JP5626872B2 - Hydrogen / air secondary battery - Google Patents

Description

  The present invention uses oxygen in the atmosphere as a positive electrode active material, hydrogen in a hydrogen storage alloy as a negative electrode active material, and an alkaline aqueous solution as an electrolytic solution. The present invention relates to an air secondary battery.

The air battery is a battery using air in the atmosphere as a positive electrode active material, and a commercially available zinc / air primary battery is well known. Among air batteries having a structure similar to that of a zinc / air primary battery, there are batteries using aluminum or iron as a negative electrode active material, all of which have been confirmed to function as primary batteries, but have not yet been put into practical use.
On the other hand, air batteries are not yet put into practical use as secondary batteries except for mechanically charged zinc / air secondary batteries. A mechanical rechargeable zinc / air secondary battery is one that only discharges as a reaction inside the battery, and can be reused by taking out the zinc negative electrode after discharge and replacing it with a new zinc negative electrode. . Therefore, unlike a generally known secondary battery, it cannot be used repeatedly by recharging by a reaction in the battery. An air battery using zinc, aluminum, iron, or the like as the negative electrode active material as described above usually uses an alkaline aqueous solution as an electrolytic solution.

On the other hand, as an air battery using an alkaline aqueous solution as an electrolyte, a battery using hydrogen as a negative electrode active material has been developed.
For example, the present inventors have disclosed an air secondary battery including an air electrode obtained by mixing nickel powder, a pyrochlore oxide containing iridium, and a binder, and a negative electrode using a hydrogen storage alloy (patent) Document 1) and (Non-Patent Document 1). Hereinafter, this secondary battery is referred to as a hydrogen / air secondary battery.

The charge / discharge reaction of the hydrogen / air secondary battery is expressed by the following equation.
Discharge: 4MH + O ₂ → 4M + 2H ₂ O
Charging: 4M + 2H ₂ O → 4MH + O ₂
In the formula, M is a hydrogen storage alloy, and MH means a hydrogen storage alloy in a state of storing hydrogen.
As shown in the above reaction formula, in the discharge, hydrogen is released from the hydrogen storage alloy at the negative electrode, and oxygen is reduced at the air electrode to produce water. At this time, water increases in the alkaline aqueous solution used for the electrolytic solution.
On the contrary, in charging, water in the alkaline aqueous solution is decomposed, hydrogen is occluded in the negative electrode, and oxygen is generated in the air electrode. The generated oxygen is released into the atmosphere through a gap in the air electrode.
That is, the hydrogen / air secondary battery is a secondary battery using only water as an active material, and is characterized in that the amount of water in the electrolytic solution changes depending on the amount of charge / discharge electricity. This is a battery reaction peculiar to hydrogen / air secondary batteries. Air batteries that use negative electrodes other than hydrogen storage alloys, all primary batteries other than air batteries, and secondary batteries that use only water as the active material Absent.
For example, (Patent Document 2) to (Patent Document 4) disclose air batteries, which use an organic solvent or an ionic liquid as an electrolytic solution, or use lithium as a negative electrode active material. It is not an air battery that uses water in the liquid as an active material of the battery, but, as will be described later, there is no problem relating to the change in the amount of water in the electrolyte, which is the point of the problem to be solved by the present invention.

JP 2006-196329 A JP 2010-103064 A JP 2010-103059 A JP 2009-289616 A

M.M. Morimitsu, T .; Kondo, N .; Osada, K .; Takano, Electrochemistry, Vol. 78, no. 5, pp. 493-496 (2010)

  The hydrogen / air secondary battery of Patent Document 1 has a simple configuration that can be charged and discharged with an air electrode, a negative electrode, and an alkaline aqueous solution, has a high energy density and a high output density, and has a large capacity by stacking. Is easy. However, the inventors of this patent have conducted various studies. As a result, in this battery, water in the electrolytic solution is reduced by charging, so that the amount of the electrolytic solution between the air electrode and the negative electrode is small, or a so-called battery separator. In the case where the electrolyte solution is held between the air electrode and the negative electrode using a so-called electrolyte solution holder, the charging voltage increases if the decrease in the electrolyte does not occur uniformly between the air electrode and the negative electrode. I found it. That is, when the decrease in the electrolyte is non-uniform, the reaction distribution on the negative electrode and / or air electrode becomes non-uniform due to the occurrence of a fast and slow part of water decomposition between the air electrode and the negative electrode, The charging voltage increases as the reaction resistance increases. It has also been found that such a phenomenon is remarkable particularly in a battery having a large electrode area. Furthermore, since the water in the electrolyte increases during discharge, if the increase in the electrolyte exceeds the amount that can be held in the space between the air electrode and the negative electrode or in the electrolyte holding body, the air electrode and the negative electrode It has been found that the discharge voltage is lowered due to distortion caused by an increase in time and an increase in electrolyte. It has also been found that such an effect is particularly significant when the battery capacity is increased, and that this leads to leakage of the electrolyte.

That is, the conventional hydrogen / air secondary battery has a problem that when charging / discharging is repeated, the discharge voltage decreases or the charging voltage increases, making subsequent charging / discharging difficult. Further, when the discharge current is increased, the discharge capacity becomes extremely small, and when the charge current is increased, there is a problem that the charge voltage becomes high and the charge cannot be continued at a stage before full charge. Furthermore, there has been a problem that when the discharge is performed at a very high current, the electrolyte leaks through the air electrode. In particular, when the electrode area is increased or the battery capacity is increased, there is a problem that the charge / discharge characteristics are deteriorated.
Therefore, in order to improve the charge / discharge cycle characteristics, rechargeability, and durability of the hydrogen / air secondary battery, a structure capable of controlling the amount of electrolyte that increases during charging and the amount of electrolyte that decreases during discharging is desired. It was.

  The present invention solves the above-mentioned problems, suppresses a large change in voltage during charging and discharging, has excellent charge / discharge cycle characteristics, does not leak electrolyte, has excellent rechargeability and durability, and is particularly negative electrode Even when the electrode area of the air electrode and the battery capacity are large, or even when the discharge current or charging current is large, the operation stability, high quality, and long life can be achieved. The object is to provide an excellent hydrogen / air secondary battery.

In order to solve the above conventional problems, the hydrogen / air secondary battery of the present invention has the following configuration. An air electrode disposed in the battery container, a negative electrode using a hydrogen storage alloy disposed in the battery container opposite to the air electrode, and disposed between the air electrode and the negative electrode. An electrolyte storage unit that holds an electrolyte solution, and is a hydrogen / air secondary battery that includes an electrolyte solution storage unit that supplies an electrolyte solution that decreases due to a charge reaction or stores an electrolyte solution that increases due to a discharge reaction The battery container is formed separately from the air electrode and the negative electrode, and at least a part of the electrolyte solution holder is immersed in the electrolyte solution in the electrolyte solution storage unit, so that supply and storage of the electrolyte solution can be performed. The structure is performed between the air electrode and the negative electrode and between the electrolytic solution storage unit via the electrolytic solution holder .
With this configuration, the following effects can be obtained.
(1) An electrolytic solution storage unit that supplies an electrolytic solution that decreases due to a charging reaction or stores an electrolytic solution that increases due to a discharging reaction is formed in the battery container separately from the air electrode and the negative electrode. Discharge between the air electrode and the negative electrode via the electrolytic solution holder due to a pressure increase caused by water generated between the air electrode and the negative electrode during discharge due to a part being immersed in the electrolyte solution in the electrolyte storage unit. It is possible to store the increased amount of the electrolyte in the electrolyte storage part, and from the electrolyte storage part to the electrolyte holder using the pressure drop due to water that decreases between the air electrode and the negative electrode during charging It becomes possible to supply the electrolyte solution reduced by charging through the air gap between the air electrode and the negative electrode.
(2) Moreover, the amount of the electrolyte solution held by the electrolyte solution holding body can always be kept constant between the air electrode and the negative electrode.
(3) Further, since the supply and storage of the electrolyte as described above are performed between the air electrode and the negative electrode and between the electrolyte solution storage unit via the electrolyte solution holder, the electrolyte solution from the air electrode Leakage can be suppressed.
(4) Further, since the supply and storage of the electrolyte as described above is performed between the air electrode and the negative electrode and between the electrolyte solution storage unit via the electrolyte solution holding body, it exists between the air electrode and the negative electrode. The amount of electrolytic solution to be adjusted can be adjusted by changing the porosity of the electrolytic solution holder, and the necessary and optimal amount of electrolytic solution can always be held between the air electrode and the negative electrode.
(5) Further, since the supply and storage of the electrolyte as described above are performed between the air electrode and the negative electrode and the electrolyte solution storage unit via the electrolyte solution holding body, it exists between the air electrode and the negative electrode. The amount of electrolyte to be adjusted can be adjusted by changing the porosity and thickness of the electrolyte holder, and the required optimum amount of electrolyte is always maintained between the air electrode and the negative electrode regardless of the charge / discharge capacity of the battery. can do.

