JP2008181853A - Air battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an air battery capable of restraining increased internal resistance caused by shortage of electrolytic liquid. <P>SOLUTION: The air battery comprises an air electrode having an air electrode layer including an conductive material and an air electrode current-collecting body for performing current-collection of the air electrode layer, a negative pole having a negative electrode layer including a negative electrode active material which occludes and discharges metal ions and a negative electrode current-collecting body for performing current collection of the negative electrode layer, and a separator arranged between the air electrode layer and negative electrode layer. When a volume change of an electrode accompanied with discharging or charging and discharging is generated, the air electrode layer and negative electrode layer in the air battery are always filled up by the electrolytic liquid. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an air battery that can suppress an increase in internal resistance due to shortage of electrolyte.

  The air battery is a nonaqueous battery using air (oxygen) as a positive electrode active material, and has advantages such as high energy density, easy size reduction, and weight reduction. In such an air battery, for example, when metal Li is used as the negative electrode active material, the following reactions (1) to (4) mainly occur.

  Conventionally, various studies have been conducted to make the most of the advantages of air batteries. For example, Patent Document 1 discloses a nonaqueous electrolyte air battery using a specific room temperature molten salt as a nonaqueous electrolyte. This was to prevent the solvent from volatilizing by using a specific room temperature molten salt, and to improve the discharge capacity at a high temperature and the discharge capacity after high-humidity storage. In Patent Document 2, a nonaqueous electrolyte battery including a positive electrode using a carbonaceous material having a specific pore capacity is disclosed. This was intended to increase the capacity of the battery by focusing on the pore capacity of the carbonaceous material. As described above, in the conventional research, attempts to improve the functionality of the constituent members have been mainstream.

However, the air battery has a problem in that the volume of the electrodes (air electrode and negative electrode) changes greatly with discharge or charge / discharge, resulting in a shortage of electrolyte. Specifically, using the above reaction, Li is eluted as Li ions at the negative electrode during discharge (reaction (1)), and lithium oxide is precipitated at the air electrode (reaction (2)). At this time, since the density of lithium oxide (Li ₂ O ₂ ) is larger than the density of Li, the entire electrode contracts as much as 35% by volume. As a result, there is a problem in that the amount of the electrolytic solution is insufficient at the end of discharge, and a part of the air electrode or the like is not immersed in the electrolytic solution, thereby increasing the internal resistance. In addition, when a carbon material such as graphite is used as the negative electrode active material as a material other than metal Li, the volume change at the negative electrode is small, but Li ₂ O ₂ is generated at the air electrode, and the electrolyte in the air electrode When the battery is pushed out, the electrolyte moves into the voids in the battery, and after the Li ₂ O ₂ is dissolved during charging, it becomes difficult for the electrolyte to return to the air electrode. As a result, the amount of the electrolyte is insufficient. After all, there was a problem that it led to internal resistance.
JP 2004-119278 A Japanese Patent No. 3515492

  This invention is made | formed in view of the said situation, and it aims at providing the air battery which can suppress the increase in internal resistance resulting from electrolyte shortage.

  In order to solve the above problems, in the present invention, an air electrode having an air electrode layer containing a conductive material and an air electrode current collector that collects the air electrode layer, and occludes / releases metal ions. A negative electrode layer containing a negative electrode active material, a negative electrode having a negative electrode current collector for collecting current of the negative electrode layer, and a separator disposed between the air electrode layer and the negative electrode layer. When the volume change of the electrode accompanying discharge occurs, the air battery is characterized in that the air electrode layer and the negative electrode layer are always filled with the electrolytic solution.

  According to the present invention, since the air electrode layer and the negative electrode layer are always filled with the electrolyte solution, it is possible to suppress an increase in internal resistance due to the electrolyte solution shortage.

  In the above invention, when the level of the electrolyte solution changes due to the volume change of the electrode accompanying discharge or charge / discharge, the lowest position of the electrolyte solution surface is the air electrode layer and the electrolyte layer. It is preferably higher than the position of the uppermost surface of the negative electrode layer. It is because it can prevent that electrolyte solution runs short by setting the quantity of electrolyte solution to become said position.

  The present invention also provides an air battery system comprising the air battery described above and at least one of a heating means for heating the electrolyte solution and a cooling means for cooling the electrolyte solution. .

  ADVANTAGE OF THE INVENTION According to this invention, it can be set as the air battery system excellent in electric power generation efficiency by providing at least one of a heating means and a cooling means with respect to an air battery.

  In the present invention, the above-described air battery is used, and at least one of heating the electrolyte during charging and cooling the electrolyte during discharging is performed. A control method is provided.

