Patent Description:
The present invention relates to a secondary battery and a method for manufacturing the same, and more particularly, to a button-type secondary battery in which an internal space increases to mount a larger electrode assembly, thereby increasing in capacity, and a method for manufacturing the secondary battery.

In general, a button-type battery commonly used as a coin-type battery or a button-type battery has a thin button shape and is widely used in various devices such as remote controllers, clocks, toys, computer parts, and the like.

Such a button-type battery is mainly manufactured as a non-rechargeable primary battery, but is also widely manufactured as a secondary battery that is chargeable and dischargeable as miniaturized devices are developed. Also, the button-type secondary battery also has a structure in which an electrode assembly and an electrolyte are embedded in a case to repeatedly perform charging and discharging, like the button-type secondary battery or the cylindrical or pouch-type secondary battery.

<FIG> is a cross-sectional view illustrating a button-type secondary battery according to the related art. As illustrated in <FIG>, an outer appearance (a shape in which a first can and a second can are coupled to each other) of the button-type secondary battery has a flat cylindrical shape similar to a schale. When an electrode assembly <NUM> is seated in the first can <NUM> with an upper side opened, peripheral components (not shown) of the electrode assembly <NUM> are mounted, and the electrolyte (comprising a liquid electrolyte) is injected, and then, the second can <NUM> covers the upper side of the first can <NUM>.

Here, clamps 1a and 2a to be fitted to each other are provided in an upper edge portion of a side surface of the first can <NUM> and an edge portion of the second can <NUM>, respectively. That is, the edge portions of the first can <NUM> and the second can <NUM> are bent to form the clamps 1a and 2a so that the edge portions are engaged with and coupled to each other when the second can <NUM> is placed on the electrode assembly <NUM>. Here, in a state in which each of the clamps 1a and 2a is elastically deformed by a pressure generated when the second can <NUM> is inserted, when the second can <NUM> is completely inserted, the clamps 1a and 2a may be elastically restored to be coupled to each other as illustrated in the drawing.

Also, a gasket <NUM> made of a rubber material may be inserted between the clamps 1a and 2a to seal the inside.

Further prior art is disclosed in <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT> and <CIT>.

In the coupling manner using the clamps as described above, since a height of the internal space between the first can <NUM> and the second can <NUM> is less than the total height (a height from the lowest end to the highest end of the battery) to limit a size of the electrode assembly <NUM>, it is difficult to increase in capacity of the battery relative to the total volume of the battery.

Therefore, a main object of the present invention is to provide a button-type secondary battery in which an internal space is more largely secured when compared to the structure according to the related art to secure more increasing capacity (in which a larger electrode assembly is capable of being mounted) with respect to the same volume, and a method for manufacturing the secondary battery.

The present invention for achieving the above object provides a button-type secondary battery, which more increases in internal space, and a method for manufacturing the secondary battery.

A button-type secondary battery according to the present invention comprises: a first can of which a first side surface is vertically disposed along a circumference of a first base surface; a second can which has a second base surface having a diameter greater than that of the first base surface of the first can and of which a second side surface is vertically disposed along a circumference of the second base surface, wherein a vent hole is punched in the second side surface; and a gasket disposed between the first side surface and the second side surface when the first can and the second can are coupled to each other, wherein the first can and the second can are coupled to each other so that the first side surface is inserted inside the second side surface and the gasket is deformed so that the gasket is fitted into the vent hole, thereby fixing the first can and the second can, the gasket being deformed to a size corresponding to a difference between a pressure inside a space defined by the first can and the second can and a pressure outside the first can and the second can.

In the present invention, the first side surface of the first can may be disposed to face an upper side from the first base surface, and the second side surface of the second can may be disposed to face a lower side from the second base surface so that the second can is coupled to cover an upper side of the first can.

In an embodiment of the present invention, at least two or more vent holes may be defined along a circumference of the second side surface of the second can.

