JP5812403B2 - Alkaline secondary battery - Google Patents

Description

The present invention relates to an alkaline secondary battery.
More specifically, the present invention relates to an alkaline secondary battery that can extend the life of a charge / discharge cycle.

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), and the development of secondary batteries for motor drive that will be the key to the practical application of these technologies is thriving. Has been 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, dendrites and morphological changes that occur during the deposition of zinc have been pointed out as a cause of a short charge / discharge cycle life.

  On the other hand, the negative electrode is an air battery composed of a gel mixture composed of a negative electrode active material and a gelled ion exchange resin, and the negative electrode is a metal negative electrode active material and a negative electrode active material provided on the surface thereof for ion exchange. There has been proposed an air battery including a layer mixed with a resin (see Patent Document 1).

JP 2001-176564 A

  However, in the air battery described in Patent Document 1, hydrogen gas generated by a side reaction during charging accumulates at the interface between the negative electrode active material and the ion exchange resin, and contact between the aqueous electrolyte and the negative electrode active material is prevented. There was a problem that it was hindered and a long charge / discharge cycle could not be performed.

  The present invention has been made in view of such problems of the prior art. And the place made into the objective of this invention is providing the alkaline secondary battery which can prolong the life of a charging / discharging cycle.

The inventors of the present invention have made extensive studies in order to achieve the above object. As a result, it has been found that the above object can be achieved when the coating containing the ion exchange resin formed on the negative electrode or the negative electrode active material contains at least one of indium oxide and lead oxide. The invention has been completed.

That is, the alkaline secondary battery of the present invention includes a positive electrode, a negative electrode including at least one of zinc and a zinc compound as a negative electrode active material, a film including an ion exchange resin formed on the negative electrode or the negative electrode active material, an alkali An electrolyte containing an aqueous solution as an electrolytic solution.
In the alkaline secondary battery of the present invention, the upper Symbol coating comprises at least one of indium oxide and lead oxide.

According to the present invention, the coating film including the ion exchange resin formed on the negative electrode or the negative electrode active material includes at least one of indium oxide and lead oxide .
Therefore, an alkaline secondary battery that can extend the life of the charge / discharge cycle can be provided.

It is sectional drawing which shows the outline of the test cell of each example. It is the graph which showed the result of the charging / discharging efficiency for every cycle of the reference example 1-1, the comparative example 1-1, and the comparative example 1-2. It is the graph which showed the result of the charging / discharging efficiency for every cycle of Reference Example 2-1 to Reference Example 2-3 and Comparative Example 2-1. It is the graph which showed the result of the charging / discharging efficiency for every cycle of the reference example 3-1. It is the graph which showed the result of the charging / discharging efficiency for every cycle of Example 4-1 and Example 4-2.

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

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 as a negative electrode active material, a film including an ion exchange resin formed on the negative electrode or the negative electrode active material, an alkali And an electrolyte containing an aqueous solution as an electrolytic solution.
Further, the negative electrode, the coating, the electrolyte, or any combination thereof in the alkaline secondary battery of this embodiment is a metal having a melting point that is nobler than the standard electrode potential of zinc and lower than the melting point of zinc, the metal Oxides containing, salts containing the metal, ions containing the metal, or any combination thereof.
By setting it as such a structure, it becomes an alkaline secondary battery which can prolong the life of a charge / discharge cycle.

  Hereinafter, each component will be described in detail.

  The positive electrode was composed of an air electrode composed of a carbon material, an oxygen reduction catalyst and a binder, a metal (per) oxide mainly composed of nickel oxyhydroxide, and a current collector such as nickel foam. It can be mentioned as a suitable example such as a nickel electrode. However, it is not limited to this, The conventionally well-known material used as a positive electrode of an alkaline secondary battery can be applied 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 as a negative electrode active material.

  Examples of the ion exchange resin contained in the coating include cation exchange resin alone, anion exchange resin alone, a mixture of cation exchange resin and anion exchange resin, a mixture of cation exchange resin and nonionic resin, and anion exchange resin and non-ion exchange resin. The thing comprised with a mixture with an ionic resin can be mentioned.

