KR102429642B1 - Curved electrochemical cell and manufacturing method thereof - Google Patents

Abstract

A curved electrochemical cell according to the present invention includes: an electrode assembly including a plurality of electrodes and electrode tabs formed on the electrodes; a casing formed to accommodate the electrode assembly; and an electrode lead connected to the electrode tab and exposed to the outside of the casing, wherein a radius of curvature at one end of both ends in the longitudinal direction of the casing is greater than a radius of curvature of the other end positioned opposite to the one end in the longitudinal direction. It is bent to have a small value, and N bending areas arranged in parallel in the longitudinal direction are formed on the exterior material (N is a natural number greater than or equal to 2), and the N bending areas are formed from the bending area located on the one end side to the other It is formed so that the radius of curvature and the length are gradually increased toward the bending area located at the end side.

Description

CURVED ELECTROCHEMICAL CELL AND MANUFACTURING METHOD THEREOF

The present invention relates to a curved electrochemical cell capable of charging and discharging, which can be provided as a power source for a mobile device or a wearable device.

An electrochemical cell means a cell that can be provided as a power source by being composed of at least two electrodes and an electrolyte. In particular, a lithium ion battery composed of a secondary cell for charging and discharging is a smart It is widely used in various high-tech electronic devices including phones.

In addition, in recent years, various attempts have been made to break away from the conventional monotonous shape in the design of mobile devices including smartphones, and further, in the design of various wearable devices, curved designs in consideration of ergonomics are attracting attention.

In the design of such mobile and wearable devices, manufacturing an electrochemical cell in a shape that can be embedded in a device having various shapes has become an important technique in that it is possible to alleviate the constraints on the design of a manufacturable device. In addition, it is an important technology in terms of improving device performance and safety by maximizing the use of internal space within a given device design.

In this regard, Patent Document 1, which is a prior art, has disclosed a curved cell bent in a curved shape. However, in the design of such a curved cell, there was a limitation in designing a large degree of curvature (a small radius of curvature) at the end of the cell because the curved state of the cell was released and restored during repeated charging and discharging. In addition, there is a limit to the curved shape that can be manufactured due to the constraints on the end of the cell and the like.

In addition, Patent Document 1 discloses a process of forming a curved shape by pressing the cell completed up to the assembly and sealing steps in a curved frame (mold), but the defective rate is increased due to damage to parts vulnerable to durability by this process There was a problem in the process. Furthermore, the curved cell manufactured by this process has a problem in that, as the degree of bending is increased, wrinkles are formed in the exterior material, thereby increasing the overall thickness, and increasing the possibility of brittle fracture.

US 10-1049841 B1 (2011.07.11. registration)

SUMMARY OF THE INVENTION One object of the present invention is to provide a curved electrochemical cell applicable to wearable devices in various regions, in which the edge side and the opposite edge side for binding and connecting electrode plates in a stacked electrode assembly are bent asymmetrically. .

Another object of the present invention is to provide a curved electrochemical cell capable of variously disposing electrode leads on corners with different radii of curvature by separately separating a corner side for binding an electrode plate and a corner side to which an electrode lead is connected. it is to do

Another object of the present invention is to prevent an increase in thickness due to wrinkling of the casing and cracks and disconnections due to contraction and tension of the electrode assembly by pre-molding the casing to be bent into a predetermined shape before the casing material accommodates the electrode assembly. An object of the present invention is to provide a method for manufacturing a curved electrochemical cell capable of improving productivity, such as suppression.

In order to achieve one object of the present invention, a curved electrochemical cell according to the present invention includes: an electrode assembly including a plurality of electrodes and electrode tabs formed on the electrodes; a casing formed to accommodate the electrode assembly; and an electrode lead connected to the electrode tab and exposed to the outside of the casing, wherein a radius of curvature at one end of both ends in the longitudinal direction of the casing is greater than a radius of curvature of the other end positioned opposite to the one end in the longitudinal direction. It is bent to have a small value, and N bending areas arranged in parallel in the longitudinal direction are formed on the exterior material (N is a natural number greater than or equal to 2), and the N bending areas are formed from the bending area located on the one end side to the other It is formed so that the radius of curvature and the length are gradually increased toward the bending area located at the end side.

In order to achieve another object of the present invention, the electrode tab of the curved electrochemical cell according to the present invention includes: a parallel connection tab formed to connect the plurality of electrodes to each other; and a lead connection tab formed on at least one of the plurality of electrodes and coupled to the electrode lead, wherein the parallel connection tab is formed on a side facing any one of the one direction and the other direction of the exterior material, and another The lead connection tab is formed on a side facing one.

In order to achieve another object of the present invention, there is provided a method for manufacturing a curved electrochemical cell according to the present invention, comprising: manufacturing an electrode assembly by stacking a plurality of electrodes; forming a accommodating part for accommodating the electrode assembly and a curved shape in a case; and accommodating the electrode assembly in the accommodating part of the case molded into the curved shape and sealing the case, wherein in the forming of the accommodating part and the curved shape and sealing the case, the case material is molded and sealed so that the radius of curvature at one end of both ends in the longitudinal direction has a smaller value than the radius of curvature of the other end positioned opposite to the one end, and N bendings arranged in parallel in the longitudinal direction on the exterior material The method further includes forming a region (N is a natural number greater than or equal to 2), wherein in the forming of the N bending regions, the curvature is gradually increased from the bending region located at the one end side to the bending region located at the other end side. It is formed to increase in radius and length.

