JP2015060665A - Air cell, negative electrode for air cell, and air cell unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an air cell capable of preventing self discharge of diboride vanadium (VB) by a simple process at a low cost, and having high discharge capacity, power and voltage.SOLUTION: An air cell 100 includes a negative electrode 110 containing, as a negative electrode active material, a VB/metal composite generating electrons by reacting on hydroxide ions and subsuming the VBparticles with a metal becoming a hydroxide by the reaction, a positive electrode 130 where oxygen is the positive electrode active material, and an electrolyte 150 conducting hydroxide ions between the negative electrode 110 and positive electrode.

Description

  The present invention relates to an air battery having a positive electrode using oxygen as a positive electrode active material, a negative electrode used in the air battery, and an air battery unit in which a plurality of cells of the air battery are connected.

In recent years, research on air batteries, which are batteries using a single metal or an alloy or metal compound thereof as a negative electrode active material and oxygen as a positive electrode active material, has been actively conducted. Since this air battery uses oxygen in the air as the positive electrode active material, it is not necessary to fill the battery with the positive electrode active material, and a large amount of the negative electrode active material can be filled accordingly. Therefore, theoretically, an air battery can realize a larger capacity than a battery using a solid positive electrode active material. For the negative electrode of the air battery, for example, a chemically base metal M such as zinc, lithium, aluminum, magnesium, iron or the like is used. For the positive electrode (air electrode), carbon, metal, alloy or the like is made porous. A gas diffusion electrode coated with an oxygen reduction catalyst is used. When oxygen in the air is taken into the gas diffusion electrode, a discharge reaction represented by the following formula proceeds.
Negative electrode: M → M ^{n +} + ne ⁻
Positive electrode: O ₂ + 2H ₂ O + 4e ⁻ → 4OH ⁻

For the negative electrode, not only the metal M but also an alloy or metal compound of the metal M can be used. As an example of a battery using a metal compound as such a negative electrode active material, an air battery using a reduced boron-containing compound such as titanium diboride, vanadium diboride (VB ₂ ), or aluminum boride as a negative electrode active material. Has been proposed (see, for example, Patent Document 1). According to the air battery described in Patent Document 1, it is said that by using a reduced boron-containing compound, a large amount of electrons are generated by a discharge reaction, and a battery having a high energy density can be produced.

  However, just using a reduced boron-containing compound as the negative electrode active material as in the air battery described in Patent Document 1, even if the amount of electrons generated from one reduced boron-containing compound is large, electrochemical When the area related to the reaction (discharge reaction) (the specific surface area of the negative electrode active material) is small, there is a problem in that sufficient discharge capacity, power and voltage cannot be obtained because the total amount of electrons generated is small. It was.

On the other hand, an air battery using 1% by weight or more of vanadium diboride (VB ₂ ) nanoparticles as a negative electrode active material has been proposed (see, for example, Patent Document 2). In the air battery described in Patent Document 2, as VB ₂ used for the negative electrode, nanometer-order particles obtained by pulverizing micrometer-order VB ₂ particles by a predetermined method are used. It is said that the discharge capacity, power and voltage can be improved by increasing the reaction site area). Patent Document 2 discloses that a specific method is used as a method for pulverizing VB ₂ particles on the order of micrometers, thereby reducing the risk of decomposition of VB ₂ resulting from the promotion of electron transfer and VB ₂ nanometers. It also describes the point of preventing the function of the negative electrode from deteriorating due to the large variation in particle size.

Special table 2002-500804 gazette International Publication No. 2012/021607

Renewable high capacity capacity VB2 / air energy storage, Chem. Commun. , 2008, 3257-3259 Nano-VB2 synthesis from elemental vanadium and boron: nano-VB2 nano / air batteries, Electrochemical and Solid-state Letters, 15 (1) (2012) A12-A12-A.

Here, when VB ₂ is used as the negative electrode active material and an alkaline substance such as potassium hydroxide (KOH) is used as the electrolyte as in the invention described in Patent Document 2, an aqueous solution of such an alkaline substance is used. There is a problem that VB ₂ used as a negative electrode active material (negative electrode fuel) is eluted, and the eluted VB ₂ reacts with hydroxide ions in the aqueous solution to cause self-discharge. In particular, there is a report that VB ₂ has a high self-discharge rate (for example, 10% self-discharge at 45 ° C. for one week and 35% self-discharge at 70 ° C. for one week) (for example, see Non-Patent Document 1). Therefore, it is highly necessary to suppress self-discharge. Nevertheless, the invention described in Patent Document 2 described above has a problem that the discharge capacity may be reduced due to self-discharge because VB ₂ self-discharge is not particularly considered.

In addition, since V ₂ O ₅ and B ₂ O ₃ which are compounds generated in the discharge reaction of VB ₂ are highly corrosive, for example, a metal current collector having high reactivity in an alkaline environment is used. May corrode the current collector, thereby hindering the speed of movement of electrons (lowering the conductivity). In Patent Document 2, since the corrosivity of V ₂ O ₅ and B ₂ O ₃ is not taken into consideration, there is a problem that a sufficient discharge capacity cannot be obtained.

In order to solve such a problem, a technique for suppressing self-discharge by coating vanadium diboride (VB ₂ ), which is a negative electrode active material, with a ZrO ₂ thin film of less than 1% by weight has been proposed (for example, (Refer nonpatent literature 2). According to the technique of this nonpatent literature 2, it is supposed that self-discharge can be suppressed to 15% in 70 degreeC 1 week.

However, in the technique of Non-Patent Document 2, the ZrO ₂ thin film forming process is complicated and ZrO ₂ is an expensive raw material, so that it is difficult in terms of manufacturing process and cost in the mass production process of the negative electrode active material. Will bring. Further, ZrO ₂ that does not become an active material (does not cause a discharge reaction) is coated, and the amount of the active material in the negative electrode is reduced accordingly, so that the discharge capacity and voltage are reduced (for example, open-circuit voltage). 1.3V for the actual circuit and 0.9V for the actual circuit).

Further, in the air battery described in Patent Document 2 and Non-Patent Document 2, an extra process and energy of pulverizing VB ₂ particles of micrometer order into particles of nanometer order are necessary, and the pulverization process Since the process itself is a special and complicated process, the process becomes complicated and increases the cost.

Therefore, the present invention has been made in view of the above circumstances, and it is possible to prevent the self-discharge of VB ₂ with a simple process and low cost, and to obtain an air battery having high discharge capacity, power and voltage. Objective.

As a result of intensive studies to solve the above problems, the present inventors have reacted with hydroxide ions as negative electrode active materials to generate electrons and diboride with a metal that becomes hydroxide by the reaction. It has been found that by using a VB ₂ / metal composite containing vanadium particles, self-discharge of VB ₂ can be prevented and an air battery having high discharge capacity, power and voltage can be obtained. The invention has been completed.

That is, the present invention contains, as a negative electrode active material, a VB ₂ / metal composite that reacts with hydroxide ions to generate electrons and includes a vanadium diboride particle with a metal that becomes a hydroxide by the reaction. And an electrolyte that conducts hydroxide ions between the negative electrode and the positive electrode, and an air battery.

The VB ₂ / metal composite preferably has an average particle size of 30 μm or more and 800 μm or less.

  The average particle diameter of vanadium diboride included in the metal is preferably 0.5 μm or more and 500 μm or less.

  The metal may be at least one metal selected from the group consisting of zinc, aluminum, magnesium, lithium, sodium, calcium, and alloys thereof.

It is preferable that the VB ₂ / metal composite further includes vanadium diboride particles encapsulated with conductive carbon and the metal.

  The conductive carbon that includes the vanadium diboride may be at least one selected from the group consisting of carbon nanotubes, carbon black, graphene, graphite, carbon fiber, graphite, and activated carbon.

The negative electrode may further contain a first conductive material having an average particle size less than the average particle size of the VB ₂ / metal composite.

The negative electrode may further contain a second conductive material having an average length equal to or larger than an average particle diameter of the VB ₂ / metal composite.

The first conductive material is contained in an amount of 0.5 to 50 parts by mass with respect to 100 parts by mass of the VB ₂ / metal composite, and the second conductive material is the VB ₂ / metal composite 100. It is preferably contained in an amount of 0.1 to 30 parts by mass with respect to parts by mass.

  The first conductive material and the second conductive material are preferably conductive carbon.

  The first conductive material is at least one conductive carbon selected from the group consisting of carbon black, graphite and activated carbon, and the second conductive material is at least one conductive selected from the group consisting of graphene, carbon nanotube and carbon fiber. It is preferable that it is a property carbon.

  The material of the current collector of the negative electrode is preferably graphite or a metal that is inactive under an alkaline environment.

In the negative electrode, the discharge region containing the VB ₂ / metal composite may be divided into a plurality in a state of being separated from each other.

The current collector of the negative electrode has a plurality of discharge cells separated from each other, and a partition is provided between the adjacent discharge cells, and each discharge cell has the discharge region as the discharge region. the VB 2 _/ metal complex may have a negative electrode active material layer containing.

  The electrolyte may be an aqueous or non-aqueous electrolytic solution, and may further include a separator that electrically insulates the negative electrode and the positive electrode, and the separator may be impregnated with the electrolytic solution.

  The negative electrode may be provided detachably with respect to the air battery.

The present invention also relates to a negative electrode for an air battery having a positive electrode having oxygen as a positive electrode active material, wherein the negative electrode active material generates electrons by reacting with hydroxide ions and reacts with hydroxides by the reaction. containing VB 2 _/ metal complexes inclusion diboride, vanadium particles comprising metal, a negative electrode.

  Moreover, this invention is an air battery unit which has multiple cells of the air battery mentioned above.

According to the present invention, as the negative electrode active material, a VB ₂ / metal composite containing a vanadium diboride particle with a metal that reacts with hydroxide ions to generate electrons and becomes a hydroxide by the reaction is used. Therefore, it is possible to obtain an air battery having high discharge capacity, power and voltage while preventing self-discharge of VB ₂ with a simple process and low cost.

It is a perspective view which shows the external appearance structure of the air battery which concerns on 1st Embodiment of this invention. It is a top view of the air battery shown in FIG. It is a disassembled perspective view which shows the internal structure of the air battery which concerns on the same embodiment. It is a disassembled perspective view which shows the structure of the positive electrode which concerns on the same embodiment. It is a schematic view showing a configuration of a VB 2 _/ metal complex according to the embodiment. VB 2 _/ metal composite of the negative electrode active material layer according to the embodiment is a schematic diagram showing the existence form of the first conductive material and the second conductive material. It is a perspective view which shows the structure of the negative electrode which concerns on the example of a change of the embodiment. It is a perspective view which shows the connection method of the negative electrode based on another modified example of the embodiment, and a positive electrode. It is explanatory drawing which shows the manufacturing method of the negative electrode which concerns on the same embodiment. It is a schematic view showing a configuration of a manufacturing apparatus of VB 2 _/ metal complex according to the embodiment. It is a perspective view which shows the whole structure of the air battery unit which concerns on the same embodiment. It is a top view of the air battery unit shown in FIG. It is a disassembled perspective view which shows the assembly method of the air battery unit which concerns on the same embodiment. It is a schematic diagram for demonstrating the operation principle of the air battery which concerns on the same embodiment. It is a perspective view which shows the external appearance structure of the air battery which concerns on 2nd Embodiment of this invention. FIG. 16 is a plan view of the air battery shown in FIG. 15. It is a disassembled perspective view which shows the internal structure of the air battery which concerns on the same embodiment. It is a perspective view which shows the whole structure of the air battery unit which concerns on the same embodiment. It is a top view of the air battery unit shown in FIG. It is a disassembled perspective view which shows the assembly method of the air battery unit which concerns on the same embodiment. It is a graph which shows the discharge curve in the single cell in the Example of this invention. It is a graph which shows the discharge curve in 10 cells in the Example of this invention.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. Note that in the present specification and drawings, components having the same reference numerals have substantially the same structure or function.

The air battery, the negative electrode for air battery, and the air battery unit according to the present invention will be described in the following order.
1 First Embodiment 1-1 Configuration of Air Battery 1-2 Air Battery Manufacturing Method 1-3 Configuration of Air Battery Unit 1-4 Assembly Method of Air Battery Unit 1-5 Operating Principle of Air Battery 1-6 Air Battery And use and usage method 2 of the air battery unit 2nd Embodiment 2-1 Configuration of the air battery 2-2 Manufacturing method of the air battery 2-3 Configuration of the air battery unit 2-4 Assembly method of the air battery unit

<< First Embodiment >>
An air battery and an air battery unit according to a first embodiment of the present invention will be described. The “air battery unit” in the present embodiment means a unit formed by connecting a plurality of unit cells of the air battery (in this embodiment, the air battery cell 100).

