JP2011054329A - Metal-air cell system; motor driver using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a metal-air cell system having an excellent charge and discharge rate and high charge efficiency and provide a motor driver using the system. <P>SOLUTION: This metal-air cell system haing a metal-air cell includes (1) a measn for setting temperature, (2) a means for controlling temperature, (3) a means for monitoring temperature control, and (4) a means for switching temperature control modes. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a metal-air battery system that can achieve both an excellent charge / discharge rate and high charge efficiency, and a motor drive body using the metal-air battery system.

  The metal-air battery is a chargeable / dischargeable battery using metal (for example, lithium) as a negative electrode active material and oxygen as a positive electrode active material. Since oxygen, which is a positive electrode active material, is obtained from air, it is not necessary to enclose the positive electrode active material in the battery, so theoretically, a metal-air battery has a larger capacity than a secondary battery using a solid positive electrode active material. Can be realized.

In the metal-air battery, the reaction of the formula (1) proceeds at the negative electrode during discharge.
2Li → 2Li ⁺ + 2e ⁻ (1)
The electrons generated by the equation (1) reach the positive electrode after working with an external load via an external circuit. Then, lithium ions (Li ⁺ ) generated in the formula (1) move from the negative electrode side to the positive electrode side by electroosmosis in the electrolyte sandwiched between the negative electrode and the positive electrode.

Further, during discharge, the reactions of the formulas (2) and (3) proceed at the positive electrode.
2Li ⁺ + O ₂ + 2e ⁻ → Li ₂ O ₂ (2)
2Li ⁺ + 1 / 2O ₂ + 2e ⁻ → Li ₂ O (3)
The generated lithium peroxide (Li ₂ O ₂ ) and lithium oxide (Li ₂ O) are accumulated in the air electrode as solids.
At the time of charging, the reverse reaction of the above formula (1) proceeds at the negative electrode, and the reverse reactions of the above formulas (2) and (3) proceed at the positive electrode, respectively. Become.

  If no temperature control measures are taken in the metal-air battery, some cells housed inside the battery act at a temperature higher than the ambient temperature of the battery, resulting in a difference in discharge / charge between the cells. There is a risk that the battery may be damaged as a result of accelerating deterioration of the solid and liquid substances in the battery due to heat. In order to avoid these disadvantages, it is necessary to provide an appropriate temperature control mechanism in the metal-air battery.

  As a kind of temperature control mechanism, a metal-air battery technology provided with a cooling means has been developed so far. Patent Document 1 has means for directing the flow of cooling air with a pair of spaced thin plates between adjacent cells, each separated thin plate having the same dimensions as the main surface, said means being Electrochemical zinc-air multi-cell battery technology that is provided to allow cooling air to flow between a pair of sheets and the outer surface of the sheets is in contact with and cools the reaction air Is disclosed.

Japanese Patent Laid-Open No. 10-162870

Patent Document 1 discloses an outline of air cooling in an electrochemical zinc-air multi-cell battery, but does not describe any specific cooling temperature. Therefore, it is not clear from Patent Document 1 what specific temperature setting should improve battery performance.
The present invention has been accomplished in view of the above circumstances, and provides a metal-air battery system capable of achieving both an excellent charge / discharge rate and high charge efficiency, and a motor drive body using the metal-air battery system. For the purpose.

The metal-air battery system of the present invention is a metal-air battery system having a metal-air battery having at least an air electrode, a negative electrode, and an electrolyte interposed between the air electrode and the negative electrode,
(1) A temperature setting means for setting a target operating temperature during charging of the metal-air battery and a target operating temperature during discharging of the metal-air battery that is different from the target operating temperature during charging.
(2) Temperature control for limiting the temperature of the metal-air battery so as to be the target operating temperature at the time of charging and limiting the temperature so as to be the target operating temperature at the time of discharging. means,
(3) Temperature control monitoring means for monitoring the necessity of temperature control during charging and / or discharging for the metal-air battery,
(4) When charging and / or discharging, when the temperature control monitoring means determines that the temperature control of the metal-air battery is necessary, the temperature control operation mode for starting the temperature control of the metal-air battery is selected. When the temperature control monitoring unit determines that the temperature control of the metal-air battery is unnecessary, the temperature control stop mode for stopping the temperature control of the metal-air battery is selected, and the selected temperature control mode is executed. Temperature control mode switching means.

  In the metal-air battery system having such a configuration, the temperature setting means sets the discharge operation target temperature and the charge operation target temperature to different temperatures, and the temperature control means, the temperature control monitoring means, By appropriately controlling the temperature by the temperature control mode switching means, the actual operating temperature of the metal-air battery at the time of discharging can be set to a temperature different from the actual operating temperature of the metal-air battery at the time of charging. It is possible to achieve both an excellent charge / discharge rate and charge efficiency.

  In the metal-air battery system of the present invention, it is preferable that the temperature setting means sets the discharge target operation temperature to a temperature lower than the charge target operation temperature.

  In the metal-air battery system having such a configuration, the temperature setting means sets the discharge operation target temperature to a temperature lower than the charge operation target temperature, and the temperature control means and the temperature control monitoring means. In addition, by appropriately performing temperature control by the temperature control mode switching means, the actual operating temperature of the metal-air battery at the time of discharging is set to a temperature lower than the actual operating temperature of the metal-air battery at the time of charging. It is possible to achieve both an excellent charge / discharge rate and charge efficiency.