  Here, at least one pair of an air electrode and a negative electrode are disposed in the battery container. In the battery container, the air electrode and the negative electrode may be disposed horizontally or vertically. In the battery container, an electrolytic solution holder that holds an electrolytic solution that is an alkaline aqueous solution is disposed between the air electrode and the negative electrode. On the opposite side of the air electrode from the electrolyte holder, there is an air passage formed in the battery container so that oxygen necessary for discharging can be taken into the air electrode or oxygen generated by charging can be dissipated from the air electrode. is there. This vent path may simply be an opening formed in the battery container. Further, the battery container is provided with an electrolytic solution storage part, and a part of the electrolytic solution holding body is immersed in the electrolytic solution in the electrolytic solution storage part. The electrolytic solution storage section has a volume suitable for the charge / discharge capacity of the battery so that the electrolytic solution that decreases by the charging reaction can be supplied or the electrolytic solution that increases by the discharging reaction can be stored. Furthermore, the flow of the electrolytic solution is ensured between the electrolytic solution storage unit and the electrolytic solution holding body, and this increases the electrolytic solution by water generated between the air electrode and the negative electrode during discharge. The electrolyte is stored in the electrolyte storage unit via the liquid holder, and the electrolyte is reduced by the decomposition of water between the air electrode and the negative electrode during charging. To be replenished between the air electrode and the negative electrode.

  The air electrode is configured based on a conductive material that imparts conductivity to the air electrode, a catalyst, and a binder. These are integrally formed in a mixed state, and are further formed integrally with a current collector for outputting electric power to the outside during discharging and facilitating input of electric power from an external power source during charging. Carbon, metal, or the like can be used as the conductive material, but those that are stable against oxygen reduction and oxygen generation in an alkaline aqueous solution are preferable. Examples of the carbon material include graphite, glassy carbon, fullerene, carbon nanotube, carbon having other structures, and graphite having excellent oxidation resistance that is heat-treated at high temperature is particularly preferable. Furthermore, nickel is more preferable as the conductive substance than the carbon material. Such conductive substances can be used in various shapes such as particles, powders, fibers, tubes, and porous bodies.

A catalyst having activity for oxygen reduction and oxygen generation is used. For example, precious metals such as platinum and silver, metal oxides, metal sulfides, metal nitrides, metal carbides, metal oxides, metal sulfides, metal carbides, metal carbide oxides, etc. with nitrogen substitution, Metal, oxygen, nitrogen, and carbon composite oxide (MeC _x N _y O _z : Me is a metal or alloy, C is carbon, N is nitrogen, O is oxygen, and x, y, and z indicate the composition ratio. ) And other oxygen reduction catalysts that have catalytic activity for oxygen reduction, and oxide activity such as iridium oxide and ruthenium oxide, metal sulfides, and metal composite oxides. The oxygen generation catalyst having the same can be used together to impart oxygen reduction activity and oxygen generation activity to the air electrode. In addition, a bifunctional metal, alloy, or compound having both oxygen reduction activity and oxygen generation activity can be used. Examples of such dual functional materials include complex oxides classified into pyrochlore type, perovskite type, spinel type, and the like.

  The binder has water repellency with respect to the electrolyte so that an air flow path can be formed inside the air electrode, and allows the air to flow through the gap while binding the conductive substances to each other. Resin-based materials such as polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), and ethylene / vinyl acetate copolymer (EVA) can be used. In addition, when the conductive material, the catalyst, and the binder are mixed and formed integrally, a dispersion solution in which such a binder is dispersed in an appropriate solution may be used as a starting material. it can.

  The current collector can be a metal, conductive organic material, etc. in various shapes such as a net, a fiber, or a porous body, but the shape needs to have an opening for taking in oxygen in the atmosphere. is there. The material for the current collector is preferably nickel. Note that the materials, structures, and shapes used for the conductive material, catalyst, binder, and current collector are particularly limited to those listed above as long as they exhibit their respective functions as described above. It is not something.

  As a method of integrating the conductive substance, the catalyst, and the binder, a method generally used for producing an air electrode such as a press method or an extrusion method can be used. For example, if the conductive substance, the catalyst, and the binder are in the form of powder or particles, they can be produced by mixing them in a dry or wet manner and then forming them into a thin plate using a roll press. Moreover, it can be produced by putting a mixture in a specific mold and molding it. Further, when the conductive material is a porous body such as nickel foam, the catalyst and the binder can be introduced into the porous body, and then the entire conductive material can be pressurized to be integrally molded. . Further, the current collector may be integrated with the air electrode as described above, or may be further integrated with the current collector after the conductive material, the catalyst, and the binder are integrally formed. Furthermore, when producing an air electrode, you may heat-process after the process of the above shaping | molding or integration.

  About the hydrogen storage alloy used for a negative electrode, La-Ni system alloy, La-Nd-Ni system alloy, La-Gd-Ni system alloy, La-Y-Ni system alloy, La-Co-Ni system alloy, La-Ce -Ni alloy, La-Ni-Ag alloy, La-Ni-Fe alloy, La-Ni-Cr alloy, La-Ni-Pd alloy, La-Ni-Cu alloy, La-Ni-Al Alloy, La-Ni-Mn alloy, La-Ni-In alloy, La-Ni-Sn alloy, La-Ni-Ga alloy, La-Ni-Si alloy, La-Ni-Ge alloy La-Ni-Al-Co alloy, La-Ni-Al-Mn alloy, La-Ni-Al-Cr alloy, La-Ni-Al-Cu alloy, La-Ni-Al-Si alloy La-Ni-Al-Ti alloy, La-Ni-Al-Zr alloy La-Ni-Mn-Zr alloy, La-Ni-Mn-Ti alloy, La-Ni-Mn-V alloy, La-Ni-Cr-Mn alloy, La-Ni-Cr-Zr alloy , La—Ni—Fe—Zr alloys, La—Ni—Cu—Zr alloys, alloys in which the La element in the above alloys is replaced with misch metal, Ti—Zr—Mn—Mo alloys, Zr -Fe-Mn alloys, Mg-Ni alloys, etc., alloys composed of combinations of two or more of Ti, Fe, Mn, Al, Ce, Ca, Mg, Zr, Nb, V, Co, Ni, Cr elements, etc. Hydrogen-absorbing alloys, metals that form hydrides such as Ti, V, Zr, La, Pd, and Pt (having hydrogen-absorbing properties), or alloys and metal hydrides (substances that store hydrogen) Can be used, but hydrogen storage and release If capacity material, is not particularly limited to the above composition.

