WO2012173091A1

WO2012173091A1 - Reversible fuel cell, system for reversible fuel cell, reversible fuel cell module, and reversible fuel cell bank

Info

Publication number: WO2012173091A1
Application number: PCT/JP2012/064920
Authority: WO
Inventors: 堤　敦司; 堤　香津雄
Original assignee: 国立大学法人東京大学; エクセルギー工学研究所株式会社
Priority date: 2011-06-15
Filing date: 2012-06-11
Publication date: 2012-12-20
Also published as: TW201306373A; JPWO2012173091A1; TWI466372B; JP5515028B2

Abstract

A reversible fuel cell has a positive electrode containing manganese dioxide, a negative electrode containing a hydrogen occlusion material, a separator interposed between the positive electrode and the negative electrode, and an electrolyte. The negative electrode and the positive electrode are electrodes for generating electricity, and are adapted for electrolyzing the electrolyte using an electric current supplied from an outside source. This cell enables electrical energy supplied during overcharging to be converted into a gas and stored, and the gas to be converted back to electric energy for use. There is accordingly provided a reversible fuel cell and cell system demonstrating exceptional energy usage efficiency, energy density, and load-following characteristics.

Description

Reversible fuel cells, reversible fuel cell systems, reversible fuel cell modules, and reversible fuel cell banks

The present invention relates to a reversible fuel cell capable of storing electric energy supplied at the time of charge as chemical energy and reconverting the stored chemical energy into electric energy for utilization, and a reversible fuel cell system using the same. , A reversible fuel cell module, and a reversible fuel cell bank.

Secondary batteries and fuel cells are highly efficient and clean energy sources. In recent years, development of electric vehicles, fuel cell vehicles, and trains, which use such secondary batteries and fuel cells as power sources, has progressed worldwide.

Fuel cells are attracting attention as power supplies with low environmental load, which have high energy conversion efficiency. Fuel cells conventionally developed and put into practical use include, for example, solid polymer fuel cells, alkaline electrolyte fuel cells, phosphoric acid fuel cells, molten carbonate fuel cells, and solid oxide fuel cells. .

Fuel cells can not store electricity. However, it is possible to construct a kind of power storage system by combining a fuel cell and a hydrogen production apparatus by electrolysis of water. Such a power storage system is called a reversible fuel cell (see Patent Document 1 and Patent Document 2). In such a reversible fuel cell in which a fuel cell and a water electrolysis system are combined, when power is not generated, electrolysis of water, which is a reverse reaction of power generation, is performed using natural energy or nighttime power. Thus, this power generation system produces its own fuel.

On the other hand, the secondary battery is used as a power source for electric and electronic devices that require a large current discharge, such as a power tool. In particular, nickel hydrogen secondary batteries and lithium ion secondary batteries have recently attracted attention as batteries for engine and battery-powered hybrid vehicles.

A normal secondary battery can be charged by receiving a supply of electrical energy and can store electricity. However, without a power source, the secondary battery can not be charged. For this reason, the secondary battery does not have sufficient convenience. Therefore, Patent Document 3 discloses a secondary battery that can be charged using a gas. In addition, Patent Document 4 discloses a new type of fuel cell using a combination of a fuel cell and a secondary cell, which uses manganese hydroxide as a positive electrode active material and a hydrogen storage alloy as a negative electrode active material. .

Patent Documents

5 and 6 propose a method for cooling a battery. That is, there has been proposed a cooling method including efficient dissipation of heat by the projections provided on the surface of the battery case. Furthermore, a cooling method has been proposed which includes providing a perforated metal plate between the battery pack and flowing cooling air through the hole.

JP 2002-348694 JP 2005-65398 A JP, 2010-15729, A JP, 2010-15783, A JP, 2009-016285, A Japanese Patent Application Publication No. 2003-007355

The secondary battery can store electricity. However, the amount of active material of the negative electrode and the positive electrode depends on the volume of the battery. For this reason, there is a limit to the electrical capacity that can be stored in the battery. In the nickel-hydrogen secondary battery, the weight ratio (weight ratio) of the reducing substance and the oxidizing substance that can be stored with respect to the weight of the active material is small. For example, the weight ratio of hydrogen that can be stored in an AB5-type hydrogen storage alloy containing misch metal nickel alloy is about 1.2% by weight. For this reason, it is difficult for the secondary battery to greatly increase the energy density.

On the other hand, the fuel cell generates (discharges) electricity using hydrogen gas or oxygen gas supplied from the outside. For this reason, the fuel cell does not have the problem of the limit of the energy density that occurs in the secondary cell. Generally, in order to use a fuel cell, a device or member for supplying hydrogen gas and oxygen gas to the electrode part needs to be used. Also, the fuel cell's ability to follow load fluctuations is inferior to secondary batteries. For this reason, it is difficult to use only a fuel cell as a power source of a device having a large load fluctuation such as a vehicle. Usually, a fuel cell is used together with a storage device such as a secondary battery or a capacitor. In addition, the reaction site of the fuel cell is an extremely small interface where three phases of solid (electrode), liquid (electrolyte solution) and gas (hydrogen gas, oxygen gas) are in contact. Therefore, the output characteristics of the fuel cell are inferior to those of the secondary cell. There is also a method using platinum as a catalyst to improve output characteristics. However, this approach is costly.

Furthermore, the gas extracted from the hydrogen production apparatus (for example, Patent Document 1) is an oxyhydrogen gas in which the ratio of hydrogen to oxygen is 2: 1. Therefore, care must be taken to ensure safety.

The secondary battery disclosed in Patent Document 3 can be discharged like a fuel cell by receiving a gas supply. For this reason, the capacity of the secondary battery is not limited to the amount of the active material as in a normal secondary battery. However, an apparatus or member is required to supply hydrogen gas and oxygen gas to the electrode portion.

The "fuel cell storage battery" disclosed in Patent Document 4 receives supply of gas from a gas storage room provided independently to generate (discharge). This eliminates the need for additional devices or components for supplying hydrogen gas and oxygen gas to the electrode portion. In addition, since the gas storage room is provided independently, safety is ensured. However, since the battery described in Patent Document 4 uses manganese hydroxide as a positive electrode active material, trimanganese tetraoxide which does not contribute to the charge / discharge reaction is generated while repeating charge / discharge. Therefore, this fuel cell has the problem that the life characteristics are poor.

A zinc-manganese primary battery is widely known as an aqueous solution battery using manganese dioxide as a positive electrode. Zinc manganese batteries are used exclusively as primary batteries and not as secondary batteries. The reason is described below. That is, in the positive electrode of the manganese battery, a change occurs such as manganese dioxide MnO ₂ → manganese oxyhydroxide MnOOH → manganese hydroxide Mn (OH) _{2 in} the discharge process. At this time, the discharge until the manganese hydroxide is generated is made, the trimanganese tetraoxide Mn ₃ O ₄ can not be charged is generated. That is, trimanganese tetraoxide which is an irreversible substance generated in the positive electrode while the discharge process (manganese oxyhydroxide → manganese hydroxide) and the charge process (manganese hydroxide → manganese oxyhydroxide) are repeated. There is a problem of increasing.

Manganese trioxide has the property of low conductivity. If the conductivity is low, it takes time to charge, which makes it difficult to fully charge the battery. In addition, if the conductivity is low, the charging efficiency will also deteriorate. Thus, as the manganese trioxide increases, the fuel cell degrades in performance and eventually becomes unusable. For this reason, manganese dioxide is used exclusively for primary batteries and is not currently used as a positive electrode active material for secondary batteries.

The separator, which is one of the components of the battery, prevents a short circuit between the positive electrode and the negative electrode. The separator is an important part for the battery. The separator is made of a material having a low thermal conductivity (a material which is difficult to transmit heat). In the wound battery, the stacked electrodes and the separator are spirally wound. For this reason, in the wound battery, separators are interposed in multiple layers from the battery center to the surface. Therefore, although the surface temperature of the wound battery is close to the ambient temperature, the temperature in the central portion is high. For this reason, even if the outside of the wound battery is cooled, the inside of the battery is not cooled to a necessary level and remains at high temperature.

Various methods for battery cooling are proposed in US Pat. These are all effective for cooling the surface of the battery case. However, in the case of a wound battery, separators with low thermal conductivity are wound in layers. For this reason, these methods are not effective as a method of cooling a wound battery.

The present invention has been made in view of the above-mentioned prior art. In the present invention, the fuel cell having a high energy density incorporates the reaction mechanism of the secondary battery excellent in load followability. As a result, a reversible fuel cell excellent in power density, energy density, and load following ability, safety is ensured, and excellent in life characteristics is provided.

The inventors conducted intensive studies to solve the above problems and completed the reversible fuel cell of the present invention.

The reversible fuel cell (hereinafter, the present fuel cell) of the present invention has a positive electrode containing manganese dioxide, a negative electrode containing a hydrogen storage material, a separator interposed between the positive electrode and the negative electrode, and an electrolyte. The negative electrode and the positive electrode are electrodes for power generation, and are electrodes that electrolyze the electrolytic solution using a current supplied from the outside.

According to this configuration, the positive electrode and the negative electrode each have an active material. Therefore, the fuel cell has a function as a storage battery. That is, it is possible to generate power without receiving the supply of gas, and it is also possible to charge using current. Furthermore, in the fuel cell, when the fuel cell in the fully charged state is further supplied with current, the electrolytic solution is decomposed into water. Thereby, oxygen gas and hydrogen gas are generated from each electrode. In addition, the positive electrode and the negative electrode function as electrodes for generating electric power using oxygen and hydrogen as fuel, respectively. That is, the positive electrode and the negative electrode of the present fuel cell not only function as an electrode of the present fuel cell but also function as an electrode for water decomposition.

In the fuel cell, the discharge reaction of the negative electrode and the positive electrode may be a reaction represented by Formula (1) and Formula (3), respectively, and the charge reaction of the negative electrode and the positive electrode is represented by Formula (2) And the reaction represented by formula (4).
^{MH → M + H + + e} - (1)
M + 1 / 2H ₂ → MH (2)
_{^{^{MnO 2 + H + + e -}}} → MnOOH (3)
MnOOH + O ₂ → MnO ₂ + H ₂ O (4)
However, in formulas (1) and (2), M represents a hydrogen storage material.

As shown in equations (2) and (4) showing the charge process of the present fuel cell, the negative electrode and the positive electrode are chemically charged with hydrogen and oxygen, respectively.
As shown in the above reaction formulas (3) and (4), the positive electrode active material repeats charge and discharge between manganese dioxide and manganese oxyhydroxide.

When manganese dioxide is discharged to manganese hydroxide, trimanganese tetraoxide is generated. Therefore, the inventors considered that trimanganese tetraoxide would not occur and the cathode would not deteriorate unless the manganese dioxide was discharged to manganese hydroxide. And the inventors confirmed that by experiment. This experiment is shown below.

The inventors examined the transition of the charge-discharge cycle characteristics of manganese dioxide according to the depth of discharge reaction by experiments. The results are shown in FIGS. 19A and B. The vertical axes of FIGS. 19A and 19B represent the potential of the electrode, and the horizontal axes represent the amount of discharged electricity. The discharge curve shown in FIG. 19A is obtained when charge and discharge in one electron reaction are repeated 30 times. The discharge curve shown in FIG. 19B is obtained when charge and discharge in the two electron reaction are repeated 30 times. According to FIG. 19A, the discharge curve hardly changes even if charge and discharge are repeated. On the other hand, according to FIG. 19B, it can be seen that the amount of discharged electricity decreases as charge and discharge are repeated. The one electron reaction is a discharge reaction in which manganese dioxide is converted to manganese oxyhydroxide. The two-electron reaction is a discharge reaction in which manganese dioxide is converted to manganese hydroxide through manganese oxyhydroxide. From the experimental results shown in FIGS. 19A and 19B, it can be seen that the discharge characteristics are almost uniform as long as the one-electron reaction remains. Furthermore, it can be seen that, when the two-electron reaction occurs, the discharge characteristics gradually deteriorate as charge and discharge are repeated. From this, it can be seen that the electrode is degraded.

The inventors conducted XRD measurement on the electrode after charge and discharge to investigate the cause of the deterioration. The results are shown in FIG. As shown in the graph (a) of FIG. 20, when charge and discharge are repeated in the one electron reaction, almost no new peak is generated except for the one corresponding to the crystal structure of the electrode before the experiment (FIG. The graph (s) of 20 shows the measurement results of the electrode before the experiment). However, as shown in the graph (b) of FIG. 20, when charge and discharge are repeated in the two-electron reaction, the characteristic peak derived from manganese dioxide is almost eliminated while the peak derived from trimanganese tetraoxide appears. From this, it is understood that the generation of trimanganese tetraoxide can be suppressed by stopping the discharge when manganese dioxide becomes manganese oxyhydroxide.

Even if manganese dioxide is oxidized by discharge, when the electrode is brought into contact with oxygen, it returns to manganese dioxide, so the reaction does not proceed to manganese hydroxide and irreversible trimanganese tetraoxide is not generated. That is, manganese dioxide was successfully used as a positive electrode by contacting with oxygen at the stage where manganese dioxide was oxidized and charging it.

21A and 21B show experimental results showing that charging can be performed by contacting the positive electrode with oxygen gas.
FIG. 21 shows a case where manganese oxyhydroxide is used as a positive electrode, silver (Ag) is used as a reference electrode, and a half-cell is formed using an alkaline electrolyte, and charging and discharging by pressurized input of oxygen gas are performed. The potential change of the positive electrode is plotted against time. The vertical axis in FIG. 21 indicates the potential of the positive electrode (V vs. Ag / AgCl), and the horizontal axis indicates the elapsed time (minutes). In a half cell using manganese dioxide as a positive electrode and silver as a reference electrode, the cutoff potential is -0.5 V when the positive electrode becomes manganese oxyhydroxide by discharge. Before charging (time zero) in FIG. 21, the positive electrode potential is −0.5 V, which indicates that the positive electrode is manganese oxyhydroxide.

(I) of FIG. 21A is a graph showing the potential with respect to the reference electrode after the oxygen gas is pressurized and introduced into the positive electrode. (Ii) of FIG. 21A is a graph in the case where the supply of oxygen gas is stopped and discharge is performed at 0.2C. As shown in FIG. 21A, when the positive electrode is brought into contact with oxygen gas (solid line), after 60 minutes, the positive electrode shows a state of almost full charge, and then discharges at 0.2 C. It shows. On the other hand, when oxygen gas is not brought into contact (dotted line), the positive electrode shows that almost no charge is performed. As a result, it was confirmed that the fuel cell cathode reaction (oxidation-reduction reaction) occurs due to the oxygen gas, and that the discharge due to the secondary cell reaction occurs after the oxygen gas shutoff. FIG. 21B shows the state of charge by oxygen gas at the time of discharge at 0.2C. From this figure, it can be seen that charging with oxygen gas is possible even during discharge. From the experimental results shown in FIGS. 21A and 21B, it was confirmed that charging is possible by supplying oxygen gas to the positive electrode.

In the reaction formula of the present fuel cell, H ₂ of Formula (2) may be hydrogen gas. Further, O ₂ in the formula (4) may be oxygen dissolved in the electrolyte solution. Further, the fuel cell may have a first oxygen storage chamber for holding an electrolyte solution in which oxygen is dissolved, and a hydrogen storage chamber for holding hydrogen gas inside the battery.

According to this configuration, when the active material in the fully charged electrode is further charged by the current, hydrogen gas is generated at the negative electrode by electrolysis of water (hereinafter simply referred to as electrolysis). This hydrogen gas can be stored in a hydrogen storage chamber. Further, oxygen gas generated at the positive electrode by electrolysis dissolves in a high-pressure electrolyte solution. For this reason, oxygen can be stored in the first oxygen storage chamber as an oxygen-dissolved electrolyte. That is, hydrogen gas and oxygen gas generated at the negative electrode and the positive electrode by electrolysis can be separately stored in the respective storage chambers without contacting and reacting each other.

The hydrogen gas stored in the hydrogen storage chamber and the oxygen stored in the first oxygen storage chamber can be reconverted to electrical energy and used when the battery is discharged. In particular, the oxygen gas generated at the positive electrode is dissolved in the electrolyte solution and is not stored in a gas state. This improves the safety of oxygen handling. When the battery is discharged, electrical energy can be taken out as a secondary battery. For this reason, rapid discharge is possible, and load followability can be improved.

As described above, the electric capacity of the secondary battery is determined by the amount of the active material contained in the electrode material. For this reason, it is difficult to increase the energy density of the secondary battery. However, in the fuel cell, electric energy that can be taken out to the outside is stored as chemical energy in each storage chamber.

As a result, the storage capacity of chemical energy per volume can be increased and the volumetric energy density of the fuel cell can be improved by enhancing the pressure resistance performance and the sealing performance of each storage chamber and a battery including the storage compartment. It becomes.

According to this configuration, the manganese dioxide in the positive electrode temporarily becomes manganese oxyhydroxide by the discharge. However, it is charged by oxygen dissolved in the electrolyte and returns to manganese dioxide. Thus, the positive electrode does not discharge to such an extent that manganese dioxide changes from manganese oxyhydroxide to other substances. By charge and discharge, the active material of the positive electrode changes between manganese dioxide and manganese oxyhydroxide. Therefore, trimanganese tetraoxide which does not contribute to charge and discharge does not occur. In addition, since trimanganese tetraoxide does not occur, the decrease in conductivity is also suppressed.

The first oxygen storage chamber and the hydrogen storage chamber of this configuration may not necessarily be dedicated independent spaces. These storage chambers may be formed in a gap of a mixture containing active materials of positive and negative electrodes or the like, or in a gap generated inside the battery.

In the fuel cell, the first oxygen storage chamber and the hydrogen storage chamber may be divided by a movable member.

According to this configuration, the first oxygen storage chamber and the hydrogen storage chamber may be provided adjacent to each other. Since the two chambers are partitioned by the movable member, if the pressure of the hydrogen storage chamber becomes high due to hydrogen gas generated by overcharging, the movable member is deformed under the influence of the pressure. By this deformation, the electrolyte in the first oxygen storage chamber is compressed, and the pressure of the electrolyte is equalized with the pressure in the hydrogen storage chamber to become a high pressure. The bulk modulus of the liquid is much larger than that of the gas. For this reason, the amount of deformation of the movable member is very small. The movable member may be a flexible member and may include an elastic body. The movable member may have a thin plate-like or membrane-like structure. Furthermore, the movable member may be a positive electrode or a negative electrode. The movable member may be a synthetic resin such as rubber or polypropylene, or a thin metal film.
A communication passage may be provided between the first oxygen storage chamber and the hydrogen storage chamber. In this case, the pressure of the hydrogen storage chamber may be transmitted to the electrolyte of the first oxygen storage chamber via the movable member disposed in the communication passage. In this case, the movable member may be a piston.

In the fuel cell, the movable member may be a flexible member, and the flexible member preferably includes the positive electrode, the negative electrode, and a separator.

In the fuel cell, the cylindrical positive electrode and the cylindrical negative electrode are disposed inside the cylindrical case via the radial space via the separator, and the opposite side of the positive electrode to the separator is disposed. The first oxygen storage chamber is formed in contact with the surface of the hydrogen storage chamber, the hydrogen storage chamber is formed in contact with the surface of the negative electrode opposite to the separator, and the diameter of the first oxygen storage chamber is The hydrogen storage chamber is disposed inward of the negative electrode, or the hydrogen storage chamber is disposed in the radial space, and the first oxygen storage chamber is You may be arrange | positioned inside the said positive electrode. In this configuration, the case functions as an exterior body.

The fuel cell is provided with an anode terminal electrically connected to the anode provided at one end in the axial direction of the case, and electrically connected to the cathode provided at the other end in the axial direction of the outer package. 2 further comprising a connected positive electrode terminal, a protrusion provided on either the positive electrode terminal or the negative electrode terminal, and a hole provided on the other of the positive electrode terminal or the negative electrode terminal; The protrusion and the hole may be engageable so that two reversible fuel cells are connected in series. In this configuration, the case functions as an exterior body.

The fuel cell module of the present invention has a plurality of cell units connected in series, and this cell unit faces a plurality of reversible fuel cells so as to sandwich the plurality of reversible fuel cells. And a plurality of current collecting plates provided, wherein the positive electrode terminal is connected to the one current collecting plate, and the negative electrode terminal is connected to the other current collecting plate; The reversible fuel cells may be connected in parallel with each other via the current collector plate.

