Laminate strengthened battery pack and method of manufacturing the same

A battery pack and a method of manufacturing the same. The battery pack includes: a package member formed of a laminate strengthened sheet; and a support plate coupled to at least a portion of the package member to form a case having a space for receiving an electrode assembly. The manufacturing method of the battery pack includes: forming an electrode assembly; forming a case for receiving the electrode assembly by coupling a solid support plate to at least a portion of a package member formed of a laminate strengthened sheet; inserting the electrode assembly into the case; and electrically connecting the electrode assembly to a terminal assembly.

CROSS-REFERENCE TO RELATED PATENT APPLICATION

This application claims priority to and the benefit of Korean Patent Application No. 10-2009-0009451, filed on Feb. 5, 2009, in the Korean Intellectual Property Office, the entire content of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a battery pack and a method of manufacturing the same, and more particularly, to a battery pack including a battery case configured to realize an increased battery capacity and an improved strength against external impact, and a method of manufacturing the same.

2. Description of the Related Art

There is a need for a portable electronic apparatus that is capable of performing various functions and be used for a long time. As such, due to their higher battery capacities, lithium secondary batteries have now been utilized as power sources for portable electronic apparatuses.

In secondary batteries, a battery case can be in the form of a metal can. Alternatively, in lithium polymer secondary batteries, a multi-layered pouch-shaped structure composed of an aluminum (Al) foil and a polymer film can be utilized as a battery case.

In order to increase the battery capacities of lithium secondary batteries, high capacity negative and/or positive electrode materials and/or thinner battery cases have been utilized. For example, when using a metal can as a battery case, the use of a thinner metal enables an increased amount of an electrode active material, thereby achieving higher capacity and higher charge/discharge efficiency of batteries. However, there is a limit in how much the thickness of the metal can be reduced. On the other hand, when using a multi-layered pouch-shaped structure as a battery case, it is possible to reduce the thickness of the battery case to a desired level and to achieve a significantly reduced battery weight as compared with the use of a metal can, but there arises a problem of insufficient strength against external impact.

Also, in the fabrication of a typical secondary battery, there is a need to separately perform a process of manufacturing a battery cell and a process of assembling the battery cell and a protection circuit into a pack, which makes the entire battery fabrication process complicated and time consuming.

SUMMARY OF THE INVENTION

An aspect of an embodiment of the present invention is directed toward a battery pack capable of increasing battery capacity and improving strength against external impact.

An aspect of an embodiment of the present invention is directed toward a method of manufacturing a battery pack, in which a battery cell fabrication process and a battery pack fabrication process are integrated (unified) and simplified, thereby resulting in improved battery productivity.

According to an embodiment of the present invention, a battery pack is provided to include: an electrode assembly; a terminal assembly electrically connected to the electrode assembly and for supplying current to an external circuit; a package member formed of a laminate strengthened sheet; and a support plate coupled to at least a portion of the package member to form a case having a space for receiving the electrode assembly.

The laminate strengthened sheet may have a folded rectangular (or square) shape.

Two opposite ends of the laminate strengthened sheet may be attached to each other.

The support plate may form a bottom surface or two opposite sides of the case. Alternatively, the support plate may form a bottom surface and two opposite sides of the case.

The support plate may be made of polypropylene (PP).

The laminate strengthened sheet of the package member may include: a blocking layer; an outer layer on a first surface of the blocking layer; and an inner layer on a second surface of the blocking layer opposite to the first surface of the blocking layer.

The package member may have a thickness between about 170 and about 300 μm.

The blocking layer may have a thickness between about 20 to about 150 μm, the outer layer may have a thickness between about 5 and about 30 μm, and the inner layer may have a thickness between about 30 and about 150 μm.

The blocking layer may be made of a metal selected from the group consisting of iron (Fe), nickel (Ni), aluminum (Al), and combinations thereof.

The outer layer may be made of a material selected from the group consisting of nylon, polyethyleneterephthalate (PET), and combinations thereof.

