JP6874806B2 - Aqueous solution-based secondary battery and aqueous solution-based secondary battery system - Google Patents

Description

The present invention relates to an aqueous solution-based secondary battery and an aqueous solution-based secondary battery system.

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. In particular, in recent years, there is a growing sense of crisis about the risk of power outages due to natural disasters such as earthquakes, heavy rains, and lightning strikes. Against this background, there is an increasing demand for power storage devices that serve as backup power sources in the event of a power outage, and in particular, there is an increasing demand for power storage devices that are easy to handle. Furthermore, facilities such as data centers equipped with many information and communication devices consume a large amount of electric power. Therefore, as a backup power source, there is a demand for a power storage device that is easy to handle and can discharge at a 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 mobile devices as well as backup batteries. Lithium-ion secondary batteries have high energy density and high output density, and are therefore widely used as power sources for mobile devices and mobile devices. Since the alkaline storage battery uses an alkaline aqueous solution as an electrolytic solution, it has excellent output characteristics and is easy to handle. Therefore, alkaline storage batteries are used as a power source for mobile devices, mobile devices, 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, the lithium ion secondary battery is complicated to handle because an organic electrolytic solution is used.

Therefore, alkaline storage batteries are attracting attention. However, in the alkaline storage battery, volatilization of the aqueous electrolytic solution is promoted at a high temperature (for example, about 40 ° C. or higher). As a result, battery life is reduced.

As a technique for suppressing volatilization of an aqueous solution-based electrolytic solution, for example, the technique described in Patent Document 1 is known. In Patent Document 1, oil is suspended on the electrolyte surface, and a positive electrode column corresponding to at least the upper limit position to the lower limit position of the specified electrolyte surface is surrounded by a tubular body, and the tubular body surrounds the positive electrode column on the electrolyte surface. A lead-acid battery is described in which the oil of the above is not in contact with the positive electrode column.

Japanese Unexamined Patent Publication No. 10-223251

However, in the configuration in which the oil that suppresses the evaporation of the electrolytic solution is provided above the electrolytic solution as in the technique described in Patent Document 1, the oil is transferred to the inside of the electrode plate group or the porous film due to vibration or surface tension between the electrode plates. Will penetrate. Therefore, the internal resistance gradually increases, and the output characteristics of the battery deteriorate. Further, when the internal resistance becomes large and the output characteristic deteriorates, the charge product cannot be completely eliminated even if the battery is discharged, so that the apparent capacity is lowered and the life characteristic is also lowered. In the present specification, the electrode plate group is generally composed of a positive electrode (plate), a negative electrode (plate), and a separator which is arranged between them and prevents them from being short-circuited. A group of components, some of which do not have a separator. The cell is configured to include one group of plates, and the secondary battery can be provided with a plurality of the cells as needed.

The present invention has been made in view of such a situation, and an object of the present invention is to provide an aqueous solution-based secondary battery and an aqueous solution-based secondary battery system having high output and long life even at high temperatures.

The aqueous secondary battery according to the present invention that solves the above problems includes a positive electrode, a negative electrode arranged apart from the positive electrode, an aqueous electrolytic solution that comes into contact with the positive electrode and the negative electrode and contains water. The positive electrode, the negative electrode, and an exterior body containing the aqueous electrolytic solution are provided, and the electrode is arranged in at least one selected from the group consisting of an upper portion, an outer periphery, and an inner wall of the outer body of the aqueous electrolytic solution. A volatilization suppressing layer that suppresses volatilization of the aqueous electrolytic solution is provided, and the volatilization suppressing layer includes a refractory liquid and a porous retainer that holds the refractory liquid.

According to the present invention, it is possible to provide an aqueous solution-based secondary battery and an aqueous solution-based secondary battery system having high output and long life even at a high temperature.
Issues, configurations and effects other than those described above will be clarified by the description of the following embodiments.

