JP4309311B2 - Aluminum battery - Google Patents

Description

  The present invention relates to a battery using aluminum as a negative electrode active material.

  Currently, manganese batteries and alkaline batteries are widely used for portable devices. However, since these batteries have zinc as the negative electrode active material, the operating voltage is as low as 1.5 V and 1.2 V, and cannot meet the demand for higher voltage accompanying the development of portable devices. In addition, regarding the duration and weight, there is a demand for a light battery that can be used for a longer time and is light.

  On the other hand, a battery using aluminum as a negative electrode active material can be expected to have a higher voltage, higher capacity, and lighter weight than a battery having a zinc negative electrode, but the negative electrode active material and the electrolyte react to generate gas, There is a problem that the self-discharge amount is large.

  In Patent Document 1, when an aluminum alloy containing at least one transition metal element selected from the group consisting of Mn, Cr, Sn, Ca, Mg, Pb, Si, In, and Zn is used as the negative electrode active material, There is a description that corrosion of the negative electrode is suppressed and self-discharge is suppressed. In Patent Document 1, it is described that it is desirable to use chlorine ions as halogen ions added to the electrolytic solution in order to obtain a high capacity.

However, the electrolytic solution containing chlorine ions reacts with the aluminum oxide film formed on the surface of the negative electrode containing the above aluminum alloy to increase the water solubility of the oxide film, so that the oxide film on the negative electrode surface dissolves in the electrolytic solution. The exposed area that is not covered with the oxide film grows greatly as the discharge progresses, so the amount of reaction between the aluminum component in the negative electrode and the water in the electrolyte increases, and the amount of gas generated during discharge There is a problem that it cannot withstand long-time discharge.
Japanese Patent Laid-Open No. 2001-319662

  It is an object of the present invention to provide an aluminum battery with improved discharge duration.

An aluminum battery according to the present invention comprises a positive electrode,
An intermetallic compound comprising at least one of aluminum and an aluminum alloy and at least two elements selected from the group consisting of Al, Mg, Zn, Mn, Sn, and In, which are homogeneously dispersed in the aluminum and the aluminum alloy A negative electrode containing a negative electrode active material containing 0.001 wt% or more and 30 wt% or less,
And an electrolytic solution containing an iodine component.

  According to the present invention, an aluminum battery having a long discharge duration can be provided.

As a result of intensive studies, the inventors have found that 0.001 to 30% by weight of an intermetallic compound composed of at least two elements selected from the group consisting of Al, Mg, Zn, Mn, Sn and In, an aluminum alloy and It was found that when a negative electrode active material containing at least one of aluminum and an electrolytic solution containing an iodine component were provided, the amount of gas generated during discharge was reduced and the discharge duration was increased. . This is because iodine components such as iodine ions have redox ability of I ⁻ ions and I ₃ ⁻ ions, and the solubility of the reaction products with aluminum hydroxide and oxide in the electrolyte is low. This is probably because of this. In particular, by having the redox ability, it is possible to obtain an effect of moderately retaining defects in the oxide film formed on the negative electrode surface. Specifically, it is considered that gas generation during discharge is suppressed by the mechanism described below.

A film of aluminum oxide (for example, Al ₂ O ₃ ) is formed on the surface of the negative electrode containing the above-described intermetallic compound and at least one of an aluminum alloy and aluminum. By reacting with iodine ions, the solubility of the film in water can be increased. Since the water-soluble property of the modified protective film is lower than that derived from chlorine ions, peeling from the negative electrode surface can be reduced as compared with the case where chlorine ions are used. Moreover, the oxide film can be regenerated on the negative electrode surface due to the redox ability of iodine ions. As a result, defects in the oxide film formed on the negative electrode surface can be maintained at a constant size and almost constant during discharge, so that the reaction between the aluminum component in the negative electrode and the water in the electrolyte is suppressed. It is estimated that the discharge can be promoted, the amount of hydrogen gas generated during the discharge can be reduced, and the discharge duration can be improved.

  Further, when the electrolyte contains at least one of nitrate ion and sulfate ion, the discharge gas can be further suppressed.

  Hereinafter, the positive electrode, the negative electrode, and the electrolytic solution will be described.

