KR20160014498A - Stack and folding-type electrode assembly and method for fabricating the same - Google Patents

Abstract

Provided are a stack-folding type electrode assembly which has high degree of freedom in a design and can reduce the number of foldings, and a producing method thereof. The stack-folding type electrode assembly according to the present invention has a structure in which a plurality of stack type unit cells are overlapped with each other and a continuous folding separation membrane sheet interposed between each overlapped part, wherein the unit cells certainly comprise quad cells having a positive electrode/separation membrane/negative electrode/separation membrane/positive electrode/separation membrane/negative electrode structure, and more comprise C-type bi-cells having a negative electrode/separation membrane/positive electrode/separation membrane/negative electrode structure, A-type bi-cells having a positive electrode/separation membrane/negative electrode/separation membrane/positive electrode structure, or a combination thereof.

Description

[0001] Stack-folding electrode assembly and method of fabricating the same [0002]

The present invention relates to a stack-folding type electrode assembly and a manufacturing method thereof, and more particularly, to a stack-folding type electrode assembly capable of reducing the number of times of folding and a method of manufacturing the same.

Due to the development of technology and demand for mobile devices, the demand for secondary batteries is also rapidly increasing. Among them, lithium secondary batteries, which have high energy density, high operating voltage and excellent storage and life characteristics, It is widely used as an energy source.

The secondary battery is roughly classified into a cylindrical battery, a prismatic battery and a pouch-shaped battery according to the structural characteristics of the outside and the inside. Among them, the secondary battery can be stacked with a high degree of integration, and prismatic batteries and pouch- .

The electrode assembly of the anode / separator / cathode structure constituting the secondary battery is largely classified into a jelly-roll type (winding type) and a stack type (laminate type) depending on its structure. In the jelly-roll type electrode assembly, an electrode active material or the like is coated on a metal foil used as a current collector, dried and pressed, cut into a band shape having a desired width and length, and a cathode and an anode are diaphragm- . The jelly-roll type electrode assembly is suitable for a cylindrical battery. However, when applied to a square or pouch type battery, it has disadvantages such as peeling of an electrode active material and low space utilization. On the other hand, the stacked electrode assembly has a structure in which a plurality of positive electrode and negative electrode unit cells are sequentially stacked and has a merit that it is easy to obtain a rectangular shape. However, when the manufacturing process is troublesome and impact is applied, .

In order to solve such a problem, the jelly-roll type and stack type mixed type electrode assemblies have been proposed in which a full cell or a positive electrode (cathode) / separator / cathode (anode) / separator A stack-folding type electrode assembly having a structure in which a bicell having an anode / cathode structure is folded by using a continuous long folding separator sheet has been developed.

Figs. 1 and 2 schematically show an exemplary structure and a manufacturing process of such a stack-folding type electrode assembly.

Referring to these drawings, C type bi-cells 10, 13, and 14 having a structure of a cathode / separator / anode / separator / cathode are sequentially formed as a unit cell and an A type bi- 11 and 12 are alternately stacked, and a folding separator sheet 20 is interposed in each of the overlapping portions. The folding separator sheet 20 has a unit length that can wrap around the bicells and is folded inward for each unit length to start from the center bicycle 10 and continue to the outermost bicycle 14, And is interposed in the overlapped portion of the bi-cell. The distal end of the folding sheet 20 is thermally fused or bonded with an adhesive tape 25 or the like.

This stack-folding type electrode assembly can be formed by, for example, arranging bicells 10, 11, 12, 13, and 14 on a long-length folding separator sheet 20, (21) and sequentially winding them.

The first bi-cell 10 and the second bi-cell 11 have a width corresponding to at least one bi-cell, as shown in FIG. The outer surface of the first bi-cell 10 is completely coated with the folding separator sheet 20 and then the lower surface electrode (negative electrode) of the first bi-cell 10 is exposed. (Positive electrode, +) of the second bi-cell 11. Since the coating length of the folding separator sheet 20 is increased in the sequential lamination process by winding the bi-cells 12, 13, and 14 after the second bi-cell 11, And are disposed so as to sequentially extend. The bi-cells 10, 11, 12, 13, and 14 should be configured such that the positive electrode and the negative electrode face each other at the interface between the first and second bi- Cell and the second bi-cell 11 and the third bi-cell 12 are bi-cells having an upper surface electrode as an anode, and the fourth bi-cell 13 and the fifth bi- In-cell. That is, the bi-cells are mounted in an alternating arrangement of two units.

