Battery pack

A core pack and a battery pack using the same. A battery pack includes a plurality of bare cells electrically connected to one another. A protection circuit module (PCM) is positioned at an outside of the bare cells and electrically connected to the bare cells. A temperature measurement device is provided with a temperature sensing portion that senses the temperature of the bare cells, a contact portion connected to the PCM, and a connecting portion through which the temperature sensing portion and the contact portion are connected to each other. A case accommodates the bare cells, the PCM and the temperature measurement device. In the battery pack, the temperature sensing portion is positioned in a space formed between outer circumferential surfaces of bare cells disposed in parallel adjacent to each other. Accordingly, it is possible to improve the quality of the battery.

CLAIM OF PRIORITY

This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. §119 from an application earlier filed in the Korean Intellectual Property Office on Mar. 31, 2011 and there duly assigned Serial No. 10-2011-0029663.

BACKGROUND OF THE INVENTION

1. Field of the Invention

An aspect of the present invention relates to a battery pack, and more particularly, to a battery pack capable of improving the quality thereof.

2. Description of the Related Art

With the rapid development of electronic and communication industries, mobile electronic devices have recently come into wide use. Secondary batteries are widely used as power sources for the mobile electronic devices in consideration of economical efficiency. The secondary batteries may also be used not only in cellular phones or notebook computers but also in medium- and large-sized apparatuses such as machine tools, electric bicycles and automobiles, which require high output and high power.

SUMMARY OF THE INVENTION

Embodiments provide an improved battery pack.

Embodiments also provide a battery pack in which a temperature sensing portion is positioned in a space between bare cells, so that it is possible to prevent interference of the temperature sensing portion with a case that accommodates the bare cells.

Embodiments also provide a battery pack in which a temperature measurement device is formed in a film type, so that it is possible to prevent the temperature measurement device from being twisted.

Embodiments also provide a battery pack in which the length of a temperature measurement device is extended, so that it is possible to prevent the temperature measurement device and a protection circuit module from being separated from each other at a soldering part between the temperature measurement device and the protection circuit module.

According to an aspect of the present invention, there is provided a battery pack including a plurality of bare cells electrically connected to one another, a protection circuit module (PCM) positioned at an outside of the bare cells and electrically connected to the bare cells, a temperature measurement device provided with a temperature sensing portion that senses the temperature of the bare cells, a contact portion electrically connected to the PCM, and a connecting portion through which the temperature sensing portion and the contact portion are electrically connected to each other, and a case that accommodates the bare cells, the PCM and the temperature measurement device. The temperature sensing portion is positioned in a space formed between outer circumferential surfaces of bare cells disposed in parallel adjacent to each other.

A heat conducting means may be fixed in a space formed between the temperature sensing portion and the bare cells.

The heat conducting means may include thermal silicon.

A fixing member may be provided above the temperature sensing portion, and both ends of the fixing member may be respectively fixed to the outer circumferential surfaces of the bare cells disposed adjacent to each other.

The fixing member may include an insulating tape.

The connecting portion may be formed in a shape bent along an outer circumferential surface of one of the bare cells.

The temperature sensing portion may be provided in parallel along the length direction of the bare cells.

The temperature measurement device may be formed in an L shape obtained by bending one region thereof.

The temperature measurement device may further include an insulating member that surrounds the temperature sensing portion and the connecting portion.

The temperature measurement device may be formed of a film type.

The contact portion of the temperature measurement device and the PCM may be connected to each other through soldering.

The temperature measurement device may be provided to be spaced apart from the case.

As described above, according to the present invention, the temperature sensing portion of the temperature measurement device is positioned between bare cells, so that it is possible to prevent the interference between the temperature sensing portion and the case, thereby improving the quality of the battery pack.

Also, the temperature measurement device is formed in a film type, so that it is possible to prevent the temperature measurement device from being twisted, thereby improving manufacturing management and workability of the core pack.

Also, the length of the temperature measurement device is extended, so that it is possible to prevent a soldering part between the temperature measurement device and the PCM from being separated from each other, thereby reducing the defect rate of the core pack.

DETAILED DESCRIPTION OF THE INVENTION

The secondary batteries used in the medium- and large-sized apparatuses are formed as a battery pack used as a power source by connecting a plurality of bare cells in series and/or parallel.

The battery pack having the plurality of bare cells further includes various protection devices for the purpose of safety. Among these protection devices, a temperature measurement device measures a temperature of the battery pack and then transfers the temperature to a protection circuit module (PCM). If a predetermined temperature is sensed, the temperature measurement device transfers the sensed temperature to the PCM so that current is cut off. Accordingly, the battery pack does not generate heat or catch fire.

In general, a temperature measurement device for measuring the temperature of a battery pack has one side fixed to a protection circuit module (PCM) through soldering and the other side positioned at a side of bare cells so as to sense the temperature of the battery pack. In this instance, the other side of the temperature measurement device, which senses sense the temperature of the battery pack, may be broken due to its interface with a case that surrounds outer surfaces of bare cells. Since the temperature measurement device is formed in a line shape, its twist may occur. Since the length of the temperature measurement device is short, the one side of the temperature measurement device, soldered to the PCM may be separated from the PCM when an impact is applied to the battery pack.

