KR101688569B1 - Battery Cell Having Step-formed Structure and Method for Checking Insulation Resistance Defects Thereof - Google Patents

Abstract

The present invention relates to a jelly-roll type electrode assembly having an improved structure, and more particularly, to a battery cell in which an electrode assembly having a separator interposed between an anode and a cathode is embedded in a battery case, Two or more electrodes or unit cells having different planar sizes are stacked in a height direction with respect to a plane; Wherein at least one of the upper case and the lower case includes at least one of an upper case and a lower case formed of a laminate sheet of a metal layer and a resin layer, A stepped step is formed; Wherein the battery case is wrapped with an electrically insulating heat shrinkable film in a state in which the electrode assembly is embedded, and a method for checking the insulation resistance failure of the battery cell.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a battery cell including a stepped structure,

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a battery cell having a stepped portion and a method for checking an insulation resistance failure.

An electrode assembly embedded in a battery case of a secondary battery includes a positive electrode, a negative electrode, and a separation membrane structure interposed between the positive electrode and the negative electrode, and is a power generation element capable of charging and discharging. And a stacked type in which a plurality of positive electrodes and negative electrodes of a predetermined size are sequentially stacked with a separator interposed therebetween.

The secondary battery is classified into a cylindrical battery and a prismatic battery in which the electrode assembly is embedded in a cylindrical or rectangular metal can according to the shape of the battery case and the pouch type battery in which the electrode assembly is housed in a pouch case of an aluminum laminate sheet do.

More specifically, the battery case of the laminate sheet structure is composed of an inner sealant layer for sealing, a metal layer for preventing the penetration of the material, and an outer resin layer forming the outermost periphery of the case. The inner sealant layer serves to provide sealing property by mutually heat-sealing by heat and pressure applied while the electrode assembly is embedded, and is mainly composed of CPP (unleaded polypropylene film). The metal layer serves to prevent air, moisture, etc. from flowing into the battery, and mainly aluminum (Al) is used. In addition, since the outer resin layer protects the battery from the outside, excellent tensile strength and weather resistance are required compared to the thickness, and ONy (stretched nylon film) is widely used.

As described above, the laminate sheet used for the battery case or the electronic component case mainly uses aluminum (Al) as the metal layer. Aluminum is preferred as a metal layer material because it has a barrier property against gases and ductility that enables processing in the form of a thin film and is inexpensive. In addition, since the battery case serves to ensure stable operation by sealing the electrode assembly in an insulated state, it is necessary that the metal layer in the laminate sheet of the battery case is maintained in an electrically insulated state.

However, there is a case where the metal layer of the laminate sheet is placed in an electrically connected state with the electrode lead unexpectedly during the process of assembling or using the battery. As a metal layer, aluminum has a large difference in electromotive force from an electrode lead mainly composed of a nickel material. Therefore, when the secondary battery is charged and discharged in such an electrically connected state, corrosion of aluminum proceeds. That is, when the metal layer comes in contact with the electrode lead due to various causes, the insulation resistance is lowered. In such a state, corrosion of the metal layer becomes large and short-circuiting occurs. As a result, the life of the battery is rapidly shortened The safety of the battery is also seriously threatened.

Therefore, there is a demand for a technique that can keep the metal layer of the battery case electrically insulated from the electrode lead.

Further, in order to inspect the insulation state, a technique of measuring the insulation resistance of the secondary battery is required. For example, there is known an insulation inspection method for comparing the voltage between the metal layer at the end of the laminate sheet and the electrode lead, and the voltage between the positive electrode lead and the negative electrode lead.

However, it is difficult to judge whether or not the insulated inspections are normally insulated before inspecting with the inspecting apparatus. Since the inspections are performed using an expensive inspecting apparatus, the manufacturing cost is increased, the manufacturing process of the battery cells becomes very troublesome, So that the manufacturing cost of the battery cell is increased.

Therefore, there is a high need for a technique for simplifying the manufacturing process, shortening the manufacturing time, and easily and safely inspecting the insulation resistance defects that can improve the manufacturing processability.