The stack-folding type electrode assembly compensates for the disadvantages of the jelly-roll and the stacked electrode assembly. However, in order to position the cathode at the outermost periphery of the electrode assembly, stacking can be performed only in an odd number of stacks. Table 1 shows the number of electrodes according to the number of stacks in the stack-folding type electrode assembly as shown in Fig.

Number of stacks One 3 5 7 9 11 13 ... Electrode number 3 9 15 21 27 33 39 ...

In this case, since the number of cells is increased by 6 cells according to the increase in the number of stacks, there is a limitation in changing the number of stacks for cell performance such as thickness, capacity, and resistance. In addition, if the number of bi-cell stacks is increased for high energy density, the number of times of folding increases, thereby increasing the dimensional change / defect rate of the electrode assembly cell and increasing the process time. Accordingly, there is a demand for a stack-folding type electrode assembly and a method of manufacturing the stack-folding type electrode assembly, which are capable of high degree of freedom in designing and capable of reducing the number of times of folding.

SUMMARY OF THE INVENTION The present invention provides a stack-folding type electrode assembly having a high degree of freedom in design and capable of reducing the number of times of folding, and a manufacturing method thereof.

According to an aspect of the present invention, there is provided a stack-folding type electrode assembly including a plurality of stacked unit cells stacked on each other, and a continuous folding separator sheet interposed between the stacked unit cells, Separators / cathodes / separators / cathodes / separators / cathodes, and a C type bi-cell or anode / separator / cathode / separator / separator / An A type bi-cell of an anode structure or a combination thereof.

The C-type bi-cell or the A-type bi-cell ('central bi-cell') is preferably located at the center of winding of the overlapped unit cells. In this case, it is preferable that the unit cells located on the upper and lower sides of the central bi-cell are symmetrical with respect to their electrode directions. The unit cells located on the upper and lower sides of the central bi-cell are preferably a combination of a quad cell and a bi-cell.

In the electrode assembly according to the present invention, the cathode may be positioned at the outermost periphery of the electrode assembly. The folding separator sheet may have a unit length capable of wrapping the unit cells, and may be folded inward for each unit length to continuously start from the central unit cell to the outermost unit cell.

The present invention also provides a secondary battery including the stack-folding type electrode assembly.

The present invention also provides a method of manufacturing such a stack-folding electrode assembly. The method includes positioning a central unit cell at a first end of the folding separator sheet and successively positioning the unit cells at a predetermined interval; And folding the central unit cell by folding the folding separator sheet once, folding the folding separator sheet outward where adjacent unit cells are located, and folding each unit cell by folding.

Particularly, in the present invention, in order to manufacture such a stack-folding type electrode assembly, a basic design loop including electrode assemblies in which the number of electrodes is increased by two in the same stack number is formed, And performing a cell design in which the number of electrodes increases by two while adding a cell or an A-type bi-cell.

At this time, the added cell can be inserted into the outermost portion of the electrode assembly included in the basic design loop, the winding center portion, or the stack intermediate portion.

In a preferred embodiment, the basic design loop comprises: (a) a central bi-cell is an A-type bi-cell and two pairs of C-type bi-cells and a pair of A-type bi- (B) a central bicycle is a C-type bicycle, and a pair of C-type bi-cells and a pair of A-type bi-cells on the upper and lower sides with respect to the central bicycle are stacked with the quad- (C) a structure in which a central bicycle is an A-type bi-cell and a pair of C-type bi-cells in an upper and a lower position are compared with the central bi-cell, (D) a structure in which a central bicycle is a C-type bi-cell and two pairs of C-type bi-cells and two pairs of A-types And the same number of quad cells as in (a) above, And a structure in which two taeksu increases.

The arrangement of the A-type bi-cell and the C-type bi-cell may be continuous or non-continuous.

According to the present invention, design freedom is increased by selectively applying quad-cell, A-type bi-cell, and C-type bi-cell. In this case, the number of electrodes can be finely adjusted and the degree of freedom of design is higher than that of the prior art in which the number of electrodes is increased by six because the cell design can increase the number of electrodes by two.

Also, since the quad cell having a larger number of electrodes than the bi-cell is used, the number of folding can be reduced because the unit assembly can be reduced at the same number of electrodes compared to the conventional one. Accordingly, the folding dimensional tolerance and the defective ratio can be reduced, and the lamination and folding process time can be reduced.

