Patent Description:
A battery may be classified as a prismatic type, a cylindrical type, a pouch type, etc., according to the shape of a case. A prismatic or cylindrical battery may be manufactured by inserting an electrode assembly having a positive electrode, a negative electrode, and a separator into a metal can, or case, and sealing the electrode assembly, while a pouch type battery may be manufactured by enclosing an electrode assembly using an aluminum foil coated with an insulator.

Traditional battery can manufacturing methods may include a deep drawing process, an impact process, and so on. In an example, the deep drawing process is performed such that a sheet-shaped metal plate is placed on a molding die and punching operations are performed on the metal plate about ten times using a punch, thereby completing the can. In another example, the impact process is performed such that a slug in the form of a billet is placed on a molding die and a strong punching operation is performed on the slug about one time using a punch, thereby completing the can. The impact process can reduce the number of processing steps, thereby lowering the manufacturing cost.

However, the conventional deep drawing process and the conventional impact process are both limited in reducing a can thickness due to the respective manufacturing process characteristics and reveal a large deviation in the thickness of the can according to the area of the can. In addition, the conventional deep drawing process and the conventional impact process are problematic in that the manufacturing cost of the battery can is quite high. The <CIT> discloses a rechargeable battery including a body formed by a polygonal tube and a bottom plate bent from at least one surface at an opening of the body and physically connected to the rest of the surfaces. The <CIT> discloses a battery with a container that has a bottom portion, long side-wall portions each standing on a corresponding one of longer side portions of the bottom portion, short-sidewall portions each standing on a corresponding one of two shorter side portions of the bottom portion, and a welded portion in which portions of a flat plate are mutually welded. The <CIT> discloses metal box body capable of housing various articles having a recessed portion in a bottom portion.

The above information disclosed in this Background section is only for enhancement of understanding of the background of the described technology and, therefore, it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.

A secondary battery has a bending type can, or case, which has no thickness deviation in various areas of the can by reducing the thickness of the can and increasing dimension accuracy, and which has improved safety by providing curved portions at corners where three or four sides meet.

A secondary battery has a bending type can, or case, which includes desirably shaped curved portions by providing protrusions at corners where three or four sides meet, the protrusions overlapping with each other when the corners are bent, thereby preventing or substantially preventing pinholes from being generated during welding.

According to the present invention, a method of manufacturing of a secondary battery is provided according to claim <NUM>.

The protrusions are located at regions where the first short side portion and the second short side portions meet.

The protrusions may include a first protrusion located in the first short side portion, and a second protrusion located in each of the second short side portions.

The first protrusion and the second protrusion may overlap with each other.

The first protrusion and the second protrusion may be in an asymmetric configuration.

The first protrusion may be larger than the second protrusion.

The second protrusion may be larger than the first protrusion.

The first and second protrusions may be circular, triangular, quadrangular, pentagonal, or hexagonal.

The first protrusion may have a larger curvature radius than the second protrusion.

The second protrusion may have a larger curvature radius than the first protrusion.

The secondary battery may further include curved portions located at regions where the bottom portion, the long side portions, and the short side portions including the first short side portion including the first protrusion and the second short side portion including the second protrusion, meet.

The short side portion further includes welding portions, and the welding portions include a first welding portion located between each of the curved portions and each of the first short side portion and the second short side portions, and a second welding portion located between the second short side portions.

The protrusions may be located at centers of regions where the first short side portion and the second short side portions meet.

The protrusions may be connected longer to the first short side portion than to the second short side portions, or the protrusions may be connected longer to the second short side portions than to the first short side portion.

The protrusions may be separately provided to be inserted between the first short side portion and the second short side portions.

The first short side portion may extends from both end portions of the bottom portion, the second short side portions may extend from both ends of the long side portions, and the short side portion may be defined on both sides of the bottom portion and the long side portions.

As described above, a secondary battery having a bending type can is provided, which has no thickness deviation in various areas of the can by reducing the thickness of the can and increasing dimension accuracy, and which can improve safety by providing curved portions at corners where three or four sides meet. In some examples, asymmetrical protrusions are provided at vertexes (corners) where the first short side portion bent from the bottom portion and the second short side portions bent from the long side portions meet, such that the asymmetrical protrusions overlap with each other when they are bent, thereby providing desirably shaped, symmetrical curved portions at the corners where the bottom portion, the long side portions, the first short side portion, and the second short side portions meet.

In addition, a secondary battery having a bending type can is provided, which includes desirably shaped curved portions by providing protrusions at corners where three or four sides meet, the protrusions overlapping with each other when the corners are bent, thereby preventing or substantially preventing pinholes from being generated during welding. In some examples, desirably shaped, symmetrical curved portions are provided by the asymmetrical protrusions overlapping with each other, and boundary regions between the first and second short side portions are spaced by a distance (e.g., a predetermined distance) apart from the curved portions, thereby easily performing welding without pinholes being generated at the curved portions and the boundary regions.

Herein, some example embodiments of the present invention will be described in further detail.

The term "welding portion" used throughout this specification can be referred to as a temporary welding portion and/or a welding portion in some cases, which is for representing the welding sequence and function but is not intended to limit the invention. In addition, the term "welding" as used herein mainly means laser welding, and examples of a laser used for welding may include, but are not limited to, CO<NUM> laser, fiber laser, disk laser, semiconductor laser, and/or yttrium aluminum garnet (YAG) laser.