  According to the present invention, power generation efficiency can be improved by controlling the temperature of the electrolyte during charging and discharging.

  In this invention, there exists an effect that the air battery which can suppress the increase in internal resistance resulting from electrolyte shortage can be provided.

  Hereinafter, an air battery, an air battery system, and an air battery control method of the present invention will be described in detail.

A. Air Battery First, the air battery of the present invention will be described. The air battery of the present invention includes an air electrode having an air electrode layer containing a conductive material and an air electrode current collector that collects the air electrode layer, and a negative electrode active material that absorbs and releases metal ions. A negative electrode having a negative electrode layer and a negative electrode current collector that collects current from the negative electrode layer; and a separator disposed between the air electrode layer and the negative electrode layer; When the change occurs, the air electrode layer and the negative electrode layer are always filled with the electrolytic solution.

  According to the present invention, since the air electrode layer and the negative electrode layer are always filled with the electrolyte solution, it is possible to suppress an increase in internal resistance due to the electrolyte solution shortage. Conventionally, although it is known that the air electrode layer and the negative electrode layer may be temporarily filled with the electrolytic solution (for example, paragraph 70 of the specification of Patent Document 1), the air electrode layer and the negative electrode layer are always used as the electrolytic solution. There is nothing known about filling with. In the present invention, by always filling the air electrode layer and the negative electrode layer with the electrolytic solution, an increase in internal resistance due to the shortage of the electrolytic solution can be suppressed, and a higher performance air battery can be obtained.

  Next, the air battery of this invention is demonstrated using drawing. Fig.1 (a) is a schematic sectional drawing which shows an example of the air battery of this invention. FIG.1 (b) is a perspective view which shows the external appearance of the air battery shown by Fig.1 (a). The air battery shown in FIG. 1A includes a negative electrode current collector 2 formed on the inner bottom surface of a lower insulating case 1a, a negative electrode lead 2 'connected to the negative electrode current collector 2, and a negative electrode current collector 2 A negative electrode layer 3 made of metal Li formed thereon, an air electrode layer 4 containing carbon, an air electrode mesh 5 and an air electrode current collector 6 for collecting the air electrode layer 4, and an air electrode current collector 6, an air electrode lead 6 ′ connected to 6, a separator 7 installed between the negative electrode layer 3 and the air electrode layer 4, and an upper insulating case 1 b having a microporous film 8 provided to supply oxygen. And an electrolytic solution 9 for immersing the negative electrode layer 3 and the air electrode layer 4. In the present invention, an air electrode current collector 6 may be disposed on the air electrode mesh 5 as shown in FIG.

  FIG. 3 is a simplified cross-sectional view of the air battery shown in FIG. For convenience, the air electrode current collector, the negative electrode current collector, and the like are omitted. Since this air battery has a sufficiently large amount of the electrolytic solution 9 (FIG. 3A), for example, during discharge, the metal Li of the negative electrode layer 3 is eluted and the volume of the electrode is reduced. As a result, the electrolytic solution Even if the liquid level of 9 is lowered, the lowest position can be kept higher than the position of the uppermost surface of the air electrode layer 4 (FIG. 3B). Thereby, the air electrode layer 4 can always be filled with the electrolyte solution 9, and the increase in internal resistance resulting from the electrolyte solution shortage can be suppressed. During discharge, oxygen dissolved in the electrolyte is used for the reaction, but when the oxygen in the electrolyte begins to run short, oxygen is supplied to the electrolyte sequentially from the gas phase, so the reaction is continuous. To be done.

In the present invention, “the volume change of the electrode accompanying discharge or charge / discharge” refers to the density of the product when the metal ions move between the air electrode layer and the negative electrode layer during discharge or charge / discharge. It means the volume change of electrodes (air electrode and negative electrode) caused by the difference. When the air battery of the present invention is a primary battery, the volume change of the electrode accompanying “discharge” is considered, and when it is a secondary battery, the volume change of the electrode accompanying “charge / discharge” is taken into consideration. For example, when metal Li is used as the negative electrode active material, a reaction in which metal Li elutes in the negative electrode layer occurs during discharge (the above reaction (1)), and lithium oxide (Li ₂ O ₂ ) in the air electrode layer. Is generated (the above reaction (2)). At this time, since the density of the lithium oxide (Li ₂ O ₂ ) is larger than the density of the metal Li, the volume of the electrode (air electrode layer and negative electrode layer) decreases. When such a volume change of the electrode occurs, in the air battery of the present invention, the air electrode layer and the negative electrode layer are always filled with the electrolytic solution.
Hereinafter, the air battery of the present invention will be described separately for the material of the air battery and the structure of the air battery.

