Battery pack

A battery pack is disclosed. An embodiment of the battery pack includes a bare cell, wherein the bare cell comprises a terminal; a circuit module coupled with the bare cell, wherein the circuit module comprises a protective device; and a cover disposed over the circuit module and coupled with the bare cell; wherein the circuit module comprises a through-hole, the cover comprises a protrusion, the protrusion engages with the through-hole, and the through-hole enables welding of the protective device of the circuit module to the terminal of the bare cell through the through-hole.

BACKGROUND

The present disclosure relates to a battery pack, and more particularly, to a battery pack including a battery and a circuit.

2. Description of the Related Technology

As the technology of mobile devices, such as cellular phones and notebook computers, has become remarkably developed and production thereof has increased, the demand for secondary batteries as an energy source for mobile devices has rapidly increased. Recently, much research into secondary batteries as an alternative energy resource for fossil fuel used in electric vehicles and hybrid electric vehicles has been conducted.

In general, such secondary batteries are used in the form of a battery pack integrated with a circuit for controlling charging and discharging operations. In order to secure stability of secondary batteries including flammable materials, the battery pack typically has a circuit for controlling abnormal operating environment of overcharging, over-discharging, over-current, or the like. The circuit mounted on a battery typically has an upper cover. Conventional battery packs do not include an assembling structure for aligning the upper cover at the right position on the battery and assembling the upper cover with the battery, and consequently, time loss increases during the assembly of the upper cover, and defects caused by misalignment also increase.

SUMMARY

According to an embodiment, a battery pack comprises a bare cell, wherein the bare cell comprises a terminal; a circuit module coupled with the bare cell, wherein the circuit module comprises a protective device; and a cover disposed over the circuit module and coupled with the bare cell; wherein the circuit module comprises a through-hole, the cover comprises a protrusion, the protrusion engages with the through-hole, and the through-hole enables welding of the protective device of the circuit module to the terminal of the bare cell through the through-hole.

According to another embodiment, a battery pack comprises a bare cell, wherein the bare cell comprises a terminal; a circuit module coupled with the bare cell; a cover disposed over the circuit module and coupled with the bare cell; and a protrusion extending from the cover, wherein the protrusion comprises two ribs in a cross structure; wherein the circuit module comprises a through-hole and the protrusion engages with the through-hole.

According to another embodiment, a battery pack comprises a bare cell, wherein the bare cell comprises a terminal; a circuit module coupled with the bare cell; a cover disposed over the circuit module and coupled with the bare cell; and a protrusion extending from the cover; wherein the circuit module comprises a through-hole and the protrusion engages with the through-hole; and wherein the protrusion and the through-hole have the same shape and substantially the same dimensions.

DETAILED DESCRIPTION

Hereinafter, embodiments of the present invention will now be described more fully with reference to the accompanying drawings.

FIGS. 1 to 3illustrate exploded perspective views of a battery pack according to an embodiment of the present invention. The battery pack includes a bare cell100including an element generating electric power, a protective circuit module (PCM)150mounted on the bare cell100and controlling a charging and discharging operation, and an upper cover160connected to the bare cell100to accommodate the PCM150.

The bare cell100may be a rechargeable secondary battery, e.g., a lithium-ion battery, in which an electrode assembly10including a cathode plate11, an anode plate13, and a separator15is impregnated in an electrolyte (not shown) and sealed in a can20. For example, the bare cell100can include an electrode assembly10including a stack of a cathode plate11, an anode plate13, and a separator15wound into a jelly-roll, a can20having an opening at the upper end to accommodate the electrode assembly10and the electrolyte, and a cap assembly30sealing the opening of the upper end of the can20. The upper end of the can20may be closed by the cap assembly30after the electrode assembly10is accommodated therein. The cap assembly30and the can20may be airtight-coupled by welding the contact portion thereof using a laser beam.

