Flat button battery

Abstract

To provide a flat button battery that can increase the amount of electrolyte impregnated on the positive electrode side without increasing the internal resistance of a battery, and in particular can significantly increase a discharge time of when discharging at a large current.SOLUTION: A flat button battery 1 includes: a bottomed cylindrical positive electrode can 12; and a negative electrode can 22 that is fixed to the inside of an opening 12a of the positive electrode can 12 with a gasket 40 interposed therebetween, and forms a housing space between the negative electrode can 22 and the positive electrode can 12. Therein, the housing space is sealed by provision of a caulked portion in which the opening 12a of the positive electrode can 12 is caulked to the negative electrode can 22 side; the housing space houses a positive electrode 10A, a negative electrode 20, a separator 30, and an electrolyte 50; the positive electrode 10A housed in the positive electrode can 12 is made of a pellet layer; and an electrolyte housing portion 11A is arranged near the outer peripheral wall 12c of the positive electrode can 12 in the pellet layer.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a flat button battery. [Background technology]

[0002] Coin-type or button-type batteries (hereafter referred to as button-type) are very small in size, and therefore the current they can output is also small. For this reason, for example, button-type alkaline manganese batteries and silver oxide batteries are designed for use in small electronic devices such as watches and calculators, and are optimally designed to consume very little current, on the order of a few μA to a few tens of μA, and to last for several years of continuous use.

[0003] The above-mentioned button batteries mainly include a cylindrical cathode can with a bottom and an anode can that is fixed to the inside of the opening of the cathode can with a gasket interposed therebetween and forms a sealed storage space between the cathode can and the anode can, and the storage space contains a cathode, an anode, a separator, and an electrolyte. Furthermore, such small button batteries are configured as flat batteries and are suitable for use in the above-mentioned small electronic devices.

[0004] On the other hand, conventional button batteries have the problem that when they are discharged with a large current, for example, more than several tens of mA, the reactions inside the battery cannot keep up, resulting in a large amount of unreacted negative and positive electrode active material, which ultimately shortens the discharge time. Furthermore, from the viewpoint of ensuring sufficient battery characteristics, it is preferable that a large amount of electrolyte is impregnated on the positive electrode side. However, in conventional button batteries, the electrolyte leaks out onto the negative electrode side, which, as mentioned above, results in a short discharge time.

[0005] In order to solve the above problems, a flat button battery has been proposed, which uses a positive electrode made of a pellet of compressed positive electrode mixture and has an electrolyte container in the center of the positive electrode on the positive electrode can side. Ru(For example, see Patent Document 1.) According to Patent Document 1, by adopting the above-described structure, it is possible to increase the amount of electrolyte impregnated in the positive electrode, and it is possible to increase the discharge time, particularly when discharging with a large current. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2020-119628 Summary of the Invention [Problem to be solved by the invention]

[0007] According to the flat button battery described in Patent Document 1, as described above, an electrolyte storage compartment is disposed on the positive electrode can side of the positive electrode, and it is said to be able to store a large amount of electrolyte. However, in the structure described in Patent Document 1, the electrolyte storage compartment is provided in the center of the positive electrode in a plan view, which increases the inter-electrode distance between this portion and the negative electrode, increasing the internal resistance of the battery and making it difficult to pass a large current, making the structure unsuitable for discharging a large current.

[0008] The mechanism by which the internal resistance of a battery increases when the structure described in Patent Document 1 is adopted is not entirely clear, but it is generally known that in a battery, the inter-electrode distance between the opposing positive and negative electrodes has a significant impact on the battery characteristics. That is, when the electrolyte storage compartment is located in the center of the positive electrode can side of the positive electrode, as in the flat button battery described in Patent Document 1, the shortest distance between the positive electrode and the negative electrode becomes less functional, which may result in inferior battery characteristics. Furthermore, in the structure described in Patent Document 1, the current flows while avoiding the electrolyte storage section located in the center of the pellet layer that forms the positive electrode, which results in a substantial increase in the distance between the positive electrode and the negative electrode, which is thought to be a factor in increasing internal resistance. Furthermore, when an electrolyte storage section is placed in the center of the pellet layer as in Patent Document 1, it is difficult to ensure a large contact area between the positive electrode and the electrolyte, which is also thought to be a factor in increasing internal resistance.

[0009] The present invention has been made in view of the above-mentioned problems, and aims to provide a flat button battery that can increase the amount of electrolyte impregnated in the positive electrode side without increasing the internal resistance of the battery, and that can significantly increase the discharge time, particularly when discharging at a large current. [Means for solving the problem]

[0010] The inventors of the present invention have conducted extensive research to solve the above problems, and have conducted repeated experiments to increase the amount of electrolyte impregnated in the positive electrode side and discharge a large current for a long period of time while suppressing an increase in internal resistance in a flat button battery. As a result, they have found that by optimizing the position of the electrolyte container in the pellet that constitutes the positive electrode, the internal resistance can be reduced and the discharge characteristics can be significantly improved, thereby completing the present invention.

[0011] That is, the flat button battery of the present invention comprises a cylindrical cathode can with a bottom, and an anode can fixed to the inside of the opening of the cathode can with a gasket interposed therebetween, forming a storage space between the cathode can and the anode can, and the storage space is sealed by providing a crimping portion that crimps the opening of the cathode can to the anode can, and the storage space is filled with: In order from the positive electrode can side to the negative electrode can side positive electrode, The separator and the negative electrode are accommodated in the accommodation space. A flat button battery containing an electrolyte, the positive electrode housed in the positive electrode can is made of a pellet layer, The pellet layer has a side surface that contacts the outer peripheral wall of the positive electrode can located around the pellet layer, and In the pellet layer, in the vicinity of the outer peripheral wall of the positive electrode can, A gap is located at least one between the inner peripheral surface of the outer peripheral wall of the positive electrode can and the pellet layer, or between the bottom surface of the positive electrode can and the pellet layer. The battery is characterized by having an electrolyte storage section disposed therein.

[0012] According to the present invention, as described above, in the pellet layer constituting the positive electrode, the electrolyte solution storage section is disposed near the outer peripheral wall of the positive electrode can, so that the amount of electrolyte solution that can be stored can be increased, and in particular, the amount of electrolyte solution impregnated on the positive electrode side can be increased. Furthermore, by arranging the electrolyte container on the outer wall side of the positive electrode can, the distance between the electrodes in the center of the battery, which particularly affects the battery characteristics, can be shortened, thereby reducing internal resistance and improving discharge characteristics. Furthermore, compared to when the electrolyte solution storage section is located in the center of the pellet layer, a larger contact area between the positive electrode and the electrolyte solution can be ensured, thereby effectively reducing internal resistance. Furthermore, since no electrolyte storage section is provided on the separator side of the pellet layer that constitutes the positive electrode, the contact area between the pellet layer and the separator can be maximized. This does not reduce the opposing area between the positive and negative electrodes, and therefore does not cause an increase in internal resistance. In addition, unlike when an electrolyte container is located in the center of the pellet layer constituting the positive electrode, the center of the pellet layer is in contact with the positive electrode can, so that when manufacturing a flat button battery, a position near the center of the bottom of the positive electrode can is ensured to withstand pressure from a punch jig, thereby reliably preventing deformation such as dents in the positive electrode can when assembling the flat button battery.

[0013] In addition, in the flat button battery of the present invention, in the above configuration, it is more preferable that the electrolyte solution storage section is arranged at a position in the pellet layer closer to the outer wall of the positive electrode can than the inner wall of the gasket.

[0014] According to the present invention, as described above, the electrolyte storage compartment is located on the inner peripheral wall of the gasket in the pellet layer constituting the positive electrode, i.e., closer to the outer peripheral wall of the positive electrode can than the sealing position of the gasket, thereby increasing the amount of electrolyte impregnated on the positive electrode side. Furthermore, as described above, the distance between the electrodes in the center of the battery can be shortened, and a large contact area between the positive electrode and the electrolyte can be secured. Furthermore, the contact area between the pellet layer and the separator can be maximized, thereby reducing internal resistance and realizing a flat button battery with excellent discharge characteristics.

[0015] In the flat button battery of the present invention, in the above configuration, the electrolyte container may be provided in a circular shape along the outer peripheral wall or bottom of the positive electrode can.