  In the metal-air battery system of the present invention, the temperature control means accumulates excess heat generated from the metal-air battery at any one of charging time and discharging time, and at any time of charging and discharging time. At the other time, it is preferable to provide a heat storage unit that warms up the metal-air battery using the surplus heat.

  Since the metal-air battery system having such a structure can be used to warm up the metal-air battery at an appropriate time by temporarily accumulating excess heat generated from the metal-air battery in a heat storage unit, it has high energy. The metal-air battery can be warmed up with efficiency.

  The motor driving body of the present invention includes the metal-air battery system and a motor driven by electric power supplied from the metal-air battery system, and the temperature control means of the metal-air battery system includes the metal-air battery. It is a heat exchange means for performing heat exchange between the motors.

  Since the motor drive body having such a configuration can use the exhaust heat generated from the motor to heat the metal-air battery during charging, the metal-air battery can be warmed up with high energy efficiency. it can.

  According to the present invention, the temperature setting means sets the discharge operation target temperature and the charge operation target temperature to different temperatures, and the temperature control means, the temperature control monitoring means, and the temperature control mode switching. By performing temperature control appropriately by means, the actual operating temperature of the metal-air battery at the time of discharging can be made different from the actual operating temperature of the metal-air battery at the time of charging, and excellent charge / discharge Both rate and charging efficiency can be achieved.

It is a figure which shows an example of the laminated constitution of the metal air battery used for this invention, Comprising: It is the figure which showed typically the cross section cut | disconnected in the lamination direction. It is the schematic diagram which showed the typical example of the state in which the metal air battery system which concerns on this invention was connected to the external load. It is the flowchart which showed the typical example of control of the metal air battery system which concerns on this invention. It is a schematic diagram of the typical example of the motor drive body which concerns on this invention. It is the flowchart which showed the typical example of control of the motor drive body which concerns on this invention. It is the cyclic voltammogram which showed the electrochemical evaluation result in salt concentration 0.32 mol / kg. It is the graph which put together the value of the discharge reaction rate in different measurement temperature, and a charge reaction rate. It is the graph which put together the value of the charge efficiency in different measurement temperature. It is a cross-sectional schematic diagram of the CV cell used for cyclic voltammetry (CV).

The metal-air battery system of the present invention is a metal-air battery system having a metal-air battery having at least an air electrode, a negative electrode, and an electrolyte interposed between the air electrode and the negative electrode,
(1) A temperature setting means for setting a target operating temperature during charging of the metal-air battery and a target operating temperature during discharging of the metal-air battery that is different from the target operating temperature during charging.
(2) Temperature control for limiting the temperature of the metal-air battery so as to be the target operating temperature at the time of charging and limiting the temperature so as to be the target operating temperature at the time of discharging. means,
(3) Temperature control monitoring means for monitoring the necessity of temperature control during charging and / or discharging for the metal-air battery,
(4) When charging and / or discharging, when the temperature control monitoring means determines that the temperature control of the metal-air battery is necessary, the temperature control operation mode for starting the temperature control of the metal-air battery is selected. When the temperature control monitoring unit determines that the temperature control of the metal-air battery is unnecessary, the temperature control stop mode for stopping the temperature control of the metal-air battery is selected, and the selected temperature control mode is executed. Temperature control mode switching means.

As described above, in the conventional metal-air battery system, a specific temperature setting has not been made from the viewpoint of improving battery performance.
However, as shown in the examples described later, as the temperature rises, both the discharge reaction rate and the charge reaction rate improve. However, if the temperature is high during discharge, the charge efficiency after discharge may deteriorate. It became clear for the first time as a result of inventors' earnest efforts. From the results of this example, by designing a system in which the actual operating temperature during discharging of the metal-air battery is different from the actual operating temperature during charging, the operating temperature of the metal-air battery as described above. It has been found that the charge / discharge rate and the charge efficiency, both of which are in a trade-off relationship, can be made compatible without any loss.
The metal-air battery system according to the present invention is based on the above idea, and sets the discharge target temperature to be different from the charge target temperature in advance and appropriately controls the temperature of the metal-air battery. Thus, both an excellent charge / discharge rate and charging efficiency can be achieved.

  The metal-air battery system of the present invention includes at least (1) temperature setting means, (2) temperature control means, (3) temperature control monitoring means, (4) temperature control mode switching means, and (5) metal air battery. . Hereinafter, the items will be described in order.

(1) About temperature setting means The temperature setting means provided in the metal-air battery system according to the present invention includes a target operating temperature during charging of the metal-air battery and a discharge of the metal-air battery that is a temperature different from the target operating temperature during charging. It is a means for setting the operation target temperature.
Here, the target operating temperature during charging is a reference temperature when the actual metal-air battery operates during charging, and the target operating temperature during discharging refers to the actual metal-air battery during discharging. This is the reference temperature for operation.
By setting each operation target temperature in this way and appropriately performing temperature control by a temperature control means, a temperature control monitoring means, and a temperature control mode switching means, which will be described later, the actual operation temperature during discharge always becomes the value during charging. The temperature of the metal-air battery can be set so that the temperature is different from the operating temperature.

