JP6813016B2 - Alkaline batteries and electrolytes for alkaline batteries - Google Patents

Description

The present invention relates to an alkaline storage battery and an electrolytic solution for an alkaline storage battery.

In recent years, information and communication infrastructure has come to be considered as a kind of lifeline, and stable information and communication technology supports the foundation of modern society. For this reason, information and communication equipment is required to operate even during a power outage, and in particular, there is a growing sense of crisis about the risk of a power outage due to a natural disaster such as a recent earthquake, heavy rain, or lightning strike. Against this background, the demand for power storage devices that serve as backup power sources in the event of a power outage is increasing, and in particular, the demand for power storage devices that are excellent in handling is increasing. Furthermore, a large amount of electric power is consumed in facilities such as data centers equipped with many information and communication devices. Therefore, as a backup power source, there is a demand for a power storage device that is easy to handle and can discharge at high output.

As a power storage device, a lead storage battery, a lithium ion secondary battery, an alkaline storage battery (alkaline aqueous solution type secondary battery) and the like are known. Lead-acid batteries have high reliability backed by a history of more than 100 years and have a low cost per unit storage capacity, so they are used in a wide range of applications such as for mobiles as well as for backup. Since lithium-ion batteries have high energy density and high output density, they are widely used as power sources for mobile devices, mobile devices, and the like. Since the alkaline storage battery uses an alkaline aqueous solution as an electrolytic solution, it is excellent in output characteristics and handling. Therefore, alkaline storage batteries are used as a power source for mobile devices, mobile objects, and the like.

On the other hand, since the volumetric energy density of the lead-acid battery is low, the installation area of the lead-acid battery becomes large. Furthermore, as represented by the RoHS Directive, lead is subject to regulation worldwide, so it is possible that the lead-acid battery itself will be subject to regulation in the future. Further, since the output density of the lithium ion secondary battery is relatively small, the number of battery cells is increased in order to increase the output density. Therefore, as with the lead storage battery, the installation area becomes large. Furthermore, since an organic electrolytic solution is used in the lithium ion secondary battery, handling is complicated.

Therefore, alkaline storage batteries are attracting attention. As a technique relating to an alkaline storage battery, the technique described in Patent Document 1 is known. Patent Document 1 describes an anode containing an electrochemically active anode substance, a cathode containing an electrochemically active cathode substance, a separator 6 between the anode and the cathode, and ions dissolved in water. and an electrolyte containing a conductive component, the area resistance of the combination of the electrolyte and the separator 6 is between 100mΩ-cm ² ~220mΩ-cm ² before one electron discharge, one electron discharge Alkaline storage batteries in which the ratio of area resistance to the previous area resistance at the completion of one-electron discharge is less than 1.9 are described.

Japanese Patent No. 6279602 (see particular claim 1)

By the way, in an alkaline storage battery, for example, when a fully charged state is maintained, electrolysis of an electrolytic solution is promoted at a high temperature (for example, about 40 ° C. or higher). As a result, battery life is reduced. In particular, when an alkaline storage battery is used as a backup power storage device, for example, the alkaline storage battery is maintained in a fully charged state, so that the battery life tends to decrease. However, Patent Document 1 does not describe suppressing the decrease in battery life under high temperature conditions.

An object of the present invention is to provide an alkaline storage battery and an electrolytic solution for an alkaline storage battery having a long life even at a high temperature.

The present invention relates to an alkaline storage battery, which comprises an electrolytic solution containing a halogen salt and being alkaline, and the content of the halogen salt with respect to the electrolytic solution is 5% by mass or more. Other solutions will be described later in the form for carrying out the invention.

According to the present invention, it is possible to provide an alkaline storage battery and an electrolytic solution for an alkaline storage battery having a long life even at a high temperature.

It is a figure which shows the structure of the alkaline storage battery which concerns on 1st Embodiment. It is a figure which shows the structure of the alkaline storage battery which concerns on 2nd Embodiment. It is a figure which shows the structure of the alkaline storage battery which concerns on 3rd Embodiment. It is a graph which shows the current density evaluation result with respect to the produced four electrolytic solutions.

