TWI707495B - Metal-air battery and oxide-layer removal method thereof - Google Patents

Abstract

An objective of the present disclosure is to provide a metal-air battery and an oxide-layer removal method which can reduce wastage of power for oxide-layer removal while adequately removing an oxide layer. A metal-air battery (1) of the present invention includes a battery body (2) in which a metal electrode and an air electrode are arranged opposed to each other via electrolytic solution, a USB terminal (8) connected to an external load, and a controller (9) electrically connected between the battery body and the USB terminal. The controller includes a microcomputer (14) configured to distinguish whether or not an external load is connected to the USB terminal, and an oxide-layer removal resistor (15), wherein, when the microcomputer confirms an external load connection, electrical current for oxide-layer removal is passed through a circuit that includes the metal electrode, the air electrode and the oxide-layer removal resistor.

Description

Metal-air battery and method for removing oxide film of metal-air battery

The present invention relates to a metal-air battery and a method for removing oxide film.

In the metal-air battery, in the air electrode as the positive electrode, oxygen in the atmosphere is used as the positive electrode active material to carry out the oxidation-reduction reaction of the oxygen. On the other hand, in the metal electrode as the negative electrode, the oxidation-reduction reaction of the metal proceeds. The metal-air battery has a high energy density and is expected to function as an emergency power source during disasters. The electrolytic solution is supplied to the metal-air battery to start power generation.

For example, in the metal-air battery of Patent Document 1, a method for removing the "passive film (oxide film) formed on the metal film due to the oxidation reaction" is proposed.

【Prior Technical Literature】

【Patent Literature】

[Patent Document 1] Japanese Patent No. 5961315

However, in the invention described in Patent Document 1, in a state where the external load is not connected to the metal-air battery, a current for removing the passive film is forced to flow.

In this way, in Patent Document 1, even in an unused state where the external load is not connected to the metal-air battery, it is necessary to flow a current to remove the passive film, resulting in a loss of power. waste.

In addition, in Patent Document 1, even if the passive film is not completely removed, if it is connected to an external load, the supply of current for removing the passive film is stopped. Therefore, the passive film may not be removed properly.

The present invention was completed in view of this point, and its purpose is to provide a metal-air battery and a method for removing the oxide film that can reduce the waste of electricity related to the removal of the oxide film on the one hand, and can appropriately remove the oxide film on the other.

The metal-air battery of the present invention has a battery body in which a metal electrode and an air electrode are opposed to each other via an electrolyte, an external connection terminal connected to an external load, and the battery body is electrically connected to the external connection terminal The control section; the control section has a monitoring section to determine whether the external connection terminal is connected to the external load, and a resistance to remove the oxide film; when the monitoring section confirms that it is connected to the external load, for the metal The electric current for removing the oxide film flows in the circuit including the electrode, the air electrode, and the resistor for removing the oxide film.

In a preferred aspect of the present invention, the control part is provided with a power conversion device for converting the power between the metal electrode and the terminal of the air electrode, and outputting the power to the external connection terminal The monitoring unit compares the battery voltage between the terminals with the operating movable voltage of the power conversion device, and when the battery voltage is lower than the operating movable voltage, instructs the circuit to supply a current to remove the oxide film.

A preferred aspect of the present invention is that even if the predetermined time is exceeded, the monitoring unit determines that the service life of the battery has been reached when the battery voltage is lower than the operation movable voltage.

A preferred aspect of the present invention is that the control unit further has a resistance for suppressing the oxide film. After the electrolyte is supplied, the circuit including the metal electrode, the air electrode and the resistance for suppressing the oxide film The current flows to suppress the oxide film.

A preferred aspect of the present invention is that the control unit is provided with a notification unit that notifies the control status.

The present invention is a method for removing the oxide film formed on the metal electrode of the battery body part with the metal electrode and the air electrode facing each other through the electrolyte, and is characterized in that it includes: judging that it is electrically connected to the battery body part Steps to determine whether the external connection terminal is connected to an external load and; when it is judged that it is connected to an external load, between the metal electrode and the air electrode terminal, use the resistance to remove the oxide film to become a conductive state to form a circuit, and A step of flowing a current for removing the oxide film into the circuit.

