Electrode assembly of novel structure and battery cell comprising the same

Abstract

Disclosed herein is an electrode assembly configured to have a structure in which a bi-cell and two or more monocells are folded in a state in which the bi-cell and the two or more monocells are arranged on a continuous separation film. The bi-cell includes electrodes in the form of at least one cathode and at least one anode stacked so that a separator is disposed between the cathode and the anode, the bi-cell having a first dimension in a first direction substantially equal to w. The two or more monocells each include electrodes in the form of at least one cathode and at least one anode stacked so that a separator is disposed between the cathode and the anode, each cathode and each anode of each monocell having a first dimension in the first direction substantially equal to 2 times the first dimension w of the bi-cell.

Claims

1. An electrode assembly comprising: a bi-cell including electrodes in the form of at least one cathode and at least one anode stacked so that a separator is disposed between the cathode and the anode with the electrodes located at opposite surfaces of the bi-cell being of a same electrical polarity, the bi-cell having a first dimension in a first direction substantially equal to w; two or more monocells, each monocell including electrodes in the form of at least one cathode and at least one anode stacked so that a separator is disposed between the cathode and the anode, the electrodes located at opposite surfaces of the monocell being of a different electrical polarity from each other, each cathode and each anode of each monocell having a first dimension in the first direction substantially equal to 2 times the first dimension w of the bi-cell; and a continuous separation film, the bi-cell disposed on a folding start region of the separation film; wherein each cathode and each anode of each monocell is in a folded state and has a width substantially equal to the first dimension w of the bi-cell in the folded state; wherein the two or more monocells include a first monocell and a second monocell; wherein each monocell includes a first portion having a width of the first dimension w, and a second portion having a width of the first dimension w, each monocell being folded between the first portion and the second portion; and wherein each monocell includes two electrode tabs disposed at the first portion.

2. The electrode assembly according to claim 1, wherein the bi-cell is disposed between the first and second portions of the first monocell, and the first monocell is disposed between the first and second portions of the second monocell.

3. The electrode assembly according to claim 1, wherein the bi-cell has a basic cathode (anode)/separator/anode (cathode)/separator/cathode (anode) stack structure.

4. The electrode assembly according to claim 1, wherein the monocell has a basic cathode (anode)/separator/anode (cathode) stack structure.

5. The electrode assembly according to claim 1, wherein each of the monocells are disposed on the separation film such that the first dimensions of the monocells are sequentially increased from the folding start region to a folding end region of the separation film.

6. The electrode assembly according to claim 1, wherein each of the monocells includes a notch on at least one surface at a location where the monocell is folded.

7. The electrode assembly according to claim 1, wherein the separation film is selected from a group consisting of micro porous polyethylene film, polypropylene film, multi-layered film prepared by a combination of the polyethylene film and the polypropylene film, and polymer film for a polymer electrolyte, such as polyvinylidene fluoride, polyethylene oxide, polyacrylonitrile, or polyvinylidene fluoride hexafluoropropylene copolymer.

8. The electrode assembly according to claim 1, wherein the separator is provided at opposite surfaces thereof with inorganic powder coated by a binder.

9. The electrode assembly according to claim 1, wherein the separation film is provided at one surface thereof contacting the bi-cell and the monocell with inorganic powder coated by a binder.

10. The electrode assembly according to claim 8, wherein the inorganic powder is selected from a group consisting of inorganic particles having a dielectric constant of 5 or more, inorganic particles having lithium ion transfer capability, and a mixture thereof and the inorganic particles have a particle diameter of 0.001 to 10 μm.

11. A battery cell comprising an electrode assembly according to claim 1.

12. The battery cell according to claim 11, wherein the battery cell is a secondary battery.

13. The battery cell according to claim 11, wherein the secondary battery is a lithium secondary battery having lithium ions as a carrier.

14. The battery cell according to claim 11, wherein the secondary battery is configured to have a structure in which an electrode assembly is mounted in a pouch-shaped case made of a laminate sheet comprising a metal layer and a resin layer.

