Rechargeable battery

A rechargeable battery including an electrode assembly including a positive electrode and a negative electrode; a case containing the electrode assembly; a terminal electrically connected to the electrode assembly; a current collecting member fixed to the electrode assembly; and a connection member electrically connecting the electrode assembly and the terminal, and the connection member includes a first end fixed to one of the current collecting member or the terminal, a second end spaced apart from the first end and contacting the other of the current collecting member or the terminal, and a fuse portion between the first end and the second end, the fuse portion having a smaller cross-sectional area than a surrounding portion of the connection member.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and the benefit of Korean Patent Application No. 10-2011-01 07016 filed on Oct. 19, 2011 in the Korean Intellectual Property Office, the entire content of which is incorporated herein by reference.

BACKGROUND

Aspects of embodiments of the present invention relate to a rechargeable battery, and more particularly, to a rechargeable battery in which a structure of a safety apparatus that is capable of decreasing a risk when an overcurrent occurs is improved.

2. Description of the Related Art

A rechargeable battery is a battery that can be charged and discharged, unlike a primary battery that is incapable of being charged. A rechargeable battery having low capacity is commonly used in a portable small electronic device, such as a mobile phone, a laptop computer, or a camcorder, and a battery having large capacity is widely used as a power source for driving a motor in an electric vehicle, a hybrid vehicle, or the like.

Recently, a high power rechargeable battery that uses a non-aqueous electrolyte having high energy density has been developed, and the high power rechargeable battery is constituted by a large-capacity rechargeable battery in which a plurality of rechargeable batteries are coupled in series in order to be used for driving devices requiring large power, such as motors for electric vehicles or hybrid vehicles, for example.

In addition, a large-capacity rechargeable battery generally includes a plurality of rechargeable batteries that are coupled in series, and the rechargeable battery may be formed in cylindrical and/or angular shapes.

If an overcurrent flows through the rechargeable battery having a case that is made of material such as metal, the temperature of the rechargeable battery may increase and increase a risk of ignition. In addition, if the internal pressure of the rechargeable battery increases because of decomposition of the electrolyte solution in the rechargeable battery due to the overcurrent, there is a risk of explosion of the rechargeable battery.

SUMMARY

According to an aspect of embodiments of the present invention, a rechargeable battery has improved safety. Further, according to an aspect of embodiments of the present invention, in a rechargeable battery, a structure of a safety apparatus that is capable of decreasing a risk when an overcurrent occurs is improved. As such, a rechargeable battery according to embodiments of the present invention is particularly suited for application in an electric vehicle or a hybrid electric vehicle.

According to an exemplary embodiment of the present invention, a rechargeable battery includes: an electrode assembly including a positive electrode and a negative electrode; a case containing the electrode assembly; a terminal electrically connected to the electrode assembly; a current collecting member fixed to the electrode assembly; and a connection member electrically connecting the electrode assembly and the terminal, and the connection member includes a first end fixed to one of the current collecting member or the terminal, a second end spaced apart from the first end and contacting the other of the current collecting member or the terminal, and a fuse portion between the first end and the second end, the fuse portion having a smaller cross-sectional area than a surrounding portion of the connection member.

The rechargeable battery may further include a lower insulation member into which a lower portion of the terminal and an upper portion of the current collecting member are inserted, and a fuse groove may be formed on the lower insulation member, the fuse groove having a bottom surface spaced apart from the fuse portion and the second end of the connection member.

The terminal may include a flange portion, a terminal pillar protruding from the flange portion, and a first groove formed in the flange portion and receiving the first end of the connection member. The current collecting member may include an electrode combination portion fixed to the electrode assembly, and a terminal combination portion bent toward the terminal from the electrode combination portion, and the terminal combination portion may have a second groove receiving the second end of the connection member.

The lower insulation member may have a flange groove into which the flange portion is inserted, and a current collecting groove into which the terminal combination portion is inserted, and the fuse groove may be formed between the flange groove and the current collecting groove at a lower position than the flange groove.

