JP2021073635A - Nickel-magnesium cell - Google Patents

Abstract

To provide a nickel-magnesium cell that has a larger electric capacitance than that of a conventional lithium-ion secondary battery, is capable of being miniaturized, and is safer than lithium-ion secondary cells.SOLUTION: A nickel-magnesium cell includes a cathode made of a nickel oxide, an anode made of a magnesium alloy, a separator provided between the cathode and the anode, and an alkaline electrolyte filling between the cathode and the anode, in which the electrolyte contains a ligand forming a chelate complex with magnesium ions. The ligand is preferably ethylenediaminetetraacetic acid.SELECTED DRAWING: Figure 1

Description

The present invention relates to a nickel-magnesium battery, and more specifically, the present invention comprises a positive electrode made of nickel oxide, a negative electrode made of a magnesium alloy, a separator provided between the positive electrode and the negative electrode, and an alkaline electrolyte. Represents a nickel-magnesium battery, characterized in that it contains a ligand that forms a chelate with magnesium ions.

In recent years, electronic and electrical devices have been steadily becoming smaller, lighter, thinner, and more sophisticated year by year in order to improve convenience, and along with this, batteries used as power sources for these devices have been used. Has been required to be a small, light, thin, high capacity, especially rechargeable secondary battery.
A small secondary battery that meets these demands has an electric capacity (weight energy density of 60 to 120 Wh / kg, volume energy density of 140 to 200 Wh / L) that is 2.5 times that of a nickel-cadmium storage battery (nickel-cadmium battery). It was a nickel-metal hydride rechargeable battery that I had. This was called the Ni-MH type, which used nickel as the positive electrode material and mischmetal, which is a hydrogen storage alloy, as the negative electrode material. Since then, lithium-ion secondary batteries with even larger electric capacities have been developed, and have lost their share in the field of portable devices, but in the field of dry batteries, they have become the mainstream in place of nickel-cadmium batteries. In the field of electric vehicles and hybrid vehicles, larger nickel-metal hydride rechargeable batteries have been developed, and the Ni-H ₂ type, which stores hydrogen in a high-pressure tank and supplies hydrogen to the cathode, is being studied. Since the nickel-metal hydride rechargeable battery for automobiles has a small volumetric energy density, there is a problem that its shape becomes large when trying to obtain a large amount of electricity.
The reason why nickel-metal hydride rechargeable batteries are used as a driving power source for automobile motors is that there is less risk of explosion than lithium-ion rechargeable batteries, which will be described later. On the other hand, the biggest drawback of nickel-metal hydride rechargeable batteries is that when they are recharged by adding them to nickel-metal hydride rechargeable batteries, a memory phenomenon occurs in which the voltage drops temporarily during discharge. It has to be discharged and then recharged.

Following the nickel-metal hydride rechargeable battery, the lithium-ion secondary battery was introduced. A lithium ion secondary battery uses a lithium transition metal composite oxide for the positive electrode, a carbon material for the negative electrode, and a non-aqueous electrolyte such as an organic solvent for the electrolyte, and charges and discharges by moving lithium ions between the positive electrode and the negative electrode. It is something to do. The strengths of lithium-ion secondary batteries are twice the weight energy density (100 to 243 Wh / kg) and three times the volume energy density (250 to 676 Wh / L) of nickel-metal hydride batteries. In the equipment field, nickel-metal hydride batteries were dominated. However, due to its high energy density, it generated abnormal heat during charging and even caused a fire accident, so countermeasures are urgently needed.

On the other hand, there is an air magnesium battery in which metallic magnesium is used for the negative electrode and oxygen in the air is used for the positive electrode. It is a type of air battery and fuel cell, and the idea of creating a "magnesium circulation society" by regenerating magnesium hydroxide generated by the discharge of the battery into magnesium using solar heat has attracted attention. , It has not reached the stage of completion yet. This is because magnesium hydroxide forms a passivation on the surface of the magnesium electrode and stops power generation. Measures to avoid by adding an auxiliary agent to make the generated magnesium hydroxide more soluble in the electrolyte (see Patent Documents 1 and 2) and using an alloy of magnesium and calcium for the electrodes, hydroxide ions Attempts have been made to suppress the formation of inductive states by depriving magnesium of calcium, but none of these attempts have been sufficiently effective.

