JP2003242958A - Lithium cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small lithium cell disusing excessive components, which can be mounted on a circuit board, with few deterioration of discharging capacity against repetitive charge/discharge and long life. <P>SOLUTION: The lithium cell 20 is formed by mounting an electricity generating element composed of a lamination body formed by successively laminating a positive electrode 7, an electrolyte 12, and a negative electrode 10, on a base plate 3 having a positive electrode lead out part 5 and a negative electrode lead out part 6; and by electrically connecting the positive electrode 7 to the positive electrode lead out part 5 by an end surface electrode for positive electrode 13, and the negative 10 to the negative electrode lead out part 6 by an end surface electrode for negative electrode 14, and by jointing a lid 2 to the base plate 3. The end surface electrodes 13, 14 for the positive pole and negative pole are formed by molding thermoplastic conductive resin. <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 lithium battery that is compact and highly reliable against heat.

[0002]

2. Description of the Related Art A conventional lithium battery has a positive electrode, a positive electrode current collector, a positive electrode, an electrolyte-containing separator, a negative electrode, and a negative electrode in order to increase energy density. A current-collecting element, a sheet in which a negative electrode is sequentially laminated and wound in a spiral shape is used as a power-generating element,
The power generating element housed in a cylindrical exterior body is used. In such a lithium battery, the top surface of the exterior body serves as an electrode lead-out portion for the positive electrode and the bottom surface of the exterior body serves as an electrode lead-out portion for the negative electrode.

However, since the cylindrical lithium battery has a large mounting area when it is mounted on a circuit board, it cannot meet the recent demand for high-density mounting. In recent years, the progress of surface mounting structure in the electronic equipment field is remarkable, and many devices are changing to the shape suitable for this surface mounting technology. For example, even in the lithium battery used for memory backup of portable small electronic equipment, What has a shape and structure suitable for mounting technology is required, and a thin lithium battery called a coin type or a flat type has been used.

However, even in such a thin lithium battery, since the upper surface of the exterior body is the electrode extraction portion for the positive electrode and the lower surface of the exterior body is the electrode extraction portion for the negative electrode, it can be soldered to the circuit board. Requires a separate terminal, and as a result requires a larger mounting area and height than the size of the battery itself, it cannot be miniaturized, and the number of parts increases, which also increases costs. There was a problem of being connected.

Therefore, as a small battery that can be directly mounted on a circuit board without using terminals or the like, one or more sets of a positive electrode, an electrolyte or a separator containing an electrolyte, and a negative electrode are integrated and integrated. And a plating method, a baking method, a vapor deposition method, on one side surface of the laminated body,
A positive electrode end face electrode made of a metal film is deposited by a thin film forming method such as a sputtering method, and a negative electrode end face electrode made of a metal film is also deposited on the other side surface of the laminate by the same method. There has been proposed a laminated battery in which end electrodes for cathode and negative electrode are respectively extended to the lower surface of the laminated body (see Japanese Patent Laid-Open No. 6-231796).

According to this laminated battery, since both the positive electrode electrode lead-out portion and the negative electrode electrode lead-out portion are provided on the lower surface of the laminate, they are directly joined to the wiring on the circuit board by soldering. Therefore, there is an advantage that the mounting area is only the area of the battery and there is no need to use a separate terminal for mounting, so that the number of parts can be reduced and the cost can be suppressed.

However, when the laminated battery disclosed in JP-A-6-231796 is used as a lithium battery,
When charging and discharging are repeated, the metal forming the end face electrode elutes in the electrolyte and adheres to the electrode surface, blocking the site where lithium ions of the electrode active material come in and out, blocking the battery characteristics for a relatively short period of time. There was a problem that it deteriorated due to.

Further, when heat is applied for soldering,
There is also a problem that stress is generated due to a difference in thermal expansion between the end face electrode and the electrode, and the end face electrode is more easily separated from the positive electrode and the negative electrode.

Further, since the laminate has a structure exposed to the outside, it cannot be said that it is a realistic structure for a lithium battery that does not like moisture, and there is also a disadvantage that an electrolytic solution cannot be used as an electrolyte.

It is to be noted that Japanese Patent Laid-Open No. 6-231796 proposes to cover the laminated body forming the laminated battery with an exterior body, but in this case, both the positive electrode and the negative electrode are provided on the lower surface of the laminated body. However, there is a problem in that the electrode lead-out portion cannot be formed, a separate terminal is required for mounting on the circuit board, the mounting area becomes large, and the number of parts cannot be reduced.