It is the schematic which shows the structure of the aqueous solution system secondary battery 100 which concerns on 1st Embodiment of this invention. It is the schematic which shows the structure of the aqueous solution system secondary battery 200 which concerns on 2nd Embodiment of this invention. It is the schematic which shows the structure of the aqueous solution system secondary battery 300 which concerns on 3rd Embodiment of this invention. It is the schematic which shows the structure of the aqueous solution system secondary battery 400 which concerns on 4th Embodiment of this invention. It is the schematic which shows the structure of the aqueous solution system secondary battery system 500 which concerns on one Embodiment of this invention. It is a graph which shows the retention rate (liquid retention rate) of the aqueous solution type electrolytic solution 3 in the presence / absence of a volatilization suppression layer 5. In the figure, the vertical axis indicates the liquid retention rate [%]. It is a graph which shows the discharge curve in the presence / absence of a volatilization suppression layer 5. In the figure, the horizontal axis represents Capacity (discharge capacity) [mAh], and the vertical axis represents Battery voltage (battery voltage) [V].

Hereinafter, embodiments of the present invention will be described with reference to the drawings. Since the drawings referred to in the following description schematically show the embodiment, the scale, spacing, positional relationship, etc. of the members are exaggerated or deformed, or a part of the members is not shown. There may be. The following description shows specific examples of the contents of the present invention, and the present invention is not limited to these descriptions. Various changes and modifications can be made by those skilled in the art within the scope of the technical ideas disclosed herein. Further, in all the drawings for explaining the present invention, those having the same function may be designated by the same reference numerals, and the repeated description thereof may be omitted.
Further, in the present specification, "upper", "lower" and the like indicate relative positions between components, and are not intended to indicate absolute positions.
The "~" described in the present specification is used to mean that the numerical values described before and after the "~" are used as the lower limit value and the upper limit value. In the numerical range described stepwise in the present specification, the lower limit or upper limit described in one numerical range may be replaced with the lower limit or upper limit described in another stepwise. It may be replaced with the numerical value shown in the Example.

FIG. 1 is a schematic view showing the configuration of an aqueous solution-based secondary battery 100 according to the first embodiment of the present invention. FIG. 2 is a schematic view showing the configuration of the aqueous solution-based secondary battery 200 according to the second embodiment of the present invention. FIG. 3 is a schematic view showing the configuration of the aqueous solution-based secondary battery 300 according to the third embodiment of the present invention. FIG. 4 is a schematic view showing the configuration of the aqueous solution-based secondary battery 400 according to the fourth embodiment of the present invention.

(Aqueous solution type secondary battery 100)
As shown in FIG. 1, the aqueous solution-based secondary battery 100 according to the first embodiment includes a positive electrode 1, a negative electrode 2, an aqueous solution-based electrolyte 3, an exterior body 4, and a volatilization suppression layer 5. There is.
The aqueous solution-based secondary battery 100 is charged and discharged by the transfer of ions between the positive electrode 1 and the negative electrode 2 and the aqueous solution-based electrolytic solution 3. As shown in FIG. 1, the volatilization suppression layer 5 in the first embodiment is arranged on the upper part of the aqueous solution-based electrolytic solution 3. The volatilization suppression layer 5 may or may not be in contact with any one or all of the positive electrode 1, the negative electrode 2, and the aqueous electrolytic solution 3. If the volatilization suppressing layer 5 covers at least a part, preferably the upper part, around the aqueous electrolytic solution 3, the volatilization of the aqueous electrolytic solution 3 can be suppressed. The volatilization suppression layer 5 will be described in detail later. Further, the exterior body 4 includes a positive electrode 1, a negative electrode 2, an aqueous electrolytic solution 3, and a volatilization suppression layer 5. Hereinafter, these elements constituting the aqueous solution-based secondary battery 100 will be described.

(Positive electrode 1)
The positive electrode 1 is composed of a compound having an oxidation-reduction potential noble than the redox potential of the negative electrode 2. For example, the positive electrode 1 is selected from the group consisting of nickel hydroxide, nickel oxyhydroxide, nickel metal (nickel alone), nickel alloy, nickel oxide, manganese oxide, manganese dioxide, silver oxide, copper oxide, lead sulfate and lead oxide. Consists of containing at least one compound. Alternatively, the positive electrode 1 is configured by utilizing the redox reaction of oxygen. In this way, it can be suitably used for the aqueous solution-based secondary battery 100. In particular, for example, it can be suitably used for a nickel-zinc secondary battery, a nickel-hydrogen secondary battery, a nickel-manganese secondary battery, a lead storage battery, or the like.
The positive electrode 1 is electrically connected to the positive electrode terminal 1a. The positive electrode terminal 1a is connected to an external electric signal line 11 (see FIG. 5). The electric signal line 11 connected to the positive electrode terminal 1a is connected to the positive electrode of the power supply 8.