For example, the cathode tap17of the electrode assembly10may be connected to the cap assembly30itself, and the anode tap19may be connected to a first terminal31extending from the upper surface of the cap assembly30. The first terminal31may be bound to the cap assembly30while insulated from the cap assembly30and extend from the upper surface of the cap assembly30to electrically connect the bare cell100and the PCM150.

A safety vent35may be designed to break to provide a path of a gas when an internal pressure of the can20is greater than a predetermined level. Such a safety vent may be disposed at one side of the cap assembly30. Meanwhile, an insulating label sheet180coated with an adhesive may be attached to the outer surface of the bare cell100. An adhesive agent171such as a double-coated tape may be attached to the bottom surface of the bare cell100to connect the bare cell100with a lower cover170.

According to an embodiment, PCM150controls the charging and discharging operation of the bare cell100and performs a protective operation to protect the operation of the bare cell100. The PCM150may include a protective circuit board140, a positive temperature coefficient (PTC) protective device120, and first and second connecting members131and132.

According to embodiments, the protective circuit board140and the PTC protective device120prevent overcharge, over-current, over-discharge, etc. The PTC protective device120may form a charging and discharging current path between the protective circuit board140and the bare cell100which will be described later, and force the current to decrease if the charging and discharging current is greater than a predetermined level.

The protective circuit board140may include a wiring pattern to form a charging and discharging current path between an external device and the bare cell100, and may be a printed circuit board (PCB) having a protective circuit limiting the charging and discharging current of the bare cell100. For example, an external connection terminal145for electrical connection with the external device may be disposed at one surface of the protective circuit board140, and first and second electrode pads141and142for electrical connection with the bare cell100may be disposed on the other surface of the protective circuit board140. The external connection terminal145may directly contact the external device to input the charging and discharging current into the bare cell100, or output the charging and discharging current from the bare cell100.

The first electrode pad141may be connected to the first terminal31of the cap assembly30, and the second electrode pad142may be connected to the upper surface of the cap assembly30. The first and second connecting members131and132may be disposed at positions corresponding to the first and second electrode pad141and142to mediate electric connection, and the PTC protective device120may be interposed between the first connecting member131and the first terminal31of the cap assembly30to form the current path therebetween. The first electrode pad141may be connected to the first terminal31of the cap assembly30via the PTC protective device120, and the PTC protective device120may include a lead120aconnected to the first terminal31of the cap assembly30at one end and a lead120bconnected to the first electrode pad141via the first connecting member131at the other end.

The lead120aof the PTC protective device120may be welded to be fixed on the first terminal31of the cap assembly30. For example, a through-hole140′ may be formed nearly at the center of the protective circuit board140, and a welding apparatus W (as shown inFIG. 3), for example, a column-shaped electrode for welding, may be inserted through the through-hole140′ to perform a spot welding that is a resistance welding between the lead120aof the PTC protective device120and the first terminal31. The through-hole140′ may be used to directly weld the PTC protective device120and the first terminal31and provide a path of the welding apparatus W.

Meanwhile, the second electrode pad142of the protective circuit board140may be connected to the upper surface of the cap assembly30via the second connecting member132. For example, the second connecting member132may have stepped upper and lower parts that is twice-bent, wherein the upper part is connected to the second electrode pad142, and the lower part is connected to the cap assembly30. The first and second connecting members131and132may be formed by processing a nickel (Ni) or aluminum (Al) thin film to have a predetermined shape.

An insulation tape111and an insulation spacer112may be interposed between the PCM150and the cap assembly30. The insulation tape111and the insulation spacer112can prevent an electrical short-circuit between the PCM150and the cap assembly30. For example, the insulation tape111may be interposed between the PTC protective device120and the cap assembly30to prevent a short-circuit. The insulation spacer112can support a part of the PCM150so that the PCM150is spaced apart from the cap assembly30by a predetermined distance. The insulation spacer112may support the step difference between the leads120aand120bdisposed at both sides of the PTC protective device120. The PTC protective device120may be disposed on the cap assembly30by interposing the insulation spacer112that supports the stepped structure therebetween. Meanwhile, the insulation tape111and insulation spacer112may have an opening corresponding to the safety vent35so that the safety vent35formed on the cap assembly30is not blocked.