The fuel cell includes an outer shell having a cylindrical body, and a bulging portion disposed at both ends of the body and bulging outward of the opening and covering the opening. And the first oxygen storage chamber provided in the inner space of the bulging portion in the inner part, and the inside of the outer shell along the axial direction, both ends of which are open to the first oxygen storage chamber A current collector in the form of a tube, the positive electrode being disposed on the outer periphery of the current collector, the separator covering the positive electrode, and the hydrogen storage chamber being the separator and the hydrogen storage chamber. The negative electrode is filled in the hydrogen storage chamber, and the electrolyte is stored in the first oxygen storage chamber, and the first electrode is formed through the current collector. It is preferable to be able to transfer between oxygen storage rooms.

The fuel cell further comprises: an outer package having a cylindrical body; and a rod-like current collector penetrating the positive electrode, the negative electrode and the separator, wherein the positive electrode, the negative electrode and the separator are of the body. While being stacked in the axial direction, the positive electrode is accommodated inside the outer package, and the positive electrode has a cutout portion formed by cutting off a part of the outer periphery, and the outer periphery of the positive electrode is The positive electrode is not in contact with the current collector except for the notch and the positive electrode is not in contact with the current collector, and the negative electrode has a U-shaped cross section opened in the inner circumferential direction. The space between the negative electrode and the current collector is in contact and the space surrounded by the negative electrode and the current collector forms the hydrogen storage chamber, and the external dimension of the negative electrode is the cylinder. Smaller than the inner dimension of the part, and between the negative electrode and the body part Electrolyte reservoir is provided for, the first oxygen storage chamber may include the cutout portion and the electrolyte reservoir.

In this configuration, the outer package may include a pipe-like body and a lid member covering the opening of the body. Moreover, the exterior body may include a low-priced cylindrical can and a lid member provided at the opening.
If the exterior body has a cylindrical shape, the outer diameter of the positive electrode is larger than the inside diameter of the body portion, and the positive electrode abuts on the exterior body. In addition, since the size of the hole of the positive electrode through which the current collector penetrates is larger than the outer diameter of the current collector, the positive electrode and the current collector do not contact. Similarly, the size of the hole of the negative electrode is smaller than the outer diameter of the current collector, and the negative electrode and the current collector are in contact with each other.

The reversible fuel cell system of the present invention comprises the fuel cell, and an oxygen storage source and a hydrogen storage source connected to the fuel cell, wherein the oxygen storage source is oxygen dissolved in oxygen gas or electrolyte solution, While being able to be supplied to the present fuel cell, and capable of storing oxygen gas generated in the present fuel cell in a gas state or in a state dissolved in an electrolyte, the hydrogen gas storage source is a hydrogen gas as the present fuel cell The fuel cell may be capable of storing hydrogen gas generated by the fuel cell.

The reversible fuel cell system of the present invention is connected to the fuel cell and the fuel cell, and a salt concentration adjusting device for removing water contained in the electrolyte, and the fuel cell is connected to the electrolyte. And an oxygen concentration adjusting device for adjusting a dissolved oxygen concentration by supplying oxygen.

In the fuel cell, H _{2 of} Formula (2) may be hydrogen gas, and O _{2 of} Formula (4) may be oxygen gas. Then, is it possible to store hydrogen gas generated at the negative electrode or store a hydrogen storage chamber provided to be in contact with the negative electrode for supplying hydrogen gas to the negative electrode, and oxygen gas generated at the positive electrode? Alternatively, a second oxygen storage chamber provided to be in contact with the positive electrode may be provided to supply oxygen to the positive electrode.

According to this configuration, when charging is performed by a current when the inside of the electrode is in a fully charged state, hydrogen gas generated at the negative electrode and oxygen gas generated at the positive electrode are brought into contact and reacted with each other by electrolysis. Instead, the hydrogen storage chamber and the second oxygen storage chamber can be stored separately. Thus, hydrogen gas and oxygen gas can be stored in each storage chamber without the need for additional gas supply sources, supply passages, boosters and the like. Then, the stored hydrogen gas and oxygen gas can be converted to electrical energy when the battery is discharged and reused. At the time of discharge of the battery, electrical energy can be taken out by a normal discharge reaction as a secondary battery. That is, electrical energy is output through the electrode reaction of the secondary battery. Therefore, rapid charge and discharge and excellent charge and discharge followability can be obtained.

In the fuel cell, the negative electrode includes a hydrophilic material disposed on the surface in contact with the separator, and a hydrophobic material disposed on the surface in contact with the hydrogen storage chamber. And / or the positive electrode includes a hydrophilic material disposed on the surface in contact with the separator, and a hydrophobic material disposed on the surface in contact with the second oxygen storage chamber. desirable.

According to this configuration, the surface of the negative electrode in contact with the separator has hydrophilicity. This surface is kept almost always wet with the electrolyte. Thus, this surface prevents gas from passing through the negative electrode. In addition, the ion conductivity of the negative electrode is secured. The surface of the negative electrode in contact with hydrogen gas has hydrophobicity. Thereby, since the negative electrode does not get wet, good contact between the negative electrode and the hydrogen gas can be maintained. The surface of the positive electrode in contact with the separator has hydrophilicity. This surface is kept almost always wet with the electrolyte. This surface then prevents gas from passing through the positive electrode. In addition, the ion conductivity of the positive electrode is secured. Further, the surface of the positive electrode in contact with the oxygen gas has hydrophobicity. Thereby, since the positive electrode does not get wet, good contact between the positive electrode and the oxygen gas is maintained. The separator almost always contains the electrolytic solution to block the passage of gas. Thereby, the hydrogen storage chamber and the second oxygen storage chamber become independent. Therefore, the hydrogen gas and the oxygen gas are independently stored without being mixed with each other.

In a secondary battery, solid and liquid react. For this reason, since the secondary battery has a large reaction area, it is possible to increase the output. However, the electrode which is solid retains the oxidizing agent and the reducing agent. For this reason, the amount of energy of the secondary battery is small. On the other hand, the reaction surface of the fuel cell is an extremely small interface in which three phases of solid (electrode), liquid (electrolyte) and gas (hydrogen gas, oxygen gas) are in contact. Therefore, it is difficult for the fuel cell to increase the output. However, since the fuel cell supplies the oxidizing agent and the reducing agent as it is, the energy density is increased. The fuel cell is a battery combining the advantages of the two.
By the way, the characteristics of a secondary battery having a reaction surface of solid (electrode) and liquid (electrolyte) and the characteristics of a fuel cell having a reaction surface of solid (electrode), gas and liquid in one electrode If realized, it is possible to further increase the output and increase the energy capacity. Therefore, the interface in contact with the electrolyte solution of the electrode may be made hydrophilic while the interface in contact with the gas of the electrode may be made hydrophobic. Further, one surface of the electrode may be made hydrophilic while the other surface of the electrode may be made hydrophobic. Furthermore, the entire electrode may be made of a material having both hydrophilicity and hydrophobicity.

In the fuel cell, the electrolyte may be held in the second oxygen storage chamber. In this configuration, the electrolytic solution may be held in the second oxygen storage chamber, and oxygen gas may be held in the upper space thereof. For this reason, water generated on the surface of the positive electrode when discharged is replenished to the electrolytic solution. Electrolysis during charging takes place at the positive electrode interface. For this reason, it is convenient for the electrolyte to be held in the second oxygen storage chamber.

When the fuel cell has a cylindrical outer package, the cylindrical positive electrode and the cylindrical negative electrode are disposed inside the outer package via a space in the radial direction, with the separator interposed therebetween. The second oxygen storage chamber is formed in contact with the surface of the negative electrode opposite to the separator, and the hydrogen storage chamber is formed in contact with the surface of the negative electrode opposite to the separator; (2) The oxygen storage chamber is disposed in the radial space, and the hydrogen storage chamber is disposed inward of the negative electrode, or the hydrogen storage chamber is disposed in the radial space, and The second oxygen storage chamber may be disposed inward of the positive electrode.

In this configuration, additional members for forming the hydrogen storage chamber and the second oxygen storage chamber are unnecessary. Therefore, the present fuel cell has a simple structure including only the minimum number of members. Therefore, the dimensions of the fuel cell can be reduced, and the pressure resistance can thereby be ensured. Further, the energy density of the fuel cell can be increased, and the assembly work of the fuel cell can be facilitated.
The fuel cell comprises a cylindrical positive electrode disposed inside the outer package via a radial space, and a cylindrical negative electrode disposed inside the positive electrode via the separator. The second oxygen storage chamber may be formed in the radial space, and the hydrogen storage chamber may be formed inward of the negative electrode. By adopting the structure in which the positive electrode is disposed outside the negative electrode as described above, the surface area of the positive electrode can be made larger than the surface area of the negative electrode. Since the output of the battery is proportional to the surface area of the electrode, the output can be increased accordingly.

The fuel cell comprises an anode terminal electrically connected to the anode provided at one end in the axial direction of the outer package, and an anode electrically connected to the other end in the axial direction of the outer package. And a projection provided on any one of the positive electrode terminal and the negative electrode terminal, and a hole provided on the other of the positive electrode terminal and the negative electrode terminal, The protrusion and the hole may be engageable so that the two fuel cells are connected in series.

According to this configuration, the protrusions and the holes of the two fuel cells can be connected. Thus, a plurality of fuel cells can be connected in series without the need for wiring. While providing a convex part in the outer periphery of a projection part, you may provide a groove (groove) in the internal peripheral surface of a hole. In this case, the projection of the projection may be fitted in the groove of the hole. This makes it possible to reliably connect the two fuel cells.

The fuel cell module according to the present invention may have a plurality of cell units connected in series. This battery unit has a plurality of main fuel cells and a pair of current collectors provided so as to sandwich the plurality of main fuel cells, and the positive electrode terminal is connected to the one current collector. The fuel cell may be connected in parallel to each other through the current collector plate by connecting the negative electrode terminal to the other current collector plate.

According to this configuration, the fuel cell is disposed between the conductive current collectors. Thereby, the wiring connecting the fuel cells can be omitted. Therefore, modularization of the battery is facilitated. The current collector plate may have a nickel-plated aluminum plate. Through holes may be provided in the current collector plate. Then, the projection of the present fuel cell may be inserted into the through hole and fitted into the hole of another present fuel cell. As a result, the current collector plate becomes a bracket that connects the batteries in series and in parallel, and allows each battery to be fixed. This facilitates assembly of the battery module.

The fuel cell further includes an oxygen gas flow port communicating with the second oxygen storage chamber, and a hydrogen gas flow port communicating with the hydrogen storage chamber, wherein the hydrogen gas and the second oxygen storage in the hydrogen storage chamber are stored. It may be possible for the oxygen gas of the chamber to be taken out of the fuel cell separately.

In this configuration, the oxygen gas flow port may be provided in the outer package, and the hydrogen gas flow port may be provided in the outer package or the positive electrode terminal. In this way, the gas stored in the hydrogen storage chamber and the second oxygen storage chamber can be taken out of the fuel cell and stored in another container. Furthermore, hydrogen gas and oxygen gas can be fed into the hydrogen storage chamber and the second oxygen storage chamber from a container provided outside.

A battery bank according to the present invention includes: a plurality of fuel cells connected to each other; a first hydrogen gas pipe including an electrical conductor, a connection portion airtightly connectable to the hydrogen gas flow port; And a first oxygen gas pipe including an electrical conductor having a connection portion airtightly connectable to the gas flow port, wherein the first hydrogen gas pipe is a second hydrogen gas pipe via an insulator. And the first oxygen gas pipe is connected to the second oxygen gas pipe via the insulator, and the adjacent first oxygen gas pipe and the first hydrogen gas pipe are electrically connected by the conductor. The second hydrogen gas pipe may be connected to the hydrogen gas tank, and the second oxygen gas pipe may be connected to the oxygen gas tank. According to this configuration, the gas pipe serves as a current passage. Therefore, the wiring can be omitted.

The fuel cell further includes a negative electrode case disposed in contact with the negative electrode and opposed to the positive electrode, and a positive electrode case disposed in contact with the positive electrode and opposed to the negative electrode, The negative electrode and the positive electrode are provided to face each other via a separator, the hydrogen storage chamber is formed in a space between the negative electrode case and the negative electrode, and the second oxygen storage chamber is It may be formed in the space between the positive electrode case and the positive electrode. According to this configuration, the negative electrode case and the positive electrode case respectively function as a negative electrode terminal and a positive electrode terminal.

The battery module according to the present invention comprises a plurality of fuel cells connected in series with one another, a positive electrode terminal in contact with the positive electrode of the fuel cell connected in series, and a negative electrode of the fuel cell connected in series. The positive electrode case of the fuel cell and the negative electrode case of the fuel cell may be arranged to be in contact with each other. According to this configuration, the wiring for connecting the present fuel cell becomes unnecessary. Moreover, it becomes unnecessary to prepare a pressure-resistant container for every battery. One pressure resistant structure may be prepared for each module.

A fuel cell bank according to the present invention includes a metal wire, a structure, a circuit breaker capable of opening and closing, and a bus bar, and one end of the metal wire is attached to the reversible fuel cell module. And the other end of the wire is attached to the structure, whereby the plurality of reversible fuel cell modules can be suspended from the structure, and the positive electrode of the adjacent reversible fuel cell modules is The terminal and the negative electrode terminal may be connected by the bus bar via the circuit breaker.

According to this configuration, the reversible fuel cell module can be suspended from a structure such as a steel tower by a plurality of metal wires. The metal wire may be inserted with a pressure resistant material such as insulator, or may be an insulating belt. A plurality of such reversible fuel cell modules may be arranged, and the positive electrode and the negative electrode may be connected by a conductive bus bar. Circuit breakers may be provided between the bus bars and at the output of the battery system.

According to this suspension structure, first, installation of a large structure becomes possible. Huge structures such as bridges or boilers have a large weight. For this reason, it is difficult to use a freestanding structure that supports weight at the bottom. Therefore, by adopting the hanging structure, it is possible to equalize the stress on each part of the battery and to solve the trouble due to the distortion. And by setting it as a hanging structure, the withstand voltage performance to ground and the withstand voltage between modules can be ensured.

In the fuel cell, the manganese dioxide may function as a catalyst for the charge reaction in the positive electrode, and the hydrogen storage material may function as a catalyst for the charge reaction in the negative electrode.

According to this configuration, at the time of discharge, in each of the negative electrode and the positive electrode, the amount of electricity reduced by the discharge is stored in the hydrogen gas stored in the hydrogen storage chamber and in the first or second oxygen storage chamber and oxygen. It is compensated by the charge by oxygen. Specifically, in the negative electrode, as shown in reaction formula (1) representing a discharge reaction, protons are released from the hydrogen storage alloy (MH) in the charged state. Then, as shown in reaction formula (2), the released protons are compensated by hydrogen gas. Thereby, the charged state of the negative electrode is maintained.

On the other hand, in the positive electrode, manganese oxyhydroxide (MnOOH) is generated by reduction of manganese dioxide (MnO ₂ ) in a charged state, as shown in reaction formula (3) representing a discharge reaction. The manganese oxyhydroxide is oxidized again by oxygen as shown in reaction formula (4). Thereby, the charged state of the positive electrode is maintained. This consumes hydrogen gas and oxygen in each storage chamber.

That is, in the fuel cell, as long as hydrogen gas and oxygen are supplied, electricity lost by discharge is immediately charged by hydrogen gas and oxygen. Therefore, the fuel cell almost always maintains a state near full charge. That is, since the negative electrode maintains the storage state almost always by hydrogen gas, expansion and contraction of the negative electrode volume due to charge and discharge can be suppressed. As a result, the negative electrode has excellent life characteristics. Furthermore, even if the amount of the active material is small, the negative electrode has the above-described action, so that the amount of heavy and expensive hydrogen storage alloy can be reduced. As a result, the weight and cost of the battery can be reduced.

In the fuel cell, the positive electrode may further contain manganese oxide in addition to manganese dioxide. Here, higher order manganese oxide includes Mn ₂ O ₅ , Mn ₂ O ₇ and MnO ₅ . These higher order manganese oxides are temporarily generated on the positive electrode when the positive electrode is overcharged when the electrolyte is hydrolysed.

In the fuel cell, the content of trimanganese tetraoxide (Mn ₃ O ₄ ) contained in the positive electrode is preferably 5% by weight or less based on the weight of the positive electrode. If hydrogen gas and oxygen are supplied almost always, trimanganese tetraoxide will not occur. However, if there is a temporary shortage of hydrogen gas or oxygen, trimanganese tetraoxide can be produced. An amount of more than 5% by weight can be a problem. Depending on the application, this amount may be about 5% by weight or less. Here, the weight of the positive electrode does not include the weight of the current collector.

In the fuel cell, the content of manganese dioxide contained in the positive electrode is preferably in the range of 20 to 99.8% by weight based on the weight of the positive electrode. Here, the weight of the positive electrode does not include the weight of the current collector.

In the fuel cell, the average particle size of manganese dioxide contained in the positive electrode is preferably in the range of 1 to 100 μm. Here, the average particle size is JIS
It is a value represented using the sphere equivalent diameter by the light scattering method of Z 8910.

In the fuel cell, manganese dioxide contained in the positive electrode may be carbon-coated.

Cobalt may be used as a conductive process. However, cobalt is expensive. Usually, carbon is used as a conductive material. However, carbon is oxidized to carbon dioxide gas. For this reason, it becomes difficult to secure the conductivity. The interior of the fuel cell is under a hydrogen atmosphere. For this reason, carbon can maintain conductivity without being oxidized.

Preferably, in the fuel cell, the hydrogen storage material is a hydrogen storage alloy or at least one metal selected from the group consisting of Sc, Ti, V, Cr, Mn, Fe, Co and Ni.

In the fuel cell of the present invention, the separator is preferably a microporous membrane having an average pore size of 0.1 to 10 μm.
In the fuel cell, the negative electrode may include a hydrophilic material disposed on the surface in contact with the separator and a hydrophobic material disposed on the surface in contact with the hydrogen storage chamber. Good.

In the fuel cell, preferably, the electrolyte contains a thickener. And, the thickener may be at least one polyacrylate selected from the group consisting of lithium polyacrylate, sodium polyacrylate and potassium polyacrylate.

In the fuel cell, the open circuit terminal voltage is preferably in the range of 0.8 to 1.48V. That is, the terminal voltage at the time of open circuit of one fuel cell may be in the range of 0.8 to 1.48V. When the positive electrode is manganese oxyhydroxide and the pressure of the electrolyte is 0.1 MPa, the terminal voltage is around 0.8 V. On the other hand, when the positive electrode is manganese dioxide and the electrolytic solution has a high pressure, the terminal voltage is 1.48V. The open circuit terminal voltage is determined by the state of charge of the positive electrode and the pressure of the electrolyte.

The fuel cell further includes an exterior body, a current collector penetrating the positive electrode, the negative electrode, and the separator in the axial direction of the exterior body, and any one of the positive electrode and the negative electrode A first electrode in contact with the inner surface of the outer package and electrically connected to the inner surface, wherein either the positive electrode or the negative electrode is not in contact with the inner surface of the outer package; In the laminated type, the second electrode is in contact with the current collector and is electrically connected to the second electrode, while the first electrode is not in contact with the current collector. It may be a battery.

According to this configuration, the separator holds the electrolytic solution and insulates between the positive and negative electrodes. The separator enables the permeation of ions. The exterior body is metal, and the material may contain iron, aluminum or titanium. The exterior body functions as a terminal of the electrode (first electrode) in contact with the exterior body. Also, the outer package may be a hollow can. The positive and negative electrodes and the separator may be formed in a sheet shape. Each of the electrodes may be stacked in the axial direction of the outer package and stored inside the outer package. The outer diameter dimension (dimension in the direction perpendicular to the thickness direction) of the first electrode may be made slightly larger than the inner diameter of the outer package. The whole or a part of the outer periphery of the first electrode is in contact with the inner surface of the outer package. The first electrode is press-fit into the inside of the package, and the first electrode is connected to the package with low thermal resistance. For this reason, an exterior body cools an electrode effectively.

On the other hand, the outer diameter of the second electrode may be smaller than the inner diameter of the outer package. The second electrode is not in contact with the outer package and is insulated. The outer package may be a can and may include iron, aluminum or titanium.

The heat generated at the first electrode is directly transmitted to the outer package. The thermal gradient (temperature difference) is small because no heat conductor is present along the way. The heat generated at the second electrode is transferred to the first electrode via the separator. The separator with low thermal conductivity interposed in the middle is only one, and does not have a large thermal resistance. For this reason, the thermal gradient can be kept small. Furthermore, the electrode group including the positive and negative electrodes and the separator is pushed into the outer casing with a large pressure in the axial direction. Thereby, the second electrode is strongly pressed to the first electrode. For this reason, the heat transfer of the second electrode is greater. The reason for the large temperature gradient of the wound battery is that there are several layers of separators that are difficult to transfer heat between the outer package and the electrode, and the structure makes it difficult to wind with a large force. As it exists, the heat transfer between the electrodes can not be increased.