The curved electrochemical cell according to the present invention is formed to have an asymmetric radius of curvature, and thus can be applied to a wearable device designed to be streamlined or asymmetrically designed according to a body part. Furthermore, stability can be secured by connecting the electrode tab to the end with a large radius of curvature, and the amount of bending at the end with a small radius of curvature can be increased, thereby reducing design constraints of the wearable device.

The curved electrochemical cell according to the present invention is configured by separating the parallel connection tab and the lead connection tab, so that a weak structure can be dispersed or removed and stress concentration can be relieved. Accordingly, the curved electrochemical cell according to the present invention can be manufactured with a smaller radius of curvature. In addition, since the electrode lead can be disposed even at the end having a relatively small radius of curvature compared to the prior art, the degree of freedom in position for disposing the curved electrochemical cell on a curved surface inside the wearable device may be increased.

According to the method for manufacturing a curved electrochemical cell according to the present invention, after the casing is molded into a curved shape, the electrode assembly is accommodated in the casing and sealed in the curved shape. Accordingly, it is possible to prevent wrinkles from remaining on the appearance of the finished curved electrochemical cell. In addition, compared to a method of sealing the electrode assembly in a state in which the exterior material is not molded into a curved shape and then molding it into a curved shape, defects are greatly reduced and cell performance can be stably secured.

1 is a perspective view of a curved electrochemical cell according to an embodiment of the present invention.
FIG. 2 is a view showing an electrode assembly constituting the curved electrochemical cell shown in FIG. 1 .
FIG. 3 is a side view illustrating the curved electrochemical cell shown in FIG. 1 with a bending region.
4 is a perspective view of a curved electrochemical cell according to another embodiment of the present invention.
5 is a perspective view of a curved electrochemical cell according to another embodiment of the present invention.
6 is a view showing an electrode assembly constituting the curved electrochemical cell shown in FIGS. 4 and 5 .
7 is an exploded view of the electrode assembly shown in FIG. 6 .
8 is a view showing examples in which a curved electrochemical cell according to the present invention is mounted on a curved surface inside a wearable device.
9 is a flowchart illustrating a method of manufacturing a curved electrochemical cell according to an embodiment of the present invention.
FIG. 10 is a view specifically illustrating a process of forming the exterior material shown in FIG. 9 into a curved shape.
11 is a flowchart illustrating a method of manufacturing a curved electrochemical cell according to another embodiment of the present invention.
12 is a view specifically illustrating a process of forming the electrochemical cell shown in FIG. 11 into a curved shape.
13 is a table showing the shape and test results of a curved electrochemical cell according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. However, the present invention may be embodied in several different forms and is not limited to the embodiments described herein. And in order to clearly explain the present invention in the drawings, parts irrelevant to the description are omitted, and similar reference numerals are attached to similar parts throughout the specification.

Throughout the specification, when a part "includes" a certain component, it means that other components may be further included, rather than excluding other components, unless otherwise stated. In addition, when it is said that a certain part is "connected" with another part throughout the specification, it is not only directly connected, but also electrically connected through another member in the middle, and another element in the middle. Including connected cases. Furthermore, throughout this specification, when a member is said to be located "on" another member, this includes not only a case in which a member is in contact with another member but also a case in which another member is present between the two members.

The curved electrochemical cell according to the present invention may be a lithium ion battery. Specifically, the electrochemical cell according to the present invention may be configured such that the electrode assembly is accommodated and sealed with an electrolyte inside the casing, and charged and discharged through movement of lithium ions. The curved electrochemical cell according to the present invention is characterized in that it is manufactured in a state in which the exterior material is bent into a predetermined shape. The curved electrochemical cell according to the present invention refers to an electrochemical cell that maintains a curved shape under a condition in which external force due to contact is not applied. The external force due to the contact may be applied after the assembly of the electrochemical cell is completed. Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

1 is a perspective view of a curved electrochemical cell 100 according to an embodiment of the present invention. Also, FIG. 2 is a view showing an electrode assembly constituting the curved electrochemical cell shown in FIG. 1 .

1 and 2 , the curved electrochemical cell 100 according to an embodiment of the present invention includes an electrode assembly 110 , a casing 120 , and an electrode lead 130 . The electrode assembly 110 may include a plurality of electrodes 111a and 111b and one or more ion conductive electronic insulating layers, and may be formed in a structure in which they are stacked.

