JP5223425B2 - Air battery - Google Patents

Description

  The present invention relates to an air battery excellent in output characteristics and cycle characteristics.

  The air battery is a battery using air (oxygen) as a positive electrode active material, and has advantages such as high energy density, easy size reduction and weight reduction. Therefore, it has been attracting attention as a high-capacity secondary battery that exceeds the widely used lithium ion secondary battery. Here, for example, in an air secondary battery using metal Li as the negative electrode active material, it is known that the following reactions (1) to (6) mainly occur.

  Conventionally, attempts have been made to improve the performance of air batteries, focusing on the electrolyte of air batteries. For example, Patent Document 1 discloses a nonaqueous electrolyte air battery using a molten salt containing a specific anion component as a nonaqueous electrolyte. The purpose of this technology is to obtain a non-aqueous electrolyte air battery that contains a specific anion component and is excellent in large current discharge characteristics and capacity retention after high-temperature storage by using a molten salt having a low vapor pressure. Was.

  Patent Document 2 discloses an air battery using a hydrophobic nonaqueous electrolyte containing a room temperature molten salt (for example, trimethylpropylammonium bis (trifluoromethylsulfonyl) imide) having a melting point of 60 ° C. or lower. . This technology uses a hydrophobic non-aqueous electrolyte containing a specific room temperature molten salt to suppress the dissolution of oxygen and moisture in the electrolyte and to prevent the metal negative electrode from being deteriorated by oxygen and moisture. An object of the present invention is to obtain an air battery in which deterioration of characteristics is suppressed.

  Moreover, in patent document 3, it has the nonaqueous electrolyte solution containing the organic carbonate compound which has the frame | skeleton represented by specific chemical formula, and coat | covered the carbon material surface of a positive electrode with the decomposition product of said organic carbonate compound A non-aqueous electrolyte battery is disclosed. This technology suppresses volatilization of the electrolyte near the surface of the carbon material by coating the surface of the carbon material with a decomposition product of an organic carbonate compound having a skeleton represented by a specific chemical formula. An object of the present invention is to obtain a nonaqueous electrolyte battery capable of discharging for a long time by suppressing the resulting decrease in discharge capacity.

Japanese Patent Laid-Open No. 2005-26023 JP 2005-116317 A JP 2003-100309 A

  However, the conventional air battery cannot be said to have sufficiently high output characteristics and cycle characteristics. The present invention has been made in view of the above circumstances, and a main object thereof is to provide an air battery excellent in output characteristics and cycle characteristics.

  As a result of intensive studies by the present inventors in order to solve the above problems, the surface of the conductive material used for the air electrode layer is modified by using an electrolyte containing a sulfur-containing cyclic compound in an air battery. As a result, it has been found that the output characteristics and cycle characteristics of an air battery are improved by facilitating movement of metal ions (for example, lithium ions). The present invention has been made based on such knowledge.

  That is, in the present invention, 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, and the negative electrode layer A negative electrode having a negative electrode current collector for collecting current, a separator disposed between the air electrode layer and the negative electrode layer, an electrolyte responsible for conduction of metal ions between the air electrode layer and the negative electrode layer, It is an air battery which has this, Comprising: The said electrolyte contains a sulfur containing cyclic compound, The air battery characterized by the above-mentioned is provided.

  According to the present invention, since the electrolyte contains a sulfur-containing cyclic compound, for example, the sulfur-containing cyclic compound is reduced and decomposed during the first discharge to form a film that covers the surface of the conductive material. The By forming this film, metal ions (for example, lithium ions) easily move, and an air battery excellent in output characteristics and cycle characteristics can be obtained.

  Further, in the present invention, 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, and the negative electrode layer A negative electrode having a negative electrode current collector for collecting current, a separator disposed between the air electrode layer and the negative electrode layer, an electrolyte responsible for conduction of metal ions between the air electrode layer and the negative electrode layer, The electrolyte contains a sulfur-containing cyclic compound, and a decomposition product obtained by decomposing all or part of the sulfur-containing cyclic compound covers the surface of the conductive material. An air battery is provided.

  According to the present invention, since the decomposition product formed by decomposing all or part of the sulfur-containing cyclic compound covers the surface of the conductive material, metal ions (for example, lithium ions) can easily move, An air battery having excellent output characteristics and cycle characteristics can be obtained.

  In the said invention, it is preferable that the said sulfur containing cyclic compound is a compound represented by following General formula (1).

(In General Formula (1), R ₁ and R ₂ are independent and are functional groups capable of forming a ring with each other.) This is because the output characteristics and cycle characteristics can be further improved.