[0011]

Therefore, in view of the above problems, the present invention sequentially laminates a positive electrode, an electrolyte, and a negative electrode on a base plate having a positive electrode extraction part and a negative electrode extraction part. A power generation element comprising a laminated body, the positive electrode of the laminated body and the positive electrode electrode extraction portion of the base plate are electrically connected by an end face electrode for the positive electrode, and the negative electrode of the laminated body and the The base plate negative electrode extraction portion is electrically connected by the negative electrode end face electrode,
The end face electrodes for the positive electrode and the negative electrode of the lithium battery in which the lid is joined to the base plate to hermetically accommodate the power generation element are carbon, graphite, zinc oxide, tin oxide, tin oxide doped with antimony, and oxidation. It is characterized in that it is formed of a conductive resin layer having thermoplasticity containing at least one conductive material selected from indium oxide, indium oxide doped with tin oxide, and titanium carbide.

As the resin component of the conductive resin layer, polyethylene terephthalate type resin, polybutylene terephthalate type resin, and their liquid crystal polymers,
Polyether ether ketone (PEEK) resin, polyketone sulfide (PKS) resin, fluororesin (PF)
A), a polysulfone-based resin, a polyether sulfone-based resin, a polyphenylene sulfide (PPS) -based resin, a polyhydroxyphenylene ether (PPO) -based resin, a polyamide-based resin, or a polystyrene-based resin. Is preferred.

Further, the average thickness of the positive and negative end face electrodes is preferably set in the range of 0.075 to 250 μm.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below.

FIG. 1 shows an example of the lithium battery of the present invention. A power generating element 1 composed of a laminated body in which a positive electrode 7, an electrolyte 12 and a negative electrode 10 are sequentially laminated, and the power generating element 1 is hermetically sealed. It is composed of a lid body 2 as an exterior body 4 to be housed and a base plate 3.

On the base plate 3, a positive electrode lead-out portion 5 is formed.
And the negative electrode extraction portion 6 are arranged so as to face each other, and the power generation element 1 is mounted between them.

The positive electrode 7 of the power generation element 1 has a base plate 3 with a positive end electrode 13 attached to the end surface thereof.
Is electrically connected to the upper positive electrode lead-out portion 5, and
The negative electrode 10 of the power generation element 1 is electrically connected to the negative electrode lead-out portion 6 on the base plate 3 through the negative end surface electrode 14 attached to the end surface of the power generation element 1.
The power generating element 1 is hermetically sealed in the exterior body 4 by covering the top with the lid 2 and bonding the lid 2 with a heat resistant resin or glass.

As described above, according to the lithium battery 20 of the present invention, the power generating element 1 is hermetically sealed in the exterior body 4 including the base plate 3 and the lid body 2. Can be prevented from being exposed to moisture in the outside air, and an electrolyte solution can be used as the electrolyte 12.

Further, since the positive electrode electrode lead-out portion 5 and the negative electrode electrode lead-out portion 6 are provided on the base plate 3, they are directly joined to the wiring on the circuit board by solder or the like without using a separate terminal or the like. The mounting area can be reduced because the mounting area is only the size of the lithium battery 20.

Moreover, by using a material having excellent heat resistance, it is possible to pass through a solder reflow furnace and it is possible to mount it together with other electronic components on a circuit board at a time, thus improving workability. Can be made. As the material of the lid body 2 and the base plate 3 that form the exterior body 4, a non-conducting metal or an insulating ceramic can be used, and an insulating ceramic that is particularly excellent in heat resistance and corrosion resistance can be used. If used, the reliability can be improved, which is preferable.

By the way, in the laminated body forming the power generation element 1, the positive electrode 7 and the negative electrode 10 are arranged so as to be offset from each other, and the overlapping portions function as a power generating portion.

As the positive electrode 7 and the negative electrode 10, a material in which active material particles are solidified with a binder, or a sintered body made of an active material can be used.

As the active material, lithium manganese composite acid is used.
Compound, manganese dioxide, lithium nickel composite oxide,
Lithium cobalt composite oxide, lithium nickel cobalt
Composite oxide, lithium vanadium composite oxide, lithium
Mutanitanium composite oxide, titanium oxide, niobium oxide, barium oxide
Nadium and tungsten oxide can be used,
Among these, Li₁+ XMn₂-XO_Four(0 ≦ x ≦ 0.
2), LiMn_2-yMe _yO_Four(Me = Ni, Cr, C
u, Zn, 0 ≦ y ≦ 0.6), Li_FourTi_FiveO₁₂Ai
Is Li_FourMn_FiveO₁₂Has a small volume change during charging and discharging.
Therefore, it is suitable as an active material.