<FIG> is a perspective view illustrating a secondary battery manufactured according to an example embodiment of the present invention. In the example shown in <FIG>, a secondary battery <NUM> may include an electrode assembly <NUM> (<NUM> and <NUM> in the examples shown in <FIG> and <FIG>), a first terminal <NUM>, a second terminal <NUM>, a can, or case, <NUM>, and a cap assembly <NUM>.

In some examples, the can <NUM> may be provided by blanking and/or notching, bending, and welding a metal plate and may have a substantially hexahedral shape having an opening through which the electrode assembly <NUM> is inserted and placed and the cap assembly <NUM> is mounted. In some examples, the can <NUM> may include a rectangular bottom portion <NUM> having long sides and short sides, long side portions <NUM> and <NUM> bent and extended from the respective long sides of the bottom portion <NUM> to the cap assembly <NUM>, and short side portions <NUM> and <NUM> extended from the respective short sides of the bottom portion <NUM> and the long side portions <NUM> and <NUM>.

In <FIG>, the can <NUM> and the cap assembly <NUM> assembled to each other are illustrated, such that the opening, which is a substantially opened part of a region corresponding to the cap assembly <NUM>, is not illustrated in <FIG>. In an embodiment, the interior surface and/or the exterior surface of the can <NUM> may be subjected to insulation treatment such that the can <NUM> is insulated from the electrode assembly, the first terminal <NUM>, the second terminal <NUM>, and the cap assembly <NUM>.

<FIG> and <FIG> are cross-sectional views illustrating secondary batteries <NUM> and <NUM> manufactured according to example embodiments of the present invention. In the example shown in <FIG>, the secondary battery <NUM> may include the electrode assembly <NUM> having a winding axis extending in a horizontal direction (i.e., in a direction substantially parallel with a lengthwise direction of the cap assembly <NUM>). In the example shown in <FIG>, the secondary battery <NUM> may include an electrode assembly <NUM> having a winding axis extending in a vertical direction (i.e., in a direction substantially perpendicular to the lengthwise direction of the cap assembly <NUM>). In some example embodiments, the electrode assembly may be a stacked electrode assembly, rather than a wound electrode assembly.

The secondary battery <NUM> shown in <FIG> will now be described. The electrode assembly <NUM> may be formed by winding or stacking a stacked structure including a first electrode plate <NUM>, a separator <NUM>, and a second electrode plate <NUM>, which are thin plates or layers. In some examples, the first electrode plate <NUM> may operate as a negative electrode and the second electrode plate <NUM> may operate as a positive electrode, or vice versa. In some examples, the first electrode plate <NUM> may be formed by coating a first active material, such as graphite or carbon, on a first electrode collector made of a metal foil, such as copper, a copper alloy, nickel, or a nickel alloy, and may include a first uncoated portion 111a that is not coated with the first active material. In some examples, the second electrode plate <NUM> may be formed by coating a second active material, such as a transition metal oxide, on a second electrode collector made of a metal foil, such as aluminum or an aluminum alloy, and may include a second uncoated portion 112a that is not coated with the second electrode material. In some examples, the separator <NUM>, which is located between the first and second electrode plates <NUM> and <NUM>, may prevent or substantially prevent short circuits between the first and second electrode plates <NUM> and <NUM>, and may allow lithium ions to move. In an embodiment, the separator <NUM> may include polyethylene, polypropylene, or a composite film of polyethylene and polypropylene. In an embodiment, the separator <NUM> may be replaced by an inorganic solid electrolyte, such as a sulfide-based compound, an oxide-based compound, or a sulphate compound, such as not to necessitate a liquid- or gel-phase electrolyte solution. The first terminal <NUM> and the second terminal <NUM> electrically connected to the first electrode plate <NUM> and the second electrode plate <NUM>, respectively, are located at opposite ends of the electrode assembly <NUM>. In some examples, the electrode assembly <NUM> may be accommodated in the can <NUM> with an electrolytic solution. In some examples, the electrolytic solution may include an organic solvent, such as ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), or dimethyl carbonate (DMC), and a lithium salt, such as LiPF<NUM> or LiBF<NUM>. In some examples, if the inorganic solid electrolyte is used, the electrolytic solution may be omitted.

The first terminal <NUM> may be made of a metal and may be electrically connected to the first electrode plate <NUM>. In some examples, the first terminal <NUM> may include a first collector plate <NUM>, a first terminal pillar <NUM>, and a first terminal plate <NUM>. In some examples, the first collector plate <NUM> may be brought into contact with the first uncoated portion 111a protruding to an end of the electrode assembly <NUM>. In an embodiment, the first collector plate <NUM> may be welded to the first uncoated portion 111a. In some examples, the first collector plate <NUM> may be substantially in an inverted L-shaped ("┌") configuration and may have a terminal hole 121a located in a top portion thereof. In some examples, the first terminal pillar <NUM> may be inserted into the terminal hole 121a, followed by riveting and/or welding. In some examples, the first collector plate <NUM> may be made of copper or a copper alloy. In some examples, the first terminal pillar <NUM> penetrates the cap plate <NUM> to be described later and is electrically connected to the first collector plate <NUM> under the cap plate <NUM>. In addition, in some examples, while the first terminal pillar <NUM> is upwardly protruded and extended to an upper portion of the cap plate <NUM> by a length (e.g., a predetermined length), a flange 122a may be located below the cap plate <NUM> to prevent or substantially prevent the first terminal pillar <NUM> from being dislodged from the cap plate <NUM>. In an embodiment, a portion of the first terminal pillar <NUM> positioned below the flange 122a is fitted into the first terminal hole 121a of the first collector plate <NUM>, followed by riveting and/or welding. In some examples, the first terminal pillar <NUM> may be electrically insulated from the cap plate <NUM>. In some examples, boundary regions of the upwardly exposed first terminal pillar <NUM> and the first terminal plate <NUM> may be welded to each other. For example, a laser beam may be supplied to the boundary regions of the upwardly exposed first terminal pillar <NUM> and the first terminal plate <NUM> to melt the boundary regions, followed by cooling, thereby welding the boundary regions. The welded regions are designated by reference numeral <NUM> in <FIG>. In an embodiment, a bus bar made of aluminum or an aluminum alloy may be welded to the first terminal plate <NUM>.