Hereinafter, the present invention will be described with reference to the drawings, but the present invention is not limited to the following contents, and the present invention can be carried out with arbitrary modifications without significantly impairing the gist thereof. In each embodiment, the same members will be described with the same reference numerals, and duplicate description will be omitted.

FIG. 1 is a diagram showing the structure of the alkaline storage battery 10 according to the first embodiment. However, FIG. 1 shows a power supply 4, an external load 5, and a switch 8 connected to the alkaline storage battery 10 for convenience of explanation. The alkaline storage battery 10, the power supply 4, the external load 5, and the switch 8 are connected by an electric signal line shown by a solid line in FIG. The alkaline storage battery 10 is a secondary battery, and in the example shown in FIG. 1, the alkaline storage battery 10 is used as a backup power storage device for the external load 5.

The alkaline storage battery 10 includes a positive electrode 1 and a negative electrode 2. Further, the alkaline storage battery 10 is in contact with the positive electrode 1 and the negative electrode 2 and includes the alkaline electrolytic solution 3. The electrolytic solution 3 is usually an aqueous solution. The alkaline storage battery 10 is charged and discharged by the transfer of ions between the positive electrode 1 and the negative electrode 2 and the alkaline electrolytic solution 3.

The positive electrode 1 is composed of a metal that is noble than the redox potential of the negative electrode 2. For example, the positive electrode 1 contains at least one compound selected from the group consisting of nickel hydroxide, nickel oxyhydroxide, nickel metal (nickel alone), nickel alloy, nickel oxide, manganese oxide, manganese dioxide, silver oxide and copper oxide. Consists of including. The positive electrode 1 is connected to the positive electrode of the power supply 4 by an electric signal line.

The negative electrode 2 is composed of a metal that is lower than the redox potential of the positive electrode 1. For example, the negative electrode 2 is at least one compound selected from the group consisting of zinc hydroxide, zinc oxide, zinc metal (zinc alone), zinc alloy, cadmium hydroxide, cadmium metal (cadmium alone), cadmium alloy and metal hydride. Consists of including. The negative electrode 2 is connected to the negative electrode of the power supply 4 via an electric signal line and a switch 8.

The electrolytic solution 3 (electrolyzable solution for an alkaline storage battery) contains a halogenate and is alkaline. The halogenate is ionized into at least one kind of cation (A ⁺ ) and at least one kind of halogenate ion (X ⁻ ) in the electrolytic solution 3 which is an alkaline aqueous solution. When the electrolytic solution 3 contains a halogen acid, the halogenate ions coordinate with water molecules in the electrolytic solution 3 to improve the reduction resistance of water and reduce the clusters of water. It is possible to suppress the electrolysis of the electrolytic solution 3 and extend the life of the electrolytic solution 3 at a high temperature.

The halogenate preferably contains a compound that has high solubility in an alkaline aqueous solution and is stable in an alkaline aqueous solution. For example, the halogenate preferably contains at least one salt selected from the group consisting of alkali metal salts, ammonium salts and transition metal salts. When the halogenate contains at least one of these salts, the solubility in the electrolytic solution 3 which is an alkaline aqueous solution can be increased. At the same time, the stability of the halide in the electrolytic solution 3 can be enhanced. As a result, the effect of containing the halogenate in the electrolytic solution 3 becomes particularly large, and the effect can be maintained for a long time.

Further, the halogenated salt preferably contains at least one salt selected from the group consisting of perchlorate, chlorate, periodate, iodate and bromate. When the halogenate contains at least one of these salts, the solubility in the electrolytic solution 3 which is an alkaline aqueous solution can be increased. At the same time, the stability of the halide in the electrolytic solution 3 can be enhanced. As a result, the effect of containing the halogen salt in the electrolytic solution 3 becomes particularly large, and the effect can be maintained for a long time.

The halides include, for example, sodium perchlorate, zinc perchlorate, barium perchlorate, lithium perchlorate, ammonium perchlorate, sodium bromate, zinc chlorate, barium chlorate, lithium chlorate, chlorate. It can contain at least one salt selected from the group consisting of ammonium, sodium perchlorate, sodium iodate, potassium iodate, sodium bromate, potassium bromate and lithium bromate.