FIG. 4is an exploded perspective view of an assembled upper cover160of the battery pack. Referring toFIG. 4, the upper cover160is assembled onto the bare cell100to accommodate the PCM150mounted on the bare cell100. The upper cover160may have an opening pattern160′ to expose the external connection terminal145of the protective circuit board140and allow the external connection terminal145to be connected to an external device. A double-coated tape (not shown) may be interposed between the upper cover160and the PCM150to mediate to the connection thereof.

The upper cover160may have an accommodation portion160″ having a concave shape to accommodate the PCM150. The upper cover160can include a protrusion165protruding downward to the PCM150to be engaged with an assembly position P of the PCM150. The protrusion165may be engaged with the PCM150integrated with the bare cell100so that the upper cover160and the bare cell100may be positioned. The protrusion165can align the upper cover160with respect to the bare cell100, regulate the assembly position of the upper cover160, and provide the binding force between the upper cover160and the bare cell100. According to the illustrated embodiment, a through-hole140′ is formed at the assembly position P of the PCM150, and the protrusion165is engaged with the through-hole140′. The through-hole140′ may function as a path through which a welding apparatus W (as shown inFIG. 3) passes and an assembly structure with which the protrusion165is engaged. Since the through-hole140′ may be used to be engaged with the protrusion165, a separate structure to be engaged with the protrusion165is not necessary, thereby simplifying the assembly structure.

FIG. 5shows the protrusion165of the upper cover160ofFIG. 4. Referring toFIG. 5, the protrusion165has a cross (+) rib structure including first and second ribs161and162. The first and second ribs161and162may each independently extend in directions of first and second axis Z1and Z2to regulate the assembly position of the upper cover160. That is, the first rib161may function as a hook for the through-hole140′ in the first axis direction Z1to regulate the position of the upper cover160, and the second rib162may function as a hook for the through-hole140′ in the second axis direction Z2to regulate the position of the upper cover160. The first and second ribs161and162may have sizes corresponding to that of the through-hole140′ so as to be engaged in the through-hole140′ of the protective circuit board140. For example, if the through-hole140′ has a rectangular shape with a long side140′aand a short side140′b, the length of the first rib161corresponds to the length of the short side140′bof the through-hole140′, and the length of the second rib162corresponds to the length of the long side140′aof the through-hole140′. The first and second ribs161and162can regulate the assembly position of the upper cover160by the hook for the through-hole140′, thereby preventing the misalignment with the bare cell100.

Since the assembly position of the upper cover160can be easily regulated using the protrusion165in the structure described above, the assembling workability may be improved. Furthermore, time loss caused by displacement may be reduced by fixing the upper cover160at the right position, and defects caused by misalignment may also be reduced.

FIG. 6is an exploded view of a battery pack according to another embodiment of the present invention. Referring toFIG. 6, the battery pack can include a bare cell100, a PCM150mounted on the bare cell100, an upper cover260connected to the bare cell100to accommodate the PCM150. The upper cover260can include a protrusion265protruding downward to the PCM150to be engaged with an assembly position P of the PCM150. The assembly position P of the upper cover260may be determined by the engagement of the protrusion265with the PCM150, and the upper cover260may be fixed at the right position since the protrusion265functions as a hook.

A through-hole140′ may be formed at the assembly position P of the PCM150, and the protrusion265can be engaged with the through-hole140′. The through-hole140′ can function as a path through which a welding apparatus W (FIG. 3) passes and an assembly structure with which the protrusion265is engaged. The protrusion265may have a shape matching with the through-hole140′, for example a rectangular shape.