Japanese Patent Application No. 2008-191821 JP-A-2009-064730

The present invention has been made to solve such a problem, and an object thereof is a lithium secondary battery having a larger electric capacity than a conventional lithium ion secondary battery and capable of miniaturization. The purpose is to provide safer nickel-magnesium batteries.

The nickel-magnesium battery of the present invention made to achieve the above object includes a positive electrode made of nickel oxide, a negative electrode made of a magnesium alloy, a separator provided between the positive electrode and the negative electrode, and a positive electrode and a negative electrode. It consists of an alkaline electrolyte packed in between, characterized in that the electrolyte contains a ligand that forms a chelate complex with magnesium ions.

The ligand is preferably ethylenediaminetetraacetic acid.
It is preferable to have a catalyst layer on which carbon fine particles carrying a noble metal catalyst are attached around the negative electrode.
The negative electrode can be a flame-retardant magnesium alloy containing calcium.

The positive electrode is preferably a porous molded body obtained by sintering nickel hydroxide.
It is preferable that a layer of activated carbon is formed between the positive electrode and the separator.

According to the present invention, the nickel-magnesium battery of the present invention prevents the formation of non-conductors, which is the biggest problem of magnesium air batteries, by blending an alkaline electrolyte with a ligand that forms a chelate complex with magnesium. , It is possible to provide a secondary battery having a larger electric capacity than a conventional lithium ion secondary battery.
By increasing the volumetric energy density, the battery can be miniaturized, and it is possible to provide a battery suitable not only for electric vehicles and hybrid vehicles but also for artificial satellites and space probes.
In the nickel-magnesium battery of the present invention, by providing a catalyst layer of carbon fine particles carrying a noble metal catalyst around the negative electrode, hydrogen (H ₂ ) generated by the reaction between the magnesium of the negative electrode and the water of the electrolyte is hydrogen ion (H 2). Since ^{it decomposes into H +} ) and electrons (e ⁻ ) and prevents hydrogen gas from accumulating in the battery cell, it is possible to prevent the cell from expanding and prevent accidents such as liquid leakage.
In the nickel-magnesium battery of the present invention, an activated carbon layer is provided between the positive electrode and the separator to buffer the violent oxidation / reduction reaction between the positive electrode and the negative electrode during charging, thereby ensuring safety.

It is sectional drawing of the square nickel-magnesium battery which is one Embodiment of this invention. It is a figure which shows the structure of the chelate complex of magnesium ion by ethylenediaminetetraacetic acid (EDTA).

The present invention drives secondary batteries for various electronic and electrical devices such as mobile phones, digital cameras / videos, portable music players, and dedicated batteries for notebook computers, motors and interior devices of electric vehicles and hybrid cars. Regarding nickel-magnesium batteries that can be used from dry batteries to artificial satellites and space probes, such as rechargeable batteries.
The nickel-magnesium battery of the present invention can be provided in a variety of shapes to meet the many needs listed above. For example, there are single type, AA type, AA type, AAA type, button type, square type, box type, and other industrial special products.
The nickel-magnesium battery of the present invention is made of a positive electrode made of nickel oxide, a negative electrode made of a magnesium alloy, a separator provided between the positive electrode and the negative electrode, and an alkaline electrolyte filled between the positive electrode and the negative electrode. The electrolyte is characterized by containing a ligand that forms a chelate with magnesium ions.
FIG. 1 is a cross-sectional view of a square nickel-magnesium battery according to an embodiment of the present invention. In FIG. 1, reference numeral 1 is a nickel-magnesium battery, 10 is a positive electrode, 20 is a negative electrode, 30 is a separator, 40 is an electrolyte, 50 is a catalyst layer, and 60 is an activated carbon layer.

The positive electrode 10 is a porous molded body made of nickel oxide. Electrons generated in the negative electrode 20, positive electrode 10 (e ^-) are moved through the cell, electrons positive electrode 10 (e ^-) is reacted with oxygen (o ₂₎ in the air. In this case, since the incorporation of oxygen (o ₂₎ is rate-limiting step, it is preferable positive electrode is porous so as to facilitate absorption of oxygen.
Examples of the nickel oxide used for the positive electrode 10 include nickel hydroxide (Ni (OH) ₂ ), nickel oxide hydroxide (NiООH), and nickel oxide (NiO).
The electrode casting method is not particularly limited, but a ceramic molding / sintering method can be applied. For example, nickel oxide powder may be placed in a mold, pressure-molded, and baked in a sintering furnace. Further, a method of removing the resin by heat-sintering a molded product obtained by injection molding a mixture obtained by melting a synthetic resin and mixing nickel oxide powder can also be used.