The content of the halogen salt is 5% by mass or more, preferably 10% by mass or more, as the content with respect to the electrolytic solution 3. By setting the halogenated salt content in this range, the electrolysis of the electrolytic solution 3 at a high temperature can be sufficiently suppressed, and the alkaline storage battery 10 can have a long life even at a high temperature.

In particular, when the content of the halogenate is 5% by mass or more, the content effect exerted by the halogenate can be increased. That is, when the content of the halide is less than 5% by mass, the current densities in the hydrogen generation region and the oxygen generation region hardly change in the graph shown in FIG. 4 described later, and hydrogen and oxygen are generated. Easy to do. That is, the electrolytic solution 3 is easily electrolyzed, and the life of the alkaline storage battery 10 is likely to be shortened. However, by containing the halide in a proportion of 5% by mass or more, the current density in the hydrogen generation region and the oxygen generation region can be significantly changed as compared with the current density in the content of less than 5% by mass. Can be done. Specifically, the absolute value of the current density can be reduced in both the hydrogen generation region and the oxygen generation region. As a result, the electrolysis of the electrolytic solution 3 is suppressed, and a large potential window can be secured. As a result, the stability of the electrolytic solution 3 can be improved, and the life of the alkaline storage battery 10 can be extended even at a high temperature.

The content of the halogenate is preferably 40% by mass or less, more preferably 30% by mass or less, as the content with respect to the electrolytic solution 3. By setting the halogenated salt content in this range, the conductivity of the electrolytic solution 3 can be increased, and the battery output of the alkaline storage battery 10 can be increased. Therefore, from the viewpoint of achieving both a long life of the alkaline storage battery 10 at a high temperature and a high battery output, the halogenated salt content is 10% by mass or more and 30% by mass or less as the content with respect to the electrolytic solution 3. Is preferable.

Further, the electrolytic solution 3 contains an alkaline agent for making the electrolytic solution 3 alkaline. The alkaline agent is ionized into at least one kind of cation (A ⁺ ) and hydroxide ion (OH ⁻ ) in the electrolytic solution 3.

As the alkaline agent, for example, at least one alkaline agent selected from the group consisting of sodium hydroxide, potassium hydroxide, lithium hydroxide, magnesium hydroxide, calcium hydroxide, cesium hydroxide and ammonium hydroxide can be used. .. Above all, the alkaline agent preferably contains sodium hydroxide. Since sodium hydroxide has high solubility in water, the hydroxide ion concentration in the electrolytic solution 3 can be sufficiently increased by containing sodium hydroxide in the alkaline agent.

The content of the alkaline agent is preferably such that the electrolysis reaction rate of the electrolytic solution 3 can be sufficiently slowed down by increasing the electrochemical polarization of the water molecules contained in the electrolytic solution 3. Specifically, for example, the content of the alkaline agent is, for example, 10% by mass or more, preferably 15% by mass or more, as the content with respect to the electrolytic solution 3. By setting the content of the alkaline agent in this range, sufficient hydroxide ions used for charging and discharging can be secured. The upper limit of the content of the alkaline agent is, for example, 40% by mass or less, preferably 30% by mass or less. By setting the content of the alkaline agent in this range, oxygen generation at the positive electrode 1 due to excess hydroxide ions can be sufficiently suppressed.

The relative relationship between the content of the alkaline agent and the content of the halogenate is not particularly limited. Therefore, the content of the alkaline agent and the content of the halogenate may be determined so as to obtain the desired content. However, the solvent contained in the electrolytic solution 3 is usually water, and the alkaline agent and the halogenate are dissolved in water. Therefore, the electrolytic solution 3 contains an amount of water that can completely dissolve both the alkaline agent and the halide at the operating temperature of the electrolytic solution 3. Therefore, for example, in 100 parts by mass of the electrolytic solution 3, for example, the content of the alkaline agent is 40 parts by mass or less, the content of the halogenated salt is 40 parts by mass or less, and the balance (20 parts by mass or more) is water. can do.

