JP2014192078A - Electrolyte for alkali batteries, and alkali battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrolyte for alkali batteries and an alkali battery which allow superior charge and discharge cycle characteristics to be realized.SOLUTION: An electrolyte for alkali batteries comprises: a salt having a hydroxide ion conductivity; and water. As to the salt having a hydroxide ion conductivity, a molecular ion forms a cation, and a hydroxide ion makes an anion. An alkali battery comprises: a positive electrode; a negative electrode; and an electrolyte for alkali batteries. The electrolyte for alkali batteries includes: a salt having a hydroxide ion conductivity; and water. As to the salt having a hydroxide ion conductivity, a molecular ion forms a cation, and a hydroxide ion makes an anion.

Description

  The present invention relates to an alkaline battery electrolyte and an alkaline battery. More specifically, the present invention relates to an alkaline battery electrolyte applied to an alkaline battery represented by an alkaline secondary battery such as an air-zinc secondary battery or a nickel-zinc secondary battery.

  Conventionally, an alkaline zinc battery excellent in leakage resistance in which hydrogen gas generation on the negative electrode surface is suppressed, and an alkaline zinc battery excellent in leakage resistance and uniform zinc deposition in the negative electrode and excellent cycle life have been proposed. (See Patent Document 1).

  This alkaline zinc battery includes a negative electrode containing zinc or a zinc alloy as a negative electrode active material, a positive electrode, a separator, and an alkaline electrolyte. In this alkaline zinc battery, the alkaline electrolyte is a solution in which a cationic organic substance is contained in a 10% to 30% by weight potassium hydroxide aqueous solution.

JP 2003-297375 A

  However, in the alkaline zinc battery described in Patent Document 1, there is little effect of controlling the dissolution of the zinc discharge product of the negative electrode in the alkaline electrolyte, and the structure of the negative electrode changes due to charge / discharge, so that the charge / discharge is performed. There was a problem that the discharge cycle characteristics deteriorated.

  The present invention has been made in view of such problems of the prior art. And an object of this invention is to provide the electrolyte for alkaline batteries and alkaline battery which can implement | achieve the outstanding charging / discharging cycling characteristics.

  The inventors of the present invention have made extensive studies in order to achieve the above object. As a result, the above object can be achieved by comprising a salt having hydroxide ion conductivity in which the cation is a molecular ion and the anion is a hydroxide ion, and water. The headline and the present invention were completed.

  That is, the alkaline battery electrolyte of the present invention contains a salt having hydroxide ion conductivity and water. In the alkaline battery electrolyte of the present invention, in the salt having hydroxide ion conductivity, the cation is a molecular ion and the anion is a hydroxide ion.

  Moreover, the alkaline battery of this invention is equipped with a positive electrode, a negative electrode, and the electrolyte for alkaline batteries. And in the alkaline battery of this invention, the electrolyte for alkaline batteries contains the salt which has hydroxide ion conductivity, and water. In the alkaline battery of the present invention, the salt having hydroxide ion conductivity has a cation that is a molecular ion and an anion that is a hydroxide ion.

  According to the present invention, since the cation is a molecular ion and the anion is a hydroxide ion, a salt having hydroxide ion conductivity and water are included, so that excellent charge / discharge cycle characteristics are achieved. It is possible to provide an alkaline battery electrolyte and an alkaline battery that can be realized.

It is sectional drawing which shows typically the test cell or battery of each example. It is a graph which shows the solubility of the zinc discharge product of each example. It is a graph which shows the hydrogen overvoltage measurement result of each example. It is a scanning electron micrograph which shows the shape change of the zinc negative electrode before and after the charging / discharging test in each example.

  Hereinafter, an electrolytic solution for an alkaline battery and an alkaline battery using the same according to an embodiment of the present invention will be described.

