Rechargeable battery and battery module using the same

The present invention relates to a rechargeable battery including an electrode assembly comprising a positive electrode, a negative electrode, and a separator interposed therebetween. The battery further comprises a case accommodating the electrode assembly and a plurality of positive electrode terminals and negative electrode terminals that are exposed outside of the case, connected to the case, and coupled to the electrode assembly.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority to and the benefit of Korean Patent Application No. 10-2004-0035482 filed on May 19, 2004, in the Korean Intellectual Property Office, the entire disclosures of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a high power, high capacity, rechargeable battery that has an improved connecting structure between unit cells. The present invention also relates to a battery module using the rechargeable battery.

2. Discussion of the Background

There exists a need to develop a high power rechargeable battery that uses a non-aqueous electrolyte and has high energy density. Such a battery may be used in low capacity batteries in which battery cells are packaged into packs that serve as power sources for various portable small electronic devices such as cellular phones, laptop computers, and camcorders. Alternately, a high capacity rechargeable battery in which several tens of battery cells are connected in series or in parallel may be used as a power source for driving motors such as in a hybrid automobile.

Such a high capacity rechargeable battery or battery module is typically assembled by connecting a plurality of rechargeable batteries together in series to form a unit cell. Each unit cell is comprises an electrode assembly, a case, and a cap assembly.

That is, the unit cell may be fabricated into various shapes such as cylindrical and rectangular. An electrode assembly of the unit cell may comprise a bar of positive and negative electrode sheets and an insulator separator interposed therebetween that are wound together as in a jelly roll and are inserted into a case. The case is mounted with a cap assembly formed with outer terminals to provide a battery.

A rectangular unit cell having the above-mentioned structure is disclosed in Japanese Utility Application Laid-Open No. H06-86259. It also discloses a structure that has a cap with terminals protruding from the surface of the rectangular case.

However, since the rechargeable battery disclosed in the publication has terminals on only one side surface of the battery, it is difficult to connect unit cells together and the utilization of the battery is limited. That is, the positive electrodes and the negative electrodes of the electrode assembly are mounted with a conductive tab or a current collecting plate that collects current that is generated when operating the battery. The tab or the current collecting plate is connected with a positive electrode terminal and a negative electrode terminal that is mounted on the cap assembly via a lead to introduce the current that is generated in the positive electrode and the negative electrode to the positive electrode terminal and the negative electrode terminal, respectively.

However, since the above-mentioned positive electrode terminals and negative electrode terminals are mounted on only one side of the cap assembly, a separate connecting member is required to join the unit cells to provide a battery module. Therefore, it is difficult to connect the unit cells and the space utilization is deteriorated.

FIG. 5shows a battery module100according to the prior art in which units cells are connected in series. According toFIG. 5, the positive electrode terminal114and the negative electrode terminal115that protrude on the upper surface of the cap assembly113of each unit cell111are positioned beside the negative electrode terminal115and the positive electrode terminal114of the adjacent unit cell111, respectively. The connection members116connect the threaded negative electrode terminals115and positive electrode terminals114via nuts117,118.

If the lower part of the case of the unit cell according to the prior art is positioned to face the floor, since both the positive electrode terminal and the negative electrode terminal are disposed on only the upper part of the case, the unit cells may have to be arranged beside each other to connect with each other in series or in parallel. Thus, the unit cells are positioned inefficiently with respect to a certain unit space.

This problem becomes more serious for hybrid electric vehicles that require numerous unit cells confined to a certain space to provide high capacity and high power. As the aforementioned unit cells of the prior art must be arranged in only one configuration the capacity and power are deteriorated per unit area are reduced.

In addition, in order to provide a battery module according to the prior art, several or several tens of unit cells are connected using nuts. The insulation of the nuts is difficult and time consuming, so the cost thereof is increased.

SUMMARY OF THE INVENTION

The present invention discloses a rechargeable battery that improves space utilization by improving the connection structures of terminals of unit cells to increase power and capacity of the battery per unit area. The present invention also discloses a battery module using the same.

The present invention also discloses a rechargeable battery in which the terminal structure of the battery is improved by simplifying the connection between unit cells to save time and labor required for connection and replacement work. The present invention also discloses a battery module using the same.

The rechargeable battery and battery module of the present invention are useful as the power source for high power electronic devices such as electric vehicles, hybrid electric vehicles, wireless vacuum cleaners, motorbikes, and motor scooters.

The present invention provides a rechargeable battery comprising an electrode assembly comprising a positive electrode, a negative electrode, and a separator interposed therebetween. The battery also comprises a case accommodating the electrode assembly and a plurality of positive electrode terminals and negative electrode terminals that are exposed from of the case, connected to the case, and coupled to the electrode assembly.

