JP2013084349A - Electrolyte for alkaline battery, and alkaline battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrolyte for an alkaline battery, which is capable of achieving a long-term charge/discharge cycle and excellent charge/discharge efficiency by suppressing generation of a hydrogen gas due to a side reaction, dendrites generated during deposition of zinc, and a shape change of zinc, and to provide an alkaline battery.SOLUTION: The electrolyte for an alkaline battery contains at least an organic substance having two or more carbon atoms and one or more hydroxyl groups in the molecule. The alkaline battery comprises the electrolyte for an alkaline battery, which contains at least the organic substance having two or more carbon atoms and one or more hydroxyl groups in the molecule.

Description

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

In recent years, in order to cope with air pollution and global warming, reduction of carbon dioxide emissions has been strongly desired.
In the automobile industry, there is a great expectation for reducing carbon dioxide emissions by introducing electric vehicles (EV) and hybrid electric vehicles (HEV). It is actively done.
As a secondary battery for driving a motor, a lithium ion secondary battery having a high energy density has attracted attention, and is currently being developed rapidly.
However, electric vehicles are required to have a cruising distance per charge comparable to that of gasoline vehicles as well as the performance of gasoline vehicles, and the technological achievement of conventional lithium ion secondary batteries has greatly reached the target. It has been pointed out that it is difficult.
Therefore, metal-air batteries are attracting attention as batteries that can achieve higher energy density than lithium ion secondary batteries.

However, the metal-air battery has a problem that the life of the charge / discharge cycle is very short.
For example, in a zinc-air battery using an aqueous electrolyte, it has been pointed out that hydrogen gas generated by side reactions, dendrites generated during zinc deposition, and shape changes are the causes of the short charge / discharge cycle life.

  Conventionally, it has been proposed to add methanol to an electrolytic solution for the purpose of suppressing a change in the shape of zinc (see Non-Patent Document 1).

M.M. A. Dziecuch, et al. "Rechargeable Cells with Modified MnO2 Cathodes" Journal of The Electrochemical Society, 135, 10, (1988).

  However, in the manganese dioxide-zinc secondary battery described in Non-Patent Document 1, although the shape change of zinc can be suppressed by adding methanol to the electrolytic solution, hydrogen due to the addition of methanol There is no description about suppression of gas generation. Therefore, the present inventors have confirmed that there is a problem that hydrogen gas is easily generated when methanol is added to the electrolytic solution.

  The present invention has been made in view of such problems of the prior art. The object of the present invention is to suppress the generation of hydrogen gas caused by side reactions, dendrites generated during the precipitation of zinc, and the shape change of zinc, and to provide a long charge / discharge cycle and excellent charge / discharge efficiency. The object is to provide an alkaline battery electrolyte and an alkaline battery that can be realized.

The inventors of the present invention have made extensive studies in order to achieve the above object.
As a result, the inventors have found that the above object can be achieved by including at least an organic substance having two or more carbon atoms and one or more hydroxyl groups in the molecule, and has completed the present invention. .

  That is, the alkaline battery electrolyte of the present invention contains at least an organic substance having two or more carbon atoms and one or more hydroxyl groups in the molecule.

  Moreover, the alkaline battery of this invention has the electrolyte solution for alkaline batteries of the said invention.

According to the present invention, the structure includes at least an organic substance having two or more carbon atoms and one or more hydroxyl groups in the molecule.
Therefore, generation of hydrogen gas caused by side reaction, dendrite generated during the precipitation of zinc, and shape change of zinc are suppressed, and an electrolytic solution for an alkaline battery that can realize a long charge / discharge cycle and excellent charge / discharge efficiency, and An alkaline battery can be provided.

