Air battery and battery pack using same

An air battery for use by being stacked in a battery pack has a cathode constituting member and an anode material adapted such that at least a part of the anode material is brought into direct contact with a cathode constituting member of another air battery. In this configuration, it is possible to eliminate the need to use an anode cap for sealing on the anode side and thereby possible to achieve not only reduction in weight and size but also reduction in cost.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims priority to Japanese Patent Application Nos. 2012-012966, filed Jan. 25, 2012 and 2013-007478, filed Jan. 18, 2013, each incorporated herein in its entirety.

TECHNICAL FIELD

The present invention relates to an air battery and a battery pack having air batteries stacked together.

BACKGROUND

Japanese Laid-Open Patent Publication No. 2000-67824 discloses the use of air batteries as a so-called battery pack. More specifically, the battery pack of Japanese Laid-Open Patent Publication No. 2000-67824 has three button-type air batteries vertically connected in series and placed in a metal exterior can, with an insulating sheet interposed between the air batteries and the exterior can, such that the air batteries are insulated from the exterior can by the insulating sheet.

Each of the air batteries includes: a cathode can formed of a metal material in a bottomed-cylindrical shape with one end open and storing therein an anode active material e.g. zinc and an electrolyte e.g. aqueous potassium hydroxide solution; and an anode cap closing the open end of the cathode can.

In the battery pack of Japanese Laid-Open Patent Publication No. 2000-67824, however, the weight ratio of the anode plate (anode cap) is large. This causes unsolved problems such as difficulty in weight reduction and hindrance to size reduction.

SUMMARY

In view of the foregoing, it is an object of the present invention to provide an air battery with no structural part corresponding to the anode cap so as to achieve not only reduction in weight and size but also reduction in cost. It is also an object of the present invention to provide a battery pack using such an air battery.

As a solution to the above-mentioned problems, there is provided according to one aspect of the present invention an air battery for use by being stacked in a battery pack, comprising an anode material and a cathode constituting member with a conductive fluid-tight air-permeable film, wherein the anode material of the air battery is adapted such that at least a part of the anode material of the air battery is brought into direct contact with a conductive fluid-tight air-permeable film of a cathode constituting member of another air battery adjacent thereto. In this configuration, the air battery can establish electrical conduction between the adjacent air batteries, without the use of the anode material and the structural part corresponding to the anode cap, and achieve not only reduction in weight and size but also reduction in cost.

It is possible in the present invention to eliminate the need for the structural part corresponding to the conventional anode cap and achieve not only reduction in weight and size but also reduction in cost.

DESCRIPTION OF EMBODIMENTS

Hereinafter, embodiments of the present invention will be described below with reference to the drawings.FIG. 1is a cross-section view of a battery pack using an air battery according to the first embodiment of the present invention.

As shown inFIG. 1, the battery pack is exemplified as a battery pack B having three air batteries: two air batteries A1and A1, each of which is according to the first embodiment of the present invention, and one air battery A0vertically stacked together.

The air battery A1according to the first embodiment includes a frame member10, a contact member20, a cathode constituting member30, an electrolyte and separator layer40and an anode material50. In the first embodiment, the frame member10is made of an electrolyte-resistant resin such as polypropylene (PP) or engineering plastic material and exhibits electrical insulation properties. As the material of the frame member10, there can alternatively be used a fiber-reinforced plastic material (FRP) in which reinforcing fibers such as carbon fibers or glass fibers are mixed to ensure mechanical strength. The use of the electrolyte-resistant resin such as polypropylene (PP) or engineering plastic material leads to weight reduction. It should however be noted that it is essential for the frame member10to exhibit electrical insulation properties as mentioned above in the first embodiment. The term “electrolyte” herein refers to an aqueous or non-aqueous solution containing potassium hydroxide (KOH) or chloride as a main component.

In the first embodiment, the frame member10is cylindrical is shape with both ends open. An engagement portion10bis provided around the entire inner circumferential edge part of one open end face (upper end face)10aof the frame member10for engagement of the contact member20(explained in detail later).