1. First, the material of the air battery of the present invention will be described. The air battery of the present invention has an air electrode, a negative electrode, a separator, an electrolytic solution, and a battery case.

(1) Air electrode The air electrode used in the present invention includes an air electrode layer containing a conductive material and an air electrode current collector that collects the air electrode layer. In the present invention, oxygen dissolved in the electrolytic solution reacts with metal ions in the air electrode, and a metal oxide is generated on the surface of the conductive material. For this reason, the air electrode layer has a gap that allows the electrolyte, which is a carrier of oxygen and metal ions, to move sufficiently.

  The conductive material 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, but in the present invention, the carbon material preferably has a porous structure. This is because the 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. Further, the conductive material may carry a catalyst. Examples of the catalyst include cobalt phthalocyanine and manganese dioxide.

  In the present invention, the air electrode layer only needs to contain at least a conductive material, but preferably further contains a binder for immobilizing the conductive material. Examples of the binder include polyvinylidene fluoride (PVdF) and polytetrafluoroethylene (PTFE). The content of the binder contained in the air electrode layer is not particularly limited. For example, it is preferably 30% by weight or less, and more preferably 1% by weight to 10% by weight.

  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, and titanium. Examples of the shape of the air electrode current collector include a foil shape, a plate shape, and a mesh (grid) shape. Among these, in the present invention, the shape of the air electrode current collector is preferably a mesh shape. 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 air battery cell may have another air electrode current collector (for example, a foil-shaped current collector) that collects charges collected by the mesh-shaped air electrode current collector. In the present invention, a battery case to be described later may also have the function of an air electrode current collector.

(2) Negative Electrode Next, the negative electrode used in the present invention will be described. The negative electrode used in the present invention has a negative electrode layer containing a negative electrode active material that absorbs and releases metal ions and a negative electrode current collector that collects current from the negative electrode layer.

  The negative electrode active material is not particularly limited as long as it can occlude / release metal ions. The metal ions are not particularly limited as long as they move between the air electrode and the negative electrode to generate an electromotive force. Specifically, lithium ions, sodium ions, aluminum ions, magnesium ions, cesium ions are used. An ion etc. can be mentioned, Among these, lithium ion is preferable.

  As the negative electrode active material capable of occluding and releasing lithium ions, the same negative electrode active materials used in general lithium ion batteries can be used. Specific examples include carbon materials such as metal lithium, lithium alloys, metal oxides, metal sulfides, metal nitrides, and graphite. Among these, metal lithium and carbon materials, particularly metal lithium are preferable. This is because metallic lithium elutes as lithium ions during discharge and has a large volume change as described in the above reaction (1).

  In the present invention, the negative electrode layer may contain at least a negative electrode active material, but may contain a binder for immobilizing the negative electrode active material, if necessary. About the kind of binder, the usage-amount, etc., since it is the same as that of the content described in "(1) Air electrode" mentioned above, description here is abbreviate | omitted.

  The material for the negative electrode current collector is not particularly limited as long as it has conductivity, and examples thereof include copper, stainless steel, and nickel. 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.

(3) Separator Next, the separator used in the present invention will be described. The separator used in the present invention is installed between the air electrode layer and the negative electrode layer. The separator is not particularly limited as long as it has a function of separating the air electrode layer and the negative electrode layer and retaining the electrolytic solution. For example, a porous film such as polyethylene or polypropylene; a resin nonwoven fabric, glass Nonwoven fabrics such as fiber nonwoven fabrics; and polymer materials used in lithium polymer batteries.

(4) Electrolyte Next, the electrolyte used for this invention is demonstrated. The electrolytic solution used in the present invention is usually obtained by dissolving an electrolyte in an organic solvent. Examples of the electrolyte include inorganic lithium salts such as LiPF ₆ , LiBF ₄ , LiClO _4, and LiAsF ₆ ; and LiCF ₃ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiC (CF ₃ SO ₂ ) ₃ , and the like. Organic lithium salts and the like can be mentioned.

  The organic solvent is not particularly limited as long as it can dissolve the electrolyte, but is preferably a solvent having high oxygen solubility. This is because the air electrode layer is always filled with the electrolytic solution, and oxygen dissolved in the solvent is used for the reaction. Specific examples of the organic solvent include ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), butylene carbonate, γ-butyrolactone, and sulfolane. , Acetonitrile, 1,2-dimethoxymethane, 1,3-dimethoxypropane, diethyl ether, tetrahydrofuran, 2-methyltetrahydrofuran and the like. Among them, in the present invention, a mixed solvent in which EC or PC and DEC or EMC are combined is preferable. In the present invention, a low-volatile liquid such as an ionic liquid can be used as the electrolytic solution. This is because the use of a low-volatile liquid can suppress a decrease in the electrolyte due to volatilization and can be used for a longer period of time.