It is sectional drawing which shows typically the test cell of each example. Cycle characteristic evaluation results in charge / discharge tests of Examples 1 to 6, Comparative Example 1 and Comparative Example 2 (Calculating charge / discharge efficiency from the ratio of charge capacity to discharge capacity, and charge / discharge efficiency is 120% or more or 80% The cycle test of the charge / discharge test was performed until the following was obtained. It is a graph which shows the hydrogen overvoltage measurement result (The electric current value by hydrogen generation in -2.00V) of Example 1- Example 6, the comparative example 1, and the comparative example 2. FIG. Cycle characteristic evaluation results in charge / discharge tests of Example 2, Example 7 and Example 8 (until the charge / discharge efficiency is calculated from the ratio of the charge capacity to the discharge capacity, until the charge / discharge efficiency becomes 120% or more or 80% or less The cycle test of the charge / discharge test was conducted. Cycle characteristic evaluation results in charge / discharge tests of Example 4, Example 9 and Example 10 (until the charge / discharge efficiency is calculated from the ratio of the charge capacity to the discharge capacity, until the charge / discharge efficiency becomes 120% or more or 80% or less The cycle test of the charge / discharge test was conducted. Results of cycle characteristic evaluation in charge / discharge tests of Example 6 and Example 11 (calculation of charge / discharge efficiency from the ratio of charge capacity to discharge capacity, and charge / discharge test until charge / discharge efficiency is 120% or more, or 80% or less The cycle test was conducted.). It is a scanning electron micrograph of the zinc negative electrode surface after the charging / discharging test (5 cycles) in Examples 12-15.

  Hereinafter, an alkaline battery electrolyte and an alkaline battery according to an embodiment of the present invention will be described in detail.

First, an alkaline battery electrolyte according to an embodiment of the present invention will be described in detail.
In addition to the alkaline electrolyte, the alkaline battery electrolyte of the present embodiment contains at least an organic substance having two or more carbon atoms and one or more hydroxyl groups in the molecule.
With such a configuration, when applied to an alkaline secondary battery such as an air-zinc secondary battery or a nickel-zinc secondary battery, hydrogen gas generated due to side reactions, dendrites generated during zinc deposition, zinc It is possible to suppress the change in the shape. As a result, the alkaline battery to which the alkaline battery electrolyte of the present invention is applied can realize a long-term charge / discharge cycle and excellent charge / discharge efficiency.

  Hereinafter, each component will be described in detail.

Examples of the alkaline electrolyte include those obtained by dissolving an alkali salt in water. Preferred examples of the alkali salt include potassium hydroxide (KOH), sodium hydroxide (NaOH) and lithium hydroxide (LiOH). These can be used individually by 1 type or in combination of 2 or more types.
In the present invention, for example, it is only necessary that the redox reaction using zinc or a zinc compound as the negative electrode active material and the redox reaction can be repeatedly performed, and the present invention is not limited thereto.

  The organic substance is not particularly limited as long as it has two or more carbon atoms and one or more hydroxyl groups in the molecule. For example, C2-C6 monohydric alcohol, bihydric alcohol, trihydric alcohol, and polyhydric alcohol of 6 or less can be mentioned. If the alcohol has more than 6 carbon atoms, it tends to be difficult to dissolve with the electrolyte solution, and the desired effect is hardly exhibited. That is, when the number of carbon atoms is 6 or less, an alkaline aqueous solution and an organic substance can be mixed at an arbitrary ratio, and an alkaline electrolyte obtained according to a desired battery system can be easily applied. On the other hand, for methanol having one carbon, a side reaction that generates hydrogen gas during charging is likely to occur. Moreover, when it has 6 or more hydroxyl groups, there exists a tendency for the hydrogen bond strength of organic substance to increase, and when it adds to alkaline aqueous solution, the viscosity of alkaline electrolyte increases. Therefore, it is preferable that the number of hydroxyl groups in the molecule is 5 or less from the viewpoint of suppressing a decrease in the ionic conductivity of the electrolyte and suppressing an increase in the internal resistance of the battery.

  The organic substance is preferably composed of a linear organic substance. By using a straight-chain organic substance, the acid dissociation constant of the hydroxyl group can be lowered, and the hydroxyl group can be stably present in the alkali, so that it exhibits a sufficient effect in a long charge / discharge cycle. be able to.