Air flow holes11aare made in a circumferential wall11of the frame member10, at a height position facing the after-mentioned fluid-tight air-permeable film31and at predetermined angular intervals about the axis O, so as to provide air communication between the inside and outside of the circumferential wall11. The engagement portion10bis formed as a step with an inner diameter equal to an outer diameter of the contact member20and a height substantially equal to a height of the contact member20.

The contact member20is made of a conductive metal material and brought into electrical conduction with the after-mentioned fluid-tight air-permeable film31and with the after-mentioned cathode material32and into contact with the frame member10of the another adjacent (upper-side) air battery A1.

In the first embodiment, the contact member20has a ring shape with an outer diameter engageable in the engagement portion10band a height that makes its end face flush with the open end face10aof the frame member10by engagement of the contact member20in the engagement portion10b.

Air flow holes21aare made in a circumferential wall21of the contact member20, at a height position facing the air flow holes11aand at the same angular intervals as the air flow holes11a, so as to provide air communication between the inside and outside of the circumferential wall21.

In the first embodiment, the cathode constituting member30is provided with a fluid-tight air-permeable film31, a cathode material32and a collector33. Herein, the cathode constituting member30has a conductive layer structure containing a catalyst for oxygen reduction reaction of the cathode material32and a conduction path forming material such as carbon powder. A binder may also be used to form the catalyst and the carbon powder into a layer shape.

The fluid-tight air-permeable film31exhibits conductivity in addition to fluid tightness and air permeability. The fluid-tight air-permeable film31is formed with a plurality of fine pores for gas supply (air supply) to the cathode material and is made of a fluoro resin, etc. capable of preventing the electrolyte from leaking to the outside. In the first embodiment, the fluid-tight air-permeable film31has a circular shape, when viewed in plane, with an outer diameter equal to an inner diameter of the contact member20. In other words, the fluid-tight air-permeable film31is adapted to cover an outer surface32aof the cathode material32. The fluid-tight air-permeable film31has the feature of allowing a flow of gas such as air by its air permeability while blocking a flow of fluid by its fluid tightness or water tightness.

The collector33is formed as an apertured conductive body of stainless steel, Cu, Ni, carbon or the like. The aperture rate of the collector33can be set as appropriate depending on the conductivity of the cathode material32. In the case of using a wire mesh as the collector33, for example, the aperture rate of the collector33is set equivalent to 50 to 600 mesh. There can alternatively be used a carbon paper as the collector33.

In the first embodiment, the collector33has a circular shape with an outer diameter equal to the inner diameter of the contact member20when viewed in plan. For example, the collector33is in the form of a conductive wire mesh whose apertures are sized to allow a flow of ions there through. The arrangement of the collector33leads to improvement in conductivity and mechanical strength.

The cathode material32is a conductive porous material containing a catalyst. For example, the cathode material32is in the form of a porous body prepared from a carbon material and a binder resin and carrying therein a catalyst such as manganese dioxide.

The anode material50is a pure metal such as Li, Al, Fe, Zn or Mg or an alloy containing one or more of such metals as a main component and is adapted such that a part or the whole of the anode material50is brought into direct contact with the cathode constituting member30of the another adjacent air battery A1. In the case of placing the air battery A0at the lowermost position and stacking two air batteries A1on the air battery A0as shown inFIG. 1, the entire lower surface of the anode material50of the upper-side air battery A1faces the conductive fluid-tight air-permeable film31of the cathode constituting member30of the lower-side air battery A1or A0. Accordingly, the upper-side air battery A1and the lower-side air battery A1or A0are electrically conducted and connected in series to each other when at least the part of the anode material50of the upper-side air battery A1is brought into press contact with the fluid-tight air-permeable film31of the cathode constituting member30of the lower-side air battery A1or A0as will be explained later.

In the first embodiment, the anode material50has a plate shape with an outer diameter equal to an inner diameter of the frame member10and a height that allows the lower surface50aof the anode material50to be flush with or slightly protrude toward the lower side from the lower end face10cof the frame member10. This eliminates the need for a conventionally required collector plate like a collector plate22of the lowermost-side air battery A0ofFIG. 1.

The air battery A0is structurally the same as the air battery A1except that the collector plate22is arranged on the lower end face10cof the frame member10. The other parts and portions of the air battery A0are the same as those of the air battery A1and thus are designated by the same reference numerals inFIG. 1to omit repeated explanations thereof.

