JP2011159413A - Coin-shaped battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem in which there is a possibility to generate internal short circuit in case of decrease of a volume of an anode and increase of a volume of a cathode by discharging, in a coin-shaped battery. <P>SOLUTION: In the coin-shaped battery 1, a power generation element made by arranging a cathode 10 and an anode 11 made of lithium metal in opposition through a separator 12 is housed with electrolyte in a battery case 13 formed in a shape of a cylinder with a bottom, a sealing plate 14 is arranged through a gasket 15 at an opening of the battery case 13, and is sealed by caulking. The separator 12 includes an extended part 12a toward a cylindrical direction, and a length B from a position corresponding to a lower surface of a flange part 14c of the sealing plate 14 in the extended part 12a to a lower end of the extended part is made larger than a thickness A of the anode. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a coin-type battery used for various portable electronic devices and the like.

  Coin-type batteries are also called button-type batteries and flat-type batteries, and when small size is required such as wristwatches and keyless entry by taking advantage of their small and thin characteristics, or long-term backup such as memory backup for OA equipment and FA equipment. Widely used when required. It is also used for various meters and power supplies for measuring machines, and its use is expanding. In recent years, there has been a demand for use in more severe environments such as automobiles and industrial equipment, and at the same time, improvements for further higher performance are being promoted.

  A coin-type battery is formed by placing a positive electrode and a negative electrode opposite to each other through a separator in a battery case, filling the electrolyte, and crimping the opening of the battery case with a sealing plate via a gasket. . (For example, see Patent Document 1)

Republication 02/013290

  In such a coin-type battery, the negative electrode gradually disappears with the discharge during use, and the positive electrode gradually expands. Along with this, the separator also approaches the sealing plate side, and at the end of discharge, the positive electrode comes close to and faces the inner surface of the negative electrode side sealing plate via the separator. At this time, if the tip of the separator rises higher than the bent portion of the sealing portion on the inner surface of the negative electrode side sealing plate, the bent portion of the outer peripheral portion of the positive electrode and the inner surface of the negative electrode side sealing plate may be short-circuited. There is.

  It is an object of the present invention to provide a highly reliable coin-type battery that does not cause an internal short circuit even when the negative electrode disappears due to discharge and the positive electrode expands.

  In order to solve the above-mentioned problems, a coin-type battery according to the present invention stores a power generation element in which a positive electrode and a negative electrode made of lithium metal are arranged opposite to each other with a separator in a battery case formed in a bottomed cylindrical shape together with an electrolytic solution. And a coin-type battery in which a sealing plate is disposed in the opening of the battery case via a gasket and sealed by caulking, and the sealing plate has a bottomed cylindrical shape opposite to the battery case, A flange portion is formed in the opening, and a cylindrical extension portion and a folded portion are formed at a tip portion of the flange portion, and the battery case is at least smaller than the inner diameter of the extension portion around the bottom surface. A rising portion having an outer diameter and formed upward from the bottom surface and a crimping portion extending further from the rising portion are formed, and the gasket is cut when crimped. In the coin-type battery disposed so as to be compressed between the crimped portion deformed in a U-shape and the flange portion, the extending portion, and the folded portion, the separator has an extending portion in the cylindrical direction. The length from the position corresponding to the lower surface of the flange portion of the sealing plate in the extension portion to the lower end of the extension portion is larger than the thickness of the negative electrode.

According to the present invention, a power generation element in which a positive electrode and a negative electrode made of lithium metal are disposed opposite to each other with a separator in a battery case is stored together with an electrolyte, and a sealing plate connected to the negative electrode is connected to the battery case via a gasket. In the coin-type battery sealed in the opening, even when the negative electrode disappears and the positive electrode expands due to discharge, a highly reliable coin-type battery in which the positive electrode and the sealing plate are not short-circuited can be provided.