  Examples of the monohydric alcohol having 2 to 6 carbon atoms include ethanol, 1-propanol, 1-butanol, 2-methyl-1-propanol, 1-pentanol, 2-methyl-1-butanol, and 3-methyl-1. -Butanol, 2,2-dimethyl-1-propanol, 1-hexanol, 2-methyl-1-pentanol, 4-methyl-1-pentanol, 3-methyl-1-pentanol, 2-ethyl-1- Chain structure alcohols having a hydroxyl group at the 1-position carbon atom, such as butanol, 2,3-dimethyl-1-butanol, 2,2-dimethyl-1-butanol, 3,3-dimethyl-1-butanol, etc. Etc., 2-propanol, 2-butanol, 2-methyl-2-propanol, 2-pentanol, 2-methyl-2-butanol, 3-methyl-2 Butanol, 2-hexanol, 2-methyl-2-pentanol, 4-methyl-2-pentanol, 3-methyl-2-pentanol, 2,3-dimethyl-2-butanol, 3,3-dimethyl-2 -Chain structure alcohols having a hydroxyl group at the 2-position carbon atom such as butanol, 3-pentanol, 3-hexanol, 2-methyl-3-pentanol, 3-methyl-3-pentanol, etc. A chain-structured alcohol having a hydroxyl group at the carbon atom at the 3-position, such as cyclopentanol, cyclopentylmethanol, 1-methyl-cyclohexanol, 2-methyl-cyclohexanol, and 3-methyl-cyclohexanol. Mention may be made of alcohols of the structure.

  Examples of the dihydric alcohol or trihydric alcohol having 2 to 6 carbon atoms include those having a structure in which a hydrogen atom bonded to a carbon atom of the monohydric alcohol described above is substituted with a hydroxyl group. Typical examples include 1,2-ethanediol, 1,2-propanediol, 1,3-propanediol, 1,2,3-propanetriol and the like.

Moreover, it is preferable to apply what has a hydroxyl group couple | bonded with the carbon atom of the 2nd-position as an organic substance in the electrolyte solution for alkaline batteries of this embodiment.
With such a configuration, it is possible to realize a long-term charge / discharge cycle and excellent charge / discharge efficiency while further suppressing hydrogen generation due to side reactions.
Specific preferred examples include 2-propanol, 1,2-ethanediol, 1,2-propanediol, 1,2,3-propanetriol and the like. However, the present invention is not limited to these.

Furthermore, it is preferable to apply a dihydric alcohol as the organic substance in the alkaline battery electrolyte of the present embodiment.
With such a configuration, hydrogen generation due to side reactions can be further suppressed.
Specific preferred examples include 1,2-ethanediol and 1,2-propanediol. In particular, it is preferable to apply 1,2-ethanediol (ethylene glycol).

  The concentration of the organic substance in the alkaline battery electrolyte of the present embodiment is preferably 0.5 to 5 mol / L (hereinafter, “mol / L” may be referred to as “M”). If the concentration is lower than 0.5M, the effect of controlling the solubility of the zinc discharge product due to the addition of the organic substance may hardly be obtained. Therefore, there is a possibility that the shape change of zinc due to the charge / discharge cycle cannot be suppressed. Further, at a concentration higher than 5M, the solubility of alkali salts such as potassium hydroxide is lowered, so that it is difficult to adjust the electrolyte having high conductivity, and the internal resistance of the battery may be increased.

Next, an alkaline battery according to an 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 of the present embodiment includes a positive electrode, a negative electrode including one or both of zinc and a zinc compound (for example, zinc oxide) as a negative electrode active material, and an electrolyte including the above-described electrolytic solution. .
In addition, as electrolyte, it may consist only of the electrolyte solution mentioned above, and the polymer material which can hold | maintain electrolyte solution may be included.
With such a configuration, when applied to an alkaline secondary battery such as an air-zinc secondary battery or a nickel-zinc secondary battery, hydrogen gas generated due to side reactions, dendrite generated during zinc deposition, zinc The shape change can be suppressed. As a result, a long charge / discharge cycle and excellent charge / discharge efficiency can be realized.

  Hereinafter, each component other than the electrolyte solution 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 this, 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.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further in detail, this invention is not limited to these Examples.

Example 1
<Preparation of electrolyte (1M KOH + 4M ethanol aqueous solution)>
A 4M KOH aqueous solution, ethanol and ion-exchanged water were weighed and mixed in a volumetric flask so that a mixed aqueous solution of 1M KOH and 4M ethanol was obtained, and this was used as an electrolyte.

<Production of battery (1M KOH + 4M ethanol 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 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 positive electrode, 2 is a negative electrode, 3 is an electrolyte, and 10 is a reference electrode. In the test cell, the negative electrode 2 was disposed at the bottom of the cylindrical casing 11, and the bottom holder 12 was fastened and attached. Next, the inside of the cylindrical casing 11 on which the negative electrode 2 was mounted was filled with the electrolytic solution 3, and the lid 13 on which the positive electrode 1 and the reference electrode 10 were mounted was rotated on the cylindrical casing 11 and mounted and assembled.