The second terminal <NUM> may also be made of a metal and may be electrically connected to the second electrode plate <NUM>. In some examples, the second terminal <NUM> may include a second collector plate <NUM>, a second terminal pillar <NUM>, and a second terminal plate <NUM>. In some examples, the second collector plate <NUM> may be brought into contact with the second uncoated portion 112a protruding to an end of the electrode assembly <NUM>. In some examples, the second collector plate <NUM> may be substantially in an inverted L-shaped ("┐") configuration and may have a terminal hole 131a located in a top portion thereof. In some examples, the second terminal pillar <NUM> may be inserted into the terminal hole 131a and then coupled thereto. In some examples, the second collector plate <NUM> may be made of, for example, but is not limited to, aluminum or an aluminum alloy. In some examples, the second terminal pillar <NUM> penetrates the cap plate <NUM> to be described later and is electrically connected to the second collector plate <NUM> under the cap plate <NUM>. In addition, in some examples, while the second terminal pillar <NUM> is upwardly protruded and extended to an upper portion of the cap plate <NUM> by a length (e.g., a predetermined length), a flange 132a may be located below the cap plate <NUM> to prevent or substantially prevent the second terminal pillar <NUM> from being dislodged from the cap plate <NUM>. In an embodiment, a portion of the second terminal pillar <NUM> positioned below the flange 132a is fitted into the second terminal hole 131a of the second collector plate <NUM>, followed by riveting and/or welding. In an embodiment, the second terminal pillar <NUM> may be electrically insulated from the cap plate <NUM>. In some examples, the second terminal pillar <NUM> may be made of aluminum or an aluminum alloy. The second terminal plate <NUM> has a hole 134a. In addition, the second terminal plate <NUM> is coupled to the second terminal pillar <NUM>. That is, the second terminal pillar <NUM> is coupled to the hole 134a of the second terminal plate <NUM>. In an embodiment, the second terminal pillar <NUM> and the second terminal plate <NUM> may be riveted and/or welded to each other. In some examples, boundary regions of the upwardly exposed second terminal pillar <NUM> and the second terminal plate <NUM> may be welded to each other. For example, a laser beam may be supplied to the boundary regions of the upwardly exposed second terminal pillar <NUM> and the second terminal plate <NUM> to melt the boundary regions, followed by cooling, thereby welding the boundary regions. The welded regions are designated by reference numeral <NUM> in <FIG>. In an embodiment, a bus bar made of aluminum or an aluminum alloy may be easily welded to the second terminal plate <NUM>. In an embodiment, the second terminal plate <NUM> may be electrically connected to the cap plate <NUM>. Thus, the cap plate <NUM> and the can <NUM>, which will be described below, may have the same polarity as the second terminal <NUM> (e.g., a positive polarity).

The cap assembly <NUM> may be coupled to the can <NUM>. In some examples, the cap assembly <NUM> may include the cap plate <NUM>, a seal gasket <NUM>, a plug <NUM>, a safety vent <NUM>, an upper coupling member <NUM>, and a lower insulating member <NUM>. The cap plate <NUM> may seal the opening of the case <NUM>, and may be made of the same material as the case <NUM>. In some examples, the cap plate <NUM> may be coupled to the can <NUM> by laser welding. As described above, in an embodiment, since the cap plate <NUM> has the same polarity as the second terminal <NUM>, the cap plate <NUM> and the can <NUM> may have the same polarity. The seal gasket <NUM> made of an insulating material may be located between each of the first terminal pillar <NUM> and the second terminal pillar <NUM> and the cap plate <NUM> at a bottom end of the cap plate <NUM> and may seal regions between each of the first terminal pillar <NUM> and the second terminal pillar <NUM> and the cap plate <NUM>. The seal gasket <NUM> may prevent or substantially prevent external moisture from permeating into the secondary battery <NUM> or prevent or substantially prevent the electrolyte accommodated in the secondary battery <NUM> from being effused outside. The plug <NUM> may seal an electrolyte injection hole 151a of the cap plate <NUM>. The safety vent <NUM> may be installed in a vent hole 151b of the cap plate <NUM> and may have a notch configured to be openable at a preset pressure. The upper coupling member <NUM> may be located between each of the first terminal pillar <NUM> and the second terminal pillar <NUM> and the cap plate <NUM> at a top end of the cap plate <NUM>. In addition, the upper coupling member <NUM> may closely contact the cap plate <NUM>. In addition, the upper coupling member <NUM> may also closely contact the seal gasket <NUM>. The upper coupling member <NUM> may insulate the first terminal pillar <NUM> and the second terminal pillar <NUM> from the cap plate <NUM>. In some examples, the upper coupling member <NUM> located at the second terminal pillar <NUM> may electrically connect the second terminal plate <NUM> and the cap plate <NUM> to each other. Accordingly, the second terminal <NUM> may have the same polarity as the cap plate <NUM> and the can <NUM>. The lower insulating member <NUM> may be located between each of the first collector plate <NUM> and the second collector plate <NUM> and the cap plate <NUM> and may prevent or substantially prevent an unnecessary short circuit from being generated. That is, the lower insulating member <NUM> may prevent or substantially prevent short circuits from being generated between the first collector plate <NUM> and the cap plate <NUM> and between the second collector plate <NUM> and the cap plate <NUM>.

