Battery module and battery pack including the same

A battery module for containing a plurality of battery units, the battery module including first and second end plates facing each other; and a side plate, the side plate being for extending across a side of the battery units, and the side plate having a first end coupled to the first end plate and a second end coupled to the second end plate, wherein a work hardening unit is disposed at the second end of the side plate, the work hardening unit being hardened in such a way that the second end of the side plate is bent.

BACKGROUND

Embodiments relate to a battery module and a battery pack including the same.

2. Description of the Related Art

In general, secondary batteries are chargeable and dischargeable unlike primary batteries, which are not chargeable. Secondary batteries may be used as energy sources for, e.g., mobile devices, electric vehicles, hybrid electric vehicles, electric bicycles, and uninterruptible power supply devices. Secondary batteries may be used in the form of a single battery or in the form of a battery module in which a plurality of batteries are electrically connected and packed as a single unit, according to the type of an external device in which the secondary batteries are to be used.

Small-sized devices such as mobile phones may be operated for a predetermined amount of time by using power output by and capacity of a single battery. On the other hand, battery modules may be usually used instead of a single battery in devices such as electric vehicles and hybrid electric vehicles consuming large amounts of power for a long time, since power output and capacity of a single battery may be insufficient. An output voltage and an output current of a battery module depends on the number of batteries accommodated therein.

In such battery modules, an assembly structure may be required to systematically bind a plurality of batteries to form a single assembly. The assembly structure may need to provide a coupling force sufficient for binding the plurality of batteries. Lithium ion batteries may be used as the secondary batteries. While lithium ion batteries may maintain a high performance even after repeated charging and discharging, a negative electrode thereof may expand due to lithium ions that are transferred during charging.

SUMMARY

Embodiments are directed to a battery module and a battery pack including the same, which represent advances over the related art.

It is a feature of an embodiment to provide a battery module capable of providing a coupling force that is sufficient to assemble a plurality of batteries in a single assembly.

It is another feature of an embodiment to provide a battery module for inhibiting deterioration of electrical characteristics by preventing expansion of batteries.

At least one of the above and other features and advantages may be realized by providing a battery module for containing a plurality of battery units, the battery module including first and second end plates facing each other; and a side plate, the side plate being for extending across a side of the battery units, and the side plate having a first end coupled to the first end plate and a second end coupled to the second end plate, wherein a work hardening unit is disposed at the second end of the side plate, the work hardening unit being hardened in such a way that the second end of the side plate is bent.

The work hardening unit may be adjacent to a coupling hole in the side plate and may contact a coupling member extending through the coupling hole.

The coupling hole may include a long coupling hole and a circular coupling hole, the circular coupling hole overlapping the long coupling hole by way of a portion of the side plate in which the long coupling hole and circular coupling hole are spaced apart from each other in a lengthwise direction being bent over itself into an overlapping condition.

The long coupling hole may have an oval shape with a major axis along the lengthwise direction of the side plate.

The circular coupling hole may have a substantially circular shape.

The side plate may include a first side plate that extends across a first surface of the battery units; and a second side plate that extends across a second surface of the battery units, the second surface being opposite to the first surface.

Each of the first and second end plates may include a base plate adjacent to the battery units; a first flange unit that is bent from the first side of the base plate in a direction away from the battery units; and a second flange unit that is bent from the second side of the base plate in a direction away from the battery units.

The first side plate may be coupled to the first flange units and the second side plate may be coupled to the second flange units.

At least one of the above and other features and advantages may also be realized by providing a battery module for containing a plurality of battery units, the battery module including first and second end plates facing each other; and a side plate, the side plate having a first end coupled to the first end plate and extending toward the second end plate, surrounding the second end plate, extending toward the first end plate, and being coupled to the first end plate via a second end of the side plate, wherein a work hardening unit is disposed at the second end of the side plate, the work hardening unit being hardened in such a way that the second end of the side plate is bent.

The work hardening unit may be adjacent to a coupling hole in the side plate and may contact a coupling member extending through the coupling hole.

