forming a storage portion in a laminate sheet by the manufacturing apparatus of Fig. 1. Fig.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings, but the present invention is not limited by the scope of the present invention.

FIG. 1 is a plan view of a manufacturing apparatus according to one embodiment of the present invention, and FIG. 2 is a schematic view of a fixing jig.

Referring to these drawings, the manufacturing apparatus 100 is provided with a punch 110 for pressing the laminate sheet 10 and an opening 126 for introducing the punch 110 and for fixing the laminate sheet 10 And includes a fixing jig 120.

The fixing jig 120 is provided with an opening having a shape corresponding to the receiving portion in a plan view and includes a die 122 for supporting the outer periphery 14 of the lower surface of the sheet 10 and a die 122 for receiving the punch 110 And a stripper 124 having a through hole and pressing the outer periphery 14 of the upper surface of the sheet 10 and fixing it to the die 122 tightly.

In this structure, the stripper 124 and the die 122 can press and fix the sheet 10 in mutually opposite directions, and in such a fixed state, the punch 110 is pushed by the through-hole of the stripper 124 and the die 122 , The laminate sheet 10 can be pressed downward.

The punch 110 includes a main body of a punch 110 having a size and a shape corresponding to the receiving part in a plan view and the extending extension part 112 formed on the lower surface of the main body of the punch 110 with reference to the pressing direction do.

The stretch expanding section 112 is a Teflon resin having a very low frictional coefficient of 0.03 to 0.04, and is a mold designed integrally with the main body.

Fig. 3 and Fig. 4 schematically show a step of forming a storage portion in a laminate sheet by the manufacturing apparatus of Fig.

3, when the punch 110 is pressed downward, the laminate sheet 10 is stretched in the pressing direction of the punch 110 from the outer periphery 14 of the sheet 10 fixed to the fixing jig 120, do. This is defined as the first state.

In this first state, the periphery 14 of the sheet 10 fixed to the fixing jig 120 is stretched along the pressing direction of the punch 110 and is brought into close contact with the side surface of the punch 110. In this state, 110 may continue to be downwardly extended from the side of the punch 110 as long as the pressurization of the punch 110 continues, which can be stretched to the limit within a range where cracks are not induced.

At the same time, as the punch 110 is pressed downward, the central portion 12 of the sheet 10 exposed through the opening of the fixing jig 120 is stretched in a state of being in close contact with the outer surface of the punch 110, The laminate sheet 10 is stretched in the direction of the fixing jig 120 along the outer surface of the punch 110 opposing the downward pressing of the punch 110. [ This is defined as the second state.

Specifically, in the second state, the sheet 10 positioned in a direction perpendicular to the pressing force of the punch 110 is extended in both directions from its central portion 12, and is moved along the outer surface of the punch 110, Direction.

In this way, in the first state, the sheet 10 is pulled down from the outer periphery 14, which is the end portion thereof, in accordance with the pushing of the punch 110 and at the same time, from the central portion 12 of the sheet 10 in the second state, ), The sum of the total lengths of the stretched portions becomes the depth of the receiving portion. Hereinafter, for convenience of description, the degree of drawing of the sheet 10 is described as a length on a plane, and the drawing of the sheet 10 in three dimensions is a concept of an area.

Since the central portion 12 of the sheet 10 stretched in the second state is stretched in both directions on the basis thereof, the stretch degree of the laminate sheet 10 is the largest, but the area adhered to the punch 110 is relatively wide Therefore, a low ductility is formed due to the frictional force with respect to the punch 110, and the most load is concentrated at the time of drawing.

Therefore, the maximum stretchable length with respect to the plane is canceled by the frictional force with respect to the punch 110, and the length of the stretch is substantially shortened. For this reason, cracking can be caused during forced stretching.

Therefore, the pressing of the punch 110 can proceed primarily to the first depth h at which cracking is not induced, based on the use of the general metal punch 110. [ Such a first depth h is a depth of a conventional storage portion, and the manufacturing apparatus 100 of the present invention can form the depth of the storage portion deeper than the first depth h through the following configuration.

