Separator Stack, Electrode Assembly Including Same, and Electrode Assembly Manufacturing Method

An electrode assembly according to an embodiment of the present invention includes: a separator stack which has a sealing portion formed in central regions of a plurality of separators stacked on each other, wherein the separator stack is folded about the sealing portion. A plurality of electrodes are inserted between respective pairs of the plurality of separators. The sealing portion may be positioned on one side of the plurality of electrodes. An electrode including the separator stack and a method of manufacturing the electrode assembly is also provided.

TECHNICAL FIELD

The present invention relates to a separator stack, an electrode assembly including same, and an electrode assembly manufacturing method.

BACKGROUND ART

In general, secondary batteries refer to chargeable and dischargeable batteries unlike primary batteries that are not chargeable, and have been widely used in electronic devices, such as mobile phones, laptops, and camcorders, or electric vehicles, etc. In particular, a lithium secondary battery has a larger capacity than a nickel-cadmium battery or a nickel-hydrogen battery and has a high energy density per unit weight, and thus the degree of utilization of the lithium secondary battery is rapidly increasing.

The lithium secondary batteries are classified according to the configuration of an electrode assembly having a structure of positive electrode/separator/negative electrode. Representative examples include a jelly-roll electrode assembly in which long sheet-shaped electrodes are wound with separators disposed therebetween, a stack-type electrode assembly in which a plurality of electrodes cut into a certain size are sequentially stacked on each other with separators disposed therebetween, and a stack/folding-type electrode assembly having a structure in which bi-cells or full-cells formed by stacking certain unit electrodes with separators disposed therebetween are wound.

SUMMARY OF THE INVENTION

Technical Problem

An object of the present invention is to provide an electrode assembly, which facilitates alignment of electrodes and has improved stability, and a separator stack included therein.

Another object of the present invention is to provide a method for manufacturing an electrode assembly using a novel stacking method of electrodes.

Technical Solution

A separator stack according to an embodiment of the present invention includes: a plurality of separators which are stacked on each other and each of which has a pair of first edges extending in a first direction and a pair of second edges extending in a second direction perpendicular to the first direction; and a sealing portion which is elongated in the second direction and formed as central regions of the plurality of separators in the first direction are sealed to each other.

The width of the sealing portion in the first direction may be reduced along the upward direction with respect to the stacking direction of the plurality of separators.

The pairs of second edges of the plurality of separators may be positioned further inward along the upward direction with respect to the stacking direction of the plurality of separators.

The sealing portion may have a shape symmetrical with respect to the first direction.

The plurality of separators may be folded about the sealing portion.

An electrode assembly according to an embodiment of the present invention includes: a separator stack which has a sealing portion formed in central regions of a plurality of separators stacked on each other, wherein the separator stack is folded about the sealing portion; and a plurality of electrodes inserted between the plurality of separators. The sealing portion may be positioned on one side of the plurality of electrodes.

At least some of the plurality of electrodes may be in contact with or close to the sealing portion.

The thickness of the sealing portion may be increased toward the central regions with respect to the stacking direction of the separator stack.

The sealing portion may have a shape symmetrical with respect to the stacking direction of the separator stack.

The outer surface of the sealing portion may be flat, or convexly bent or folded toward the outside of the separator stack.

The separator stack may have a sub-sealing portion which is positioned on the other side of the plurality of electrodes and in which the plurality of separators are sealed to each other, and the sub-sealing portion may have a shape asymmetrical with the sealing portion.

A separator stack according to another embodiment of the present invention includes: a base separator which has a pair of first edges extending in a first direction and a pair of second edges extending in a second direction perpendicular to the first direction; and a base material portion which is provided in a central region in the first direction of the base separator and elongated in the second direction; and a plurality of main separators which have fixed edges connected to the base material portion.

With respect to the first direction, some of the plurality of main separators may be spread toward one side, and the others may be spread toward the other side.

The base separator may be folded about the base material portion so that the plurality of main separators are gathered.

Non-fixed edges of the plurality of main separators on the opposite side from the fixed edges may be positioned further inward along the upward direction with respect to the stacking direction.

An electrode assembly according to another embodiment of the present invention includes: a separator stack in which edges of a plurality of main separators are fixed to a base material portion provided in a central region of a base separator, wherein the separator stack is folded about the base material portion; and a plurality of electrodes which are inserted between the base separator and the plurality of main separators. The base material portion may be positioned on one side of the plurality of electrodes.

The plurality of electrodes may be in contact with or close to the base material portion.

The thickness of the base material portion may be constant with respect to the stacking direction of the plurality of main separators.

