JP2018041530A - Coin-shaped battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce damages on an organism due to accidental ingestion of a coin-shaped battery.SOLUTION:CLAIM 1: A coin-shaped battery comprises: a case having a bottom plate part and a side part rising up from a peripheral edge of the bottom plate part; a sealing port plate having a top plate part and a peripheral edge part extended to an inner side of the side part from the top plate part; a gasket that is interposed between the side part and the peripheral edge part; an electric power generation element that is sealed with the case and the sealing port plate; a first metal layer in which at least one of the case and the sealing port plate is provided to an outer surface side; and a second metal layer that is provided on an inner surface side from the first metal layer. The first metal layer includes at least one selected from a group consisting of aluminum and magnesium.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a coin-type battery, and more particularly to a coin-type battery with improved safety against accidental ingestion.

  Coin batteries are widely used as power sources for small devices and memory backup. Although the use of coin-type batteries is expanding, the importance of countermeasures against accidental swallowing of coin-type batteries is increasing. When the coin-type battery is taken into the living body, the terminal surfaces of the case of the coin-type battery and the sealing plate come into contact with body fluid, and water electrolysis proceeds. Although the pH of the body fluid is generally neutral, when the electrolysis of water proceeds, the body fluid on the negative electrode terminal side changes to alkaline, and the body fluid on the positive electrode terminal side changes to acidic. Therefore, it causes harm to the living body.

  Therefore, Patent Document 1 proposes forming a conductive film containing a bitter substance on the surface of the battery from the viewpoint of preventing accidental ingestion.

  Usually, a metal material (for example, stainless steel) excellent in corrosion resistance is used for the case and the sealing plate of the coin-type battery. Moreover, when using as a secondary battery, using the clad material of stainless steel and aluminum is also proposed from a viewpoint of suppressing the corrosion of the metal material of the positive electrode side at the time of overcharge. In this case, aluminum needs to be disposed on the inner surface side of the battery (Patent Document 2).

JP-A-4-317622 JP-A-5-174873

  When the material proposed in Patent Document 2 is used as the case and sealing plate of the coin-type battery, it is difficult to avoid the above-mentioned harm due to accidental ingestion. The method of Patent Document 1 also causes the same problem when a living body swallows a coin-shaped battery without discharging it.

  In view of the above, an object of the present invention is to provide a highly safe coin-shaped battery that can reduce harm to a living body due to accidental ingestion.

  One aspect of the present invention is a case having a bottom plate portion and a side portion rising from the periphery of the bottom plate portion, a sealing plate having a top plate portion and a peripheral portion extending from the top plate portion to the inside of the side portion, and the side A gasket interposed between the peripheral portion and the peripheral portion, a power generation element sealed by the case and the sealing plate, and at least one of the case and the sealing plate is provided on the outer surface side. A coin comprising: a metal layer; and a second metal layer provided on an inner surface side of the first metal layer, wherein the first metal layer includes at least one selected from the group consisting of aluminum and magnesium. The present invention relates to a battery.

  ADVANTAGE OF THE INVENTION According to this invention, the harm to the biological body by accidental ingestion of a coin-type battery can be reduced.

It is a longitudinal cross-sectional view of the coin-type battery which concerns on embodiment of this invention.

  A coin-type battery according to an embodiment of the present invention includes a power generation element and an exterior body that hermetically houses the power generation element. The exterior body includes a bottomed case having an opening, a sealing plate that closes the opening of the case, and a gasket that is interposed between an end portion (opening end portion) of a side portion of the case and a peripheral portion of the sealing plate. doing. The power generation element includes a first electrode, a second electrode, a separator interposed therebetween, and an electrolytic solution. After the power generation element is filled in the space formed by the case and the sealing plate, the power generation element is hermetically housed inside the exterior body by crimping the opening end of the case to the peripheral edge of the sealing plate via a gasket. Is done.

  The coin type battery includes a button type. That is, the shape and diameter of the coin battery are not particularly limited. For example, a button-type battery whose battery thickness is larger than the diameter is also included in the coin-type battery.