1 is a schematic diagram of an exemplary structure of a conventional stack-folding type electrode assembly.
FIG. 2 is a schematic diagram illustrating an exemplary arrangement of unit cells in a manufacturing process of the stack-folding type electrode assembly of FIG. 1;
3 is a schematic diagram of a stack-folding type electrode assembly structure according to an embodiment of the present invention.
FIG. 4 is a schematic view showing an arrangement combination of unit cells in the manufacturing process of the stack-folding type electrode assembly of FIG. 3;
5 is a schematic view of a stack-folding type electrode assembly structure according to another embodiment of the present invention.
6 is a schematic diagram showing an arrangement combination of unit cells in the manufacturing process of the stack-folding type electrode assembly of FIG.
FIG. 7 illustrates possible cell designs in the case where the number of stacks is 11 or more in the electrode assembly according to the present invention, wherein (a) to (e) Together.
Figs. 8 to 10 are modifications of the cell design shown in Fig.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. It is provided to let you know.

In addition, the battery or the electrode assembly included in the present invention is not particularly limited in its shape and may include various shapes. For example, the stacked unit cells may be stacked on a stack of folded separator sheets A folding type electrode assembly, a Z stack electrode assembly for folding in the zigzag direction when the stacked unit cells are wound with a folding separator sheet, and the like.

3 is a schematic diagram of a stack-folding type electrode assembly structure according to an embodiment of the present invention.

Referring to FIG. 3, a plurality of stacked unit cells 110, 111, 112, 113 and 114 are stacked in a stack-folding type electrode assembly, and a folding separator sheet 120 is interposed between stacked unit cells 110, 111, 112, 113 and 114. The folding separator sheet 120 has a unit length capable of wrapping the unit cells 110, 111, 112, 113, and 114 and is bent inward for each unit length to start from the center unit cell 110, 111, 112, 113, and 114 in a structure in which the unit cells 110, 111, 112, 113, and 114 are continuously surrounded by the unit cells 110, 111, 112, 113, In addition, the distal end of the folding sheet 120 is thermally fused or bonded with an adhesive tape 125 or the like.

The electrode assembly includes an A type bi-cell 110 having a positive electrode / separator / negative electrode / separator / positive electrode structure, quad cells 111 and 112 having a positive electrode / separator / negative electrode / separator / positive electrode / separator / negative structure, And a C type bi-cell 113, 114 of a separator / cathode structure.

The unit cell anode is prepared, for example, by coating a mixture of a cathode active material, a conductive material and a binder on both surfaces of a cathode current collector, followed by drying and pressing, and if necessary, a filler may be further added to the mixture. The unit cell negative electrode is prepared by applying, drying and pressing an anode active material on a negative electrode current collector, and may optionally further include a conductive material, a binder, a filler, and the like as described above. As described above, the positive electrode and the negative electrode may be coated with a positive electrode active material or a negative electrode active material on both sides of each current collector (electrode sheet), but they are not shown for convenience.

A type Bicell 110 (a 'central bicycle') is located at the center of winding of the unit cells 110, 111, 112, 113, and 114. The unit cells 111, 112, 113, and 114 located at the upper and lower sides of the central biqual cell are symmetrical with respect to their electrode directions. The negative electrode may be positioned at the outermost periphery of the electrode assembly. Particularly, in this embodiment, the quad-cell 111 and the quad-cell 112 are folded at the center of the A-type bi-cell 110, and the unit cells located on the upper and lower sides of the central b- 111 and 112 and a bi-cell combination 113 and 114, respectively.

When a plurality of unit cells are stacked in a positive electrode / negative electrode facing structure, if possible, the negative electrode occupies a large area. For example, when the unit cells are used in a lithium secondary battery, lithium metal, dendrite) can be suppressed as much as possible. Accordingly, the cathode may be formed to have a wider area than the anode, and / or the outermost electrode assembly may be constituted of the cathode.