Therefore, a plan for solving such problems is required in the battery pack. Hereinafter, embodiments of the present invention will be specifically described as the plan for solving the problems with reference to the accompanying drawings.

FIG. 1is an oblique view of a core pack constructed as an embodiment according to the principles of the present invention.

Referring toFIG. 1, core pack100according to the principles of present invention includes a plurality of cylindrical bare cells10, a PCM40and a temperature measurement device30. In core pack100, the plurality of bare cells10electrically connected to one another are electrically connected to PCM40. Temperature measurement device30measures the temperature of bare cells10and transfers the measured temperature to PCM40.

Bare cell10includes an electrode assembly, an electrolyte and a case in which the electrode assembly and the electrolyte are accommodated. Here, the electrode assembly is formed by winding a positive electrode plate, a negative electrode plate and a separator interposed therebetween. Bare cell10supplies electric energy generated by a chemical reaction of the electrode assembly and the electrolyte to the exterior thereof. For example, bare cell10may be a lithium secondary battery.

PCM40may include a printed circuit board (PCB), a protection circuit device, and the like. One or more devices that electrically connect bare cells10to an external electronic device are mounted on the PCB. PCM40is electrically connected to bare cells10by a terminal tab20, and terminal tab20may be formed of nickel, copper or the like.

PCM40may further include a connector41formed at one side thereof. Connector41is a portion fastened to the external electronic device, and the battery pack can be electrically connected to the external electronic device by connector41.

Generally, temperature measurement device30is a semiconductor formed by mixing two or three kinds of oxides and sintering the mixture so as to have a proper specific resistance and a proper temperature coefficient. Here, the two or three oxides include cobalt, copper, manganese, iron, nickel, titanium and the like.

Temperature measurement device30may be divided into a negative temperature coefficient (NTC) and a positive temperature coefficient (PTC). The NTC has a characteristic in which resistance decreases as temperature increases, and the PTC has a characteristic in which resistance increases as temperature decreases. Since a rapid change in resistance is generated by even a minute change in temperature due to a small heat capacity of temperature measurement device30, temperature measurement device30is frequently used as a sensor for temperature control.

Temperature measurement device30according to the principles of the present invention senses the temperature of the plurality of bare cells10and transfers the sensed temperature to PCM40. Temperature measurement device30includes a temperature sensing portion31to sense the temperature of bare cells10, a contact portion33electrically connected to PCM40, and a connecting portion32to electrically connect temperature sensing portion31to contact portion33.

Temperature sensing portion31may be positioned in a space formed by outer circumferential surfaces11of a plurality of bare cells10aand10bdisposed in parallel adjacent to each other. That is, temperature sensing portion31may be positioned near nip13where bare cells10aand10bmeet, at a concave portion12formed between the outer circumferential surfaces of the one bare cell10aand the other bare cell10b.

In this instance, temperature sensing portion31may be provided in parallel along the length direction of bare cell10. For example, temperature measurement device30is formed in an L shape obtained by bending one region thereof, and a portion of temperature measurement device30after temperature measurement device30is extended and then bent from PCM40may be formed as temperature sensing portion31.

Accordingly, temperature sensing portion31of temperature measurement device30is positioned near nip13between the one bare cell10aand the other bare cell10b, so that it is possible to prevent interference with a case50(seeFIG. 5) that surrounds core pack100. Thus, it is hardly likely that temperature sensing portion31will be damaged by case50. When this is applied to mass production, the quality of the battery pack can be improved. Here, contact portion33of temperature measurement device30and PCM40may be connected to each other through soldering.

In temperature measurement device30, temperature sensing portion31that measures the temperature of bare cell10may be connected to contact portion33soldered to PCM40by connecting portion32. Temperature measurement device30may be formed in a film type in which a flat-shaped insulating member34may be further formed on temperature sensing portion31and connecting portion32. Accordingly, temperature measurement device30is adhered closely to bare cell10, and therefore, its twist is prevented. Thus, it is possible to improve the manufacturing management and workability of core pack100.

FIG. 2is a cross sectional view showing a core pack constructed as an embodiment according to the principles of the present invention.

Referring toFIG. 2, a temperature measurement device30constructed as this embodiment includes a contact portion33connected to a PCM40through soldering, and a temperature sensing portion31positioned in a space formed by outer circumferential surfaces of bare cells10aand10bdisposed in parallel adjacent to each other. Temperature measurement device30may further include a connecting portion32through which contact portion33and temperature sensing portion31are connected to each other. In this instance, a film-type insulating member34may be further formed on connecting portion32and temperature sensing portion31, which come in contact with the outer circumferential surfaces of bare cells10aand10b. Insulating member34can prevent a short circuit between temperature measurement device30and bare cells10aand10b.