According to the metal-air battery of the present invention, since the current for removing the oxide film is flowed after confirming that it is connected to an external load, it is possible to reduce the waste of electricity related to the removal of the oxide film and to remove the oxide film appropriately.

1: Metal air battery

2: The battery body

3: shell

5: Electrolyte

6: Air pole

7: Metal pole

8: USB terminal

9: Control Department

10: Air chamber

10a: upper part

11: Liquid chamber

13: Water inlet

14: Microcomputer

15: Resistance to remove the oxide film

16: To suppress the resistance of the oxide film

17: converter

18: LED

22: Metal-air battery pack

ST1~ST12: steps

The first figure is a cross-sectional view of the battery main body constituting the metal-air battery of this embodiment.

The second figure is a circuit diagram (block diagram) of the metal-air battery of this embodiment.

The third figure is a flowchart showing the operation of the control unit constituting the metal-air battery of this embodiment.

The fourth diagram is a timing diagram in the control unit constituting the metal-air battery of this embodiment.

Hereinafter, an embodiment of the present invention (hereinafter abbreviated as "embodiment") will be described in detail. In addition, the present invention is not limited to the following embodiments, and various changes can be implemented within the scope of the gist.

As shown in the first figure, the battery main body 2 constituting the metal-air battery 1 includes, for example, a plurality of metal-air battery packs 22. In the first figure, the number of metal-air battery packs 22 is three, but the number of metal-air battery packs 22 is not limited, and it can be one, two, or four or more.

Each metal-air battery pack 22 is provided with an air chamber 10 and a liquid chamber 11. The air chamber 10 is surrounded, for example, except for the upper part 10a. On the other hand, the liquid chamber 11 is surrounded except for the water supply port 13. In the first figure, the water supply port 13 is provided in the lower part of the liquid chamber 11. The air chamber 10 and the liquid chamber 11 are isolated, and the electrolyte injected into the liquid chamber 11 will not leak into the air chamber 10. In addition, the structure of the air chamber 10 and the liquid chamber 11 shown in the first figure is an example.

As shown in the first figure, each metal-air battery pack 22 is configured to have an air electrode 6 and a metal electrode 7 as electrodes. The air electrode 6 and the metal electrode 7 are respectively supported by the frame constituting the metal-air battery pack 22. As shown in the first figure, the air electrode 6 and the metal electrode 7 are arranged facing each other in the liquid chamber 11. One side of the air electrode 6 is exposed in the liquid chamber 11, and the other side of the air electrode 6 is exposed in the air chamber 10. The number of the air electrode 6 and the metal electrode 7 is not limited, but it can be, for example, one metal electrode 7 is provided for one air electrode 6, or two or more air electrodes 6 and metal electrodes 7 are provided.

The case 3 shown in the first figure is a large container that can house the electrolyte and the battery body 2. When the metal-air battery 1 is not in use, for example, the case 3 shown in the first figure can be covered from above the battery body 2.

For example, the electrolyte solution 5 is injected into the case 3 shown in the first figure, and the battery body portion 2 is immersed in the electrolyte solution 5. At this time, the electrolyte solution 5 is introduced into each liquid chamber 11 from the water supply port 13 of each metal-air battery pack 22. The electrolyte 5 is simultaneously injected into each liquid chamber 11 through the water supply port 13. At this time, as shown in the first figure, the electrolyte 5 does not flow into the air chamber 10.

As shown in the first figure, if the electrolytic solution 5 is supplied to each liquid chamber 11, for example, when the metal electrode 7 is magnesium, an oxidation reaction represented by the following formula (1) occurs in the vicinity of the metal electrode 7. In addition, in the air electrode 6, a reduction reaction represented by the following formula (2) occurs. The entire magnesium-air battery undergoes a reaction represented by the following formula (3) and discharges.

^{(1) 2Mg → 2Mg 2+ +} 4e -

_{(2) O 2 + 2H 2} O + 4e - → 4OH -

(3) 2Mg+O ₂ +2H ₂ O → 2Mg(OH) ₂

Although not shown in the first figure, for example, the top surface of the metal-air battery pack 22 has external connection terminals for supplying the power output from the battery to the outside, and electrical connections between the battery body 2 and the external connection terminals The connected control unit (power system). The terminal for external connection is a connector, a USB (Universal Serial Bus) terminal, etc., and is not particularly limited. In addition, the installation position of the external connection terminal is not limited to the top plate portion, and the installation position can be arbitrarily set with respect to the metal-air battery 1.

