JP2003115328A - Flat type nonaqueous electrolyte battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flat type nonaqueous electrolyte battery having a high capacity, a superior cycle characteristic, and further, a superior anti-leakage property and a high reliability. SOLUTION: This is the flat type nonaqueous electrolyte battery comprised that this is provided with a sealing plate, a metal sheath can and a gasket interposed between them and in which a negative electrode, a positive electrode and a nonaqueous electrolyte are tightly sealed up inside by inwardly tightening an open end part of the metal sheath can, and the flat type nonaqueous electrolyte battery is constituted in such a way that the seal plate serves as the positive electrode terminal in combination, that the metal sheath can serves as the negative electrode terminal in combination and that a circumferential part of the negative electrode is arranged between the inside bottom face of the metal sheath can and the gasket. In the flat type nonaqueous electrolyte battery, it is preferable to use lithium alloy or oxide of an element possible to be alloyed with lithium at the negative electrode, and further preferable to make a capacity ratio of the negative electrode against that of the positive electrode be 1.2 or more.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flat type non-aqueous electrolyte battery such as a button type non-aqueous electrolyte battery and a coin type non-aqueous electrolyte battery. More specifically, the sealing plate also serves as a positive electrode terminal, and a metal outer can is used. The present invention relates to a flat type non-aqueous electrolyte battery having a structure that also serves as a negative electrode terminal, high capacity, excellent cycle characteristics, and high reliability.

[0002]

2. Description of the Related Art Non-aqueous electrolyte batteries of flat type such as button type and coin type are widely used as main power sources and memory backup power sources for various electronic devices, both primary batteries and secondary batteries.

In particular, with the miniaturization of electronic equipment, batteries having a diameter of about 10 to 20 mm have been mainly used in the past, but recently, a small battery having a diameter of 8 mm or less has been required. .

In this flat type non-aqueous electrolyte battery, conventionally, as shown in FIG. 5, a metal outer can 4 also serves as a negative electrode terminal by tightening the open end of the metal outer can 4 also serving as a positive electrode terminal inward. The sealing plate 5 and the gasket 6 employ a structure in which the negative electrode 1, the positive electrode 2, and a power generation element such as a nonaqueous electrolytic solution in which a lithium salt is dissolved in an organic solvent are sealed inside. The positive electrode 2 has almost the same area, or the negative electrode 1 is arranged on the sealing plate 5 side,
It was customary to make the area of the anode smaller than the area of the positive electrode 2.

[0005]

In the above flat type non-aqueous electrolyte battery, the capacity of the battery is designed to depend mainly on the capacity of the positive electrode, while the cycle characteristics of the battery mainly depend on the capacity of the negative electrode. Therefore, the capacity and cycle characteristics of the battery are determined by the balance between the capacity of the positive electrode and the capacity of the negative electrode. In a conventional battery having a diameter of about 10 to 20 mm, the capacity ratio of both electrodes is determined under the condition that the areas of the negative electrode and the positive electrode are approximately the same as described above, and both the capacity of the battery and the cycle characteristics are to some extent. The battery design was satisfactory.

However, even in the conventional battery having a relatively large diameter, while maintaining good cycle characteristics,
There has been a demand for higher capacity. Further, in the case of a small battery, when the flat non-aqueous electrolyte battery is downsized by the above conventional configuration, the ratio of the volume occupied by something other than the power generation element such as a gasket increases compared to the volume of the entire battery. Therefore, the reduction rate of the effective internal volume inside the battery is larger than the reduction rate of the internal volume of the battery, which makes it impossible to design a battery having a target capacity. Moreover, as the size of the battery becomes smaller, the content of the electrolytic solution is regulated, so that the cycle characteristics of the battery largely depend on the capacity ratio of the positive electrode and the negative electrode, and the conventional diameter is about 10 to 20 mm. It was also found that the cycle ratio is significantly reduced at the capacity ratio used in the battery.

However, in order to solve the above problem, if the ratio of the positive electrode is decreased and the capacity ratio of the negative electrode is increased,
If the capacity of the battery is greatly reduced and it becomes a battery that is not practical, and if the amount of electrolyte is increased, the cycle characteristics are improved, but electrolyte leakage easily occurs, and the effective contents inside the battery It was also found that if the volume ratio of the gasket is reduced to secure the product, the sealing ability of the gasket is reduced and the sealing performance is deteriorated.

The present invention solves the problems of the flat type non-aqueous electrolyte battery as described above, and has a high capacity, excellent cycle characteristics, and excellent liquid leakage resistance, and a highly reliable flat type non-aqueous battery. It is intended to provide an electrolyte battery.

[0009]

The present invention comprises a sealing plate, a metal outer can, and a gasket interposed therebetween, and the opening end of the metal outer can is tightened inward to form a negative electrode. In a flat nonaqueous electrolyte battery in which a positive electrode and a nonaqueous electrolyte are sealed inside, the sealing plate also serves as a positive electrode terminal, the metal outer can also serves as a negative electrode terminal, and the space between the inner bottom surface of the metal outer can and the gasket is By arranging the outer peripheral portion of the negative electrode in a high capacity, and excellent cycle characteristics, further provides a highly reliable flat non-aqueous electrolyte battery having excellent liquid leakage resistance, to solve the above problems It was done.

The battery structure of the present invention becomes more effective as the diameter of the battery becomes smaller. Therefore, it is preferably used in a battery having a diameter of 2 to 16 mm, particularly 2 to 8 mm.
The remarkable effect can be obtained in the small-sized battery.

[0011]

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

In the present invention, unlike the conventional flat type non-aqueous electrolyte battery, the positive electrode is arranged on the side of the sealing plate of the battery and the negative electrode is arranged on the side of the metal outer can. The material of the sealing plate is Usually, the one used for the metal outer can in the conventional flat non-aqueous electrolyte battery can be used, and as the material of the metal outer can, usually, the sealing plate in the conventional flat non-aqueous electrolyte battery. What was used can be used.

Specific examples of the materials of the sealing plate and the metal outer can include, for example, stainless steel, copper, titanium,
Examples thereof include iron, nickel, aluminum, alloys thereof, those obtained by plating the surface of the member, and those obtained by compounding a plurality of materials such as a clad plate of the member. Further, the member may be subjected to an annealing treatment or the like, if necessary, for the purpose of improving workability and liquid leakage resistance.