The rechargeable battery may further include an insulative gasket between the cap plate and the terminal. The current collecting member may have a hole formed therein, and the gasket may include a protrusion inserted in the hole.

The rechargeable battery may further include a lower cover on an upper portion of the gasket and combined with the lower insulation member by being inserted therein, and the current collecting member may have a hole formed therein, and the lower cover may include a protrusion inserted in the hole.

The second end of the connection member may include a second connection plate, and a protrusion may be formed on the second connection plate. The protrusion may be formed by bending the second connection plate. The fuse portion may be configured to separate from the surrounding portion in an overcurrent condition and drop into the fuse groove.

In one embodiment, the connection member may be integrally formed with the terminal. In another embodiment, the connection member may be integrally formed with the current collecting member. The first end of the connection member may include a first connection plate fixed to the terminal, and the second end of the connection member may include a second connection plate contacting the current collecting member. The connection member may be elastically deformed against the other of the current collecting member or the terminal.

According to an aspect of embodiments of the present invention, when a short circuit occurs by overcurrent, a blocking member allows a fuse member to be in a short circuit state, thereby improving safety of a rechargeable battery.

DESCRIPTION OF REFERENCE NUMERALS INDICATING SOME ELEMENTS IN THE DRAWINGS

DETAILED DESCRIPTION

FIG. 1is a perspective view of a rechargeable battery according to an exemplary embodiment of the present invention, andFIG. 2is a cross-sectional view of the rechargeable battery ofFIG. 1, taken along the line II-II.

Referring toFIG. 1andFIG. 2, a rechargeable battery101according to an exemplary embodiment of the present invention includes an electrode assembly10that is wound with a separator13interposed between a positive electrode11and a negative electrode12, a case40in which the electrode assembly10is housed, and a cap assembly30sealing an opening of the case40.

The rechargeable battery101is described and shown having an angular shape as a lithium ion rechargeable battery. However, the present invention is not limited thereto, and a rechargeable battery according to embodiments of the present invention may be of another of various shapes or types of batteries, such as a lithium polymer battery or a cylindrical battery.

In one embodiment, the positive electrode11and the negative electrode12include a coating region that is a region on which an active material is coated on a current collector formed of a metal foil or a thin plate, and uncoated regions11aand12athat are regions on which the active material is not coated.

The positive electrode uncoated region11ais formed at a side end of one side of the positive electrode11along a lengthwise direction of the positive electrode11, and the negative electrode uncoated region12ais formed at a side end of another side of the negative electrode12along a lengthwise direction of the negative electrode12. In one embodiment, the positive electrode11and negative electrode12are wound after a separator13that is an insulator is interposed therebetween.

However, the present invention is not limited thereto, and the electrode assembly10may have a structure in which a positive electrode and a negative electrode including a plurality of sheets are laminated with an insulator interposed therebetween.

The case40, in one embodiment, is formed having a generally cuboid shape, and an opening is formed on a side thereof. The cap assembly30includes a cap plate31that covers the opening of the case40, a positive electrode terminal21that protrudes to an external portion of the cap plate31and is electrically connected to the positive electrode11, a negative terminal22that protrudes to the external portion of the cap plate31and is electrically connected to the negative electrode12, and a vent member39in which a notch39ais formed such that the vent member39is broken according to an internal pressure (e.g., at a predetermined internal pressure).

The cap plate31, in one embodiment, is formed of a thin plate having an electrolyte injection opening37for injecting an electrolyte solution formed at one side, and a sealing stopper38that seals the electrolyte injection opening37is fixed to the cap plate31.

In one embodiment, the negative electrode terminal22is installed penetrating through the cap plate31, and between the cap plate31and the negative electrode terminal22, a first gasket25disposed at an upper portion and a second gasket28disposed at a lower portion insulate the cap plate31and the negative electrode terminal22from each other.

The negative electrode terminal22, in one embodiment, is formed in a cylindrical shape, a nut29that supports the negative electrode terminal22at the upper portion thereof is installed on the negative electrode terminal22, and a screw thread is formed on an external circumference of a terminal pillar22aof the negative electrode terminal22such that the nut29may be fastened thereto. A washer23may be installed between the nut29and the first gasket25.

