JP2003223872A - Resin coating method for lithium ion secondary battery and the battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin coating method for lithium secondary batteries, which can provide a speedy, stable coating on the exterior of a battery and also provide the battery. <P>SOLUTION: The positive pole side of a lithium ion secondary battery body 2 is covered with an insulative top cover member 4. A shrinkage film 1 drawn in a tube-like shape is cut in a prescribed length and the lithium ion secondary battery body 2 is put into the cut shrink film 1, and further the cut shrink film 1 is closed in a sack-like shape at the edge of the negative pole side of the battery, or is formed in a belt-like shape, and then the exterior of the lithium ion secondary battery body 2 including its insulative top member 4 is fitted with the cut shrink film 1 by shrinking it by heat. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for coating a main body of a lithium ion secondary battery with a tubular heat-shrinkable synthetic resin and the battery.

[0002]

2. Description of the Related Art Conventionally, the exterior of a battery is hermetically covered with a case-like body such as aluminum or plastic, or is injection-molded with a thermoplastic resin to be packaged. It has been known. It is also known that a heat-shrinkable tube made of polyvinyl chloride is used as a heat-shrinkable synthetic resin for coating a battery. Further, use of a stretched tube made of a mixture containing an olefin-based ionomer resin as a main component is also disclosed.

[0003]

However, in the prior art, in particular, the outer packaging by coating the electronic parts by using the tube,
Regarding the specific coating method which has been disclosed,
Many unresolved points are not mentioned. In reality, when applied to batteries, it has problems such as properties and stability of raw materials, costs and environmental aspects as waste, or technically problematic problems, and is not always an efficient method. Not necessarily. Generally, it is often covered by a mold method. The present invention has been made based on such a technical background, and particularly improves a method of inserting a lithium ion secondary battery main body into a tubular heat-shrinkable synthetic resin,
It achieves the following objectives.

An object of the present invention is to use a synthetic resin of a tubular shrink film which has a wide shrinking temperature and is designed to prevent electrification, and which is a resin for a lithium-ion secondary battery which enables quick and stable coating. It is to provide a coating technology and its battery. Another object of the present invention is to provide a resin coating technology for a lithium-ion secondary battery, which has a reduced cost, is easy to mass-produce, and is highly efficient, and the battery.

[0005]

[Means for Solving the Problems] To solve the above problems, the following means are adopted. The resin coating method of the lithium ion secondary battery of the present invention is a method of coating the outer peripheral surface of the lithium ion secondary battery main body with a stretched heat-shrinkable synthetic resin, wherein the electrode portion of the lithium ion secondary battery main body is A step of covering with an insulating lid member, a step of cutting the heat-shrinkable synthetic resin formed into a tube into a predetermined size, and a step of inserting the lithium ion secondary battery main body into the heat-shrinkable synthetic resin, The heat-shrinkable synthetic resin covers the outer peripheral surface of the lithium ion secondary battery body including the insulating lid member by heat shrink-bonding.

Before the covering step, there may be provided a step of closing the end portion of the heat-shrinkable synthetic resin on the tip end side of the negative electrode of the lithium ion secondary battery body into a bag shape. By closing the bag when the heat-shrinkable synthetic resin is cut, it is possible to achieve stability during insertion.

Further, the cutting step may be a step of cutting the heat-shrinkable synthetic resin including the length covering the side surface of the insulating lid member. It is possible to protect the lithium ion secondary battery by insulatingly covering all but the terminal portion.

Further, the cutting step may be a step of cutting the heat-shrinkable synthetic resin including the length covering the surface of the insulating lid member. Similarly to the above, it is possible to protect the lithium ion secondary battery by insulatingly covering all but the terminal portion. Further, the electrode part in the step of covering with the insulating lid member may be a positive electrode part.
Further, the electrode part in the step of covering with the insulating positive lid member may be a positive electrode part and a negative electrode part.

The resin-coated lithium-ion secondary battery is a battery coated with a heat-shrinkable synthetic resin in which the outer peripheral surface of the main body of the lithium-ion secondary battery is stretched, and the main body of the lithium-ion secondary battery and the lithium-ion secondary battery. An insulating lid member that covers the electrode portion of the secondary battery body, and a heat-shrinkable synthetic resin that covers the outer peripheral surface of the lithium ion secondary battery body and that is covered by heat-shrinking adhesion including the insulating lid member. There is. By using a heat-shrinkable synthetic resin for the exterior, a battery with a thin exterior coating can be obtained. The insulating lid member that covers the electrode portion may be a member that covers the positive electrode terminal or the negative electrode terminal. Since the end portions are opened, the heat-shrinkable synthetic resin can be heat-shrinked in a strip shape.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. FIG. 1 is an external view of a tubular shrink film 1 (heat-shrinkable synthetic resin) that is a covering material to which the present invention is applied. The shrink film 1 is a tube-shaped film, and has a structure having a space 1a inside when it is unfolded, and normally has a structure 1b in which two sheets are rolled into a roll shape as shown in the figure. ing. When it is used, the end portion is expanded and an electronic component or the like is inserted into the internal space 1a. In mass production, a plurality of electronic components may be inserted in the shrink film 1. Depending on the production form, it may be single insertion or multiple insertion.