[0016] According to the present invention, as described above, the electrolyte container is provided in a circular shape along the outer wall or bottom of the positive electrode can, which, like the above, shortens the inter-electrode distance at the center of the battery, ensures a large contact area between the positive electrode and the electrolyte, and also ensures a maximum contact area between the pellet layer and the separator, thereby effectively reducing internal resistance and realizing a flat button battery with excellent discharge characteristics.

[0017] Furthermore, in the flat button battery of the present invention, in a configuration in which the electrolyte solution storage section is provided in a circular shape as described above, the electrolyte solution storage section may be arranged along the outer peripheral wall of the positive electrode can and be configured so as to open toward the outer peripheral wall.

[0018] According to the present invention, as described above, the electrolyte container is disposed along the outer wall of the positive electrode can and opens toward the outer wall, thereby shortening the inter-electrode distance at the center of the battery, ensuring a large contact area between the positive electrode and the electrolyte, and maximizing the contact area between the pellet layer and the separator. This effectively reduces internal resistance and realizes a flat button battery with superior discharge characteristics.

[0019] Furthermore, in the flat button battery of the present invention, in the configuration in which the electrolyte solution storage section is provided in a circular shape as described above, the electrolyte solution storage section may be arranged along the bottom of the positive electrode can and be configured to open toward the bottom side.

[0020] According to the present invention, as described above, the electrolyte container is disposed along the bottom of the positive electrode can and opens toward the bottom, thereby shortening the inter-electrode distance at the center of the battery, ensuring a large contact area between the positive electrode and the electrolyte, and maximizing the contact area between the pellet layer and the separator. This effectively reduces internal resistance and realizes a flat button battery with superior discharge characteristics.

[0021] Furthermore, in the flat button battery of the present invention, in the configuration in which the electrolyte solution storage section is provided in a circular ring shape as described above, the electrolyte solution storage section may be configured to open toward the outer wall side and the bottom side of the positive electrode can.

[0022] According to the present invention, as described above, the electrolyte container is provided so as to open toward the outer wall and bottom of the positive electrode can, which shortens the inter-electrode distance at the center of the battery, as well as ensuring a large contact area between the positive electrode and the electrolyte and maximizing the contact area between the pellet layer and the separator. This effectively reduces internal resistance and realizes a flat button battery with superior discharge characteristics.

[0023] Furthermore, in the flat button battery of the present invention, in the above configuration, a configuration may be adopted in which the electrolyte solution storage sections are arranged intermittently in multiple numbers along the outer peripheral wall and bottom of the positive electrode can, and are open toward the outer peripheral wall and the bottom.

[0024] According to the present invention, as described above, the electrolyte containers are arranged intermittently along the outer wall and bottom of the positive electrode can, and are open toward the outer wall and bottom, thereby ensuring a larger contact area between the positive electrode and the electrolyte, and thus more effectively reducing internal resistance. Furthermore, as described above, the distance between the electrodes at the center of the battery can be shortened, and the contact area between the pellet layer and the separator can be maximized, thereby more effectively reducing internal resistance and realizing a flat button battery with superior discharge characteristics.

[0025] Furthermore, in the flat button battery of the present invention having the above-mentioned configuration, it is also possible to employ a configuration in which an impregnating material or a hydrophilic material is housed in the electrolyte housing portion.

[0026] According to the present invention, as described above, the impregnated material or hydrophilic member is housed in the electrolyte solution housing, so that the electrolyte solution can be impregnated into the impregnated material, or the hydrophilic member can easily house and retain the electrolyte solution using an aqueous solvent. This allows the amount of electrolyte solution impregnated, particularly on the positive electrode side, to be increased, making it possible to discharge a large current. [Effects of the Invention]

[0027] As described above, the flat button battery of the present invention employs a configuration in which the positive electrode housed in the positive electrode can is made of a pellet layer and an electrolyte container is disposed in the pellet layer near the outer wall of the positive electrode can, thereby increasing the electrolyte capacity, particularly the amount of electrolyte impregnated on the positive electrode side, thereby reducing internal resistance and enabling high-current discharge. Furthermore, in the flat button battery of the present invention, the electrolyte container is located on the outer wall of the positive electrode can, thereby shortening the distance between the electrodes at the center of the battery, which is thought to have a particularly adverse effect on battery performance, thereby reducing internal resistance. Furthermore, compared to when the electrolyte container is located at the center of the pellet layer, a larger contact area between the positive electrode and the electrolyte can be ensured, effectively reducing internal resistance and enabling high-current discharge. Furthermore, by not providing an electrolyte storage section on the separator side of the pellet layer and maximizing the contact area between the pellet layer and the separator, a large opposing area between the positive and negative electrodes is ensured, preventing an increase in internal resistance and enabling discharge with a larger current. [Brief explanation of the drawings]

[0028] [Figure 1] FIG. 1 is a cross-sectional view schematically showing a flat button battery according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view schematically showing a flat button battery according to a second embodiment of the present invention. [Figure 3] FIG. 3 is a cross-sectional view schematically showing a flat button battery according to a third embodiment of the present invention. [Figure 4] FIG. 4 is a perspective view schematically showing a positive electrode provided in a flat button battery according to a fourth embodiment of the present invention. [Figure 5] FIG. 5 is a perspective view schematically showing a positive electrode provided in a flat button battery according to a fifth embodiment of the present invention. [Figure 6] FIG. 6 is a perspective view schematically showing a positive electrode provided in a flat button battery according to a sixth embodiment of the present invention. [Figure 7] FIG. 7 is a side view schematically showing a positive electrode provided in a flat button battery according to another embodiment of the present invention. [Figure 8] FIG. 8 is a side view schematically showing a positive electrode provided in a flat button battery according to another embodiment of the present invention. [Figure 9] FIG. 9 is a side view schematically showing a positive electrode provided in a flat button battery according to another embodiment of the present invention. [Figure 10] FIG. 10 is a cross-sectional view schematically showing a modification of the flat button battery according to the first embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0029] Hereinafter, embodiments of the flat button battery of the present invention will be described in detail, with reference to Figures 1 to 10. The flat button battery described in the present invention is specifically a primary or secondary battery in which an active material used as a positive or negative electrode, a separator, and an electrolyte are housed in a container.

[0030] In addition, the drawings used in the following description may show characteristic portions enlarged for convenience in order to make the features of the present invention easier to understand, and the dimensional ratios of each component may not necessarily be the same as in reality. Furthermore, the materials and shapes exemplified in the following description are merely examples, and the present invention is not limited to them and can be implemented with appropriate changes within the scope of the present invention.

[0031] First Embodiment A flat button battery 1 according to a first embodiment of the present invention will be described below with reference to FIG. FIG. 1 is a cross-sectional view schematically showing a flat button battery 1 according to the first embodiment.

[0032] 1 is a so-called button (coin) type battery. This flat button battery 1 is generally configured by including, in a container 2, a positive electrode 10A containing a positive electrode active material, a negative electrode 20 containing a negative electrode active material, a separator 30 disposed between the positive electrode 10A and the negative electrode 20, a gasket 40 for sealing the storage space of the container 2, and an electrolyte 50.

[0033] More specifically, the flat button battery 1 of this embodiment has a cylindrical positive electrode can 12 with a bottom, and a cylindrical (hat-shaped) negative electrode can 22 with a lid that is fixed to the opening 12a of the positive electrode can 12 with a gasket 40 interposed therebetween, forming a storage space between the positive electrode can 12 and the negative electrode can 22. In the flat button battery 1, the periphery of the opening 12a of the positive electrode can 12 shown in Fig. 1 is crimped inward, i.e., toward the negative electrode can 22, thereby forming a storage container 2 in which the storage space is sealed by the gasket 40.

[0034] In the storage space sealed by the storage container 2 shown in FIG. 1, a positive electrode 10A provided on the inner bottom surface side of the positive electrode can 12 and a negative electrode 20 provided on the negative electrode can 22 side are arranged opposite each other with a separator 30 interposed therebetween. As shown in FIG. 1, the gasket 40 ,negativeThe gasket 40 is disposed so as to enclose the outer peripheral edge of the electrode can 22 from both the inner and outer peripheral sides, and the outer peripheral edge of the gasket 40 is surrounded by the peripheral edge 12 b of the positive electrode can 12 . In addition, in the flat button battery 1 of this embodiment, a separator 30 is provided along the bottom surface of the gasket 40 so as to divide the storage space of the storage container 2 into upper and lower halves, and the positive electrode 10A is accommodated between the separator 30 and the bottom surface of the positive electrode can 12, and the negative electrode 20 is accommodated between the separator 30 and the negative electrode can 22.