In one embodiment, a terminal flange22bis formed at the lower portion of the negative electrode terminal22to support the negative electrode terminal22at the lower portion thereof. In one embodiment, the terminal flange22band a current collecting member41are inserted into a groove formed on a lower insulation member61that is disposed under the cap plate31. The lower insulation member61serves to insulate the current collecting member41and the negative electrode terminal22from the cap plate31.

The positive electrode terminal21is installed penetrating through the cap plate31, and between the cap plate31and the positive electrode terminal21, a first gasket27disposed at an upper portion and a second gasket26disposed at a lower portion insulate the cap plate31and the positive electrode terminal21from each other.

The positive electrode terminal21, in one embodiment, is formed having a cylindrical shape, a nut29that supports the positive electrode terminal21at the upper portion thereof is installed on the positive electrode terminal21, and a screw thread is formed on an external circumference of the positive electrode terminal21such that the nut29may be fastened thereto. A washer24may be installed between the nut29and the first gasket27.

FIG. 3is an exploded perspective view of a portion of the rechargeable battery101, andFIG. 4is a cross-sectional view of a portion of the rechargeable battery101.

The positive electrode terminal21, in one embodiment, includes a terminal flange21b, a terminal pillar21athat protrudes from the terminal flange21band has an external circumferential surface having the screw thread formed, and a first groove21cformed on a bottom side of the terminal flange21b.

The second gasket26, in one embodiment, is installed to cover the terminal flange21b, and has a plate portion26acovering the terminal flange21b, an upper insulation portion26binto which the terminal pillar21ais inserted and which surrounds the terminal pillar21a, and a plurality of protrusions26cthat protrude from a lower surface of the plate portion26aand are inserted into corresponding holes42dformed in a current collecting member42. The second gasket26, in one embodiment, is formed of an electrically insulative polymer material.

The positive electrode terminal21is electrically connected to the positive electrode11through the current collecting member42. The current collecting member42, in one embodiment, includes an electrode combination portion42athat is attached to the electrode assembly10(e.g., by welding), and a terminal combination portion42bthat is bent toward the positive electrode terminal21at an upper end of the electrode combination portion42a. A second groove42cis formed on a lower surface of the terminal combination portion42b, and the holes42dinto which the protrusions26care inserted are formed on the terminal combination portion42b.

Between the current collecting member42and the positive electrode terminal21, a connection member70on which a fuse portion73is formed is installed. The connection member70includes a first connection plate71inserted into the first groove21c, a second connection plate72inserted into the second groove42c, and the fuse portion73that is formed between the first connection plate71and the second connection plate72and has a smaller cross-sectional area than surrounding portions (i.e. the first and second connection plates71and72). In one embodiment, the fuse portion73is formed to have a smaller width than the first connection plate71and the second connection plate72to have a smaller cross-sectional area than surrounding portions.

The first connection plate71, in one embodiment, is a fixed end by being fixed to the positive electrode terminal21(e.g., by welding), and the second connection plate72is contacted with the current collecting member42in a free end state. In one embodiment, an upper surface of the second connection plate72is formed higher than the second groove42c, and the second connection plate72is installed such that the second groove42cpresses down on the second connection plate72(e.g., in an elastically deformed state). Accordingly, contact resistance between the current collecting member42and the connection member70may be minimized or reduced.

A lower insulation member62is installed under the positive electrode terminal21and, in one embodiment, includes a terminal groove62ainto which the terminal flange21bis inserted, a current collecting groove62cwhich is spaced apart from the terminal groove62aand into which the current collecting member42is inserted, and a fuse groove62bthat is formed between the terminal groove62aand the current collecting groove62cand is formed having a depth lower than the terminal groove62a.

The terminal groove62asupports the terminal flange21bthat is inserted therein, and the first connection plate71is inserted and fixed between the terminal groove62aand the first groove21c. The current collecting groove62csupports the terminal combination portion42bby inserting the terminal combination portion42btherein.