<Configuration of Air Battery Cell 100>
First, the structure of the air battery cell 100 which concerns on this embodiment is demonstrated, referring FIGS. FIG. 1 is a perspective view showing an external configuration of an air battery cell 100 according to the present embodiment. 2 is a plan view of the air battery cell 100 shown in FIG. 1, wherein (a) is a top view, (b) is a front view, (c) is a left side view, and (d) is a right side view. ing. FIG. 3 is an exploded perspective view showing the internal configuration of the air battery cell 100 according to the present embodiment. FIG. 4 is an exploded perspective view showing the configuration of the positive electrode 130 according to the present embodiment. FIG. 5 is a schematic diagram showing the configuration of the VB ₂ / metal composite according to this embodiment, where (a) shows the state before the discharge reaction, and (b) shows the state after the discharge reaction. FIG. 6 is a schematic diagram showing the presence forms of the VB ₂ / metal composite, the first conductive material, and the second conductive material in the negative electrode active material layer 112 according to the present embodiment. FIG. 7 is a perspective view showing the configuration of the negative electrode 120 according to a modified example of the present embodiment.

  As shown in FIGS. 1 to 4, the air battery cell 100 according to this embodiment includes a negative electrode (anode) 110 as a fuel electrode, a positive electrode (cathode) 130 as an air (oxygen) electrode, and the present embodiment. An electrolyte 150 as an example of such an electrolyte and a separator 160 as necessary are provided. In the air battery cell 100, two sheet-like positive electrodes 130 are arranged inside the housing 101 so as to sandwich the plate-like negative electrode 110 from the front side and the back side.

  More specifically, in the state where the negative electrode current collector 111 and the negative electrode active material layer 112 of the negative electrode 110 are entirely covered by the bag-shaped separator 160, the negative electrode 110 is opened in the housing 101 in which the positive electrode 130 is disposed. Housed in the housing 101 from the portion 101a. Further, the electrolyte 150 is injected into the housing 101 from the opening 101 a in a state where the negative electrode 110 and the positive electrode 130 are accommodated in the housing 101. At this time, the electrolyte 150 is present inside the separator 160 (a state where the electrolyte 150 and the negative electrode 110 are in contact) and outside (a state where the electrolyte 150 and the positive electrode 130 are in contact). In the above state, the opening 101 a is sealed by the cap 105.

  As shown in FIG. 4, the housing 101 includes a housing frame 102, a front cover 103, and a back cover 104. The housing frame 102 has an opening 102 a, and the front cover 103 and the back cover 104 are attached to the housing frame 102 so as to cover the opening 102 a from both the front and back sides of the housing frame 102. Specifically, the front cover 103 and the back cover 104 are attached to the housing frame 102 by fitting the peripheral portions of the front cover 103 and the back cover 104 with the peripheral portions of the opening 102 a. In the present embodiment, a partition member 102b extending in the height direction of the housing frame 102 is provided at a substantially central portion of the opening 102a. The partition member 102b may be provided as necessary. As described later, the positive electrode 120 is disposed in each of the two regions separated by the partition member 102b of the opening 102a. In addition, an opening 103a and an opening 104a are provided at substantially the center portions of the front cover 103 and the back cover 104, respectively. The opening 103a and the opening 104a are respectively formed in a lattice-like partition 103b and a partition 104b. Thus, it is divided into a plurality of sections. These partitions 103b and 104b may be provided as necessary. However, by providing the partitions 103b and 104b, the mechanical strength of the casing 101 can be increased, or a water-repellent oxygen permeable sheet 133 described later (FIG. 4 and the like). Can be prevented from being damaged.

  The cap 105 is attached so as to be fitted to the upper portion of the housing frame 102 so as to cover the opening 101 a provided in the upper portion of the housing frame 102. The cap 105 is configured to be slidable in one direction (for example, the x-axis direction in FIG. 3) by the slide member 106. The slide member 106 is provided with an engagement protrusion 106 a. With the engagement protrusion 106 a engaged with the peripheral edge portion of the opening 105 a provided in the cap 105, the cap 105 is located with respect to the slide member 106. The cap 105 can be attached to and detached from the housing 101 by sliding in the one direction. For example, when the cap 105 is slid in the direction of “OPEN” displayed on the upper surface of the cap 105 shown in FIGS. 1 to 3, the cap 105 can be removed from the housing 101, and the upper surface of the cap 105 can be removed. The cap 105 can be attached to the housing 101 by sliding the cap 105 in the displayed “CLOSE” direction.

  In this embodiment, one air battery cell 100 has two electrode pairs (one negative electrode 110 and two positive electrode 130 pairs disposed on both sides thereof). When the discharge capacity of the air battery cell 100 is increased and can be used even with a relatively small discharge capacity depending on the use of the air battery according to the present invention, one air battery cell 100 has one set. You may have only an electrode pair. On the other hand, when a very large discharge capacity is required depending on the use of the air battery according to the present invention, one air battery cell 100 may have three or more electrode pairs.

[Negative electrode 110]
The negative electrode 110 is an electrode that functions as a fuel electrode of the air battery cell 100. For example, as shown in FIG. 3, the negative electrode current collector 111, the negative electrode active material layer 112, the electrode-side negative electrode terminal 113, and the cell side And a negative electrode terminal 114.

(Negative electrode current collector 111)
The negative electrode current collector 111 is a substantially plate-like member having conductivity, and has a role of holding a negative electrode active material and supplying a current to the negative electrode active material.

[Material]
The material of the negative electrode current collector 111 is not particularly limited as long as it is a conductive material. For example, conductive materials such as aluminum, stainless steel, nickel, chromium, gold, platinum, silver, and copper are used. And conductive carbon such as carbon black (furnace black, channel black, acetylene black, thermal black, etc.), graphene, graphite, carbon nanotube, carbon nanohorn, etc. can be used. However, as the material of the negative electrode current collector 111, it is preferable to use graphite or a metal that is inactive in an alkaline environment (for example, brass or the like). By using graphite or a metal that is inactive in an alkaline environment as the material of the negative electrode current collector 111, the negative electrode current collector 111 itself is oxidized even if the fuel VB ₂ / metal complex undergoes an oxidation-reduction reaction. Since the reduction reaction does not occur, an increase in the internal resistance of the battery can be suppressed. The negative electrode active material layer 112 includes a first conductive material and a second conductive material as conductive aids that impart conductivity of the negative electrode active material, and conductive carbon ( For example, when carbon black or graphene) is used, the negative electrode current collector 111 is preferably made of graphite. By using graphite as the negative electrode current collector 111 and using conductive carbon as a conductive additive in the negative electrode active material layer 112, the negative electrode current collector 111 and the negative electrode active material layer 112 have the same thermal expansion coefficient. Therefore, when the temperature in the air battery cell 100 rises due to a discharge reaction or the like, the negative electrode active material layer 112 can be made difficult to peel from the negative electrode current collector 111.

〔shape〕
The negative electrode current collector 111 has a substantially plate shape, and a plurality of groove portions 111a are provided on both front and back surfaces. Each groove portion 111a is provided such that its length direction is perpendicular to the longitudinal direction of the negative electrode current collector 111, and its width direction is the longitudinal direction of the negative electrode current collector 111. The negative electrode current collector 111 is arranged along the longitudinal direction. In addition, a partition wall 111b is provided between adjacent groove portions 111a so that the groove portions 111a are spaced apart from each other. The width of the partition 111b (the length in the longitudinal direction of the negative electrode current collector 111) is not particularly limited as long as the grooves 111a are physically separated. Further, the shape of the side cross section of the groove 111a (a surface parallel to the YZ plane in FIG. 3) is not particularly limited, and may be any shape such as a substantially rectangular shape, a substantially triangular shape, a substantially polygonal shape, or a substantially arc shape. be able to.

(Negative electrode active material layer 112)
The negative electrode active material layer 112 is a layer that is provided in the groove 111 a of the negative electrode current collector 111 described above and includes a negative electrode active material that serves as a fuel when the air battery cell 100 is discharged. The negative electrode active material layer 112 contains, as an essential component, a VB ₂ / metal composite that reacts with hydroxide ions to generate electrons and includes VB ₂ particles with a metal that becomes hydroxide by the reaction. . In this case, the present embodiment, what with VB 2 _/ metal composite as the negative electrode active material (fuel) is, VB ₂ from to generate the eleven electrons by discharge reaction, high energy density (zinc About 5 times that of an air battery), and further, a metal that encapsulates VB ₂ particles (hereinafter referred to as “inclusion metal”) also functions as a negative electrode active material (fuel), and discharge reaction (with hydroxide ions). This is because the discharge capacity of the air battery cell 100 is increased as a result of generating electrons by reaction. Theoretically, when a VB ₂ / metal composite is used as the negative electrode active material, the capacity can exceed 5000 Ah per 1 kg of VB ₂ , depending on the type of inclusion metal.

In addition, the inclusion metal becomes a reaction-inactive hydroxide after the discharge reaction. Accordingly, this means that VB ₂ particles are coated with a hydroxide of a reaction inert subsumption metal, it is possible to prevent self-discharge of VB _2.

Thus, the inclusion of VB ₂ particles with a chemically base metal not only fundamentally solved the problem of VB ₂ self-discharge, but also the product of the VB ₂ discharge reaction. Since V ₂ O ₅ and B ₂ O _3, which also have an effect as an inclusion metal catalyst (hereinafter referred to as “internal catalytic effect”), can also promote the discharge reaction of the inclusion metal. In addition, by using such a VB ₂ / metal composite, the process of pulverizing micrometer-order VB ₂ particles to nanometer order as in Patent Document 2 can be performed with a simple process and low cost. An air battery having a high energy density and a high discharge capacity can be obtained.

In addition, the VB ₂ / metal composite as described above is used as a negative electrode active material, and an average length equal to or greater than the average particle diameter of the VB ₂ / metal composite is used as a conductive aid for assisting the conductivity of the negative electrode active material. And the second conductive material having an average particle diameter less than the average particle diameter of the VB ₂ / metal composite, promotes electron transfer during discharge and further improves conductivity. Can do.

Here, in this embodiment, the negative electrode active material layers 112 are provided on both surfaces of the negative electrode current collector 111, and correspondingly, the positive electrode 130 is also provided on both surfaces of the negative electrode 110 as described later. Yes. Therefore, more oxygen can be used as the fuel for the positive electrode 130, and further, the VB ₂ / metal composite as the negative electrode active material can also be reacted efficiently, thereby improving the discharge efficiency. . Note that the negative electrode of the air battery according to the present invention may have not only the negative electrode active material layer on both sides of the current collector but also one side.

Furthermore, the negative electrode current collector 111 does not have a structure in which the negative electrode active material layer 112 is provided, but a slurry containing a current collector material, a VB ₂ / metal composite, a first conductive material, and a second conductive material is used. A material obtained by sintering and integrating the current collector and the negative electrode active material layer may be used as the negative electrode of the air battery according to the present invention. At this time, it is preferable that the VB ₂ / metal composite as the negative electrode active material, the first conductive material, and the second conductive material are uniformly dispersed in the negative electrode. Due to the uniform dispersion, an increase in internal resistance due to the discharge reaction of the VB ₂ / metal complex being concentrated on a part can be suppressed.

[VB ₂ / metal composite]
As shown in FIG. 5A, the VB ₂ / metal composite contained in the negative electrode active material layer 112 according to this embodiment is used as the negative electrode active material (fuel) of the air battery cell 100, as described above. The VB ₂ particles are included by a metal (inclusion metal) that reacts with hydroxide ions to generate electrons and becomes a hydroxide by the reaction. In this embodiment, as shown in FIG. 5A, the surface of the VB ₂ particles is included with conductive carbon such as carbon nanotubes (CNT), and the surface is included with an included metal such as zinc (Zn). However, it is not always necessary to use conductive carbon.

  As such an inclusion metal, it reacts with hydroxide ions to generate electrons (that is, has a function as a negative electrode active material in the present air battery), and a metal that becomes hydroxide by the reaction (that is, The metal hydroxide is not particularly limited as long as it becomes a metal hydroxide having no activity for the discharge reaction after the discharge reaction. Specific examples of inclusion metals that can be used in the present embodiment include zinc, aluminum, magnesium, lithium, sodium, calcium, and alloys thereof. These may be used alone or in combination of two or more. May be used.