For the negative electrode, lithium, a lithium alloy, an oxide of an element capable of alloying with lithium, a carbonaceous material, a lithium-containing nitride, or the like can be used as an active material. Above all, a lithium alloy or an oxide of an element capable of alloying with lithium is preferably used, and particularly when a lithium alloy is used, a remarkable effect can be obtained.

As the lithium alloy, for example, an alloy of lithium and an element capable of alloying with lithium, such as aluminum, indium, lead, tin, silicon, magnesium, zinc, cadmium, bismuth, boron and antimony is used. It is possible to coexist two or more kinds of the above elements and form an alloy of ternary system or more. Among them, an alloy containing at least one element selected from aluminum, tin and silicon is preferably used. Further, for the purpose of improving the cycle characteristics by suppressing the collapse of the negative electrode due to repeated charge and discharge, in the lithium alloy, for example, manganese, chromium, iron, tungsten, molybdenum, cobalt, nickel, zirconium, Other elements such as titanium and vanadium may be contained.

Specific examples of oxides of elements capable of alloying with lithium include tin oxides such as SnO and SnO ₂ and silicon oxides such as SiO and SiO _2. . Of course, it may be an oxide in which a part of the elements forming the oxide is replaced with another element.

Some lithium-containing transition metal oxides such as lithium titanium oxide represented by Li _x Ti _y O _z can be used as a negative electrode active material. In the case of the lithium titanium oxide, x = 4 /
An oxide represented by 3, y = 5/3 and z = 4 is preferably used, and an oxide in which a part of titanium is replaced with another element can also be used.

As the carbonaceous material, for example, natural graphite,
Graphite-based materials such as artificial graphite, cokes, carbon fiber,
Materials conventionally used as a negative electrode active material for nonaqueous electrolyte batteries such as mesocarbon microbeads and activated carbon can be used.

As the lithium-containing nitride, for example, a composite nitride containing a transition metal element such as cobalt, nickel, manganese, iron and vanadium and lithium as constituent elements can be used. Specifically, a nitride containing cobalt or nickel such as Li _2.6 Co _0.4 N can be preferably used. Further, it may be an oxynitride in which a part of nitrogen is replaced with oxygen.

Among the above-mentioned materials which become the active material of the negative electrode, oxides of elements capable of alloying with lithium and materials containing no lithium such as carbonaceous materials are used in combination with these. Depending on the positive electrode active material, lithium may be contained in advance by an electrochemical or mechanical method before use. For materials containing lithium such as lithium alloys and lithium-containing nitrides, conversely to the above,
Depending on the positive electrode active material to be combined, lithium may be released in advance, or a lithium-free material may be added with lithium later in the battery assembly process to form the desired compound.

Further, the above-mentioned negative electrode active material may be used as it is, but a plurality of materials may be mixed and used, or a composite may be used. Furthermore, if necessary, it can be used in combination with a conductive substrate such as a metal foil, a metal plate or a metal net, or can be mixed with a binder, a conductive auxiliary agent or the like to be used as a molded body. Here, as the binder, for example, polytetrafluoroethylene, polyvinylidene fluoride, a fluorine-based resin such as tetrafluoroethylene-hexafluoropropylene copolymer, a styrene-based resin such as styrene-butadiene copolymer, carboxymethyl cellulose, etc. Cellulose, a polymer or copolymer of N-vinylacetamide, polyethylene terephthalate and the like can be preferably used. Examples of the conductive aid include, for example, flake graphite, acetylene black,
Carbon black, Ketjen black, etc. can be used.

As described above, for the negative electrode, the negative electrode active material is used as it is, an active material layer is formed on a conductive substrate such as a metal foil or a metal plate, or a mixture is molded. It is produced by the method of. When the negative electrode is formed by forming a lithium alloy layer on a metal plate, for example,
If a lithium alloy layer is formed on the metal plate by a method such as bringing lithium into contact with a metal plate containing an element capable of alloying with lithium, such as aluminum, or electrochemically doping lithium. Good. At this time, the lithium alloy layer may be uniformly formed on the entire surface of the metal plate on the side facing the positive electrode, but the lithium alloy layer formed on the outer peripheral portion of the metal plate is the inner bottom surface of the metal outer can and the gasket. Since it is arranged between the two, and does not directly face the positive electrode, the utilization factor during charging and discharging is lower than that in the central portion. In addition, since the formation of the lithium alloy layer involves volume expansion, if more lithium alloy layer is formed between the inner bottom surface of the metal outer can and the gasket, the sealing part will be deformed and the hermeticity will be reduced. May cause Therefore, by suppressing the formation of the lithium alloy layer in the outer peripheral portion of the metal plate, and by configuring the negative electrode so that the thickness of the lithium alloy layer in that portion is thinner than the thickness in the central portion, charging / discharging It is possible to use the lithium alloy layer efficiently at
Further, it becomes possible to prevent the above-mentioned deterioration of the hermeticity. Note that the lithium alloy layer may not be formed on the outer peripheral portion of the metal plate as long as the required capacity of the negative electrode can be secured.

As a method of suppressing the formation of the lithium alloy layer on the outer peripheral portion of the metal plate, for example, a method of making the diameter of lithium contacting the metal plate smaller than the diameter of the metal plate can be adopted. . In this case, when a metal plate having a central portion thinner than the outer peripheral portion is used, the movement of lithium to the outer peripheral portion of the metal plate is suppressed, which effectively forms the lithium alloy layer on the outer peripheral portion of the metal plate. Can be suppressed. As the metal plate, for example, a metal plate having a recess in the center and the diameter of the recess being 70 to 90% of the outer diameter of the metal plate is preferably used. If lithium is brought into contact with the recess to form a lithium alloy layer, the movement of lithium to the outside of the recess is suppressed due to the step in the recess, and the lithium alloy layer is hardly formed on the outer peripheral portion of the metal plate. You can also

Further, by providing the metal plate with a recess,
The depression of the concave portion and the expansion due to the formation of the lithium alloy layer are canceled out to form a negative electrode having a thickness close to the initially designed value, so that a preferable result can be obtained from the standpoint of battery design. The thickness of the concave portion of the metal plate is not particularly limited, but if the composition of the lithium alloy layer to be formed and the amount of expansion when forming the lithium alloy layer are taken into consideration, the thickness of the outer peripheral portion is 25 It is preferably ˜95%.

