KR20060110405A - Improved battery pack - Google Patents

Abstract

Provided is an improved battery pack, which shows excellent force between the constitutional elements, has excellent structural stability against external impact, and avoids a need for a label for preventing the introduction of foreign materials into a site where the constitutional elements are coupled. The improved battery pack(100) comprises: a battery main body(200) in which an electrode assembly including a cathode, an anode and a separator and an electrolyte are contained and sealed; a lower casing(300) having an inner space for housing the battery main body; and an upper casing(400) coupled to the lower casing. In the battery pack, the upper casing and the lower casing each have a sidewall(320,420) with a predetermined thickness so that their coupling portion locates at a lateral side of the battery casing. At least one surface of the top surface of the upper casing and the bottom surface of the lower casing has a film-shaped label.

Description

Improved Battery Pack {Improved Battery Pack}

1 is a perspective view of an external battery pack;

2 is a perspective view of a built-in battery pack according to the prior art including a rectangular battery body;

3 is an exploded perspective view of the battery pack of Figure 2, Figure 4 is a perspective view of a part assembled state;

5 is a perspective view of a built-in battery pack according to the prior art including a pouch-type battery body;

6 is an exploded perspective view of the battery pack of Figure 5, Figure 7 is a perspective view of a part assembled state;

8 is a plan view of a battery pack according to the prior art, and FIG. 9 is a sectional view taken along line A-A;

10 and 11 are partially enlarged views of the portion B before and after ultrasonic welding in FIG. 9;

12 is an exploded perspective view of a battery pack according to one embodiment of the present invention, and FIG. 13 is a perspective view of an assembled state;

14 is a perspective view of a state in which a label is separated from an upper case according to one embodiment in the battery pack of the present invention;

FIG. 15 is a plan view of a battery pack according to an exemplary embodiment of the present invention, FIG. 16 is a cross-sectional view taken along the line C-C, and FIG. 17 is a partially enlarged view of a portion D.

The present invention relates to an improved battery pack, and more particularly, ultrasonic welding is performed on sidewalls of a predetermined thickness extending from upper and lower cases, respectively, and film-like labels are formed on upper and / or lower surfaces of the case. In spite of its very thin thickness, the bonding force by ultrasonic welding is very good, and the structural stability against dropping or external impact is not only excellent, and the interfacial area of the bonding part is large, so that the labeling is enhanced to improve the bonding force and prevent inflow of foreign substances. Provided is a battery pack which can be omitted.

As the development and demand for mobile devices increases, the demand for secondary batteries as energy sources is increasing rapidly. Among them, many researches have been conducted and commercialized and widely used for lithium secondary batteries with high energy density and discharge voltage. It is used.

Lithium secondary batteries are classified into cylindrical batteries, rectangular batteries, and pouch-type batteries according to their appearance, and are classified into lithium ion batteries and lithium ion polymer batteries depending on the type of electrolyte. Due to the recent trend toward the miniaturization of mobile devices, there is an increasing demand for small square and pouch type batteries.

In addition, according to the form in which the secondary battery is mounted in the case, it is generally classified into an external battery pack (hard pack) and an internal battery pack (inner pack). A representative example of an external battery pack is disclosed in FIG. 1. Referring to FIG. 1, the external battery pack 10 forms an external part of the external device 12 to which it is mounted. Although it has an easy advantage, it has a relatively expensive and less compatible problem because the case (housing: 11) must be designed according to the type of the external device in a state where the battery body (not shown) is built.

On the other hand, since the built-in battery pack 20 covers the cover forming a part of the external device while being mounted inside the external device as shown in FIG. 2, the mounting is relatively cumbersome, but the design is difficult. It is easy, inexpensive and has the advantage of compatibility.

