KR101812574B1 - Curved-shaped Electrode Stack Having Elastic Restoring Force And Battery Cell Comprising The Same - Google Patents

Abstract

The present invention relates to an electrode laminate comprising at least one anode, at least one cathode, and at least one separator, wherein the anode, the cathode and the separator are stacked such that a separator is interposed between the anode and the cathode, Characterized in that the laminate surface comprises at least one curved surface portion and at least one current collector of the anode and the cathode comprises a core sheet having an elastic restoring force against deformation And a battery cell comprising the same.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an electrode stacked body having an elastic restoring force and a battery cell including the electrode stacked body.

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an electrode laminate constituting a lithium secondary battery, and more particularly, to a bent electrode laminate having an elastic restoring force.

As information technology (IT) technology has developed remarkably, various portable information and communication devices have been spreading, so that the 21st century is being developed into a "ubiquitous society" capable of providing high quality information services regardless of time and place.

As a development base for such a ubiquitous society, a lithium secondary battery occupies an important position. 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.

In such a secondary battery, since electronic devices are becoming smaller and thinner depending on the taste of the consumer, the shape of the battery is also required to be reduced in size and thickness in order to minimize unnecessary space waste. Therefore, it is necessary to realize various shapes of the battery according to the shape of the device and efficiently utilize the inner space of the device.

In particular, in recent years, since the design of the device itself is a very important factor in the selection of the product of the consumer, various designs are being designed by avoiding the planar design considering the productivity and the like. For example, a device such as a mobile phone, a notebook, or the like can be designed with a predetermined curved surface for an ergonomic design.

As described above, many designs having a curved surface formed on the outer surface have been developed and put into practical use. However, since most of the commercialized batteries are flat, unnecessary space is wasted and it is difficult to stably install the battery There is a problem that the battery may be damaged due to external impact.

Therefore, when a curved surface is formed at a position where a battery is to be mounted in a device in which a curved surface is formed, a battery having a curved portion and being bent so that the device can be stably mounted on such a device is being developed.

Fig. 1 shows a schematic diagram of a stacked electrode laminate having a shape curved along an imaginary line segment X'-X '', as an example. 1 shows a structure in which one positive electrode plate 11 formed with positive electrode tabs 11a, one separator 12 and one negative electrode plate 13 formed with negative electrode tabs 13a are stacked However, the electrode stack 10 may include a plurality of positive electrodes, a plurality of separators, and a plurality of negative plates.

However, in such a bent electrode stack, since the active materials repeatedly expand and contract during the charging / discharging process of the secondary battery due to the external pressure, the bending state can not be maintained, There is a problem that it receives a lot of force and penetrates the separator to cause a short circuit.

Therefore, there is a great need for a bent electrode laminate capable of solving the above problems and reducing the possibility of short circuit by maintaining a bending state.

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.

The inventors of the present application have conducted intensive research and various experiments and have found that when a current collector including a core sheet having elastic restoring force against deformation is used for an anode and / or an anode, it is possible to maintain a bending state at a desired specific temperature The present invention has been accomplished on the basis of confirming that it is possible to solve the problems of the prior art such as an increase in the risk of short circuit.

Therefore, the electrode stacked body according to the present invention comprises at least one anode, at least one cathode, and at least one separator, and the anode, cathode and separator are laminated so that a separator is interposed between the anode and the cathode Wherein at least one of the anode and the cathode has a laminated surface of an electrically conductive core sheet having an elastic restoring force against deformation, and a laminated surface of the anode, the cathode and the separator comprises at least one curved surface portion, sheet.

At this time, the core sheet may have a structure in which two or more different metal materials are heterogeneously bonded.

Thus, when two or more different metal materials are used as the constitution of the current collector, the difference in properties of the metal materials, for example, a difference in ductility, that is, a difference in expansion coefficient, Therefore, even if the current collector of the warped shape is deformed by repetition of external pressure or expansion and contraction because the cell including the electrode stacking material can have an elastic restoring force against deformation at a certain temperature, The deformed range of the electrode is restored to its original shape by the bent shape. As a result, the end of the electrode plates is pressed by the cell case due to the deformation of the electrode, thereby causing a short circuit through the separator.

At this time, the metal materials of the respective layers which are heterojunctionally bonded can be selected corresponding to the degree of warpage desired depending on the temperature at which the device including the electrode laminate is to be used, for example, copper, stainless steel, aluminum , Nickel, titanium, sintered carbon; Aluminum, stainless steel, surface-treated with carbon, nickel, titanium, or silver; And an aluminum-cadmium alloy.