As described above, the fuel cell has a small temperature gradient and can reduce the temperature rise at the center of the cell. Therefore, it is not necessary to provide a pipe or the like for flowing the refrigerant inside the battery. Therefore, the temperature rise can be suppressed with a compact structure. Furthermore, the inside of the battery can be easily cooled by cooling the outer package. Therefore, the temperature rise can be effectively suppressed.

The second electrode is in contact with the current collector and electrically connected to the current collector. On the other hand, the first electrode is not in contact with the current collector. The positive and negative electrodes and the separator have holes in their central portions through which the current collector passes. A rod-shaped current collector passes through the hole. The diameter of the hole of the first electrode is larger than the outer diameter of the rod-like current collector. Therefore, the first electrode does not contact the current collector. The diameter of the hole of the second electrode is smaller than the outer diameter of the rod-like current collector. Thus, the second electrode is electrically connected to the current collector in contact therewith. The material of the current collector contains a metal. Thus, the current collector functions as a terminal of the second electrode. Moreover, as a material of a collector, iron, aluminum, or what plated these to nickel is included.

In the fuel cell of the present invention, the outer package may have a cylindrical metal body. The exterior body may be a cylinder with a lid and a bottom. The exterior body may have a cylindrical metal body and two lids covering an axial opening of the body. In this case, the current collector may penetrate the lid.

According to this configuration, the current collector may penetrate through the lid and be supported by the both lids. The exterior body may be provided with a lid at the openings at both ends of the circular pipe (pipe). In this case, the exterior body has an enclosed space formed by the circular pipe and the lid in its inside. Then, an electrode group including positive and negative electrodes and a separator is housed in the sealed space. The lid may be made of metal. The outer diameter of the first electrode may be slightly larger than the inner diameter of the outer package. The outer diameter of the second electrode is smaller than the inner diameter of the outer package.

In the fuel cell, the side portion of the exterior body may have a substantially cylindrical shape, and the exterior body may have a bulging portion that bulges in the axial direction at both ends in the axial direction.

According to this configuration, the exterior body has the side portion having the bulging portion formed at one end, and the bulging portion separate from the side portion attached to the opening at the other end of the side portion. May be Alternatively, the outer package may have a substantially cylindrical side portion open at both axial ends, and a bulging portion attached to the both ends.
In any case, the outer package has a sealed space surrounded by the bulging portion and the side portion. The positive and negative electrodes and the separator are housed in the sealed space.

The outer diameter of the first electrode is slightly larger than the inner diameter of the outer package. The outer diameter of the second electrode is smaller than the inner diameter of the outer package. With such a configuration, the heat generated at the first electrode is directly transmitted to the outer package. The heat generated by the second electrode is transferred to the first electrode through one separator. As described above, in the fuel cell, the heat generated at the electrode is efficiently transmitted to the outer package. For this reason, it is possible to reduce the temperature gradient and to reduce the temperature rise at the central portion of the laminated battery.

The laminated battery according to the present invention may further include a hydrogen storage chamber provided in an inner space of the dome-like bulging portion of the outer package and storing hydrogen gas generated at the negative electrode.

As described above, in the fuel cell and the fuel cell system using the same, manganese dioxide is adopted as the positive electrode active material. Furthermore, at the time of overcharge, hydrogen gas and oxygen gas generated from the negative electrode and the positive electrode are stored as hydrogen gas and oxygen gas or oxygen dissolved in the electrolyte, respectively. Thus, chemical energy of hydrogen and oxygen can be reconverted to electrical energy and used. Therefore, energy utilization efficiency and energy density can be dramatically improved. In addition, there is no need to separately provide equipment for supplying hydrogen gas and oxygen gas.

Furthermore, electrical energy is output through the electrode reaction of the secondary battery. Therefore, the ability to follow load fluctuations is significantly improved compared to conventional fuel cells. In addition, trimanganese tetraoxide which is an irreversible substance is not generated in the charge-discharge reaction process at the positive electrode. Thus, the life characteristics can be significantly improved.
In addition, the fuel cell suppresses temperature rise inside the cell and does not require extra space for cooling.

FIG. 1 is a cross-sectional view schematically showing a structure of a reversible fuel cell according to a first embodiment of the present invention, in which oxygen is dissolved in an electrolytic solution. It is a modification of the reversible fuel cell of 1st Embodiment of this invention. FIG. 5 is a cross-sectional view showing a structure of a fuel cell according to a second embodiment of the present invention. It is drawing which shows the DD cross section of FIG. 2A. It is sectional drawing which shows the structure of the 2nd modification of the fuel cell which concerns on 2nd Embodiment of this invention. It is a figure which shows the structure of the battery module which consists of a fuel cell which concerns on the modification shown in FIG. 3, and the part enclosed with circular shape in a figure is a principal part enlarged view. It is a front view of the current collection board in FIG. 4A. It is sectional drawing which shows the structure of the 3rd modification of the fuel cell which concerns on 2nd Embodiment of this invention. FIG. 5A shows a modification of the shape of the connection portion of the fuel cell. FIG. 5A shows another modification of the shape of the connection portion of the fuel cell. It is drawing which shows the structure of the battery bank which consists of a fuel cell which concerns on the modification shown to FIG. 5C. It is sectional drawing which shows the structure when the fuel cell which concerns on 3rd Embodiment of this invention is comprised as a unit cell. It is an assembly sectional view which shows the structure when the unit cell of FIG. 7A is assembled and modularized. It is drawing which shows the structure of the battery bank formed by connecting multiple fuel cells shown to FIG. 7B. It is a connection diagram of the fuel cell in the battery bank of FIG. 8A. It is a partially broken side view showing a structure of a reversible fuel cell according to a fourth embodiment of the present invention. It is an AA cross section of FIG. 9A. It is a cross-sectional view which shows typically the structure of the electrode part of the reversible fuel cell which concerns on 4th Embodiment of this invention. It is a systematic diagram for demonstrating the electric power generation process using the reversible fuel cell which concerns on 4th Embodiment of this invention. It is a cross-sectional view which shows the structure of the reversible fuel cell which concerns on 5th Embodiment of this invention. It is a BB sectional view of FIG. It is CC sectional drawing of FIG. It is a systematic diagram which shows the relationship between the reversible fuel cell which concerns on 5th Embodiment of this invention, and an external system. It is a systematic diagram for demonstrating the electrolyte solution processing process using the reversible fuel cell which concerns on 5th Embodiment of this invention. It is a schematic block diagram of a cylindrical stack type fuel cell concerning a 6th embodiment of the present invention, and is a figure showing an axial direction section. It is a schematic block diagram of the modification of the cylinder lamination type fuel cell concerning a 6th embodiment of the present invention, and is an axial sectional view. It is a schematic block diagram which shows the donut battery which concerns on 7th Embodiment of this invention. It is a graph which shows the discharge characteristic (in the case of one electron reaction) of a manganese dioxide positive electrode. It is a graph which shows the discharge characteristic (in the case of two electron reaction) of a manganese dioxide positive electrode. It is a graph which shows the result of a XRD measurement, and this measurement is measurement which investigates the change according to the difference in the depth of discharge in the composition in a manganese dioxide positive electrode. It is a graph which shows the experimental result when charging a manganese dioxide electrode with oxygen gas. It is a graph which shows the other experimental result when charging a manganese dioxide electrode with oxygen gas. It is a characteristic graph which shows typically the relationship between the composition of a positive electrode, and terminal voltage. It is the graph which calculated | required the influence by the pressure of free energy by thermodynamic calculation.

Hereinafter, embodiments according to the present invention will be described with reference to the drawings. The voltage of one fuel cell is as low as several volts or less. For this reason, when a high voltage is required, a plurality of fuel cells are connected in series with each other and modularized for use. Note that a system including a combination of a fuel cell and other equipment is referred to as a fuel cell system.

Before describing the individual embodiments, matters common to these embodiments will be described. That is, first, the negative electrode, the positive electrode, the electrolytic solution, and the separator will be described. Thereafter, specific embodiments will be described.

<Negative electrode>
The negative electrode used in the reversible fuel cell of the present invention contains a hydrogen storage material. The hydrogen storage material may be any material that can store and release hydrogen, and is not limited to a hydrogen storage alloy. The hydrogen storage material may be a material that adsorbs hydrogen on the catalyst surface, such as a hydrogenation catalyst, as well as a hydrogen storage alloy. The hydrogenation catalyst includes, for example, Ni, Fe, Ti, Al, Ga, As, Se, Mg, Sb, Te, Tl, Pd, Sc, Bi, Ca, V, Cr, Mn, Co, Cu, Zn and Ru And a metal or alloy containing one or more selected from the group consisting of The hydrogen storage material may be a metal or an alloy containing one or more selected from Ni, Fe, Ti, Pd, Sc, V, Mn and Co. These metals or alloys have alkali resistance and have an excellent hydrogen dissociation and adsorption rate.

The hydrogen storage material may be a hydrogen storage alloy from the viewpoint of hydrogen storage capacity. The material of the hydrogen storage alloy may be a commonly used one such as, for example, Mm (misch metal), Ni, Co, Mn or an AB5 type alloy based on Al. In addition, this material may be an AB2 type alloy containing a nickel-based transition metal and a rare earth metal having a higher content than that. Furthermore, this material may be an AB3 type alloy, an A2B7 type alloy, a Ti-Fe based alloy, a V based alloy, an Mg based alloy, or a Pd based alloy.

The average particle diameter of the hydrogen storage alloy contained in the negative electrode may be in the range of 5 to 100 μm, and more preferably in the range of 10 to 50 μm. When the average particle size of the hydrogen storage alloy is less than 5 μm, the specific surface area of the alloy particles is increased. For this reason, the particle surface of the hydrogen storage alloy is easily corroded by alkali. Such corrosion causes a decrease in hydrogen storage capacity and a decrease in utilization of the hydrogen storage alloy in the negative electrode. Furthermore, the conductivity also deteriorates, and the discharge characteristics of the battery are degraded. When the average particle size exceeds 100 μm, the specific surface area of the particles decreases. For this reason, the hydrogen storage and release reaction in the negative electrode is delayed. As a result, the discharge characteristics of the battery deteriorate. In the first embodiment to be described later, the average particle diameter of the hydrogen storage alloy contained in the negative electrode is 20 μm.

Generally, on the particle surface of the hydrogen storage alloy, there is an oxide film which causes a decrease in capacity, and / or an impurity which does not contribute to the charge / discharge reaction. For this reason, the hydrogen storage alloy may be subjected to activation treatment. The method of this activation treatment includes, for example, a surface modification treatment method including acid treatment of a hydrogen storage alloy and removal of an oxide film present on the surface of alloy particles. Moreover, the method of this activation treatment includes a surface modification treatment method using an alkali treatment. In addition, the method of using an acid treatment includes a water washing process as a post-process. This water washing step is a step for removing the treatment liquid adhering to the hydrogen storage alloy. On the other hand, the surface modification treatment method using the alkali treatment is a surface modification treatment method in which the number of steps is small because it does not include the water washing step. The use of a high-temperature aqueous alkaline solution improves the effect of the treatment. In the first embodiment described later, a surface modification treatment method using an alkali treatment was adopted.

The hydrogen storage alloy may be a hydrogen storage alloy represented by the general composition formula RE _(1-x) Mg _x Ni _y Al _z . When using the hydrogen storage alloy of the above composition formula, a better negative electrode can be obtained than when using the conventional AB5 system. This negative electrode has low self-discharge, high capacity retention rate, high discharge voltage, and good high-rate discharge characteristics. Furthermore, the negative electrode does not require activation by the acid treatment or the alkali treatment as described above. The crystal structure of the hydrogen storage alloy of the above composition has a superlattice phase. Here, in the formula, RE is at least one or more elements selected from the group consisting of La, Ce, Pr and Nd. The subscripts x, y and z are in the ranges shown by 0.01 ≦ x ≦ 0.2, 4.0 ≦ y ≦ 4.9, and 0.05 ≦ z ≦ 0.3, respectively.

The weight ratio of the hydrogen storage alloy in the negative electrode is in the range of 80 to 99.8%, assuming that the total of the hydrogen storage alloy powder, the binder, and the conductive additive added as needed is 100% by weight. It may be within.

The negative electrode includes a paste-type negative electrode and a non-paste-type negative electrode. In the production of a paste-type negative electrode, a paste is formed by mixing a hydrogen storage alloy powder, a binder, and a conductive powder which is optionally added. The paste is applied and filled to a current collector and dried. Thereafter, the negative electrode is manufactured by rolling the current collector with a roller press or the like. In the production of the non-pasted negative electrode, the hydrogen storage alloy powder, the binder, and the conductive powder to be added as needed are stirred. The powder obtained by stirring is spread on a current collector. Thereafter, current collector rolling with a roller press or the like produces a negative electrode.

Examples of the binder used for the negative electrode include sodium polyacrylate, methylcellulose, carboxymethylcellulose (CMC), polyvinyl alcohol (PVA), polyvinyl butyral (PVB), ethylene-vinyl alcohol, ethylene-vinyl acetate copolymer (EVA) And polyethylene (PE), polypropylene (PP), styrene butadiene rubber (SBR), styrene-ethylene-butylene-styrene copolymer (SEBS), xanthan gum, guar gum, and peptin. Assuming that the total of the hydrogen storage alloy powder, the binder, and the conductive additive added as needed is 100% by weight, the weight ratio of the binder blended to the negative electrode is 0.1 to 10 weight It is preferable to mix | blend in%.

The conductive aid for the negative electrode may be any powder having conductivity. The conductive aid may be, for example, carbon powder such as graphite powder, acetylene black and ketjen black. In addition, the conductive aid may be metal powder such as nickel powder, copper powder and cobalt powder. Assuming that the total of the hydrogen storage alloy powder, the binder, and the conductive additive added as needed is 100% by weight, the weight ratio of the conductive additive to the negative electrode is 0.1 to 10 weight It is preferable to mix | blend in% range.

The current collector for the negative electrode may be, for example, a two-dimensional substrate such as a punching metal, an expanded metal, and a wire mesh. Further, the current collector for the negative electrode may be a three-dimensional substrate such as a foamed nickel substrate, a net-like sintered fiber substrate, or a felt-plated substrate which is a non-woven fabric plated with metal. However, when producing a non-paste type hydrogen storage alloy electrode, a mixture containing hydrogen storage alloy powder is dispersed. Therefore, a two-dimensional substrate may be used as a conductive substrate.

<Positive electrode>
The positive electrode contains manganese dioxide as an active material. The average particle size of the positive electrode active material may be in the range of 1 to 100 μm, preferably in the range of 10 to 50 μm. When the average particle diameter of the positive electrode active material is less than 1 μm, the specific surface area of the positive electrode active material particles is increased. For this reason, the amount of the binder for binding the particles to the particles increases. This causes a decrease in the active material content ratio of the positive electrode composition and a decrease in positive electrode capacity. Furthermore, the conductivity also deteriorates, and the discharge characteristics of the battery are degraded. When the average particle size exceeds 100 μm, the rate of charge due to the contact between the oxygen-containing electrolyte and the positive electrode active material tends to decrease due to the diffusion limitation of oxygen. In addition, the specific surface area of the particles is reduced. This inhibits the charge / discharge reaction of the positive electrode and deteriorates the discharge characteristics of the battery. In addition, the energy density is lowered because the electrode is not compact. In the first embodiment described later, the positive electrode active material is manganese dioxide having an average particle diameter of 10 μm.

Assuming that the total of the positive electrode active material, the binder, and the conductive additive added as needed is 100% by weight, the weight ratio of the positive electrode active material blended in the positive electrode is 20 to 99.8% by weight It may be in the range of When the weight ratio of the positive electrode active material is less than 20% by weight, trimanganese tetraoxide, which is an irreversible component, is likely to be generated on the positive electrode during rapid discharge. On the other hand, when the weight ratio of the positive electrode active material exceeds 99.8% by weight, it is difficult to manufacture an electrode.

The above-mentioned positive electrode active material is usually a composite of manganese dioxide particles and a conductive material covering the surface thereof. The material having conductivity may be a metal material, a carbon material, a conductive ceramic, or a conductive polymer. Also, this material may be a carbon material from the viewpoint of conductivity and alkali resistance. The carbon material is not particularly limited as long as it has conductivity. Carbon materials include, for example, ketjen black (KB), acetylene black (AB), furnace black, graphite, graphene, fibrous carbon, glass carbon, and activated carbon. The specific surface area of the above KB and AB is preferably 50 to 3000 m ² / g.

In general, when carbon is used as a conductive material, carbon is oxidized to carbon dioxide and can not maintain conductivity. However, the inside of the fuel cell is under a hydrogen atmosphere. For this reason, carbon is not oxidized and can maintain conductivity.

The thickness of the carbon coating may be, for example, in the range of 0.01 to 5 μm. If the thickness of the carbon coating film is less than 0.01 μm, the improvement of the conductivity is insufficient. Therefore, current concentration on the surface of the active material is likely to occur at the time of charge and discharge. For this reason, it becomes difficult to improve the high rate charge and discharge characteristics. On the other hand, when the thickness of the carbon coating film exceeds 5 μm, the electrode capacity density may be lowered. The coverage of the carbon coating film is preferably 0.1 to 20% by weight with respect to 100% by weight of the positive electrode active material. If the coverage is less than 0.1% by weight, the conductivity improvement is insufficient. Therefore, current concentration on the surface of the active material is likely to occur at the time of charge and discharge. For this reason, it becomes difficult to improve the high rate charge and discharge characteristics. On the other hand, if the coverage exceeds 20% by weight, there arises a problem that the electrode capacity density is lowered. The preferred lower limit of the coverage is 0.2% by weight, and the more preferred lower limit is 0.5% by weight. Moreover, the preferable upper limit of a coverage is 5 weight%, and a more preferable upper limit is 2 weight%.

The conductive treatment method may be any method that can form a carbon-coated film on the surface of the positive electrode active material particles. This method includes, for example, known techniques such as sputtering, vapor deposition, mechanical milling, heating, electroless plating and spray drying. Among them, in the mechanical milling method and the heating method, a carbon coating excellent in uniformity can be formed by a simple method without using a large-scale apparatus. For example, mechanical milling involves applying mechanical energy to powder particles and causing strong surface fusion among particles by mechanochemical reaction on the particle surface. This method is a technique for obtaining a fine particle composite material, and is a method of coating carbon on the particle surface of the active material powder. Mechanical milling may be performed under a hydrogen atmosphere. Under a hydrogen atmosphere, it becomes easy to form a carbon coating film on the surface of the positive electrode active material particles.

The heating method includes mixing the positive electrode active material and the carbon precursor, and heat treatment such as heating in a non-oxidizing atmosphere. This forms a coating of carbon. In the heat treatment, for example, a carbon precursor gas such as butane gas is held in a non-oxidizing gas atmosphere in a heat treatment furnace such as a rotary kiln maintained at 400 to 2000 ° C. for 0.1 to 5 hours. When the heat treatment temperature is less than 400 ° C., it is difficult to realize carbonization, so the conductivity improvement effect of the positive electrode active material may be reduced. On the other hand, when the heat treatment temperature exceeds 2000 ° C., the apparatus becomes large. Therefore, not only the cost increases, but also the active material may be damaged. In addition, if the heat treatment time is less than 0.1 hours, it may be difficult to uniformly coat carbon. On the other hand, when the heat treatment time exceeds 5 hours, the heat source is driven for a long time. Therefore, the cost may be high. The heat treatment atmosphere is not limited to butane gas, and may be methane gas, ethane gas, propane gas, or a mixed gas thereof. The heat treatment atmosphere may be, for example, a carbon precursor gas diluted with nitrogen, helium, neon, argon, hydrogen, carbon dioxide, or a mixture thereof.

In the production of a positive electrode, a paste is formed by mixing the above-mentioned positive electrode active material powder, a binder, and a conductive powder which is optionally added. The paste is applied and filled to a current collector and dried. Thereafter, the current collector is rolled by a roller press or the like to produce a positive electrode.

As a binder for positive electrodes, for example, sodium polyacrylate, polytetrafluoroethylene (PTFE), methylcellulose, carboxymethylcellulose (CMC), polyvinyl alcohol (PVA), polyvinyl butyral (PVB), ethylene-vinyl alcohol, ethylene acetate And vinyl copolymers (EVA), polyethylene (PE), polypropylene (PP), and styrene-ethylene-butylene-styrene copolymers (SEBS). Among these, polytetrafluoroethylene (PTFE) is fiberized by stirring. For this reason, it is possible to fix the positive electrode active material powder and the conductive auxiliary agent added as needed in a mesh form. The weight ratio of the binder blended in the positive electrode is 0.1 to 20 wt% when the total of the positive electrode active material powder, the binder and the conductive additive added as needed is 100 wt% It may be in the range of%.