  Among them, a cation exchange resin can be suitably used from the viewpoint that the dissolution and precipitation of the negative electrode active material are repeatedly and smoothly performed.

  Furthermore, these ion exchange resins preferably have a sulfonic acid group, a phosphoric acid group, a carboxylic acid group, and the like. By having such a group, the diffusion of the zinc discharge product can be suppressed, and the shape change can be more effectively suppressed even by a long charge / discharge cycle.

The coating containing the ion exchange resin is preferably present stably without hindering elution or deposition in the electrolytic solution accompanying charging / discharging of the negative electrode active material.
As a method for forming a film containing an ion exchange resin, a conventionally known film forming method can be appropriately employed. For example, a method in which a dispersion in which an ion exchange resin is dispersed in a solvent having a good dispersibility at an appropriate concentration is applied using a spin coater or the like to form a film can be applied.
The thickness of such a coating is usually a few μm, but it is sufficient that dissolution and deposition of the negative electrode active material be performed smoothly and efficiently, and these methods and the thickness of the coating are limited. is not.

  Preferred examples of the alkaline aqueous solution constituting the electrolytic solution contained in the electrolyte include a potassium hydroxide (KOH) aqueous solution and a sodium hydroxide (NaOH) aqueous solution, but are not limited thereto. That is, the electrolyte is not limited to these electrodes and electrolytes as long as the redox reaction with the negative electrode containing zinc or a zinc compound as a negative electrode active material can be repeatedly performed.

  In addition, the negative electrode, the coating, the electrolyte, or any combination thereof is a metal having a melting point that is nobler than the standard electrode potential of zinc and lower than the melting point of zinc, an oxide containing the metal, and a salt containing the metal Alternatively, the aspect including an ion including the metal or any combination thereof includes a metal partially deposited on the surface of the negative electrode active material, an oxide including the metal, a salt including the metal, and an ion including the metal. There is no particular limitation as long as the crystal grain boundary on the surface of the negative electrode active material in contact with the electrolytic solution is reduced, the active points for hydrogen gas generation are reduced, and hydrogen gas generation is suppressed. More preferably, the metal oxide or the metal salt is dissolved in an alkali solvent, but it may be simply dispersed without being precipitated in the alkali solvent.

  Here, “a metal-containing oxide” and “a metal-containing salt” are a metal oxide and a metal salt, respectively. However, “a metal-containing ion” is not limited to a metal ion. It must be interpreted to mean including polyatomic ions.

  Metals having a melting point higher than the standard electrode potential of zinc and lower than the melting point of zinc, metal-containing oxides, metal-containing salts, metal-containing ions include indium, bismuth, lead, thallium oxides, halogens Preferred examples include compounds, sulfates, nitrates or acetates or ions thereof.

  As a suitable form of the said aspect, the following suitable forms can be mentioned, for example.

As a 1st suitable form, the aspect in which the electrolyte solution contained in electrolyte contains the ion containing the metal which is nobler than the standard electrode potential of zinc and lower than melting | fusing point of zinc can be mentioned.
By setting it as an ion state, ion permeate | transmits the inside of an ion exchange resin, and it supplies to the surface of a negative electrode or a negative electrode active material, and generation | occurrence | production of hydrogen gas is suppressed.

Moreover, as a 2nd suitable form, the aspect which contains the metal which is nobler than the standard electrode potential of zinc and lower than melting | fusing point of zinc in the surface or inside of a negative electrode active material can be mentioned.
In addition, about the method of making the said metal be included in the surface or inside of a negative electrode or a negative electrode active material, a conventionally well-known method can be suitably employ | adopted. For example, an electroless plating method can be applied. That is, this is a method in which a negative electrode active material is immersed in a solution in which one or more kinds of metal oxides or metal salts are dissolved for a certain period of time, and such a metal is deposited on the surface of the negative electrode active material. The completion of the formation of such metal deposits can be determined at the time when the surface color changes. As another method, the negative electrode active material is immersed as an electrode in a solution in which one or more kinds of metal oxides or metal salts are dissolved, and an appropriate metal plate such as platinum is disposed on the counter electrode, or is attached thereto. Furthermore, an appropriate reference electrode is disposed, and the potential is swept as appropriate at regular intervals to deposit such a metal on the surface of the negative electrode active material. The completion of the formation of such metal deposition can be completed when the change in the current value becomes small. However, the formed metal is not limited to these methods as long as the hydrogen overvoltage can be reduced without hindering dissolution and precipitation of the negative electrode active material.
The thickness of such a deposited metal is the same as or thinner than that of a film containing an ion exchange resin, but also with respect to this thickness, the dissolution and deposition of the negative electrode active material are repeated smoothly and smoothly. There is no limitation as long as it is efficiently performed.

