KR20210140997A - Electrode assembly - Google Patents

Abstract

The present invention relates to an electrode assembly to suppress defects due to swelling. According to one aspect of the present invention, the electrode assembly comprises: an electrode stack in which a first separator, a first electrode sheet, a second separator, and a second electrode sheet are sequentially stacked; a can accommodating the electrode stack inside; and a first space maintenance member disposed in a first space formed in the circumferential direction of the electrode stack from at least one of both ends of the first electrode sheet to suppress the first space from getting narrow. According to another aspect of the present invention, the electrode assembly comprises: an electrode stack wound in a form in which a base material, an electrode sheet in which an active material is laminated on the base material, and a separator are alternately stacked; a can accommodating the electrode stack inside; an electrode tab providing one side to an uncoated region, on which the active material is not laminated, on the base material; and a second space maintenance member disposed in a second space formed in the circumferential direction of the electrode stack from one side of the electrode tab to suppress the second space from getting narrow.

Description

Electrode assembly {ELECTRODE ASSEMBLY}

The present invention relates to an electrode assembly, and more particularly, to an electrode assembly having a wound-type electrode stack capable of suppressing defects caused by swelling.

Secondary batteries, unlike primary batteries, are rechargeable, and have been widely researched and developed in recent years due to their small size and large capacity. As technology development and demand for mobile devices increase, the demand for secondary batteries as an energy source is rapidly increasing.

The secondary battery is classified into a coin-type battery, a cylindrical battery, a prismatic battery, and a pouch-type battery according to the shape of the battery case. In a secondary battery, an electrode stack mounted inside a battery case is a charging/discharging power generating element having a stacked structure of electrodes and a separator.

The electrode assembly is a jelly-roll type in which a separator is interposed between a sheet-type positive electrode and a negative electrode coated with an active material, a stack type in which a plurality of positive electrodes and negative electrodes are sequentially stacked with a separator interposed therebetween, and a stack It can be roughly classified into a stack/folding type in which unit cells of the type are wound with a long-length separation film. Among them, the jelly roll type electrode assembly is widely used because it is easy to manufacture and has the advantage of high energy density per weight.

The above-mentioned background art is technical information that the inventor possessed for the derivation of the embodiments of the present invention or acquired in the process of derivation, and it cannot be said that it is necessarily known technology disclosed to the general public prior to the filing of the embodiments of the present invention. none.

Korean Patent Publication No. 10-2013-0020550 Republic of Korea Patent Publication No. 10-2017-0117653 Korean Patent Publication No. 10-2019-0027527

The present invention has been devised to solve the above-described problem, and an object of the present invention is to provide an electrode assembly having a wound-type electrode stack capable of suppressing defects caused by swelling.

However, the problems to be solved by the present invention are not limited to the above-mentioned problems, and other problems not mentioned will be clearly understood by those skilled in the art from the following description.

An electrode assembly according to an embodiment of an aspect of the present invention includes: an electrode laminate wound in a sequentially stacked form in which a first separator, a first electrode sheet, a second separator, and a second electrode sheet are sequentially stacked; a can accommodating the electrode stack body therein; and a first space holding member disposed in a first space formed from at least one of both ends of the first electrode sheet in a circumferential direction of the electrode stack to suppress the narrowing of the first space. can

In this embodiment, the first space portion and the first space maintaining member may be positioned between the first separation membrane and the second separation membrane.

In this embodiment, the first space maintaining member may be a tape.

An electrode assembly according to another aspect of the present invention includes: an electrode stack wound in a form in which a base material, an electrode sheet in which an active material is laminated on the base material, and a separator are alternately stacked; and a can for accommodating the electrode laminate therein, comprising: an electrode tab provided with one side of an uncoated region on which the active material is not laminated on the base material; and a second space maintaining member disposed in the second space formed from one side of the electrode tab along the circumferential direction of the electrode stack to suppress the narrowing of the second space.

In this embodiment, the second space portion and the second space maintaining member may be located between the base material and the separation membrane.

In this embodiment, the second space maintaining member may be a tape.

According to the embodiment of the present invention, it is possible to suppress the narrowing of the space formed in the electrode stack and/or the electrode assembly due to swelling during charging.