The above-mentioned metal plate may be integrated with the metal outer can, for example, the plate of the element capable of alloying with lithium is pressure-bonded or welded to the metal outer can. It is also possible to use a clad material (for example, a nickel-stainless steel-aluminum clad plate) with a member that constitutes a metal outer can.

Further, the formation of the lithium alloy layer is suppressed by applying a sealing agent to the outer peripheral portion of the metal plate to prevent it from getting wet with the electrolytic solution or by disposing a pedestal described later. It is possible to

On the other hand, for the positive electrode, a metal oxide, a metal chalcogenide, an organic sulfur compound, a conductive polymer, a carbonaceous material or the like can be used as a positive electrode active material.

Examples of the metal oxides include transition metal oxides such as manganese oxide, vanadium oxide and niobium oxide, lithium cobalt oxide, lithium nickel oxide, lithium niobium oxide and lithium manganese oxide. (LiMn ₂ O ₄ , LiMn ₃ O ₆ , LiMnO _{2 and the} like), lithium-containing composite oxides such as lithium titanium oxide (Li _4/3 Ti _5/3 O _{4 and the} like), and the like can be used. In addition, Li _{1 + x} Ni _{1 / 2-y + z} Mn _{1 / 2-yz} Co _2y
A compound obtained by substituting a part of the elements of the complex oxide with another element such as O ₂ can also be used.

As the metal chalcogenide, metal sulfides such as titanium disulfide, molybdenum disulfide, lithium sulfide and nickel sulfide can be mainly used. Further, a lithium sulfide having solubility in an electrolytic solution can be used in a form dissolved in the electrolytic solution.

Examples of the organic sulfur compound include CS
_A compound represented by a general formula such as _t and having a disulfide bond mainly composed of carbon and sulfur can be preferably used.

As the conductive polymer, for example, polyaniline, polyacetylene, polypyrrole, etc. can be used.

Also for the production of the positive electrode, as in the case of the negative electrode, the above positive electrode active material is used as it is, or the active material layer is formed on a conductive substrate such as a metal foil or a metal plate, or a mixture is molded. And the like can be adopted. Further, the content of lithium may be appropriately adjusted as in the case of the negative electrode active material.

In the present invention, the capacity ratio of the negative electrode and the positive electrode varies depending on the combination of the active material used for the negative electrode and the active material used for the positive electrode, but a metal oxide is used for the positive electrode and a lithium alloy is used for the negative electrode. Alternatively, when an oxide of an element capable of alloying with lithium is used, the ratio of the capacity of the negative electrode to the capacity of the positive electrode (negative electrode capacity / positive electrode capacity) is preferably about 1.2 or more, and 1.39 or more. More preferably, it is preferably 2 or less, more preferably 1.73 or less. That is, by setting the capacity of the negative electrode to 1.2 times or more the capacity of the positive electrode, the negative electrode is pulverized with charge and discharge to reduce the conductivity, and the electrolyte is excessively taken into the negative electrode to cause discharge. It can be prevented from becoming difficult.
Further, by setting the capacity of the negative electrode to not more than twice the capacity of the positive electrode, it is possible to prevent the crystal structure of the positive electrode active material from changing during overdischarging so that charging and discharging cannot be performed. And
The ratio of the negative electrode capacity to the positive electrode capacity (negative electrode capacity /
The positive electrode capacity) is preferably 1.39 or more from the viewpoint of ensuring the cycle characteristics, and 1.73 or less from the viewpoint of ensuring the discharge capacity of the battery.

A flat nonaqueous electrolyte battery is assembled as follows using the above-mentioned negative electrode and positive electrode. First, the negative electrode is arranged on the inner bottom surface of the metal outer can, and the positive electrode is arranged on the sealing plate side via the separator. The connection between the negative electrode and the metal outer can and the connection between the positive electrode and the sealing plate are made by integration by pressure bonding or welding, or by contact via a conductive agent such as carbon paste.

In the present invention, the battery is constructed so that the volume ratio of the gasket is reduced as compared with the conventional configuration, and the outer peripheral portion of the negative electrode is located between the inner bottom surface in the metal outer can and the gasket. By adopting such a configuration, the capacity of the negative electrode can be increased without lowering the capacity of the battery, and the cycle characteristics can be greatly improved. Further, when the volume ratio of the gasket is reduced, generally, the sealing performance of the gasket is deteriorated and the hermeticity is deteriorated, and the leakage of the electrolytic solution or the dissipation to the outside of the battery is likely to occur. Since the gasket is favorably fixed by the outer peripheral portion of the negative electrode disposed between the inner bottom surface of the outer can and the gasket, and the adhesion between the gasket and the metal outer can and the sealing plate is improved, the above problems occur. It gets harder.

In the present invention, the outer peripheral portion of the negative electrode is arranged between the inner bottom surface of the metal outer can and the gasket, but the outer peripheral portion of the negative electrode directly contacts the inner bottom surface of the metal outer can and the gasket. This is not always necessary, and for example, a separator or a pedestal as shown below may be arranged between the negative electrode and the metal outer can or gasket.

In the present invention, the shape change of the negative electrode or the positive electrode due to charge / discharge is prevented, and when a lithium alloy is used for the negative electrode, formation of a lithium alloy layer on the outer peripheral portion of the negative electrode is suppressed to improve cycle characteristics and reliability. In order to further improve the property, a member for maintaining the shape, a so-called pedestal may be arranged on the outer peripheral portion of the negative electrode or the positive electrode. The material and shape of the pedestal are not particularly limited, but usually a metal such as nickel or stainless steel, such as a washer (washer) shape or an L-shaped or L-shaped inverted L-shaped cross section is used. It is preferably used.