(5) Battery Case Next, the battery case used in the present invention will be described. The shape of the battery case used in the present invention is not particularly limited as long as it can hold the above-described air electrode, negative electrode, separator, and electrolyte, but specifically, a coin type, a flat plate type, a cylindrical type Etc. The battery case usually has an air hole for supplying air. However, for example, in the case of an electrolyte circulation type air battery described later, an air hole is not particularly required.

2. Next, the structure of the air battery of the present invention will be described. In the air battery of the present invention, the air electrode layer and the negative electrode layer are always filled with the electrolytic solution when the volume of the electrode changes due to discharge or charge / discharge.

  An example of a configuration in which the air electrode layer and the negative electrode layer are always filled with the electrolyte when a volume change associated with discharge or charge / discharge occurs is a configuration in which the electrolyte is circulated. By circulating the electrolyte, charging / discharging can be performed without causing a gas-liquid interface between the electrolyte and the air, which existed when using a conventional air battery. This is because the air electrode layer and the negative electrode layer can always be filled with the electrolytic solution. In addition, there is an advantage that it is possible to prevent a decrease in the electrolyte due to volatilization. Further, by circulating the electrolytic solution, it is possible to efficiently remove oxygen generated by the charging reaction from the air electrode layer.

  Specifically, as shown in FIG. 4, the electrolyte solution is circulated by using an electrolyte solution transfer means 11 such as a motor to divide the electrolyte solution 9 into the negative electrode layer 3, the separator 7, and the air electrode layer 4. A configuration in which they are circulated in order can be given. At the time of discharge, oxygen 13 is supplied to the air electrode layer 4 using oxygen supply means 12 such as bubbling, and excess oxygen is removed by the exhaust means 14. If the oxygen supply means 12 can raise the oxygen concentration dissolved in the electrolyte 9 appropriately, the exhaust means 14 is not particularly necessary. Further, at the time of charging, the electrolytic solution may be circulated in the direction opposite to the flow of the electrolytic solution shown in FIG. In FIG. 4, for convenience, the air electrode current collector and the negative electrode current collector are omitted, but current collection may be performed by an appropriate method.

  That is, the present invention contains an air electrode having an air electrode layer containing a conductive material and an air electrode current collector that collects the air electrode layer, and a negative electrode active material that absorbs and releases metal ions. A negative electrode having a negative electrode layer and a negative electrode current collector that collects current from the negative electrode layer; a separator disposed between the air electrode layer and the negative electrode layer; an electrolyte solution that immerses the air electrode layer and the negative electrode layer; There can be provided an air battery having an electrolyte moving means for circulating the electrolyte solution and an oxygen supply means for supplying oxygen to the air electrode layer. Furthermore, the air battery preferably has an exhaust means for removing excess air.

  As another configuration in which the air electrode layer and the negative electrode layer are always filled with the electrolytic solution when a volume change caused by discharge or charge / discharge occurs, a configuration using a large amount of the electrolytic solution can be given. As described with reference to FIG. 3, by using a sufficiently large amount of the electrolyte solution 9, it is possible to prevent the air electrode layer 4 from becoming insufficient in the electrolyte solution.

  That is, in the present invention, when the level of the electrolyte solution changes due to the volume change of the electrode accompanying discharge or charge / discharge, the lowest position of the electrolyte solution surface is the air electrode layer. And it is preferable that it is higher than the position of the uppermost surface of the negative electrode layer. It is because it can prevent that electrolyte solution runs short by setting the quantity of electrolyte solution to become said position. For example, when metal Li is used for the negative electrode layer, a reaction in which lithium is eluted by discharge occurs, and the volume of the entire electrode is reduced. Therefore, normally, the level of the electrolytic solution at the end of discharge corresponds to the lowest position.

  The “top surfaces of the air electrode layer and the negative electrode layer” refers to the case where the top surface of the air electrode layer, the top surface of the negative electrode layer, the top surface of the air electrode layer and the negative electrode layer, depending on the configuration of the air battery. Sometimes it means the top surface. Each case will be described with reference to FIG. For convenience, the air electrode current collector and the negative electrode current collector are omitted.