FIG. 4 is a schematic view showing an arrangement combination of unit cells in the manufacturing process of the stack-folding type electrode assembly of FIG. 3;

A plurality of quad cells and bi-cells are manufactured by stacking an anode and a cathode with a separator interposed therebetween and cutting the anode and the cathode into a predetermined size to form unit cells 110, 111, 112, 113 and 114 are provided. After the folding separator sheet 120 is cut and prepared, the unit cells 110, 111, 112, 113 and 114 are arranged as shown in FIG. The folding separator sheet 120 has a width slightly larger than the unit cells 110, 111, 112, 113 and 114 while exposing electrode tabs (not shown) of the unit cells 110, 111, 112, And may have an extended length that covers the electrode assembly once after being wound, and the outermost end of the folding sheet 120 may be heat-sealed or tape-fixed. For example, the folding separator sheet 120 itself can be melted and adhered and fixed by contact with a folding separator sheet 120 to be finished, such as a heat welder or a hot plate, have.

This stack-folding type electrode assembly has a structure in which the unit cells 110, 111, 112, 113 and 114 are arranged on the long folding separator sheet 120 and the one end 121 of the folding separator sheet 120 And then winding them sequentially. At this time, after the central bycell 110 is once wound on the folding separator sheet 120, the folding separator sheet 120 is folded outward where the adjacent unit cells 111, 112, 113, and 114 are located, The unit cells 111, 112, 113, and 114 are folded.

The central unit cell 110 is positioned at the first end of the folding separator sheet 120 and the unit cells 111, 112, 113, and 114 are arranged at predetermined intervals. 113, and 114 are successively positioned. The first unit cell, that is, the central unit cell 110 and the second unit cell 111 are located at a distance separated by a width corresponding to at least one bi-cell, The bottom surface electrode (anode) of the central biphase 110 is brought into contact with the top surface electrode (cathode) of the second unit cell 111 after the outer surface is completely coated with the folding separator sheet 120. Since the length of the folded sheet 120 is increased during the sequential lamination process by winding the unit cells 112, 113 and 114 after the second unit cell 111, And are disposed so as to sequentially extend. The unit cells 110, 111, 112, 113, and 114 are formed so that the positive electrode and the negative electrode face each other at the stacked interface at the time of winding. The center cell 110 has an A- The second unit cell 111 and the third unit cell 112 are quad cells having the upper surface electrode as a cathode and the fourth unit cell 113 and the fifth unit cell 114 are connected to the upper surface electrode And a C type bi-cell which is a cathode.

The number of unit cells wound on the folding separator sheet 120 may be determined by various factors such as the structure of each unit cell such as each quad cell, the bi-cell, and the desired capacity of the final cell. 3, the number of unit cells included in the stack-folding type electrode assembly may be smaller or larger than the number of unit cells included in the stack-folding type electrode assembly.

The folding separator sheet 120 may be the same material as the separator constituting the unit cell. The folding separator sheet or separator may be a polyethylene film containing micropores, a polypropylene film, or a multilayer film produced by a combination of these films, and a layered film made of polyvinylidene fluoride, polyethylene oxide, polyacrylonitrile, or polyvinylidene Fluorinated hexafluoropropylene copolymer, and polymer film for a polymer electrolyte of a fluorinated hexafluoropropylene copolymer, and may be a single layer or a multi-layered folding separator sheet or separator film .

In the structure shown in Fig. 3, a pair of quad cells 111 and 112 and a pair of C-type bi-cells 113 and 114 come sequentially in the center with respect to the A-type bi-cell 110 as an example heard. The stacking order of a pair of C type bi-cells 113 and 114 and a pair of quad cells 111 and 112 may be different. For example, when a pair of C-type bi-cells 113 and 114 are first turned on at the center of the A-type bi-cell 110, It is also possible that the bixel comes to the winding center as in the case where the quad cells 111 and 112 are stacked. It is also possible to use a modification in which two or more pairs of quad cells and two or more pairs of C type bicells are included. More than two pairs of quad cells and two or more pairs of C type bi-cells may be stacked one on top of the other, that is, the arrangement of bi-cells may be continuous, or a pair of quad cells - a pair of C type bi- - Various combinations are possible, for example, the arrangement of the bi-cells may be discontinuous, as in the case of a pair of C-type bi-cells being stacked alternately. In addition, it is also possible to stack the A-type bicells between the C-type bi-cells and the quad-cells.

Particularly, such a lamination structure must be formed in the cell design stage before the production of the actual electrode assembly, and the present invention also provides a method of manufacturing an electrode assembly including a cell designing step for manufacturing such a stack-folding type electrode assembly. The cell designing step includes the steps of creating a basic design loop including electrode assemblies in which the number of electrodes increases by two in the same stack number and then forming a quad cell, a C type bi-cell or an A type bi- And performing cell design in which the number of electrodes is increased by two. This method will be described in more detail in the following embodiments.