The collector plate22is made of a conductive material capable of preventing the electrolyte from leaking to the cartridge outside. As such a material, there can be used stainless steel, copper (alloy) or a metal material having a surface coated with a plating of corrosion resistant metal.

Next, the assembling of the above-mentioned air batteries into the battery pack B will be explained below. When the air battery A1is stacked on the lowermost-side air battery A0, the upper end face20aof the contact member20and the upper end face10aof the frame member10of the air battery A0are brought into contact with the lower end face10cof the frame member10of the air battery A1.

Simultaneously, the lower surface50aof the anode material50of the air battery A1is brought into intimate contact with and into electrical conduction with the fluid-tight air-permeable film31of the air battery A0. By this, the upper-side air battery A1and the lower-side air battery A0are connected in series to each other. Each of these air batteries easily allows a flow of air since the air flow holes11aand21aare made in the frame member10and the contact member20, respectively.

When the another air battery A1is stacked on this air battery A1, the upper end face20aof the contact member20and the upper end face10aof the frame member10of the lower-side air battery A1are brought into contact with the lower end face10cof the frame member10of the upper-side air battery A1. Simultaneously, the lower surface50aof the anode material50of the upper-side air battery A1is brought into intimate contact with and into electrical conduction with the fluid-tight air-permeable film31of the lower-side air battery A1. By this, the upper-side air battery A1and the lower-side air battery A1are connected in series to each other. As in the above case, each of these air batteries easily allows a flow of air since the air flow holes11aand21aare made in the frame member10and the contact member20, respectively.

In the above configuration, the conductive fluid-tight air-permeable film31is utilized so as to secure a large contact surface with the anode material. This leads to reduction in electrical resistance at a contact interface between the anode material and the fluid-tight air-permeable film. This also enables monitoring of the degree of wear of the anode material as a voltage change occurs in response to a change of anode surface area in current-controlled operation.

As explained above, there is no need to use any structural part corresponding to the conventional anode cap for sealing. There is also no need to provide the collector plate20in the air battery A1as is different from the air battery A0. It is therefore possible to achieve not only reduction in weight and size but also reduction in cost and facilitate battery assembling due to the reduction of parts count.

Next, an air battery according to the second embodiment of the present invention will be explained below with reference toFIG. 2.FIG. 2is a cross-section view of the air battery according to the second embodiment of the present invention. In the second embodiment, parts and portions that are the same as or similar to those in the above embodiment are designated by the same or similar reference numerals to avoid repeated explanations thereof.

The air battery A2according to the second embodiment has a frame member and an anode material that are of different shapes. The anode material50A includes a small-diameter region50A′ made equal in diameter to an inner diameter of the frame member10A and a large-diameter region50A″ made larger in diameter than the small-diameter region50A′.

The frame member10A is cylindrical in shape with both ends open. An engagement portion10bis provided around the entire inner circumferential edge part of one open end face (upper end face)10aof the frame member10for engagement of the conductive fluid-tight air-permeable film31.

Another engagement portion10dis provided around the entire inner circumferential edge part of the other open end face (lower end face)10cof the frame member10for engagement of the large-diameter region50A″ of the anode material50A. Further, the anode material50A is adapted such that the entire lower surface of the anode material50A is brought into direct contact with a cathode constituting member30of another adjacent air battery A1and, more specifically, brought into direct contact with a fluid-tight air-permeable film31of the cathode constituting member30of the another adjacent air battery A1.

In the above configuration, the conductive fluid-tight air-permeable film31is utilized so as to secure a large contact surface with the anode material as in the case of the first embodiment. This leads to reduction in electrical resistance at a contact interface between the anode material and the fluid-tight air-permeable film. This also enables monitoring of the degree of wear of the anode material as a voltage change occurs in response to a change of anode surface area in current-controlled operation.

An air battery according to the third embodiment of the present invention will be explained below with reference toFIG. 3.FIG. 3is a cross-section view of the air battery according to the third embodiment of the present invention. In the third embodiment, parts and portions that are the same as or similar to those in the above-mentioned embodiments are designated by the same or similar reference numerals to avoid repeated explanations thereof.

