JP6771965B2 - Metal-air batteries and metal-air batteries - Google Patents

Description

The present invention relates to a metal-air battery having a housing for accommodating a positive electrode and a negative electrode, and a metal-air battery in which a plurality of metal-air batteries are connected.

In recent years, various batteries using the chemical reaction of metal for electrodes have been put into practical use, and one of them is a metal-air battery. A metal-air battery is composed of an air electrode (positive electrode), a fuel electrode (negative electrode), an electrolyte (or an electrolytic solution), etc., and is subjected to an electrochemical reaction to produce zinc, iron, magnesium, aluminum, sodium, calcium, etc. And the electrical energy obtained in the process of converting a metal such as lithium into a metal oxide is extracted and used.

Further, in a metal-air battery, it has been proposed to provide a three-pole rechargeable air battery by providing an auxiliary pole in addition to the air electrode and the fuel electrode (see, for example, Patent Document 1).

Special Table 2013-505544

The rechargeable electrochemical cell system described in Patent Document 1 is composed of a plurality of electrochemical cells including a fuel electrode, an oxidizing agent electrode, and a charging electrode, and has an oxidizing agent for the fuel electrode of a subsequent cell. It has a switch to switch between the pole and the charging pole. In this configuration, there are two contacts, the oxidizing agent electrode and the charging electrode, but there is a concern that a failure may occur at the contacts. Further, advanced control such as switching between two contacts as appropriate is required, and there is a problem that the control system becomes complicated.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a metal-air battery and a metal-air battery that can switch between charging and discharging with a simple configuration.

The metal air cell according to the present invention is connected to a positive electrode for discharging, a positive electrode for charging, a negative electrode, a positive electrode output unit in which the positive electrode for discharging and the positive electrode for charging are connected in parallel, and the negative electrode. A metal air battery including a negative electrode output portion, the positive electrode for discharging and the positive electrode for charging are provided with a branch point between the positive electrode for discharging and the positive electrode for charging, and the positive electrode for discharging and the branching are provided. only between the points, one switch unit is provided for opening and closing the connection, the switch unit is composed of at least one MOSFET is turned off in the charging state, is turned on in the discharge state, the MOSFET The parasitic diode is characterized in that the anode is located on the side of the positive electrode for discharging and the cathode is located on the side of the branch point .

In the metal-air battery according to the present invention, the positive electrode for charging may generate oxygen in the charged state, and the positive electrode for discharging may be configured to consume oxygen in the discharged state.

In the metal-air battery according to the present invention, the positive electrode for charging may have a porous shape having three-dimensionally communicating pores.

In the metal-air battery according to the present invention, the MOSFET may be configured to be a P-channel MOSFET.

The metal-air battery according to the present invention, the P-channel MOSFET has a drain connected to the positive electrode for the discharge may be configured to source connected to the positive electrode output section.

The metal-air battery according to the present invention, the switch unit has two P-channel MOSFET, the two P-channel MOSFET is connected to the facing drain of each other, one source is the positive output The configuration may be such that the other source is connected to the positive electrode for discharging .

In the metal-air battery according to the present invention, the MOSFET may be configured to be an N-channel MOSFET.

The metal-air battery according to the present invention, the N-channel MOSFET has a source connected to the positive electrode for the discharge may be configured to drain is connected to the positive electrode output section.

The metal-air battery according to the present invention, the switch unit has two N-channel MOSFET, the two N-channel MOSFET is connected to the facing to each other of the source, one drain said positive output A configuration may be configured in which the drain is connected to the portion and the other drain is connected to the positive electrode for discharging .

The metal-air battery according to the present invention is characterized by including a plurality of metal-air batteries according to the present invention.

According to the present invention, charging / discharging can be switched by one switch unit provided on the positive electrode side, and mechanical failure can be suppressed by using a simple configuration.

It is a schematic block diagram of the metal-air battery which concerns on 1st Embodiment of this invention. It is a schematic diagram which shows the metal-air battery connected through the switch part. It is a schematic diagram which shows the metal-air battery in the discharged state. It is a schematic diagram which shows the metal-air battery in a charged state. It is a schematic diagram of the metal-air battery which concerns on 2nd Embodiment of this invention. It is a schematic diagram which shows the modification 1 of the 2nd Embodiment. It is a schematic diagram of the metal-air battery which concerns on 3rd Embodiment of this invention. It is a schematic diagram which shows the modification 2 of the 3rd Embodiment.

