JP3260323B2 - Sheet type electrochemical element and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet-type electrochemical element such as a sheet-type battery, an electric double-layer capacitor, and the like, and a method of manufacturing the same. The present invention relates to a chemical element and a method for manufacturing the same.

[0002]

2. Description of the Related Art In recent years, secondary batteries using a carbon material, tin oxide, silicon oxide or the like as a negative electrode active material called a lithium ion secondary battery have been studied for use in various electronic products and electric vehicles. I have. These lithium ion secondary batteries use a so-called electrolytic solution in which an electrolyte salt is dissolved in a liquid solvent. Batteries using an electrolytic solution have the advantage of low internal resistance, but, on the other hand, have the problem of liability to leak and ignition. To address such problems, for example, a gel polymer solid electrolyte comprising a polymer, an electrolyte salt and a solvent has recently been spotlighted. Some of these gel-like polymer solid electrolytes have a conductivity close to that of a liquid and exhibit a value on the order of 10 ⁻³ S · cm ⁻¹ .

A battery using a solid polymer electrolyte does not leak because it does not use a liquid electrolyte. Therefore,
Unlike a conventional battery using a liquid electrolyte, it is not necessary to mechanically caulk with a metal container and a polymer packing therebetween. The polymer solid electrolyte battery can prevent liquid leakage by using a laminate film composed of a polymer film and a metal foil as an exterior (container).

[0004]

However, depending on the type of the polymer forming the laminate film as the exterior, the adhesion between the external connection terminal connected to the battery electrode and the laminate film is insufficient and the external The connection terminals were not fixed properly.

Although a laminated film can be used as an exterior in an electric double layer capacitor or the like using a solid polymer electrolyte, the same problem occurs.

The present inventors have studied various polymers in order to improve the above-mentioned drawbacks. As a result, the present inventors have examined various types of polymers, and found that sheet-type electrochemical devices such as batteries and electric double-layer capacitors using this kind of polymer solid electrolyte. The sheet-type electrochemical element using an external connection terminal coated with an acid-modified polyolefin is a sheet-type electrochemical element whose inner surface is a polyolefin, which can be used as an exterior body of the laminate film. It has been found that the fixing strength of the external connection terminal is sufficiently large because of its excellent performance.

Japanese Patent Application Laid-Open No. Hei 8-287889 proposes a two-layer resin film in addition to a laminate film as an exterior body, but does not improve the fixing strength of external connection terminals. .

SUMMARY OF THE INVENTION In view of the foregoing, it is an object of the present invention to provide a sheet-type electrochemical element in which the strength of fixing an external connection terminal to an exterior body and a method of manufacturing the same are provided.

Other objects and novel features of the present invention will be clarified in embodiments described later.

[0010]

In order to achieve the above object, a sheet-type electrochemical element of the present invention has an electrode / electrolyte structure in which electrodes are disposed on both sides of a solid polymer electrolyte and is sealed in an outer package. In the configuration, the inner surface of the exterior body is polyolefin, the external connection terminal connected to the positive electrode of the electrodes is aluminum , and the external connection terminal is connected to the negative electrode of the electrodes.
To an external connection terminal is nickel are, each external connection
Through-holes only in the sealing portion of the terminal for
Is formed so as not to contact the edge of the terminal, it is interposed an acid-modified polyolefin to the sealing portion by the outer body of both sides of each external connection terminal, the outer in the sealing portion
It is characterized in that the body surface and each external connection terminal are thermally fused .

[0011]

The method of manufacturing a sheet-type electrochemical device according to the present invention is characterized in that an external connection terminal of aluminum is welded to a positive electrode of the electrodes of the electrode / electrolyte structure having electrodes disposed on both sides of a polymer solid electrolyte ; To the nickel external connection terminal
Welded and sealed with an exterior body as terminals for each external connection
Only the through hole was formed so as not to contact the edge of the terminal
Using things, is interposed an acid-modified polyolefin to the sealing portion by the outer body of the both surfaces of the external connection terminals, the electrode-electrolyte structure, with inner surfaces are sealed in the outer package of polyolefins, said outer package The surface and each external connection terminal are heat-sealed.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a sheet-type electrochemical device and a method for manufacturing the same according to the present invention will be described below with reference to the drawings.