  First, an alkaline battery electrolyte according to an embodiment of the present invention will be described in detail. The electrolyte for an alkaline battery according to the present embodiment includes a salt having hydroxide ion conductivity and water, the cation of the salt having hydroxide ion conductivity is a molecular ion, and the anion is a hydroxide. It is an ion. For example, when the alkaline battery electrolyte of the present invention is applied to an alkaline battery such as an air-zinc secondary battery or a nickel-zinc secondary battery, which will be described in detail later, the alkaline battery electrolyte of the present invention is a negative electrode during charging. In order to suppress the inhibition of zinc rearrangement, the structural change of the negative electrode due to charge / discharge can be suppressed. As a result, the alkaline battery can realize excellent charge / discharge cycle characteristics.

  At present, we believe that the effect is obtained by the following mechanism.

  When a salt composed of a metal ion that is not a molecular cation (for example, potassium cation) and a hydroxide ion, and a salt composed of a molecular cation and a hydroxide ion at the same molar concentration, generally, the molecular cation is Since the molecular weight is large or bulky compared to metal ions, the amount of water molecules in the electrolyte decreases (activity decreases). By reducing the water activity, the zinc discharge product of the negative electrode is difficult to dissolve in the alkaline electrolyte, and it becomes possible to suppress dendrite and zinc shape changes that occur during the deposition of zinc. It is considered that the charge / discharge cycle characteristics of the are improved.

  In addition, when a molecular cation is applied, the ion radius is large even with the same charge, that is, the ion size is large (bulky) and the ion charge density is small as compared with the metal ion. On the other hand, the distance between ions increases as ions increase. Here, the magnitude of the electrostatic force is proportional to the charge density and inversely proportional to the distance between ions. For this reason, as the ions become larger, the electrostatic force becomes smaller and the electrostatic interaction between the ions becomes weaker. As a result, salts containing metal ions become solid at high concentrations and are difficult to use as electrolytes, while salts containing molecular cations are liquid even at higher concentrations (in other words, less water). The state can be maintained, and the water activity can be reduced. And, by reducing the activity of water, the discharge product of the zinc of the negative electrode is difficult to dissolve in the alkaline electrolyte, and it becomes possible to suppress dendrite and zinc shape changes that occur during the deposition of zinc. It is considered that the long-term charge / discharge cycle characteristics are improved.

  However, the above mechanism is based on estimation. Therefore, it goes without saying that even if the above-described effect is obtained by a mechanism other than the above-described mechanism, it is included in the scope of the present invention.

  In addition, as a cation of a salt having hydroxide ion conductivity in the alkaline battery electrolyte of the present embodiment, an imidazolium derivative cation, a pyridinium derivative cation, a piperidinium derivative cation, an ammonium derivative cation, a phosphonium derivative cation or a sulfonium derivative cation, or these The cation which concerns on arbitrary combinations of these can be mentioned. A salt containing these cations can exhibit high ionic conductivity when used as an electrolyte salt. Therefore, energy efficiency can be improved when applied as an alkaline battery electrolyte.

  Here, the imidazolium derivative cation can be represented by the following general formula (1).

(In the formula, R1 and R3 are the same or different, and each represents at least one of an alkyl group and a fluoroalkyl group, and R2, R4, and R5 may be the same or different. And at least one selected from the group consisting of hydrogen, alkyl groups and fluoroalkyl groups.)

  In addition, as a preferable example of the imidazolium derivative cation, in the general formula (1), R1, R2, and R3 may be the same or different and each is at least one of an alkyl group and a fluoroalkyl group. Can be mentioned. Such a cation has high durability against the decomposition action in the electrolyte for alkaline batteries, and the long-term charge / discharge cycle characteristics of the alkaline battery are improved. R4 and R5 are preferably hydrogen from the viewpoint of solubility, but are not limited thereto.

  In addition, an alkyl group and a fluoroalkyl group can mention a C1-C21 thing, respectively, As a suitable example of an alkyl group and a fluoroalkyl group, a C1-C6 thing can be mentioned.

  The pyridinium derivative cation can be represented by the following general formula (2).