In the temperature setting means described above, it is preferable to set the discharge operation target temperature to a temperature lower than the charge operation target temperature.
As shown in the examples described later, the inventors have earnestly determined that it is possible to achieve both an excellent charge / discharge rate and charging efficiency by setting the actual operating temperature during discharging to a temperature lower than the operating temperature during charging. It becomes clear by effort. Therefore, the operation target temperature during discharging is set to a temperature lower than the operation target temperature during charging by the temperature setting means, and temperature control is appropriately performed by the temperature control means, the temperature control monitoring means, and the temperature control mode switching means. Therefore, the actual operating temperature of the metal-air battery at the time of discharging can be made lower than the actual operating temperature of the metal-air battery at the time of charging, and both excellent charge / discharge rate and charging efficiency can be achieved. .

  Specifically, as the temperature setting means, a recording medium such as a magnetic disk storing the operation target temperature data at the time of charging and the operation target temperature data at the time of discharging, or the temperature data can be transmitted to a temperature control monitoring means to be described later. An apparatus such as an electronic computer can be exemplified. However, the charging target temperature data for charging and the target operating temperature data for discharging may be set before, during, or during the operation of the metal-air battery system, and the temperature data can be used for temperature control of the metal-air battery. For example, the recording medium and the apparatus are not necessarily limited, and any means can be adopted.

(2) About temperature control means The temperature control means provided in the metal-air battery system according to the present invention limits the temperature of the metal-air battery so that it becomes the operation target temperature at the time of charging, and at the time of discharging. Is a means for limiting the temperature so as to be the operation target temperature during discharge.
Here, “temperature limitation” includes changing or maintaining the temperature of the metal-air battery, and “temperature control” specifically refers to warming, cooling, or maintaining a constant temperature of the metal-air battery. To do any of the above. “Warming / cooling of the metal-air battery” means increasing / decreasing the temperature of the metal-air battery. Here, the “temperature of the metal-air battery” means the temperature around the metal-air battery including the inside of the metal-air battery, and preferably the temperature inside the metal-air battery.
It should be noted that limiting the temperature so as to achieve each operation target temperature does not necessarily mean that the control is continued until the operation target temperature is exactly reached. Although the actual operating temperature of the metal-air battery depends on the temperature distribution inside the metal-air battery, the temperature range in the vicinity of each of the operation target temperatures, specifically, the temperature within a temperature range of about ± 1 to 3 ° C If it is good.
A method for measuring the temperature of the metal-air battery will be described in the description of the temperature control monitoring means.

  The temperature control means may be a means for controlling the temperature of the metal-air battery independently of the discharge mechanism of the metal-air battery system, but from the viewpoint of space saving and power saving, the metal-air battery system It is also possible to use a means using the discharge mechanism.

The temperature control means described above accumulates surplus heat generated from the metal-air battery at one of charging and discharging, and surplus heat at the other of charging and discharging. It is preferable to provide a heat storage unit for warming up the metal-air battery using By adopting such a configuration, surplus heat generated from the metal-air battery can be temporarily stored in the heat storage unit and used to warm up the metal-air battery at an appropriate time. The battery can be warmed up.
The configuration of the heat storage unit is not particularly limited as long as it can sufficiently accumulate and warm up the excess heat of the metal-air battery. Specific examples of the configuration of the heat storage unit include a device in which a liquid or solid heat storage material is stored in an appropriate container, and a flow path through which the liquid heat storage material circulates, and the flow path surrounds the vicinity of the metal-air battery. Examples of such a device can be given.
The heat storage material is not particularly limited as long as it can store a certain amount of heat, but is preferably a substance having a heat of fusion of 100 kJ / kg, and a substance having a heat of fusion of 150 kJ / kg. Particularly preferred. From the viewpoint of being easy to handle and having a relatively high melting point and heat of fusion, the heat storage material is preferably water or a linear saturated hydrocarbon having 14 or more carbon atoms.
Table 1 below shows examples of heat storage materials and their molecular formulas, melting points, and heats of fusion.

(3) Temperature control monitoring means The temperature control monitoring means included in the metal-air battery system according to the present invention is a means for monitoring the necessity of temperature control during charging and / or discharging of the metal-air battery. In order to monitor the necessity of temperature control of the metal-air battery and to transmit the monitoring result to the temperature control mode switching means described later, the temperature control monitoring means is at least a means or device for acquiring physical property data from the metal-air battery And means for determining whether the metal-air battery requires temperature control based on the obtained physical property data.

  As one form of the temperature control monitoring means, the temperature measuring device for monitoring the temperature of the metal-air battery, and the charging time set by the temperature setting means described above as temperature data serving as a reference for determining the necessity of temperature control The operation target temperature data and the discharge operation target temperature data can be held. By holding such temperature data, the temperature control monitoring means can determine whether or not the temperature control of the metal-air battery is necessary from the temperature of the metal-air battery monitored by the temperature measuring device.

  The means for measuring the temperature of the metal-air battery is not particularly limited, and generally a method for measuring the temperature around the metal-air battery can be adopted. As specific examples of the temperature measurement method, a glass thermometer using pure mercury, a metal thermometer using bimetal, an electric thermometer using a platinum wire, a temperature sensor using a thermocouple, and a thermistor were used. The measuring method using a resistance thermometer, a radiation thermometer, etc. can be mentioned.