  More specifically, the case has a bottom plate portion and side portions that rise from the periphery of the bottom plate portion. The bottom plate portion is usually circular, but may have a shape close to a circle (for example, an ellipse). The sealing plate has a top plate portion and a peripheral portion extending from the top plate portion to the inside of the side portion of the case. The top plate portion corresponds to the shape of the bottom plate portion, and is usually a circle having a smaller diameter than the bottom plate portion. The thickness T of the coin-type battery is often smaller than the diameter D of the bottom plate portion (T <D), for example, 1.2 mm ≦ T ≦ 5.0 mm and 9 mm ≦ D ≦ 24.5 mm. A gasket is compressed and interposed between the side of the case and the peripheral edge of the sealing plate. Here, at least one of the case and the sealing plate includes a first metal layer provided on the outer surface side and a second metal layer provided on the inner surface side of the first metal layer, and the first metal layer is It contains at least one selected from the group consisting of aluminum and magnesium.

  The first metal layer provided on the outer surface side is a metal layer that first comes into contact with body fluid when the coin-type battery is accidentally swallowed. That is, in addition to the first metal layer and the second metal layer, at least one third metal layer may be present, but the third metal layer needs to be provided on the inner surface side of the first metal layer. On the other hand, the 2nd metal layer should just be provided in the inner surface side rather than the 1st metal layer, and may be on the outer surface side from the 3rd metal layer.

  The first metal layer may be formed of pure aluminum or magnesium (a simple substance), may be formed of an aluminum alloy or a magnesium alloy, or may be formed of an alloy containing aluminum and magnesium. Further, the first metal layer may be a laminate of layers formed of these simple substances and / or alloys.

  The aluminum alloy, the magnesium alloy, and the alloy containing aluminum and magnesium may each include a fourth metal that is neither aluminum nor magnesium. However, from the viewpoint of enhancing the action of the first metal layer when accidental ingestion occurs, the content of the fourth metal contained in the first metal layer is preferably 6% by mass or less. Examples of the fourth metal include Mn, Zn, Ti, and Cu.

  In addition, even if trace amount metals other than Al and Mg have adhered to the outer surface side of the 1st metal layer, the effect | action of the 1st metal layer at the time of accidental ingestion is not inhibited. Moreover, the outer surface of the first metal layer may be covered with a material that dissolves in the living body. For example, a nickel layer having a thickness of 5 μm or less, preferably 1 μm or less may be provided on the outer surface of the first metal layer. Since the nickel layer is easily dissolved in an alkaline or acidic environment in the living body, the action of the first metal layer is not inhibited.

  The first electrode and the second electrode have different polarities. That is, when the first electrode is a positive electrode (or negative electrode), the second electrode is a negative electrode (or positive electrode). When the coin-type battery is a lithium battery, it is common that the positive electrode is housed so as to face the bottom plate portion of the case, and the negative electrode is housed in the exterior body so as to face the top plate portion of the sealing plate. However, the arrangement of the positive and negative electrodes is not limited to this.

  The first metal layer on the outer surface side of the battery has an effect of suppressing a significant change in the pH of the body fluid when the coin-type battery is accidentally swallowed and the case and the body fluid and / or the sealing plate and the body fluid come into contact with each other. Aluminum or magnesium contained in the first metal layer is an amphoteric metal that dissolves in both acidic and alkaline body fluids. Therefore, when a coin-shaped battery is taken into the body and comes into contact with body fluid, water electrolysis temporarily proceeds, but when the body fluid in the vicinity of the case or sealing plate changes to acidic or alkaline, aluminum or magnesium dissolves. The precipitation reaction begins to proceed. Thereby, the electrolysis of water is suppressed, and the capacity of the coin-type battery is consumed by the dissolution or precipitation reaction of aluminum or magnesium.

  More specifically, for example, when a case or sealing plate that functions as a negative electrode terminal is in contact with body fluid, water electrolysis temporarily proceeds to generate hydrogen, and the body fluid near the negative electrode terminal becomes alkaline. Change. However, before reaching a strong alkali that is harmful to the living body, for example, aluminum contained in the first metal layer starts to dissolve as an aluminate anion and immediately deposits as aluminum on the negative electrode terminal. Since this reaction takes precedence over the reductive decomposition reaction of water, further increase in pH is suppressed. Current flows due to the precipitation reaction of aluminum, and eventually the capacity of the coin-type battery is consumed.