(Negative electrode 2)
The negative electrode 2 is arranged apart from the positive electrode 1. The negative electrode 2 is composed of a compound that is lower than the redox potential of the positive electrode 1. For example, the negative electrode 2 contains at least one compound selected from the group consisting of zinc hydroxide, zinc oxide, zinc metal (zinc alone), zinc alloy, cadmium metal, cadmium alloy, metal hydride, lead metal and lead sulfate. It is composed of things. In this way, it can be suitably used for the aqueous solution-based secondary battery 100. In particular, for example, it can be suitably used for a nickel-zinc secondary battery, a nickel-hydrogen secondary battery, a nickel-manganese secondary battery, a lead storage battery, or the like.
The negative electrode 2 is electrically connected to the negative electrode terminal 2a. The negative electrode terminal 2a is connected to an external electric signal line 11 (see FIG. 5). The electric signal line 11 connected to the negative electrode terminal 2a is connected to the negative electrode of the power supply 8 via the switch 10.

(Aqueous solution electrolyte 3)
The aqueous electrolytic solution 3 comes into contact with the positive electrode 1 and the negative electrode 2 and contains water. The aqueous electrolytic solution 3 is composed of a compound or solution having ionic conductivity and no electrical conductivity. For example, the aqueous electrolytic solution 3 is composed of an aqueous solution containing cations and anions. The pH of the aqueous electrolytic solution 3 is not particularly limited.

When the aqueous solution-based electrolytic solution 3 is an alkaline aqueous solution, it contains an alkaline agent for making the aqueous solution-based electrolytic solution 3 alkaline. The alkaline agent is ionized into at least one kind of cation (A ⁺ ) and hydroxide ion (OH ⁻ ) (anion (B ^{−)) in the aqueous 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. .. When these alkaline agents are used, they are easily dissolved in water and OH ⁻ can be suitably supplied. These alkaline agents are particularly suitably applicable to the nickel-based aqueous solution-based secondary battery 100.

The content of the alkaline agent shall be such that the charge / discharge reaction rate can be sufficiently increased by reducing the electrochemical polarization between the hydroxide ion contained in the aqueous electrolytic solution 3 and the positive electrode 1 and the negative electrode 2. Is preferable. Specifically, for example, the content of the alkaline agent is 10% by mass or more, preferably 15% by mass or more, as the content with respect to the aqueous electrolytic solution 3. When the content of the alkaline agent is 10% by mass or more, sufficient hydroxide ions used for charging / discharging can be secured. The content of the alkaline agent is, for example, 40% by mass or less, preferably 30% by mass or less. When the content of the alkaline agent is 40% by mass or less, oxygen generation at the positive electrode 1 due to excess hydroxide ions can be sufficiently suppressed.

When the aqueous solution-based electrolytic solution 3 is an acidic aqueous solution, it contains an acid for making the aqueous solution-based electrolytic solution 3 acidic. The acid is ionized into at least one kind of anion (B ⁻ ) and a proton (H ⁺ ) (cation (A ^{+)) in the aqueous electrolyte solution 3.} As the acid, for example, at least one acid selected from the group consisting of sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, phosphoric acid, bromic acid, iodic acid and organic acid can be used. When these acids are used, they can be easily mixed with water, and H ⁺ can be suitably supplied. These acids are particularly suitable for lead-acid batteries.

The acid content is preferably such that the charge / discharge reaction rate can be sufficiently increased by reducing the electrochemical polarization between the protons contained in the aqueous electrolytic solution 3 and the positive electrode 1 and the negative electrode 2. Specifically, for example, the content when sulfuric acid is used is 20% by mass or more as the content with respect to the aqueous electrolytic solution 3. When the content of sulfuric acid is 20% by mass or more, sufficient sulfuric acid ions used for charging / discharging can be secured. The content of sulfuric acid is, for example, 40% by mass or less. When the content of sulfuric acid is 40% by mass or less, it is possible to sufficiently suppress that the viscosity of the aqueous electrolytic solution 3 increases and the output characteristics of the secondary battery deteriorate.