In addition to the halogenated salt and the alkaline agent, the electrolytic solution 3 can contain any simple substance or compound as long as the effects of the present invention are not significantly impaired.

The separator 6 is for suppressing a short circuit between the positive electrode 1 and the negative electrode 2, and is arranged between the positive electrode 1 and the negative electrode 2. Further, in the example shown in FIG. 1, one separator 6 is arranged on each side of the liquid retaining member 7 so as to sandwich the liquid retaining member 7 described later. The separator 6 can be composed of, for example, an anion exchange membrane that selectively permeates anions. By forming the separator 6 with an anion exchange membrane, it is possible to suppress the permeation of the cation eluted from the negative electrode 2 into the separator 6, and the cation eluted from the negative electrode 2 can be retained in the vicinity of the negative electrode. As a result, the reprecipitation of the eluted cations is suppressed from reaching the positive electrode 1, and a short circuit between the positive electrode 1 and the negative electrode 2 can be suppressed.

Further, the separator 6 can also be formed of a porous membrane that allows ions and molecules to freely permeate. By forming the separator 6 with the porous membrane, it is possible to suppress the reprecipitation of the eluted cations from reaching the positive electrode 1 and suppress the short circuit between the positive electrode 1 and the negative electrode 2. Further, since water molecules can permeate through the porous membrane, extremely non-uniformity between the amount of the electrolytic solution 3 on the positive electrode 1 side and the amount of the electrolytic solution 3 on the negative electrode 2 side due to charging and discharging of the alkaline storage battery 10 is suppressed. it can.

The separator 6 may be formed by stacking one or a plurality of single types. Further, the separator 6 may be formed by stacking one or a plurality of separators of two or more types, respectively. By reducing the number of separators 6 used, it is possible to suppress an increase in internal resistance due to the separator 6. On the other hand, by increasing the number of separators 6 used, a short circuit between the positive electrode 1 and the negative electrode 2 can be more sufficiently suppressed. Therefore, the number of separators 6 may be determined in consideration of, for example, internal resistance and short-circuit possibility.

The liquid-retaining member 7 suppresses the volatilization of the electrolytic solution 3 (specifically, water) by permeating the electrolytic solution, and is arranged between the positive electrode 1 and the negative electrode 2. Specifically, the liquid retention member 7 is arranged between the two separators 6. The liquid-retaining member 7 can suppress a decrease in the contact area between the positive electrode 1 and the negative electrode 2 and the electrolytic solution 3 due to the volatilization of the electrolytic solution 3. Further, the liquid retention member 7 can suppress the sedimentation of the cation eluted from the negative electrode 2 downward to the negative electrode 2. As a result, the reprecipitation of the eluted cation can be suppressed, and the so-called shape change of the negative electrode 2 can be suppressed.

The liquid retention member 7 can be made of any material that can permeate the electrolytic solution 3. For example, the liquid retention member 7 can be composed of at least one material selected from the group consisting of non-woven fabric, paper, felt and knitted fabric.

In the illustrated example, the liquid retention member 7 is arranged with a gap between it and the separator 6, and also with a gap between the positive electrode 1 and the negative electrode 2. However, the liquid retaining member 7 may be brought into contact with at least one of the positive electrode 1 and the negative electrode 2. In particular, by bringing the liquid retention member 7 into contact with the negative electrode 2, sedimentation of the cation eluted from the negative electrode 2 can be suppressed more sufficiently.

Further, the liquid retention member 7 may be brought into contact with the separator 6. When the liquid-retaining member 7 comes into contact with the separator 6, the separator 6 may further come into contact with at least one of the positive electrode 1 and the negative electrode 2. That is, the liquid retention member 7 and at least one of the positive electrode 1 and the negative electrode 2 may be brought into contact with each other via the separator 6. By bringing the liquid-retaining member 7 into contact with at least one of the positive electrode 1 and the negative electrode 2 via the separator 6, the depletion of the electrolytic solution 3 between the positive electrode 1 and the negative electrode 2 can be suppressed.