The base material portion may be flat, or convexly bent or folded toward the outside of the separator stack.

The separator stack may have a sub-sealing portion which is positioned on the other side of the plurality of electrodes and in which the base separator and the plurality of separators are fused to each other, and the sub-sealing portion may have a shape asymmetrical with the base material portion.

An electrode assembly manufacturing method according to an embodiment of the present invention includes: preparing a separator stack in which central regions of a plurality of separators stacked on each other are sealed to each other to form a sealing portion; folding the separator stack about the sealing portion; and inserting a plurality of electrodes into spaces between the plurality of separators.

During the preparing of the separator stack, an operation of stacking another separator on the upper side of one separator and an operation of fusing central regions of the one separator and another separator to each other to form a sealing portion may be repeated. The width of the sealing portion may be reduced along the upward direction with respect to the stacking direction of the separator stack.

The electrode assembly manufacturing method may further include forming a sub-sealing portion by sealing the plurality of separators to each other on the opposite side from the sealing portion.

An electrode assembly manufacturing method according to another embodiment of the present invention includes: preparing a separator stack in which edges of a plurality of main separators are fixed to a base material portion provided in a central region of a base separator; folding the separator stack about the base material portion; and inserting a plurality of electrodes into spaces between the base separator and the plurality of main separators.

The electrode assembly manufacturing method may further include sealing edges of the base separator and plurality of main separators to each other, wherein the edges are positioned on the opposite side from the base material portion.

Advantageous Effects

According to the embodiments of the present invention, the manufacturing process is simplified, the manufacturing equipment is also simplified, compared to various methods for manufacturing electrode assemblies according to the related art.

Also, the separator stack that does not include the electrodes is manufactured first, and thus, the accurate alignment between the plurality of separators is possible. In addition, the plurality of electrodes are simultaneously or sequentially inserted into the separator stack, and thus, the accurate alignment between the plurality of electrodes is possible. Accordingly, the quality and energy density of the electrode assembly may be enhanced.

In addition, the sealing stability of the sealing portion or the base material portion provided in the separator stack is properly maintained, and thus, it is possible to prevent the plurality of electrodes from being separated from the separator stack. Accordingly, it is possible to prevent the occurrence of a short circuit between the plurality of electrodes and to improve the stability of the electrode assembly.

Furthermore, the thickness of the sealing portion or the base material portion provided in the separator stack is relatively smaller than the thickness of a separator sealing portion according to the related art, and thus, it is possible to efficiently dissipate heat from the plurality of electrodes.

In addition to the effects described above, effects that can be easily predicted by those skilled in the art from the configurations according to the embodiments of the present invention may be included.

DETAILED DESCRIPTION

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so as to be easily carried out by a person skilled in the art to which the present invention pertains. However, the present invention may be embodied in various different forms, and is neither limited nor restricted to the following embodiments.

In order to clearly describe the present disclosure, detailed description of parts irrelevant to the disclosure or detailed descriptions of related well-known technologies that may unnecessarily obscure subject matters of the disclosure will be omitted. In the specification, when reference numerals are given to components in each of the drawings, the same or similar components will be designated by the same or similar reference numerals throughout the specification.

Also, terms or words used in this specification and claims should not be restrictively interpreted as ordinary meanings or dictionary-based meanings, but should be interpreted as meanings and concepts conforming to the technical ideas of the present disclosure on the basis of the principle that an inventor can properly define the concept of a term so as to describe his or her invention in the best ways.

FIG.1is a side view of a separator stack according to an embodiment of the present invention, andFIG.2is a plan view of the separator stack illustrated inFIG.1.

A separator stack100according to an embodiment of the present invention may include a plurality of separators110stacked on each other and a sealing portion120formed by sealing central regions of the plurality of separators110to each other.

Each of the separators110may include a pair of first edges110aextending in a first direction and a pair of second edges110bextending in a second direction perpendicular to the first direction. Therefore, the pair of second edges110bof each separator110may form both ends of the separator110in the first direction.

The first direction may be parallel to one of the longitudinal direction or width direction of the separator110, and the second direction may be parallel to the other one of the longitudinal direction or width direction of the separator110.

The sealing portion120may be formed as the central regions of the plurality of separators110in the first direction are sealed to each other. The sealing portion120may be elongated in the second direction.

The width of the sealing portion120in the first direction may be reduced along the upward direction with respect to the stacking direction of the plurality of separators110. That is, a lower width w1of the sealing portion120may be greater than an upper width w2thereof.

Accordingly, the thickness of the sealing portion120with respect to the stacking direction of the plurality of separators110may be increased toward the central regions with respect to the first direction.