In recent years, there has been a demand for a new type of battery cell that minimizes dead space due to a slim type or various design trends. It is necessary to reduce the capacity of the battery cell or to change the design of the device to a larger size in order to construct a new structure in consideration of the design of the device to which the battery cell is applied and there is a problem that the battery case must be manufactured according to the shape of the electrode assembly exist.

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 cell having a structure in which a metal layer of a battery case can maintain an electrically insulated state from an electrode lead.

It is still another object of the present invention to provide a method of confirming a failure of an insulation resistance that can easily and accurately determine whether or not a insulation resistance of a battery cell is defective.

It is another object of the present invention to provide a high capacity battery cell structure that minimizes dead space.

According to an aspect of the present invention, there is provided a battery cell in which an electrode assembly having a separator interposed between an anode and a cathode is embedded in a battery case,

Wherein the electrode assembly has a structure in which two or more electrodes or unit cells having different planar sizes are stacked in a height direction with respect to a plane;

Wherein at least one of the upper case and the lower case includes at least one of an upper case and a lower case formed of a laminate sheet of a metal layer and a resin layer, A stepped step is formed;

The battery case has a structure in which the electrode assembly is enclosed in an electrically insulating heat shrinkable film.

That is, due to the above-described structure, the battery cell according to the present invention has a high capacity by increasing the space utilization inside the device in which the battery cell is mounted, and at the same time, Resistance. In addition, whether or not the insulation state is defective can be easily confirmed by the mounting form of the heat shrinkable film.

The two or more unit cells having different plane sizes may be different from each other in at least one of the thickness, the width, and the width of the unit cell. Specifically, when comparing two unit cells among the stacked unit cells, the thickness of the relatively small electrode or unit cell is 20% to 95% of the thickness of the relatively large electrode or unit cell, , Preferably in the range of 30 to 90%.

The unit cell may be a bi-cell having the same type of electrodes located on both sides or a full cell having different types of electrodes located on both sides in a structure in which one or more positive electrodes and one or more negative electrodes are stacked with a separator interposed therebetween.

In one specific example, the unit cells may have a structure in which electrode terminals of the positive electrode and the negative electrode are laminated so as to be arranged at the same position. As an example, the unit cells may be stacked such that the electrode taps of the electrodes forming the unit cells are all located on the same virtual vertical line in the height direction with respect to the plane. This structure facilitates the process of forming the electrode terminal by bonding each electrode tab to one electrode lead in the process of manufacturing the battery cell with the electrode assembly embedded therein.

For example, the unit cells may be stacked in an array in which the size of the unit cells is reduced from the lower portion of the electrode assembly toward the upper portion, so that a stepped step is formed. have.

The upper case and the lower case of the battery case may be a unit or a separate member. In the former case, one end of the upper case may be bent to form the lower case.

In one specific example, the outer circumference of the battery case may include a sealing portion for sealing the battery cell in which the laminate sheet is thermally fused, and a structure in which a cathode terminal and a cathode terminal are formed on one surface including the sealing portion have.

In this structure, the side sealing parts on both sides are bent upward toward the electrode assembly receiving part based on the position of the electrode terminal, and the heat shrinkable film may surround the upwardly bent side sealing parts. Therefore, it is possible to prevent the metal layer of the laminate sheet from being exposed at its sealing end, for example, a phenomenon of being electrically connected to the electrode terminal by an external conductive member. For this reason, it is preferable that the heat-shrinkable film completely surrounds the upwardly bent side sealing portion.

In some cases, the heat shrinkable film may cover the outer circumference of the upper end surface and the outer circumference of the lower end surface of the battery case in which the electrode terminals are located. Specifically, it may be a structure that shrinks to a structure covering the outer periphery of the upper end surface excluding the electrode located at the upper portion of the battery case and the outer periphery of the lower end surface. Such a structure can be realized as a heat-shrinkable film, for example, using a heat-shrinkable tube. Thus, in one specific example, the heat-shrinkable film can be tubular in shape prior to heat shrinking, and in addition to the easy implementation of the structure as described above, such tubular members can have a shape corresponding to the step shape of the battery case during heat shrinkage There is also an effect of tightly contracting properly.