The negative electrode 20 is made of metallic magnesium (Mg), and at the time of discharge, it reacts with an alkaline electrolyte 40 on its surface to become magnesium ions (Mg ²⁺ ) and electrons (e ⁻ ). The electron (e ⁻ ) moves in the cell toward the positive electrode 10. The negative electrode 20 can be manufactured of metallic magnesium (Mg) having a purity of 99% or more, but since it is soft and may have insufficient hardness, it is usually 2 to 10% aluminum (Al) and about 1%. An alloy mixed with zinc (Zn) is used. ^{Magnesium ions (Mg 2+} ) eluted from the negative electrode react with surrounding hydroxide ions (ОH ⁻ ) to become sparingly soluble magnesium hydroxide (Mg (OH) ₂ ), forming a passivation. In order to prevent the formation of passivation, the negative electrode 20 is preferably a flame-retardant magnesium alloy containing calcium. The amount of calcium mixed is usually about 1 to 5% with respect to the weight of the negative electrode 20. If the amount of calcium mixed is less than 1% by weight, the effect of interfering with passivation formation may not be sufficiently obtained, and if it exceeds 5%, the electrode may become brittle and crack.
Calcium (Ca) has a lower ionization tendency than magnesium (Mg) and is therefore easier to ionize than magnesium (Mg). Therefore, the hydroxide ion (ОH ⁻ ) can be deprived from the magnesium (Mg), ^{and the magnesium (Mg 2+ ) of the electrode dissolves at the moment when the hydroxide ion (ОH −} ) binds to the other party, which is not possible. The formation of kinetics can be delayed.

A separator 30 is provided between the negative electrode 20 and the positive electrode 10. The separator 30 is provided in order to separate the negative electrode side and the positive side, the electrons during discharge (e ^-) is shifted from the negative side to the positive side, the electrons during charging from the positive electrode side to the negative electrode side (e ^-) migration To do. Therefore, the separator 30 is preferably a non-polar porous membrane.
Materials used for the separator 30 include non-woven fabrics made from inorganic fibers such as glass wool, rock wool, and sludge wool, polyvinyl alcohol, polyamide, polyacrylonitrile, polyethylene, polypropylene, polystyrene, polyvinyl chloride, and polyethylene terephthalate. Woven or non-woven fabric made from synthetic fibers such as polyurethane, fluorinated resins such as polytetrafluoroethylene, polyvinylidene fluoride, and vinyl chloride, membrane filters made from cellulose acetate, and natural materials such as cellulose are used as raw materials. Cotton cloth or Japanese paper can be mentioned.
Among them, Japanese paper made of pure cellulose can be preferably used as the separator 30 of the nickel-magnesium battery 1.

An electrolyte 40 is filled between the positive electrode 10 and the negative electrode 20. An alkaline aqueous solution is used for the electrolyte 40. In an acidic electrolyte, it reacts with magnesium (Mg) in the electrode _{to generate hydrogen (H 2} ) and self-discharge.
The alkaline electrolyte 40 may be prepared by dissolving a basic compound in water. The basic substance used is not particularly limited as long as the aqueous solution is alkaline, but potassium hydroxide (KOH) or sodium hydroxide (NaOH) is usually used because of its price and availability. The concentration is 0.3 to 32%.
When the alkaline electrolyte 40 is used, magnesium (Mg) ^{reacts with hydroxide ions (OH −} ) to generate magnesium hydroxide (Mg (OH) ₂ ) and electrons (e ⁻ ). Electrons (e ⁻ ) move toward the positive electrode 10, but magnesium hydroxide (Mg (OH) ₂ ) has low water solubility and dissolves only 1.2 mg in 100 mL of water, so magnesium hydroxide (magnesium hydroxide (OH) 2) is present on the surface of the negative electrode. Mg (OH) ₂ ) precipitates. This becomes passivated and the reaction stops.
In order to solve this problem, _{research is being conducted on an auxiliary agent that dissolves magnesium hydroxide (Mg (OH) 2} ) in water, but no practical agent has been developed yet.
The present invention prevents the formation of non-conductors by isolating magnesium ions (Mg ²⁺ ) as a chelate complex outside the electrolyte system, rather than dissolving magnesium hydroxide (Mg (OH) _2).