By using the inclusion metal as described above, since the amount of electrons generated by the discharge reaction of the inclusion metal itself is larger than when VB ₂ is used alone as the negative electrode active material, the discharge capacity is increased. Can be further increased. In addition, as shown in FIG. 5 (b), a metal hydroxide such as [Zn (OH ₄ )] ²⁻ is generated by the discharge reaction of the inclusion metal, and this metal hydroxide has an activity for the discharge reaction. Therefore, the surface of VB ₂ is covered with such a reaction-inactive substance, and VB ₂ is protected, so that self-discharge of VB ₂ can be prevented. Furthermore, as a result of the discharge reaction of VB ₂ , V ₂ O ₅ and B ₂ O ₃ are generated as shown in FIG. 5B. These products are effective as a catalyst for the discharge reaction of the inclusion metal ( Hereinafter, it is also referred to as “internal catalytic effect.”), The discharge reaction of the inclusion metal can also be promoted.

Here, it is preferable that the VB ₂ / metal composite is obtained by further including VB ₂ particles encapsulated with conductive carbon with an encapsulating metal. The conductive carbon has a function to increase the surface activity of VB ₂ particle surface to facilitate the adsorption of inclusion metal to VB ₂ particle surface. That is, since the conductive carbon exists between the VB ₂ particles and the inclusion metal, the inclusion metal is easily adsorbed on the surface of the VB ₂ particles. Conductive carbon also has a role as a path when electrons generated by the discharge reaction of VB ₂ reach the inclusion metal. That is, when conductive carbon exists between the VB ₂ particles and the inclusion metal, electrons generated by the discharge reaction of VB ₂ are easily transmitted to the positive electrode through the conductive carbon and the inclusion metal.

Examples of the conductive carbon including VB ₂ having the above role include nano-sized conductive carbon such as carbon nanotube, carbon black, graphene, graphite, carbon fiber, graphite, activated carbon, and the like. These can be used individually or in combination of 2 or more types. Among these conductive carbons, nano-sized conductive carbon is suitable, and furthermore, the specific surface area is large and the surface of the VB ₂ particles can be covered densely, and the carbon nanotubes are excellent in conductivity. It is particularly preferred to use it.

In addition, the VB ₂ / metal composite according to this embodiment is preferably a particle having a particle diameter on the order of micrometers. In the present embodiment, as in the battery described in Patent Document 2 described above, VB ₂ particles having a particle size on the micrometer order can be used as they are without being pulverized until reaching a particle size on the nanometer order. . This is, in the present embodiment, as a conductive additive to aid the conductivity of VB _2, from the fact that by using a first conductive material and the second conductive material having a specific shape and size, the particle size of VB ₂ is This is because the negative electrode active material layer 112 (and thus the entire negative electrode 110 as a whole) can have sufficient conductivity even if it is large. In addition, the detailed reason which can have sufficient electroconductivity in this way is mentioned later.

Specifically, the particle diameter of the VB ₂ / metal composite according to this embodiment is preferably an average particle diameter of 30 μm or more and 800 μm or less. When the average particle size is less than 30 μm, it is not preferable because inclusion of VB ₂ particles with metal becomes difficult (complex production becomes difficult). On the other hand, when the average particle diameter exceeds 800 μm, the specific surface area is small, the area of the reaction site used for the discharge reaction is small, and large current discharge is difficult. From the viewpoint of battery performance, the average particle size of the VB ₂ / metal composite is preferably 50 μm or more, and more preferably 100 μm or more. On the other hand, from the viewpoint of battery discharge characteristics and production cost, the average particle size of the VB ₂ / metal composite is preferably 700 μm or less, and more preferably 500 μm or less.

In this case, the average particle diameter of the VB ₂ particles included in the included metal is preferably 0.5 μm or more and 500 μm or less. The lower limit value of the average particle diameter is more preferably 1 μm, and further preferably 2 μm. On the other hand, the upper limit value of the average particle diameter is more preferably 100 μm or less, and further preferably 10 μm or less.

Incidentally, the average particle diameter of VB ₂ particles and VB 2 _/ metal complex in the present embodiment, the scanning electron microscope by taking any 100 particles of 100 by image analysis of pictures taken The particle diameter of the particles is measured, and a value obtained by averaging these is used.

[First and second conductive materials]
The VB ₂ / metal composite contained in the negative electrode active material layer 112 according to the present embodiment has a relatively low electrical conductivity, and when such particles are solidified and used, the internal resistance increases. The performance of the battery cell 100 may deteriorate. Therefore, in the present embodiment, the first conductive material is used as a conductive assistant in the negative electrode active material layer 112 in order to assist the conductivity of the VB ₂ / metal composite used as the negative electrode active material and reduce the internal resistance. And the second conductive material is preferably included. That is, the first conductive material and the second conductive material, which are conductive assistants, have a role of facilitating conduction of electrons generated by the discharge reaction of VB ₂ or the inclusion metal to the current collector.

Here, the presence form of the VB ₂ / metal composite, the first conductive material, and the second conductive material in the negative electrode active material layer 112 will be described with reference to FIG. As shown in FIG. 6, the second conductive material, poppy bridges between a plurality of VB 2 _/ metal composite particles adjacent to or near, the role of promoting electron transfer between a plurality of VB 2 _/ metal composite particles Have The first conductive material exists so as to fill the space between and around the VB ₂ / metal composite particles bridged by the second conductive material, and between the VB ₂ / metal composite particles or VB ₂ / It has a role of promoting electron transfer between the metal composite particles and the second conductive material. Electronic This detailed mechanism is not clear, the present inventors have a first conductive material and the second conductive material that used with VB 2 _/ metal complex, generated by the discharge reaction of VB 2 _/ metal complex It is speculated that the movement of electrons will be promoted because a network or channel will flow through. Thus, the first conductive material and the second conductive material have a role as a conductive auxiliary agent that assists the conductivity of the VB ₂ / metal composite as the negative electrode active material. The first conductive material and the second conductive material also have a role of assisting the action of a binder described later, that is, helping the binding between the VB ₂ / metal composite particles.

As described above, the second conductive material mainly has a role of bridging between a plurality of adjacent or adjacent VB ₂ / metal composite particles, and thus, at least two adjacent or adjacent VB ₂ / metal composites are used. to reach the particle, VB 2 _/ metal composite particle radius of 2 times or more, i.e., it is necessary to have an average length on the mean particle size or less of the VB 2 _/ metal composite particles. Here, the “average length” of the second conductive material means a one-dimensional length including the length, width, height, diameter (long diameter in the case of an ellipse), etc. of the second conductive material (particles). The number average length divided by the number of particles of the second conductive material is represented. In the present embodiment, the number average value of parameters indicating at least the maximum length among the length, width, height, diameter (long diameter if elliptical) of the second conductive material (particle) is VB ₂ / What is necessary is just to be more than the average particle diameter of metal composite particles. In order to more reliably bridge between the VB ₂ / metal composite particles, the average length of the second conductive material may be 1.5 times or more the average particle diameter of the VB ₂ / metal composite particles. Preferably, it is 2 times or more. On the other hand, if the second conductive material is too large, the binding force with the VB ₂ / metal composite particles and the second conductive material is reduced, so the average length of the second conductive material is VB ₂ / metal composite particles. The average particle diameter is preferably 50 times or less. In addition, as an average length of the second conductive material, an arbitrary 100 particles are photographed with a scanning electron microscope, and the particle size of the 100 particles is measured by image analysis of the photographed images. The average value is used.

The substance that can also be used as the second conductive material is not particularly limited as long as it has conductivity. For example, the conductive material such as aluminum, stainless steel, nickel, chromium, gold, platinum, silver, copper, etc. Metal having excellent resistance, conductive carbon such as carbon black (furnace black, channel black, acetylene black, thermal black, etc.), graphene, graphite, carbon nanotube, carbon nanohorn, and the like can be used. Among these, it is preferable to use conductive carbon rather than metal from the viewpoint of increasing the binding force of the VB ₂ / metal composite particles or reducing the internal resistance. Furthermore, since the VB ₂ / metal composite particles have a shape suitable for bridging, it is particularly preferable to use particles having a large aspect ratio such as graphene, carbon nanotubes, and carbon nanohorns.

In addition, since the first conductive material mainly has a role of filling the space between and around the VB ₂ / metal composite particles bridged by the second conductive material, the VB ₂ / metal composite particles It is necessary to have an average particle size that is less than the average particle size of the VB ₂ / metal composite particles so as to be able to intervene. In order to increase the binding force between the first conductive material and the VB ₂ / metal composite particles, it is better that the particle diameter of the first conductive material is small. Specifically, the average particle diameter may be 5 μm or less. Preferably, it is 1 μm or less. On the other hand, if the particle diameter of the first conductive material is too small, the workability during formation of the negative electrode active material layer 112 is reduced, so the average particle diameter is preferably 0.1 μm or more, and is 0.3 μm or more. More preferably. In addition, as an average particle diameter of the first conductive material, an arbitrary 100 particles are photographed with a scanning electron microscope, and the particle diameter of the 100 particles is measured by image analysis of the photographed photographs. The average value is used.

The substance that can also be used as the first conductive material is not particularly limited as long as it has conductivity like the second conductive material. For example, aluminum, stainless steel, nickel, chromium, gold, platinum Metals having excellent conductivity such as silver and copper, and conductive carbon such as carbon black (furnace black, channel black, acetylene black, thermal black, etc.), graphene, graphite, carbon nanotube, and carbon nanohorn can be used. Among these, it is preferable to use conductive carbon rather than metal from the viewpoint of increasing the binding force of the VB ₂ / metal composite particles or reducing the internal resistance. Furthermore, since the shape is suitable for filling the space between and around the VB ₂ / metal composite particles bridged by the second conductive material, the aspect ratio of carbon black or the like is close to 1 (spherical) It is particularly preferred to use (close) particles. Among carbon blacks, acetylene black is preferably used because of its particularly high conductivity.

  Further, conductive carbon such as graphene is used as the second conductive material, conductive carbon such as carbon black is used as the first conductive material, and conductive carbon such as graphite is used as the material of the negative electrode current collector 111 described above. When used, since the negative electrode current collector 111 and the negative electrode active material layer 112 both contain carbon, as described above, both have the same thermal expansion coefficient. Even when the temperature in 100 increases, the formation of a gap between the negative electrode current collector 111 and the negative electrode active material layer 112 is suppressed, or the negative electrode active material layer 112 is hardly peeled from the negative electrode current collector 111. You can do it.

  Note that if both the first conductive material and the second conductive material are not necessarily included, the effect of improving the conductivity cannot be obtained. If at least the first conductive material is included, the conductivity is improved. An effect is obtained.

[Binder]
The negative electrode active material layer 112 also includes a binder for binding the above-described VB ₂ / metal composite, the first conductive material, and the second conductive material. The kind of this binder is not specifically limited, The well-known binder used for manufacture of an active material layer can be used. As the binder according to the present embodiment, for example, polytetrafluoroethylene (PTFE), polyvinylpyrrolidone (PVP), or the like can be used. For example, when an aqueous solution such as KOH is used as the electrolyte, it is preferable not to use a water-soluble material or a material with low alkali resistance as the binder.

[Other ingredients]
In addition, the negative electrode active material layer 112 can contain known components that can be used as negative electrode materials for air batteries, fuel cells, and other secondary batteries.

[Dispersed state of each particle]
In the present embodiment, it is preferable that the VB ₂ / metal composite particles, the first conductive material, and the second conductive material are uniformly dispersed. Accordingly, since the contact point with the VB 2 _/ metal composite particles and the first and second conductive material is increased, the effect of promoting electron transfer increases, thereby increasing the conductivity. In order to obtain a uniformly dispersed state, a slurry containing VB ₂ / metal composite particles, the first conductive material, and the second conductive material is dispersed using a machine having a stirring function such as a bead mill, a ball meal, or an ultrasonic wave. It is desirable to process.