1) Positive electrode The positive electrode includes a positive electrode mixture containing a positive electrode active material and a current collector.

  Examples of the positive electrode active material include metal oxides, metal sulfides, and conductive polymers.

Examples of the metal oxide include manganese dioxide (MnO ₂ ), lead dioxide (PbO ₂ ), nickel hydroxide {NiOOH or Ni (OH) ₂ }, silver oxide (Ag ₂ O), iron oxide {eg, FeO, Fe ₂ O ₃ , FeO _x (where x is x> 1.5), M _x FeO ₄ (where M is at least one selected from the group of Li, K, Sr and Ba, x is x ≧ 1)}, etc. Can be mentioned. Examples of the conductive polymer include polyaniline, polypyrrole, sulfur, and organic sulfur compounds such as disulfide compounds. Among these, manganese dioxide is preferable.

  The positive electrode mixture can contain a conductive agent. Examples of the conductive agent include graphite, acetylene black, and carbon black.

  By containing a conductive agent in the positive electrode mixture, the electron conductivity between the positive electrode mixture and the current collector can be improved. The content of the conductive agent in the positive electrode mixture is preferably in the range of 1 to 20% by weight. If the amount is less than 1% by weight, the electron conductivity in the positive electrode mixture cannot be sufficiently increased. If the amount exceeds 20% by weight, the content of the positive electrode active material is decreased, and the positive electrode reaction is sufficiently performed. Because there is a risk that it will not be possible.

  The positive electrode mixture is produced, for example, by mixing a powdered positive electrode active material and a conductive agent, and then pressing the mixture into a pellet. Moreover, you may fix a positive mix on the collector surface by mixing a binder in a positive mix as needed.

  Examples of the binder to be contained in the positive electrode mixture include polytetrafluoroethylene.

  The positive electrode current collector that supports the positive electrode mixture can improve the electron conductivity between the positive electrode mixture and the positive electrode terminal.

  As a material used for the positive electrode current collector, for example, at least one selected from tungsten (W), molybdenum (Mo), lead (Pb), and titanium nitride (TiN), or a conductive material such as a carbonaceous material is contained. It is preferable to use one.

  This positive electrode current collector may be a porous material or a non-porous material. In the positive electrode current collector, tungsten (W), molybdenum (Mo), and lead (Pb) may exist in a single state, but are included as an alloy composed of two or more selected from tungsten, molybdenum, and lead. May be. Moreover, examples of the positive electrode current collector containing titanium nitride (TiN) include a positive electrode current collector made of titanium nitride, or a metal plate such as a nickel plate whose surface is coated (plated) with titanium nitride. . In particular, at least one metal selected from the group consisting of tungsten (W) and molybdenum (Mo) or a carbonaceous material is preferable.

  The content of the conductive material made of one or more selected from tungsten (W), molybdenum (Mo), lead (Pb), and titanium nitride (TiN) in the positive electrode current collector is preferably 99% by weight or more. A more preferable range is 99.9% by weight or more.

  A positive electrode current collector containing a carbonaceous material as a conductive material is produced, for example, by mixing a carbonaceous material powder and a binder and then pressure-molding the mixture.

  Examples of the carbonaceous material powder include graphite powder and carbon fiber.

  The carbonaceous material content in the positive electrode current collector is preferably 80% by weight or more. More preferably, it is 90 weight% or more.

This positive electrode may be mixed in advance with an electrolyte solution described later.
2) Negative electrode The negative electrode active material contained in the negative electrode is 0.001 to 30% by weight of an intermetallic compound composed of at least two elements selected from the group consisting of Al, Mg, Zn, Mn, Sn and In. It contains at least one of aluminum alloy and aluminum.

  Intermetallic compounds are a kind of alloys. Here, the intermetallic compound means a compound formed from two or more kinds of metal elements, and the component atomic ratio is not necessarily a stoichiometric ratio (Iwanami Physical and Chemical Dictionary, 5th Edition Iwanami Shoten, April 1998) Issued May 24, pages 352-353). Moreover, confirmation of being an intermetallic compound is performed by the method demonstrated below.

  Intermetallic compounds basically have a different symmetry from the mixing of simple constituent elements. That is, since the microscopic structures are different, the diffraction peak position of X-ray diffraction is different from each simple substance. That is, in the present invention, it can be said that the effect is exhibited depending not only on the component elements but also on the resulting structure.