More detailed contents of the built-in battery including the rectangular battery body can be found in FIGS. 3 and 4. Referring to these drawings, the built-in battery pack 20 includes, for example, a positive electrode terminal at one side thereof and the other side thereof. A square battery body 21 having a negative terminal formed therein; A PTC element 22 connected to one of the two electrode terminals of the battery body 21 to primarily protect the battery from overcurrent, overdischarge, and overcharge; It is connected to the electrode terminal (one of the positive terminal and the negative terminal) of the PTC element 22 through the nickel plate 23 and the other electrode terminal through the nickel plate 27 to secondaryly protect the battery and to display the corresponding device (shown on the outside). A protection circuit section 24 having an external input / output terminal formed thereon for connection thereto; It consists of an upper case 25 and a lower case 26 surrounding the battery body 21, the PTC element 22, and the protection circuit unit 24.

An insulating sheet 28 is disposed between the side of the battery body 21 and the nickel plate 23, and between the protection circuit part 24 and the nickel plate 27, so that the battery body adjacent to each of the nickel plates 23 and 27 is disposed. Unnecessary contact between 21 or the protection circuit part 24 prevents a short circuit.

In addition, a double-sided tape 29 is disposed between the battery body 21 and the lower case 26 so that the battery body 21 can be fixed to the bottom surface of the lower case 26. Accordingly, when the battery body 21 is accommodated in the upper and lower cases 25 and 26, the battery body 21 can be stably fixed in the upper and lower cases 25 and 26.

After the upper case 25 is coupled to the lower case 26 in which the battery body 21 is stored, in order to further increase the bonding force between the cases 25 and 26 and to prevent foreign substances from entering the coupling part or the inside of the case. The packaging label 30 may also be wrapped.

5 to 7 are a perspective view of a built-in battery pack according to the prior art including a pouch-type battery body, a separate perspective view and a perspective view of the assembly process, respectively.

Referring to these drawings, the battery pack 50 includes a pouch-type battery main body 51 and a battery main body 51 in which the electrode assembly of the positive electrode, the negative electrode, and the separator and the electrolyte are sealed. A lower case 52 having a space and an upper case 53 coupled to the lower case 52 in which the battery body 51 is housed are sealed to the battery body 51. In addition, a double-sided tape 54 is interposed between the battery body 51 and the upper and lower cases 52 and 53 to stably fix the battery body 51 in the spaces inside the cases 52 and 53.

After the upper case 51 is coupled to the lower case 52 in which the battery body 51 is accommodated, the packaging is further packed to increase the bonding force between the cases 51 and 52 and to prevent foreign substances from entering the coupling part or the inside of the case. The process of wrapping the label 40 is the same as in the assembly process of the battery pack 20 of FIGS. 2 to 4.

In the battery pack 20 of FIG. 2 and the battery pack 50 of FIG. 5, the upper case and the lower case are made of a plastic material such as PC and ABS, respectively, and are assembled by mutual bonding by ultrasonic welding. The ultrasonic welding method is, for example, a method in which friction heat is generated by vibration using a high frequency of 20,000 Hz to melt-bond two surfaces to be bonded.

More specific details of coupling the lower case and the upper case by ultrasonic welding may be described with reference to FIGS. 8 to 11. 8 and 9 show a top view with the upper case 60 mounted on the lower case 70 and its vertical cross section (A-A cross section of FIG. 8), respectively. With the upper case 60 mounted on the lower case 70, both end surfaces of the upper case 60 and both ends of the lower case 70 are in contact with each other. An enlarged view of such a contact portion B and a change in ultrasonic welding are shown in Figs. 10 and 11, respectively. As illustrated in FIG. 10, a wedge-shaped welding peak 61 is formed on the lower surface of the upper case 60, and a welding surface that the welding peak 61 is in contact with the corresponding portion of the lower case 70 ( 71) is formed. When high frequency vibration is applied for ultrasonic welding, the contact surfaces of the welding acid 61 and the welding surface 71 are melted, and mutual adhesion is performed.

However, as the overall demand for battery packs of smaller and thinner thickness increases, the thicknesses of the lower case 60 and the upper case 70 become 0.3 to 0.35 mm, respectively, and accordingly, mold processing and injection molding are performed. As the difficulty increases, the welding peak 61 and the welding surface 71 become smaller, resulting in a higher welding failure rate such as weak welding strength.