As the positive electrode 7 and the negative electrode 10,
When using the active material particles solidified with a binder, for example, stainless steel, aluminum, nickel, copper, Kovar,
It can be produced by applying a slurry prepared by kneading an active material, a conductive agent and a binder onto a thin metal plate such as iron, titanium or an aluminum alloy and then drying and curing it.

As the positive electrode 7 and the negative electrode 10,
When a sintered body of the active material is used, one manufactured by any of the following methods (1) to (3) can be used. (1) The active material is dispersed in water or a solvent in which a molding aid is dissolved, and if necessary, a plasticizer and a dispersant are mixed to prepare a slurry, and the slurry is applied onto a base film,
After drying, the molded body is peeled from the base film and baked. (2) The active material is directly or granulated and then charged into a mold, and a compact molded by a press is fired. (3) The granulated active material is pressure-molded by a roll press machine and molded into a sheet, and then fired.

As the molding aid used when preparing the slurry, one or a mixture of two or more of polyacrylic acid, carboxymethyl cellulose, polyvinylidene fluoride, polyvinyl alcohol, diacetyl cellulose, hydroxypropyl cellulose, polyvinyl chloride, polyvinyl pyrrolidone, etc. Can be used, and as the base film, for example, a resin film of polyethylene terephthalate, polypropylene, polyethylene, tetrafluoroethylene or the like can be used.

However, with regard to the granulation of (2) and (3), it may be either wet granulation granulated from the slurry described in the method (1) or dry granulation using no solvent. Good, and it is not always necessary to use the molding aid in the method (2).

A positive electrode current collector plate 8 made of a thin metal plate is provided on the surface of the positive electrode 7 opposite to the contact surface with the electrolyte 12 via a conductive adhesive layer 9, and the negative electrode A negative electrode current collector plate 11 made of a thin metal plate is provided on the surface of 10 opposite to the contact surface with the electrolyte 12 via a conductive adhesive layer 9.

The positive electrode current collector 8 and the negative electrode current collector 11
As the material of, for example, a thin metal plate such as stainless steel, aluminum, nickel, copper, kovar, iron, titanium or aluminum alloy can be used.
It may be appropriately selected in consideration of the operating voltage range of 10 and the like.

As the conductive adhesive 9 for joining the positive electrode current collector 8 and the positive electrode 7 and the negative electrode current collector 11 and the negative electrode 10 respectively, an acrylic resin, an epoxy resin,
Silicon resin, polyamide resin, phenol resin,
At least one polymer adhesive of polyester resin, polyimide resin or styrene synthetic rubber, carbon black, graphite, zinc oxide, tin oxide, tin oxide doped with antimony oxide, indium oxide, tin oxide It is preferable to use a material containing a conductive material of at least one of doped indium oxide, titanium oxide coated with antimony-doped tin oxide, and potassium titanate coated with antimony-doped tin oxide.

It should be noted that the positive electrode 7 and the negative electrode 10 are relative, and the charge / discharge potentials of the respective active materials are compared with each other. It is only necessary to use a negative electrode 10 having a different potential, and a lithium battery 20 having an arbitrary voltage can be obtained by combining these.
Can be configured.

On the other hand, the electrolyte 12 may be liquid or solid as long as it has ion conductivity. As the electrolyte 12, an organic electrolyte solution obtained by dissolving an electrolyte salt in an organic solvent or a polymer solid electrolyte obtained by dissolving an electrolyte salt in a polymer solid electrolyte and polymerizing it, or a gel obtained by combining the organic electrolyte solution and the polymer solid electrolyte It is also possible to use an electrolyte or an inorganic solid electrolyte made of an inorganic material.

When an organic electrolytic solution is used for the electrolyte 12, examples of the organic solvent include ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, gamma-butyrolactone, sulfolane, 1,2-
It is possible to use a solvent selected from dimethoxyethane, 1,3-dimethoxypropane, dimethyl ether, tetrahydrofuran, 2-methyltetrahydrofuran, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, or a mixture of two or more thereof, and an electrolyte. Examples of salts include LiClO ₄ , LiBF ₄ , LiPF ₆ , and LiCF _3.
SO ₃ , LiN (SO ₂ CF ₃ ) ₂ , LiN (SO ₂ C
A lithium salt such as ₂ F ₅ ) ₂ can be used.

When an organic electrolytic solution is used for the electrolyte 12, it may be used by impregnating it in a separator. As the separator, for example, a polyolefin fibrous nonwoven fabric or a polyolefin fibrous microporous membrane can be used. Here, examples of the polyolefin fiber include polypropylene fiber and polyethylene fiber.

