Patent Description:
A button-type battery commonly used as a coin-type battery or a button-type battery has a thin button shape of which a diameter is greater than a height 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 of a button-type secondary battery according to a related art.

As illustrated in the drawing, a button-type secondary battery has a structure, in which an upper can <NUM> and a lower can <NUM> are coupled to each other. Here, each of the upper can <NUM> and the lower can <NUM> has a flat cylindrical shape having a diameter greater than a height thereof, and the upper can <NUM> has a diameter slightly greater than that of the lower can <NUM>.

An electrode assembly <NUM>, in which a positive electrode, a separator, and a negative electrode are stacked, and an electrolyte (not shown) are mounted in the lower can <NUM>. The electrode assembly <NUM> has a structure in which the separator, the negative electrode, the separator, and the positive electrode are put in and wound on a rotating core in order, and a center pin <NUM> is inserted into a center hole from which the core is removed. Also, a negative electrode tab (not shown) extending from the negative electrode and a positive electrode tab (not shown) extending from the positive electrode protrude, and the negative electrode tab and the positive electrode tab are bonded to the lower can <NUM> and the upper can <NUM>, respectively.

In addition, in order to prevent short circuit from occurring when the upper can <NUM> and the lower can <NUM> are coupled to each other, an end of the upper can <NUM> may be coupled to the lower can <NUM> while being bent to press a gasket <NUM> in a state in which the gasket <NUM> having no conductivity is disposed at a contact point at which the upper can <NUM> and the lower can <NUM> are in contact with each other.

<CIT> concerns a rechargeable hearing aid battery with slotted grommet. The battery includes a first cup, having a first sidewall in a vertical direction along a circumference of a first flat portion, and a second cup, having a second sidewall in a vertical direction along a circumference of a second flat portion. The outer diameter of the first cup is less than the inner diameter of the second cup such that the first cup may be inserted into cavity. The battery further includes an active core comprising an electrode assembly and a grommet. The upper cup and active core are fixed in position relative to the second cup by folding or crimping an upper edge of the second cup over a top wall of the first cup.

However, the above-described coupling method has a problem in that the upper can and the lower can are separated from each other when the external impact is applied. Therefore, a main object of the present invention for solving the above problems is to provide a button-type secondary battery having a structure that is more robust to an external impact.

A button-type secondary battery, in which an electrode assembly is mounted in a lower can, and an upper can is coupled to the lower can according to the present invention for achieving the above objects is defined in claim <NUM>. The button-type secondary battery comprises: the lower can having a first sidewall in a vertical direction along a circumference of a first flat portion; an upper can having a second sidewall in a vertical direction along a circumference of a second flat portion, wherein the upper can is coupled to the lower can so that the second flat portion faces the first flat portion, and the second sidewall is disposed outside the first sidewall; an electrode assembly in which a negative electrode, a separator, and a positive electrode are wound in a state of being stacked and which is mounted in an inner space between the lower can and the upper can so that the negative electrode is connected to the lower can, and the positive electrode is connected to the upper can; and a gasket disposed between the second sidewall and the first sidewall to prevent the upper can and the lower can from being in contact with each other, wherein the second sidewall comprises a distant end that is bent to surround an edge configured to connect the first flat portion to the first sidewall and is disposed below the first flat portion, and the gasket extends to be disposed between the distal end and the first flat portion.

An exposed portion protruding to the outside through the distal end is formed on an end of the gasket, and the exposed portion is disposed below the first flat portion.

The exposed portion is expanded downward from the distal end and is bent to cover a portion of a bottom surface of the distal end.

The second sidewall may comprise: a body portion bent from the second flat portion; and an expansion portion configured to connect the body portion to the distal end having a diameter that is expanded rather than the body portion.

An inclined portion having an inclined cross-sectional shape to be gradually expanded in diameter may be formed between the body portion and the expansion portion. In addition, a connection point between the expansion portion and the distal end may be curved at a predetermined curvature.

The exposed portion exposed at the distal end may have a thickness that is capable of forming a flat surface together with the distal end.