Also, the sealing portion120may have a shape symmetrical with respect to the first direction. Both ends of the sealing portion120in the first direction may be positioned further inward along the upward direction with respect to the stacking direction of the plurality of separators110.

To this end, a sealing portion120may be formed each time each separator110is sealed. Also, as the separators110are stacked, the width of the sealing portion120may be gradually decreased.

In more detail, when a second separator110is stacked on a first separator110, a sealing portion120having a first width may be formed by sealing the central regions of the first separator110and the second separator110to each other. Subsequently, when a third separator110is stacked on the second separator110, a second sealing portion120having a second width smaller than the first width may be formed by sealing the central regions of the second separator110and the third separator110to each other. Here, the first to third separators are arbitrary names to describe the stacking order of the separators, not specific separators.

The plurality of separators110are stacked and sealed by repeating the above process, and thus, it is possible to form the separator stack100in which the width of the sealing portion120is reduced along the upward direction.

Also, the separator stack100, more specifically, the plurality of separators110may be folded about the sealing portion120(seeFIG.3). Therefore, the length of the separator stack100in the first direction may be reduced by about half, and the height in the stacking direction may be increased by about two times.

In more detail, the separator stack100may be folded in a direction such that one portion and another portion of the last separator110stacked last among the plurality of separators110face each other. Therefore, the one portion and another portion of the last separator110may be positioned in the central region in the stacking direction of the folded separator stack100and may face each other. In addition, one portion and another portion of the initial separator110stacked first among the plurality of separators110may form both outermost regions of the folded separator stack100.

That is, the separator stack100according to the embodiment may have a similar structure to a book in bound form. The initial separator110may correspond to the cover of the book, and another separator110may correspond to each page of the book.

The folded separator stack100will be described later in detail.

Meanwhile, the pairs of second edges110bof the plurality of separators110may be positioned further inward along the upward direction with respect to the stacking direction of the plurality of separators110. That is, the lengths between the pairs of second edges110bof the plurality of separators110may be reduced along the upper direction with respect to the stacking direction. Accordingly, when the separator stack100is folded about the sealing portion120(seeFIG.3), the lengths from the sealing portion120to the plurality of second edges110bwith respect to the plurality of separators110may be the same or similar to each other.

However, the embodiment is not limited thereto, and a plurality of separators110having the constant length may be stacked. In this case, in a state in which the separator stack100is folded about the sealing portion120, a process of cutting a portion of the separator stack100may be further performed so that the lengths from the sealing portion120to the plurality of second edges110bare the same or similar to each other.

FIG.3is a side view illustrating a state in which a plurality of electrodes are inserted into a separator stack according to an embodiment of the present invention,FIG.4is an enlarged view of a region ‘A’ shown inFIG.3, andFIG.5is a side view of an electrode assembly according to an embodiment of the present invention.

An electrode assembly10according to an embodiment of the present invention may include the separator stack100which is folded about the sealing portion120and a plurality of electrodes200which are inserted between the plurality of separators110.

Hereinafter, the separator stack100will be described based on a folded state.

The sealing portion120may be positioned on one side of the separator stack100, and the second edges110bof the plurality of separators110may be positioned on the other side.

The shape of the sealing portion120may vary depending on the degree to which the separator stack100is folded. In one example, an outer surface120aof the sealing portion120may be formed flat as illustrated inFIG.4. In another example, the outer surface120aof the sealing portion120may be convexly bent or folded toward the outside of the separator stack100.

The outer surface120aof the sealing portion120may form a portion of the perimeter of the separator stack100.

A thickness t of the sealing portion120may be increased toward the central region with respect to the stacking direction of the separator stack100. Therefore, the sealing portion120may have a maximum thickness tm in the central region in the stacking direction of the separator stack100.

Here, the thickness t of the sealing portion120may represent a distance from a point, at which each of the separators110is connected to the sealing portion120, to the outer surface120aof the sealing portion120, with respect to the direction perpendicular to the outer surface120aof the sealing portion120. For example, when the outer surface120aof the sealing portion120is flat, the thickness t of the sealing portion120may be parallel to the first direction.

The sealing portion120may have a shape symmetrical with respect to the stacking direction of the separator stack100.

Also, the sealing portion120may be positioned on one side of the plurality of electrodes200. At least some of the plurality of electrodes200may be in contact with or close to the sealing portion120. The sealing portion120may prevent the plurality of electrodes200from being separated from the separator stack100.

The plurality of electrodes200may be inserted between the plurality of separators110included in the separator stack100. The plurality of electrodes200may include a plurality of positive electrodes and a plurality of negative electrodes which are positioned alternately with the separators110therebetween.