When a polymer solid electrolyte is used as the electrolyte 12, for example, a polymer having a polyethylene oxide skeleton, a polymer having a propylene oxide skeleton, or a mixture and a copolymer thereof can be used as the polymer solid electrolyte. .

In the case of using the inorganic solid electrolyte in the electrolyte 12, the inorganic solid electrolyte e.g. Li _{1. 3} Al _0.3 Ti _1.7
(PO _{4) 3} crystalline solid electrolyte such or _{Li 3.6 Ge 0.6 V 0.4 O 4} , 30LiI-41Li 2 O-29P 2 O 5 and 40
It may be an oxide-based amorphous solid electrolytes such as _{Li 2 O-35B 2 O 3} -25LiNbO 3.

As a method for producing such a power generating element 1, when the active material particles are hardened with a binder as the electrodes 7 and 10, the positive electrode with the positive electrode current collector plate 8 formed by the above-mentioned method is used. The negative electrode 10 with the negative electrode current collector 7 and the negative electrode 10 is prepared, and as the electrolyte 12,
Separator containing electrolyte, solid polymer electrolyte film,
Alternatively, a solid electrolyte sheet is prepared. Then, the positive electrode 7 is brought into contact with one main surface of the electrolyte 12, and the negative electrode 10 is brought into contact with the other main surface thereof, which are sequentially stacked and pressure-bonded.

When a sintered body of an active material is used as the electrodes 7 and 10, the positive electrode 7 and the negative electrode 10 are formed by the above-mentioned methods (1) to (3) to form the positive electrode 7. The positive electrode current collector plate 8 is attached to one main surface via the conductive adhesive 9, and the negative electrode current collector plate 11 is also attached to one main surface of the negative electrode 10 via the conductive adhesive 9. Paste. Moreover, as the electrolyte 12, a separator containing an electrolytic solution, a polymer solid electrolyte film, or a solid electrolyte sheet is prepared. Then, the positive electrode 7 can be brought into contact with one main surface of the electrolyte 12 and the negative electrode 10 can be brought into contact with the other main surface of the electrolyte 12 by sequentially stacking and pressure bonding.

The method of manufacturing the power generating element 1 is not limited to the above method.

Next, when mounting the power generating element 1 on the base plate 13, the negative electrode 10 exposed on one end side of the laminate forming the power generating element 1 and the negative electrode electrode take-out portion on the base plate 13. 6 is electrically connected via the end face electrode 14 for the negative electrode, and the positive electrode 7 exposed on the other end side of the laminated body forming the power generation element 1 and the positive electrode lead-out portion 5 on the base plate 13 are connected. Are electrically connected via the positive electrode end face electrode 13, and the positive electrode end face electrode 13 and the negative electrode end face electrode 14 are formed by a conductive resin layer having thermoplasticity.

Thus, the lithium battery 20 of the present invention
Since the end electrodes 13 and 14 for the positive electrode and the negative electrode are each formed of a conductive resin layer having thermoplasticity, heat is applied by, for example, soldering to a circuit board, and the respective electrodes 7, 10 are Even if the end surface electrodes 13 and 14 are thermally expanded, the end surface electrodes 13 and 14 can be deformed to absorb the thermal stress acting between the end surface electrodes 13 and 14, so that the end surface electrodes 13 and 14 are prevented from peeling off and a conduction failure is prevented from occurring. can do.

In the present invention, the conductive resin layer having thermoplasticity means a resin layer containing a conductive material in a thermoplastic resin. Further, as a method of forming the end face electrodes 13 and 14 on the end face of the laminated body forming the power generation element 1, a method of directly applying a conductive coating material using a dispenser, or a method of applying a constant amount on a base film which has been subjected to a peeling treatment is used. It is possible to employ a method in which a conductive coating material having a width is applied in advance and transferred to the end face of the laminate, a method of masking a portion which should not be conducted and dipping the conductive coating material tank.

Further, the end face electrodes 13 for the positive electrode and the negative electrode,
The conductive material contained in the conductive resin layer forming 16 includes carbon and graphite (40 to 70 μΩ · c
m), zinc oxide (10 ¹¹ to 10 ¹⁶ μΩ · cm), tin oxide (10 ⁸ μΩ · cm), antimony-doped tin oxide (1 × 10 ^{6 to} 5 × 10 ⁶ μΩ · cm), indium oxide ( 10 ² to 10 ¹¹ μΩ · cm), tin oxide-doped indium oxide (10 ² μΩ · cm), titanium carbide (18
0 μΩ · cm) is used.

