Patent ID: 12224453

DESCRIPTION OF SYMBOLS

10: negative electrode20: positive electrode22: insulating member24: adhesive layer30: separator100,101,102,103,104,105,106,107: electrode assembly200,201,202,203,204,205,206,207: fixing member300: nozzle-type applicator

DETAILED DESCRIPTION

The present invention will be described more fully herein with reference to the accompanying drawings, in which some example embodiments of the invention are shown. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention.

To clearly describe the present invention, parts that are irrelevant to the description may be omitted, and like reference numerals refer to like or similar constituent elements throughout the specification.

Further, since sizes and thicknesses of constituent elements shown in the accompanying drawings may be arbitrarily shown for better understanding and ease of description, the present invention is not limited to the illustrated sizes and thicknesses.

In the drawings, the thicknesses of layers, films, panels, regions, etc., may be exaggerated for clarity. In the drawings, for better understanding and ease of description, the thicknesses of some layers and areas may be exaggerated. It is to be understood that when an element, such as a layer, film, region, or substrate, is referred to as being “on” another element, it may be directly on the other element or one or more intervening elements may also be present.

In addition, unless explicitly described to the contrary, the word “comprise” and variations, such as “comprises” or “comprising,” are to be understood to imply the inclusion of stated elements but not the exclusion of any other elements. Further, in the specification, the word “on” means positioning on or below the object portion, but does not necessarily mean positioning on the upper side of the object portion based on a gravity direction.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which example embodiments of the inventive concept belong. It is to be further understood that terms, such as those defined in commonly-used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

Herein, a rechargeable battery according to an embodiment of the present invention will be described in further detail with reference to the accompanying drawings.

FIG.1illustrates a schematic layout view of an electrode assembly according to an embodiment of the present invention;FIG.2illustrates a cross-sectional view taken along the line II-II ofFIG.1; andFIG.3illustrates a cross-sectional view taken along the line III-III ofFIG.1.

As illustrated inFIGS.1to3, an electrode assembly100according to an embodiment of the present invention is a stacked electrode assembly in which a negative electrode10and a positive electrode20are repeatedly stacked with a separator30interposed therebetween.

The separator30is a polymer film through which lithium ions pass, and may include, for example, a polyolefin series.

The negative electrode10includes an electrode region1formed by coating an active material on a current collector of a thin metal plate, and an uncoated region3where the thin metal plate is exposed by not coating an active material thereon. In an embodiment, a thin metal plate of the negative electrode may be a thin copper (Cu) plate.

The positive electrode20includes an electrode region2formed by coating an active material on a current collector of a thin metal plate, and an uncoated region4where the thin metal plate is exposed by not coating an active material thereon. In an embodiment, a thin metal plate of the positive electrode may be a thin aluminum (Al) plate.

A plurality of respective uncoated regions3and4of a same polarity may be electrically connected to an outer terminal. The uncoated region4of the positive electrode20and the uncoated region3of the negative electrode10may protrude in opposite directions as illustrated inFIG.1, but the present invention is not limited thereto, and, in an embodiment, they may protrude in a same direction to be spaced apart from each other.

In an embodiment, the electrode assembly100is formed by repeatedly stacking the plurality of positive electrodes20and negative electrodes10with the separators30therebetween, and, thus, they may be fixed by using a fixing member200to maintain an aligned state after being stacked.

In an embodiment, the fixing member200has an elastic force and includes an adhesive layer made of a material having excellent adhesion to the separator30, and, in an embodiment, the adhesive layer may include a polyolefin grafted with maleic anhydride having excellent adhesion to the separator30made of a polyolefin-based series. In an embodiment, the polyolefin may be any of polypropylene, polyethylene, and ethylene vinyl acetate (EVA).

In an embodiment, the fixing member200may be formed at a regular interval along an edge of the separator30to facilitate penetration of an electrolyte solution into the electrode assembly100. In an embodiment, the fixing member200may be formed to overlap or form a linear shape (seeFIG.7) in a direction Y crossing at least one sidewall of the electrode assembly100, which is a substantially rectangular parallelepiped.

The separator30may be larger than the negative electrode10and the positive electrode20, and may protrude outward of the negative electrode10and the positive electrode20, while the fixing member200may be disposed at the edge of the separator30, which protrudes.

In an embodiment, the fixing member200may be formed at a same position in the direction Y in which a plurality of overlapping separators30overlap, that is, across the sidewalls. Accordingly, the fixing member200is fixed by contacting a first surface and a second surface of the separators30facing each other. In an embodiment, the fixing member200is disposed within the boundary of the separator30and does not protrude outward.

In one or more embodiments of the present invention, when the fixing member200is formed along the edge of the separator30, the contact area between the separator30and the fixing member200is increased to firmly hold the separator30, such that when a shock is applied to the electrode assembly100or it moves, the alignment of the positive electrode20, the negative electrode10, and the separator30of the electrode assembly100may be prevented or substantially prevented from being distorted.