A protrusion protruding downward to have the same height as the distal end may be disposed on the first flat portion.

The exposed portion exposed at the distal end may have a thickness that is capable of forming a flat surface together with the distal end, and a protrusion protruding downward to have the same height as the distal end may be disposed on the first flat portion so that the protrusion, the exposed portion, and the distal end form a flat surface.

Furthermore, the present invention may provide a secondary battery module in which the plurality of button-type secondary batteries, each of which has the above configuration, are electrically connected to each other.

In the present invention having the above configuration, the distal end formed on the end of the second sidewall of the upper can may surround the edge connecting the first flat portion to the first sidewall and be bent to be parallel to the first flat portion to increase in coupling force between the upper can and the lower can compared to the structure according to the related art.

The exposed portion disposed below the first flat portion by passing through the distal end to protrude to the outside may be formed on the end of the gasket to more reliably prevent the electrical short between the upper can and the lower can from occurring.

Since the exposed portion forms a flat surface together with the distal end, the possibility of occurrence of the unintentional short circuit by the metal object may be more reduced.

Since the exposed portion is expanded downward from the distal end and is bent to cover a portion of the bottom surface of the distal end, the possibility of occurrence of the short circuit may be more reduced, and thus, the distal end may be protected against the physical impact.

Hereinafter, comparative examples, not according to the claimed invention but useful for understanding the invention, and an embodiment of the present invention will be described in detail with reference to the accompanying drawings in such a manner that the technical idea of the present invention may easily be carried out by a person with ordinary skill in the art to which the invention pertains. The present invention may, however, be embodied in different forms within the scope of the appended claims and should not be construed as limited to the embodiments set forth herein.

In order to clearly describe the present invention, parts irrelevant to the description are omitted, and the same reference numerals are assigned to the same or similar components throughout the specification.

The present invention relates to a button-type secondary battery having a shape of which a diameter is greater than a height thereof and provides a button-type secondary battery having a structure in which a lower can <NUM> and an upper can <NUM> are more strongly coupled to each other. Hereinafter, embodiments according to the present invention will be described with reference to the accompanying drawings.

<FIG> is a longitudinal cross-sectional view illustrating a state in which a distal end <NUM> of an upper can <NUM> is bent downward from a first flat portion <NUM> of a lower can <NUM> to couple the upper can <NUM> to the lower can <NUM> according to a first comparative example not forming part of the claimed invention.

Referring to the drawings, in this comparative example, an electrode assembly <NUM> has a structure in which a separator, a negative electrode, a separator, and a positive electrode are sequentially put to be wound around a rotating core, and then a center pin <NUM> is inserted when the core is removed and also has a structure in which a positive electrode tab (not shown) extending from the positive electrode protrudes from one surface (a top surface in the drawing), and a negative electrode tab (not shown) extending from the negative electrode protrudes from the other surface (a bottom surface in the drawing). Also, before being completely inserted into the lower can <NUM>, the negative electrode tab is bonded to the lower can <NUM>, and the positive electrode tab is bonded to the upper can <NUM>.

Also, the lower can <NUM> has a structure in which a first sidewall <NUM> is formed vertically upward along a circumference of the first flat portion <NUM> having a circular plate shape. When the electrode assembly <NUM> is seated in the lower can <NUM>, a predetermined amount of electrolyte is injected.

The upper can <NUM> has a second sidewall <NUM> formed in a vertical direction along a circumference of the second flat portion <NUM> having a circular plate shape. Here, a diameter of the second flat portion <NUM> is slightly larger than that of the first flat portion <NUM>, and thus, the first sidewall <NUM> may be inserted into the second sidewall <NUM>.

Therefore, when the upper can <NUM> and the lower can <NUM> are coupled to each other, the second flat portion <NUM> may face the first flat portion <NUM>, and the second sidewall portion <NUM> may be coupled in a state of being placed outside the first sidewall portion <NUM>.