That is, when a metal such as silver, nickel, or copper is used as the conductive material, the metallic conductive material is eluted from the end face electrodes 13 and 14 as the battery 20 is charged and discharged, and the positive electrode 7 and the negative electrode. Since the site that adheres to the surface of 10 and in which lithium ions of the active material come in and out is blocked, the cycle characteristics are deteriorated and an appropriate discharge capacity cannot be obtained. zinc,
When tin oxide, antimony-doped tin oxide, indium oxide, tin oxide-doped indium oxide, and titanium carbide are used, they will not be ionized even if the battery 20 is repeatedly charged and discharged, and thus will be eluted and the positive electrode 7 or the negative electrode will be used. Electrode 1
It is possible to prevent deterioration of cycle characteristics and maintain an appropriate discharge capacity without sticking to the surface of 0.

Further, in order to reduce the electrode loss in the battery 20 as much as possible, it is preferable that the electric resistance of the end face electrodes 13, 14 is as small as possible. For that purpose, carbon or graphite (40 to 40) having a small electric resistance is used as a conductive material. 70μ
End face electrode 1 by the conductive resin layer containing Ω · cm)
3 and 14 are preferably formed. Specific examples of carbon include furnace black, acetylene black,
Ketjen Black can be mentioned.

Further, as the resin component of the conductive resin layer forming the end face electrodes 13 and 14, it is preferable to use the thermoplastic resin as described above. Since the thermoplastic resin is easily deformed when heat is applied, as described above, even if the electrodes 7, 10 are thermally expanded by the heat applied when the battery 20 is mounted on the circuit board by soldering or the like, the end surface electrodes 13, 14
Can be deformed and absorb the thermal stress acting between them, so that it can be firmly adhered to each other without causing separation between the electrodes 7 and 10, and it is possible to secure conduction. Further, it is possible to obtain a current collecting structure having extremely excellent heat resistance, which can withstand the harsh conditions such as passing through a reflow furnace.

The thermoplastic resins preferable for forming the end electrodes 13 and 14 include polyethylene terephthalate resin, polybutylene terephthalate resin, liquid crystal polymers thereof, polyether ether ketone (PEEK) resin, and polyketone. Sulfide (PK
At least one of S) resin, engineering plastics such as fluororesin (PFA), polysulfone, polyether sulfone, polyphenylene sulfide (PPS) resin, polyhydroxyphenylene ether (PPO) resin, polyamide resin, and polystyrene resin. There is one kind.

However, if the average thickness T of each of the end face electrodes 13 and 14 is less than 0.075 μm, the end face electrodes 13 and 14 are too thin, which may reduce the reliability of the current collection and the adhesion strength. , 14 has an average thickness T of 250
If it exceeds μm, the electric resistance becomes too high for practical use, and the power generation area increases to reduce the energy density of the battery 20.

Therefore, each end face electrode 1 for the positive electrode and the negative electrode
The average thickness T of 3, 14 is 0.075 μm or more, 250
The average thickness T of each end face electrode 13, 14 is preferably set to 1 μm or more and 100 μm or less in consideration of electric resistance, reliability, adhesion strength, energy density of the battery 20, and the like. desirable.

Although the embodiments of the present invention have been described above, the present invention is not limited to those shown in the embodiments, and is also applicable to those improved or modified without departing from the gist of the present invention. It goes without saying that you can do it.

[0051]

Example 1 Here, when the kind of the conductive material contained in the conductive resin layers forming the end electrodes 13 and 14 for the positive electrode and the negative electrode of the lithium battery shown in FIG. 1 was changed. An experiment was conducted to measure the resistance value of the battery 20 and to compare the deterioration degree of the charge / discharge cycle characteristics.

The procedure for producing a lithium battery will be described below. The positive electrode electrode 7 <manufacture of a positive electrode electrode> is lithium manganese composite oxide _{(Li 1.1 Mn 1 .9 O 4} ) used as an active material. Then, a molding aid and a solvent were added to this active material and mixed to prepare a slurry.

The obtained slurry was applied on a polyethylene terephthalate (PET) film by a doctor blade method and then dried to prepare a green molded sheet.

The obtained green form sheet was placed in an atmosphere of 650
Electrode for positive electrode made of a sintered body of active material, which is fired at ℃ for 3 hours
Got 7. Further, aluminum as the positive electrode current collector 8
After printing the conductive adhesive 9 on one side of the foil, the positive electrode
The electrode for use 7 was placed, and both were joined by thermocompression bonding. <Production of Negative Electrode> The negative electrode 10 is made of an active material.
Lithium titanium composite oxide (Li_FourTi_FiveO ₁₂) Is used
It was Then, add the molding aid and solvent to this active material and mix.
Then, a slurry was produced.

