Patent Description:
Rechargeable batteries are classified into coin type batteries, cylindrical type batteries, prismatic type batteries, and pouch type batteries according to a shape of a battery case. The secondary battery accommodates an electrode assembly and an electrolyte. In such a secondary battery, an electrode assembly mounted in a battery case is a chargeable and dischargeable power generating device having a structure in which an electrode and a separator are stacked.

The electrode assembly may be approximately classified into a jelly roll type electrode assembly in which a separator is interposed between a positive electrode and a negative electrode, each of which is provided as the form of a sheet coated with an active material, and then, the positive electrode, the separator, and the negative electrode are wound, a stacked type electrode assembly in which a plurality of positive and negative electrodes with a separator therebetween are sequentially stacked, and a stack/folding type electrode assembly in which stacked type unit cells are wound together with a separation film having a long length.

A cylindrical battery is constituted by a jelly rolltype electrode assembly and a can containing the electrode assembly.

The typical cylindrical battery has a risk of being ignited under various conditions (overcharge, a high temperature, and an external impact).

In addition, when the cylindrical battery is ignited, there is a problem that there is no device capable of extinguishing the fire by itself or preventing the fire from being spread.

[Prior Art Document] (Patent Document) <CIT>.

<CIT> discloses a secondary battery comprising an electrode assembly in which electrodes and separators are alternately stacked to be wound; a can configured to accommodate the electrode assembly therein, having an opening in an upper end thereof, and provided with a beading part that is bent inward to form a recessed groove; and a cap assembly seated on the beading part to cover the opening of the can.

<CIT> discloses a battery comprising: a battery can including top opening bounded by a peripheral lip and defining an electrode receiving cavity; an electrode assembly including at least one anode, at least one cathode, and at least one separator disposed between the anode and the cathode, the electrode assembly being disposed in the electrode receiving cavity, an electrolyte disposed in the electrode receiving cavity, a safety valve disposed in the electrode receiving cavity adjacent the top opening, a battery cover including a raised central portion disposed in the top opening and sealably closing off the top opening and defining a first venting chamber between the safety valve and the raised central portion, a secondary cover member disposed on an outside surface of the battery cover extending between the raised central portion and the peripheral lip and defining a second venting chamber under the secondary cover member, said raised central portion including an opening connecting the first venting chamber and the second venting chamber.

One aspect of the present invention is to provide a secondary battery capable of be extinguished through a fire extinguishing agent when the battery is ignited.

A secondary battery according to an embodiment of the present invention comprises an electrode assembly in which electrodes and separators are alternately stacked to be wound, a can configured to accommodate the electrode assembly therein, having an opening in an upper end thereof, and provided with a beading part that is bent inward to form a recessed groove, a cap assembly seated on the beading part to cover the opening of the can, an extinguishing agent accommodated in the recessed groove to extinguish ignition when the secondary battery is ignited, and a sealing part configured to seal the recessed groove.

A battery pack according to an embodiment of the present invention may comprise the secondary battery according to an embodiment of the present invention.

According to the present invention, the extinguishing agent may be disposed in the beading part of the can, and a portion of the beading part in which the extinguishing agent is accommodated may be sealed by the sealing part to extinguish the fire through the extinguishing agent when the battery is ignited.

In addition, the extinguishing agent may be provided as the compressed extinguishing agent, which is ejected when the secondary battery is ignited, and thus may easily extinguish the fire in the surrounding space or prevent the fire from being spread.

The objectives, specific advantages, and novel features of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings. It should be noted that the reference numerals are added to the components of the drawings in the present specification with the same numerals as possible, even if they are illustrated in other drawings. Also, the present invention may be embodied in different forms and should not be construed as limited to the embodiments set forth herein. In the following description of the present invention, the detailed descriptions of related arts which may unnecessarily obscure the gist of the present invention will be omitted.

<FIG> is a cross-sectional view of a secondary battery according to an embodiment of the present invention, <FIG> is a cross-sectional view illustrating a state before an extinguishing agent is ejected in the secondary battery according to an embodiment of the present invention, and <FIG> is a cross-sectional view illustrating a state in which the extinguishing agent is being ejected in the secondary battery according to an embodiment of the present invention.

Referring to <FIG>, a secondary battery <NUM> according to an embodiment of the present invention comprises an electrode assembly <NUM>, a can <NUM> accommodating the electrode assembly <NUM>, a cap assembly <NUM> covering an opening <NUM> of the can <NUM>, an extinguishing agent <NUM> extinguishing fire when ignition occurs, and a sealing part <NUM> sealing a recessed groove <NUM>.