[0035] 1, the flat button battery 1 has a configuration in which the positive electrode can 12 also serves as a positive electrode current collector, and the negative electrode can 22 also serves as a negative electrode current collector, but this is not limiting. For example, a configuration may be adopted in which the positive electrode 10A is electrically connected to the inner surface of the positive electrode can 12 via a positive electrode current collector (not shown), and the negative electrode 20 is electrically connected to the inner surface of the negative electrode can 22 via a negative electrode current collector (not shown).

[0036] (Positive and negative electrode cans) 1, the storage container 2 used in the flat button battery 1 of this embodiment includes a cylindrical positive electrode can 12 with a bottom, and a negative electrode can 22 that is fixed to the opening 12a of the positive electrode can 12 via a gasket 40, which will be described in detail later, and forms a storage space between the positive electrode can 12 and the negative electrode can 22. As described above, the storage container 2 is a roughly coin-shaped (button-shaped) container in which the storage space is sealed by crimping the opening 12a of the positive electrode can 12 to the negative electrode can 22. Therefore, the maximum inner diameter of the positive electrode can 12 is larger than the maximum outer diameter of the negative electrode can 22.

[0037] As described above, the cathode can 12 constituting the storage container 2 is configured as a bottomed cylinder having a circular opening 12a in plan view. The material of the cathode can 12 can be any known material without any restrictions, including stainless steels such as SUS304, SUS316L, SUS329J4L, and NAS64, as well as cold-rolled steel. Preferably, a nickel layer is formed on the surface of the cathode can 12 by plating or pressure welding.

[0038] As described above, the negative electrode can 22 is configured in a covered cylindrical (hat-shaped) shape, with its tip 22a slightly protruding from the opening 12a into the positive electrode can 12. As with the material of the positive electrode can 12, the material for the negative electrode can 22 may be conventionally known stainless steel or cold-rolled steel, and the same material as the positive electrode can 12 may be used. Alternatively, the negative electrode can 22 may be made of, for example, a clad material obtained by pressure-welding copper, nickel, or the like to stainless steel.

[0039] The thickness of the metal plate material used for the positive electrode can 12 and the negative electrode can 22 is generally about 0.1 to 0.3 mm, and for example, the positive electrode can 12 and the negative electrode can 22 can be configured to have an average thickness of about 0.20 mm throughout the entire body.

[0040] 1, the tip portion 22a of the negative electrode can 22 is folded back along the outer surface of the negative electrode can 22, but this is not limiting. For example, the present invention can also be applied to a negative electrode can 22 that does not have the above-described folded back shape, in which the tip portion 22a is the end face of a metal plate.

[0041] As shown in FIG. 1, the positive electrode can 12 and the negative electrode can 22 are sealed with a gasket 40 interposed therebetween by crimping the peripheral edge 12b of the positive electrode can 12 toward the negative electrode can 22 to form a crimped sealing portion, thereby forming a storage space and providing a sealed structure for the flat button battery 1.

[0042] Furthermore, examples of flat button batteries to which the configuration described in detail in this embodiment can be applied include various primary battery types, such as alkaline batteries, manganese batteries, and silver oxide batteries. Examples of secondary batteries include various types of batteries, such as the button (coin) type nonaqueous electrolyte secondary batteries described below. These various flat button batteries can be made in various known sizes.

[0043] (gasket) As shown in FIG. 1, gasket 40 is formed in an annular shape along the inner circumferential surface of positive electrode can 12, and tip portion 22a of negative electrode can 22 is placed inside an annular groove 41 thereof. Gasket 40 is composed of a ring-shaped outer edge portion having an outer diameter that allows it to be inserted tightly into the inner periphery of the opening of positive electrode can 12, a ring-shaped inner edge portion, and a bottom wall portion that connects the lower ends of the outer edge portion and the inner edge portion. Therefore, the upper surface of the outer periphery of gasket 40 is formed with the above-mentioned annular groove 41, into which front end 22a of negative electrode can 22 can be inserted.

[0044] The material of the gasket 40 can be any conventionally known material that is suitable for use in button batteries, without any restrictions. For example, if the flat button battery is an alkaline primary battery, which is a type of primary battery, a polyamide such as nylon can be used. Furthermore, when the flat button battery is a battery using a non-aqueous electrolyte, details of which will be described later, the gasket 40 can be made of plastic resins such as polypropylene resin (PP), polyphenyl sulfide (PPS), polyethylene terephthalate (PET), polyamide, liquid crystal polymer (LCP), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer resin (PFA), polyether ether ketone resin (PEEK), polyether nitrile resin (PEN), polyether ketone resin (PEK), polyarylate resin, polybutylene terephthalate resin (PBT), polycyclohexane dimethylene terephthalate resin, polyether sulfone resin (PES), polyamino bismaleimide resin, polyetherimide resin, and fluororesin.

[0045] A sealant may be applied to the inner surface of the annular groove 41 of the gasket 40. Examples of such a sealant include asphalt, epoxy resin, polyamide resin, and butyl rubber adhesive. After the sealant is applied to the inside of the annular groove 41, it can be dried before use.

[0046] The gasket 40 is sandwiched between the positive electrode can 12 and the negative electrode can 22, and at least a portion of it is compressed. The compression ratio at this time is not particularly limited, and it should be within a range that can reliably seal the inside of the flat button battery 1 and does not cause breakage of the gasket 40.

[0047] [If the flat button battery is an alkaline primary battery] The configurations (compositions) of the positive electrode 10A, negative electrode 20, and electrolyte 50 when the flat button battery is an alkaline primary battery will be described below.

[0048] (positive electrode) When the flat button battery is an alkaline primary battery, the positive electrode 10A is preferably formed from a disk-shaped pellet layer made of mixed particles such as manganese dioxide particles and silver oxide particles. This positive electrode (pellet layer) 10 is made of a cylindrical molded body obtained by compressing raw material mixed particles, which are a positive electrode mixture obtained by mixing particles of a positive electrode active material described later with necessary amounts of conductive additive particles and additive particles. The density of this molded body is, for example, 4.5 to 6.0 g / cm. 3 It can be about.

[0049] In this embodiment, for example, manganese dioxide (MnO) particles, silver oxide (AgO, AgO) particles, particles of silver nickelite, etc., conductive additive particles such as graphite (Gr) particles or graphite particles, and hydrogen storage alloy particles are mixed as additives, and this mixture can be used as raw material mixed particles.

[0050] In addition to the conductive additives and hydrogen storage alloys described above, the additives contained in the positive electrode 10A may also include, if necessary, a binder for enhancing the adhesion between particles. Examples of such binders include polyvinylidene fluoride (PVDF), styrene butadiene rubber (SBR), polyacrylic acid (PA), carboxymethyl cellulose (CMC), polyimide (PI), and polyamide-imide (PAI), and these may be used singly or in combination of two or more.

[0051] In the disk-shaped positive electrode 10A, an electrolyte solution storage portion 11A is formed in the positive electrode 10A near the outer peripheral wall 12c of the positive electrode can 12. In the example shown in Fig. 1 etc., the electrolyte solution storage portion 11A is formed in a position in the positive electrode 10A closer to the outer peripheral wall 12c of the positive electrode can 12 than to the inner peripheral wall 40a of the gasket 40. Here, the two-dot chain line L shown in Fig. 1 is a line indicating the position of the inner peripheral wall 40a of the gasket 40. Furthermore, the electrolyte solution storage section 11A in the illustrated example has a circular cutout shape in plan view, with the inner corners stepped, at a position about halfway through the thickness of the positive electrode 10A from the bottom surface 10b side of the positive electrode 10A that contacts the bottom 12d of the positive electrode can 12. This ensures a space between the electrolyte solution storage section 11A and the positive electrode can 12. The upper surface 10a of the positive electrode 10A is in contact with the separator 30.

