SECONDARY BATTERY AND METHOD OF MANUFACTURING THE SAME

A secondary battery includes: an electrode assembly; a case accommodating the electrode assembly, the case having a bottom surface and long and short sidewalls that extend upwardly from the bottom surface; a cap plate coupled to an upper portion of the case and sealing the case; and an insulation member attached to an outer surface of the case. The insulation member includes a first layer in contact with the outer surface of the case and made of a heat-resistant material, a third layer exposed to the outside and made of a stretchable material, and a second layer between the first and third layers and made of an insulating material.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and the benefit of Korean Patent Application No. 10-2022-0007197, filed on Jan. 18, 2022, in the Korean Intellectual Property Office, the entire content of which is herein incorporated by reference.

BACKGROUND

Aspects of embodiments of the present disclosure relate to a secondary battery and a method of manufacturing the same.

2. Description of the Related Art

Different from a primary battery that is not designed to be charged (or recharged), a secondary battery is a rechargeable and dischargeable battery. A low-capacity secondary battery comprised of a single cell packaged in the form of a pack may be used for various portable small-sized electronic devices, such as cellular phones or camcorders, while a high-capacity secondary battery in which several tens of cells are connected together in a battery pack is widely used as a power source for driving motors, such as those in hybrid vehicles or electric vehicles.

Secondary batteries may be classified as a circular (or cylindrical) type, a prismatic type, or a pouch type according to its shape. For example, a prismatic secondary battery may be configured by including an electrode assembly stacked or wound with a separator interposed between positive and negative plates in a case with an electrolyte and by installing a cap plate in (or on) the case. In addition, an insulation member may be attached to an outer surface of the case to insulate the case.

SUMMARY

Embodiments of the present disclosure provide a secondary battery exhibiting improved safety and that secures a manufacturing process margin, and a method of manufacturing the same.

A secondary battery according to an embodiment of the present disclosure includes: an electrode assembly; a case accommodating the electrode assembly; a cap plate coupled to and sealing an upper portion of the case, the case has a bottom surface and long and short sidewalls that extend upwardly from the bottom surface; and an insulation member attached to an outer surface of the case. The insulation member includes a first layer in contact with an outer surface of the case and made of a heat-resistant material, a third layer exposed to the outside and made of a stretchable material, and a second layer between the first and third layers and made of an insulating material.

The insulation member may have a first region and a second region that cover the long sidewalls of the case and a third region between the first region and the second region and covering the bottom surface of the case.

The first region may have a first sidewall extension part extending to one of the short sidewalls of the case, the second region may have a second sidewall extension part extending to the one of the short sidewalls of the case, and the third region may have a third sidewall extension part extending to the one of the short sidewalls of the case.

A portion of the one of the short sidewalls of the case may be overlapped and covered by the first sidewall extension part, the second sidewall extension part, and the third sidewall extension part.

The third sidewall extension part may have a cut portion including two slits spaced apart from each other.

The cut portion may be spaced apart from an interface between the first sidewall extension part and the third sidewall extension part and an interface between the second sidewall extension part and the third sidewall extension part.

The first region may have a first upper extension part extending to the cap plate, and the second region may have a second upper extension part extending to the cap plate.

A method of manufacturing a secondary battery according to an embodiment of the present disclosure includes: attaching an insulation member to an outer surface of a case, the case having an electrode assembly accommodated therein and sealed with a cap plate at a top portion thereof and has a bottom surface and long and short sidewalls that extend upwardly from the bottom surface, the insulation member having a first region, a second region, and a third region between the first region and the second region. The attaching of the insulation member to the outer surface of the case includes: bringing the bottom surface of the case into contact with the third region; bending the first region and the second region to cover the long sidewalls of the case; bending a first sidewall extension part of the first region and a second sidewall extension part of the second region to cover the short sidewalls of the case; bending a third sidewall extension part of the third region to cover the short sidewalls of the case; and bending a first upper extension part of the first region and a second upper extension part of the second region to cover an edge of the cap plate.