[Content of each component]
The content of the first conductive material in the negative electrode active material layer 112 is preferably 0.5 parts by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the VB ₂ / metal composite. If the content of the first conductive material is less than 0.5 parts by mass, the effect of promoting electron transfer is insufficient, and sufficient conductivity cannot be obtained. As a result, the discharge capacity of the air battery cell 100 becomes insufficient. There is a risk that. If the content of the first conductive material exceeds 50 parts by mass, the dispersibility of the conductive auxiliary agent is deteriorated, or the binding force between the VB ₂ / metal composite and the conductive auxiliary agent due to the binder is decreased. As a result of not being able to obtain sufficient conductivity, the discharge capacity of the air battery cell 100 may be insufficient. Further, since the VB ₂ / metal composite cannot be sufficiently contained, the energy density is lowered, and as a result, the discharge capacity of the air battery cell 100 may be insufficient. More preferably, the content of the first conductive material in the negative electrode active material layer 112 is 3 parts by mass or more and 15 parts by mass or less with respect to 100 parts by mass of the VB ₂ / metal composite, or the negative electrode active material layer The content rate of the 1st electrically-conductive material in 112 is 3-15 mass%.

When the second conductive material is included in the negative electrode active material layer 112, the content of the second conductive material is 0.1 parts by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the VB ₂ / metal composite. Preferably, it is 0.1 to 10 parts by mass. If the content of the second conductive material is less than 0.1 parts by mass, the effect of promoting electron transfer is insufficient, and sufficient conductivity cannot be obtained. As a result, the discharge capacity of the air battery cell 100 becomes insufficient. There is a risk that. If the content of the second conductive material exceeds 50 parts by mass, the dispersibility of the conductive auxiliary agent will deteriorate, or the binding force between the VB ₂ / metal composite and the conductive auxiliary agent due to the binder will decrease. As a result of not being able to obtain sufficient conductivity, the discharge capacity of the air battery cell 100 may be insufficient. Further, since the VB ₂ / metal composite cannot be sufficiently contained, the energy density is lowered, and as a result, the discharge capacity of the air battery cell 100 may be insufficient. More preferably, the content of the second conductive material in the negative electrode active material layer 112 is 0.2 parts by mass or more and 5 parts by mass or less with respect to 100 parts by mass of the VB ₂ / metal composite, or the negative electrode active material The content rate of the 2nd conductive material in the material layer 112 is 0.2-5 mass%.

  In the case where the negative electrode active material layer 112 includes both the first conductive material and the second conductive material, the mass ratio between the first conductive material and the second conductive material (the mass of the first conductive material / the mass of the second conductive material). ) Is preferably 3 or more and 50 or less, and more preferably 5 or more and 20 or less. If the mass ratio is less than 3, it is not preferable because a network of long-fiber conductive assistants cannot be sufficiently formed, and even if it exceeds 50, the conductivity does not change, which is not preferable from the viewpoint of economy.

Further, the binder content in the negative electrode active material layer 112 may be appropriately determined according to the contents of the VB ₂ / metal composite and the conductive auxiliary. For example, the binder is other than the VB ₂ / metal composite and the conductive auxiliary. (The total content of VB ₂ / metal composite, conductive additive and binder in the negative electrode active material layer 112 is 100 mass%).

(Electrode side negative terminal 113, Cell side negative terminal 114)
In addition to the negative electrode current collector 111 and the negative electrode active material layer 112 described above, the negative electrode 110 further includes an electrode-side negative electrode terminal 113 and a cell-side negative electrode terminal 114. The electrode-side negative electrode terminal 113 includes a main body portion 113a attached to the negative electrode current collector 111 and a terminal portion 113b connected to the main body portion 113a. The main body portion 113a has a substantially rectangular plate shape, and a side portion on one side thereof is fixed to the negative electrode current collector 111 with a screw 115 or the like. In addition, an elongated plate-like terminal portion 113b is continuously provided so as to protrude from a side portion different from the side fixed to the current collecting portion 111 of the main body portion 113a. The terminal portion 113b is electrically connected to the cell-side negative electrode terminal 114 via the terminal support member 116.

  The cell-side negative electrode terminal 114 includes a terminal receiving portion 114a and a terminal portion 114b. A terminal support member 116 is fixed to the terminal receiving portion 114a. The terminal support member 116 has a notch 116a formed on the upper surface side, and the terminal portion 113b of the electrode-side negative terminal 113 is fitted into the notch 116a of the terminal support member 116 fixed to the terminal receiving portion 114a. At this time, since the electrode-side negative terminal 113, the cell-side negative terminal 114, and the terminal support member 116 are all made of a conductive material such as metal, the electrode-side negative terminal 113 and the cell-side negative terminal 114 are electrically connected. Is done.

  The terminal portion 114b of the cell-side negative electrode terminal 114 is inserted into a through hole 102c provided on one side of the housing frame 102, and is fixed to the housing frame 102 by a washer, a nut, or the like (both not shown). .

  In this embodiment, in order to reliably connect the electrode-side negative terminal 113 and the cell-side negative terminal 114, a notch 116a having a width substantially the same as the thickness of the terminal portion 113b of the electrode-side negative terminal 113 is formed. Although the terminal support member 116 is used, the terminal support member 116 may not be used if the above-described reliable electrical connection is possible.

(Negative electrode 120)
Here, the negative electrode according to the present embodiment includes not only the configuration of the negative electrode 110 having the negative electrode current collector 111 in which the plurality of groove portions 111a described above are formed, but also a plurality of, for example, as shown in FIG. A configuration like the negative electrode 120 having the current collector 121 in which the recesses 121a are arranged in a grid pattern may be used. Note that in FIG. 7, the negative electrode active material layer is not shown for easy understanding of the shape of the current collector 121. What is necessary is just to provide the negative electrode active material layer in the negative electrode 120 which concerns on this example in each recessed part 121a.

  The negative electrode 120 includes two current collectors 121A and 121B having a substantially rectangular plate shape (hereinafter, the current collectors 121A and 121B may be collectively referred to as “current collector 121”), and the spacer 122 is provided. It has a sandwiching structure. With such a configuration, it is only necessary to form the recess 121a only on one surface of the current collector 121, and thus the negative electrode 120 (particularly, the current collector 121) can be easily processed.

[Current collector 121]
Since the material of the current collector 121 is the same as that of the negative electrode current collector 111 described above, the shape of the current collector 121 will be described. A plurality of recesses 121 a are provided on one surface of the current collector 121. Each recess 121 a is provided in a grid pattern on the surface of the current collector 121, and the plurality of recesses 121 a are arranged along the longitudinal direction and the width direction of the current collector 121. Moreover, the partition 121b is provided between the adjacent recessed parts 121a so that each recessed part 121a may be arrange | positioned mutually spaced apart. In the negative electrode 110 described above, the partition walls 111b are provided along two opposite sides of each groove 111a. However, the partition walls 121b in the negative electrode 120 are provided so as to surround the four sides of the substantially rectangular recess 121a. Yes. Further, the width of the partition wall 121b is not particularly limited as long as the concave portions 121a are physically separated.

[Spacer 122]
The spacer 122 is a substantially rectangular member sandwiched between two current collectors 121. As a material of the spacer 122, a conductive material such as metal or conductive carbon is used in order to transmit electrons generated by the discharge reaction of VB ₂ as a negative electrode active material to the positive electrode 130. In addition, an electrode-side negative terminal 123 connected to the cell-side negative terminal 114 is connected to one vertex of the spacer 122. The electrode-side negative terminal 123 is formed of the same or different conductive material as the spacer 122, has substantially the same shape as the electrode-side negative terminal 113, and is fitted into the notch 116a of the terminal support member 116.

(Discharge area)
In the negative electrode 110 according to the present embodiment, the negative electrode active material layer 112 including the VB ₂ / metal composite, the first conductive material, and the second conductive material is a discharge region according to the present embodiment. In this case, the plurality of grooves 111a provided with the negative electrode active material layer 112 function as a plurality of discharge cells separated from each other, and the partition 111b functions as a partition provided between adjacent discharge cells. As described above, the discharge region (the negative electrode active material layer 112) is divided into a plurality of (physically) separated states by the barrier ribs provided between adjacent discharge cells. That is, in each discharge cell, a negative electrode active material layer 112 including a VB ₂ / metal composite, a first conductive material, and a second conductive material is provided as a discharge region. Similarly, in the negative electrode 120 according to the modified example of the present embodiment, a negative electrode active material layer (not shown) including the VB ₂ / metal composite, the first conductive material, and the second conductive material is used in the present embodiment. This is the discharge region. In this case, the plurality of recesses 121a provided with the negative electrode active material layer function as a plurality of discharge cells separated from each other, and the partition 121b functions as a partition provided between adjacent discharge cells. Thus, also in the negative electrode 120 according to the modified example, the discharge region (negative electrode active material layer) is divided into a plurality of (physically) separated states by the partition provided between adjacent discharge cells. . Note that the number of discharge regions may be adjusted as appropriate according to the entire area of the current collector (in this embodiment, the negative electrode current collectors 111 and 121) (the area of the front surface or the back surface).

  Here, as a general current collector, a plate-like one having a flat surface or a net (lattice) -like one is used. However, in the case of a plate having a flat surface, if a part of the flat surface is corroded by an electrolytic solution or the active material is not uniformly applied to the current collector, an internal local discharge occurs. There is a problem that the discharge efficiency is lowered. In the case of a net-like structure, a net-like current collector is collected when the negative electrode active material jumps out of the mesh gap due to volume expansion due to the reaction of the negative electrode active material (for example, zinc) or a part of the net is corroded. As a result of the negative electrode active material peeling off from the body, there is a problem that the discharge efficiency is lowered.

Therefore, in order to suppress the problems as described above, the negative electrode 110 according to the present embodiment and the negative electrode 120 according to the modified example have the VB ₂ / metal composite, the first conductive material, and the second conductive as described above. The discharge region including the material has a structure that is divided into a plurality of parts in a state of being separated from each other. With such a structure, the current collector surrounds the periphery of the negative electrode active material layer (a total of three surfaces including two side surfaces and a bottom surface in the negative electrode 110 and a total of five surfaces including four side surfaces and a bottom surface in the negative electrode 120). Therefore, the negative electrode active material (VB ₂ / metal composite) and the current collector are easily in contact with each other, and electron transfer is promoted. In addition, since the discharge region, that is, the negative electrode active material layer is divided into a plurality of regions, the reaction site of the active material is a total of five surfaces including the surface of the negative electrode active material layer and the four side surfaces. growing. Accordingly, the discharge efficiency is improved.

  In addition, since there are a plurality of discharge cells, some of the discharge cells may malfunction (for example, the negative electrode current collector 111 and the negative electrode active material layer 112 may be corroded due to corrosion of the negative electrode current collector 111 or generation of reaction heat). Even if the internal resistance of the battery increases due to peeling, etc.), each discharge area is physically separated and the fuel reaction occurs independently in each discharge area. In such a discharge cell, normal operation (discharge reaction) is ensured, and the influence of the defective discharge cell hardly occurs. Therefore, by using the negative electrodes 110 and 120 according to the present embodiment, the stability of the operation of the entire battery is improved, and as a result, the discharge capacity close to the theoretical value can be obtained.

(Removal of negative electrode 110)
As described above, the negative electrode 110 (negative electrode 120) according to the present embodiment is housed inside the housing 101, but is detachably attached to the air battery cell 100. As a result, even if the VB ₂ / metal composite that is the negative electrode active material (fuel) of the negative electrode 110 is consumed (oxidized) by the discharge reaction, the negative electrode 110 is taken out of the housing 101 and the oxidized VB _{2 and the} like are reduced. Thus, it becomes possible to regenerate the negative electrode active material (fuel) VB ₂ or the like, or to replace the negative electrode 110 itself.

[Positive electrode 130]
The positive electrode 130 is an electrode that functions as an oxygen electrode of the air battery cell 100 (an electrode using oxygen as a positive electrode active material). For example, as shown in FIG. 4, the surface side of the negative electrode 110 accommodated in the housing 101 is used. The positive electrode 130 </ b> A and the positive electrode 130 </ b> B (hereinafter may be collectively referred to as “positive electrode 130”) are disposed on the back surface side. Each of the positive electrodes 130 </ b> A and 130 </ b> B mainly includes a positive electrode current collector 132, a water repellent oxygen permeable sheet 133, and a catalyst layer 134. The outer sides (the outermost surface side and the rear surface side) of the two negative electrodes 130A and 130B are covered with a front surface cover 103 and a rear surface cover 104, respectively.

(Positive electrode current collector 132)
The positive electrode current collector 132 is a substantially rectangular frame-shaped member, and has an opening 132a at a substantially central portion (inside the frame). After the air battery cell 100 is assembled, the water repellent oxygen permeable sheet 133 is located in the opening 132a. Further, in one air battery cell 100, two positive electrode current collectors 132 are provided for each of the positive electrode 130A and the positive electrode 130B, corresponding to the two negative electrodes 110.