The resulting slurry was applied on a polyethylene terephthalate (PET) film by the doctor blade method and then dried to prepare a green molded sheet.

The obtained green molded sheet was placed in an atmosphere of 750
The negative electrode 10 made of a sintered body of the active material was obtained by firing at 3 ° C. for 3 hours. In addition, after printing a conductive adhesive on both surfaces of an aluminum foil as the negative electrode current collector 11, the negative electrode 10 was adhered onto these and the both were joined by thermocompression bonding. <Production of Power Generation Element> The solid polymer electrolyte 12 is applied to the surface of the negative electrode 10, the positive electrode 7 is placed on the surface, and the thickness of the solid solid electrolyte 12 is reduced by hot pressing to simultaneously heat cure. Thus, a laminated body was formed. The positive electrode 7 and the positive electrode current collector 8 are exposed on one end surface of the laminated body, and the negative electrode 10 is formed on the other end surface of the laminated body.
Then, the negative electrode current collector 11 was cut so as to be exposed to manufacture the power generation element 1. <Formation of End Face Electrodes> Next, carbon, indium oxide doped with tin oxide (hereinafter referred to as ITO), and silver are used as conductive materials, and a polystyrene-based resin having thermoplasticity is used as a polymer adhesive for conductivity. Paint (conductive material: 50
vol.%, polymer adhesive: 50 vol.%), applied on a base film that has been subjected to a release treatment in advance, and transferred to both end faces of the laminate forming the power generation element 1, and then polymer By curing the pressure-sensitive adhesive, the positive electrode end face electrode 13 formed of a conductive resin layer electrically connected to the positive electrode 7 is provided on one end face of the laminate, and the negative electrode 10 is provided on the other end face of the laminate. The end face electrodes 14 for negative electrodes, each of which is composed of a conductive resin layer electrically connected to the above, were formed. In both cases, the average thickness T of the end face electrodes 13 and 14 is 10 μm.
m. <Formation of Lithium Battery> Alumina ceramics was used for the lid 2 and the base plate 3 that form the outer package 4, and the positive electrode extraction part 5 and the negative electrode extraction part 6 were previously formed on the base plate 3. Then, the power generation element 1 is mounted on the base plate 3, the positive electrode end face electrode 13 and the positive electrode electrode lead-out portion 5 are electrically connected using a conductive adhesive, and the negative electrode end face electrode 14 and the negative electrode After electrically connecting the electrode lead-out portion 6 with a conductive adhesive, the lid 2 is attached to the base plate 3
Are bonded to each other via an epoxy adhesive for encapsulation, and the adhesive is cured by being heated at a temperature of 120 ° C. for about 45 minutes while being pressed by a hot press to bond the two, and A lithium battery 20 as shown in FIG. 1 in which the power generating element 1 was hermetically sealed was manufactured. <Evaluation> Then, in measuring the resistance value of the obtained lithium battery 20, an Agilent 4338B milliohm meter manufactured by Agilent Technologies, Inc. was used to perform AC measurement at 1 kHz.

Next, for charge / discharge cycle characteristics, a charge / discharge cycle test was conducted. Specifically, the lithium battery 20 is charged with a current of 20 μA to 2.8 V, then discharged with a current of 5 μA to 2.0 V, and then again 2.
Charging up to 8 V was set as one cycle, charging / discharging was repeated for 50 cycles, and the ratio of the discharge capacity after 50 cycles to the initial discharge capacity was calculated and evaluated.

The results are shown in Table 1.

[0059]

[Table 1]

As can be seen from Table 1, in the comparative example using silver as the conductive material, the charge / discharge cycle characteristics were significantly deteriorated to 63.1%, although the resistance value of the battery 20 was as small as 1.02 kΩ. Therefore, when disassembling and examining the battery 20,
Since silver is attached to the surfaces of the electrodes 7 and 10, and this silver is contained only in the conductive resin layer forming the end face electrodes 13 and 14, the silver in the conductive resin layer elutes and the electrode 13 ,
It is considered that, as a result of being attached to the surface of No. 14, the site where lithium ions come in and go out with charge and discharge is prevented.