The insulation member may have a cut portion including two slits spaced apart from each other in the third sidewall extension part, and the cut portion may be spaced apart from an interface between the first sidewall extension part and the third sidewall extension part and an interface between the second sidewall extension part and the third sidewall extension part.

An exterior region of the cut portion in the third sidewall extension part may be bent together with the first sidewall extension part and the second sidewall extension part.

The insulation member may include a first layer in contact with the outer surface of the case and made of a heat-resistant material, a third layer exposed to the outside and made of a stretchable material, and a second layer between the first and third layers and made of an insulating material.

DETAILED DESCRIPTION

Example embodiments of the present disclosure are provided to more completely explain the present disclosure to those skilled in the art, and the following examples may be modified in various other forms. In other words, the present disclosure may be embodied in many different forms and should not be construed as being limited to the example embodiments set forth herein. Rather, these example embodiments are provided so that this disclosure will be thorough and complete and will fully convey the aspects and features of the present disclosure to those skilled in the art.

In addition, in the accompanying drawings, sizes or thicknesses of various components may be exaggerated for brevity and clarity. Like numbers refer to like elements throughout. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used herein, the singular forms are intended to include the plural forms as well, unless the context clearly indicates otherwise. Further, the use of “may” when describing embodiments of the present disclosure relates to “one or more embodiments of the present disclosure.” Expressions, such as “at least one of,” when preceding a list of elements, modify the entire list of elements and do not modify the individual elements of the list. As used herein, the terms “use,” “using,” and “used” may be considered synonymous with the terms “utilize,” “utilizing,” and “utilized,” respectively. As used herein, the terms “substantially,” “about,” and similar terms are used as terms of approximation and not as terms of degree, and are intended to account for the inherent variations in measured or calculated values that would be recognized by those of ordinary skill in the art.

FIG.1is a perspective view of a secondary battery according to an embodiment of the present disclosure,FIG.2is a cross-sectional view of the secondary battery shown in FIG.1,FIG.3is an enlarged cross-sectional view of the portion A ofFIG.2, andFIG.4is a plan view showing an insulation member shown inFIG.1.

Referring toFIGS.1to4, the secondary battery100according to the embodiment of the present disclosure includes an electrode assembly110, a current collector plate120, a cap assembly130, a case140, and an insulation member150.

The electrode assembly110is formed by stacking or winding a laminate of a first electrode plate, a separator, and a second electrode plate, which are shaped as thin plates or layers. In some embodiments, the first electrode plate may be a negative electrode and the second electrode plate may be a positive electrode, but the present disclosure is not limited thereto.

The first electrode plate is formed by coating a first electrode active material, such as graphite or carbon, on a first electrode current collector plate formed of a metal foil, such as copper or nickel, and includes a first electrode uncoated portion that is a region to which the first active material is not applied. The first electrode uncoated portion provides a passage for current flow between the first electrode plate and the outside (e.g., the terminal).

In addition, the first electrode plate uncoated portion may form a first current collecting tab111. The first current collecting tab111may include a plurality of first current collecting tabs, which are formed to protrude from the first electrode plate. In a stacked structure, the first current collecting tab111may be formed to protrude from the first electrode plate in a direction (e.g., a predetermined direction) and overlap at one side. In addition, in a winding structure, the first current collecting tab111may be formed by placing the uncoated portion at a reference (e.g., a pre-calculated or predetermined) distance from the first electrode plate to allow the first current collecting tabs111to protrude from the same region after being wound, and then overlapping the same.

The second electrode plate is formed by coating a second electrode active material, such as a transition metal oxide, on a second electrode current collector plate formed of a metal foil, such as aluminum, and includes a second electrode uncoated portion that is a region to which the second active material is not applied.

In addition, a second current collecting tab112may be formed from the uncoated portion of the second electrode plate to correspond to the first current collecting tab111. Accordingly, the second current collecting tab112also has a multi-tab structure, similar to the first current collecting tab111. The second current collecting tab112may protrude in a direction opposite to that of the first current collecting tab111.

The separator is positioned (or arranged) between the first electrode plate and the second electrode plate to prevent a short circuit and to enable movement of lithium ions. The separator may be made of polyethylene or polypropylene or may be a composite film of polyethylene and polypropylene.

