JP2001076706A - Polymer electrolyte battery - Google Patents

Abstract

(57) [Problem] To provide a polymer electrolyte battery having high connection performance between a lead portion of a positive electrode and a positive electrode terminal and having high reliability of battery performance. SOLUTION: A positive electrode having a positive electrode mixture layer formed on at least one surface of an aluminum current collector and a negative electrode having a negative electrode mixture layer formed on at least one surface of a copper current collector are provided. Laminated via a polymer electrolyte, the positive electrode, a negative electrode and a polymer electrolyte battery obtained by sealing an electrode group consisting of the polymer electrolyte with an exterior material, as a positive electrode terminal, a clad material of aluminum and nickel or stainless steel, And, using a clad material having a thickness of at least twice the thickness of the aluminum lead portion of the positive electrode, the aluminum portion at one end of the positive electrode terminal is connected to the lead portion of the positive electrode, and the other of the positive electrode terminal is connected. Is pulled out from the sealing portion of the exterior material to form a polymer electrolyte battery.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polymer electrolyte battery, and more particularly, to a polymer electrolyte battery having an electrode group in which a sheet-shaped positive electrode and a sheet-shaped negative electrode are laminated with a polymer electrolyte interposed therebetween. And a polymer electrolyte battery suitable for use as a power source for portable equipment.

[0002]

2. Description of the Related Art In a polymer electrolyte battery, the electrolyte can be formed into a sheet. By using the sheet electrolyte, a battery having a large area and a thin shape such as an A4 plate or a B5 plate can be manufactured. As a result, application to various thin products has become possible, and the range of use of batteries has been greatly expanded.
Batteries using this polymer electrolyte have excellent safety and storage properties, including leakage resistance, and are thin and flexible, so batteries can be designed according to the shape of equipment. Has features not found in

[0003] This polymer electrolyte battery usually uses a laminate film having an aluminum film as a core material as an outer package, laminates a thin sheet-like electrode and a sheet-like polymer electrolyte layer, and forms the laminate with the above-mentioned laminate film. A thin battery can be completed by sealing with an exterior material.

In this polymer electrolyte battery, in order to make the electrodes thin, a metal foil is usually used as a current collector, an aluminum foil is used as a positive electrode current collector, and a copper is used as a negative electrode current collector. Uses foil. And the external terminals of the battery,
As the positive terminal and the negative terminal used for connection with the battery-powered device, usually, because of the ease of connection with the battery-powered device, etc.
Nickel foil or ribbon is used.

The electrical connection between these electrodes and external terminals is
Usually, on the positive electrode side, an exposed portion of the aluminum foil is left without forming a positive electrode mixture layer on a part of the aluminum foil during the production of the positive electrode, and this is used as a lead portion for connection with the positive electrode terminal. Occasionally, an exposed portion of the copper foil is left without forming a negative electrode mixture layer on a part of the copper foil, and this is used as a lead portion for connection with a negative electrode terminal.

However, the aluminum lead and the copper lead have a low strength due to their small thickness, and also have a problem that the strength of the connection between them and the positive electrode terminal or the negative electrode terminal is low. .

That is, the connection between the positive electrode terminal and the negative electrode terminal is usually performed by resistance welding, ultrasonic welding, or the like. However, since welding is performed between dissimilar metals, their welding strength is low. In particular, welding of aluminum and nickel on the positive electrode side is very difficult, and there is a problem that the welding strength is very low.

Further, when a high voltage or a high capacity is demanded from a battery-using device, this polymer electrolyte battery takes advantage of the feature that the electrodes and the polymer electrolyte can be made into a thin sheet shape while utilizing a plurality of sheet shapes. By stacking a positive electrode and a plurality of sheet-shaped negative electrodes with a polymer electrolyte interposed therebetween to form a multilayer electrode group having a multilayer structure, and connecting these electrodes in series or in parallel,
It has become possible to cope with high voltage or high capacity required by battery-powered equipment.

However, when the above-mentioned multilayer electrode group having a multilayer structure is provided, a plurality of positive electrode aluminum leads and a plurality of negative electrode copper leads constituting the multilayer electrode group are provided. It is necessary to laminate the parts and connect them to the positive terminal and the negative terminal, and there is a problem that the connection becomes more difficult. Especially on the positive electrode side, welding of aluminum and nickel is extremely difficult as described above, In addition to the fact that the electrolyte is interposed between aluminum and nickel, a local battery is formed and corrosion of aluminum occurs when aluminum and nickel are interposed therebetween. However, there is a problem that the thickness of the lead portion may be increased due to a plurality of lead portions, and the connection becomes more difficult.