[0052] As described above, in the flat button battery 1 of this embodiment, the electrolyte storage capacity can be increased by forming the electrolyte storage section 11A in the pellet layer constituting the positive electrode 10A near the outer peripheral wall 12c of the positive electrode can 12. This allows the amount of electrolyte impregnated, particularly on the positive electrode 10A side, to be increased, enabling large current discharge. Furthermore, by arranging the electrolyte solution storage section 11A on the outer wall 12c side of the positive electrode can 12, it is possible to shorten the inter-electrode distance at the center of the battery, which particularly affects the battery characteristics. This reduces the internal resistance of the entire battery, making it possible to discharge a large current, thereby improving the discharge characteristics. Furthermore, by adopting a configuration including the electrolyte solution storage portion 11A as described above, a larger contact area between the positive electrode 10A and the electrolyte can be ensured compared to, for example, a case where the electrolyte solution storage portion is disposed in the center of the pellet layer constituting the positive electrode. This allows the internal resistance of the entire battery to be more effectively reduced, making it possible to discharge at a larger current and further improving discharge characteristics. Furthermore, since no electrolyte solution storage section is provided on the separator 30 side of the pellet layer constituting the positive electrode 10A, it is possible to maximize the contact area between the positive electrode (pellet layer) 10 and the separator 30. This prevents a decrease in the opposing area between the positive and negative electrodes, thereby preventing an increase in internal resistance. In addition, unlike when an electrolyte container is located in the center of the pellet layer constituting the positive electrode, the center of the pellet layer is in contact with the positive electrode can 12, so that when manufacturing the flat button battery 1, the portion near the center of the bottom 12d of the positive electrode can 12 can be made durable against pressure from a punching tool (not shown). This reliably prevents deformation such as dents from occurring in the positive electrode can 12 when assembling the flat button battery 1.

[0053] 1, if the electrolyte solution storage section 11A is formed in the pellet layer constituting the positive electrode 10A on the inner peripheral wall 40a of the gasket 40, i.e., on the outer peripheral wall 12c side of the positive electrode can 12 relative to the sealing position of the gasket 40, the amount of electrolyte impregnated on the positive electrode 10A side can be further increased. As described above, the inter-electrode distance in the center of the battery can be shortened, and the contact area between the positive electrode 10A and the electrolyte can be increased. Furthermore, the contact area between the positive electrode 10A and the separator 30 can be maximized. This effectively reduces internal resistance, resulting in a flat button battery 1 with superior discharge characteristics.

[0054] In the example shown in FIG. 1, the electrolyte storage section 11A has a stepped notch formed in a circular shape in a plan view across the bottom surface 10b and the side surface 10c of the positive electrode 10A to secure the space therein. However, this is not limited to this configuration in the present embodiment. For example, as in the example of the electrolyte storage section 11K shown in FIG. 10, a configuration may be adopted in which the space is secured by a chamfered portion 10d having a shape in which the corners are uniformly cut across the bottom surface 10b and the side surface 10c of the positive electrode 10A. In such a case, the corner-cut shape of the chamfered portion 10d may be an overall non-uniform shape, such as by reducing the ratio of the chamfered shape to the thickness of the positive electrode 10A, or may have a shape that includes some steps. Furthermore, as will be described in detail in other embodiments below, the shape and the position where the electrolyte solution container is formed can be set as appropriate.

[0055] In addition to the electrolyte, for example, an impregnating material or a hydrophilic material (not shown) may be disposed inside the electrolyte solution storage section 11A. The impregnating material is not particularly limited as long as it is a material that can be impregnated with the electrolyte, but for example, a thickener made of a water-soluble polymer (carboxyvinyl polymer, sodium polyacrylate (PAS), carboxymethyl cellulose (CMC)), etc. can be used. As the hydrophilic member, for example, inorganic compounds such as hydrophilic fume silica, nonwoven fabrics made of cellulose fibers or glass fibers, etc. can be used. However, when the flat button battery 1 is an alkaline primary battery, it is desirable to avoid using impregnating materials or hydrophilic materials that may react with or dissolve in alkaline electrolyte. Alternatively, the above-mentioned impregnating material or hydrophilic member may be housed in the electrolyte solution housing portion 11A, and the electrolyte solution described below may be impregnated into these.

[0056] As described above, by accommodating an impregnating material or a hydrophilic member in the electrolyte solution accommodating section 11A, the electrolyte solution can be impregnated into the impregnating material, or an electrolyte solution using a water-based solvent can be easily accommodated and held in the hydrophilic member. This allows the amount of electrolyte solution impregnated, particularly on the positive electrode 10A side, to be increased, enabling a larger current to be discharged.

[0057] (Negative electrode) The negative electrode 20 may have an electrode structure in which, for example, a negative electrode active material powder such as zinc powder or zinc alloy powder, a conductivity stabilizer such as zinc oxide (ZnO), a gelling agent such as carboxymethyl cellulose (CMC) or polyacrylic acid (PAS), a viscoelasticity adjuster such as resin powder, PP (polypropylene), or polyethylene (PE) is mixed, and an electrolyte solution is added to the mixture. The viscoelasticity adjuster added to the negative electrode 20 is added as needed and may be omitted.

[0058] (electrolyte) The electrolyte is not particularly limited, but it is preferable to use an electrolyte with high viscosity, and when the flat button battery 1 is an alkaline primary battery, for example, an aqueous solution of sodium hydroxide (NaOH) or potassium hydroxide (KOH) can be used. Furthermore, when the battery is intended for large current output applications, an aqueous solution of potassium hydroxide is particularly suitable.

[0059] In the flat button battery 1 shown in Fig. 1, the positive electrode (pellet layer) 10 is impregnated with the electrolyte, and the electrolyte accommodating portion 11A is also filled with the electrolyte 50. In this way, the amount of electrolyte held inside the battery, particularly on the positive electrode 10A side, increases by the amount of electrolyte 50 accommodated in the electrolyte accommodating portion 11A compared to a structure without the electrolyte accommodating portion 11A. Furthermore, if the electrolyte accommodating portion 11A is configured to accommodate an impregnating material or hydrophilic member as described above, the electrolyte is accommodated in the electrolyte accommodating portion 11A in a state of being impregnated therein.

[0060] 1, the presence of electrolyte solution storage compartment 11A allows a larger amount of electrolyte to be held compared to a flat button battery without electrolyte solution storage compartment 11A. Furthermore, because no electrolyte solution storage compartment is provided on the portion of positive electrode 10A facing separator 30, the contact area between positive electrode 10A and separator 30 can be maximized without sacrificing the opposing area between the positive and negative electrodes, and without causing an increase in the internal resistance of the battery.

[0061] When manufacturing the flat button battery 1 having the structure shown in FIG. 1, it is desirable to accommodate the electrolyte in the electrolyte accommodating portion 11A in a manner that does not trap air.

[0062] [An example where the flat button battery is a non-aqueous electrolyte secondary battery] The flat button battery 1 having the structure illustrated in FIG. 1 is not limited to the alkaline primary battery described above, but can also be applied to batteries with other configurations. An example of the configuration (composition) of the positive electrode 10A, the negative electrode 20, and the electrolyte solution 50 when the flat button battery 1 is a non-aqueous electrolyte secondary battery will be described below.

[0063] (positive electrode) When the flat button battery 1 is a non-aqueous electrolyte secondary battery, lithium manganese oxide particles can be used as the positive electrode active material. The positive electrode active material used in the positive electrode may contain other positive electrode active materials in addition to lithium manganese oxide particles, and may be configured to include a pellet layer containing one or more of other oxide particles such as molybdenum oxide particles, lithium iron phosphate compound particles, lithium cobalt oxide particles, lithium nickel oxide particles, and vanadium oxide particles.

[0064] (Negative electrode) When the flat button battery 1 is a non-aqueous electrolyte secondary battery, the type of negative electrode active material in the negative electrode 20 is not particularly limited, but it is preferable that the negative electrode active material contains, for example, silicon oxide particles or aluminum alloy particles. Furthermore, in the negative electrode 20, silicon oxide particles expressed as SiOx (0≦x<2) can also be used as the negative electrode active material.

[0065] (electrolyte) When the flat button battery 1 is a non-aqueous electrolyte secondary battery, the electrolyte solution used is usually one in which a supporting salt is dissolved in a non-aqueous solvent. When the flat button battery 1 is a non-aqueous electrolyte secondary battery, for example, the non-aqueous solvent constituting the electrolyte solution may contain tetraglyme (TEG) as the main solvent, diethoxyethane (DEE) as the secondary solvent, and further contain ethylene carbonate (EC) and vinylene carbonate (VC) as additives. Examples of the main solvent that can be used to form the glyme-based solvent include tetraglyme, triglyme, pentaglycle, and diglyme.