In more detail, the electrode assembly <NUM> may be a chargeable and dischargeable power generation element and have a structure in which an electrode <NUM> and a separator <NUM> are alternately stacked. Here, the electrode assembly <NUM> may be formed in a shape in which the electrodes <NUM> and the separator <NUM> are alternately stacked to be wound. Here, the electrode assembly <NUM> may be provided in a shape that is wound in a circular or oval shape.

The electrodes <NUM> may comprise a positive electrode <NUM> and a negative electrode <NUM>. Also, the separator <NUM> separates and electrically insulates the positive electrode <NUM> and the negative electrode <NUM> from each other. Here, in the electrode assembly <NUM>, the positive electrode <NUM>, the separator <NUM>, and the negative electrode <NUM> may be alternately combined to be wound.

The positive electrode <NUM> may comprise a positive electrode collector and a positive electrode active material provided on one surface of the positive electrode collector. Here, the positive electrode <NUM> may comprise a positive electrode non-coating portion that is an area on which the positive electrode active material is not stacked.

For example, the positive electrode collector may be provided as foil made of an aluminum material.

The positive electrode active material may comprise lithium manganese oxide, lithium cobalt oxide, lithium nickel oxide, lithium iron phosphate, or a compound or mixture containing at least one of the above-described materials.

The negative electrode <NUM> may comprise a negative electrode collector and a negative electrode active material stacked on one surface of the negative electrode collector. Here, the negative electrode <NUM> may comprise a negative electrode non-coating portion that is an area on which the negative electrode active material is not stacked.

The negative electrode collector may be made of, for example, a copper foil made of a copper (Cu) material.

The negative electrode active material may comprise synthetic graphite, lithium a metal, a lithium alloy, carbon, petroleum coke, activated carbon, graphite, a silicon compound, a tin compound, a titanium compound, or an alloy thereof. Here, the negative electrode active material may further comprise, for example, non-graphite-based SiO (silica) or SiC (silicon carbide).

The separator <NUM> may be made of an insulating material to insulate the positive electrode <NUM> and the negative electrode <NUM> from each other.

Also, the separator <NUM> may be, for example, a multilayered film produced by microporous polyethylene, polypropylene, or a combination thereof or a polymer film for solid polymer electrolytes or gel-type polymer electrolytes such as polyvinylidene fluoride, polyethylene oxide, polyacrylonitrile, or polyvinylidene fluoride hexafluoropropylene copolymers.

The can <NUM> accommodates the electrode assembly <NUM> therein, and an opening <NUM> may be formed in an upper end thereof. Here, the can <NUM> may be formed in a cylindrical shape in which an accommodation part <NUM>, in which the electrode assembly <NUM> is accommodated, is formed.

In addition, the can <NUM> may comprise a metal material. Here, the can <NUM> may comprise, for example, an aluminum or copper material.

Furthermore, a beading part <NUM> formed to be bent inward so that the cap assembly <NUM> is mounted on the can <NUM> to form a recessed groove <NUM> in the outside thereof may be formed.

In addition, a crimping part <NUM> that wraps and fixes an edge of the cap assembly <NUM> may be formed on an upper portion of the beading part <NUM> of the can <NUM>. Here, the crimping part <NUM> may comprise an outer circumferential portion formed in a longitudinal direction of the can <NUM> and an upper end perpendicular to the longitudinal direction of the can <NUM>.

The cap assembly <NUM> may be seated on the beading part <NUM> to cover the opening <NUM> of the can <NUM>.

In addition, the cap assembly <NUM> may comprise a top cap <NUM> disposed at an upper portion of the secondary battery <NUM>, a safety vent <NUM> disposed below the top cap <NUM>, a current blocking member <NUM> disposed below the safety vent <NUM>, and a gasket <NUM> wrapping an outer circumferential surface of each of the top cap <NUM> and the safety vent <NUM>. Here, the gasket <NUM> may seal and insulate a gap between the cap assembly <NUM> and the can <NUM>.

The top cap <NUM> may have an outlet and be disposed at the upper outermost portion of the secondary battery <NUM>.

In addition, the top cap <NUM> may comprise a protruding terminal on an upper end thereof and a positive electrode terminal electrically connected to the electrode assembly <NUM> accommodated in the secondary battery <NUM>.

The safety vent <NUM> may be disposed inside the secondary battery <NUM> rather than the top cap <NUM>. Thus, when an internal pressure of the secondary battery <NUM> increases, the safety vent <NUM> may be reversed in shape toward the top cap <NUM> so as to be ruptured.

The current blocking member <NUM> may be disposed below the safety vent <NUM> and comprise a central portion connected to the safety vent <NUM> and an outer portion that is not connected to the safety vent <NUM>.