Batteries using an alkaline aqueous solution as the electrolytic solution holder, such as zinc / air primary batteries, nickel / hydrogen secondary batteries, alkaline batteries, alkaline manganese batteries, nickel / cadmium batteries, etc. A separator material or the like can be used. Such materials include, for example, JP-A-7-272771, JP-A-11-293564, JP-A-2007-154402, JP-A-2007-284845, JP-A-2009-224100, and special publication. This is disclosed in Japanese Patent Application Laid-Open No. 2009-516781 and Japanese Patent Application Laid-Open No. 2010-70870. Specific examples include ion permeable films such as cellophane, films such as polypropylene and polyethylene, polyvinyl alcohol fibers, cellulose fibers, polyamide fibers, polyolefin fibers, and ethylene-vinyl alcohol copolymer fibers. A composite film in which an inorganic compound such as TiO ₂ , K ₂ Ti ₆ O ₁₃ , ZrO ₂ , Al ₂ O ₃ , SiO ₂ or BN is filled in a porous resin sheet, Etc. Further, for these materials, ultrafine fibers, core-sheath type composite fibers, those subjected to hydrophilic treatment, and the like are also used. The electrolytic solution holding body only needs to have a function of isolating the air electrode and the negative electrode and holding the electrolytic solution. Therefore, the electrolytic solution holding body has ion conductivity or ion permeability while holding the electrolytic solution, and has alkali resistance and electrolysis. The liquid is not particularly limited as long as it has liquid absorption.
In the hydrogen / air secondary battery according to the present invention, a metal or alloy other than a hydrogen storage alloy is used for the negative electrode. Since a short circuit does not occur, so-called separation property, which is a function intended for this, is not necessarily required for the electrolyte solution holder of the hydrogen / air secondary battery of the present invention.

The invention according to claim 2 is the hydrogen / air secondary battery according to claim 1, wherein the air electrode contains nickel, a pyrochlore oxide containing iridium, and a binder. It has the composition which becomes.
With this configuration, in addition to the operation obtained in the first aspect, the following operation can be obtained.
(1) High catalytic ability for oxygen generation and oxygen reduction is obtained by electronic and chemical interaction between the pyrochlore oxide containing iridium and nickel. Can also proceed smoothly.
(2) The combination of the pyrochlore oxide containing iridium and nickel suppresses the oxidation and reduction of nickel that may occur as a side reaction at the air electrode, thereby reducing nickel consumption and carbon powder. As compared with an air electrode using a metal electrode and an air electrode having a configuration in which nickel and another metal-based and / or oxide-based catalyst are mixed, durability against oxygen generation / reduction cycle can be improved.
(3) The pyrochlore-type oxide containing iridium and nickel can be easily mixed and molded with a binder by either wet or dry methods, and an air electrode can be produced without using a special device.
(4) Since expensive noble metals such as platinum are not used for the catalyst, the cost of the air electrode can be reduced.

Here, the pyrochlore type oxide containing iridium is a B site in A ₂ B ₂ O _7-x (where −1 ≦ x ≦ 1), which is a general expression representing the molar composition of the pyrochlore type oxide. Is an oxide in which the element is iridium, and examples of the A site element include bismuth and lead. However, as a matter of course, a part of iridium at the B site is partially substituted with another element.
Pyrochlore oxide containing iridium is supported on nickel and / or in contact with nickel against both alkaline aqueous solution and air, and is a high catalyst for both oxygen reduction and oxygen generation Has activity.

A third aspect of the present invention is the hydrogen / air secondary battery according to the second aspect, wherein the pyrochlore oxide containing the iridium is a bismuth iridium oxide.
With this configuration, in addition to the operation obtained in the second aspect, the following operation can be obtained.
(1) Among bismuth iridium oxides, among pyrochlore-type oxides containing iridium, particularly in combination with nickel, the catalytic activity is high with respect to oxygen generation at the time of charging in the air electrode and oxygen reduction at the time of discharge. High durability against charge / discharge cycles even at current density and high temperature operation.
(2) Since other pyrochlore type oxides such as lead iridium oxide do not contain toxic components such as lead, the safety of the battery in manufacturing, use, disposal, and disposal increases.
(3) Bismuth iridium oxide is a simple process in which a bismuth compound such as bismuth nitrate and an iridium compound such as chloroiridic acid are used as starting materials, and a precursor material is synthesized by a method called a coprecipitation method, followed by heat treatment. Therefore, a highly active catalyst constituting the air electrode can be easily obtained.

Here, the bismuth iridium oxide is an oxide represented by Bi ₂ Ir ₂ O _7-x in the composition formula of the pyrochlore oxide shown above. However, as a matter of course, those in which bismuth at the A site and / or iridium at the B site are partially substituted with other elements are also included.

A fourth aspect of the present invention is the hydrogen / air secondary battery according to any one of the first to third aspects, wherein the two air electrodes are disposed so as to face the negative electrode. The electrolyte solution holding body is configured to be disposed between the negative electrode and each air electrode.
With this configuration, in addition to the action obtained in any one of claims 1 to 3, the following action is obtained.
(1) By disposing two air electrodes opposite to the negative electrode, both sides of the negative electrode can be used for the battery reaction, and charging and discharging at a higher current as a single cell is possible. The polarization of the discharge voltage can be reduced.
(2) The dead space inside the battery can be reduced as compared with the case where one air electrode is disposed facing the negative electrode.

A fifth aspect of the present invention is the hydrogen / air secondary battery according to the fourth aspect, wherein at least a part of the plurality of electrolytic solution holders is immersed in the electrolytic solution in the common electrolytic solution storage unit. It has the composition which has.
With this configuration, in addition to the operation obtained in the fourth aspect, the following operation can be obtained.
(1) Since at least some of the plurality of electrolytic solution holders are immersed in the electrolytic solution in the common electrolytic solution storage unit, the structure of the electrolytic solution storage unit in the battery container can be simplified (2 ) Compared to the case where the electrolyte storage part is not common and is arranged for each electrolyte holder, the volume of the electrolyte storage part can be reduced, and the volume of the entire battery container is also reduced. The hit energy density and output density can be improved.

A sixth aspect of the present invention is the hydrogen / air secondary battery according to the fifth aspect, wherein a plurality of the electrolytic solution holders are connected in the common electrolytic solution storage unit. Yes.
With this configuration, in addition to the operation obtained in the fifth aspect, the following operation can be obtained.
(1) Since a plurality of electrolyte holders are connected in a common electrolyte storage part, the plurality of electrolyte holders are integrated with each other with respect to two or more air electrodes via the electrolyte storage part. The number of members of the electrolytic solution holder can be reduced.
(2) It is possible to keep the amount of electrolyte in the electrolyte holder between the air electrode and the negative electrode uniform between the plurality of air electrodes and the negative electrode, and between each air electrode and the negative electrode. It is possible to prevent the balance of the amount of the existing electrolyte from being lost, and to prevent the interelectrode voltage between each air electrode and the negative electrode from being different.

A seventh aspect of the present invention is the hydrogen / air secondary battery according to any one of the first to sixth aspects, wherein the negative electrode and one or two of the air electrodes facing the negative electrode are provided. A plurality of pairs of electrodes whose longitudinal directions are arranged in parallel with the horizontal direction are stacked in the battery container.
With this configuration, in addition to the action obtained in any one of claims 1 to 6, the following action is obtained.
(1) The maximum as a single cell is obtained by laminating a plurality of electrode pairs in which the longitudinal direction of one or two air electrodes facing the negative electrode and the negative electrode is arranged in parallel with the horizontal direction in the battery container The dischargeable current, power density, and energy density can be improved.
(2) Since a plurality of electrode pairs are stacked in a single container, the volume occupied by the entire battery can be reduced as compared with the case where a plurality of batteries each made up of a single electrode pair are connected.