Furthermore, as a third preferred embodiment, a film containing an ion exchange resin contains an oxide or an ion containing a metal that is noble than the standard electrode potential of one or more kinds of zinc and lower than the melting point of zinc. The aspect which contains can be mentioned.
In addition, as for the method of containing an oxide, salt, ion, or the like containing the above metal in the coating containing a cation exchange resin, a conventionally known method can be appropriately employed. For example, as a dispersion solution containing a cation exchange resin, a method in which a solution containing an oxide, salt, or ion containing the above metal is added to a negative electrode or a negative electrode active material using a spin coater or the like can be mentioned. However, it is not limited to these methods.

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

( Reference Example 1-1)
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, melting point of zinc: 419.5 ° C.) 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.
Next, a film was formed on the negative electrode active material. About 500 μL of NAFION dispersion (manufactured by DuPont) containing NAFION as an ion exchange resin was dropped on the surface of the obtained negative electrode, and a film was formed on the negative electrode active material by spin coating at an appropriate rotation speed. The thickness of the NAFION coating after drying was about 4 mm.
Furthermore, 0.02 g of lead oxide (melting point of lead: 327.46 ° C.) per 1 L was dissolved in 4N potassium hydroxide (KOH) aqueous solution to obtain an electrolyte 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 a film, 4 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 electrolyte 4, 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.

(Comparative Example 1-1)
Without forming the coating on Example 1 -1, potassium hydroxide (KOH) aqueous solution of 4N instead of the electrolyte of Example 1-1, except that the electrolyte used in the present example, as in Reference Example 1-1 The same operation was repeated to produce a test cell of this example as shown in FIG.

(Comparative Example 1-2)
The aqueous potassium hydroxide (KOH) of 4N instead of the electrolyte of Example 1-1, except that the electrolyte used in the present embodiment, repeating the same procedure as in Reference Example 1-1, as shown in FIG. 1 The test cell of this example was produced.

The test cell of each example produced in this manner was assembled to each test cell, and after waiting for the circuit voltage to stabilize, an electrochemical measurement system was used, and -1.18 V (vs. Hg / HgO, the same applies below). A charge / discharge test was performed by starting a discharge at room temperature with a voltage range of ˜−1.46 V and a current value of 0.5 mA / cm ² per negative electrode area with a pause of 10 minutes. The ratio of the charge capacity to the discharge capacity was compared and evaluated as charge / discharge efficiency (%).
The obtained results are shown in FIG. That is, FIG. 2 is a diagram showing the results of charge and discharge efficiency for each cycle of Reference Example 1-1, Comparative Example 1-1, and Comparative Example 1-2. A curve 2-1 in FIG. 2 shows a change in the charge / discharge efficiency cycle of Reference Example 1-1, a curve 2-2 shows a change in the charge / discharge efficiency cycle of Comparative Example 1-1, and a curve 2-3 shows a comparison. The change by the cycle of the charging / discharging efficiency of Example 1-2 is shown.
As is clear from FIG. 2, the reference example 1-1 has a stable and excellent result in which the charge / discharge efficiency is closest to 100% in all cycles as compared with the comparative example 1-1 and the comparative example 1-2. Indicated.