Further, when the case or sealing plate that functions as the positive electrode terminal is in contact with the body fluid, water electrolysis temporarily proceeds to generate oxygen, and the body fluid in the vicinity of the positive electrode terminal changes to acidic. At this time, for example, aluminum contained in the first metal layer dissolves as aluminum chloride and reacts with water to form a hydroxide or an oxo compound. Thereafter, the hydroxide or oxo compound changes to aluminum oxide and is deposited on the surface of the positive electrode terminal. Aluminum oxide is passive. In the place covered with the passive state, the oxidative decomposition reaction of water does not occur, and the reaction at the positive electrode is delayed according to the area.
Even when the first metal layer contains magnesium, the same reaction proceeds at the positive electrode terminal and the negative electrode terminal.

  The second metal layer is a main material constituting the skeleton of the case or the sealing plate, and requires strength as well as corrosion resistance to the power generation element. Therefore, it is desirable that the second metal layer includes at least one selected from the group consisting of stainless steel and titanium.

  The second metal layer may be formed of stainless steel, may be formed of pure titanium (simple substance), or may be formed of a titanium alloy. The second metal layer may be a laminate of layers each formed of stainless steel, titanium alone and / or a titanium alloy. The titanium alloy may contain a fifth metal other than titanium, for example, with a content of 7% by mass or less. Examples of the fifth metal include Al, Fe, and V.

  At least one of the case and the sealing plate may be formed of a clad material of the first metal layer and the second metal layer. As such a clad material, specifically, a clad material of aluminum or aluminum alloy (the content of the fourth metal is 6 mass% or less) and stainless steel, magnesium or a magnesium alloy (the content of the fourth metal is 6 mass% or less) and stainless steel clad material, aluminum or aluminum alloy (the fourth metal content is 6 mass% or less) and titanium or titanium alloy (the fifth metal content is 7 mass% or less) Examples thereof include a clad material, a clad material of magnesium or a magnesium alloy (the content of the fourth metal is 6% by mass or less) and titanium or a titanium alloy (the content of the fifth metal is 7% by mass or less). Among them, a clad material of aluminum or aluminum alloy and stainless steel is preferable because it is easy to manufacture.

  In the case or sealing plate functioning as the negative electrode terminal, inexpensive ordinary steel or carbon steel may be used as the second metal layer instead of stainless steel. The ordinary steel is a steel material such as SS material, SM material, or SPCC material specified by JIS. Carbon steel is a steel material such as S10C, S20C, S30C, S45C, and S55C, and belongs to alloy steel for machine structure. However, when ordinary steel or carbon steel is used for the second metal layer, a rust-preventing plating layer (for example, a nickel plating layer) is formed on the inner side of the battery. As for the thickness of a plating layer, 1-5 micrometers is desirable.

  The impact on the living body is greater when the body fluid becomes alkaline than acidic. In general, the sealing plate is a negative electrode terminal. Therefore, at least the sealing plate preferably includes the first metal layer and the second metal layer, and more preferably both the case and the sealing plate include the first metal layer and the second metal layer. However, even when only the case includes the first metal layer and the second metal layer, the influence on the living body can be alleviated.

  Thereafter, aluminum or magnesium ions dissolved from the first metal layer may be deposited in a metallic state also near the boundary between the case and the sealing plate. At this time, if the amount of dissolved metal ions is sufficient, the case and the sealing plate (that is, the positive terminal and the negative terminal) are externally short-circuited by the deposited metal. If such an external short circuit occurs, the current flows through the short circuit path and the capacity is consumed, so that the electrolysis is remarkably suppressed. Therefore, harm to a living body can be greatly reduced.

  When the case includes the first metal layer and the second metal layer, it is desirable to cover the end portion (open end portion) of the side portion of the case with an insulating material. This is because even if the first metal layer is disposed on the outer surface side of the case, the second metal layer on the inner surface side is exposed at the edge surface of the opening end. From the viewpoint of enhancing the action of the first metal layer when accidental ingestion occurs, it is desirable to avoid contact between the second metal layer and the body fluid as much as possible. At this time, the insulating material is not particularly limited, and a rubber material, a resin material such as a fluororesin, grease, wax, asphalt, and the like can be used. In addition, since the peripheral part of a sealing board is arrange | positioned inside the side part of a case also including the edge surface, it is not exposed outside.