The specific configuration of the core sheet is not particularly limited as long as it has an elastic restoring force in a warped shape due to a difference in properties. In one example, a first metal sheet made of a first metal and a second metal sheet A first metal sheet made of a first metal, and a second metal sheet made of a second metal, wherein the first metal sheet is made of a first metal and the second metal sheet is different from the first metal sheet. Lt; RTI ID = 0.0 > a < / RTI > second metal strip.

When the core sheet includes a second metal strip, the second metal strip may have a bonding direction so as to maintain a curved shape due to the difference in properties, and more specifically, have.

Also, the modulus of elasticity of the second metal strip may be between 110% and 500% of the elastic modulus of the first metal sheet. When the modulus of elasticity of the second metal strip is less than 110%, the difference from the first metal sheet is small and it is difficult to have elastic restoring force capable of maintaining the warped shape by only the strip shape. Conversely, when the elastic modulus exceeds 500% The difference is so large that the shape of the core sheet itself may be distorted, so that it is difficult to maintain the bonding, which is not preferable.

The second metal sheet or the second metal strip may be produced by subjecting the surface of the first metal sheet to a plasma activating surface treatment, then laminating and bonding the first metal sheet to the first metal sheet and performing rolling.

In addition, such a core sheet may be plated with a third metal to have an effective cell performance.

Specifically, plating with the third metal may be determined depending on whether the core sheet is contained in the positive electrode collector or the negative electrode collector. In one example, when the core sheet is included in the positive electrode collector, The third metal may be aluminum, and when the core sheet is included in the negative electrode collector, the third metal may be copper or nickel.

This is because the positive electrode active material used for the anode differs from the negative electrode active material used for the negative electrode, and the metal having an effective cell performance differs depending on the type thereof.

On the other hand, in general, when a plurality of electrode stacks are manufactured so that the curved surface portion has a value smaller than a predetermined radius of curvature, the inner deformation amount is relatively larger than the outer deformation amount, . However, when two metal materials of different properties are bonded to each other as a current collector as in the present invention, the warping of the current collector itself is caused by the difference in properties of the metal. Therefore, And may have a small radius of curvature (R).

Therefore, the at least one curved portion formed on the laminated surface of the electrode stacked body may have a radius of curvature (R) of 500 mm or less, more specifically, 20 mm to 300 mm.

However, if the radius of curvature is too small, stress may concentrate in the central portion of the battery cell, causing deformation such as distortion. On the contrary, if the radius of curvature is smaller than the radius of curvature If it is too large, it is difficult to control the radius of curvature and it is easy to return to a flat state again.

On the other hand, the electrode laminate may include at least one non-curved surface portion, and the non-curved portion may exist on the side of the laminate or the electrode laminate which is not parallel to the laminate . In this case, the side surface means a surface perpendicular to the laminated surface.

In the case where the electrode stack includes two non-curved portions, both the positive electrode terminal and the negative electrode terminal may be located on one non-curved surface, and the positive electrode terminal And the negative electrode terminal may be formed on the other non-curved surface,

The type of the electrode laminate is not particularly limited, but the jelly roll type may be of the stacked type or stacked and folded type because the direction of warping is limited in the winding direction or difficult to manufacture itself. Details of the stacked and folded 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 Are incorporated into the present invention.

The present invention also provides a battery cell in which the electrode laminate is embedded in a battery case together with a non-aqueous electrolyte.

In the present invention, the battery case may be a pouch-shaped battery case of a laminated sheet including a metal can or a metal layer and a resin layer, and it is preferable that the battery case has variable characteristics so that the electrode laminate can be easily bent Specifically, a pouch-type battery case.

The laminate sheet may preferably have a structure in which a resin outer layer having excellent durability is attached to one surface (outer surface) of the metal barrier layer and a thermally fusible resin sealant layer is added to the other surface (inner surface).

Since the resin outer layer has excellent resistance from the external environment, it is necessary to have a tensile strength and weather resistance of a predetermined level or higher. In this respect, polyethylene terephthalate (PET) and stretched nylon film can be preferably used as the polymer resin of the resin outer layer.

The metal barrier layer may preferably be made of aluminum so as to exhibit a function of improving the strength of the battery case, in addition to a function of preventing foreign matter such as gas or moisture from leaking or leaking.