  In the above invention, the compound represented by the general formula (1) is ethylene sulfite, propylene sulfite, butylene sulfite, vinylene sulfite, phenylethylene sulfite, or a part of these constituent elements is a halogen element. It is preferable that they are substituted. This is because the output characteristics and cycle characteristics can be further improved.

  In the said invention, it is preferable that the said sulfur containing cyclic compound is a compound represented by following General formula (2).

(In General Formula (2), R ₃ and R ₄ are independent and are functional groups capable of forming a ring with each other.) This is because the output characteristics and cycle characteristics can be further improved.

  In the said invention, the compound represented by the said General formula (2) is 1, 3- propane sultone, 1, 4- butane sultone, 3-phenyl- 1, 3- propane sultone, 4-phenyl- 1, 4-. Butane sultone or a part of these constituent elements is preferably substituted with a halogen element. This is because the output characteristics and cycle characteristics can be further improved.

  In the said invention, it is preferable that the said sulfur containing cyclic compound is a compound represented by following General formula (3).

(In General Formula (3), R ₅ and R ₆ are independent and are functional groups capable of forming a ring with each other.) This is because the output characteristics and cycle characteristics can be further improved.

  In the above invention, the compound represented by the general formula (3) is sulfolane, 2-methylsulfolane, 3-methylsulfolane, 2-ethylsulfolane, 3-ethylsulfolane, 2,4-dimethylsulfolane, 2-phenyl. Sulfolane, 3-phenylsulfolane, sulfolene, 3-methylsulfolene, or a part of these constituent elements is preferably substituted with a halogen element. This is because the output characteristics and cycle characteristics can be further improved.

  In the said invention, it is preferable that the said sulfur containing cyclic compound is a compound represented by following General formula (4).

(In General Formula (4), R ₇ and R ₈ are independent and are functional groups capable of forming a ring with each other.) This is because the output characteristics and cycle characteristics can be further improved.

  In the above invention, the compound represented by the general formula (4) is an ethylene glycol sulfate ester, 1,2-propanediol sulfate ester, 1,3-propanediol sulfate ester, or a part of these constituent elements. It is preferable that it is substituted with a halogen element. This is because the output characteristics and cycle characteristics can be further improved.

  In this invention, there exists an effect that the air battery excellent in the output characteristic and cycling characteristics can be provided.

  Hereinafter, the air battery of the present invention will be described in detail.

  The air battery of the present invention is greatly characterized in that an electrolyte containing a sulfur-containing cyclic compound is used. Furthermore, the air battery of the present invention can be roughly divided into two embodiments before and after the sulfur-containing cyclic compound is decomposed and coated on the surface of the conductive material contained in the air electrode layer. Hereinafter, the air battery of the present invention will be described for each embodiment.

1. First Embodiment First, a first embodiment of the air battery of the present invention will be described. The air battery of this embodiment includes an air electrode layer having a conductive material and an air electrode current collector that collects the air electrode layer, a negative electrode layer containing a negative electrode active material, and the negative electrode layer. A negative electrode having a negative electrode current collector for collecting the current, a separator disposed between the air electrode layer and the negative electrode layer, an electrolyte responsible for conduction of metal ions between the air electrode layer and the negative electrode layer, , Wherein the electrolyte contains a sulfur-containing cyclic compound.

  According to this embodiment, since the electrolyte contains a sulfur-containing cyclic compound, for example, the sulfur-containing cyclic compound is reduced and decomposed at the time of the first discharge to form a film that covers the surface of the conductive material. Is done. By forming this film, metal ions (for example, lithium ions) easily move, and an air battery excellent in output characteristics and cycle characteristics can be obtained. In this embodiment, a sulfur-containing cyclic compound is contained in the electrolyte. Thereby, when the sulfur-containing cyclic compound is decomposed, ring-opening decomposition occurs first, so that the conductive material can be coated in a large fragment state. On the other hand, when a sulfur-containing chain compound (for example, DMSO) is contained in the electrolyte, it is assumed that molecular chains are broken apart during decomposition, and a good film is not formed. That is, in the present embodiment, a film in which metal ions (for example, lithium ions) can easily move can be formed by using a cyclic sulfur-containing compound.

Next, the air battery of this embodiment is demonstrated using drawing. Fig.1 (a) is a schematic sectional drawing which shows an example of the air battery of this embodiment. 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 and formed thereon, an air electrode layer 4 containing a conductive material, 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 Upper insulating case having an air electrode lead 6 ′ connected to the electric body 6, a separator 7 installed between the negative electrode layer 3 and the air electrode layer 4, and a microporous film 8 provided for supplying oxygen. 1b, and the negative electrode layer 3 and the air electrode layer 4, and the electrolyte solution 9 containing a sulfur-containing cyclic compound.
Hereinafter, the air battery of this embodiment is demonstrated for every structure.