1 is a half sectional view schematically showing a configuration of a coin-type battery according to an embodiment of the present invention. The half sectional view which shows typically the structure of the coin-type battery which is other embodiment of this invention Half sectional view schematically showing the configuration of a coin-type battery of a comparative example Half sectional view schematically showing the configuration of a coin-type battery of another comparative example

  According to a first aspect of the present invention, in a battery case formed in a bottomed cylindrical shape, a power generation element in which a positive electrode and a negative electrode made of lithium metal are arranged opposite to each other with a separator interposed therebetween is accommodated together with an electrolyte, A coin-type battery in which a sealing plate is arranged via a gasket and sealed by caulking, and the sealing plate is a bottomed cylindrical shape opposite to the battery case, and a flange portion is formed in the opening. A cylindrical portion extending in the front end portion of the flange portion and a folded portion thereof, and the battery case has an outer diameter smaller than an inner diameter of the extending portion around the bottom surface of the battery case. A rising portion formed upward from the bottom surface and a crimping portion further extending from the rising portion are formed, and the gasket was deformed into a U-shaped cross section when crimped. In the coin-type battery arranged to be compressed between the squeeze portion and the flange portion, the extension portion, and the folded portion, the separator has an extension portion in a cylindrical direction, and the extension portion in the extension portion The coin-type battery is characterized in that the length from the position corresponding to the lower surface of the flange portion of the sealing plate to the lower end of the extension portion is larger than the thickness of the negative electrode.

  With this configuration, even if the negative electrode at the end of discharge almost disappears and the positive electrode expands and comes close to the sealing plate side, the presence of the extension of the separator causes the separator between the inner surface of the bent portion of the sealing plate and the positive electrode. It is possible to provide a highly reliable coin-type battery in which the extension is always present and the positive electrode and the sealing plate are not short-circuited.

  According to a second aspect of the present invention, there is provided a coin-type battery according to the first aspect, wherein the lower end of the extension of the separator is located below the bottom surface of the gasket and above the inner bottom surface of the battery case.

  With this configuration, even when the negative electrode disappears at the end of discharge and the positive electrode expands, the positive electrode and the sealing plate do not short-circuit, and the presence of the rising part of the battery case also prevents the tip of the separator from being sealed even in the initial stage of discharge. In this case, it is possible to prevent the occurrence of a leakage path due to biting between the gasket and the battery case, and it is possible to provide a highly reliable coin-type battery.

  Embodiments of the present invention will be described below. The following embodiment is an example embodying the present invention, and does not limit the technical scope of the present invention.

  FIG. 1 is a half sectional view schematically showing a configuration of a coin-type battery 1 which is one of the embodiments of the present invention. The coin-type battery 1 is a coin-type battery including a positive electrode 10, a negative electrode 11, a separator 12, a battery case 13 on the positive electrode side, a sealing plate 14 on the negative electrode side, a gasket 15, and a non-aqueous electrolyte (not shown).

  The positive electrode 10 includes a positive electrode active material, a conductive material, and a binder, and is provided to face the negative electrode 11 with a separator 12 interposed therebetween.

  As the positive electrode active material, those commonly used in the field of lithium primary batteries can be used, and among them, fluorinated graphite, metal oxides and the like are preferable. As the fluorinated graphite, those represented by the chemical formula CF (0.8 ≦ x ≦ 1.1) are preferable. Fluorinated graphite is excellent in terms of long-term reliability, safety, and high-temperature stability. Fluorinated graphite is obtained by fluorinating petroleum coke, artificial graphite and the like. Examples of the metal oxide include manganese dioxide and copper oxide. A positive electrode active material can be used individually by 1 type or in combination of 2 or more types.

  As the conductive material, those commonly used in the field of lithium primary batteries can be used. For example, carbon black such as acetylene black and ketjen black, and graphite such as artificial graphite can be used. A conductive material can be used individually by 1 type or in combination of 2 or more types. As the binder, those commonly used in the field of lithium primary batteries can be used. For example, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), modified PVDF, tetrafluoroethylene-hexafluoropropylene copolymer Copolymer (FEP), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-chlorotrifluoroethylene copolymer, ethylene-tetrafluoroethylene copolymer Polymer (ETFE resin), vinylidene fluoride-pentafluoropropylene copolymer, propylene-tetrafluoroethylene copolymer, ethylene-chlorotrifluoroethylene copolymer (ECTFE), vinylidene fluoride-hexafluoropropylene Pyrene - fluororesin such as tetrafluoroethylene copolymer, styrene-butadiene rubber (SBR), modified acrylonitrile rubber, ethylene - like acrylic acid copolymer.

  A binder can be used individually by 1 type or in combination of 2 or more types.

  The negative electrode 11 contains lithium or a lithium alloy, and is provided so as to face the positive electrode 10 with the separator 12 interposed therebetween. As the lithium alloy, those commonly used in the field of lithium primary batteries can be used, and examples thereof include Li—Al, Li—Sn, Li—NiSi, and Li—Pb.