[0010] Therefore, the laminated body of the lead portion of the positive electrode is connected to one end of an aluminum lead body, and the other end of the lead body is connected to an external terminal at a sealing portion of the exterior material. However, there has been a problem that the number of times of welding increases and the effective internal volume of the battery decreases.

[0011]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems in the prior art, and in particular, increases the connection strength between the positive electrode lead portion and the positive electrode terminal in a polymer electrolyte battery to improve the reliability of battery performance. It is an object of the present invention to provide a polymer electrolyte battery having a high density.

[0012]

SUMMARY OF THE INVENTION The present invention provides a positive electrode comprising a positive electrode mixture layer formed on at least one surface of an aluminum current collector and a negative electrode mixture on at least one surface of a copper current collector. In a polymer electrolyte battery in which a negative electrode formed with a layer is laminated via a polymer electrolyte, and the positive electrode, the negative electrode, and an electrode group composed of the polymer electrolyte are sealed with an exterior material, aluminum and nickel or stainless steel are used as a positive electrode terminal. A clad material with steel, and an aluminum portion at one end of the clad material having a thickness of at least twice the thickness of the aluminum lead portion of the positive electrode is connected to the lead portion of the positive electrode, The object has been achieved by pulling out the other end of the clad material constituting the positive electrode terminal from the sealing portion of the exterior material to the outside.

That is, by adopting the above configuration,
Since the connection between the lead portion of the positive electrode and the positive electrode terminal is made by aluminum between the aluminum lead portion and the aluminum portion of the clad material constituting the positive electrode terminal, the connection strength can be increased and the battery can be dropped. Even if a mechanical force such as vibration is applied, breakage of the connection portion is suppressed, stable battery performance can be obtained, and a polymer electrolyte battery having high reliability in battery performance can be obtained.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, as a current collector of a positive electrode, aluminum foil, punched metal, mesh, expanded metal, and the like can be used. Usually, aluminum foil is used. The current collector of the positive electrode preferably has a thickness of 20 μm or less in view of reducing the thickness of the positive electrode. In the present invention, even if the current collector has such a small thickness, the lead constituted by the exposed portion is used. Since the part does not come out of the battery, there is no possibility of damage. However, if the thickness is too small, wrinkles may occur when the positive electrode mixture-containing paste is applied in producing the positive electrode, or the film may be broken by pulling, so the thickness is 20 μm or less as described above. Is preferably 10 μm or more.
In this specification, the description will be made mainly for the positive electrode, but the concept is the same for the negative electrode.

In the lead portion on the positive electrode side, the exposed portion of the current collector is usually left without forming a positive electrode mixture layer on a part of the current collector made of aluminum when the positive electrode is manufactured, and the lead portion is used as the lead portion. Provided by However, the lead portion is not necessarily required to be integrated with the current collector from the beginning,
The current collector may be provided by connecting an aluminum foil or the like later.

In the present invention, as the positive electrode terminal, one end is connected to the lead of the positive electrode, and the other end is pulled out from the sealing portion of the exterior material to the outside, and the positive terminal is connected to the external terminal. The clad material constituting the positive electrode terminal is a clad material of aluminum and nickel or stainless steel, the thickness of which is twice or more the thickness of the lead portion of the positive electrode. Used.

In the clad material constituting the positive electrode terminal, one component is made of aluminum because the lead portion of the positive electrode is made of aluminum and the other component is made of nickel or stainless steel. This is to facilitate connection with battery-powered equipment.

The clad material constituting the positive electrode terminal is preferably in the form of a foil or a ribbon when used, and has a thickness of 30 to 300 μm, particularly 40 to 150 μm.
m is preferred. That is, the thickness of the clad material is 30
By setting the thickness to at least μm, it is possible to prevent breakage during welding with the lead portion of the positive electrode and to prevent tearing due to pulling and bending. Can be prevented from forming a gap. Further, the clad material is required to have a thickness of at least twice the thickness of the lead portion of the positive electrode. This is to prevent cutting, welding, and bending at the time of welding with the lead portion of the positive electrode as described above. This is to prevent the rupture due to the above.

The clad material may be a clad material in which an aluminum layer and a nickel layer or a stainless steel layer are present entirely, but in the present invention, the clad material is partially formed of an aluminum layer and a nickel layer or a stainless steel layer. Is preferably a so-called partial cladding material in which That is, both the aluminum layer and the nickel layer or the stainless steel layer may be present at the sealing portion of the exterior material that is not affected by the electrolytic solution or outside the battery, but the battery contacting the electrolytic solution may be present. It is preferable that aluminum alone is used inside, that is, inside the sealing portion of the exterior material. At least nickel or stainless steel needs to be present outside the battery, that is, outside the sealed portion of the exterior material.