In addition, according to one or more embodiments of the present invention, since the fixing member200has elasticity, even when the alignment is distorted due to an impact on the electrode assembly100, the fixing member200can be restored to its original alignment state by the elasticity of the fixing member200.

FIG.4illustrates a view for describing a method of forming the electrode assembly ofFIG.2andFIG.3.

As illustrated inFIG.4, the fixing member200may be formed by repeating processes of disposing the positive electrode20on the separator30, forming the fixing member200at the edge of the separator30, disposing the separator30and the negative electrode10, and forming the fixing member200at the edge of the separator30. In an embodiment, the process of forming the fixing member200includes applying a solution adhesive to the edge and curing it.

In an embodiment, the fixing member200may be formed of a solution-type adhesive capable of thermosetting or UV curing, and the fixing member200may be a material having excellent adhesion to the separator30but inferior adhesion to the metal sheets of the positive electrode20and the negative electrode10. In an embodiment, the fixing member200may include a polyolefin grafted with maleic anhydride. In this case, the polyolefin may be any of polypropylene, polyethylene, and ethylene vinyl acetate (EVA).

The solution-type adhesive may be applied to the separator30, and then move along the surface of the separator30. Therefore, after the solution-type adhesive is applied to the edge, viscosity and an amount of application of the solution-type adhesive may be adjusted so as to not contact the end of the positive electrode20or the negative electrode10while moving along the surface of the separator30.

In an embodiment, thermal curing or UV curing is rapidly performed after application to block the contact between the solution-type adhesive and the ends of the positive electrode20and the negative electrode10.

In an embodiment, the fixing member200is formed at a regular interval along the edge of the separator30, and is formed to overlap at a same position.

FIG.5illustrates a schematic cross-sectional view of an electrode assembly according to another embodiment of the present invention, taken along a line corresponding to the line III-III ofFIG.1.

Since the electrode assembly shown inFIG.5may be almost the same as that shown inFIG.2andFIG.3, only different parts may now be described in further detail.

As illustrated inFIG.5, an electrode assembly101includes the positive electrode20and the negative electrode10that are repeatedly stacked with the separator30interposed therebetween. The separator30is formed larger than the positive electrode20and the negative electrode10, and a protruding edge thereof is fixed in contact with a fixing member201.

In this case, the fixing member201may be formed to contact the end of the separator30as well as the surfaces of the separators30facing each other.

The fixing member200ofFIG.2andFIG.3is in contact with the surfaces of the separators30facing each other, while the fixing member201ofFIG.5is in contact not only with the surfaces of the separators30facing each other, but also with the ends of the separators30, and, thus, the area between the fixing member201and the separator30is wider.

As such, as the area in which the separator30and the fixing member201come into contact with each other is increased, the separators30may be more firmly fixed, and thus the alignment of the stacked electrode assembly101may be more effectively prevented from being misaligned.

FIG.6illustrates a view for describing a method of forming the electrode assembly ofFIG.5.

As illustrated inFIG.6, an electrode assembly in which the positive electrode20, the separator30, and the negative electrode10are stacked is prepared, and the solution-type adhesive is applied to the end of the separator30by using a nozzle-type applicator300, and then is cured to form the fixing member201.

In an embodiment, the fixing member201may include a solution-type adhesive capable of thermosetting or UV curing, and may include a material having excellent adhesion to the separator30but inferior adhesion to the metal sheets of the positive electrode20and the negative electrode10. In an embodiment, the fixing member201may include a polyolefin grafted with maleic anhydride. In this case, the polyolefin may be any of polypropylene, polyethylene, and ethylene vinyl acetate (EVA).

The solution-type adhesive may be applied to the separator30, and then move along the surface of the separator30. Therefore, after the solution-type adhesive is applied to the edge, a concentration and an amount of application of the solution-type adhesive may be adjusted so as to not contact the end of the positive electrode or the negative electrode while moving along the surface of the separator30.

In an embodiment, thermal curing or UV curing is rapidly performed after application to prevent or substantially prevent contact between the solution-type adhesive and the ends of the positive electrode and the negative electrode.

In an embodiment, since the fixing member201is applied by using the nozzle-type applicator300, the fixing member201may be formed in a continuous linear shape in the direction Y across a sidewall of the electrode assembly101, but the present invention is not limited thereto, and it may be formed discontinuously (not illustrated) at a regular interval along the direction Y crossing the sidewall or a longitudinal direction X of the sidewall.

FIG.7toFIG.10illustrate views for describing a fixing member according to other embodiments of the present invention.

As illustrated inFIG.7toFIG.10, a fixing member202,203,204,205may be formed across the sidewall of an electrode assembly102,103,104,105in various forms.