The air battery A3according to the third embodiment has a frame member and an anode material that are of different shapes as in the case of the second embodiment. The anode material50B has a substantially trapezoidal cross-sectional area gradually increasing from an upper surface50ato the vicinity of a lower surface50bthereof. Further, the anode material50B is adapted such that the entire lower surface of the anode material50A is brought into direct contact with a cathode constituting member30of another adjacent air battery A3and, more specifically, brought into direct contact with a fluid-tight air-permeable film31of the cathode constituting member30of the another adjacent air battery A3.

The frame member10B is cylindrical in shape with both ends open. An engagement portion10eis provided around the entire inner circumferential edge part of one open end face (lower end face)10bof the frame member10for engagement of the anode material50B. In the above configuration, it is possible for the air battery A3to obtain the same effects as those of the air battery A2.

An air battery according to the fourth embodiment of the present invention will be explained below with reference toFIG. 4.FIG. 4is a cross-section view of a stack of two air batteries according to the fourth embodiment of the present invention. In the fourth embodiment, parts and portions that are the same as or similar to those in the above-mentioned embodiments are designated by the same or similar reference numerals to avoid repeated explanations thereof.

The air battery A4according to the fourth embodiment has an anode material50A and a conductive fluid-tight air-permeable film31formed with an outer diameter D2larger than an outer diameter D1of the anode material50A. This enables the fluid-tight air-permeable film31, which is larger in size than the anode material50A, to perform a seal function even when perforation occurs of the anode material50A by dissolution during continuous use.

An air battery according to the fifth embodiment of the present invention will be explained below with reference toFIG. 5.FIG. 5is a cross-section view of a stack of two air batteries according to the fifth embodiment of the present invention. In the fifth embodiment, parts and portions that are the same as or similar to those in the above-mentioned embodiments are designated by the same or similar reference numerals to avoid repeated explanations thereof.

The air battery A5according to the fifth embodiment has a conductive fluid-tight air-permeable film31and an anode material50C adapted to, when the fluid-tight air-permeable film31of the air battery A5is brought into contact with the anode material50C of the another adjacent air battery A5, form an air flow path for air flow at a contact interface there between (as indicated by an arrow).

Although not shown inFIG. 5, the air flow path is formed by making a groove in the contact surface (particularly, surface50″) of the anode material50C or by making a groove in the contact surface of the fluid-tight air-permeable film31.

The air battery A5has a frame member10C of cylindrical or rectangular shape with both ends open. Herein, the cross-section view ofFIG. 5is based on the premise that the frame member10C is rectangular in shape (the same applies to the following). No engagement portions are provided around inner circumferential edge parts of both end faces of the frame member10. The anode material50C has a small-diameter region50C′ made equal in outer diameter to an inner diameter of the frame member10C and a large-diameter region50C″ ranging in outer diameter between inner and outer diameters of the frame member10C.

The large-diameter region50C″ is interposed between the two adjacent air batteries A5and A5and, more specifically, between the lower end face10bof the frame member10C of the upper-side air battery A5and the upper end face10aof the frame member10C of the lower-side air battery A5for the formation of the air flow path.

The air battery A5also has a collector33A of the same type as the collector33. The collector33A is arranged at an interface between the small-diameter region50C′ and the large-diameter region50C″, that is, at a height position substantially flush with the lower end face10bof the frame member10C.

Further, the air battery A5has a fluid-tight air-preferable film31A of higher air permeability than the fluid-tight air-permeable film31. The fluid-tight air-permeable film31A is disposed on inlet and outlet of the air flow path. In the fifth embodiment, the fluid-tight air-preferable film31A has an inner diameter equal to an outer diameter of the fluid-tight air-preferable film31and an outer diameter equal to an outer diameter of the frame member10C.