(In the formula, R6 represents one of an alkyl group and a fluoroalkyl group, and R7 to R11 may be the same or different, and at least one selected from the group consisting of hydrogen, an alkyl group, and a fluoroalkyl group. Indicates the species.)

  In addition, an alkyl group and a fluoroalkyl group can mention a C1-C21 thing, respectively, As a suitable example of an alkyl group and a fluoroalkyl group, a C1-C6 thing can be mentioned.

  Further, the piperidinium derivative cation can be represented by the following general formula (3).

(In the formula, R12 and R13 each represent at least one of an alkyl group and a fluoroalkyl group, which may be the same or different, and R14 to R18 may be the same or different, hydrogen, It represents at least one selected from the group consisting of an alkyl group and a fluoroalkyl group.)

  In addition, an alkyl group and a fluoroalkyl group can mention a C1-C21 thing, respectively, As a suitable example of an alkyl group and a fluoroalkyl group, a C1-C6 thing can be mentioned.

  The ammonium derivative cation can be represented by the following general formula (4).

(R19 to R22 in the formula each represents at least one of an alkyl group and a fluoroalkyl group, which may be the same or different.)

  In addition, an alkyl group and a fluoroalkyl group can mention a C1-C21 thing, respectively, As a suitable example of an alkyl group and a fluoroalkyl group, a C1-C6 thing can be mentioned.

  Furthermore, the phosphonium derivative cation can be represented by the following general formula (5).

(R23 to R26 in the formula each represent at least one of an alkyl group and a fluoroalkyl group, which may be the same or different.)

  In addition, an alkyl group and a fluoroalkyl group can mention a C1-C21 thing, respectively, As a suitable example of an alkyl group and a fluoroalkyl group, a C1-C6 thing can be mentioned.

  Furthermore, the sulfonium derivative cation can be represented by the following general formula (6).

(R27 to R29 in the formula each represent at least one of an alkyl group and a fluoroalkyl group, which may be the same or different.)

  In addition, an alkyl group and a fluoroalkyl group can mention a C1-C21 thing, respectively, As a suitable example of an alkyl group and a fluoroalkyl group, a C1-C6 thing can be mentioned.

  Such a cation has high durability against the decomposition action in the electrolyte for alkaline batteries, and the long-term charge / discharge cycle characteristics of the alkaline battery are improved. In addition, it effectively functions to suppress hydrogen generation, which is a side reaction during charging. It is.

  Next, an alkaline battery according to one embodiment of the present invention will be described in detail using an alkaline secondary battery as an example of the alkaline battery. The alkaline secondary battery according to this embodiment includes a positive electrode, a negative electrode, and the above-described electrolyte. With such a configuration, for example, when applied to an alkaline secondary battery such as an air-zinc secondary battery or a nickel-zinc secondary battery, the alkaline battery electrolyte is used in the rearrangement of zinc at the negative electrode during charging. In order to suppress inhibition, the structural change of the negative electrode due to charge / discharge can be suppressed. As a result, the alkaline battery can realize excellent charge / discharge cycle characteristics. The electrolyte may be in a liquid state or in a so-called gel state formed by impregnating a polymer material capable of holding a liquid, and any case is included in the scope of the present invention. .

  Hereinafter, each component other than the electrolyte described above will be described in detail.

  The positive electrode includes an air electrode composed of a carbon material, an oxygen reduction catalyst, and a binder, and a nickel electrode composed of a metal hydroxide mainly composed of nickel oxyhydroxide and a current collector such as nickel foam. Etc. can be mentioned as a suitable example. However, it is not limited to these, The conventionally well-known material used as a positive electrode of an alkaline secondary battery can be used suitably.

  In consideration of energy density, charge / discharge efficiency, and cycle life, the negative electrode preferably contains one or both of zinc and a zinc compound (such as zinc oxide) as the negative electrode active material. However, the material is not limited to these, and a conventionally known material used as a negative electrode of an alkaline secondary battery can be appropriately used.

  Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples.