[Charge / discharge test]
The charge / discharge test waits for the open circuit voltage of the test cell to stabilize, and uses an electrochemical measurement system to measure a voltage range of −1.18 V (vs. Hg / HgO, the same applies hereinafter) to −1.46 V, negative electrode A charge / discharge test was conducted by starting a discharge at room temperature with a pause of 10 minutes at a current value of 5 mA / cm ² per area. The charge / discharge efficiency was calculated from the ratio of the charge capacity to the discharge capacity, and the charge / discharge test cycle was repeated until the charge / discharge efficiency was 120% or more or 80% or less. FIG. 2 shows the cycle characteristic evaluation results of the charge / discharge test.

[Hydrogen overvoltage measurement]
The hydrogen overvoltage was measured by waiting for the open circuit voltage of the test cell to stabilize and then scanning the potential from the open circuit voltage to -2.00 V at a scan rate of 1 mV / sec using an electrochemical measurement system. The current value due to hydrogen generation at -2.00V is shown in FIG.

(Example 2)
<Preparation of electrolytic solution (1M KOH + 4M 1-propanol aqueous solution)>
A 4M KOH aqueous solution, 1-propanol and ion-exchanged water were weighed and mixed in a volumetric flask so as to be a mixed aqueous solution of 1M KOH and 4M 1-propanol, and this was used as an electrolytic solution.

<Production of battery (1M KOH + 4M 1-propanol aqueous solution)>
The cell configuration was the same as in Example 1 except that this electrolytic solution was used instead of the electrolytic solution in Example 1.

[Charge / discharge test]
A charge / discharge test was carried out in the same manner as in Example 1. 2 and 4 show the cycle characteristic evaluation results of the charge / discharge test.

[Hydrogen overvoltage measurement]
Hydrogen overvoltage measurement was carried out in the same manner as in Example 1. FIG. 3 shows the current value due to hydrogen generation at -2.00V.

(Example 3)
<Preparation of electrolyte (1M KOH + 4M 2-propanol aqueous solution)>
A 4M KOH aqueous solution, 2-propanol and ion-exchanged water were weighed and mixed in a volumetric flask so as to be a mixed aqueous solution of 1M KOH and 4M 2-propanol, and this was used as an electrolytic solution.

<Production of battery (1M KOH + 4M 2-propanol aqueous solution)>
The cell configuration was the same as in Example 1 except that this electrolytic solution was used instead of the electrolytic solution in Example 1.

[Charge / discharge test]
A charge / discharge test was carried out in the same manner as in Example 1. FIG. 2 shows the cycle characteristic evaluation results of the charge / discharge test.

[Hydrogen overvoltage measurement]
Hydrogen overvoltage measurement was carried out in the same manner as in Example 1. FIG. 3 shows the current value due to hydrogen generation at -2.00V.

Example 4
<Preparation of Electrolytic Solution (1M KOH + 4M 1,2-ethanediol aqueous solution)>
A 4M KOH aqueous solution, 1,2-ethanediol and ion-exchanged water were weighed and mixed in a volumetric flask so as to be a mixed aqueous solution of 1M KOH and 4M 1,2-ethanediol, and this was used as an electrolytic solution.

<Production of battery (1M KOH + 4M 1,2-ethanediol aqueous solution)>
The cell configuration was the same as in Example 1 except that this electrolytic solution was used instead of the electrolytic solution in Example 1.

[Charge / discharge test]
A charge / discharge test was carried out in the same manner as in Example 1. 2 and 5 show the results of evaluating the cycle characteristics of the charge / discharge test.

[Hydrogen overvoltage measurement]
Hydrogen overvoltage measurement was carried out in the same manner as in Example 1. FIG. 3 shows the current value due to hydrogen generation at -2.00V.

(Example 5)
<Preparation of Electrolytic Solution (1M KOH + 4M 1,2-propanediol aqueous solution)>
A 4M KOH aqueous solution, 1,2-propanediol and ion-exchanged water were weighed and mixed in a volumetric flask so as to be a mixed aqueous solution of 1M KOH and 4M 1,2-propanediol, and this was used as an electrolyte.

<Production of battery (1M KOH + 4M 1,2-propanediol aqueous solution)>
The cell configuration was the same as in Example 1 except that this electrolytic solution was used instead of the electrolytic solution in Example 1.

