JP5152886B2 - Coin battery - Google Patents

Description

  The present invention relates to a coin-type battery, and more particularly to a coin-type battery having excellent corrosion resistance performance of a battery can during long-term storage.

  In coin-type batteries represented by manganese dioxide-lithium batteries, stainless steel plates are generally used for both the sealing plate and the outer can. Since stainless steel sheet has high strength, it can secure a certain level of strength even if the sealing plate and outer can are made thin, and problems such as leakage and battery deformation are unlikely to occur. It is preferable in that it can be achieved.

  In addition, when a coin-type battery is used as a power source for an electronic device or the like, the terminal installed in the electronic device and the battery sealing plate or the outer can may be energized by point contact. Alternatively, the outer surface of the outer can is generally subjected to a plating process such as Ni plating in order to reduce contact resistance.

  However, the coin-type battery seals the opening of the outer can by caulking, and both the sealing plate and the outer can have a large deformation region at the end, so the Ni plating layer provided on the outer surface, etc. May crack or peel off. However, since stainless steel has high corrosion resistance, it is also preferable in that the problem of corrosion of the outer can does not occur even when the Ni plating layer is cracked or peeled off.

  The stainless steel plate as the material for the coin-type battery sealing plate and the outer can has the above-mentioned advantages, but also has a demerit that the manufacturing cost of the battery increases because of the high price.

  On the other hand, for example, a technique in which an outer can of a cylindrical battery is formed of a Ni-plated steel plate having an Fe—Ni diffusion layer has also been proposed (Patent Document 1). Since such a Ni-plated steel sheet is cheaper than stainless steel, there is a possibility that the manufacturing cost can be reduced by replacing the material of the sealing plate and the outer can with the above-described Ni-plated steel sheet in the coin-type battery. is there.

JP 2005-85480 A

  However, according to the study by the present inventors, when a Ni-plated steel sheet as disclosed in Patent Document 1 is used for a sealing plate or an outer can of a coin-type battery, the sealing plate or the outer can is rusted and has an appearance. It has been found that problems such as defects occur and leakage occurs.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a coin-type battery having a sealing plate made of a steel plate and suppressing the occurrence of rust and leakage on the outer surface. Is to provide.

  In the coin-type battery of the present invention that can achieve the above object, the sealing plate having the upper wall and the curved portion curved downward from the upper wall and the opening of the outer can are caulked through a gasket. In the sealing plate, at least the outer surface of the steel substrate is Ni (nickel) plated, and between the Ni plated portion and the steel substrate portion, Fe (iron), Ni, and Are composed of Ni-plated steel plates in which regions diffused from each other, and the ratio R / θ between the radius of curvature R (mm) of the curved portion of the sealing plate and the internal angle θ (°) of the curved portion is 0.0060 to 0.0160.

  The Ni-plated steel plate constituting the sealing plate is preferably obtained by heat-treating a steel plate having a matte Ni-plated layer. In this case, the thickness of the matte Ni-plated layer is 2 It is recommended to be 10 μm.

  In the coin battery of the present invention, the outer can is preferably made of stainless steel, and it is recommended that the outer can be provided with a negative electrode having lithium or a lithium alloy.

  In the battery industry, a flat battery with a diameter larger than the height is called a coin-type battery or a button-type battery, but there is a clear gap between the coin-type battery and the button-type battery. There is no difference, and the coin type battery of the present invention does not exclude what is called a button type battery, and such a battery called a button type battery is also included in the scope of the coin type battery of the present invention. Moreover, not only a flat planar shape but also a polygonal flat battery such as a quadrangle is included.

  According to the present invention, by applying a specific Ni-plated steel plate to the constituent material of the sealing plate, the productivity is reduced by reducing the cost at the time of manufacture compared to a coin-type battery having a conventional stainless steel sealing plate. It is possible to provide a coin-type battery that is enhanced and also has suppressed the occurrence of rust and leakage on the outer surface.