[0066] In this embodiment, the electrolyte solution may be a non-aqueous solvent containing ethylene carbonate (EC), tetraglyme (TEG), and diethoxyethane (DEE). By adopting such a configuration, DEE and TEG are solvated with the Li ions that form the supporting salt. At this time, since DEE has a higher donor number than TEG, DEE selectively solvates with Li ions. In this way, DEE and TEG solvate the Li ions that form the supporting salt, thereby protecting the Li ions. This prevents the reaction between water and Li even if moisture enters the nonaqueous electrolyte secondary battery under a high-temperature, high-humidity environment, thereby suppressing a decrease in discharge capacity and improving storage characteristics.

[0067] Even when the flat button battery 1 is a nonaqueous electrolyte secondary battery, as in the alkaline primary battery described above, the electrolyte capacity can be increased, particularly by increasing the amount of electrolyte impregnated on the positive electrode 10A side, thereby enabling high-current discharge. Furthermore, as described above, the distance between the electrodes at the center of the battery can be shortened, thereby reducing the overall internal resistance of the battery and enabling high-current discharge, thereby improving discharge characteristics. Furthermore, since a large contact area between the positive electrode 10A and the electrolyte can be secured, the overall internal resistance of the battery can be more effectively reduced, enabling higher-current discharge, thereby further improving discharge characteristics. Furthermore, since no electrolyte storage compartment is provided on the separator 30 side of the positive electrode 10A, the contact area between the positive electrode 10A and the separator 30 can be maximized, thereby preventing an increase in internal resistance without reducing the opposing area between the positive and negative electrodes.

[0068] [Another example where the flat button battery is a non-aqueous electrolyte secondary battery] The configurations (compositions) of the positive electrode 10A, negative electrode 20, and electrolyte 50 when the flat button battery 1 is another example of a nonaqueous electrolyte secondary battery different from the nonaqueous electrolyte secondary battery described above will be described below.

[0069] (positive and negative electrodes) When the flat button battery is another example of a nonaqueous electrolyte secondary battery, the positive electrode 10A includes a positive electrode active material made of lithium cobaltate particles, conductive additive particles, and binder particles, and the negative electrode 20 includes a negative electrode active material made of lithium titanate particles, a conductive additive made of graphite particles, and binder particles, thereby forming a so-called CTL battery. When the flat button battery is the above-mentioned nonaqueous electrolyte secondary battery, the negative electrode 20 may contain a conductive additive in an amount of 7% by mass or more and less than 10% by mass relative to the total mass of the negative electrode 20 .

[0070] (electrolyte) When a flat button battery is another example of a nonaqueous electrolyte secondary battery, an electrolyte solution containing at least an organic solvent and a supporting salt can be used. The electrolyte solution can be a mixed solvent containing, as the organic solvent, propylene carbonate (PC), which is a cyclic carbonate solvent, ethylene carbonate (EC), which is a cyclic carbonate solvent, and ethyl methyl carbonate (EMC), which is a chain carbonate solvent. Such an electrolyte solution is usually made by dissolving a supporting salt in a non-aqueous solvent such as an organic solvent, and its properties are determined taking into consideration the heat resistance, viscosity, and other properties required of the electrolyte solution.

[0071] In this example, the organic solvent used in the electrolyte solution can be a mixed solvent containing cyclic carbonate solvents PC and EC and chain carbonate solvent EMC, thereby realizing a nonaqueous electrolyte secondary battery that can obtain sufficient discharge capacity over a wide temperature range and supply a large current. Specifically, the use of PC and EC as cyclic carbonate solvents, which have high dielectric constants and high solubility for supporting electrolytes, allows for a large discharge capacity. Furthermore, because PC and EC have high boiling points, the resulting electrolyte solution is less likely to volatilize, even when used or stored in a high-temperature environment. Furthermore, by mixing PC, which has a lower melting point than EC, with EC as the cyclic carbonate solvent, it is possible to improve low-temperature properties. Furthermore, by using EMC, which has a low melting point, as the chain carbonate solvent, the low-temperature properties are improved.

[0072] Examples of the cyclic carbonate solvent include propylene carbonate (PC), ethylene carbonate (EC), butylene carbonate (BC), trifluoroethylene carbonate (TFPC), chloroethylene carbonate (ClEC), trifluoroethylene carbonate (TFEC), difluoroethylene carbonate (DFEC), and vinylene carbonate (VEC).

[0073] <Second embodiment> A flat button battery 60 according to a second embodiment of the present invention will be described below with reference to FIG. FIG. 2 is a cross-sectional view schematically showing a flat button battery 60 according to the second embodiment. In the following description, components common to or similar to the flat button battery 1 according to the first embodiment described above will be denoted by the same reference numerals, and detailed description thereof may be omitted.

[0074] Although only a cross section viewed from the side of the flat button battery 60 of this embodiment is shown in Figure 2, the flat button battery 60 differs from the flat button battery 1 of the first embodiment shown in Figure 1 only in that the electrolyte solution storage section 11B provided in the positive electrode 10B is formed in a circular ring shape along the outer peripheral wall 12c of the positive electrode can 12.

[0075] Specifically, the electrolyte solution storage section 11B provided in the positive electrode 10B of the flat button battery 60 is formed in a ring shape over the entire side surface 10c, approximately at the center in the thickness direction of the side surface 10c, as shown in the example in Fig. 2. Moreover, the electrolyte solution storage section 11B in the illustrated example is formed as a recess with a rectangular cross section on the side surface 10c of the positive electrode 10B.

[0076] Other configurations of the flat button battery 60 of the second embodiment are similar to those of the flat button battery 1 of the first embodiment shown in FIG.

[0077] According to the flat button battery 60 of this embodiment, as described above, in the pellet layer constituting the positive electrode 10B, the electrolyte solution storage portion 11B is formed in a circular ring shape along the outer peripheral wall 12c of the positive electrode can 12, so that the amount of electrolyte solution that can be stored can be increased, as described above. This allows the amount of electrolyte impregnated, particularly on the positive electrode 10B side, to be increased, making it possible to discharge a large current. Furthermore, by arranging the electrolyte solution storage section 11B on the outer wall 12c side of the positive electrode can 12, the distance between the electrodes in the center of the battery, which particularly affects the battery characteristics, can be shortened. As a result, as described above, the internal resistance of the entire battery is reduced, it becomes possible to discharge a large current, and the discharge characteristics are improved. Furthermore, by providing the electrolyte solution storage section 11B, a larger contact area between the positive electrode 10B and the electrolyte can be ensured compared to when the electrolyte solution storage section is located in the center of the positive electrode. As a result, as described above, the internal resistance of the entire battery can be reduced more effectively, making it possible to discharge a larger current and further improving the discharge characteristics. Furthermore, no electrolyte solution storage section is provided on the separator 30 side of the positive electrode 10B, i.e., on the upper surface 10a of the positive electrode 10B, and the contact area between the positive electrode 10B and the separator 30 is maximized. This prevents a decrease in the opposing area between the positive and negative electrodes, thereby preventing an increase in internal resistance.

[0078] 2, when the electrolyte storage section 11B is formed in the positive electrode 10B at a position closer to the outer peripheral wall 12c of the positive electrode can 12 than the inner peripheral wall 40a of the gasket 40, the amount of electrolyte impregnated on the positive electrode 10B side can be further increased. As described above, the inter-electrode distance in the center of the battery can be shortened, and the contact area between the positive electrode 10B and the electrolyte can be increased. Furthermore, the contact area between the positive electrode 10B and the separator 30 can be maximized. This effectively reduces internal resistance, resulting in a flat button battery 60 with superior discharge characteristics.

[0079] 2, the electrolyte solution storage section 11B provided in the flat button battery 60 of this embodiment has a space secured by a recess with a uniform rectangular cross section, but this is not limited to this in this embodiment. For example, the electrolyte solution storage section 11B may have a space secured by a recess with a trapezoidal, triangular, or semicircular cross section formed on the side surface 10c of the positive electrode 10B, or may have a shape that includes some steps.

[0080] <Third embodiment> A flat button battery 61 according to a third embodiment of the present invention will be described below with reference to FIG. FIG. 3 is a cross-sectional view schematically showing a flat button battery 61 according to the third embodiment. In the following description, components common to or similar to the flat button batteries 1 and 60 according to the first and second embodiments will be denoted by the same reference numerals, and detailed description thereof may be omitted.