The positive electrode conductive auxiliary agent may be any powder that maintains conductivity without being oxidized at the positive electrode potential. The conductive aid may be, for example, powders of carbon, nickel, cobalt hydroxide (Co (OH) ₂ ), cobalt monoxide (CoO), and cobalt. The weight ratio of the conductive aid blended into the positive electrode is 0.1 to 60% when the total of the positive electrode active material powder, the binder, and the conductive aid optionally added is 100% by weight It is preferable to mix | blend in% range.

The positive electrode current collector may be, for example, a two-dimensional substrate such as a metal foil, a punching metal, an expanded metal, and a wire mesh. The positive electrode current collector may be a three-dimensional substrate such as a foam metal substrate, a net-like sintered fiber substrate, or a felt-plated substrate which is a non-woven fabric plated with metal. When the positive electrode current collector is a punched metal, a three-dimensional substrate, or a foam metal substrate, sufficient current collection can be obtained, and a positive electrode having a structure in which the oxygen-dissolved electrolyte can easily be immersed can be obtained.

Charging the positive electrode can be realized by bringing the positive electrode into contact with the oxygen-dissolved electrolytic solution. If the thickness of the positive electrode is too large, the oxidation rate (charging rate) of the positive electrode tends to be oxygen diffusion limited and decrease. Therefore, the thickness of the positive electrode may differ depending on the concentration of oxygen dissolved in the electrolyte solution, but may be in the range of 50 to 2000 μm. When the thickness of the positive electrode is less than 50 μm, the positive electrode capacity decreases. When the thickness of the positive electrode exceeds 2000 μm, the diffusion of oxygen becomes insufficient, and thus there is a possibility that a portion which is not oxidized is left on the positive electrode.

<Electrolyte solution>
The electrolyte used in the present invention is preferably an oxygen-dissolved electrolyte in which oxygen is dissolved in the electrolyte in the range of 0.02 to 200 g / L. When the concentration of oxygen dissolved in the electrolytic solution is less than 0.1 g / L, it takes time to oxidize the positive electrode active material because the concentration of oxygen is low. When the oxygen concentration exceeds 200 g / L, the corrosiveness of the electrolytic solution is enhanced, and thus the negative electrode is damaged.

The adjustment of the dissolved oxygen concentration in the electrolyte may be performed by adding hydrogen peroxide to the electrolyte to increase the concentration of dissolved oxygen. Alternatively, in this adjustment, the dissolved oxygen concentration may be increased by raising the fluid pressure of the electrolyte according to Henry's law. For example, if oxygen is sealed at a hydraulic pressure of 100 MPa, about 26 g of oxygen can be dissolved in one liter of electrolyte.

However, in the method of increasing the concentration of dissolved oxygen by adding hydrogen peroxide to the electrolyte, high concentration of hydrogen peroxide is used. High concentrations of hydrogen peroxide are highly corrosive and therefore easily form peroxides when in contact with combustibles. For this reason, the dissolved oxygen concentration may be adjusted by increasing the liquid pressure of the electrolyte. In that case, the liquid pressure of the electrolyte is preferably 0.1 MPa to 10 GPa. Not only it is possible to raise the dissolved oxygen concentration, but also the oxygen gas generated at the time of overcharging can be dissolved in the electrolyte by using the high pressure or ultra high pressure electrolyte. In addition, it is possible to increase the operating voltage of the battery.

The above oxygen-dissolved electrolyte can oxidize (charge) the positive electrode active material by contacting with the positive electrode. When the oxygen-dissolved electrolyte is at a high pressure or an ultrahigh pressure, oxygen gas generated during charging is dissolved in the electrolyte. For this reason, while the space which stores oxygen gas becomes unnecessary, the dissolved oxygen concentration in electrolyte solution can be made high.

With regard to the above-described hydraulic pressure range of the electrolytic solution, when the hydraulic pressure of the electrolytic solution is less than 0.1 MPa, it becomes difficult to increase the concentration of dissolved oxygen in the electrolytic solution. For this reason, it takes time to oxidize the positive electrode active material, and it becomes difficult to effectively dissolve oxygen gas generated during charging in the electrolytic solution. It is substantially difficult to make the liquid pressure of the electrolyte ultrahigh pressure exceeding 10 GPa.

The electrolytic solution used in the present invention may be a commonly used alkaline aqueous solution. From the viewpoint of suppressing the elution of the alloy components into the electrolytic solution, for example, an alkaline substance such as lithium hydroxide (LiOH), sodium hydroxide (NaOH), or potassium hydroxide (KOH) may be used alone. And two or more may be used in combination. The concentration of the alkaline substance in these electrolytic solutions is preferably 1 to 10 mol / L, and more preferably 3 to 8 mol / L.

A thickener may be dissolved in the electrolytic solution. Since the electrolyte in which the thickener is dissolved has a high viscosity, the oxygen diffusion rate is slow. By reducing the oxygen diffusion rate, the negative electrode and oxygen are less likely to be in contact with each other, so the self-discharge reaction of the negative electrode can be reduced. In addition, since the viscosity of the electrolytic solution is also increased, the liquid leakage resistance is also improved. As a material of the thickener, any material may be used as long as it has water absorbency and raises the viscosity of the electrolytic solution. This material includes, for example, resins such as polyacrylate, polystyrene sulfonate, polyvinyl sulfonate, gelatin, starch, polyvinyl alcohol (PVA) and fluoroplastics.

The above-mentioned thickener may be a polyacrylate from the viewpoints of high water absorption, high water retention, high gelling power, and alkali resistance. Specific examples of the polyacrylate include lithium polyacrylate, sodium polyacrylate, potassium polyacrylate and the like. These may be used singly or in combination of two or more.

The weight ratio of the thickener is preferably in the range of 0.1 to 30 wt%, more preferably 1 to 20 wt%, based on 100 wt% of the total of the electrolytic solution and the thickener. When the weight ratio of the thickener exceeds 30% by weight, the viscosity of the electrolyte is too high, so that the active material and the electrolyte do not easily come in contact with each other. Therefore, not only the proton conductivity is lowered, but also the electrolyte does not easily circulate. If the weight ratio of the thickener is less than 0.1% by weight, sufficient effect by the addition of the thickener can not be obtained.

<Separator>
The separator used in the present invention is preferably a separator that transmits protons but is difficult to pass oxygen gas. Examples of the material of the separator include resins such as polyethylene (PE), polypropylene (PP), polybutene (PB), polyolefins such as ethylene propylene rubber, polyphenylene sulfite, polyfluoroethylene, polyamide, polyimide, polyamide imide, and Nafion. Including. These may be used singly or in combination of two or more.

The separator may contain inorganic particles in addition to the above resin. The weight ratio of the inorganic particles is preferably in the range of 10 to 80% by weight, based on 100% by weight of the total of the resin and the inorganic particles. The inorganic particles may be oxide ceramics such as alumina, titania, zirconia, magnesia, ceria, yttria and iron oxide. Furthermore, the inorganic particles may be nitride-based ceramics such as titanium nitride and boron nitride. Furthermore, the inorganic particles are ceramics such as aluminum sulfate, aluminum hydroxide, potassium titanate, talc, kaolin clay, kaolinite, halloysite, pyrophyllite, montmorillonite, sericite, mica, amesite, bentonite, zeolite, etc. It may also be glass fiber or the like. One of these may be used alone, or two or more of these may be used in combination. Inclusion of inorganic particles in the resin not only improves the immersion and electrochemical stability but also suppresses the meltdown of the separator due to heat.

The separator may be, for example, a fibrous assembly such as a woven fabric and a non-woven fabric, or may be in the form of a film such as a microporous membrane. Also, the separator may be in the form of a sheet in which these are laminated in multiple layers.

When the separator is a microporous membrane, the size of the pores is preferably in the range of 0.1 to 10 μm. In this embodiment, it is preferable to use a microporous membrane made of polypropylene (thickness 20 μm, average pore diameter 0.2 μm) as a separator. The use of a separator having a thickness of 20 μm and an average pore diameter of 20 μm increases the probability of shorting. The method of determining the average pore diameter of the separator includes taking a photograph with a magnification of 5000 times with a scanning electron microscope (SEM), and extracting 30 points of the pore diameter of the outermost surface only. The separator may be formed as a water-sealed separator wetted with an electrolytic solution or water. Water-sealed separators have high gas impermeability. By using a water-sealed separator, hydrogen gas and oxygen gas can be more reliably prevented from passing through the separator and coming into contact with each other and reacting with each other.

Hereinafter, the present invention will be more specifically described based on more detailed embodiments. The present invention is not limited to these embodiments.

First Embodiment
FIGS. 1A and 1B are cross-sectional views schematically showing the structure of a reversible fuel cell C1 (hereinafter simply referred to as a cell C1) according to the first embodiment, which has a basic configuration of a fuel cell. The battery C1 converts chemical energy of hydrogen and oxygen into electric energy and uses it. Furthermore, the battery C1 can convert electrical energy into chemical energy and store it. The battery C1 includes, as main components, a negative electrode 4, a positive electrode 6, a negative electrode case 1, and a positive electrode case 2. The negative electrode 4 and the positive electrode 6 face each other via the separator 5. The negative electrode case 1 has a hydrogen storage chamber 8. The positive electrode case 2 has an oxygen storage chamber 7.

The negative electrode active material of the negative electrode 4 includes a hydrogen storage alloy represented by La _0.54 Pr _0.18 Nd _0.18 Mg _0.1 Ni _4.5 Al _0.1 . In the manufacture of the negative electrode 4, a slurry-like mixture is prepared such that the weight ratio thereof is 97: 1: 1: 1 using AB, CMC and SBR. Further, the slurry-like mixture is applied to a punching metal in which a steel material is plated with nickel.

The positive electrode active material of the positive electrode 6 contains manganese dioxide. In the production of the positive electrode 6, AB, CMC and PTFE are used to prepare a slurry-like mixture having a weight ratio of 97: 0.5: 2: 0.5. Further, the slurry-like mixture is filled in the foamed nickel. In addition, manganese dioxide of a positive electrode active material is previously charged in a rotary kiln (700 ° C., 1 hour, butane gas atmosphere). Thereby, a conductive thin film is formed on manganese dioxide. The coverage of the conductive film (carbon coating film) can be obtained by heat-treating the obtained manganese dioxide in an oxygen atmosphere, and calculating the weight difference before and after the heat treatment of manganese dioxide. The coverage of the carbon coating film is 0.9% by weight with respect to 100% by weight of manganese dioxide.

The separator 5 includes a microporous film made of polypropylene (thickness 20 μm, average pore diameter 0.2 μm). The electrolytic solution 3 is held in the separator 5.

The electrolytic solution 3 contains a 6 mol / L potassium hydroxide aqueous solution. Furthermore, the electrolyte solution 3 contains 5% by weight of sodium polyacrylate as a thickener.

As shown in FIG. 1A, the negative electrode 4 and the positive electrode 6 have a structure in which the separator 5 is sandwiched. The surface of the negative electrode 4 not in contact with the separator 5 is airtightly covered by a box-shaped negative electrode case 1. An inner space formed by the negative electrode 4 and the negative electrode case 1 constitutes a hydrogen storage chamber 8. The hydrogen storage chamber 8 directly stores the hydrogen gas generated at the negative electrode without requiring an additional member such as a pressure booster. Further, the hydrogen storage chamber 8 is provided in contact with the negative electrode 4. Therefore, it is possible to supply hydrogen gas directly to the negative electrode 4 without interposing the communication passage or the additional member.

The surface of the positive electrode 6 not in contact with the separator 5 is covered by a box-shaped positive electrode case 2. An inner space formed by the positive electrode 6 and the positive electrode case 2 constitutes an oxygen storage chamber 7 for storing oxygen. The oxygen storage chamber 7 stores the electrolytic solution 3 having a high hydraulic pressure (for example, 10 MPa). Therefore, the oxygen gas generated at the positive electrode 6 is dissolved in the electrolytic solution and stored as dissolved oxygen in the oxygen storage chamber 7. That is, the oxygen gas generated at the positive electrode 6 is directly stored in the oxygen storage chamber 7 without requiring an additional member such as a pressure booster. Further, the oxygen storage chamber 7 is provided in contact with the positive electrode 6. Therefore, it is possible to supply oxygen directly to the positive electrode 6 without interposing the communication passage or the additional member.

The hydrogen storage chamber 8 and the oxygen storage chamber 7 are divided by the movable wall member 9. The wall member 9 includes the positive electrode 4 and the negative electrode 6, and the separator 5. The wall member 9 may be a member having flexibility.

The surface of the negative electrode 4 in contact with the hydrogen storage chamber 8 contains a large amount of hydrophobic material. Thereby, the hydrogen storage alloy of the negative electrode 4 can contact with hydrogen gas without getting wet. Further, the surface of the negative electrode 4 in contact with the separator 5 has hydrophilicity. Thus, this surface prevents hydrogen gas from passing through the negative electrode 4. This surface is kept almost always wet with the electrolyte. Thereby, the ion conductivity of the negative electrode 4 is secured.

The operation of the battery C1 configured as described above is shown below. The battery C1 includes the positive electrode 6 having a positive electrode active material and the negative electrode 4 having a negative electrode active material. Therefore, at the time of initial charge, it is stored as electrical energy in the electrode of the battery C1. In the present specification, for the convenience of description, charging beyond the electric capacity of the active material in the electrode may be referred to as overcharging. In the overcharged state, oxygen gas and hydrogen gas are generated.

After the electrodes of the battery C1 are initially charged, when current supply is further continued, hydrogen gas is generated from the negative electrode 4 and oxygen gas is generated from the positive electrode 6. Hydrogen gas is stored in the hydrogen storage chamber 8. As charging proceeds, the pressure in the hydrogen storage chamber 8 rises. Therefore, the hydrogen storage chamber 8 expands under the influence of the hydrogen gas pressure. The hydrogen storage chamber 8 and the oxygen storage chamber 7 are separated by a movable wall member 9. Therefore, when the hydrogen storage chamber 8 expands, the wall member 9 is displaced or deformed, and the electrolyte 3 in the oxygen storage chamber 7 is compressed. The deformation of the wall member 9 continues until the pressures of the hydrogen storage chamber 8 and the oxygen storage chamber 7 are substantially equalized. Thus, the electrolyte 3 in the oxygen storage chamber 7 has a high pressure. As a result, the oxygen gas generated from the positive electrode 6 dissolves in the electrolytic solution 3. Thereby, the electrolyte solution 3 becomes an oxygen-dissolved electrolyte solution.

The electrolyte 3 of the present fuel cell can have a hydraulic pressure in the range of 0.1 MPa to 10 GPa. In the battery C1 of the present embodiment, the electrolytic solution 3 has a fluid pressure in the range of 1 MPa to 10 MPa.

During the discharge of the battery C1, a discharge reaction as a secondary battery occurs between the negative electrode 4 and the positive electrode 6. Thereby, current flows to the load. At this time, the amounts of electricity of the negative electrode 4 and the positive electrode 6 decrease due to discharge. The reduced amount of electricity of the negative electrode 4 and the positive electrode 6 is compensated by charging with hydrogen gas and oxygen stored in the hydrogen storage chamber 8 and the oxygen storage chamber 7. That is, in the negative electrode 4, the reaction represented by the chemical formula (2) occurs. As a result, hydrogen gas compensates for the amount of protons released from the charged hydrogen storage alloy (MH). Thereby, the charged state of the negative electrode is maintained. On the other hand, at the positive electrode 6, the reaction represented by the chemical formula (4) occurs. As a result, manganese oxyhydroxide produced by reduction of charged manganese dioxide (MnO ₂ ) is oxidized again by oxygen. Thereby, the charged state of the positive electrode is maintained. That is, manganese dioxide functions as a catalyst for the reaction at the positive electrode. On the other hand, the hydrogen storage alloy functions as a catalyst for the reaction in the negative electrode.

The manganese dioxide in the positive electrode 6 is reduced to manganese oxyhydroxide when discharged. Manganese oxyhydroxide is oxidized by oxygen in the electrolyte to return to manganese dioxide. Therefore, manganese dioxide is almost always present in the positive electrode 6. Therefore, the SOC of the positive electrode (state of charge; State
of Charge) is maintained at almost 100%. Further, the positive electrode 6 faces the oxygen storage chamber 7 and is always in contact with oxygen. Therefore, the discharge reaction of manganese dioxide does not proceed until manganese dioxide becomes manganese hydroxide, and trivalent manganese trioxide (Mn ₃ O ₄ ), which is an irreversible component, is not generated. Therefore, the deterioration of the positive electrode 6 is suppressed, and its life characteristics are significantly improved.

The hydrogen storage alloy in the negative electrode 4 releases protons at the time of discharge. For this reason, the amount of hydrogen of the hydrogen storage alloy decreases. However, the negative electrode 4 faces the hydrogen storage chamber 8 and is always in contact with hydrogen gas. For this reason, protons of the amount released from the hydrogen storage alloy (MH) are compensated by hydrogen gas. As a result, the hydrogen storage alloy that has released hydrogen returns to the state where it stores hydrogen. Therefore, in the negative electrode 4, an alloy that occludes hydrogen almost always exists. As a result, the SOC of the negative electrode is maintained at approximately 100%.

FIG. 22 is a graph schematically showing the relationship between the potential (vertical axis) of the manganese dioxide electrode and the SOC (horizontal axis). As shown in FIG. 22, the potential of the battery C1 is near the high potential indicated by manganese dioxide (MnO ₂ ). That is, the battery C1 maintains a high discharge potential.

The battery C1 according to the present embodiment stores electric energy supplied at the time of overcharge in the

storage rooms

7 and 8 as chemical energy. Then, the battery C1 can convert the stored chemical energy into electrical energy and use it. Therefore, unlike the conventional secondary battery, the electric capacity of the battery C1 is not limited by the amount of the active material. Therefore, the hydrogen gas storage amount and the dissolved oxygen amount per volume can be increased by enhancing the pressure resistance performance and the sealing performance of

storage chambers

7 and 8 and battery C1. As a result, the energy density of the battery C1 can be significantly improved (for example, several tens of times) as compared with the conventional secondary battery. Furthermore, hydrogen gas generated at the negative electrode 4 or oxygen gas generated at the positive electrode 6 is directly stored in the

storage chambers

7 and 8 at the time of overcharging. For this reason, it is not necessary to additionally provide a gas pressure booster or a communication passage. Therefore, the battery C1 is a battery that can be manufactured and supplied inexpensively because it has a simple structure. In particular, oxygen gas is dissolved and stored in the electrolyte. Therefore, the safety regarding the handling of oxygen gas is dramatically improved.

Furthermore, as described above, when the battery C1 is discharged, electrical energy is output by the reactions shown in the formulas (1) and (3). For this reason, load followability and power are significantly improved as compared with the conventional fuel cell. As a result, the battery C1 can also be used in applications with a large load fluctuation that requires instantaneous high power, such as a vehicle. At this time, the battery C1 can be used alone without requiring an additional secondary battery or a storage device such as a capacitor.

(Modification of the first embodiment)
FIG. 1B is a cross-sectional view schematically showing a structure of a battery C1 ′ according to a modification of the first embodiment. The battery C1 ′ has substantially the same structure as the battery C1 of the first embodiment. That is, the battery C1 ′ includes the negative electrode 4 ′ and the positive electrode 6 ′ facing each other through the separator 5 ′, the negative electrode case 1 ′ forming the hydrogen storage chamber 8 ′, and the positive electrode case 2 ′ forming the oxygen storage chamber 7 ′. , As a main component. The main differences are as follows. That is, in the oxygen storage chamber 7 'of the battery C1, the electrolytic solution 3' in which oxygen is dissolved is stored. On the other hand, the oxygen storage chamber 7 'of the battery C1' holds the oxygen gas and the electrolytic solution 3 '. That is, the oxygen storage chamber 7 'partially holds the electrolytic solution 3'.

The surface of the negative electrode 4 ′ in contact with the hydrogen storage chamber 8 ′ contains a large amount of hydrophobic material. On the other hand, the surface in contact with the separator 5 'of the negative electrode 4' has hydrophilicity. Further, the surface of the positive electrode 6 'in contact with the oxygen storage chamber 7' contains a large amount of hydrophobic material. Thereby, the manganese dioxide of positive electrode 6 'can be contacted with oxygen gas, without getting wet. The surface in contact with the separator 5 'of the positive electrode 6' has hydrophilicity. Thus, this surface prevents the passage of oxygen gas. This surface is kept almost always wet with the electrolyte. Thereby, the ion conductivity of the positive electrode 6 'is secured. The surfaces of the electrodes 4 'and 6' on the side of the gas storage chambers 8 'and 7' may be coated or sprayed with hydrophobic carbon or Teflon. In addition, the surface of the electrodes 4 'and 6' in contact with the separator 5 'may be coated or sprayed with hydrophilic modified nylon. Furthermore, vinyl acetate having both hydrophilic and hydrophobic properties may be granulated and used as a binder.