The present invention also provides a battery module comprising a rechargeable battery comprising a plurality of unit cells. The plurality of unit cells are coupled wherein one end of a unit cell and another end thereof are respectively provided with a positive electrode terminal and a negative electrode terminal so that at least two unit cells can be coupled.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The present invention provides a rechargeable battery comprising an electrode assembly comprising a positive electrode, a negative electrode, and a separator interposed therebetween. The rechargeable battery also comprises a case that accommodates the electrode assembly and a plurality of positive electrode terminals and negative electrode terminals that are exposed outside the case, connected to the case, and coupled to the electrode assembly. The rechargeable battery is preferably formed as a rectangular case and an electrode assembly that is wound like a jelly roll.

The positive electrode and the negative electrode of the electrode assembly each comprise a current collector, a coated region coated with active materials, and an uncoated region. The uncoated region is formed along one end of each of the positive electrode and the negative electrode in opposite directions to form both ends of the electrode assembly.

The uncoated region of the negative electrode and the uncoated region of the positive electrode are disposed on each side of the case when the case is positioned for the top cap assembly to face upwards. This allows the positive electrode terminal and the negative electrode terminal mounted on the top cap assembly and the positive electrode terminal and the negative electrode terminal mounted on the bottom cap assembly to be coupled to the uncoated regions of the positive electrode and the negative electrode via the tab (or current collecting plate), respectively.

In the above-mentioned structure, the other side of the case may be provided with a positive electrode terminal and a negative electrode terminal with a separate insulating member positioned in between the case and the negative electrode terminal and the positive electrode terminal to insulate them. Each end of the case for the rechargeable battery may be provided with a cap assembly that is mounted with a positive electrode terminal and a negative electrode terminal in order to close the case and to couple to the electrode assembly.

The positive and negative electrode terminal pairs that are mounted at each end of the case may be disposed such that the positive electrodes and the negative electrodes are respectively mounted on the same side or on opposite sides. Further, the terminals mounted on the ends of the case preferably have a post structure that has a threaded surface.

According to the battery module of the present invention in which several unit cells are coupled, both ends of a unit cell are respectively mounted with the positive electrode terminal and the negative electrode terminal so that at least two unit cells can be coupled thereto via connection members.

The unit cells for the battery module may be connected in series or in parallel via connection members while disposing them in both vertical and horizontal directions. The unit cells for the battery module are arranged in the vertical direction by connecting upper terminals mounted on the ends of a unit cell to lower terminals of a unit cell directly thereabove, via a connection conductor, in series or in parallel. Further, the unit cells are disposed in the horizontal and vertical directions to connect adjacent unit cells via a connection conductor and a connection member in series or in parallel.

The terminals mounted on the unit cells have a threaded axis structure formed with a screw mount. The connection conductor is composed of a nut having a length sufficient to fasten two terminals together, so that two unit cells can be coupled with one nut when the terminals of the two unit cells are aligned in a lengthwise direction.

Hereinafter, preferable embodiments of the present invention are described in detail with reference to the attached drawings.

FIG. 1is a schematic perspective view showing a rechargeable battery according to an exemplary embodiment of the present invention.FIG. 2Ais a perspective view showing a jelly roll type of electrode assembly.FIG. 2Bis an exploded perspective view showing a lamination type of electrode assembly.FIG. 3is a front view of the rechargeable battery according to another exemplary embodiment of the present invention.FIG. 4is a schematic perspective view showing the battery module in which unit cells are connected according to the present invention.

Referring toFIG. 1, each unit cell11for the high capacity battery module comprises an electrode assembly12comprising a negative electrode, a positive electrode, and a separator interposed therebetween. The unit cell also comprises a case13enclosing a space accommodating the electrode assembly12, cap assemblies14a,14bconnected at the upper end and the lower end of the case respectively, via a gasket when the case13is enclosed by the same. In addition, positive electrode terminals16a,17aand negative electrode terminals16b,17bprotrude out of each cap assembly14a,14bof each unit cell11. Each terminal16a,16b,17a,17bis threaded and is coupled to the positive electrode12aand the negative electrode12bvia a tab15.

The case13is fabricated with a conductive metal such as aluminum, an aluminum alloy, or steel plated with nickel, for example, and is formed into a hexahedron or other shapes that have an inner space that accommodates an electrode assembly.

Further, the cap assemblies14a,14bare firmly mounted to the terminals on the surface thereof, and may comprise a gasket (not shown) insulating between the case13and the cap plates140a,140b. The cap assemblies may further comprise a vent plate (not shown) that vents gas by being ruptured at a set pressure to prevent expansion of the battery.

Referring toFIG. 2A, the electrode assembly12may be formed as a wound jelly roll type in which a positive electrode12aand a negative electrode12bcoated with an appropriate active material on the respective current collectors are laminated with a separator interposed therebetween and are then spiral-wound in a jelly roll shape. Both ends of the jelly roll type of electrode assembly are provided with uncoated regions12d,12e.FIG. 2Bshows a lamination type of electrode assembly120in which positive electrodes120aand negative electrodes120bthat are coated with each active material on the respective current collectors are laminated with a separator120cinterposed therebetween, and an end each of the positive electrodes120aand negative electrodes120bare provided with uncoated regions120d,120e.