15. A battery module comprising a battery cell according to claim 11 as a unit cell.

16. The electrode assembly according to claim 1, wherein the first monocell has a first dimension equal to n1 times the first dimension w of the bi-cell, and the second monocell has a first dimension equal to n2 times the first dimension w of the bi-cell, n1 and n2 being integers that are equal to or greater than 2, and n1 and n2 being different integers.

17. The electrode assembly according to claim 1, wherein the two electrode tabs of each monocell are disposed at exactly two positions on a same edge of the first portion along the first dimension of the monocell.

18. A method of forming an electrode assembly, the method comprising: placing a bi-cell on a folding start region of a continuous separation film, the bi-cell including electrodes in the form of at least one cathode and at least one anode stacked so that a separator is disposed between the cathode and the anode with the electrodes located at opposite surfaces of the bi-cell being of a same electrical polarity, the bi-cell having a first dimension in a first direction substantially equal to w; placing two or more monocells on the continuous separation film, each monocell including electrodes in the form of at least one cathode and at least one anode stacked so that a separator is disposed between the cathode and the anode, the electrodes located at opposite surfaces of the monocell being of a different electrical polarity from each other, each cathode and each anode of each monocell having a first dimension in the first direction substantially equal to 2 times the first dimension w of the bi-cell, wherein the two or more monocells include a first monocell and a second monocell, the first and second monocells disposed on the continuous separation film with the first monocell disposed between the bi-cell and the second monocell in the first direction along the continuous separation film; and folding each monocell over itself to have a width substantially equal to the first dimension w of the bi-cell in the folded state, wherein each monocell includes a first portion having a width of the first dimension w, and a second portion having a width of the first dimension w, each cathode and each anode of each monocell being folded between the first portion and the second portion, and the each monocell includes two electrode tabs disposed at the first portion.

19. The method according to claim 18, wherein the bi-cell is disposed between the first and second portions of the first monocell, and the first monocell is disposed between the first and second portions of the second monocell.

Description

DESCRIPTION OF DRAWINGS

(1) The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

(2) FIG. 1 is a series of perspective views showing an exemplary process for preparing a conventional stacked/folded type electrode assembly;

(3) FIG. 2 is a graph typically showing the change in thickness and capacity of the conventional stacked/folded type electrode assembly due to the increase in number of stacks;

(4) FIG. 3 is a series of typical views showing a bi-cell and monocells of a stacked/folded type electrode assembly according to an embodiment of the present invention; and

(5) FIGS. 4 and 5 are typical views showing manufacturing processes of stacked/folded type electrode assemblies according to exemplary embodiments of the present invention.

(6) FIG. 4A is a side view of an exemplary electrode assembly that may result from folding the bi-cell and first two monocells of FIG. 4 in the direction of the arrow.

BEST MODE

(7) Now, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted, however, that the scope of the present invention is not limited by the illustrated embodiments.

(8) FIG. 3 is a series of typical views typically showing a bi-cell and monocells of a stacked/folded type electrode assembly according to an embodiment of the present invention.

(9) Referring to FIG. 3, the stacked/folded type electrode assembly according to the embodiment of the present invention includes, for example, a bi-cell 100 having an anode/separator/cathode/separator/anode stack structure and various sized monocells 110, 120, and 130 each including one cathode and one anode.

(10) The bi-cell 100 has a width W, which is a basic folding width. The monocell 110 has a width 2W equivalent to twice the basic width W of the bi-cell 100. The monocell 120 has a width 3W equivalent to three times the basic width W of the bi-cell 100.

(11) FIGS. 4 and 5 are typical views showing manufacturing processes of stacked/folded type electrode assemblies according to exemplary embodiments of the present invention. FIG. 4A illustrates a bi-cell 100, monocells 110a and 110b, and the continuous separation film 200 having a first end 201 and a surplus portion 300 fixed to another portion of the continuous separation film. The bi-cell 100 is disposed between first and second portions of the monocell 110a, and the monocell 110a is disposed between first and second portions of the monocell 110b. The monocells 100a and 100b each are folded at a location 113.