Connecting portion32is positioned to come in contact with an outer circumferential surface of bare cell10a, and may be formed in a shape bent along the outer circumferential surface of bare cell10a. Accordingly, it is possible to prevent temperature measurement device30from being lifted off from the outer circumferential surface of bare cell10a, and temperature measurement device30can be adhered closely to bare cell10a. Also, temperature sensing portion31is more stably mounted in a space between bare cells10aand10b, so that it is possible to prevent temperature sensing portion31from being separated from the space.

FIG. 3is a cross-sectional view showing a core pack constructed as another embodiment according to the principles of the present invention. InFIG. 3, descriptions of components identical to those described with reference toFIGS. 1 and 2will be omitted.

Referring toFIG. 3, a temperature sensing portion31is positioned in a space formed by outer circumferential surfaces of bare cells10aand10b. Here, the space is a concave portion. A heat conducting means35such as thermal silicon may be formed between temperature sensing portion31and the nip13of bare cells10aand10b. Thus, temperature sensing portion31can be firmly fixed in the space by heat conducting means35.

FIG. 4is an oblique view showing a core pack constructed as still another embodiment according to the principles of the present invention.

Referring toFIG. 4, a temperature measurement device30may be formed in an L shape obtained by bending one region thereof so that a distal portion thereof extends in parallel along the length direction of a bare cell10. Here, a portion after temperature measurement device30is extended and then bent from a PCM40may be formed as a temperature sensing portion31.

In this instance, a heat conducting means35such as thermal silicon is formed between temperature sensing portion31and bare cells10aand10b, and a fixing member36such as an insulating tape may be further formed above temperature sensing portion31. Both ends36aand36bof fixing member36may be respectively fixed to outer circumferential surfaces of bare cells10aand10badjacent to each other. Accordingly, temperature sensing portion31can be more stably and firmly fixed in the space between bare cells10aand10b.

FIG. 5is an oblique view of a battery pack constructed as an embodiment according to the principles of the present invention.FIG. 6is a cross-sectional view of the battery pack taken along line I-I′ ofFIG. 5.

InFIGS. 5 and 6, a battery pack including one of the core packs described inFIGS. 1 to 4and a case50that houses the core pack will be described. However, inFIGS. 5 and 6, the core pack in the interior of case50may be configured in various forms such as those inFIGS. 1 to 4. Here, the cross-sectional view ofFIG. 6shows the cross-sectional view of the embodiment ofFIG. 4.

Referring toFIGS. 5 and 6, a battery pack200according to this embodiment includes a core pack that includes a plurality of bare cells10electrically connected to one another, a PCM40electrically connected to bare cells10, and a temperature measurement device30that senses the temperature of bare cells10and transfers the sensed temperature to PCM40. Battery pack200may further include a case50that houses the core pack.

In temperature measurement device30, a temperature sensing portion31that senses the temperature of bare cells10is positioned in a concave space between a plurality of bare cells10aand10bconnected in parallel to each other. Temperature sensing portion31may be provided in parallel to the plurality bare cells10aand10b. Accordingly, temperature sensing portion31can be spaced apart from inner surface50aof case50.

In this instance, a first adhesive member35and a second adhesive member36may be additionally provided so that temperature sensing portion31is more firmly and stably fixed in the space between bare cells10aand10b.

Temperature measurement device30is generally connected to PCM40, so as to be provided approximately vertically to the length direction of bare cells10. That is, in temperature measurement device30, a contact portion33is vertically connected to PCM40. Temperature measurement device30connected as described above is positioned vertical to the length direction of bare10without bending. A connecting portion32of temperature measurement device30is positioned to come in contact with one region of the outer circumferential surface of bare cells10, and temperature sensing portion31is positioned near the nip between bare cells10aand10b.

In a case where the core pack described above is housed by case50, case50is positioned closely to bare cell10a, and hence it is not sufficient to secure a space in which temperature sensing portion31of temperature measurement device30is to be disposed. Therefore, in a case where an impact is applied to battery pack200, contact portion33may become detached from the PCM40, or there may be caused a defect such as damage to temperature sensing portion31.

As described above, in the present invention, temperature sensing portion31is positioned in the space formed by outer circumferential surfaces of the plurality of cylindrical bare cells10aand10b.

To this end, temperature measurement device30according to the principles of the present invention may be formed to be further extended toward bare cell10from PCM40as compared with a general temperature measurement device. Accordingly, it is possible to prevent a soldering part between temperature measurement device30and PCM40from being separated from each other, and thus it is possible to reduce the defect rate of the battery pack. That is, it is possible to prevent temperature measurement device30and PCM40from being detached from each other at a location that corresponds to where the soldering part is formed between temperature measurement device30and PCM40. Since temperature sensing portion31is stably fixed in the space adjacent to nip13, the inner surface of case50does not interfere with the temperature sensing portion31, and thus the quality of battery pack200can be improved.