The coupling hole may include a long coupling hole and a circular coupling hole, the circular coupling hole overlapping the long coupling hole by way of a portion of the side plate in which the long coupling hole and circular coupling hole are spaced apart from each other in a lengthwise direction being bent over itself into an overlapping condition.

The long coupling hole may have an oval shape with a major axis along the lengthwise direction of the side plate.

At least one of the above and other features and advantages may also be realized by providing a battery pack including a plurality of battery modules, each battery module including first and second end plates facing each other; a plurality of battery units disposed between the first and second end plates; and a side plate, the side plate being for extending across a side of the battery units and having a first end coupled to the first end plate and a second end coupled to the second end plate, wherein a work hardening unit is disposed at the second end of the side plate, the work hardening unit being hardened in such a way that the second end of the side plate is bent.

The work hardening unit may be adjacent to a coupling hole in the side plate and may contact a coupling member extending through the coupling hole.

The coupling hole may include a long coupling hole and a circular coupling hole, the circular coupling hole overlapping the long coupling hole by way of a portion of the side plate in which the long coupling hole and circular coupling hole are spaced apart from each other in a lengthwise direction being bent over itself into an overlapping condition.

The long coupling hole may have an oval shape with a major axis along the lengthwise direction of the side plate.

The circular coupling hole may have a substantially circular shape.

The side plate may include a first side plate that extends across a first surface of the battery units; and a second side plate that extends across a second surface of the battery units, the second surface being opposite to the first surface.

Each of the first and second end plates may include a base plate adjacent to the battery units; a first flange unit that is bent from the first side of the base plate in a direction away from the battery units; and a second flange unit that is bent from the second side of the base plate in a direction away from the battery units.

The first side plate may be coupled to the first flange units and the second side plate may be coupled to the second flange units.

DETAILED DESCRIPTION

Korean Patent Application No. 10-2009-0131805, filed on Dec. 28, 2009, in the Korean Intellectual Property Office, and entitled: “Battery Module and Battery Pack Comprising the Same,” is incorporated by reference herein in its entirety.

In the drawing figures, the dimensions of layers and regions may be exaggerated for clarity of illustration. It will also be understood that when a layer or element is referred to as being “on” another element, it can be directly on the other element, or intervening elements may also be present. Further, it will be understood that when an element is referred to as being “under” another element, it can be directly under, and one or more intervening elements may also be present. In addition, it will also be understood that when an element is referred to as being “between” two elements, it can be the only layer between the two elements, or one or more intervening elements may also be present. Like reference numerals refer to like elements throughout.

The battery pack of an embodiment described herein may include a plurality of battery modules, each including a plurality of battery units that are arranged in a predetermined direction and electrically connected to each other.

FIG. 1illustrates an exploded perspective view of a battery module100. Referring toFIG. 1, the battery module100may include a plurality of battery units10that are arranged in a row15, and plates20,30,40,51, and52that surround the battery row15. In an implementation, the battery units10may be arranged in a single row in a predetermined direction. In another implementation, the battery module100may have a stacked structure in which the battery units10are arranged in multiple rows.

The battery units10may each be a secondary battery, e.g., a lithium ion battery. The battery units10may be any of various types of secondary batteries, e.g., cylindrical shape secondary batteries, square pillar shape secondary batteries, or polymer secondary batteries, but are not limited thereto. The battery units10may each include an electrode assembly (not shown), a case11, and electrode terminals12. Each electrode assembly (not shown) may include a positive electrode, a separator, and a negative electrode that are stacked and that may be wound. The cases11may accommodate the electrode assemblies; and the electrode terminals12may protrude out of the cases11in order to allow for an electrical connection between the electrode assemblies and an external circuit. The battery units10may be electrically connected to each other in series or in parallel via the electrode terminals12. For example, the electrode terminals12may be connected to each other via bus bars18. Each case11may include a safety vent13. The safety vents13may have a relatively low strength to fracture when an internal pressure in the cases11exceeds a predetermined threshold to thereby emit gas contained in the cases11.