  In a cylindrical battery as disclosed in Patent Document 1, the outer can is usually covered with an outer member (such as a film on which the name of the battery is printed), so that it is hardly affected by the external environment. However, since the sealing plate and the outer can of the coin-type battery may be energized by direct point contact as described above, the material cannot be covered with a film or the like, and is easily affected by moisture from the outside. Therefore, for example, at places where deformation is great when processing into a sealing plate or an outer can, the Ni plating layer is peeled off or cracked, and the underlying steel substrate is likely to be exposed. It is considered that rust is generated.

  Therefore, further investigation was carried out on the sealing plate with fewer exposed parts to the outside of the battery using a specific Ni-plated steel sheet, and the coin-type battery was completed while processing the sealing plate to prevent rusting. As a result, it was found that liquid leakage is relatively easy to occur.

  In view of the above circumstances, in the present invention, the sealing plate is made of a specific Ni-plated steel plate, and peeling and cracking of the Ni-plated portion are suppressed, and the shape of the sealing plate is controlled, thereby the Ni-plated portion. As a result, it was possible to further suppress the occurrence of rust on the outer surface of the sealing plate by further suppressing peeling and cracking of the sealing plate, and also suppressing the occurrence of liquid leakage.

  The sealing plate according to the present invention is a Ni-plated steel plate in which at least the outer surface of a steel substrate is Ni-plated, and a region in which Fe and Ni are diffused is present between the Ni-plated portion and the steel substrate portion. It consists of

  The Ni-plated steel sheet can be obtained, for example, by performing a heat treatment on a steel sheet having a Ni-plated layer. A region in which Ni in the Ni plating layer and Fe in the steel substrate diffuse to each other at the interface between the Ni plating layer and the steel substrate (steel plate) by this heat treatment (hereinafter referred to as “Fe—Ni diffusion region”). Are formed in layers.

  Thus, if the Ni-plated steel sheet has a Fe—Ni diffusion region between the Ni plating layer (Ni plating portion) and the steel base (steel base portion), the presence of the Fe—Ni diffusion region Since the adhesion between the Ni-plated layer on the surface of the Ni-plated steel plate and the steel base material is improved, peeling of the Ni-plated layer and cracking during processing into a sealing plate are suppressed, and generation of rust is suppressed. In the Ni-plated steel sheet constituting the sealing plate according to the present invention, since the boundary with the Fe-Ni diffusion region becomes ambiguous due to the formation of the Fe-Ni diffusion region, for example, the Ni plating layer is Fe-Ni. Although it is not a layer that can be clearly distinguished from the Ni diffusion region, in this specification, in the following description, the remaining portion (Ni plating portion) of the Ni plating layer in the Ni plated steel sheet after the Fe—Ni diffusion region is formed For convenience, it is referred to as “Ni plating layer”. For the same reason, the steel substrate (steel plate) portion after the Fe—Ni diffusion region is formed is also referred to as “iron substrate” or “steel plate”.

  As described above, the Ni-plated steel sheet constituting the sealing plate according to the present invention can be obtained, for example, by heat-treating the Ni-plated steel sheet. In the Ni-plated steel sheet before the heat treatment, the Ni-plated layer has a matte surface. A Ni plating layer is preferred. The matte Ni plating layer is a soft Ni plating layer formed without using organic additives such as a gloss additive, a leveling agent, and a pinhole inhibitor. Unlike the ordinary Ni plating layer (so-called hard Ni plating layer) which is a trace alloy plating such as P and S, the soft Ni plating layer inevitably contains such a trace component such as P and S when forming the plating layer. It means a Ni plating layer that does not substantially contain, except for mixed materials, or that does not affect the increase in hardness of the plating layer even if it is contained.

  In other words, in ordinary hard Ni plating layers (including those called glossy Ni plating layers and semi-glossy Ni plating layers), trace components such as P and S described above function as brighteners and as hardeners. Because it functions, it has high hardness and poor spreadability. On the other hand, the matte plating layer containing little or no curing component such as P or S has good spreadability, and the Ni plating layer left after forming the Fe—Ni diffusion region by the above heat treatment However, since good extensibility is maintained, since the Ni plating layer is not easily peeled off or cracked even when it is molded into the shape of the sealing plate, the occurrence of rust can be further suppressed.