  The positive electrode current collector 132 has a role of supplying electrons to oxygen which is a positive electrode active material. The material of the positive electrode current collector 132 is not particularly limited as long as it is a conductive material. For example, conductive materials such as aluminum, stainless steel, nickel, chromium, gold, platinum, silver, and copper are used. And conductive carbon such as carbon black (furnace black, channel black, acetylene black, thermal black, etc.), graphene, graphite, carbon nanotube, carbon nanohorn, etc. can be used. Among these, it is preferable to use stainless steel as the positive electrode current collector 132, and it is more preferable to use SUS304 plated with nickel.

  A positive electrode terminal 137 is provided at a substantially central portion of the long side portion of the positive electrode current collector 132. The positive electrode terminal 137 is inserted into a through hole 102d provided in a substantially central portion of one side of the housing frame 102 (below the above-described through hole 102c in the example shown in FIG. 4), and isher, nut, etc. (Not shown). In the example shown in FIG. 4, one positive electrode terminal 137 is provided for each of the positive electrode current collector 132 of the positive electrode 130A and the positive electrode current collector 132 of the positive electrode 131B (in the positive electrode 130A, the positive electrode current collector 132 is provided). (It is provided on the long side portion on the back side of the electric body 132 in the drawing, and is provided on the long side portion on the near side in the drawing of the positive electrode current collector 132 in the positive electrode 130B). However, it is sufficient that two positive terminals 137 are provided for both of the positive electrodes 130A and 130B. For example, the positive terminals 137 are provided on both the front side and the rear side of the positive electrode current collector 132 of the positive electrode 130A. The positive electrode current collector 132 of the positive electrode 130B may not be provided with the positive electrode terminal 137.

(Water repellent oxygen permeable sheet 133)
The water-repellent oxygen permeable sheet 133 has a function as an oxygen intake portion that becomes a channel of air (oxygen) when air (oxygen) outside the air battery cell 100 is taken into the air battery cell 100, and the housing 101. When the electrolyte 150 filled therein is an electrolytic solution such as a KOH aqueous solution, it has a function as an electrolytic solution leakage prevention unit that prevents leakage of the electrolytic solution to the outside. In order to realize such a function, the water-repellent oxygen permeable sheet 133 has water repellency and does not allow electrolyte solution or hydroxide ions present in the solution to pass but allows air (oxygen) to pass. A porous material having a certain degree of voids and pores is used. The amount of oxygen supplied into the air battery cell 100 can be adjusted by the porosity of the water repellent oxygen permeable sheet 133. The porosity may be determined so that a necessary amount of oxygen can be appropriately supplied according to the use of the air battery cell 100, but the porosity is preferably 30% or more and 95% or less. Specifically, for example, depending on the use of the air battery cell 100, it can be 30% or more and 50% or less, or 70% or more and 95% or less.

  Here, examples of the material having water repellency (hereinafter referred to as “water-repellent material”) include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), and the like. In order to prevent collapse of a catalyst layer 134 (a powder sheet) described later, it is preferable to apply polyvinyl alcohol (PVA) or the like to the water repellent oxygen permeable sheet 133.

  In the present embodiment, the water repellent oxygen permeable sheet 133 may contain conductive carbon in order to enhance conductivity in addition to a water repellent material such as PTFE. Here, the blending ratio of the water-repellent material and the conductive carbon is such that if there is too much water-repellent material, the permeability of air (oxygen) will decrease, and if there is too much conductive carbon, the electrolyte may leak out. Therefore, the blending ratio of the two may be determined in consideration of the balance between water repellency and oxygen permeability.

  Furthermore, the water-repellent oxygen permeable sheet 133 according to this embodiment may contain activated carbon. Since the activated carbon has both oxygen reduction ability and conductivity, it has a role as a discharge reaction catalyst and a conductive material in the positive electrode 130.

  Note that the water-repellent oxygen permeable sheet 133 according to the present embodiment uses a water-repellent material such as PTFE because the electrolyte does not leak out of the air battery cell 100 when the electrolyte 150 is an electrolyte. For this reason, when a gel or solid electrolyte is used, the function as an electrolyte leakage preventing portion is unnecessary, and it is not necessary to use a water repellent material such as PTFE. In this case, a polymer material having a predetermined porosity can be used in place of the water-repellent material, as long as it has at least a function as an oxygen intake portion. Examples of such a polymer material include polyvinylidene fluoride (PVDF).

  The water-repellent oxygen permeable sheet 133 is installed so as to be positioned in the opening 132a of the positive electrode current collector 132. After the air battery cell 100 is assembled, the opening 103a and the back cover of the front cover 103 of the housing 101 are assembled. The shape is exposed to the outside from the opening 104 a of 104.

(Catalyst layer 134)
The catalyst layer 134 is a layer having a catalyst (oxygen reducing agent) that causes oxygen in the air taken into the air battery cell 100 from the water-repellent oxygen permeable sheet 133 to react. It is formed by holding the holding body 135 in layers. Although not shown, the catalyst holding body 135 has a predetermined opening so that air taken in from the water-repellent oxygen permeable sheet 133 can pass therethrough. Although the specific shape is not particularly limited, for example, the catalyst holding body 135 has a net shape. In addition, the catalyst holder 135 is preferably formed of a conductive material so that electrons generated in the catalyst layer 134 are transmitted.

  Further, the catalyst layer 134 reduces oxygen in the air taken in from the water-repellent oxygen permeable sheet 133 and generates electrons. The generated electrons are transmitted in the order of the catalyst holder 135, the positive electrode current collector 132, and the positive electrode terminal 137, reach the negative electrode 110 through the cell-side negative electrode terminal 114 connected to the positive electrode terminal 137, and discharge at the negative electrode 110. Used for reaction. Further, the catalyst layer 134 has a mesh structure so that air taken in from the water repellent oxygen permeable sheet 133 can pass therethrough.

The catalyst is not particularly limited as long as it can reduce oxygen. For example, manganese dioxide (MnO ₂ ), zinc oxide (ZnO ₂ ), vanadium oxide (V ₂ O ₅ ), platinum (Pt), or the like is used. be able to.

  Further, when the electrolyte 150 is an electrolytic solution, the catalyst layer 134 is made of a water repellent material such as PTFE in order to make the catalyst layer 134 water repellent and prevent the electrolyte solution from leaking more effectively. May be included. In this case, for example, the water repellent material is used in the form of powder, and the powder and catalyst powder that are kneaded and solidified may be used as the catalyst layer 134.

[Electrolyte 150]
The electrolyte 150 has a role of conducting hydroxide ions between the negative electrode 110 and the positive electrode 130. The electrolyte 150 may be any one that can conduct hydroxide ions. Examples of the electrolyte 150 include aqueous electrolytes (for example, alkaline aqueous solutions such as an aqueous potassium hydroxide solution, an aqueous lithium hydroxide solution, and an aqueous sodium hydroxide solution), non-aqueous electrolysis. Liquids (for example, strong alkaline alcohol solutions), solid electrolytes (for example, metal oxides), and known electrolytes can be used without particular limitation. However, in the case of a liquid electrolyte (electrolytic solution), there is a problem of liquid leakage, and the electrolytic solution such as an aqueous potassium hydroxide solution has a high temperature dependency, so that the voltage depends on the operating temperature of the air battery cell 100. There is also the problem of fluctuating. Therefore, it is preferable to use a solid electrolyte from the viewpoint of preventing such a problem.

[Separator 160]
When the electrolyte 150 described above is an aqueous or non-aqueous electrolyte, the air battery cell 100 further includes a separator 160 that electrically insulates the negative electrode 110 and the positive electrode 130 from each other. When the electrolyte 150 is a solid electrolyte, the air battery cell 100 may or may not include the separator 160.

The separator 160 needs to be formed of an insulator capable of electrically insulating the negative electrode 110 and the positive electrode 130 in order to prevent a short circuit due to contact between the negative electrode 110 and the positive electrode 130. Further, the separator 160 does not transmit VB ₂ dissolved so as not to release the VB ₂ eluted in the electrolytic solution (electrolyte 150) to the outside of the separator 160, and hydroxide ions generated at the positive electrode 130 are not allowed to pass through the electrolyte 150. In order to transmit to the negative electrode 110 through, it is made of a material that transmits hydroxide ions. Furthermore, the separator 160 is formed of a material that can be impregnated with the electrolytic solution (electrolyte 150), so that the amount of the electrolytic solution in the separator 160 is suppressed in order to suppress the elution of VB ₂ from the negative electrode 110 into the electrolytic solution. Even if the amount is reduced, the negative electrode 110 can receive hydroxide ions through the electrolytic solution impregnated in the separator 160. In the present embodiment, since the VB ₂ particles are covered with the inclusion metal, the problem of elution of VB _{2 into} the electrolytic solution hardly occurs.

  As a material of the separator 160 for realizing the function of the separator 160 as described above, for example, vinylon, cellulose, rayon, polyvinyl alcohol (PVA), or the like can be used alone or in combination.

Further, as described above, since the separator 160 needs to have hydroxide ion permeability, a porous material having a predetermined pore diameter is used for the separator 160. preferable. If the pore diameter is too large, VB ₂ eluted in the electrolyte (electrolyte) 150 may leak out of the separator 160. If the pore diameter is too small, the hydroxide ions cannot permeate. It is preferable to make it a large size. For example, if it has a pore diameter of approximately 10 μm, VB ₂ eluted into the electrolyte (electrolytic solution) 150 does not leak and allows hydroxide ions to permeate.

[Other Examples of Connection Method of Negative Electrode 110 and Positive Electrode 130]
Next, a modified example of the connection method between the negative electrode 110 and the positive electrode 130 according to the present embodiment will be described with reference to FIG. FIG. 8 is a perspective view showing a method for connecting the negative electrode 110 and the positive electrode 130 according to another modification of the present embodiment.

  In the example described above, the negative electrode 110 and the positive electrode 130 in one air battery cell 100 are not electrically connected. On the other hand, as shown in FIG. 8, the negative electrode 110 and the positive electrode 130 in one air battery cell 100 may be connected in series to increase the output voltage per unit cell of the air battery cell 100. In this case, of the two negative electrodes 110 (110A, 110B) housed in the air battery cell 100, the electrode-side negative terminal 113b (110A) of one negative electrode 110A is connected to the positive electrode current collector 132 of the adjacent positive electrode 130B. By contact, negative electrode 110A and positive electrode 130B are connected in series. Further, the electrode-side negative electrode terminal 113b (110B) of the other negative electrode 110B is connected to one end of the linear negative electrode harness 117 via the negative electrode harness terminal 118A, and the other end of the negative electrode harness 117 is connected via the negative electrode harness terminal 118B. Are connected to the cell-side negative electrode terminal 119. The negative harness 117 is provided for withstand voltage by serially connecting the negative electrode 110 and the positive electrode 130. Further, the cell-side negative terminal 119 has a function similar to that of the cell-side negative terminal 114 described above.

<Method for Manufacturing Air Battery Cell 100>
The configuration of the air battery cell 100 according to the present embodiment has been described in detail above. Subsequently, the manufacture of the air battery cell 100 having the above-described configuration with reference to FIGS. 3, 4, 9, and 10. The method will be described in detail. FIG. 9 is an explanatory diagram showing a method for manufacturing the negative electrode 110 according to the present embodiment, and FIG. 10 is a schematic diagram showing a configuration of a VB ₂ / metal composite manufacturing apparatus according to the present embodiment.

[Manufacture of Negative Electrode 110]
First, the manufacturing process of the negative electrode 110 will be described. First, as shown in FIG. 9A, the material of the negative electrode active material layer 112 described above, that is, a VB ₂ / metal composite and a binder having a predetermined blending ratio (if necessary, a first conductive material, a first conductive material, 2 conductive materials and other additives), and as shown in FIG. 9B, a slurry of the negative electrode active material (active material slurry) is produced.

Here, the manufacturing process of the VB ₂ / metal composite will be described in detail. In advance, VB ₂ particles are added to a conductive carbon dispersion containing conductive carbon such as CNT at a predetermined concentration, and then gently stirred. The obtained slurry containing VB ₂ and conductive carbon can be processed by a spray drying method or the like to obtain VB ₂ particles (for example, VB ₂ / CNT particles) encapsulated with conductive carbon such as CNT. Next, the VB ₂ particles encapsulated with the conductive carbon are mixed with the encapsulated metal powder in a predetermined compounding ratio and pressed to obtain a VB ₂ / metal composite having a predetermined shape (for example, a cylindrical shape). Furthermore, in order to make this composite into a particulate form, a composite manufacturing apparatus 500 shown in FIG. 10 is used.

