Rechargeable battery

A rechargeable battery includes an electrode assembly for charging and discharging, a case in which the electrode assembly is stored; an electrode terminal electrically connected to the electrode assembly; a current collecting portion that electrically connects the electrode assembly with the electrode terminal, the current collecting portion including a fuse portion; and an insulation portion that insulates the fuse portion, the insulation portion being slidable in response to pressure applied in the fuse portion.

CROSS-REFERENCE TO RELATED APPLICATION

Korean Patent Application No. 10-2013-0115489, filed on Sep. 27, 2013, in the Korean Intellectual Property Office, and entitled: “Rechargeable Battery,” is incorporated by reference herein in its entirety.

BACKGROUND

Embodiments relate to a rechargeable battery.

2. Description of the Related Art

A rechargeable battery differs from a primary battery in that it can be repeatedly charged and discharged, while the latter is incapable of being recharged.

A low-capacity rechargeable battery is used in small portable electronic devices such as mobile phones, notebook computers, and camcorders, while a high-capacity rechargeable battery is widely used as a power source for driving a motor of a hybrid vehicle and the like.

Recently, a high power rechargeable battery using a non-aqueous electrolyte and having high energy density has been developed. The high power rechargeable battery is formed by coupling a plurality of rechargeable batteries in series to be used as a power source for driving a motor of a device requiring a large amount of electric power, for example, an electric vehicle and the like. A rechargeable battery may be formed in a cylindrical shape, a prismatic shape, a pouch shape, or the like.

SUMMARY

Embodiments are directed to a rechargeable battery including an electrode assembly for charging and discharging, a case in which the electrode assembly is stored, an electrode terminal electrically connected to the electrode assembly, a current collecting portion that electrically connects the electrode assembly with the electrode terminal, the current collecting portion including a fuse portion, and an insulation portion that insulates the fuse portion, the insulation portion being slidable in response to pressure applied in the fuse portion.

The current collecting portion may include a current collecting plate connected to the electrode assembly and a current collecting lead member connecting the electrode terminal with the current collecting plate.

The current collecting lead member may include a terminal lead portion connected to the electrode terminal and a current collecting lead portion that extends from the terminal lead portion and is connected to the current collecting plate.

The fuse portion may be in the terminal lead portion.

The fuse portion may be in the current collecting lead portion.

The lead member may include a sliding hole. The fuse portion may bridge the sliding hole at one lateral side of the lead member.

The fuse portion may include coupling portions at opposite sides of the sliding hole on one lateral side of the current collecting lead portion, the coupling portions being electrically connected to the current collecting lead portion, and a fuse sheet connecting a space between the coupling portions.

The coupling portion may be arc-welded to the lead member.

The insulation portion of the fuse portion may include a first insulation portion that covers one lateral side of the fuse sheet, and a second insulation portion that covers another lateral side of the fuse sheet, the second insulation portion being integrally formed with the first insulation portion, and the insulation portion including a insertion space for the fuse sheet between the first and second insulation portions.

The first and second insulation portions may contact respective lateral sides of the fuse sheet.

The first and second insulation portions may be bent to protrude toward the electrode assembly.

The insulation portion may be slidable in response to a gas pressure created by melting of the fuse portion when a current exceeding a predetermined level flows in the fuse portion, such that the insulation portion increases a separation between the respective of separated parts of the fuse portion.

Slidability between the insulation portion and the separated parts of the fuse may be in a direction in which the separated parts separate from each other.

Slidability of the insulation portion may include slidable engagement between the insulation portion and a sliding hole in the current collecting portion.

DETAILED DESCRIPTION

FIG. 1illustrates a view schematically depicting a rechargeable battery according to an exemplary embodiment, andFIG. 2illustrates a cross-sectional view of the rechargeable battery inFIG. 1, taken along the line II-II.

As shown inFIG. 1andFIG. 2, the rechargeable battery100according to this exemplary embodiment may include an electrode assembly10for charging and discharging, a case20in which the electrode assembly10is stored, an electrode terminal30electrically connected to the electrode assembly10, current collecting portions40and50which electrically connect the electrode assembly10and the electrode terminal30and include a fuse portion60, and an insulation portion65to insulate the fuse portion60.