  The thickness of the matte Ni plating layer is, for example, 1.5 μm or more, more preferably 2.5 μm or more, and preferably 10 μm or less, more preferably 5 μm or less. If the thickness of the matte Ni plating layer is too small, the Fe-Ni diffusion region formed by the heat treatment becomes thin, so that the effect of suppressing cracking and peeling of the Ni plating layer when processed into a sealing plate may be reduced. . On the other hand, if the thickness of the matte Ni plating layer is too large, the effect of suppressing cracking and peeling of the Ni plating layer when processing into a sealing plate is saturated, but the manufacturing cost increases, which is not preferable.

  Moreover, it is preferable that the thickness of the steel base material (steel plate) before heat processing is 100-500 micrometers, for example.

  When forming the Fe-Ni diffusion region by heat-treating the Ni-plated steel sheet having the matte Ni-plated layer, in the case of heat treatment by a box-type annealing method, for example, at a temperature of 450 to 650 ° C, 4 to 15 In the case of heat treatment by a time and continuous annealing method, it is preferable to employ heat treatment conditions such as, for example, 0.5 to 3 minutes at a temperature of 600 to 850 ° C.

  FIG. 1 shows an example of a coin battery of the present invention. FIG. 1 is a schematic view showing a cross section of the main part of the coin-type battery of the present invention, wherein 1 is a coin-type battery, 2 is a sealing plate, 3 is an outer can, 4 is a gasket (annular gasket), 5 is a negative electrode, 6 is a separator, and 7 is a positive electrode.

  As shown in FIG. 1, in the coin-type battery 1, the sealing plate 2 and the outer can 3 are caulked through the gasket 4 so as to tighten the opening end of the outer can 3 inward. The peripheral folded portion and the open end of the outer can 3 are sealed by being pressed against the gasket 4. Inside the coin-shaped battery 1, a negative electrode 5 in contact with the sealing plate 2 and a positive electrode 7 in contact with the outer can 3 are loaded in a state of being stacked with a separator 6 interposed therebetween, and an electrolytic solution (not shown) ) Has been injected. The sealing plate 2 functions as a negative electrode terminal, and the outer can 3 functions as a positive electrode terminal.

  Reference numeral 2a denotes an upper surface wall of the sealing plate 2, and 2b denotes a curved portion curved downward from the upper surface wall 2a. In the present invention, in the sealing plate 2, in addition to the specific Ni-plated steel plate, the ratio of the radius of curvature R (mm) of the curved portion 2b and the internal angle θ (°) of the curved portion 2b is “ R / θ ”has the greatest feature where it is 0.0060 or more and 0.0160 or less.

  FIG. 2 shows an enlarged view of the sealing plate 2 shown in FIG. FIG. 2 shows a cross-sectional view of the sealing plate 2, but in order to facilitate understanding, a hatched line indicating that the sealing plate 2 is a cross-sectional view is omitted. When the sealing plate 2 is viewed in cross section, the curved portion 2b of the sealing plate 2 starts from a curved portion that faces downward from the substantially flat upper surface wall 2a, and then terminates the curved portion that changes in curvature. Means that the curvature is constant. The curvature radius R of the curved portion 2b is a curved radius of curvature of the outer surface (battery outer surface) of the curved portion 2a of the sealing plate 2 as shown in FIG. 2, and the inner angle θ of the curved portion 2b. The term “inner angle” refers to the inner angle between the two lines when a line segment from the both ends of the outer surface of the curved portion 2b toward the center of curvature is drawn. In FIG. 2, the curvature radius R and the internal angle θ are illustrated so as to facilitate understanding. For example, the position of the curvature center for obtaining the curvature radius is not necessarily accurate.