The plates51and52may include first end plates51and second end plates52at ends of the battery row15. Each of the first and second end plates51and52may have a surface that is in a close contact with an outermost battery unit10of the battery row15. The first and second end plates51and52may bind the battery units10constituting the battery row15as a single unit, may inhibit volume expansion of the battery units10caused by charging and discharging operations, and may maintain resistance characteristics of the battery units10, so that deterioration of electrical characteristics of the battery may be beneficially inhibited.

The first and second end plates51and52may each include a base plate61and flange units62,63,64, and65that are bent at edges of the base plate61. The base plates61may each have an area that is sufficient to cover an external surface of the battery units10.

The flange units62,63,64, and65may be bent at edges of the base plates61in a direction away from the battery row15. In this regard, single flange units63and64may be formed by bending, without cutting, entire right, left, and lower edges of the base plates61. The flange units62and65may be separated from each other by cutting upper edges of the base plates61and bending the cut edges at different positions so that the bent portions have different heights. The flange units62,63,64, and65may function as a coupling unit to facilitate coupling of the first and second end plates51and52with other members and may be modified in various ways. In addition, the flange units62,63,64, and65may reinforce mechanical rigidity of the first and second end plates51and52. The flange units62,63,64, and65may include a plurality of binding holes.

The first and second end plates51and52may be connected to each other via plates40, which may be side plates. In other words, the side plates40may bind the first and second end plates51and52to each other. The side plates40may extend along sides of the battery row15. First ends of the side plates40may be coupled to the first end plate51and second ends of the side plates40may be coupled to the second end plate52. The side plates40may each have a strip shape that extends along the battery row15. The first ends of the side plates40may each have a first coupling hole41through which the side plates40and the flange unit64, bent at right and left edges of the first end plate51, may be, e.g., screw-coupled, to each other. For example, the side plates40and the flange unit64may be screw-coupled by overlapping the side plates40and the flange unit64and coupling them using coupling members45through the first coupling holes41. In an implementation, bolts may be inserted into the first coupling holes41and fastened with nuts.

The second ends of the side plates40may each have a second coupling hole42through which the side plates40and the flange unit64, that is bent at right and left edges of the second end plate52, may be, e.g., screw-coupled, to each other. The side plates40and the flange unit64may be screw-coupled by overlapping the side plates40and the flange unit64and coupling them using coupling members45through the second coupling holes42. In an implementation, bolts may be inserted into the second coupling holes42and fastened with nuts.

Work hardening units WH may be formed at the second ends of the side plates40, which may be adjacent to the second coupling holes42. For example, the work hardening units WH may have a roll shape at the second ends of the side plates40. The protruding work hardening units WH may contact the coupling members45when the coupling members45are inserted into the coupling holes42. Thus, coupling of the side plates40to the second end plate52may be strengthened since the work hardening units WH and the coupling members45are hooked together. The work hardening units WH may be formed by bending the second ends of the side plates40and overlapping the bent portions back onto the side plates40. The bent portions may have improved mechanical rigidity after they are processed by a work hardening process. Electrical characteristics of the battery units10may not be deteriorated since volume expansion of the battery units10may be inhibited due to a coupling force applied in the lengthwise direction of the side plates40. Further, the coupling force of the side plates40may be reinforced by forming the work hardening units WH at the second ends of the side plates40.

The side plates40may each have at least one heat dissipation hole40a. For example, a plurality of the heat dissipation holes40amay be disposed along the lengthwise direction of the side plates40at equal intervals. Since the heat dissipation holes40amay allow contact between the battery units10and external air, heat generated during operation of the battery units10may quickly be dissipated from the battery units10.

The plate30may be a lower plate under the battery row15. The lower plate30may be connected to lower portions of the first and second end plates51and52across a bottom of the battery row15. The lower plate30may include bending units30athat are bent from side ends thereof to face each other. The lower plate30may support the total weight of the battery module100and bending rigidity thereof may be reinforced due to the bending units30a.