Furthermore, a method for manufacturing a button-type secondary battery according to the present invention, in which a first can of which a first side surface is vertically disposed along a circumference of a first base surface and a second can which has a second base surface having a diameter greater than that of the first base surface of the first can and of which a second side surface is vertically disposed along a circumference of the second base surface are coupled to each other, comprises: a step of preparing the first can; a step of preparing the second can; a punching step in which a vent hole punched in the second side surface of the second can; a coupling step in which a gasket is disposed between the first side surface of the first can and the second side surface of the second can (after an electrode assembly and an electrolyte are mounted), and the first can and the second can are coupled to allow the gasket to cover the vent hole; and a fixing step in which the gasket is deformed to allow the gasket to be fitted into the vent hole so as to fix the first can and the second can, wherein, in the fixing step, when a negative pressure is applied to the vent hole from the outside of the gasket, the gasket is deformed to be fitted into the vent hole.

In the present invention, the method may further comprise a temporary fixing step in which the first can and the second can are fixed before the negative pressure is applied to the vent hole.

Also, the negative pressure may be applied in a state in which the gasket is attached to the first side surface of the first can.

Furthermore, the negative pressure is applied in a state in which a partial region of the gasket to be deformed is attached with adhesion force lower than that of each of other regions or is not attached (thereby preventing the first side surface of the first can from being deformed).

Also, a partial region of the gasket to be deformed has a thickness different from that of each of other regions (so that the negative pressure is concentrated to more easily cause the deformation).

In the punching step, at least two or more vent holes may be formed along a circumference of the second side surface of the second can.

According to the present invention having the configuration as described above, since the coupling point of the first can and the second can moves from the upper side to the side surface of the battery, the height of the internal space relative to the total height may increase, and thus, the electrode assembly having the larger capacity may be mounted.

According to the present invention, since the gasket is deformed to be fitted into the vent hole so as to fix the first can and the second can, each of the first can and the second can may have the smooth surface.

Since the gasket is deformed to the size corresponding to the difference between the pressure inside the space defined by the first can and the second can and the pressure outside the first can and the second can, the physical pressure causing the stress and/or the unnecessary deformation may not be applied to the first can and the second can.

Since at least two or more vent holes are formed, the coupling force may be adjusted according to the required specification.

Also, in the state in which the partial region of the gasket to be deformed is attached with adhesive force lower than that of each of other regions or is not attached, the negative pressure may be applied to prevent the first side surface of the first can from being deformed.

Also, the partial region of the gasket to be deformed may have a thickness greater than that of each of other regions and thus may be more easily deformed.

The present invention provides a button-type secondary battery having an internal space greater than that of the structure according to the related art and a method for manufacturing the secondary battery. Hereinafter, embodiments of the present invention will be described in more detail with reference to accompanying drawings.

The present invention provides a button-type secondary battery having an internal space greater than that of the structure according to the related art as Embodiment <NUM>. The secondary battery of the present invention has a feature in which a gasket <NUM> disposed between a first can <NUM> and a second can <NUM> is fitted into and fixed to a vent hole <NUM> defined in the second can <NUM>.

Referring to <FIG>, the first can <NUM> has a circular first base surface <NUM> having a predetermined size, and a first side surface <NUM> is vertically disposed along a circumference of the first base surface <NUM>. Also, the second can <NUM> has a circular second base surface <NUM> having a diameter greater than that of the first base surface <NUM> of the first can <NUM>, and a second side surface <NUM> is vertically disposed along a circumference of the second base surface <NUM>. In addition, a vent hole <NUM> is punched in the second side surface <NUM>. That is, each of the first can <NUM> and the second can <NUM> has a flat cylindrical shape similar to a schale. Here, the second can <NUM> has an area slightly greater than that of the first can <NUM>, and the vent hole <NUM> is additionally punched in the second can <NUM>.