(1) Electrolyte The electrolyte used in the present embodiment is responsible for the conduction of metal ions between the air electrode layer and the negative electrode layer, and contains at least a sulfur-containing cyclic compound.

(I) Sulfur-containing cyclic compound First, the sulfur-containing cyclic compound used in this embodiment will be described. The sulfur-containing cyclic compound used in the present embodiment is not particularly limited as long as it has a sulfur element (S) and has a cyclic structure, but preferably has an S═O bond. Although details are unknown, since the oxygen element of the S═O bond has an unshared electron pair, a film having an S═O bond is formed on the surface of the conductive material, so that lithium in the vicinity of the film is formed. It is considered that ions easily move and oxygen near the film is easily adsorbed.

  In this embodiment, the sulfur-containing cyclic compound is preferably a compound represented by the general formula (1) described above.

In the general formula (1), R ₁ and R ₂ are independent and are functional groups capable of forming a ring with each other. In this embodiment, the main skeleton of the ring constituent part formed by R ₁ and R ₂ is preferably formed from carbon. Furthermore, the main skeleton (carbon main skeleton) formed from the carbon may be formed only from a saturated bond or may include an unsaturated bond. The carbon main skeleton may have an arbitrary side chain functional group. Examples of the side chain functional group include an alkyl group, an alkenyl group, and an aryl group. Examples of the alkyl group include a methyl group, an ethyl group, and a propyl group. Examples of the alkenyl group include a vinyl group and a propenyl group. Examples of the aryl group include a phenyl group and a naphthyl group. In this embodiment, part or all of the hydrogen element bonded to the carbon main skeleton or part or all of the hydrogen element of the side chain functional group may be substituted with a halogen element. In particular, in this embodiment, it is preferable that the hydrogen element of the sulfur-containing cyclic compound is substituted with a halogen element in the range of 1 to 3. Examples of the halogen element include a fluorine element, a chlorine element, a bromine element, and an iodine element. Among these, a fluorine element is preferable. This is because the amount of dissolved oxygen in the electrolytic solution can be improved.

  In particular, in this embodiment, the compound represented by the general formula (1) contains ethylene sulfite, propylene sulfite, butylene sulfite, vinylene sulfite, phenylethylene sulfite, or a part of these constituent elements. It is preferable that it is substituted with a halogen element. In this embodiment, a component obtained by substituting a part of the constituent elements of the compound with a halogen element can be used. Among them, as described above, one of the hydrogen elements bonded to the carbon main skeleton of the compound is used. It is preferable that a part or the whole or a part or all of the hydrogen element contained in the side chain functional group of the compound is substituted with a halogen element. The same applies to the compounds represented by the general formulas (2) to (4) described later.

  Moreover, in this embodiment, it is preferable that a sulfur containing cyclic compound is a compound represented by General formula (2) mentioned above.

In the general formula (2), R ₃ and R ₄ are independent and are functional groups capable of forming a ring with each other. The preferred embodiments of R ₃ and R ₄ are the same as the embodiments of R ₁ and R ₂ in the general formula (1) described above, and therefore description thereof is omitted here.

  In particular, in this embodiment, the compound represented by the general formula (2) is 1,3-propane sultone, 1,4-butane sultone, 3-phenyl-1,3-propane sultone, 4-phenyl-1, It is preferable that 4-butane sultone or a part of these constituent elements is substituted with a halogen element.

  Moreover, in this embodiment, it is preferable that a sulfur containing cyclic compound is a compound represented by General formula (3) mentioned above.

In the general formula (3), R ₅ and R ₆ are independent and are functional groups capable of forming a ring with each other. The preferred embodiments of R ₅ and R ₆ are the same as the embodiments of R ₁ and R ₂ in the general formula (1) described above, so description thereof is omitted here.

  In particular, in this embodiment, the compound represented by the general formula (3) is sulfolane, 2-methylsulfolane, 3-methylsulfolane, 2-ethylsulfolane, 3-ethylsulfolane, 2,4-dimethylsulfolane, 2 -Phenylsulfolane, 3-phenylsulfolane, sulfolene, 3-methylsulfolene, or a part of these constituent elements is preferably substituted with a halogen element.

  Moreover, in this embodiment, it is preferable that a sulfur containing cyclic compound is a compound represented by General formula (4) mentioned above.

In the general formula (4), R ₇ and R ₈ are independent and are functional groups capable of forming a ring with each other. The preferred embodiments of R ₇ and R ₈ are the same as the embodiments of R ₁ and R ₂ in the general formula (1) described above, so description thereof is omitted here.