The subsequent battery manufacturing process is as follows. The positive electrode and the negative electrode lead are welded to the electrode tab portion of the stack-folding type electrode assembly manufactured. At this time, it is effective to use aluminum as the positive electrode and copper as the negative electrode. After the packing of the welded cells into an aluminum pouch, an electrolyte is injected.

The electrolytic solution used in the art is not particularly limited. Specific examples of the solvent include dimethyl carbonate (DMC), ethylene carbonate (EC), ethyl methyl carbonate (EC), propylene carbonate (PC), diethyl carbonate (EC), ethylene carbonate (EC), dimethyl carbonate (DMA) At least one selected from the group consisting of N, N-dimethylformamide (DMF), N-methyl-2-pyrrolidinone (NMP), dimethyl sulfoxide (DMSO), tetrahydrofuran (THF), propylene carbonate use.

FIG. 5 is a schematic view of a stack-folding type electrode assembly according to another embodiment of the present invention, and FIG. 6 is a schematic diagram showing an arrangement combination of unit cells in a manufacturing process of the stack-folding type electrode assembly of FIG.

5, a plurality of stacked unit cells 210, 211, 212, 213, 214, 215, and 216 are stacked, and a folding separator sheet 220 is interposed between the stacked unit cells 210, have. The folding separator sheet 220 has a unit length capable of wrapping the unit cells 210, 211, 212, 213, 214, 215 and 216 and is bent inward for each unit length to start from the center unit cell 210, The unit cells 210, 211, 212, 213, 214, 215, and 216 are formed to surround the unit cells 210, 211, 212, 213, 214, 215, As shown in Fig. Further, the distal end of the folding sheet 220 is heat-sealed or attached with an adhesive tape 225 or the like. The electrode assembly includes C type bi-cells 210, 215 and 216, quad cells 211 and 212, and A type bi-cells 213 and 214. In particular, the C type bi-cell 210 is centered and the quad cells 211 and 212 are folded.

A C type bi-cell 210 (a 'central bi-cell') is located at a central portion of the overlapped unit cells 210, 211, 212, 213, 214, The unit cells 211, 212, 213, 214, 215, and 216 located on the upper and lower sides of the central biqual cell are symmetrical with respect to their electrode directions. The cathode is located at the outermost edge of the electrode assembly.

This stack-folding type electrode assembly has a structure in which unit cells 210, 211, 212, 213, 214, 215 and 216 are arranged on a long folding separator sheet 220 and one end of the folding separator sheet 220 (221) and sequentially winding them. The central unit cell 210 is positioned at the first end of the folding separator sheet 220 and the unit cells 211, 212, 213, 214, 215, and 216 are successively positioned at predetermined intervals. Each of the unit cells 210, 211, 212, 213, 214, 215, and 216 is configured such that the positive electrode and the negative electrode face each other at the interface where the unit cells are stacked at the time of winding. C type bi-cell, the second unit cell 211 and the third unit cell 212 are quad cells in which the upper surface electrode is an anode, and the fourth unit cell 213 and the fifth unit cell 214 are in the upper surface And the sixth unit cell 215 and the seventh unit cell 216 are formed of a C type bi-cell having a top electrode at the top.

5, a pair of quad cells 211 and 212, a pair of A type bi-cells 213 and 214, and a pair of C type The bi-cells 215 and 216 come in succession. The stacking order of these can be changed. For example, when a pair of A type bi-cells 213 and 214 are first turned on at the center of a C type bi-cell 210, and then a pair of quad cells 211 and 212 are reversely stacked It is also possible. It is also possible to use a modification in which two or more pairs of quad cells and two or more pairs of A type bicells and C type bicells are included. Two or more pairs of quad cells, A type Bicells, and C type Bicells may be stacked one after the other or stacked alternately or in sequence. Various combinations are possible. It is also possible to combine only C type bi-cell and quad cell without A type bi-cell.

In the embodiments of the present invention, the central unit cell is an A type bi-cell or a C type bi-cell. However, the central unit cell may be a quad cell. In the embodiments of the present invention, the unit cells positioned above and below the center bi-cell are symmetrical with respect to their electrode directions. However, the electrode directions do not necessarily have to be symmetrical.