( Reference Example 2-1)
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, melting point of zinc: 419.5 ° C.) 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.
Next, a film was formed on the negative electrode active material. About 500 μL of NAFION dispersion (manufactured by DuPont) containing NAFION as an ion exchange resin was dropped on the surface of the obtained negative electrode, and a film was formed on the negative electrode active material by spin coating at an appropriate rotation speed. The thickness of the NAFION coating after drying was about 4 mm.
Further, 0.0002 g of lead oxide (melting point of lead: 327.46 ° C.) per 1 L was dissolved in a 4N potassium hydroxide (KOH) aqueous solution to obtain an electrolyte 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.

( Reference Example 2-2)
(Melting point of lead: 327.46 ° C.) lead oxide 1L per 0.02g in aqueous potassium hydroxide (KOH) of 4N instead of the electrolyte of Example 2-1 except that the electrolyte containing dissolved, the reference The same operation as in Example 2-1 was repeated to produce a test cell of this example as shown in FIG. This example is the same as Reference Example 1-1.

( Reference Example 2-3)
Lead oxide (Pb mp: 327.46 ° C.) of the electrolyte 1L per 0.2g aqueous solution of potassium hydroxide (KOH) of 4N instead of Reference Example 2-1 except that the electrolyte containing dissolved, the reference The same operation as in Example 2-1 was repeated to produce a test cell of this example as shown in FIG.

(Comparative Example 2-1)
The aqueous potassium hydroxide (KOH) of 4N instead of the electrolyte of Example 1-1, except that the electrolyte used in the present embodiment, repeating the same procedure as in Reference Example 1-1, as shown in FIG. 1 The test cell of this example was produced. This example is the same as Comparative Example 1-2.

The test cell of each example produced in this way is assembled in the test cell, and then waits for the circuit voltage to stabilize, and then uses an electrochemical measurement system to set a voltage range of -1.18V to -1.46V, A charge / discharge test was conducted by starting a discharge at room temperature with a pause of 10 minutes at a current value of 0.5 mA / cm ² per negative electrode area. The ratio of the charge capacity to the discharge capacity was compared and evaluated as charge / discharge efficiency (%).
The obtained results are shown in FIG. That is, FIG. 3 is a graph showing the results of charge and discharge efficiency of each cycle of the reference examples 2-1 to Reference Example 2-3 and Comparative Example 2-1. A curve 3-1 in FIG. 3 indicates a change due to the cycle of the charge / discharge efficiency of Reference Example 2-1, a curve 3-2 indicates a change due to the cycle of the charge / discharge efficiency of Reference Example 2-2, and a curve 3-3 indicates the reference. The curve 3-4 shows the change of the charge / discharge efficiency of Example 2-3 due to the cycle, and the curve 3-4 shows the change of the charge / discharge efficiency of Comparative Example 2-1 due to the cycle.
As is clear from FIG. 3, Reference Example 2-1 to Reference Example 2-3 showed cycle stability of charge / discharge efficiency superior to that of Comparative Example 2-1.

( Reference Example 3-1)
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, melting point of zinc: 419.5 ° C.) as a negative electrode active material was cut into a predetermined size, and the surface was washed with ethanol. Next, a solution in which 2 g of lead oxide per liter was dissolved in 4N potassium hydroxide (KOH) aqueous solution was prepared, and a zinc plate washed with ethanol was immersed in the outer solution for 2 hours to form a lead layer on the surface of the zinc plate. Thus, the negative electrode used in this example was obtained.
Next, a film was formed on the negative electrode on which the lead layer was formed. About 500 μL of NAFION dispersion (manufactured by DuPont) containing NAFION, which is an ion exchange resin, was dropped on the surface of the obtained negative electrode, and a film was formed on the negative electrode by spin coating at an appropriate rotation speed. The thickness of the NAFION coating after drying was about 4 mm.
Furthermore, 4N potassium hydroxide (KOH) aqueous solution was used as the electrolyte 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.