The separator 5 'holds the electrolytic solution 3'. Furthermore, in the present embodiment, both surfaces of the separator 5 'are wetted with the electrolyte solution 3'. For this reason, the separator 5 'functions as a water seal separator. Thereby, the gas impermeability of the separator 5 'is enhanced. As a result, hydrogen gas and oxygen gas are more reliably prevented from passing through the separator 5 'and coming into contact with each other and reacting with each other.

The hydrogen storage chamber 8 ′ and the oxygen storage chamber 7 ′ are configured not to communicate with each other. The oxygen storage chamber 7 'is filled with about one third of the volume of the oxygen storage chamber 7', which is the same type of electrolyte as the electrolyte 3 'interposed between the positive and negative electrodes.

When the amount of the electrolyte solution 3 'filled in the oxygen storage chamber 7' is small, the amount of water to be electrolyzed is small. As a result, the amount of hydrogen gas and oxygen gas generated during overcharge decreases. On the other hand, if the amount of electrolyte solution is large, the storage volume of gas decreases. From such a point of view, the amount of the electrolyte 3 'filled in the oxygen storage chamber 7' is preferably in the range of 20 to 50% of the volume of the oxygen storage chamber 7 ', and in the range of 25 to 40%. It is more preferable to be inside.

The operation of the battery C1 'configured as described above is shown below. The battery C1 'can be charged by current as usual until it is fully charged as a secondary battery. After the battery C1 'reaches a fully charged state, when current supply is further continued, hydrogen gas is generated from the negative electrode 4' and oxygen gas is generated from the positive electrode 6 '. The hydrogen gas and the oxygen gas are respectively stored in the hydrogen storage chamber 8 'and the oxygen storage chamber 7' without contacting each other. Then, the negative electrode 4 'and the positive electrode 6' are charged by the hydrogen gas or oxygen gas stored in the storage chamber 8 'or 7'.

When the discharge of the battery C1 'is started, a normal discharge reaction as a secondary battery occurs between the negative electrode 4' and the positive electrode 6 '. Thereby, current flows to the load. At this time, the amount of electricity of the negative electrode 4 'and the positive electrode 6' decreases due to discharge. The reduced amount of electricity of the negative electrode 4 'and the positive electrode 6' is compensated by charging with hydrogen gas and oxygen gas stored in the hydrogen storage chamber 8 'and oxygen storage chamber 7'. That is, in the negative electrode 4 ', hydrogen gas compensates for the amount of protons released from the charged hydrogen storage alloy (MH). Thereby, the charged state of the negative electrode is maintained. On the other hand, in the positive electrode 6 ′, manganese oxyhydroxide (MnOOH) produced by reduction of charged manganese dioxide (MnO ₂ ) is oxidized again by oxygen gas. Thereby, the charged state of the positive electrode is maintained. After the hydrogen gas and oxygen gas in storage chambers 7 'and 8' are consumed, battery C1 'discharges in the same manner as a conventional secondary battery.

That is, the battery C1 'which concerns on this embodiment can store energy in an electrode by normal charge as a secondary battery. Furthermore, the battery C1 'stores the electric energy supplied at the time of overcharge as a gas in the storage chambers 7' and 8 '. Then, the battery C1 'can reconvert the stored energy into electrical energy for use.

Furthermore, the pressure resistance performance and the sealing performance of the battery C1 'are enhanced between the storage chambers 7' and 8 'and the battery C1' including them. This increases the amount of gas storage per volume. As a result, the energy density of the battery C1 'can be significantly improved (for example, by several tens of times) as compared with the conventional secondary battery. In addition, hydrogen gas generated at the negative electrode 4 'or oxygen gas generated at the positive electrode 6' is directly stored in the storage chambers 7 'and 8' at the time of overcharging. For this reason, it is not necessary to additionally provide a gas pressure booster or a communication passage. Therefore, the battery C1 'is a battery that can be manufactured and supplied inexpensively because it has a simple structure.

Furthermore, as described above, when the battery C1 'is discharged, electrical energy is output by the electrode reaction of the secondary battery. For this reason, load followability and power are significantly improved as compared with the conventional fuel cell. Thus, the battery C1 'can also be used in applications with a large load fluctuation that requires instantaneous high power, such as a vehicle. Under the present circumstances, battery C1 'can be used independently, without requiring electrical storage apparatuses, such as an additional secondary battery or a capacitor.

Second Embodiment
Next, a battery C2 according to a second embodiment of the present fuel cell will be described. The battery C2 has a battery structure that is excellent in pressure resistance performance and easy to handle. 2A and 2B are cross-sectional views showing the structure of the battery C2. FIG. 2B is a cross-sectional view taken along the line DD in FIG. 2A. This battery C2 has the same basic configuration as the battery C1 of the first embodiment described in FIGS. 1A and 1B. However, as shown in FIG. 2A, the battery C2 has a tubular outer package 10. Thus, the battery C2 has excellent withstand voltage performance and handling performance. And while the energy density increases, the battery C2 is easy to handle it. The negative electrode, the positive electrode, the separator, and the electrolyte, which are the basic elements of the battery C2 according to the present embodiment as a battery, are the same as the battery C1 according to the first embodiment except for the points specifically described below. The substance and structure of

As shown in FIG. 2A, the exterior body 10 formed in a tubular shape more specifically includes a cylindrical portion 10a and a bottom portion 10b. The bottom portion 10 b is the bottom of the exterior body 10 continuing to one end of the cylindrical portion 10 a. The negative electrode 14, the positive electrode 16, and the separator 15 interposed between the negative electrode 14 and the positive electrode 16 are accommodated inside the bottom portion 10 b. The negative electrode 14 and the positive electrode 16 are formed in a bottomed cylindrical shape. The negative electrode 14 and the positive electrode 16 have cylindrical

peripheral walls

14a and 16a and

bottoms

14b and 16b. The positive electrode 16 is disposed inside the exterior body 10 via a space in the radial direction. The negative electrode 14 is disposed further inside the positive electrode 16 with the separator 15 interposed therebetween. In the battery C <b> 2, a space (a space in the radial direction) between the exterior body 10 and the positive electrode 16 constitutes an oxygen storage chamber 19. On the other hand, a space formed inward of the negative electrode 14 constitutes a hydrogen storage chamber 18.

The exterior body 10 is formed of a conductive material, specifically, nickel-plated iron. The outer surface of the bottom 16 b of the positive electrode 16 is joined to the inner surface of the bottom 10 b of the package 10. Thereby, the exterior body 10 functions as a positive electrode terminal of the battery C2. On the other hand, a disk-shaped negative electrode terminal 11 is joined to the right end portion 14c of the negative electrode 14 on the opposite side (right side in FIG. 2A) of the bottom portion 14b. Specifically, the right end portion 14 c of the negative electrode 14 is disposed to project further to the right than the right end surfaces 10 c and 16 c of the exterior body 10 and the positive electrode 16. The inner diameter surface 17a of the doughnut-shaped insulating member 17 is fitted to the outer peripheral surface of the right end portion 14c. The insulating member 17 covers the exterior body 10 and the right end faces 10 c and 16 c of the positive electrode 16. Further, an inner surface (left surface in FIG. 2A) which is one surface of the negative electrode terminal 11 is joined to the right end portion 14 c of the negative electrode 14.

The

electrodes

14 and 16 have flexibility. Therefore, when the hydrogen storage chamber 18 becomes high pressure due to the generation of hydrogen gas due to overcharge, the pressure of the hydrogen storage chamber 18 is transmitted to the oxygen storage chamber 19. As a result, the electrolyte solution 13 in the oxygen storage chamber 19 is compressed to a high pressure. The electrolyte that has become high pressure can dissolve more oxygen inside.

Here, the surface of the negative electrode 14 in contact with the hydrogen storage chamber 18 contains a large amount of hydrophobic material. Thereby, the hydrogen storage alloy of the negative electrode 14 can be in contact with hydrogen gas without getting wet. Further, since the surface of the negative electrode 14 in contact with the separator 15 has hydrophilicity, it is kept almost always wet with the electrolytic solution. As a result, hydrogen gas is prevented from passing through the negative electrode 14, and the ion conductivity of the negative electrode 14 is secured.

The dimensions of the exterior body 10 will be described. The outer diameter of the exterior body 10 may be in the range of 13.5 mm to 14.5 mm. In addition, the length of the exterior body 10 may be in the range of 49.0 mm to 50.5 mm. In addition, the outer diameter of the exterior body 10 may be in the range of 10.5 mm to 9.5 mm. In addition, the length of the exterior body 10 may be in the range of 42.5 mm to 44.5 mm. When the size of the outer package 10 is in the above range, dimensional compatibility with a commercially available AA battery or AAA battery can be realized.

According to the battery C2 of the second embodiment configured as described above, the following effects can be obtained in addition to the effects obtained by the battery C1 of the first embodiment described above.

The exterior body 10 of the battery C2 has a tubular structure as shown in FIGS. 2A and 2B. For this reason, it becomes easy to secure excellent pressure resistance and to increase the energy density. Furthermore, by connecting a large number of batteries C2 in parallel and in series, it becomes easy to configure a battery module with a large charge / discharge capacity. In particular, in the battery C2 of the present embodiment, the oxygen storage chamber 19 is formed in the space in the radial direction. Furthermore, a hydrogen storage chamber 18 is formed inward of the negative electrode 14. Thus, no additional components are needed to form the hydrogen storage chamber 18 and the oxygen storage chamber 19. Therefore, the battery C2 has a simple structure, and can be formed using only the minimum necessary members. Therefore, the battery C2 has high pressure resistance and energy density because it has small dimensions. Nevertheless, the assembly operation of the battery C2 is easy because the number of parts is small.

First Modification of Second Embodiment
A battery C2 'according to a modification of the second embodiment has substantially the same structure as the battery C2 of the second embodiment. The differences are as follows. That is, in the oxygen storage chamber 19 of the battery C2, the electrolytic solution 13 in which oxygen is dissolved is stored. On the other hand, the oxygen storage chamber 19 of the battery C2 'holds oxygen gas and the electrolyte solution 13. That is, the oxygen storage chamber 19 partially holds the electrolyte solution 13. In addition, each electrode may not have flexibility.

Furthermore, the surface of the positive electrode 16 in contact with the oxygen storage chamber 19 contains a large amount of hydrophobic material. Thereby, the manganese dioxide of the positive electrode 16 can contact with oxygen gas without getting wet. Since the surface of the positive electrode 16 in contact with the separator 15 has hydrophilicity, it is kept almost always wet with the electrolytic solution. Thus, oxygen gas is prevented from passing through the positive electrode 16, and the ion conductivity of the positive electrode 16 is secured. The surfaces of the

electrodes

14 and 16 on the side of the

gas storage chambers

18 and 19 may be coated or sprayed with hydrophobic carbon or Teflon. The surface of the

electrodes

14 and 16 on the separator 15 side may be coated or sprayed with modified nylon.

Second Modification of Second Embodiment
Next, a cell C3 according to a second modification of the second embodiment of the present fuel cell will be described. FIG. 3 is a partially broken view showing the connection structure of the battery C3. The battery C3 is a modification of a part of the external structure of the battery C2 according to the second embodiment. The following description focuses on the changes. The battery C3 has a negative electrode terminal 11 electrically connected to the negative electrode 14 at one end in the axial direction (axial direction of the exterior body 10). In addition, the battery C3 has, at the other end in the axial direction, a positive electrode terminal which is an exterior body 10 electrically connected to the positive electrode 16. Then, as shown in FIG. 3, a protrusion 11 d is provided at the center of the negative electrode terminal 11. In addition, a bottom recess 10 d is provided at the center of the bottom 10 b of the exterior body 10. The projection 11 d and the bottom recess 10 d are shaped to be fittable. Thereby, two batteries C3 can be connected in series.
According to this configuration, a plurality of batteries C3 can be connected in series without the need for wiring. In the example shown in FIG. 3, the convex portion is provided in the outer peripheral axial direction of the protrusion. On the other hand, a groove is provided on the inner peripheral surface of the bottom recess. And the convex part of a projection part is comprised so that the groove of a bottom part recessed part may be fitted. However, the shape of the fitting portion may be another method.

A threaded portion may be formed on the positive electrode terminal (exterior body 10) and the negative electrode terminal 11. That is, the protrusion 11 d of the negative electrode terminal 11 may be a male screw, and the recess 10 d provided in the bottom 10 b of the exterior body 10 may be a female screw. Thereby, the two batteries C2 can be connected more reliably.

In the battery C3, the oxygen storage chamber (not shown) may be filled with an electrolyte in which oxygen is dissolved. Alternatively, it may be filled with an electrolytic solution and oxygen gas.

FIGS. 4A and 4B show the structure of a battery module B3 in which a plurality of batteries C3 are connected. The battery module B3 has a pair of conductive current collector plates 25 provided opposite to each other. The plurality of batteries C3 are disposed between the current collectors 25. The exterior body 10 which is a positive electrode terminal is in contact with one current collecting plate 25. The negative electrode terminal 11 is in contact with the other current collector plate 25. The batteries C3 are arranged parallel to one another so as to maintain such a state. In the battery module B3, a battery group including a plurality of batteries C3 connected in parallel is connected in series (FIG. 4A).

With such a configuration, it is possible to omit the wiring for connecting the battery C3. For this reason, assembly of battery module B3 becomes easy. Further, as shown in the enlarged view of the main part surrounded by a circle in FIG. 4A, through holes 25 a may be provided in the current collector plate 25. In this case, the protrusion 11d of the battery C3 is fitted into the bottom recess 10d of the other battery C3 through the through hole 25a. Thereby, assembly of battery module B3 becomes still easier. With such a structure, the plurality of batteries C3 are supported by the current collector 25. Therefore, battery module B3 has a self-supporting structure as an assembled battery. The battery included in the battery module B3 is not limited to the battery C3, and may be the battery C2.

In order to send the cooling air in the parallel direction of the current collector plate 25, a blower fan 27 may be provided. The heat generated by the battery C3 is transmitted to the current collector 25. Battery C3 is indirectly cooled by collector plate 25 acting as a radiation fin. The current collector plate 25 plays the role of both the conductive member and the heat dissipation member. For this reason, the material of the current collector plate 25 may have high thermal conductivity and electrical conductivity. In this regard, aluminum has relatively low electrical resistance and relatively high thermal conductivity. For this reason, aluminum has desirable characteristics as a material for forming the current collector plate 25. However, since aluminum is easily oxidized, the contact resistance of the current collector plate 25 tends to increase. Therefore, the aluminum plate included in the current collector plate 25 may be plated with nickel. Thereby, the contact resistance can be reduced. The current collector plate 25 is provided with a plurality of refrigerant passages 26 for passing insulating oil for cooling (see FIG. 4B). The batteries C3 (through holes 25a) may be arranged in a staggered arrangement (see FIG. 4B). Thus, the cooling air from the blower fan 27 is blown directly to the side surface of the battery C3. As a result, the cooling effect is enhanced. However, when the battery module is cold, the air warmed by a heater (not shown) may be blown by the blower fan 27. This makes it possible to warm up the battery module.

(Third Modification of Second Embodiment)
Next, a cell C4 according to a third modification of the second embodiment of the present fuel cell will be described. 5A to 5C are cross sectional views showing the structure of a battery C4 (battery C4a, C4b and C4c). The cell C4 is a part of the structure of the cell C2 according to the second embodiment of the present fuel cell. The following description focuses on the changes. The battery C 4 is provided with a hydrogen flow port 28 communicating with the hydrogen storage chamber 18 at the central portion of the negative electrode terminal 11. An oxygen flow port 30 communicating with the oxygen storage chamber 19 is provided at the central portion of the bottom portion 10 b of the exterior body 10 acting as a positive electrode terminal. The hydrogen or oxygen stored in the

storage chambers

18 and 19 of the battery C4 can be exhausted through the

flow ports

28 or 30 provided in the

connection portions

29 and 31.

Also, a hydrogen gas source and an oxygen gas source are installed outside. From these, hydrogen gas and oxygen gas can be supplied to the

storage chambers

18 and 19 through the

flow ports

28 and 30. The

connection parts

29 and 31 provide connection means for realizing connection between the battery C4 and an external hydrogen gas source and an oxygen gas source. Further, the shapes of the

connection parts

29 and 31 in the battery C4 may be any of the structures shown in FIGS. 5A to 5C. That is, in the example (battery C4a) shown to FIG. 5A, while it has the shape which the connection part 29a protruded, it has the shape of the hole which the connection part 31a penetrates. Moreover, in the example (battery C4c) shown to FIG. 5C, the connection parts 29c and 31c have the shape which protruded both. Furthermore, in the example shown in FIG. 5B (battery C4b), both of the connection parts 29b and 31b have the shape of a through hole. It is possible to select any shape as appropriate.

FIG. 6 is a drawing showing the configuration of the battery bank S4. A plurality of batteries C4c are connected to the battery bank S4. The battery C4a or the battery C4b may be used depending on the shape of the connection portion. The battery bank S4 has a hydrogen gas first header 35 and an oxygen gas first header 36. These include conductive materials. Each of these is provided with a plurality of connection portions 35a and 36a. Thereby, the connection part 29 and the connection part 31 of the battery C4 are connected airtightly. Thus, the hydrogen storage chamber 18 and the oxygen storage chamber 19 of the battery C4 can communicate with the hydrogen gas first header 35 and the oxygen gas first header 36, respectively. For example, thirty batteries C4 are disposed between the hydrogen gas first header 35 and the oxygen gas first header 36 and connected to these

headers

35 and 36.

If 30 or more batteries C4 are used, a hydrogen gas first header 35 and an oxygen gas first header 36 may be added. When a plurality of hydrogen gas first gas headers 35 and oxygen gas first headers 36 are used, the hydrogen gas first gas headers 35 and the oxygen gas first headers 36 are respectively via insulating connecting

members

32 and 33 including an insulating material. The hydrogen gas second header 38 and the oxygen gas second header 39 are connected. The adjacent oxygen gas first header 36 and the hydrogen gas first header 35 are electrically connected via the conductive connection member 34 including the conductive material. The hydrogen gas second header 38 and the oxygen gas second header 39 are finally connected to the hydrogen gas tank and the oxygen gas tank (both are TANK in the figure). In such a configuration, the hydrogen gas and the oxygen gas generated in the battery C4 are collected in the respective tanks, and can be used in the battery C4. In addition, hydrogen gas and oxygen gas can be supplied from these tanks to the hydrogen storage chamber 18 and the oxygen storage chamber 19 of the battery C4. This makes it possible to generate electricity using chemical energy of hydrogen gas and oxygen gas. On the other hand, the negative electrode terminal 11 of the battery C4 and the exterior body 10 to be a positive electrode terminal are connected to the hydrogen gas first header 35 and the oxygen gas first header 36, respectively. Thereby, the electricity of the battery C4 is collected by the

first headers

35 and 36. When a plurality of

first headers

35 and 36 are employed, they are connected in series by the conductive connection members 34, and electricity is output from the battery bank S4.

In the battery C4, instead of the oxygen gas source, an oxygen electrolyte source in which oxygen is dissolved may be connected. In this case, in the above-described battery bank, oxygen acts as a working fluid in a state of being dissolved in the electrolyte.

Third Embodiment
FIGS. 7A and 7B are cross-sectional views showing the structure of a cell C5 according to a third embodiment of the present fuel cell. The battery C5 adopts substantially the same material and configuration as the battery C1 of the first embodiment described in FIGS. 1A and 1B. However, part of the structure is different between the battery C5 and the battery C1. The differences will be mainly described.

The battery C5 converts chemical energy of hydrogen and oxygen into electric energy and uses it. Furthermore, the cell C5 is configured as a reversible fuel cell in which the reaction mechanism of the secondary cell is incorporated into the fuel cell. The battery C5 includes, as main components, a negative electrode 54, a positive electrode 56, a negative electrode case 51, and a positive electrode case 52. The negative electrode 54 and the positive electrode 56 face each other via the separator 55. The negative electrode case 51 has a hydrogen storage chamber 58. The positive electrode case 52 has an oxygen storage chamber 59.

The main active material of the negative electrode 54 is a hydrogen storage alloy. The main active material of the positive electrode 56 is manganese dioxide. An electrolytic solution 53 is interposed between the negative electrode 54 and the positive electrode 56 together with the separator 55. As the electrolytic solution 53, a KOH aqueous solution, which is an alkaline aqueous solution generally used in a secondary battery, is used.