[0014] Figure 1 in FIG. 5 will be described an embodiment of the present invention. FIG. 1 is an enlarged cross-sectional view of a main part of a sheet-type lithium ion secondary battery as an electrochemical element, and FIG. 2 is a front cross-sectional view of the entire configuration of the sheet-type lithium ion secondary battery. It is one. FIG. 3 is a plan view of the same, and FIG. 4 is a plan view of a current collector. In these figures, 1 is a positive electrode,
Reference numeral 2 denotes a negative electrode, 3 denotes a separator of a polymer solid electrolyte interposed between the positive and negative electrodes, and a positive electrode 1 is provided with an aluminum current collector 4 and a negative electrode 2 is provided with a copper current collector 5 laminated and integrated. , And the battery body 10 (electrode / electrolyte structure). As shown in FIG. 4, the current collectors 4, 5 have tongue pieces 4a, 5a for connecting the external connection terminals 7, 8, to which the external connection terminals 7, 8 are respectively welded. The current collector 4 and the external connection terminal 7 to be welded to the same are made of the same metal material (or a material that is easily welded). Similarly, the current collector 5 and the external connection terminal 8 are made of the same metal material (or welded). It is preferable that the material is easy to use. The external connection terminal 7,
8 has a small through hole 11 only in the sealing portion by the exterior body 6.
Are provided in large numbers. As shown in FIG.
The external connection terminals 7 and 8 are formed so as not to contact the edges of the terminals.
ing.

The outer package (sealed container) 6 is a laminated bag of a metal foil 6a such as an aluminum foil, a polyolefin (polypropylene or the like) film 6b inside the metal foil 6a and an insulating film 6c such as a polyamide or polyester outside the metal foil. The inner surface is a polyolefin film 6b.
Further, an acid-modified polyolefin (such as acid-modified polypropylene) 9 is applied to portions of the external connection terminals 7 and 8 which are sealed by the outer package 6 on both surfaces. Then, the battery element body 10 to which the external connection terminals 7 and 8 are welded is housed in the exterior body 6 of a laminate bag having polyolefin as an inner surface,
The opening (the hatched portion in FIG. 3) of the exterior body 6 is sealed (heat-sealed) by heating and pressurizing the opening (the hatched portion in FIG. 3) with the distal ends of the external connection terminals 7 and 8 drawn out.

An acid-modified polypropylene, which is one type of the acid-modified polyolefin, is sold by Mitsui Chemicals, Inc. under the trade name “UNISTOL (liquid polyolefin adhesive)”. The acid-modified polyolefin has a carboxyl group in the molecule and therefore has good adhesion to metals (aluminum, copper, iron, stainless steel, etc.), polyolefins, and the like. Also, the heat resistance is excellent. The application of the acid-modified polyolefin 9 to the external connection terminals 7 and 8 is performed by spraying a dispersion in which the acid-modified polyolefin is dispersed in toluene or the like to a necessary portion of the terminal (a portion sealed with an exterior body) by spraying or the like. I just need.

According to this embodiment, the inner surface of the outer package 6 is made of polyolefin, and the acid-modified polyolefin 9 is arranged between the polyolefin and the external connection terminals 7 and 8, so that the outer package 6 is Because of the excellent adhesion to the terminals 7 and 8, the terminals 7 and 8 can be sufficiently fixed for practical use, and the tensile strength can be improved. Further, through holes 1 are provided in some of the external connection terminals 7 and 8.
1 is provided, and the exterior body 6 is
By using a configuration in which the connection terminals 7 and 8 are thermally fused,
Polyolefin on the inner surface of the exterior is entrapped into the through hole 11
In addition, the fixing strength of the external connection terminals 7 and 8 is improved.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to a case where a sheet type lithium ion secondary battery is constructed.

Reference Example 1 As an acid-modified polypropylene which is a kind of acid-modified polyolefin, “UNISTOL R-200” manufactured by Mitsui Chemicals, Inc.
Was used. Unistor R-200 is a dispersion in which acid-modified polypropylene fine particles are dispersed in toluene. Unistor R-200 is about 4mm in width and about 40 in length
mm, 0.1mm thick aluminum foil and nickel foil,
It was applied by spray. After coating, 10
Put in for a minute and adhere. These foils are the external connection terminals 7,
It becomes 8. However, in this reference example 1, the external connection was made as shown in FIG.
The connection terminals 7 and 8 are not provided with through holes.