The shrink film 1 is generally used for packaging and binding products. For example, it is used in various fields such as transportation packaging and packaging of industrial materials, and has a proven record. The shrink film 1 is a heat-shrinkable film, which is a kind of synthetic resin, and has the following features. It has a wide shrinking temperature, is easy to seal, is not affected by the shape and size of the packaged item, can be packaged in multiple packages, and is easy to use.

It has good heat resistance, has a large shrinkage force, and can shrink even at a relatively low temperature. There is no puncture when contracted, and the binding force is great. Strong and hard to tear. Since it is transparent and has good gloss, the appearance of the package can be kept beautiful. Since it is harmless and odorless and contains no harmful additives, it does not generate harmful substances even if it is burned, and can be safely used for packaging foods and medicines.

Therefore, environmental protection is not impaired. The shrinkage ratio has a wide range, and for example, a shrinkage ratio of 30 to 60% at 120 ° C. is commercially available. In addition to having such characteristics,
The shrink film 1 is a low cost as a heat shrinkable resin material. There are different types of shrink film 1 depending on the application, but those applied to the present invention are those that are antistatic and are suitable for electronic parts.

FIG. 2 shows a state in which the main body 2 of the lithium ion secondary battery, which is the target coating, is inserted into the shrink film 1. The lithium ion secondary battery is a battery that can be repeatedly charged, and has recently been used as a battery for mobile phones, digital cameras and the like. It is characterized by high energy density, light weight and compact size, high operating voltage, and high safety.

The principle of this lithium ion secondary battery is
A current is caused to flow by moving the lithium ions to the negative electrode during charging and moving them to the positive electrode during discharging. The basic structure of the lithium-ion secondary battery main body 2 is a three-layer structure in which a sheet-shaped positive electrode plate and a negative electrode plate are provided and a resin-based separator is sandwiched therebetween. Cobalt acid lithium or the like is used for the positive electrode, and graphite or the like is used for the negative electrode.

The resin-based separator is, for example, a polymer porous film. These are housed in the metal case 3, covered with a lid, filled with an electrolytic solution, and sealed by laser welding or the like. In a general prismatic structure, a positive electrode terminal 2a is provided on the upper portion of the lithium ion secondary battery main body 2, and the metal case 3 serves as a negative electrode terminal 2b. This negative terminal 2
b may be provided as a terminal in the lower part of the metal case 3 or may be provided in parallel on the positive electrode side, depending on the form.

In the embodiment, the lithium ion secondary battery main body 2 has a structure in which the negative electrode terminal 2e on the negative electrode side is provided on the positive electrode side via the lead wire 2d. Between the lead wire 2d and the negative electrode terminal 2e on the negative electrode side, the protection circuit 2f is insulated from the main body.
Is provided. Further, the safety valve 2 is provided on the upper side of the positive electrode terminal 2a.
c is provided, and if the pressure inside the battery rises, the gas inside the battery is released to the outside to ensure safety.

The lid 4 has a box-like shape with a peripheral edge, and has holes 4a formed in portions corresponding to the positive electrodes 2a and 2e and the safety valve 2c so that these terminal portions are exposed to the outside. It has become. Instead of the hole 4a, a contact may be provided at the terminal portion so as to make contact with the terminal portion of the lithium ion secondary battery main body 2. The lid 4 itself is insulative and has a thin shape such as thin plastic or paper. The lid 4 is attached to the body 2 of the lithium-ion secondary battery so as to cover it as shown by the arrow in FIG. The state of FIG. 2 shows a process of a method of covering the metal case 3 which is the negative electrode of the lithium ion secondary battery main body 2 with the shrink film 1.

After the lid 4 is attached to the lithium ion secondary battery main body 2, the metal case 3 side of the lithium ion secondary battery main body 2 is inserted into the tubular shrink film 1 in which the ends are opened. . At this time, the insertion end 1c of the shrink film 1 (tip on the negative electrode side of the lithium ion secondary battery) is heated and melted by a heater and closed so as to be integrated.