Furthermore, as described above, since the lower can <NUM> and the upper can <NUM> are in the state of being connected to the negative electrode tab and the positive electrode tab, respectively, the upper can <NUM> and the lower can <NUM> may be coupled to each other in a state in which a gasket <NUM> is inserted between the first sidewall <NUM> and the second sidewall <NUM>, which corresponds to a point at which the upper can <NUM> and the lower can <NUM> are in contact with each other, so as to prevent short circuit from occurring. The gasket <NUM> has a sufficient length so that an end of the first sidewall <NUM> and the second flat portion <NUM> do not come into contact with each other, and one end of the gasket <NUM> is placed inside the first sidewall <NUM>.

Also, the second sidewall <NUM> has a distal end <NUM> that is bent to surround an edge, at which the first flat portion <NUM> and the first sidewall <NUM> are connected, and is placed below the first flat portion <NUM>. Here, the gasket <NUM> extends to be disposed between the distal end <NUM> and the first flat portion <NUM>. Furthermore, the other end of the gasket <NUM> forms an exposed portion <NUM> protruding to the outside through the distal end <NUM>.

Therefore, in the structure according to this comparative example, since the distal end <NUM> of the second sidewall <NUM> is disposed below the first flat portion <NUM> of the lower can <NUM> to prevent the lower can <NUM> from being separated, the separation of the lower can <NUM> may be strongly prevented compared to the conventional structure in which the upper can <NUM> and the lower can <NUM> are coupled to each other by press-fitting force therebetween.

The second sidewall <NUM> comprises a body portion <NUM> bent from the second flat portion <NUM> and an expansion portion <NUM> connecting the body portion <NUM> to the distal end <NUM> and expanded in diameter rather than the body portion <NUM>. In addition, an inclined portion <NUM> having an inclined cross-sectional shape is formed between the body portion <NUM> and the expansion portion <NUM> so as to be gradually expanded in diameter.

Thus, when the lower can <NUM> is inserted into the upper can <NUM> before the distal end <NUM> is bent, the lower can <NUM> may be easily inserted, and also, since the gasket <NUM> is more pressed at an end-side (an upper side in the drawing) of the first sidewall <NUM>, which is close to the inside of the lower can <NUM>, sealing force may increase.

In addition, in the second side wall <NUM>, the connection point between the expansion portion <NUM> and the distal end <NUM> may be curved at a predetermined curvature to prevent damage from occurring due to sharpness or a device, on which the secondary battery is mounted, from being scratched.

<FIG> is a longitudinal cross-sectional view illustrating a state in which an exposed portion <NUM> increases in thickness to form a flat surface together with a distal end <NUM> according to a second comparative example not forming part of the claimed invention, and <FIG> is a longitudinal cross-sectional view illustrating a state in which the exposed portion <NUM> increases in thickness and length to form a continuous flat surface between a protrusion <NUM> and the distal end <NUM>.

Referring to <FIG> and <FIG>, in this comparative example, the exposed portion <NUM> of the gasket <NUM> protruding from the distal end <NUM> has a thickness D capable of forming a flat surface extending from the distal end <NUM>.

In the comparative examples and in the present invention to be described below, a protrusion <NUM> convexly protruding downward to have the same height as the distal end <NUM> protrudes from the first flat portion <NUM> of the lower can <NUM>. In the comparative examples and in the present invention to be described below, since the secondary battery has a structure that protrudes downward by the distal end <NUM> to a bottom surface of the secondary battery, the protrusion <NUM> is provided as a structure that protrudes to be in contact with a negative terminal of an external device to offset the portion protruding as described above.

Here, in the comparative example, since the exposed portion <NUM> has a thickness capable of forming the flat surface even with the protrusion <NUM>, the protrusion <NUM>, the exposed portion <NUM>, and the distal end <NUM> may form a flat bottom surface in the button-type secondary battery. However, the flat surface may be discontinuously formed as illustrated in <FIG> or may be continuously formed as illustrated in <FIG> according to the length of the exposed portion <NUM>.

Thus, in this comparative example, as the exposed portion <NUM> forms the flat surface, short circuit between the distal end <NUM> and the lower can <NUM> may be more effectively suppressed.