  From the viewpoint of monitoring whether or not the temperature control of the metal air battery is necessary from the starting stage of the metal air battery system, and starting the temperature control of the metal air battery if necessary, the temperature control monitoring means Preferably operate at least during the startup phase of the metal-air battery system. For example, when the use environment of the metal-air battery system is extremely low temperature, or when the use environment is extremely high temperature, the necessity for temperature control must always be confirmed. It is preferable that the temperature control monitoring means operates not only in the starting stage of the battery system but also in the middle stage of the metal-air battery system.

(4) Temperature control mode switching means The temperature control mode switching means provided in the metal-air battery system according to the present invention is a means for selecting a temperature control operation mode or a temperature control stop mode and executing the selected temperature control mode. .
The temperature control operation mode is a mode for starting the temperature control of the metal-air battery when it is determined that the temperature control of the metal-air battery is necessary by the above-described temperature control monitoring means during charging and / or discharging. The temperature control stop mode is a mode in which the temperature control of the metal-air battery is stopped when it is determined by the above-described temperature control monitoring means that the temperature control of the metal-air battery is unnecessary.

Here, “when it is determined that temperature control is necessary” does not necessarily occur only once. That is, it is determined that the temperature control of the metal-air battery is necessary by the temperature control monitoring means, and as a result of performing the temperature control, the temperature control monitoring means once determines that the temperature control is unnecessary, and then it is determined that the temperature control is necessary again. A case can also be assumed. Even in such a case, the temperature control mode switching means provided in the metal-air battery system according to the present invention can select the temperature control operation mode again. The same applies to “when temperature control is determined to be unnecessary”. That is, it is assumed that the temperature control mode switching means periodically obtains information on necessity / unnecessity of temperature control from the temperature control monitoring means and switches the temperature control mode.
The configuration of the temperature control mode switching means is not particularly limited. Specifically, a switch for switching the temperature control means described above in conjunction with information on whether or not temperature control is necessary, and information on whether or not temperature control is necessary are provided. An apparatus such as an electronic computer that can be transmitted to a temperature control means or the like can be exemplified.

(5) Metal-air battery The metal-air battery provided in the metal-air battery system according to the present invention includes at least an air electrode, a negative electrode, and an electrolyte interposed between the air electrode and the negative electrode.
As one form of the metal-air battery used in the present invention, an air electrode current collector having a porous structure, and an air electrode layer formed on the air electrode current collector and containing a catalyst and a conductive material are provided. It can take a configuration of having an air electrode, a negative electrode current collector, a negative electrode having a negative electrode active material layer containing at least a negative electrode active material, and an electrolyte layer sandwiched between the air electrode and the negative electrode, It is not necessarily limited only to this form.

FIG. 1 is a diagram showing an example of a layer configuration of a metal-air battery used in the present invention, and is a diagram schematically showing a cross section cut in a stacking direction. The metal-air battery used in the present invention is not necessarily limited to this example.
The metal-air battery 100 includes an air electrode 16 containing the air electrode layer 12 and the air electrode current collector 14, a negative electrode 17 containing the negative electrode active material layer 13 and the negative electrode current collector 15, the air electrode 16 and the negative electrode. 17 has an electrolyte layer 11 sandwiched by 17.
Hereinafter, the electrolyte layer, the air electrode, and the negative electrode, which are components of the metal-air battery used in the present invention, will be described in order.

(Electrolyte layer)
The electrolyte layer in the metal-air battery used in the present invention is a layer formed between the air electrode layer and the negative electrode layer and responsible for conduction of metal ions. Examples of the electrolyte constituting the electrolyte layer include a liquid electrolyte (electrolyte), a gel electrolyte, a solid electrolyte, and the like. Among these, a liquid electrolyte and a gel electrolyte are preferable, and particularly, high ionic conductivity is provided. Therefore, a liquid electrolyte is preferable. Further, when the electrolyte used in the present invention is a liquid electrolyte or a gel electrolyte, the solvent used may be a non-aqueous solvent or water, but in particular, it may be a non-aqueous solvent. preferable.

The type of the non-aqueous electrolyte is preferably selected as appropriate according to the type of metal ion to be conducted. For example, a non-aqueous electrolyte of a lithium air secondary battery usually contains a lithium salt and a non-aqueous solvent. Examples of the lithium salt include inorganic lithium salts such as LiPF ₆ , LiBF ₄ , LiClO _4, and LiAsF ₆ ; and LiCF ₃ SO ₃ , LiN (SO ₂ CF ₃ ) ₂ (Li-TFSI), LiN (SO ₂ C _2). And organic lithium salts such as F ₅ ) ₂ and LiC (SO ₂ CF ₃ ) ₃ . Examples of the non-aqueous solvent include ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), butylene carbonate, γ-butyrolactone, sulfolane, acetonitrile, Examples include 1,2-dimethoxymethane, 1,3-dimethoxypropane, diethyl ether, tetrahydrofuran, 2-methyltetrahydrofuran, and mixtures thereof. Further, from the viewpoint that dissolved oxygen can be efficiently used for the reaction, the non-aqueous solvent is preferably a solvent having high oxygen solubility. The concentration of the lithium salt in the non-aqueous electrolyte is, for example, in the range of 0.5 mol / L to 3 mol / L. In the present invention, a low volatile liquid such as an ionic liquid may be used as the nonaqueous electrolytic solution.