The electrolyte 40 of the nickel-magnesium battery 1 of the present invention is characterized by containing a ligand (ligand) that forms a chelate with ^{magnesium ion (Mg 2+).} A chelate is a bond to a metal ion by a ligand having a plurality of coordination positions. A compound made up of chelate bonds is called a chelate complex. In chelate complexes of magnesium ions ^{(Mg 2+),} located magnesium ions ^{(Mg 2+)} in the center of complex molecules ^{(Mg 2+),} to form a complex compound surrounds ligand (ligand) is with shared electrons it .. In the chelate complex, since the ligand has a plurality of coordination loci and wraps the metal, it becomes difficult to separate the metal from the coordinating substance. This is called the chelate effect, and is ^{the principle of separating magnesium ions (Mg 2+} ) from the system of the electrolyte solution.
The number of ligands in the metal chelate is determined to be 2, 4 or 6 depending on the nature of the metal, and magnesium (Mg) is 6. Therefore, the structure of the chelate complex of magnesium ion (Mg ^{2+) is octahedral.} _{Ethylenediaminetetraacetic acid (EDTA: (HOCOCH 2} ) ₂ NCH ₂ CH ₂ N (CH ₂ COOH) ₂ ) is known as a ligand (ligand) of a hexahedron that forms a regular octahedron.

Shows the structure of a chelate complex of ethylenediaminetetraacetic magnesium with acetic acid (EDTA) ion ^{(Mg 2+)} in FIG. 2, a magnesium ion ^{(Mg 2+)} is ethylenediaminetetraacetic two nitrogen (N) and four oxygen acid (EDTA) ( Coordinated by O).
Ethylenediaminetetraacetic acid (EDTA) is freely soluble in an aqueous alkaline solution. The concentration of ethylenediaminetetraacetic acid (EDTA) in the electrolyte of the present invention is 0.5 to 50% by weight, preferably 3 to 30% by weight, and more preferably 6 to 24% by weight. If the concentration of ethylenediaminetetraacetic acid (EDTA) is less than 0.5% by weight ^{, the amount of magnesium ions (Mg 2+} ) that can form a chelate is small, and there is a risk that the formation of passivation cannot be sufficiently suppressed. On the other hand, when the concentration of ethylenediaminetetraacetic acid (EDTA) is 50% by weight or more, sodium hydroxide (NaOH) or potassium hydroxide (KOH) dissolved in the electrolyte 40 begins to precipitate, so that the function of the electrolyte deteriorates. There is a risk.

Magnesium (Mg) powder reacts with water to violently _{generate hydrogen (H 2} ). Magnesium (Mg) forming the negative electrode 20 does not react violently with the alkaline electrolyte 40 because it is a metal mass, but reacts gently to generate _{hydrogen (H 2).} Since the generated hydrogen (H ₂ ) stays in the cell, there is a risk of deteriorating the performance of the battery, and further, when hydrogen gas accumulates in the cell, the cell may expand and cause liquid leakage. In order to prevent deterioration of battery performance and liquid leakage accident, it is preferable that a catalyst layer 50 made of carbon fine particles carrying a catalyst is formed around the negative electrode 20.
_{The catalyst layer 50 formed around the negative electrode 20 converts hydrogen (H 2} ) generated by the reaction of magnesium (Mg) of the negative electrode 20 with water of the electrolyte 40 into hydrogen ions (H ⁺ ) and electrons (e ⁻ ). The hydrogen ion (H ⁺ ) reacts with the hydroxide ion (ОH ⁻ ) of the electrolyte 40 to form water (H ₂ О), and the electron (e ⁻ ) is moved to the positive electrode 10.
The catalyst supported on the catalyst layer 50 formed around the negative electrode 20 is one or more selected from catalysts containing precious metals such as platinum (Pt), palladium (Pd), rhodium (Rh), and ruthenium (Ru). Is preferable. The noble metal catalyst may be fine particles of metal, or may be a chelate catalyst in which a noble metal catalyst is coordinated and bonded. Among them, a platinum black catalyst formed by reducing fine particles (Adams' catalyst) of _{platinum oxide (PtO 2) can be preferably used.} The method of supporting the catalyst on carbon is, for example, a nano-sized state in which _{chloroplatinic acid (H 2} PtCl ₆ ) or ammonium chloroplatinate ((NH ₄ ) ₂ PtCl ₆ ) is melted in sodium nitrate (NaNO _3). After immersing in carbon to support platinum, wash with water to remove nitrate to obtain platinum oxide (PtO), and _{reduce with hydrogen (H 2} ) or formaldehyde (HCHO) to prepare platinum black (Pt). Good.
The carbon supporting the catalyst is applied to the surface of the negative electrode 20 via water or a liquid having a boiling point of 500 ° C. or lower, and is near the melting point of the magnesium alloy (500 to 1000 ° C.) under _{an argon (Ar) or nitrogen (N 2) atmosphere.} ), The catalyst layer can be fixed on the surface of the negative electrode 20.
The amount of the catalyst contained in the catalyst layer 50 is about 0.001% of the weight of the negative electrode 20.