In the example shown in FIG. 1, the alkaline storage battery 10 is connected to the DC power supply 4. Further, the external load 5 (for example, equipped with a DC / AC converter (not shown)) is connected to the power supply 4 so as to be in parallel with the alkaline storage battery 10. A switch 8 is connected between the power supply 4 and the alkaline storage battery 10.

When the power supply 4 is operating normally, the switch 8 is closed, and power is supplied from the power supply 4 to the alkaline storage battery 10 and the external load 5 connected in parallel to the alkaline storage battery 10. As a result, electricity is stored in the alkaline storage battery 10 and power is supplied to the external load 5. On the other hand, when the power supply 4 is unexpectedly cut off, the switch is opened and the electric power stored in the alkaline storage battery 10 is supplied to the external load 5. By doing so, even if the power supply 4 is unintentionally turned off, the alkaline storage battery 10 can be used as a backup power storage device for the external load 5.

In particular, the alkaline storage battery 10 is installed near, for example, a drive control device (not shown) for performing drive control of the power supply 4, or the like. Therefore, the alkaline storage battery 10 is installed in an environment exposed to the exhaust heat of the drive control device, and the alkaline storage battery 10 is easily exposed to a high temperature. As a result, the life of the alkaline storage battery 10 tends to be shortened. However, the alkaline storage battery 10 has a long life even at a high temperature. Therefore, the life of the alkaline storage battery 10 can be extended even at a high temperature such as near a drive control device.

The alkaline storage battery 10 will be described in detail with reference to Examples, but the degree of deterioration of the alkaline storage battery 10 is gradual even if it is kept in a fully charged state for a long period of time at a high temperature. Therefore, the alkaline storage battery 10 is also suitable as, for example, a backup power storage device that is held in a fully charged state.

FIG. 2 is a diagram showing the structure of the alkaline storage battery 20 according to the second embodiment. Unlike the alkaline storage battery 10 (see FIG. 1), the alkaline storage battery 20 is not provided with the separator 6 and the liquid retaining member 7. However, even in the alkaline storage battery 20 that does not include the separator 6 and the liquid retention member 7, the life of the alkaline storage battery 20 can be extended by the electrolytic solution 3. Further, the alkaline storage battery 20 is also suitable as, for example, a backup power storage device.

FIG. 3 is a diagram showing the structure of the alkaline storage battery 30 according to the third embodiment. Unlike the alkaline storage battery 10 (see FIG. 1), the alkaline storage battery 30 is not provided with the liquid retention member 7. However, even in the alkaline storage battery 30 that does not have the liquid retention member 7, the life of the alkaline storage battery 30 can be extended by the electrolytic solution 3. Further, the alkaline storage battery 30 is also suitable as, for example, a backup power storage device.

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

In order to evaluate the effect of containing a halogen salt in the electrolytic solution 3, an electrolytic solution 3 (an electrolytic solution for an alkaline storage battery) was prepared by the method shown below. First, as the electrolytic solution 3 of Example 1, an electrolytic solution 3 containing sodium hydroxide (alkaline agent) and sodium perchlorate (halogenate) and using water as a solvent was prepared. In the electrolytic solution 3 of Example 1, the content of sodium hydroxide was 20% by mass with respect to the electrolytic solution 3, and the content of sodium perchlorate was 40% by mass with respect to the electrolytic solution 3.

Further, the electrolytic solution 3 of Example 2 was prepared in the same manner as in Example 1 except that the content of sodium perchlorate was 20% by mass. Further, the electrolytic solution 3 of Example 3 was prepared in the same manner as in Example 1 except that the content of sodium perchlorate was set to 5% by mass. Then, the electrolytic solution 3 of Comparative Example was prepared in the same manner as in Example 1 except that sodium perchlorate was not contained.

The electrodes were immersed in the four prepared electrolytic solutions 3 (electrolyte solutions of Examples 1 to 3 and Comparative Examples), and the current density was evaluated when the potential was swept. The current density evaluation was performed on the electrolytic solution 3 kept at 55 ° C. A glassy carbon electrode was used as the working electrode, a platinum wire electrode was used as the counter electrode, and a nickel plate electrode coated with nickel hydroxide was used as the reference electrode. Then, the current density was measured while sweeping the potential of the working electrode at a speed of 100 mV / sec. The result is shown in FIG.