  Fig.5 (a) is a schematic sectional drawing which shows the aspect in which the position where the liquid level of electrolyte solution fell most is higher than the uppermost surface of an air electrode layer. The air battery shown in FIG. 5A is an air battery in which the negative electrode layer 3, the separator 7, and the air electrode layer 4 are formed in this order from the inner bottom surface of the battery case 1, and the position where the electrolyte solution 9 is lowest. Is higher than the uppermost surface of the air electrode layer 4. This air battery has an advantage that oxygen can be easily supplied.

  FIG. 5B is a schematic cross-sectional view showing an aspect in which the position where the liquid level of the electrolytic solution is lowest is higher than the uppermost surface of the negative electrode layer. The air battery shown in FIG. 5B is an air battery formed in the order of the air electrode layer 4, the separator 7 and the negative electrode layer 3 from the inner bottom surface of the battery case 1, and the position where the electrolyte solution 9 is lowest. Is higher than the uppermost surface of the negative electrode layer 3. Furthermore, since this air battery has a structure in which the air electrode layer is below the negative electrode layer, the oxygen supply means 12 and the exhaust means 14 may be provided as necessary.

  FIG.5 (c) is a schematic sectional drawing which shows the aspect in which the position where the liquid level of electrolyte solution fell most is higher than the uppermost surface of an air electrode layer and a negative electrode layer. The air battery shown in FIG. 5C is a circle having a separator 7, a negative electrode layer 3 disposed on one surface of the separator 7, and an air electrode layer 4 disposed on the other surface of the separator 7. In the columnar air battery, the lowest position of the electrolyte 9 is higher than the uppermost surfaces of the negative electrode layer 3 and the air electrode layer 4.

  In this invention, it is preferable that the position where the said electrolyte solution fell most is higher than the position of the uppermost surface of the said air electrode layer and the said negative electrode layer. The difference in height between the position where the electrolyte solution is lowered and the position of the uppermost surface of the air electrode layer and the negative electrode layer varies depending on the volume of the battery case used, for example, 1 mm to 30 mm. In particular, it is preferable to be in the range of 3 mm to 10 mm. If the difference in height is too small, the electrolyte may be insufficient due to volatilization of the solvent, etc., and if the difference in height is too large, the supply of oxygen may be delayed and high-rate discharge characteristics may deteriorate. Because there is. Moreover, it is preferable that the initial input amount of the electrolytic solution is determined by measuring or calculating in advance the volume change of the electrode accompanying discharge or charge / discharge, and determining the optimal input amount.

  In addition, the shape of the electrode body (air electrode, negative electrode and separator) used in the present invention is not particularly limited as long as a desired air battery can be obtained. And a wound type.

B. Air Battery System Next, the air battery system of the present invention will be described. The air battery system of the present invention includes the air battery described above, and at least one of heating means for heating the electrolytic solution and cooling means for cooling the electrolytic solution.

  ADVANTAGE OF THE INVENTION According to this invention, it can be set as the air battery system excellent in electric power generation efficiency by providing at least one of a heating means and a cooling means with respect to an air battery. Here, it can be said that the air battery system of the present invention utilizes the temperature dependence of the solubility at which oxygen dissolves in the electrolyte. That is, in the discharge reaction in which oxygen is consumed in the air electrode layer, the electrolyte solution can be cooled to increase the amount of dissolved oxygen in the electrolyte solution, and in the charging reaction in which oxygen is generated in the air electrode layer. In order to reduce the amount of dissolved oxygen in the electrolytic solution, the electrolytic solution can be heated. Thereby, it can be set as the air battery system excellent in power generation efficiency. In the air battery used in the present invention, the air electrode layer and the negative electrode layer are always filled with the electrolytic solution. Therefore, it can be said that it is particularly important to control the amount of dissolved oxygen in the electrolytic solution.

  The reaction of the air battery is strongly influenced by the amount of dissolved oxygen in the electrolytic solution. This is described, for example, in Journal of The Electrochemical Society, 149 (9) A1190-A1195 (2002). Specifically, the inclusions on page A1194 describe that the solubility of oxygen in the electrolyte affects the discharge capacity. The amount of dissolved oxygen in the electrolyte is a factor that greatly affects battery characteristics. I understand that there is. The temperature dependence of the amount of dissolved oxygen in the electrolytic solution is described in, for example, Mitochondrial Physiology Network 6.3: 1-6 (2001-2006). Although the data shown here are the amount of dissolved oxygen in water and seawater, it can be seen that the amount of dissolved oxygen changes greatly as the temperature changes. Furthermore, in FIFTEENTH SYMPOSIUM ON THERMOPHYSICAL PROPERTIES, p164- (2003), it can be seen that even in a non-aqueous solvent such as perfluorocarbon, the amount of dissolved oxygen changes greatly when the temperature changes. In particular, in a system using perfluorocarbon as a solvent, it can be seen that when the temperature of 10 ° C. changes, the amount of dissolved oxygen in the electrolytic solution changes by about 10% to 20%.