In the above configuration, the fluid-tight air-preferable film31A serves as a fluid sealing member on the inlet and outlet of the air flow path. In a state where the anode material50C is brought into direct contact with the fluid-tight air-permeable film31with the use of no collector plate, there may occur leakage of the electrolyte due to dissolution and perforation of the anode material50C. Even in such a case, the fluid-tight air-preferable film31A prevents the electrolyte from leaking through the inlet and outlet of the air flow path. When the two air batteries A5and A5are stacked together as shown inFIG. 5, these upper and lower-side air batteries A5and A5are electrically conducted and connected in series to each other by intimate contact of the large-diameter region50C″ of the anode material50C of the upper-side air battery A5with the fluid-tight air-permeable film31of the lower-side air battery A5.

An air battery according to the sixth embodiment of the present invention will be explained below with reference toFIGS. 6A-6C.FIG. 6(A)is a plan view of an air battery according to the sixth embodiment of the present invention; andFIGS. 6(B) and 6(C)are cross-section views of the air battery taken along line I-I and line II-II ofFIG. 6(A), respectively. In the sixth embodiment, parts and portions that are the same as or similar to those in the above-mentioned embodiments are designated by the same or similar reference numerals to avoid repeated explanations thereof.

The air battery A6according to the sixth embodiment has a frame member60of rectangular frame shape when viewed in plan such that the cathode constituting member30, the electrolyte and separator layer40and the anode material50A are placed in the frame member60. The air battery A6also has a flow path forming member70and highly air-permeable seal members80and80

The flow path forming member70is arranged on the conductive fluid-tight air-permeable film31of the cathode constituting member30and has a plurality of ribs71formed at regular intervals and extending in parallel to the direction of air flow α. In the sixth embodiment, the flow path forming member70has conductivity. The highly air-permeable seal members80and80are disposed on air inlet- and outlet-side surfaces60band60cof the frame member60and, more specifically, in center portions of longitudinal-side upper end faces60aand60aof the frame member60so as to easily allow a flow of air.

The upper end faces60aand60aof the frame member60, on which the highly air-permeable seal members80and80are disposed, are made lower in height than the flow path forming member70. There is thus formed an air flow path between the upper- and lower-side air batteries A6and A6when the air batteries A6and A6are stacked together.

An air battery according to the seventh embodiment of the present invention will be explained below with reference toFIGS. 7A-7D.FIGS. 7(A) and 7(B)are a top view and a bottom view of an air battery according to the seventh embodiment of the present invention, respectively; andFIGS. 7(C) and 7(D)are cross-section views of the air battery taken along line III-III and line IV-IV ofFIG. 7(A), respectively. In the seventh embodiment, parts and portions that are the same as or similar to those in the above-mentioned embodiments are designated by the same or similar reference numerals to avoid repeated explanations thereof.

The air battery A7according to the seventh embodiment has an outer frame90of ring shape when viewed in plane, an air introduction tube91of smaller diameter than the outer frame90and a flow path forming member110. The outer frame90and the air introduction tube91are coaxially arranged about the axis O. The contact member20, the flow path forming member110, the cathode constituting member30, the electrolyte and separator layer40and the anode material50are stacked together and placed in an inner space between the outer frame90and the air introduction tube91.

Further, the air battery A7has a highly air-permeable seal member100located on an upper end face90aof the outer frame90. The highly air-permeable seal member100has a thick annular shape with a predetermined height and with inner and outer diameters equal to those of the outer frame90so as to surround the fluid-tight air-permeable film31. Air flow grooves101are made in the highly air-permeable seal member100at predetermined angular intervals about the axis O so as to provide air communication between the inside and outside of the outer frame90.

As shown inFIG. 7(C), an upper end face91aof the air introduction tube91is at the same height as the highly air-permeable seal member100. Air introduction grooves92are made in the upper end face91aof the air introduction tube91so as to extend along a diameter line across the axis O. Air introduction grooves94are also made in a lower end face91bof the air introduction tube91so as to extend along a diameter line across the axis O.

The flow path forming member110is arranged on the conductive fluid-tight air-permeable film31of the cathode constituting member30and has a plurality of ribs formed radially about the axis O so as to allow a smooth flow of air from the air introduction groove92to the air flow grooves101.

Although the embodiments of the present invention have been described in detail above, the features of the respective embodiments are not limited to the above applications. The feature or features of any one of the embodiments may be applied, with or without modification, to any other one of the embodiments. It is feasible to combine any of the features of the above embodiments.