1 is an exploded perspective view illustrating a secondary battery to which a conventional electrode assembly is applied.
2 is a side view conceptually illustrating a state in which a conventional electrode stack is unfolded before being wound.
3 is a cross-sectional view of a model schematically illustrating a non-charging state of a secondary battery having a conventional electrode laminate in a wound shape.
4 is a cross-sectional view of a model schematically illustrating a state in which swelling occurs during charging of a secondary battery having a conventional electrode stack in a wound shape.
5 is a cross-sectional view of a model schematically illustrating a non-charging state of a secondary battery having an electrode stack according to an embodiment of the present invention.
6 is a cross-sectional view of a model schematically illustrating a state in which swelling occurs during charging of a secondary battery having an electrode stack according to an embodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention will become apparent with reference to the embodiments described below in detail in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in a variety of different forms, and only these embodiments allow the disclosure of the present invention to be complete, and common knowledge in the technical field to which the present invention belongs It is provided to fully inform the possessor of the scope of the invention, and the present invention is only defined by the scope of the claims.

On the other hand, the terms used herein are for the purpose of describing the embodiments and are not intended to limit the present invention. As used herein, the singular also includes the plural unless specifically stated otherwise in the phrase. As used herein, "comprises" and/or "comprising" refers to the presence of one or more other components, steps, operations and/or elements mentioned. or addition is not excluded. Terms such as first, second, etc. may be used to describe various elements, but the elements should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another.

1 is an exploded perspective view showing a secondary battery to which a conventional electrode assembly is applied, FIG. 2 is a side view conceptually illustrating an unfolded state before a conventional electrode stack is wound, and FIG. 3 is a conventional electrode stack in a wound form. It is a cross-sectional view of a model that schematically illustrates a non-charging state of a secondary battery having a.

1 to 3 , a typical electrode assembly 100 may include an electrode stack 110 , a can 120 , and electrode tabs 130 and 140 .

The electrode stack 110 may be accommodated in the can 120 to constitute a secondary battery. In this case, the electrolyte may be accommodated in the can 120 .

The electrode stack 110 is a power generating element capable of charging and discharging, in which a first separator 111 , a first electrode sheet 112 , a second separator 113 , and a second electrode sheet 114 are sequentially stacked. It can be wound and formed. The electrode laminate 110 in the wound state is formed by stacking a first separator 111, a first separator 111, a first electrode sheet 112, a second separator 113, and a second electrode sheet 114. forms a group of and the groups are continuously stacked. In this case, the electrode stack 110 may be wound in a circular or oval shape, for example.

The first electrode sheet 112 and the second electrode sheet 114 may be a positive electrode sheet and a negative electrode sheet, respectively. In addition, the first separator 111 and the second separator 113 separate and electrically insulate the first electrode sheet 112 and the second electrode sheet 114 . Here, the electrode sheets 112 and 114 may be wound together with the separators 111 and 113 to form a jelly roll type.

The electrode sheets 112 and 114 may include base materials 1121 and 1141 and electrode active materials 1122, 1123, 1142, and 1143 stacked on the base materials 1121 and 1141. Here, the electrode sheets 112 and 114 have electrode active materials 1122, 1123, 1142, 1143 coated on the base materials 1121 and 1141, and the electrode active materials 1122, 1223, An uncoated region N to which 1142 and 1143 are not applied may be formed. The position of the uncoated region N on the base materials 1121 and 1141 is not particularly limited, and may be variously located according to a design model.

Meanwhile, in the first electrode sheet 112 corresponding to the positive electrode sheet, the base material 1121 (the first base material) may be made of, for example, aluminum (Al) material.

The positive electrode active materials 1122 and 1123 stacked on the first base material 1121 may be made of lithium manganese oxide, lithium cobalt oxide, lithium nickel oxide, lithium iron phosphate, or a compound or mixture containing at least one of them. .

In this case, the positive electrode tab 130 may be provided in the uncoated region N1 to which the positive electrode active materials 1122 and 1123 are not applied. That is, the positive electrode tab 130 may be fixed such that one side is electrically connected to a portion of the first base material 1121 that is the uncoated portion of the first electrode sheet 112 to which the positive electrode active materials 1222 and 1123 are not applied.

The second electrode sheet 114 corresponding to the negative electrode sheet, the base material 1141 (the second base material) may be made of, for example, a foil made of copper (Cu) or nickel (Ni) material.

The negative active materials 1142 and 1143 laminated on the second base material 1141 are made of artificial graphite, lithium metal, lithium alloy, carbon, petroleum coke, activated carbon, graphite, silicon compound, tin compound, titanium compound, or an alloy thereof. can In this case, the negative active materials 1142 and 1143 may further include, for example, non-graphite-based SiO (silica, silica) or SiC (silicon carbide, silicon carbide).

In this case, the negative electrode tab 140 may be provided in the uncoated region N2 to which the negative electrode active materials 1142 and 1143 are not applied.