In addition, the non-aqueous gel electrolyte used in the present invention is usually a gel obtained by adding a polymer to a non-aqueous electrolyte. For example, a non-aqueous gel electrolyte of a lithium-air secondary battery is gelled by adding a polymer such as polyethylene oxide (PEO), polyacrylonitrile (PAN), or polymethyl methacrylate (PMMA) to the non-aqueous electrolyte described above. By doing so, it can be obtained. In the present _{invention, LiTFSI (LiN (CF 3 SO} 2) 2) -PEO nonaqueous gel electrolyte systems are preferred.

(Air electrode)
The air electrode in the metal-air battery used in the present invention preferably has an air electrode layer. Usually, in addition to this, an air electrode current collector and air connected to the air electrode current collector are used. It has a pole lead.

(Air electrode layer)
The air electrode layer in the metal-air battery used in the present invention contains at least a conductive material. Furthermore, you may contain at least one of a catalyst and a binder as needed.

  The conductive material used for the air electrode layer in the metal-air battery used in the present invention is not particularly limited as long as it has conductivity, and examples thereof include a carbon material. Furthermore, the carbon material may have a porous structure or may not have a porous structure. However, in the present invention, the carbon material preferably has a porous structure. This is because the specific surface area is large and many reaction fields can be provided. Specific examples of the carbon material having a porous structure include mesoporous carbon. On the other hand, specific examples of the carbon material having no porous structure include graphite, acetylene black, carbon nanotube, and carbon fiber. As content of the electroconductive material in an air electrode layer, it is preferable to exist in the range of 65 mass%-99 mass%, for example in the range of 75 mass%-95 mass% especially. If the content of the conductive material is too small, the reaction field may decrease and the battery capacity may be reduced. If the content of the conductive material is too large, the content of the catalyst is relatively reduced and sufficient. This is because it may not be possible to exert a proper catalytic function.

Examples of the catalyst used for the air electrode layer in the metal-air battery used in the present invention include cobalt phthalocyanine and manganese dioxide. The catalyst content in the air electrode layer is, for example, preferably in the range of 1% by mass to 30% by mass, and more preferably in the range of 5% by mass to 20% by mass. If the catalyst content is too low, sufficient catalytic function may not be achieved. If the catalyst content is too high, the content of the conductive material is relatively reduced, the reaction field is reduced, and the battery capacity is reduced. This is because there is a possibility that a decrease in the number of times will occur.
From the viewpoint that the electrode reaction is performed more smoothly, the conductive material described above preferably supports a catalyst.

  The air electrode layer may contain at least a conductive material, but preferably further contains a binder for fixing the conductive material. Examples of the binder include polyvinylidene fluoride (PVdF) and polytetrafluoroethylene (PTFE). Although it does not specifically limit as content of the binder in an air electrode layer, For example, it is preferable that it is in the range of 30 mass% or less, especially 1 mass%-10 mass%.

The thickness of the air electrode layer is different depending on the use of the air battery, for example, 2 μm to
It is preferable to be in the range of 500 μm, especially in the range of 5 μm to 300 μm.

(Air current collector)
The air electrode current collector in the metal-air battery used in the present invention collects current in the air electrode layer. The material for the air electrode current collector is not particularly limited as long as it has conductivity, and examples thereof include stainless steel, nickel, aluminum, iron, titanium, and carbon. Examples of the shape of the air electrode current collector include a foil shape, a plate shape, and a mesh (grid) shape. Especially, in this invention, it is preferable that the shape of an air electrode electrical power collector is a mesh form. This is because the current collection efficiency is excellent. In this case, usually, a mesh-shaped air electrode current collector is disposed inside the air electrode layer. Furthermore, the metal-air battery of the present invention may have another air electrode current collector (for example, a foil-shaped current collector) that collects the charges collected by the mesh-shaped air electrode current collector. good. In the present invention, a battery case to be described later may also have the function of an air electrode current collector.
The thickness of the air electrode current collector is, for example, preferably in the range of 10 μm to 1000 μm, and more preferably in the range of 20 μm to 400 μm.

(Negative electrode)
The negative electrode in the metal-air battery used in the present invention preferably has a negative electrode layer containing a negative electrode active material, and is usually connected to the negative electrode current collector and the negative electrode current collector in addition to this. It has a negative electrode lead.

(Negative electrode layer)
The negative electrode layer in the metal-air battery used in the present invention contains at least a negative electrode active material having an alkali metal element. Examples of the alkali metal element include Li, Na, and K. Li is preferable from the viewpoint that a battery having a high energy density can be obtained.

  The negative electrode active material in the metal-air battery used in the present invention is preferably capable of occluding and releasing alkali metal ions. Such a negative electrode active material is not particularly limited as long as it has an alkali metal element, and examples thereof include simple metals, alloys, metal oxides, and metal nitrides. Furthermore, examples of the alloy having a lithium element include a lithium aluminum alloy, a lithium tin alloy, a lithium lead alloy, and a lithium silicon alloy. Moreover, as a metal oxide which has a lithium element, lithium titanium oxide etc. can be mentioned, for example. Examples of the metal nitride containing a lithium element include lithium cobalt nitride, lithium iron nitride, and lithium manganese nitride.

  Further, the negative electrode layer in the metal-air battery used in the present invention may contain only the negative electrode active material, and contains at least one of a conductive material and a binder in addition to the negative electrode active material. It may be a thing. For example, when the negative electrode active material is in the form of a foil, a negative electrode layer containing only the negative electrode active material can be obtained. On the other hand, when the negative electrode active material is in a powder form, a negative electrode layer having a negative electrode active material and a binder can be obtained. Note that the conductive material and the binder are the same as the contents described in the above-mentioned “air electrode” section, and thus the description thereof is omitted here.