The aqueous electrolytic solution 3 can contain any simple substance or compound in addition to the alkaline agent and the acid. Examples of the simple substance include zinc and silicon. Examples of the compound include a surfactant, sodium tetraborate, sodium perchlorate and the like.

(Exterior body 4)
The exterior body 4 contains a positive electrode 1, a negative electrode 2, and an aqueous electrolytic solution 3. The exterior body 4 can be formed into an arbitrary shape with a material having corrosion resistance to the aqueous electrolytic solution 3. The exterior body 4 can be formed of, for example, a bottomed square tubular or bottomed cylindrical main body and a lid that seals the opening of the main body. In this case, as the exterior body 4, for example, one in which the surface of a metal material such as aluminum, stainless steel, or nickel-plated steel is covered with a resin having corrosion resistance to the aqueous solution-based electrolytic solution 3 can be preferably mentioned. Further, as the exterior body 4, a housing made of a resin having corrosion resistance to the aqueous electrolytic solution 3 can be preferably used. When the exterior body 4 is formed by the main body and the lid, a resin sealing material may be interposed between the main body and the lid, if necessary. By doing so, it is possible to prevent electrolytes and the like from leaking from the gap between the main body and the lid. Further, as the exterior body 4, for example, one that is sealed with an arbitrary laminating material can be used.

Further, in the exterior body 4, the positive electrode terminal 1a connected to the positive electrode 1 is exposed to the outside from an arbitrary portion, and the negative electrode terminal 2a connected to the negative electrode 2 is exposed to the outside from an arbitrary portion. The positive electrode terminal 1a and the negative electrode terminal 2a can be formed of aluminum, aluminum alloy, copper, copper alloy, stainless steel, titanium, or the like in any shape.

(Volatilization suppression layer 5)
Then, in the present embodiment, the volatilization suppressing layer 5 is arranged in at least one selected from the group consisting of the upper part, the outer periphery, and the inner wall of the outer body 4 of the aqueous solution-based electrolytic solution 3 to suppress the volatilization of the aqueous solution-based electrolytic solution 3. To do. In FIG. 1 for explaining the first embodiment, a state in which the volatilization suppression layer 5 is arranged on the upper part of the aqueous solution-based electrolytic solution 3 is shown. Other arrangements of the volatilization suppression layer 5 will be described later as the second to fourth embodiments. Since the aqueous solution-based secondary battery 100 includes the volatilization suppressing layer 5, the volatilization of the aqueous solution-based electrolytic solution 3 can be suppressed even at a high temperature. Therefore, the water-based secondary battery 100 provided with the volatilization suppression layer 5 has a high output and a long life even at a high temperature.

The volatility suppression layer 5 includes a refractory liquid 5a and a porous retainer 5b that holds the refractory liquid 5a.
The retainer 5b may be any holder as long as it can retain the refractory liquid 5a as described above. For example, the retainer 5b may be a solid or a gel. Specifically, as the holding body 5b, at least one selected from the group consisting of a porous membrane, a porous body, cotton, cloth, paper, agar, gelatin, silica gel, silicone gel and water glass can be used. As the porous membrane, for example, one formed of polyethylene resin, ethylene tetrafluoride resin, or the like can be preferably used. Further, as the porous body, for example, one made of ceramics can be preferably used. The retainer 5b formed of these materials is stable to the aqueous electrolytic solution 3 (that is, difficult to react), and can suitably retain the refractory liquid 5a. The size and density of the pores of the retainer 5b may be any as long as it can retain the refractory liquid 5a, and is not particularly limited. Further, in the present specification, refractory means that the vapor pressure is smaller than that of water, and more preferably the vapor pressure at 25 ° C. is 3200 Pa or less.

The refractory liquid 5a may be any liquid as long as it can suppress the volatilization of the aqueous electrolytic solution 3. For example, as the refractory liquid 5a, at least one selected from the group consisting of mineral oil, vegetable oil and animal oil can be used. In this way, the poorly volatile liquid 5a easily floats on the aqueous solution-based electrolytic solution 3 and is difficult to mix with the aqueous solution-based electrolytic solution 3. Further, in this way, since the refractory liquid 5a does not conduct electricity, the positive electrode 1 and the negative electrode 2 are not short-circuited. Further, needless to say, since the refractory liquid 5a itself using these has low volatility, it is possible to realize the aqueous solution-based secondary battery 100 having high output and long life even at a high temperature. As the non-volatile liquid 5a, paraffin-based mineral oil is particularly suitable because it has a high viscosity and does not easily penetrate into the electrode plate group.