As the polymer resin of the resin sealant layer, a polyolefin resin having a low heat absorbing property (heat adhesion property) and low hygroscopicity in order to suppress penetration of an electrolyte solution and not being swollen or eroded by an electrolytic solution is preferably used And more preferably unleaded polypropylene (CPP) can be used.

In general, a polyolefin resin such as polypropylene has a low adhesive force with a metal. Therefore, as an approach for improving the adhesion with the metal barrier layer, it is preferable to further include an adhesive layer between the metal layer and the resin sealant layer, And blocking characteristics can be improved. Examples of the material of the adhesive layer include a urethane-based material, an acryl-based material, a composition containing a thermoplastic elastomer, and the like, but are not limited thereto.

The battery cell may be a lithium ion polymer battery or a lithium ion battery or a lithium polymer battery.

The present invention also provides a battery pack including the battery cell and the protection circuit module (PCM), and provides the device including the battery pack. At this time, the protection circuit module is connected to the electrode terminal of the battery cell.

The device is not limited as long as the battery cell or the battery pack can be used as a power source. For example, the device may be a smart phone with a curved shape, a cellular phone with a curved shape, a notebook with a curved shape, a tablet PC with a curved shape, A clock, a warped television, a curved shape, and the like.

The battery cell, the battery pack, and other components and the manufacturing method of the device are well known in the art, and a detailed description thereof will be omitted herein.

According to the present invention, a current collector including a core sheet having elastic restoring force against deformation is used for the positive electrode and / or the negative electrode to constitute a bent electrode laminate, It is possible to minimize the unnecessary waste of space, and it is possible to develop a device having various designs according to the taste of the consumer, and it is also possible to configure to maintain a desired bending state at a specific temperature There is an effect of solving the short circuit problem.

Brief Description of the Drawings Fig. 1 is a schematic diagram of a stacked electrode stacked body in a bent shape; Fig.
2 is a schematic diagram of a bent electrode stack according to one embodiment of the present invention;
3 is a schematic view of an electrode including a core sheet having a structure in which two or more different metal materials are heterogeneously bonded;
4 is a top view of a core sheet having a second metal strip bonded to a first metal sheet;
5 is a side view of the electrode laminate of Fig. 2 showing the curvature radius R of the curved surface portion of the electrode laminate of the present invention.

Hereinafter, the present invention will be described in detail with reference to the drawings according to the embodiments of the present invention, but the scope of the present invention is not limited thereto.

FIG. 2 shows an electrode stack 100 having a shape bent along an imaginary line segment X'-X '' according to an embodiment of the present invention. A structure in which one anode 101, one separator 102 and one cathode 103 are laminated is shown for convenience of explanation. However, the electrode stack 100 may include a plurality of anodes, a plurality of separators, And may include a plurality of cathodes.

2, the electrode stack 100 includes an anode 101, a separator 102, and a cathode 103. The electrode stack 100 includes an anode 101, a separator 102, A curved surface portion is formed on the laminated surface of the substrate 103, and a non-curved surface is formed on the two side surfaces which are not parallel to the laminated surface. One of the two side surfaces is formed with a positive electrode tab 101a and a negative electrode tab 103a, and the positive electrode tab 101a and the negative electrode tab 103a are respectively formed with a positive electrode lead (not shown), a negative electrode lead (Not shown) to form a positive electrode terminal and a negative electrode terminal.

As described above, the battery cell including the electrode stacked body in which the predetermined curved surface portion is formed on the laminated surface of the electrode stacked body is mounted in a device having a design with various curved surfaces such as a cellular phone, so that the inner space can be efficiently used, A device with a close contact structure can be manufactured. In addition, it is possible to develop devices having various designs according to consumers' preferences, thereby ultimately contributing to diversification of products.

FIG. 3 is an enlarged view of an electrode 200 in a side view of a curved electrode laminate according to an embodiment of the present invention. Referring to FIG.

Specifically, the electrode 200 of FIG. 3 has a structure in which the electrode material 220 is coated on the core sheet 210 having a structure in which two or more different metal materials are heterogeneously bonded so as to have a curved shape. Needless to say, the core sheet 210 may be plated with a third metal, although not separately shown.

The specific structure of the heterojunction is not limited to a structure including a first metal sheet made of a first metal and a second metal sheet made of a second metal and differentially bonded to the first metal sheet, The metal sheet may be entirely bonded to the first metal sheet, but may include a first metal sheet made of a first metal and at least one second metal strip made of a second metal and differentially bonded to the first metal sheet The second metal strip may be partially bonded to the first metal sheet.