(Negative electrode current collector)
The material of the negative electrode current collector in the metal-air battery used in the present invention is not particularly limited as long as it has conductivity, and examples thereof include copper, stainless steel, nickel, and carbon. . Examples of the shape of the negative electrode current collector include a foil shape, a plate shape, and a mesh (grid) shape. In the present invention, a battery case, which will be described later, may have the function of a negative electrode current collector.

  In the case where the metal-air battery used in the present invention has a structure in which multiple layers as shown in FIG. 1 are stacked, from the viewpoint of safety, between the air electrode layer and the negative electrode layer belonging to different layers. It is preferable to have a separator. Examples of the separator include porous films such as polyethylene and polypropylene; and nonwoven fabrics such as a resin nonwoven fabric and a glass fiber nonwoven fabric.

  The metal-air battery used in the present invention usually has a battery case that houses the air electrode layer, the negative electrode layer, and the electrolyte layer. Specific examples of the shape of the battery case include a coin type, a flat plate type, a cylindrical type, and a laminate type. The battery case may be an open-air battery case or a sealed battery case. An open-air battery case is a battery case having a structure in which at least the air electrode layer can sufficiently come into contact with the atmosphere. On the other hand, when the battery case is a sealed battery case, it is preferable to provide a gas (air) introduction pipe and an exhaust pipe in the sealed battery case. In this case, the gas to be introduced / exhausted preferably has a high oxygen concentration, and more preferably pure oxygen. In addition, it is preferable to increase the oxygen concentration during discharging and decrease the oxygen concentration during charging.

FIG. 2 is a schematic diagram showing a typical example of a state in which the metal-air battery system according to the present invention is connected to an external load. This typical example is merely an example, and the metal-air battery system according to the present invention is not limited to this typical example.
FIG. 3 is a flowchart showing a typical example of control of the metal-air battery system according to the present invention.

  As shown in FIG. 2, a typical example of a metal-air battery system according to the present invention includes a metal-air battery, a temperature control means having a heat storage material, a temperature control monitoring means having a temperature sensor for measuring the temperature of the metal-air battery, Temperature control mode switching means is included. The temperature control monitoring means holds the charging operation target temperature data and the discharging operation target temperature data set in advance by a temperature setting means (not shown). The temperature control means, the temperature control mode switching means, and the temperature control monitoring means are all electrically connected. When the temperature control monitoring means determines whether or not the temperature control of the metal-air battery is necessary, it follows the determination. It is set so that the temperature control mode is automatically switched by the temperature control mode switching means.

Based on the schematic diagram of FIG. 2 and the flowchart of FIG. 3, control during discharge of a typical example of the metal-air battery system according to the present invention will be described.
First, in step S11 shown in FIG. 3, the system is started and at the same time the temperature control operation mode is set. Next, in step S12, temperature control means and temperature control monitoring means are executed.
Subsequently, in step S13, the temperature control monitoring means determines whether or not temperature control is necessary. The temperature control monitoring means has operation target temperature data at the time of discharge as described above, and determines whether or not temperature control is necessary based on the data. If temperature control is unnecessary, the process proceeds to step S14. Moreover, if temperature control is required, it will return to step S12 and will continue temperature control operation mode. The time interval for executing step S13, that is, the time interval for executing the determination by the temperature control monitoring unit again after the temperature control monitoring unit determines that the temperature control is necessary may be as short as several seconds or longer. A time interval of several minutes.
In step S14, the temperature control of the metal-air battery is completed by executing the temperature control mode switching means and switching to the temperature control stop mode.

Hereinafter, a motor driving body using the above-described metal-air battery system will be described.
A motor driving body of the present invention includes the above-described metal-air battery system and a motor driven by electric power supplied from the metal-air battery system, and the temperature control means of the metal-air battery system includes a metal-air battery and a motor. It is a heat exchange means for exchanging heat between.
Since the motor drive body having such a configuration can use the exhaust heat generated from the motor for heating the metal-air battery during charging, the metal-air battery can be warmed up with high energy efficiency.

The heat exchange means is not necessarily limited to a device for heat exchange or the like, and may be, for example, each shape of a metal-air battery and a motor, arrangement of each device, or the like. For example, as a method for setting the heat exchange means, there can be mentioned a method in which the metal-air battery and the motor are arranged at positions where they can exchange heat with each other, more specifically, a method in which the metal-air battery is arranged in the vicinity of the motor.
Moreover, as an example of the heat exchange means, an apparatus having a flow path for flowing a heat exchange medium that circulates between the metal-air battery and the motor can be exemplified.

  The heat exchanging means described above is preferably a heat storage section that moves back and forth between the vicinity of the metal-air battery and the vicinity of the motor. As the heat storage unit, a heat storage unit as described in the above section “(2) Temperature control means” in the description of the metal-air battery system according to the present invention can be employed.

  From the viewpoint that the motor drive body of the present invention can withstand longer use, it is preferable that the motor drive body further includes a metal-air battery charging means, and the charging source of the charging means is a motor. Since the motor drive body configured as described above can be driven and charged by the motor at the same time, no special charging facility is required, and volume saving of the entire motor drive body can be realized.