In the current blocking member <NUM>, an upper end of the central portion thereof may be in contact with a lower end of a central portion <NUM> of the safety vent <NUM>, and when the internal pressure increases, the central portion <NUM> of the safety vent <NUM> may move to the top cap <NUM>, and the contact between the safety vent <NUM> and the current blocking member <NUM> may be released to release the electrical connection.

The secondary battery <NUM> according to an embodiment of the present invention may comprise an electrode lead <NUM> attached to the electrode <NUM> and electrically connected to the electrode <NUM>.

The electrode lead <NUM> may comprise a positive electrode lead <NUM> connected to the positive electrode <NUM> and a negative electrode lead connected to the negative electrode <NUM>.

Referring to <FIG>, the positive electrode lead <NUM> may be formed in a direction, in which the cap assembly <NUM> is disposed, i.e., an upward direction and be electrically connected to the current blocking member <NUM>, and the negative electrode lead may be electrically connected to a lower portion of the can <NUM> in a downward direction.

The extinguishing agent <NUM> may be accommodated in the recessed groove <NUM> of the can <NUM> to extinguish fire when the secondary battery <NUM> is ignited.

In addition, the extinguishing agent <NUM> may be provided as the compressed extinguishing agent containing a compressed gas and thus be ejected when the secondary battery is ignited to extinguish fire.

Furthermore, the extinguishing agent <NUM> may be made of at least any one or more of a Halon gas, nitrogen, and carbon dioxide.

The sealing part <NUM> may seal the recessed groove <NUM>. Thus, the recessed groove <NUM> of the can <NUM> in which the extinguishing agent <NUM> is accommodated may be sealed through the sealing part <NUM>.

The sealing part <NUM> may comprise a rubber material. Thus, the extinguishing agent may be easily injected into the recessed groove <NUM>. That is, for example, an injection syringe may pass through the sealing part <NUM> to inject the extinguishing agent <NUM> into the recessed groove <NUM>, and then, heat may be applied to a portion through which the syringe passes to seal the portion, or the portion may be contracted by its own elastic force so as to be sealed.

The sealing part <NUM> may be made of adhesive rubber and thus be attached to the can <NUM> to cover the recessed groove <NUM>. Here, after additionally adhering to the can <NUM> with the adhesive rubber, the heat and pressure may be applied so that the extinguishing agent is fixed to an outer surface of the can <NUM> through thermal fusion.

In the secondary battery <NUM>, which is configured as the described above, according to an embodiment of the present invention, the extinguishing agent <NUM> may be disposed on the beading part <NUM> of the can <NUM>, and a portion of the beading part <NUM>, in which the extinguishing agent <NUM> is accommodated, may be sealed through the sealing part <NUM> to extinguish fire or prevent the fire from being spread through the extinguishing agent <NUM> when the battery is ignited. Particularly, the fire extinguishing agent <NUM> may be provided as the compressed extinguishing agent <NUM> containing the compressed gas and be ejected when the secondary battery <NUM> is ignited to extinguish fire in a surrounding space or prevent fire from being spread. Here, when the battery is ignited, the extinguishing agent <NUM> containing the compressed gas may be heated to release the sealing of the sealing part <NUM> and then be ejected, or the extinguishing agent <NUM> may be ejected to the portion of the sealing part <NUM>, which is melted by heat of the ignition.

Hereinafter, a secondary battery according to another embodiment of the present invention will be described.

<FIG> is a cross-sectional view of a secondary battery according to another embodiment of the present invention, <FIG> is a perspective view of a can in the secondary battery according to another embodiment of the present invention, <FIG> is a cross-sectional view illustrating a state before an extinguishing agent is ejected in the secondary battery according to another embodiment of the present invention, and <FIG> is a cross-sectional view illustrating a state in which the extinguishing agent is being ejected in the secondary battery according to another embodiment of the present invention.

Referring to <FIG>, a secondary battery <NUM> according to another embodiment of the present invention comprises an electrode assembly <NUM>, a can <NUM> accommodating the electrode assembly <NUM>, a cap assembly <NUM> covering an opening <NUM> of the can <NUM>, an extinguishing agent <NUM> extinguishing fire when ignition occurs, and a sealing part <NUM> sealing a recessed groove <NUM>.

The secondary battery <NUM> according to another embodiment of the present invention is different from the secondary battery according to the foregoing embodiment of the present invention in that notches <NUM> and <NUM> are further formed on the beading part <NUM> of the can <NUM>. Thus, in another embodiment of the secondary battery <NUM>, contents duplicated with the secondary battery according to the forgoing embodiment of the present invention will be omitted or briefly described, and also, differences therebetween will be mainly described.