The inner layer may be made of cast polypropylene (CPP).

The terminal assembly may include: a cap plate having a first terminal through-hole for receiving an electrode terminal; a top case coupled to the cap plate and having a second terminal through-hole for receiving an external terminal for supplying current from the electrode terminal to an external circuit; and a protection circuit board in the top case and including the external terminal electrically connected to the electrode terminal passing through the cap plate via the first terminal through-hole and for controlling charge-discharge cycling of the battery pack.

The terminal assembly may further include a secondary protection device between the cap plate and the protection circuit board.

According to another embodiment of the present invention, there is provided a method of manufacturing a battery pack, the method including: forming an electrode assembly; forming a case for receiving the electrode assembly by coupling a solid support plate to at least a portion of a package member formed of a laminate strengthened sheet; inserting the electrode assembly into the case; and electrically connecting the electrode assembly to a terminal assembly.

The method may further include injecting an electrolyte solution into the case via an electrolyte solution injection hole formed in the case, after the electrically connecting of the electrode assembly to the terminal assembly. The method may further include sealing the electrolyte solution injection hole, after the injecting of the electrolyte solution into the case.

The method may further include injecting an electrolyte solution into the case, before the electrically connecting of the electrode assembly to the terminal assembly.

In one embodiment, during the electrically connecting of the electrode assembly to the terminal assembly, the terminal assembly may be coupled to a portion of the package member by thermal fusion or high frequency heating.

DETAILED DESCRIPTION

In the following detailed description, only certain exemplary embodiments of the present invention are shown and described, by way of illustration. As those skilled in the art would recognize, the invention may be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Also, in the context of the present application, when an element is referred to as being “on” another element, it can be directly on the another element or be indirectly on the another element with one or more intervening elements interposed therebetween. Like reference numerals designate like elements throughout the specification.

FIG. 1is a perspective schematic view of a battery pack according to an embodiment of the present invention,FIG. 2is a vertical sectional schematic view of the battery pack ofFIG. 1,FIG. 3is an exploded perspective schematic view of the battery pack ofFIG. 1, andFIG. 4is an enlarged schematic view of a portion IV ofFIG. 3.

Referring toFIGS. 1 through 4, a battery pack100according to an embodiment of the present invention includes an electrode assembly110; a package member120; a support plate130coupled to at least a portion (e.g., a bottom portion inFIG. 1) of the package member120to form a case for receiving the electrode assembly110; and a terminal assembly140coupled to a portion (e.g., a top portion inFIG. 1) of the package member120.

The electrode assembly110may be formed by winding a positive electrode plate111, a negative electrode plate112, and a separator113interposed therebetween into a jelly roll-type structure (or substantially into a jelly roll-type structure). A positive electrode tab114is coupled to the positive electrode plate111, and a negative electrode tab115is coupled to the negative electrode plate112.

The package member120may be formed of a rectangular sheet120cwith an upper end120a, a lower end120b, and two opposite sides120dand120e. When the two opposite sides120dand120eof the sheet are attached, the sheet is formed into a tube (e.g., an elliptical tube) with open upper and lower ends.

The package member120may have a thickness between about 170 and about 300 μm. In one embodiment, if the thickness of the package member120is less than 170 μm, it may not have sufficient strength against external impact. In another embodiment, if the thickness of the package member120is greater than 300 μM, it may not improve battery capacity as compared with a metal can-type package member.

The package member120is composed of a laminate strengthened sheet (high strength laminate sheet) that includes (or is composed of) a blocking layer121; an outer layer122disposed on a first surface of the blocking layer121; and an inner layer123disposed on a second surface of the blocking layer121opposite to the first surface of the blocking layer121.