(First Embodiment)
Hereinafter, the metal-air battery according to the first embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic configuration diagram of a metal-air battery according to the first embodiment of the present invention.

The metal-air battery 1 has a structure in which a discharge positive electrode 3 (air electrode), a charging positive electrode 4 (auxiliary electrode), and a negative electrode 5 (fuel electrode) are housed in a housing 2. Air intake ports 2a for taking in air from the outside are formed on the two opposite side surfaces of the housing 2 so as to open the inside. Two discharge positive electrodes 3 are provided along each of the two side surfaces on which the air intake port 2a is formed. The negative electrode 5 is provided substantially in the center between the two discharged positive electrodes 3, and the charged positive electrode 4 is provided at two locations between the two discharged positive electrodes 3 and the negative electrode 5. That is, in the present embodiment, the discharge positive electrode 3 and the charge positive electrode 4 are provided on both side surfaces of the negative electrode 5 provided in the center, respectively. The arrangement of each electrode is not limited to this, and the discharge positive electrode 3 and the charge positive electrode 4 may be provided on one surface of the negative electrode 5, and the discharge positive electrode 3, the charge positive electrode 4, and the negative electrode 5 may be arranged in this order. Also, the discharge positive electrode 3, the negative electrode 5, and the charge positive electrode 4 may be arranged in this order.

In addition to the electrodes of the discharged positive electrode 3, the charged positive electrode 4, and the negative electrode 5, the housing 2 further houses the electrolytic solution 10 and the separator 9. The electrolytic solution 10 is a liquid in which the electrolyte is dissolved in a solvent and has ionic conductivity. The type of the electrolytic solution 10 varies depending on the type of the electrode active material contained in the negative electrode 5, but may be an aqueous electrolyte solution using an aqueous solvent. As the electrolytic solution 10, for example, when the electrode active material of the negative electrode 5 is zinc, aluminum, and iron, an alkaline aqueous solution such as an aqueous sodium hydroxide solution and an aqueous potassium hydroxide solution can be used, and the electrode active material is magnesium. In this case, an aqueous solution of sodium chloride can be used. An organic additive or an inorganic additive other than the electrolyte may be added to the electrolytic solution 10, or the electrolytic solution 10 may be gelled by a polymer additive.

The separator 9 is arranged between the electrodes to prevent an electron conduction path from being formed between the electrodes to cause a short circuit, and is made of an insulating material. The separator 9 suppresses, for example, metal dendrites reduced and precipitated at the negative electrode 5 during charging reach the discharged positive electrode 3 and the charged positive electrode 4 and short-circuit. As the separator 9, for example, a solid electrolyte sheet such as a porous resin sheet or an ion exchange membrane can be used, and ion conduction occurs through the separator 9.

The discharge positive electrode 3 is a porous electrode having an air electrode catalyst. The discharge positive electrode 3 may have a structure having a porous gas diffusion layer and a porous air electrode catalyst layer provided on the gas diffusion layer. In the discharge positive electrode 3, when an alkaline aqueous solution is used as the electrolytic solution 10, the water supplied from the electrolytic solution 10 or the like on the air electrode catalyst, the oxygen gas supplied from the atmosphere, and the electrons react with each other to cause a hydroxide. A discharge reaction that produces ions occurs. That is, at the air electrode, the discharge reaction proceeds at the three-phase interface where oxygen (gas phase), water (liquid phase), and electron conductor (solid phase) coexist. The reaction at each electrode will be described in detail with reference to FIGS. 3A and 3B described later.

The discharge positive electrode 3 includes a discharge positive electrode current collector 6 made of a porous and electron-conducting material. When an alkaline aqueous solution is used as the electrolytic solution 10, the discharge positive electrode current collector 6 is nickel-plated on the surface of a metal material such as nickel or stainless steel from the viewpoint of corrosion resistance and catalytic ability for discharge reaction. Materials are suitable.