In a preferred example, the heat-shrinkable film may have a color that is contrasted with the color of the battery case. In a specific example, the heat-shrinkable film may have a white, black, or chromatic color. The heat shrinkable film of such a color facilitates identification of the portion of the battery case such as silver or gray covered with the heat shrinkable film. Therefore, in the structure as described above, whether or not the end portion of the side sealing portion bent in the heat-shrinkable film, in particular, the end portion of the metal layer is properly wrapped can be visually judged easily.

The heat-shrinkable film may be shrunk to, for example, 5% to 40% in size compared to the size before heat shrinkage. This size can be set based on the surface area of the film. If the shrinkable size of the heat shrinkable film is too small, the adhesion to the battery case may be deteriorated, and conversely, if the shrinkable size is too large, it may rupture, which is not preferable.

The heat shrinkable film may be made of one or more materials selected from the group consisting of, for example, polyethylene, polypropylene, polyethylene terephthalate (PET) and PVC, but is not limited thereto.

The present invention also provides a method for determining whether an insulation resistance is defective based on the battery cell.

In one specific example, whether or not the sealing end of the laminate sheet of the battery case is exposed to the outside of the heat-shrinkable film can be visually checked, and the case of being exposed can be judged to be defective and the case not exposed can be judged to be normal.

In some cases, when the sealing end of the laminate sheet of the battery case is exposed to the outside, the voltage between the sealing end and the negative electrode terminal of the battery cell is further measured, and if the energization is confirmed, .

The present invention also provides a device comprising the battery cell.

The device may be a notebook, a mobile phone, a PDP, a PMP, an MP3 player, a DSC (Digital Still Camera), a DVR, a smart phone, a GPS system and a camcorder, an electric vehicle, a hybrid electric vehicle, But the present invention is not limited to these.

The structure and manufacturing method of such a device are well known in the art, so a detailed description thereof will be omitted herein.

INDUSTRIAL APPLICABILITY As described above, the battery cell according to the present invention increases the space utilization inside the device in which the battery cell is mounted, provides a high capacity and provides an insulation state to the end portion of the laminate sheet as the battery case, It is possible to easily confirm whether the insulation state is defective or not.

1 is a schematic view of a conventional battery cell;
2 is a perspective view of a battery cell according to an embodiment of the present invention inserted into a tubular heat-shrinkable film;
3 is a cross-sectional view of a battery cell according to one embodiment of the present invention;
4 is a cross-sectional view of a battery cell according to another embodiment of the present invention;
5 is a flowchart showing a method for checking insulation resistance failure of a battery cell according to an embodiment of the present invention.

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 schematically shows a perspective view of a conventional battery cell.

1, the pouch-type secondary battery 10 includes an electrode assembly 30 including an anode, a cathode, and a separator disposed between the anode and the cathode, And two electrode leads 40 and 41 electrically connected to the electrodes 31 and 32 are sealed to be exposed to the outside.

The battery case 20 includes a case body 21 including a concave shaped storage portion 23 on which the electrode assembly 30 can be seated and a cover 22 integrally connected to the body 21 have.

The battery case 20 is formed of a laminate sheet and is composed of an outer resin layer 20a forming an outermost layer, a barrier metal layer 20b for preventing the passage of a substance, and an inner resin layer 20c for sealing .

In the stacked electrode assembly 30, a plurality of positive electrode tabs 31 and a plurality of negative electrode tabs 32 are fused to each other and coupled to the electrode leads 40 and 41. In addition, when the upper end portion 24 of the case body 21 and the upper end portion of the cover 22 are thermally fused by a heat welding machine (not shown), a short circuit occurs between the heat fusion welding machine and the electrode leads 40 and 41 An insulating film 50 is attached to the upper and lower surfaces of the electrode leads 40 and 41 in order to prevent the electrode leads 40 and 41 and ensure the sealing property between the electrode leads 40 and 41 and the battery case 20.