Herein, the rechargeable battery100is exemplarily illustrated as a prism-shaped lithium ion rechargeable battery.

The electrode assembly10may include a first electrode plate, a separator13, and a second electrode plate. The electrode assembly10may be formed in a jelly-roll shape by spirally winding the first electrode plate, the separator13, and the second electrode plate.

In other implementations, the first electrode plate, the separator13, and the second electrode plate may be formed to be multi-layered while being alternately arranged. In this instance, the separator13may be interposed between the first and second electrode plates.

In some implementations, the first electrode plate may be a positive electrode plate11and the second electrode may be a negative electrode plate12.

The case20, which stores the electrode assembly10, may be formed as a prismatic can shape with one opened side. The electrode assembly10, along with an electrolyte solution, may be placed in the case20through the opened side.

A cap plate21may be coupled to the opened side of the case20, and may close and seal the case20into which the electrode assembly10is placed. The cap plate21may cover the case20while allowing the electrode terminal30to protrude outwards.

The interfacing part between the case20and the cap plate21may be laser welded to close and seal the case20which stores the electrode assembly10along with the electrolyte solution.

The cap plate21may be formed in a shape of a thin plate. The cap plate21may be formed with an electrolyte injection opening22a. A sealing cap22may be fitted into the electrolyte injection opening22aafter the electrolyte solution is injected. A vent member23may be provided with a groove, in the cap plate21, to be ruptured at a predetermined internal pressure.

Terminal holes24aand25amay respectively penetrate the cap plate21. The terminal holes24aand25amay respectively be a positive electrode terminal hole24aand a negative electrode terminal hole25a. A positive electrode terminal31may protrude outwards by penetrating the positive electrode terminal hole24a. A negative electrode terminal33may protrude outwards by penetrating the negative electrode terminal hole25a.

Gaskets26and27may be provided to be respectively interposed between the cap plate21and the electrode terminals31and33. The upper gasket26may be provided to be inserted above the cap plate21.

The positive and negative electrode terminals31and33may be respectively formed with screw threads, and may be respectively fastened with nuts29. The nuts29may respectively support the electrode terminals31and33from above. A washer28may be provided above the upper gaskets26to buffer a fastening force.

In other implementations, the electrode terminals31and33may be respectively formed in a rivet shape. In this instance, parts of the electrode terminals31and33may protrude outwards by respectively penetrating the terminal holes24aand25a. Protruded parts of the electrode terminals31and33may be respectively pressed to have a wide flat shape while the upper gaskets26are respectively inserted between the terminal holes24aand25aand the protruded parts of the electrode terminals31and33, and thereby are respectively fixed to the cap plate21.

The current collecting portions40and50may respectively include current collecting plates41and51that are connected to the first and second electrode terminals, and lead members43and53that connect the electrode terminal30and the current collecting plates41and51.

The lead members43and53may respectively include terminal lead portions43aand53athat are respectively connected to the electrode terminal30, and current collecting lead portions43band53bthat respectively extend from the terminal lead portions43aand53aand are respectively connected to the current collecting plates41and51.

The positive electrode current collecting portion40may include the positive electrode current collecting plate41and the positive electrode lead member43. The negative electrode current collecting portion50may include the negative electrode current collecting plate51and the negative electrode lead member53. The current collecting plates41and51may respectively be the positive electrode current collecting plate41and the negative electrode current collecting plate51. The lead members43and53may respectively be the positive electrode lead member43and the negative electrode lead member53.

The current collecting portions40and50may be integrally formed. The positive electrode current collecting portion40may be integrally formed with the positive electrode current collecting plate41and the positive electrode lead member43. The negative electrode current collecting portion50may be integrally formed with the negative electrode current collecting plate51and the negative electrode lead member53.

The positive electrode current collecting plate41may be connected by welding to a positive electrode uncoated region11aof the electrode assembly10. The positive electrode current collecting plate41may be electrically connected to the positive electrode terminal31through the positive electrode lead member43. Accordingly, the positive electrode terminal31may be connected by welding to the positive electrode plate11of the electrode assembly10through the positive electrode lead member43and the positive electrode current collecting plate41.