In one embodiment, the blocking layer121is formed of a metal material. In one embodiment, the metal material includes a metal selected from the group consisting of iron (Fe), nickel (Ni), aluminum (Al), and combinations thereof. Such a metal material has a strong mechanical strength and a good corrosion resistance, thereby leading to improved mechanical strength of the package member120and good corrosion resistance against an electrolyte solution. The use of such a metal material also reduces or prevents moisture penetration into the electrode assembly110of the battery pack100. The metal material may have a percent elongation (percent elongation at fracture) of between about 20 and 60%. The thickness of the blocking layer121may be between 20 and 150 μm.

The outer layer122constitutes an outer surface of the package member120. In this regard, the outer layer122may be made of a material having good tensile strength, impact strength, and durability, e.g. nylon and/or polyethyleneterephthalate (PET). The outer layer122may be laminated on the outer surface of the blocking layer121by heat treatment at high temperature. The thickness of the outer layer122may be between about 5 and 30 μm.

PET may be used in the form of an alloy film. PET may not contain an adhesive. In this case, a PET film is attached to a surface of the blocking layer121by utilizing an adhesive between the PET film and the blocking layer121(e.g., an adhesive applied to the surface of the blocking layer121).

The inner layer123may be made of cast polypropylene (CPP). CPP may be coated to a thickness between about 30 and 150 μm on the inner surface of the blocking layer121.

The support plate130may be an elliptical or rectangular plate. The support plate130may be made of polypropylene (PP).

The support plate130may be coupled to the bottom end120bof the package member120. When the support plate130is the elliptical or rectangular plate, the package member120may be formed to have a parallelepiped shape (e.g., a rectangular parallelepiped shape) due to coupling between it and the support plate130.

The terminal assembly140includes a cap plate141; a protection circuit board142; a secondary protection device143disposed between the cap plate141and the protection circuit board142; and a top case144receiving the cap plate141, the protection circuit board142, and the secondary protection device143.

The cap plate141may be coupled to the top end120aof the package member120. A negative terminal145electrically connected to the negative electrode tab115of the electrode assembly110is disposed to pass through a center portion of the cap plate141. The cap plate141may be made of an aluminum material and is electrically connected to the positive electrode tab114of the electrode assembly110.

The protection circuit board142includes an external terminal146that is electrically connected to the negative terminal145and supplies current to an external circuit; and an electrical circuit device controlling the charge/discharge cycling of the battery pack100. The protection circuit board142is fixedly installed between the cap plate141and the top case144.

The top case144may be coupled to a top portion of the cap plate141. A terminal through-hole147through which the external terminal146of the protection circuit board142is exposed is formed in the top case144.

A procedure of assembling the above-described constitutional elements into the battery pack100will now be described.

First, the bottom end120bof the package member120is coupled to a top end of the support plate130. Here, the bottom end120bof the package member120may be thermally fused to the top end of the support plate130. The support plate130may be made of polypropylene, and the inner layer123of the package member120may be made of polypropylene or cast polypropylene (CPP), leading to good adhesion between the package member120and the support plate130.

As such, when the bottom end120bof the package member120is thermally fused to the top end of the support plate130, a bottom of a case formed by thermal fusion between the package member120and the support plate130is sealed with the support plate130, and a top thereof is open. Here, when the support plate130is an elliptical or rectangular plate the package member120can maintain a parallelepiped or rectangular parallelepiped shape due to the coupling between it and the support plate130.

Next, the electrode assembly110is inserted into the case formed by the package member120and the support plate130via the top end120a. In this state, the terminal assembly140is coupled to the package member120. In more detail, the top end120aof the package member120may be thermally fused to the terminal assembly140. That is, the top end120aof the package member120may be thermally fused to a side portion of the cap plate141of the terminal assembly140. The top end120aof the package member120may also be coupled to the cap plate141of the terminal assembly140by high frequency heating.

After coupling the package member120to the terminal assembly140, an electrolyte solution is injected. That is, an electrolyte solution is injected into an electrolyte solution injection hole124formed in an upper side of the package member120. Then, the electrolyte solution injection hole124is sealed with a sealing member125. This completes the battery pack100.