  In the curved portion 2b of the sealing plate 2, the value of R / θ is controlled to the above specific value to prevent the Ni plated layer from peeling or cracking in the curved portion 2b and to prevent leakage after the battery is formed. Can be achieved. That is, if the value of R / θ is too small, peeling or cracking occurs in the Ni plating layer, particularly in the vicinity of the curved portion 2b, and rust is likely to occur. On the other hand, if the value of R / θ is too large, peeling or cracking of the Ni plating layer is difficult to occur, but liquid leakage tends to occur when the battery is manufactured. The value of R / θ is preferably 0.008 or more and preferably 0.015 or less.

  Controlling the value of R / θ means adjusting the size of the deformation region in the curved portion when the sealing plate is formed using the specific Ni-plated steel plate.

  For example, when the radius of curvature R of the curved portion is reduced, the deformation at the curved portion increases. Therefore, if R is reduced so that the value of R / θ is lower than the above specific value and the deformation at the curved portion is increased, the Ni plating layer is peeled off or cracked in the vicinity of the curved portion. End up. Further, if processing is performed so that θ becomes too large, the upper part is bent inward, and the battery internal volume may be wasted.

  On the other hand, if the radius of curvature R of the curved portion is processed to be large or the internal angle θ of the curved portion is processed to be small, deformation at the curved portion becomes small, so that the Ni plating layer is hardly peeled off or cracked. The degree of work hardening of the plated steel sheet is reduced. Therefore, when R is increased or θ is decreased so that the value of R / θ exceeds the specific value, work hardening in the curved portion becomes insufficient, resulting in insufficient strength of the sealing plate, Liquid leakage occurs when the battery is used.

  The curvature radius R of the curved portion is, for example, 0.40 mm or more, more preferably 0.50 mm or more, and preferably 0.90 mm or less, more preferably 0.70 mm or less. Further, it is desirable that the internal angle θ of the curved portion is, for example, 60 ° or more, more preferably 70 ° or more, 90 ° or less, and more preferably 85 ° or less.

  In the present invention, the R / θ at the curved portion of the sealing plate is controlled by the deformation of the portion of the sealing plate exposed outside the battery when the curved portion is processed and formed into the sealing plate. It is because it is the place that has received.

  The outer can according to the battery of the present invention is preferably made of stainless steel. The sealing plate has a function of supporting the caulking portion (sealing portion obtained by caulking the sealing plate and the outer can via a gasket) from the inside when the battery is used, but the sealing plate is configured using the specific Ni-plated steel plate. Since the plate is somewhat inferior in strength to the sealing plate made of stainless steel, for example, when the specific Ni-plated steel plate is used for the outer can, the strength of the caulking portion is further lowered.

  In the coin battery of the present invention, for example, when an organic electrolyte battery is used, it is preferable to use lithium or a lithium alloy for the negative electrode. When such a negative electrode is used, the battery voltage is about 3V. When the specific Ni-plated steel sheet is used as the material, the sealing plate is not oxidized, but the outer can may be corroded by oxidation.

  The coin-type battery of the present invention includes both modes of an organic electrolyte battery having an organic electrolyte as an electrolyte and an alkaline battery having an alkaline electrolyte (alkaline aqueous solution) as an electrolyte.

  The positive electrode according to the coin-type battery of the present invention is obtained by pressure-molding a positive electrode mixture containing a positive electrode active material, a conductive additive and a binder into a pellet form. The positive electrode active material is not particularly limited. For example, in the case of an organic electrolyte battery, an oxide such as manganese, cobalt, nickel, magnesium, copper, iron, or niobium; a composite oxide thereof; In the case where the composite oxide; fluorinated graphite; etc. is an alkaline battery, manganese dioxide, nickel oxyhydroxide, silver oxide and the like can be mentioned. Examples of the conductive assistant include carbon black, scaly graphite, ketjen black, acetylene black, and fibrous carbon. Examples of the binder include polytetrafluoroethylene (PTFE), polyvinylidene fluoride, Carboxymethyl cellulose, styrene butadiene rubber and the like can be used.