The negative electrode 54 is manufactured as follows. That is, a solvent is added to the negative electrode active material, the conductive filler, and the resin to form a paste. This paste is applied onto a substrate, shaped into a plate, and cured. Similarly, the positive electrode 56 is manufactured as follows. That is, a solvent is added to the positive electrode active material, the conductive filler and the resin to form a paste. This paste is applied onto a substrate, shaped into a plate, and cured.

As a material of the conductive filler, carbon fiber, carbon fiber with nickel plating, carbon particles, carbon particle with nickel plating, organic fiber with nickel plating, fibrous nickel, nickel particles , And nickel foils. These can be used alone or in combination of two or more. The resin is used as a binder. As this resin, a thermoplastic resin having a softening temperature of up to 120 ° C., a resin having a curing temperature of from normal temperature to 120 ° C., a resin having an evaporation temperature of 120 ° C. or less and soluble in a solvent, a water soluble solvent A resin that dissolves, a resin that dissolves in a solvent soluble in alcohol, or the like can be used. An electrically conductive metal plate such as a nickel plate can be used as the substrate. Alternatively, a foamed nickel sheet may be used instead of the substrate.

The surface of the negative electrode 54 in contact with the hydrogen storage chamber 58 contains a large amount of hydrophobic material. Thereby, the hydrogen storage alloy of the negative electrode 54 can be in contact with the hydrogen gas without getting wet. The surface of the negative electrode 54 in contact with the separator 55 has hydrophilicity. Thus, this surface prevents hydrogen gas from passing through the negative electrode 54. This surface is kept almost always wet with the electrolyte. Thereby, the ion conductivity of the negative electrode 54 is secured. The surface of the positive electrode 56 in contact with the oxygen storage chamber 59 contains a large amount of hydrophobic material. Thereby, the manganese dioxide of the positive electrode 56 can be in contact with oxygen gas without being wetted. The surface of the positive electrode 56 in contact with the separator 55 has hydrophilicity. Thus, this surface prevents oxygen gas from passing through the positive electrode 56. This surface is kept almost always wet with the electrolyte. Thereby, the ion conductivity of the positive electrode 56 is secured.

The surfaces of the

electrodes

54 and 56 on the side of the

gas storage chambers

58 and 59 may be coated or sprayed with hydrophobic carbon, Teflon or the like. In addition, the surface of the

electrodes

54 and 56 on the separator 55 side may be coated or sprayed with modified nylon. Moreover, when manufacturing an electrode, you may granulate and use as a binder the vinyl acetate which has the characteristic of both hydrophilicity and hydrophobicity. Furthermore, a mixture of a binder containing granulated vinyl acetate and a hydrophilic material may be applied to the separator 55 side of the

electrodes

54 and 56. A mixture of a binder containing granulated vinyl acetate and a hydrophobic material may be applied to the

gas storage chambers

58 and 59 of the

electrodes

54 and 56.

The separator 55 has a structure that transmits proton (H ⁺ ) but does not easily transmit hydrogen gas and oxygen gas. Specifically, a microporous film can be used as a material for forming the separator 55. The material of this microporous film includes polyolefin fibers such as polyethylene fibers and polypropylene fibers, polyphenylene sulfide fibers, polyfluoroethylene fibers, polyamide fibers and the like. The electrolytic solution 53 is held in the separator 55. Furthermore, in the present embodiment, both surfaces of the separator 55 are wetted with the electrolyte solution 53. Thereby, the separator 55 functions as a water-sealed separator and has high gas impermeability. Also, the hydrogen gas and the oxygen gas are reliably prevented from passing through the separator 55 and coming in contact with each other and reacting with each other.

The structure is such that the negative electrode 54 and the positive electrode 56 sandwich the separator 55. The surface of the negative electrode 54 not in contact with the separator 55 is airtightly covered by a box-shaped negative electrode case 51. Therefore, the inner space formed by the negative electrode 54 and the negative electrode case 51 functions as a hydrogen storage chamber 58. The hydrogen storage chamber 58 stores hydrogen gas generated at the negative electrode 54 without interposing an additional member such as a pressure increasing device or a communication passage with the negative electrode 54. Similarly, the surface of the positive electrode 56 not in contact with the separator 55 is airtightly covered by a box-shaped positive electrode case 52. The inner space formed by the positive electrode 56 and the positive electrode case 52 functions as an oxygen storage chamber 59. The hydrogen storage chamber 58 and the oxygen storage chamber 59 are configured independently, that is, the hydrogen storage chamber 58 and the oxygen storage chamber 59 do not communicate with each other. The oxygen storage chamber 59 is filled with an electrolyte of the same type as the electrolyte 53 held by the separator 55, which is about one third of the volume of the oxygen storage chamber 59. However, the oxygen storage chamber 59 may be filled with the electrolyte. In this case, oxygen may be dissolved in the electrolytic solution. However, in this case, the

electrodes

54 and 56 have flexibility, and the deformation of the hydrogen storage chamber 58 extends to the oxygen storage chamber 59. As a result, when the pressure of the hydrogen storage chamber 58 is increased by the hydrogen gas, the pressure of the electrolyte is increased to be substantially equal to the pressure of the hydrogen storage chamber 58.

The negative electrode case 51 and the positive electrode case 52 may be made of a material having high thermal conductivity and electrical conductivity. These may be comprised with steel materials, such as aluminum. However, steel materials are easily oxidized and contact resistance tends to increase. Therefore, the aluminum contained in the negative electrode case 51 and the positive electrode case 52 may be plated with nickel. Thereby, the contact resistance can be reduced. The negative electrode case 51 and the positive electrode case 52 function as a negative electrode terminal and a positive electrode terminal of the battery C5, respectively.

The amount of the electrolyte solution 53 filled in the oxygen storage chamber 59 is roughly divided into two. One is 90% or more of the volume of the oxygen storage chamber 59. The other is in the range of 20 to 40% of the volume of the storage chamber 59. In the former case, oxygen gas generated by electrolysis is dissolved in the electrolyte and stored. In the latter case, oxygen is stored in gaseous state in the oxygen storage chamber 59.

The operation of the battery C5 configured as described above is shown below. The battery C5 is charged by the current as a secondary battery until it is fully charged. After the battery C5 reaches the fully charged state, when current supply is further continued, hydrogen gas is generated from the negative electrode 54 and oxygen gas is generated from the positive electrode 56. The hydrogen gas and the oxygen gas are respectively stored in the hydrogen storage chamber 58 and the oxygen storage chamber 59 without being in contact with each other.

When the discharge of the battery C5 is started, a normal discharge reaction as a secondary battery occurs between the negative electrode 54 and the positive electrode 56. Thereby, current flows to the load. At this time, the amounts of electricity of the negative electrode 54 and the positive electrode 56 decrease due to discharge. The reduced amount of electricity of the negative electrode 54 and the positive electrode 56 is compensated by charging with hydrogen gas and oxygen gas stored in the hydrogen storage chamber 58 and the oxygen storage chamber 59. When the oxygen storage chamber 59 is filled with the electrolyte in which oxygen is dissolved, the positive electrode 56 is charged by the oxygen in the electrolyte.

At the negative electrode 54, hydrogen gas compensates for the amount of protons released from the charged hydrogen storage alloy (MH). Thereby, the charged state of the negative electrode is maintained. On the other hand, in the positive electrode 56, manganese oxyhydroxide (MnOOH) produced by reduction of charged manganese dioxide (MnO ₂ ) is oxidized again by oxygen. Thereby, the charged state of the positive electrode is maintained. After the hydrogen gas and oxygen gas in

storage chambers

58 and 59 are consumed, battery C5 discharges in the same manner as a conventional secondary battery.

That is, the battery C5 which concerns on this embodiment can store electrical energy in an electrode by charge by electricity as a secondary battery. Furthermore, the battery C5 stores the electric energy supplied at the time of overcharge in the

storage chambers

58 and 59 as gas (chemical energy). Then, the battery C5 can convert the stored chemical energy into electrical energy and use it. Furthermore, the gas storage capacity per volume can be increased by enhancing the pressure resistance performance and the sealing performance of the storage compartments 58 and 59 and the battery C5 including the storage compartments 58 and 59. As a result, the energy density of the battery C5 can be greatly improved (for example, about several tens of times) as compared with the conventional secondary battery. Moreover, in the

storage chambers

58 and 59, hydrogen gas generated at the negative electrode 54 or oxygen gas generated at the positive electrode 56 at the time of overcharging is directly stored. For this reason, it is not necessary to additionally provide a gas pressure booster or a communication passage. Therefore, the battery C5 is a battery that can be manufactured and supplied inexpensively because it has a simple structure.

When the battery C5 is discharged, electrical energy is output by the electrode reaction of the secondary battery. For this reason, the followability to the load is greatly improved as compared with the conventional fuel cell. As a result, the battery C5 can also be used in applications with a large load fluctuation that requires instantaneous high power, such as a vehicle. Under the present circumstances, the battery C5 can be independently used, without requiring electrical storage apparatuses, such as an additional secondary battery or a capacitor.

Moreover, in the battery C5 according to the present embodiment, the positive electrode 56 contains manganese dioxide as a positive electrode active material. Therefore, the positive electrode 56 is excellent in durability and has high life characteristics.

In the battery C5 shown in FIG. 7A, the outer peripheral surface 55a of the separator 55 is covered with an insulating portion 67 having the same thickness as the separator 55. The outer dimensions of the negative electrode case 51, the positive electrode case 52, and the insulating portion 67 are adjusted such that the outer peripheral surface 51a of the negative electrode case 51, the outer peripheral surface 52a of the positive electrode case 52, and the outer peripheral surface 67a of the insulating portion 67 are flush. . The insulating portion 67 is made of an airtight material. Further, the separator 55 blocks the passage of gas by the action of the electrolytic solution. Therefore, even if oxygen gas or hydrogen gas reaches the outer peripheral surface 55a of the separator 55, these do not leak to the outside of the battery C5.

A step 65 or 66 is provided at the opening of each of the negative electrode case 51 and the positive electrode case 52. The width of the steps 65 and 66 is approximately equal to the thickness of the negative electrode 54 and the positive electrode 56. The negative electrode 54 and the positive electrode 56 are attached so as to cover the openings of the negative electrode case 51 and the positive electrode case 52, respectively.

FIG. 7B is an assembled cross-sectional view showing the structure of a battery module B5 including a plurality of batteries C5 shown in FIG. 7A. The battery module B5 includes, as main components, a positive electrode terminal 64, a negative electrode terminal 63, an insulating casing 62 for wrapping the battery C5, lid members 68 and 69, and a mounting bolt 70. The lid members 68 and 69 are members for clamping and fixing the battery C5 in the axial direction of the insulating casing 62. These main components are covered by a metal protective casing 61.

In the battery module B <b> 5, a plurality of batteries C <b> 5 are enclosed in the insulating casing 62 along the axial direction of the insulating casing 62. The outer peripheral surfaces 51a and 52a of the battery C5 are along the inner peripheral surface 62a of the insulating casing 62 including the insulating material. The side surface 51b of the negative electrode case 51 of the adjacent battery C5 and the side surface 52b of the positive electrode case 52 are in contact with each other. The negative electrode terminal 63 and the positive electrode terminal 64 of the battery module B5 are provided at both ends of the plurality of batteries C5. A lid member 68 or 69 is fitted to the inner circumferential surface 61 a of the protective casing 61 on the outside of each of the negative electrode terminal 63 and the positive electrode terminal 64. Screw holes are formed in the lid members 68 and 69. Further, in the protective casing 61, bolt holes 70a are formed. The protective casing 61 and the lid members 68 and 69 are fixed by the mounting bolt 70, respectively. Thus, the battery C5 and the positive and

negative electrode terminals

63 and 64 are housed inside the protective casing 61.

A configuration example of a battery bank including a plurality of battery modules B5 connected to one another is shown in FIGS. 8A and 8B.
In the battery bank S5, one end of a metal wire 474 is attached to the battery module B5, and the other end is attached to a steel tower 478. Thus, the plurality of battery modules B5 can be suspended from the steel tower 478. The negative electrode terminal 63 and the positive electrode terminal 64 of the adjacent battery modules B5 are connected by a bus bar 477 via a circuit breaker 476 which can be opened and closed.

The battery bank S5 as described above may be applied to a power system. When the battery bank S5 is applied to a power system, the voltage becomes high and a withstand voltage structure is adopted. For this reason, in this case, the circuit breaker 476 is also suspended by the insulated wire 474 in order to ensure the withstand pressure performance to the ground.

Fourth Embodiment
FIGS. 9A and 9B are cross-sectional views showing the structure of a reversible fuel cell C10 (hereinafter simply referred to as a cell C10) according to a fourth embodiment of the present fuel cell. FIG. 9A is a partial cutaway view in the longitudinal direction. FIG. 9B is a cross-sectional view along the line AA in FIG. 9A. The battery C10 has a structure covered by the outer shell 100. Inside the outer shell 100, a plurality of tube-shaped positive electrodes 110 are accommodated along the axial direction of the outer shell 100 (X direction in FIG. 9A). Then, around the positive electrode 110, the negative electrode 120 is packed and disposed via the separator 130. The negative electrode, the positive electrode, the separator, and the electrolyte, which are the basic elements of the battery C10 according to the present embodiment, are the same as / in the same manner as the battery C1 according to the first embodiment described above except in the cases specifically described below It may be composition and structure.

The outer shell 100 has a cylindrical body portion 101 and a bulging portion 102. The bulging portion 102 is disposed at both end openings of the body portion 101. The bulging portion 102 bulges outward of the opening in a direction away from the opening and covers the opening. A packing 103 for keeping the inside of the outer shell 100 liquid tight is disposed between the trunk portion 101 and the bulging portion 102. The body portion 101 and the bulging portion 102 may be made of steel, preferably high-tensile steel. Thus, the body portion 101 has a cylindrical shape, and the bulging portion 102 bulges outward. Thus, the outer shell 100 has a structure that can withstand the internal pressure even if the internal pressure is extremely high.

Oxygen storage chambers

136a and 136b are provided inside the outer shell 100 and in the inner space of the bulging portion 102. The left and right

oxygen storage chambers

136 a and 136 b are respectively divided by the partition plate 135. The oxygen storage chambers 136 a and b can be connected to external equipment via the

flanges

211 and 212 attached to the shell 100. The positive electrode 110, the negative electrode 120, the separator 130, and the current collector 134 are disposed in the space between the left and right

oxygen storage chambers

136a and 136b and surrounded by the partition plate 135 and the body portion 101.

FIG. 10 is a partially broken view for illustrating the structure of an electrode in battery C10. The current collector 134 is a nickel-plated perforated steel pipe. The positive electrode 110 is formed by applying a paste-like mixture containing manganese dioxide around the current collector 134. The positive electrode 110 may apply the mixture directly to the current collector 134. Alternatively, the positive electrode 110 may be formed by spreading a positive electrode sheet formed by applying a composite material to foamed nickel, to the current collector 134. A separator 130 is interposed between the positive electrode 110 and the negative electrode 120 containing an oxygen storage alloy. The separator 130 prevents the positive electrode 110 and the negative electrode 120 from coming in contact with each other. The

oxygen storage chambers

136 a and 136 b located on the left and right sides of the shell 100 communicate with each other through the current collector 134. The electrolyte solution 137 in the

oxygen storage chambers

136a and 136b can flow in the direction indicated by the arrow in FIG.

A hydrogen storage alloy having an average particle diameter of 20 μm is filled in an outer space of the separator 130 between the left and right partition plates 135. In this configuration, the porosity is approximately 35%. The size of the porosity varies depending on the method of filling the hydrogen storage alloy. The porosity may be greater than 35%. When the average particle size is 5 to 50 μm, the porosity is approximately 30 to 60%. Such a void functions as a hydrogen storage chamber 138. In addition, said average particle diameter is JIS like other embodiment.
It is a value represented using the sphere equivalent diameter by the light scattering method of Z 8910.

As shown by a broken line in FIG. 9A, a hydrogen gas storage source 121 and a storage passage 122 are connected to the hydrogen storage chamber 138 of the battery C10. The negative electrode 120 can be charged with hydrogen gas supplied from the outside.

The current collector 134 of the positive electrode passes through a nickel-plated steel partition plate 135. Both ends of the current collector 134 are supported by the partition plate 135. For this reason, the bulging part 102 and the positive electrode 110 are electrically connected via the partition plate 135. Thereby, the bulging part 102 functions as a positive electrode terminal of the battery C10. Further, the body portion 101 in direct contact with the negative electrode 120 functions as a negative electrode terminal. The packing 103 has insulation as well as sealability. Thereby, the packing 103 prevents the positive electrode 110 and the negative electrode 120 from shorting.

The operation of the battery C10 configured as described above is shown below. The electrolytic solution 137 in which oxygen is dissolved is supplied to the battery C10 from one of the flanges 211 (right side in FIG. 9A). The electrolytic solution 137 is an electrolytic solution in which oxygen is dissolved at a high concentration, and can be referred to as a high concentration oxygen-dissolved electrolytic solution. The electrolytic solution 137 in which oxygen is dissolved to a high concentration flows inside the pipe-like current collector 134, passes through the punched holes provided in the current collector 134, and contacts the positive electrode 110. Thus, the manganese oxyhydroxide in the positive electrode is oxidized to manganese dioxide by the oxygen dissolved in the electrolytic solution. As a result, the positive electrode is charged. As a result, oxygen dissolved in the electrolyte is consumed to generate H ₂ O, and the oxygen concentration in the electrolyte decreases. The electrolyte solution 137 (low concentration oxygen dissolved electrolyte solution) with the lowered oxygen concentration is discharged to the oxygen storage chamber 136b on the left side, and finally discharged from the flange 212 to the outside of the system. On the other hand, the negative electrode 120 is charged by hydrogen gas supplied from the external hydrogen gas storage source 121.

When an electrical load is connected between the bulging portion 102 functioning as a positive electrode terminal and the trunk portion 101 functioning as a negative electrode terminal using a wiring cable (not shown), the battery C10 discharges. Thereby, current is supplied to the electrical load. The load current can be taken from the bulges 102 at both ends. Therefore, the current flowing through the current collector 134 is divided into two on the left and right, and the Joule heat loss is about 1⁄4.

Next, the case of converting the electric energy into chemical energy and charging the battery C10 will be described. The battery C10 can store hydrogen gas generated by overcharging in the hydrogen storage chamber 138. In addition, the battery C10 can store oxygen gas in the

oxygen storage chambers

136a and 136b in a state of being dissolved in the electrolytic solution. That is, the battery C10 of the present embodiment can convert electrical energy into chemical energy and store it. Furthermore, the battery C10 can appropriately convert chemical energy into electrical energy and output it. For this reason, unlike the conventional secondary battery, the battery C10 is not limited by the amount of the active material.

Similar to the battery C1 according to the first embodiment, the battery C10 according to the present embodiment is also discharged by the battery reaction at the time of discharge, and is charged with hydrogen gas and oxygen. During such charge and discharge, manganese dioxide functions as a catalyst for the reaction at the positive electrode. On the other hand, the hydrogen storage alloy functions as a catalyst for the reaction in the negative electrode.

A power generation process using a battery C10 according to the fourth embodiment is shown in FIG. A pipe 220 is connected to the battery C10 via a flange 212. The electrolytic solution 137 deteriorated by the discharge of the battery C10 is carried to the first chamber 231 of the salt concentration adjusting device 230 through the pipe 220. The reverse osmosis membrane 233 is attached to the salt concentration adjusting device 230. The salt concentration adjusting device 230 is divided into a first chamber 231 and a second chamber 232 by the reverse osmosis membrane 233. The reverse osmosis membrane 233 has a function of selectively permeating water in the electrolyte solution 137. The permeated water is stored as drain in the second chamber 232 and drained out of the system through the drain port 234. The electrolyte solution 137 of the salt concentration adjusting device 230 is carried to the oxygen concentration adjusting device 250 through the pipe 221. An oxygen storage source 251 and a storage passage 252 are connected to the bottom of the oxygen concentration adjusting device 250. The contact between the oxygen gas and the electrolytic solution 137 increases the concentration of dissolved oxygen in the electrolytic solution. In addition, the storage passage 253 is separately provided in the oxygen concentration adjustment device 250, and the oxygen generated by the overcharge can be stored in the oxygen storage source 251. As a result, the high-concentration dissolved oxygen electrolyte stored in the oxygen storage source 251 can be returned to the oxygen concentration adjustment device 250. This electrolytic solution can be used to adjust the oxygen concentration lowered by the discharge.

The temperature of the electrolytic solution 137 discharged from the oxygen concentration adjusting device 250 is increased due to the use of the battery. The electrolytic solution 137 is cooled by the cooler 260 and reaches a predetermined temperature. Thereafter, the electrolytic solution 137 is pressurized by the pump 270 and returned to the battery C10 through the pipe 222.