The ratio of the refractory liquid 5a to the retainer 5b is not particularly limited, but if it is excessive, the refractory liquid 5a permeates the inside of the electrode plate group, and if it is insufficient, the volatilization of the aqueous electrolytic solution 3 is suppressed. The effect is reduced. Therefore, it is preferable that the holding body 5b holds the poorly volatile liquid 5a at the upper limit of the holding amount. By doing so, the excessively volatile liquid 5a does not permeate into the inside of the electrode plate group, and the volatilization suppressing effect of the aqueous solution-based electrolytic solution 3 can be more reliably obtained.

(Aqueous solution type secondary battery 200)
As shown in FIG. 2, the aqueous solution-based secondary battery 200 according to the second embodiment is provided with a separator 6 between the positive electrode 1 and the negative electrode 2, and the aqueous solution-based secondary battery according to the first embodiment is provided. It is different from 100. Since the aqueous solution-based secondary battery 200 includes the separator 6, a short circuit between the positive electrode 1 and the negative electrode 2 can be more reliably prevented. The separator 6 can be made of a porous membrane or the like that allows ions and molecules to freely permeate. The separator 6 can be formed of, for example, the same material as the holder 5b.

As shown in FIG. 2, the arrangement of the separator 6 is not limited to the mode in which only one is provided between the positive electrode 1 and the negative electrode 2, and the arrangement can be arbitrarily changed. For example, the arrangement of the separator 6 may be such that two or more separators are provided between the positive electrode 1 and the negative electrode 2.

(Aqueous solution type secondary battery 300)
As shown in FIG. 3, the aqueous solution-based secondary battery 300 according to the third embodiment includes the liquid-retaining layer 7 between the positive electrode 1 and the negative electrode 2, and the aqueous solution-based secondary battery 300 according to the first embodiment is provided. It is different from the next battery 100. Further, in the aqueous solution-based secondary battery 300, the separator 6 is arranged between the positive electrode 1 and the liquid-retaining layer 7, and the separator 6 is arranged between the negative electrode 2 and the liquid-retaining layer 7. It is different from the aqueous solution-based secondary battery 100 according to the embodiment.

Since the aqueous solution-based secondary battery 300 includes the liquid-retaining layer 7, the aqueous solution-based electrolytic solution 3 can be impregnated therein, and the volatilization of the aqueous solution-based electrolytic solution 3 can be further suppressed. The liquid retention layer 7 can be composed of, for example, at least one material selected from the group consisting of non-woven fabric, paper, felt and knitted fabric.

As for the arrangement of the separator 6 and the liquid retention layer 7, as shown in FIG. 3, one separator 6 is arranged between the positive electrode 1 and the liquid retention layer 7, and the separator 6 and the liquid retention layer 7 are arranged between the negative electrode 2 and the liquid retention layer 7. The arrangement is not limited to the mode in which one separator 6 is arranged and the liquid retention layer 7 is arranged between the two separators 6, and the arrangement can be arbitrarily changed. For example, the separator 6 may be arranged in only one of the two separators 6 shown in FIG. Further, two or more separators 6 may be arranged between the positive electrode 1 and the liquid retention layer 7 and between the negative electrode 2 and the liquid retention layer 7. Further, in the aqueous solution-based secondary battery 300, the separator 6 may not be arranged.