Each of the electrodes200may be formed by applying an electrode active material onto a current collector having an electrode plate shape. Also, an electrode tab210(seeFIG.12) may be connected to each of the electrodes200, and the electrode tab210may be an uncoated portion which is not coated with the electrode active material in the current collector.

A plurality of electrode tabs210may protrude toward one side or both sides of the electrode assembly10. In more detail, the plurality of electrode tabs210may include positive electrode tabs connected to the positive electrodes and negative electrode tabs connected to the negative electrodes. The positive electrode tabs and the negative electrode tabs may protrude in parallel to each other or in opposite directions.

The plurality of electrode tabs210may protrude in a direction not interfering with the sealing portion120of the separator stack100and a sub-sealing portion130thereof which will be described later.

The sub-sealing portion130may be positioned on the opposite side from the sealing portion120with the plurality of electrodes200therebetween. That is, the sealing portion120may be positioned on one side of the plurality of electrodes200, and the sub-sealing portion130may be positioned on the other side of the plurality of electrodes200.

The sub-sealing portion130may be formed by sealing the plurality of separators110to each other. In more detail, the sub-sealing portion130may be formed by sealing the second edges110bof the plurality of separators110to each other.

More specifically, in the sub-sealing portion130, the second edges110bof the plurality of separators110may be gathered at the central region and heat-sealed by a separate sealing tool (not shown) or may be folded in random directions and heat-sealed. Therefore, when the sub-sealing portion130is formed, the sub-sealing portion130inevitably has a shape asymmetrical with the sealing portion120.

However, the sub-sealing portion130may not be formed in the separator stack100.

FIG.6is a flowchart of a method for manufacturing an electrode assembly according to an embodiment of the present invention.

A method for manufacturing an electrode assembly10according to an embodiment of the present invention may include preparing a separator stack100in which central regions of a plurality of separators110stacked on each other are sealed to each other to form a sealing portion120(S10), folding the separator stack100about the sealing portion120(S20), and inserting a plurality of electrodes200into spaces between the plurality of separators110(S30).

During the preparing of the separator stack100(S10), the sealing portion120may be formed in the central regions, in a first direction of the plurality of separators110and the sealing portion120may be elongated in a second direction perpendicular to the first direction.

During the preparing of the separator stack100(S10), an operation of stacking another separator120on the upper side of one separator110and an operation of fusing central regions of the one separator110and another separator110to each other to form a sealing portion120may be repeated. Also, the width of the sealing portion120may be reduced along the upper direction with respect to the stacking direction of the separator stack100.

Therefore, the sealing portion120formed at the center of the separator stack100may have a shape of which the width is reduced along the upper direction with respect to the stacking direction of the separator stack100.

During the folding of the separator stack100(S20), the separator stack100may be folded about the sealing portion120that is elongated in the second direction. In more detail, the separator stack100may be folded in a direction such that one portion and another portion of the last separator110stacked last among the plurality of separators110face each other.

Therefore, when the separator stack100is folded, the sealing portion120may be positioned on one side of the separator stack100. Also, a thickness t (seeFIG.4) of the sealing portion120may be increased toward the central region with respect to the stacking direction of the separator stack100.

Also, the shape of the sealing portion120may vary depending on the degree to which the separator stack100is folded.

In one example, when the separator stack100is folded,

the sealing portion120itself may not be folded, and thus, the shape of the sealing portion120may be maintained. In this case, an outer surface120aof the sealing portion120may be flat.

In another example, when the separator stack100is folded, the sealing portion120may be bent together with the plurality of separators110. In this case, the outer surface120aof the sealing portion120may be convexly bent or folded toward the outside of the separator stack100.

During the inserting of the plurality of electrodes200(S30), the plurality of electrodes200may be simultaneously inserted or sequentially inserted into the separator stack100.

For example, a plurality of guide slits (not shown) may be inserted between the plurality of separators110, and each of the electrodes200may be inserted into the separator stack100via the guide slit. Subsequently, the guide slits may be removed.

Accordingly, the sealing portion120of the separator stack100may be positioned on one side of the plurality of electrodes200, and may be in contact with or close to at least some of the plurality of electrodes200.

Also, electrode tabs210(seeFIG.12) provided in the plurality of electrodes200may protrude to the outside of the separator stack100. In more detail, the electrode tabs210may protrude in a direction not interfering with the sealing portion120.

Meanwhile, although not illustrated inFIG.6, the method for manufacturing the electrode assembly10according to the embodiment may further include forming a sub-sealing portion130by sealing the plurality of separators110to each other on the opposite side from the sealing portion120.