As described above, the stack-folding electrode assembly according to the present invention includes a quad cell having an anode / separator / cathode / separator / anode / separator / cathode structure as a unit cell and a cathode / separator / anode / separator / cathode structure C type bi-cell of the anode / separator / cathode / separator / anode structure, or a combination thereof. In the present invention, the quad cell, the A type bi-cell, and the C type bi-cell are laminated, respectively. As the total number of unit assemblies decreases at the same number of electrodes, the number of times of lamination can be reduced. A quad cell, an A-type bi-cell, and a C-type bi-cell are placed on the folding separator sheet according to the desired number of electrodes, and then the folding process is performed. By reducing the unit assembly, the number of folding decreases and the degree of design freedom increases.

Table 2 shows the number of electrodes according to an increase in the number of stacks in the stack-folding type electrode assembly according to the present invention including a pair of quad-cells or more while the A type or C type bi-cell is a central bi-cell.

Number of stacks 3 (central bicycle + 2 quad cells) 5 (central bicycle + 4 quad cell) 7 (central bicycle + 6 quad cell) 9 (central bicycle + 8 quad cells) 11 (central bicycle + 10 quad cell) 13 (central bicycle + 12 quad cells) ... Electrode number 11 19 27 35 43 51 ...

Although the number of stacks is nine in the present invention even though the number of electrodes is equal to 27 in Table 2, seven stacks are required in the present invention, and 17 stacks are required even though the number of electrodes is 51. In the present invention, As the number of stacks is required, the effect of reducing the number of stacks is excellent.

Table 3 shows the number of electrodes according to the increase in the number of stacks in the stack-folding type electrode assembly according to the present invention, which includes one pair of bi-cells and one pair or more of quad cells while the A type or C type bi- .

Number of stacks 5 (central bicycle + 2 quad cells + 2 bi cells) 7 (central bicycle + 4 quad cells + 2 bi cells) 9 (central bicycle + 6 quad cells + 2 bi cells) 11 (central bicycle + 8 quad cells + 2 bi cells) 13 (central bicycle + 10 quad cells + 2 bi cells) 15 (central bicycle + 12 quad cells + 2 bi cells) ... Electrode number 17 25 33 41 49 57 ...

Table 4 shows the number of electrodes according to the increase in the number of stacks in the stack-folding type electrode assembly according to the present invention including two or more pairs of bi-cells, including one or more pairs of quad cells while the A type or C type bi- .

Number of stacks 7 (central bicycle + 2 quad cells + 4 bicells) 9 (central bicycle + 4 quad cells + 4 bicells) 11 (central bicycle + 6 quad cells + 4 bi cells) 13 (central bicycle + 8 quad cells + 4 bi-cells) 15 (central bicycle + 10 quad cells + 4 bicells) 17 (central bicycle + 12 quad cells + 4 bicells) ... Electrode number 23 31 39 47 55 63 ...

Table 5 shows the number of electrodes according to the increase in the number of stacks in the stack-folding type electrode assembly according to the present invention, in which the A type or C type bi-cell is a central bi-cell and includes at least one pair of quad cells, .

Number of stacks 9 (central bicycle + 2 quad cells + 6 bi cells) 11 (central bicycle + 4 quad cells + 6 bi cells) 13 (central bicycle + 6 quad cells + 6 bi cells) 15 (central bicycle + 8 quad cells + 6 bi cells) 17 (central bicycle + 10 quad cells + 6 bicells) 19 (central bicycle + 12 quad cells + 6 bicells) ... Electrode number 29 37 45 53 61 69 ...

Table 6 shows the number of electrodes according to the increase in the number of stacks in the stack-folding type electrode assembly according to the present invention, in which the A type or C type bi-cell is a central bi-cell and includes at least one pair of quad cells and four pairs of bi- .

Number of stacks 11 (central bicycle + 2 quad cells + 8 bicells) 13 (central bicycle + 4 quad cells + 8 bicells) 15 (central bicycle + 6 quad cells + 8 bi-cells) 17 (central bicycle + 8 quad cells + 8 bi-cells) 19 (central bicycle + 10 quad cells + 8 bi-cells) 21 (central bicycle + 12 quad cells + 8 bicells) ... Electrode number 35 43 51 59 67 75 ...