The charging positive electrode 4 is a porous electrode, and when an alkaline aqueous solution is used as the electrolytic solution 10, a reaction occurs in which oxygen, water, and electrons are generated from hydroxide ions (charging reaction). From the viewpoint of solubility resistance in the discharged state, the charged positive electrode 4 is preferably formed into a porous shape having pores communicating three-dimensionally (three-dimensionally), and is formed of, for example, foamed metal. Further, it is desirable that the charging positive electrode 4 is made of a nickel material from the viewpoint of catalytic ability for the charging reaction and corrosion resistance for the charging reaction and the discharging reaction. The charging positive electrode 4 includes a charging positive electrode current collector 7 similar to the discharging positive electrode current collector 6 of the discharging positive electrode 3.

The negative electrode 5 is an electrode formed of an active material containing a metal element, and an oxidation reaction of the active material occurs during discharge and a reduction reaction occurs during charging. As the metal element, zinc, lithium, sodium, calcium, magnesium, aluminum, iron and the like are used. Further, the active material may be a metal in a reduced state or an oxidized state. For example, when the metal element is zinc, it is metallic zinc in the reduced state and zinc oxide in the oxidized state. Further, the negative electrode 5 is provided with a negative electrode current collector 8, and it is desirable to use a material obtained by plating the surface of a metal material such as nickel or stainless steel with a material having a high hydrogen overvoltage.

FIG. 2 is a schematic view showing a metal-air battery connected via a switch unit.

The metal-air battery 1 includes a positive electrode output unit 11 connected to the discharged positive electrode 3 and the charged positive electrode 4, and a negative electrode output unit 12 connected to the negative electrode 5, via the positive electrode output unit 11 and the negative electrode output unit 12. It is connected to the outside and another metal-air battery 1. When the metal-air battery 1 is provided with two discharged positive electrodes 3 and two charged positive electrodes 4, for example, the two discharged positive electrodes 3 may be connected to each other by a power line or the like and connected to the positive electrode output unit 11, and the charged positive electrode 4 may be connected. May be the same.

As shown in FIG. 2, a switch unit 13 for opening and closing the connection is provided between the discharged positive electrode 3 and the positive electrode output unit 11. The switch unit 13 is composed of a mechanical relay, and utilizes the magnetic force generated by energizing the coil on the input side to make the contacts on the output side contact and non-contact with physical metal parts on the load side. Controls the opening and closing of the circuit. By using physical parts in this way, the circuit can be reliably cut off.

Next, the operation of the metal-air battery 1 and the flow of current when the switch unit 13 is opened and closed will be described.

FIG. 3A is a schematic view showing a metal-air battery in a discharged state.

In the discharged state, the switch unit 13 is turned on (short-circuited). In the discharged state, as indicated by the arrow A, a current flows from the negative electrode output unit 12 toward the positive electrode output unit 11.

In the present embodiment, zinc is used as the active material of the negative electrode 5, and the reaction at the negative electrode 5 in this case will be described below. In the negative electrode 5, ^{"Zn + 4OH - → Zn (OH} ) 4 2- + 2e - " and if oxidized zinc as dissolved as zincate ions in the electrolyte solution 10, ^{"Zn + 2OH - → ZnO + H} 2 O + 2e - " or "Zn + 2OH _{^{- → Zn (OH) 2 +}} 2e - "and a case where zinc oxide or zinc hydroxide is produced as. Further, zincate ions, ^{_{"Zn (OH) 4 2- → ZnO}} + 2OH - + H 2 O " and ^{_{"Zn (OH) 4 2- → Zn}} (OH) 2 + 2OH - " by the reaction, such as zinc oxide or hydroxide It may precipitate as zinc in the electrolytic solution 10.

In the discharge positive electrode 3, _{"O 2 + 2H 2 O + 4e} - → 4OH - " reactions consuming the oxygen takes place as. Further, even in the discharged state, the charging positive electrode 4 and the positive electrode output unit 11 are directly connected.