On the other hand, in the case of the present invention using ITO and carbon as the conductive material, although the resistance value of the battery using ITO is slightly high at 3.79 kΩ, the charging / discharging cycle characteristics are 70% or more. And was superior to the comparative example. Among them, the one using carbon as the conductive material is particularly excellent in that the resistance value of the battery 20 is as small as 1.26 kΩ and the discharge capacity is small as 81.0% in the charge / discharge cycle characteristics. I understood. (Example 2) Next, in the lithium battery 20 of the present invention using carbon as a conductive material, a polystyrene-based resin having thermoplasticity was used as a resin component of the conductive resin layer forming the end face electrodes 13 and 16. After preparing the batteries 20 and 10 batteries each using a thermosetting epoxy resin and measuring the resistance value of each battery 20, the temperature was set to 26.
An experiment was conducted in which the resistance value of the battery 20 was measured again and passed through a reflow furnace set at 5 ° C., and the charge / discharge cycle characteristics were compared.

The resistance value and charge / discharge cycle characteristics of the battery 20 were measured under the same conditions as in Example 1.

In the experiment, the end face electrodes 13,
Ten lithium batteries 20 each having the same configuration as in Example 1 except that the resin components of the conductive resin layer forming 14 were different were prepared, and the average value was obtained.

The results are shown in Table 2.

[0065]

[Table 2]

As can be seen from Table 2, the end face electrodes 13 and 14 are
In the comparative example in which the thermosetting epoxy resin is used as the resin component of the conductive resin layer that forms the battery, a significant difference occurs in the resistance value of the battery 20 before and after passing through the reflow furnace, and the charging is performed. Even with the discharge cycle characteristics, the discharge capacity is 65.8%
Fell significantly.

On the other hand, in the case of the present invention in which the polystyrene-based resin having thermoplasticity is used as the resin component of the conductive resin layer forming the end electrodes 13 and 14, the battery 20 is used even if it is passed through the reflow furnace. No significant change was observed in the resistance value, and the discharge capacity was 81.0
%, No significant decrease was seen.

As a result, if a thermoplastic resin such as polystyrene resin is used as the resin component of the conductive resin layer forming the end face electrodes 13 and 14, the charge / discharge cycle characteristics can be obtained without increasing the resistance of the battery 20. It can be seen that a long-life lithium battery 20 with less deterioration can be provided.

Although Example 2 was described based on an example in which carbon was used as the conductive material, the same tendency was observed when the conductive oxide exemplified in the embodiment such as ITO was used as the conductive material. Was given. (Example 3) Therefore, in the lithium battery 20 of the present invention in which carbon is used as the conductive material, the resistance value of the battery 20 when the average thickness T of the end face electrodes 13 and 14 is changed is shown in Example 1.
An experiment was conducted under the same conditions as above.

In the experiment, the end face electrode 13,
A lithium battery 20 having the same configuration as in Example 1 was used, except that the average thickness T of 14 was different, and the same average thickness T
10 pieces were prepared and the average value was calculated.

The results are shown in Table 3.

[0072]

[Table 3]

As can be seen from Table 3, the end face electrodes 13 and 14 are
Although the resistance value of the battery 20 could be minimized when the average thickness T was 0.1 μm, the resistance value rapidly increased when the average thickness T exceeded 0.075 μm.
It can be seen that the resistance value gradually increases even when is larger than 0.1 μm.

Since the resistance value of the battery is preferably as small as possible, the average thickness T of the end face electrodes 13 and 14 is
The resistance value of the battery 20 could be suppressed to less than 2 kΩ,
It can be seen that it is preferable to set in the range of 0.075 to 250 μm.

Although Example 3 has been described based on an example in which carbon is used as the conductive material, the same tendency is observed even when the conductive oxide exemplified in the embodiment such as ITO is used as the conductive material. And the average thickness T of the end face electrodes 13 and 14 is 0.0
It was good to set in the range of 75 to 250 μm.

[0076]