Example 1
<Production of electrolyte (1.5M 1-ethyl-2,3-dimethylimidazolium hydroxide aqueous solution)>
The 1.5M 1-ethyl-2,3-dimethylimidazolium hydroxide aqueous solution was prepared by an anion exchange method using an ion exchange resin. First, a strong basic ion exchange resin (Amberlite IRA-400 OH type) was immersed in ion exchange water overnight, and then the ion exchange resin was set in a column tube. Subsequently, 1M potassium hydroxide (KOH) aqueous solution was gradually dropped into the column tube to perform an initial regeneration treatment of the ion exchange resin (the counter ion of the ion exchange resin was OH ⁻ ). Further, ion exchange water was gradually dropped onto the column tube to wash the ion exchange resin (confirmed that the pH of the effluent from the lower part of the column tube was 7). Furthermore, 1-ethyl-2,3-dimethylimidazolium bromide (1-Ethyl-2,3-dimethylimidazolium bromide) dissolved in ion-exchanged water was added dropwise to the column tube. Thereafter, the pH of the effluent at the bottom of the column tube was confirmed, and when the pH of the effluent increased, recovery of the effluent was started (hydroxide ions were formed by anion exchange of 1-Ethyl-2,3-dimethylimidazolium hydroxide). Since it became an anion, pH rose.) The effluent was collected until the pH approached 7. A part of the water in the obtained 1-ethyl-2,3-dimethylimidazolium hydroxide aqueous solution was removed by an evaporator. Then, after determining the OH ⁻ ion concentration in the aqueous solution by neutralization titration using 0.1M hydrochloric acid, ion exchange is performed so that the aqueous solution becomes 1.5M 1-ethyl-2,3-dimethylimidazolium hydroxide. Water was added to obtain the electrolyte of this example.

<Assembly of electrochemical measurement cell (1.5M 1-ethyl-2,3-dimethylimidazolium hydroxide aqueous solution)>
First, a working electrode was produced. A zinc plate (thickness: 1 mm) was cut into a predetermined size, and the surface was washed with ethanol to obtain a working electrode used in this example. Next, a counter electrode was produced. Nickel foam was used as a current collector, and a nickel oxyhydroxide paste was fixed to the current collector and molded into a counter electrode used in this example. The Hg / HgO electrode was used as a reference electrode. Thereafter, using these, a test cell of this example as shown in FIG. 1 was produced.

  That is, FIG. 1 is a cross-sectional view schematically showing a test cell. 1 is a working electrode, 2 is a counter electrode, 3 is an electrolyte, and 4 is a reference electrode. In the test cell, the working electrode 1 was disposed at the bottom of a cylindrical housing 5 and the bottom holder 6 was tightened. Next, the inside of the cylindrical casing 5 on which the working electrode 1 was mounted was filled with the electrolytic solution 3, and the lid 7 on which the counter electrode 2 and the reference electrode 4 were mounted was rotated on the cylindrical casing 5 and mounted and assembled.

[Anode polarization test (evaluation of solubility of zinc discharge products)]
In the anodic reaction (discharge reaction) of zinc, Zn (OH) ₄ ²⁻ is generated as an intermediate soluble component during the reaction (the following formula [1]), and Zn (OH) ₄ ²⁻ on the electrode surface as the reaction proceeds. This is a dissolution precipitation reaction that precipitates on the electrode surface as ZnO (the following formula [2]). Accordingly, the solubility of the zinc discharge product was evaluated by measuring the reaction time of the following formula [1] by conducting a constant current anodic polarization test, and evaluating the time as the solubility of the zinc discharge product.

Zn + 4OH ⁻ = Zn (OH) ₄ ² + 2e ⁻ (E ₀ = −1.25 V) [1]
Zn (OH) ₄ ²⁻ = ZnO + H ₂ O + 2OH ⁻ [2]

  In a specific anodic polarization test, after the open circuit voltage of the test cell is stabilized, an electrochemical measurement system is used to perform anodic polarization at a constant current of 1 mA, and the potential of the working electrode is −1.18 V (vs. The test was terminated when Hg / HgO, the same applies hereinafter), and the time until that time was measured. FIG. 2 shows the evaluation results of the solubility of the zinc discharge product of this example when the solubility of the zinc discharge product calculated from the anodic polarization test with the electrolyte of Comparative Example 1 is 1.