  As the rubber material, styrene butadiene rubber, butadiene rubber, ethylene propylene rubber, chloroprene rubber, isobutylene rubber, butyl rubber, silicone rubber and the like are preferable.

  Among the resin materials, a fluororesin is preferable because it has high water repellency and is difficult to peel. Examples of fluororesins include polytetrafluoroethylene (PTFE), polychlorotrifluoroethylene (PCTFE), polyvinylidene fluoride (PVDF), modified PVDF, polyvinyl fluoride (PVF), and tetrafluoroethylene-perfluoroalkyl. Vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), ethylene-tetrafluoroethylene copolymer (ETFE), ethylene-chlorotrifluoroethylene copolymer (ECTFE), vinylidene fluoride -A hexafluoropropylene copolymer etc. can be used.

  The thickness T1 of the first metal layer is preferably 5 to 125 μm, and more preferably 10 to 100 μm. Thereby, sufficient quantity of aluminum and magnesium to suppress electrolysis of water can be included in the 1st metal layer.

  The thickness T2 of the second metal layer is preferably 125 to 250 μm, and more preferably 150 to 220 μm. Thereby, it becomes easy to ensure sufficient strength as an exterior body. At this time, the ratio of thickness: T2 / T1 is preferably 1 to 50, and more preferably 2 to 20 so that the ratio of the first metal layer in the case or the sealing plate does not become too large.

  Hereinafter, a coin-type battery according to an embodiment of the present invention will be described with reference to the drawings. However, the following embodiments do not limit the technical scope of the present invention.

FIG. 1 is a cross-sectional view of an example of a coin-type battery according to the present embodiment.
The coin-type battery 10 includes an exterior body including a case 1, a sealing plate 6, and a gasket 5. The case 1 is a cylindrical and shallow battery can having a bottom plate portion 1a and a side portion 1b rising from the periphery of the bottom plate portion 1a. The sealing plate 6 has a top plate portion 6 a and a peripheral portion 6 b extending from the top plate portion 6 a to the inside of the side portion 1 b of the case 1. A part of the gasket 5 seals the gap between the case 1 and the sealing plate 6 by being interposed between the side portion 1 b of the case 1 and the peripheral portion 6 b of the sealing plate 6.

  A power generation element is accommodated in the exterior body. The power generation element includes a positive electrode 2, a negative electrode 3, a separator 4, and an electrolytic solution (not shown). In the illustrated example, the positive electrode 2 is disposed so as to face the bottom plate portion 1 a of the case 1. Case 1 functions as a positive terminal. On the other hand, the negative electrode 3 is disposed so as to face the top plate portion 6 a of the sealing plate 6. The sealing plate 6 functions as a negative electrode terminal.

  In the illustrated example, a clad material A of a first metal layer 11 made of aluminum and a second metal layer 12 made of stainless steel is used as a material of the case 1. In the coin battery 10, the first metal layer 11 is disposed on the outer surface side, and the second metal layer 12 is disposed on the inner surface side. However, at least the edge surface of the second metal layer 12 is exposed at the end 1t of the side 1b of the case 1. Therefore, the end 1t is covered with an insulating film 8 containing an insulating material.

  As a material of the sealing plate 6, a clad material B of a first metal layer 61 made of aluminum and a second metal layer 62 made of stainless steel, ordinary steel, carbon steel or the like is used. In the coin battery 10, the first metal layer 61 is disposed on the outer surface side, and the second metal layer 62 is disposed on the inner surface side. Since the edge part 6t of the peripheral part 6b of the sealing board 6 is arrange | positioned inside the side part 1b of the case 1, the edge surface of the 2nd metal layer 62 is not exposed outside.

  The stainless steel constituting the second metal layer of case 1 desirably has corrosion resistance at the positive electrode potential. For example, it is desirable to use stainless steel such as SUS430, SUS444, and SUS329J for the case 1 of the lithium battery.