The connection method between the aluminum part of the clad material and the lead part of the positive electrode includes, for example, resistance welding,
Various connection methods such as ultrasonic welding, laser welding, soldering, caulking, and a method using a conductive adhesive can be adopted, but welding is particularly suitable.

As the current collector of the negative electrode, copper foil, punched metal, net, expanded metal, etc. can be used.
Usually, copper foil is used. As the thickness of the current collector of the negative electrode, for the same reason as in the case of the current collector of the positive electrode,
5 to 20 μm is preferable, and the lead portion on the negative electrode side also has
Usually, it is provided by leaving an exposed portion of the current collector without forming the negative electrode mixture layer on a part of the copper current collector at the time of manufacturing the negative electrode and using the current collector as a lead portion. However, the lead portion on the negative electrode side is not necessarily required to be integrated with the current collector from the beginning, and may be provided by connecting a copper foil or the like to the current collector later.

The lead of the negative electrode is made of copper, and the welding of copper and nickel is not as difficult as the welding of aluminum and nickel in the positive electrode. Although it is also possible to directly connect the terminal, here also a clad material of copper and nickel or stainless steel is used as the negative electrode terminal, and the copper part at one end of the clad material constituting the negative electrode terminal is used as the negative electrode. It is preferable to connect to a copper lead part and to pull out the other end outside the sealing part of the exterior material.

That is, the welding of copper is easier than the welding of copper and nickel, and a higher welding strength is obtained, so that the connection strength between the lead portion of the negative electrode and the external terminal is higher, and the battery performance is higher. , A polymer electrolyte battery having a high density can be obtained.

In the present specification, the term "negative electrode terminal" refers to a terminal having one end connected to a lead portion of the negative electrode and having the end drawn out from the sealing portion of the exterior material. The constituting clad material is also preferably in the form of a foil or a ribbon when used, and has a thickness of 30 to 300 as in the case of the clad material used on the positive electrode side.
μm, particularly preferably 40 to 150 μm. Also, the thickness of the clad material used as the negative electrode terminal is preferably at least twice the thickness of the lead portion of the negative electrode.

As a method for connecting the copper portion of the clad material constituting the negative electrode and the lead portion of the negative electrode, there are various methods such as resistance welding, ultrasonic welding, laser welding, soldering, caulking, and a method using a conductive adhesive. Can be adopted, but welding is particularly suitable.

As the exterior material, for example, a laminated film having a three-layer structure composed of a nylon film or a polyester film-aluminum film-modified polyolefin film is used.
A larger width is advantageous in terms of strength, but if the width of the sealing portion of the outer material is increased, the outer material becomes larger, which increases the volume and weight of the battery, hindering miniaturization, and If the width of the sealing part is increased without changing the size of the electrode, the electrode must be reduced accordingly, which hinders the increase in capacity. It is preferable that the width is 1 mm or more and about 5 mm on both sides from the center (that is, about 2 to 10 mm as the width of the sealed portion).

As described above, if an electrolytic solution exists between aluminum and nickel, there is a problem that a local battery is formed and corrosion of aluminum occurs, but the clad material used as the positive electrode terminal is changed to a partial clad material. ,
The portion inside the battery, that is, the portion inside the sealing portion of the exterior material is made only of aluminum, and the portion where the aluminum layer and the nickel layer coexist is arranged in the sealing portion of the exterior material and is affected by the electrolytic solution. If not, corrosion of aluminum can be prevented.

[0028]

Next, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to only these examples. The preparation of the positive electrode, the negative electrode, and the polymer electrolyte commonly used in the following Examples and Comparative Examples will be described prior to the description of the Examples and the like.

Preparation of positive electrode: LiCoO as positive electrode active material
₂ 90 parts by weight, 5 parts by weight of carbon black is a conductive aid, polyvinylidene fluoride 5 parts by weight of a binder mixture of N- methylpyrrolidone to be uniform as a solvent, to prepare a positive electrode mixture-containing paste.