FIG. 4 shows a schematic diagram of a typical example of the motor driving body according to the present invention. FIG. 4A is a schematic diagram showing the arrangement of the devices in the motor drive body during discharge of the metal-air battery, and FIG. 4B shows the arrangement of the devices in the motor drive body during charging of the metal-air battery. It is the shown schematic diagram. In addition, this typical example is an example to the last, and the motor drive body which concerns on this invention is not limited only to this typical example.
FIG. 5 is a flowchart showing a typical example of the control of the motor driving body according to the present invention.

  As shown in FIG. 4, a typical example of the motor driving body according to the present invention is a metal air battery, a heat storage unit as a temperature control means, a temperature control monitoring means having a temperature sensor for measuring the temperature of the metal air battery, a temperature Control mode switching means and a motor are provided. The motor driver shown in FIG. 4 warms up the metal-air battery when the metal-air battery is charged, and the temperature control monitoring means is a charge set in advance by a temperature setting means (not shown). Operation target temperature data, and discharge operation target temperature data set to a temperature lower than the charge operation target temperature. The metal-air battery is electrically connected to the motor. Furthermore, the heat storage unit, the temperature control mode switching means, and the temperature control monitoring means are all electrically connected, and if the temperature control monitoring means determines whether the temperature control of the metal-air battery is necessary or not, it follows that determination. Thus, the temperature control mode is set to be automatically switched by the temperature control mode switching means. The heat storage unit is movable so that it can move within the motor drive body.

As shown to Fig.4 (a), at the time of discharge of a metal air battery, the thermal storage part is arrange | positioned in the position close | similar to a motor and far from a metal air battery. In this arrangement, the heat storage unit absorbs Joule heat generated by driving the motor and accumulates it in the heat storage unit. This arrangement is an arrangement under the temperature control stop mode, and the temperature control of the metal-air battery is not particularly performed.
On the other hand, as shown in FIG. 4B, when the metal-air battery is charged, the heat storage unit is disposed at a position close to the metal-air battery and far from the motor. This arrangement is an arrangement under the temperature control operation mode. In this arrangement, the heat storage part gives Joule heat obtained from the motor at the time of discharge to the metal air battery so that the metal air battery can be warmed up. is there.
When discharging again after charging, the heat storage is performed by switching from the arrangement under the temperature control operation mode shown in FIG. 4 (b) to the arrangement under the temperature control stop mode as shown in FIG. 4 (a). The part is removed from the vicinity of the metal-air battery, and is again arranged at a position near the motor.
In this typical example, since the exhaust heat of the motor at the time of discharge of the metal-air battery is transmitted to the metal-air battery through the heat storage unit at the time of charging of the metal-air battery, at least the motor of the motor at the time of discharge is discharged. It is preferable that the temperature is higher than the temperature of the metal-air battery during charging.

Based on the schematic diagram of FIG. 4 and the flowchart of FIG. 5, the control when the metal-air battery is switched from discharging to charging in the typical example of the motor driving body according to the present invention will be described.
The initial state when starting the motor drive body is assumed to be a temperature control stop mode (FIG. 4A). First, in step S21 shown in FIG. 5, the motor driving body is started, and at the same time, the metal air battery is discharged. Next, in step S22, the metal-air battery is switched from discharging to charging, and in step S23, temperature control monitoring means is executed.
Subsequently, in step S24, the temperature control monitoring means determines whether or not temperature control is necessary. The temperature control monitoring means has operation target temperature data at the time of charging as described above, and determines whether temperature control is necessary or not based on the data. If temperature control is necessary, the process proceeds to step S25. If temperature control is unnecessary, the process returns to step S23, and the temperature control operation mode is continuously executed. The time interval for executing step S24, that is, the time interval for executing the determination by the temperature control monitoring unit again after the temperature control monitoring unit determines that the temperature control is unnecessary is as short as several seconds or longer. A time interval of several minutes.
In step S25, the temperature control of the metal-air battery is started by executing the temperature control mode switching means and switching to the temperature control operation mode (FIG. 4B).

In order to investigate the transition of the charge / discharge rate and the charge efficiency under different operating temperatures, cyclic voltammetry (CV) was performed using an apparatus as schematically shown in FIG.
As shown in FIG. 9, the CV measuring apparatus is roughly divided into a cell 20 in which an electrolyte and electrodes are stored, and a potentiostat that performs voltage / current control. In the cell 20, the sample electrode 21, the counter electrode 22, and the reference electrode 23 are disposed so as to be sufficiently immersed in the electrolyte solution 24, and these three electrodes are electrically connected to the potentiostat. Further, the oxygen introduction tube 25 is disposed so as to be immersed in the electrolytic solution 24, and oxygen is bubbled into the electrolytic solution 24 for a certain time from an oxygen supply source (not shown) installed outside the cell, and the electrolytic solution is oxygen. Saturated state. Circles 26 represent oxygen bubbles.
As the electrolytic solution 24, N-methyl-N-propylpiperidinium-bis (trifluoromethylsulfonyl) amine (hereinafter referred to as PP13-TFSA) is used, and LiN (SO ₂ CF ₃ ) is used as a lithium salt in the electrolytic solution. ₂ (Li-TFSA) was added after adjusting so that the lithium salt concentration would be 0.32 mol / kg.
Details of the configuration of the apparatus are as follows.