The closing timing may be after the main body 2 of the lithium ion secondary battery is inserted into the shrink film 1, and the main body 2 of the lithium ion secondary battery 2 is inserted after the insertion end 1c of the shrink film is closed first. Good. At this time, the shrink film 1 is cut into a predetermined size. When a plurality of lithium ion secondary battery bodies 2 are inserted into the shrink film 1 and cut,
You will be disconnecting multiple items at the same time. In this case as well, the cutting is performed in a state of being set to a predetermined size, and the cutting is performed according to the production form.

Thus, by closing the insertion end 1c in a bag shape, the lower part of the shrink film 1 is sealed, and in this state, at least the part other than the positive electrode side is covered.
Further, the dimensional control up to the upper end can be performed accurately based on this closed portion, and a stable covered state can be maintained. The end portion of the shrink film 1 is dimensioned so as to cover the lid 4. Therefore, the insertion width is adjusted so as to cover up to the intermediate width portion of the lid 4 on the positive electrode side of the lithium ion secondary battery main body 2. After the shrink film 1 is completely covered with the main body 2 of the lithium ion secondary battery, the shrink film 1 is heated and shrunk by a heater such as a halogen lamp.

As described above, the shrink film 1 has a shrinkage rate of, for example, 30 to 60% at 120 ° C., so that it shrinks immediately when heated and sticks and adheres to the surface of the lithium ion secondary battery main body 2. To be done. This bonded state is completed as the resin-coated lithium-ion secondary battery A covered with the shrink film 1 in FIG. The covered portion of the shrink film 1 is the range of B in FIG. Since this method is not complicated, the actual production process can be easily automated by mass production.

Although not shown, the air trapped in the shrink film 1 when contracting is smoothly discharged to the outside during the contracting process. Since the shrink film 1 is transparent, by attaching a label on which the design and description are printed in advance to the main body 2 of the lithium ion secondary battery, the shrink film 1 can be inserted as it is in the flow work, cut, and the bag closed. It is efficient to repeat the procedure. Since the shrink film 1 is thin, the thickness is not felt even if the resin-coated lithium-ion secondary battery A coated is held by hand. As described above, as compared with the case where the metal case 3 that forms the outer shape of the body of the lithium ion secondary battery is provided with an exterior such as a plastic mold, the exterior of the shrink film 1 is the product of the resin-coated lithium ion secondary battery A. Can be thinned. Further, the cost related to the exterior can be reduced.

FIG. 4 shows another embodiment.
In this case, the plate-shaped lid 5 is attached to the lithium ion secondary battery main body 2, and then the lithium ion secondary battery main body 2 is inserted into the tubular shrink film 1 shown in FIG. In this embodiment as well, since the negative electrode terminal 2e is provided in parallel with the positive electrode side as described above, the plate-like lid 5 is covered including these. The plate-like lid 5 is provided with holes 5a for terminals and safety valves as described above. At the time of insertion, the shrink film 1 insertion end 1c on the negative electrode side is closed like a bag in the same manner as described above.

After the insertion, the shrink film 1 is heated to shrink and adhere, and the resin-coated lithium-ion secondary battery A covered with the shrink film 1 is completed as shown in FIG. The positive electrode-side end 1d of the shrink film 1 to be covered projects onto the surface 5b of the plate-like lid 5, and the lithium ion secondary battery main body 2 and the plate-like lid 5 are sandwiched and bonded.

FIG. 6 shows a lithium ion secondary battery main body 2
Similarly to the positive electrode side, the negative electrode side of 6 has an insulating cover 6 as shown by the arrow.
It is an example of a method of covering with. In this case, the shrink film 1 is covered with the main body 2 of the lithium-ion secondary battery in a stripped state while the tube is cut without closing the bag, and heat-shrinked to cover it. The basic method is the same as in the case of FIG.
6 will be used, but the feature is that the handling of the shrink film 1 is simplified. In this case, since the negative electrode side is not closed, the negative electrode side terminal can be installed on the negative electrode side. The resin-coated lithium-ion secondary battery A as a product has a form shown in FIG. Other than electrodes,
It is in a state of being completely covered, including the lid portion.

FIG. 8 shows an example of a method in which the plate-like lid 7 similar to the case of FIG. 4 is applied to the negative electrode side as shown by the arrow. In this case as well, the shrink film 1 is covered in a stripped state while the tube is cut, and is heat-shrinked to cover the shrink film 1 without closing the bag. The shrink film 1 is projected and adhered to the surfaces of the two plate-shaped lids 5 and 7 to cover them. The resin-coated lithium-ion secondary battery A as a product has a form shown in FIG. It is the same as the above description that all the parts except the electrodes are covered, including the lid.