In more detail, the second edges110bof the plurality of separators110may be sealed to each other by a separate sealing tool (not shown) to form the sub-sealing portion130. The sealing portion120and the sub-sealing portion130may be positioned on the opposite sides with the plurality of electrodes200therebetween, and may have shapes asymmetrical with each other.

In this case, the electrode tabs210(seeFIG.12) provided in the plurality of electrodes200may protrude in a direction not interfering with the sealing portion120and the sub-sealing portion130.

The method for manufacturing the electrode assembly10according to the embodiment is relatively simple, compared to various kinds of methods for manufacturing an electrode assembly according to the related art. Accordingly, the manufacturing process is simplified, and the manufacturing equipment is also simplified.

Also, the separator stack100that does not include the electrodes200is manufactured first, and thus, the accurate alignment between the plurality of separators110is possible. In addition, the plurality of electrodes200are simultaneously or sequentially inserted into the separator stack100, and thus, the accurate alignment between the plurality of electrodes200is possible. Accordingly, the quality and energy density of the electrode assembly10may be enhanced.

In addition, compared to the related art, the sealing stability of the sealing portion120may be enhanced, and the sealing portion120may prevent the plurality of electrodes200from being separated from the separator stack100. Accordingly, it is possible to prevent the occurrence of a short circuit between the plurality of electrodes200and to improve the stability of the electrode assembly10.

FIG.7is a side view of a separator stack according to another embodiment of the present invention.

A separator stack100′ according to the embodiment may include a base separator111, a base material portion140located in a central region of the base separator111, and a plurality of main separators112connected to the base material portion140.

The base separator111may include a pair of first edges extending in a first direction and a pair of second edges111bextending in a second direction perpendicular to the first direction. Therefore, the pair of second edges110bof the base separator111may form both ends of the separator110in the first direction.

The first direction may be parallel to one of the longitudinal direction or width direction of the base separator111, and the second direction may be parallel to the other one of the longitudinal direction or width direction of the base separator111.

The base separator111may be a single separator or may include a pair of separators spaced apart from each other and connected to the base material portion140which will be described later. Hereinafter, a case in which the base separator111is a single separator will be described as an example.

The base material portion140may be provided in a central region, in the first direction, of the base separator111. In more detail, the base material portion140may be provided in the central region, in the first direction, on the upper surface of the base separator111. Also, the base material portion140may be elongated in the second direction. It is preferable that the width and thickness of the base material portion140are constant.

The base material portion140may be configured to fix edges112aof the main separators112which will be described later, and the material thereof is not limited. For example, the base material portion140may include an adhesive, or include a polymer resin that can be heat-sealed.

Each of the plurality of main separators112may have one edge112aconnected to the base material portion140and the other edge112bpositioned on the opposite side from the one edge112a.The one edge112aand the other edge112bmay extend side-by-side in the second direction.

Hereinafter, for convenience of description, the one edge112ais referred to as a fixed edge, and the other edge112bis referred to as a non-fixed edge.

The fixed edge112aof each of the main separators112may be connected perpendicularly to the base material portion140.

Also, with respect to the first direction, some of plurality of main separators112may be spread toward one side, and the others may be spread toward the other side.

Also, the separator stack100′ may be folded about the base material portion140. In more detail, the base separator111may be folded about the base material portion140so that the plurality of main separators112are gathered (seeFIG.8). Therefore, the plurality of main separators112may be gathered so as to face each other in the stacking direction, and one portion and another portion of the base separator111may form both outermost regions of the folded separator stack100′.

That is, the separator stack100′ according to the embodiment may have a similar structure to a book in bound form. The base separator111may correspond to the cover of the book, and each of the main separators112may correspond to a page of the book.

The folded separator stack100′ will be described later in detail.

Meanwhile, non-fixed edges112bof the plurality of main separators112may be positioned further inward than the second edges111bof the base separator111.

Also, the non-fixed edges112bof the plurality of main separators112may be positioned further inward along the upward direction with respect to the stacking direction of the plurality of main separators112. That is, the lengths between the fixed edges112aand the non-fixed edges112bof the plurality of main separators112may be reduced along the upper direction with respect to the stacking direction.

Accordingly, when the separator stack100′ is folded about the base material portion140(seeFIG.8), the lengths from the base material portion140to the plurality of non-fixed edges112bwith respect to the plurality of main separators112may be the same or similar to each other.

However, the embodiment is not limited thereto, and a plurality of main separators112having the constant length may be used. In this case, in a state in which the separator stack100′ is folded about the base material portion140, a process of cutting a portion of the separator stack100′ may be further performed so that the lengths from the base material portion140to the plurality of non-fixed edges112bare the same or similar to each other.