As the separator, a microporous resin film, a non-woven fabric, or the like is used. Examples of the material thereof include polyolefin such as polyethylene and polypropylene, and tetrafluoroethylene-perfluoroalkoxyethylene copolymer for heat resistance. A fluororesin such as a polymer (PFA), polyphenylene sulfide (PPS), polyether ether ketone (PEEK), polybutylene terephthalate (PBT) and the like can be mentioned. In particular, a plurality of laminated microporous film and non-woven fabric of the above material,
Alternatively, a separator having a multi-layer structure formed by laminating a plurality of microporous films or a plurality of nonwoven fabrics is preferably used. This is due to the following reasons. That is, in the present invention, as will be described later, it is possible to reduce the amount of electrolytic solution compared to the conventional configuration, but with it, the liquid retaining performance of the separator becomes more important, and the active material with a large capacity It is necessary to ensure the stability when using, but the separator having the above-mentioned multilayer structure can easily satisfy those requirements.

The separator is not particularly limited as to its arrangement as long as it can prevent contact between the negative electrode and the positive electrode, but if the outer peripheral edge portion of the separator is inserted between the gasket and the negative electrode, the battery Positional deviation of the separator is less likely to occur during assembly. Further, if the outer peripheral edge portion of the separator is fixed by the sealing plate and the gasket, it is possible to more effectively prevent the displacement of the separator.

As the non-aqueous electrolyte, a non-aqueous liquid electrolysis is used.
Quality, polymer electrolytes can be used, but generally electrolysis
Since a liquid electrolyte called a liquid is often used,
Detailed explanation of liquid electrolyte by the expression "electrolyte"
To do. That is, as the non-aqueous electrolyte solution, lithium salt
It is prepared by dissolving an electrolyte salt such as
The prepared organic solvent-based electrolyte can be preferably used.
It Then, the organic solvent used as the solvent of the electrolytic solution
Examples of the medium include propylene carbonate and ethylene.
Cyclic carbonate, butylene carbonate, etc.
Bonate, diethyl carbonate, dimethyl carbonate
Carbonated chains such as gypsum and ethyl methyl carbonate
Toluene, fluorobenzene, difluoroanisole, trif
Fluorine-containing organic solvents such as luorotoluene, γ-butyral
Kuton, 1,2-dimethoxyethane, 1,2-dietoki
Sietane, tetrahydrofuran, dioxolane, etc.
These solvents are used alone or as a mixture of two or more kinds.
It can be used as a mixed solvent. And lithium
Examples of electrolyte salts such as salts include, for example, LiN (CF₃S
O₂)₂, LiClO_Four, LiBF_Four, LiPF₆, LiA
sF₆, LiSbF₆, LiCF₃SO₃, LiCF₃C
O₂, LiC_nF_{2n + 1}SO₃(N ≧ 2), LiN (CF ₃C
F₂SO₂)₂Etc. can be used. Also the polymer
Solid polymer electrolyte in which electrolyte salt is supported on the substrate
Gel-like polymer made by gelling the electrolyte and electrolyte
An electrolyte can also be used as the non-aqueous electrolyte.

Examples of gaskets include polypropylene and nylon, and tetrafluoroethylene-perfluoroalkoxyethylene copolymer (PF) for heat resistant applications.
Fluororesin such as A), polyphenylene ether (PP
E), polysulfone (PSF), polyarylate (P
AR), polyether sulfone (PES), polyphenylene sulfide (PPS), polyether ether ketone (PEEK) and the like can be used.

The sealing is performed by tightening the opening end of the metal outer can inward. At this time, a structure in which the peripheral portion of the sealing plate is folded back is preferable because the adhesion between the gasket and the sealing plate is improved and the liquid leakage resistance is improved. In addition, the shape of the gasket is not particularly limited, but in order to prevent the gasket from protruding from the opening end of the metal outer can when sealing and preventing the sealing performance from decreasing, the inner surface of the opening end of the metal outer can is prevented. It is preferable that the corner portion of the outer peripheral surface of the gasket contacting with is formed into a curved surface or the C portion is attached to the corner portion (the corner portion is a flat surface). Further, the outer peripheral edge portion of the separator is sandwiched between the metal outer can and the gasket to be cut by forming the corner portion of the gasket facing the negative electrode into a curved surface or by attaching the C surface to the corner portion. Can be prevented, and in the upper part of the part where the folded part of the peripheral part of the gasket sealing plate comes into contact,
By providing the convex portion with which the upper end of the folded-back portion of the peripheral portion of the sealing plate can be caught, the sealing plate and the gasket can be fixed more securely.

In the flat type non-aqueous electrolyte battery having the conventional structure, the amount of the electrolytic solution required for the battery design is about 40 with respect to the area of the facing surface of the negative electrode (the area on the side facing the positive electrode).
Although it was about 50 μl / cm ² , in the flat non-aqueous electrolyte battery of the present invention, the capacity ratio of the negative electrode was increased, so that the charge depth or the discharge depth of the negative electrode in the charge / discharge cycle was reduced, and particularly lithium was used. Since the deterioration of the negative electrode when the alloy is used is suppressed, the battery can sufficiently function even with a small amount of the electrolytic solution of about 10 to 40 μl / cm ² .

[0044]

EXAMPLES Next, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to only those examples.

(Example 1) A positive electrode was prepared as follows. First, 100 parts by weight of LiMn ₃ O ₆ powder, 5 parts by weight of carbon black as a conduction aid, 5 parts by weight of flake graphite as a conduction aid, and 0.7 parts by weight of polytetrafluoroethylene as a binder. After being mixed and dried, the resulting mixture is pressure-molded into pellets having a diameter of 4.8 mm and a thickness of 0.46 mm, and the pellets are dried at 250 ° C. for 12 hours in an electric drying furnace to be dehydrated. 4.
A 0 mAh positive electrode was prepared.

A lithium-aluminum alloy was used for the negative electrode. The production of this negative electrode was carried out as follows, using a current collecting network in order to improve current collecting efficiency. First, punch out a stainless steel collector net into a disc with a diameter of 6.1 mm,
It is made of stainless steel with an outer diameter of 6.5 mm (material:
The inner bottom surface of SUS444) was resistance-welded, and an aluminum plate (flat plate) punched into a disc shape having a diameter of 6.1 mm and a thickness of 0.31 mm was crimped to the current collecting net. Then, a disc-shaped lithium plate having a diameter of 5.0 mm and a thickness of 0.15 mm was arranged on the aluminum plate to form a negative electrode having a capacity of 6.2 mAh.