The electrode assembly110may be accommodated in the case140together with the electrolyte. The electrolyte may be formed of a lithium salt, such as LiPF6or LiBF4, in an organic solvent, such as ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), or dimethyl carbonate (DMC). In addition, the electrolyte may be in a liquid, solid, or gel phase. In addition, the first current collecting tab111and the second current collecting tab112are electrically connected to the current collector plate120.

The current collector plate120includes a pair of current collector plates and is electrically connected to each of the first current collecting tab111and the second current collecting tab112of the electrode assembly110. For example, the current collector plate120that is electrically connected to the first current collecting tab111may have a negative polarity, and the current collector plate120that is electrically connected to the second current collecting tab112may have a positive polarity depending on the polarity of the first and second current collecting tabs111and112.

The cap assembly130may be formed on the electrode assembly110and may be coupled to the case140to seal the case140. The cap assembly130may include a cap plate131and an electrode terminal135.

The cap plate131, which may have a plate shape, may be coupled to an opening in the case140and may be formed of the same material as the case140. The cap plate131may be coupled to the case140by, for example, laser welding. In some embodiments, the cap plate131may be electrically connected to the second current collecting tab112. In such an embodiment, the cap plate131and the case140may have the same polarity (e.g., positive polarity). Of course, the cap plate131may also be electrically connected to the first current collecting tab111.

The cap plate131may include a safety vent132having a relatively small thickness compared to other regions of the cap plate121, and an electrolyte injection hole (e.g., an electrolyte injection opening)133for injecting an electrolyte into the case140. The electrolyte injection hole133may be sealed by a stopper134after the electrolyte is injected into the case140.

Electrode terminals135may pass through the cap plate131at opposite sides (or ends) thereof and may be electrically connected to the current collector plate120. In some embodiments, the electrode terminal135connected to the current collector plate120, which is coupled to the first current collecting tab111, may have negative polarity, and the electrode terminal135connected to the current collector plate120, which is coupled to the second current collecting tab112, may have positive polarity.

The case140may have a substantially hexahedron shape having an opening through which the electrode assembly110can be inserted to be accommodated therein. The case140may have a substantially rectangular bottom surface141, long sidewalls142and143, and short sidewalls144and145that extend a length (e.g., a predetermined length) upwardly from the bottom surface141. The long sidewalls142and143and the short sidewalls144and145may include each pair of sidewalls facing each other.

In some embodiments, the case140may be made of steel, a steel alloy, nickel plated steel, a nickel plated steel alloy, aluminum, or an aluminum alloy. The inner surface of the case140may be insulated to prevent an electrical short from occurring therein. In some embodiments, the case140may be electrically connected to one electrode of the electrode assembly110through the cap plate131.

The insulation member150may be attached to, adhered to, in close contact with, in contact with, or coupled to an outer surface of the case140. In some embodiments, the insulation member150may include or may be an insulating tape, a sheathing tape, or a finishing tape.

The insulation member150may cover the bottom surface141, the long sidewalls142and143, and the short sidewalls144and145of the case140. In some embodiments, the insulation member150may extend to the cap plate131to cover the edge of the cap plate131. In some embodiments, the insulation member150may cover the interface (e.g., a welding portion) between the cap plate131and the case140. In some embodiments, the insulation member150may insulate the case140and an external device from each other.

The insulation member150may include a first layer150ain contact with the case140, a third layer150cexposed to the outside, and a second layer150binterposed between the first layer150aand the third layer150c.

The first layer150amay include a heat-resistant material. In some embodiments, the first layer150amay include polyimide (PI) or polyether ether ketone (PEEK) as the high heat-resistant material. The first layer150ais the innermost layer and may be in direct contact with the case140. The first layer150amay prevent the insulation member150from being deformed by heat generated in the case140. In some embodiments, the first layer150amay be vicious and/or may be to attach the insulation member150to the case140.