FIG.8is a side view illustrating a state in which a plurality of electrodes are inserted into a separator stack according to another embodiment of the present invention,FIG.9is an enlarged view of a region ‘B’ shown inFIG.8, andFIG.10is a side view of an electrode assembly according to another embodiment of the present invention.

An electrode assembly10′ according to an embodiment of the present invention may include the separator stack100′ which is folded about the base material portion140and a plurality of electrodes200which are inserted between the plurality of separators111and112.

Hereinafter, the separator stack100′ will be described based on a folded state.

The base material portion140may be positioned on one side of the separator stack100′, and the non-fixed edges112bof the plurality of main separators112and the second edges111bof the base separator111may be positioned on the other side.

When the base separator111is a single separator, a portion of the base separator111may cover the base material portion140from the outside. However, the embodiment is not limited thereto. When the base separator111includes a pair of separators that are connected to the base material portion140and spaced apart from each other, the base material portion140may form a portion of the perimeter of the separator stack100′.

The shape of the base material portion140may vary depending on the degree to which the separator stack100′ is folded. In one example, the base material portion140may be formed flat as illustrated inFIG.9. In another example, the base material portion140may be convexly bent or folded toward the outside of the separator stack100′.

The thickness of the base material portion140may be constant with respect to the stacking direction of the plurality of main separators112.

Also, the base material portion140may be positioned on one side of the plurality of electrodes200. The plurality of electrodes200may be in contact with or close to the base material portion140. The base material portion140may prevent the plurality of electrodes200from being separated from the separator stack100′.

The plurality of electrodes200may be inserted between the base separator111and the plurality of main separators112included in the separator stack100′. In more detail, both outermost electrodes200among the plurality of electrodes200may be inserted between the base separator111and the main separator112, and the other electrodes200may be inserted between the plurality of main separators112.

The plurality of electrodes200may include a plurality of positive electrodes and a plurality of negative electrodes which are positioned alternately with the separators111and112therebetween.

Each of the electrodes200may be formed by applying an electrode active material onto a current collector having an electrode plate shape. Also, an electrode tab210(seeFIG.12) may be connected to each of the electrodes200, and the electrode tab210may be an uncoated portion which is not coated with the electrode active material in the current collector.

A plurality of electrode tabs210may protrude toward one side or both sides of the electrode assembly10′. In more detail, the plurality of electrode tabs210may include positive electrode tabs connected to the positive electrodes and negative electrode tabs connected to the negative electrodes. The positive electrode tabs and the negative electrode tabs may protrude in parallel to each other or in opposite directions.

The plurality of electrode tabs210may protrude in a direction not interfering with the base material portion140of the separator stack100′ and a sub-sealing portion150thereof which will be described later.

Meanwhile, the separator stack100′ may include a sub-sealing portion150.

The sub-sealing portion150may be positioned on the opposite side from the base material portion140with the plurality of electrodes200therebetween. That is, the base material portion140may be positioned on one side of the plurality of electrodes200, and the sub-sealing portion150may be positioned on the other side of the plurality of electrodes200.

The sub-sealing portion150may be formed by sealing the base separator111and the plurality of main separators112to each other. In more detail, the sub-sealing portion130may be formed by sealing the non-fixed edges112bof the plurality of main separators112and the second edges111bof the base separator111to each other.

More specifically, in the sub-sealing portion150, the non-fixed edges112bof the plurality of main separators112and the second edges111bof the base separator111may be gathered at the central region and heat-sealed by a separate sealing tool (not shown) or may be folded in random directions and heat-sealed. Therefore, when the sub-sealing portion150is formed, the sub-sealing portion150inevitably has a shape asymmetrical with the base material portion140.

However, the sub-sealing portion150may not be formed in the separator stack100′.

FIG.11is a flowchart of a method for manufacturing an electrode assembly according to another embodiment of the present invention.

A method for manufacturing an electrode assembly10′ according to an embodiment of the present invention may include preparing a separator stack100′ in which edges112aof a plurality of main separators112are fixed to a base material portion140provided in a central region of a base separator111(S10′); folding the separator stack100′ about the base material portion140(S20′); and inserting a plurality of electrodes200into spaces between the base separator111and the plurality of main separators112(S30′).

During the preparing of the separator stack100′ (S10′), the base material portion140may be provided in the central region, in a first direction, of the base separator111, and may be elongated in a second direction perpendicular to the first direction. Also, the base material portion140may have the constant width and thickness.

In one example, the base material portion140may be formed by applying an adhesive onto a central region of the upper surface of the base separator111.