The coating method using the shrink film 1 for coating the lithium ion secondary battery main body 2 and the structure thereof have been described above. However, since this coating method can be applied to various product forms, it is not limited to the configuration described. It goes without saying that the present invention is not limited to the examples.

[0029]

As described above in detail, the insulative lid member is attached to the body of the lithium ion secondary battery, and the end portion is closed in a bag shape or is covered in a band state so as to cover the tubular shrink film. Since the coating method and the battery configuration thereof have been adopted, the exterior of the lithium-ion secondary battery can be coated in a thin and sealed manner and the weight can be reduced. In addition, the shrink link is a material that is easily available and low cost can be realized.
Furthermore, the coating method of the present invention is a simple method and is suitable for mass production.

[Brief description of drawings]

FIG. 1 is an external view showing a tubular shrink film.

FIG. 2 is an external view showing a process of attaching a box-shaped lid member to a lithium ion secondary battery main body and covering the shrink film.

FIG. 3 is an external view showing a state in which a shrink film is heat-shrink-bonded and coated on the body of the lithium-ion secondary battery in FIG.

FIG. 4 is an external view showing a process in which a plate-like lid member is attached to the body of the lithium-ion secondary battery and the shrink film is covered.

5 is an external view showing a state in which a shrink film is heat-shrink-bonded and covered on the body of the lithium-ion secondary battery in FIG.

FIG. 6 is an external view showing a process of attaching a box-shaped lid to the positive electrode side and the negative electrode side of the main body of the lithium ion secondary battery and covering the shrink film.

7 is an external view of a resin-coated lithium-ion secondary battery coated with a shrink film in the process of FIG.

FIG. 8 is an external view showing a process in which plate-like lids are attached to the positive electrode side and the negative electrode side of the main body of the lithium-ion secondary battery to cover the shrink film.

9 is an external view of a resin-coated lithium-ion secondary battery coated with a shrink film in the process of FIG.

[Explanation of symbols]

1 ... Shrink film 1c ... Insertion end 2 ... Lithium ion secondary battery body 3 ... Metal case 4, 6 ... Lid 5, 7 ... Plate-shaped lid

Claims (8)

[Claims] 1. A method of coating an outer peripheral surface of a lithium ion secondary battery body with a stretched heat-shrinkable synthetic resin, the method comprising: covering an electrode portion of the lithium ion secondary battery body with an insulating lid member; Cutting the heat-shrinkable synthetic resin formed into a tubular shape to a predetermined size; inserting the lithium ion secondary battery main body into the heat-shrinkable synthetic resin; A method for coating a resin of a lithium-ion secondary battery, which comprises a step of heat-shrink-bonding and covering the outer peripheral surface of the body of the lithium-ion secondary battery including a flexible lid member. 2. The heat-shrinkable synthetic resin end portion on the negative electrode tip end side of the lithium ion secondary battery main body before the coating step in the resin coating method for a lithium ion secondary battery according to claim 1. A method for coating a resin for a lithium-ion secondary battery, which comprises the step of closing the bag in a bag shape. 3. The resin coating method for a lithium ion secondary battery according to claim 1, wherein the cutting step includes cutting a heat-shrinkable synthetic resin including a length for covering a side surface of the insulating lid member. A resin coating method for a lithium-ion secondary battery, which is characterized by being a step. 4. The resin coating method for a lithium ion secondary battery according to claim 1, wherein the cutting step includes cutting the heat-shrinkable synthetic resin including the length covering the surface of the insulating lid member. A resin coating method for a lithium-ion secondary battery, which is characterized by being a step. 5. The resin for a lithium-ion secondary battery according to claim 1, wherein the electrode portion in the step of covering with the insulating positive lid member is a positive electrode portion in the resin coating method for a lithium-ion secondary battery according to claim 1. Coating method. 6. The resin coating method for a lithium ion secondary battery according to claim 5, wherein the electrode portion in the step of covering with the insulating positive lid member includes a negative electrode portion. Resin coating method. 7. A battery covered with a heat-shrinkable synthetic resin in which an outer peripheral surface of a lithium ion secondary battery main body is stretched, wherein the lithium ion secondary battery main body and an electrode portion of the lithium ion secondary battery main body are provided. A resin-coated lithium-ion secondary battery comprising an insulating lid member for covering and a heat-shrinkable synthetic resin covering the outer peripheral surface of the body of the lithium ion secondary battery and including the insulating lid member and covered by heat-shrinking adhesion. 8. The resin-covered lithium-ion secondary battery according to claim 7, wherein the insulating lid member that covers the electrode portion comprises:
A resin-coated lithium-ion secondary battery, which is a member that covers the positive electrode terminal or the negative electrode terminal.