(Device configuration)
Sample electrode φ3mm glassy carbon rod electrode Counter electrode Ni ribbon Reference electrode Ag / Ag ⁺
Sweep speed 100mV / s
Oxygen bubbling time 30 minutes

FIG. 6 shows the electrochemical evaluation results at a Li salt concentration of 0.32 mol / kg. FIG. 6 is a cyclic voltammogram (CV) at a measurement temperature of 25 ° C., and shows the result of correcting the standard electrode potential (Li ⁺ + e ⁻ = Li) of lithium to 0V.
The first arrow in FIG. 6 indicates a reduction current value at 2.5 V when lithium oxide (Li-TFSA) is reduced. The second arrow indicates the oxidation current value of the reductant at 3.0 V, that is, the current value when the reductant is broken and returns to lithium oxide (Li-TFSA). Furthermore, the No. 4 region, that is, the region surrounded by the CV curve from 1.5 V to 2.5 V is the amount of reduction electricity, and the No. 3 region, that is, the region sandwiched by the CV curve from 3 V to 4 V is oxidized. The amount of electricity is shown respectively.
Based on these experimental values, a graph summarizing the reduction current value at 2.5 V as the discharge reaction rate (ie, discharge rate) and the oxidation current value at 3.0 V as the charge reaction rate (ie, charge rate) FIG. Further, FIG. 8 is a graph in which CV reversibility rate = [{oxidized electricity amount (3rd region) / reduced electricity amount (4th region)} × 100] and the CV reversible rate is summarized as charging efficiency. is there.

FIG. 7 is a graph summarizing the values of the discharge reaction rate and the charge reaction rate at a measurement temperature of 25 ° C., 40 ° C. or 60 ° C.
As can be seen from the white square plot showing the discharge reaction rate, the reduction current value was 0.2 A when the measurement temperature was 25 ° C., that is, the temperature near room temperature, and 0.9 A when the measurement temperature was 60 ° C. It became. On the other hand, as can be seen from the black triangle plot showing the charge reaction rate, the oxidation current value that was 0.1 A when the measurement temperature was 25 ° C., that is, the temperature near room temperature, was 2 when the measurement temperature was 60 ° C. 5A. That is, it can be seen that both the discharge rate and the charge rate improve as the temperature rises.

  FIG. 8 is a graph summarizing charging efficiency values at a measurement temperature of 25 ° C., 40 ° C., or 60 ° C. As can be seen from the graph, the charging efficiency, which was 50% or more when the measurement temperature was 25 ° C., that is, the temperature near room temperature, was less than 40% when the measurement temperature was 60 ° C. This indicates that the charging efficiency after discharging deteriorates when the temperature is high during discharging.

  From the above results, the discharge reaction rate and the charge reaction rate are improved as the operating temperature is increased, but the charging efficiency is lowered, and even if the operating temperature is simply increased, the performance of the battery is not necessarily improved. I understand that. Therefore, by setting the temperature at the time of discharging, that is, the operating temperature at the time of discharging to a temperature that is at least lower than the operating temperature at the time of charging, the metal-air battery can be improved in terms of discharge reaction speed, charge reaction speed, and charging efficiency. I understood.

DESCRIPTION OF SYMBOLS 11 Electrolyte layer 12 Air electrode layer 13 Negative electrode active material layer 14 Air electrode current collector 15 Negative electrode current collector 16 Air electrode 17 Negative electrode 20 CV cell 21 Sample electrode 22 Counter electrode 23 Reference electrode 24 Electrolytic solution 25 Oxygen introduction tube 26 Oxygen bubble 100 metal-air battery

Claims (4)

A metal-air battery system having a metal-air battery having at least an air electrode, a negative electrode, and an electrolyte interposed between the air electrode and the negative electrode,
(1) A temperature setting means for setting a target operating temperature during charging of the metal-air battery and a target operating temperature during discharging of the metal-air battery that is different from the target operating temperature during charging.
(2) Temperature control for limiting the temperature of the metal-air battery so as to be the target operating temperature at the time of charging and limiting the temperature so as to be the target operating temperature at the time of discharging. means,
(3) Temperature control monitoring means for monitoring the necessity of temperature control during charging and / or discharging for the metal-air battery,
(4) When charging and / or discharging, when the temperature control monitoring means determines that the temperature control of the metal-air battery is necessary, the temperature control operation mode for starting the temperature control of the metal-air battery is selected. When the temperature control monitoring unit determines that the temperature control of the metal-air battery is unnecessary, the temperature control stop mode for stopping the temperature control of the metal-air battery is selected, and the selected temperature control mode is executed. A metal-air battery system comprising temperature control mode switching means.   2. The metal-air battery system according to claim 1, wherein the temperature setting unit sets the discharge operation target temperature to a temperature lower than the charge operation target temperature. 3.   The temperature control means accumulates surplus heat generated from the metal-air battery at one of charging and discharging, and the surplus at one of charging and discharging. The metal air battery system of Claim 1 or 2 provided with the thermal storage part which warms up the said metal air battery using heat.   The metal-air battery system according to any one of claims 1 to 3 and a motor driven by electric power supplied from the metal-air battery system, wherein the temperature control means of the metal-air battery system includes: A motor driving body, wherein the motor driving body is a heat exchanging means for exchanging heat between the metal-air battery and the motor.