  On the other hand, the alloy here means something other than an intermetallic compound (for example, solid solution, eutectic, etc.). Confirmation of the alloy is performed by the method described below.

  Since a mixture of component elements and a mixture that inherits the symmetry of one of the elements are made of an alloy, the diffraction peak position of X-ray diffraction is slightly different, but it matches or overlaps the peak position of the component element alone. It will be.

  The reason why the content of the intermetallic compound in the negative electrode active material is defined within the above range is as follows. When the content of the intermetallic compound is less than 0.001% by weight, the reactivity between the iodine component in the electrolytic solution and the aluminum oxide film on the negative electrode surface is decreased, and the amount of gas generated during discharge increases. On the other hand, when the content of the intermetallic compound exceeds 30% by weight, the discharge duration is shortened because the aluminum content decreases. A more preferable range of the content of the intermetallic compound is 1% by weight or more and 10% by weight or less.

  The composition of the intermetallic compound is not particularly limited. For example, ternary systems such as Al-Mg-Zn and Al-Mg-Mn, Al-Mg, Mg-Zn, Mg-In, and Al-Mn Binary systems such as Among these, Al—Mg—Zn is preferable.

  The composition of the aluminum alloy is not particularly limited, and examples thereof include an alloy of Al and at least one metal selected from Mn, Cr, Sn, Ca, Mg, Pb, Si, In, and Zn. be able to. Among them, it is desirable to use an alloy containing Mg and Cr in Al.

  The negative electrode can be used as a container formed of a negative electrode active material, or can be obtained by forming a mixture obtained by adding a binder or the like into the negative electrode active material into a suitable shape as a negative electrode, A gel material obtained by adding a molecular compound, an electrolytic solution, or the like may be used as the negative electrode.

  The gelled negative electrode can increase the surface area of the negative electrode.

  Although it does not restrict | limit especially as a high molecular compound, For example, polyvinyl alcohol, polyacrylic acid, polyacrylonitrile, polysulfonic acid vinyl, polyvinyl acetate, polyalanine etc. can be used, and when molecular weight shall be about 100-10,000,000. good. Moreover, when apply | coating to the negative electrode active material surface, there is no restriction | limiting in particular in thickness. It may be completely packed between the positive electrode and the negative electrode.

  The polymer compound may be in a solid form or a gel form swollen in an electrolytic solution. When the polymer compound is in a gel form, the electrolytic solution can move between the resins and reach the negative electrode active material. Even when the polymer compound is in a solid state, the electrolyte solution, the electrolyte, the additive, etc. penetrate the polymer compound and perform their respective functions.

  Further, as the polymer compound, it is preferable to use a compound having an acidic group such as a sulfonic acid group or a carboxylic acid group, a basic group such as a hydroxyl group or an amine group, a basic group or a derivative of an acidic group as a substituent. . These substituents increase the affinity with the electrolyte and facilitate the reaction of the negative electrode.

  It is preferable to add a chloride ion or an organic acid, an inorganic weak acid salt, an inorganic alkali salt or a derivative thereof to the polymer compound. Thereby, self-discharge can be further suppressed.

  Examples of organic acid, inorganic weak acid salt, inorganic alkali salt or derivatives thereof include calcium tartrate, sorbitol, gelatin, calcium gluconate, itaconic acid, citric acid, benzoic acid, antimony pentoxide hydrate, titanium hydroxide water Examples thereof include Japanese, zirconium phosphate, and titanium phosphate.

  The amount of organic acid or chloride ion added to the polymer compound is preferably 0.01 to 1 wt%, more preferably 0.03 to 0.3 wt%. If the amount is less than this range, the self-discharge of the negative electrode cannot be sufficiently suppressed. If the amount is more than this range, the negative electrode reaction is hindered and the output of the battery may be reduced.

  A separator can be disposed between the positive electrode and the negative electrode. The separator prevents electrons from moving between the positive electrode and the negative electrode, and is made of an insulating material. However, since the electrolyte solution is held in the separator and the electrolyte ionized in the electrolyte solution needs to be movable, a porous body is usually used.