As described above, according to the present invention, a laminate in which a positive electrode, an electrolyte, and a negative electrode are sequentially laminated on a base plate having a positive electrode extraction part and a negative electrode extraction part. A positive electrode of the laminated body and the positive electrode electrode extraction portion of the base plate are electrically connected by an end face electrode for the positive electrode, and the negative electrode of the laminated body and the base plate of the laminated body. An end face electrode for the positive electrode and the negative electrode of a lithium battery in which the negative electrode electrode extraction portion is electrically connected to the negative electrode end face electrode, the lid is joined to the base plate to hermetically accommodate the power generating element, Thermoplastic containing at least one conductive material of carbon, graphite, zinc oxide, tin oxide, tin oxide doped with antimony, indium oxide, indium oxide doped with tin oxide, and titanium carbide By forming a conductive resin layer having, it is possible to obtain the following excellent effects. (1) Since the power generating element is hermetically sealed in the exterior body composed of the base plate and the lid, it is possible to prevent the power generating element from being exposed to moisture or the like in the outside air, and the electrolyte is electrolyzed. A liquid can also be used. (2) Since the positive electrode electrode lead-out portion and the negative electrode electrode lead-out portion are provided on the base plate, they should be directly joined to the wiring on the circuit board with solder or the like without using a separate terminal, etc. In addition, the mounting area can be reduced to the size of the lithium battery. (3) Since the positive electrode end surface electrode and the negative electrode end surface electrode are each formed of a conductive resin layer having thermoplasticity, heat is applied by, for example, soldering to a circuit board, and each electrode expands thermally. Also, since the end face electrodes can be deformed and the thermal stress acting between the two can be absorbed, the end face electrodes can be prevented from peeling off and conduction failure can be prevented. Moreover, since it can be passed through the solder reflow furnace, it can be mounted on the circuit board together with other electronic components at one time, so that workability can be improved. (4) As the conductive material of the conductive resin layer forming the positive electrode end surface electrode and the negative electrode end surface electrode, a material that does not ionize when charging and discharging are repeated is used, so that characteristic deterioration due to repeated charging and discharging is prevented. It is possible to maintain a predetermined discharge capacity for a long period of time.

As the resin component of the conductive resin layer, polyethylene terephthalate resin, polybutylene terephthalate resin, and their liquid crystal polymers,
Polyether ether ketone (PEEK) resin, polyketone sulfide (PKS) resin, fluororesin (PF)
A), a polysulfone-based resin, a polyether sulfone-based resin, a polyphenylene sulfide (PPS) -based resin, a polyhydroxyphenylene ether (PPO) -based resin, a polyamide-based resin, or a polystyrene-based resin. Thereby, a lithium battery having further heat resistance can be provided.

By adjusting the average thickness of the positive and negative end face electrodes to 0.075 to 250 μm,
A battery with low resistance can be provided stably.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of a lithium battery of the present invention.

[Explanation of symbols]

1 ... Power generation element 2 ... Lid 3 ... Base plate 4 ... Exterior body 5 ... Electrode take-out part for positive electrode 6 ... Electrode take-out part for negative electrode 7 ... Positive electrode 8 ... Current collector for positive electrode 9 ... Conductive adhesive layer 10 ... Negative electrode 11 ... Current collector for negative electrode 12 ... Electrolyte 13 ... End face electrode for positive electrode 14 ... Edge electrode for negative electrode 20: Lithium battery

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 5H022 AA09 BB03 BB12 CC04 CC10                       CC12 CC16 CC22 EE05 EE06                       EE08                 5H029 AK02 AK03 AL02 AL03 AM03                       AM04 AM05 AM07 BJ04 BJ12                       BJ23 CJ02 CJ05 CJ06 CJ08                       DJ05 EJ04 EJ05 EJ12 HJ04                 5H040 AA02 AT04 AY02 DD02 DD10                       DD15 DD21 JJ03 LL04 LL07                       NN01

Claims (3)

[Claims] 1. A power generation element comprising a laminated body in which a positive electrode, an electrolyte, and a negative electrode are sequentially laminated on a base plate having a positive electrode electrode extraction portion and a negative electrode electrode extraction portion. The positive electrode and the positive electrode electrode extraction portion of the base plate are electrically connected by a positive electrode end surface electrode, and the negative electrode of the laminate and the negative electrode electrode extraction portion of the base plate are connected to the negative electrode end surface electrode. A lithium battery in which a lid is joined to the base plate to hermetically accommodate the power generation element, and the positive and negative end face electrodes are carbon, graphite, and zinc oxide. Conductive resin containing at least one kind of conductive material selected from the group consisting of tin oxide, tin oxide doped with antimony, indium oxide, indium oxide doped with tin oxide, and titanium carbide. Lithium battery, comprising the. 2. The resin component of the conductive resin layer is polyethylene terephthalate resin, polybutylene terephthalate resin, and liquid crystal polymers thereof, polyether ether ketone (PEEK) resin, polyketone sulfide (PKS) resin, Fluorine resin (PFA), polysulfone-based resin, polyether sulfone-based resin, polyphenylene sulfide (PPS) -based resin, polyhydroxyphenylene ether (PPO) -based resin, polyamide-based resin, polystyrene-based resin The lithium battery according to claim 1, comprising: 3. The lithium battery according to claim 1, wherein the positive and negative end face electrodes have an average thickness of 0.075 to 250 μm.