  Next, the air battery system of the present invention will be described with reference to the drawings. FIG. 6 is an explanatory diagram for explaining an example of the air battery system of the present invention. In FIG. 6, the description of a part of the reference numerals overlapping those in FIG. 1 is omitted. The air battery system shown in FIG. 6 detects the temperature of the air battery, the heater 15 that heats the electrolyte 9 through the battery case 1 (the lower insulating case 1a and the upper insulating case 1b), and the temperature of the electrolyte 9. And a thermocouple 16 to be used. In this air battery system, during charging, an electric current is passed through the heater 15 to raise the temperature of the electrolyte 9 to a predetermined temperature. As a result, oxygen dissolved in the electrolytic solution 9 is easily released to the outside, the amount of dissolved oxygen around the air electrode layer 4 as a reaction field is reduced, and the charging reaction is promoted. After the end of charging, the supply of current is stopped and the temperature of the electrolyte 9 is lowered by natural cooling.

  FIG. 7 is an explanatory diagram for explaining another example of the air battery system of the present invention. In FIG. 7, the description of a part of the reference numerals overlapping those in FIG. 1 is omitted. The air battery system shown in FIG. 7 includes the air battery described above, a Peltier element 17 that heats and cools the electrolyte 9 via the battery case 1 (the lower insulating case 1a and the upper insulating case 1b), And a thermocouple 16 for detecting temperature. In this air battery system, during charging, a current is passed through the Peltier element 17 to raise the temperature of the electrolyte 9 to a predetermined temperature. As a result, oxygen dissolved in the electrolytic solution 9 is easily released to the outside, the amount of dissolved oxygen around the air electrode layer 4 as a reaction field is reduced, and the charging reaction is promoted. At the time of discharging, the electrolytic solution 9 is cooled by causing a current to flow through the Peltier element 17 in the direction opposite to that during charging. Thereby, the amount of oxygen dissolved in the electrolytic solution 9 is increased, and the discharge reaction is promoted.

  The air battery system of the present invention includes an air battery and at least one of heating means and cooling means. As described above, the air battery used in the present invention may be a primary battery or a secondary battery. When the air battery used for this invention is a secondary battery, it is preferable that the air battery system of this invention has a heating means. This is because the charging reaction peculiar to the secondary battery can be promoted. Especially, it is preferable that the air battery system of this invention has both a heating means and a cooling means. This is because both the charge reaction and the discharge reaction can be promoted. On the other hand, when the air battery used for this invention is a primary battery, it is preferable that the air battery system of this invention has a cooling means. This is because the discharge reaction can be promoted by providing the cooling means.

  The heating means used in the present invention is not particularly limited as long as it can heat the electrolytic solution of the air battery. For example, a method of heating through a battery case, a method of directly heating the electrolytic solution, etc. Can be mentioned. The method of heating through the battery case is a method of heating the electrolyte solution indirectly by heating the battery case. As a method for heating the battery case, for example, a method using a heater, a method using a Peltier element, a method of blowing hot air, a method of arranging a heating tube through which a heated liquid or gas is conducted, etc. Can be mentioned. On the other hand, as a method of directly heating the electrolytic solution, for example, a method of placing a heating tube through which heated liquid or gas is conducted inside a battery case, a method of bubbling heated inert gas into the electrolytic solution, heating And a method of injecting the electrolyte solution. Further, as shown in FIG. 4 described above, in the air battery in which the electrolyte solution is circulated, the electrolyte solution is heated in a region where the electrolyte solution is circulated outside the air cell (for example, a region in the vicinity of the electrolyte solution moving means 11). You can go.

  The temperature of the electrolytic solution heated by the heating means varies depending on the electrolytic solution used, the material of the constituent member, and the like, but is preferably in the range of, for example, 45 ° C to 60 ° C. This is because the amount of dissolved oxygen in the electrolytic solution is sufficiently low within the above range, and the charging reaction is promoted.