Specifically, first, a predetermined shape (non-particulate) VB ₂ / metal composite prepared as described above is charged into the melting furnace 502 in the melting chamber 501, and only the inclusion metal melts. Heat to. Then, in the melting furnace 502, VB ₂ particles encapsulated with conductive carbon are present in the molten encapsulated metal. Here, for example, CNT, graphene, carbon black, etc. is used as the conductive carbon, because in the case of using Zn as inclusion metal has a specific gravity towards the _VB 2 / CNT particles is smaller than _Zn, VB 2 / CNT The particles are in a state of floating above the molten Zn. Next, when the floating VB ₂ / CNT particles are moved to the crucible 503 in this way, the crucible 503 is filled with VB ₂ / CNT particles having molten Zn adhered to the surface.

Further, VB ₂ / CNT particles having molten Zn adhered to the surface are sprayed from the nozzle 505 toward the spray chamber 507. The amount of VB ₂ / CNT particles ejected from the nozzle 505 is the gas supplied from the high pressure air supply device 511 by the pressure regulating valve 509 (this gas is preferably an inert gas such as nitrogen or argon). .)) By adjusting the flow rate. In this way, when the VB ₂ / CNT particles are ejected from the nozzle 505, the molten Zn adhering to the surface of the VB ₂ / CNT particles is naturally cooled in the spray chamber 507 until it falls to the powder collector 513. During this time, the Zn solidifies, and the VB ₂ / metal composite particles in which the surfaces of the VB ₂ / CNT particles are included by the inclusion metal such as Zn are collected by the powder collector 513.

Finally, among the VB ₂ / metal composite particles collected by the powder collector 513, those having a particle size equal to or smaller than a predetermined particle size are transferred to the cyclone separator 515 (VB ₂ / metal composite particles having a particle size that is too large are collected by powder In the cyclone separator 515, the predetermined particle size or less (the particle size is too small) is removed out of the complex manufacturing apparatus 500 and has an appropriate particle size. Only things are collected in the fine powder collector 517. In this manner, the VB ₂ / metal composite particles collected by the fine powder collector 517 are used as the negative electrode active material.

  Next, the active material slurry produced as described above is applied (cast) to the groove 111a of the negative electrode current collector 111 as shown in FIG. Although it does not restrict | limit especially as a coating method, For example, methods, such as a brush coating, the method using an applicator, and a press, can be used. Further, by vibrating the active material slurry during coating, the negative electrode active material can be stabilized on the negative electrode current collector 111. In other words, the negative electrode active material can be applied uniformly and without gaps to the groove 111a. Become. In addition, as a method of vibrating an active material slurry, the method using a shaker (vibrator) is mentioned, for example. Finally, by drying the active material slurry applied to the groove 111a of the negative electrode current collector 111, the active material slurry adheres firmly to the negative electrode current collector 111 and solidifies, as shown in FIG. 9 (d). As described above, the negative electrode active material layer 112 is formed in the groove 111 a of the negative electrode current collector 111. The drying method at this time is not particularly limited. For example, the drying method may be left for a predetermined time at room temperature and dried for a long time, or may be dried in a short time using a known heating drying furnace. As described above, the negative electrode 110 can be manufactured.

  In the case where the negative electrode active material layer 112 is provided on both surfaces of the negative electrode current collector 111, the active material slurry is uniformly applied to the groove portion 111a without unevenness. It is preferable to apply an active material slurry to the other surface after the treatment.

[Manufacture of positive electrode 130]
Next, the manufacturing process of the positive electrode 130 will be described. First, a material for forming the catalyst layer 134, that is, a catalyst having a function of reducing oxygen (for example, MnO ₂ ) is an essential component, and an additive such as a water repellent material (for example, PTFE) is added as necessary. Prepare and knead these powders to make the catalyst layer material. Next, the catalyst layer 134 is formed on the surface of the catalyst holding body 135 by holding the catalyst layer material on the surface of the catalyst holding body 135. The catalyst layer 134 may be formed on both surfaces of the catalyst holding body 135 or only on one surface.

  Next, the above-described water-repellent oxygen permeable sheet 133 is attached to one surface of the catalyst holder 135 on which the catalyst layer 134 is formed. When a solid electrolyte is used as the electrolyte 150, an oxygen permeable sheet (not shown) having no water repellency may be used instead of the water repellent oxygen permeable sheet 133. Furthermore, the positive electrode 130 can be manufactured by fixing the catalyst holding body 135 holding the water-repellent oxygen permeable sheet 133 and the catalyst layer 134 to the positive electrode current collector 132.

  In the present embodiment, a total of four positive electrodes 130 are manufactured, two for installation on the front side of the casing 101 and two for installation on the back side.

[Manufacture of air battery cell 100]
Next, a process for manufacturing the air battery cell 100 using the negative electrode 110 and the positive electrode 130 manufactured as described above will be described. First, as shown in FIG. 4, the terminal portion 114b of the cell-side negative electrode terminal 114 of the negative electrode 110 is inserted into the through hole 102c of the housing frame 102, and is fixed by a washer, a nut, or the like (not shown). Next, two positive electrodes 130 are fitted into the front surface side and the back surface side of the opening 102a of the frame 102, respectively. At this time, the positive electrode terminal 137 is inserted into the through hole 102d and fixed by a washer, a nut, or the like (not shown). Further, the front cover 103 and the rear cover 104 are fixed to the housing frame 102 so as to cover the outer surface of the positive electrode 130, whereby the housing 101 in which the positive electrode 130 is installed is obtained. At this time, a space (gap) for housing the negative electrode 110 exists inside the housing 101.

  Subsequently, as shown in FIGS. 3 and 4, the terminal support member 116 is installed in the terminal receiving portion 114 a of the cell-side negative electrode terminal 114. Further, in the separator 160, the periphery of the negative electrode current collector 111 and the negative electrode active material layer 112 of the negative electrode 110 is covered with a bag-shaped separator 160 (the electrode-side negative electrode terminal 113 portion is not covered with the separator 160). The negative electrode 110 is accommodated. Next, the negative electrode 110 whose periphery is covered with the separator 160 is accommodated in the housing 101 through the opening 101a in which the positive electrode 130 is installed. At this time, the terminal portion 113 b of the electrode-side negative terminal 113 is fitted with the notch 116 a of the terminal support member 116.

  Subsequently, an electrolyte 150 is filled in the housing 101 in which the positive electrode 130 and the negative electrode 110 are installed. Furthermore, the air battery cell 100 can be manufactured by sealing the opening 101 a of the housing 101 with the cap 105.

<Configuration of Air Battery Unit 10>
Next, a configuration of the air battery unit 10 in which a plurality of the air battery cells 100 described above are connected will be described with reference to FIGS. 11 and 12. FIG. 11 is a perspective view showing the overall configuration of the air battery unit 10 according to the present embodiment. 12 is a plan view of the air battery unit shown in FIG. 11, wherein (a) is a top view, (b) is a front view, (c) is a left side view, and (d) is a right side view. Yes.

(overall structure)
As shown in FIGS. 11 and 12, the air battery unit 10 includes a plurality of the air battery cells 100 described above. In the example shown in FIG.11 and FIG.12, although the example which connected five air battery cell 100A, 100B, 100C, 100D, 100E is described, it does not restrict | limit especially regarding the number of the air battery cells 100. FIG. Absent. Moreover, although the example shown in FIG.11 and FIG.12 has shown the example in which the several air battery cell 100 was connected in series, the connection method may be either serial or parallel.

  In the air battery unit 10 according to the present embodiment, the negative electrode 110 and the positive electrode 130 of the adjacent air battery cells 100 are connected by the bus bar 11. More specifically, the bus bar 11 connects, for example, the positive electrode terminal 137 of the air battery cell 100A and the cell-side negative electrode terminal 114 of the air battery cell 100B adjacent to the air battery cell 100A. One end of the bus bar 11 is fixed to the tip of the positive electrode terminal 137 of the air battery cell 100 by the nut 12, and the other end of the bus bar 11 is fixed to the tip of the cell side negative electrode terminal 114 of the air battery cell 100 by the nut 13. The In general, the bus bar is a general term for rod-shaped metals used in place of electric wires, etc., but the cross section of the electric wires etc. is circular, whereas the cross section of the bus bar is a long and narrow rectangle, so it has a heat dissipation effect. In addition, since the surface area is larger than that of electric wires or the like, it is more advantageous in a light beam system having a large surface current.

  Furthermore, in order to bundle and fix the plurality of air battery cells 100 (100A, 100B, 100C, 100D, 100E) connected by the bus bar 11, the plurality of air battery cells 100 are fastened by bolts 15. The bolt 15 is rod-shaped, and its length is longer than the total thickness of the plurality of air battery cells 100 connected by the bus bar 11. The bolt 15 passes through a bolt hole 101b (see FIG. 1 and the like) provided in the housing frame 102 of the plurality of air battery cells 100, and both ends thereof are fastened by nuts 16 and 17, thereby It fixes so that the air battery cell 100 may not slip | deviate. The larger the number of bolts 15 (the number of bolt holes 101b), the more firmly the plurality of air battery cells 100 are fixed. For example, in the present embodiment, the plurality of air battery cells 100 are fixed very firmly because the bolts 15 are fastened at a total of four places on two sides on the both sides in the width direction.

(Control part)
Moreover, the air battery unit 10 which concerns on this embodiment may have a control part (not shown) for switching the connection of the several air battery cell 100 by series and parallel. When the plurality of air battery cells 100 are connected in series, the output voltage is increased, and when the plurality of air battery cells 100 are connected in parallel, the discharge capacity is increased. Therefore, the control unit switches the connection method of the plurality of air battery cells 100 between series and parallel according to the use of the air battery unit 10, for example, in the case of an application requiring a high output voltage. In the case of applications that require a large discharge capacity, they can be paralleled. Thereby, the one air battery unit 10 can be utilized now for various uses.

<Assembly method of air battery unit 10>
Next, an assembling method of the air battery unit 10 having the above-described configuration will be described with reference to FIG. FIG. 13 is an exploded perspective view showing a method for assembling the air battery unit 10 according to the present embodiment.

  As shown in FIG. 13, with respect to a plurality of air battery cells 100 (100A, 100B, 100C, 100D, 100E), positive terminals of adjacent air battery cells 100 (for example, air battery cell 100A and air battery cell 100B). 137 (for example, the positive terminal 137 of the air battery cell 100A) and the cell side negative terminal 114 (for example, the cell side negative terminal 114 of the air battery cell 100B) are connected by the bus bar 11, and the tip of the positive terminal 137 is connected by the nut 12. The bus bar 11 is fixed to the air battery cell 100 by fastening the tip of the cell-side negative electrode terminal 114 with the nut 13. This is performed for all adjacent air battery cells 100.

  Moreover, after arrange | positioning the several air battery cell 100 (100A, 100B, 100C, 100D, 100E) to arrange in the thickness direction, it is volt | bolt so that the bolt hole 101b provided in each air battery cell 100 may be penetrated. 15 is inserted. At this time, the bolt 15 penetrates all the bolt holes 101b of the air battery cells 100A, 100B, 100C, 100D, and 100E. Furthermore, by tightening both ends of the bolt 15 with nuts 16 and 17, the plurality of air battery cells 100 (100A, 100B, 100C, 100D, and 100E) are fastened and fixed.

  As described above, the air battery unit 10 according to this embodiment to which the plurality of air battery cells 100 are connected can be manufactured. Note that either the connection by the bus bar 11 or the fastening by the bolt 15 may be performed first.

<Operation Principle of Air Battery Cell 100>
Next, the operation principle of the air battery cell 100 according to the present embodiment will be described with reference to FIG. FIG. 14 is a schematic diagram for explaining the operating principle of the air battery cell 100 according to the present embodiment.

  As shown in FIG. 14, the air battery cell 100 according to the present embodiment is provided with the negative electrode active material layers 112 on both surfaces of the negative electrode current collector 111, so as to face the respective negative electrode active material layers 112. A positive electrode 130 is disposed. An electrolyte 150 is filled between the positive electrode 130 and the negative electrode 110. The positive electrode 130 has a water repellent oxygen permeable sheet 133 for taking in oxygen in the air outside the air battery cell 100 on the current collector 132, and a reducing ability of oxygen taken from the water repellent oxygen permeable sheet 133. The catalyst layer 134 having the structure is laminated. If the electrolyte 150 is not an electrolytic solution, a sheet or layer that is permeable to oxygen that does not have water repellency may be used instead of the water repellent oxygen permeable sheet 133.