(Aqueous solution type secondary battery 400)
As shown in FIG. 4, in the aqueous solution-based secondary battery 400 according to the fourth embodiment, the volatilization suppressing layer 5 is arranged on the outer periphery of the aqueous solution-based electrolytic solution 3, and from a different point of view, the volatilizing suppressing layer 5 is It differs from the aqueous solution-based secondary battery 100 according to the first embodiment in that it is arranged along the inner wall of the exterior body 4. In this way, since the volatilization suppression layer 5 is arranged on the outer periphery of the aqueous solution-based electrolytic solution 3, the volatilization of the aqueous solution-based electrolytic solution 3 from the upper part of the aqueous solution-based electrolytic solution 3 is prevented, and the volatilization of the aqueous solution-based electrolytic solution 3 is prevented from the wall surface of the exterior body 4. It is possible to prevent the aqueous electrolytic solution 3 from seeping out. In FIG. 4, the upper part of the volatilization suppression layer 5 is in contact with the exterior body 4, but the upper part of the volatilization suppression layer 5 does not necessarily have to be in contact with the exterior body 4. This also applies to the volatilization suppression layer 5 in the first to third embodiments, and the upper portion of the volatilization suppression layer 5 may be in contact with the exterior body 4 in the first to third embodiments as well. And it does not have to be in contact. Further, in FIG. 4, the volatilization suppression layer 5 is arranged in contact with the inner wall (for example, the side wall or the bottom) of the exterior body 4, but the volatilization suppression layer 5 is not necessarily in contact with the inner wall of the exterior body 4. May be good.

Further, the aqueous solution-based secondary battery 400 according to the fourth embodiment is provided with a liquid-retaining layer 7 between the positive electrode 1 and the negative electrode 2, and is located between the positive electrode 1 and the liquid-retaining layer 7, as in the third embodiment. It is different from the aqueous solution-based secondary battery 100 according to the first embodiment in that one separator 6 is arranged in the battery and one separator 6 is arranged between the negative electrode 2 and the liquid retention layer 7. Since these differences have been described in the third embodiment, the description thereof will be omitted.

(Aqueous solution system secondary battery system 500)
Next, the aqueous solution-based secondary battery system 500 according to the embodiment will be described with reference to FIG. FIG. 5 is a schematic view showing the configuration of an aqueous solution-based secondary battery system 500 according to an embodiment of the present invention. As the aqueous solution-based secondary battery shown in FIG. 5, the aqueous solution-based secondary battery 100 according to the first embodiment is typically shown, but instead of this, the aqueous solution-based secondary battery 200 to 400 can be applied. Needless to say.

As shown in FIG. 5, the aqueous solution-based secondary battery system 500 includes the above-mentioned aqueous solution-based secondary battery 100. Further, the aqueous solution-based secondary battery system 500 includes a power supply 8, an external load 9, and a switch 10.
In the aqueous solution-based secondary battery 100 in the aqueous solution-based secondary battery system 500, the positive electrode terminal 1a and the negative electrode terminal 2a are connected to the electric signal line 11 shown by the solid line in FIG. The power supply 8, the external load 9, and the switch 10 are connected by the electric signal line 11. As shown in FIG. 5, the external load 9 and the aqueous solution-based secondary battery 100 are connected in parallel.

In the example shown in FIG. 5, the aqueous solution-based secondary battery 100 is used as a backup power storage device for the external load 9. When the power supply 8 is operating normally, the switch 10 is closed, and the power supply 8 is connected to the aqueous solution-based secondary battery 100 and the external load 9 connected in parallel to the aqueous solution-based secondary battery 100. Power is supplied. Then, when the power supply 8 is unexpectedly cut off, the switch 10 is opened, and the electric power stored in the aqueous solution-based secondary battery 100 is supplied to the external load 9. By doing so, the aqueous solution-based secondary battery system 500 can use the aqueous solution-based secondary battery 100 as a backup power storage device for the external load 9 even when the power supply 8 is unintentionally turned off.

The external load 9 can be any external load 9 as long as it can be applied to the aqueous solution-based secondary battery system 500. Examples of the external load 9 include a power supply, a mobile body, an electronic device, and the like. Examples of the power source include, but are not limited to, a battery, a system power source, a distributed power source, a regenerated energy, and the like. Examples of moving objects include, but are not limited to, automobiles, motorcycles, electric bicycles, railroad vehicles, ships, submarines, aircraft, spacecraft, and the like. Examples of electronic devices include, but are not limited to, mobile terminals, information and communication devices, computers, game machines, CD players, DVD players, video cameras, digital cameras, drones, and the like.