  In the case of an organic electrolyte battery, the negative electrode according to the present invention preferably uses lithium metal or a lithium alloy as the negative electrode active material. Examples of the lithium alloy include binary lithium alloys such as lithium-aluminum alloy, lithium-lead alloy, lithium-bismuth alloy, and lithium-indium alloy, and ternary lithium alloys such as lithium-indium-gallium alloy. Is mentioned. Of these lithium alloys, lithium-aluminum alloys are particularly suitable. When the battery of the present invention is an alkaline battery, zinc or a zinc alloy can be used as the negative electrode.

  As the electrolyte, when the battery of the present invention is an organic electrolyte battery, for example, cyclic carbonates such as propylene carbonate, ethylene carbonate, butylene carbonate, vinylene carbonate; dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, etc. Chain carbonate ester; and 1,2-dimethoxyethane, diglyme (diethylene glycol methyl ether), triglyme (triethylene glycol dimethyl ether), tetraglyme (tetraethylene glycol dimethyl ether), 1,2-dimethoxyethane, 1,2-di By dissolving the electrolyte in a concentration of about 0.3 to 2.0 mol / L in one solvent selected from ethers such as ethoxymethane and tetrahydrofuran; The organic electrolytic solutions prepared Te is used.

Examples of the electrolyte include LiBF ₄ , LiPF ₆ , LiAsF ₆ , LiSbF ₆ , LiClO ₄ , LiCF ₃ SO ₃ , LiC ₄ F ₉ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiN (C ₂ F ₅ SO ₂ ) ₂ etc. are used.

  When the battery of the present invention is an alkaline battery, an alkaline aqueous solution (for example, a lithium hydroxide aqueous solution, a potassium hydroxide aqueous solution, a sodium hydroxide aqueous solution, etc.) can be used as the electrolytic solution.

  As the separator, either a microporous resin film or a resin nonwoven fabric can be used. Examples of the material include polyolefins such as PE, PP, and polymethylpentene, and as heat resistance, fluororesin such as tetrafluoroethylene-perfluoroalkoxyethylene copolymer (PFA); PPS; polyether ether ketone ( PEEK); PBT and the like. Moreover, you may comprise a separator by laminating | stacking two or more microporous resin films and resin nonwoven fabrics of the said material, or laminating | stacking two or more microporous resin films or resin nonwoven fabrics.

  As a material of the gasket interposed between the sealing plate and the outer can, for example, PP; nylon (nylon 6, nylon 66, etc.); etc., and for heat resistance, fluorine resin such as PFA; polyphenylene ether (PPE); Examples include polysulfone (PSF); polyarylate (PAR); polyethersulfone (PES); PPS; PEEK;

  The coin-type battery of the present invention can take either a primary battery or a secondary battery depending on the selection of the constituent elements (power generation elements) exemplified above. And the coin-type battery of this invention can be used suitably for the various uses to which the conventionally well-known coin-type primary battery and coin-type secondary battery are applied.

  Hereinafter, the present invention will be described in detail based on examples. However, the following examples are not intended to limit the present invention, and all modifications made without departing from the spirit of the preceding and following descriptions are included in the technical scope of the present invention.

Example 1
In producing the coin-type battery 1 of Example 1, the outer can 3, the sealing plate 2, the annular gasket 4, the positive electrode 7, the negative electrode 5, the separator 6, and the electrolytic solution shown below were used. First, as the outer can 3, a stainless steel plate having a thickness of 3 μm and plated with a nickel plate having a thickness of 200 μm and formed into a bottomed cylindrical shape having a peripheral wall height of 3 mm by drawing is used.

  The sealing plate 2 is formed into a shape having a curved portion 2b by forming a Fe-Ni diffusion region by heat-treating a cold-rolled steel plate (steel plate) having a thickness of 250 μm with a 3 μm matte Ni plating. What was done was used. Here, the heat treatment was performed at 780 ° C. for 60 seconds using a continuous annealing method.