Therefore, FIG. 4 shows a top view of the core sheet 210 having the second metal strip 212 bonded on the first metal sheet 211. The top view of the core sheet in which the second metal sheet is entirely bonded on the first metal sheet is not described separately because it is represented only by the second metal sheet.

Referring to FIG. 4, the second metal strips 212 are bonded in a longitudinal direction on the first metal sheet 211 at regular intervals. However, the structure of the core sheet 210 of FIG. 4 is only one example, and the present invention is not limited to such a structure.

Fig. 5 schematically shows a side view of the electrode laminate 100 of Fig. 2 for indicating the radius of curvature R of the curved portion of the electrode laminate.

5, the electrode stack 100 is bent so as to have a predetermined radius of curvature R, and the radius of curvature R is 500 mm or less, more specifically, 20 mm to 300 mm, mm. < / RTI >

Generally, when a plurality of electrode stacks are manufactured so that the curved surface portion has a value smaller than or equal to a predetermined radius of curvature, the inner deformation amount is relatively larger than the outer deformation amount, so that it can not maintain the warped state and tends to return to a flat state . However, as in the present invention, when two metal materials of different properties are bonded to each other so as to have an elastic restoring force and used as a current collector, it is necessary to have a smaller radius of curvature R And can be applied to many products having various curvature radii (R)

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 (24)

A cathode, and a separator, wherein the anode, the cathode, and the separator are stacked such that a separator is interposed between the anode and the cathode,
The laminated surface of the anode, the cathode and the separator includes at least one curved surface portion,
Wherein at least one current collector of the positive electrode and the negative electrode includes an electrically conductive core sheet having an elastic restoring force against deformation,
Wherein the core sheet has a structure in which two or more different metal materials are heterogeneously bonded. delete The method of claim 1,
Copper, stainless steel, aluminum, nickel, titanium, sintered carbon;
Aluminum, stainless steel, surface-treated with carbon, nickel, titanium, or silver; And
Aluminum-cadmium alloy. ≪ RTI ID = 0.0 > 11. < / RTI > The electrode sheet according to claim 1, wherein the core sheet comprises: a first metal sheet made of a first metal; and a second metal sheet made of a second metal and differentially bonded to the first metal sheet sieve. The method according to claim 1, wherein the core sheet comprises a first metal sheet made of a first metal, and at least one second metal strip made of a second metal and differentially bonded to the first metal sheet . The electrode laminate according to claim 5, wherein the at least one second metal strip is hetero-bonded in the major axis direction of the first metal sheet. The electrode laminate according to claim 1, wherein the core sheet is plated with a third metal. The electrode laminate according to claim 7, wherein the core sheet is contained in the positive electrode collector and the third metal is aluminum. The electrode laminate according to claim 7, wherein the core sheet is contained in an anode current collector, and the third metal is copper or nickel. The electrode laminate according to claim 1, wherein a radius of curvature (R) of the curved surface portion is 500 mm or less. The electrode laminate according to claim 10, wherein a radius of curvature (R) of the curved surface portion is 20 mm to 300 mm. 2. The electrode stack of claim 1, wherein the electrode stack comprises at least one non-curved surface portion. The electrode laminate according to claim 1, wherein the side surface of the electrode laminate which is not parallel to the laminate surface comprises at least one non-curved surface portion. 13. The electrode laminate according to claim 12, wherein the electrode terminal is located on the non-curved surface portion. 15. The electrode laminate according to claim 14, comprising two non-curved portions, wherein both the positive electrode terminal and the negative electrode terminal are located on one non-curved portion. 15. The electrode laminate according to claim 14, comprising two non-curved portions, wherein the positive electrode terminal is located on one non-curved surface portion and the negative electrode terminal is located on the other non-curved surface portion. The battery cell according to any one of claims 1 to 16, wherein the electrode laminate is embedded in the battery case together with the non-aqueous electrolyte. 18. The battery cell according to claim 17, wherein the battery case is a pouch-shaped battery case of a laminate sheet including a metal can or a metal layer and a resin layer. The battery cell of claim 17, wherein the battery cell is a lithium ion polymer battery, a lithium ion battery, or a lithium polymer battery. The battery pack according to claim 17, comprising a battery cell and a protection circuit module (PCM), wherein the protection circuit module is connected to an electrode terminal of the battery cell. A device comprising a battery pack according to claim 20. 22. The device of claim 21, wherein the device is a smart phone, a mobile phone, a notebook, a tablet PC, a watch, a television, a glasses. delete delete

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