FIG. 4 is a graph showing the current density evaluation results for the four prepared electrolytic solutions. The horizontal axis represents the potential (V) based on nickel-nickel hydroxide (Ni / Ni (OH) ₂ ), and the vertical axis represents the current density (mA / cm ² ). Further, in FIG. 4, Example 1 is shown as a white diamond, Example 2 is shown as a white square, Example 3 is shown as a white triangle, and Comparative Example is shown as a white circle. In the hydrogen generation region on the low potential side on the horizontal axis, the electrolytic solution 3 is electrolyzed to mainly generate hydrogen. On the other hand, in the oxygen evolution region on the high potential side, the electrolytic solution 3 is electrolyzed to mainly generate oxygen. Therefore, the alkaline storage battery using the electrolytic solution 3 is used at a usable region excluding the water oxygen generation region and the oxygen generation region, that is, the potential in the “potential window”.

As shown in this graph, Examples 1 to 3 containing a halogenate in a proportion of 5% by mass or more have potentials in the hydrogen generation region and the oxygen generation region, as compared with the comparative examples not containing the halide. There was a change in the current density.

For example, with respect to the current densities in the hydrogen generation region (hydrogen generation current density, reduction current density), the current densities in Examples 1 to 3 containing the halide in a proportion of 5% by mass or more are compared without the halide. It became larger than the example current density (note that the absolute value of the critical current density became smaller). Therefore, in the hydrogen generation region, it can be said that in Examples 1 to 3 containing 5% by mass or more of the halogenate, the degree of decrease in the current density was slower than that in the comparative example not containing the halogenate. In particular, in Examples 1 to 3 containing a halogenate, the current density of Example 1 containing the halogenate in a proportion of 40% by mass or more is the largest, followed by the halogenate in a proportion of 20% by mass or more. The size increased in the order of Example 2 and Example 3 in which the halogenate was contained in a proportion of 5% by mass or more. Therefore, from the viewpoint of increasing the current density (decreasing the absolute value) in the hydrogen generation region, it was found that a large halogenate content is preferable.

On the other hand, in the current densities in the oxygen generation region (oxygen generation current density, oxidation current density), the current densities of Examples 1 to 3 containing the halide in a proportion of 5% by mass or more do not contain the halide. It became smaller than the current density of the comparative example. (The absolute value of the critical current density has also become smaller). Therefore, in the oxygen generation region, it can be said that in Examples 1 to 3 containing 5% by mass or more of the halide, the degree of increase in the current density was slower than that in the comparative example not containing the halide. In particular, also in Examples 1 to 3 containing a halide, the current density of Example 1 containing a halogenate in a proportion of 40% by mass or more is the smallest, followed by a halide in a proportion of 20% by mass or more. It became smaller in the order of Example 2 containing the halide and Example 3 containing the halide in an proportion of 5% by mass or more. Therefore, from the viewpoint of reducing the current density (decreasing the absolute value) in the oxygen evolution region, it was found that a large halogenate content is preferable.

The magnitude of the current density at the lower limit potential (-2.0V) in the hydrogen generation region and the upper limit potential (2.5V) in the oxygen generation region (absolute value. Hereinafter, in the explanation of Table 1, it is absolute unless otherwise specified. The values are shown in Table 1 below.

In Examples 1 to 3 containing a halogen salt at a ratio of 5% by mass or more, the current density was significantly reduced in both the hydrogen generation region and the oxygen generation region as compared with the comparative example not containing the halogen salt. It was. Specifically, in Example 1 in the hydrogen generation region, the current density was reduced to 29% as compared with Comparative Example. Further, in Example 2 in the hydrogen generation region, the current density was reduced to 66% as compared with Comparative Example. In Example 3 in the hydrogen generating region, the current density was reduced to 84% as compared with Comparative Example.