The lower plate30and the flange units63bent from the lower edges of the first and second end plates51and52may be, e.g., screw-coupled. The lower plate30and the flange units63may overlap each other and positions of coupling holes may correspond to each other and may then be screw-coupled using coupling members, e.g., bolts and nuts.

The plate20may be an upper plate disposed on the battery row15. The upper plate20may be connected to upper portions of the first and second end plates51and52across a top of the battery row15. The upper plate20may have bending units21that are bent from side ends thereof to face each other. The upper plate20may have openings20aalong a lengthwise direction of the upper plate20so as to correspond to the safety vents13of the battery units10. The upper plate20and the flange units62, bent from the upper edges of the first and second end plates51and52, may be, e.g., screw-coupled. The upper plate20and the flange units62may overlap each other and positions of coupling holes may correspond to each other, and may then be screw-coupled using coupling members, e.g., bolts and nuts.

FIGS. 3A and 3Billustrate perspective views of a battery module showing the formation of the work hardening units WH of the side plates40. Referring toFIG. 3A, the first end of one side plate40may be fixed to the first end plate51and may extend toward the second end plate52. A long coupling hole42aand a circular coupling hole42bmay be disposed at the second end of the side plate40and spaced apart from each other by a predetermined distance in the lengthwise direction of the side plate40.

Referring toFIGS. 3A and 3B, the second end of the side plate40may be bent into a roll shape to overlap the circular coupling hole42bover the long coupling hole42a. Accordingly, the work hardening unit WH bent into a roll shape may be formed. The work hardening unit WH may have a flat-folded shape by applying compression, i.e., pressure, thereto. In this regard, a position of the circular coupling hole42boverlapping the long coupling hole42amay be changed along the lengthwise direction of the side plate40according to the bending of the side plate40and a manufacturing tolerance. Here, the long coupling hole42amay have a shape extending in the lengthwise direction of the side plate40so that the circular coupling hole42bmay easily correspond to the long coupling hole42a.

FIG. 4illustrates a perspective view of a battery pack300including a plurality of battery modules100as shown inFIG. 3B. Referring toFIG. 4, the battery pack300may be an assembly of a plurality of battery modules100that are stacked in a vertical direction Z1and a horizontal direction Z2. The number of the battery modules100constituting the battery pack300may be determined in consideration of charging and discharging current and capacity; and may be electrically connected to each other in series or in parallel.

Adjacent battery modules100may be coupled to each other by coupling the end plates51and52, which are outermost layers of the battery module100.FIG. 5illustrates an enlarged view of the end plates51and52ofFIG. 4. U, D, L, and R in brackets used herein respectively indicate relative positions of the battery modules100, i.e., upper (U), lower (D), left (L), and right (R). For example, the battery module100disposed at the upper left position may be indicated by100(U) and100(L).

The upper battery modules100(U) and the lower battery modules100(D) may be aligned in the vertical direction Z1. The lower flange units63may be disposed at lower edges of the upper battery modules100(U); and the upper flange units65may be disposed at upper edges of the lower battery modules100(D). The lower flange units63of the upper battery modules100(U) and the upper flange units65of the lower battery modules100(D) may be aligned to overlap each other and to align the coupling holes thereof. Then, the upper and lower battery modules100(U) and100(D) may be coupled using coupling members154through the coupling holes, e.g., by inserting bolts into the coupling holes and fastening the bolts with nuts. In this regard, the lower flange units63of the upper battery modules100(U) and the upper flange units65of the lower battery modules100(D) may have an interfacial contact therebetween on at least one portion. Via the interfacial contact between the lower flange units63and the upper flange units65, the weight of the upper battery modules100(U) may be sustained by the lower battery modules100(D).

The left battery modules100(L) and the right battery modules100(R) may be aligned in the horizontal direction Z2. The flange units64may be disposed at right edges of the left battery modules100(L) and left edges of the right battery modules100(R) and may be disposed to face each other. Here, the flange units64of the left battery modules100(L) and the right battery modules100(R) may overlap each other and coupling holes thereof may correspond to each other. Then, the left and right battery modules100(L) and100(R) may be coupled using coupling members164through the coupling holes, e.g., by inserting bolts into the coupling holes and fastened with nut.