[Hydrogen overvoltage measurement]
The hydrogen overvoltage measurement was performed by a method of scanning the potential from the open circuit voltage to −1.50 V at a scanning speed of 1 mV / sec using an electrochemical measurement system after waiting for the open circuit voltage of the test cell to stabilize. . The measurement result of the hydrogen generation current is shown in FIG.

<Production of battery (1.5M 1-ethyl-2,3-dimethylimidazolium hydroxide aqueous solution)>
First, a positive electrode was produced. Nickel foam was used as a current collector, and a nickel oxyhydroxide paste was fixed to the current collector and molded to obtain a positive electrode used in this example. Next, a negative electrode was produced. A zinc plate (thickness: 1 mm) as a negative electrode active material was cut into a predetermined size, and the surface was washed with ethanol to obtain a negative electrode used in this example. The Hg / HgO electrode was used as a reference electrode. Thereafter, using these, a battery of this example as shown in FIG. 1 was produced.

  That is, FIG. 1 is a sectional view schematically showing the battery. 1 is a negative electrode, 2 is a positive electrode, 3 is an electrolyte, and 4 is a reference electrode. In the test cell, the negative electrode 1 was disposed at the bottom of the cylindrical casing 5 and the bottom holder 6 was tightened. Next, the inside of the cylindrical casing 5 on which the negative electrode 1 was mounted was filled with the electrolyte 3, and the lid 7 on which the positive electrode 2 and the reference electrode 4 were mounted was rotated on the cylindrical casing 5 and mounted and assembled.

[Charge / discharge test]
The charge / discharge test waits for the open circuit voltage of the battery to stabilize, uses an electrochemical measurement system, sandwiches a pause of 10 minutes at a current range of −1.18 V to −1.46 V and a current value of 1 mA, A charge / discharge test was conducted starting from discharge at room temperature. After the 5-cycle charge / discharge test, the zinc negative electrode was taken out, washed with ion-exchanged water, dried, and the change in the shape of the zinc negative electrode was observed using a scanning electron microscope. The result is shown in FIG. FIG. 5 also shows the zinc negative electrode before the charge / discharge test (see FIG. 5A).

(Example 2)
<Production of Electrolyte (1.5 M Tetrabutylammonium Hydroxide Aqueous Solution)>
Preparation of 1.5M tetrabutylammonium hydroxide aqueous solution was performed using commercially available tetrabutylammonium hydroxide aqueous solution. First, a part of water in the tetrabutylammonium hydroxide aqueous solution was removed by an evaporator. Subsequently, the OH ⁻ ion concentration in the aqueous solution was determined by neutralization titration using 0.1M hydrochloric acid. Thereafter, ion-exchanged water was added to obtain a 1.5M tetrabutylammonium hydroxide aqueous solution to obtain an electrolyte of this example.

<Assembly of electrochemical measurement cell (1.5M tetrabutylammonium hydroxide aqueous solution)>
A cell configuration similar to that of Example 1 was used except that the electrolyte of this example was used instead of the electrolyte of Example 1.

[Anode polarization test (evaluation of solubility of zinc discharge products)]
An anodic polarization test was carried out in the same manner as in Example 1. The evaluation results of the solubility of the zinc discharge product calculated from the anodic polarization test are shown in FIG.

[Hydrogen overvoltage measurement]
Hydrogen overvoltage measurement was carried out in the same manner as in Example 1. The measurement result of the hydrogen generation current is shown in FIG.