By using these various combinations, it is possible to design a cell in which the number of electrodes increases by two in accordance with the increase in the number of stacks. Therefore, there is no restriction on the change in stack number for cell performance such as thickness, capacity, resistance, and the degree of design freedom is high.

Hereinafter, the degree of freedom of design increase and the cell designing step of the present invention will be described in more detail.

FIG. 7 illustrates possible cell designs in the case where the number of stacks is 11 or more in the electrode assembly according to the present invention. FIGS. 7A to 7E schematically show the cell internal lamination structure, Together.

The electrode assembly of FIG. 7 is a case in which (a), (b), (c) and (d) constitute a basic design loop and (e) (a) to (e), the unit cells located above and below the center cell are symmetrical with respect to their electrode directions. It includes all quad cell, A type bi-cell, and C type bi-cell.

First, (a) shows that the central bicycle is an A-type bi-cell and two pairs of C-type bi-cells and a pair of A-type bi-cells are stacked with two pairs of quad cells on the upper and lower sides, The number is 11. (b) shows a case where the central bicycle is a C type bicycle and a pair of C type bi-cells and a pair of A type bi-cells are arranged on the upper and lower sides of the central bicycle, and a pair of quad cells And the same number of stacks is included. (c) shows a structure in which a central bi-cell is an A-type bi-cell and a pair of C-type bi-cells are vertically arranged on the basis of the central bi-cell and two pairs of quad- to be. (D) shows that the central bicycle is a C-type bi-cell and two pairs of C-type bi-cells, two pairs of A-type bi-cells, and a quad cell (a) And the number of stacks is increased by two to 13.

The next in (e) is shown as returning to the beginning of the loop (a) and further including a pair of quad cells at the winding center. Although not shown, the next cell is a case where a pair of quad cells is further included in the winding center by returning to (b), and the next cell is returned to (c) ), And a pair of quad cells is further included in the winding center. Repeating the loop in this way increases the number of electrodes by two and increases the number of stacks by 11, 13. In this manner, as the number of stacks increases, the cell design may repeat the loop and proceed to a configuration that further includes a quad cell, an A-type bi-cell or a C-type bi-cell in the outermost portion of the electrode assembly, the winding center, or in the middle of the stack.

That is, a basic design loop including the electrode assemblies in which the number of electrodes increases by two in the same stack number, a basic design loop composed of the above-mentioned examples (a) to (d), and then, A cell design in which the number of electrodes is increased by two while adding a quad cell, a C type bi-cell or an A type bi-cell to the outermost portion of the electrode assembly, the winding center portion, or the middle of the stack.

In the case of FIG. 7, the case where the bi-cell is located at the outermost periphery of the electrode assembly is taken as an example. The electrode assembly may have a structure in which the bi-cell is stacked on the winding central portion as shown in FIG. 8, or may have a structure located in the middle of the stack of the bi-cell as shown in FIG.

7 to 9 illustrate the case where the bi-cells are continuously arranged. However, the bi-cells may be disposed discontinuously as shown in FIG. 10 as the quad cells are inserted in the middle.

In FIGS. 8 to 10, which are modifications of FIG. 7, (a) to (d) constitute one loop, and then a pair of quad cells is further added to (a).

Table 7 below summarizes the number of stacks and the number of electrodes in the case of Fig.

Number of stacks (Examples) 11 11 11 13 13 Electrode number (example) 37 39 41 43 45 Stack count converted to conventional electrode assembly 12.33 (*) 13.00 13.67 (*) 14.33 (*) 15.00

(a) to (c) show 11 stacks, and (d) 13 stacks.

It can be seen that the number of electrodes can be increased by two in order of 37, 39, 41, 43, and 45.

(a) to (e) are 12.33, 13.00, 13.67, 14.33 and 15.00 in terms of the number of stacks of the conventional stack-folding electrode assembly. As indicated by an asterisk (*), 12.33, 13.67, and 14.33 are the number of stacks that can not be implemented in a stack-folding electrode assembly that is conventionally composed of bi-cells.

As described above, according to the present invention, it is possible to design the number of electrodes to increase by two, so that the number of electrodes can be finely adjusted and the degree of freedom in designing is higher than that in the prior art in which the number of electrodes is increased by six. It is possible to realize a number of stacks which can not be implemented with the conventional stack-folding electrode assembly, and in addition, even if the same number of electrodes is used, the number of stacks is actually smaller and the number of times of lamination and folding is reduced But the number of stacks converted into the existing structure is larger than 12.33 to 13.67). Accordingly, the folding dimensional tolerance and the defective ratio can be reduced, and the lamination and folding process time can be reduced.