The invention according to claim 8 is the hydrogen / air secondary battery according to any one of claims 1 to 6, wherein the negative electrode and one or two of the air electrodes facing the negative electrode are provided. A plurality of pairs of electrodes whose longitudinal directions are arranged in parallel with the vertical direction are arranged in parallel in the battery container.
With this configuration, in addition to the action obtained in any one of claims 1 to 6, the following action is obtained.
(1) A plurality of electrode pairs, in which the longitudinal direction of one or two air electrodes facing the negative electrode and the negative electrode is arranged in parallel with the vertical direction, are arranged in parallel in the battery container. Maximum dischargeable current, power density, and energy density can be improved.
(2) Since a plurality of electrode pairs are arranged in parallel in a single container, the volume occupied by the whole battery can be reduced as compared with the case where a plurality of batteries each made up of a single electrode pair are connected.
(3) By arranging the air electrode and the negative electrode vertically, the pressure increases due to water generated between the air electrode and the negative electrode by discharge, and the pressure decrease due to water that decreases between the air electrode and the negative electrode due to charging, and gravity. By adding the interaction between sedimentation and capillary action, the electrolyte holder between the air electrode and the negative electrode from the electrolyte storage part corresponds to the decrease / increase in water between the air electrode and the negative electrode during charge / discharge. In addition, the electrolyte can be supplied at a more appropriate timing, or the electrolyte can be stored at a more appropriate timing from the electrolyte holder between the air electrode and the negative electrode to the electrolyte reservoir.

As described above, according to the hydrogen / air secondary battery of the present invention, the following advantageous effects can be obtained.
According to the first aspect of the invention, the following advantageous effects can be obtained.
(1) Since the increase or decrease in the amount of the electrolyte between the air electrode and the negative electrode can be adjusted by the electrolyte holder and the electrolyte storage unit, the amount of the electrolyte between the air electrode and the negative electrode can always be kept constant. , Leakage of electrolyte from the battery container due to increase in the amount of electrolyte between the air electrode and negative electrode due to discharge, increase in battery resistance due to increase in the amount of electrolyte, and reaction distribution on the electrode due to increase in the amount of electrolyte It is possible to suppress an increase in electrode reaction resistance due to non-uniformization and a decrease in utilization rate during discharge of hydrogen stored in the hydrogen storage alloy of the negative electrode.
(2) In addition to the effects of (1), the battery resistance is increased by increasing the electrode reaction resistance of the negative electrode and the air electrode due to the decrease in the amount of the electrolyte between the air electrode and the negative electrode during charging, and the non-uniform reaction distribution on the electrode And a decrease in the amount of hydrogen stored in the hydrogen storage alloy of the negative electrode can be suppressed.
(3) Along with the effects of (1) and (2), it is possible to increase the discharge capacity and charge capacity of the battery, improve the utilization rate of the hydrogen storage alloy, and reduce the total battery resistance. The density can be improved.
(4) Furthermore, in accordance with the effects (1) and (2), the leakage of the electrolyte and the heat generation associated with the battery reaction are suppressed, and the safety of the battery can be improved.
(5) Furthermore, with the effects (1) and (2), the charge / discharge cycle characteristics of the battery are improved, and the battery life can be extended.
(6) Furthermore, since the necessary and optimum amount of electrolyte can be held between the air electrode and the negative electrode, and the necessary and optimum amount of electrolyte can be held regardless of the charge / discharge capacity of the battery, The effects described above can be exhibited for various battery capacities and battery sizes.

According to the invention described in claim 2, in addition to the effect described in claim 1, the following advantageous effects can be obtained.
(1) Since high catalytic properties for oxygen generation and oxygen reduction are obtained, and both oxygen generation and oxygen reduction inside the air electrode can proceed smoothly, it contains nickel as a conductive substance and iridium as a catalyst. The resistance of the air electrode during charging and discharging can be reduced as compared to the case where a pyrochlore type oxide is used.
(2) Along with the effect of (1), the resistance of the air electrode can be reduced, whereby the battery resistance is reduced, and the voltage efficiency and energy efficiency of the battery can be improved.
(3) Compared to the case where a substance other than nickel is used as the conductive substance or the case where a substance other than the pyrochlore oxide containing iridium is used as the catalyst, the consumption of the conductive substance itself due to oxidation and reduction can be suppressed. .
(4) Compared to the case where a substance other than nickel is used as the conductive substance, or the case where a substance other than the pyrochlore oxide containing iridium is used as the catalyst, the consumption of the catalyst itself due to oxidation and reduction can be suppressed.
(5) In addition to the effects of (3) and (4), the durability of the air electrode is improved, and the life of the battery can be extended.

According to the invention described in claim 3, in addition to the effect described in claim 2, the following advantageous effects can be obtained.
(1) Among pyrochlore oxides containing iridium, bismuth iridium oxide has particularly high catalytic activity for oxygen generation and oxygen reduction, and has a high air electrode for charge / discharge cycles even at high current density and high temperature operation. Since it has durability, it becomes possible to improve the maximum current that can be charged and discharged of the battery, and it is possible to widen the operating temperature range.
(2) Along with the effect of (1), the maximum current that can be charged / discharged by the battery is improved, so that the maximum output of the battery can be further increased.
(3) In addition to the effects of (1) and (2), it is possible to provide a battery having excellent durability even when operated at a high current and a high temperature.
(4) Since bismuth iridium oxide does not contain harmful substances such as lead iridium oxide, it is safer to manufacture, use, dispose of, and dispose of batteries. A secondary battery with high safety and recyclability in a life cycle can be provided in a power source for a mobile body, a power source for an electric vehicle / hybrid vehicle, a power source for an electric motorcycle, and the like.
(5) In addition to the effects of (4), a secondary battery with high safety can be provided even when used as a power source for devices used near the human body, such as a power source for hearing aids or a power source for mobile devices.

According to the invention described in claim 4, in addition to the effect described in any one of claims 1 to 3, the following advantageous effects can be obtained.
(1) As a single cell, charging / discharging at a higher current is possible, and the polarization during charging / discharging can be reduced, so that the maximum current that can be charged / discharged is improved, and the energy density and output density of the battery are increased. Can be high.
(2) In addition to the effects of (1), the dead space inside the battery can be reduced compared to the case where one air electrode is disposed opposite to the negative electrode, so that the energy density and output density of the battery can be further increased. Can be improved.

According to the invention described in claim 5, in addition to the effect described in claim 4, the following advantageous effect can be obtained.
(1) Since the structure of the electrolyte storage part in the battery container can be simplified and the volume thereof can be reduced, the overall volume of the battery is also reduced, and the energy density and output density per volume are high, so that it can be mounted at a high density. And high output performance.

According to the invention described in claim 6, in addition to the effect described in claim 5, the following advantageous effect is obtained.
(1) The number of members of the electrolytic solution holder is small, and the amount of electrolytic solution in the electrolytic solution holder can be kept uniform with respect to the space between the plurality of air electrodes and the negative electrode. It is possible to prevent the balance of the amount of the existing electrolyte from being lost, to suppress the difference in the voltage between the electrodes, and to achieve excellent output uniformity and stability.

According to the invention described in claim 7, in addition to the effect described in any one of claims 1 to 6, the following advantageous effects can be obtained.
(1) By arranging a plurality of air electrodes and negative electrodes and securing a large electrode area and battery capacity, the output characteristics and energy density as a unit cell can be improved, and rechargeability and durability are excellent.