Specifically, the stretch expanding portion 112 formed on the punch 110 is in close contact with a central portion 12 and a side portion of the sheet 10 positioned in a direction perpendicular to the pressing force of the punch 110, The low frictional force of the sheet 112 increases the elongation length of the sheet 10 in the relatively second state while decreasing the degree to which the maximum stretchable length of the central portion 12 is canceled by the frictional force.

Therefore, even if the sheet 10 is further pressed down below the limit depth h, the punch 110 does not cause cracks on the outer surface of the sheet 10, and the depth of the receiving portion is increased by the stretching length of the increased sheet 10 And a second depth (H) that is deeper than the first depth (h).

As described above, in the manufacturing apparatus 100 according to the present invention, the punch 110 which is pressed in a state of being in tight contact with the laminate sheet 10 is provided with the stretch expanding section 112 having a low coefficient of friction, 10 and the punch 110 are minimized, the occurrence of cracks can be suppressed, and the depth of the receiving portion can be relatively deep.

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.

Claims (16)

A battery case manufacturing apparatus for forming a housing portion for mounting a secondary battery electrode assembly on a laminate sheet,
A fixing jig having an opening in a shape corresponding to the accommodating portion in a plan view and configured to closely fix the upper surface and the lower surface of the sheet along the outer periphery of the sheet; And
A punch for pressing the sheet downward through the opening to form a receiving portion in a state where the sheet is fixed by the fixing jig;
And,
Characterized in that the punch is formed on at least one surface of which a stretch expanding section having a relatively low coefficient of surface friction is brought into close contact with a sheet so as to prevent the occurrence of a crack due to the frictional force to the sheet upon downward pressing, . 2. The punch of claim 1,
A holding portion is formed by a combination of a first state in which a part of the sheet fixed to the fixing jig is stretched in the pressing direction and a second state in which the sheet in close contact with the punch is extended toward the fixing jig;
Wherein said elongate extension extends the elongated extension of the sheet by a low frictional resistance against the sheet in the second state. 3. The manufacturing apparatus according to claim 2, wherein the receiving portion is deeply formed by a size of the stretching extension derived by the stretching extending portion of the punch in the second state. The punch according to claim 2, wherein the punch includes a punch body having a size and shape corresponding to the receiving portion in a plan view, the extending portion is formed on a lower surface of the punch body with respect to a pressing direction,
Wherein the increment of the stretch size in the second state is 1% to 10% of the area of the stretch extensions closely attached to the sheet. 3. The manufacturing apparatus according to claim 2, wherein a portion of the sheet whose stretch size is increased in the second state is a front surface of the sheet adhered to the stretch expanding portion. 3. The manufacturing apparatus according to claim 2, wherein the coefficient of friction of the extension portion for the sheet in the second state is 0.1 to 0.4. The manufacturing apparatus according to claim 4, wherein the material of the punch body is a metal, and the material of the extension portion is a polymer resin. The manufacturing apparatus according to claim 7, wherein the polymer resin is a teflon resin. The manufacturing apparatus according to claim 3, wherein the edges of the elongated extension portion are rounded. [4] The apparatus of claim 3, wherein the elongated extension portion has a chamfered shape. The manufacturing apparatus according to claim 1, wherein the laminate sheet comprises an upper layer of a polymer resin, an intermediate layer of a barrier metal, and a lower layer of a polymer resin. 2. The apparatus according to claim 1,
A die having an opening or indentation of a shape corresponding to the accommodating portion in a plan view and supporting the outer periphery of the seat bottom; And
A stripper in which a through hole through which a punch can be introduced is formed and which presses the outer periphery of the upper surface of the sheet and fixes it to the die;
Wherein the first and second substrates are bonded to each other. 13. A method of manufacturing a battery case using the manufacturing apparatus according to any one of claims 1 to 12,
(i) fixing and fixing a laminate sheet to a fixing jig;
(ii) pressing the sheet downward by a punch through the opening of the fixing jig to form a receiving portion; And
(iii) cutting the sheet having the housing portion formed therein and processing it into the form of a battery case;
≪ / RTI > 14. The method according to claim 13, wherein the pressing of the sheet in the step (ii) is performed once, or two or more times. A battery case made by the method according to claim 13. The secondary battery according to claim 13, wherein the battery case is sealed with the electrode assembly and the electrolyte contained therein.

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