In addition, since the ultrasonic welding between the upper and lower cases of a thin thickness is relatively inferior in bonding strength, it is possible to secure the bonding force necessary for use as a battery pack and to prevent foreign substances from flowing into the battery pack through the coupling portion or the battery pack. It is required to apply the outer surface of the battery pack with a film-like packaging label.

Accordingly, there is a high demand for a battery pack having a low manufacturing cost since it provides a suitable strength to external impact while using a thin case and a simple manufacturing process.

The present invention aims to solve the problems of the prior art as described above and the technical problems that have been requested from the past.

The present inventors continued an in-depth study of the battery pack structure, when performing ultrasonic welding on the side wall of a predetermined thickness extending from the upper case and the lower case, respectively, and forming a film-like label on the upper and / or lower surface of the case. In spite of its very thin thickness, the bonding force by ultrasonic welding is very good, and the structural stability against dropping or external impact is not only excellent, and the interfacial area of the bonding part is large, so that the labeling is enhanced to improve the bonding force and prevent inflow of foreign substances. It has been confirmed that the present invention can be omitted, and the present invention has been completed.

Therefore, the battery pack according to the present invention for achieving the above object is a rectangular battery body in which the electrode assembly and the electrolyte of the positive electrode, the negative electrode and the separator is embedded in a sealed state, an internal space that can accommodate the battery body A battery pack comprising a lower case having a lower case, and an upper case coupled to a lower case in which the battery body is accommodated to seal the battery body, wherein the upper case and the lower case have a predetermined thickness such that a portion to be coupled to each other is located at the side of the battery body. A film-like label is formed on at least one surface selected from the upper surface of the upper case and the lower surface of the lower case.

Therefore, the battery pack of the present invention can secure an appropriate thickness for ultrasonic welding of the upper and lower cases without increasing its thickness, thereby not only obtaining a high bonding force, but also the interface area of the bonding portion is relatively Since the packaging label does not need to be separately attached to block the inflow of foreign substances, the manufacturing process can be greatly shortened.

In the conventional battery pack, as shown in FIGS. 2 to 7, the upper case of the plate-shaped upper case is coupled to the box-shaped lower case of which the upper part is open, so that the coupling portion between the upper case and the lower case corresponds to the edge of the battery body. . Therefore, the coupling portion between the cases is limited to the end of the upper case of a thin thickness, there was a limit in ensuring the appropriate thickness.

On the other hand, since the side wall is present in each of the upper case and the lower case in the present invention and they are coupled to each other, the coupling portion is located on the side of the battery body. As such, since the coupling portions between the cases are located on the side of the battery body, it is possible to make the thickness of the sidewalls suitable for ultrasonic welding without increasing the overall thickness of the battery pack. The term "predetermined thickness" in the above means a thickness suitable for ultrasonic welding, and does not have a particularly limited size. In addition, since the predetermined thickness increases the interfacial area of the bonding site, it is not necessary to attach a packaging label or the like to the bonding site in order to prevent the inflow of foreign substances.

In one preferred example, the sidewalls of the upper case and the sidewalls of the lower case are approximately equal in length and thickness and may have an overall symmetrical structure. In this case, the coupling part of the upper case and the lower case is located at approximately the center of the side of the battery body, it is possible to secure the optimum thickness for ultrasonic welding.

In another preferred example, a portion (shoulder) where the upper side and the sidewall of the upper case contact each other may have a structure that is gently curved in the shape of a cross section. Such a gentle curved structure is a wide arched structure as a whole, so it is relatively stable even when an external impact is applied to the upper edge or the like. This gentle bending structure can be equally applied to the lower case.

The material of the upper case and the lower case is not particularly limited, and at least the sidewall portion where ultrasonic welding is performed is made of a plastic material such as Polycarbonate (PC) or Polyacrylonitrile-butadiene-styrene (ABS). Therefore, the whole case including the side wall may be made of a plastic material, or may be made of a composite material including a plastic material and a metal material.