  In particular, in this embodiment, the compound represented by the general formula (4) is ethylene glycol sulfate, 1,2-propanediol sulfate, 1,3-propanediol sulfate, or one of these constituent elements. It is preferable that the part is substituted with a halogen element.

  In addition, the content of the sulfur-containing cyclic compound in the electrolyte varies greatly depending on the specific surface area and pore volume of the conductive material, and is not particularly limited. In addition, the sulfur-containing cyclic compound used in the present embodiment may be liquid at normal temperature or solid at normal temperature.

(Ii) Form of electrolyte The form of the electrolyte used in this embodiment is not particularly limited as long as it contains a sulfur-containing cyclic compound and has metal ion conductivity. Examples thereof include solid forms, and liquid and gel forms, particularly liquid forms are preferred. Specific examples of the liquid electrolyte include an electrolytic solution and an ionic liquid. Among them, the electrolytic solution is preferable.

  The electrolytic solution usually has a supporting salt and a sulfur-containing cyclic compound. Here, when the sulfur-containing cyclic compound is solid at room temperature, the electrolytic solution usually further contains a solvent in addition to the supporting salt and the sulfur-containing cyclic compound. On the other hand, when the sulfur-containing cyclic compound is liquid at room temperature, the electrolytic solution may contain only a supporting salt and a sulfur-containing cyclic compound, or contain a supporting salt, a sulfur-containing cyclic compound and a solvent. There may be. In the former case, it is preferable that the sulfur-containing cyclic compound has solubility enough to achieve a desired supported salt concentration.

  The type of the supporting salt used in the electrolytic solution is preferably selected as appropriate according to the type of metal ion to be conducted. Hereinafter, as an example of the electrolytic solution, an electrolytic solution used for a lithium-air battery will be described.

Examples of the supporting salt used for the electrolyte of the lithium air battery 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 , LiN (C _And organic lithium salts such as ₂ F ₅ SO ₂ ) ₂ and LiC (CF ₃ SO ₂ ) ₃ . The content of the supporting salt in the electrolytic solution is not particularly limited. For example, it is within the range of 0.2 mol / l to 5 mol / l, and particularly within the range of 0.5 mol / l to 3 mol / l. preferable.

  Moreover, as above-mentioned, the electrolyte solution of a lithium air battery may contain the solvent. As said solvent, the thing similar to the nonaqueous solvent used for the electrolyte solution of a general lithium air battery can be used, Specifically, ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC) ), Diethyl carbonate (DEC), ethyl methyl carbonate (EMC), butylene carbonate, γ-butyrolactone, sulfolane, acetonitrile, 1,2-dimethoxymethane, 1,3-dimethoxypropane, diethyl ether, tetrahydrofuran, 2-methyltetrahydrofuran, And a mixed solvent thereof. Among these, in this embodiment, a mixed solvent in which EC or PC and DEC or EMC are combined is preferable. Moreover, the electrolyte solution used for this embodiment may contain an ionic liquid.

  In addition, in this embodiment, the electrolyte for air batteries characterized by containing a sulfur containing cyclic compound can also be provided.

(2) Air electrode Next, the air electrode used for this embodiment is demonstrated. The air electrode used in this embodiment has an air electrode layer containing a conductive material and an air electrode current collector that collects the air electrode layer.

  The air electrode layer contains at least a conductive material. The conductive material is not particularly limited as long as it has conductivity, and examples thereof include a carbon material. Further, the carbon material may have a porous structure or may not have a porous structure. However, in the present embodiment, 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. The content of the conductive material in the air electrode layer is, for example, preferably in the range of 65% to 99% by weight, and more preferably in the range of 75% to 95% by weight. 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.

  In this embodiment, the conductive material preferably carries a catalyst. This is because the electrode reaction is performed more smoothly. Examples of the catalyst include cobalt phthalocyanine and manganese dioxide. The catalyst content in the air electrode layer is, for example, preferably in the range of 1% by weight to 30% by weight, and more preferably in the range of 5% by weight to 20% by weight. 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.

  The air electrode layer only needs to 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 weight% or less, especially 1 weight%-10 weight%.

  The thickness of the air electrode layer varies depending on the application of the air battery and the like, but is preferably in the range of 2 μm to 500 μm, and more preferably in the range of 5 μm to 300 μm.

  On the other hand, the air electrode current collector has a function of collecting 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 embodiment, it is preferable that the shape of the air electrode current collector is 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 of the present embodiment 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. Moreover, in this embodiment, the battery case mentioned later may have the function of the air electrode current collector.