The test cell of Reference Example 3-1 produced in this way was assembled to the test cell, and after waiting for the circuit voltage to stabilize, an electrochemical measurement system was used, and a voltage of -1.18V to -1.46V was used. A charge / discharge test was conducted starting from discharge at room temperature with a rest of 10 minutes at a current value of 0.5 mA / cm ² per area and negative electrode area. The ratio of the charge capacity to the discharge capacity was compared and evaluated as charge / discharge efficiency (%).
The obtained results are shown in FIG. That is, FIG. 4 is a diagram showing the results of charge and discharge efficiency for each cycle of Reference Example 3-1. A curve 4-1 in FIG. 4 shows a change in the charge / discharge efficiency of Reference Example 3-1 due to the cycle.
As is clear from FIG. 4, Reference Example 3-1 showed excellent charge / discharge efficiency.

(Example 4-1)
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, melting point of zinc: 419.5 ° C.) 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.
Next, a film was formed on the negative electrode active material. NAFION dispersion (made by DuPont) containing NAFION, which is an ion exchange resin, is mixed with 2 mL and 10 mg of lead oxide, and the resulting mixture is dropped on the surface of the negative electrode, followed by spin coating at an appropriate rotational speed. A coating was formed on top. The thickness of the NAFION coating after drying was about 4 mm.
Furthermore, 4N potassium hydroxide (KOH) aqueous solution was used as the electrolyte 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.

(Example 4-2)
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, melting point of zinc: 419.5 ° C.) 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.
Next, a film was formed on the negative electrode active material. NAFION dispersion (manufactured by DuPont) containing NAFION, which is an ion exchange resin, is mixed with 2 mL and 10 mg of indium oxide. A coating was formed on top. The thickness of the NAFION coating after drying was about 4 mm.
Furthermore, 4N potassium hydroxide (KOH) aqueous solution was used as the electrolyte 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.

The test cells of Example 4-1 and Example 4-2 manufactured as described above were assembled using the electrochemical measurement system after waiting for the circuit voltage to stabilize after the test cells were assembled. A charge / discharge test was conducted starting from discharge at room temperature with a voltage range of −1.46 V and a current value of 0.5 mA / cm ² per negative electrode area with a pause of 10 minutes. The ratio of the charge capacity to the discharge capacity was compared and evaluated as charge / discharge efficiency (%).
The obtained results are shown in FIG. That is, FIG. 5 is a diagram illustrating the results of charge and discharge efficiency for each cycle of Example 4-1 and Example 4-2. A curve 5-1 in FIG. 4 shows a change due to the cycle of the charge / discharge efficiency of Example 4-1, and a curve 5-2 shows a change due to the cycle of the charge / discharge efficiency of Example 4-2.
As is clear from FIG. 5, Example 4-1 and Example 4-2 showed excellent charge / discharge efficiency.

From the results of each example, the negative electrode or the negative electrode active material has a coating containing an ion exchange resin, and the negative electrode, the coating, the electrolyte, or any combination thereof is more noble than the standard electrode potential of zinc and zinc The structure includes a metal having a melting point lower than the melting point of the metal, an oxide containing the metal, a salt containing the metal, an ion containing the metal, or any combination thereof. It can be inferred that it was achieved.
In addition, when a cation exchange resin, a sulfonic acid group, a phosphoric acid group, or a carboxylic acid is used as the ion exchange resin, it is presumed that the charge / discharge cycle can be extended.
Furthermore, it can be inferred that the life of the charge / discharge cycle could be extended because indium, bismuth, thallium, lead, or the like was applied as a metal having a melting point lower than the zinc standard electrode potential and lower than the melting point of zinc.

DESCRIPTION OF SYMBOLS 1 Positive electrode 2 Negative electrode 3 Coating 4 Electrolyte 10 Reference electrode 11 Housing 12 Bottom holder 13 Cover

Claims (3)

A positive electrode;
A negative electrode containing at least one of zinc and a zinc compound as a negative electrode active material;
A film containing an ion exchange resin formed on the negative electrode or the negative electrode active material;
An electrolyte containing an alkaline aqueous solution as an electrolyte,
The alkaline secondary battery, wherein the coating contains at least one of indium oxide and lead oxide . The alkaline secondary battery according to claim 1 , wherein the ion exchange resin is a cation exchange resin. The alkaline secondary battery according to claim 1 or 2 , wherein the ion exchange resin has at least one group selected from the group consisting of a sulfonic acid group, a phosphoric acid group, and a carboxylic acid group.

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