The secondary battery <NUM> shown in <FIG> will now be described. The secondary battery <NUM> is different from the secondary battery <NUM> described above in terms of the construction of the electrode assembly <NUM> and the connection relationships between the electrode assembly <NUM> and each of the terminals <NUM> and <NUM>. A first electrode tab 211a may be positioned between the electrode assembly <NUM> and a first terminal pillar <NUM> of a first terminal <NUM>, and a second electrode tab 212a may be positioned between the electrode assembly <NUM> and a second terminal pillar <NUM> of a second terminal <NUM>. The first electrode tab 211a may be extended from a top end of the electrode assembly <NUM> to a bottom end of the first terminal pillar <NUM> of the first terminal <NUM> to be electrically connected or welded to a planar flange 122a provided in the first terminal pillar <NUM>. In addition, the second electrode tab 212a may be extended from a top end of the electrode assembly <NUM> to a bottom end of the second terminal pillar <NUM> of the second terminal <NUM> to be electrically connected or welded to a planar flange 132a provided in the second terminal pillar <NUM>. The first electrode tab 211a may be either a first uncoated portion of the first electrode plate <NUM> of the electrode assembly <NUM>, which is not coated with a first active material 211b, or a separate member connected to the first uncoated portion. Here, the first uncoated portion may be made of a same material as the first electrode plate <NUM>, and the separate member may be one selected from the group consisting of nickel, a nickel alloy, copper, a copper alloy, aluminum, an aluminum alloy, and equivalents thereof. In addition, the second electrode tab 212a may be either a second uncoated portion of the second electrode plate <NUM> of the electrode assembly <NUM>, which is not coated with a second active material, or a separate member connected to the second uncoated portion. Here, the second uncoated portion may be made of a same material as the second electrode plate <NUM>, and the separate member may be one selected from the group consisting of aluminum, an aluminum alloy nickel, a nickel alloy, copper, a copper alloy, and equivalents thereof.

As described above, since a winding axis of the electrode assembly and terminal axes of the terminals are parallel or horizontal with each other, the electrode assembly has excellent electrolyte impregnation capability when an electrolyte is injected, and internal gases are rapidly transferred to a safety vent during overcharging to facilitate the safety vent <NUM> quickly operating. In addition, electrode tabs (uncoated portions or separate members) of the electrode assembly are directly electrically connected to the terminals, which shortens electrical paths, thereby reducing internal resistance of the secondary battery <NUM> while reducing the number of components of the secondary battery <NUM>.

The can <NUM> manufactured by an example method, which will be described below, may be employed to the secondary batteries <NUM> and <NUM> shown in <FIG>, <FIG>, and <FIG>.

<FIG> and <FIG> are perspective views illustrating a method for manufacturing a secondary battery <NUM>, <NUM> according to an example embodiment of the present invention. <FIG> shows a can <NUM> at an initial stage of manufacture. Here and in the following description of the Figures, not only the manufacturing method but also the features of example embodiments of a secondary battery manufactured according to the invention become clear and are illustrated in more detail.

In the example shown in <FIG>, a substantially planar metal plate 140A having a uniform thickness is provided. In some example embodiments, the metal plate 140A may include aluminum (Al), iron (Fe), copper (Cu), titanium (Ti), nickel (Ni), magnesium (Mg), chromium (Cr), manganese (Mn), zinc (Zn), or alloys of these elements. In some example embodiments, the metal plate 140A may include nickel (Ni) plated iron (Fe) or SUS (e.g., SUS <NUM>, SUS <NUM>, SUS <NUM>, SUS <NUM>, or SUS <NUM>).

In addition, in some example embodiments, the metal plate 140A may have a thickness in a range from approximately <NUM> to approximately <NUM>, and a deviation in the thickness of the metal plate 140A in all areas may be in a range from approximately <NUM>% to approximately <NUM>%. Therefore, the present invention may provide the can <NUM> that is relatively thin and has a small thickness deviation, compared to a conventional can.

In addition, in some examples, the metal plate 140A may be preprocessed to facilitate a bending process, a notching process, a bending process, and/or a welding process, which will be described below. In some examples, the metal plate 140A may be subjected to annealing treatment performed in a predetermined gas atmosphere and a predetermined temperature range for a predetermined period of time. In some examples, the annealing treatment may be performed in an atmosphere of inert gas, such as argon (Ar) or nitrogen (N<NUM>) at a temperature ranging from approximately <NUM> to approximately <NUM> for approximately <NUM> seconds to approximately <NUM> minutes. The annealing treatment may increase the elastic modulus of the metal plate 140A by approximately <NUM>% to approximately <NUM>%. Accordingly, the bending process of the metal plate 140A, which will later be described, may be easily performed, and occurrence of a spring-back phenomenon can be minimized or reduced, particularly after the bending process.