When nickel is used for the charging positive electrode 4, the charging positive electrode 4 which becomes nickel dioxide (NiO ₂ ) during charging becomes the same potential as the discharging positive electrode 3 in the discharged state, so that reduction proceeds and the oxidation number decreases. or a Ni ₃ O _4, HNiO ₂ ^- with or dissolved as the charging positive electrode 4 is likely to be deteriorated. However, if the charging positive electrode 4 is made of a porous material having pores that communicate three-dimensionally, the specific surface area of the charging positive electrode 4 becomes large, and the amount of nickel dioxide generated during charging can be increased. also progressed reduction reaction, remains in the oxidation number of reduction to Ni ₃ O _4, HNiO ₂ ^- it is possible to suppress the degradation reactions which dissolves as.

FIG. 3B is a schematic view showing a metal-air battery in a charged state.

In the charged state, the switch unit 13 is turned off (open). In the charged state, as indicated by arrow B, a current flows from the positive electrode output unit 11 to the negative electrode output unit 12.

In the negative electrode 5, ^{_{"Zn (OH) 4 2- + 2e}} - → Zn + 4OH - ", ^{_{"ZnO + H 2 O + 2e -}} → Zn + 2OH - ", and ^{_{"Zn (OH) 2 + 2e -}} → Zn + 2OH - " as in the discharge state and reverse Reaction occurs. That is, zinc may be produced by the reduction of zincate ions dissolved in the electrolytic solution 10, or zinc oxide or zinc hydroxide may be reduced to zinc.

In the charging positive electrode 4, _{^{"2OH - → 1 / 2O 2 +}} H 2 O + 2e - " reaction that produces an oxygen occurs as.

In the discharge positive electrode 3, since the switch unit 13 is turned off, the current does not flow from the positive electrode output unit 11 to the discharge positive electrode 3 and does not react. If, using manganese dioxide and carbon as an electrode material of the discharge positive electrode 3, when the switch unit 13 is turned on state of charge ^{_{"MnO 2 + 4OH - → MnO 4}} 2- + 2H 2 O + 2e - " or "C + 4OH ^{_{- → CO 2 + 2H 2 O}} + 4e - "reaction occurs such, oxidation of the electrode material occurs.

As described above, in the present embodiment, charging / discharging can be switched by one switch unit 13 provided on the positive electrode side, and a simple configuration with one contact allows mechanical failure. It can be suppressed.

Further, by using the charged positive electrode 4 having a porous shape that communicates three-dimensionally, deterioration due to the dissolution reaction of the charged positive electrode 4 in the discharged state can be suppressed.

By the way, oxygen accumulated in the vicinity of the charging positive electrode 4 during charging obstructs the ion conduction path between the negative electrode 5 and the discharging positive electrode 3 during discharging, and has a problem that the discharging performance is deteriorated. On the other hand, in the present embodiment, since the switch unit 13 is arranged only between the positive electrode output unit 11 and the discharged positive electrode 3, the charged positive electrode 4 and the discharged positive electrode 3 have the same potential in the discharged state. .. As a result, oxygen is accumulated in the vicinity of the charging positive electrode 4 is in a discharged state, _{"O 2 + 2H 2 O + 4e} - → 4OH - " over charging the positive electrode 4 to be consumed as a discharge performance by storing oxygen Can be solved.

Although one metal-air battery 1 is shown in FIG. 2, a plurality of metal-air batteries 1 may be connected to form a metal-air battery. For example, when the metal-air battery 1 is connected in series, the metal-air battery is configured by connecting the positive electrode output unit 11 and the negative electrode output unit 12 in order to the adjacent metal-air battery 1.

(Second Embodiment)
Next, the metal-air battery according to the second embodiment of the present invention will be described with reference to the drawings. In the second embodiment and the third embodiment shown below, the switch unit 13 has a different configuration from the first embodiment, and the structure of the housing 2 and the like is the same as that of FIG. Therefore, the drawing is omitted.

FIG. 4 is a schematic view of the metal-air battery according to the second embodiment of the present invention. The components having substantially the same functions as those of the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

In the second embodiment, the switch unit 13 is composed of a P-channel MOSFET 21 (an example of MOSFET). In the P channel MOSFET 21, the drain 21D is connected to the discharge positive electrode 3, and the source 21S is connected to the positive electrode output unit 11. A signal from the control circuit 14 is input to the gate 21G of the P-channel MOSFET 21, and the switch unit 13 can be switched on and off. Since MOSFETs do not have mechanical contacts, they are quiet, have a long life, are compact, and can be safely and repeatedly turned on and off.