(3) Negative Electrode Next, the negative electrode used in this embodiment will be described. The negative electrode used in this embodiment has a negative electrode layer containing a negative electrode active material and a negative electrode current collector that collects current from the negative electrode layer.

  The negative electrode layer contains at least a negative electrode active material. As a negative electrode active material, the negative electrode active material of a general air battery can be used, and it is not specifically limited. In addition, when the air battery of this embodiment is a secondary battery, a negative electrode active material is what can occlude / release metal ion normally. When the air battery of this embodiment is a lithium-air secondary battery, examples of the negative electrode active material used include carbon materials such as metal lithium, lithium alloy, metal oxide, metal sulfide, metal nitride, and graphite. Among them, metallic lithium and carbon materials are preferable, and metallic lithium is more preferable from the viewpoint of increasing capacity.

  Although the said negative electrode layer should just contain a negative electrode active material at least, it may contain the binder which fixes a negative electrode active material as needed. Since the kind of binder, the amount of use, and the like are the same as the contents described in “(2) Air electrode” described above, description thereof is omitted here.

  On the other hand, the negative electrode current collector has a function of collecting current in the negative electrode layer. The material of the negative electrode current collector 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 this embodiment, a battery case described later may have the function of a negative electrode current collector.

(4) Separator Next, the separator used in this embodiment will be described. The separator used in this embodiment 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 electrically separating the air electrode layer and the negative electrode layer. For example, a porous film such as polyethylene and polypropylene; a resin nonwoven fabric, a glass fiber nonwoven fabric and the like Nonwoven fabrics; and polymer materials used in lithium polymer batteries.

(5) Battery Case Next, the battery case used in this embodiment will be described. The shape of the battery case used in this embodiment 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 cylinder, A laminating type etc. can be mentioned. The battery case may be an open battery case or a sealed battery case. Here, the open battery case refers to a battery case that can come into contact with the atmosphere, and refers to the battery case as shown in FIG. On the other hand, when the battery case is a sealed battery case, it is preferable to provide an air (oxygen) supply pipe and a discharge pipe in the sealed battery case.

(6) Air battery The air battery of this embodiment is not particularly limited as long as the electrolyte has the above-described sulfur-containing cyclic compound. Among them, in the air battery of this embodiment, it is preferable that the air electrode layer and the negative electrode layer are always filled with the electrolytic solution when the volume change of the electrode accompanying discharge or charge / discharge occurs. This is because if the air electrode layer and the negative electrode layer are always filled with the electrolytic solution, an increase in internal resistance due to the shortage of the electrolytic solution can be suppressed.

Note that the air battery has a problem that the volume of the electrodes (air electrode and negative electrode) changes greatly with discharge or charge / discharge, resulting in a situation where the electrolyte is insufficient. Specifically, during discharge, Li elutes as Li ions at the negative electrode, and lithium oxide precipitates at the air electrode. At this time, since the density of the lithium oxide (for example, 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 or the like is generated at the air electrode, and electrolysis in the air electrode When the liquid is pushed out, the electrolyte moves to 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. However, there is also a problem that it leads to internal resistance. In contrast, even when the volume of the electrode changes due to discharge or charge / discharge, the air electrode layer and the negative electrode layer always fill the electrolyte solution, thereby increasing the internal resistance due to insufficient electrolyte solution. It can be suppressed.

  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. Even if it exists, an air electrode layer and a negative electrode layer can always be satisfy | filled with electrolyte 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. 2, the electrolytic solution is circulated by using an electrolytic solution moving means 11 such as a motor to divide the electrolytic 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. 2, 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.

  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. By using a sufficiently large amount of electrolyte, it is possible to prevent the air electrode layer from becoming insufficient.

  That is, in this embodiment, when the level of the electrolyte solution changes due to a change in the volume of the electrode due to discharge or charge / discharge, the position at which the liquid level of the electrolyte solution is lowered is the air electrode. It is preferable that it is higher than the position of the uppermost surface of the layer and 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. 3A is a schematic cross-sectional view showing an aspect in which the position where the liquid level of the electrolytic solution is lowered is higher than the uppermost surface of the air electrode layer. The air battery shown in FIG. 3A 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. 3B is a schematic cross-sectional view illustrating 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. 3B is an air battery in which the air electrode layer 4, the separator 7 and the negative electrode layer 3 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 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. 3C 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 surfaces of the air electrode layer and the negative electrode layer. The air battery shown in FIG. 3C has 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 embodiment, it is preferable that the position where the electrolyte solution is lowered is higher than the positions of the uppermost surfaces of the air electrode layer and the 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 air battery of this embodiment may be a primary battery or a secondary battery. Furthermore, examples of the air battery include a lithium air battery, a sodium air battery, a magnesium air battery, a calcium air battery, and a potassium air battery, and among them, a lithium air battery is preferable. In addition, the use of the air battery according to the present embodiment is not particularly limited, and examples thereof include a vehicle mounting application, a stationary power supply application, and a household power supply application.