In an embodiment, the metal plate 140A may have a substantially planar top surface and a substantially planar bottom surface. In an embodiment, the top surface and/or the bottom surface of the metal plate 140A may be subjected to insulation treatment. In some examples, a thin insulation film may be located on the top surface of metal plate 140A by forming a thin oxide layer (e.g., an anodizing layer) through a metal oxidation process, or coating or laminating an insulation resin (e.g., polyimide, polypropylene, or polyethylene). In some examples, the top surface of the metal plate 140A may correspond to the interior surface of the can <NUM> , and the bottom surface of the metal plate 140A may correspond to the exterior surface of the can <NUM>. These features of the metal plate 140A may be commonly applied to all of the metal plates disclosed in the following embodiments.

<FIG> shows a can <NUM> at a later stage of manufacture.

In the example shown in <FIG>, a substantially planar metal plate 140A having a uniform thickness may be provided using a blanking process and/or a notching process. In some examples, the metal plate 140A may include a substantially rectangular bottom portion <NUM> having long sides and short sides, long side portions <NUM> and <NUM> (to later be bent from the bottom portion) horizontally extended from the respective long sides of the bottom portion <NUM>, and short side portions <NUM> and <NUM> (to later be bent from the bottom portion and the long side portions) horizontally extended from the bottom portion <NUM> and the respective long side portions <NUM> and <NUM>.

In some examples, one of the short side portions <NUM> may include a first short side portion 144a extended from the short side of the bottom portion <NUM> in a substantially triangular shape, a second short side portion 144b horizontally extended from an end of the long side portion <NUM>, and a third short side portion 144c horizontally extended from an end of the long side portion <NUM>. Here, the second short side portion 144b may include an inclined periphery located at a region facing the first short side portion 144a, and the third short side portion 144c may also include an inclined periphery located at a region facing the first short side portion 144a. In other words, the second and third short side portions 144b and 144c may be matched with or correspond to the first short side portion 144a. In addition, the width of each of the long side portions <NUM> and <NUM> may be substantially equal to that of each of the long sides of the bottom portion <NUM>. In addition, the width of the first short side portion 144a may be substantially equal to that of each of the short sides of the bottom portion <NUM>. In addition, the overall width of the second and third short side portions 144b and 144c may be substantially equal to the width of each of the short sides of the bottom portion <NUM>. In addition, the length of each of the long side portions <NUM> and <NUM> may be substantially equal to that of each of the short side portions <NUM> and <NUM>. In <FIG>, dashed lines indicate bending lines in a subsequent process to be described later.

<FIG> are partially enlarged plan views illustrating a method for manufacturing a secondary battery according to an example embodiment of the present invention. For clarity and brevity, <FIG> shows a first short side portion 144a extended from a bottom portion <NUM>, and second and third short side portions 144b and 144c extended from the long side portions <NUM> and <NUM>, respectively.

As shown in <FIG>, in some examples, in a region "4b," at least one or more protrusions 1440A may be provided between the first short side portion 144a and the second short side portion 144b, for example, a region where the first short side portion 144a and the second short side portion 144b meet, a connecting region where the first short side portion 144a and the second short side portion 144b are connected to each other, a vertex between the first short side portion 144a and the second short side portion 144b, a corner between the first short side portion 144a and the second short side portion 144b, or a corner joint region between the first short side portion 144a and the second short side portion 144b.

In addition, as shown in <FIG>, in some examples, in a region "4c," at least one or more protrusions 1440B may be provided between the first short side portion 144a and the third short side portion 144c, for example, a region where the first short side portion 144a and the third short side portion 144c meet, a connecting region where the first short side portion 144a and the third short side portion 144c are connected to each other, a vertex between the first short side portion 144a and the third short side portion 144c, a corner between the first short side portion 144a and the third short side portion 144c, or a corner joint region between the first short side portion 144a and the third short side portion 144c.

In some examples, the protrusions 1440A may include a first protrusion <NUM> located in the first short side portion 144a, and a second protrusion <NUM> located in the second short side portion 144b.

In addition, in some examples, the protrusions 1440B may include a first protrusion <NUM> located in the first short side portion 144a, and a third protrusion <NUM> located in the third short side portion 144c.

In addition, in some examples, the first protrusion <NUM> and the second protrusion <NUM> may be in an asymmetric configuration. In addition, in some examples, the first protrusion <NUM> and the third protrusion <NUM> may be in an asymmetric configuration.

As shown in <FIG>, in some examples, the first protrusion <NUM> may have a smaller area than the second protrusion <NUM>. In addition, as shown in <FIG>, in some examples, the first protrusion <NUM> may have a smaller area than the third protrusion <NUM>, or vice versa.

In some examples, the first, second, and third protrusions <NUM>, <NUM>, and <NUM> may be circular, triangular, quadrangular, pentagonal, or hexagonal. In addition, in some examples, if the first, second, and third protrusions <NUM>, <NUM>, and <NUM> are circular, the first protrusion <NUM> may have a smaller curvature radius than the second protrusion <NUM>. In addition, the first protrusion <NUM> may have a smaller curvature radius than the third protrusion <NUM>.

<FIG> are partially enlarged plan views illustrating a method for manufacturing a secondary battery according to an example embodiment of the present invention. As shown in <FIG>, in some examples, the first protrusion <NUM> may be larger (e.g., have a larger area) than the second protrusion <NUM>. In addition, as shown in <FIG>, in some examples, the first protrusion <NUM> may be larger (e.g., have a larger area) than the third protrusion <NUM>. In some examples, if the first, second, and third protrusions <NUM>, <NUM>, and <NUM> are circular, the first protrusion <NUM> may have a larger curvature radius than the second protrusion <NUM>. In addition, in some examples, the first protrusion <NUM> may have a larger curvature radius than the third protrusion <NUM>.