(Example 3)
<Production of Electrolyte (1.5M Tetrabutylphosphonium Hydroxide Aqueous Solution)>
The 1.5M tetrabutylphosphonium hydroxide aqueous solution was prepared using a commercially available tetrabutylphosphonium hydroxide aqueous solution. First, a part of water in the tetrabutylphosphonium hydroxide aqueous solution was removed by an evaporator. Subsequently, the OH ⁻ ion concentration in the aqueous solution was determined by neutralization titration using 0.1M hydrochloric acid. Thereafter, ion-exchanged water was added so as to obtain a 1.5 M tetrabutylphosphonium hydroxide aqueous solution to obtain an electrolyte of this example.

<Assembly of electrochemical measurement cell (1.5M tetrabutylphosphonium hydroxide aqueous solution)>
A cell configuration similar to that of Example 1 was used except that the electrolyte solution of this example was used instead of the electrolyte of Example 1.

[Anode polarization test (evaluation of solubility of zinc discharge products)]
An anodic polarization test was carried out in the same manner as in Example 1. The evaluation results of the solubility of the zinc discharge product calculated from the anodic polarization test are shown in FIG.

[Hydrogen overvoltage measurement]
Hydrogen overvoltage measurement was carried out in the same manner as in Example 1. The measurement result of the hydrogen generation current is shown in FIG.

(Comparative Example 1)
<Preparation of electrolyte (1.5M potassium hydroxide (KOH) aqueous solution)>
Preparation of 1.5M potassium hydroxide (KOH) aqueous solution was performed using commercially available potassium hydroxide (KOH). Potassium hydroxide (KOH) and ion-exchanged water were weighed and mixed in a volumetric flask so as to obtain a 1.5M potassium hydroxide (KOH) aqueous solution to obtain an electrolyte of this example.

<Assembly of electrochemical measurement cell (1.5M potassium hydroxide (KOH) aqueous solution)>
A cell configuration similar to that of Example 1 was used except that the electrolyte of this example was used instead of the electrolyte of Example 1.

[Anode polarization test (evaluation of solubility of zinc discharge products)]
An anodic polarization test was carried out in the same manner as in Example 1. The evaluation results of the solubility of the zinc discharge product calculated from the anodic polarization test are shown in FIG.

[Hydrogen overvoltage measurement]
Hydrogen overvoltage measurement was carried out in the same manner as in Example 1. The measurement result of the hydrogen generation current is shown in FIG.

<Production of battery (1.5M potassium hydroxide (KOH) aqueous solution)>
The battery configuration was the same as that of Example 1, except that the electrolyte of this example was used instead of the electrolyte of Example 1.

[Charge / discharge test]
A charge / discharge test was carried out in the same manner as in Example 1. After the 5-cycle charge / discharge test, the zinc negative electrode was taken out, washed in the same manner as in Example 1, dried, and the change in the shape of the zinc negative electrode was observed using a scanning electron microscope. The result is shown in FIG.

(Comparative Example 2)
<Preparation of electrolyte (1.5 M potassium hydroxide (KOH) +10 mass% tetra-n-butylammonium bromide aqueous solution)>
4M potassium hydroxide (KOH) aqueous solution, tetra-n-butylammonium bromide and ion-exchanged water were added so that a mixed aqueous solution of 1.5M potassium hydroxide (KOH) and 10% by mass tetra-n-butylammonium bromide was obtained. , Weighed and mixed in a volumetric flask to obtain the electrolyte of this example.

<Assembly of electrochemical measurement cell (1.5 M potassium hydroxide (KOH) +10 mass% tetra-n-butylammonium bromide aqueous solution)>
A cell configuration similar to that of Example 1 was used except that the electrolyte solution of this example was used instead of the electrolyte of Example 1.

[Anode polarization test (evaluation of solubility of zinc discharge products)]
An anodic polarization test was carried out in the same manner as in Example 1. The evaluation results of the solubility of the zinc discharge product calculated from the anodic polarization test are shown in FIG.

[Hydrogen overvoltage measurement]
Hydrogen overvoltage measurement was carried out in the same manner as in Example 1. The measurement result of the hydrogen generation current is shown in FIG.