Hereinafter, battery packs according to other embodiments of the present invention will be described.

Battery packs as will be described hereinafter are substantially the same as the battery pack100according to the above-described embodiment of the present invention except for a coupling structure between a package member and a support plate, and thus, a detailed description about elements other than a package member and a support plate will not be provided again.

FIG. 5illustrates a battery pack200according to another embodiment of the present invention, the battery pack200is substantially the same as the battery pack100of the previous embodiment in that a support plate230is disposed below a package member220, but the package member220is coupled to the support plate230to wholly surround side surface(s) (e.g., four side surfaces) of the support plate230.

That is, in the battery pack100of the previous embodiment, the package member120is coupled to a portion (e.g., the top end120ainFIG. 1) of the support plate130so that the side surface(s) of the support plate130is exposed to the outside. By contrast, according to the current embodiment of the present invention, the package member220is coupled to the support plate230to wholly surround the side surface(s) of the support plate230so that the support plate230is not exposed to the outside. As such, since the package member220wholly surrounds the side surface(s) of the support plate230, an adhesion area between the package member220and the support plate230is increased, thereby leading to improved adhesion strength.

As described above, according to the battery pack200of the current embodiment of the present invention, the package member220is coupled to the support plate230to form a case, and the bottom of the case is sealed with the support plate230. When the support plate230has substantially a rectangular plate shape as shown inFIG. 5the package member220can stably maintain substantially a rectangular parallelepiped shape due to the coupling between it and the support plate230.

FIG. 6illustrates a battery pack300according to another embodiment of the present invention.

Referring toFIG. 6, the battery pack300is structured such that a package member320is coupled to support plates332and334to form a case, and the support plates332and334form two opposite sides of the case.

Under such a structure, a top of the case has an opening336. An electrode assembly (e.g., the electrode assembly110ofFIG. 2) is inserted into the case via the opening336.

In this state, a terminal assembly (e.g., the terminal assembly140ofFIG. 2) is inserted into the opening336and is electrically connected to the electrode assembly.

As described above, according to the battery pack300of the current embodiment of the present invention, the package member320is coupled to the support plates332and334to form the case for receiving the electrode assembly110, and the support plates332and334form two opposite sides of the case. When the support plates332and334have a rectangular plate shape as shown inFIG. 6after coupling the terminal assembly (e.g., the terminal assembly140) to the package member320, the package member320can stably maintain a rectangular parallelepiped shape due to the coupling between it and the support plates332and334.

FIG. 7illustrates a battery pack400according to another embodiment of the present invention.

Referring toFIG. 7, the battery pack400is structured such that a package member420is coupled to support plates432,434and436to form a case, and the support plates432,434and436form a bottom surface and two opposite sides of the case.

The support plates432,434and436may be formed integrally. Alternatively, the support plates432,434and436may be separately formed and coupled to the package member420.

Under such a structure, an opening438is formed at a top of the case. An electrode assembly (e.g., the electrode assembly110ofFIG. 2) is inserted into the case via the opening438. In this state, a terminal assembly (e.g., the terminal assembly140ofFIG. 2) is inserted into the opening438and is electrically connected to the electrode assembly.

According to the battery pack400having the above-described structure, the package member420is coupled to the support plates432,434and436to form the case for receiving the electrode assembly (e.g., the electrode assembly110), and the support plates432,434and436form a bottom surface and two opposite sides of the case. When the support plates432,434and436have a rectangular plate shape as shown inFIG. 7after coupling the terminal assembly (e.g., the terminal assembly140) to the package member420, the package member420can stably maintain a rectangular parallelepiped shape due to the coupling between it and the support plates432,434and436.

Such combination of the package member420with the support plates432,434and436produces a structure very similar to a polygonal (e.g., four-sided) can.

Hereinafter, a method of manufacturing a battery pack according to embodiments of the present invention will be described in more detail.