The second connection plate72and the fuse portion73are disposed over the fuse groove62band spaced apart from the bottom of the fuse groove62b, and a space in which the fuse portion73and the second connection plate72may be received is formed under the fuse portion73and the second connection plate72. Accordingly, the second connection plate72is formed in a free end form, which does not have a structure that is supported at the lower portion thereof.

As shown inFIG. 4, if an overcurrent flows due to a short circuit, the fuse portion73is melted, and a portion of the melted fuse portion73and the second connection plate72fall into the fuse groove62b. Accordingly, after the fuse portion73is melted, a spark is prevented or substantially prevented from occurring between the melted portions at a cut portion because a space between the melted portions is not narrow, and the fuse portion73is prevented or substantially prevented from becoming reconnected by external vibration. If a spark were to occur, a rechargeable battery could be ignited or exploded due to a flame. However, in the rechargeable battery101according to the present invention, when the fuse portion73is operated, the melted portion of the fuse portion73and the second connection plate72fall into the fuse groove62band the space between the melted portions is not narrow, such that reconnection of the fuse portion73or a spark between the melted portions is prevented or substantially prevented. As such, the rechargeable battery101is particularly suited for application in an electric vehicle or a hybrid electric vehicle.

In addition, if a melted fuse portion at a high temperature were to fall into an electrolyte solution, the electrolyte solution could be ignited. However, according to embodiments of the present invention, the melted fuse portion73falls into the fuse groove62b, and contact between the fuse portion73at a high temperature and the electrolyte solution is prevented or substantially prevented.

FIG. 5is a cross-sectional view of a portion of a rechargeable battery according to another exemplary embodiment of the present invention, andFIG. 6is a perspective view of a connection member of the rechargeable battery ofFIG. 5.

Referring toFIG. 5andFIG. 6, a rechargeable battery102according to another exemplary embodiment of the present invention has a same or substantially same structure as the rechargeable battery101described above, except for a structure of a connection member80, and further description of the same structures is therefore omitted.

The connection member80according to one embodiment includes a first connection plate81that is inserted into the first groove21cformed on the terminal flange21b, a second connection plate82that is inserted into the second groove42cformed on the current collecting member42, and a fuse portion83that is formed between the first connection plate81and the second connection plate82and has a smaller cross-sectional area than surrounding portions (i.e. the first and second connection plates81and82). The fuse portion83, in one embodiment, is formed to have a smaller width than the first connection plate81and the second connection plate82to have a smaller cross-sectional area than surrounding portions.

In one embodiment, the first connection plate81is a fixed end by being fixed to the positive electrode terminal21(e.g., by welding), and the second connection plate82is contacted with the current collecting member42in a free end state. A plurality of protrusions84are formed on an upper surface of the second connection plate82, and the protrusions84contact the current collecting member42. The upper surfaces of the protrusions84are formed higher than the second groove42c, and the second groove42cpresses down on the second connection plate82, such that the connection member80is contacted with the current collecting member42in an elastically deformed state. Accordingly, contact resistance between the current collecting member42and the connection member80may be minimized or reduced.

FIG. 7is a cross-sectional view of a portion of a rechargeable battery according to another exemplary embodiment of the present invention.

Referring toFIG. 7, a rechargeable battery103according to another exemplary embodiment of the present invention has a same or substantially same structure as the rechargeable battery101described above, except for a structure of an insulative second gasket91and an insulative lower cover92, and further description of the same structures is therefore omitted.

The positive electrode terminal21includes the terminal pillar21aprotruding from the terminal flange21b, the terminal pillar21ahaving an external circumferential surface having a screw thread, and the first groove21cis formed on the bottom of one side of the terminal flange21b.

The second gasket91is installed to cover the terminal flange21b, and the lower cover92covering the second gasket91is installed on the second gasket91. The lower cover92is installed to cover the second gasket91, and is combined with a groove formed on the lower insulation member62by being inserted therein.

In addition, a protrusion92ainserted into the hole42cformed on the current collecting member42is formed on the lower cover92. Accordingly, the current collecting member42may be stably supported by the protrusion92abetween the lower cover92and the lower insulation member62.