The separators 111 and 113 are made of an insulating material and are alternately stacked with the first electrode sheet 112 and the second electrode sheet 114 . Here, the separators 111 and 113 may be located between the first electrode sheet 112 and the second electrode sheet 114 and on the outer surfaces of the first electrode sheet 112 and the second electrode sheet 114 . . The separators 111 and 113 may be made of, for example, polypropylene (PP) or polyethylene (PE).

Referring to FIG. 3A , on the electrode laminate 110 , the electrode laminate is spaced apart from at least one end 112a of both ends of the first electrode sheet 112 and from the first electrode sheet 112 . A first space portion 150a may be formed along the circumferential direction of 110 .

One first space portion 150a is an electrode spaced apart from the first electrode sheet 112 from the first end portion 112a of the first electrode sheet 112 close to the center of the wound electrode laminate 110 . It may be formed along the circumferential direction of the laminate 110 . Here, the first space portion 150a may be positioned between the first separation membrane 111 and the second separation membrane 113 .

Although not shown in detail in FIG. 3 , even on the outermost side of the electrode stack 110 , along the circumferential direction of the electrode stack 100 spaced apart from the first electrode sheet 112 from the other end of the first electrode sheet 112 . A first space portion 150a may be formed.

As shown in FIG. 2, the formation of the first space part is formed in the first electrode sheet (or the length of the first separator 111 and the second separator 113) in the unfolded state before the electrode stack 110 is wound. Since the length of the 112 is short, the first electrode sheet 112 is not disposed between one end of the first separator 111 and one end of the second separator 113 , In the circumferential direction of the electrode stack 110 spaced apart from the first electrode sheet 112 from the first end 112a or the second end 112b of the first electrode sheet 112 during winding, the first separator The first space portions 150a and 150b in a state in which 111 and the second separation membrane 113 are spaced apart are formed.

As the distance from the first electrode sheet 112 in the circumferential direction of the electrode laminate 110 from the first end 112a or the second end 112b of the first electrode sheet 112 increases, the first space portion 150a, 150b), the gap between the first separator 111 and the second separator 113 may be narrowed, and the first separator 111 and the second separator 113 may be in close contact with each other at a predetermined point.

Referring to FIG. 3B , the negative electrode tab 140 may be disposed on the uncoated area N2 on the second end 1141b side of the base material 1141 constituting the second electrode sheet 114 .

In addition, referring to FIG. 3C , the positive electrode tab 130 may be disposed on any uncoated area N1 on the base material 1121 constituting the first electrode sheet 112 .

On the electrode stack 110 , from one side of the electrode tabs 130 and 140 , along the circumferential direction of the electrode stack 110 spaced apart from the electrode sheets 112 and 114 on which the electrode tabs 130 and 140 are disposed. Second space portions 160a and 160b may be formed.

Specifically, referring to (c) of FIG. 3 , on the wound electrode stack 110 , the second space 160b is disposed along the circumferential direction of the electrode stack 110 from both sides of the positive electrode tab 130 . can be formed. Here, the second space 160b may be positioned between the base material 1121 of the first electrode sheet 112 and the second separator 113 .

In addition, referring to FIG. 3B , on the wound electrode stack 110 , it is formed between the positive electrode tabs 130 from both sides of the negative electrode tab 140 along the circumferential direction of the electrode stack 110 . A second space portion 160a may be formed such as the second space portion 160b.

Meanwhile, since the circumferential direction of the electrode stack 110 includes both a clockwise circumferential direction and a counterclockwise circumferential direction, two second space portions 160b are formed on both sides of the positive electrode tab 130 . In the same way, two second space portions 160a may be formed on both sides of the negative electrode tab 140 .

4 is a cross-sectional view of a model schematically illustrating a state in which swelling occurs during charging of a secondary battery having a conventional electrode stack in a wound shape.

During charging of the secondary battery, swelling may occur in each layer inside the electrode stack 110 .

In this case, the space of the first space 150a and/or the second space 160a and 160b may be narrowed by swelling of the respective layers. As the space of the first space portion 150a and/or the second space portion 160a, 160b becomes narrower, the electrolyte inside the can 120 does not permeate evenly into the electrode stack 110 or is discharged even if it permeates. If this is not done normally, by-products may be generated. The generation of these by-products has adverse effects such as reducing the output of the secondary battery.

5 is a cross-sectional view of a model schematically illustrating a non-charging state of a secondary battery having an electrode stack according to an embodiment of the present invention.