As illustrated inFIG.7, the fixing member202may be formed perpendicularly with respect to upper and lower surfaces of the electrode assembly102, or, as illustrated inFIG.8andFIG.9, a fixing member203or204may be formed to be inclined with respect to an upper surface or a lower surface of an electrode assembly103or104. In addition, as illustrated inFIG.10, a fixing member205may be formed to have a width W that is wider than that of the fixing members202,203, and204ofFIG.7toFIG.9.

In an embodiment, an area corresponding to the sidewall is formed to be 95% or less of a total sidewall area such that the fixing members202,203,204, and205do not block penetration of the electrolyte solution.

FIG.11illustrates a schematic cross-sectional view of an electrode assembly according to another embodiment of the present invention, taken along a line corresponding to the line III-III ofFIG.1.

Since the electrode assembly shown inFIG.11may be almost the same as that shown inFIG.3, only different parts may now be described in further detail.

As illustrated inFIG.11, an electrode assembly106includes the positive electrode20and the negative electrode10that are repeatedly stacked with the separator30interposed therebetween. The separator30is formed to be larger than the positive electrode20and the negative electrode10, and a fixing member206is attached to a protruding edge thereof.

The fixing member206may include an insulating member22and an adhesive layer24. Similar to the embodiment illustrated inFIG.5, the adhesive layer24may be formed to contact the end of the separator30as well as the surfaces of the separators30facing each other.

In addition, the insulating member22may be formed to surround upper and lower surfaces of the electrode assembly106together with the adhesive layer24. Accordingly, upper and lower end portions of the insulating member22on which the adhesive layer24is not formed may have adhesiveness and may be attached to the upper and lower surfaces of the electrode assembly106.

As in the above-described embodiment, when the insulating member22having adhesiveness is formed together with the adhesive layer24, the insulating member22is attached to the upper and lower surfaces of the electrode assembly106to fix the fixing member206and the upper and lower surfaces of the electrode assembly106, whereby an area contacted by the electrode assembly106may be increased to more firmly maintain the alignment of the electrode assembly106.

In embodiments, the electrode assembly described inFIG.11may be formed by methods ofFIG.12andFIG.13.

FIG.12andFIG.13illustrate views for describing a method of forming a fixing member in an electrode assembly according to embodiments of the present invention.

As illustrated inFIG.12, an electrode assembly107including the stacked positive electrode20, the separator30, and the negative electrode10and a fixing member207is prepared.

The fixing member207may include an adhesive layer24and an insulating member22. The fixing member207may have adhesiveness, and the adhesive layer24may be a hot melt adhesive that melts when a certain (e.g., predetermined) temperature is applied. Since the hot melt adhesive does not use an organic solvent, a risk due to the use of the organic solvent may be reduced.

In an embodiment, the adhesive layer24may include a polymer selected from the group consisting of cellulose, polyvinylidene fluoride-cohexafluoropropylene, polyvinylidene fluoridecotrichloroethylene, polymethylmethacrylate, polybutylacrylate, polybutylacrylate acrylonitrile, polyvinylpyrrolidone, polyvinylacetate, ethylene vinyl co-vinyl acetate, polyethylene oxide, polyarylate, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethylpullulan, cyanoethylpolyvinylalcohol, cyanoethylcellulose, cyanoethylsucrose, pullulan, carboxyl methyl cellulose, a maleic acid anhydride-polypropylene, and a mixture of two or more thereof, and, in an embodiment, may include polypropylene-maleic acid anhydride.

Thereafter, the fixing member207is disposed such that the adhesive layer22is disposed on a sidewall of the electrode assembly107and is heated to melt the adhesive layer24, and then the adhesive layer24is adhered to the separator30by removing the heat and curing it. In an embodiment, the adhesive layer24may be adhered between adjacent separators while being cured by UV.

The adhesive layer24may move to an end of the positive electrode20or the negative electrode10during curing depending on viscosity, and, thus, the thickness, viscosity, melting temperature, time, etc. of the adhesive layer24may be adjusted such that the adhesive layer24does not come into contact with the ends of the positive electrode20and the negative electrode10even when the adhesive layer24moves between the separators30. For example, the adhesive layer24may have viscosity of 500 cP or more. In the case of using heat, when the adhesive layer24is melted by heat to viscosity of 500 cP or more and then the heat is removed, the adhesive layer24may be cured before contacting the ends of the positive and negative electrodes. In an embodiment, when UV is used, the adhesive layer24may be formed using an adhesive having viscosity of 500 cP to prevent or substantially prevent the adhesive from moving during curing with UV.

In an embodiment, referring toFIG.13, the insulating member22having adhesiveness may be further attached onto an adhesive layer, which may be the fixing member201of the electrode assembly101illustrated inFIG.5.

In one or more embodiments, the above electrode assembly may be assembled as a rechargeable battery by being inserted into a can-shaped case (not illustrated) together with an electrolyte solution, and then sealing the case with a cap plate connectable to an external terminal.

While the present invention has been described in connection with what are presently considered to be some practical embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.