  The separator 12 is not particularly limited as long as it can prevent the short-circuit between the positive electrode 10 and the negative electrode 11 as long as it can be used in the coin-type battery field. It is desirable that it has excellent properties and does not become an ion migration resistance. Typical materials include polyolefin, polyester, polycarbonate, polyacrylate, polymethacrylate, polyamide, polytetrafluoroethylene, polyvinylidene fluoride, polysulfone, polyethersulfone, polybenzimidazole, polyetheretherketone, polyphenylene, etc. Examples of the shape include a nonwoven fabric and a microporous film.

  The separator 12 has an extension part 12a in the cylindrical direction, and the length B from the position corresponding to the lower surface of the flange part 14c of the sealing plate 14 to the lower end of the extension part 12a in the extension part 12a is the thickness A of the negative electrode 11. Greater than. The extension 12a prevents a short circuit between the positive electrode 10 and the inner surface of the sealing plate 14.

  The nonaqueous electrolytic solution contains a solute and a nonaqueous solvent.

As the solute, those commonly used in the field of lithium primary batteries can be used. For example, lithium hexafluorophosphate (LiPF ₆ ), lithium borofluoride (LiBF ₄ ), lithium trifluoromethanesulfonate (LiCF ₃ SO ₃ ) , Lithium-bispentafluoroethylsulfonic acid imide (LiN (SO ₂ C ₂ F ₅ ) ₂ ), lithium bis (trifluoromethylsulfonyl) imide (LiN (CF ₃ SO ₂ ) ₂ ), lithium tris (trifluoromethylsulfonyl) ) Methide (LiC (CF ₃ SO ₂ ) ₃ ), lithium perchlorate (LiClO ₄ ) and the like. Solutes can be used alone or in combination of two or more.

  As the non-aqueous solvent, those commonly used in the field of lithium primary batteries can be used. For example, γ-butyrolactone (γ-BL), γ-valerolactone (γ-VL), propylene carbonate (PC), ethylene carbonate ( EC), cyclic carbonates such as 1,2-dimethoxyethane (DME), 1,2-diethoxyethane (DEE), 1,3-dioxolane, dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), N, N-dimethylformamide, tetrahydrofuran, 2-methyltetrahydrofuran, dimethylsulfoxide, formamide, acetamide, dimethylformamide, dioxolane, acetonitrile, propylnitrile, nitromethane, ethyl monoglyme, trimethoxyme Emissions, dioxolane derivatives, sulfolane, methyl sulfolane, propylene carbonate derivatives, tetrahydrofuran derivatives. A non-aqueous solvent can be used individually by 1 type or in combination of 2 or more types.

  The solute concentration in the nonaqueous electrolytic solution is not particularly limited, but is preferably 0.5 to 1.5 mol / L. If the solute concentration is less than 0.5 mol / L, the discharge characteristics at room temperature or the discharge characteristics after long-term storage may be deteriorated. If the solute concentration exceeds 1.5 mol / L, the increase in viscosity and decrease in ionic conductivity of the nonaqueous electrolyte solution may become prominent under a low temperature environment of about −40 ° C.

  The battery case 13 also serves as a positive electrode current collector and a positive electrode terminal. The sealing plate 14 also serves as a negative electrode current collector and a negative electrode terminal. The gasket 15 is ring-shaped and has a L-shaped cross section, and mainly insulates the battery case 13 and the sealing plate 14. As the battery case 13, the sealing plate 14, and the gasket 15, those commonly used in the field of lithium primary batteries can be used. For the battery case 13 and the sealing plate 14, for example, stainless steel can be used. For the gasket 15, for example, a synthetic resin such as polypropylene can be used.

  The battery case 13 has an upward rising portion 13a at the peripheral portion, the sealing plate 14 has a flange portion 14c at the opening, and a cylindrical extending portion at the tip portion of the flange portion 14c. 14d and the folded portion 14e are formed, and the crimped portion 13b of the battery case 13 and the flange portion 14c of the sealing plate 14, the extending portion 14d, the folded portion 14e, and the gasket 15 are caulked and sealed.

  FIG. 2 is a half cross-sectional view schematically showing the configuration of a coin-type battery 1 according to another embodiment of the present invention.