Since most of the configuration of the electrode assembly 100 ′ and/or the electrode stack 110 ′ according to an embodiment of the present invention is the same as that of the conventional electrode assembly 100 and/or the electrode stack 110 , the following In this section, we will focus on the differences.

Referring to FIG. 5 , the electrode assembly 100 ′ according to an embodiment of the present invention may further include a first space maintaining member 170 as compared to the conventional electrode assembly 100 .

The first space maintaining member 170 may be disposed in the first space portion 150a to prevent the first space portion 150a from being narrowed. Specifically, the first space maintaining member 170 may be positioned between the first separation membrane 111 and the second separation membrane 113 . The first space maintaining member 170 may be provided as a tape, specifically, an adhesive tape having an adhesive interposed on at least one surface thereof, wherein the adhesive is the first space maintaining member 170 including the first separation membrane 111 and the second adhesive tape. Adhesive force may be provided to be fixedly positioned on at least one of the separation membranes 113 .

The electrode assembly 100 ′ according to an embodiment of the present invention may further include a second space maintaining member (not shown), such as the first space maintaining member 170 , compared to the conventional electrode assembly 100 . .

Similarly to the manner in which the first space holding member 170 is disposed in the first space portion 150a, the second space retaining member is disposed in the second space portions 160a and 160b, respectively, to form the second space portions 160a and 160b. can be prevented from narrowing.

Specifically, the second space maintaining member may be positioned between the base material 1121 of the first electrode sheet 112 or the base material 1141 of the second electrode sheet 114 and the second separator 113 . The second space maintaining member may be provided as a tape, specifically, an adhesive tape having an adhesive interposed on at least one surface thereof, wherein the adhesive is the second space maintaining member comprising at least one of the first separator 111 and the second separator 113 . Adhesion can be provided so that it can be fixedly positioned on one.

In FIG. 6, (a) is a cross-sectional view of a model schematically illustrating a state in which swelling occurs during charging of a secondary battery having a conventional electrode laminate, and (b) is an electrode laminate according to an embodiment of the present invention. It is a cross-sectional view of a model that schematically illustrates a state in which swelling occurs during charging of a secondary battery having a.

Referring to FIG. 6 , the first space 150a and the secondary battery having the conventional electrode stack shown in FIG. 4 without the first space retaining member 170 and/or the second space retaining member are less than in the case of the secondary battery. / Or it can be confirmed that the size of the space of the second space portion (160a, 160b) is better maintained.

Specifically, as shown in comparison with (a) and (b) of FIG. 6 , the gap d generated by separation between the first electrode sheet 112 and the second electrode sheet 114 by swelling is It can be seen that a decrease

According to the electrode assembly according to the embodiment of the present invention, it is possible to suppress the narrowing of the space that can be formed inside the electrode assembly, so that the electrolyte can well permeate between each layer during charging and also affect the reduction of output. Since the generation of possible by-products can be suppressed, there is an advantage in that the quality of the electrode assembly can be improved.

Although the present invention has been described with reference to the above-mentioned preferred embodiments, various modifications and variations are possible without departing from the spirit and scope of the invention. Accordingly, it is intended that the appended claims cover such modifications and variations as long as they fall within the scope of the present invention.

100: conventional electrode assembly 110: electrode laminate
111: first separator 112: first electrode sheet
113: second separator 114: second electrode sheet
1121, 1141: base material 1122, 1123: positive electrode active material
1142, 1143: negative active material 120: can
130: positive tab 140: negative tab
150a: first space 160a, 160b: second space
170: first space holding member N1, N2: uncoated part

Claims (6)

an electrode laminate in which a first separator, a first electrode sheet, a second separator, and a second electrode sheet are sequentially stacked;
a can accommodating the electrode stack body therein; and
Electrode including; assembly. According to claim 1,
The first space portion and the first space maintaining member are positioned between the first separator and the second separator. According to claim 1,
and the first space holding member is a tape. An electrode laminate wound in a form in which a base material, an electrode sheet in which an active material is laminated on the base material, and a separator are alternately stacked; And
As an electrode assembly comprising; a can for accommodating the electrode laminate therein,
an electrode tab in which one side is provided on the uncoated part on which the active material is not laminated on the base material; and
and a second space maintaining member disposed in a second space formed from one side of the electrode tab along a circumferential direction of the electrode stack to suppress the narrowing of the second space. 5. The method of claim 4,
The second space portion and the second space maintaining member are positioned between the base material and the separator, the electrode assembly. 5. The method of claim 4,
and the second space holding member is a tape.

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