The electrode may include a first electrode plate 111a and a second electrode plate 111b having different polarities, and the active material is disposed on both surfaces or one end surface of each of the first electrode plate 111a and the second electrode plate 111b. can be applied. An ion conductive electronic insulating layer may be interposed between the first electrode plate 111a and the second electrode plate 111b. The ion conductive electronic insulating layer may be a dendritic porous film or a polymer matrix composite containing an electrolyte. The first electrode plate 111a is a negative electrode, and is a sheet or a fibrous current collector comprising a part or all of a material such as copper, aluminum, nickel, stainless steel, carbon, graphite, lithium titanium oxide, lithium, silicon, silicon. It may be manufactured by applying an active material layer composed of a combination of one or more of a silicon derivative such as an oxide, a silicon-graphite composite, tin, and a silicon-tin composite. In addition, the second electrode plate 111b is a positive electrode, and is a sheet or a fibrous current collector comprising aluminum, nickel, and stainless steel material in part or in whole, lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium cobalt-manganese. oxide, lithium cobalt-nickel oxide, lithium manganese-nickel oxide, lithium cobalt-nickel-manganese oxide, lithium cobalt-nickel-aluminum oxide, lithium iron phosphate oxide have.

The electrode assembly 110, one direction (longitudinal direction) of the two directions in which the electrode forms a surface is longer than the other one (width direction), and intersects (eg, orthogonal) with the direction in which the surface is formed. The electrode and the ion conductive electronic insulating layer may be alternately stacked on each other in the thickness direction.

Also, the electrode assembly 110 includes an electrode tab 113 . The electrode tabs 113 may have a shape protruding from the longitudinal ends of the electrodes, and the electrode tabs 113 formed on electrodes having the same polarity may be coupled to each other. For example, the first electrode tabs 113a formed on the first electrode plate 111a may be coupled to each other, and the second electrode tabs 113b formed on the second electrode plate 111b may be coupled to each other. By the electrode tab 113 , the current collectors may be electrically connected in parallel, and a plurality of electrodes may be structurally coupled to each other at the longitudinal ends. Also, in this embodiment, the electrode tab 113 may be coupled to the electrode lead 130 .

Meanwhile, the exterior material 120 is formed to accommodate the electrode assembly 110 . The exterior material 120 is, for example, a polyolefin-based, polyethylene terephthalate-based, polyamide-based and polyimide-based resin layer and one or two or more metal foil layers such as aluminum, stainless steel, titanium, etc. laminated It may be made of a composite film. have. The exterior material 120 includes a accommodating part 121 in which the electrode assembly 110 is accommodated, and a sealing part 122 formed by bonding at least a portion of edges surrounding the accommodating part 121 to each other, and the sealing part ( 122), the electrode assembly 110 and the electrolyte may be sealed from the outside. As in the present embodiment, the sealing part 122 may be bent with respect to the receiving part 121 .

The electrode lead 130 is connected to the electrode assembly 110 inside the casing 120 and protrudes to the outside through the edge of the casing 120 . The electrode lead 130 functions as a terminal for electrical connection with the electrode assembly 110 accommodated in the exterior material 120 , and is interposed between the exterior material 120 when the sealing part 122 is formed. can be joined together with The electrode tabs 113 provided in the electrode assembly 110 may be respectively coupled to the pair of electrode leads 130 in a state in which the same polarities are bonded to each other.

FIG. 3 is a side view illustrating the curved electrochemical cell 100 shown in FIG. 1 together with a bending region A _n . Hereinafter, the curved shape of the curved electrochemical cell 100 according to an embodiment of the present invention will be described in detail with further reference to FIG. 3 .

In one embodiment of the present invention, the casing 120 accommodating the electrode assembly 110 is characterized in that it has a curved shape. Specifically, the exterior material 120 of the present embodiment may be formed to be bent in a curved shape while extending in the longitudinal direction. In this case, the radius of curvature at one end of both ends in the longitudinal direction of the exterior material 120 may have a smaller value than the radius of curvature at the other end opposite to the end. In addition, in the present embodiment, the electrode tab 113 may be disposed on a side facing the other end of both ends of the casing 120 in the longitudinal direction, that is, a side having a relatively large radius of curvature. The electrode tab 113 may be joined to connect a plurality of electrodes in parallel to each other at the other end of the electrode, and may also be joined to the electrode lead 130 .

The curved electrochemical cell 100 according to an embodiment of the present invention is asymmetrically formed so that both ends in the longitudinal direction have different radii of curvature, so that it can be applied to a wearable device designed to be streamlined and asymmetrically designed according to body parts. . In particular, it is possible to escape from the constraint that the energy density could not be increased because the cell having a symmetrical shape as in the prior patent document 1 and, further, the cell having a large radius of curvature at the end does not efficiently utilize the space.

Furthermore, in the electrochemical cell, the connection portion between the electrode tab and the electrode lead is structurally weak, and thus has a high possibility of breakage, and may be a location with a high tendency to restore its original shape even after being bent. In the curved electrochemical cell 100 according to the present embodiment, since the electrode tab 113 is formed on the end side having a relatively large radius of curvature and is connected to the electrode lead 130, productivity is improved by reducing the defect rate due to breakage. can be improved

In addition, in the curved electrochemical cell 100 according to the present invention, an allowable amount of bending at the end to which the electrode lead is not connected may be increased. That is, the curved electrochemical cell 100 according to the present invention has an advantage in that stable quality can be secured even in a shape with a larger amount of curvature (a state with a smaller radius of curvature) than in the prior art. Accordingly, the curved electrochemical cell 100 according to the present invention can be stably mounted on a wearable device bent along a body part (eg, neck, wrist, etc.) having a small radius of curvature.