As described above, a plurality of battery modules100that are aligned in the vertical direction Z1and the horizontal direction Z2may be assembled as a single battery pack300by coupling the end plates51and52. In this regard, the coupling of the end plates51and52may be conducted by using a mechanical coupling method using, e.g., bolts and nuts, or a welding method.

FIG. 6illustrates a perspective view of a battery module according to another embodiment. Referring toFIG. 6, the first and second end plates51and52may be disposed at the outermost layers of the battery row15; and side plates140that are disposed across sides of the battery row15may be coupled to the first and second end plates51and52. The side plates140may extend along sides of the battery row15. First ends of the side plates140may be coupled to the first end plate51; and second ends of the side plates140may be coupled to the second end plate52. At least two side plates140may be disposed in parallel and spaced apart by a predetermined interval. The side plates140that are aligned in multi rows, i.e., in parallel, may bind the first and second end plates51and52by double coupling so that expansion of the battery row15that is interposed between the first and second end plates51and52may be inhibited. Thus, deterioration of electrical characteristics of the battery caused by volume expansion of the battery units10may be efficiently inhibited.

The side plates140may have first ends thereof coupled to the first end plate51and second ends thereof coupled to the second end plate52and may have a strip shape. Work hardening units WH that are bent into a roll shape may be formed at the second ends of the side plates140. The protruding work hardening units WH may contact the coupling members45; and coupling strength between the work hardening units WH and the coupling members45may increase since the work hardening units WH and the coupling members45are hooked together. The work hardening units WH may be formed by bending the second ends of the side plates140and overlapping the bent portions onto the side plates140. The bent work hardening units WH may have high mechanical rigidity. Thus, coupling strength thereof to the side plates140may be improved.

FIG. 7illustrates a perspective view of a battery module according to yet another embodiment.FIG. 8illustrates the battery module ofFIG. 7from an end plate side. Referring toFIGS. 7 and 8, the first and second end plates51and52may be disposed at the outermost layers of the battery units10arranged in a row15. Then, the first and second end plates51and52and the battery row15may be bound by a side plate240that surround them. The second end plate52may have a left flange unit64L and a right flange unit64R at side ends thereof. For example, one end of the side plate240may be coupled to the left flange unit64L of the second end plate52; and another end of the side plate240may be coupled to the right flange unit64R of the second end plate52. The side plate240may extend from the one end that is coupled to the left flange unit64L of the second end plate52toward the first end plate51, may surround the first end plate51, may extend toward the second end plate52, and may be coupled to the right flange unit64R of the second end plate52.

Here, a work hardening unit WH that is bent into a roll shape may be formed at the end of the side plate240that is coupled with the right flange unit64R. The protruding work hardening unit WH may contact one coupling member45that fixes the side plate240; and the coupling strength of the side plate240may increase since the work hardening unit WH and the coupling member45are hooked each other.

Since the first and second end plates51and52and the battery row15may be coupled using the single side plate240in a single process, the number of parts and processes required to assemble the parts may be advantageously reduced.

According to the embodiments, when a plurality of batteries are coupled to each other to form a single battery module, portions providing binding or coupling forces may be bent and cured by a work hardening process to improve the coupling strength. Thus, mechanical rigidity of the entire battery module may be improved. Furthermore, since the batteries aligned in a row may be bound with a strong coupling force, volume expansion of the batteries may be inhibited and electrical characteristics may not be deteriorated.

In particular, in a battery pack including a plurality of secondary batteries, if each battery slightly expands, an entire volume of the battery pack may increase by about 5 to 10%. The battery pack of an embodiment may prevent serious deformation thereof; and electrical resistance of unit batteries may thereby be prevented from increasing. Thus, electrical characteristics of the battery pack may be maintained.