  Further, as the shape of the curved portion of the sealing plate 2, the radius of curvature R was 0.6 mm, and the internal angle θ of the curved portion was 78 °. At this time, R / θ was 0.0077.

  In the production of the positive electrode 7, manganese dioxide is used as the positive electrode active material, artificial graphite is used as the conductive additive, polytetrafluoroethylene is used as the binder, manganese dioxide is 91.7% by mass, and artificial graphite is 7.6% by mass. % And polytetrafluoroethylene were mixed so as to be 0.7% by mass to prepare a positive electrode mixture. The positive electrode mixture was filled in a mold and pressure-molded to produce a positive electrode 7. This positive electrode 7 had a diameter of 16 mm and a thickness of 1.9 mm.

As an electrolytic solution, an organic electrolytic solution prepared by dissolving 0.5 mol / l of LiClO _{4 in} a mixed solvent of propylene carbonate and 1,2-dimethoxyethane in a volume ratio of 1: 1 was used.

  As the negative electrode 5, a lithium plate having a thickness of 0.58 mm punched into a circle having a diameter of 16 mm was used, and the negative electrode 5 was accommodated in the sealing plate 2.

  The separator 6 is made of polypropylene non-woven fabric, the annular gasket 4 is made of polypropylene, and the outer can 3, the sealing plate 2, the positive electrode 7, the negative electrode 5, and the electrolytic solution are used. A coin-shaped battery having a structure of 1 and a diameter of 20 mm and a height of 3.2 mm was produced. Here, the battery of Example 1 will be described with reference to FIG. 1. The positive electrode 1 is formed by pressure-molding a positive electrode mixture containing manganese dioxide as a positive electrode active material as described above, and the negative electrode 5 is formed by the above-described method. The separator 6 made of a polypropylene non-woven fabric is interposed between the positive electrode 7 and the negative electrode 5 as shown in FIG. 7, the negative electrode 5, the separator 6, the electrolytic solution, and the like are housed in a space formed by the outer can 3, the sealing plate 2, and the annular gasket 4. When the battery is assembled, the opening end portion of the outer can 3 is tightened inward, so that a so-called caulking process is performed to connect the annular gasket 4 to the peripheral folded portion of the sealing plate 2 and the inner periphery of the opening end portion of the outer can 3. The opening of the outer can 3 is sealed by being brought into pressure contact with the surface, and the inside of the battery is sealed.

Example 2
A coin-type battery was fabricated in the same manner as in Example 1 except that the curved portion of the sealing plate 2 had a curvature radius R of 0.6 mm and an internal angle θ of the curved portion of 60 °. The R / θ of the curved portion of the sealing plate 2 was 0.0100.

Example 3
A coin-type battery was fabricated in the same manner as in Example 1 except that the curved portion of the sealing plate 2 had a curvature radius R of 0.55 mm and an internal angle θ of the curved portion of 84 °. The R / θ of the curved portion of the sealing plate 2 was 0.0065.

Example 4
A coin-type battery was fabricated in the same manner as in Example 1 except that the curved portion of the sealing plate 2 had a curvature radius R of 0.9 mm and an internal angle θ of the curved portion of 60 °. The R / θ of the curved portion of the sealing plate 2 was 0.0150.

Example 5
As a material for forming the sealing plate 2, a cold-rolled steel plate (steel plate) having a thickness of 250 μm subjected to 1.5 μm matte Ni plating and subjected to heat treatment under the same conditions as in Example 1 was used. A coin-type battery was produced in the same manner as in Example 1 except for the above.

Comparative Example 1
A coin-type battery was fabricated in the same manner as in Example 1 except that the curved portion of the sealing plate 2 had a curvature radius R of 0.45 mm and an internal angle θ of the curved portion of 78 °. The R / θ of the curved portion of the sealing plate 2 was 0.0058.