When the current density decreases in the hydrogen generation region, the number of electrons received by the hydrogen ions decreases, so that the amount of hydrogen generated decreases. That is, for example, in the alkaline storage batteries using the electrolytic solutions of Example 1 and Comparative Example, when energized at the same current density, the amount of hydrogen generated corresponding to the decrease in the current density decreases. Therefore, in the electrolytic solution of Example 1, since the current density was reduced to 29% of that of Comparative Example, it can be said that the amount of hydrogen generated was reduced by 71% (= 100% -29%) as compared with that of Comparative Example. Similarly, it can be said that the amount of hydrogen generated decreased by 34% in Example 2 and the amount of hydrogen generated decreased by 16% in Example 3.

Further, also in the oxygen generation region, if the current density decreases, the number of generated electrons decreases, so that the amount of oxygen generated decreases. Then, in the oxygen evolution region, in Example 1, the current density was reduced to 53% as compared with Comparative Example. Further, in Example 2 in the oxygen evolution region, the current density was reduced to 81% as compared with Comparative Example. In Example 3 in the oxygen evolution region, the current density was reduced to 90% as compared with Comparative Example. Therefore, it can be said that in the electrolytic solution of Example 1, the amount of oxygen generated was reduced by 47% (= 100% -53%) as compared with the comparative example, as in the hydrogen generation region described above. Similarly, it can be said that the amount of oxygen generated decreased by 19% in Example 2 and the amount of oxygen generated decreased by 10% in Example 3.

From these results, in the alkaline storage battery 10 provided with the electrolytic solution 3 of Examples 1 to 3, both the amount of hydrogen generated and the amount of oxygen generated during charging / discharging are suppressed even at a high temperature such as 55 ° C., that is, It was found that the electrolysis of the electrolytic solution 3 was suppressed during charging and discharging. Therefore, according to the alkaline storage battery of the present invention, it is possible to provide an alkaline storage battery having a long life even at a high temperature.

In the above example, sodium perchlorate was used as the halogenate. However, for example, in addition to alkali metal salts other than sodium perchlorate, at least one salt selected from the group consisting of ammonium salts and transition metal salts is considered to give the same results as in the above examples. Be done. The reason for this is that both sodium perchlorate and these salts are considered to have the same effect of coordinating with water molecules by producing cations that are easily coordinated with water molecules by ionization.

Similarly, in the above examples, perchlorate was used as the halogenate. However, for example, in addition to perchlorate other than sodium perchlorate, at least one salt selected from the group consisting of chlorate, periodate, iodate and bromate may be described above. It is considered that the same result as in the examples can be obtained. The reason for this is that both sodium perchlorate and these salts are considered to have the same effect of ionizing to generate halogenate ions and coordinating with water molecules.

Next, the change in the discharge capacity of the alkaline storage battery after being held at a high temperature for a long period of time was evaluated.

Using a nickel hydroxide metal plate as the positive electrode 1, a zinc hydroxide metal plate as the negative electrode 2, and the electrolytic solution 3 of Example 1 as the electrolytic solution 3, the alkaline storage battery 10 shown in FIG. 1 (alkali of Example 1). A storage battery 10) was produced. Further, an alkaline storage battery of Comparative Example was produced in the same manner as the alkaline storage battery 10 of Example 1 except that the electrolytic solution of Comparative Example was used as the electrolytic solution.

Each of the two produced alkaline storage batteries (the alkaline storage battery 10 of Example 1 and the alkaline storage battery of Comparative Example) was fully charged to 1.8 V, and the discharge capacity (initial discharge capacity) was measured. Next, each of the two produced alkaline storage batteries (Example 1 and Comparative Example) was connected to a separate charging circuit (not shown), and a weak current was passed so as to reach a constant voltage (1.8 V). Then, the two alkaline storage batteries were held for 15 days in an environment of 55 ° C. in a state where a weak current was applied so that the charging voltage of the alkaline storage batteries became a constant voltage. For the two alkaline storage batteries held for 15 days, the discharge capacity (discharge capacity after holding for 15 days) was measured under the same conditions as when the first discharge capacity was measured.