Hereinafter, examples are described with reference to the jelly roll type of electrode assembly12as shown inFIG. 2A. Needless to say, the laminated electrode assembly120as shown inFIG. 2Bmay alternately be employed.

Further, these examples are described with reference to the structure in which the uncoated region12dof the positive electrode and the uncoated region12eof the negative electrode that are coupled to the respective terminals are each formed along one end of each electrode for the electrode assembly12. Needless to say, the present invention is not limited to the above-mentioned structure and is applicable to all battery shapes as well as those without the uncoated regions.

According to this embodiment of the present invention, the electrode assembly12for the rechargeable battery comprises an uncoated region12dof the positive electrode and an uncoated region12eof the negative electrode that face each other at respective ends of the jelly roll type of electrode assembly. The positive electrode12a, the negative electrode12b, and the separator that is interposed therebetween are wound into a jelly roll shape. When the case13is vertically positioned to install the cap assemblies14a,14bat upper and lower ends thereof, the uncoated regions12d,12eof the positive electrode12aand the negative electrode12bare disposed at opposite ends of the case. The terminals16a,17a,16b,17bof the cap assemblies14a,14bare coupled via tabs15(or current collecting plates) that are mounted to the uncoated region12d,12e.

The rechargeable battery has a structure in which the electrode terminals16a,16band the electrode terminals17a,17bare respectively protruded upwardly and downwardly at the ends of the case13.

As shown inFIG. 4, a plurality of the above-mentioned unit cells11are arranged with and are connected to each other in series or in parallel to provide a battery module10. According to this embodiment, when a unit cell11is positioned vertically so that the terminals16a,16b, and17a,17brespectively face upward and downward, the unit cells11are positioned in both a horizontally stacked direction (H direction inFIG. 4) and in a vertical direction (V direction inFIG. 4) to connect them together.

When the unit cells11are positioned in the horizontal direction H to connect with each other, a unit cell is disposed to face an adjacent unit cell with a space therebetween. The positive electrode terminals16aand negative electrode terminals16bthat protrude from the upper cap assemblies14aof the unit cells are arranged such that the positive electrode terminal16aof one unit cell and the negative electrode terminal16bof the adjacent unit cell are beside each other. This pattern is repeated while maintaining a certain distance between the unit cells11based on the centers thereof, to form a terminal row, which is one line that has terminals in which polarities are alternatively arranged.

In order to connect the unit cells11in series, the positive electrode terminal16aof one unit cell11and the negative electrode terminal16bof the adjacent unit cell are coupled via a connection member20. The connection member20has a plate structure that is formed with holes21at both ends. A nut18is threaded onto each terminal16a,16b, and the terminals16a,16bare inserted through the holes21and the connection member20is fastened with nuts22to affix it thereto. This confirmation allows the positive electrode terminals16aof unit cells11to be connected to the negative electrode terminals16bof adjacent unit cells11via connection member20to form the terminal row of serially connected unit cells11along the H direction.

In addition, as shown inFIG. 4, the unit cells may be arranged to connect with each other in a vertical direction V. A positive electrode terminal17aand a negative electrode terminal17bthat are mounted on the lower cap assembly14bof one unit cell11respectively face the positive electrode terminal16aand the negative electrode terminal16bthat are mounted on the upper cap assembly14aof the adjacent unit cell11in the V direction. The positive electrode terminals17a,16aof the adjacent unit cells11are fastened together by connection conductors30in the form of nuts to couple them to each other in the vertical direction in a parallel circuit.

In other words, the positive electrode terminal (or the negative electrode terminal) mounted on the lower cap assembly14bof the upper unit cell is fastened to the positive electrode terminal (or the negative electrode terminal) mounted on the upper cap assembly14aof the lower unit cell through both ends of the connection conductor30. This configuration allows the terminals of two unit cells that are coupled via one connection conductor30to be coupled to each other in parallel. Therefore, the unit cells may be arranged in a vertical direction V as well as in a horizontal direction H to electrically connect to each other. It is then possible to couple many unit cells11and to maximize the capacity of the battery module10.

The unit cells of the H or V configurations may be coupled in series or in parallel. When the unit cells are disposed in the vertical direction, the terminal positions of the unit cells11can alternate to form a terminal row in which positive electrode terminals and negative electrode terminals are repeatedly connected to each other in a vertical direction. Thereby, the positive electrode terminal17aof one unit cell11is fastened to the negative electrode terminal16bof a vertically adjacent unit cell with a certain interval via a connection member30to connect the unit cells11in series.

All unit cells disposed in a horizontal or a vertical direction are generally connected in series so that the power of the battery module is maximized.

According to this embodiment of the present invention, several unit cells may be easily connected in series or in parallel to form a battery module. Further, when a plurality of unit cells are coupled together, the arranged structure of the unit cells may be varied to carry more unit cells per certain unit space so that the power and capacity thereof are maximized per unit area.