According to the invention described in claim 8, in addition to the effect described in any one of claims 1 to 6, the following advantageous effects can be obtained.
(1) By arranging a plurality of air electrodes and negative electrodes and securing a large electrode area and battery capacity, output characteristics as a unit cell can be improved, and rechargeability and durability are excellent.
(2) Corresponding to the decrease / increase of water between the air electrode and the negative electrode during charging / discharging, supply or store the electrolyte at a more appropriate timing between the electrolyte holder and the electrolyte reservoir. Thus, the amount of the electrolytic solution held in the electrolytic solution holding body can always be kept constant, and stable charging / discharging can be performed, and the operational stability, high quality, and long life are excellent.

FIG. 2 is a schematic cross-sectional view of the main part of the hydrogen / air secondary battery according to Embodiment 1 of the present invention. Cross-sectional schematic diagram of relevant parts of a modification of the hydrogen / air secondary battery of Embodiment 1 of the present invention Sectional schematic diagram of relevant parts of the hydrogen / air secondary battery of Embodiment 2 of the present invention Sectional schematic diagram of relevant parts of a modification of the hydrogen / air secondary battery of Embodiment 2 of the present invention Cross-sectional schematic diagram of relevant parts of a hydrogen / air secondary battery according to Embodiment 3 of the present invention Sectional schematic diagram of relevant parts of a hydrogen / air secondary battery according to Embodiment 4 of the present invention Sectional schematic diagram of relevant parts of a hydrogen / air secondary battery according to Embodiment 5 of the present invention Sectional schematic diagram of relevant parts of a hydrogen / air secondary battery according to Embodiment 6 of the present invention The figure which shows the cycle dependence of the charge / discharge voltage of a hydrogen / air secondary battery The figure which shows the discharge curve of a hydrogen / air secondary battery

Hereinafter, a hydrogen / air secondary battery according to an embodiment of the present invention will be described with reference to the drawings.
(Embodiment 1)
FIG. 1 is a schematic cross-sectional view of the relevant part of a hydrogen / air secondary battery according to Embodiment 1 of the present invention.
In FIG. 1, 1 is a hydrogen / air secondary battery according to Embodiment 1 of the present invention, 1a is a battery container of the hydrogen / air secondary battery 1, and 2 is bismuth iridium, which is a pyrochlore oxide containing nickel and iridium. The air electrode 3 formed by mixing the oxide and the binder and horizontally disposed in the battery container 1 a is disposed horizontally in the battery container 1 a so as to face the air electrode 2. Negative electrode 4 using hydrogen storage alloy, 4 is disposed between air electrode 2 and negative electrode 3, and is an electrolytic solution holder that holds an electrolytic solution that is an alkaline aqueous solution, and 5 is opposite to electrolytic solution holder 4 of air electrode 2. On the side of this, an air passage formed in the battery case 1a so that oxygen necessary for discharge can be taken into or discharged from the air electrode 2 is formed in the battery case 1a. An electrolyte storage part formed at one end in the longitudinal direction of the electrolyte holder 4 Part is immersed in the electrolyte in the electrolytic solution reservoir 6, between the electrolyte storage unit 6 and the electrolytic solution holding body 4 to flow of the electrolyte is ensured.

The electrolyte is increased by the water generated between the air electrode 2 and the negative electrode 3 at the time of discharge, but this is stored in the electrolyte storage unit 6 via the electrolyte holder 4, and the air is charged at the time of charging. The electrolytic solution decreases due to the decomposition of water between the electrode 2 and the negative electrode 3, but this is replenished from the electrolytic solution storage unit 6 through the electrolytic solution holder 4. As a result, between the air electrode 2 and the negative electrode 3, the amount of the electrolyte solution held in the electrolyte solution holder 4 is always kept constant.
The electrolytic solution storage unit 6 supplies sufficient electrolytic solution to the electrolytic solution holder 4 in which the electrolytic solution decreases due to the charging reaction, and can reliably store the electrolytic solution that increases in the electrolytic solution holder 4 due to the discharge reaction. Furthermore, the volume is suitable for the charge / discharge capacity of the battery.
The ventilation path 5 may simply be an opening formed in the battery container 1.

Next, a modification of the hydrogen / air secondary battery according to Embodiment 1 of the present invention will be described. In addition, about the thing similar to Embodiment 1, the same code | symbol is attached | subjected and description is abbreviate | omitted.
FIG. 2 is a schematic cross-sectional view of an essential part of a modification of the hydrogen / air secondary battery according to Embodiment 1 of the present invention.
In FIG. 2, the hydrogen / air secondary battery 1A in the modification of the first embodiment is different from that of the first embodiment in that the two ends of the electrolytic solution holder 4 are immersed in the electrolytic solution in the battery container 1a. One electrolyte storage part 6 is formed.
Thus, an electrolyte holding body is used at the time of discharge by utilizing a pressure increase caused by water generated between the air electrode 2 and the negative electrode 3 due to discharge and a pressure drop caused by water decreasing between the air electrode 2 and the negative electrode 3 due to charging. 4 can be stored in the electrolyte storage units 6 at both ends, and the amount of electrolyte decreased by the electrolyte holder 4 can be supplied from the electrolyte storage units 6 at both ends during charging. Can do. As a result, between the air electrode 2 and the negative electrode 3, the amount of the electrolyte solution held in the electrolyte solution holder 4 is always kept constant.

The hydrogen / air secondary battery according to Embodiment 1 configured as described above has the following effects.
(1) The battery container has an electrolyte solution storage unit that supplies an electrolyte solution that decreases due to a charging reaction or stores an electrolyte solution that increases due to a discharge reaction, and at least a part of the electrolyte solution holder is in the electrolyte solution storage unit. By immersing in the electrolyte, the amount of electrolyte increased by the discharge between the air electrode and the negative electrode via the electrolyte holder is increased by the pressure increase caused by the water generated between the air electrode and the negative electrode during discharge. It is possible to store in the electrolyte storage unit, and the amount of decrease due to charging from the electrolyte storage unit through the electrolyte holder using the pressure drop due to water that decreases between the air electrode and the negative electrode during charging. This electrolyte solution can be supplied between the air electrode and the negative electrode.
(2) Moreover, the amount of the electrolyte solution held by the electrolyte solution holding body can always be kept constant between the air electrode and the negative electrode.
(3) Further, since the supply and storage of the electrolyte as described above are performed between the air electrode and the negative electrode and between the electrolyte solution storage unit via the electrolyte solution holder, the electrolyte solution from the air electrode Leakage can be suppressed.
(4) Further, since the supply and storage of the electrolyte as described above is performed between the air electrode and the negative electrode and between the electrolyte solution storage unit via the electrolyte solution holding body, it exists between the air electrode and the negative electrode. The amount of electrolytic solution to be adjusted can be adjusted by changing the porosity of the electrolytic solution holder, and the necessary and optimal amount of electrolytic solution can always be held between the air electrode and the negative electrode.
(5) Further, since the supply and storage of the electrolyte as described above are performed between the air electrode and the negative electrode and the electrolyte solution storage unit via the electrolyte solution holding body, it exists between the air electrode and the negative electrode. The amount of electrolyte to be adjusted can be adjusted by changing the porosity and thickness of the electrolyte holder, and the required optimum amount of electrolyte is always maintained between the air electrode and the negative electrode regardless of the charge / discharge capacity of the battery. can do.
(6) A high catalytic ability for oxygen generation and oxygen reduction is obtained by electronic and chemical interaction between the pyrochlore oxide containing iridium and nickel. Can also proceed smoothly.
(7) The combination of iridium-containing pyrochlore oxide and nickel suppresses the oxidation and reduction of nickel that may occur as a side reaction at the air electrode, thereby reducing nickel consumption and carbon powder. As compared with an air electrode using a metal electrode and an air electrode having a configuration in which nickel and another metal-based and / or oxide-based catalyst are mixed, durability against oxygen generation / reduction cycle can be improved.
(8) Pyrochlore oxide containing iridium and nickel can be easily mixed and molded with a binder by either wet or dry methods, and an air electrode can be produced without using a special device. it can.
(9) Since expensive noble metals such as platinum are not used for the catalyst, the cost of the air electrode can be reduced.
(10) The bismuth iridium oxide forming the air electrode is a catalytic activity for oxygen generation during charging and oxygen reduction during discharge in the air electrode, particularly in combination with nickel among pyrochlore oxides containing iridium. And high durability against charge / discharge cycles even at high current density and high temperature operation.
(11) Compared with other pyrochlore type oxides such as lead iridium oxide, since it does not contain toxic components such as lead, the safety of manufacturing, using, disposing and disposing of the battery is increased.
(12) Bismuth iridium oxide is a simple process in which a bismuth compound such as bismuth nitrate and an iridium compound such as chloroiridic acid are used as starting materials, a precursor material is synthesized by a method called a coprecipitation method, and then heat treatment is performed. Therefore, a highly active catalyst constituting the air electrode can be easily obtained.