  The cooling means used in the present invention is not particularly limited as long as it is a method capable of cooling the electrolyte solution of the air battery. For example, a method of cooling through the battery case, a method of directly cooling the electrolyte solution, and the like. Can be mentioned. The method of cooling through the battery case is a method of cooling the electrolyte solution indirectly by cooling the battery case. Examples of the method for cooling the battery case include a method using a Peltier element, a method of blowing cool air, and a method of arranging a cooling pipe through which a cooled liquid or gas is conducted outside the battery case. On the other hand, as a method for directly cooling the electrolytic solution, for example, a method of arranging a cooling pipe through which the cooled liquid or gas is conducted inside the battery case, a method of bubbling the cooled oxygen gas into the electrolytic solution, And a method of injecting an electrolytic solution. Further, as shown in FIG. 4 described above, in the air battery in which the electrolyte solution is circulated, the electrolyte solution is cooled in a region where the electrolyte solution is circulated outside the air cell (for example, a region in the vicinity of the electrolyte solution moving means 11). You can go.

  The temperature of the electrolytic solution cooled by the cooling means varies depending on the electrolytic solution used, the material of the constituent member, and the like, but is preferably in the range of, for example, 0 ° C to 15 ° C. If the temperature of the electrolytic solution is too low, the ionic conductivity inside the electrolytic solution will decrease, causing problems that resistance will increase and the electrochemical reaction of the discharge will be disturbed, and if the electrolytic solution temperature is too high, This is because the amount of dissolved oxygen therein does not increase sufficiently.

  The air battery used in the present invention is the same as the contents described in the above “A. Air battery”, and thus the description thereof is omitted here. Moreover, it is preferable that the air battery system of this invention further has a liquid temperature detection means which detects the liquid temperature of electrolyte solution. This is because the temperature of the electrolytic solution can be detected more accurately, and an air battery system with excellent power generation efficiency can be obtained. As said liquid temperature detection means, a thermocouple etc. can be mentioned, for example. In the present invention, since the amount of dissolved oxygen in the vicinity of the air electrode layer is important, the liquid temperature detecting means is preferably disposed in the vicinity of the air electrode.

C. Next, a method for controlling an air battery according to the present invention will be described. The air battery control method of the present invention is characterized in that the above-described air battery is used and at least one of heating the electrolyte solution during charging and cooling the electrolyte solution during discharging is performed. To do.

  According to the present invention, power generation efficiency can be improved by controlling the temperature of the electrolyte during charging and discharging. Specifically, by heating the electrolytic solution during charging, the amount of dissolved oxygen in the electrolytic solution can be reduced, and the charging reaction can be promoted. In addition, by cooling the electrolyte during discharge, the amount of dissolved oxygen in the electrolyte can be increased, and the discharge reaction can be promoted.

  The air battery used in the present invention, the method for heating / cooling the electrolyte, the temperature of the electrolyte during heating / cooling, etc. are described in the above-mentioned “A. Air battery” and “B. Air battery system”. Since it is the same as the content, description here is abbreviate | omitted.

  As described above, the air battery used in the present invention may be a primary battery or a secondary battery. When the air battery used for this invention is a secondary battery, it is preferable that the control method of the air battery of this invention heats electrolyte solution in the case of charge. This is because the charging reaction peculiar to the secondary battery can be promoted. Especially, it is preferable that the control method of the air battery of this invention performs both heating an electrolyte solution in the case of charge, and cooling an electrolyte solution in the case of discharge. This is because both the charge reaction and the discharge reaction can be promoted. On the other hand, when the air battery used in the present invention is a primary battery, the air battery control method of the present invention preferably cools the electrolyte during discharge. This is because the discharge reaction can be promoted.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has substantially the same configuration as the technical idea described in the claims of the present invention, and any device that exhibits the same function and effect is the present invention. It is included in the technical scope of the invention.

Hereinafter, the present invention will be described in more detail with reference to examples.
[Example]
In this example, a coin cell type air lithium battery was produced. The following coin cells were assembled in an argon box.
A schematic diagram of a coin cell is shown in FIG. Both the negative electrode case 22 and the air electrode case 20 are made of SUS material, and the air electrode case 20 has a plurality of through holes 29 having a diameter of 2 mm. A metal lithium foil 24 is installed on the negative electrode case 22. As the metal lithium foil 24, a sheet having a thickness of 250 μm punched out with a diameter of 18 mm was used. A polyethylene separator 25 was placed on the metal lithium foil 24. The separator 25 used was punched to a diameter of 19.5 mm with a thickness of 25 μm.