However, the structure of the metal-air battery 1 shown in the first figure is only an example, and it may be the following structure: the top surface side of the metal-air battery pack 22 has a water supply port from which the inside of each metal-air battery pack 22 Supply electrolyte 5.

The second figure is a circuit diagram (block diagram) of the metal-air battery of this embodiment. As shown in the second figure, the metal-air battery 1 has a battery body 2 as external connection terminals The USB terminal 8 and the control unit 9 are constructed.

As shown in the second figure, the control unit 9 has a microcomputer 14, a resistor 15 for removing the oxide film, a resistor 16 for suppressing the oxide film, a converter 17 as a power conversion device, and an LED ( Light-Emitting Diode: Light-Emitting Diode) 18.

In the circuit of the control unit 9, the resistor 15 for removing the oxide film is provided in such a way that it can be electrically connected to the metal electrode 7 and the air electrode 6 of the battery body 2. The conductive path of the resistor 15 for removing the oxide film is provided with a switching element (not shown in the figure). The microcomputer 14 can control the opening and closing control of the switching element. If the switching element is turned off, a first closed circuit (discharge) electrically connected to the "resistor 15 for removing the oxide film, the metal electrode 7 and the air electrode 6 of the battery body 2" is formed. Circuit). The first closed circuit is a circuit for removing the oxide film, and a large current flows temporarily. By flowing the current for removing the oxide film into the first closed circuit, the oxide film formed on the surface of the metal electrode 7 can be dissolved in the electrolyte 5, and the oxide film can be appropriately removed.

The resistor 16 for suppressing the oxide film is always electrically connected to the metal electrode 7 and the air electrode 6 of the battery body 2. Therefore, a second closed circuit (discharge circuit) electrically connected to "the resistor 16 for suppressing the oxide film, the metal electrode 7 and the air electrode 6 of the battery body 2" is always formed. The second closed circuit is an oxide film suppression circuit, and a weak current flows in the second closed circuit. Thereby, it is possible to appropriately suppress the formation of an oxide film on the surface of the metal film.

The converter 17 is a DC-DC converter. In the converter 17, the power supplied from the battery main body 2 is output to the USB terminal 8 by conversion of the DC voltage. The converter 17 is driven at a predetermined voltage or higher.

In addition, the resistor 15 used to remove the oxide film and the electrical resistance to suppress the oxide film The resistor 16 may be a resistive element, or a diode including a resistive component. By controlling the resistance value, the current value can be adjusted. Or the current value can be controlled in the microcomputer 14.

The third figure is a flowchart showing the operation of the control unit constituting the metal-air battery of this embodiment. The fourth figure is a timing chart in the control unit constituting the metal-air battery of this embodiment.

As shown in the third figure, the electrolytic solution 5 is supplied to the battery body portion 2 (step ST1). In addition, it does not matter whether the USB terminal 8 is connected to an external load such as a mobile device after the electrolyte 5 is supplied or before the electrolyte 5 is supplied.

By supplying the electrolyte 5, the microcomputer 14 is activated. By starting the microcomputer 14, the voltage (battery voltage) between the terminals of the metal electrode 7 and the air electrode 6 is measured. Furthermore, the microcomputer 14 monitors whether the USB terminal 8 is connected to an external load such as a mobile device. This is done in step ST2 in the third figure.

Here, the second closed circuit including the resistor 16 for suppressing the oxide film shown in the second figure, as shown in the "oxidation film suppression current" in the fourth figure, always flows a weak current after the electrolyte is supplied. (For example, 0.1A) (refer to (1) of the fourth figure). The discharge of the closed circuit can suppress the formation of an oxide film on the surface of the metal electrode 7.

As shown in step ST3 in the third figure, after the electrolyte is supplied, the LED 18 as the notification unit shown in the second figure lights up in red, for example (refer to (2) in the fourth figure). As shown in the second figure, the LED 18 is electrically connected to the microcomputer 14. According to an instruction from the microcomputer 14, the LED 18 lights up in red, for example. The red color indicates the standby state, for example. The standby state refers to a state in which electrolyte has been supplied and external loads such as mobile devices can be connected to the USB terminal 8. In addition, the color of lighting can be arbitrarily determined in this step or in the steps described later, and the color of lighting is not limited.