In some examples, the first, second, and third protrusions <NUM>, <NUM>, and <NUM> are provided by blanking and/or notching the metal plate 140A. Therefore, thicknesses of the first, second, and third protrusions <NUM>, <NUM>, and <NUM> may be equal to or similar to those of the bottom portion <NUM>, the first short side portion 144a, the second short side portion 144b, and the third short side portion 144c.

<FIG> are perspective views illustrating a method for manufacturing a secondary battery according to an example embodiment of the present invention. <FIG> show the can <NUM> at a later stage of manufacture. In the example shown in <FIG>, the metal plate 140A may be bent in a shape (e.g., a predetermined shape). In some examples, the metal plate 140A may be bent in a shape (e.g., a predetermined shape) after it is fixed by a bending machine or a press mold.

In some examples, the long side portions <NUM> and <NUM> bent and extended from the respective long sides of the bottom portion <NUM> in a substantially perpendicular direction, and the short side portions <NUM> and <NUM> bent and extended from the bottom portion <NUM> and the long side portions <NUM> and <NUM> in a substantially perpendicular direction, may be provided as the result of the bending process. That is, in an embodiment, the long side portions <NUM> and <NUM> may be bent approximately <NUM> degrees from the long sides of the bottom portion <NUM> to be extended. The short side portions <NUM> and <NUM> may be bent approximately <NUM> degrees from the short sides of the bottom portion <NUM> to be extended and may be bent approximately <NUM> degrees from the long side portions <NUM> and <NUM> to be extended.

Therefore, the first short side portion 144a, the second short side portion 144b, and the third short side portion 144c may be positioned to face one another and their peripheries may be matched and brought into contact with one another. In an embodiment, a vertex angle between the upper periphery of the first short side portion 144a and the short side of the bottom portion <NUM> may be in a range from approximately <NUM> degrees to approximately <NUM> degrees, and, in an embodiment, <NUM> degrees. In addition, an angle of a vertex of the first short side portion 144a, facing the second and third short side portions 144b and 144c, may be in a range from approximately <NUM> degrees to approximately <NUM> degrees, and, in an embodiment, <NUM> degrees.

In some examples, an angle defined between each of two upper peripheries of the first short side portion 144a and the short side of the bottom portion <NUM> may be in a range from approximately <NUM> degrees to approximately <NUM> degrees, and, in an embodiment, <NUM> degrees, an angle defined between the periphery of the second short side portion 144b facing an end of the periphery of the first short side portion 144a and an end of the long side portion <NUM> may be in a range from approximately <NUM> degrees to approximately <NUM> degrees, and, in an embodiment, <NUM> degrees, and an angle defined between the periphery of the third short side portion 144c facing another end of the periphery of the first short side portion 144a and an end of the long side portion <NUM> may be in a range from approximately <NUM> degrees to approximately <NUM> degrees, and, in an embodiment, <NUM> degrees. Accordingly, a vertex at which the bottom portion <NUM>, the end of the long side portion <NUM>, the first short side portion 144a, and the second short side portion 144b meet, and a vertex at which the bottom portion <NUM>, the end of the long side portion <NUM>, the first short side portion 144a, and the third short side portion 144c meet, may be bent in a substantially round shape.

In some examples, a pair of asymmetrical protrusions 1440A (<NUM> and <NUM>) are provided at a region or vertex where the first short side portion 144a and the second short side portion 144b meet, and a pair of asymmetrical protrusions 1440B (<NUM> and <NUM>) are provided at a region or vertex where the first short side portion 144a and the third short side portion 144c meet, thereby providing a curved portion 1550A (see <FIG>) at a region where the bottom portion <NUM>, the long side portion <NUM>, and the short side portions including the first short side portion 144a having the first protrusion <NUM> and the second short side portion 144b having the second protrusion <NUM>, meet, and a curved portion 1550B (see <FIG>) at a region where the bottom portion <NUM>, the long side portion <NUM>, and the short side portions including the first short side portion 144a having the first protrusion <NUM> and the third short side portion 144c having the third protrusion <NUM>, meet.

<FIG> shows an example in which the short side portions <NUM> and <NUM> are bent from the long side portions <NUM> and <NUM>, respectively. That is, <FIG> shows an example in which the long side portions <NUM> and <NUM> have yet to be bent from the bottom portion <NUM>.

<FIG> shows the can <NUM> at a later stage of manufacture. In the example shown in <FIG>, a bending process and a welding process may be performed.

Similarly as above, in some examples, when the long side portion <NUM>, the first short side portion 144a, and the second short side portion 144b are bent with respect to the bottom portion <NUM>, the protrusions 1440A, i.e., the first protrusion <NUM> and the second protrusion <NUM>, are positioned to overlap with each other or to be piled up one on another, thereby providing the symmetrical curved portion 1550A at a corner where the bottom portion <NUM>, the long side portion <NUM>, the first short side portion 144a, and the second short side portion 144b meet.

In addition, in some examples, when the long side portion <NUM>, the first short side portion 144a, and the second short side portion 144b are bent with respect to the bottom portion <NUM>, the protrusions 1440B, i.e., the first protrusion <NUM> and the third protrusion <NUM>, are positioned to overlap with each other or to be piled up one on another, thereby providing the symmetrical curved portion 1550B at a corner where the bottom portion <NUM>, the long side portion <NUM>, the first short side portion 144a, and the third short side portion 144c meet.