When the battery pack falls or an external shock is applied, the external force tends to be concentrated at the coupling portions of the upper and lower cases, causing damage. The upper surface of the battery pack (upper case of the upper case) and the lower surface (lower case of the lower case) are not significantly affected unless a vertical external force is applied, and the possibility of applying such an external external force may take into account the overall effect of the external force on the battery pack. When is relatively low. Therefore, the conventional battery packs of FIGS. 2 to 7 do not guarantee protection against external force applied perpendicularly to the upper and lower surfaces thereof. In consideration of this and the increase in demand for a thin battery pack, it is preferable to manufacture the upper surface of the upper case and the lower surface of the lower case in a relatively thin thickness. However, considering the limitation of injection molding and the formation of a welding acid for ultrasonic welding, the conventional battery pack has a certain limitation.

On the other hand, in the present invention, since the ultrasonic welding is performed on the side wall extending downward from the upper case, the upper surface can solve the latter problem among the limitations of the prior art. Furthermore, in the present invention, in consideration of the former problem, that is, the limitation of injection molding, among the limitations of the prior art, it is made of a structure in which a label on the upper case is formed on the film. The portion where the label is formed may be part or all of the upper surface of the upper case, or may be formed on the lower surface of the lower case. Alternatively, the upper case may be formed on the upper case and the lower case, respectively.

The method of forming a label on the upper or lower surface of the battery pack case may be realized by various methods, for example, in the upper case frame (and / or lower case frame of the lower structure of the open structure) of the upper surface is open. A method of attaching a film label to the open top surface (and / or open bottom surface), a method of inserting a film label into a mold and insert-molding the upper case frame (and / or lower case frame); It is not limited only. Of these, the latter insert injection molding method is particularly preferable.

The material of the film-like label is not particularly limited. For example, a plastic material such as PC or polyethylene terephthalate (PET), a metal material of a thin film, or the like may be used, and a plastic material is particularly preferable. The preferred thickness of the label may be about 0.1 to 0.2 mm, but not limited thereto, in consideration of the thickness of the battery pack and its function as a protective member. However, considering that the limit of thin film injection is generally about 0.2 mm, it should be noted that the present invention enables the manufacture of a battery pack consisting of a case having a top and / or bottom surface having a thickness that cannot be manufactured by thin film injection. .

The battery pack according to the present invention may have a rectangular or pouch type battery body in form, and for example, a lithium ion secondary battery, a lithium ion polymer secondary battery, or the like may be preferably used.

Hereinafter, the present invention will be further described with reference to the drawings according to embodiments of the present invention, but the scope of the present invention is not limited thereto.

12 and 13 illustrate an exploded perspective view before assembly and a combined perspective view after assembly of the battery pack according to the exemplary embodiment of the present invention, respectively.

Referring to these drawings, the battery pack 100 may include a battery body 200 and a lower case 300 accommodating the battery body 200 and the battery body 200 in which the electrode assembly of the positive electrode, the negative electrode, and the separator and the electrolyte are sealed. And an upper case 400 coupled to the lower case 300 to seal the battery body 200.

A protection circuit device such as a protection circuit module (PCM) 210 and a PTC (not shown) is mounted on an upper end of the battery body 200.

The lower case 300 is formed of an inner surface corresponding to an outer surface thereof so that the battery body 200 may be seated thereon, and the external thrust terminals 212 and 214 of the PCM 210 may be exposed at an upper end thereof. Terminal windows 310 and 312 and the like are formed.

The lower case 300 and the upper case 400 has a similar structure as a whole. In detail, film-shaped labels 500 are formed on the lower surface of the lower case 300 and the upper surface of the upper case 400, and sidewalls 320 and 420 are formed on portions corresponding to each other. In addition, shoulders 330 and 430 where the upper or lower surface and the side walls 320 and 420 meet each other form a smooth curved shape in cross section. Accordingly, the lower case 300 and the upper case 400 form an arcuate symmetric structure as a whole and are structurally stable with respect to an applied external force.

FIG. 14 schematically shows the shape of one exemplary upper case in which the label is separated from the battery pack of FIG. 13.