In step ST4 in the third figure, the microcomputer 14 determines whether the USB terminal 8 is External load connection such as moving equipment.

In step ST4 of the third figure, if it is determined that the external load is not connected, the process returns to step ST3, and the LED 18 is continuously lit in red.

In step ST4, if it is judged that it is connected to an external load, it moves to step ST5. The fourth figure (3) shows the state of connection with an external load.

In step ST5 of the third figure, the resistor 15 for removing the oxide film shown in the second figure is conductively connected to the metal electrode and the air electrode of the battery body 2 to form a first closed circuit, and to the first closed circuit The current flows in to remove the oxide film. As described above, the conduction path of the resistor 15 for removing the oxide film is provided with a switching element. If the microcomputer 14 determines that the external load is connected, the switching element is turned ON (open) to form a first closed circuit. The current flowing into the first closed circuit for removing the oxide film is greater than the current for suppressing the oxide film.

As shown in the timing chart of the fourth figure, the current for removing the oxide film flows for a predetermined time (refer to (4) of the fourth figure). While the current for removing the oxide film flows, the LED 18 can be made to blink green, for example (refer to (5) of the fourth figure). The oxide film formed on the surface of the metal electrode 7 can be removed by flowing a current for removing the oxide film to discharge it.

Next, in step ST6 of the third figure, in the microcomputer 14, the voltage between the terminals of the battery body (battery voltage) and the operable voltage of the converter 17 are compared. When it is determined that the battery voltage is higher than the operable voltage of the converter 17 (refer to (6) of the fourth figure), the process moves to step ST7.

In step ST7 in the third figure, the converter 17 is operated to perform output to the USB terminal 8 (see (7) in the fourth figure). At this time, while outputting to the USB terminal 8, the LED 18 can be lit in green, for example (see (8) in the fourth figure).

As shown in step ST8 in the third figure, the external load is continuously connected to the USB terminal 8 During the connection period, it is determined whether the battery voltage is greater than the operable voltage of the converter 17 (step ST6). On the other hand, in step ST8, it is determined that the external load is not connected to the USB terminal 8 (that is, if the external load is removed from the USB terminal 8), the operation of the converter 17 is stopped (step ST9), and the LED 18 is turned on. Lights in red (return to step ST3).

Next, in step ST6 of the third figure, when it is determined that the battery voltage is less than the operable voltage of the converter 17, the time (total time) for removing the oxide film current is measured (step ST10). If the time measurement at this time has not reached the predetermined time (step ST11), the process returns to step ST5, and the current for removing the oxide film flows again.

In step ST6, as long as it is determined that the battery voltage is not greater than the operable voltage of the converter 17, a current for removing the oxide film flows until the predetermined time in step ST11 is reached.

The case where the predetermined time is reached in step ST11 will be described. The time for removing the current of the oxide film shown in (9) of the fourth figure (the measurement time shown in (10) of the fourth figure) reaches the predetermined time (that is, the measurement time> the predetermined time (see section (11))) in Figure 4, stop the current flowing to remove the oxide film, and the microcomputer 14 determines that the battery life has been reached. In addition, if it is determined that the service life of the battery has been reached, as shown in step ST12 in the third figure, the LED 18 blinks red, for example (refer to (12) in the fourth figure). In this way, the user can know that the service life of the battery has been reached.

As described above, in this embodiment, it is monitored whether the USB terminal 8 is connected to an external load (step ST4 in the third figure). If it is judged that it is connected to the external load, in step ST5 in the third figure, the flow is used to remove oxidation. The method of coating current is controlled. In other words, as long as the external load is not connected to the USB terminal 8, the current for removing the oxide film does not flow. In this way, first confirm the connection of the external load, and then flow the current to remove the oxide film. As long as it is not connected, no current flows, which can reduce the power waste associated with removing the oxide film. Moreover, the When connected for use, the oxide film can be properly removed, and the decrease in battery output can be suppressed during use.