(Embodiment 2)
A hydrogen / air secondary battery according to Embodiment 2 will be described. In addition, about the thing similar to Embodiment 1, the same code | symbol is attached | subjected and description is abbreviate | omitted.
FIG. 3 is a schematic cross-sectional view of the main part of the hydrogen / air secondary battery according to Embodiment 2 of the present invention, and FIG. 4 is a cross-sectional view of the main part of a modification of the hydrogen / air secondary battery according to Embodiment 2 of the present invention. It is a schematic diagram.
In FIG. 3, the hydrogen / air secondary battery 1B of the second embodiment is different from that of the first embodiment in that the air electrode 2, the negative electrode 3, and the electrolyte holding body 4 are arranged in the vertical direction. In FIG. 3, the electrolyte solution storage part 6 is arrange | positioned under these. Although not shown in the figure, Embodiment 2 also includes an arrangement in which the electrolyte storage unit 6 is turned upside down in FIG.
Also, in FIG. 4, the hydrogen / air secondary battery 1C according to the modification of the second embodiment is different from the second embodiment in that both ends of the electrolytic solution holder 4 are immersed in the electrolytic solution in the battery container 1a. In other words, two electrolyte storage parts 6 are formed, which corresponds to a vertical arrangement of the hydrogen / air secondary battery 1A in the modification of the first embodiment.

According to the hydrogen / air secondary battery in the second embodiment configured as described above, in addition to the functions in the first embodiment, the following functions are provided.
(1) By arranging the air electrode and the negative electrode vertically, the pressure increases due to the water generated between the air electrode and the negative electrode due to discharge, and the pressure decrease due to the water that decreases between the air electrode and the negative electrode due to charging, the gravity By adding the interaction between sedimentation and capillary action, the electrolyte holder between the air electrode and the negative electrode from the electrolyte storage part corresponds to the decrease / increase in water between the air electrode and the negative electrode during charge / discharge. In addition, the electrolyte can be supplied at a more appropriate timing, or the electrolyte can be stored at a more appropriate timing from the electrolyte holder between the air electrode and the negative electrode to the electrolyte reservoir.

(Embodiment 3)
A hydrogen / air secondary battery according to Embodiment 3 will be described. In addition, about the thing similar to Embodiment 1 or 2, the same code | symbol is attached | subjected and description is abbreviate | omitted.
FIG. 5 is a schematic cross-sectional view of the relevant part of a hydrogen / air secondary battery according to Embodiment 3 of the present invention.
In FIG. 5, the hydrogen / air secondary battery 1D of the third embodiment is different from the modification of the second embodiment in that two air electrodes 2 are arranged opposite to both sides of the negative electrode 3 to hold the electrolyte solution. The body 4 is disposed between the negative electrode 3 and each air electrode 2. In addition, the structure of FIG. 5 can be set as one set, and a plurality of sets can be arranged in parallel in one battery container 1a. At this time, the air passage 5 can be shared between the adjacent air electrodes 2.
In the present embodiment, the negative electrode 3, the air electrode 2, and the electrolytic solution holding body 4 are arranged in the vertical direction in the battery container 1a. However, the structure may be arranged in the horizontal direction as in the first embodiment.

According to the hydrogen / air secondary battery in the third embodiment configured as described above, in addition to the functions in the second embodiment, the following functions are provided.
(1) By disposing two air electrodes opposite to the negative electrode, both sides of the negative electrode can be used for the battery reaction, and charging and discharging at a higher current as a single cell is possible. Energy polarization and output density can be improved by reducing the polarization of the discharge voltage.
(2) The dead space inside the battery can be reduced as compared with the case where one air electrode is disposed facing the negative electrode.

(Embodiment 4)
A hydrogen / air secondary battery according to Embodiment 4 will be described. In addition, about the thing similar to Embodiment 1 thru | or 3, the same code | symbol is attached | subjected and description is abbreviate | omitted.
FIG. 6 is a schematic cross-sectional view of the relevant part of a hydrogen / air secondary battery according to Embodiment 4 of the present invention.
In FIG. 6, the hydrogen / air secondary battery 1E of the fourth embodiment is different from that of the third embodiment in that both ends of the two electrolyte holding bodies 4a and 4b are electrolyzed in a common electrolyte storage section 6. It is a point immersed in the liquid. In addition, the structure of FIG. 6 can be set as one set, and a plurality of sets can be arranged in parallel in one battery container 1a. At this time, the air passage 5 can be shared between the adjacent air electrodes 2.
In the present embodiment, the negative electrode 3, the air electrode 2, and the electrolyte solution holders 4a and 4b are arranged in the vertical direction in the battery container 1a. However, as in the first embodiment, the structure may be arranged in the horizontal direction. Good.

According to the hydrogen / air secondary battery in the fourth embodiment configured as described above, in addition to the functions in the third embodiment, the following functions are provided.
(1) Since at least some of the plurality of electrolytic solution holders are immersed in the electrolytic solution in the common electrolytic solution storage unit, the structure of the electrolytic solution storage unit in the battery container can be simplified.
(2) Compared to the case where the electrolyte storage part is not common and is arranged for each electrolyte holder, the volume of the electrolyte storage part can be reduced, and the volume of the entire battery is also reduced. The energy density per volume and the power density can be improved.

(Embodiment 5)
A hydrogen / air secondary battery according to Embodiment 5 will be described. In addition, about the thing similar to Embodiment 1 thru | or 4, the same code | symbol is attached | subjected and description is abbreviate | omitted.
FIG. 7 is a schematic cross-sectional view of the relevant part of a hydrogen / air secondary battery according to Embodiment 5 of the present invention.
In FIG. 7, the hydrogen / air secondary battery 1 </ b> F of the fifth embodiment is different from the fourth embodiment in that two electrolyte solution holders 4 a and 4 b are connected by a connecting portion 4 c in a common electrolyte storage unit 6. It is an integrated point. The electrolytic solution holders 4a and 4b and the connection portion 4c may be integrated as a matter of course. Moreover, the structure of FIG. 7 can be set as one set, and a plurality of sets can be arranged in parallel in one battery container 1a. At this time, the air passage 5 can be shared between the adjacent air electrodes 2.
In the present embodiment, the negative electrode 3, the air electrode 2, and the electrolytic solution holders 4a and 4b are arranged in the vertical direction in the battery container 1a. However, as in the first embodiment, the structure may be arranged in the horizontal direction. Good.