As the non-aqueous electrolyte, an electrolytic solution prepared by dissolving LiPF ₆ at 0.6 mol / l in a mixed solvent of propylene carbonate and 1,2-dimethoxyethane in a volume ratio of 2: 1 was used, and the amount of the electrolytic solution was 7 μl. did. When the amount of this electrolytic solution is expressed as a value relative to the area of the facing surface of the negative electrode, it is 24 μl / cm
^{Was 2} . A separator having a three-layer structure of polypropylene non-woven fabric-microporous polypropylene film-polypropylene non-woven fabric was used, and a gasket made of polypropylene whose cross-sectional shape of the main part is shown in FIG. 2 was used. Although only a part of the gasket 6 is shown in FIG. 2, the gasket 6 is a ring-shaped body, and the outer peripheral corner on the side facing the negative electrode is a curved surface 6a. C at the corner of the outer peripheral surface that contacts the inner surface of the
A surface 6b is provided, and a convex portion 6c with which the upper end of the folded-back portion can be hooked is provided above the portion of the peripheral portion of the sealing plate with which the folded-back portion abuts.

The above positive electrode, negative electrode, separator, gasket, non-aqueous electrolyte and stainless steel sealing plate (material:
SUS444) and an outer diameter of 6.5 mm shown in FIG.
A flat type non-aqueous electrolyte battery having a height of 1.4 mm was assembled.
The ratio of the capacity of the negative electrode (hereinafter referred to as “negative electrode capacity”) to the capacity of the positive electrode (hereinafter referred to as “positive electrode capacity”) of this battery (negative electrode capacity / positive electrode capacity) was 1.55. Is a so-called button type battery, and has an outer diameter of 6.5 mm and a height of 1.4 mm.
It is a small battery of mm.

The structure of the battery of Example 1 will be described with reference to FIG. 1. Reference numeral 1 is the negative electrode, and the negative electrode 1 is housed in the metal outer can 4, and the metal outer can 4 is as described above. It is made of stainless steel and also serves as the negative electrode terminal. A current collecting net is welded to the inner bottom surface of the metal outer can 4, but the current collecting net is not shown.

On the other hand, the positive electrode 2 is housed in the sealing plate 5, which is made of stainless steel and also serves as the positive electrode terminal. In order to reduce the contact resistance, the positive electrode 2 and the sealing plate 5 are coated with a carbon paste between them and are connected via the carbon paste, but the carbon paste is not shown.

A separator 3 is disposed between the negative electrode 1 and the positive electrode 2, and the outer peripheral edge portion of the separator 3 and the outer peripheral portion 1a of the negative electrode 1 are between the inner bottom surface of the metal outer can 4 and the gasket 6. The gasket 6 is disposed in the inner peripheral surface of the sealing plate 5 and the inner side surface of the open end of the metal outer can 4 by pressing the inner end of the open end of the metal outer can 4 inward. Then, the inside of the battery has a sealed structure.

It should be noted that FIG. 1 schematically shows the structure of the battery, and does not necessarily show all the constituent members as described above, and of course the non-aqueous electrolyte (electrolyte solution).
Also not shown. This is because, if all the constituent members are illustrated, it becomes complicated and it is rather difficult to understand the drawings. Further, in the production of the negative electrode 1, an aluminum plate and a lithium plate were laminated, but they were electrochemically alloyed in the presence of an electrolytic solution after battery assembly, and a lithium-aluminum alloy layer was formed on the aluminum plate. Has been formed. However, in FIG. 1, they are shown as an integral one without being divided. Further, the gasket 6 is deformed by inward tightening of the opening end of the metal outer can 4 and seals the gap between the opening end of the metal outer can 4 and the folded-back portion 5 a of the periphery of the sealing plate 5. Due to the sealed structure inside the battery, the details of the gasket 6 shown in FIG. 2 are not shown in FIG.

(Embodiment 2) A circular pedestal made of stainless steel and having an inverted L-shaped cross section is installed on the outer periphery of the negative electrode so that the outer peripheral edge of the separator is sandwiched between the sealing plate and the gasket and fixed. The battery was assembled in the same manner as in Example 1, except that the outer diameter was 6.5 mm and the height was 1.4 m shown in FIG.
m flat non-aqueous electrolyte battery was produced.

The structure of the battery of Example 2 will be described with reference to FIG. 3. The pedestal 7 is installed between the outer peripheral portion 1a of the negative electrode 1 and the gasket 6, and the outer peripheral edge portion 3 of the separator 3 is provided.
a is a folded-back portion 5 around the gasket 6 and the sealing plate 5.
It is sandwiched and fixed between a and. The other structure is almost the same as that of the battery of the first embodiment shown in FIG.

(Example 3) Diameter 4.8 mm, thickness 0.4
A positive electrode was produced in the same manner as in Example 1 except that the pellet had a shape of 8 mm and the capacity was 4.2 mAh.

The negative electrode was manufactured as follows. First of all, a stainless steel current collecting network with a diameter of 6.25 m
It is punched into a disk shape of m and resistance-welded to the inner bottom surface of a stainless steel outer can (material: SUS444) having an outer diameter of 6.5 mm, and an aluminum plate 11 having a cross section shown in FIG. did. That is, the aluminum plate 11 has a diameter of 6.4 mm and a thickness of the outer peripheral portion 11a of 0.35.
It has a disk shape of mm and a recess 11b having a diameter of 5.2 mm is formed in the central portion. The thickness of the recess 11b of the aluminum plate 11 is 0.25 mm, that is, 71% of the thickness of the outer peripheral portion, and the diameter of the recess 11b is 81% of the outer diameter of the aluminum plate 11. Further, a disc-shaped lithium plate having a diameter of 4.7 mm and a thickness of 0.18 mm was placed in the recess 11b of the aluminum plate 11 to form a negative electrode having a capacity of 6.5 mAh.

Using the above positive electrode and negative electrode, the amount of electrolyte was 7.
A flat type non-aqueous electrolyte battery having an outer diameter of 6.5 mm and a height of 1.4 mm was produced in substantially the same configuration as in Example 1 except that the amount was 2 μl. The amount of the electrolytic solution with respect to the area of the facing surface of the negative electrode of this battery was 22 μl / cm ² .