In addition, in this embodiment, the microcomputer 14 compares the battery voltage with the operable voltage of the converter 17 (step ST6 in the third figure), and when it is determined that the battery voltage is lower than the operable voltage of the converter 17, reflows to remove the oxide film It is controlled by the current method (step ST5 in the third figure). Thereby, until the battery voltage exceeds the operable voltage of the converter 17, a current for removing the oxide film flows in, so that the oxide film can be reliably removed, and the converter 17 can be operated appropriately.

In addition, even if the predetermined time is reached, the microcomputer 14 can determine that the service life of the battery has been reached when the battery voltage is lower than the operating voltage of the converter (step ST12 in the third figure). Therefore, the battery life can be appropriately judged without wasting power.

In addition, in this embodiment, after the electrolytic solution 5 is supplied, a current (weak current) for suppressing the oxide film always flows. Thereby, the effect of suppressing the formation of the oxide film can be improved.

In addition, in this embodiment, an LED 18 as a notification unit is installed, and the user can be notified of the control status of the battery by the color of the LED 18 and the lighting method. The "control status" includes standby, removal of oxide film, power supply to USB terminal 8, and end of battery life. The notification unit may not be the LED 18, but may notify the status, such as sound or video.

In the metal-air battery 1 shown in the second figure, there is one USB terminal 8, but a plurality of USB terminals 8 may be provided. In this case, the converter 17 is provided in accordance with the number of USB terminals 8. Next, the microcomputer 14 monitors whether each USB terminal 8 is connected to an external load, and compares the battery voltage with the operable voltage of each converter 17.

In addition, the metal-air battery 1 in this embodiment can be applied to magnesium-air batteries, and can also be applied to other metal-air batteries.

[Industrial use possibility]

According to the metal-air battery of the present invention, the oxide film on the surface of the metal electrode can be appropriately removed, and the battery output can be prevented from decreasing. The metal-air battery of the present invention is provided with external connection terminals such as USB connected to an external load, and can be effectively applied to metal-air batteries of any structure and material as long as an oxide film is easily formed on the metal electrode.

1: Metal air battery

2: The battery body

8: USB terminal

9: Control Department

14: Microcomputer

15: Resistance to remove the oxide film

16: To suppress the resistance of the oxide film

17: converter

18: LED

Claims (7)

A metal-air battery, which is characterized by comprising: a battery body, the metal electrode and the air electrode are arranged facing each other through an electrolyte; an external connection terminal, which is connected to an external load; and a control unit, which connects the battery body to The external connection terminals are electrically connected; the control unit has a monitoring unit for judging whether the external load is connected to the external connection terminal and a resistor for removing the oxide film; the monitoring unit confirms that it is connected to the external load At this time, a current for removing the oxide film flows into the circuit including the metal electrode, the air electrode, and the resistor for removing the oxide film. For the metal-air battery described in claim 1, wherein the control part is provided with a power conversion device, and the power conversion device is used to convert the power between the metal electrode and the terminal of the air electrode, and the power Output to the external connection terminal; the monitoring unit compares the battery voltage between the terminals with the operating movable voltage of the power conversion device, and when the battery voltage is lower than the operating movable voltage, it instructs the circuit to be supplied for removal The current of the oxide film. For the metal-air battery described in item 2 of the scope of patent application, the monitoring unit determines that the service life of the battery has been reached when the battery voltage is lower than the operating movable voltage even if the predetermined time is exceeded. For the metal-air battery described in any one of items 1 to 3 in the scope of the patent application, the control part further has a resistance for suppressing the oxide film. After the electrolyte is supplied, the metal electrode and the air Pole and the circuit used to suppress the resistance of the oxide coating To suppress the current of the oxide film. For the metal-air battery described in any one of items 1 to 3 in the scope of the patent application, the control unit is provided with a notification unit for notifying the control status. For the metal-air battery described in item 4 of the scope of patent application, the control unit is provided with a notification unit for notifying the control status. A method for removing the oxide film of a metal-air battery, which is used to remove the oxide film formed on the metal electrode of the battery body part with the metal electrode and the air electrode facing each other through the electrolyte, and it is characterized by comprising: The step of judging whether the external connection terminal electrically connected to the battery body is connected to an external load; and when judging that it is connected to the external load, use it to remove the oxide film between the metal electrode and the air electrode terminal The resistance of φ is turned on to form a circuit, and a current for removing the oxide film flows into the circuit.

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