In more detail, the can <NUM> may accommodate the electrode assembly <NUM> therein, and an opening <NUM> may be formed in an upper end thereof. Here, the can <NUM> may be formed in a cylindrical shape in which an accommodation part <NUM>, in which the electrode assembly <NUM> is accommodated, is formed.

Notches <NUM> and <NUM> may be formed in the beading part <NUM>. Thus, when the secondary battery <NUM> is ignited, the notches <NUM> and <NUM> of the beading part <NUM> may be ruptured, and thus, the extinguishing agent <NUM> accommodated in the recessed groove <NUM> may be ejected to easily extinguish fire in the surrounding space.

The notches <NUM> and <NUM> may be formed in at least one of an outer surface 230b and an inner surface 230a of the beading part <NUM>. Here, each of the notches <NUM> and <NUM> may be formed in a triangular groove shape.

The can <NUM> may be formed in a cylindrical shape, and the notches <NUM> and <NUM> may be formed along an outer circumferential surface or an inner circumferential surface of the beading part <NUM>. Here, the notches <NUM> and <NUM> may be discontinuously or continuously formed along the outer circumferential surface or the inner circumferential surface of the beading part <NUM>.

Also, the notches <NUM> and <NUM> may be formed, for example, in one or more lines on the beading part <NUM>.

Furthermore, the notches <NUM> and <NUM> may be melted by flame generated when the secondary battery <NUM> is ignited or may be ruptured by a high internal pressure generation due to the ignition, or the fire extinguishing agent <NUM> containing compressed gas may be heated by the heat of the ignition and thus be ruptured by the fire extinguishing agent <NUM> such as any one or more factors. Thus, an ejection passage for the extinguishing agent <NUM> between the accommodation part <NUM> of the can <NUM> and the recessed groove <NUM>, in which the extinguishing agent <NUM> is accommodated may be formed in portions of the melted or ruptured notches <NUM> and <NUM>. Thus, when the secondary battery <NUM> is internally ignited, the notches <NUM> and <NUM> may be melted or ruptured so that the extinguishing agent <NUM> is ejected into the secondary battery <NUM> to extinguish the internal ignition.

Here, the notches <NUM> and <NUM> may be ruptured, for example, at the same or higher pressure as a rupture pressure of the safety vent <NUM>. The notches <NUM> and <NUM> may be ruptured, for another example, at a pressure lower than the rupture pressure of the safety vent <NUM>.

A crimping part <NUM> that wraps and fixes an edge of the cap assembly <NUM> may be formed on an upper portion of the beading part <NUM> of the can <NUM>.

The extinguishing agent <NUM> may be accommodated in the recessed groove <NUM> to extinguish fire when the secondary battery <NUM> is ignited.

In addition, the extinguishing agent <NUM> may be provided as the compressed extinguishing agent containing a compressed gas and thus be ejected when the secondary battery <NUM> is ignited to extinguish fire.

The sealing part <NUM> may seal the recessed groove <NUM>. Thus, the recessed groove <NUM> in which the extinguishing agent <NUM> is accommodated may be sealed through the sealing part <NUM>.

In addition, the sealing part <NUM> may comprise a rubber material.

Furthermore, the sealing part <NUM> may be made of adhesive rubber and thus be attached to the can <NUM> to cover the recessed groove <NUM>.

Also, when the battery is ignited, the extinguishing agent <NUM> containing the compressed gas may be heated to release the sealing of the sealing part <NUM> and then be ejected, or the extinguishing agent <NUM> may be ejected to the portion of the sealing part <NUM>, which is melted by heat of the ignition.

Here, when the secondary battery <NUM> provided with the extinguishing agent <NUM> and the sealing part <NUM> are ignited, the ignition may be extinguished, and when fire occurs in the surrounding or adjacent batteries of the secondary battery <NUM>, fire in the surrounding space may be easily extinguished.

Claim 1:
A secondary battery (<NUM>, <NUM>) comprising:
an electrode assembly (<NUM>) in which electrodes (<NUM>) and separators (<NUM>) are alternately stacked to be wound;
a can (<NUM>, <NUM>) configured to accommodate the electrode assembly (<NUM>) therein, having an opening (<NUM>, <NUM>) in an upper end thereof, and provided with a beading part (<NUM>, <NUM>) that is bent inward to form a recessed groove (<NUM>, <NUM>);
a cap assembly (<NUM>) seated on the beading part (<NUM>) to cover the opening (<NUM>, <NUM>) of the can (<NUM>, <NUM>); characterized by
an extinguishing agent (<NUM>) accommodated in the recessed groove (<NUM>, <NUM>) to extinguish ignition when the secondary battery (<NUM>, <NUM>) is ignited; and
a sealing part (<NUM>) configured to seal the recessed groove (<NUM>, <NUM>).