(7) Air Battery Manufacturing Method Next, the air battery manufacturing method of this embodiment will be described. The method for producing an air battery according to this embodiment is not particularly limited as long as the above-described air battery can be obtained, and a method similar to a general method for producing an air battery can be used. . For example, when a coin cell type air battery is manufactured using an electrolytic solution containing a sulfur-containing cyclic compound, first, a negative electrode having a negative electrode layer and a negative electrode current collector is used as a negative electrode battery case in an inert gas atmosphere. And then placing a separator on the negative electrode layer, then injecting an electrolytic solution containing a sulfur-containing cyclic compound from the separator, and then, air electrode layer and air electrode current collector A method of arranging the air electrode having the air electrode facing the separator side, then arranging the air electrode in the air electrode side battery case, and finally caulking them can be exemplified.

  In the present embodiment, 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, and the negative electrode layer A negative electrode having a negative electrode current collector for collecting the current, a separator disposed between the air electrode layer and the negative electrode layer, an electrolyte responsible for conduction of metal ions between the air electrode layer and the negative electrode layer, A method for producing an air battery, characterized in that an electrolyte containing a sulfur-containing cyclic compound is used as the electrolyte.

2. Second Embodiment Next, a second embodiment of the air battery of the present invention will be described. The air battery of this embodiment includes an air electrode layer having a conductive material and an air electrode current collector that collects the air electrode layer, a negative electrode layer containing a negative electrode active material, and the negative electrode layer. A negative electrode having a negative electrode current collector for collecting the current, a separator disposed between the air electrode layer and the negative electrode layer, an electrolyte responsible for conduction of metal ions between the air electrode layer and the negative electrode layer, Wherein the electrolyte contains a sulfur-containing cyclic compound, and a decomposition product obtained by decomposing all or part of the sulfur-containing cyclic compound covers the surface of the conductive material. It is characterized by being.

  According to this embodiment, since the decomposition product formed by decomposition of all or part of the sulfur-containing cyclic compound covers the surface of the conductive material, metal ions (for example, lithium ions) can easily move. Thus, an air battery having excellent output characteristics and cycle characteristics can be obtained.

  In this embodiment, the electrolyte contains a sulfur-containing cyclic compound. Since the type of sulfur-containing cyclic compound, the type of electrolyte, the preferred mode of each member constituting the air battery, and other matters are the same as those described in the above “1. First embodiment”, Is omitted.

  In this embodiment, usually, a decomposition product formed by decomposition of all or part of the sulfur-containing cyclic compound covers the surface of the conductive material. As a method for coating the surface of the conductive material with the decomposition product of the sulfur-containing cyclic compound, for example, a method by electrochemical treatment can be mentioned. Specifically, a method of performing a discharge treatment using the air battery of the first embodiment described above to perform reductive decomposition of a sulfur-containing cyclic compound can be exemplified. At this time, it is considered that the sulfur-containing cyclic compound undergoes ring-opening decomposition and covers the surface of the conductive material. Examples of the discharge process include a process of discharging until reaching 0 V to about 0.5 V using lithium as a counter electrode. At this time, the current is preferably 20 mA / (g-carbon) or less. The thickness of the film formed by the decomposition product of the sulfur-containing cyclic compound is not particularly limited as long as it is within a range that can contribute to improvement of output characteristics and cycle characteristics.

  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 1]
In this example, a coin cell type lithium air secondary battery was produced. The coin cell was 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. First, a metal lithium foil 24 was disposed 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. Next, a polyethylene separator 25 was placed on the metal lithium foil 24. As the separator 25, a sheet having a thickness of 25 μm punched to a diameter of 19.5 mm was used. Next, the electrolytic solution 23 was injected from above the separator 25 with a dropper. In the electrolytic solution 23, LiClO ₄ (manufactured by Kishida Chemical) was dissolved at a concentration of 1M in a mixed solvent mixed with ethylene carbonate (manufactured by Kishida Chemical): diethyl carbonate (manufactured by Kishida Chemical) = 1: 1 (volume ratio), Furthermore, what added ethylene sulfite (sulfur containing cyclic compound) so that it might become a density | concentration of 5 wt% was used.