  In FIG. 2, the thickness of the negative electrode 11 is larger than that in FIG. In such a case, in order for the length B from the position corresponding to the lower surface of the flange portion 14c of the sealing plate 14 to the lower end of the extension portion 12a in the extension portion 12a of the separator 12 to be larger than the thickness A of the negative electrode 11, the extension of the separator 12 The lower end of the portion 12a is positioned below the bottom surface 15a of the gasket and above the inner bottom surface 13c of the battery case, that is, in the range of C in FIG.

  Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples.

Example 1
1) Preparation of positive electrode 100 parts by weight of fluorinated graphite (positive electrode active material) and 10 parts by weight of acetylene black (conductive material) were dry mixed, and methanol was added to the obtained dry mixture and kneaded. In this kneaded product,
5 parts by weight of styrene butadiene rubber (binder) was added and further kneaded, and the obtained kneaded product was dried and pulverized to prepare a powdery positive electrode mixture. This positive electrode mixture was filled in a cylindrical mold having a diameter of 17.0 mm and pressure-molded to produce a disk-shaped positive electrode 10.

2) Production of negative electrode Lithium metal was used for the negative electrode active material. A lithium metal foil was punched out to form a disc-shaped negative electrode 11 and pressed onto the inner surface of the sealing plate 14 equipped with the gasket 15.

3) Separator A polypropylene nonwoven fabric having a thickness of 100 μm was punched out into a circular shape and molded into a cup shape to produce a separator 12. At this time, as shown in FIG. 1, the length B from the position corresponding to the lower surface of the flange portion 14c of the sealing plate 14 in the extension portion 12a of the cup-shaped separator to the lower end of the extension portion is larger than the thickness A of the negative electrode 11, and The diameter of the separator 12 was adjusted so that the lower end of the extension was positioned above the bottom surface of the gasket 15.

4) Preparation of non-aqueous electrolyte A solution obtained by dissolving lithium borofluoride in γ-butyrolactone at a ratio of 1 mol / L was used.

5) Assembling the battery The sealing plate 14 to which the negative electrode 11 is pressure-bonded is covered with the tip of the cup-shaped separator 12 facing the opening of the sealing plate 14, and the negative electrode 11 and the positive electrode 10 face each other. After placing the positive electrode 10 in this manner, a nonaqueous electrolytic solution was injected into the sealing plate, and the positive electrode 10 and the separator 12 were impregnated with the nonaqueous electrolytic solution. Next, the battery case 13 is attached to the sealing plate 14, and the peripheral edge of the battery case 13 is caulked to the gasket 15 attached to the sealing plate 14, so that the coin-type battery 1 (diameter 24.5 mm, thickness 5) of the present invention is used. 0.0 mm). The size of the battery is 24.5 mm in diameter and 5.0 mm in height. The assembly process was performed in dry air with a dew point of −40 ° C. or lower.

(Example 2)
As shown in FIG. 2, the length B from the position corresponding to the lower surface of the flange portion 14c of the sealing plate 14 in the extension portion 12a of the cup-shaped separator 12 to the lower end of the extension portion 12a is larger than the thickness A of the negative electrode 11, and In the same manner as in Example 1, except that the diameter of the separator 12 was adjusted and punched so that the lower end of the extended portion 12a of the separator 12 was positioned below the bottom surface 15a of the gasket and above the inner bottom surface 13c of the battery case. A coin-type battery of Example 2 was produced.

(Comparative Example 1)
As shown in FIG. 3, the length B from the position corresponding to the lower surface of the flange 14 c of the sealing plate 14 in the extension 12 a of the cup-shaped separator 12 to the lower end of the extension is smaller than the thickness A of the negative electrode 11. A coin-type battery of Comparative Example 1 was produced in the same manner as in Example 1 except that the diameter of the separator 12 was adjusted and punched out.

(Comparative Example 2)
As shown in FIG. 4, when the battery case 13 does not have the rising portion 13a and the negative electrode 11 is thick as in the second embodiment, the flange portion of the sealing plate 14 in the extension portion 12a of the separator 12 is used. Comparative Example 2 in the same manner as in Example 1 except that the diameter of the separator 12 was adjusted and punched out so that the length B from the position corresponding to the lower surface of 14c to the lower end of the extension 12a was larger than the thickness A of the negative electrode 11. A coin-type battery was manufactured.

For the coin batteries obtained in Examples 1 and 2 and Comparative Examples 1 and 2, the test temperature was 20 ° C.,
After discharging to a discharge load of 15 kΩ and a final voltage of 2.0 V, a vibration test was performed. The number of voltage drops in the vibration test is shown in (Table 1).