  Next, the electrolytic solution 23 was injected from above the separator 25 with a dropper. Thereafter, an air electrode was installed on the separator 25. As the air electrode, an air electrode mesh 26 was pressed into the air electrode mesh 26 and pressed into the air electrode mesh 26. The air electrode mesh 26 is a Ni mesh having a thickness of 150 μm and a diameter of 15 mm. The air electrode mixture 27 was prepared by kneading 90 parts by weight of ketjen black and 5 parts by weight of manganese dioxide in a mortar, adding polytetrafluoroethane (hereinafter abbreviated as PTFE), and further kneading. It was used. An air electrode case 20 was put in pellets of the air electrode mixture 27. The air electrode current collector 28 is installed in the air electrode case 20 by welding. The air electrode current collector 28 was a nickel mesh having a thickness of 150 μm and a diameter of 15 mm. A gasket 21 was fitted into the air electrode case 20 to obtain an air electrode plate.

  The air electrode plate was put on a separator immersed in an electrolytic solution, combined, and then the negative electrode case and the air electrode case were joined using a coin cell caulking machine (manufactured by Hosen). The obtained coin cell was fitted into a cell case with a lead attached in advance, and the battery was mounted in a glass sealed container.

  The attached state is shown in FIG. A gas introduction pipe 35 and an exhaust pipe 30 are attached in the glass sealed container. The cell was set in a container, sealed, and taken out from the argon box. Next, oxygen gas was sealed from the gas introduction pipe 35 of the container, and the operation of discharging from the exhaust pipe 30 was performed for 5 minutes to replace the argon atmosphere with the oxygen atmosphere. First, this was taken as a comparative example.

  Next, when the cell was attached to the sealed container in the argon box, 60 ml of the electrolytic solution 41 was added to the Teflon (registered trademark) container 40, and the cell was immersed therein. This is shown in FIG. The cell was set at a depth of about 2 cm from the liquid level. Thereafter, the glass container was sealed, removed from the argon box, and replaced with an oxygen gas atmosphere in the same manner as in the comparative example. This was taken as an example.

  A discharge test was performed using the battery. Discharging was performed at a constant current of 0.2 mA and stopped when 2V was reached. During the test, the cell was set in a constant temperature bath at 25 ° C. The obtained discharge curve is shown in FIG. In both cases, a flat discharge portion was observed around 2.6 V, but the comparative example reached 2 V considerably faster than the examples. When the discharge capacity of the example was 100%, the comparative example had a discharge capacity of about 47%. This is presumably because part of the air electrode was dried and the electrolyte was depleted. On the other hand, in the case of Example, since it is always immersed in electrolyte solution, it is thought that the discharge characteristic became better than the comparative example.

It is explanatory drawing explaining the air battery of this invention. It is explanatory drawing explaining the air battery of this invention. It is explanatory drawing explaining the air battery of this invention. It is explanatory drawing explaining the method to circulate electrolyte solution. It is explanatory drawing explaining the positional relationship of the liquid level of electrolyte solution, and uppermost surfaces, such as an air electrode layer. It is explanatory drawing explaining an example of the air battery system of this invention. It is explanatory drawing explaining the other example of the air battery system of this invention. It is explanatory drawing explaining the coin cell used in the Example. It is explanatory drawing explaining the battery used in the Example. It is explanatory drawing explaining the battery used in the Example. It is a graph which shows the result of a discharge test.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Battery case 1a ... Lower insulating case 1b ... Upper insulating case 2 ... Negative electrode collector 2 '... Negative electrode lead 3 ... Negative electrode layer 4 ... Air electrode layer 5 ... Air electrode mesh 6 ... Air electrode current collector 6' ... Air Electrode lead 7… Separator 8… Microporous membrane 9… Electrolyte

Claims (4)

An air electrode having an air electrode layer containing a conductive material and an air electrode current collector for collecting the air electrode layer, a negative electrode layer containing a negative electrode active material that absorbs and releases metal ions, and the negative electrode layer A negative electrode having a negative electrode current collector for collecting current, and a separator disposed between the air electrode layer and the negative electrode layer,
An air battery characterized in that the air electrode layer and the negative electrode layer are always filled with an electrolytic solution when a volume change of the electrode accompanying discharge or charge / discharge occurs.   When the level of the electrolyte solution changes due to the volume change of the electrode accompanying discharge or charge / discharge, the lowest position of the electrolyte solution surface is the uppermost surface of the air electrode layer and the negative electrode layer. The air battery according to claim 1, wherein the air battery is higher than the position of the air battery.   An air battery system comprising: the air battery according to claim 1; and at least one of a heating means for heating the electrolyte solution and a cooling means for cooling the electrolyte solution.   3. Air using the air battery according to claim 1 or 2, wherein at least one of heating the electrolyte during charging and cooling the electrolyte during discharging is performed. Battery control method.

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