[0081] The flat button battery 61 of this embodiment is shown only in cross section as viewed from the side in Figure 3, but differs from the flat button battery 60 of the second embodiment shown in Figure 2 only in that the electrolyte storage section 11C provided in the positive electrode 10C is formed in a circular ring shape along the bottom 12d of the positive electrode can 12.

[0082] 3, the electrolyte container 11C provided in the positive electrode 10C of the flat button battery 61 is formed in a ring shape in a plan view at a position on the bottom surface 10b near the outer peripheral wall 12c of the positive electrode can 12. In addition, the electrolyte container 11C in the illustrated example is formed as a recess with a rectangular cross section on the bottom surface 10b of the positive electrode 10C.

[0083] Other configurations of the flat button battery 61 of the third embodiment are similar to those of the flat button battery 1 of the first embodiment shown in FIG. 1 and the flat button battery 60 of the second embodiment shown in FIG.

[0084] In the flat button battery 61 of this embodiment, as described above, the electrolyte container 11C of the positive electrode 10C is formed in a circular shape in plan view along the bottom 12d of the positive electrode can 12. This, as described above, shortens the inter-electrode distance at the center of the battery, increases the contact area between the positive electrode and the electrolyte, and maximizes the contact area between the pellet layer and the separator. As a result, as in the flat button batteries 1, 60 of the first and second embodiments, the internal resistance of the entire battery is reduced, enabling high-current discharge. Furthermore, the amount of electrolyte contained can be increased, and the amount of electrolyte impregnated on the positive electrode 10C side can be increased, enabling higher-current discharge.

[0085] Furthermore, in this embodiment, as in the example shown in Figure 3, if the electrolyte storage section 11C is formed in the positive electrode 10C at a position closer to the outer wall 12c of the positive electrode can 12 than to the inner wall 40a of the gasket 40, the internal resistance is more effectively reduced for the same reasons as above, and a flat button battery 61 with better discharge characteristics can be realized.

[0086] 3, the electrolyte solution storage section 11C provided in the flat button battery 61 of this embodiment has a space secured by a recess with a uniform rectangular cross section, but this is not limited to this in this embodiment either. As with the electrolyte solution storage section 11B provided in the flat button battery 60 of the second embodiment, the space secured by a recess with a trapezoidal, triangular, or semicircular cross section formed on the side surface 10c of the positive electrode 10C may also be a shape that includes a slight step.

[0087] <Fourth embodiment> A flat button battery according to a fourth embodiment of the present invention will be described below mainly with reference to FIG. FIG. 4 is a perspective view schematically showing a positive electrode 10D provided in a flat button battery according to a fourth embodiment.

[0088] In the following description, components common to or similar to those of the flat button batteries 1, 60, and 61 according to the first to third embodiments are denoted by the same reference numerals and will not be described in detail. Furthermore, the flat button battery of this embodiment has the same configuration as the flat button batteries 1, 60, and 61 described above, except for the structure of the electrolyte solution storage portion in the positive electrode. Therefore, only the positive electrode 10D is shown in Fig. 4, and the other components will be described with reference to Figs. 1 to 3 as appropriate.

[0089] The cathode 10D included in the flat button battery of this embodiment has an annular electrolyte storage compartment 11D that is disposed along the outer peripheral wall 12c of the cathode can 12 and opens toward the outer peripheral wall 12c (see also the flat button batteries 1, 60, and 61 shown in FIGS. 1 to 3). The cathode 10D of the example shown in FIG. 4 also has an electrolyte storage compartment 11D that is disposed along the bottom 12d of the cathode can 12 and opens toward the bottom 12d. That is, the cathode 10D of the example shown in FIG. 4 has an electrolyte storage compartment 11D that opens toward both the outer peripheral wall 12c and the bottom 12d of the cathode can 12. Furthermore, the illustrated positive electrode 10D has a plurality of electrolyte solution storage sections 11D arranged discontinuously along the outer peripheral wall 12c and bottom 12d of the positive electrode can 12. That is, the electrolyte solution storage section 11D provided in the positive electrode 10D is formed so as to be open from the side surface 10c side to the bottom surface 10b side of the positive electrode 10D, and is provided so as to be intermittently arranged in a circular ring shape. In the illustrated example, a total of six electrolyte solution storage sections 11D are arranged at equal intervals along the circumferential direction of the positive electrode 10D.

[0090] In the flat button battery of this embodiment, as described above, the electrolyte container 11D is configured to open toward the outer wall 12c or the bottom 12d of the positive electrode can 12, or toward both the outer wall 12c and the bottom 12d. This, as described above, shortens the inter-electrode distance in the center of the battery, increases the contact area between the positive electrode 10D and the electrolyte, and maximizes the contact area between the positive electrode 10D and the separator 30. This effectively reduces internal resistance, enables high-current discharge, and realizes a flat button battery with superior discharge characteristics.

[0091] Furthermore, in the flat button battery of this embodiment, if multiple electrolyte containers 11D are arranged discontinuously along the outer wall 12c and bottom 12d of the positive electrode can 12, as in the illustrated example, the contact area between the positive electrode 10D and the electrolyte can be further increased. This further reduces the internal resistance, enabling discharge with an even larger current and achieving a flat button battery with even better discharge characteristics.

[0092] 4, the electrolyte solution storage section 11D provided in the positive electrode 10D is also provided with a recess having a generally uniform rectangular cross section, similar to the electrolyte solution storage sections in the above-described embodiments, but is not limited thereto. The electrolyte solution storage section 11D may be provided with a recess having a trapezoidal, triangular, or semicircular cross section, for example, formed on either or both of the side surface 10c and the bottom surface 10b of the positive electrode 10D, and the space may be provided by such a recess, or the electrolyte solution storage section 11D may have a shape including some steps.

[0093] <Fifth embodiment> A flat button battery according to a fifth embodiment of the present invention will be described below mainly with reference to FIG. FIG. 5 is a perspective view schematically showing a positive electrode 10E provided in a flat button battery according to a fifth embodiment.

[0094] As with the fourth embodiment, the flat button battery of this embodiment has the same configuration as the flat button batteries of the above-mentioned embodiments, except for the structure of the electrolyte storage section in the positive electrode. Therefore, only the positive electrode 10E is shown in FIG. 5, and the other configurations will be described with reference to FIGS. 1 to 3 as appropriate.

[0095] The positive electrode 10E included in the flat button battery of this embodiment has an electrolyte solution storage compartment 11E that is disposed along the outer peripheral wall 12c and bottom 12d of the positive electrode can 12 and is formed in an annular, discontinuous manner so as to open toward both the outer peripheral wall 12c and bottom 12d (see also FIGS. 1 to 3). That is, the electrolyte solution storage compartment 11E provided in the positive electrode 10E is formed as a recess with a rectangular cross section that opens to both the side surface 10c and bottom surface 10b of the positive electrode 10D, and is provided in multiple, discontinuous annular configuration, similar to the positive electrode 10D of the fourth embodiment shown in FIG. 4. In the example shown in FIG. 5, the electrolyte solution storage compartments 11E are disposed at a total of six locations at equal intervals along the circumferential direction of the positive electrode 10E.

[0096] 5, the electrolyte solution accommodating portion 11E penetrates between the bottom 12d side and the opening 12a of the positive electrode can 12. That is, the illustrated positive electrode 10E differs from the positive electrode 10D shown in FIG. 4 in that the electrolyte solution accommodating portion 11E penetrates in the thickness direction of the positive electrode 10E.

[0097] In the flat button battery of this embodiment, as described above, the electrolyte container 11E penetrates between the bottom 12d side of the positive electrode can 12 and the opening 12a, thereby ensuring a larger contact area between the positive electrode 10E and the electrolyte and enabling a larger amount of electrolyte to be contained. This further reduces internal resistance, enabling high-current discharge, and realizing a flat button battery with superior discharge characteristics.

[0098] Meanwhile, since the electrolyte solution accommodating portion 11E is provided so as to penetrate the positive electrode 10E in the thickness direction, the electrolyte solution accommodating portion 11E is also exposed on the separator 30 side. However, the reduction in the contact area between the positive electrode 10E and the separator 30 due to the exposure of the electrolyte solution accommodating portion 11E is slight, and therefore the effect obtained by the flat button battery of this embodiment is also slight. From this perspective, it is desirable to adjust the shape and dimensions of the positive electrode 10E so that the exposed area of ​​the electrolyte solution accommodating portion 11E on the separator 30 side is as small as possible.