The paste containing the positive electrode mixture was coated to a thickness of 20 μm.
Is uniformly coated on both sides of the positive electrode current collector made of aluminum foil such that the amount of the positive electrode mixture on one side is 20 mg / cm ² (however, the amount of the positive electrode mixture after drying), and then dried to form a positive electrode mixture layer. Was formed, calendering was performed, and the thickness of the positive electrode mixture layer on one side was adjusted to 65 μm. 70mm x 4
The positive electrode was cut to a size of 0 mm. However, when producing the above-mentioned positive electrode, the paste containing the positive electrode mixture was not applied to a part of the aluminum foil constituting the positive electrode current collector, leaving an exposed portion of the aluminum foil, and the exposed portion was clad with aluminum and nickel. A lead portion for connection with a positive electrode terminal made of a material was used.

Preparation of negative electrode: 77 parts by weight of graphite as the negative electrode active material, 8 parts by weight of CARBOTRON P (trade name, low crystalline carbon having an average particle size of 22 μm, manufactured by Kureha Chemical Industry Co., Ltd.), and polyvinylidene fluoride as a binder 15 parts by weight were uniformly mixed using N-methylpyrrolidone as a solvent to prepare a negative electrode mixture-containing paste.

This negative electrode mixture mixture paste is 10 μm thick.
The negative electrode current collector made of copper foil is uniformly coated on both surfaces such that the amount of the negative electrode material mixture on one surface is 12 mg / cm ² (however, the amount of the negative electrode material mixture after drying), and dried to form a negative electrode material mixture layer. Was formed, calendering was performed to adjust the thickness of the negative electrode mixture layer on one side to 65 μm. This was cut into a size of 72 mm × 42 mm to obtain a negative electrode. However, in producing the negative electrode, the negative electrode mixture-containing paste was not applied to part of the copper foil constituting the negative electrode current collector, leaving an exposed portion of the copper foil, and the exposed portion was clad with copper and nickel. A lead portion for connection with a negative electrode terminal made of a material was used.

Production of positive electrode unit:
In the vicinity of the positive terminal and connection part of the lead part of the manufactured positive electrode,
50μm thick, 3mm wide polyimide tape on both sides
To prevent short circuit and maintain strength
Was. In addition, the surface of the lead portion that will be connected to the positive terminal
With a heat-peeling tape that loses the adhesiveness of the adhesive surface due to heat
Coated. Then, this positive electrode is made of a gel polymer electrolyte.
30 μm thickness and 12 g / m basis weight ^TwoPolyb
Tylene terephthalate non-woven fabric [manufactured by NKK, MB123
0 (product name)].

Preparation of the negative electrode unit: Near the connecting portion of the negative electrode lead portion with the negative electrode terminal, a thickness of 50 μm and a width of 3 mm
The imide tape was adhered from both sides to prevent short-circuiting and maintain strength of the portion. In addition, the surface of the lead portion, which is to be connected to the negative electrode terminal, was covered with a heat-peeling tape from which the adhesiveness of the adhesive surface was lost by heat. Then, the negative electrode is formed into a thickness of 30 μm serving as a support for the gel polymer electrolyte,
It was wrapped with a polybutylene terephthalate nonwoven fabric having a basis weight of 12 g / m ² [manufactured by NKK, MB1230 (trade name)].

Preparation of electrolytic solution containing gelling component: volume ratio of propylene carbonate to ethylene carbonate 1: 1
As a polymerization initiator, an electrolyte prepared by dissolving 1.22 mol / l of LiPF _{6 in} a mixed solvent of
4,6-Trimethylbenzoyldiphenylphosphine oxide (Lucillin TPO (trade name), manufactured by BSF Japan Co., Ltd.) was previously added and dissolved in the monomer component at 2% by weight, and dipentaerythritol hexaacrylate was added thereto. Was added 10 minutes before the start of use so that the concentration became 6% by weight, and mixed to prepare an electrolytic solution containing a gelling component. Hereinafter, the electrolyte containing the gelling component is simply referred to as a “gelling component-containing electrolyte” as described above.

The gelled component-containing electrolytic solution is absorbed by the positive electrode unit and the negative electrode unit under reduced pressure, respectively. The positive electrode unit and the negative electrode unit impregnated with the gelled component-containing electrolytic solution are put into a polyethylene bag. The bag was sealed.

From both sides of a bag containing a positive electrode unit and a bag containing a negative electrode unit impregnated with the gelling component-containing electrolyte, Fusion UV Systems Japan Co., Ltd.
UV light was applied for 10 seconds at an illuminance of 1 W / cm ² using a UV light irradiating device manufactured by Co., Ltd. to form a gel polymer electrolyte having a built-in support around the positive and negative electrodes.