Here, in the alkaline storage battery of the comparative example, the maintenance rate (reference value) obtained by dividing the discharge capacity after holding for 15 days by the initial discharge capacity is set to 1. Then, in the alkaline storage battery of Example 1, the maintenance rate obtained by dividing the discharge capacity after holding for 15 days by the initial discharge capacity was 1.13 times the above reference value. The results are shown in Table 2 below.

From the results shown in Table 2, the alkaline storage battery 10 of Example 1 provided with the electrolytic solution 3 of Example 1 has a degree of deterioration due to high temperature of 1 as compared with the alkaline storage battery of Comparative Example containing the electrolytic solution of Comparative Example. It can be said that it has become .13 times slower. It is considered that this result is due to the fact that the electrolytic solution 3 of Example 1 suppressed the electrolysis of the electrolytic solution 3 at a high temperature as described with reference to Table 1 above. In particular, in the alkaline storage battery 10 of Example 1, even if it was held at a high temperature (55 ° C.) for 15 days while maintaining a fully charged state, the degree of deterioration was slower than that of the alkaline storage battery of Comparative Example.

Therefore, according to the alkaline storage battery of the present invention, it is possible to provide an alkaline storage battery having a long life even at a high temperature while maintaining a fully charged state. Therefore, it is possible to provide an alkaline storage battery which is installed at a high temperature such as near a drive control device and is suitable as a backup power storage device, for example. Further, since it has a long life even at a high temperature while maintaining a fully charged state, it is considered that a long-life alkaline storage battery can be provided even when a normal charge / discharge cycle is performed at a high temperature, for example.

1 Positive electrode 2 Negative electrode 3 Electrolyte (electrolyte for alkaline storage battery)
4 Power supply 5 External load 6 Separator 7 Liquid retention member 8 Switch 10 Alkaline storage battery 20 Alkaline storage battery 30 Alkaline storage battery

Claims (10)

Equipped with an electrolytic solution containing a halogenate and being alkaline
An alkaline storage battery characterized in that the content of the halogenated salt with respect to the electrolytic solution is 5% by mass or more. The alkaline storage battery according to claim 1, wherein the halogenated salt contains at least one salt selected from the group consisting of an alkali metal salt, an ammonium salt and a transition metal salt. The halogenate comprises at least one salt selected from the group consisting of perchlorate, chlorate, periodate, iodate and bromate, claim 1 or 2. The alkaline storage battery described in. The halides include sodium perchlorate, zinc perchlorate, barium perchlorate, lithium perchlorate, ammonium perchlorate, sodium chlorate, zinc chlorate, barium chlorate, lithium chlorate, and ammonium chlorate. , Which of claims 1 to 3, comprising at least one salt selected from the group consisting of sodium perchlorate, sodium iodate, potassium iodate, sodium bromate, potassium bromate and lithium bromate. Or the alkaline storage battery according to item 1. The alkaline storage battery according to any one of claims 1 to 4, wherein the content of the halogenated salt with respect to the electrolytic solution is 40% by mass or less. The alkaline storage battery according to any one of claims 1 to 5, wherein the content of the halogenated salt with respect to the electrolytic solution is 10% by mass or more and 30% by mass or less. The electrolytic solution contains an alkaline agent and contains
The alkaline storage battery according to any one of claims 1 to 6, wherein the content of the alkaline agent with respect to the electrolytic solution is 10% by mass or more and 40% by mass or less. The alkaline storage battery according to claim 7, wherein the alkaline agent contains sodium hydroxide. Equipped with positive and negative electrodes
The positive electrode contains at least one compound selected from the group consisting of nickel hydroxide, nickel oxyhydroxide, nickel metal, nickel alloy, nickel oxide, manganese oxide, manganese dioxide, silver oxide and copper oxide.
The negative electrode comprises at least one compound selected from the group consisting of zinc hydroxide, zinc oxide, zinc metal, zinc alloy, cadmium hydroxide, cadmium metal, cadmium alloy and metal hydride. The alkaline storage battery according to any one of 1 to 8. Equipped with an electrolytic solution containing a halogenate and being alkaline
An electrolytic solution for an alkaline storage battery, characterized in that the content of the halogenated salt with respect to the electrolytic solution is 5% by mass or more.

Images