According to the hydrogen / air secondary battery in the fifth embodiment configured as described above, in addition to the functions in the fourth embodiment, the following functions are provided.
(1) Since the two electrolyte holders are connected in the common electrolyte reservoir, the two electrolyte holders are integrated with the two air electrodes via the electrolyte reservoir. The number of members of the liquid holder can be reduced.
(2) It becomes possible to keep the amount of the electrolyte in the electrolyte holder between the air electrode and the negative electrode uniform between the two air electrodes and the negative electrode, and between each air electrode and the negative electrode. It is possible to prevent the balance of the amount of the existing electrolyte from being lost, and to prevent the interelectrode voltage between each air electrode and the negative electrode from being different.

(Embodiment 6)
A hydrogen / air secondary battery according to Embodiment 6 will be described. In addition, about the thing similar to Embodiment 1 thru | or 5, the same code | symbol is attached | subjected and description is abbreviate | omitted.
FIG. 8 is a schematic cross-sectional view of the relevant part of a hydrogen / air secondary battery according to Embodiment 6 of the present invention.
In FIG. 8, the hydrogen / air secondary battery 1G of the sixth embodiment is different from that of the fifth embodiment in that the two airs facing the negative electrode 3 and the negative electrode 3 in the hydrogen / air secondary battery 1F of the fifth embodiment. Two pairs of electrode pairs in which the longitudinal direction of the pole 2 is arranged in parallel with the vertical direction are arranged in parallel in the battery container 1a, and the electrolyte holders 4b are connected to each other in the common electrolyte storage part 6 by the connecting part 4d. Thus, a common air passage 5a that is integrated in a meandering manner and communicates with the outside of the battery case 1a is formed between two adjacent air electrodes 2.
Thereby, the dispersion | variation in the voltage between each air electrode 2 and the negative electrode 3 can be suppressed, and it can equalize.

In the present embodiment, as described above, all the electrolytic solution holders 4a and 4b are connected by the connecting portions 4c and 4d, and the common electrolytic solution storage unit 6 is immersed in the electrolytic solution. The configurations of 3 to 5 hydrogen / air secondary batteries 1D to 1F may be arranged in parallel in the battery container 1a.
Further, in the present embodiment, the case where the number of electrode pairs arranged in parallel in the battery container 1a is two has been described, but the number of electrode pairs can be appropriately selected.
Moreover, although the negative electrode 3, the air electrode 2, and the electrolyte solution holders 4a and 4b are arranged in the vertical direction in the battery container 1a, the structure may be arranged in the horizontal direction as in the first embodiment. The electrolytic solution holders 4a and 4b and the connection portions 4c and 4d may be integrated as well.

According to the hydrogen / air secondary battery in the fifth embodiment configured as described above, in addition to the functions in the fifth embodiment, the following functions are provided.
(1) Maximum discharge as a unit cell is possible by arranging two pairs of electrode pairs in which the negative electrode and the two air electrodes facing the negative electrode are arranged in parallel in the vertical direction in the battery container Current, power density, and energy density can be improved.
(2) Since a plurality of electrode pairs are arranged in parallel in a single container, the volume occupied by the whole battery can be reduced as compared with the case where a plurality of batteries each made up of a single electrode pair are connected.
(3) By arranging the air electrode and the negative electrode vertically, the pressure increases due to water generated between the air electrode and the negative electrode by discharge, and the pressure decrease due to water that decreases between the air electrode and the negative electrode due to charging, and gravity. By adding the interaction between sedimentation and capillary action, the electrolyte holder between the air electrode and the negative electrode from the electrolyte storage part corresponds to the decrease / increase in water between the air electrode and the negative electrode during charge / discharge. In addition, the electrolyte can be supplied at a more appropriate timing, or the electrolyte can be stored at a more appropriate timing from the electrolyte holder between the air electrode and the negative electrode to the electrolyte reservoir.

Hereinafter, the present invention will be specifically described by way of examples. The present invention is not limited to these examples.
Example 1
Bi (NO ₃ ) ₃ · 5H ₂ O and H ₂ IrCl ₆ · 6H ₂ O are dissolved in distilled water at 75 ° C. to the same concentration, stirred and mixed, and then added with 2 mol / L NaOH aqueous solution. It was.
At that time, the bath temperature was 75 ° C., and the mixture was stirred for 3 days while carrying out oxygen bubbling. The solution containing the precipitate formed thereby was kept at 85 ° C. and evaporated to dryness to obtain a paste. The paste-like material was transferred to an evaporating dish, dried at 120 ° C. for 12 hours, pulverized in a mortar, and then baked in an air atmosphere at 600 ° C. for 2 hours. Next, in order to remove by-products contained in the fired product, suction filtration was performed using distilled water at 70 ° C. to isolate pyrochlore-type bismuth iridium oxide. Furthermore, after drying this at 120 degreeC for 12 hours, it grind | pulverized using the mortar and obtained the bismuth iridium oxide powder.
The thus obtained bismuth iridium oxide powder, nickel powder (purity 99.8%, particle size 10-20 μm), and commercially available PTFE (polytetrafluoroethylene) particles are in a weight ratio of 20:70:10. The mixture is made into a clay and then dried at room temperature for about 30 minutes, and then pressed into a disk shape (diameter: 13 mm, thickness: 0.3 mm) at 100 kg / cm ² on a nickel mesh as a current collector. After that, heat treatment was performed in a nitrogen atmosphere at 370 ° C. for 13 minutes to produce an air electrode.

Hydrogen storage alloy (MmNi _4.10 Mn _0.40 Al _0.10 Co _0.50 , capacity density 310 mAh / g), nickel powder (purity 99.8%, average particle size 3-7 μm) and polyethylene mixed at a weight ratio of 2: 3: 0.12. Thereafter, it was press-molded into a disk shape at 5 t / cm ² and further heat-treated at 150 ° C. for 60 minutes in a vacuum heating furnace to produce a negative electrode (theoretical capacity 31 mAh) having almost the same area as the air electrode. A nickel ribbon was resistance-welded to the negative electrode as a lead.
The above-described air electrode and negative electrode, a commercially available alkaline battery separator (manufactured by Yuasa Membrane Systems, registered trade name: Yumigrapher) as an electrolyte solution holder, and a 7 mol / L aqueous KOH solution as an electrolyte solution are shown in FIG. A hydrogen / air secondary battery having a structure was prepared using PTFE (polytetrafluoroethylene) as a material for a battery container. In the PTFE container, a space serving as an electrolytic solution storage unit was disposed, and 5 mL of the electrolytic solution was injected into the space. The area of the electrolytic solution holder is larger than that of the air electrode and the negative electrode, and a part of the electrolytic solution holder is immersed in the electrolytic solution in the electrolytic solution storage unit. A nickel wire was used for the lead of the air electrode.

(Comparative Example 1)
The same hydrogen / air secondary battery as that of Example 1 was manufactured except that the battery container was not provided with a space serving as an electrolyte solution storage unit, and the electrolyte solution holding body had almost the same area as the air electrode and the negative electrode. In addition, the electrolyte solution hold | maintained at the electrolyte solution holder was about 60 microliters.