The second layer150bmay include an insulating material. In some embodiments, the second layer150bmay include polyethylene terephthalate (PET), polybutylene terephthalate (PBT), or polyphenylene sulfide (PPS) as the insulating material. The second layer150bis positioned (or arranged) between the first layer150aand the third layer150cand may strengthen the insulating properties of the case140.

The third layer150cmay include a stretchable material. In some embodiments, the third layer150cmay include oriented poly propylene (OPP), casting poly propylene (CPP), or polyurethane (PU) as the stretchable material.

The insulation member150may have a first region151that covers one long sidewall142of the case140, a second region152that covers the other long sidewall143of the case140, and a third region153that covers the bottom surface141of the case140. For convenience of description, the long sidewall142that is covered by the first region151will be referred to as a front long sidewall, and the long sidewall143that is covered by the second region152will be referred to as a rear long sidewall.

The first region151may have a first sidewall extension part151athat extends to the sidewalls144and145of the case140. The first sidewall extension part151aextends in the first direction (e.g., the longitudinal direction of the case140), and may be positioned at both sides of the first region151. The first sidewall extension part151amay cover portions of the short sidewalls144and145of the case140. The first sidewall extension part151amay be connected to the third region153.

In addition, the first region151may have a first upper extension part151bthat extends to the cap plate131. The first upper extension part151bmay extend in a second direction (e.g., a height direction of the case) perpendicular to the first direction and may be positioned at one side of the first region151. On the basis of the second direction, the first upper extension part151bmay be positioned at one end of the first region151, and the third region153may be positioned at the other end of the first region151.

The second region152may have a second sidewall extension part152athat extends to the sidewalls144and145of the case140. The second sidewall extension part152aextends in the first direction (e.g., the longitudinal direction of the case140) and may be positioned at both sides of the second region152. The second sidewall extension part152amay cover a portion of the short sidewalls144and145of the case140. The second sidewall extension part152amay be connected to the third region153.

In addition, the second region152may have a second upper extension part152bthat extends to the cap plate131. The second upper extension part152bextends in the second direction (e.g., the height direction of the case140) perpendicular to the first direction and may be positioned at one side of the second region152. On the basis of the second direction, the second upper extension part152bmay be positioned at one end of the second region152, and the third region153may be positioned at the other end of the second region152.

The third region153may be positioned between the first region151and the second region152. The third region153may have a third sidewall extension part153athat extends to the sidewalls144and145of the case140. The third sidewall extension part153aextends in the first direction (e.g., the longitudinal direction of the case140) and may be positioned at both sides of the third region153. The third sidewall extension part153amay cover portions of the short sidewalls144and145of the case140. The third sidewall extension part153amay be connected to (e.g., may extend between) the first sidewall extension part151aand the second sidewall extension part152a.

A cut portion153bthat extends in the first direction may be provided in the third sidewall extension part153a. As shown inFIG.1, when the insulation member150is attached to the case140, the direction in which the cut portion153bextends may be the height direction of the case140.

The cut portion153bmay extend inwardly along the insulation member150from the end of the third sidewall extension part153a. The cut portion (e.g., each cut portion)153bmay include two (or more) slits spaced apart from each other. The cut portion153bmay be spaced apart from the interface at where the third sidewall extension part153aand the first sidewall extension part151ameet and the interface at where the third sidewall extension part153aand the second sidewall extension part152ameet. The cut portion153bmay be a guide for inducing the folding of the insulation member150. In some embodiments, the cut portion153bmay prevent the insulation member150from being crushed (or folded or wrinkled) when the first sidewall extension part151a, the second sidewall extension part152a, and the third sidewall extension part153aare attached to the short sidewalls144and145of the case140.

As such, the short sidewalls144and145of the case140may be covered by the first sidewall extension part151a, the second sidewall extension part152a, and the third sidewall extension part153a. In some embodiments, a region at where the first sidewall extension part151a, the second sidewall extension part152a, and the third sidewall extension part153aoverlap and cover each other may be at the short sidewalls144and145of the case140. In some embodiments, there may exist a region at the short sidewalls144and145of the case140at where the first sidewall extension part151a, the second sidewall extension part152a, and the third sidewall extension part153aoverlap and cover each other.