In addition, in some examples, welding portions <NUM> may be provided in the short side portions <NUM> and <NUM>. In some examples, the welding portions <NUM> may include a first welding portion 146a, a second welding portion 146b, and a third welding portion 146c. The first welding portion 146a may be located at a boundary region between the first short side portion 144a and the second short side portion 144b and may extend from the curved portion 1550A provided at a corner where the bottom portion <NUM>, the long side portion <NUM>, the first short side portion 144a, and the second short side portion 144b meet. The second welding portion 146b may be located at a boundary region between the first short side portion 144a and the third short side portion 144c and may extend from the curved portion 1550B provided at a corner where the bottom portion <NUM>, the long side portion <NUM>, the first short side portion 144a, and the third short side portion 144c meet. The third welding portion 146c may be located at a boundary region between the second short side portion 144b and the third short side portion 144c.

In other words, the first welding portion 146a may be at an acute angle with respect to a short side of the bottom portion <NUM> in the curved portion 1550A where the bottom portion <NUM>, the end of the long side portion <NUM>, the first short side portion 144a, and the second short side portion 144b meet, and the second welding portion 146b may be at an acute angle with respect to the short side of the bottom portion <NUM> in the curved portion 1550B where the bottom portion <NUM>, the end of the long side portion <NUM>, the first short side portion 144a, and the third short side portion 144c meet. In addition, the third welding portion 146c may be extended from a bottom end of the second and third short side portions 144b and 144c to a top end (i.e., an opening <NUM>) of the second and third short side portions 144b and 144c.

In some examples, the first and second welding portions 146a and 146b may be consecutively formed, and the third welding portion 146c may then be formed, or vice versa. In an embodiment, the welding process may be performed on the first welding portion 146a, the third welding portion 146c, and the second welding portion 146b in that order; however, the welding order may be reversed. In an embodiment, the welding process performed on the third welding portion 146c may be started from the bottom end and may be terminated at the top end, or vice versa. In some examples, the first, second, and third welding portions 146a, 146b, and 146c may include a butt joint structure, a lap joint structure, an overlay joint structure, or an edge joint structure. In some examples, the welding portions <NUM> may be in a substantially inverted Y-shaped ("<IMG>") configuration. In an embodiment, the welding portions <NUM> may be provided to have a solid-line shape. Therefore, the first short side portion 144a may be securely fixed to the second and third short side portions 144b and 144c due to the first and second welding portions 146a and 146b, and the second and third short side portions 144b and 144c may be securely fixed to each other by the third welding portion 146c.

In an embodiment, the first and second welding portions 146a and 146b connected to each other may be shaped of straight lines having at least one vertex, and the third welding portion 146c may be shaped of a straight line extending from the vertex, where the first and second welding portions 146a and 146b meet, to the opening <NUM>. In an embodiment, a vertex angle defined between the first welding portion 146a and the second welding portion 146b may be in a range from approximately <NUM> degrees to approximately <NUM> degrees, and, in an embodiment, <NUM> degrees. In an embodiment, an angle in a range from approximately <NUM> degrees to approximately <NUM> degrees, and, in an embodiment, <NUM> degrees, may be defined between the first welding portion 146a and the short side of the bottom portion <NUM>, and an angle in a range from approximately <NUM> degrees to approximately <NUM> degrees, and, in an embodiment, <NUM> degrees, may also be defined between the second welding portion 146b and the short side of the bottom portion <NUM>.

As described above, an embodiment of the present invention provides the can <NUM> configured such that the first short side portion 144a is bent and extended from the bottom portion <NUM>, and asymmetrical protrusions 1440A and 1440B are provided at the vertex (corner) between the first short side portion 144a and the second short side portion 144b and at the vertex (corner) between the first short side portion 144a and the third short side portion 144c, thereby providing symmetrical curved portions 1550A and 1550B, which are desirable, at regions where three or four sides meet, respectively. In addition, the first, second, and third welding portions 146a, 146b, and 146c are provided from the curved portions 1550A and 1550B along interfaces (e.g., cutting lines) between each of the first, second, and third short side portions 144a, 144b, and 144c to be connected to one another to construct a single short side portion <NUM>, thereby providing the can <NUM> having increased bending and welding workability and improved sealing efficiency to prevent or substantially prevent leakage of an electrolyte.

Here, as a result of the bending process, curved portions may also be provided between the bottom portion <NUM> and the first short side portion 144a, between the bottom portion <NUM> and each of the long side portions <NUM> and <NUM>, between the long side portion <NUM> and the second short side portion 144b, and between the long side portion <NUM> and the third short side portion 144c.

In some examples, as described above, the curved portion 1550A having a round shape may be provided at the corner where the bottom portion <NUM>, the long side portion <NUM>, the first short side portion 144a and the second short side portion 144b meet by the asymmetrical protrusions 1440A. In addition, as described above, the curved portion 1550B having a round shape may be provided at the corner where the bottom portion <NUM>, the long side portion <NUM>, the first short side portion 144a and the third short side portion 144c meet by the asymmetrical protrusions 1440B. In some examples, the curvature radii of the curved portions 1550A and 1550B located at regions where three or four sides meet may be smaller than those of the curved portions located at regions where the two sides meet, thereby providing the generally stable can <NUM>.