The positive electrode and the negative electrode having the gel polymer electrolyte formed around them as described above are respectively taken out of the bag,
After the thermal release tape was peeled off from the lead portion by blowing hot air at 150 ° C. onto the lead portion, the five negative electrodes and four positive electrodes were alternately laminated to form a multilayer structure (that is, each of the positive electrode and the negative electrode was (A plurality of stacked electrode groups). Hereinafter, connection with an external terminal was performed by the method described in Examples and Comparative Examples, and a laminate film having a three-layer structure including a nylon film, an aluminum film, and a modified polyolefin film was prepared as an outer package for sealing the above-mentioned laminated electrode group.

Example 1 First, a clad material of aluminum and nickel (hereinafter, this clad material is referred to as “aluminum / Nickel clad material)
A ribbon-shaped clad material having a thickness of 80 μm was prepared. The aluminum thickness in this clad material is 6
At 0 μm, the thickness of the nickel was 20 μm. In addition, a clad material of copper and nickel (hereinafter, referred to as “copper / nickel”) is used as a clad material constituting a negative electrode terminal in which a portion outside the sealing portion of the exterior material functions as an external terminal.
Nickel clad material ") and a thickness of 80 μm
To prepare a ribbon-shaped clad material. The thickness of the clad material was 60 μm, and the thickness of nickel was 20 μm.

Then, using an ultrasonic welding machine, the positive electrode lead laminate (a laminate of four lead portions composed of four exposed aluminum foil portions) in the above-mentioned laminated electrode group and the aluminum / metal / laminate were used. A welding time of 75 msec, pressure of 2 kg / c with aluminum at one end of nickel clad material
m, and connected by ultrasonic welding under the conditions of amplitude of 60%. Further, the lead portion laminate of the negative electrode and the copper portion at one end of the copper / nickel clad material were welded for 12 hours.
0 msec, pressure 2 kg / cm, amplitude 60
% And connected by ultrasonic welding. Thereafter, the above-mentioned laminated electrode group was packaged with a package material and sealed to produce a laminated polymer electrolyte battery.

The welding width between the aluminum portion of the aluminum / nickel clad material constituting the positive electrode terminal and the lead portion laminate of the positive electrode was 2 mm, and the copper portion of the copper / nickel clad material constituting the negative electrode terminal was connected to the negative electrode. Was 2 mm and the width of the sealed portion of the exterior material was 4 mm.

In describing the structure of the polymer electrolyte battery, a positive electrode unit having a polymer electrolyte formed thereon as described above (hereinafter referred to as a “polymer electrolyte holding positive electrode”) and a negative electrode unit having a polymer electrolyte formed therearound (Hereinafter, this is referred to as “Polymer
That is, as shown in FIG. 1,
The polymer electrolyte-carrying positive electrode 10 has a support 3 around the positive electrode 1.
It is constituted by forming a gel-like polymer electrolyte 3 containing a.

As shown in FIG. 2, the polymer electrolyte holding negative electrode 20 is formed by forming a gel polymer electrolyte 3 having a support 3a built in around the negative electrode 2.

Then, the polymer electrolyte holding positive electrode 10
Are laminated with five sheets of the polymer electrolyte holding negative electrode 20,
As shown in FIG. 3, a stacked electrode group having a multilayer structure is configured.
That is, the first polymer electrolyte-holding negative electrode 20 and the fifth polymer electrolyte-holding negative electrode 20 are respectively disposed in the outermost layers, and between them, four polymer electrolyte-holding positive electrodes 10 and three polymer electrolyte-holding negative electrodes 20 are alternately arranged. And stacked. Then, the polymer electrolyte holding positive electrode 10
As shown in FIG. 4, between the positive electrode 1 and the negative electrode 2, the polymer electrolyte 3 formed around the positive electrode 1 and the polymer electrolyte 3 formed around the negative electrode 2 And they form a sufficiently thick polymer electrolyte layer, whereby the positive electrode 1 and the negative electrode 2 are sufficiently isolated.

In the battery, the laminated electrode group as described above is
As shown in the figure, the package is formed by packaging and sealing with a packaging material 4 composed of a laminated film having a three-layer structure of a nylon film-aluminum film-modified polyolefin film. In this battery, the positive electrode terminal 5 is made of an aluminum / nickel clad material, and the negative electrode terminal 6 is made of a copper / aluminum clad material.