(12) Referring to these drawings together with FIG. 3, a bi-cell 100, which is a unit cell having an anode/separator/cathode/separator/anode stack structure, and a plurality of monocells 110 or 120 are arranged on a long continuous separation film 200 such that cathode tabs 101 face each other while anode tabs 102 face each other at stack interfaces therebetween when the bi-cell 100 and the monocells 110 or 120 are folded (in a direction as indicated by an arrow). Specifically, the monocells 110 or 120 are sequentially arranged in a state in which the first one of the monocells 110 or 120 is spaced apart from the bi-cell 100 by the basic width W.

(13) Each of the monocells 110 or 120 has one cathode B and one anode A although each of the monocells 110 or 120 is folded. A notch 113 or 123 to partition each of the monocells 110 or 120 into equal parts is formed at each of the monocells 110 or 120 such that each of the monocells 110 or 120 can be easily folded.

(14) The number of the monocells 110 and 120 and the number of the cathodes B and the anodes A are shown in Table 2 below.

(15) TABLE-US-00002 TABLE 2 1 2 N Cath- An- Cath- An- Cath- An- odes odes odes odes . . . odes odes Double 3 4 5 6 . . . 2N + 1 2N + 2 monocell Triple 4 5 7 8 . . . 3N + 1 3N + 2 monocell . . . M-fold M + 1 M + 2 2M + 1 2M + 2 . . . M .Math. N + M .Math. N + monocell 1 2

(16) As can be seen from Table 2 above, a combination of the bi-cell 100 and the monocell 110 includes three cathodes B and four anodes A. That is, the number of the monocells 110 having the same length is increased, the numbers of the cathodes B and the anodes A are increased by 2N+1 and 2N+2, respectively.

(17) In the same manner, a combination of the bi-cell 100 and the monocell 120 includes four cathodes B and five anodes A. That is, the number of the monocells 120 having the same length is increased, the numbers of the cathodes B and the anodes A are increased by 3N+1 and 3N+2, respectively.

(18) On the other hand, the number of the monocells 110 and 120 and the number of electrode tabs 111, 112, 121, and 122 as the cathode tabs and the anode tabs based on arrangement of the monocells 110 and 120 are shown in Table 3 below.

(19) TABLE-US-00003 TABLE 3 1 2 N Cathode Anode Cathode Anode Cathode Anode tabs tabs tabs tabs . . . tabs tabs Double 2 3 3 4 . . . N + 1 N + 2 monocell Triple 2 3 3 4 . . . N + 1 N + 2 monocell . . . M-fold 2 3 monocell

(20) As can be seen from Table 3 above, a combination of the bi-cell 100 and the monocell 110 includes two cathode tabs 101 and 111 and three anode tabs 102 and 112. That is, the number of the monocells 110 having the same length is increased, the numbers of the cathode tabs 101 and 111 and the anode tabs 102 and 112 are increased by N+1 and N+2, respectively.

(21) In the same manner, a combination of the bi-cell 100 and the monocell 120 includes two cathode tabs 101 and 111 and three anode tabs 102 and 112. That is, the number of the monocells 120 is increased, the numbers of the cathode tabs 101 and 111 and the anode tabs 102 and 112 are increased by N+1 and N+2, respectively.

(22) Consequently, it can be seen that the number of the electrode tabs is considerably reduced as compared with Table 1 showing the number of the electrode tabs based on stacking of the electrodes of the conventional stacked/folded type electrode assembly.

(23) Meanwhile, a surplus portion 300 is formed at the outermost end, i.e. a folding end portion, of the separation film 200. The surplus portion 300 is fixed by thermal bonding or using an adhesive tape.

(24) Although the exemplary embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

INDUSTRIAL APPLICABILITY

(25) As is apparent from the above description, a battery cell according to the present invention is manufactured by arranging a bi-cell and one or more monocells configured to be folded by a desired number of times in response to the width of the bi-cell on a continuous separation film and folding the bi-cell and the monocells. Consequently, it is possible to increase capacity of the battery cell, thereby greatly improving energy density of the battery cell. In addition, the monocells are configured to be folded by a large number of times in response to the width w of the bi-cell. Consequently, it is possible to considerably reduce the number of electrode tabs as compared with a conventional stacked/folded type electrode assembly, thereby greatly improving welding process ability.