In another example, an adhesive member or a polymer resin member, which is provided separately from the base separator111, is attached or bonded to the central region of the upper surface of the base separator111, thereby forming the base material portion140.

In another example, a pair of separators spaced apart from each other in the first direction may be connected to an adhesive member or a polymer resin member provided separately. In this case, the pair of separators may form the base separator111, and the adhesive member or the polymer resin member may form the base material portion140.

During the folding of the separator stack100′ (S20), the separator stack100′ may be folded about the base material portion140that is elongated in the second direction. In more detail, the separator stack100′ may be folded in a direction in which the plurality of main separators112are gathered to face each other.

Therefore, when the separator stack100is folded, the base material portion140may be positioned on one side of the separator stack100′, and the thickness of the base material portion140may be constant with respect to the stacking direction of the separator stack100′.

Also, the shape of the base material portion140may vary depending on the degree to which the separator stack100′ is folded.

In one example, when the separator stack100′ is folded, the base material portion140itself may not be folded, and thus, the shape of the base material portion140may be maintained. In this case, the base material portion140may be flat.

In another example, when the separator stack100′ is folded, the base material portion140may be bent together with the base separator111. In this case, the base material portion140may be convexly bent or folded toward the outside of the separator stack100′.

During the inserting of the plurality of electrodes200(S30′), the plurality of electrodes200may be simultaneously inserted or sequentially inserted into the separator stack100′.

For example, a plurality of guide slits (not shown) may be inserted between the plurality of separators111and112, and each of the electrodes200may be inserted into the separator stack100′ via the guide slit. Subsequently, the guide slits may be removed.

Accordingly, the base material portion140of the separator stack100′ may be positioned on one side of the plurality of electrodes200, and may be in contact with or close to the plurality of electrodes200.

Also, electrode tabs210(seeFIG.12) provided in the plurality of electrodes200may protrude to the outside of the separator stack100′. In more detail, the electrode tabs210may protrude in a direction not interfering with the base material portion140.

Meanwhile, although not illustrated inFIG.11, the method for manufacturing the electrode assembly10′ according to the embodiment may further include forming a sub-sealing portion150by sealing the base separator111and the plurality of main separators112to each other on the opposite side from the base material portion140.

In more detail, the second edges111bof the base separator111and the non-fixed edges112bof the plurality of main separators112may be sealed to each other by a separate sealing tool (not shown) to form the sub-sealing portion150. The base material portion140and the sub-sealing portion150may be positioned on the opposite sides with the plurality of electrodes200therebetween, and may have shapes asymmetrical with each other.

In this case, the electrode tabs210(seeFIG.12) provided in the plurality of electrodes200may protrude in a direction not interfering with the base material portion140and the sub-sealing portion150.

In the method for manufacturing the electrode assembly10′ according to the embodiment of the present invention, the separator stack100′ that does not include the electrodes200is manufactured first, and thus, the accurate alignment between the plurality of separators111and112is possible. In addition, the plurality of electrodes200are simultaneously or sequentially inserted into the separator stack100′, and thus, the accurate alignment between the plurality of electrodes200is possible. Accordingly, the quality and energy density of the electrode assembly10′ may be enhanced.

In addition, the sealing stability of the base material portion140may be enhanced, and the base material portion140may prevent the plurality of electrodes200from being separated from the separator stack100′. Accordingly, it is possible to prevent the occurrence of a short circuit between the plurality of electrodes200and to improve the stability of the electrode assembly10′.

In addition, the thickness of the base material portion140is constant, and thus, the alignment of the plurality of electrodes200may be more accurate. Therefore, an empty space between the base material portion140and the plurality of electrodes200may be minimized, the energy density of the electrode assembly10′ may be more enhanced, and the plurality of electrodes200may be more efficiently cooled.

FIG.12is an exploded perspective view of a secondary battery that includes an electrode assembly according to an embodiment of the present invention, andFIG.13is a schematic view of a battery module that includes the secondary battery illustrated inFIG.12.

FIG.12will be illustrated on the basis of the electrode assembly10according to an embodiment of the present invention. From this, one skilled in the art may easily understand a case about the electrode assembly10′ (seeFIG.10) according to another embodiment of the present invention.

The electrode assembly10according to an embodiment of the present invention may be provided with the plurality of electrode tabs210. The electrode tabs210may be respectively connected to the plurality of electrodes200included in the electrode assembly10, and may protrude in a direction not interfering with the sealing portion120and the sub-sealing portion130.

A lead220may be connected to the plurality of electrode tabs210. The lead220may be bonded to the plurality of electrode tabs210by spot welding or the like, and may serve as a passage for supplying power to the outside of the electrode assembly10in conjunction with the plurality of electrode tabs210.