(Comparative Example 1) A stainless steel current collector net was punched into a disc shape having a diameter of 4.0 mm, which was resistance-welded to the inner surface of the same sealing plate as in Example 1, and the current collector net had a diameter of 4.
A disc-shaped aluminum plate having a thickness of 0 mm and a thickness of 0.24 mm was press-bonded, and a diameter of 4.0 mm and a thickness of 0.
A 18 mm disc-shaped lithium plate is placed and the capacity is 4.7.
It was used as a negative electrode of mAh.

Then, the same procedure as in Example 1 was carried out except that a carbon paste was applied on the inner bottom surface of a metal outer can, the same positive electrode as that in Example 1 was placed, and 6 μl of an electrolytic solution was injected. 1 and an outer diameter of 6.
A flat non-aqueous electrolyte battery having a size of 5 mm and a height of 1.4 mm was produced. The amount of the electrolytic solution with respect to the area of the negative electrode facing surface of this battery was 48 μl / cm ² .

In the battery of Comparative Example 1, since the negative electrode 1 is housed in the sealing plate 5 as described above, the sealing plate 5 also serves as the negative electrode terminal, and the positive electrode 2 is the metal outer can 4. The metal outer can 4 also serves as the positive electrode terminal. Then, the lower part of the gasket 6 reaches the inner bottom surface of the metal outer can 4, and the volume of the gasket 6 occupied in the battery is larger than that of the batteries of Examples 1 to 3, and the volume occupied by the electrodes is correspondingly increased. It's getting less. Further, the gasket 6 used in the battery of Comparative Example 1 has a convex portion to which the curved surface 6a of the outer peripheral corner portion as shown in FIG. 2 and the upper end of the folded-back portion 5a of the peripheral portion of the sealing plate 5 can be caught. 6c
Are not provided.

In the battery of Comparative Example 1, the same positive electrode as in Example 1 was used to increase the capacity. Therefore, the filling amount of the negative electrode had to be reduced by the amount of the filling amount of the positive electrode, and therefore, The ratio of the negative electrode capacity to the positive electrode capacity (negative electrode capacity / positive electrode capacity) was a small value of 1.18.

Comparative Example 2 Diameter 4.8 mm, Thickness 0.3
Pressure molded into 9 mm pellets with a capacity of 3.4 mAh
Positive electrode, diameter 4.0 mm, thickness 0.28 mm
The diameter is 4.0m on the aluminum plate punched in the shape of
m, and a 0.2 mm thick disc-shaped lithium plate was placed,
A flat non-aqueous electrolyte battery having an outer diameter of 6.5 mm and a height of 1.4 mm was produced in the same manner as in Comparative Example 1 except that a negative electrode having a capacity of 5.2 mAh was used. The ratio of the negative electrode capacity to the positive electrode capacity of the battery of Comparative Example 2 (negative electrode capacity / positive electrode capacity) was 1.53.

The battery of Comparative Example 2 had a ratio of the negative electrode capacity to the positive electrode capacity (negative electrode capacity / positive electrode capacity) of Examples 1 to 3.
The filling amount of the positive electrode and the negative electrode is adjusted so as to be approximately the same as that of the battery.

A load resistance of 270 kΩ was connected to the batteries of Examples 1 to 3 and Comparative Examples 1 and 2, and the discharge capacity until the battery voltage dropped to 2.0 V was measured. In addition, a charge / discharge cycle test was performed under the following conditions to check the number of cycles that can be charged / discharged. That is, charging is 2.4 kΩ
Was connected for 15 hours, and a power supply voltage of 3.25V was applied, and discharging was performed for 15 hours. A discharging resistance of 27 kΩ was connected for 16 hours. Then, the cycle life was judged from the battery voltage 11 hours after the start of discharge, and the life of the battery was determined when this voltage became lower than 2V. Then, the number of cycles at that time was defined as the number of cycles capable of charging and discharging. The measurement results are shown in Table 1 together with the ratio of the negative electrode capacity to the positive electrode capacity and the amount of the electrolytic solution with respect to the area of the facing surface of the negative electrode.
However, in Table 1, the ratio of the negative electrode capacity to the positive electrode capacity is shown by the capacity ratio (negative electrode capacity / positive electrode capacity).

[0065]

[Table 1]

As shown in Table 1, the batteries of Examples 1 to 3 had a large discharge capacity, a large number of chargeable and dischargeable cycles, and excellent cycle characteristics. That is, in the batteries of Examples 1 to 3 of the present invention, the positive electrode was arranged on the side of the sealing plate, the negative electrode was arranged on the side of the metal outer can, and the outer peripheral portion of the negative electrode was placed between the inner bottom surface of the metal outer can and the gasket. By arranging, it is possible to increase the capacity of the negative electrode without decreasing the capacity of the positive electrode, suppress the deterioration of the negative electrode due to charge / discharge cycles, and even with a small size, high capacity, and a flat surface with excellent cycle characteristics. A non-aqueous electrolyte battery could be obtained. Further, in the batteries of Examples 1 to 3, the volume ratio of the gasket in the battery was smaller than that of the batteries of Comparative Examples 1 and 2, but no liquid leakage was observed even after repeated charging and discharging. .

On the other hand, in the battery of Comparative Example 1 in which the capacity was increased by the conventional structure, the number of cycles that can be charged and discharged was extremely reduced due to the rapid deterioration of the negative electrode during the charge and discharge cycles. In addition, in the battery of Comparative Example 2 in which the capacity ratio (negative electrode capacity / positive electrode capacity) was adjusted to the same level as the batteries of Examples 1 to 3 by adjusting the filling amounts of the positive electrode and the negative electrode, the discharge capacity was reduced, In addition, since the discharge depth in the charge / discharge cycle became deeper than that of the batteries of Examples 1 to 3, the number of chargeable / dischargeable cycles also decreased.

Next, by arranging a pedestal on the outer peripheral portion of the negative electrode and using a metal plate whose central portion is thinner than the outer peripheral portion for the negative electrode, how the battery sealing performance changes. I checked. That is, 100 flat non-aqueous electrolyte batteries of each of Examples 1 to 3 were used, left for 20 days in an environment of 85 ° C. and a humidity of 90%, and subjected to a liquid leakage resistance test under high temperature and high humidity. It was The results are summarized in Table 2 as the number of batteries in which leakage was observed.