[Charge / discharge test]
A charge / discharge test was carried out in the same manner as in Example 1. FIG. 2 shows the cycle characteristic evaluation results of the charge / discharge test.

[Hydrogen overvoltage measurement]
Hydrogen overvoltage measurement was carried out in the same manner as in Example 1. FIG. 3 shows the current value due to hydrogen generation at -2.00V.

(Example 6)
<Preparation of electrolyte solution (1M KOH + 2M 1,2,3-propanetriol aqueous solution)>
4M KOH aqueous solution, 1,2,3-propanetriol and ion-exchanged water are weighed and mixed in a volumetric flask so as to be a mixed aqueous solution of 1M KOH and 2M 1,2,3-propanetriol, and this is electrolyzed. A liquid was used.

<Production of battery (1M KOH + 2M 1,2,3-propanetriol aqueous solution)>
The cell configuration was the same as in Example 1 except that this electrolytic solution was used instead of the electrolytic solution in Example 1.

[Charge / discharge test]
A charge / discharge test was carried out in the same manner as in Example 1. FIG. 2 shows the cycle characteristic evaluation results of the charge / discharge test.

[Hydrogen overvoltage measurement]
Hydrogen overvoltage measurement was carried out in the same manner as in Example 1. FIG. 3 shows the current value due to hydrogen generation at -2.00V.

(Comparative Example 1)
<Preparation of electrolyte solution (1M KOH aqueous solution)>
1M KOH was used as the electrolyte.

<Production of battery (1M KOH aqueous solution)>
A cell configuration similar to that of Example 1 was used except that 1M KOH was used as the electrolyte 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. FIG. 2 shows the cycle characteristic evaluation results of the charge / discharge test.

[Hydrogen overvoltage measurement]
Hydrogen overvoltage measurement was carried out in the same manner as in Example 1. FIG. 3 shows the current value due to hydrogen generation at -2.00V.

(Comparative Example 2)
<Preparation of electrolyte (1M KOH + 4M aqueous methanol solution)>
A 4M KOH aqueous solution, methanol and ion-exchanged water were weighed and mixed in a volumetric flask so as to be a mixed aqueous solution of 1M KOH and 4M methanol, and this was used as an electrolyte.

<Production of battery (1M KOH + 4M aqueous methanol solution)>
The cell configuration was the same as in Example 1 except that this electrolytic solution was used instead of the electrolytic solution in Example 1.

[Charge / discharge test]
A charge / discharge test was carried out in the same manner as in Example 1. FIG. 2 shows the cycle characteristic evaluation results of the charge / discharge test.

[Hydrogen overvoltage measurement]
Hydrogen overvoltage measurement was carried out in the same manner as in Example 1. FIG. 3 shows the current value due to hydrogen generation at -2.00V.

(Example 7)
<Preparation of electrolytic solution (1M KOH + 2M 1-propanol aqueous solution)>
A 4M KOH aqueous solution, 1-propanol and ion-exchanged water were weighed and mixed in a volumetric flask so as to be a mixed aqueous solution of 1M KOH and 2M 1-propanol, and this was used as an electrolytic solution.

<Production of battery (1M KOH + 2M 1-propanol aqueous solution)>
The cell configuration was the same as in Example 1 except that this electrolytic solution was used instead of the electrolytic solution in Example 1.

[Charge / discharge test]
A charge / discharge test was carried out in the same manner as in Example 1. FIG. 4 shows the cycle characteristic evaluation results of the charge / discharge test.

(Example 8)
<Preparation of electrolyte solution (1M KOH + 1M 1-propanol aqueous solution)>
A 4M KOH aqueous solution, 1-propanol and ion-exchanged water were weighed and mixed in a volumetric flask so as to be a mixed aqueous solution of 1M KOH and 1M 1-propanol, and this was used as an electrolytic solution.

<Production of battery (1M KOH + 1M 1-propanol aqueous solution)>
The cell configuration was the same as in Example 1 except that this electrolytic solution was used instead of the electrolytic solution in Example 1.

[Charge / discharge test]
A charge / discharge test was carried out in the same manner as in Example 1. FIG. 4 shows the cycle characteristic evaluation results of the charge / discharge test.

Example 9
<Preparation of Electrolytic Solution (1M KOH + 2M 1,2-ethanediol aqueous solution)>
A 4M KOH aqueous solution, 1,2-ethanediol and ion-exchanged water were weighed and mixed in a volumetric flask so that a mixed aqueous solution of 1M KOH and 2M 1,2-ethanediol was obtained, and this was used as an electrolyte.