A portion of the perimeter of the lead220may be surrounded by an insulating member230. For example, the insulating member230may include an insulating tape. The insulating member230may insulate the lead220from an edge portion24of a pouch-type battery case20which will be described later, and a portion of the lead220may protrude to the outside of the pouch-type battery case20.

As the electrode assembly10is accommodated in the pouch-type battery case20(hereinafter, referred to as a ‘battery case’), a secondary battery1may be formed. That is, the secondary battery1may include the electrode assembly10and the battery case20.

Meanwhile, the battery case20may be formed from a pair of cases21connected by a folding portion22sealed to each other. Hereinafter, the configuration of each of the pair of cases21will be described on the basis of a state in which the battery case20is unfolded. The ‘state in which the battery case20is unfolded’ represents a state in which the battery case20is spread out as illustrated inFIG.12by removing certain bonding or sealing present in the battery case20.

Each case21may include a cup portion23having a recessed shape and an edge portion24expanding around the cup portion23. However, the embodiment is not limited thereto, and the cup portion23may be formed in only one of the pair of cases21.

In a state in which the electrode assembly10is placed on one cup portion23, the battery case20may be folded about the folding portion22. The edge portions24of the pair of cases21may be brought into contact with and sealed to each other. Therefore, the electrode assembly10may be accommodated in an accommodation space formed by the pair of cup portions23.

Also, a portion, which is positioned on the opposite side from the folding portion22, of the edge portions24sealed to each other may be folded at least once and, for example, double side folding (DSF) may be made thereon. This is well known in the art, and thus, one skilled in the art can easily understand this technique.

The sealing portion120of the electrode assembly10may be located to face the folding portion22of the battery case20. In more detail, the sealing portion120of the electrode assembly10may face the outer wall, on a side of the folding portion22, among a plurality of outer walls that form the perimeter of the cup portion23. Also, the sub-sealing portion130of the electrode assembly10may face the outer wall, which is positioned on the opposite side from the folding portion22, among the plurality of outer walls that form the perimeter of the cup portion23.

For the electrode assembly10′ (seeFIG.10) according to another embodiment of the present invention, the base material portion140may be located to face the folding portion22of the battery case20. In more detail, the base material portion140of the electrode assembly10′ may face the outer wall, on a side of the folding portion22, among a plurality of outer walls that form the perimeter of the cup portion23. Also, the sub-sealing portion150of the electrode assembly10′ may face the outer wall, which is positioned on the opposite side from the folding portion22, among the plurality of outer walls that form the perimeter of the cup portion23.

Also, a battery module5may include a plurality of secondary batteries1stacked on each other and a housing51for accommodating the plurality of secondary batteries1.

A cooling unit52having high thermal conductivity may be provided on the bottom surface inside the housing51, and each of the secondary batteries1may stand such that the folding portion22thereof is in contact with the cooling unit52. For example, the cooling unit52may include thermal grease.

As described above, the edge portion24positioned on the opposite side from the folding portion22in the battery case20is folded at least once, and thus may have a relatively larger thickness than the folding portion22. Therefore, in order to efficiently dissipate heat of the plurality of electrodes200included in the electrode assembly10, it is more effective to bring the folding portion22into contact with the cooling unit52.

Also, referring toFIG.5, the thickness of the sealing portion120may be generally less than the thickness of the sub-sealing portion130. Therefore, the sealing portion120of the electrode assembly10is disposed to face the folding portion22of the battery case20, and thus, the heat of the plurality of electrodes200may be efficiently dissipated.

Similarly, referring toFIG.10, the thickness of the base material portion140may be generally less than the thickness of the sub-sealing portion150. Therefore, the base material portion140of the electrode assembly10′ according to another embodiment of the present invention is disposed to face the folding portion22of the battery case20, and thus, the heat of the plurality of electrodes200may be efficiently dissipated.

In particular, the base material portion140of the electrode assembly10′ according to another embodiment of the present invention has a small and uniform thickness and thus may have higher heat dissipating efficiency with respect to the plurality of electrodes200than the electrode assembly10according to an embodiment.

The technical ideas of the present invention have been described merely for illustrative purposes, and those skilled in the art will appreciate that various changes and modifications are possible without departing from the essential features of the present invention.

Thus, the embodiments of the present invention are to be considered illustrative and not restrictive, and the technical idea of the present invention is not limited to the foregoing embodiments.

The protective scope of the present invention is defined by the appended claims, and all technical ideas within their equivalents should be interpreted as being included in the scope of the present invention.

DESCRIPTION OF THE SYMBOLS