In such an air battery cell 100, when oxygen (O ₂ ) in the air is taken in from the outside through the water-repellent oxygen permeable sheet 133, first, in the positive electrode 130, the catalyst layer 134 has the following formula (1). Oxygen reduction occurs as a discharge reaction.
Positive electrode: O ₂ + 2H ₂ O + 4e ⁻ → 4OH ⁻ (1)

Hydroxide ions (OH ⁻ ) generated at the positive electrode 130 as in the formula (1) are transmitted to the current collector 132, and further pass through the electrolyte 150 to pass through the negative electrode 110 (the negative electrode current collector 111 and the negative electrode active material). The material layer 112) is reached. Then, in the negative electrode 110, in the negative electrode active material layer 112, the positive electrode active material VB ₂ and the inclusion metal (for example, in the following formula (3), the reaction formula of Zn is expressed as in the following formulas (2) and (3). And the hydroxide ions react to cause an oxidation reaction of VB ₂ as a discharge reaction.
Negative electrode: VB ₂ + 11OH ⁻ → 1 / 2V ₂ O ₅ + B ₂ O ₃ + 11 / 2H ₂ O + 11e ⁻
(2)
Zn + 4OH ⁻ → [Zn (OH) ₄ ] ² + 2e ⁻ (3)

Thus, in the negative electrode 110, a large amount of electrons (e ⁻ ) of 11 per mol of VB _{2 as} the negative electrode active material (fuel) and ₂ per mol of Zn as the inclusion metal are generated by the discharge reaction. The energy density is high, and the air battery cell 100 according to the present embodiment has a very high discharge capacity per unit volume. At this time, in the negative electrode active material layer 112, in addition to the negative electrode active material VB ₂ and the inclusion metal, the first conductive material and the second conductive material are used as a conductive auxiliary agent for assisting the conductivity of the negative electrode active material. When a conductive material is included, the large amount of generated electrons can be efficiently transmitted. Therefore, according to the air battery cell 100 which concerns on this embodiment, the discharge capacity near a theoretical value is realizable.

<Use and usage of air battery cell 100 and air battery unit 10>
Then, the use and usage method of the air battery cell 100 and the air battery unit 10 mentioned above are demonstrated.

  The air battery cell 100 and the air battery unit 10 according to the present embodiment have a high energy density and a large discharge capacity, and thus can be applied to various applications. It can be used for alternative applications such as a power source, a backup power source in the event of a disaster, a battery such as a PC or a mobile device, and other general air batteries, fuel cells, lithium secondary batteries, and the like. In this case, in order to increase the open circuit voltage, it is preferable to use the air battery unit 10 combined with a predetermined booster circuit or connected to a large number of air battery cells 100. Moreover, since the open circuit voltage can be increased by combining the air battery cell 100 and the air battery unit 10 with a predetermined booster circuit, it can be used for an emergency battery or the like. It can also be used as a power source for use in a coal mine. In a coal mine application, since a battery in which hydrogen is generated or burned cannot be used, it is preferable to use the air battery cell 100 and the air battery unit 10 according to this embodiment.

<< Second Embodiment >>
Next, an air battery and an air battery unit according to a second embodiment of the present invention will be described.

<Configuration of Air Battery Cell 100>
First, the structure of the air battery cell 200 which concerns on this embodiment is demonstrated, referring FIGS. 15-17. FIG. 15 is a perspective view showing an external configuration of the air battery cell 200 according to the present embodiment. 16 is a plan view of the air battery cell 200 shown in FIG. 15, wherein (a) is a top view, (b) is a front view, (c) is a left side view, (d) is a right side view, e) shows an enlarged view of the circled portion of the broken line in (c). FIG. 17 is an exploded perspective view showing the internal configuration of the air battery cell 200 according to the present embodiment.

  As shown in FIGS. 15 to 17, an air battery cell 200 according to this embodiment includes a negative electrode (anode) 210 as a fuel electrode, a positive electrode (cathode) 230 as an air (oxygen) electrode, and the present embodiment. An electrolyte (not shown) as an example of the electrolyte and a separator 260 are provided. In the air battery cell 200, two sheet-like positive electrodes 230 are arranged so as to sandwich a plate-like negative electrode 210 from the front side and the back side via a separator 260.

  More specifically, the air battery cell 200 has a structure in which a negative electrode 210, a positive electrode 230, and a separator 260 are laminated in the order of a positive electrode 230, a separator 260, a negative electrode 210, a separator 260, and a positive electrode 230. Then, in order to fix the laminated negative electrode 210, positive electrode 230, and separator 260, the clip-shaped clamping member 201 fixes the negative electrode 210, the positive electrode 230, and the separator 260 so as to sandwich them from their edges. Yes. As shown in FIG. 16 (e), the sandwiching member 201 has a bent portion 201a at the tip portion, and a portion protruding to the inside (positive electrode current collector 232 side) of the bent portion 201a By pressing the surface of the positive electrode current collector 232, the negative electrode 210, the positive electrode 230, and the separator 260 are sandwiched. A plurality of protrusions 232 b are provided on the surface of the positive electrode 230 so as to be positioned inside the sandwiching member 201 when sandwiched by the sandwiching member 201. Since the protrusion 232b serves as a stopper for the sandwiching member 201, the sandwiching member 201 is hardly detached.

  The electrolyte (electrolytic solution) is present around the air battery cell 200 in a state where the air battery cell 200 is accommodated in a unit housing 21 (see FIGS. 18 to 20) described later. Further, in the present embodiment, unlike the first embodiment described above, one air battery cell 200 includes one set of electrode pairs (one negative electrode 110 and a pair of two positive electrodes 130 arranged on both sides thereof. )have.

[Negative electrode 210]
The negative electrode 210 is an electrode that functions as a fuel electrode of the air battery cell 200. For example, as shown in FIG. 17, the negative electrode 210 mainly includes a negative electrode current collector 211, a negative electrode active material layer 212, and a negative electrode terminal 214. .

(Negative electrode current collector 211)
The negative electrode current collector 211 is a substantially plate-like member having conductivity, and has a role of holding a negative electrode active material and supplying a current to the negative electrode active material.

[Material]
Since the material of the negative electrode current collector 211 is the same as that of the negative electrode current collector 111 according to the first embodiment described above, the description thereof is omitted here.

〔shape〕
The negative electrode current collector 211 has a substantially plate shape, but unlike the first embodiment, no groove or recess is provided.

(Negative electrode active material layer 212)
The negative electrode active material layer 212 is a layer that is provided on the surface (both surfaces) of the negative electrode current collector 211 described above and includes a negative electrode active material that serves as a fuel when the air battery cell 200 is discharged. Since the negative electrode active material layer 212 has the same components and other configurations as those of the negative electrode active material layer 112 according to the first embodiment described above, the description thereof is omitted here.

(Negative electrode terminal 214)
The negative electrode 210 has a negative electrode terminal 214 in addition to the negative electrode current collector 211 and the negative electrode active material layer 212 described above. The negative electrode terminal 214 is an elongated plate-like member provided so as to protrude outward from one vertex of the negative electrode current collector 211. Of course, the negative electrode terminal 214 is formed of a conductive material, like the electrode-side negative electrode terminal 113 and the cell-side negative electrode terminal 114 described above. The negative electrode terminal 214 is electrically connected to the positive electrode terminal 237 and the negative electrode terminal 214 of the power supply or other air battery cell 200.

[Positive electrode 230]
The positive electrode 230 is an electrode that functions as an oxygen electrode of the air battery cell 200 (an electrode having oxygen as a positive electrode active material). For example, one electrode is provided on each of the front surface side and the back surface side of the negative electrode 210 as shown in FIG. Has been placed. The positive electrode 230 mainly includes a positive electrode current collector 232 and an oxygen permeation / catalyst layer 233.

(Positive electrode current collector 232)
The positive electrode current collector 232 is a substantially rectangular frame-shaped member, and has an opening 232a at a substantially central portion (inside the frame). After the air battery cell 200 is assembled, the oxygen permeable / catalyst layer 233 is located in the opening 232a.

  The positive electrode current collector 232 has a role of supplying electrons to oxygen which is a positive electrode active material. Since the material of the positive electrode current collector 232 is the same as that of the positive electrode current collector 132 according to the first embodiment described above, detailed description thereof is omitted.

  A positive electrode terminal 237 is provided at a substantially central portion of the long side portion of the positive electrode current collector 232. The positive electrode terminal 237 is electrically connected to the positive electrode terminal 237 and the negative electrode terminal 214 of the power source or other air battery cell 200.

(Oxygen permeation / catalyst layer 233)
Although not shown, the oxygen permeation / catalyst layer 233 is basically the same as in the first embodiment, and a member corresponding to the catalyst holding body 135 is made to hold a layer corresponding to the catalyst layer 134. Later, a sheet corresponding to the water-repellent oxygen permeable sheet 133 is pasted thereon. Therefore, the oxygen permeation / catalyst layer 233 has the function of the water repellent oxygen permeable sheet 133 and the function of the catalyst layer 134 described above. Other configurations are the same as those of the water-repellent oxygen permeable sheet 133 and the catalyst layer 134, and thus description thereof is omitted here.

[Separator 260]
In this embodiment, since the negative electrode 210 and the positive electrode 230 are laminated, unlike the first embodiment, it is necessary to prevent a short circuit regardless of whether the electrolyte is an electrolyte (liquid) or not. It becomes. The function of the separator 260 is the same as that of the separator 160 described above. In addition to the material similar to the separator 160, an insulator similar to the separator generally used for batteries can be used as the material of the separator 260.

<Method for Manufacturing Air Battery Cell 200>
The configuration of the air battery cell 200 according to the present embodiment has been described in detail above. Subsequently, the method for manufacturing the air battery cell 200 having the above-described configuration will be described in detail with reference to FIG.

[Manufacture of Negative Electrode 210]
First, the manufacturing process of the negative electrode 210 will be described. First, the material of the negative electrode active material layer 212 described above, that is, the VB ₂ / metal composite and the binder (and the first conductive material, the second conductive material, and other additives as necessary) having a predetermined mixing ratio are kneaded. Then, a negative electrode active material slurry (active material slurry) is prepared. Next, the active material slurry thus prepared is applied (cast) to the surface (both sides) of the negative electrode current collector 211. Finally, the active material slurry applied to the surface of the negative electrode current collector 211 is dried, so that the active material slurry adheres firmly to the negative electrode current collector 211 and solidifies. As shown in FIG. A negative electrode active material layer 212 is formed on the surface of the current collector 211. In addition, about the coating method of an active material slurry, the drying method, etc., it is the same as that of 1st Embodiment mentioned above.

[Manufacture of Positive Electrode 230]
Next, the manufacturing process of the positive electrode 230 will be described. First, the oxygen permeable / catalyst layer 233 is produced in the same manner as the catalyst holding body 135 holding the water-repellent oxygen permeable sheet 133 and the catalyst layer 134. Next, the positive electrode 230 can be manufactured by fixing the oxygen permeation / catalyst layer 233 thus prepared to the positive electrode current collector 232.

[Manufacture of air battery cell 200]
Next, the process of manufacturing the air battery cell 200 using the negative electrode 210 and the positive electrode 230 manufactured as described above will be described. First, as shown in FIG. 17, the positive electrode 230, the separator 260, the negative electrode 210, the separator 260, and the positive electrode 230 are laminated in this order. Next, the negative electrode 210, the positive electrode 230, and the separator 260 are fixed by attaching the sandwiching member 201 so that the edges of the long sides of the stacked negative electrode 210, positive electrode 230, and separator 260 are sandwiched by the sandwiching member 201. The Here, in FIG. 17, the negative electrode 210, the positive electrode 230, and the separator 260 are fixed using the four sandwiching members 201, but if the strength that can be secured so as not to detach is secured, The number may be three or less, and may be five or more if the strength is insufficient (in order to maintain the balance of the fixed strength in the width direction, it is preferable that the number of the sandwiching members 201 is an even number). . The air battery cell 200 can be manufactured as described above.