  Next, the air electrode composite material 27 was pressed against the air electrode mesh 26, and the air electrode composite material 27 was inserted into the air electrode mesh 26. As the air electrode mesh 26, a Ni mesh having a thickness of 150 μm and a diameter of 15 mm was used. As the air electrode mixture 27, 82 parts by weight of ketjen black (KB), 3 parts by weight of polytetrafluoroethane (PTFE), and 15 parts by weight of electrolytic manganese dioxide were kneaded in an agate mortar. Next, the integrated air electrode mesh 26 and the air electrode mixture 27 were installed on the air electrode case 20 to which the air electrode current collector 28 was joined by welding. A Ni mesh having a thickness of 150 μm and a diameter of 15 mm was used as the air electrode current collector 28. Next, the gasket 21 was fitted into the air electrode case 20.

  Next, the obtained negative electrode case and air electrode case were joined using a coin cell caulking machine (manufactured by Hosen). In this way, a coin cell was obtained.

[Examples 2 to 10]
A coin cell was obtained in the same manner as in Example 1 except that the composition of the electrolytic solution 23 was changed as shown in Table 1 below.

[Comparative Example 1]
As the electrolytic solution 23, LiClO ₄ (manufactured by Kishida Chemical Co., Ltd.) dissolved at a concentration of 1M in a mixed solvent mixed with ethylene carbonate (manufactured by Kishida Chemical Co., Ltd.): Diethyl carbonate (manufactured by Kishida Chemical Co., Ltd.) = 1: 1 (volume ratio). A coin cell was obtained in the same manner as in Example 1 except that the above was used (that is, the sulfur-containing cyclic compound was not used).

[Comparative Example 2]
As an electrolytic solution 23, LiClO ₄ (manufactured by Kishida Chemical) was dissolved at a concentration of 1M in a mixed solvent mixed with ethylene carbonate (manufactured by Kishida Chemical): diethyl carbonate (manufactured by Kishida Chemical) = 1: 1 (volume ratio), and A coin cell was obtained in the same manner as in Example 1 except that dimethyl sulfoxide (sulfur-containing chain compound) was added so as to have a concentration of 5 wt%.

  A coin cell was obtained in the same manner as in Comparative Example 2, except that dimethyl sulfoxide (sulfur-containing chain compound) was added to a concentration of 30 wt%.

[Evaluation]
Using the coin cells obtained in Examples 1 to 10 and Comparative Examples 1 to 3, a high rate discharge capacity test and a cycle test were performed.

(1) High-rate discharge capacity test First, the obtained coin cell was fitted into a cell case, placed in a glass container, and sealed with an aluminum lid. In addition, the wiring of the positive electrode terminal and the negative electrode terminal was made to be able to be taken out from an aluminum lid. The glass container was taken out from the argon box and first pretreated. As pretreatment, discharging and charging were performed under the following conditions. The following (g-carbon) refers to the weight of carbon in the positive electrode layer.
・ Discharge condition: Discharge until the battery voltage reaches 0.3V at a current of 20 mA / (g-carbon). Charge condition: Charge until the battery voltage reaches 3.5 V at a current of 20 mA / (g-carbon). In addition, since this pretreatment is performed in an argon atmosphere, an oxide formation reaction due to the reaction of the air battery does not occur.

Thereafter, the inside of the glass container was gas-substituted from argon to oxygen using a pipe provided in an aluminum lid. Then, it discharged on the following discharge conditions and measured discharge capacity. The results are shown in Table 2.
-Discharge condition: Discharge at a current of 100 mA / (g-carbon) until the battery voltage reaches 2V.

(2) Cycle test First, the obtained coin cell was fitted in a cell case, put in a glass container, and sealed with an aluminum lid. In addition, the wiring of the positive electrode terminal and the negative electrode terminal was made to be able to be taken out from an aluminum lid. The glass container was taken out from the argon box and first pretreated. The pretreatment conditions are the same as in the case of the high rate discharge capacity test.

Thereafter, the inside of the glass container was gas-substituted from argon to oxygen using a pipe provided in an aluminum lid. Then, charging / discharging was performed on the following discharge conditions and charge conditions, and the discharge capacity of the 10th cycle was measured. The results are shown in Table 2.
-Discharge condition: Discharge until the battery voltage reaches 2V with a current of 50 mA / (g-carbon) or reaches an electric quantity of 1500 mAh / (g-carbon)-Charging condition: 25 mA / (g-carbon) Charging is performed until the battery voltage reaches 4.3 V with current. The cycle test started from discharging.