The electrode 1 was prepared by a doctor blade method in which the positive electrode 1 was composed of an active material LiCoO ₂ , a conductive auxiliary carbon black (HS-100, manufactured by Denki Kagaku Kogyo), and a binder PVDF (polyvinylidene fluoride). . The negative electrode 2 was made of a material composed of active material mesocarbon microbeads (MCMB), a conductive aid HS-100, and a binder PVDF by a doctor blade method. The separator 3 is PVDF,
An article made of SiO ₂ was prepared by a doctor blade method. The positive electrode and the negative electrode were cut into a rectangular shape having a width of 31 mm and a length of 41 mm. The separator was cut into a rectangular shape having a width of 33 mm and a length of 43 mm. The current collectors 4 and 5 (the composition of ethylene acrylic acid copolymer and carbon black are applied to expanded metal made of aluminum and copper) have a rectangular shape having a width of 29 mm and a length of 39 mm as shown in FIG. The terminal connection portion was cut while leaving a tongue piece having a width of 7 mm and a length of 8 mm.

The fabrication of the battery body 10 was performed as follows.
First, the positive electrode 1 and the separator 3 were laminated and laminated by hot pressing. Laminating condition is 130 ° C, pressure 3kgcm
^The pressure was increased by ^-2 for 2 minutes. A negative electrode was laminated thereon and laminated similarly. A current collector 4 made of aluminum was laminated on the positive electrode and similarly laminated. The negative electrode 2 was similarly laminated with a copper current collector 5.

An aluminum terminal 7 was welded to the aluminum current collector 4 of the battery body 10 and a nickel terminal 8 was welded to the copper current collector 5. This was immersed for 1 hour in 330 ml of an electrolytic solution obtained by dissolving 1 M of LiPF _{6 in} a mixed solvent of EC (ethylene carbonate) and DMC (dimethyl carbonate) at a volume ratio of 1: 2. After taking out the battery body from the electrolyte, the electrolyte adhering to the electrode surface was wiped off. This battery element absorbed the electrolytic solution and became a gel state. The battery body is formed of an exterior body 6 made of polypropylene on the inner surface.
(Laminate bag of aluminum foil, polypropylene film and polyethylene terephthalate), and the opening was heat-sealed (heat-sealed) to produce a sheet-type lithium ion secondary battery. The battery of Reference Example 1 using a terminal obtained by applying acid-modified polypropylene to the external connection terminals 7 and 8 as the acid-modified polyolefin 9 has excellent tensile strength of the external connection terminals 7 and 8 as shown in Table 1 below. I was

Table 1 Sample Terminal Tensile Strength (kgf) Reference Example 1 Aluminum 3.1 〃 3.2 〃 3.0 ニ ッ ケ ル Nickel 13.0 〃 11.5 〃 10.2 Example 1 Aluminum 3. 5 〃 〃 4.0 ４ 〃 4.5 ニ ッ ケ ル Nickel 14.0 〃 １４ 14.5 〃． 15.0 Comparative Example 1 Aluminum 1.3 〃 1.7 〃 1.0 〃 Nickel 1.4 2.3 〃 1.7

[Example 1 ] Except for using external connection terminals 7, 8 having a large number of small through-holes 11 only in a sealing portion by an exterior body as shown in FIGS. 1 and 5 , A sheet-type lithium ion secondary battery was manufactured in the same manner as in Reference Example 1 . The same reference numerals are given to the same or corresponding parts as in Reference Example 1 . The battery of Example 1 had excellent tensile strength as shown in Table 1 above. The reason is that when the exterior body 6 and the external connection terminals 7 and 8 are thermally fused, the through hole 1
This is probably because the polypropylene on the inner surface of the exterior penetrated into 1.

Comparative Example 1 A sheet-type lithium ion secondary battery was manufactured in the same manner as in Reference Example 1, except that an external connection terminal not coated with an acid-modified polyolefin was used. As shown in Table 1, the battery of Comparative Example 1 was inferior in tensile strength to Reference Example 1 and Example 1 .