That is, a method of manufacturing a battery pack according to an embodiment of the present invention will now be described with reference toFIG. 8.

As shown inFIG. 8, the method of manufacturing the battery pack includes forming an electrode assembly (S10); forming a case for receiving the electrode assembly by coupling a solid support plate to at least a portion of a laminate strengthened sheet type package member (S20); inserting the electrode assembly into the case (S30); electrically connecting the electrode assembly to a terminal assembly (S40); and injecting an electrolyte solution into the case (S50).

Referring toFIG. 8, together withFIGS. 1 through 4, in the formation of the electrode assembly (S10), a positive electrode plate111, a negative electrode plate112, and a separator113interposed therebetween are wound into a jelly roll-type structure, a positive electrode tab114is coupled to the positive electrode plate111, and a negative electrode tab115is coupled to the negative electrode plate112to thereby complete an electrode assembly110.

In the formation of the case (S20), a support plate130is coupled to at least a portion (e.g., a bottom end120binFIG. 1) of a package member120formed of a laminate strengthened sheet to thereby form a case. Here, the coupling between the package member120and the support plate130may be performed by heat treatment. Alternatively, the package member120may also be coupled to the support plate130by high frequency heating.

Then, the electrode assembly110is inserted into the case (S30) and is then electrically connected to a terminal assembly140(S40). Here, the terminal assembly140may be thermally fused to a top end120a(inFIG. 1) of the package member120. The terminal assembly140may also be coupled to the top end120aof the package member120by high frequency heating.

In the injection of the electrolyte solution into the case (S50), an electrolyte solution is injected into the case via an electrolyte solution injection hole124formed in an upper side of the package member120. Then, the electrolyte solution injection hole124is sealed with a sealing member125(S60). This completes the fabrication of a battery pack100.

A method of manufacturing a battery pack according to another embodiment of the present invention will now be described with reference toFIG. 9.

As shown inFIG. 9, the method of manufacturing the battery pack includes forming an electrode assembly (S10); forming a case for receiving the electrode assembly by coupling a solid support plate to at least a portion of a laminate strengthened sheet type package member (S20); inserting the electrode assembly into the case (S30); injecting an electrolyte solution into the case (S70); and electrically connecting the electrode assembly to a terminal assembly (S80).

The battery pack manufacturing method of the current embodiment of the present invention is substantially the same as that of the previous embodiment in terms of steps S10through S30.

Referring toFIG. 9, together withFIGS. 1 through 4, according to the current embodiment of the present invention, after inserting an electrode assembly110into a case formed by a package member120and a support plate130(S30), an electrolyte solution is injected into the case (S70).

After injecting the electrolyte solution into the case, a terminal assembly140is electrically connected to the package member120(S80). Here, a cap plate141of the terminal assembly140may be coupled to a top end120aof the package member120to thereby complete the battery pack100. Therefore, according to the battery pack manufacturing method of the current embodiment of the present invention, it is not necessary to form an electrolyte solution injection hole in the package member120.

As should be apparent from the above description, a battery pack (or battery) of an embodiment of the present invention is composed of a laminate strengthened sheet that is utilized as a package member (that is coupled to a support member to form a battery case). Here, since the battery pack (or battery) is composed of the laminate strengthened sheet that is utilized to form the package member, and the battery case is formed by coupling the support plate to at least a portion of the package member, the battery pack has an increased battery capacity as compared with a can type battery, and an increased strength as compared with a pouch type battery. Therefore, in embodiments of the present invention, a battery pack (or battery) with an increased battery capacity can be realized as compared with a can type battery, and a battery pack (or battery) with an increased strength can be realized as compared with a pouch type battery.

Furthermore, in an embodiment of the present invention, an electrode assembly is surrounded by a laminate strengthened sheet type package member, and it is electrically connected to a terminal assembly supplying current to an external circuit. Therefore, a battery cell fabrication process and a battery pack fabrication process are integrated and simplified, thereby resulting in improved battery productivity.