As described above, the present invention is not limited to simply forming an electrode assembly with a quad-cell or a bi-cell combination, and it should not be overlooked that the cell configuration and the number of times of folding are reduced through the combination of the quad cell and the bi-cell.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but many variations and modifications may be made without departing from the spirit and scope of the invention as defined in the appended claims. It will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the scope of the appended claims.

110, 213, 214 ... A type bi-cell 111, 112, 211, 212 ... quad cell
113, 114, 210, 215, 216 ... C type bi-
120, 220 ... folding separator sheet 125, 225 ... tape

Claims (17)

An electrode assembly having a structure in which a plurality of stacked unit cells are stacked and a continuous folding separator sheet is interposed in each of the stacked units,
The unit cells necessarily include a quad cell having a structure of a cathode / separator / cathode / separator / cathode / separator / cathode, and a cathode / separator / anode / separator / Further comprising an A-type bi-cell of a cathode / separator / anode structure or a combination thereof. The stack-folding electrode assembly of claim 1, wherein the cathode is located at an outermost periphery of the electrode assembly. The folding membrane module according to claim 1, wherein the folding separator sheet has a unit length capable of wrapping the unit cells, and the folding separator sheet is folded inward for each unit length and starts from the center unit cell and continuously covers the unit cells at the outermost unit. - Folding type electrode assembly. The stack-folding type electrode assembly according to claim 1, wherein the C-type bi-cell or the A-type bi-cell is located at the center of the overlapped unit cells. The stack-folding type electrode assembly according to claim 4, wherein the unit cells located above and below the center bi-cell have their electrode directions symmetrical to each other. 5. The stack-folding type electrode assembly of claim 4, wherein the unit cells located on the upper and lower sides of the central bi-cell are a quad cell and a bi-cell combination. A secondary battery comprising a stack-folding type electrode assembly according to claim 1. A method of manufacturing a stack-folding type electrode assembly according to claim 1,
Positioning the central unit cell at the first end of the folding separator sheet and successively positioning the unit cells at a predetermined interval; And
Folding the folded separator sheet to the outer side where the adjacent unit cells are located after folding the central unit cell once with the folding separator sheet, and stacking and folding each unit cell Assembly. 9. The method of claim 8, wherein a cathode is positioned at an outermost periphery of the electrode assembly. 9. The method of claim 8, wherein the central unit cell is a C-type bi-cell or an A-type bi-cell. 11. The method of claim 10, wherein the unit cells located above and below the center bi-cell are positioned such that their unit cells are symmetrical. 11. The method of claim 10, wherein the unit cells located on the upper and lower sides of the central bi-cell are a combination of a quad cell and a bi-cell. A method of fabricating a stack-folding electrode assembly according to claim 1, comprising the steps of: creating a basic design loop comprising electrode assemblies in which the number of electrodes increases by two in the same stack number, Forming a cell design in which the number of electrodes is increased by two while adding a cell or an A-type bi-cell. 14. The method of claim 13, wherein the additional cell is inserted into an outermost, winding center, or stack intermediate position of the electrode assembly included in the basic design loop. 14. The method of claim 13, wherein the basic design loop
(a) a structure in which two pairs of C type bi-cells and a pair of A type bi-cells are stacked with one or more pairs of quad cells on the upper and lower sides with respect to the central bi-cell,
(b) the central bicycle is a C-type bicycle and a pair of C-type bi-cells and a pair of A-type bi-cells are vertically arranged on the basis of the central bicycle, and a pair of quad- The same number of stacks,
(c) a structure in which a central bi-cell is an A-type bi-cell and a pair of C-type bi-cells are vertically arranged on the basis of the central bi-cell and two pairs of quad- And
(d) a central bicycle is a C-type bi-cell and two pairs of C-type bi-cells, two pairs of A-type bi-cells, and quad cells as in (a) And the number of stacks is increased by two. 16. The method of claim 15, wherein the electrode assembly is inserted at an outermost position, a winding center, or an intermediate stack position. 16. The method of claim 15, wherein the arrangement of the A-type bi-cell and the C-type bi-cell is continuous or discontinuous.

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