FIG. 5 schematically shows a connection portion between the laminate of the aluminum lead portions 1c of the positive electrode 1 of the battery shown in FIG. 3 and the positive electrode terminal 5 and the vicinity thereof. Two exterior materials 4 are used, and the sealing is performed by heat fusion of a modified polyolefin film of a laminate film used as the exterior material 4. 4 a is a sealing portion of the exterior material 4, Reference numeral 4b denotes a sealing layer formed by melting the innermost modified polyolefin film of the exterior material 4 by heating, and the sealing layer 4b is a sealing portion 4a of the exterior material 4.
In addition, the sealing property of the inside of the battery is maintained by the sealing layer 4b. The positive electrode terminal 5 is made of a clad material of aluminum 5a and nickel 5b.
and c by welding.

As shown in FIG. 4, the positive electrode 1 is formed by forming a positive electrode mixture layer 1b on both surfaces of a current collector 1a made of aluminum, and a polymer electrolyte 3 is formed around the positive electrode 1. . The negative electrode 2 is a current collector 2a made of copper foil.
, A negative electrode mixture layer 2b is formed on both surfaces thereof, and a polymer electrolyte 3 is formed around the negative electrode 2. Although not shown in FIG. 5, the negative electrode 2 is also provided with a lead portion laminated as in the case of the positive electrode 1, and the laminate of the lead portion is welded to the copper portion of the copper / nickel clad material. Connected by 1 to 5 and FIG.
8 are schematically shown, and the dimensional ratio of each component is not always accurate. 1 and 2, the illustration of the current collector and the lead portion is omitted.

Example 2 A laminated polymer electrolyte battery was manufactured in the same manner as in Example 1 except that a so-called partial clad material was used as a clad material to be a positive electrode terminal.

FIG. 6 schematically shows a connection portion between the laminate of the aluminum lead portions 1c of the positive electrode 1 of the battery of the second embodiment and the positive electrode terminal 5 and the vicinity thereof. FIG.
As shown in the figure, the clad material constituting the positive electrode terminal 5 is such that the portion inside the battery, that is, the portion inside the sealing portion 4a of the exterior material 4 is composed of only aluminum 5a, and the portion of only aluminum is exterior 1 mm from the end face of the sealing portion 4a of the material 4 on the inside of the battery, and from there, aluminum 5a and nickel 5b toward the outside of the battery.
, And on the outside of the battery, only nickel 5b. The thickness of aluminum 5a where aluminum 5a and nickel 5b coexist is 40 μm, and the thickness of nickel 5b is 40 μm.

Example 3 A laminated polymer electrolyte battery was manufactured in the same manner as in Example 1 except that a partial clad material having a different form from that of Example 2 was used as a clad material to be a positive electrode terminal.

FIG. 7 schematically shows a connection portion between the laminate of the aluminum lead portions 1c of the positive electrode 1 of the battery of the third embodiment and the positive electrode terminal 5 and the vicinity thereof. FIG.
As shown in the figure, the clad material constituting the positive electrode terminal 5 is such that the portion inside the battery, that is, the portion inside the sealing portion 4a of the exterior material 4 is composed of only aluminum 5a, and the portion of only aluminum is exterior 1 mm from the end face of the sealing portion 4a of the material 4 on the inside of the battery, and from there, aluminum 5a and nickel 5b toward the outside of the battery.
It is composed of The thickness of aluminum 5a where aluminum 5a and nickel 5b coexist is 50 μm, and the thickness of nickel 5b is 30 μm.

COMPARATIVE EXAMPLE 1 A positive electrode lead portion laminate (a laminate of four lead portions composed of exposed portions of four aluminum foils) in the above-mentioned laminated electrode group having a multilayer structure was prepared with a thickness of 100 μm and a width of 100 μm. 3 mm, sandwiched between two reinforcing plates made of aluminum, and one 40 μm-thick nickel ribbon as a positive electrode terminal was stacked thereon. Using an ultrasonic welding machine, welding time was 75 msec, pressure was 2 kg / c.
Welding was performed under conditions of m ² and 60% amplitude. The position of this welded portion was made to coincide with the sealed portion when the laminated electrode group was sealed with the exterior material. In the same manner as described above, a negative electrode lead portion laminate (a laminate of five lead portions composed of five exposed portions of copper foil) in the laminated electrode group was made of copper having a thickness of 100 μm and a width of 3 mm. Between the two reinforcing plates,
Further, one nickel ribbon having a thickness of 40 μm was stacked as a negative electrode terminal, and the welding time was set to 1 using a welding machine similar to the above.
Welding was performed under the conditions of ²⁰ msec, a pressure of 2 kg / cm ² and an amplitude of 60%. The position of the welded portion was also set to match the sealed portion when the stacked electrode group was sealed with the exterior material. Thereafter, the laminated electrode group was packaged with a package material and sealed, thereby producing a laminated polymer electrolyte battery.