<Production of battery (1M KOH + 2M 1,2-ethanediol aqueous solution)>
The cell configuration was the same as in Example 1 except that this electrolytic solution was used instead of the electrolytic solution in Example 1.

[Charge / discharge test]
A charge / discharge test was carried out in the same manner as in Example 1. FIG. 5 shows the results of evaluating the cycle characteristics of the charge / discharge test.

(Example 10)
<Preparation of Electrolytic Solution (1M KOH + 1M 1,2-ethanediol aqueous solution)>
A 4M KOH aqueous solution, 1,2-ethanediol and ion-exchanged water were weighed and mixed in a volumetric flask so that a mixed aqueous solution of 1M KOH and 1M 1,2-ethanediol was obtained, and this was used as an electrolyte.

<Production of battery (1M KOH + 1M 1,2-ethanediol aqueous solution)>
The cell configuration was the same as in Example 1 except that this electrolytic solution was used instead of the electrolytic solution in Example 1.

[Charge / discharge test]
A charge / discharge test was carried out in the same manner as in Example 1. FIG. 5 shows the results of evaluating the cycle characteristics of the charge / discharge test.

(Example 11)
<Preparation of electrolyte solution (1M KOH + 1M 1,2,3-propanetriol aqueous solution)>
4M KOH aqueous solution, 1,2,3-propanetriol and ion-exchanged water are weighed and mixed in a volumetric flask so that a mixed aqueous solution of 1M KOH and 1M 1,2,3-propanetriol is obtained, and this is electrolyzed. Liquid.

<Production of battery (1M KOH + 1M 1,2,3-propanetriol aqueous solution)>
The cell configuration was the same as in Example 1 except that this electrolytic solution was used instead of the electrolytic solution in Example 1.

[Charge / discharge test]
A charge / discharge test was carried out in the same manner as in Example 1. FIG. 6 shows the cycle characteristic evaluation results of the charge / discharge test.

(Example 12)
<Preparation of electrolyte (4M KOH + 0.6M 1,2-propanediol aqueous solution)>
4M KOH aqueous solution, 1,2-propanediol and ion-exchanged water are weighed and mixed in a volumetric flask so as to be a mixed aqueous solution of 4M KOH and 0.6M 1,2-propanediol. did.

<Production of battery (4M KOH + 0.6M 1,2-propanediol aqueous solution)>
The cell configuration was the same as in Example 1 except that this electrolytic solution was used instead of the electrolytic solution in Example 1.

[Scanning electron microscope observation]
Waiting for the open circuit voltage of the prepared test cell to stabilize, using an electrochemical measurement system, voltage range of -1.18V to -1.46V, current value of 5 mA / cm ² per negative electrode area for 10 minutes A charge / discharge test was conducted starting from discharge at room temperature. After the charge / discharge test of 5 cycles, the battery was disassembled, the zinc negative electrode was taken out and washed with ion-exchanged water. After washing, the zinc negative electrode was dried under reduced pressure, and the shape of the zinc negative electrode surface was observed with a scanning electron microscope. A scanning electron micrograph is shown in FIG.

(Example 13)
<Preparation of Electrolytic Solution (4M KOH + 1.2M 1,2-propanediol aqueous solution)>
4M KOH aqueous solution, 1,2-propanediol and ion-exchanged water are weighed and mixed in a volumetric flask so as to be a mixed aqueous solution of 4M KOH and 1.2M 1,2-propanediol. did.

<Production of battery (4M KOH + 1.2M 1,2-propanediol aqueous solution)>
The cell configuration was the same as in Example 1 except that this electrolytic solution was used instead of the electrolytic solution in Example 1.

[Scanning electron microscope observation]
A charge / discharge test was performed under the same conditions as in Example 12, and the shape of the zinc negative electrode surface was observed with a scanning electron microscope. A scanning electron micrograph is shown in FIG.

(Example 14)
<Preparation of electrolyte (4M KOH + 1.8M 1,2-propanediol aqueous solution)>
4M KOH aqueous solution, 1,2-propanediol and ion-exchanged water are weighed and mixed in a volumetric flask so as to be a mixed aqueous solution of 4M KOH and 1.8M 1,2-propanediol. did.