FIG. 7shows a protrusion265of the upper cover260. The protrusion265may have a rectangular shape with a long side265aand a short side265b. For example, the long side265aof the protrusion265can function as a hook for the through-hole140′ in the second axis direction Z2to regulate the assembly position of the upper cover260. The short side265bof the protrusion265can function as a hook for the through-hole140′ in the first axis direction Z1to regulate the assembly position of the upper cover260. In order to maintain a close contact between the protrusion265and the through-hole140′, tolerance therebetween may be maintained within a predetermined range, thereby efficiently regulating the position of the upper cover260. The protrusion265may have round portions R at corners thereof to reduce unnecessary interference between the protrusion265and the through-hole140′ during the assembly.

The upper cover260may have a binding force sufficient to be integrated with the bare cell100to form the battery pack. For example, the protrusion265may be forced to be engaged with the through-hole140′ to provide a sufficient binding force. If desired, the binding force of the upper cover260may increase using an additional structure. For example, a double-coated tape (not shown) may be interposed between the upper cover260and the PCM150to strongly assemble the upper cover260with the bare cell100.

FIG. 8is an exploded perspective view of a battery pack according to another embodiment of the present invention. Referring toFIG. 8, the battery pack can include a bare cell100, a PCM150mounted on the bare cell100, and an upper cover360connected to the bare cell100so as to accommodate the PCM150. The PCM150may be fixed on the bare cell100using, e.g., spot welding, and the upper cover360may be assembled onto the PCM150. In this regard, the upper cover360can include a protrusion365protruding downward to the PCM150to be engaged with an assembly position P of the PCM150. For example, the assembly position P of the upper cover360may be determined by the engagement of the protrusion365with the PCM150. Due to the tight coupling between the protrusion365and the through-hole140′, the assembly position of the upper cover360can be regulated, and displacement of the upper cover360may be avoided.

A sleeve368extending from the edge of a side of the upper cover360and covering a portion of a side of the bare cell100may be disposed along the edge of the upper cover360. For example, the sleeve368may extend from the long side360aof the upper cover360to cover a portion of a side of the bare cell100. The sleeve368may be used to strongly fix the upper cover360. For example, displacement of the upper cover360may be avoided by the sleeve368that is disposed to cover a portion of a side of the bare cell100and function as a hook. The sleeve368and the protrusion365may be disposed at different positions in the upper cover360to determine the assembly position of the upper cover360and prevent displacement of the upper cover360from the determined assembly position. Meanwhile, although not shown herein, the sleeve368may be formed along the short side360bof the upper cover360, or along the long side360a/short side360b.

Meanwhile, during the last stage of the assembly of the battery pack, the outer surface of the bare cell100may be surrounded by an insulating label sheet180coated with an adhesive. In this regard, the sleeve368may also be surrounded by the insulating label sheet180, and thus the binding force between the upper cover360and the bare cell100may increase by the insulating label sheet180.

FIG. 9is an exploded perspective view of a battery pack according to another embodiment of the present invention. Referring toFIG. 9, the battery pack can include a bare cell200, a PCM150mounted on the bare cell200, and an upper cover160connected to the bare cell200so as to accommodate the PCM150. Here, the upper cover160and the PCM150may be aligned by engaging the protrusion165of the upper cover160into a through-hole140′ of the PCM150.

Meanwhile, a position determining unit200′ or alignment member may be disposed at a contact portion between the PCM150and the bare cell200to align the PCM150and the bare cell200. As shown inFIG. 9, the position determining unit200′ may have a concave shape retracted from the upper surface of the bare cell200. The position determining unit200′ may be formed to match the second connecting member132at a contact position between the position determining unit200′ and the second connecting member132of the PCM150. The displacement of the PCM150may be avoided since the second connecting member132can be inserted into the position determining unit200′, and the assembly may be easily conducted since the PCM150can be fixed before performing an assembling process such as a spot welding. Meanwhile, the position determining unit200′ may also be disposed at the PCM150instead of at the bare cell200. Alternatively, the position determining unit200′ may also be a pair disposed at the both bare cell200and the PCM150and may match each other. Reference numeral230that is not described herein indicates a cap assembly. The position determining unit200′ may also be disposed in the cap assembly230forming the upper part of the bare cell200.

While embodiments of the present invention has been particularly shown and described, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention.