JP2016009525A - Negative electrode composite material of lithium air battery, lithium air battery and lithium air battery module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a negative composite material of a lithium air battery, a lithium air battery and a lithium air battery system that can suppress extreme increase in size and implement light weight and compact size even when energy density and input/output density are increased as compared with conventional air batteries.SOLUTION: A negative electrode composite material 10 of a lithium air battery has a plate-like or linear negative electrode collector 2, two plate-like negative layers 1 which contain metal lithium, lithium alloy or a lithium component and pinches a part of the negative electrode collector, and an isolation layer 3 which is configured in a hollow box-like shape opened at one surface thereof, contains the two negative layers therein and has lithium ion conductivity.

Description

  The present invention relates to a negative electrode composite of a lithium air battery, a lithium air battery, and a lithium air battery module.

  Due to the widespread use of electric vehicles, there are expectations for air batteries having a much higher energy density than lithium ion batteries. The air battery uses oxygen in the air as a positive electrode active material.

  By the way, a lithium air battery using metal lithium, a lithium alloy, or a lithium compound as a negative electrode active material is known. Focusing on the type of electrolyte, lithium-air batteries are broadly divided into two types: aqueous electrolytes and nonaqueous electrolytes. Non-aqueous electrolyte lithium-air batteries have become the mainstream of research and development because they can utilize the technology of lithium-ion batteries other than the air electrode.

  On the other hand, research and development of an aqueous electrolyte-based lithium-air battery is also in progress, although the number is still small. Compared to lithium water batteries of non-aqueous electrolytes, lithium air batteries of aqueous electrolytes have advantages such as being not affected by moisture in the air and being inexpensive and non-combustible. However, metallic lithium, which is a negative electrode active material, reacts when directly in contact with oxygen or water. Therefore, in an aqueous electrolyte-type lithium-air battery, it is necessary to provide a protective layer such as a lithium ion conductive solid electrolyte in order to protect metallic lithium from the atmosphere or an aqueous solution.

  Therefore, a buffer layer of a polymer electrolyte is formed on one surface of the plate-shaped metallic lithium, and the one surface of the buffer layer of the polymer electrolyte is water resistant having lithium ion conductivity (also expressed as lithium ion conductivity or lithium ion conductivity). A lithium-air battery including a negative electrode composite covered with glass ceramics as a layer is known (see, for example, Patent Document 1 and Non-Patent Document 1).

JP 2010-192313 A

Yasuo Takeda, Masayuki Imanishi, Osamu Yamamoto, “Current Status and Problems of Aqueous Lithium / Air Battery”, GS Yuasa Technical Report, June 2010, Vol. 7, No. 1, p. 1-6

  In the conventional air battery described in Patent Document 1 and Non-Patent Document 1, one surface of one air electrode is directly opposed to one surface of one negative electrode composite and is enclosed in a container or a laminate film. In the case of increasing the input / output density (output per weight), these conventional air batteries simply use a large number of air batteries having the same structure or simply increase the size of the air battery having the same structure. However, the mode in which a large number of air batteries having the same structure are simply used, or the mode in which the air battery having the same structure is simply enlarged is mounted on an electric vehicle in order to increase the required air battery mounting space inefficiently and greatly. In reality, it is difficult to adopt.

  The conventional air battery described in Non-Patent Document 1 encloses the negative electrode composite in a gas barrier laminate film having a three-layer structure of polypropylene (PP), aluminum foil, and polyethylene terephthalate (PET). The negative electrode composite of Non-Patent Document 1 closes the opening made in the laminate film with glass ceramics as a window material having lithium ion conductivity in order to ensure lithium ion conductivity inside and outside the laminate film.

  However, it is difficult to bond a combination of polypropylene (PP) as a laminate film and glass ceramics as a negative electrode composite with an adhesive, and lack durability. In addition, in order to form a negative electrode composite by thermally welding the laminate film, a welding margin of about 10 mm is required on the outer peripheral edge of the laminate film. As a result, the area of the laminate film is increased and the volume of the air battery is increased. To increase.

  In other words, the conventional air battery discloses a small single cell for experimentation, and it is difficult to construct a compact practical cell with increased battery characteristics, particularly energy density.

  Therefore, the present invention provides a lithium-air battery negative electrode composite, lithium air, which can suppress an excessive increase in size even when the energy density and input / output density are increased as compared with a conventional air battery, and realizes a reduction in weight and size. An object is to provide a negative electrode composite of a battery and a lithium-air battery.

  In order to achieve the above object, the present invention provides a negative electrode composite for a lithium-air battery, which includes a plate-like or linear negative electrode current collector and metallic lithium, a lithium alloy, or a lithium compound, and the negative electrode current collector A lithium-air battery comprising two plate-shaped negative electrode layers sandwiching a portion of the electrode and a hollow box shape having one open surface, and a lithium ion conductive isolation layer accommodating the two negative electrode layers therein A negative electrode composite is provided.

  In one embodiment of the negative electrode composite for a lithium-air battery according to the present invention, the opening is preferably sealed with a gasket and / or an adhesive.

  In one aspect of the negative electrode composite of the lithium-air battery according to the present invention, it is preferable that a buffer layer is further provided between the negative electrode layer and the isolation layer.

  In another aspect, the present invention provides a lithium-air battery, the negative electrode composite, an air electrode layer containing a conductive material and having a surface facing at least one surface of the isolation layer, and the air electrode layer Provided is a lithium-air battery comprising an air electrode provided with a plate-like or linear air electrode current collector electrically connected.

  In one aspect of the lithium-air battery according to the present invention, the air electrode layer has a hollow box shape with one side opened, the negative electrode composite is accommodated therein, and each of the inner surfaces of the air electrode layer is It is preferable to face one of the outer surfaces of the isolation layer.

  In one aspect of the lithium-air battery according to the present invention, it is preferable that the air electrode layer is formed as an integral part.

  In another aspect, the present invention provides a lithium-air battery module comprising a plurality of the lithium-air batteries connected in parallel.

  In one aspect, the lithium-air battery module according to the present invention preferably further includes a case that houses the plurality of lithium-air batteries, and an electrolyte that is stored in the case and contacts at least the air electrode. .

  According to the present invention, an anode composite of a lithium-air battery, which can suppress an excessive increase in size even when the energy density and input / output density are increased as compared with a conventional air battery, and realizes a reduction in weight and size, lithium air A negative electrode composite of a battery and a lithium air battery can be provided.

It is a typical perspective view which shows one Embodiment of the negative electrode composite of the lithium air battery which concerns on this invention. It is a typical perspective view which shows other embodiment of the negative electrode composite_body | complex of the lithium air battery which concerns on this invention. It is typical sectional drawing which shows other embodiment of the negative electrode composite_body | complex of the lithium air battery which concerns on this invention. It is a typical perspective view which shows one Embodiment of the lithium air battery which concerns on this invention. It is typical sectional drawing which shows other embodiment of the lithium air battery which concerns on this invention. It is a typical perspective view which shows one Embodiment of the lithium air battery module which concerns on this invention. It is a typical perspective view which shows other embodiment of the lithium air battery module which concerns on this invention. 2 is a schematic cross-sectional view showing a negative electrode composite of a cell of Example 1. FIG. 3 is a schematic cross-sectional view showing a negative electrode composite of a cell of Comparative Example 1. FIG.

  Hereinafter, the negative electrode composite, the lithium air battery, and the lithium air battery module of the lithium air battery of the lithium air battery according to the present invention will be described in more detail. The present invention is not limited to the following embodiments.

  FIG. 1 shows an embodiment of a negative electrode composite for a lithium-air battery according to the present invention. A negative electrode composite 10 of a lithium-air battery shown in FIG. 1 includes two negative electrode layers 1, a negative electrode current collector 2, and an isolation layer 3 as main components.

  The two negative electrode layers 1 have a rectangular flat plate shape and sandwich a part of the negative electrode current collector 2. The two negative electrode layers 1 have substantially the same size and shape. The thickness and size of the negative electrode layer 1 can be appropriately adjusted according to the desired battery capacity.

The negative electrode layer 1 contains metallic lithium, a lithium alloy, or a lithium compound, and can be the same as the negative electrode used in a general lithium ion battery. The negative electrode layer 1 preferably contains metallic lithium from the viewpoint of increasing the capacity. The lithium alloy is preferably at least one metal element selected from the group consisting of magnesium, calcium, aluminum, silicon, germanium, tin, lead, arsenic, antimony, bismuth, silver, gold, zinc, cadmium, It is an alloy with lithium. The lithium compound is not particularly limited as long as it can desorb and insert lithium ions. Examples of the lithium compound include Li _3-x M _x N (wherein M represents Co, Cu, Ni, or the like), lithium oxide, and lithium sulfide.

  The material of the negative electrode current collector 2 may be any material as long as it can exist stably in the operating range of the lithium-air battery and has a desired conductivity. For example, copper, nickel, or alloys thereof can be used. The negative electrode current collector 2 has a plate shape or a linear shape. The negative electrode current collector 2 has a portion that is sandwiched between two negative electrode layers 1 and a portion that is led out from the negative electrode layer 1 and exposed to the outside of the isolation layer 3. This exposed portion can be electrically connected to the outside and functions as a negative electrode terminal.

  The isolation layer 3 is made of a solid electrolyte and constitutes most of the outer shell of the negative electrode composite 10. The isolation layer 3 has a hollow rectangular parallelepiped shape with one side opened. The front side surface 3 b and the rear side surface 3 c facing the isolation layer 3 are slightly larger than the negative electrode layer 1. Inside the isolation layer 3, two negative electrode layers 1 are accommodated, and the negative electrode current collector 2 is led out from the opening surface 3 a of the isolation layer 3. Although the illustration is omitted, the opening of the isolation layer 3 is appropriately closed by a cover material such as rubber, elastomer, and adhesive.

  In this embodiment, the isolation layer 3 has a hollow rectangular parallelepiped shape. However, as long as the object of the present invention is substantially achieved, the isolation layer 3 may have a hollow box shape. The hollow box shape includes an arbitrary shape such as a polyhedron such as a parallel polyhedron, a pyramid, a cylinder (including an elliptical column), a truncated cone, and the like in addition to a cube and a rectangular parallelepiped shape. The isolation layer 3 may partially have a curved surface at a corner or the like. As long as various conditions permit, the isolation layer 3 may be provided with uneven portions, protrusions, holes, or slits. “One side is open” means that the two negative electrode layers 1 are accommodated through the openings and then the openings can be closed, and the opening is not blocked. The opening can have a size that allows the two negative electrode layers 1 to pass therethrough.

  The isolation layer 3 serves as a separator that partitions the positive electrode layer containing the electrolyte from the negative electrode layer 1 and protects the negative electrode layer 1 from moisture. In the embodiment shown in FIG. 1, the isolation layer 3 is disposed such that the inner surface thereof does not contact the negative electrode layer 1, but may be in contact. In the present embodiment, the isolation layer 3 and the negative electrode layer 1 are disposed so as to be directly adjacent to each other, but the isolation layer 3 and the negative electrode layer 1 may be disposed with a buffer layer described later therebetween. Good.

  The five side surfaces other than the opening surface 3a of the isolation layer 3 can function as electrodes. Each of the five side surfaces except the opening surface 3a of the isolation layer 3 can face the air electrode layer, but at least one of the five side surfaces, for example, one surface, two surfaces, three surfaces, or four surfaces is present. If it faces the air electrode layer, a lithium-air battery can be constructed.

The isolation layer 3 is preferably made of glass ceramics having water resistance and lithium ion conductivity. The isolation layer 3 preferably has a lithium ion conductivity of 10 ⁻⁵ S / cm or more. Examples of the isolation layer 3 include a NASICON (Na Super Ionic Conductor) type lithium ion conductor. Further, as the isolation layer 3, a tetravalent cation M of a lithium ion conductor represented by the general formula LiM ₂ (PO ₄ ) ₃ (wherein M represents a tetravalent cation such as Zr, Ti, Ge). Lithium ion conduction represented by the general formula Li _{1 + x} M _2−x M ′ _x (PO ₄ ) _{3 in} which lithium ion conductivity is improved by substituting a part of the trivalent cation M ′ such as In and Al. The body is mentioned. Further, as the isolation layer 3, a tetravalent cation M of a lithium ion conductor represented by the general formula LiM ₂ (PO ₄ ) ₃ (wherein M represents a tetravalent cation such as Zr, Ti, Ge, etc.). some lithium ion conductivity represented by "formula _{Li 1-x M 2-x} M with improved lithium ion conductivity by replacing" x _{(PO 4) 3} 5 monovalent cation M of Ta or the like The body is mentioned. P in these lithium ion conductors may be substituted by Si, and the lithium ion conductor represented by the general formula Li _{1 + x + y} Ti _2−x Al _x P _3−y Si _y O ₁₂ (LTAP) is an ion. Desirable from the viewpoint of conductivity.

The inside of the isolation layer 3 is filled with an organic electrolyte. The organic electrolyte exists between the negative electrode layer 1 and the isolation layer 3 and is responsible for the conduction of lithium ions between the negative electrode layer 1 and the isolation layer 3. From the viewpoint of lithium ion conduction, it is desirable that the organic electrolyte is filled in the isolation layer 3, but from the viewpoint of weight reduction, the negative electrode layer 1 and the isolation layer 3 are interposed via the buffer layer 4 impregnated with the organic electrolyte. As long as it has lithium ion conductivity. The organic electrolyte is, for example, a mixed solvent such as propylene carbonate (PC), ethylene carbonate (EC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), LiPF ₆ (lithium hexafluorophosphate), LiClO ₄ (peroxide). Lithium salt such as lithium chlorate) or LiBF ₄ (lithium tetrafluorophosphate) is added.

  The negative electrode composite 10 according to the present embodiment has a rectangular parallelepiped shape, and five of the six surfaces can be used as electrodes, and can contribute to power generation. By making the side surface electrode that has not conventionally contributed as a live part, the effective area for battery reaction per unit volume can be increased and the input / output density can be improved as compared with a conventional lithium-air battery.

  The negative electrode composite 10 according to the present embodiment has a structure in which the isolation layer 3 has a hollow rectangular parallelepiped shape and the organic electrolyte does not leak. Therefore, in order to prevent the organic electrolyte of the negative electrode composite from leaking, it is only necessary to seal the opening surface, and it is not necessary to seal all side surfaces with a gasket or the like. Furthermore, it is not necessary to tilt the isolation layer 3 when assembling the negative electrode composite 10. Therefore, the negative electrode composite 10 can be easily manufactured without leaking the organic electrolyte. Thus, since there is no possibility that the organic electrolyte leaks from the inside of the negative electrode composite, the injection amount of the organic electrolyte can be set to a target value, and a discharge voltage according to the target value can be achieved. Since there is no variation in the amount of organic electrolyte for each negative electrode composite 10 produced, it is possible to always obtain the negative electrode composite 10 having the same characteristics. Furthermore, it is possible to easily inject the organic electrolyte into the isolation layer 3 using a microsyringe or the like. Therefore, in the negative electrode composite 10 according to the present embodiment, it is possible to add the organic electrolyte to the inside later by removing a cover material such as an adhesive.

  On the other hand, in the case where the negative electrode composite has a structure in which the negative electrode layer is sandwiched between two flat plate-shaped isolation layers, a window frame-shaped gasket arranged on the periphery of each flat plate-shaped isolation layer is inserted between the negative electrode layers. Assemble by overlapping gaskets. In such a negative electrode composite, the organic electrolyte is previously injected into the space surrounded by the frame-shaped gasket on the isolation layer before the gaskets are overlapped to seal the space in the isolation layer. However, when the gaskets are overlapped with each other, it is necessary to incline at least one flat plate-shaped isolation layer, so that the organic electrolyte leaks from the inside of the gasket frame, and the amount of the organic electrolyte becomes less than the target value. As a result, the ionic conductivity between the negative electrode layer and the isolation layer is lowered and the internal resistance is increased. As a result, there is a problem that the discharge voltage becomes smaller than a target value. Furthermore, as a result of variations in the amount of the organic electrolyte in each negative electrode composite produced, it becomes difficult to produce a negative electrode composite having the same characteristics. Further, in such a negative electrode composite, once the gasket that has been brought into close contact is disassembled, the organic electrolyte inside the negative electrode composite leaks out, so that it is not possible to add an organic electrolyte later into the negative electrode composite.

  In FIG. 2, other embodiment of the negative electrode composite of the lithium air battery which concerns on this invention is shown. In FIG. 3, the typical cross section of 10 A of negative electrode composites of the lithium air battery which concerns on this embodiment is shown.

  A negative electrode composite body 10A of a lithium-air battery according to the embodiment shown in FIGS. 2 and 3 includes, as main components, two negative electrode layers 1, a negative electrode current collector 2, an isolation layer 3, a buffer layer 4, a gasket 5, and An adhesive 6 is provided. The negative electrode composite body 10 </ b> A of the lithium-air battery according to this embodiment is characterized in that the inside is sealed with a gasket 5 and an adhesive 6. In addition, the component to which the same code | symbol was attached | subjected has the same structure as embodiment described about FIG. 1, and the overlapping description is abbreviate | omitted.

The buffer layer 4 is disposed between the negative electrode layer 1 and the isolation layer 3. The buffer layer 4 separates the negative electrode layer 1 and the isolation layer 3, protects the isolation layer 3 from contact with the negative electrode layer 1, and enhances the ion conductivity of the negative electrode layer 1 and the isolation layer 3. The buffer layer 4 is preferably wrapped so as to cover the entire two negative electrode layers 1. The buffer layer 4 includes a lithium ion conductive polymer electrolyte, a lithium ion conductive solid electrolyte, or an organic electrolyte. The buffer layer 4 preferably has a lithium ion conductivity (also expressed as lithium ion conductivity, conductivity) of 10 ⁻⁵ S / cm or more.

The buffer layer 4 may be a solid electrolyte in which a lithium salt is dispersed in a polymer, or may be a gel electrolyte in which an organic electrolyte in which a lithium salt is dissolved is swollen in a polymer. Examples of the polymer serving as a host for the solid electrolyte include PEO (polyethylene oxide) and PPO (polypropylene oxide). Examples of the polymer serving as a host for the gel electrolyte include PEO (polyethylene oxide), PVDF (polyvinylidene fluoride), PVDF-HFP (copolymer of poly (vinylidene fluoride) and hexafluoropropylene). Examples of the lithium salt include LiPF ₆ , LiClO ₄ , LiBF ₄ , LiTFSI (Li (CF ₃ SO ₂ ) ₂ N), Li (C ₂ F ₄ SO ₂ ) ₂ N, LiBOB (lithium bisoxalatoborate), and the like.

In addition, when using especially desirable PEO as a polymer of a solid electrolyte, the molecular weight of PEO is desirably 10 ⁴ to 10 ⁵ , and the molar ratio of PEO and lithium salt is 8 to 30: 1. It is desirable to be.

In order to improve the strength and electrochemical characteristics of the buffer layer 4, a ceramic filler, for example, BaTiO ₃ powder may be dispersed in the polymer. The mixing amount of the ceramic filler is desirably 1 to 20 parts by weight with respect to 100 parts by weight of the remaining components.

Further, the buffer layer 4 may be one in which an organic electrolyte is soaked in a separator. The whole of the two negative electrode layers 1 may be wrapped with one separator, or the two negative electrode layers 1 may be wrapped with two or more separators. The material of the separator is a porous material that easily penetrates the organic electrolyte. For example, paper (cellulose), chemical fiber nonwoven fabric, and porous polymers such as polyethylene (PE), polypropylene (PP), and polyimide (PI). A membrane is mentioned. The organic electrolyte soaked into the separator is, for example, a mixed solvent such as propylene carbonate (PC), ethylene carbonate (EC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), LiPF ₆ (lithium hexafluorophosphate), A lithium salt such as LiClO ₄ (lithium perchlorate) or LiBF ₄ (lithium tetrafluorophosphate) is added.

  When the isolation layer 3 is made of glass ceramics, the negative electrode layer 1 and the isolation layer 3 may be in direct contact with each other, so that the glass ceramics of the isolation layer 3 may react with lithium in the negative electrode layer 1 and deteriorate. For example, when the material of the isolation layer 3 is LTAP, the LTAP may be deteriorated by reaction with lithium. However, such a reaction is suppressed by inserting the buffer layer 4 to prevent contact between the negative electrode layer 1 and the isolation layer 3. This contributes to extending the life of the lithium-air battery.

  The gasket 5 is fixed between the side surfaces at the opening edge of the isolation layer 3 so as to block the opening surface 3 a of the isolation layer 3. The gasket 5 has a rectangular shape that can be attached to the opening surface 3a. The thickness of the gasket 5 is not particularly limited as long as it can be fixed between the side surfaces of the opening edge of the isolation layer 3, and can be appropriately set by those skilled in the art. The gasket 5 may be fixed to the inner surface of each of the side surfaces of the isolation layer 3 by any method, but is preferably fixed by the adsorptivity and / or adhesiveness of the gasket 5 itself. The gasket 5 may be in contact with the negative electrode layer 1 or may not be in contact therewith. The gasket 5 includes two gaskets, and the negative electrode current collector 2 is led out of the negative electrode composite 10 through the overlapping surface. Alternatively, the gasket 5 may be configured as one member. In such a case, a through hole for the negative electrode current collector 2 is provided in the gasket 5. A part of the gasket 5 may protrude outward from the opening end of the isolation layer 3.

  Since the space in the negative electrode complex is sealed by the gasket 5, it is possible to prevent moisture and solution from entering the negative electrode complex 10A and leakage of the organic electrolyte from the negative electrode complex. The organic electrolyte causes deterioration of the adhesive, resin, and the like, but the deterioration of the adhesive 6 can be suppressed by preventing leakage of the organic electrolyte by the gasket 5.

  The material of the gasket 5 is rubber or elastomer, preferably rubber or elastomer that is resistant to organic electrolyte. If rubber or elastomer that is resistant to the organic electrolyte is used, the gasket 5 is less likely to be deteriorated by the organic electrolyte inside the negative electrode composite, and the hermeticity inside the negative electrode composite 10A can be maintained for a longer period of time. The rubber or elastomer is preferably a rubber or elastomer made of ethylene-propylene-diene copolymer, or a fluorine-based rubber or elastomer. Examples of the rubber made of ethylene-propylene-diene copolymer include EPM, EPDM, and EPT. Examples of the fluorine-based rubber or elastomer include vinylidene fluoride (FKM), tetrafluoroethylene-propylene (FEPM), tetrafluoroethylene-purple fluorovinyl ether (FFKM), and the like. The physical property of the rubber or elastomer is preferably a soft hardness. The hardness of the gasket material is preferably around Shore A 50-70. If the gasket material is extremely soft, there may be problems such as poor processability. Further, the rubber or elastomer is preferably a type in which the raw material before molding is liquid and has high adsorptivity and / or adhesiveness.

  The adhesive 6 is fixed to the opening edge of the isolation layer 3 so as to block the opening surface 3 a of the isolation layer 3, and the space in the isolation layer is exposed while the remaining part of the negative electrode current collector 2 is exposed to the outside of the isolation layer 3. To seal. The adhesive 6 is fixed so as to cover the entire opening surface 3 a of the isolation layer 3. The adhesive 6 preferably contacts the gasket 5 and fixes the gasket 5 from the outside. The adhesive 6 has a penetrating portion through which the negative electrode current collector 4 penetrates. The adhesive 6 can further improve the sealing performance of the negative electrode composite 10 </ b> A. As the adhesive 6, those having low moisture permeability and high sealing properties are suitable. For example, epoxy adhesives, acrylic adhesives, silicone adhesives, olefin adhesives, synthetic rubber adhesives, and the like Is mentioned. More preferably, the adhesive further has resistance to an aqueous electrolyte (preferably an organic electrolyte), such as an epoxy adhesive or an olefin adhesive. The adhesive 6 preferably has a curing condition that cures at room temperature in a short time. In addition, the adhesive 6 may contain an alcoholic solvent or the like that degrades metallic lithium as a trace component. However, since the space in the isolation layer is hermetically sealed by the gasket 5, Intrusion into the negative electrode composite body 10A can be prevented. For this reason, the freedom degree of the kind of adhesive agent which can be used can be improved.

  The internal space of the negative electrode composite body 10 </ b> A of the lithium-air battery according to this embodiment is sealed by the gasket 5 and the adhesive 6. Therefore, the organic electrolyte is confined inside the negative electrode composite and does not leak to the outside. Therefore, there is no fear that the organic electrolyte touches the electrolyte present outside the negative electrode composite 10A and the concentration and pH of the electrolyte change, and desired discharge characteristics can be achieved.

  Furthermore, in the negative electrode composite body 10 </ b> A of the lithium-air battery according to the present embodiment, the gasket 5 and the adhesive 6 are fixed to an opening located on the upper surface of the rectangular parallelepiped isolation layer 3. Therefore, in a normal use state of the lithium-air battery, the electrolyte responsible for lithium ion conduction between the air electrode and the negative electrode composite 10A outside the negative electrode composite 10A is the gasket 5 and the adhesive 6 of the negative electrode composite 10A. Does not adhere to. Further, since the gasket 5 and the adhesive 6 are fixed to the opening located on the upper surface, the gasket 5 and the adhesive 6 do not come into contact with the organic electrolyte present in the negative electrode composite 10A. Therefore, 10 A of negative electrode composites of the lithium air battery which concern on this embodiment have the advantage that the gasket 5 and the adhesive agent 6 do not deteriorate by contact with electrolyte. For this reason, the internal organic electrolyte does not leak due to damage due to deterioration of the gasket 5 and the adhesive 6, and the sealing performance of the negative electrode composite 10 </ b> A is improved. Moreover, in the range of normal use, the gasket 5 and the adhesive 6 do not contact the electrolyte and the organic electrolyte, and therefore, the compatibility of the gasket 5 and the adhesive 6 with the electrolyte and the organic electrolyte need not be considered. Therefore, there exists an advantage that the freedom degree of design of 10 A of negative electrode composites improves.

  FIG. 4 shows an embodiment of a lithium air battery according to the present invention. In FIG. 5, the typical cross section of the lithium air battery which concerns on this embodiment is shown.

  The lithium-air battery 100 according to the embodiment shown in FIGS. 4 and 5 includes a negative electrode composite 10A and an air electrode 13 as main components. The air electrode 13 includes an air electrode layer 11 and an air electrode current collector 12. In addition, the component to which the same code | symbol was attached | subjected has the same structure as embodiment described about FIGS. 1-3, and the overlapping description is abbreviate | omitted.

  The air electrode layer 11 has a hollow rectangular parallelepiped shape with one surface opened, and accommodates the negative electrode composite 10 </ b> A therein. Each of the five inner surfaces excluding the opening surface of the air electrode layer 11 faces one of the five surfaces excluding the opening surface of the isolation layer 3 constituting the negative electrode composite 10A. The outer surface of the isolation layer 3 of the negative electrode composite 10A and the inner surface of the air electrode layer 11 are actually in contact with each other, but are separated from each other in FIGS. 4 and 5 for easy identification. . The air electrode layer 11 is formed as an integral part. The air electrode layer 11 has a shape that matches the shape of the negative electrode composite body 10A, that is, the shape of the isolation layer 3, and is slightly larger than the isolation layer 3 so that the isolation layer 3 can be fitted therein. Although not shown, the opening of the air electrode layer 11 is appropriately closed with a cover material such as rubber, elastomer, and adhesive.

  In the present embodiment, the air electrode layer 11 has a hollow rectangular parallelepiped shape, but in addition to a cube or a rectangular parallelepiped shape, a polyhedron such as a parallel polyhedron, a pyramid, or a cylinder (including an elliptical column) is used in accordance with the shape of the isolation layer 3. The hollow box shape can be any shape such as a truncated cone. The air electrode layer 11 may partially have curved surfaces at corners or the like. The air electrode layer 11 may be provided with uneven portions, protrusions, holes, or slits as long as various conditions permit. “One side is open” means that after the negative electrode composite 10A is accommodated through the opening, the opening can be closed, and the opening is not blocked. The opening can have a size that allows the negative electrode composite 10A to pass therethrough.

  The air electrode layer 11 contains a conductive material. The air electrode layer 11 is made of a material having conductivity and gas diffusibility, preferably a conductor such as carbon fiber. Specifically, the air electrode layer 11 has a porous structure, for example, a mesh structure in which constituent fibers are regularly arranged, a nonwoven fabric structure in which random arrangement is made, and a three-dimensional network structure. Specifically, carbon materials such as carbon cloth, carbon non-woven fabric, and carbon paper. Further, as another material having a porous structure, for example, a porous metal material such as stainless steel, nickel, aluminum, or iron may be used. A preferable air electrode material is a material that is conductive, excellent in weight reduction, and highly resistant to corrosion with respect to an electrolyte, and particularly preferably a carbon material. The air electrode layer 11 sucks up the electrolyte 15 by a capillary phenomenon and interposes the electrolyte between the negative electrode composite 10 </ b> A and the air electrode 13.

The air electrode layer 11 may include a catalyst such as a noble metal or a metal oxide. The catalyst may be a catalyst that promotes an oxygen reduction reaction during discharging and an oxygen oxidation reaction during charging. For _{example, MnO 2, CeO 2, Co} 3 O 4, NiO, V 2 O 5, Fe 2 O 3, ZnO, CuO, La 1.6 Sr 0.4 NiO 4, La 2 NiO 4, La 0.6 Sr Metal oxidation such as _0.4 FeO ₃ , La _0.6 Sr _0.4 Co _0.2 Fe _0.8 O ₃ , La _0.8 Sr _0.2 MnO ₃ , Mn _1.5 Co _1.5 O ₄ A noble metal such as Au, Pt, and Ag; and a composite thereof. The method of producing the air electrode layer 11 containing the catalyst is not particularly limited. For example, a carbon cloth carrying a catalyst metal such as platinum mixed with a binder (binder) and an organic solvent (slurry) is used. It can be carried out by adhering to. As the organic solvent, for example, N-methyl-2-pyrrolidone (NMP), acetonitrile, dimethylformamide (DMF), dimethylacetamide (DMA), and dimethyl sulfoxide (DMSO), acetone, ethanol, 1-propanol and the like are used. be able to. Examples of the binder include polyvinylidene fluoride (PVdF), polytetrafluoroethylene (PTFE), styrene-butadiene rubber (SBR), and the like. Specific examples of the method for attaching the catalyst to the air electrode layer 11 include a method in which the slurry is applied and adhered by a doctor blade method or a spray method.

  The air electrode current collector 12 has a plate shape or a linear shape, and is electrically connected to the air electrode layer 11. The air electrode current collector 12 has a portion exposed to the outside of the air electrode layer 11, and this exposed portion can be electrically connected to the outside and functions as a positive electrode terminal. The material of the air electrode current collector 12 may be any material as long as it can exist stably in the operating range of the lithium air battery 100 and has a desired conductivity. Examples of the material of the air electrode current collector 12 include metal materials such as stainless steel, nickel, aluminum, gold, and platinum, and carbon materials such as carbon cloth and carbon nonwoven fabric. The air electrode current collector 12 may be formed of the same material as the air electrode layer 11.

  Although not shown in FIGS. 4 and 5, when the lithium air battery 100 is used, the electrolyte is appropriately supplied by immersing a part of the lithium air battery 100 in the electrolyte stored in the container. Is done.

In the lithium-air battery 100 according to the present embodiment, each of the five inner surfaces of the hollow rectangular parallelepiped air electrode layer 11 faces one of the side surfaces or the bottom surface of the isolation layer 3, and the battery per unit volume of the negative electrode The effective area for reaction has increased significantly. Therefore, the energy density of the lithium air battery 100 according to the present embodiment is improved as compared with the conventional lithium air battery.

  Furthermore, in the lithium-air battery 100 according to the present embodiment, the air electrode layer 11 is formed as an integral part of a hollow rectangular parallelepiped shape in accordance with the shape of the negative electrode composite 10, so that the negative electrode composite 10 and the air electrode layer 11 can be simplified. Moreover, it is not necessary to prepare the number of side surfaces and the bottom surface of the negative electrode composite 10, that is, five air electrode layers, and the number of parts as the air electrode layers can be reduced.

  Further, the conventional lithium-air battery is enclosed in a container or a laminate film with one surface of one air electrode facing one surface of one negative electrode composite. On the other hand, the lithium-air battery 100 according to the present embodiment eliminates the need for a laminate film in a conventional lithium-air battery, reduces the number of parts, and eliminates difficult adhesion in joining the laminate film polypropylene and glass ceramics.

  FIG. 6 shows an embodiment of a lithium air battery module according to the present invention. The lithium air battery module 200 according to the embodiment shown in FIG. 6 includes a plurality of lithium air batteries 100 connected in parallel. In addition, the component to which the same code | symbol was attached | subjected has the same structure as embodiment demonstrated about FIGS. 1-5, and the overlapping description is abbreviate | omitted.

  In the lithium air battery module 200 according to the present embodiment, a plurality of lithium air batteries 100 are connected in parallel. The lithium air batteries 100 are arranged in contact with each other. Or you may arrange | position the lithium air battery 100 through the vent hole which air permeate | transmits between and it is easy to improve reactivity, without making it contact directly. The plurality of lithium-air batteries 100 are formed of a fluororesin molded product made of polyethylene, polypropylene, or a fluoropolymer having vinylidene fluoride units and tetrafluoroethylene units, or a fluoropolymer having vinylidene fluoride units and tetrafluoroethylene units. They may be fixed to each other by a tube made of a material such as fluororesin and having a hole for air permeation. The number of lithium-air batteries 100 connected in parallel can be set in accordance with the required current. Although not shown in the figure, in each lithium air battery 100, the opening of the air electrode layer 11 is appropriately closed with a cover material such as rubber, elastomer, and adhesive.

  Although not shown in FIG. 6, when the lithium air battery module 200 is used, the electrolyte is appropriately supplied by immersing a part of the lithium air battery module 200 in the electrolyte stored in the container. The

  In the lithium-air battery module 200 according to the present embodiment, the air electrode layer 11 itself also serves as the exterior of the lithium-air battery cell, so there is no need to provide a partition for each lithium-air battery cell inside the module. For this reason, the lithium air battery module 200 can realize weight reduction and cost reduction. On the other hand, in the conventional air battery module, a partition corresponding to the exterior of the lithium air battery is provided in the module, and the air battery cell is formed in the partitioned space. Therefore, partition parts such as a partition plate are separately required, which is disadvantageous in terms of weight and cost.

  Therefore, according to the lithium air battery module 200 according to the present embodiment, even if the energy density and the input / output density are increased as compared with the conventional air battery, an extreme increase in size is suppressed, and a reduction in weight and size is realized. be able to.

  FIG. 7 shows another example of the lithium air battery module according to the present embodiment. A lithium air battery module 200A according to the embodiment shown in FIG. 7 includes a plurality of lithium air batteries 100 connected in parallel, a case 101, and an electrolyte 15 as main components. In addition, the component to which the same code | symbol was attached | subjected has the same structure as embodiment demonstrated about FIGS. 1-6, and the overlapping description is abbreviate | omitted.

  The case 101 is a hexahedron, for example, a hollow body having a rectangular parallelepiped shape. The material of the case 101 is a gas-permeable but liquid-impermeable material, such as a molded product of polyethylene, polypropylene, or a fluororesin made of a fluoropolymer having vinylidene fluoride units and tetrafluoroethylene units, or vinylidene fluoride. A porous body of a fluororesin composed of a fluoropolymer having a ride unit and a tetrafluoroethylene unit is preferred. Alternatively, the case 101 may be a molded article made of a material that is impermeable to both gas and liquid. In this case, a vent is provided on the side wall of the case 101. The vent is provided at a position where the electrolyte 15 described later does not leak, and allows air to flow inside and outside the case.

  A plurality of lithium-air batteries 100 connected in parallel with the electrolyte 15 are accommodated in the case 101. Only the negative electrode current collector 2 and the air electrode current collector 12 are drawn out and exposed outside the case 101. Although not shown, it is preferable that a lid is attached to the upper surface of the case 101 to prevent volatilization and contamination of the electrolyte 15.

  The electrolyte 15 is stored in the case 101 and is in contact with the air electrode layer 11 of the lithium air battery 100. The electrolyte 15 is sucked up into the air electrode layer 11 by capillary action, and is interposed between the air electrode layer 11 and the negative electrode composite 10, and is responsible for conduction of lithium ions between the air electrode layer 11 and the isolation layer 3.

The electrolyte 15 is a water based electrolyte. As the aqueous electrolyte, a solution containing lithium salt in water can be usually used. Examples of the lithium salt include lithium salts such as LiCl, LiOH, LiNO ₃ , and CH ₃ CO ₂ Li. The electrolyte 15 only needs to be in contact with at least the bottom surface of the air electrode layer 11, and is preferably stored in the case 101 in an amount that immerses 1/5 to 3/5 of the side surface of the air electrode layer 11.

  Alternatively, the electrolyte 15 may be a polymer electrolyte. In this case, the electrolyte 15 may be a thin film-like body sandwiched between the air electrode layer 11 and the isolation layer 3, or may be a film-like body that coats the surface of the air electrode layer 11.

  In the lithium-air battery module 200A according to the present embodiment, a plurality of lithium-air batteries 100 are connected in parallel and accommodated in one case 101. With this structure, the electrolyte 15 can be shared by all the lithium air batteries 100 in the case. Therefore, there is no need to prepare an electrolyte for each lithium-air battery 100, and the amount of stored electrolyte can be reduced. As a result, the weight and volume of the lithium air battery module 200A as a whole can be reduced, weight reduction can be achieved, and the energy density can be improved.

  Further, in the lithium air battery module 200A according to the present embodiment, even if the electrolyte 15 volatilizes as the discharge progresses, it is only necessary to replenish the electrolyte in the case 101, and replenish the electrolyte for each lithium air battery 100. There is no need.

  Further, in the lithium air battery module 200A according to the present embodiment, the lithium air battery 100 has a rectangular parallelepiped shape, and therefore, the lithium air battery 100 can be efficiently disposed in the case 101. In addition, since the air electrode layer 11 itself also serves as an exterior, it is not necessary to separately provide a partitioning part corresponding to the exterior of the lithium-air battery in the case 101. Therefore, the space inside the case 101 can be used effectively, which contributes to the improvement of the energy density of the lithium air battery module 200A.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, the negative electrode composite_body | complex of lithium air battery which concerns on this invention, a lithium air battery, and a lithium air battery module are not restrict | limited by the following Example.

[Example 1]
1. Production of Box-shaped Structure Solid Electrolyte 203 (1) A lithium ion conductive glass ceramic (LTAP) thin plate was cut into five plates.
(2) A two-component curable epoxy adhesive was applied to the end face of a plate-shaped LTAP thin plate, bonded together, and a box-shaped pentahedron with one side opened was assembled to prepare a solid electrolyte 203.

2. Production of Negative Electrode Composite The negative electrode composite 210 was assembled in the following procedure under an inert atmosphere with Ar having an oxygen concentration of 1 ppm or less and a dew point of −76 ° C. dp. FIG. 8 shows a schematic cross-sectional view of the negative electrode composite 210.
(1) The box-shaped solid electrolyte 203 produced in 1 above, which is a constituent member of the negative electrode composite 210, and the metal lithium negative electrode 201 (square, two) bonded to both surfaces of the copper foil (negative electrode current collector) 202, A separator 204 (square, two sheets) made of a PP resin porous sheet and a gasket sheet 205 (EPDM, one sheet) arranged on the upper surface were prepared.
(2) A metallic lithium negative electrode 201 (with a copper foil 202 current collector) was sandwiched between two PP resin porous sheets 204 and inserted into a box-shaped solid electrolyte 203.
(3) An organic electrolyte (EC: EMC = 1: 1, 1M LiPF ₆ ) was dropped into the solid electrolyte 203. It was confirmed that the electrolyte solution was filled up to the upper part in the solid electrolyte 203.
(4) A part of the copper foil (negative electrode current collector) 202 affixed to the metal lithium 201 was exposed to the outside of the solid electrolyte 203, and a gasket sheet 205 was attached to the upper opening of the solid electrolyte 203. The end portions of the gasket sheet 205 and the solid electrolyte 203 were adhered and sealed with an epoxy adhesive 206 (two-component room temperature curing type).

3. Production of Air Electrode 400 mg of platinum-supported carbon (Pt 45.8%) as a catalyst for oxygen reduction of the positive electrode and 100 mg of polyvinylidene fluoride (PVdF) as a binder (binder) were weighed, and N-methyl-2- A mixed solvent was prepared by adding 15 ml of pyrrolidone (NMP).
The mixed solvent was stirred and dispersed with a stirrer (AR-100 manufactured by Shinki Co., Ltd.) for 15 minutes and with ultrasonic waves for 60 minutes, and coated on a carbon cloth using a coating machine, and then placed on a hot plate to be 110. An air electrode having a platinum loading of 0.25 mg / cm ² was produced by heating and drying at 0 ° C. for 1 hour. After that, the air electrode was cut and assembled into a box-shaped pentahedron whose one surface was opened so as to cover the box-shaped solid electrolyte. The positive electrode current collector was affixed to the air electrode with the same material as the air electrode.

4). Preparation of aqueous electrolyte 42.4 g of LiCl was dissolved in 500 ml of purified water to prepare a 2M LiCl aqueous solution.

5. Preparation of Cell A container in which a box-shaped negative electrode composite 210 is housed in a box-shaped air electrode is placed in a plastic case having a size that can accommodate the air electrode and having a vent hole. In addition to the extent that the whole was immersed, a lithium-air battery cell of Example 1 was obtained.

[Comparative Example 1]
1. Production of Negative Electrode Composite A negative electrode composite 310 was produced by the following procedure in an inert atmosphere with Ar having an oxygen concentration of 1 ppm or less and a dew point of −76 ° C. dp. FIG. 9 shows a schematic cross-sectional view of the negative electrode composite 310. The negative electrode composite 310 has the same outer size as the negative electrode composite 210 of Example 1.
(1) Solid electrolyte 303 (lithium ion conductive glass ceramics (LTAP) thin plate, square, two pieces), which is a constituent member of the negative electrode composite 310, metal lithium 301 (metal Li, square, two pieces, copper foil (negative electrode collection) Electrical body) 310) and cellulose separator 304 (square, 2 sheets) and gasket sheet 308 (EPDM, square frame, 2 sheets) were prepared. A gasket sheet 308 was attached to each of the two solid electrolytes 303.
(2) On one solid electrolyte 303 shown on the lower side in FIG. 9, the cellulose separator 304 is disposed so as to enter the frame of the gasket sheet 308, and an organic electrolyte (EC: EMC = 1: 1, 1M). Of LiPF ₆ ) was dripped into the cellulose separator 304 and soaked throughout. The metallic lithium 301 was placed on the cellulose separator 304 so as to enter the frame of the gasket sheet 308, and the second cellulose separator 304 was placed on the metallic lithium 301. The organic electrolyte was dropped into the second cellulose separator 304 and soaked throughout.
(3) The upper solid electrolyte 303 prepared in (1) is placed over the product in (2), and the upper and lower gasket sheets 308 are pasted so as not to shift so that no external air or the like enters. Thus, the gasket sheet 308 was sealed by the adhesiveness. The constituent members inside the negative electrode composite 310 were pressed and fixed from the outside so that the components contact each other with good adhesion.
(4) An epoxy adhesive 309 (two-component room temperature curing type) is thinly applied to the entire periphery of the outer peripheral edge of the solid electrolyte 303 so that the space between the two solid electrolytes 303 is sealed. 309 was cured.

2. Production of Air Electrode Weigh 80 mg of platinum-supported carbon (Pt 45.8%) as a catalyst for oxygen reduction of the positive electrode and 20 mg of polyvinylidene fluoride (PVdF) as a binder (binder), and measure N-methyl-2- A mixed solvent was prepared by adding 3 ml of pyrrolidone (NMP).
Stir and disperse the mixed solvent for 15 minutes with an agitator (AR-100 manufactured by Shinki Co., Ltd.) and 60 minutes with ultrasonic waves, and apply on the carbon cloth using a coating machine (K202 Control Coater made by Matsuo Sangyo). Then, it was placed on a hot plate and dried by heating at 110 ° C. for 1 hour to produce an air electrode having a platinum loading of 0.25 mg / cm ² . As a current collector for the air electrode, the carbon cloth of the air electrode was extended in a rectangular shape.

3. Preparation of aqueous electrolyte The aqueous electrolyte was prepared in the same manner as in Example 1.

4). Production of Cell In a plastic case with a hole and a size that can accommodate the negative electrode composite 310, an air electrode, a cellulose sheet in which an aqueous electrolyte is dropped, a negative electrode composite 310, a cellulose sheet in which an aqueous electrolyte is dropped, and A cell in which the air electrode was stacked so that there was no deviation in this order was accommodated, and a lithium-air battery cell of Comparative Example 1 was obtained.

[Discharge test]
In the cells of Example 1 and Comparative Example 1, the discharge voltage when discharged at 4 mA / cm ² (about 0.1 C discharge rate) was measured with ALS608A manufactured by BAS for 10 hours. Here, 1C indicates a current value at which discharge is completed in just one hour after constant-current discharge of a cell having a nominal capacity. The measurement results of the discharge voltage are shown in Table 1. The cells of Example 1 and Comparative Example 1 both showed a high discharge voltage at the beginning of discharge, but the cell of Example 1 maintained a higher discharge voltage for a longer time than the cell of Comparative Example 1.

DESCRIPTION OF SYMBOLS 1 Negative electrode layer 2 Negative electrode collector 3 Separation layer 3a Opening surface 3b Front side surface 3c Rear side surface 4 Buffer layer 5 Gasket 6 Adhesive 10, 10A Negative electrode complex 11 Air electrode layer 12 Air electrode current collector 13 Air electrode 15 Electrolyte 100 Lithium air battery 101 Case 200, 200A Lithium air battery module

201 Metal Lithium 202 Copper Foil 203 Solid Electrolyte 204 Separator 205 Gasket Sheet 206 Epoxy Adhesive 210 Negative Electrode Composite

301 Metal Lithium 302 Copper Foil 303 Solid Electrolyte 304 Cellulose Separator 308 Gasket Sheet 309 Epoxy Adhesive 310 Negative Electrode Composite

Claims (8)

A plate-like or linear negative electrode current collector;
Two plate-shaped negative electrode layers containing metallic lithium, a lithium alloy, or a lithium compound and sandwiching a part of the negative electrode current collector;
A negative electrode composite for a lithium-air battery, which has a hollow box shape with one surface open and includes a lithium ion conductive isolation layer that accommodates the two negative electrode layers therein.   The negative electrode composite according to claim 1, wherein the opening is sealed with a gasket and / or an adhesive.   The negative electrode composite according to claim 1, further comprising a buffer layer between the negative electrode layer and the isolation layer. The negative electrode composite according to any one of claims 1 to 3,
An air electrode layer containing a conductive material and having a surface opposite to at least one surface of the isolation layer;
A lithium air battery comprising: an air electrode comprising a plate-like or linear air electrode current collector electrically connected to the air electrode layer.   The air electrode layer has a hollow box shape with an open surface, accommodates the negative electrode composite therein, and each inner surface of the air electrode layer faces one of the outer surfaces of the isolation layer. 4. The lithium air battery according to 4.   The lithium air battery according to claim 5, wherein the air electrode layer is formed as an integral part.   A lithium air battery module comprising a plurality of lithium air batteries according to any one of claims 1 to 6 connected in parallel. A case housing the plurality of lithium-air batteries;
The lithium air battery module according to claim 7, further comprising an electrolyte stored in the case and in contact with at least the air electrode.

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