  As shown in the results of the high rate discharge capacity test, it was confirmed that the coin cells obtained in Examples 1 to 10 showed a very high discharge capacity as compared with the coin cells obtained in Comparative Examples 1 to 3. It was done. This is considered to be because a film made of the decomposition product of the sulfur-containing cyclic compound was formed on the surface of the conductive material, and lithium ions were easily transferred. In particular, when the coin cells obtained in Examples 1 to 10 and the coin cells obtained in Comparative Example 2 and Comparative Example 3 are compared, the sulfur-containing cyclic compound has an improved discharge capacity compared to the sulfur-containing chain compound. It was confirmed that it contributed greatly to From this, it was found that when considered as a primary air battery, the air battery of the present invention exhibits excellent discharge characteristics.

  On the other hand, as a result of the cycle test, compared with the coin cells obtained in Comparative Examples 1 to 3, the coin cells obtained in Examples 1 to 10 all maintain a high capacity with respect to the initial 1500 mAh / (g-carbon). It became clear to show the rate. This phenomenon is also considered to be because a film made of the decomposition product of the sulfur-containing cyclic compound was formed on the surface of the conductive material, and the movement of lithium ions was facilitated, as described above.

  Further, when Example 3 and Comparative Example 1 were compared, it was confirmed that ethylene sulfite (sulfur-containing cyclic compound) contributes to improvement of output characteristics and cycle characteristics even when 1 wt% is added. On the other hand, when Example 6 and Example 7 are compared, for example, even when the addition of sulfolane (a sulfur-containing cyclic compound) is changed from 5 wt% to 30 wt%, the output characteristics and the cycle characteristics are significantly reduced. I couldn't.

It is explanatory drawing explaining the air battery of this invention. It is a schematic sectional drawing which illustrates the air battery of this invention. It is a schematic sectional drawing which illustrates the air battery of this invention. 3 is an explanatory view illustrating an air battery manufactured in Example 1. FIG.

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 (6)

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, and a negative electrode current collector for collecting the negative electrode layer A lithium- air battery comprising: a negative electrode having a body; a separator disposed between the air electrode layer and the negative electrode layer; and an electrolyte that conducts metal ions between the air electrode layer and the negative electrode layer. And
The lithium- air battery, wherein the electrolyte contains a sulfur-containing cyclic compound represented by any one of the following general formulas (1) to (4) .

(In General Formula (1), R ₁ and R ₂ are independent and are functional groups capable of forming a ring with each other. In General Formula (2), R ₃ and R ₄ are independent and form a ring with each other. In the general formula (3), R ₅ and R ₆ are independent and can form a ring with each other. In the general formula (4), R ₇ and R ₈ are independent. And a functional group capable of forming a ring with each other.) 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, and a negative electrode current collector for collecting the negative electrode layer A lithium- air battery comprising: a negative electrode having a body; a separator disposed between the air electrode layer and the negative electrode layer; and an electrolyte that conducts metal ions between the air electrode layer and the negative electrode layer. And
The electrolyte contains a sulfur-containing cyclic compound represented by any one of the following general formulas (1) to (4), and a decomposition product obtained by decomposing all or part of the sulfur-containing cyclic compound is: A lithium- air battery characterized by covering the surface of a conductive material.

(In General Formula (1), R ₁ and R ₂ are independent and are functional groups capable of forming a ring with each other. In General Formula (2), R ₃ and R ₄ are independent and form a ring with each other. In the general formula (3), R ₅ and R ₆ are independent and can form a ring with each other. In the general formula (4), R ₇ and R ₈ are independent. And a functional group capable of forming a ring with each other.) The compound represented by the general formula (1) is ethylene sulfite, propylene sulfite, butylene sulfite, vinylene sulfite, phenylethylene sulfite, or a part of these constituent elements substituted with a halogen element. The lithium air battery according to claim 1 , wherein the lithium air battery is provided. The compound represented by the general formula (2) is 1,3-propane sultone, 1,4-butane sultone, 3-phenyl-1,3-propane sultone, 4-phenyl-1,4-butane sultone, or these The lithium- air battery according to claim 1 or 2 , wherein a part of the constituent elements is substituted with a halogen element. The compound represented by the general formula (3) is sulfolane, 2-methyl sulfolane, 3-methyl sulfolane, 2-ethyl sulfolane, 3-ethyl sulfolane, 2,4-dimethyl sulfolane, 2-phenyl sulfolane, 3-phenyl. The lithium- air battery according to claim 1 or 2 , wherein sulfolane, sulfolene, 3-methylsulfolene, or a part of these constituent elements is substituted with a halogen element. The compound represented by the general formula (4) has ethylene glycol sulfate, 1,2-propanediol sulfate, 1,3-propanediol sulfate, or a part of these constituent elements substituted with a halogen element. The lithium air battery according to claim 1 or 2 , wherein the battery is a lithium- air battery.

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