Fifth Embodiment
FIG. 12 is a schematic cross-sectional view in the axial direction of a reversible fuel cell (hereinafter simply referred to as a cell C30) according to a fifth embodiment of the present fuel cell. The negative electrode, the positive electrode, the separator, and the electrolyte, which are the basic elements of the battery C30 according to this embodiment, are the same as / in the same manner as in the battery C1 according to the first embodiment except for the points specifically described below. It may have a composition and a structure. As shown in FIG. 12, the battery C30 is equipped with the exterior body 300, the collector 310, and the electrode accommodated in the inside of an exterior body as a main component. The exterior body 300 includes a circular tube 301 and a disc-like lid member 302. The lid member 302 is provided at the openings at both ends of the circular pipe 301. The material of the circular tube 301 and the lid member 302 is iron plated with nickel.

The material of the current collector 310 is made of a conductive material in which rod-shaped iron is plated with nickel. Both end portions of the current collector 310 pass through a hole provided at the center of the lid member 302. Nuts 311 are screwed on both ends of the current collector 310. The current collector 310 is fixed to the lid member 302 by the nut 311. The nut 311 is in the form of a bag. This prevents the electrolyte in the battery from leaking to the outside. An insulating packing 312 is provided between the nut 311 and the lid member 302. As a result, electrical contact between the current collector 310 and the lid member 302 is prevented. A packing 303 for sealing the inside of the battery is provided between the circular tube 301 and the lid member 302. The packing 303 has insulation. Therefore, electrical contact between the circular tube 301 and the lid member 302 is prevented. The current collector 310 is prevented from being corroded by the electrolytic solution by being plated with nickel.

The positive electrode 320 and the negative electrode 330 are stacked in the axial direction (X direction in FIG. 12) of the circular tube 301 via the separator 340. The positive electrode 320 and the negative electrode 330 are housed inside the exterior body 300. The separator holds an electrolytic solution. The separator 340 can insulate ions between the positive and negative electrodes as well as insulate between the positive and negative electrodes. The positive electrode 320 contains manganese dioxide filled in foamed nickel. The negative electrode 330 contains a hydrogen storage alloy filled in foamed nickel. Thereby, hydrogen gas can permeate | transmit a negative electrode. The positive electrode 320 has a substantially disk shape having an outer shape slightly larger than the inner diameter of the circular tube 301. The positive electrode 320 is partially cut away on the circumference 180 degrees apart from each other. The outer periphery of the positive electrode 320 is in contact with the inner surface of the circular tube 301 except for the cut-off portion (see FIG. 13A). A notch 321 is formed between the cut portion of the positive electrode 320 and the circular tube 301. Between the positive electrode 320 and the current collector 310 inside the positive electrode 320, a polypropylene PP packing 351 having the same thickness as that of the positive electrode 320 is interposed. The PP packing 351 insulates the positive electrode 320 and the current collector 310.

13A shows a BB cross section of the battery C30, and FIG. 13B shows a CC cross section of the battery C30.
The negative electrode 330 has a disk shape. The negative electrode 330 has a U-shaped cross section opening inward in the inner circumferential direction. A current collector 310 penetrates a hole provided at the center of the negative electrode 330. The diameter of the through hole is slightly smaller than the outer diameter of the current collector 310. Therefore, the inner diameter portion of the negative electrode 330 and the outer diameter portion of the current collector 310 are in contact with each other. A space surrounded by the negative electrode 330 and the current collector 310 forms a hydrogen storage chamber 380. A separator 340 is interposed between the positive electrode 320 and the negative electrode 330. The radially outer peripheral surface of the negative electrode 330 is covered with a PP packing 352. The outer diameter of the PP packing 351 is smaller than the inner diameter of the circular pipe 301. Therefore, a space (a gap) 331 is formed between the PP packing 351 and the circular pipe 301 (see FIG. 13B). Furthermore, a portion of the negative electrode 330 which does not face the separator 340 and the hydrogen storage chamber 380 is covered with a PP packing 353.

The lid member 302 is provided with a hydrogen gas supply port 373.

Holes

351a or 353a are provided in the positive electrode 320 and the PP packing 353. The

holes

351 a and 353 a form a hydrogen gas passage 370 communicating with the hydrogen storage chamber 380. As shown in FIG. 14, a high pressure hydrogen gas storage source 371 is connected to the hydrogen gas supply port 373 via a storage passage 372. The high pressure hydrogen gas can be supplied to each hydrogen storage chamber 380 through the hydrogen gas passages 370.

The lid member 302 is provided with an electrolyte inlet 365 and an electrolyte outlet 366, which are inlets and outlets of the electrolyte in which oxygen is dissolved, at positions separated by 180 degrees. The

electrolyte ports

365 and 366 are in communication with the notch 321. The notch 321 is in communication with the gap 331 between the PP packing 351 and the circular pipe 301. Therefore, the electrolytic solution flowing from the electrolytic solution inlet 365 circulates the inside of the battery C30 along the inner surface of the circular tube 301 and flows out from the electrolytic solution outlet 366. As shown in FIG. 14, a supply source 361 of an electrolytic solution in which high concentration of oxygen is dissolved is connected to an electrolytic solution inlet 365 via a supply passage 362. On the other hand, an electrolytic solution adjustment chamber 363 is connected to the electrolytic solution outlet 366 via a discharge passage 364. The electrolytic solution adjustment chamber 363 processes the electrolytic solution in which the oxygen concentration is lowered.

FIG. 15 is a system diagram of a battery C30 according to a fifth embodiment, including an electrolytic solution treatment process. The electrolytic solution coming out of the electrolytic solution outlet 366 of the battery C30 is sent to the cooler 326 through the pipe 364a. The electrolyte whose temperature has risen due to the use of the battery is cooled by the cooler 326 and reaches a constant temperature. Thereafter, the electrolytic solution is pressurized by the pump 327 and carried to the electrolytic solution adjustment chamber 363 through the pipe 364 b. Here, part of the water is selectively removed from the electrolytic solution. In addition, the electrolytic solution receives supply of oxygen from the electrolytic solution supply source 361. Thereby, the oxygen concentration of the electrolytic solution is adjusted. Thereafter, the electrolytic solution is returned to the battery C30 through the pipe 364c.

Next, the operation of the battery C30 will be described. As described above, the hydrogen gas supplied from the hydrogen gas supply port 373 is led to the hydrogen storage chamber 380 and charges the negative electrode 330. On the other hand, the electrolytic solution in which oxygen is dissolved to a high concentration supplied from the electrolytic solution inlet 365 is supplied from the notch 321 to the positive electrode 320 to charge the positive electrode 320. By charging the positive electrode 320, H ₂ O is generated. The H ₂ O is mixed with the electrolyte and discharged from the electrolyte outlet 366 to the outside of the battery C 30.

Similar to the charge and discharge in the battery C1 according to the first embodiment, the battery C30 according to the present embodiment is also discharged by the function of the secondary battery at the time of discharge and is chemically charged with hydrogen gas and oxygen. That is, the battery C30 is charged by gas at the same time as discharging as a secondary battery. And, at this time, manganese dioxide functions as a catalyst for the reaction at the positive electrode. On the other hand, the hydrogen storage alloy functions as a catalyst for the reaction in the negative electrode. Furthermore, the battery C30 can also be charged by current. The hydrogen gas generated by the overcharge can be stored in the hydrogen gas storage source 371 through the hydrogen gas passage 370 and the storage passage 372. In addition, oxygen gas can be stored in a state of being dissolved in the electrolyte. In other words, the battery C30 of the present embodiment can convert electrical energy into chemical energy and store it. For this reason, unlike the conventional secondary battery, the storage capacity of the battery C30 is not limited by the amount of the active material.

Hydrogen gas is supplied to the negative electrode of the battery C30. Therefore, the negative electrode is not oxidized even by the discharge. Thus, the life of the negative electrode does not deteriorate due to volume expansion and contraction. The positive electrode is oxidized by the oxygen of the oxygen-dissolved electrolytic solution to be in a charged state. For this reason, the positive electrode does not deteriorate due to discharge.

<Regarding the energy efficiency of reversible fuel cells>
The relationship between pressure and energy efficiency of the fuel cell is added below. Assuming that the energy obtained from the chemical substance to be used is ΔH, the amount of electricity that can be extracted is ΔG, and the heat that is generated is TΔS, the relationship ΔH = ΔG + TΔS holds. ΔH is also called reaction reaction heat or calorific value. ΔH takes a negative value in the case of an exothermic reaction such as a combustion reaction. ΔG is called free energy. ΔG is energy that can be taken out as work, and is called exergy as effective energy.

TΔS is heat generated with the reaction, and is expressed by the product of entropy change and temperature. And, ΔG / ΔH is the ability to extract effective energy, which is called exergy efficiency. The storage efficiency (that is, the amount of discharged power relative to the amount of charged power) when charging and discharging the nickel-hydrogen secondary battery can be raised to about 90 to 99%. On the other hand, the exergy efficiency ΔG / ΔH at the time of producing water and oxygen by electrolyzing water is 83% at normal temperature. Therefore, it is difficult for the storage efficiency to exceed 83%.

One of the problems to be solved by the present fuel cell is to make the exergy efficiency ΔG / ΔH as close as possible to 1 and reduce the proportion of heat (TΔS) at ΔH, and to make as many proportions of ΔH as possible. It is an object of the present invention to provide an apparatus capable of realizing conversion into electrical energy (ΔG). In order to increase the power generation efficiency η (= ΔG / ΔH), TΔS may be decreased and ΔG may be increased. ΔG is a value determined by temperature and pressure. By increasing this, the value of ΔG / ΔH can be increased.

When converting hydrogen to electrical energy using a fuel cell, 17% of the chemical energy ΔH obtained from hydrogen is heat (TΔS). In order to reduce the amount of heat generation, high pressure hydrogen may be sent to the fuel cell to generate electricity. This makes it possible to suppress the generation of heat and to increase the power generation efficiency. When producing hydrogen from electrical energy using a fuel cell, heat (TΔS) corresponding to 17% of ΔH obtained from hydrogen is used. At that time, if hydrogen and oxygen are generated at normal pressure, they will work to the atmosphere, causing losses. The electrolysis is then carried out in a closed space. This allows the used TΔS to be less than 17% of ΔH. FIG. 23 shows the thermodynamic calculation results. This figure shows that the larger the pressure, the smaller the TΔS.

In the fuel cell, oxygen gas and hydrogen gas obtained by electrolyzing the electrolyte are stored and used at high pressure without returning to atmospheric pressure. Thereby, high power generation efficiency η can be realized.

Further, the potential V and the free energy ΔG are proportional. That is, the relationship of V = ΔG / FM holds (where, F; Faraday coefficient, M; molecular weight). That is, as the potential V increases, ΔG increases and the power generation efficiency η also increases. As shown in FIG. 22, the fuel cell maintains a high potential almost always, and maintains a high power generation efficiency η.

The open circuit terminal voltage per fuel cell is in the range of 0.8 to 1.48V. The discharge of the positive electrode proceeds, and most of the composition thereof is manganese oxyhydroxide. When the pressure of the electrolytic solution is 0.1 MPa, the terminal voltage is 0.8 V. When the charge of the positive electrode proceeds and most of the composition thereof is manganese dioxide and the pressure of the electrolytic solution is a high pressure exceeding 10 MPa, the terminal voltage is 1.48 V.

Sixth Embodiment
FIG. 16 is a schematic cross-sectional view in the axial direction of a cylindrical stack reversible fuel cell according to a sixth embodiment of the present fuel cell. A cylindrically laminated fuel cell 71 (hereinafter simply referred to as a laminated cell) shown in FIG. 16 is mainly configured of an exterior body 75, a current collector 77, and an electrode body 73 housed inside the exterior body 75. It is equipped as an element. The exterior body 75 has a bottomed cylindrical can 72 and a disc-like lid member 76. The lid member 76 is attached to the opening 72 c of the cylindrical can 72. The cylindrical can 72 and the lid member 76 may be made of iron or other metals. The outer diameter of the lid member 76 is slightly larger than the inner diameter of the opening 72c of the cylindrical can 72, and after being housed in the electrode body 73, the lid member 76 is squeezed and fitted in the cylindrical can opening 72c.

The electrode body 73 includes a positive electrode 73a containing a positive electrode active material, a negative electrode 73b containing a negative electrode active material, and a separator 73c. The separator 73c is interposed between the positive electrode 73a and the negative electrode 73b, and transmits ions but does not transmit electrons. The positive electrode 73 a, the negative electrode 73 b, and the separator 73 c are stacked in the axial direction of the cylindrical can 72 (direction X in FIG. 16), and are accommodated in the exterior body 75. The electrolytic solution (not shown) is held by the separator 73c. Each of the positive electrode 73a, the negative electrode 73b, and the separator 73c has a disk shape with a hole in the center. The outer diameter 73ab of the positive electrode 73a is smaller than the inner diameter 72a of the cylindrical can 72. For this reason, the positive electrode 73a and the cylindrical can 72 are not in contact with each other. On the other hand, the outer diameter 73bb of the negative electrode 73b is larger than the inner diameter 72a of the cylindrical can 72. Therefore, the outer periphery 73bb of the negative electrode is in contact with the inner surface 72a of the cylindrical can 72. Thereby, the negative electrode 73 b and the cylindrical can 72 are electrically connected. The outer diameter 73bb of the negative electrode 73b may be larger than the inner diameter 72a of the cylindrical can 72 by 100 μm.

The material of the current collector 77 is a conductive material including nickel-plated iron. The nickel plating prevents the current collector 77 from being corroded by the electrolytic solution contained in the separator 73c. The current collector 77 has a rod-shaped shaft 77 a and a stopper 77 b disposed at one end of the shaft 77 a. The shaft portion 77a of the current collector 77 penetrates the center of the electrode body 73 including the positive electrode 73a, the negative electrode 73b, and the separator 73c in the axial direction (X direction in FIG. 16) of the exterior body 75. The diameter of the hole 73aa provided at the center of the positive electrode 73a is smaller than the outer diameter of the shaft portion 77a. For this reason, the positive electrode 73a is in contact with the shaft 77a and is electrically connected to the shaft 77a. On the other hand, the diameter of the hole 73ba provided at the center of the negative electrode 73b is larger than the outer diameter of the shaft portion 77a. For this reason, since the negative electrode 73b is not in contact with the shaft 77a, the negative electrode 73b is electrically insulated from the shaft 77a.

The electrode body 73 is disposed so as to be sequentially stacked on the stopping portion 77b of the current collector. The stopper 77 b prevents the electrode body 73 from falling off the end of the current collector 77. The shape of the stopper 77b is disk-like. The stopper 77b is disposed at the cylindrical can bottom 72b. An insulating plate 74 is disposed between the cylindrical can bottom 72b and the stopper 77b. This prevents the current collector 77 and the cylindrical can 72 from coming into contact with each other and causing an electrical short. An end of the shaft 77 a opposite to the stopper 77 b is supported by a bearing 78 provided at the center of the lid member 76. The bearing 78 has an insulating property to prevent an electrical short between the lid member 76 and the shaft 77a. The shaft portion 77 penetrating the lid member 76 functions as the positive electrode terminal 77 d. The cylindrical can 72 functions as a negative electrode terminal.

Next, the operation and effect of the sixth embodiment, in particular, the cooling effect will be described.
<About cooling structure>
The negative electrode 73 b is pressed strongly against the cylindrical can 72 and they are in close contact with each other. The heat generated at the negative electrode 73 b is directly transmitted to the cylindrical can 72 with little resistance. Further, the heat generated at the positive electrode 73a is transmitted to the negative electrode 73b through the separator 73c. The separator 73c is difficult to transfer heat, but is thin (10 μm in the present embodiment) and is only one sheet. For this reason, the separator 73c does not greatly impede the heat conduction. As described above, the heat generated by the

electrodes

73a and 73b is transferred to the cylindrical can 72 with a small thermal gradient. Thereby, it is possible to suppress the temperature rise inside the laminated battery.

Thus, the laminated battery can reduce the temperature rise in the central portion. For this reason, it is not necessary to provide a pipe or the like for flowing the refrigerant inside the battery. Furthermore, the exterior body 75 is exposed to the outside. For this reason, the laminated battery can suppress the temperature rise more effectively than the conventional wound battery. Here, the difference in temperature rise between the laminated battery according to the present embodiment and the conventional wound battery is shown using a calculation example.

The overall heat transfer coefficient (U ₁ ) of the wound battery is shown by equation ₁ . On the other hand, the overall heat transfer coefficient (U ₂ ) of the laminated battery according to the present invention is represented by Equation 2.

Here, calculation will be made by taking the 18650 type battery as an example. The specifications of the wound battery are
_{_{t = 0.5mm, t + = t}} - = t s = 10μm,
_{_{^{k = k + = k - =}}} 40Wm -2 deg -1,
h ₀ = 100 Wm ⁻² deg ⁻¹ , h ₁ = ¹ Wm ⁻² deg ⁻¹ ,
It is k _s = ¹ Wm ⁻² deg ⁻¹ , n = 9 / 0.03 = 300.
Substituting these values into Equation 1 yields U ₁ = 0.0011 Wm ⁻² deg ⁻¹ .

On the other hand, the specifications of the laminated battery according to the present embodiment are as follows:
h ₀ = 100 Wm ^-2 deg ^-1 , t = 0.5 mm, k = 40 Wm ^-2 deg ^-1
h ₁ = 10000 Wm ^-2 deg ^-1 , t ^* = 0.009 m,
It is k ^* = 40Wm- ² deg- ¹ .
Substituting these values into Equation 2, U ₂ = 100 Wm ⁻² deg ⁻¹ is obtained.

Comparing the two, it can be said that the laminated battery having the cooling structure according to the present invention is excellent in heat transfer by nearly 100,000 times as compared with the conventional wound battery.

(Modification of the sixth embodiment)
FIG. 17 is a schematic cross-sectional view in the axial direction of a pipe stack-type reversible fuel cell (hereinafter simply referred to as a pipe cell) according to a modification of the sixth embodiment of the present fuel cell. The pipe battery 81 shown in FIG. 17 includes an exterior body 85, a current collector 87, and an electrode body 83 housed inside the exterior body 85 as main components. The exterior body 85 has a circular tube 82 and a disc-like lid member 86. The lid member 86 is attached to the openings 82 b at both ends of the circular tube 82. The circular tube 82 and the lid member 86 may be made of iron or other metals. The outer diameter of the lid member 86 is slightly larger than the inner diameter of the opening 82 b of the circular pipe 82. After being stored in the electrode body 83, the lid member 86 is squeezed and fitted in the circular pipe opening 82b.

The electrode body 83 includes a positive electrode 83a containing a positive electrode active material, a negative electrode 83b containing a negative electrode active material, and a separator 83c. The separator 83c is interposed between the positive electrode 83a and the negative electrode 83b. The positive electrode 83a, the negative electrode 83b, and the separator 83c are stacked in the axial direction of the circular tube 82 (the X direction in FIG. 17), and are accommodated in the exterior body 85. The electrolytic solution (not shown) is held by the separator 83c. Each of the positive electrode 83a, the negative electrode 83b, and the separator 83c has a disk shape with a hole in the center. The outer diameter 83bb of the negative electrode 83b is smaller than the inner diameter 82a of the circular tube 82. For this reason, the negative electrode 83 b is not in contact with the circular tube 82. On the other hand, the outer diameter 83 ab of the positive electrode 83 a is larger than the inner diameter 82 a of the circular tube 82. For this reason, the positive electrode 83a is in contact with the inner surface 82a of the circular tube 82, and the positive electrode 83a is electrically connected to the circular tube 82. The outer diameter 83ab of the positive electrode 83a may be larger than the inner diameter 82a of the circular tube 82 by 100 μm.

The material of the current collector 87 is a conductive material including nickel-plated rod-like iron. The current collector 87 has a central portion shaft portion 87a and end portions 87b at both end portions. The shaft portion 87a of the current collector 87 penetrates the center of the electrode body 83 including the positive electrode 83a, the negative electrode 83b, and the separator 83c in the axial direction (X direction in FIG. 17) of the exterior body 85. The diameter of the hole 83ba provided in the negative electrode 83b is smaller than the outer diameter of the shaft portion 87a. For this reason, the negative electrode 83b is in contact with the shaft portion 87a and is electrically connected to the shaft portion 87a. On the other hand, the diameter of the hole 83aa provided in the positive electrode 83a is larger than the outer diameter of the shaft portion 87a. For this reason, since the positive electrode 83a is not in contact with the shaft portion 87a, the positive electrode 83a is electrically insulated from the shaft portion 87a.