In this embodiment, the first side surface <NUM> of the first can <NUM> faces an upper side from the first base surface <NUM>, and the second side surface <NUM> of the second can <NUM> faces a lower side from the second base surface <NUM> so that the second can <NUM> covers an upper side of the first can <NUM>. Here, the first can <NUM> is coupled to the second can <NUM> in a state in which the gasket <NUM> having a ring shape) is fitted into an outer circumferential surface of the first side surface <NUM>. Thus, when the first can <NUM> is coupled to the second can <NUM>, the gasket <NUM> is disposed between the first side surface <NUM> and the second side surface <NUM>. For reference, here, the gasket <NUM> may be in a state in which a portion or the whole of the gasket <NUM> is attached to the first side surface <NUM>.

Also, in a state in which the first side surface <NUM> is inserted inside the second side surface <NUM>, the gasket <NUM> coupled to the outer circumferential surface of the first side surface <NUM> faces an inner circumferential surface of the second side surface <NUM>. Here, since the gasket <NUM> is exposed through the vent hole <NUM> defined in the second side surface, when a negative pressure is applied to the vent hole <NUM>, a portion of the gasket <NUM> is deformed to be fitted into the vent hole <NUM>.

That is, the gasket <NUM> may be deformed to a size corresponding to a difference between a pressure inside a space defined by the first can <NUM> and the second can <NUM> and a pressure outside the first can <NUM> and the second can <NUM> to fix the first can <NUM> and the second can <NUM>.

Furthermore, in an embodiment of the present invention, although one vent hole <NUM> is illustrated in the drawings, at least two or more vent holes may be defined along a circumference of the second side surface <NUM> of the second can <NUM>. For example, the second can <NUM> has a circular plate shape on a plane. In <FIG>, which shows examples of embodiments not belonging to the present invention, the vent hole <NUM> may be provided in even numbers, and the vent holes <NUM> may be disposed in pairs to be symmetric to each other with respect to a center of the circular plate (see <FIG>). For reference, <FIG> illustrates positions at which the vent holes <NUM> are defined when the second can <NUM> is viewed upward or downward, i.e., illustrates a transverse cross-sectional view of the second can at the portions in which the vent holes are defined.

In another configuration, the second can <NUM> has a circular plate shape on the plane. Here, the vent holes <NUM> may be disposed to be denser in a specific region than other regions with respect to a circumference of the circular plate shape (see <FIG>).

Furthermore, the present invention provides a method for manufacturing a button-type secondary battery having the above-described configuration as Embodiment <NUM>.

The manufacturing method according to the present invention comprises a step of preparing (providing) a first can <NUM> in which a first side surface <NUM> is vertically formed along a circumference of a first base surface <NUM> and a step of preparing (providing) a second can <NUM> which has a second base surface <NUM> having a diameter greater than that of the first base surface <NUM> and in which a second side surface <NUM> is vertically formed along a circumference of the second base surface <NUM>.

Since the first can <NUM> and the second can <NUM> are provided through the known molding method according to the related art, detailed description thereof will be omitted. Also, in the provided second can <NUM>, a vent hole <NUM> having a predetermined size is punched in predetermined numbers in the second side surface <NUM>. The punching of the vent hole <NUM> may be performed through the known method such as punching or drilling according to a material of the second can <NUM>.

Also, after an electrode assembly is seated in the first can <NUM>, and an electrolyte or the like is additionally mounted in the state in which the first side surface is placed to face an upper side, the second can <NUM> covers an upper side of the first can <NUM> in a state in which the second side surface is placed to face a lower side. Here, before the second can <NUM> covers the first can <NUM>, a gasket <NUM> is coupled to the first can <NUM> so as to be fixed to an outer circumferential surface of the first side surface <NUM>. The gasket <NUM> may be coupled to the first can <NUM> before the electrode assembly is seated or may be coupled to the first can <NUM> after the electrode assembly is seated. Alternatively, the gasket <NUM> may be attached to the first side surface <NUM> by using an adhesive or through a method such as thermal fusion.

Thus, when the first can <NUM> and the second can <NUM> are coupled to each other, the gasket <NUM> is disposed between the first side surface <NUM> and the second side surface <NUM>, and the gasket <NUM> faces the vent hole <NUM> (the gasket is exposed to the outside through the vent hole when viewed from the outside of the vent hole).