[0099] 5, similar to the electrolyte solution storage portions in the above-described embodiments, the electrolyte solution storage portion 11E provided in the positive electrode 10E is formed in the positive electrode 10E and has a recess with a generally uniform rectangular cross section to provide a space, but is not limited thereto. As in the above-described embodiments, the electrolyte solution storage portion 11E may have a space provided by a recess with a trapezoidal, triangular, or semicircular cross section formed on either or both of the side surface 10c and the bottom surface 10b of the positive electrode 10E, or may have a shape including a slight step.

[0100] Sixth Embodiment A flat button battery according to a sixth embodiment of the present invention will be described below mainly with reference to FIG. FIG. 6 is a perspective view schematically showing a positive electrode 10F provided in a flat button battery according to a sixth embodiment.

[0101] As with the fourth and fifth embodiments, the flat button battery of this embodiment has the same configuration as the flat button batteries of the above-mentioned embodiments, except for the structure of the electrolyte storage section in the positive electrode. Therefore, only the positive electrode 10F is shown in FIG. 6, and the other configurations will be described with reference to FIGS. 1 to 3 as appropriate.

[0102] The positive electrode 10F provided in the flat button battery of this embodiment is similar to the positive electrode 10B provided in the flat button battery 60 of the second embodiment shown in Figure 2 in that the electrolyte storage section 11F is arranged along the outer peripheral wall 12c of the positive electrode can 12 and is arranged so as to open toward the outer peripheral wall 12c. On the other hand, the positive electrode 10F illustrated in FIG. 6 differs from the positive electrode 10B illustrated in FIG. 2 in that it is open not only on the outer wall 12c side of the positive electrode can 12 but also on the opening 12a side, i.e., on the separator 30 side.

[0103] In the flat button battery of this embodiment, as described above, the electrolyte container 11F is configured to open both toward the outer wall 12c and toward the opening 12a of the positive electrode can 12, thereby ensuring a large contact area between the positive electrode 10F and the electrolyte and increasing the amount of electrolyte that can be contained. This effectively reduces internal resistance, enabling high-current discharge, and realizing a flat button battery with excellent discharge characteristics.

[0104] On the other hand, because the electrolyte solution storage section 11F is open toward the opening 12a of the positive electrode can 12, the electrolyte solution storage section 11F is also exposed to the separator 30, as in the case of the positive electrode 10E of the fifth embodiment. However, as in the case of the fifth embodiment, the reduction in the contact area between the positive electrode 10F and the separator 30 due to the exposure of the electrolyte solution storage section 11F is slight, and therefore the effect obtained by the flat button battery of this embodiment is also slight. From this perspective, as described above, it is desirable to adjust the shape and dimensions of the positive electrode 10F so that the exposed area of ​​the electrolyte solution storage section 11F toward the separator 30 is as small as possible.

[0105] 6 also has a space provided by a recess having a rectangular cross section formed in the positive electrode 10F and having a uniform shape overall, similar to the electrolyte solution storage portions in the above-described embodiments, but is not limited thereto. The electrolyte solution storage portion 11F may have a shape including, for example, a slight step or inclined portion, similar to the above.

[0106] <Another embodiment of the flat button battery> A flat button battery according to another embodiment of the present invention will now be described. 7 to 9 are side views schematically showing positive electrodes 10G, 10H, and 10J provided in flat button batteries according to other embodiments of the present invention.

[0107] The positive electrode 10G shown in FIG. 7 has a larger recess on the side surface 10c than the positive electrode 10B provided in the flat button battery 60 shown in FIG. 2, thereby increasing the capacity of the electrolyte storage section 11G. Such a positive electrode 10G can increase the capacity of the electrolyte solution and significantly increase the contact area between the positive electrode 10G and the electrolyte solution, thereby significantly reducing the internal resistance of the battery, enabling high-current discharge and significantly improving discharge characteristics.

[0108] In addition, the positive electrode 10H shown in FIG. 8 is different from the positive electrode 10A provided in the flat button battery 1 shown in FIG. 1 in that the electrolyte storage section 11H opens toward the opening 12a of the positive electrode can 12, i.e., toward the separator 30, and the chamfered portion 10d formed by corner cutting has a gentle taper angle (see also FIGS. 1 to 3). With this positive electrode 10H, the chamfered portion 10d has a gentle taper angle. Therefore, even if the electrolyte storage compartment 11H is open toward the separator 30, the reduction in the contact area between the positive electrode 10H and the separator 30 is minimal, thereby fully achieving the benefits of the flat button battery of this embodiment. Furthermore, by configuring the chamfered portion 10d to be longer, a sufficient contact area between the positive electrode 10H and the electrolyte can be ensured. This significantly reduces the internal resistance of the battery, enabling high-current discharge and significantly improving discharge characteristics.

[0109] In addition, the positive electrode 10J shown in Figure 9 has a larger recess that opens across the side surface 10c and the top surface 10a, compared to the positive electrode 10F shown in Figure 6, thereby increasing the capacity of the electrolyte solution storage section 11J. As with the case of the above-described positive electrode 10G, this positive electrode 10J can increase the amount of electrolyte to be accommodated and significantly increase the contact area between the positive electrode 10J and the electrolyte, thereby significantly reducing the internal resistance of the battery, enabling discharge at a large current and significantly improving the discharge characteristics.

[0110] <Action and effect> As described above, the flat button batteries 1, 60, 61 of this embodiment employ a configuration in which positive electrodes 10A, 10B, 10C housed in positive electrode can 12 are made of a pellet layer, and electrolyte solution housing portions 11A, 11B, 11C are formed in the pellet layer near outer peripheral wall 12c of positive electrode can 12. This allows for an increased amount of electrolyte to be housed, and in particular, allows for an increased amount of electrolyte solution 50 impregnated on the positive electrode 10A, 10B, 10C side, making it possible to discharge a large current. Furthermore, by arranging the electrolyte solution containers 11A, 11B, and 11C on the outer peripheral wall 12c side of the positive electrode can 12, the distance between the electrodes at the center of the battery, which is thought to have a particular effect on the battery characteristics, can be shortened, thereby reducing internal resistance. Furthermore, compared to when the electrolyte solution containers are arranged at the center of the positive electrodes, a larger contact area can be ensured between the positive electrodes 10A, 10B, and 10C and the electrolyte 50, thereby effectively reducing internal resistance and enabling large current discharge. Furthermore, by not providing an electrolyte storage section on the separator 30 side of the positive electrodes 10A, 10B, and 10C and maximizing the contact area between the positive electrodes 10A, 10B, and 10C and the separator 30, a large opposing area between the positive and negative electrodes is ensured, which prevents an increase in internal resistance and enables discharge with a larger current. In addition, unlike when an electrolyte container is located in the center of the pellet layer constituting the positive electrode, the center of the pellet layer is in contact with the positive electrode can 12, so that the portion near the center of the bottom 12d of the positive electrode can 12 can be made durable against pressure from a punch tool when manufacturing the flat button battery 1, 60, 61. This makes it possible to reliably prevent deformation such as dents from occurring in the positive electrode can 12 when assembling the flat button battery 1, 60, 61. [Example]

[0111] The present invention will now be described in more detail with reference to examples and comparative examples. Note that the scope of the present invention is not limited by these examples, and the flat button battery according to the present invention can be modified as appropriate within the scope of the present invention.

[0112] <Fabrication of flat button batteries> [Example] 1, a flat button battery 1 was fabricated in which a gasket 40 was interposed between the cathode can 12 and the anode can 22 to secure the anode can 22 to the inside of the opening 12a of the cathode can 12, and the anode can 22 was then crimped and sealed to form a storage space between the cathode can 12 and the anode can 22, and the storage space contained a cathode 10A, an anode 20, a separator 30, and an electrolyte 50. In this example, a flat button battery 1 (Example: FIG. 1) having a configuration according to the present invention was fabricated, in which an electrolyte storage section 11A was formed in the cathode 10A near the outer peripheral wall 12c of the cathode can 12. In this example, a flat button battery was fabricated with n=3. In this example, a flat button battery (44 type) having an outer diameter of 11.6 mm and a thickness of 5.4 mm in the cross-sectional views shown in FIGS. 1 to 3 was fabricated.