Hereinafter, a detailed configuration of a curved shape capable of stably and easily forming an asymmetric radius of curvature in the longitudinal direction will be described.

Referring to FIG. 3 , a plurality of bending regions A _n may be formed in the casing 120 of the curved electrochemical cell 100 according to an embodiment of the present invention. Here, n is a natural number and may have a value of 1 or more and N-1 or less. That is, the N bending regions A _n may be formed in the exterior material 120 in parallel in the longitudinal direction. In this case, N may be a natural number of 2 or more, and for example, five bending regions A ₁ , A ₂ , A ₃ , A ₄ A ₅ may be formed as shown in FIG. 3 .

And, in the curved electrochemical cell 100 according to the present embodiment, the radius of curvature r _n of the n-th bending region A _n from one end of the casing 120 is the n+1-th bending region A _{n +1} ) may be formed to be less than or equal to the radius of curvature (r _n+1 ). Accordingly, as in the present embodiment of FIG. 3 , the radius of curvature r ₁ , r ₂ , r ₃ , r ₄ , r of the five bending areas A ₁ , A ₂ , A ₃ , A ₄ , A ₅ . ₅ ) may be formed to increase sequentially from one end side to the other end side.

In this way, the exterior material 120 is partitioned into a plurality of bending regions (A _n ) in the longitudinal direction and formed such that the radius of curvature between the bending regions (A _n ) is gradually increased, so that the curved electrochemical cell 100 of this embodiment can be smoothly implemented with an asymmetrical curved shape. Accordingly, by evenly distributing the stress accompanying the curved electrochemical cell 100 due to a change in the thickness of the electrode layer during charging and discharging, deformation of the shape during use can be minimized. Furthermore, since it is not necessary to apply excessive force to the electrochemical cell 100 in order to form the curving, there is no risk of damage to the weak portions of the electrode assemblies 110 and 210, thereby ensuring stable and uniform quality.

In addition, the curved electrochemical cell 100 according to the present embodiment may be formed such that the length L _n of the bending region A _n is sequentially increased with the sequential increase in the radius of curvature of the bending region A _n . can That is, as shown in FIG. 3 , the curved electrochemical cell 100 according to the present embodiment has an n+1-th bending region (A _n+1 ) from one end of the casing 120 with respect to one end. ) may be formed such that the length (L _{n + 1} ) is greater than or equal to the length (L _n ) of the n-th bending region A _n from one end (n is a natural number, and 1≤n≤N-1) .

Furthermore, in the curved electrochemical cell 100 according to the present embodiment, the radius of curvature (r _n+1 ) of the n+1-th bending region (A _n+1 ) with respect to one end of the exterior material 120 is The ratio (r _n+2 /r _n+1 ) of the radius of curvature (r _n+2 ) of the n+2th bending area (A _n+2 ) from one end is the radius of curvature of the nth bending area (A _n ) It may be formed to be greater than or equal to a ratio (r _n+1 /r _n ) of a radius of curvature r _n+1 of the n+1-th bending region A _n+1 from one end to (r _n ). . That is, the increase ratio of the radius of curvature of the bending area A _n may increase from one end to the other. In this case, the number of bending regions A _n may be 3 or more.

As described above, by the configuration in which the length of the bending region A _n is increased or the increase rate of the radius of curvature of the bending region A _n is increased, the curved electrochemical cell 100 according to the present embodiment is A gradual change of the radius of curvature in the longitudinal direction may be implemented. Accordingly, the curved electrochemical cell 100 according to the present embodiment is a localized stress generated due to a change in the thickness of the electrochemical cell 100 accompanied by charging and discharging at a specific point between both ends in the longitudinal direction. It is possible to prevent concentration in the phosphorous area.

4 is a perspective view of a curved electrochemical cell 200 according to another embodiment of the present invention, and FIG. 5 is a perspective view of a curved electrochemical cell 300 according to another embodiment of the present invention. 6 is a view showing an electrode assembly constituting the curved electrochemical cells 200 and 300 shown in FIGS. 4 and 5 , and FIG. 7 is an exploded view showing the electrode assembly 210 shown in FIG. 6 . to be. Hereinafter, another embodiment and another embodiment of the present invention in which the configuration of the electrode tab is different will be described with reference to FIGS. 4 to 7 .

First, referring to FIGS. 6 and 7 , the electrode tabs of the curved electrochemical cells 200 and 300 according to the present embodiments may include a parallel connection tab 213 and a lead connection tab 214 . The parallel connection tab 213 may be formed to connect the plurality of electrodes 211a and 211b to each other. Specifically, the parallel connection tabs 213 may protrude from an end of each electrode, so that the plurality of parallel connection tabs 213 may overlap each other and be bonded. In this case, the first electrode tabs 213a formed on the first electrode plate 211a may be coupled to each other, and the second electrode tabs 213b formed on the second electrode plate 211b may be coupled to each other.