Comparative Example 2
A coin-type battery was fabricated in the same manner as in Example 1 except that the curved portion of the sealing plate 2 had a radius of curvature R of 0.45 mm and an internal angle θ of the curved portion of 86 °. The R / θ of the curved portion of the sealing plate 2 was 0.0052.

Comparative Example 3
A coin-type battery was fabricated in the same manner as in Example 1 except that the curved portion of the sealing plate 2 had a curvature radius R of 1.1 mm and an internal angle θ of the curved portion of 60 °. The R / θ of the curved portion of the sealing plate 2 was 0.0183.

Comparative Example 4
As a material for forming the sealing plate 2, a cold-rolled steel plate (steel plate) having a thickness of 250 μm and subjected to 3 μm matte Ni plating is used without being heat-treated and without forming an Fe—Ni diffusion region. A coin-type battery was produced in the same manner as in Example 1 except that.

  The batteries of Examples 1 to 5 and Comparative Examples 1 to 4 were stored in an atmosphere at 85 ° C. and a relative humidity of 90% for 15 days, and the presence / absence of leakage and the presence / absence of corrosion of the curved portion were examined. Each discrimination was made visually. In these tests, 25 batteries each of Examples 1 to 5 and Comparative Examples 1 to 4 were used. The results are shown in Table 1.

  Moreover, the photograph which image | photographed the curved part in the sealing board of the battery of Example 1 with an electron microscope in FIG. 3 is shown in FIG. 4, and the photograph which image | photographed the curved part in the sealing board of the battery of the comparative example 4 with an electron microscope is shown. .

  As shown in Table 1, coin-type batteries of Examples 1 to 5 having a sealing plate processed so that R / θ becomes a suitable value using a Ni-plated steel sheet having a Fe—Ni diffusion region are comparative examples. Corrosion at the curved portion does not occur compared to coin-type batteries 1, 2, and 4, and no leakage occurs as in the coin-type battery of Comparative Example 3, and a steel plate is used for the sealing plate. In addition, it can be confirmed that the problem of leakage due to the corrosion of the battery can and the decrease in strength is improved.

  Here, comparing FIG. 3, which is a photograph of the curved portion of the sealing plate of the battery of Example 1 taken with an electron microscope, and FIG. 4, which is a photograph of the curved portion of the sealing plate of the battery of Comparative Example 4, In the battery of the example, it can be confirmed that generation of cracks in the Ni-plated portion can be remarkably suppressed.

It is a longitudinal cross-sectional view which shows typically an example of the principal part of the coin-type battery of this invention. It is an enlarged view which shows the principal part of the sealing board which concerns on the coin-type battery shown in FIG. 3 is an electron micrograph of a curved portion of a sealing plate of a coin-type battery according to Example 1. FIG. 6 is an electron micrograph of a curved portion of a sealing plate of a coin-type battery according to Comparative Example 4.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Coin type battery 2 Sealing plate 2a Upper surface wall 2b Curved part 3 Exterior can 4 Gasket

Claims (5)

A coin-type battery in which a sealing plate having a top wall and a curved portion curved downward from the top wall and an opening of an outer can are sealed by caulking through a gasket,
The sealing plate is made of a Ni-plated steel plate in which at least the outer surface of the steel base is Ni-plated, and a region in which Fe and Ni are diffused between each other exists between the Ni-plated portion and the steel base portion. And
A coin-type battery, wherein a ratio R / θ between a radius of curvature R (mm) of the curved portion of the sealing plate and an internal angle θ (°) of the curved portion is 0.0060 to 0.0160. The coin-type battery according to claim 1, wherein an inner angle θ of the curved portion of the sealing plate is 60 to 90 °. The coin-type battery according to claim 1 or 2 , wherein the Ni-plated steel plate constituting the sealing plate is obtained by heat-treating a steel plate having a matte Ni-plated layer. The coin-type battery according to claim 3 , wherein the matte Ni plating layer has a thickness of 2 to 10 μm. The outer can coin cells according to any one of claims 1 to 4, which comprises a negative electrode having a stainless steel is constituted by steel, and lithium or a lithium alloy.