The negative electrode current collecting plate51may be connected by welding to a negative electrode uncoated region12aof the electrode assembly10. The negative electrode current collecting plate51may be electrically connected to the negative electrode terminal33through the negative electrode lead member53. Accordingly, the negative electrode terminal31may be connected to the negative electrode plate12of the electrode assembly10through the negative electrode lead member53and the negative electrode current collecting plate51.

Insulation members35for insulation may be respectively provided between the lead members43and53and the cap plate21.

The lead members43and53respectively include the terminal lead portions43aand53aand the current collecting lead portions43band53b. The terminal lead portions43aand53amay be respectively coupled with the electrode terminals31and33to be electrically connected thereto.

The current collecting lead portions43band53bmay be respectively combined with the current collecting plates41and51to be electrically connected thereto.

The rechargeable battery100according to the present exemplary embodiment may be a lithium-ion rechargeable battery. In other implementations, the rechargeable battery100may be any one of various other types of batteries, such as a nickel-cadmium rechargeable battery, a nickel-hydrogen rechargeable battery, or a lithium battery.

The rechargeable battery100according to the present exemplary embodiment is exemplarily illustrated as a prism-shaped rechargeable battery. In other implementations, the rechargeable battery100may be any one of various other types of batteries, such as a cylindrical battery or a pouch-shaped battery.

The positive electrode plate11, the positive electrode current collecting plate41, and the positive electrode lead member43may be electrically connected to each other, and may be formed: of a same material, for example, a material including aluminum.

The negative electrode plate12, the negative electrode current collecting plate51, and the negative electrode lead member53may be electrically connected to each other, and may be formed of a same material, for example, a material including copper.

The fuse portion60may be formed in the current collecting portions40and50. The fuse portion60may be formed in at least one of the positive electrode current collecting portion40and the negative electrode current collecting portion50.

The fuse portion60according to the first exemplary embodiment may be formed in the positive electrode current collecting portion40. In this instance, the fuse portion60may be formed of aluminum, which has a lower melting point than copper. Accordingly, the fuse portion60may have improved performance.

Herein, the fuse portion60may be provided in the lead member43in order to have a simpler structure. For example, the fuse portion60may be provided in the current collecting lead portion43bto provide sufficient room to install the insulation portion65.

FIG. 3illustrates an exploded view schematically depicting a state in which the electrode assembly is separated from the current collecting lead portion in order to better show the location of the fuse portion, andFIG. 4illustrates a cross-sectional view schematically depicting the fuse portion provided in the current collecting lead portion.

As shown inFIG. 3andFIG. 4, the fuse portion60may be provided to bridge a sliding hole43cformed in the current collecting lead portion43b. The fuse portion60may include coupling portions61provided respectively at opposite sides of the sliding hole43con one lateral side of the current collecting lead portion43b, and a fuse sheet63that connects a space between the coupling portions61.

The coupling portions61may be coupled by arc welding to respective surfaces of the one lateral side of current collecting lead portion43b. The one lateral side of the current collecting lead portion43bmay be a side that faces towards the electrode assembly10.

Two coupling portions61may be provided at respective opposite sides of the sliding hole43cformed in the current collecting lead portion43bsuch that the two coupling portions61are electrically connected to each other through the fuse sheet63.

One end of the fuse sheet63may be coupled to one coupling portion61that is attached to one side of the sliding hole43c, and the other end of the fuse sheet63may be coupled to another coupling portion61that is attached to the other side of the sliding hole43c. The fuse sheet63may be coupled to the coupling portions61by ultrasonic welding.

In the event of an overcurrent, a part of the fuse sheet63in its length direction may be melted and then separated to protect the rechargeable battery100from the overcurrent, thereby improving the stability of the rechargeable battery100.

The insulation portion65may be provided at the outer side of the fuse sheet to extinguish an arc generated between the separated parts of the fuse sheet63. The process of extinguishing the arc generated at the fuse sheet63, using the insulation portion65, will be described in more detail below when referring to the insulation portion65.

As shown inFIG. 4, the insulation portion65may include a first insulation portion65ato cover one lateral side of the fuse sheet63and a second insulation portion65bto cover the other lateral side of the fuse sheet63. A space in which the fuse sheet63is inserted may be provided between the first and second insulation portions65aand65b. The first and second insulation portions65aand65bmay be provided to contact the fuse sheet63at respective lateral sides thereof.