The lead connection tab 214 may protrude from an end of at least one of the plurality of electrodes to be coupled to the electrode lead 230 . In the present exemplary embodiment, the lead connection tab 214 may be formed to protrude from a pair of positive and negative electrode plates disposed at the outermost among the plurality of electrodes. A first lead tab 214a may be disposed on an outermost first electrode plate, and a second lead tab 214b may be disposed on an outermost second electrode plate, respectively. On the other hand, the ion conductive electronic insulating layer 212 is prepared in the form of a porous film as shown in FIG. 7 so that the first electrode plate 211a and the second electrode plate 211b are in contact with one side and the opposite side, respectively. It can be arranged to extend in a zigzag.

4 , in another embodiment of the present invention, the electrode lead 230 is disposed at one end of the casing 220 , and thus the lead connection tab 214 of the electrode assembly 210 is connected to the casing 220 . It may be disposed on the side facing one end of the. That is, the lead connection tab 214 may be formed at one end side having a relatively small radius of curvature, and the parallel connection tab 213 may be formed at the other end side having a relatively large radius of curvature. Alternatively, with further reference to FIG. 5 , in another embodiment of the present invention, the lead connection tab 214 is disposed on the side facing the other end of the casing 320 to be connected to the electrode lead 330 , and the casing 320 . A parallel connection tab 213 may be disposed on a side facing one end of the .

According to another embodiment and another embodiment of the present invention, since the electrode tab is provided with the parallel connection tab 213 and the lead connection tab 214 arranged to be divided at both ends of the electrode in the longitudinal direction, the external force applied during curving is provided. The concentration of stress can be alleviated by dispersing the Due to this, according to the present invention, it is possible to manufacture the curved electrochemical cells 200 and 300 in which the radius of curvature is formed smaller than that of the prior art.

Furthermore, according to another embodiment of the present invention of FIG. 4 , the radius of curvature of the side to which the electrode lead 230 is connected may be formed to be smaller (the curvature is large). That is, as compared to the electrode tab 113, which is a structurally weak part, disposed at an end with a large radius of curvature in the previous embodiment, in another embodiment of the present invention, the electrode lead 230 is disposed at an end with a small radius of curvature. Arranged design is possible. Accordingly, in the curved electrochemical cell 200 according to the present invention, constraints can be removed when designing a connection part with a driving circuit of the wearable device, and further, it can contribute to weight reduction and structural simplification of the wearable device.

In the curved electrochemical cell according to the present invention in which the constraint on the curved shape is relaxed as described above, the distance ratio in the length direction to the width direction may be 3:1 to 20:1, and the minimum radius of curvature is 100 It can be manufactured in a curved shape so that it may be less than or equal to mm.

Meanwhile, FIG. 8 is a view showing examples in which the curved electrochemical cells 100 , 200 , and 300 according to the present invention are mounted on a curved surface inside a wearable device. The arrangement as shown in (b) of FIG. 8 is, in consideration of the design (radius of curvature) of the wearable device itself, the curved electrochemical cell ( 100, 300).

In addition, according to the curved electrochemical cell 200 of another embodiment ( FIG. 4 ) of the present invention, since the electrode lead 230 may be disposed at an end with a small radius of curvature, as shown in FIG. It is possible to design in consideration of both the location where the main circuit module is installed and the overall radius of curvature of the wearable device. Furthermore, as shown in (c) and (d) of FIG. 8 , the curved electrochemical cell 200 according to the present invention may be applied to various positions, directions, and radii of curvature in the wearable device.

9 is a flowchart illustrating a method of manufacturing a curved electrochemical cell according to an embodiment of the present invention, and FIG. 10 is a diagram specifically illustrating a process of forming the exterior material shown in FIG. 9 into a curved shape. 11 is a flowchart illustrating a method of manufacturing a curved electrochemical cell according to another embodiment of the present invention. In addition, FIG. 12 is a view specifically illustrating a process of forming the electrochemical cell shown in FIG. 11 into a curved shape. Hereinafter, a method for manufacturing a curved electrochemical cell according to an embodiment and another embodiment of the present invention will be described.

Referring to FIG. 9 , the method for manufacturing a curved electrochemical cell according to an embodiment of the present invention includes manufacturing an electrode assembly ( S310 ), forming a receiving part and a curved shape in an exterior material ( S320 ), and , accommodating the electrode assembly in the receiving portion and sealing the exterior material (S330).

In the step of manufacturing the electrode assembly ( S310 ), a plurality of electrodes are stacked to manufacture the electrode assemblies 110 and 210 . The first electrode plates 111a and 211a and the second electrode plates 111b and 211b may be alternately stacked, and an ion conductive electron insulating layer 212 may be disposed therebetween.

In this case, the relative sizes of the first electrode plate serving as the negative electrode and the second electrode plate serving as the positive electrode may be designed in consideration of a shape to be bent in a subsequent process. Specifically, when a lithium ion cell using graphite as an anode active material has a curved shape, if the cathode active material coating layer is exposed at the edge of the electrode assembly, lithium precipitation occurs during charging, causing problems in performance and safety. Thus, the size of the electrode plate can be designed.