<FIG> is a longitudinal cross-sectional view illustrating a state in which an exposed portion <NUM> is expanded downward from a distal end <NUM> to have a bent shape so as to cover a portion of a bottom surface of the distal end <NUM> according to an embodiment of the present invention. Referring to <FIG>, in the embodiment, the exposed portion <NUM> has a bent structure so that an end 31a of the exposed portion <NUM> is expanded downward from a distal end <NUM> to cover a portion of a bottom surface of the distal portion <NUM>.

Due to the above-described structure, the distal end <NUM> and a lower can <NUM> may be more reliably disconnected to fundamentally prevent short circuit from occurring.

In addition, in the embodiment, since a gasket <NUM> having elasticity and insulating electricity is disposed at the uppermost end, when the secondary battery is stacked and seated, a surface of the secondary battery may be more efficiently prevented from being scratched, and when a plurality of secondary batteries are stacked in a longitudinal direction, electrical connection therebetween may be blocked.

In the present invention having the above configuration, the distal end <NUM> formed on an end of the second sidewall <NUM> of the upper can <NUM> is bent to surround an edge connecting a first flat portion <NUM> to a first sidewall <NUM> and is disposed below the first flat portion <NUM> to increase in coupling force between the upper can <NUM> and the lower can <NUM> compared to the conventional structure.

The exposed portion <NUM> disposed below the first flat portion <NUM> through the distal end <NUM> to protrude to the outside is formed on an end of the gasket <NUM> to more reliably prevent the electric short circuit from occurring between the upper can <NUM> and the lower can <NUM>.

Since the exposed portion <NUM> forms a flat surface together with the distal end <NUM>, the possibility of occurrence of the unintentional short circuit by the metal object may be more reduced.

Since the exposed portion <NUM> is expanded downward from the distal end <NUM> and is bent to cover a portion of the bottom surface of the distal end <NUM>, the possibility of occurrence of the short circuit may be more reduced, and thus, the distal end <NUM> may be protected against a physical impact.

Claim 1:
A button-type secondary battery, in which an electrode assembly (<NUM>) is mounted in a lower can (<NUM>), and an upper can (<NUM>) is coupled to the lower can (<NUM>), wherein the button-type secondary battery has a first end in a height direction, which is an upper end, and a second end in the height direction, which is a lower end, the button-type secondary battery comprising:
the lower can (<NUM>) having a first sidewall (<NUM>) in a vertical direction along a circumference of a first flat portion (<NUM>);
an upper can (<NUM>) having a second sidewall (<NUM>) in a vertical direction along a circumference of a second flat portion (<NUM>), wherein the upper can (<NUM>) is coupled to the lower can (<NUM>) so that the second flat portion (<NUM>) faces the first flat portion (<NUM>), and the second sidewall (<NUM>) is disposed outside the first sidewall (<NUM>);
an electrode assembly (<NUM>) in which a negative electrode, a separator, and a positive electrode are wound in a state of being stacked and which is mounted in an inner space between the lower can (<NUM>) and the upper can (<NUM>) so that the negative electrode is connected to the lower can (<NUM>), and the positive electrode is connected to the upper can (<NUM>); and
a gasket (<NUM>) disposed between the second sidewall (<NUM>) and the first sidewall (<NUM>) to prevent the upper can (<NUM>) and the lower can (<NUM>) from being in contact with each other,
wherein the second sidewall (<NUM>) comprises a distal end (<NUM>) that is bent to surround an edge configured to connect the first flat portion (<NUM>) to the first sidewall (<NUM>) and is disposed below the first flat portion (<NUM>), and
the gasket (<NUM>) extends to be disposed between the distal end (<NUM>) and the first flat portion (<NUM>),
wherein an exposed portion (<NUM>) protruding to the outside through the distal end (<NUM>) is formed on an end of the gasket (<NUM>), and
the exposed portion (<NUM>) is disposed below the first flat portion (<NUM>), and
the exposed portion (<NUM>) is expanded downward from the distal end (<NUM>) and is bent to cover a portion of a bottom surface of the distal end (<NUM>).