[0069]

[Table 2]

As shown in Table 2, the battery of Example 2 in which a pedestal was arranged on the outer peripheral portion of the negative electrode and the battery of Example 3 in which an aluminum plate having a recessed portion in the central portion was used were 100 pieces tested. No leakage was observed in any of the batteries of Example 1, but in the battery of Example 1 in which lithium was only placed on a flat plate of aluminum, leakage was observed in 15 of 100 batteries used in the test. Was recognized. In order to investigate the cause of the leakage, the batteries of Examples 1 to 3 were disassembled after the leakage resistance test and the cross section of the battery was observed. It was found that the lithium alloy layer was formed thicker in some parts than in other parts, and the gasket was deformed at that part and the electrolytic solution leaked out. The uneven formation of the lithium alloy layer on the outer peripheral portion of the aluminum plate is caused by the step of disposing the lithium plate on the aluminum plate and the center of the aluminum plate does not completely coincide with the center of the lithium plate. It is considered that this occurred because the lithium plate was placed at a position slightly deviated from the center of. However, in the battery of Example 2 and the battery of Example 3,
The non-uniform formation of the lithium alloy layer as described above was not recognized, and the formation of the lithium alloy layer on the outer peripheral portion of the aluminum plate was effectively suppressed. By suppressing the formation of the above, even if variations occur in the process of assembling the battery, it is possible to maintain the liquid leakage resistance of the battery in a good condition and provide a highly reliable flat non-aqueous electrolyte battery.

(Example 4) Diameter 9.3 mm, thickness 0.6
A positive electrode was produced in the same manner as in Example 1 except that it was in the form of pellets of 4 mm and had a capacity of 18.3 mAh.

The outer diameter of the outer can is 12.0 mm,
10.5 mm diameter collector net, 11.7 mm diameter and 0.35 mm thick aluminum plate, and 9.5 m diameter
Example 1 except that lithium plates each having a thickness of 0.19 mm and a thickness of 0.19 mm were used and the capacity was set to 27.8 mAh.
A negative electrode was prepared in the same manner as in.

Example 1 was obtained by combining the above positive electrode and negative electrode.
Similarly to the above, a flat non-aqueous electrolyte battery having an outer diameter of 12.0 mm and a height of 2.0 mm was assembled. The negative electrode capacity / positive electrode capacity of this battery was 1.52.

Example 5 Diameter 16.1 mm, thickness 0.
A positive electrode was produced in the same manner as in Example 1 except that the pellet had a shape of 98 mm and the capacity was 78.6 mAh.

The outer diameter of the outer can is 20.0 mm,
18.8 mm diameter collector net, 19.0 mm diameter and 0.7 mm thick aluminum plate, and 16.0 m diameter
A negative electrode was produced in the same manner as in Example 1 except that lithium plates each having a thickness of 0.29 mm and a thickness of 120.3 mAh were used.

Example 1 was prepared by combining the above positive electrode and negative electrode.
Similarly to the above, a flat non-aqueous electrolyte battery having an outer diameter of 20.0 mm and a height of 3.2 mm was assembled. The negative electrode capacity / positive electrode capacity of this battery was 1.53.

(Comparative Example 3) Diameter 8.9 mm, thickness 0.6
A positive electrode was produced in the same manner as in Comparative Example 2 except that it was in the form of pellets of 3 mm and had a capacity of 16.1 mAh.

A current collecting network having a diameter of 8.6 mm and a diameter of 9.
An aluminum plate having a thickness of 0 mm and a thickness of 0.35 mm, and
A negative electrode was produced in the same manner as in Comparative Example 2 except that lithium plates each having a diameter of 8.7 mm and a thickness of 0.2 mm were used and the capacity was set to 24.5 mAh.

The positive electrode and the negative electrode are combined to have an outer diameter of 1
Using an outer can of 2.0 mm, in the same manner as in Comparative Example 2,
A flat non-aqueous electrolyte battery having an outer diameter of 12.0 mm and a height of 2.0 mm was assembled. The negative electrode capacity / positive electrode capacity of this battery was 1.52.

(Comparative Example 4) Diameter 15.2 mm, thickness 0.
A positive electrode was produced in the same manner as in Comparative Example 2 except that it was in the form of pellets of 95 mm and had a capacity of 71.0 mAh.

A current collecting network having a diameter of 14.9 mm and a diameter of 1
Same as Comparative Example 2 except that an aluminum plate having a thickness of 5.0 mm and a thickness of 0.7 mm and a lithium plate having a diameter of 14.5 mm and a thickness of 0.32 mm were used, respectively, so that the capacity was 109.0 mAh. A negative electrode was produced.

The positive electrode and the negative electrode are combined to have an outer diameter of 2
Using a 0.0 mm outer can, in the same manner as in Comparative Example 2,
A flat non-aqueous electrolyte battery having an outer diameter of 20.0 mm and a height of 3.2 mm was assembled. The negative electrode capacity / positive electrode capacity of this battery was 1.54.

The batteries of Examples 4 and 5 had the same battery configuration as that of Example 1 and had a diameter of 12.0 m.
It is a flat type non-aqueous electrolyte battery with m and 20.0 mm.

The batteries of Comparative Example 3 and Comparative Example 4 had the same battery configuration as that of Comparative Example 2 and each had a diameter of 1
A flat non-aqueous electrolyte battery having a size of 2.0 mm and 20.0 mm.

With respect to the batteries of Example 4 and Comparative Example 3, a load voltage of 70 kΩ was connected and the battery voltage was 2.0.
The discharge capacity until it decreased to V was measured. Further, with respect to the batteries of Example 5 and Comparative Example 4 described above, a load resistance of 20 kΩ was connected and the discharge capacity until the battery voltage dropped to 2.0 V was measured. The measurement results are shown in Table 3 together with the discharge capacities of the batteries of Example 1 and Comparative Example 2. Table 3 shows the discharge capacities of the batteries of Examples 1, 4 and 5 and the corresponding discharge capacities of the batteries of Comparative Examples (Comparative Example 2, Comparative Example 3 and Comparative Example 4). Compare
The rate of increase [(discharge capacity of the example−discharge capacity of the comparative example) × 100 / discharge capacity of the comparative example] (%) is shown as the rate of increase of the discharge capacity.