  The stainless steel constituting the second metal layer of the sealing plate 6 is desirably stable against lithium metal. For example, it is desirable to use stainless steel such as SUS304, SUS316, or SUS430 for the sealing plate 6 of the lithium battery. Ordinary steel or carbon steel may be used.

Next, taking a lithium battery as an example, a method for manufacturing a coin-type battery will be described.
The coin battery includes a step (i) of preparing a power generation element, a step (ii) of preparing the case 1, a step (iii) of preparing the sealing plate 6, a step of preparing the gasket 5 (iv), A step (v) of housing the power generation element in the case 1, closing the opening of the case 1 with the sealing plate 6, and crimping the opening end of the case 1 to the peripheral edge of the sealing plate 6 via the gasket 5; A step (vi) of covering the end portion 1t of the side portion 1b with the insulating coating 8. The thickness of the material (for example, the clad material described above) used for the case 1 and / or the sealing plate 6 is, for example, 0.1 to 0.4 mm.

  In step (ii), for example, the case 1 is manufactured by drawing a clad material and forming it into a cylindrical shape with a bottom. A first metal layer is provided on the surface of the cladding material corresponding to the outer surface side of the battery, and a second metal layer is provided on the surface corresponding to the inner surface side.

  In step (iii), for example, a sealing plate having a predetermined shape is formed by pressing a clad material. A first metal layer is provided on the surface of the cladding material corresponding to the outer surface side of the battery, and a second metal layer is provided on the surface corresponding to the inner surface side.

  In step (iv), a gasket 5 having an annular groove to be fitted to the peripheral edge of the sealing plate 6 is prepared. The gasket 5 may be attached to the peripheral edge of the sealing plate 6 in advance. As a material of the gasket 5, for example, polypropylene (PP), polyphenylene sulfide (PPS), polyether ether ketone (PEEK), or the like can be used.

  In the step (v), the power generation element is accommodated in the case 1 and the sealing plate 6 is disposed so as to close the opening of the case 1. Then, the edge part (opening edge part) of the side part of case 1 is bend | folded inside. Thereby, the gasket 5 is compressed and the lower end portion of the gasket 5 is in close contact with the bottom plate portion of the case. Further, the upper end portion of the gasket 5 is in close contact with the peripheral portion of the sealing plate 6.

  In step (vi), a solution or dispersion in which an insulating material such as a rubber-based material is dissolved or dispersed is applied and dried so that the end 1t of the side portion 1b of the case 1 is covered, and the insulating coating is applied. 8 may be formed. Thereby, exposure of the 2nd metal layer 12 in the edge part 1t is suppressed.

Next, taking a lithium battery as an example, a power generation element of a coin-type battery will be described.
The positive electrode 2 is formed by press molding the positive electrode mixture into a coin shape. The positive electrode mixture includes a positive electrode active material, a conductive additive, and a binder. The type of the positive electrode active material is not particularly limited, but is an oxide containing at least one selected from the group consisting of transition metals such as manganese, cobalt, nickel, magnesium, copper, iron, niobium, and vanadium (for example, manganese dioxide). Alternatively, a composite oxide can be used. A composite oxide containing lithium and containing at least one selected from the group consisting of metals such as manganese, cobalt, nickel, magnesium, copper, iron, and niobium (for example, LiCoO ₂ ) can also be used. Alternatively, fluorinated graphite can be used. A positive electrode active material may be used individually by 1 type, and may be used in combination of 2 or more type.

  As the conductive assistant, carbon black such as acetylene black and ketjen black and graphite such as artificial graphite can be used. A conductive support material may be used individually by 1 type, and may be used in combination of 2 or more type.

  Examples of the binder include fluororesin, styrene butadiene rubber (SBR), modified acrylonitrile rubber, and ethylene-acrylic acid copolymer. A binder may be used individually by 1 type, and may be used in combination of 2 or more type.