A part of the fuse sheet65having the structure described above may be melted when a current exceeding the predetermined level flows in the fuse sheet63. A space may be thereby created between the respective ends of the separated parts of the fuse sheet.

FIG. 5illustrates a cross-sectional view schematically depicting a state in which the part of the fuse sheet is melted and then separated inside the insulation portion as an overcurrent flows through the fuse sheet. As shown inFIG. 5, when the overcurrent flows, the part of the fuse sheet63may be melted and then separated to form a gas space65cbetween the first and second insulation portions65. The gas space65cmay be filled with gas formed during melting of the part of the fuse sheet63.

At the time of melting, the respective ends of the separated parts of the fuse sheet63inside the insulation portion65may be disposed close to each other, thereby generating an arc64. As shown inFIG. 6, the arc64generated by the fuse sheet63may be extinguished, as the respective ends of the separated parts of the fuse sheet63are further separated from each other by sliding of the insulation portion65.

FIG. 6illustrates a cross-sectional view schematically depicting a state in which respective ends of the separated parts of the fuse sheet are separated by sliding of the insulation portion, thereby extinguishing the arc.

As shown inFIG. 6, when a predetermined time passes after the gas is created by melting the part of the fuse sheet63inside the insulation portion65, the insulation portion65may be moved along the sliding hole43ctoward one side of the current collecting lead portion43b. When the part of the fuse sheet63is melted in the insulation portion65, the gas space65cis created between the first and second insulation portions65aand65bto be filled with the gas. The gas space65may be filled by gas having a high pressure due to continuous melting of the fuse sheet63.

The gas filling the gas space65cmay be released out of the insulation portion65at a predetermined pressure when a predetermined time passes.

As the insulation portion65is moved along the sliding hole43cto one side by the repulsive force of the emission of the gas, the respective ends of the separated parts of the fuse sheet63may be further separated from each other, as shown inFIG. 6.

The arc generated at the respective ends of the separated parts of the fuse sheet63may be extinguished as the respective ends of the separated parts of the fuse sheet63are further separated. Accordingly, the external short-circuit characteristic of the rechargeable battery may be improved.

The insulation portion65according to the present embodiment may be made of a fluorine resin material having superior flame resistance, wear resistance, and chemical resistance.

A part of the insulation portion65may be bent to protrude toward its moving direction. The insulation portion60may be partially bent to provide a passage of the gas through which the gas filled in the gas space65cmay be released in a direction opposite to its moving direction.

FIG. 7illustrates a schematic perspective view of a fuse portion provided in a rechargeable battery according to another exemplary embodiment.

The same reference numbers ofFIG. 1toFIG. 6refer to the same members inFIG. 7having the same functions. Hereinafter, a detailed description of features having the same reference numbers will not be repeated.

As shown inFIG. 7, a fuse portion160of the rechargeable battery according to this exemplary embodiment may be provided in the terminal lead portions143aor53a.

For example, the fuse portion160may be located at a part of the terminal lead portion143aof a current collecting portion140that is electrically connected to an electrode assembly10.

The fuse portion160according to the present exemplary embodiment may have the same structure as the fuse portion according to the exemplary embodiment illustrated inFIGS. 1 to 6, except for being provided at a different position, for example, in a part of the terminal lead portions143aor53a.

By way of summation and review, a rechargeable battery may include an electrode assembly having a separator interposed between positive and negative electrodes; a case having a space in which the electrode assembly is stored; a cap plate which seals the case and is provided with a terminal hole to be inserted by a terminal; and the terminal to be electrically connected through the electrode assembly and a current collecting portion and to protrude out of the case while being inserted in the terminal hole.

In a rechargeable battery, a fuse may cut off an overcurrent in the current collecting portion when an overcurrent occurs. When a part of the fuse is melted due to the overcurrent, it may be difficult to effectively cut off the overcurrent due to arc generation when ends of the separated parts of the fuse are disposed close to each other.

Embodiments provide a rechargeable battery having an improved short circuit characteristic. Embodiments provide a rechargeable battery in which arc generation is prevented at the separated parts of the fuse even if a part of the fuse is melted and then separated. In case a part of the fuse sheet is melted and then separated due to an overcurrent, the short-circuit characteristic of the rechargeable battery may be improved by preventing arc generation at the gap of the separated parts of the fuse sheet.