<Production of battery (4M KOH + 1.8M 1,2-propanediol aqueous solution)>
The cell configuration was the same as in Example 1 except that this electrolytic solution was used instead of the electrolytic solution in Example 1.

[Scanning electron microscope observation]
A charge / discharge test was performed under the same conditions as in Example 12, and the shape of the zinc negative electrode surface was observed with a scanning electron microscope. A scanning electron micrograph is shown in FIG.

(Example 15)
<Preparation of Electrolytic Solution (4M KOH + 2.4M 1,2-propanediol aqueous solution)>
4M KOH aqueous solution, 1,2-propanediol and ion-exchanged water are weighed and mixed in a volumetric flask so that a mixed aqueous solution of 4M KOH and 2.4M 1,2-propanediol is obtained. did.

<Production of battery (4M KOH + 2.4M 1,2-propanediol aqueous solution)>
The cell configuration was the same as in Example 1 except that this electrolytic solution was used instead of the electrolytic solution in Example 1.

[Scanning electron microscope observation]
A charge / discharge test was performed under the same conditions as in Example 12, and the shape of the zinc negative electrode surface was observed with a scanning electron microscope. A scanning electron micrograph is shown in FIG.

From the cycle characteristic evaluation results of the charge / discharge test of FIG. 2, it can be seen that the electrolyte solutions of Examples 1 to 6 exhibit excellent cycle characteristics as compared with Comparative Example 1 using only 1M KOH. Furthermore, it turns out that the cycling characteristics which were excellent also compared with the comparative example 2 which added methanol in the conventional report are shown.
Although not shown, Example 2 reached 300 cycles (see FIG. 4), and Example 4 exceeded 100 cycles (see FIG. 5).

  In addition, from the measurement result of the hydrogen generation current at −2.00 V in FIG. 3, it can be seen that the electrolytic solution of the present invention has a smaller hydrogen generation current value than Comparative Example 1 in which only 1M KOH is used. From this result, it is considered that the corrosion reaction (self-discharge) of zinc and the hydrogen gas generation reaction which is a side reaction during charging are suppressed, and the decrease in discharge capacity and charge / discharge efficiency is effectively suppressed. That is, this result is considered to be one of the reasons for showing excellent cycle characteristics in FIG.

  Furthermore, from the cycle characteristic evaluation results of the charge / discharge test of FIGS. 4, 5 and 6, Example 2, Example 7 and Example 8, Example 4, Example 9 and Example 10, Example 6 and Example It can be seen that, in the concentration range shown in Example 11, excellent cycle characteristics are exhibited as compared with Comparative Example 1 using only 1M KOH.

  Furthermore, from the observation result of the zinc negative electrode surface after the charge / discharge test by the scanning electron microscope in FIG. 7, the electrolytic solution of the present invention effectively suppresses the change in the shape of the zinc negative electrode surface by the charge / discharge test. I understand.

  As mentioned above, although this invention was demonstrated with some embodiment and an Example, this invention is not limited to these, A various deformation | transformation is possible within the range of the summary of this invention.

  For example, in each of the embodiments and examples described above, a nickel-zinc secondary battery has been described as an example of an alkaline secondary 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 are combined other than the above-described embodiments. Or the details of the positive electrode, the negative electrode, and the electrolyte can be changed.

DESCRIPTION OF SYMBOLS 1 Positive electrode 2 Negative electrode 3 Electrolyte 10 Reference electrode 11 Housing 12 Bottom holder 13 Cover

Claims (8)

  An alkaline battery electrolyte comprising at least an organic substance having two or more carbon atoms and one or more hydroxyl groups in a molecule.   2. The alkaline battery electrolyte according to claim 1, wherein the organic substance has a hydroxyl group bonded to a carbon atom at the 2-position.   3. The alkaline battery electrolyte solution according to claim 1, wherein the organic substance is a dihydric alcohol.   The electrolyte for alkaline batteries according to any one of claims 1 to 3, wherein the organic substance is 1,2-ethanediol.   5. The alkaline battery electrolyte solution according to claim 1, wherein the organic substance has a concentration of 0.5 to 5 mol / L.   An alkaline battery comprising the alkaline battery electrolyte solution according to any one of claims 1 to 5.   The alkaline battery according to claim 6, wherein the alkaline battery is a secondary battery.   The alkaline battery according to claim 6 or 7, wherein the secondary battery is an air-zinc secondary battery or a nickel-zinc secondary battery.

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