FIG. 9 shows the results of charging and discharging the batteries of Example 1 and Comparative Example 1 at room temperature and 2 mA, and recording the battery voltage during charging and discharging.
In FIG. 9, the horizontal axis represents the number of charge / discharge cycles (times), and the vertical axis represents the battery voltage (V) during discharge and charge.
In Example 1, charge / discharge of 300 cycles or more was possible, and a stable voltage of an average discharge voltage of 0.9 to 0.73 V (see white circle) and an average charge voltage of 1.5 V (see gray circle) was shown.
On the other hand, in Comparative Example 1, the initial charge / discharge test showed substantially the same discharge voltage and charge voltage as in Example 1 (see white squares and gray squares), but the charge / discharge was completed in 10 cycles, and 11 cycles. Can no longer charge / discharge. As a result of disassembling the battery of Comparative Example 1, it was found that almost no electrolyte remained in the electrolyte holder.
From the above results, supply of the electrolytic solution from the electrolytic solution storage unit and storage of the electrolytic solution in the electrolytic solution storage unit with respect to the decrease and increase of the electrolytic solution (water) in the electrolytic solution holder during charging and discharging. This makes it possible to keep the amount of electrolyte held in the electrolyte holder substantially constant, and to repeatedly perform stable charge and discharge, and to provide hydrogen / air with excellent operational stability, high quality, and long life. It became clear that a secondary battery could be realized.

(Example 2)
A bismuth iridium oxide powder produced by the same method as in Example 1, a nickel powder (purity 99.8%, particle size 10 to 20 μm), and commercially available PTFE (polytetrafluoroethylene) particles in a weight ratio of 20:70: After mixing with a nickel press and pressing with a roll press, heat treatment was performed at 370 ° C. for 13 minutes in a nitrogen atmosphere to produce a square air electrode (45 mm × 45 mm, thickness 0.2 mm) did. Further, using the same hydrogen storage alloy as in Example 1, this was roll-pressed together with EVA (ethyl vinyl acetate) in foamed nickel to form a negative electrode (theoretical capacity 600 mAh) having almost the same area as the air electrode. . The weight ratio of the hydrogen storage alloy, foamed nickel, and EVA was 1: 1: 0.01.
FIG. 2 shows the air electrode and negative electrode, a commercially available alkaline battery separator (manufactured by Yuasa Membrane Systems Co., Ltd., Yumigrapher) and a nonwoven fabric as the electrolyte holder, and a 7 mol / L KOH aqueous solution as the electrolyte. A hydrogen / air secondary battery having the structure described above was fabricated using PTFE (polytetrafluoroethylene) as a material for the battery container. In the PTFE container, a space serving as an electrolytic solution storage unit was disposed, and 5 mL of the electrolytic solution was injected into the space. The area of the electrolytic solution holder is larger than that of the air electrode and the negative electrode, and a part of the electrolytic solution holder is immersed in the electrolytic solution in the electrolytic solution storage unit. A nickel wire was used for the lead of the air electrode.

(Comparative Example 2)
The same hydrogen / air secondary battery as that of Example 2 was manufactured except that the battery container was not provided with a space serving as an electrolyte solution storage unit, and the electrolyte solution holding body had almost the same area as the air electrode and the negative electrode. In addition, the electrolyte solution hold | maintained at the electrolyte solution holding body was about 1 mL.

FIG. 10 shows the results of recording the battery voltage during discharge when the batteries of Example 2 and Comparative Example 2 were charged and discharged at room temperature and a constant current. In addition, Example 2 is 50 mA, and Comparative Example 2 is 30 mA.
In Example 2, discharge for 10 hours was possible with respect to discharge at 50 mA, and a stable discharge voltage was obtained. On the other hand, in Comparative Example 2, the discharge time was 7.5 hours despite discharge at a lower current than that in Example 2. At this time, the discharge electricity amount of Example 2 was 508 mAh, the discharge electricity amount of Comparative Example 2 was 219 mAh, and Example 2 was able to discharge twice or more that of Comparative Example 2. The volume energy density was 308 Wh / L in Example 2 and 115 Wh / L in Comparative Example 2. In Example 2, the energy density was improved 2.7 times compared to Comparative Example 2. In addition, as a result of measuring the maximum dischargeable current value with a dischargeable limit voltage at which a stable discharge voltage can be obtained being 0.1 V, Example 2 is 600 mA and Comparative Example 2 is 150 mA. In Example 2, the maximum dischargeable current value was improved four times. Further, the utilization rate of the hydrogen storage alloy for the negative electrode was 84% in Example 2 and 29% in Comparative Example 2, and the utilization rate was improved about 3 times.
From the above results, supply of the electrolytic solution from the electrolytic solution storage unit and storage of the electrolytic solution in the electrolytic solution storage unit with respect to the decrease and increase of the electrolytic solution (water) in the electrolytic solution holder during charging and discharging. Therefore, it is possible to keep the amount of electrolyte held in the electrolyte holder substantially constant and to perform stable discharge, thereby improving the maximum current value, output and energy density that can be discharged, and operating. It became clear that a hydrogen / air secondary battery with excellent discharge characteristics as well as stability, high quality and long life can be realized.

  The present invention suppresses a large change in voltage during charging and discharging, is excellent in charge / discharge cycle characteristics, has no electrolyte leakage, and is excellent in rechargeability and durability. Hydrogen / air secondary with excellent operational stability, high quality, and long life that can perform stable charge and discharge even when the battery capacity is large or when the discharge current or charge current is large. Provides batteries, power supplies for mobile devices such as personal computers, mobile phones, portable music players, portable video players, and portable book terminals, electric work machines such as electric cars, hybrid cars, electric bikes, electric bicycles, excavators, and electric construction Power or auxiliary batteries for machinery, etc., automobile, household, commercial, and industrial fuel cells for power storage and output regulation, solar power generation, wind power generation, hydropower generation, atomic power It can be used, such as the power storage and output adjustment batteries such as power generation.

1, 1A, 1B, 1C, 1D, 1E, 1F, 1G Hydrogen / air secondary battery 1a Battery container 2 Air electrode 3 Negative electrode 4, 4a, 4b Electrolyte holder 4c, 4d Connection portion 5, 5a Air passage 6 Electrolysis Liquid storage part

Claims (8)

An air electrode disposed in the battery container, a negative electrode using a hydrogen storage alloy disposed in the battery container opposite to the air electrode, and disposed between the air electrode and the negative electrode. A hydrogen / air secondary battery comprising an electrolyte solution holding body for holding an electrolyte solution,
An electrolytic solution storage unit that supplies an electrolytic solution that decreases due to a charging reaction or stores an electrolytic solution that increases due to a discharging reaction is formed in the battery container separately from the air electrode and the negative electrode . At least a part of the electrolyte solution is immersed in the electrolyte solution in the electrolyte solution storage unit, and supply and storage of the electrolyte solution are performed between the air electrode and the negative electrode and the electrolyte solution storage unit via the electrolyte solution holding body. A hydrogen / air secondary battery, characterized in that it is performed between the two. The hydrogen / air secondary battery according to claim 1, wherein the air electrode contains nickel, a pyrochlore oxide containing iridium, and a binder. The hydrogen / air secondary battery according to claim 2, wherein the pyrochlore oxide containing iridium is bismuth iridium oxide. The two air electrodes are disposed to face the negative electrode, and the electrolyte holder is disposed between the negative electrode and each of the air electrodes. The hydrogen / air secondary battery according to any one of the above. 5. The hydrogen / air secondary battery according to claim 4, wherein at least a part of the plurality of electrolyte solution holders are immersed in the electrolyte solution in the common electrolyte storage unit. 6. The hydrogen / air secondary battery according to claim 5, wherein a plurality of the electrolyte holders are connected in a common electrolyte storage section. The electrode pair in which a longitudinal direction of the negative electrode and one or two of the air electrodes facing the negative electrode is arranged in parallel with a horizontal direction is laminated in the battery container. 7. The hydrogen / air secondary battery according to any one of 1 to 6. A plurality of electrode pairs in which a longitudinal direction of the negative electrode and one or two air electrodes facing the negative electrode are arranged in parallel with a vertical direction are arranged in parallel in the battery container. Item 7. The hydrogen / air secondary battery according to any one of Items 1 to 6.