<Configuration of Air Battery Unit 20>
Next, the configuration of the air battery unit 20 in which a plurality of the air battery cells 200 described above are connected will be described with reference to FIGS. 18 and 19. FIG. 18 is a perspective view showing the overall configuration of the air battery unit 20 according to the present embodiment. 19 is a plan view of the air battery unit shown in FIG. 18, in which (a) is a top view, (b) is a front view, and (c) is a right side view.

(overall structure)
As shown in FIGS. 18 and 19, the air battery unit 20 includes a plurality of the air battery cells 200 described above. In the example shown in FIGS. 18 and 19, an example in which 16 air battery cells 200 are connected is described, but the number of air battery cells 200 is not particularly limited.

  The air battery unit 20 according to the present embodiment is in a state in which a plurality of air battery cells 200 are accommodated in the unit housing 21. In this state, the negative electrode 210 and the positive electrode 230 ( Alternatively, the negative electrode 210 and the negative electrode 210, and the positive electrode 230 and the positive electrode 230) are connected by a bus bar (not shown) or the like. The unit housing 21 has a plurality of housing grooves 22 for housing the air battery cells 200 therein. The width of the housing groove 22 is slightly larger than the thickness of the entire air battery cell 200, and the air battery cell 200 is fixed in the housing groove 22 with a predetermined play. Yes. The unit housing 21 is provided with a voltage management board 26 on which a circuit for managing the output voltage of the power supply 25 and the air battery unit 20 is arranged.

(Control part)
Moreover, the air battery unit 20 which concerns on this embodiment is the control part (for switching the connection of the several air battery cell 100 in series and parallel similarly to the air battery unit 10 which concerns on 1st Embodiment mentioned above. (Not shown). The configuration of this control unit is the same as that of the first embodiment. The control unit may be provided on a part of the voltage management board 26 described above, or may be provided as a separate circuit board or an external device.

<Assembly method of air battery unit 20>
Next, a method for assembling the air battery unit 20 having the above-described configuration will be described with reference to FIG. FIG. 20 is an exploded perspective view showing an assembling method of the air battery unit 20 according to the present embodiment.

  As shown in FIG. 20, first, each of the plurality of air battery cells 200 is inserted into each of the plurality of receiving grooves 22 provided in the unit housing 21, and the plurality of air battery cells 200 are inserted into the unit housing 21. To accommodate. Next, although not shown in the drawing, the plurality of air battery cells 200 housed in the unit housing 21 and the power source 25 are connected by a bus bar (not shown), a conductive wire, or the like, so that the plurality of air battery cells 200 are connected. The air battery unit 20 according to this embodiment to which is connected can be manufactured.

  Note that the operating principle of the air battery cell 200 according to the present embodiment and the uses and usage methods of the air battery cell 200 and the air battery unit 20 are the same as those in the first embodiment described above.

  Next, although an example and a comparative example explain the present invention still more concretely, the present invention is not limited at all by these examples.

[Preparation of Zn-incorporated VB ₂ complex (VB ₂ / Zn complex)]
After adding 1000 g of VB ₂ powder having an average particle size of 0.5 to 10 μm to 1000 mL of a CNT dispersion solution containing 5 mass% of carbon nanotubes (CNT), the mixture was gently stirred for about 2 hours. The obtained slurry containing VB ₂ and CNT was treated by a spray drying method to obtain VB ₂ particles (VB ₂ / CNT particles) encapsulated with CNT having an average particle diameter of about 3 to 300 μm. Next, the obtained VB ₂ / CNT particles were gently mixed with zinc powder having an average particle diameter of 50 to 500 μm at a mass ratio of 1/2 (VB ₂ / CNT particles: zinc = 1: 2), and then 420 ° C. And 30 MPa for 30 seconds to prepare a cylindrical VB ₂ / Zn composite having a diameter of 30 mm and a length of 100 mm. Furthermore, VB ₂ powder encapsulated with zinc through a powder processing process using the VB ₂ / metal composite production apparatus 500 shown in FIG. 10, that is, VB ₂ / Zn composite particles having an average particle diameter of 100 to 500 μm. Was made.

[Production of negative electrode]
The VB ₂ / Zn composite particles obtained as described above, carbon black, and PVDF as a binder were kneaded at a mass ratio of 84%, 8%, and 8%, respectively. A slurry was prepared. Next, this slurry was applied to the grooves of a graphite current collector having the shape shown in FIG. 9 and the like using a brush and allowed to dry naturally. By performing this on both sides of the current collector, a negative electrode having a negative electrode active material or the like formed on both sides of the current collector was obtained.

[Production of air battery]
Further, a powder of MnO ₂ (30% by mass), PTFE (25% by mass), carbon black (5% by mass), and activated carbon (40% by mass) was kneaded and made into a catalyst layer material. Next, the catalyst layer material is held on a metal mesh made of stainless steel (SUS304 nickel plating), a PTFE sheet is pasted on one surface thereof, and further fixed to a frame made of SPCC to obtain a positive electrode. .

  Using the negative electrode and the positive electrode manufactured as described above, an air battery cell was manufactured as described above with reference to FIGS. In addition, the potassium hydroxide aqueous solution with a density | concentration of 86 mass% was used as electrolyte solution, and the woven fabric (thickness 200 micrometers) containing a cellulose, rayon, and PVA was used as a separator. The separator had a pore diameter of 11 μm and a width of 260 mm × 200 mm.

[Evaluation of discharge characteristics with a single air battery cell]
Using a single air battery cell (single cell) produced as described above, the discharge characteristics were evaluated by performing a 30 A constant current discharge. The results are shown in Table 1 below, and the discharge curve is shown in FIG. FIG. 21 is a graph showing a discharge curve in a single cell in this example. In FIG. 21, the horizontal axis represents the discharge time, the left vertical axis represents the voltage, and the right vertical axis represents the current value. Moreover, the curve shown by the practice of a figure shows the change of a voltage, and the curve shown with the broken line has shown the change of an electric current.

As shown in Table 1 and FIG. 21, even in the case of a single cell, a voltage of 1 V or higher can be maintained for nearly 9 hours, a voltage of 0.8 V or higher can be maintained for 11 hours or longer, and a voltage of 0.3 V or higher can be maintained for 12 hours. I was able to maintain it. Furthermore, the average voltage of 1V or more could be maintained for 12 hours or more. This is a practically sufficient value. In addition, since the VB ₂ / Zn composite particles are used as the negative electrode active material, the energy density is very high, and the discharge capacity and the discharge power amount are also very high.

[Evaluation of discharge characteristics of 10-cell air battery unit]
In addition, an air battery unit (10 cells) having 10 air battery cells as shown in FIG. 11 and the like is obtained by connecting 10 single cells produced as described above as described in FIG. Was made. The discharge characteristics were evaluated by performing constant current discharge using the 10-cell air battery unit. In this 10-cell evaluation, a constant current discharge of 30 A was first performed, the current value was changed to 20 A after the voltage dropped, a constant current discharge was performed, and the current value was changed to 10 A after the voltage dropped further. A constant current discharge was performed with the change. The results are shown in Table 2 below, and the discharge curve is shown in FIG. FIG. 22 is a graph showing a discharge curve in 10 cells in this example. In FIG. 22, the horizontal axis represents the discharge time, the left vertical axis represents the voltage, and the right vertical axis represents the current value. Moreover, the curve shown with the continuous line of the figure has shown the change of a voltage, and the curve shown with the broken line has shown the change of an electric current.

  As shown in Table 2 and FIG. 22, even in the case of 10 cells, a constant current discharge of 30 A could be maintained for 10 hours or more. Further, the discharge capacity was very high at 300 Ah or more, and the average voltage was 11 V or more, which was a practically sufficient value. If it is an air battery unit which has such discharge performance, it is a level which can be used also as a battery for electric vehicles, for example. In addition, it was found that in applications that do not require such a high discharge capacity and voltage, the battery can be used for a further 30 minutes at a constant current of 20A and for another hour at a constant current of 10A.

As conductive carbon subsumes VB ₂ particles, instead of the CNT, a carbon black and graphene, also subsumed the VB ₂ particles VB ₂ particles and graphene inclusion with carbon black prepared, as above also for these The same discharge characteristics were evaluated. In either case, the discharge capacity was slightly lower than that in the case of using CNT, but the discharge capacity was high enough for practical use.

  The preferred embodiment of the present invention has been described above with reference to the drawings, but the present invention is not limited to the above-described embodiment. That is, it is understood that other forms or various modifications that can be conceived by those skilled in the art within the scope of the invention described in the claims belong to the technical scope of the present invention.

10, 20 Air battery unit 11 Bus bar 15 Bolt 21 Unit housing 22 Housing groove 100, 200 Air battery cell 101 Housing 102 Housing frame 103 Front cover 104 Back cover 105 Cap 106 Slide members 110, 120, 210 Negative electrodes 111, 121 , 211 Negative electrode current collector 111a Groove portion 121a Recess 112, 212 Negative electrode active material layer 113, 123 Electrode side negative electrode terminal 114 Cell side negative electrode terminal 116 Terminal support member 130, 230 Positive electrode 132, 232 Positive electrode current collector 133 Water repellent oxygen permeable sheet 134 Catalyst layer 135 Catalyst holder 137, 237 Positive electrode terminal 150 Electrolytic solution 160, 260 Separator 201 Nipping member 233 Oxygen permeation / catalyst layer

Claims (18)

As a negative electrode active material, a negative electrode containing a VB ₂ / metal composite containing vanadium diboride particles in a metal that reacts with hydroxide ions to generate electrons and becomes a hydroxide by the reaction;
A positive electrode using oxygen as a positive electrode active material;
An electrolyte that conducts hydroxide ions between the negative electrode and the positive electrode;
An air battery comprising: _2. The air battery according to claim 1, wherein the VB ₂ / metal composite has an average particle size of 30 μm or more and 800 μm or less.   The air battery according to claim 1 or 2, wherein an average particle size of vanadium diboride included in the metal is 0.5 µm or more and 500 µm or less.   The air battery according to any one of claims 1 to 3, wherein the metal is at least one metal selected from the group consisting of zinc, aluminum, magnesium, lithium, sodium, calcium, and alloys thereof. The air battery according to any one of claims 1 to 4, wherein the VB ₂ / metal composite further includes vanadium diboride particles encapsulated with conductive carbon.   The air battery according to claim 5, wherein the conductive carbon containing the vanadium diboride is at least one selected from the group consisting of carbon nanotubes, carbon black, graphene, graphite, carbon fiber, graphite, and activated carbon. The air battery according to any one of claims 2 to 6, wherein the negative electrode further contains a first conductive material having an average particle size less than the average particle size of the VB ₂ / metal composite. The air battery according to claim 7, wherein the negative electrode further contains a second conductive material having an average length equal to or larger than an average particle diameter of the VB ₂ / metal composite. The first conductive material is contained in an amount of 0.5 to 50 parts by mass with respect to 100 parts by mass of the VB ₂ / metal composite,
The air battery according to claim 8, wherein the second conductive material is contained in an amount of 0.1 parts by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the VB ₂ / metal composite.   The air battery according to claim 8 or 9, wherein the first conductive material and the second conductive material are conductive carbon.   The first conductive material is at least one conductive carbon selected from the group consisting of carbon black, graphite and activated carbon, and the second conductive material is at least one conductive selected from the group consisting of graphene, carbon nanotube and carbon fiber. The air battery according to claim 10, which is a functional carbon.   The air battery according to any one of claims 1 to 11, wherein a material of the current collector of the negative electrode is graphite or a metal that is inactive under an alkaline environment. The air battery according to any one of claims 1 to 12, wherein in the negative electrode, discharge regions including the VB ₂ / metal composite are divided into a plurality in a state of being separated from each other. The negative electrode current collector has a plurality of discharge cells separated from each other, and a partition is provided between the adjacent discharge cells,
The air battery according to claim 13, wherein each discharge cell has a negative electrode active material layer containing the VB ₂ / metal composite as the discharge region. The electrolyte is an aqueous or non-aqueous electrolyte;
A separator that electrically insulates the negative electrode from the positive electrode;
The air battery according to claim 1, wherein the separator can be impregnated with the electrolytic solution.   The air battery according to any one of claims 1 to 15, wherein the negative electrode is detachably provided to the air battery. A negative electrode for an air battery having a positive electrode using oxygen as a positive electrode active material,
A negative electrode containing, as a negative electrode active material, a VB ₂ / metal composite that reacts with hydroxide ions to generate electrons and includes a vanadium diboride particle with a metal that becomes a hydroxide by the reaction. The air battery unit which has two or more cells of the air battery as described in any one of Claims 1-16.

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