The electrode body 83 is sequentially stacked in a skewed state on the shaft portion 87a of the current collector. Both end portions 87 b of the current collector 87 are supported by a bearing 88 provided at the center of the lid member 86. The bearing 88 has an insulating property. As a result, an electrical short circuit between the lid member 86 and the current collector 87 is prevented. The current collector end 87 b penetrating the lid member 86 functions as the negative electrode terminal 87 d. The circular tube 82 functions as a positive electrode terminal.

Seventh Embodiment
FIG. 18 is a schematic cross-sectional view in the axial direction of a cylindrical stack reversible fuel cell (hereinafter referred to as a donut cell) according to a seventh embodiment of the present fuel cell. The donut battery 41 shown in FIG. 18 is provided with an exterior body 45, a current collector 47, and an electrode body 43 housed inside the exterior body as main components. The exterior body 45 has a bottomed cylindrical outer structure 42 and a lid member 46. The lid member 46 is attached to the opening 42 c of the outer assembly 42. The structure 42 and the lid member 46 may include iron plated with nickel. The outer structure 42 and the cover member 46 each have a cylindrical side portion 42a or 46a and a bulging

portion

42b or 46b which bulges in a dome shape at the bottom. The lid member 46 is shorter than the outer assembly 42. The outer diameter of the lid member 46 is smaller than the inner diameter of the opening 42 c of the outer assembly 42. The lid member 46 is joined to the outer assembly 42 via the insulating seal member 48. The opening of the lid member 46 and the opening of the outer assembly 42 are opposed to each other. The insulating seal member 48 electrically insulates the outer structure 42 and the lid member 46. Furthermore, the insulating seal member 48 forms a sealed space inside the exterior body 45 by sealing the joint portion. The insulating seal member 48 is a substance having both insulating properties and sealing properties, and may be, for example, asphalt pitch.

The electrode body 43 includes a positive electrode 43a containing a positive electrode active material, a negative electrode 43b containing a negative electrode active material, and a separator 43c. The separator 43c is interposed between the positive electrode 43a and the negative electrode 43b. The positive electrode 43a, the negative electrode 43b, and the separator 43c are stacked in the axial direction of the outer body 42 (the X direction in FIG. 18), and are accommodated inside the exterior body 45. The electrolytic solution (not shown) is held by the separator 43c. Each of the positive electrode 43a, the negative electrode 43b, and the separator 43c has a disk shape with a hole in the center. The outer diameter 43aa of the positive electrode 43a is smaller than the inner diameter 42aa of the outer body 42. Therefore, the positive electrode 43a and the outer assembly 42 are not in contact with each other. On the other hand, the outer diameter 43 ba of the negative electrode 43 b is larger than the inner diameter 42 aa of the outer body 42. Therefore, the negative electrode 43 b is in contact with the inner surface 42 a of the outer body 42. Thus, the negative electrode 43 b is electrically connected to the outer assembly 42. The outer diameter 43 ba of the negative electrode 43 b may be larger than the inner diameter 42 aa of the outer body 42 by 100 μm.

The material of the current collector 47 is a conductive material including nickel-plated iron. The current collector 47 has a rod-like shaft 47 a and a stopper 47 b attached to one end of the shaft 47 a. The shaft portion 47a of the current collector 47 penetrates the center of the electrode body 43 including the positive electrode 43a, the negative electrode 43b, and the separator 43c in the axial direction of the exterior body 45 (X direction in FIG. 18). The diameter of the hole 43ab provided at the center of the positive electrode 43a is smaller than the outer diameter of the shaft portion 47a. Therefore, the positive electrode 43a is in contact with the shaft 47a and is electrically connected to the shaft 47a. On the other hand, the diameter of the hole 43bb provided at the center of the negative electrode 43b is larger than the outer diameter of the shaft portion 47a. For this reason, since the negative electrode 43b is not in contact with the shaft portion 47a, the negative electrode 43b is electrically insulated from the shaft portion 47a.

The electrode body 43 is disposed so as to be sequentially stacked on the stop portion 47b of the current collector. The stopper 47 b prevents the electrode body 43 from falling off the end of the current collector 47. Insulating push plates 44 a are disposed at both ends of the stacked electrode bodies 43. The pressing plate 44 a prevents the electrode body 43 from being damaged when the electrode body 43 is stacked and pressed. The material of the pressing plate 44a may be any material suitable as an insulating material and a structural material. This material comprises, for example, polypropylene. The shape of the stopper 47b is disk-like. The stopper 47 b is not in contact with the bulging portion 42 b at the bottom of the outer assembly. For this reason, the stop portion 47b and the outer assembly 42a are electrically insulated. The stopper 47 b and the opposite end 47 c of the shaft 47 a pass through a hole 46 d provided at the center of the lid 46 and project outward (rightward in the drawing) of the lid 46. The shaft portion 47c penetrating the lid member 46 functions as a positive electrode terminal. The outer structure 42 functions as a negative electrode terminal. A hydrogen storage chamber 49 is provided in the inner space of the bulging

portions

42 b and 46 b. That is, the hydrogen storage chamber 49 is disposed in the space inside the exterior body surrounded by the inner surfaces 42 ba and 46 ba of the bulging portion and the electrode body 43.

The fuel cell can be suitably used as an industrial or consumer storage device.

DESCRIPTION OF SYMBOLS 1 negative electrode case 2 positive electrode case 3 electrolyte solution 4 negative electrode 5 separator 6 positive electrode 7 oxygen storage chamber 8 hydrogen storage chamber 9 wall member 10 exterior body 11 negative electrode terminal 13 electrolyte solution 14 negative electrode 15 separator 16 positive electrode 17 insulating member 18 hydrogen storage chamber 19 oxygen Storage room 25 Current collecting plate 27 Blower fan 28 Hydrogen flow port 29 Connection part 30 Oxygen flow port 31 Connection part 32 Insulating connection member 33 Insulating connection member 34 Conductive connection member 35 Hydrogen gas first header 36 Oxygen gas first header 38 Hydrogen gas Second header 39 Oxygen gas second header 41 Donut battery 42 Outer structure (a: side, b: bulging part)
43 electrode body (a: positive electrode, b: negative electrode, c: separator)
44: Push plate 45: Exterior body 46: Lid member 47: Current collector (a: shaft, b: stop, c: screw, d: end)
48 insulation sealing member 49 hydrogen storage room 51 negative case 52 positive case 53 electrolyte 54 negative electrode 55 separator 56 positive electrode 58 hydrogen storage room 59 oxygen storage room 61 protective casing 62 insulating casing 63 negative terminal 64 positive terminal 65 step 66 step 67 insulation 67 68 lid member 69 lid member 70 mounting bolt 474 wire 476 circuit breaker 477 busbar
478 tower 71 laminated battery 72 cylindrical can (a: side inner surface)
73 electrode body (a: positive electrode, b: negative electrode, c: separator)
74 insulating plate 75 exterior body 76 lid member 77 current collector (a: shaft portion, b: stop portion, c: screw portion, d: positive electrode terminal)
78 bearing 81 pipe battery 82 circular pipe (a: inner surface)
83 Electrode body (a: positive electrode, b: negative electrode, c: separator)
85 exterior body 86 lid member 87 current collector 88 bearing 100 outer shell 101 body 102 bulging portion 103 packing 110 positive electrode 120 negative electrode 121 hydrogen gas storage source 130 separator 134 current collector 135 partition plate 136a and b oxygen storage chamber 137 electrolysis Liquid 138

Hydrogen storage chamber

211, 212

Flange

220, 221, 222 Piping 230 Salt concentration adjustment device 233 Reverse osmosis membrane 250 Oxygen concentration adjustment device 251 Oxygen storage source 260 Cooler 270 Pump 300 Exterior body 301 Circular tube 302 Lid member 310 Current collection Body 311 Nut 320 Positive electrode 321 Notch 330 Negative electrode 331 Gap 340

Separators

351, 352, 353 PP packing 365 Electrolyte inlet 361 Electrolyte supply source 363 Electrolyte adjustment chamber 364 Discharge passage 366 Electrolyte outlet 371 Hydrogen gas storage source 372 Hydrogen gas storage aisle 373 Hydrogen gas supply port 380 Hydrogen gas storage room

Claims

A positive electrode containing manganese dioxide,
A negative electrode containing a hydrogen storage material,
A separator interposed between the positive electrode and the negative electrode;
With electrolyte and
The reversible fuel cell, wherein the negative electrode and the positive electrode are electrodes for power generation, and are electrodes that electrolyze the electrolytic solution using an externally supplied current.
The discharge reactions of the negative electrode and the positive electrode are represented by Formula (1) and Formula (3), respectively,
The reversible fuel cell according to claim 1, wherein the charge reaction of the negative electrode and the positive electrode is represented by Formula (2) and Formula (4), respectively.
MH → M + H + + e - (1)
M + 1 / 2H 2 → MH (2)
MnO 2 + H + + e - → MnOOH (3)
MnOOH + O 2 → MnO 2 + H 2 O (4)
However, in formulas (1) and (2), M represents a hydrogen storage material.
And are H 2 is hydrogen of the formula (2), a oxygen O 2 in the formula (4) is dissolved in the electrolyte, reversible fuel cell according to claim 2.
4. The reversible fuel cell according to claim 3, further comprising a first oxygen storage chamber for holding an electrolyte solution in which oxygen is dissolved, and a hydrogen storage chamber for holding hydrogen gas.
The reversible fuel cell according to claim 4, wherein the first oxygen storage chamber and the hydrogen storage chamber are separated by a movable member.
The reversible fuel cell according to claim 5, wherein the movable member is a flexible member.
The reversible fuel cell according to claim 6, wherein the flexible member comprises the positive electrode, the negative electrode and a separator.
The cylindrical positive electrode and the cylindrical negative electrode are disposed inside the cylindrical case via a radial space via the separator, and are in contact with the surface of the positive electrode opposite to the separator. And the hydrogen storage chamber is formed in contact with the surface of the negative electrode opposite to the separator.
The first oxygen storage chamber is disposed in the radial space, and the hydrogen storage chamber is disposed inward of the negative electrode, or
The hydrogen storage chamber is disposed in the radial space, and the first oxygen storage chamber is disposed inward of the positive electrode.
A reversible fuel cell according to claim 4.
A negative electrode terminal electrically connected to the negative electrode provided at one axial end of the case;
A positive electrode terminal electrically connected to the positive electrode, provided at the other axial end of the outer package;
A projection provided on any one of the positive electrode terminal and the negative electrode terminal;
And a hole provided in the other of the positive electrode terminal and the negative electrode terminal,
The reversible fuel cell according to claim 8, wherein the protrusion and the hole can be fitted such that two reversible fuel cells are connected in series.
Has multiple battery units connected in series,
This battery unit is
A plurality of reversible fuel cells according to claim 9;
And a pair of current collectors provided opposite to each other so as to sandwich the plurality of reversible fuel cells,
By connecting the positive electrode terminal to the one current collector plate and connecting the negative electrode terminal to the other current collector plate, the plurality of reversible fuel cells are mutually connected via the current collector plate. Connected in parallel,
Reversible fuel cell module.
An outer shell having a cylindrical body portion, and a bulging portion disposed at both end openings of the body portion and bulging outward of the opening portion to cover the opening portion;
The first oxygen storage chamber provided in the inner space of the bulging portion inside the outer shell;
A tube-like current collector housed axially along the inside of the outer shell and having both ends open to the first oxygen storage chamber;
And further
The positive electrode is disposed on the outer periphery of the current collector,
The separator covers the periphery of the positive electrode,
The hydrogen storage chamber is formed between the separator and the shell;
The negative electrode is filled in the hydrogen storage chamber;
The electrolytic solution is stored inside the first oxygen storage chamber, and can pass between the first oxygen storage chamber through the current collector.
A reversible fuel cell according to claim 4.
An exterior body having a tubular body;
And a rod-like current collector penetrating the positive electrode, the negative electrode, and the separator,
The positive electrode, the negative electrode, and the separator are stacked in the axial direction of the body portion, and are accommodated inside the exterior body,
The positive electrode has a notch formed by cutting off a part of the outer periphery, and the outer periphery of the positive electrode is in contact with the inner surface of the body except for the notch.
The positive electrode is not in contact with the current collector,
The negative electrode has a U-shaped cross section opening in the inner circumferential direction, and the negative electrode and the current collector are in contact with each other,
A space surrounded by the negative electrode and the current collector forms the hydrogen storage chamber,
An outer diameter of the negative electrode is smaller than an inner dimension of the body portion, and an electrolytic solution reservoir communicating with the cutout portion is provided between the negative electrode and the body portion,
5. The reversible fuel cell according to claim 4, wherein the first oxygen storage chamber includes the notch and the electrolyte reservoir.
A reversible fuel cell according to claim 11 or 12, and an oxygen storage source and a hydrogen storage source connected to the fuel cell,
The oxygen storage source is capable of supplying oxygen dissolved in oxygen gas or electrolyte to the reversible fuel cell, and storing oxygen gas generated in the reversible fuel cell dissolved in gas state or electrolyte. Is possible and
The reversible fuel cell system, wherein the hydrogen gas storage source can supply hydrogen gas to the reversible fuel cell and can store hydrogen gas generated by the reversible fuel cell.
A reversible fuel cell according to claim 11 or 12;
A salt concentration adjusting device connected to the reversible fuel cell for removing water contained in the electrolyte;
An oxygen concentration adjusting device connected to the reversible fuel cell to adjust the dissolved oxygen concentration by supplying oxygen to the electrolyte;
And a reversible fuel cell system.
And are H 2 is hydrogen of the formula (2), a O 2 is the oxygen gas of the formula (4), reversible fuel cell according to claim 2.
A hydrogen storage chamber provided in contact with the negative electrode for storing hydrogen gas generated at the negative electrode or supplying hydrogen gas to the negative electrode;
A second oxygen storage chamber provided in contact with the positive electrode, for storing oxygen gas generated at the positive electrode or supplying oxygen to the positive electrode;
The reversible fuel cell according to claim 15, comprising:
The negative electrode includes a material having hydrophilicity disposed on the surface contacting the separator, and a material having hydrophobicity disposed on the surface contacting the hydrogen storage chamber, and / or
The positive electrode includes a hydrophilic material disposed on a surface in contact with the separator, and a hydrophobic material disposed on a surface in contact with the second oxygen storage chamber.
A reversible fuel cell according to claim 16.
The reversible fuel cell according to claim 16, wherein the electrolyte is held in the second oxygen storage chamber.
The cylindrical positive electrode and the cylindrical negative electrode are disposed inside the cylindrical outer package via a radial space with the separator interposed therebetween, and are in contact with the surface of the positive electrode opposite to the separator. As described above, the second oxygen storage chamber is formed, and the hydrogen storage chamber is formed to be in contact with the surface of the negative electrode opposite to the separator.
The second oxygen storage chamber is disposed in the radial space, and the hydrogen storage chamber is disposed inward of the negative electrode, or
The reversible fuel cell according to claim 16, wherein the hydrogen storage chamber is disposed in the radial space, and the second oxygen storage chamber is disposed inward of the positive electrode.
A negative electrode terminal electrically connected to the negative electrode provided at one axial end of the outer package;
A positive electrode terminal electrically connected to the positive electrode, provided at the other axial end of the outer package;
A projection provided on any one of the positive electrode terminal and the negative electrode terminal;
And a hole provided in the other of the positive electrode terminal and the negative electrode terminal,
20. The reversible fuel cell according to claim 19, wherein the projection and the hole can be fitted such that two reversible fuel cells are connected in series.
Has multiple battery units connected in series,
This battery unit is
A plurality of reversible fuel cells according to claim 20,
And a pair of current collectors provided opposite to each other so as to sandwich the plurality of reversible fuel cells,
By connecting the positive electrode terminal to the one current collector plate and connecting the negative electrode terminal to the other current collector plate, the plurality of reversible fuel cells are mutually connected via the current collector plate. Connected in parallel,
Reversible fuel cell module.
An oxygen gas flow port communicating with the second oxygen storage chamber;
And a hydrogen gas flow port communicating with the hydrogen storage chamber;
The reversible fuel cell of claim 18, wherein the hydrogen gas in the hydrogen storage chamber and the oxygen gas in the second oxygen storage chamber can be separately taken out of the reversible fuel cell.
A plurality of reversible fuel cells according to claim 22 connected together.
A first hydrogen gas pipe including an electrical conductor, having a connection portion airtightly connectable to the hydrogen gas flow port;
A first oxygen gas pipe including an electrical conductor, having a connection portion airtightly connectable to the oxygen gas flow port,
The first hydrogen gas pipe is connected to a second hydrogen gas pipe via an insulator.
The first oxygen gas pipe is connected to a second oxygen gas pipe via an insulator.
The adjacent first oxygen gas pipe and the first hydrogen gas pipe are electrically connected by a conductor,
The second hydrogen gas pipe is connected to the hydrogen gas tank, and
The second oxygen gas pipe is connected to the oxygen gas tank,
Reversible fuel cell bank.
A negative electrode case disposed in contact with the negative electrode and opposed to the positive electrode;
And a positive electrode case disposed in contact with the positive electrode and disposed to face the negative electrode,
The negative electrode and the positive electrode are provided to face each other via the separator.
The hydrogen storage chamber is formed in a space between the negative electrode case and the negative electrode,
The reversible fuel cell according to claim 15, wherein the second oxygen storage chamber is formed in a space between the positive electrode case and the positive electrode.
A plurality of reversible fuel cells according to claim 24, connected in series with one another.
A positive electrode terminal in contact with the positive electrode of the reversible fuel cell connected in series;
A negative electrode terminal in contact with the negative electrode of the reversible fuel cell connected in series;
The positive electrode case of the reversible fuel cell and the negative electrode case of the reversible fuel cell adjacent to each other are disposed in contact with each other.
Reversible fuel cell module.
26. A reversible fuel cell module according to claim 25, a metal wire, a structure, a circuit breaker capable of opening and closing, and a bus bar,
One end of the metal wire is attached to the reversible fuel cell module, and the other end of the wire is attached to the structure, whereby a plurality of the reversible fuel cell modules are the structure Can be hung on the
A reversible fuel cell bank, in which the positive electrode terminal and the negative electrode terminal of the adjacent reversible fuel cell modules are connected by the bus bar via the circuit breaker.
The reversible fuel cell according to claim 2, wherein the manganese dioxide functions as a catalyst for the charge reaction at the positive electrode, and the hydrogen storage material functions as a catalyst for the charge reaction at the negative electrode.
The reversible fuel cell according to claim 2, wherein the positive electrode further contains manganese dioxide in addition to manganese dioxide.
The reversible fuel cell according to claim 2, wherein the content of trimanganese tetraoxide (Mn 3 O 4 ) contained in the positive electrode is 5% by weight or less based on the weight of the positive electrode.
The reversible fuel cell according to claim 2, wherein the content of manganese dioxide contained in the positive electrode is in the range of 20 to 99.8 wt% based on the weight of the positive electrode.
The reversible fuel cell according to claim 2, wherein the mean particle size of manganese dioxide contained in the positive electrode is in the range of 1 to 100 μm.
The reversible fuel cell according to claim 2, wherein manganese dioxide contained in the positive electrode is carbon-coated.
The reversible fuel cell according to claim 2, wherein the hydrogen storage material comprises a hydrogen storage alloy or at least one metal selected from the group consisting of Sc, Ti, V, Cr, Mn, Fe, Co and Ni. .
The reversible fuel cell according to claim 2, wherein the separator comprises a microporous membrane in the range of 0.1 to 10 μm in average pore size.
The said negative electrode contains the material which has hydrophilicity distribute | arranged to the surface which contact | connects the said separator, and the material which has hydrophobicity distribute | arranged to the surface which contact | connects the said hydrogen storage chamber. Reversible fuel cell.
The reversible fuel cell according to claim 2, wherein the electrolyte contains a thickener.
The reversible fuel cell according to claim 2, wherein the open circuit terminal voltage is in the range of 0.8 to 1.48V.
Exterior body,
And a current collector penetrating the positive electrode, the negative electrode, and the separator in the axial direction of the package.
One of the positive electrode and the negative electrode is a first electrode which is in contact with the inner surface of the outer package and electrically connected to the inner surface.
Either the positive electrode or the negative electrode is a second electrode not in contact with the inner surface of the outer package,
The reversible fuel according to claim 1, wherein the second electrode is in contact with and electrically connected to the current collector, while the first electrode is not in contact with the current collector. battery.
The reversible fuel cell according to claim 38, wherein the outer package has a cylindrical metal body.
The side of the exterior body is substantially cylindrical, and
The exterior body has a bulging portion that bulges in a dome shape at both axial ends thereof.
40. The reversible fuel cell of claim 39.
41. The reversible fuel cell according to claim 40, further comprising: a hydrogen storage chamber provided in an inner space of the dome-like bulging portion of the outer package, for storing hydrogen gas generated at the negative electrode.