In the step (S320) of forming the accommodating part and the curved shape in the exterior material, the cup-shaped accommodating part 121 for accommodating the electrode assembly may be formed together, and the exterior material ( 120, 220, and 320) may be molded into a curved shape having a cup-shaped accommodating part. The exterior material may be bent so as to have a radius of curvature based on a center line or a central axis spaced apart from a plane formed by the longitudinal direction and the width direction. For molding into the curved shape of the exterior material, the exterior material is placed between the punch and the die manufactured with a predetermined curvature, and the edge of the exterior material is fixed. In this state, if the exterior material is pressed with a punch, the exterior material is tensioned at the boundary between the punch and the die, and shape deformation may start. Thereafter, deformation of the exterior material occurs according to the shape of the punch, and the support mold mounted inside the die brakes the descent of the punch, so that the bending of the exterior material according to the shape of the punch can be formed. At this time, the punch, die, and support mold may be heated to a preset temperature, and the above exterior material forming process may be performed. For example, in consideration of the thickness of the cell, the molding process may be performed under conditions of applying a pressure of 1 to 10 kgf/cm ² to the exterior material, and a temperature of 30 to 120° C. to the punch, die, and support mold.

In addition, a pattern (eg, a concave-convex pattern, a wrinkle pattern, etc.) that can be formed in the accommodating part may also be formed in the forming process. To this end, the frame is provided with a shape corresponding to the accommodating part and the pattern, and a curved shape and various pattern shapes can be formed by one press.

Referring to FIG. 10 , the step (S320) of forming the receiving part and the curved shape in the exterior material includes a fixing step (S321) of supporting and fixing at least one end of the exterior material, and pressing the exterior material by a curved frame to form a curved shape. It may include a curving step (S322) of forming the.

In the fixing step ( S321 ), at least one end of the casing 120 placed on the first holder or die 321 ′ is supported by the first pressing part or the punch 321 , so that the location of the casing 120 can be fixed. have. And, in the curving step ( S322 ), the exterior material may be pressed by the curved frame (the second holder or die 322 ′ and the second pressing unit or punch 322 ) to be molded into a curved shape.

In the step (S330) of accommodating the electrode assembly in the receiving part and sealing the casing, the electrode assembly is accommodated in the curved casing and the casing is sealed. Specifically, the packaging material having a curved shape accommodating the electrode assemblies 110 and 210 may be pressure-sealed. The electrode assembly may be bent to match the shape of the casing while being accommodated in the curved casing. The exterior material may be sealed by bonding of the sealing part 122 formed along the edge of the exterior material. In particular, for bonding the sealing portion, the sealing portion may be naturally joined to the curved shape by pressing and bonding the sealing portion by a frame having a curved shape to be formed.

In the step (S320) of forming the receiving part and the curved shape in the above casing and the step (S330) of accommodating the electrode assembly in the receiving part and sealing the casing (S330), the radius of curvature at one end of both ends of the casing in the longitudinal direction is one It is molded and sealed to have a value smaller than the radius of curvature of the other end located opposite to the end. Accordingly, an asymmetrical curved shape in the longitudinal direction may be formed.

According to the manufacturing method of the curved electrochemical cell of this embodiment, the shape of the casing material is formed into a curved shape before accommodating the electrode assembly, and further, the casing material accommodating the electrode assembly can be sealed in a curved shape under a reduced pressure environment. According to this, unlike the conventional method of pressing the cell after completing assembly and sealing, it is possible to prevent wrinkles from remaining on the appearance of the finished curved electrochemical cell. Accordingly, the curved electrochemical cell manufactured according to the present embodiment has the advantage of being freely mounted in a narrow space such as a wearable device. In addition, in the conventional process of pressurizing the cell after assembling the electrode assembly and injecting the electrolyte, it is possible to prevent a defect from occurring in the cell due to a physical force.

Meanwhile, the method of manufacturing the curved electrochemical cell according to the present embodiment may further include the step of further molding the curved shape ( S340 ). In the preceding step, the electrochemical cell in which the electrode assembly is accommodated in the curved packaging material may be pressure-sealed. And, in the step of further molding the curved shape, the pressure-sealed electrochemical cell may be pressed to form a more curved shape. At this time, pressurization may be made under preset pressure and temperature conditions, for example, in consideration of the cell thickness, pressurized by a curved frame at a pressure of 1 to 10 kgf/cm ² and a temperature of 30 to 120° C. The process may proceed. The step (S340) of additionally forming the curved shape of the present embodiment may be performed in the same process as the step (S430) of forming the curved shape of another embodiment to be described later.

By adding the step ( S340 ) of additionally forming the curved shape, the forming of the curved electrochemical cell may be performed step by step. For example, for a portion where the radius of curvature is formed to be relatively small, the curved shape of the exterior material may be secured in advance by forming the exterior material into a curved shape before receiving the electrode assembly. In addition, a portion having a relatively large radius of curvature may be formed into a curved shape by forming the sealed electrochemical cell into a curved shape. By such a step-by-step molding process, the occurrence of defects due to force and temperature applied to the electrochemical cell during the manufacturing process may be suppressed.

On the other hand, referring to FIGS. 11 and 12 , the method for manufacturing a curved electrochemical cell according to another embodiment of the present invention includes manufacturing an electrode assembly ( S410 ), and sealing the electrode assembly by accommodating the electrode assembly in a casing. It includes a step (S420) and a step (S430) of forming a curved shape by pressing the sealed electrochemical cell.