Referring to FIG. 14, the upper case 400 includes a frame 440 having an open top surface, and the label 500 applies the open top surface 442. As described above, the method of forming the label 500 on the open upper surface 442 of the upper case 400 may be various. For example, a predetermined mold (not shown) in which the structure of the upper case 400 is imprinted. And the label 500 may be integrated into insert injection molding for injecting a molten resin.

15 to 17 are plan views, vertical cross-sectional views, and partial cross-sectional views of the battery packs according to the exemplary embodiment of the present invention, respectively.

Referring to FIG. 15, the battery pack 100 has a rectangular structure as a whole and a label 500 is formed on an upper surface thereof.

Referring to FIG. 16, the side wall 320 of the lower case 300 and the side wall 420 of the upper case 400 have a relatively large thickness and a large interface area compared to the battery pack of the prior art. The battery body 200 is protected only by the labels 500 on the upper and lower surfaces of the side walls 320 and 420. Therefore, the thickness of the battery pack 100 has a very thin structure to almost correspond to the thickness of the battery body 200.

Referring to Figure 17, in the battery pack according to the present invention can be seen a change in the side wall interface during ultrasonic welding. A step is formed at an upper end of the lower case sidewall 320, and a welding surface 322 is formed at an inner upper end surface thereof. On the other hand, the lower end of the upper case side wall 420 has a structure corresponding to the upper step of the lower case side wall 320, the welding peak 422 is formed on the inner bottom surface. The change in ultrasonic welding is the same as in FIGS. 10 and 11. As another example, a welding surface may be formed at an upper end of the lower case sidewall 320, and a welding acid may be formed at a lower end of the upper case sidewall 420.

The battery pack according to the present invention can be particularly preferably used in the built-in battery pack.

The foregoing has been described above with reference to some embodiments according to the present invention, but those skilled in the art to which the present invention pertains to various applications and modifications within the scope of the present invention based on the above information. It will be possible.

As described above, the battery pack according to the present invention can be manufactured in a very thin thickness, the bonding force by the ultrasonic welding is very excellent, not only excellent structural stability against falling or external impact, but also the interface of the bonding site Since the enemy is large, it is possible to omit labeling to increase the bonding force and prevent the inflow of foreign substances.

Claims (10)

A rectangular battery body in which the electrode assembly of the positive electrode, the negative electrode, and the separator and the electrolyte are sealed, the lower case having an inner space for accommodating the battery body, and the lower case in which the battery body is housed. The battery pack is composed of an upper case for sealing the battery body, wherein the upper case and the lower case includes a side wall of a predetermined thickness so that the portion to be coupled to each other is located on the side of the battery body, the upper surface of the upper case and the lower surface of the lower case A battery pack, characterized in that the label on the film is formed on at least one surface selected from. The battery pack as claimed in claim 1, wherein the sidewalls of the upper case and the sidewalls of the lower case are substantially the same in length and thickness and have a symmetrical structure as a whole. The battery pack according to claim 1, wherein a portion (shoulder part) where the upper side of the upper case is in contact with the side wall is curved in a curved shape in cross section. The battery pack according to claim 1, wherein a portion (shoulder part) where the upper part and the side wall of the lower case contact each other is curved in a curved shape in cross section. The battery pack according to claim 1, wherein the upper case and the lower case are formed of a plastic material such as polycarbonate (PC), polyacrylonitrile-butadiene-styrene (ABS), and sidewalls in which ultrasonic welding is performed. The battery pack as claimed in claim 1, wherein the portion where the label is formed is part or all of an upper case upper surface or a lower case lower surface. The battery pack as claimed in claim 1, wherein the label is placed in a predetermined mold and the upper case frame or the lower case frame is insert injection molded to manufacture the upper case or the lower case. The battery pack as claimed in claim 1, wherein the label is made of a plastic material such as PC and polyethylene terephthalate (PET). The battery pack as claimed in claim 1, wherein the label has a thickness of 0.1 to 0.2 mm. The battery pack according to claim 1, wherein the battery body is a lithium ion secondary battery or a lithium ion polymer secondary battery.

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