Also, the gasket <NUM> may be deformed to fix the first can <NUM> and the second can <NUM>. In an embodiment of the present invention, as illustrated in <FIG> and <FIG>, when a vacuum hose <NUM> is connected to the vent hole <NUM> of the second can <NUM> while a pressure is vertically and horizontally applied to fix the first can <NUM> and the second can <NUM> (or the first can <NUM> and the second can <NUM> are fitted into a fixed position or coupled to the exclusive bracket so as to be limited in movement) in a state in which the first can <NUM> and the second can <NUM> are placed on a flat surface plate <NUM>, a negative pressure is generated in the first can <NUM> and the second can <NUM> to deform the first can <NUM> and the second can <NUM>.

Here, since the inner space of the first can <NUM> and the second can <NUM> is filled with the electrode assembly and the electrolyte, the first can <NUM> and the second can <NUM> may be supported even though the negative pressure is applied. On the other hand, since a space between the first side surface <NUM> and the second side surface <NUM> is a point at which the negative pressure is applied and thus has relatively weak supporting force, the deformation may occur. When the deformation occurs by the negative pressure, as illustrated in <FIG>, a portion of the first side surface <NUM> may be deformed together with the gasket <NUM>. Alternatively, as illustrated in <FIG>, only the gasket <NUM> may be deformed without deforming the first side surface <NUM>.

The above-described difference may be determined by magnitude of the applied negative pressure, an area to which the negative pressure is applied, adhesion between the gasket <NUM> and the first side surface <NUM>, a material of the first can <NUM>, and the like and also may be differently designed according to a required design specification. Furthermore, when a portion of the first side surface <NUM> is deformed as illustrated in <FIG>, a groove may be locally formed so that the (plastic or elastic) deformation increases in the first side surface <NUM>. Particularly, the groove may be locally formed at a portion of the first side surface <NUM> at which bending occurs. Also, the gasket <NUM> may adhere to the first side surface with greater adhesive force at a portion of the gasket <NUM> to which the pressure is concentrated to cause the deformation of the gasket <NUM>. On the other hand, when only the gasket is deformed without the deformation of the first side surface <NUM> as illustrated in <FIG>, it is preferable that the adhesion force between the first side surface <NUM> and the gasket <NUM> is less than that of each of other points at a specific portion at which the deformation of the gasket <NUM> occurs.

As illustrated in <FIG>, a path through which air moves between the first side surface <NUM> and the second side surface <NUM> may be narrower than other portions within the first can <NUM> and the second can <NUM>. However, if the applied negative pressure is low, or the space between the first side surface <NUM> and the second side surface <NUM> is sufficient large, sufficient deformation may not occur. Thus, a distance between the first side surface <NUM> and the second side surface <NUM> has to be sufficiently short so that the gasket <NUM> is sufficiently deformed to be fitted into and fixed to the vent hole <NUM>, and the negative pressure to be applied may be sufficient high. That is, when a negative pressure may be applied due to the Bernoulli's theorem, in which a flow velocity of a fluid increases, but an inner pressure decreases when the fluid flowing through a wider cross-section flows through a narrower cross-section, so that air flows, a pressure between the first side surface <NUM> and the second side surface <NUM> is relatively lower than that of each of other points. Thus, since the first can <NUM> and the second can <NUM> are in the fixed state, a pressure is applied to the gasket <NUM> in a direction in which the gasket <NUM> is inserted into the vent hole <NUM> (a direction in which the first can <NUM> and the second can <NUM> are in close contact with each other) to cause the deformation. For reference, when the vent hole <NUM> is provided in plurality, it may be preferable that the negative pressure is applied to a corresponding vent hole <NUM> in a state in which rest vent holes except for the corresponding vent hole <NUM> are blocked (through a separate mechanism or the like) to prevent pressure leakage from occurring in the rest vent holes.