In another embodiment of the present invention, the step ( S410 ) of manufacturing an electrode assembly by stacking electrodes may be performed as in the previous embodiment. Then, the assembled electrode assembly may be accommodated in the housing in which the receiving portion is formed, and the housing may be sealed so that a portion of the electrode lead connected to the electrode assembly is exposed to the outside ( S420 ).

In addition, the electrochemical cell sealed in the state in which the electrode assembly is accommodated may be formed into a curved shape by pressure (S430). In this case, the curved shape of the exterior material may have a radius of curvature at one end of both ends in the longitudinal direction is smaller than a radius of curvature at the other end positioned opposite to the one end. In order to mold the sealed electrochemical cell into a curved shape, pressing may be performed by a curved frame under a pressure of 1 to 10 kgf/cm ² and a temperature of 30 to 120° C. in consideration of the thickness of the cell.

In this embodiment, forming the curved shape of the electrochemical cell (S430) may include a fixing step (S431) and a curving step (S432). In the fixing step ( S431 ), at least one end of the exterior material may be supported and fixed. Referring to FIG. 12 , in the fixing step ( S431 ), the coupling part of the electrode tab and the electrode lead, which may have relatively weak durability, or one end of the exterior material having a small radius of curvature is moved in the thickness direction by the first pressing part 431 . can be supported on both sides. When the electrode lead is coupled to the other end having a large radius of curvature, a more vulnerable portion may be supported in consideration of the size of the radius of curvature and the overall thickness of the curved electrochemical cell. Alternatively, the first pressing part 431 may have a predetermined radius of curvature to support and fix one end of the exterior material in a curved shape.

In the curving step ( S432 ), the electrochemical cell may be formed into a curved shape while being pressed by the curved frame. Referring to FIG. 12 , in the curving step S432 , the remaining portion other than the portion supported in the fixing step S431 may be pressed by the second pressing unit 432 . The portion pressed and molded by the second pressing unit 432 may be a portion including the other end of the electrochemical cell having a relatively large radius of curvature. 13 is a table showing cell shapes and test results of embodiments of a curved electrochemical cell and a method for manufacturing the same according to the present invention. With reference to FIG. 13 , shapes and test results of various embodiments according to the method for manufacturing the curved electrochemical cell and the curved electrochemical cell according to the present invention described above will be described.

13 is a cell shape and test results based on an electrochemical cell having a standard of 120 mm in length, 14 mm in width, and 3 mm in thickness. Also, Ref. 1 to Ref. 3 is a comparative example of a conventional manufacturing method in which a curved shape is formed by pressing an assembled cell. The bending area was divided into three and the radius of curvature and length were designed as shown in the table.

Case 1 to Case 4 of FIG. 13 correspond to the curved electrochemical cell 100 according to an embodiment of the present invention, and Case 5 to Case 8 are another embodiment or a curved electrochemical cell 100 according to another embodiment of the present invention. Corresponds to the electrochemical cells 200 and 300 . Specifically, Case 5, Case 6, and Case 8 are the curved electrochemical cell 300 according to another embodiment of the present invention, and Case 7 is the curved electrochemical cell 200 according to another embodiment of the present invention. (Bending regions are shown in reverse order for comparison with Case 6).

In addition, Cases 1 to 8 are by the method of manufacturing a curved electrochemical cell according to an embodiment of the present invention, and after forming the exterior material in a curved shape, the electrode assembly is accommodated and sealed in the curved shape. Furthermore, Case 4 and Case 8 are cases in which the exterior material is pressed once more after sealing and molded into a curved shape.

First, referring to comparative examples in which a curved shape was formed (cured) by pressing a cell that has been assembled and sealed, all comparisons In the example, it can be seen that the voltage does not come out normally after curving. This was confirmed to be due to the electrode tab or the coupling portion of the electrode tab and the electrode lead was broken. In addition, it can be seen that there are a number of cells in which defects are generated after curving, and the wrinkle of the exterior material is larger than the allowable standard.

On the other hand, referring to Cases 1 to 4 of the curved electrochemical cell 100 according to an embodiment of the present invention manufactured by the method for manufacturing a curved electrochemical cell according to an embodiment of the present invention, curving and It can be seen that the finished curved electrochemical cell had good appearance wrinkles and no defects. In particular, referring to Case 4, it can be seen that the voltage is normally maintained even after curving.

Furthermore, referring to Cases 5 to 8, which are curved electrochemical cells 200 and 300, in which electrode tabs are distributed to both ends of the exterior material as parallel connection tabs and lead connection tabs, similarly, the appearance state is good and defects do not occur. can confirm that it is not. In particular, referring to Cases 5 to 8, it can be confirmed that it is possible to form a smaller radius of curvature and a larger difference in the radius of curvature of both ends of the exterior material compared to Cases 1 to 4.

The foregoing description of the present invention is for illustration, and those of ordinary skill in the art to which the present invention pertains can understand that it can be easily modified into other specific forms without changing the technical spirit or essential features of the present invention. will be. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive. For example, each component described as a single type may be implemented in a distributed manner, and likewise components described as distributed may also be implemented in a combined form.

The scope of the present invention is indicated by the following claims rather than the detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included in the scope of the present invention.