FIG. 2 schematically shows a battery cell according to an embodiment of the present invention inserted into a tubular heat-shrinkable film.

Referring to FIG. 2, a state before the battery case 310 in which the electrode assembly is embedded is inserted into the tubular heat-shrinkable film 350 and is heat-shrunk. The electrode assembly has a plurality of unit cells of different sizes stacked in a height direction with respect to a plane, and the housing portion of the battery case 310 corresponds to an outer shape of a structure in which a plurality of unit cells are stacked, ) Are formed.

The heat-shrinkable film 350 is made of, for example, a color such as red, blue, or black, so that it is distinguished from a silver or gray battery case color. When the heat shrinkable film 350 contracts due to heat, the outer periphery of the upper surface where the electrode leads 330 of the battery case 310 are located is wrapped, and the battery case 310, (310). When heat is applied to the heat-shrinkable film 350, the heat shrinkable film 350 is shrunk to a shape corresponding to the stepped shape as shown in Fig.

3 is a cross-sectional view schematically illustrating a battery cell according to an embodiment of the present invention.

Referring to FIG. 3, the electrode assembly 420 has a stacked structure in which the unit cells 422, 424, and 426 are reduced in planar size from the ground. Specifically, the battery case is composed of an upper case 411 and a lower case 412, and an upper case 411 has an outer surface of a structure in which a plurality of unit cells 422, 424, And a stepped step 414 is formed in correspondence with the shape. Accordingly, the electrode assembly 420 having the stacked unit cells 422, 424, and 426 is housed in the battery case corresponding to the stepped step 414.

The heat-shrinkable film 450 is heat-shrunk so as to surround the battery case corresponding to the shape of the step 414 of the upper case 411 in which the electrode assembly 420 is housed. Specifically, the heat-shrinkable film 450 is heat-shrunk except for the electrode leads 330 to surround the outer periphery 455 of the upper end surface where the electrode leads 330 are located and to face the upper end surface where the electrode leads 330 are located And contracts while surrounding the outer periphery 456 of the lower end face. Since the heat shrinkable film 450 has a chromatic color, a white color, or a black color, whether or not the sealing end of the laminate sheet of the battery case is exposed in a contracted state can be easily determined visually. For example, when the shrinkage of the heat-shrinkable film 450 is completed at a position A where all or a part of the lower side of the heat-shrinkable film 450 does not wrap a part of the lower side of the battery case, the exposed end of the laminate sheet is judged as a difference in color, Can be processed.

4 is a cross-sectional view schematically illustrating a battery cell according to another embodiment of the present invention.

Referring to FIG. 4, the electrode assembly 520 has a laminated structure in which the unit cells 522, 524 and 526 are reduced in size. Specifically, a step 514 is formed in a diagonal direction opposite to the direction in which the electrode lead 530 is positioned. The electrode assembly 520 is accommodated in the upper case 511 in a shape corresponding to the upper case 511. The battery case 510 is composed of an upper case 511 and a lower case 512.

As in the embodiment of FIG. 3, when heat is applied to the heat shrinkable film 550, the heat shrinkable film 550 shrinks in such a shape as to surround the battery case 510 corresponding to the stepped step 514. The heat shrinkable film 550 is thermally shrunk so as to surround the battery case 510 corresponding to the shape of the step 514 of the upper case in which the electrode assembly 520 is housed. Specifically, the heat shrinkable film 550 is heat-shrunk except for the electrode leads 530 to surround the outer periphery 555 of the upper end surface on which the electrode leads 530 are located and to face the upper end surface where the electrode leads 530 are located And is contracted while surrounding the outer periphery 556 of the lower end face. When the shrinkage of the heat-shrinkable film 450 is completed at a position B where all or a part of the lower side of the heat-shrinkable film 450 does not wrap a part of the lower side of the battery case, the exposure of the sealing end of the laminate sheet is judged as a difference in color, .