The width of the above welded portion was 2 mm on both the positive electrode side and the negative electrode side, and the width of the sealing portion of the exterior material was 4 mm in each case.

FIG. 8 schematically shows the connection between the laminate of the aluminum lead portions 1c of the positive electrode 1 of the battery of Comparative Example 1 and the positive electrode terminal 5 and the vicinity thereof. Is connected to the positive electrode terminal 5 by reinforcing the laminate of the lead portion 1c with a reinforcing plate 7 and welding the positive electrode terminal 5 to the reinforcing plate 7. The welding is performed by sealing the exterior material 4. This is performed at the stop portion 4a.

Comparative Example 2 A nickel ribbon having a thickness of 40 μm was used as a positive electrode terminal.
One end of this positive electrode terminal was welded and connected to the aluminum lead laminate of the positive electrode, and a nickel ribbon having a thickness of 40 μm was used as a negative electrode terminal. One end of this negative electrode terminal was connected to the negative electrode. A laminated polymer electrolyte battery was produced in the same manner as in Example 1 except that the laminate was connected to the copper lead laminate by welding.

The connection parts (welded parts) between the positive electrode aluminum lead and the positive electrode terminal by the energy density and the drop test of the batteries of Examples 1 to 3 and Comparative Examples 1 and 2 above.
Then, the presence or absence of peeling of the connection portion (welded portion) between the copper lead portion of the negative electrode and the negative electrode terminal was examined.
The storage deterioration after storage for one day was investigated. Table 1 shows the results. The above energy density was obtained by charging the battery at a constant current and constant voltage of 4.2 V and 0.2 C for 8 hours, and calculating from the discharge capacity and the average operating voltage when discharging the battery to 0.275 V at 0.2 C. . In the drop test above, the battery was 180c
m was dropped on concrete from a height of m, and the presence or absence of peeling of the welded portion between the positive electrode lead and the positive electrode terminal and the welded portion between the negative electrode lead and the negative electrode terminal was examined. This drop test was performed on each of the ten batteries, and Table 1 shows the number of batteries subjected to the test in a denominator, and the number of batteries that caused peeling of the welded portion in a numerator. Also,
The storage deterioration is determined by the following formula from the discharge capacity measured under the above conditions before storage and the discharge capacity measured under the above conditions after storage.

[0057]

[Table 1]

As is clear from the results shown in Table 1, in Examples 1 to 3, there was no peeling of the connection portions (welded portions) in the drop test, and the lead portions of the electrodes and the electrode terminals such as the positive electrode terminal and the negative electrode terminal. Had sufficient connection strength (welding strength). In Examples 1 to 3, storage deterioration was as low as 5 to 6%. In Example 1, since the nickel of the cladding material constituting the positive electrode terminal is in contact with the electrolytic solution, the storage deterioration is slightly higher than in Examples 2 and 3 in which nickel does not contact the electrolytic solution. Nevertheless, compared with Comparative Example 2 in which the nickel ribbon itself, which is not a clad material, was used as the positive electrode terminal, storage deterioration was small, and the range was within a range that would not hinder practical use. This is considered to be due to the fact that the corrosion of aluminum proceeds mainly at the welded portion of aluminum and nickel, and that the clad material has a small reaction area even when nickel is in contact with the electrolytic solution.

On the other hand, in Comparative Example 1 in which the laminate of the lead portions of the electrodes was reinforced with the reinforcing plate, no peeling was caused by the drop test and the leakage rate was low.
Energy density decreased. In Comparative Example 2 in which the positive electrode terminal made of a nickel ribbon was directly welded to the aluminum lead laminate of the positive electrode, the connection portion was peeled off in the drop test, and the storage deterioration was large.

In the above embodiment, an example of a clad material using nickel as one component of the clad material has been described.
Instead of nickel, a clad material using stainless steel as one component of the clad material may be used. When this stainless steel is used, the resistance is slightly higher than that of nickel, so that the load characteristics are slightly reduced. Otherwise, almost the same characteristics were obtained.

When the polymer electrolyte is gelled, in addition to those shown in the above Examples, for example, those which gel the polymer, radically polymerizable unsaturated polyester, radically polymerizable acrylic epoxy acrylate, urethane Photocurable resins such as acrylates, polyester acrylates, alkyd acrylates, and silicon acrylates may be gelled using ultraviolet rays or electron beams.