[0113] In fabricating the flat button battery 1, first, a mixture of 92 mass% silver oxide (AgO), 5 mass% manganese dioxide, 2 mass% graphite, and 1 mass% lanthanum nickel (LaNi5) was prepared as the positive electrode mixture for the positive electrode 10A. The average particle size of the silver oxide was 10 μm, that of the manganese dioxide was 30 μm, that of the graphite was 15 μm, and that of the lanthanum nickel was 35 μm.

[0114] Next, the positive electrode mixture made of the mixed particles was compression molded into a disk-shaped pellet (outer diameter 11.0 mm, thickness 1.8 mm) to prepare a positive electrode 10A made of a pellet layer. Here, in the step of producing positive electrode 10A by compression molding, a recess was formed by cutting a portion of the pellet layer, thereby producing positive electrode 10A capable of securing electrolyte solution storage portion 11A as shown in FIG. The molding density in this case was 5.5 g / cm 3 It was decided. Furthermore, 35 mg of the electrolyte solution was dropped onto each of the positive electrodes 10A to impregnate them.

[0115] In addition, 343 mg of a negative electrode mixture was obtained by mixing 64 mass% zinc powder, 2.5 mass% zinc oxide powder, 2.50 mass% CMC (carboxymethyl cellulose) as a gelling agent, 30.99 mass% potassium hydroxide aqueous solution as an electrolyte, and 0.01 mass% lithium hydroxide (LiOH), as a negative electrode mixture for the negative electrode 20.

[0116] Next, the positive electrodes 10A prepared by the above procedure were housed in multiple positive electrode cans 12 made of nickel-plated iron, a separator 30 was placed on top of them, and a ring-shaped gasket 40 was inserted into the positive electrode can 12 in a press-fit form. Next, the negative electrode mixture was placed on the separator 30, and the negative electrode can 22 was placed on top of this with a gasket 40 interposed therebetween. Then, the opening 12a of the positive electrode can 12 was crimped to produce the flat button battery 1 (flat alkaline primary battery) of this example. The separator 30 used was made of polyethylene film, cellophane, and nonwoven fabric, and the gasket 40 used was made of polyamide.

[0117] [Comparative Example 1] A flat button battery of Comparative Example 1 was produced under the same conditions and by the same procedures as in the above-mentioned Example, except that the electrolyte solution storage portion was not formed when producing the positive electrode. In Comparative Example 1, three flat button batteries were fabricated with n=3.

[0118] Comparative Example 2 A flat button battery of Comparative Example 2 was produced under the same conditions and by the same procedures as those of the above-mentioned Example, except that, in producing the positive electrode, an electrolyte storage section was formed in the center of the bottom side of the positive electrode, and the electrolyte storage section was made into a recessed shape with an outer diameter of 6.8 mm and a depth of 0.5 mm. In Comparative Example 2, a flat button battery was fabricated with n=3.

[0119] <Evaluation of flat button batteries> The internal resistance of the flat button batteries of Example and Comparative Examples 1 and 2 obtained by the above procedure was measured as an impedance value at 1 kHz AC using a commercially available LCR meter with the R function. At this time, the internal resistance of the flat button batteries of each example was measured under temperature conditions in a room temperature (25°C) environment. Furthermore, the ohmic resistance of each member constituting the flat button battery was measured by measuring the ohmic loss (IR drop) based on the voltage drop at the beginning of discharge when the battery was discharged at a discharge current of 100 mA. Further, the discharge capacity was measured at a discharge current of 100 mA and a cut-off voltage of 0.4 V. The evaluation results of the flat button batteries of Example and Comparative Examples 1 and 2 under the above conditions are shown in Table 1 below.

[0120] [Table 1]

[0121] <Evaluation results> The internal resistance of the flat button batteries of the Example and Comparative Examples 1 and 2 was measured under the above conditions. As shown in Table 1, the average measured internal resistance of the flat button battery 1 of the Example was 3.35 ohms. The measured internal resistances of Comparative Examples 1 and 2 were 4.26 ohms and 3.33 ohms, respectively. These results confirmed that the internal resistance of the flat button battery 1 of the Example was lower than that of the flat button battery of Comparative Example 1, which did not have an electrolyte reservoir in the positive electrode. In contrast, there was almost no difference in internal resistance between the flat button battery 1 of the Example and the flat button battery of Comparative Example 2, which had an electrolyte reservoir in the center of the bottom surface of the positive electrode.

[0122] On the other hand, as shown in Table 1, when the discharge current was set to 100 mA, the IR drop, which is based on the voltage drop at the beginning of discharge, was smaller for the flat button battery 1 of the example than for either of the comparative examples 1 or 2. This result confirmed that the flat button battery 1 of the example has superior internal resistance characteristics, which affect large current discharge, compared to the flat button batteries of comparative examples 1 and 2. Regarding the discharge capacity, no clear difference was observed between the Example and Comparative Examples 1 and 2.

[0123] From the results of the above-described examples, it was confirmed that the use of a positive electrode having the structure defined in the present invention can suppress an increase in internal resistance, and it is clear that the flat button battery having the structure according to the present invention is capable of discharging at a large current and therefore has excellent discharge characteristics. [Industrial Applicability]

[0124] The flat button battery of the present invention can increase the amount of electrolyte impregnated in the positive electrode without increasing the internal resistance of the battery, and can significantly increase the discharge time, particularly when discharging at a large current. Therefore, by applying the flat button battery of the present invention to small electronic devices such as watches and calculators, it can contribute to improving the performance of various electronic devices. [Explanation of symbols]

[0125] 1,60,61...Flat button battery 2...Storage container 10A, 10B, 10C, 10D, 10E, 10F, 10G, 10H, 10J... Positive electrode (pellet layer) 10a…Top surface 10b…Bottom surface 10c...side 10d... Chamfered part 11A, 11B, 11C, 11D, 11E, 11F, 11G, 11H, 11J, 11K...Electrolyte storage section 12...Positive electrode can 12a...Opening 12b...periphery 12c...Outer wall 12d...Bottom 20...Negative electrode 22...Anode can 22a...Tip 30...Separator 40...Gasket 40a…Inner peripheral wall 41...Annular groove 50...Electrolyte

Claims

1. a cylindrical positive electrode can with a bottom; an anode can fixed to the inside of the opening of the cathode can with a gasket interposed therebetween, forming a storage space between the anode can and the cathode can; a flat button battery in which the accommodation space is sealed by providing a crimping portion that crimps an opening of the positive electrode can to the negative electrode can, a positive electrode, a separator, and a negative electrode are accommodated in the accommodation space in this order from the positive electrode can side to the negative electrode can side, and an electrolyte is accommodated in the accommodation space; a flat button battery, characterized in that the positive electrode contained in the positive electrode can is made of a pellet layer, the pellet layer has a side surface that contacts the outer wall of the positive electrode can located around the pellet layer, and an electrolyte container is disposed in the pellet layer near the outer wall of the positive electrode can, the electrolyte container being located at least either between the inner surface of the outer wall of the positive electrode can and the pellet layer or between the bottom of the positive electrode can and the pellet layer.

2. 2. The flat button battery according to claim 1, wherein the electrolyte container is disposed in the pellet layer at a position closer to the outer wall of the positive electrode can than the inner wall of the gasket.

3. 3. The flat button battery according to claim 1, wherein the electrolyte container is provided in a circular shape along the outer peripheral wall or the bottom of the positive electrode can.

4. 4. The flat button battery according to claim 3, wherein the electrolyte container is disposed along the outer peripheral wall of the positive electrode can and is provided so as to open toward the outer peripheral wall.

5. 4. The flat button battery according to claim 3, wherein the electrolyte container is disposed along the bottom of the positive electrode can and is open toward the bottom.

6. 4. The flat button battery according to claim 3, wherein the electrolyte container is provided so as to open toward the outer wall and the bottom of the positive electrode can.

7. 3. The flat button battery according to claim 1, wherein a plurality of the electrolyte solution storage sections are arranged intermittently along the outer peripheral wall and the bottom of the positive electrode can, and are provided so as to open toward the outer peripheral wall and the bottom.

8. 8. The flat button battery according to claim 1, wherein the electrolyte solution storage section contains an impregnating material or a hydrophilic material.

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