FIGS.5A to5Gare views for describing a method of manufacturing a secondary battery according to an embodiment of the present disclosure.

A method of attaching the insulation member150to the case140will be described with reference toFIGS.5A to5G.

As shown inFIG.5A, the case140, in which the electrode assembly110is accommodated and sealed by the cap plate131, is arranged on the insulation member150so that the first layer150aof the insulation member150is in contact with bottom surface141of the case140. The bottom surface141of the case140may be arranged on the third region153of the insulation member150.

Next, as shown inFIG.5B, by bending the first region151and the second region152of the insulation member150, the insulation member150may cover the long sidewalls142and143of the case140. The first region151may be attached to the front long sidewall142of the case140, and the second region152may be attached to the rear long sidewall143of the case140. The first upper extension part151bof the first region151and the second upper extension part152bof the second region152may protrude upwardly from (or above) the cap plate131.

By bending the first sidewall extension part151aof the first region151and the second sidewall extension part152aof the second region152toward the short sidewalls144and145of the case140, as shown inFIG.5C, the insulation member150may cover the short sidewalls144and145of the case140. In some embodiments, after the first sidewall extension part151ais attached to the short sidewalls144and145, the second sidewall extension part152amay be attached on the first sidewall extension part151a. Alternatively, after the second sidewall extension part152ais attached to the short sidewalls144and145, the first sidewall extension part151amay be attached on the second sidewall extension part152a. Accordingly, a region in which the first sidewall extension part151aand the second sidewall extension part152aoverlap each other may be formed. Accordingly, a region in which the first sidewall extension part151aand the second sidewall extension part152aoverlap each other may be generated.

In addition, when the first sidewall extension part151aand the second sidewall extension part152aare bent (or folded), the third sidewall extension part153amay be spaced apart from the first sidewall extension part151aand the second sidewall extension part152adue to the cut portion153b. For example, in the third sidewall extension part153a, a region that is positioned inside the cut portion153bmay not be folded or moved together with the first sidewall extension part151aand the second sidewall extension part152aeven when the first sidewall extension part151aand the second sidewall extension part152aare bent. In the third sidewall extension part153a, a region that is positioned outside the cut portion153bmay be bent together with the first sidewall extension part151aand the second sidewall extension part152a.

Next, by bending (or folding) the third sidewall extension part153a, as shown inFIG.5D, the short sidewalls144,145of the case140may be covered. The third sidewall extension part153amay be attached on a region of the case140at where the first sidewall extension part151aand the second sidewall extension part152aoverlap each other. Accordingly, there may exist a region at the short sidewalls144and145of the case140at where the first sidewall extension part151a, the second sidewall extension part152a, and the third sidewall extension part153aoverlap and cover each other.

Next, as shown inFIGS.5E to5G, by bending the first upper extension part151bof the first region151and the second upper extension part152bof the second region152, the edge of the cap plate131may be covered. In some embodiments, after bending the first upper extension part151band the second upper extension part152bthat protrude upwardly from the short sidewalls144and145of the case140, the first upper extension part151band the second upper extension part152bthat protrude upwardly from the long sidewalls142and143of the case140may be bent. Alternatively, after bending the first upper extension part151band the second upper extension part152bthat protrude upwardly from the long sidewalls142and143of the case140, the first upper extension part151band the second upper extension part152bthat protruding upwardly from the short side walls144and145of the case140may be bent.

Accordingly, the secondary battery100having the insulation member150attached to the outer surface of the case140may be provided.

As described above, in a secondary battery and a method of manufacturing the same, according to embodiments of the present disclosure, by attaching, to the outer surface of the case, an insulation member including a first layer made of a heat-resistant material, a second layer made of an insulating material, and a third layer made of a stretchable material, the safety of the secondary battery can be improved and a manufacturing process margin can be secured.

The foregoing embodiments are only some embodiments for carrying out the present disclosure, which is not limited to the embodiments described herein. It will be understood by a person skilled in the art that various changes in form and details may be made to the embodiments described herein without departing from the spirit and scope of the present disclosure as defined by the following claims and their equivalents.