A layer 60 of activated carbon is formed between the positive electrode 10 and the separator 30. The layer 60 of the activated carbon is a support that maintains the structure of the cell, and at the same time, is a pool of ^{electrons (e −) that move from the negative electrode 20.}
The nickel - the rate limiting step of the magnesium battery 1 is in the incorporation of oxygen (o ₂₎ in the positive electrode 10. Thus generated at the negative electrode 20, electrons transferred to the positive electrode 10 (e ^-) will wait the order in which they are oxidized. Activated carbon is ^{a mixture of conductive SP 2-} bonded carbon and non-conductive SP ^3- bonded carbon, and is non-conductive as a whole. At ^{the end of SP 3-} bonded carbon, there are many covalent-bonded branches with no bond partner. It is considered that this unbound branch retains the waiting electron (e ^−).
The layer 60 of activated carbon between the positive electrode 10 and the separator 30 adjusts ^{the amount of electrons (e −} ) supplied to the negative electrode 20 extending over the positive electrode 10, so that the violent oxidation / reduction reaction that occurs in the positive electrode 10 and the negative electrode 20 during charging is buffered. By doing so, safety can be ensured.

The chemical reaction that occurs when the nickel-magnesium battery 1 of the present invention is discharged and charged is as follows.
[Discharge]
・ Negative electrode Mg + 2OH ⁻ −> Mg (OH) ₂ + 2e ⁻
- electrolyte _{Mg (OH) 2 + EDTA -} > EDTA-Mg 2+ + 2OH -
・ Positive electrode O ₂ + 2H ₂ O + 4e ⁻ −> 4OH ⁻
〔charging〕
・ Positive electrode NiOOH + H ₂ O + e ⁻ −> Ni (OH) ₂ + OH ⁻
- electrolyte ^{EDTA-Mg 2+ + 2e - -} > Mg + EDTA
・ Negative electrode Mg (OH) ₂ + 2e ⁻ −> Mg + 2OH ⁻
At the time of discharge, in the negative electrode 20, magnesium (Mg) ^{reacts with hydroxide ions (ОH −} ) in the electrolyte to form magnesium hydroxide (Mg (OH) ₂ ) and electrons (e ⁻ ). Electrons (e ⁻ ) move in the electrolyte 40 toward the positive electrode 10.
Magnesium hydroxide (Mg (OH) ₂ ) becomes a chelate complex (EDTA-Mg ^{2+ ) of magnesium ions (Mg 2+} ) by ethylenediaminetetraacetic acid (EDTA), and the interaction with the ions existing in the electrolyte 40 is Extremely small.
At the time of discharge, in the positive electrode 10, oxygen (O ₂ ) in the atmosphere, water (H ₂ ^{O) in the electrolyte, and electrons (e −} ) transferred from the negative electrode 20 are combined to form a hydroxide ion (OH ^−). ) Will occur.
On the other hand, during charging, the positive electrode 10 uses the supplied electrons (e ⁻ ) to turn nickel oxide (NiOOH) into nickel hydroxide (Ni (OH) ₂ ), and in the electrolyte, a chelate complex (EDTA-Mg ²⁺ ). Ethylenediaminetetraacetic acid (EDTA), which formed a chelate complex (EDTA-Mg ²⁺ ), was formed into metallic magnesium (Mg) by combining magnesium ions (Mg ²⁺ ) that existed as a metal with the supplied electrons (e ^−). It releases magnesium ions (Mg) and becomes free.
During charging, the negative electrode 20 uses electrons supplied with magnesium hydroxide (Mg (OH) ₂ ) to convert it into metallic magnesium (Mg) and hydroxide ions (OH ^−).
[Example 1]