  As can be seen from Table 1, in the coin batteries of Examples 1 and 2 and Comparative Example 2 of the present invention, no voltage drop occurred in the vibration test. On the other hand, in Comparative Example 1, a voltage drop occurred in the vibration test.

  In Examples 1 and 2 and Comparative Example 2 of the present invention, even if the positive electrode 10 expands due to discharge, the extended portion 12a of the separator 12 is always between the outer peripheral portion of the positive electrode 10 and the sealing plate 14 during discharge. In the comparative example 1, from the position corresponding to the negative electrode thickness A in FIG. 2 and the lower surface of the flange portion 14c of the sealing plate 14 in the separator extension 12a, the positive electrode 10 and the inner surface of the sealing plate 14 are not short-circuited. The relationship with the length B to the lower end of the extension portion is A> B. When the negative electrode 11 disappears and the positive electrode 10 expands at the end of discharge, the tip of the separator 12 is the inner surface of the sealing plate 14 on the negative electrode side. It is considered that the outer peripheral surface of the positive electrode 10 and the inner surface of the sealing plate 14 may be short-circuited.

  Next, regarding the coin batteries obtained in Examples 1 and 2 and Comparative Examples 1 and 2, the number of occurrences of liquid leakage when assembled is shown in Table 2.

  As can be seen from Table 2, in the coin-type batteries of Examples 1 and 2 and Comparative Example 1 of the present invention, no leakage occurred during assembly, but in Comparative Example 2, leakage occurred during assembly. It was.

  This is because in Example 1 and Comparative Example 1 of the present invention, the lower end of the extension of the separator 12 is located above the bottom surface of the gasket 15, so that the separator 12 is caught between the gasket 15 and the battery case 13. There is no. In Example 2, the lower end of the extended portion of the separator 12 is positioned below the bottom surface 15a of the gasket. However, the separator 12 is also prevented from moving to the crimped portion by the rising portion 13a of the battery case 13. 15 and the battery case 13 are not caught.

  On the other hand, in Comparative Example 2, since there is no rising portion 13a of the battery case 13, the separator 12 may bite between the gasket 15 and the battery case 13, and it is considered that a leak occurred as a leakage path. .

According to the present invention, a power generation element in which a positive electrode and a negative electrode made of lithium metal are disposed opposite to each other with a separator in a battery case is stored together with an electrolyte, and a sealing plate connected to the negative electrode is connected to the battery case via a gasket. In the coin-type battery sealed in the opening, it is possible to provide a highly reliable coin-type battery in which the outer peripheral portion of the positive electrode and the sealing plate are not short-circuited when the positive electrode expands due to discharge, which is industrially useful. is there.

DESCRIPTION OF SYMBOLS 1 Coin type battery 10 Positive electrode 11 Negative electrode 12 Separator 12a Extension part 13 Battery case 13a Standing part 13c Inner bottom face of battery case
13b Caulking part 14 Sealing plate 14a Falling part 14b Folding part 14c Flange part 14d Extension part 14e Folding part 15 Gasket 15a Bottom surface of gasket

Claims (2)

In the battery case formed in a bottomed cylindrical shape, a power generation element in which a positive electrode and a negative electrode made of lithium metal are arranged to face each other via a separator is stored together with an electrolytic solution, and a sealing plate is attached to the opening of the battery case via a gasket. A coin-type battery sealed by caulking, wherein the sealing plate has a bottomed cylindrical shape opposite to the battery case, and has a flange portion at an opening thereof, and is provided at a tip portion of the flange portion. An extension part in the cylindrical direction and a folded part thereof are formed, and the battery case has an outer diameter smaller than an inner diameter of the extension part around the bottom surface and is formed upward from the bottom surface. A rising portion and a caulking portion that extends further from the rising portion are formed, and when the gasket is caulked, the caulking portion deformed into a U-shaped cross section, the flange portion, In the coin-type battery disposed so as to be compressed between the folded portion and the folded portion, the separator has an extension portion in the cylindrical direction, and corresponds to the lower surface of the flange portion of the sealing plate in the extension portion. A coin-type battery characterized in that the length from the position to the lower end of the extension is larger than the thickness of the negative electrode. The coin-type battery according to claim 1, wherein a lower end of the extension portion of the separator is located below the bottom surface of the gasket and above the inner bottom surface of the battery case.