FIG. 8is an exploded perspective view of a portion of a rechargeable battery according to another exemplary embodiment of the present invention, andFIG. 9is a cross-sectional view of a portion of the rechargeable battery ofFIG. 8, shown in an assembled state.

Referring toFIG. 8andFIG. 9, a rechargeable battery104according to another exemplary embodiment of the present invention has a same or substantially same structure as the rechargeable battery101described above, except for a structure of a positive electrode terminal121and a connection portion121c, and further description of the same structures is therefore omitted.

The positive electrode terminal121includes a terminal pillar121aprotruding at a terminal flange121band having an external circumferential surface having a screw thread, the terminal pillar121aextending from an end of one side of the terminal flange121b. The positive electrode terminal121further includes a connection portion121cthat is electrically contacted with the current collecting member42, and a fuse portion121dformed between the connection portion121cand the terminal flange121b.

The connection portion121c, in one embodiment, is formed as a plate that is inserted into the second groove42cformed on the current collecting member42. In one embodiment, a protrusion121ebent and protruding is formed on the connection portion121c, such that the protrusion121epresses against the current collecting member42and is contacted therewith. In one embodiment, the protrusion121eis pressed and is elastically deformed to be contacted with the current collecting member42. Accordingly, contact resistance between the connection portion121cand the current collecting member42may be minimized or reduced.

The fuse portion121dhas a smaller cross-sectional area than surrounding portions, and when an overcurrent flows, the fuse portion is melted to cut electrical connection between the positive electrode terminal121and the current collecting member42.

In the rechargeable battery104, the fuse portion121dand the connection portion121care formed on the positive electrode terminal121and, therefore, it is not necessary to install a separate connection member, and the contact resistance may be minimized or reduced. That is, the fuse portion121dand the connection portion121care a connection member that is formed on (e.g., integrally formed with) the positive electrode terminal121. In addition, if the fuse portion121dis melted, the fuse portion121dfalls into the fuse groove62bformed on the lower insulation member62, such that reconnection of the melted portion or an occurrence of a spark is prevented or substantially prevented.

FIG. 10is a cross-sectional view of a portion of a rechargeable battery according to another exemplary embodiment of the present invention, andFIG. 11is a perspective view of a current collecting member of the rechargeable battery ofFIG. 10.

Referring toFIG. 10andFIG. 11, a rechargeable battery105according to another exemplary embodiment of the present invention has a same or substantially same structure as the rechargeable battery101described above, except for a structure of a current collecting member242, and further description of the same structures is therefore omitted.

The current collecting member242includes an electrode combination portion242athat is attached to the electrode assembly10(e.g., by welding), a terminal combination portion242bthat is formed by being bent toward the positive electrode terminal21at the electrode combination portion242a, one or more holes242cformed in the terminal combination portion242b, a connection portion242dthat is electrically contacted with the positive electrode terminal21, and a fuse portion242ethat is formed between the connection portion242dand the terminal combination portion242b.

The connection portion242d, in one embodiment, is formed having a plate form and is inserted into the first groove21cformed on the terminal flange21b. A protruding protrusion242fis formed on the connection portion242d, and the protrusion242fis pressed against the terminal flange242band is contacted therewith.

The fuse portion242eis formed to have a smaller cross-sectional area than surrounding portions, and when an overcurrent flows, the fuse portion is melted to cut electrical connection between the positive electrode terminal21and the current collecting member242.

In the rechargeable battery105, according to an exemplary embodiment, the fuse portion242eand the connection portion242dare formed on the current collecting member242, such that a separate connection member is not needed, and a contact resistance may be minimized or reduced. That is, the fuse portion242eand the connection portion242dare a connection member that is formed on (e.g., integrally formed with) the current collecting member242. In addition, if the fuse portion242eis melted, the fuse portion242eand the connection portion242dfall into the fuse groove62bformed on the lower insulation member62, such that reconnection of the melted portion or an occurrence of a spark is prevented or substantially prevented.