Hereinafter, examples of the nickel-magnesium battery of the present invention of the present invention will be described.
Positive electrode Nickel hydroxide (manufactured by Sumitomo Metal Mining Co., Ltd .: nickel powder) is crushed and dried to prepare fine powder of nickel oxide under pressure molding to create a porous nickel plate, which is pressed. A box-shaped container (cell) having a width of 100 mm, a length of 1000 mm, and a width of 1500 mm was prepared. This was sintered at 210 ° C. under a nitrogen atmosphere to obtain a positive electrode.
Negative electrode A negative electrode cut into a rectangle (thickness 2.5 mm) with a length of 950 mm and a width of 1450 mm from a flame-retardant magnesium alloy (manufactured by Kurimoto, Ltd.) containing 4% calcium, 7% aluminum, and 1% zinc. And said.
The catalyst layer chloroplatinic acid _{(H 2 PtCl 6 · 6H 2} O: Yoneyama Yakuhin Kogyo Co., Ltd.) Sodium nitrate: melted (NaNO ₃ manufactured by Wako Pure Chemical Industries, Ltd.), carbon black (Mitsubishi Chemical Corporation, brand : No.44) was immersed to support platinum, and then washed with water to remove nitrate to obtain platinum oxide (PtO), which was then immersed in formaldehyde (HCHO: manufactured by Wako Pure Chemical Industries, Ltd.). Platinum black (Pt) was prepared by expanding sales at 60 ° C. for 1 hour and reducing the mixture. After applying this suspension to both sides of the negative electrode, it was heated at 500 ° C. in a nitrogen atmosphere to fix the catalyst layer.

The negative electrode with the catalyst layer fixed on the surface of the separator was wrapped in handmade Japanese paper (Mino paper) and placed in the center of the cell made of nickel oxide on the positive electrode.
Electrolyte Potassium hydroxide (manufactured by Wako Pure Chemical Industries, Ltd.) and ethylenediaminetetraacetic acid (EDTA: manufactured by Tokyo Kasei Kogyo Co., Ltd.) are dissolved in deionized water to dissolve 24% by weight potassium hydroxide and 16% ethylenediaminetetraacetic acid (EDTA). Alkaline electrolytes containing were prepared. Activated carbon (manufactured by Kuraray Chemical Co., Ltd., product name: Kuraraycol (registered trademark), brand: PW, standard particle size: 150 μm or less) is suspended in this alkaline electrolyte and poured into the space between the positive electrode and the negative electrode. , An activated carbon layer impregnated with an electrolyte was formed.

Leads serving as terminals were provided on the positive and negative electrodes, and an ammeter, a voltmeter, and a resistor were connected to measure the amount of power generation.
As a result, it was found that the nickel-magnesium battery of the present invention had a weight energy density of 515 Wh / kg and a volume energy density of 550 Wh / L, and had a power capacity approximately twice that of the conventional lithium ion secondary battery. ..

1: Nickel-magnesium battery 10: Positive electrode 20: Negative electrode 30: Separator 40: Electrolyte 50: Catalyst layer 60: Activated carbon layer

Claims (6)

A positive electrode made of nickel oxide and
A negative electrode made of magnesium alloy and
A separator provided between the positive electrode and the negative electrode and
It is composed of an alkaline electrolyte filled between the positive electrode and the negative electrode.
A nickel-magnesium battery, characterized in that the electrolyte contains a ligand that forms a chelate with magnesium ions. The nickel-magnesium battery according to claim 1, wherein the ligand is ethylenediaminetetraacetic acid. The nickel-magnesium battery according to claim 1, further comprising a catalyst layer having carbon fine particles supporting a noble metal catalyst attached around the negative electrode. The nickel-magnesium battery according to claim 1, wherein the negative electrode is a flame-retardant magnesium alloy containing calcium. The nickel-magnesium battery according to claim 1, wherein the positive electrode is a porous molded body obtained by sintering nickel hydroxide. The nickel-magnesium battery according to claim 1, wherein a layer of activated carbon is formed between the positive electrode and the separator.

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