FIG. 5 is a flow chart schematically illustrating a method for checking the insulation resistance failure according to one embodiment of the present invention.

Referring to FIG. 5, the step of inserting the stepped electrode assembly into the battery case and sealing the heat-shrinkable film with heat (S110) is performed. Next, in a case where the sealing end of the laminate sheet is not exposed through visual inspection (S120) as to whether or not the sealing end of the laminate sheet of the battery case is exposed to the outside of the heat shrinkable film, it is determined as normal (S210). However, when the sealing end of the laminate sheet is exposed, the voltage between the metal layer at the sealing end and the negative electrode terminal of the battery cell is further measured, and if it is confirmed that the power supply is confirmed (S140). In some cases, it may be determined as defective (S140) by checking the energization between the metal layer of the sealing end and the negative electrode terminal of the battery cell through a process (S120) of visually determining the sealing end of the laminate sheet.

Those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Claims (17)

A battery cell in which an electrode assembly having a separator interposed between an anode and a cathode is embedded in a battery case,
Wherein the electrode assembly has a structure in which two or more electrodes or unit cells having different planar sizes are stacked in a height direction with respect to a plane;
Wherein at least one of the upper case and the lower case includes at least one of an upper case and a lower case formed of a laminate sheet of a metal layer and a resin layer, A stepped step is formed;
Wherein the battery case is wrapped with an electrically insulating heat shrinkable film in a state where the electrode assembly is embedded,
Wherein the outer periphery of the battery case includes a sealing portion to which the laminate sheet is thermally fused,
The side sealing portions on both sides of the electrode terminal are bent upward in the direction of the electrode assembly receiving portion, the heat shrinkable film surrounds the upwardly bent side sealing portions,
The heat shrinkable film covers the outer circumference of the upper end surface of the battery case and the outer circumference of the lower end surface of the battery case,
Wherein the heat shrinkable film has a color contrasting with the color of the battery case so that the battery case can be easily visually confirmed on the part covered with the heat shrinkable film. The battery cell according to claim 1, wherein at least two of the unit cells having different planar sizes have different thicknesses, widths (widths) and widths (lengths) of the unit cells. The unit cell according to claim 1, wherein the unit cell has a structure in which one or more positive electrodes and one or more negative electrodes are stacked with a separator interposed therebetween, Wherein the battery cell is another pull cell. The battery cell according to claim 1, wherein the unit cells are stacked such that electrode terminals are arranged at the same position. The battery cell according to claim 1, wherein the unit cells are stacked in an array in which a unit cell is reduced in size from a lower portion to an upper portion of the electrode assembly. delete delete delete delete The battery cell according to claim 1, wherein the heat shrinkable film has a white, black or chromatic color. The battery cell according to claim 1, wherein the heat shrinkable film is a tubular shape before heat shrinkage. The battery cell according to claim 1, wherein the heat shrinkable film is shrunk to 5% to 40% of the size before heat shrinkage. The battery cell according to claim 1, wherein the heat shrinkable film is made of at least one material selected from the group consisting of polyethylene, polypropylene, polyethylene terephthalate (PET), and PVC. A method for confirming whether or not an insulation resistance is defective in a battery cell according to claim 1,
Shrinkable film of the battery case is visually inspected whether or not the sealing end of the laminate sheet of the battery case has been exposed to the outside of the heat shrinkable film to determine that the case where the battery case is exposed is judged to be defective and the case where the case is not exposed is judged to be normal . The method according to claim 14, further comprising the step of, when the battery is exposed, further measuring a voltage between the sealing end and a negative terminal of the battery cell, Way. A device comprising a battery cell according to claim 1. 17. The device of claim 16, wherein the device is a mobile phone, a PDP, a PMP, an MP3 player, a digital still camera (DSC), a DVR, a smart phone, a GPS system, and a camcorder, an electric vehicle, a hybrid electric vehicle, Or a power storage device.

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