[0062]

As described above, according to the present invention, the connection strength between the lead portion of the electrode and the electrode terminal can be increased, and a polymer electrolyte battery having high reliability in battery performance can be provided.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically showing a polymer electrolyte holding positive electrode used in a polymer electrolyte battery of Example 1.

FIG. 2 is a cross-sectional view schematically showing a polymer electrolyte holding negative electrode used in the polymer electrolyte battery of Example 1.

FIG. 3 is a cross-sectional view schematically showing one example of a polymer electrolyte battery of Example 1.

FIG. 4 is an enlarged view of a main part of a stacked electrode group in the polymer electrolyte battery of Example 1 shown in FIG.

5 is a cross-sectional view schematically showing a connection portion between a lead portion of a positive electrode and a positive electrode terminal of the polymer electrolyte battery of Example 1 shown in FIG. 3 and the vicinity thereof.

FIG. 6 is a cross-sectional view schematically showing a connection portion between a lead portion of a positive electrode and a positive electrode terminal of a polymer electrolyte battery of Example 2 and the vicinity thereof.

FIG. 7 is a cross-sectional view schematically showing a connection portion between a lead portion of a positive electrode and a positive electrode terminal of a polymer electrolyte battery of Example 3 and the vicinity thereof.

FIG. 8 is a cross-sectional view schematically showing a connecting portion between a lead body of a positive electrode and a positive electrode terminal of a polymer electrolyte battery of Comparative Example 1 and the vicinity thereof.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Positive electrode 1a Aluminum foil 1b Positive electrode mixture layer 1c Lead part 2 Negative electrode 2a Copper foil 2b Negative electrode mixture layer 2c Lead part 3 Polymer electrolyte 4 Exterior material 4a Sealing part 5 Positive terminal 5a Aluminum 5b Nickel 6 Negative terminal 10 Polymer electrolyte holding Positive electrode 20 Polymer electrolyte holding negative electrode

Continued on the front page F term (reference) 5H022 AA09 AA19 BB11 CC02 CC08 CC12 CC22 EE01 EE03 EE04 5H029 AJ11 AJ13 AK03 AL07 AM00 AM03 AM05 AM07 AM16 BJ04 DJ02 DJ03 DJ05 DJ07 DJ12 EJ01 EJ12 HJ04

Claims (6)

[Claims] 1. A sheet-like positive electrode having a positive electrode mixture layer formed on at least one surface of an aluminum current collector and a negative electrode mixture layer formed on at least one surface of a copper current collector. In a polymer electrolyte battery in which a sheet-shaped negative electrode is laminated with a polymer electrolyte therebetween, and the positive electrode, the negative electrode and an electrode group composed of the polymer electrolyte are sealed with an exterior material, aluminum and nickel or stainless steel are used as a positive electrode terminal. A clad material having a thickness of at least twice the thickness of the aluminum lead portion of the positive electrode, and the aluminum portion at one end of the positive electrode terminal made of the clad material is used as a positive electrode. And the other end of the positive electrode terminal made of the clad material is drawn out from the sealing portion of the exterior material. battery. 2. The method according to claim 1, wherein each of the plurality of positive electrodes and the plurality of negative electrodes is a stacked electrode group in which the plurality of positive electrodes and the plurality of negative electrodes are stacked with a polymer electrolyte interposed therebetween. The polymer electrolyte battery according to the above. 3. A clad material constituting a positive electrode terminal is a partial clad material, at least a part of which is mainly composed of aluminum inside the sealed portion of the exterior material and which is disposed in the sealed portion of the exterior material. 3. The polymer electrolyte battery according to claim 1, wherein is a clad material of aluminum and nickel or stainless steel. 4. The current collector made of aluminum for the positive electrode having a thickness of 1
The thickness of the clad material of aluminum and nickel or stainless steel which comprises an aluminum foil of 0 to 20 μm and constitutes the positive electrode terminal is 30 to 300 μm.
4. The polymer electrolyte battery according to any one of 3. 5. A negative electrode terminal comprising: a clad material of copper and nickel or stainless steel, wherein the clad material has a thickness of at least twice the thickness of a copper lead of the negative electrode. The copper portion at one end of the negative electrode terminal comprising a lead connected to the negative electrode, and the other end of the negative electrode terminal comprising the clad material is drawn out of the sealing portion of the exterior material. The polymer electrolyte battery according to any one of the above. 6. The negative electrode current collector comprises a copper foil having a thickness of 5 to 20 μm, and a thickness of a clad material of copper and nickel or stainless steel constituting a negative electrode terminal is 30 to 300 μm. Polymer electrolyte battery.