As the P-channel MOSFET 21, an enhancement type P-channel MOSFET and a depletion type P-channel MOSFET can be used. From the viewpoint of safety, a normally-off enhancement type P so that the current path between the positive electrode output unit 11 and the discharge positive electrode 3 is cut off when a failure occurs in which the gate voltage is not applied. It is desirable to use a channel MOSFET.

Further, since the P channel MOSFET 21 causes power loss due to the on resistance at the time of discharging, it is desirable to use the P channel MOSFET 21 having a small on resistance, and the on resistance is preferably 10 mΩ or less, more preferably 5 mΩ or less. desirable. It is desirable that the structure of the P-channel MOSFET 21 is a trench gate structure capable of increasing the channel density and reducing the on-resistance.

Further, when the P-channel MOSFET 21 is used, the switching signal voltage can be generated without providing the charge pump circuit and the bootstrap circuit required when the N-channel MOSFET is used, and the control circuit is simplified. , Power consumption can be reduced.

The P-channel MOSFET 21 has a parasitic diode (body diode 22 of the P-channel MOSFET 21). Specifically, in the body diode 22, the anode is located on the discharge positive electrode 3 side, and the cathode is located on the positive electrode output portion 11 side. By connecting in the above-described direction, the forward direction of the body diode 22 is the direction from the discharged positive electrode 3 to the positive electrode output unit 11. As a result, at the time of charging, a current flows from the positive electrode output unit 11 to the discharged positive electrode 3 via the body diode 22 to avoid charging the discharged positive electrode 3, so that the discharged positive electrode 3 due to the decomposition of the catalyst can be avoided. Deterioration can be prevented.

FIG. 5 is a schematic view showing a modification 1 of the second embodiment.

The first modification is different from the structure shown in FIG. 4 in that the switch unit 13 is composed of two P-channel MOSFETs 21. Specifically, in the two P-channel MOSFETs 21, the drains 21D of each other are connected to face each other, one source 21S is connected to the positive electrode output unit 11, and the other source 21S is connected to the discharge positive electrode 3. .. A control circuit 14 is connected to the gate 21G of the two P-channel MOSFETs 21. Therefore, since the directions of the body diodes 22 in the two P-channel MOSFETs 21 are different, the current flowing through the body diode 22 can be reliably cut off regardless of the direction in which the current flows. Can be done.

(Third Embodiment)
FIG. 6 is a schematic view of the metal-air battery according to the third embodiment of the present invention. The components having substantially the same functions as those of the first embodiment and the second embodiment are designated by the same reference numerals and the description thereof will be omitted.

The third embodiment has substantially the same configuration as the second embodiment, except that the switch unit 13 is composed of an N-channel MOSFET 23 (an example of MOSFET). In the N-channel MOSFET 23, the source 23S is connected to the discharge positive electrode 3, the drain 23D is connected to the positive electrode output unit 11, and the control circuit 14 for inputting a signal to the gate 23G is connected.

As the N-channel MOSFET 23, an enhancement type N-channel MOSFET and a depletion type N-channel MOSFET can be used. From the viewpoint of safety, a normally-off enhancement type N is used so that the current path between the positive electrode output unit 11 and the discharge positive electrode 3 is cut off when a failure occurs in which the gate voltage is not applied. It is desirable to use a channel MOSFET.

Further, since the N-channel MOSFET 23 causes power loss due to the on-resistance at the time of discharging, it is desirable to use an N-channel MOSFET having a small on-resistance, and the on-resistance is preferably 10 mΩ or less, more preferably 5 mΩ or less. desirable. It is desirable that the structure of the N-channel MOSFET 23 is a trench gate structure capable of increasing the channel density and reducing the on-resistance.

The N-channel MOSFET 23 has a parasitic diode (body diode 24) like the P-channel MOSFET 21. Specifically, in the body diode 24, the anode is located on the discharge positive electrode 3 side and the cathode is located on the positive electrode output portion 11 side. By adjusting the orientation of the body diode 24 in this way, it is possible to prevent the current from flowing through the body diode 24.