[0086]

[Table 3]

As shown in Table 3, Example 1, Example 4,
The batteries of Example 5 and Comparative Examples 2 to 4 are designed so that the negative electrode capacity / the positive electrode capacity have substantially the same value, but the batteries of Example 1, Example 4 and Example 5 have the same comparison. The discharge capacity could be increased compared to the example battery. Further, the smaller the diameter of the battery, the greater the rate of increase in discharge capacity, and the greater the effect of the present invention when the diameter is 16 mm or less, the remarkable effect was obtained especially in the small battery having the diameter of 8 mm or less.

In the present invention, the lower limit of the diameter of the battery is not particularly limited, but a diameter of up to 2 mm is practical considering the ease of manufacturing.

Comparative Example 5 Diameter 6.1 mm, Thickness 0.3
A positive electrode was produced in the same manner as in Example 1 except that the pellet had a shape of 5 mm and the capacity was 4.9 mAh. Then, after applying a carbon paste onto the inner bottom surface of the same metal outer can as in Example 1, the positive electrode was placed there.

A positive electrode placed in this metal outer can and a negative electrode similar to Comparative Example 1 attached to the sealing plate were combined, and the outer diameter was 6.5 mm and the height was 1. A 4 mm flat non-aqueous electrolyte battery was assembled. That is, the battery of Comparative Example 5 is a battery in which the outer peripheral portion of the positive electrode is arranged between the inner bottom surface of the metal outer can and the gasket, and the battery of Example 1 of the present invention has the arrangement of the positive electrode and the negative electrode. It is the reverse.

The negative electrode capacity / positive electrode capacity of this battery was 0.96.
Therefore, the capacity of the negative electrode became smaller than the capacity of the positive electrode. Therefore, the battery of Comparative Example 5 showed a larger capacity (4.0 mAh) than the battery of Example 1 when the discharge capacity was measured under the same conditions as the battery of Example 1, but the discharge depth of the negative electrode was Becomes too deep and the negative electrode deteriorates, so that the charge / discharge cycle characteristics were inferior to those of the battery of Comparative Example 1.

[0092]

As described above, in the present invention, the sealing plate also serves as the positive electrode terminal, the metal outer can also serves as the negative electrode terminal, and the outer peripheral portion of the negative electrode is arranged between the inner bottom surface of the metal outer can and the gasket. With such a structure, it was possible to provide a flat non-aqueous electrolyte battery having a high capacity and excellent cycle characteristics. Particularly, when the negative electrode is formed by forming a lithium alloy layer on a metal plate, by suppressing the formation of the lithium alloy layer on the outer peripheral portion of the metal plate, a highly reliable battery with excellent liquid leakage resistance can be obtained. Can be

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view schematically showing a flat non-aqueous electrolyte battery of Example 1 of the present invention.

FIG. 2 is a cross-sectional view schematically showing a main part of a gasket used in the battery of Example 1.

FIG. 3 is a partial cross-sectional view schematically showing a flat non-aqueous electrolyte battery of Example 2 of the present invention.

FIG. 4 is a cross-sectional view schematically showing an aluminum plate used as a negative electrode of the flat type nonaqueous electrolyte battery of Example 3 of the present invention.

FIG. 5 is a partial cross-sectional view schematically showing a flat non-aqueous electrolyte battery of Comparative Example 1 corresponding to a conventional battery.

[Explanation of symbols]

1 negative electrode 1a outer peripheral part 2 positive electrode 3 separator 3a outer peripheral portion 4 metal exterior cans 5 Seal plate 5a Folded part 6 gasket 6a curved surface 6b C surface 6c convex part 7 pedestal 11 Aluminum plate 11a outer peripheral part 11b recess

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Kenichi Sano             Hitachi Ma, 1-88, Torora, Ibaraki City, Osaka Prefecture             Within Kucsel Co., Ltd. F-term (reference) 5H011 AA03 AA17 BB04 CC06 DD06                       KK01 KK02                 5H021 AA06 CC02 CC04                 5H029 AJ03 AJ05 AJ15 AK03 AL12                       AM03 AM05 AM07 BJ03 DJ02                       DJ04 DJ15 EJ01 EJ12 HJ04                       HJ19

Claims (9)

[Claims] 1. A negative electrode, a positive electrode and a non-aqueous electrolyte are provided inside by providing a sealing plate, a metal outer can and a gasket interposed therebetween, and tightening an opening end portion of the metal outer can inward. A flat non-aqueous electrolyte battery which is hermetically sealed, wherein the sealing plate also serves as a positive electrode terminal, the metal outer can also serves as a negative electrode terminal, and the outer peripheral portion of the negative electrode is provided between the inner bottom surface of the metal outer can and the gasket. A flat non-aqueous electrolyte battery characterized by being arranged. 2. The flat non-aqueous electrolyte battery according to claim 1, wherein the metal outer can has a diameter of 2 to 16 mm. 3. The flat non-aqueous electrolyte battery according to claim 1, wherein the metal outer can has a diameter of 2 to 8 mm. 4. The flat non-aqueous electrolyte battery according to claim 1, wherein a lithium alloy or an oxide of an element capable of alloying with lithium is used for the negative electrode. 5. The negative electrode is one in which a lithium alloy layer is formed on a metal plate, and in forming the lithium alloy layer, a metal plate having a central portion thinner than an outer peripheral portion is used. The flat non-aqueous electrolyte battery described in. 6. The metal plate is a metal plate having a recess in the center, and the diameter of the recess is 70 to 90 of the outer diameter of the metal plate.
%, And the flat nonaqueous electrolyte battery according to claim 5, wherein a lithium alloy layer is formed by bringing lithium into contact with the concave portion of the metal plate. 7. The flat non-aqueous electrolyte battery according to claim 6, wherein the thickness of the recess of the metal plate is 25 to 95% of the thickness of the outer peripheral portion. 8. The flat type non-aqueous electrolyte battery according to claim 1, wherein the ratio of the capacity of the negative electrode to the capacity of the positive electrode is 1.2 or more. 9. The flat non-aqueous electrolyte battery according to claim 1, wherein a separator having a multilayer structure is interposed between the negative electrode and the positive electrode.