  From the results of the solubility evaluation of the zinc discharge product by the anodic polarization test in FIG. 2, the cations of Examples 1 to 3 belonging to the scope of the present invention are molecular ions and the anions are hydroxide ions. The electrolyte using the salt having oxide ion conductivity effectively controls the solubility of the zinc discharge product as compared with the electrolyte using the salt in which the cation of Comparative Example 1 outside the present invention is potassium ion. I understand that An electrolyte using a salt having hydroxide ion conductivity in which the cation of Examples 1 to 3 belonging to the scope of the present invention is a molecular ion and the anion is a hydroxide ion is not included in the present invention. It can be seen that the solubility of the zinc discharge product is effectively controlled even when the cation of Comparative Example 2 is a molecular ion or compared with an electrolyte using a salt whose anion is not a hydroxide ion. .

  Moreover, from the hydrogen overvoltage measurement result of FIG. 3, the salt which has hydroxide ion conductivity whose cation of Examples 1-3 which belong to the scope of the present invention is a molecular ion, and whose anion is a hydroxide ion. Compared with the electrolyte using the salt in which the cation of Comparative Example 1 outside the present invention is a potassium ion, the hydrogen generation current value is small and the hydrogen generation overvoltage is large. Recognize. From this result, by using the alkaline battery electrolyte of the present invention, the generation of hydrogen during the charging of zinc is effectively suppressed, the charge and discharge efficiency of the zinc negative electrode is increased, and the internal pressure of the battery is increased by the generation of hydrogen gas. It can be seen that the leakage of the electrolyte due to can be effectively suppressed.

  Furthermore, from the observation result of the surface of the zinc negative electrode before and after the charge / discharge test by the scanning electron microscope in FIG. 4, the alkaline battery electrolyte of Example 1 (see FIG. 4B) belonging to the scope of the present invention is present. Compared with the electrolyte for alkaline batteries of Comparative Example 1 (see FIG. 4C), it can be seen that the change in the shape of the zinc negative electrode surface by the charge / discharge test is effectively suppressed. That is, since the rearrangement of the zinc at the negative electrode is difficult to be inhibited during charging, the effect of improving the charge / discharge cycle characteristics can be obtained.

  The present invention has been described with some embodiments and examples. However, the present invention is not limited to these, and various modifications are possible within the scope of the gist of the present invention.

  For example, in the above-described embodiments, a nickel-zinc secondary battery has been described as an example of an alkaline battery, but the present invention can also be applied to an air-zinc secondary battery.

  Further, for example, the configurations described in the above-described embodiments and examples are not limited to the respective embodiments and examples. For example, the configurations of the embodiments may be combined other than the above-described embodiments, The details of the working electrode, the counter electrode, and the electrolyte can be changed.

1 Working electrode (or negative electrode)
2 Counter electrode (or positive electrode)
3 Electrolyte 4 Reference electrode 5 Housing 6 Bottom holder 7 Lid

Claims (4)

A salt having hydroxide ion conductivity and water,
In the electrolyte for alkaline batteries, the salt having hydroxide ion conductivity is characterized in that a cation is a molecular ion and an anion is a hydroxide ion.   The cation of the salt having hydroxide ion conductivity is at least one cation selected from the group consisting of an imidazolium derivative cation, a pyridinium derivative cation, a piperidinium derivative cation, an ammonium derivative cation, a phosphonium derivative cation, and a sulfonium derivative cation. The electrolyte for alkaline batteries according to claim 1, wherein the electrolyte is used. The alkaline battery electrolyte according to claim 2, wherein the imidazolium derivative cation is an imidazolium derivative cation represented by the following general formula (1).

(In the formula, R1, R2 and R3 each represent at least one of an alkyl group and a fluoroalkyl group which may be the same or different, and R4 and R5 each represent hydrogen.) A positive electrode, a negative electrode, and an alkaline battery electrolyte;
The alkaline battery electrolyte includes a salt having hydroxide ion conductivity and water,
In the alkaline ion battery, the salt having hydroxide ion conductivity is characterized in that a cation is a molecular ion and an anion is a hydroxide ion.

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