Further, by using the N-channel MOSFET 23, it is possible to carry out switching control with lower on-resistance and higher efficiency than when the P-channel MOSFET is used.

FIG. 7 is a schematic view showing a modification 2 of the third embodiment.

The second modification is different from the structure shown in FIG. 6 in that the switch unit 13 is composed of two N-channel MOSFETs 23. In the two N-channel MOSFETs 23, the sources 23S are connected to each other facing each other, one drain 23D is connected to the positive electrode output unit 11, and the other drain 23D is connected to the discharge positive electrode 3. A control circuit 14 is connected to the gate 23G of the two N-channel MOSFETs 23. Even in this configuration, the directions of the body diodes 24 are different from each other, so that the current flowing through the body diode 24 can be reliably cut off regardless of the direction in which the current flows.

It should be noted that the embodiments disclosed this time are examples in all respects and do not serve as a basis for limited interpretation. Therefore, the technical scope of the present invention is not construed solely by the above-described embodiments, but is defined based on the description of the claims. It also includes all changes within the meaning and scope of the claims.

1 Metal air battery 2 Housing 2a Air intake port 3 Discharge positive electrode 4 Charging positive electrode 5 Negative electrode 6 Discharging positive electrode current collector 7 Charging positive electrode current collector 8 Negative electrode current collector 9 Separator 10 Electrode solution 11 Positive electrode output unit 12 Negative electrode output unit 13 Switch section 14 Control circuit 21 P-channel MOSFET (an example of MOSFET)
21D Drain 21G Gate 21S Source 23 N-Channel MOSFET (Example of MOSFET)
23D drain 23G gate 23S source

Claims (10)

A positive electrode for discharging and a positive electrode for charging,
With the negative electrode
A positive electrode output unit in which the positive electrode for discharging and the positive electrode for charging are connected in parallel, and
A metal-air battery including a negative electrode output unit connected to the negative electrode.
The positive electrode for discharging and the positive electrode for charging are provided with a branch point between the positive electrode for discharging and the positive electrode for charging.
Only between the positive electrode for discharge and the branch point, one switch unit for opening and closing the connection is provided.
The switch unit is composed of at least one MOSFET and is turned off in the charged state and turned on in the discharged state .
The parasitic diode of the MOSFET is a metal-air battery characterized in that the anode is located on the side of the positive electrode for discharging and the cathode is located on the side of the branch point . The metal-air battery according to claim 1.
The positive electrode for charging produces oxygen in the charged state,
The positive electrode for discharge is a metal-air battery characterized in that it consumes oxygen in a discharged state. The metal-air battery according to claim 1 or 2.
A metal-air battery characterized in that the positive electrode for charging has a porous shape having pores that communicate three-dimensionally. The metal-air battery according to any one of claims 1 to 3 .
The MOSFET is a metal-air battery characterized by being a P-channel MOSFET. The metal-air battery according to claim 4 .
The P-channel MOSFET is a metal-air battery characterized in that a drain is connected to the positive electrode for discharging and a source is connected to the positive electrode output portion. The metal-air battery according to any one of claims 1 to 3 .
The switch unit has two P-channel MOSFETs.
The two P-channel MOSFETs are characterized in that their drains are connected to each other facing each other, one source is connected to the positive electrode output portion, and the other source is connected to the positive electrode for discharge. Metal-air battery. The metal-air battery according to any one of claims 1 to 3 .
The MOSFET is a metal-air battery characterized by being an N-channel MOSFET. The metal-air battery according to claim 7 .
The N-channel MOSFET is a metal-air battery characterized in that a source is connected to the positive electrode for discharging and a drain is connected to the positive electrode output portion. The metal-air battery according to any one of claims 1 to 3 .
The switch unit has two N-channel MOSFETs.
The two N-channel MOSFETs are characterized in that their sources are connected to each other facing each other, one drain is connected to the positive electrode output portion, and the other drain is connected to the positive electrode for discharge. Metal-air battery. A metal-air battery including a plurality of metal-air batteries according to any one of claims 1 to 9 .

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