(effect)
As described above, the aqueous solution-based secondary batteries 100 to 400 according to the first to fourth embodiments and the aqueous solution-based secondary battery system 500 according to the position embodiment are the upper portion and the outer periphery of the aqueous solution-based electrolyte solution 3. Since the volatilization suppression layer 5 is arranged in at least one selected from the group consisting of the inner wall of the exterior body 4 and the outer wall 4, the volatilization of the aqueous electrolytic solution 3 can be suppressed. Therefore, the aqueous solution-based secondary batteries 100 to 400 have high output and long life even at high temperatures. Further, since the aqueous solution-based secondary battery system 500 includes the aqueous solution-based secondary batteries 100 to 400, it also has a high output and a long life even at a high temperature.

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

(Life at high temperature)
As the aqueous electrolyte solution 3, an alkaline aqueous solution containing 20% by mass of potassium hydroxide, 5% by mass of sodium hydroxide, and 1% by mass of lithium hydroxide with respect to the total weight is used for aqueous solution-based electrolysis. The volatilization amount of the liquid 3 was measured. As the refractory liquid 5a of the volatility suppression layer 5, any one of an insulating oil for an ultrahigh voltage device, a pump oil, and liquid paraffin was used, and polypropylene cotton was used as the holder 5b.

FIG. 6 shows the ratio (liquid retention rate) of the aqueous electrolytic solution 3 remaining after 4 days at an environmental temperature of 55 ° C. That is, FIG. 6 is a graph showing the retention rate (liquid retention rate) of the aqueous solution-based electrolytic solution 3 in the presence or absence of the volatilization suppression layer 5. In this experiment, no electrode was used and no voltage was applied, so that the aqueous electrolytic solution 3 was not electrolyzed. Therefore, the decrease of the aqueous electrolytic solution 3 is entirely due to volatilization.

As shown in FIG. 6, as compared with Comparative Example 1 not provided with the volatilization suppression layer, Example 1 (insulating oil for ultrahigh voltage equipment + polypropylene cotton) and Example 2 (pump oil + polypropylene) using the volatilization suppression layer 5 were used. In Cotton) and Example 3 (liquid paraffin + polypropylene cotton), the volatilization amount of the aqueous electrolyte 3 after 4 days was reduced to 1/60 or less. From this experiment, it was confirmed that the volatilization of the aqueous electrolytic solution 3 was suppressed by using the volatilization suppression layer 5. That is, it was confirmed that the aqueous solution-based secondary battery having a long life can be realized even at a high temperature by using the volatility suppressing layer 5, that is, by using the refractory liquid 5a and the holding body 5b.

(Output at high temperature)
Next, a nickel hydroxide metal plate was prepared as the positive electrode 1, and a zinc oxide metal plate was prepared as the negative electrode 2. Further, as the aqueous electrolytic solution 3, an alkaline aqueous solution containing 20% by mass of potassium hydroxide, 5% by mass of sodium hydroxide, and 1% by mass of lithium hydroxide with respect to the total weight was prepared. A porous membrane was used as the separator 6, and a non-woven fabric was used as the liquid retention layer 7. Then, using polypropylene cotton impregnated with liquid paraffin as the volatilization suppression layer 5, an aqueous solution-based secondary battery 300 (Example 4) having the configuration shown in FIG. 3 was produced.
Further, in order to compare with this Example 4, an aqueous solution-based secondary battery (Comparative Example 2) not provided with a volatilization suppression layer and an aqueous solution-based secondary battery (Comparative Example) in which only liquid paraffin is added on the aqueous solution-based electrolyte 3. 3) and was prepared.

The aqueous secondary battery 300 according to Example 4 after the initial activation treatment and the aqueous secondary battery according to Comparative Examples 2 and 3 after the initial activation treatment are each subjected to a current density of 1C. FIG. 7 shows a discharge curve discharged by a current density of 4C after charging to 90V. That is, FIG. 7 is a graph showing a discharge curve with and without the volatilization suppression layer 5. The current density of 1C represents a current density that takes one hour to fully charge or discharge all the battery capacity. The current density of 4C means four times the current density of 1C. In the initial activation treatment, the electrodes were activated by repeating charging and discharging at a current density lower than 1C.

As shown in FIG. 7, the discharge voltage of the discharge curve of Comparative Example 3 was remarkably reduced as compared with the discharge curve of Comparative Example 2, and the discharge capacity was reduced to 1/6 or less. This is caused by the increase in internal resistance due to the permeation of the liquid paraffin of Comparative Example 3 into the inside of the electrode plate group.
On the other hand, in Example 4, both the discharge voltage and the discharge capacity were significantly improved as compared with Comparative Example 3, and the performance was about the same as that of Comparative Example 2. That is, it was confirmed that the aqueous solution-based secondary battery having high output can be realized even at a high temperature by using the volatility suppressing layer 5, that is, by using the poorly volatile liquid 5a and the holding body 5b.