  The negative electrode 3 is, for example, lithium metal or lithium alloy formed into a coin shape. Examples of the lithium alloy include a Li—Al alloy, a Li—Sn alloy, a Li—Si alloy, and a Li—Pb alloy. The negative electrode 3 may be a negative electrode mixture containing a negative electrode active material and a binder that is pressure-molded into a coin shape. The type of the negative electrode active material is not particularly limited, but carbon materials such as natural graphite, artificial graphite, and non-graphitizable carbon, and metal oxides such as silicon oxide, lithium titanate, niobium pentoxide, and molybdenum dioxide may be used. it can. As a binder, the material illustrated as a material which can be used for a positive electrode, for example can be used arbitrarily. A conductive additive may be included in the negative electrode mixture.

The electrolytic solution includes a non-aqueous solvent and a solute (salt) dissolved in the non-aqueous solvent. The solute concentration in the electrolytic solution is preferably 0.3 to 2.0 mol / L. As the non-aqueous solvent, cyclic carbonate, chain carbonate, chain ether, cyclic ether and the like can be used. These may be used alone or in combination of two or more. As the solute, LiBF ₄ , LiPF 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 or the like is used.

  The separator 4 may be any material that can prevent a short circuit between the positive electrode 2 and the negative electrode 3. For example, a woven fabric, a nonwoven fabric, a microporous film or the like formed of polyolefin, polyester, or the like can be given.

  Next, the present invention will be specifically described based on examples. However, the following examples do not limit the present invention. In this example, a coin-type battery having a structure as shown in FIG. 1 was produced.

Example 1
(I) Case A clad material comprising a 40 μm thick first metal layer formed of aluminum and a 160 μm thick second metal layer formed of stainless steel (SUS430) was prepared. The clad material was drawn so that the first metal layer was on the outer surface, and a case 1 having a bottom plate portion diameter of 20 mm and a side portion 1b height of 2.8 mm was produced.

(Ii) Sealing plate A clad material comprising a 50 μm thick first metal layer formed of aluminum and a 200 μm thick second metal layer formed of stainless steel (SUS430) was prepared. The clad material was pressed so that the first metal layer became the outer surface, and a sealing plate 6 having a top plate portion 6a with a diameter of 17 mm was produced.

(Iii) Power generation element 100 parts by mass of manganese dioxide as a positive electrode active material, 7 parts by mass of graphite as a conductive additive, and 5 parts by mass of polytetrafluoroethylene as a binder are mixed to obtain a positive electrode mixture. Prepared. The positive electrode mixture was formed into a coin shape having a diameter of 15 mm and a thickness of 2 mm to produce the positive electrode 2. On the other hand, a metal lithium foil having a thickness of 0.6 mm was punched into a circle having a diameter of 16 mm to produce a negative electrode. As the electrolytic solution, an organic electrolytic solution in which LiClO ₄ was dissolved as a solute at a concentration of 1.0 mol / L in a non-aqueous solvent in which propylene carbonate and 1,2-dimethoxyethane were mixed at a volume ratio of 2: 1 was used. .

(Iv) Assembling the coin-type battery A polypropylene gasket 5 coated with a sealant made of bron asphalt and mineral oil is disposed inside the side portion 1b of the case 1, and a current collector made of SUS430 is disposed on the bottom plate portion 1a. A body (not shown) was placed, and the positive electrode 2 was placed thereon. Next, a polypropylene nonwoven fabric having a thickness of 300 μm was placed on the positive electrode 2 as the separator 4. Thereafter, the organic electrolyte was poured into the case 1. The negative electrode 3 was attached to the inside of the top plate portion 6 a of the sealing plate 6. Next, the sealing plate 6 was disposed so as to close the opening of the case 1, and the end portion of the side portion 1 b of the case 1 was crimped to the peripheral edge portion 6 b of the sealing plate 6 via the gasket 5. Next, styrene butadiene rubber dissolved in toluene was applied so as to cover the end 1t of the side 1b of the case 1 and dried to form the insulating coating 8.
Thereby, a coin-type battery A1 having a diameter of 20 mm, a thickness of 3.2 mm, and an electric capacity of 225 mAh was completed.

<< Comparative Example 1 >>
A clad material is not used as a material for the case and the sealing plate, and a stainless steel plate (SUS430) having a thickness of 2 μm formed on the outer surface side of the case is used as a material for the sealing plate. A coin type battery B1 was completed in the same manner as in Example 1 except that a 250 μm thick stainless steel plate (SUS430) having a 2 μm thick nickel plating layer formed on the outer surface side of the sealing plate was used.