Furthermore, when the distance between the first side surface <NUM> and the second side surface <NUM> increases due to a problem in the manufacturing process or other reasons, as illustrated in <FIG>, a portion of the gasket <NUM> may protrude toward the vent hole <NUM> (so that the distance between the first side surface and the second side surface decreases to cause an effect of the concentration of the negative pressure). That is, a portion of the gasket <NUM> may be manufactured to be thicker according to the distance between the first side surface <NUM> and the second side surface <NUM>, the magnitude of the negative pressure, the size of the vent hole <NUM>, or the like.

In conclusion, in the manufacturing method according to an embodiment of the present invention, the movement of the first can <NUM> and the second can <NUM> may be interrupted (temporarily before being fixed by the gasket) before the negative pressure is applied and thus be in a temporarily fixed state. Here, the material of the first can <NUM>, the adhesion between the first can <NUM> and the gasket <NUM>, the thickness of the gasket <NUM>, and the like may be differently designed according to the sizes of the first can <NUM> and the second can <NUM>, the magnitude of the negative pressure, and the like.

Also, the elastic or plastic deformed gasket <NUM> has to be maintained in the fitted state but does not need to protrude from the vent hole (so as to maintain a smooth outer surface). Also, even if a portion of the gasket <NUM> protrudes, the protruding portion may be cut to maintain the smooth outer surface, and the adhesive or the like may be additionally applied in the state of protruding to increase in fixing force (so that the deformed portion of the gasket is firmly fixed to the second can).

As described above, in the punch step, a plurality of vent holes <NUM> are punched along a circumference of the second side surface <NUM> of the second can <NUM>. That is, as illustrated in <FIG>, the vent holes may be provided in pairs in the direction facing each other (see FIGS. 5I, <FIG>) or may be concentrated to one side to increase in coupling force in a specific direction (see <FIG>).

According to the present invention having the configuration as described above, since the coupling point of the first can <NUM> and the second can <NUM> moves from the upper side to the side surface of the battery, the height of the internal space relative to the total height may increase, and thus, the electrode assembly having the larger capacity may be mounted. Also, since the gasket <NUM> is deformed to be fitted into the vent hole <NUM> so as to fix the first can <NUM> and the second can <NUM>, each of the first can <NUM> and the second can <NUM> may have the smooth outer surface.

Also, since the gasket <NUM> is deformed to the size corresponding to the difference between the pressure inside the space defined by the first can <NUM> and the second can <NUM> and the pressure outside the first can <NUM> and the second can <NUM>, the physical pressure causing the stress and/or the unnecessary deformation may not be applied to the first can <NUM> and the second can <NUM>. Also, since at least two or more vent holes <NUM> are formed, the coupling force may be adjusted according to the required specification.

Claim 1:
A secondary battery comprising:
a first can (<NUM>) of which a first side surface (<NUM>) is vertically disposed along a circumference of a first base surface (<NUM>);
a second can (<NUM>) which has a second base surface (<NUM>) having a diameter greater than that of the first base surface (<NUM>) of the first can (<NUM>) and of which a second side surface (<NUM>) is vertically disposed along a circumference of the second base surface (<NUM>), characterized in that a vent hole (<NUM>) is punched in the second side surface (<NUM>); and
a gasket (<NUM>) disposed between the first side surface (<NUM>) and the second side surface (<NUM>) when the first can (<NUM>) and the second can (<NUM>) are coupled to each other,
wherein the first can (<NUM>) and the second can (<NUM>) are coupled to each other so that the first side surface (<NUM>) is inserted inside the second side surface (<NUM>) and the gasket (<NUM>) is deformed so that the gasket (<NUM>) is fitted into the vent hole (<NUM>), thereby fixing the first can (<NUM>) and the second can (<NUM>),
wherein the gasket (<NUM>) is deformed to a size corresponding to a difference between a pressure inside a space defined by the first can (<NUM>) and the second can (<NUM>) and a pressure outside the first can (<NUM>) and the second can (<NUM>).