A ₁ , A ₂ , A ₃ , A ₄ , A ₅ : bending area
100, 200, 300: electrochemical cell
110, 210: electrode assembly
111a, 211a: first electrode plate
111b, 211b: second electrode plate
113: electrode tab
113a, 213a: first electrode tab
113b, 213b: second electrode tab
120, 220, 320: exterior material
121: receptacle
122: sealing part
130, 230, 330: electrode lead
212: ion conductive electronic insulating layer
213: parallel connection tap
214: lead connection tab
214a: first lead tab
214b: second lead tab

Claims (11)

A curved electrochemical cell comprising:
an electrode assembly including a plurality of electrodes and electrode tabs formed on the electrodes;
a casing formed to accommodate the electrode assembly; and
and an electrode lead connected to the electrode tab and exposed to the outside of the exterior material,
The exterior material is characterized in that it is bent so that the radius of curvature at one end of both ends in the longitudinal direction is smaller than the radius of curvature of the other end located opposite to the one end,
N bending regions arranged in parallel in the longitudinal direction are formed on the exterior material (N is a natural number equal to or greater than 2),
The N bending areas are formed such that the radius of curvature and the length gradually increase from the bending area located at the one end side to the bending area located at the other end side,
The curved electrochemical cell is a curved electrochemical cell, characterized in that by pressing and fixing one end of the exterior material by a first pressing part, and pressing the exterior material by a second pressing part having a curved surface to form a curved shape. chemical cell.
According to claim 1,
The electrode tab is a curved electrochemical cell, characterized in that formed to connect the plurality of electrodes to each other on the side facing the other end of the casing.
According to claim 1,
The radius of curvature (r _n ) of the n-th bending region from the one end is less than or equal to the radius of curvature (r _n+1 ) of the n+1-th bending region from the one end (n) is a natural number, 1≤n≤N-1).
4. The method of claim 3,
A curved electrochemical cell, characterized in that in a direction from the one end to the other end, the length of the n+1-th bending region is greater than or equal to the length of the n-th bending region.
4. The method of claim 3,
Wherein N is a natural number of 3 or more,
The ratio of the radius of curvature (r _n+2 ) of the n+2th bending region to the radius of curvature (r _n+1 ) of the n+1th bending region is the radius of curvature (r _n ) of the nth bending region A curved electrochemical cell, characterized in that it is greater than or equal to the ratio of the radius of curvature (r _n+1 ) of the n+1-th bending region from the one end.
According to claim 1,
The electrode tab is
a parallel connection tab formed to connect the plurality of electrodes to each other; and
and a lead connection tab formed on at least one of the plurality of electrodes and coupled to the electrode lead;
A curved electrochemical cell, characterized in that the parallel connection tab is formed on a side facing one of the one end and the other end of the casing, and the lead connection tab is formed on a side facing the other.
delete A method for manufacturing a curved electrochemical cell, comprising:
manufacturing an electrode assembly by stacking a plurality of electrodes;
forming a accommodating part for accommodating the electrode assembly and a curved shape in a case; and
accommodating the electrode assembly in the receiving portion of the packaging material molded into the curved shape and sealing the exterior material,
In the step of forming the accommodating part and the curved shape and sealing the exterior material, the radius of curvature at one end of both ends of the exterior material in the longitudinal direction is smaller than the radius of curvature of the other end located opposite to the one end. Characterized in molding and sealing to have a value,
Further comprising the step of forming N bending regions arranged in parallel in the longitudinal direction on the exterior material (N is a natural number equal to or greater than 2),
In the step of forming the N bending regions, it is characterized in that the curvature radius and length are gradually increased from the bending region located at the one end side to the bending region located at the other end side,
pressing and fixing one end of the exterior material by a first pressing unit; and
The method of manufacturing a curved electrochemical cell further comprising the step of pressing the exterior material by a second pressing unit having a curved surface to form a curved shape.
9. The method of claim 8,
The method of manufacturing a curved electrochemical cell further comprising the step of further molding the curved shape by pressing the electrochemical cell in which the electrode assembly is accommodated and sealed in the curved shape of the exterior material.
delete A method for manufacturing a curved electrochemical cell, comprising:
manufacturing an electrode assembly by stacking a plurality of electrodes;
accommodating the electrode assembly in a casing and sealing the casing so that a portion of an electrode lead connected to the electrode assembly is exposed to the outside of the casing; and
and forming a curved shape by pressing the sealed electrochemical cell in a state in which the electrode assembly is accommodated,
In the step of forming the curved shape, the exterior material is molded so that the radius of curvature at one end of both ends in the longitudinal direction has a smaller value than the radius of curvature of the other end located opposite to the one end,
Further comprising the step of forming N bending regions arranged in parallel in the longitudinal direction on the exterior material (N is a natural number equal to or greater than 2),
In the step of forming the N bending areas, it is characterized in that the curvature radius and length are gradually increased from the bending area located at the one end side to the bending area located at the other end side, ,
pressing and fixing one end of the exterior material by a first pressing unit; and
The method of manufacturing a curved electrochemical cell, characterized in that it further comprises the step of pressing the exterior material by a second pressing part having a curved surface to form a curved shape.

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