In the above-described embodiments and examples, the case where the battery is formed as the electrode / electrolyte structure is exemplified. However, the present invention can be applied to a sheet type electrochemical element such as an electric double layer capacitor. . In an electric double layer capacitor, a polarizable electrode using activated carbon or the like as an active material may be used instead of the positive electrode and the negative electrode.

The acid-modified polyolefin is available from Chuo Rika Kogyo Co., Ltd. under the trade name "Aquatex" and Sumitomo Seika Co., Ltd. in addition to the trade name "UNISTOL" from Mitsui Chemicals, Inc.
Some are sold as liquid polyolefin-based adhesives under the trade names “Seporjon”, “Siixen”, and “CSM latex”, and these can also be used.

Although the embodiments of the present invention have been described above, it is obvious to those skilled in the art that the present invention is not limited to the embodiments and various modifications and changes can be made within the scope of the claims. There will be.

[0029]

As described above, according to the present invention,
By coating the external connection terminal with an acid-modified polyolefin such that the inner surface of the outer package is polyolefin and the acid-modified polyolefin is interposed between the polyolefin and the external connection terminal, the outer package and the external connection terminal Can be improved, and the fixing strength of the external connection terminal can be improved, and the fixing of the external connection terminal is sufficiently strong for practical use.

Further, if a through hole is provided in a part of the external connection terminal, and the exterior body and the external connection terminal are heat-sealed at the part of the through hole, the exterior body is provided in the through hole. The polyolefin on the surface is engaged, and the fixing strength of the external connection terminal is improved.

[Brief description of the drawings]

FIG. 1 is an essential part enlarged sectional view showing a case where a sheet-type lithium ion secondary battery is configured according to an embodiment (Example 1) of the present invention.

FIG. 2 is a front sectional view showing the entire configuration of the embodiment (Example 1).

FIG. 3 is a plan view of the same.

FIG. 4 is a plan view showing a current collector used in the embodiment (Example 1).

FIG. 5 is a plan view of an external connection terminal used in the embodiment (Example 1).

FIG. 6 is an enlarged sectional view of a main part of Reference Example 1.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Positive electrode 2 Negative electrode 3 Separator 4,5 Current collector 6 Outer case 7,8 External connection terminal 9 Acid-modified polyolefin 10 Battery element 11 Through hole

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Katsuo Naoi 1-1-13 Nihonbashi, Chuo-ku, Tokyo Inside TDK Corporation (56) References JP-A-11-307066 (JP, A) JP-A-11 -67166 (JP, A) JP-A-10-289698 (JP, A) JP-A-9-288998 (JP, A) JP-A-9-270250 (JP, A) JP-A-9-265974 (JP, A) JP-A-9-283101 (JP, A) JP-A-9-293499 (JP, A) JP-A-10-302756 (JP, A) JP-A-11-204090 (JP, A) JP-A-11- 297332 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) H01M 2/06 H01G 9/016 H01G 9/10 H01M 2/02 H01M 10/40

Claims (2)

(57) [Claims] 1. A sheet type electrochemical device of the solid polymer electrolyte on both sides in the electrode-electrolyte arranged an electrode structure formed by sealing the outer package, the inner surface of the outer body is a polyolefin, said electrodes
The external connection terminal connected to the positive electrode is aluminum , and the external connection terminal connected to the negative electrode of the electrodes
Is nickel , and the outer body of each external connection terminal
Make sure that the through hole does not touch the edge of the terminal
It is formed in, and the acid-modified polyolefin is interposed in the sealing portion by the exterior body on both surfaces of each external connection terminal ,
In the sealed portion, the exterior body surface and each external connection end
A sheet-type electrochemical element characterized in that the element is thermally fused. 2. The electrode of the electrode / electrolyte structure having electrodes disposed on both sides of a polymer solid electrolyte, an external connection terminal of aluminum is welded to a positive electrode, and an external connection terminal of nickel is formed to a negative electrode.
Connection terminals are welded, and the external
Make sure that the through hole does not contact the edge of the terminal
Used after formed, by interposing acid-modified polyolefin to the sealing portion by the <br/> exterior of both sides of each external connection terminal, the electrode-electrolyte structure, the inner surface of the outer package of the polyolefin A method for manufacturing a sheet-type electrochemical element, wherein the sealing is performed and the inner surface of the exterior body and each external connection terminal are heat-sealed.