(Summary)
From the above results, it was confirmed that by providing the volatilization suppressing layer 5, the volatilization of the aqueous solution-based electrolytic solution 3 can be suppressed even at a high temperature, and at the same time, the discharge at a high output can be maintained. That is, it has been confirmed that the present invention can provide an aqueous solution-based secondary battery and an aqueous solution-based secondary battery system having high output and long life even at high temperatures.

Although the aqueous solution-based secondary battery and the aqueous solution-based secondary battery system according to the present invention have been described in detail with reference to the embodiments and examples, the gist of the present invention is not limited to this, and various modifications can be made. included. For example, the above-described embodiment has been described in detail in order to explain the present invention in an easy-to-understand manner, and is not necessarily limited to the one including all the described configurations. Further, it is possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. Further, it is possible to add / delete / replace a part of the configuration of each embodiment with another configuration.

100, 200, 300, 400 Aqueous secondary battery 500 Aqueous secondary battery system 1 Positive electrode 1a Positive electrode terminal 2 Negative electrode 2a Negative electrode terminal 3 Aqueous electrolyte 4 Exterior 5 Volatilization suppression layer 5a Refractory liquid 5b Holder 6 Separator 7 Liquid retention layer 8 Power supply 9 External load 10 Switch 11 Electrical signal line

Claims (8)

With the positive electrode
A negative electrode arranged apart from the positive electrode and
An aqueous electrolyte solution that comes into contact with the positive electrode and the negative electrode and contains water,
The positive electrode, the negative electrode, and an exterior body containing the aqueous electrolytic solution are provided.
It is provided with a volatilization suppressing layer which is arranged in at least one selected from the group consisting of the upper part, the outer periphery and the inner wall of the outer body of the aqueous solution-based electrolytic solution and suppresses the volatilization of the aqueous solution-based electrolytic solution.
An aqueous solution-based secondary battery in which the volatility suppressing layer comprises a refractory liquid and a porous retainer that holds the refractory liquid. The aqueous solution-based secondary battery according to claim 1, wherein the retainer includes at least one selected from the group consisting of a porous film, a porous body, cotton, cloth, paper, agar, gelatin, silica gel, silicone gel, and water glass. The aqueous secondary battery according to claim 1, wherein the refractory liquid contains at least one selected from the group consisting of mineral oil, vegetable oil and animal oil. The positive electrode contains at least one selected from the group consisting of nickel hydroxide, nickel oxyhydroxide, nickel metal, nickel alloy, nickel oxide, manganese oxide, manganese dioxide, silver oxide, copper oxide, lead sulfate and lead oxide.
The aqueous solution system according to claim 1, wherein the negative electrode contains at least one selected from the group consisting of zinc hydroxide, zinc oxide, zinc metal, zinc alloy, cadmium metal, cadmium alloy, metal hydride, lead metal and lead sulfate. Secondary battery. The aqueous solution-based secondary battery according to claim 1, wherein the holding body holds the refractory liquid at an upper limit of the holding amount. The aqueous solution-based electrolytic solution contains 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. The aqueous secondary battery according to any one of 5 to 5. The solution according to any one of claims 1 to 5, wherein the aqueous electrolytic solution contains at least one acid selected from the group consisting of sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, phosphoric acid, bromic acid, iodic acid and organic acid. The aqueous secondary battery described. An exterior body that comes into contact with a positive electrode, a negative electrode arranged apart from the positive electrode, the positive electrode and the negative electrode, and contains an aqueous electrolytic solution containing water, the positive electrode, the negative electrode, and the aqueous electrolytic solution. And, provided with a volatilization suppression layer which is arranged in at least one selected from the group consisting of the upper part, the outer periphery, and the inner wall of the outer body of the aqueous electrolytic solution to suppress the volatilization of the aqueous electrolytic solution. An aqueous secondary battery system comprising an aqueous secondary battery in which the volatilization suppression layer comprises a refractory liquid and a porous retainer that holds the refractory liquid.

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