In some examples, prior to formation of the welding portions <NUM>, a temporary welding portion may first be provided at a boundary region between the first short side portion 144a and the second short side portion 144b, a boundary region between the first short side portion 144a and the third short side portion 144c, and/or a boundary region between the second short side portion 144b and the third short side portion 144c. In an embodiment, the temporary welding portion may include multiple temporary welding portions spaced apart from one another. In some examples, the temporary welding portions may be provided to have substantially dotted-line shapes. The temporary welding portions may prevent or substantially prevent spring back phenomena from occurring to the long side portions <NUM> and <NUM>, the short side portions <NUM> and <NUM> and the bottom portion <NUM>. In addition, the temporary welding portions can securely fix the long side portions <NUM> and <NUM> and the short side portions <NUM> and <NUM> to each other. Accordingly, the main welding portions <NUM> (i.e., the welding portions <NUM>) can be easily provided. In an embodiment, the temporary welding portions may be provided by ultrasonic welding or resistance welding, as well as laser welding.

<FIG> and <FIG> are partially enlarged plan views illustrating a method for manufacturing a secondary battery according to an example embodiment of the present invention. As shown in <FIG>, in some examples, a protrusion 1440C may be provided substantially at the center of a region where a first short side portion 144a and a second short side portion 144b (or a third short side portion) meet. In some examples, the protrusion 1440C may be provided substantially at the center of the region where the first short side portion 144a and the second short side portion 144b (or the third short side portion) meet, in a substantially symmetrically round shape, but the shape of the protrusion 1440C is not limited thereto. Rather, the protrusion 1440C may have any of the shapes of the above-described protrusions.

As shown in <FIG>, in some examples, a protrusion 1440D may be connected longer (or more widely) to the second short side portion 144b (or the third short side portion) than to the first short side portion 144a. In some other examples, the protrusion 1440D may be connected longer (or more widely) to the first short side portion 144a than to the second short side portion 144b (or the third short side portion). Accordingly, in some examples, the protrusion 1440D may have an asymmetric configuration around a region where the first short side portion 144a and the second short side portion 144b meet (e.g., a vertex or a corner). Similarly as above, the protrusion 1440D may be provided in a substantially round shape, but the shape of the protrusion 1440D is not limited thereto. Rather, the protrusion 1440D may have any of the shapes of the above-described protrusions.

As described above, in an embodiment, when a metal plate is blanked and/or notched, the protrusions 1440A, 1440B, 1440C and 1440D, may be integrally formed at the boundary region between the first short side portion 144a and the second short side portion 144b or at the boundary region between the first short side portion 144a and the third short side portion 144c.

However, in some examples, the protrusions 1440A, 1440B, 1440C, and 1440D may be separately provided (for example, provided as individual pieces) to then be inserted or connected to the boundary region between the first short side portion 144a and the second short side portion 144b or the boundary region between the first short side portion 144a and the third short side portion 144c.

In addition, in some examples, the long side portions <NUM> and <NUM> and the first short side portion 144a are bent from the bottom portion <NUM>, and the second and third short side portions 144b and 144c are bent from the long side portions <NUM> and <NUM>, as described above, the protrusions 1440A, 1440B, 1440C, and 1440D, to then be inserted or connected to the corners of three or four sides, where these side portions meet (for example, a region where the first short side portion 144a and the second short side portion 144b meet, and a region where the first short side portion 144a and the third short side portion 144c meet).

In addition, in some examples, the protrusions 1440A, 1440B, 1440C, and 1440D, which are separately provided and inserted or connected between the first and second short side portions 144a and 144b, and the protrusions 1440A, 1440B, 1440C and 1440D, which are inserted or connected between the first and third short side portions 144a and 144c, may be integrated with the can <NUM> through a welding process.

As described above, since the protrusion(s) are located at the regions where the first short side portion bent from the bottom portion and the second and third short side portions bent from the long side portions meet, desirably shaped curved portions in a symmetric configuration may be provided by the protrusions when the first short side portion and the second and third short side portions are bent. In addition, since the desirably shaped curved portions in a symmetric configuration are provided by the protrusion(s) and distances between boundary regions of the curved portions and the first, second, and third short side portions are reduced, welding can be easily performed, thereby preventing or substantially preventing pinholes from being generated at the boundary regions. In addition, when multiple batteries are assembled or stacked to manufacture a battery module or pack at a later stage, the symmetrical curved portions may not interfere with other batteries, thereby preventing or substantially preventing insulation breakdowns from occurring among the batteries. However, if the curved portions are asymmetrically configured, insulation layers of other neighboring batteries may be damaged by the asymmetrical curved portions, resulting in insulation breakdowns among the neighboring batteries.

Claim 1:
Method of manufacturing a secondary battery, comprising the steps:bending and extending long side portions (<NUM>, <NUM>) from a bottom portion (<NUM>) of a metal plate (140A),
bending and extending a first short side portion (144a) from the bottom portion (<NUM>) of the metal plate (140A),
bending and extending second short side portions (144b, 144c) from the long side portions (<NUM>, <NUM>), wherein protrusions (1440A, 1440B, 1440C, 1440D) are located at regions where the first short side portion (144a) and the second short side portions (144b, 144c) meet and are overlapped with each other in the bending,
connect the first short side portion (144a) and the second short side portions (144b, 144c) to each other by welding to define a short side portion (<NUM>) and to form a case (<NUM>),
accommodating an electrode assembly (<NUM>, <NUM>) in the case (<NUM>),
couple a cap assembly (<NUM>) to the case (<NUM>) to seal the case (<NUM>).