Example 2
Example 1 except that the same clad material as in Example 1 was used as the material for the sealing plate, and a stainless steel plate having a nickel plating layer with a thickness of 2 μm on the outer surface side was used as the material for the case. Similarly, coin-type battery A2 was completed.

Example 3
The same clad material as that of Example 1 was used as the material of the case, and the stainless steel plate having a nickel plating layer having a thickness of 2 μm on the outer surface side was used as the material of the sealing plate as in Comparative Example 1. Similarly, coin-type battery A3 was completed.

[Evaluation]
Ten coin batteries of Examples 1 to 3 and Comparative Example 1 were prepared.
Processed meat (ham) made of pork as a raw material was placed on the bottom of a petri dish having a depth of 15 mm, and then physiological saline was poured into the petri dish instead of body fluid, so that the ham was completely immersed in physiological saline. Next, the battery for evaluation was placed on the ham so that the sealing plate was in contact with the ham. At this time, the bottom surface of the battery case was slightly below the surface of the physiological saline so that the battery would not float, so that a saline film was formed on the bottom surface of the case. In this state, it was left at 25 ° C. for 30 minutes. Then, when the state of the ham in contact with the sealing plate was visually observed, almost no discoloration was seen in the ham on which the batteries of Examples 1 and 2 were placed. A slight discoloration was observed in the ham on which the battery of Example 3 was placed. On the other hand, severe discoloration was observed in the ham on which the battery of Comparative Example 1 was placed. The ten batteries in each example all showed the same tendency.

  Next, the pH of the surface of the ham after removing the battery was measured, and an average value of 10 pieces was calculated for each. The results are shown in Table 1.

  From the above, according to the present invention, it has been clarified that even when a coin-type battery is accidentally swallowed by a living body, the harm to the living body can be greatly reduced.

  In the above embodiment, the first metal layer is formed of aluminum. However, even when the first metal layer is formed of aluminum alloy, magnesium, or magnesium alloy, it is considered that the safety of the coin-type battery can be similarly improved.

  The present invention can be applied to various batteries including a primary battery and a secondary battery such as a lithium battery, a lithium ion battery, an alkaline battery, and an alkaline storage battery, but particularly in a battery having a battery voltage exceeding 3.0 V (for example, a lithium battery). Useful.

  1: Case, 1a: Bottom plate portion, 1b: Side portion, 1t: End portion, 2: Positive electrode, 3: Negative electrode, 4: Separator, 5: Gasket, 6: Sealing plate, 6a: Top plate portion, 6b: Peripheral portion 6t: end, 8: insulating coating, 10: coin-type battery, 11, 61: first metal layer, 12, 62: second metal layer

Claims (7)

A case having a bottom plate portion and a side portion rising from a peripheral edge of the bottom plate portion;
A sealing plate having a top plate portion and a peripheral portion extending from the top plate portion to the inside of the side portion;
A gasket interposed between the side portion and the peripheral portion compressed and interposed,
A power generation element sealed by the case and the sealing plate;
At least one of the case and the sealing plate comprises a first metal layer provided on the outer surface side, and a second metal layer provided on the inner surface side than the first metal layer,
The coin-type battery, wherein the first metal layer includes at least one selected from the group consisting of aluminum and magnesium.   The coin-type battery according to claim 1, wherein the second metal layer includes at least one selected from the group consisting of stainless steel and titanium.   The coin-type battery according to claim 1 or 2, wherein at least one of the case and the sealing plate is formed of a clad material of the first metal layer and the second metal layer.   The coin-type battery according to any one of claims 1 to 3, wherein at least the sealing plate includes the first metal layer and the second metal layer. At least the case comprises the first metal layer and the second metal layer;
The coin-type battery according to any one of claims 1 to 4, wherein an end portion of the side portion is covered with an insulating material.   The coin-type battery according to claim 1, wherein the first metal layer has a thickness of 5 to 125 μm.   The coin-type battery according to any one of claims 1 to 6, wherein the thickness of the second metal layer is 125 to 250 µm.

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