  Examples of the material used for the separator include kraft paper, synthetic fiber sheet, natural fiber sheet, non-woven fabric, glass fiber sheet, and polyolefin porous film.

  Further, the thickness of the separator is preferably in the range of 10 to 1000 μm. This is because if the thickness is less than 10 μm, there is a risk of a short circuit between the positive electrode and the negative electrode, and if the thickness is greater than 1000 μm, the ionized electrolyte may move and the ion conduction efficiency may decrease. A more preferable thickness range of the separator is 10 to 200 μm.

  Note that the separator is not necessarily required as long as the battery structure is arranged so that the positive electrode and the negative electrode are not in contact with each other and the electrolytic solution can be held between the positive electrode and the negative electrode.

  Moreover, a thickener can be added to electrolyte solution, it can be gelatinized, and it can also be used as what is called a solid electrolyte. In that case, the thickener phase functions as a separator, and the electrolyte phase is retained in the thickener phase.

3) Electrolytic solution The electrolytic solution contains an electrolyte and a solvent in which the electrolyte is dissolved.

Examples of the electrolyte include those containing an iodine compound. Examples of the iodine compound include iodides of NH ₄ I and III elements (eg, AlI ₃ , InI ₃ ), alkali metal iodides (eg, KI, NaI, LiI), and alkaline earth metal iodides ( for _{example, MgI 2, BaI 2, CaI} 2), a transition metal iodide (e.g. ZnI _2), and the like. The kind of iodine compound to be used can be one kind or two kinds or more. Of these, NH ₄ I and MgI ₂ are preferable.

  The iodine concentration of the electrolytic solution is desirably in the range of 0.01 mol / L or more and 6 mol / L or less. This is due to the reason explained below. If the iodine concentration is less than 0.01 mol / L, the amount of gas generated during discharge increases and the discharge duration may be shortened. On the other hand, when the iodine concentration exceeds 6 mol / L, the ion concentration is too high and the ion mobility in the electrolytic solution is lowered, and the output may be lowered. A more preferable range of the iodine concentration is 0.5 mol / L or more and 4 mol / L or less.

The electrolyte may further contain a solvent that supplies at least one ion selected from the group of sulfate ions (SO ₄ ²⁻ ) and nitrate ions (NO ₃ ⁻ ). Such an electrolyte can further suppress the amount of gas generated during discharge.

  Examples of those that provide sulfate ions include sulfuric acid, aluminum sulfate, magnesium sulfate, sodium sulfate, ammonium sulfate, and lithium sulfate.

  Examples of those that provide nitrate ions include nitric acid, aluminum nitrate, magnesium nitrate, sodium nitrate, ammonium nitrate, and lithium nitrate.

  The concentration of ions consisting of at least one of nitrate ions and sulfate ions in the electrolyte is preferably in the range of 0.2 to 16 M / L. This is due to the following reason. If the ion concentration is less than 0.2 M / L, the effect of suppressing gas generation during discharge may not be obtained. On the other hand, if the ion concentration exceeds 16 M / L, oxide film growth on the surface of the negative electrode becomes remarkable, and the interface resistance of the negative electrode increases, so that a high voltage may not be obtained. A more preferable range is 0.5 to 10 M / L.

  As the solvent in which the electrolyte is dissolved, for example, water, methyl ethyl carbonate, or the like can be used.

[Example]
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

Example 1
In order to disperse the intermetallic compound homogeneously in the aluminum alloy, a mixture comprising 99% by weight of the aluminum alloy having the composition shown in Table 1 below and 1% by weight of the intermetallic compound composed of Al ₂ Mg ₃ Zn ₃ And stored at 400 ° C. for one month under an argon gas atmosphere.

A bottomed cylindrical negative electrode container was produced from this mixture. Moreover, 3 mol / L ammonium iodide aqueous solution was prepared as electrolyte solution. Further, a positive electrode mixture was prepared by mixing manganese dioxide: carbon black: Teflon (registered trademark) at a weight ratio of 10: 1: 0.5. A carbon rod was prepared as a positive electrode current collector, and kraft paper was prepared as a separator. Using these, a cylindrical aluminum negative electrode battery having the structure shown in FIG. 1 was assembled. The battery size was AA size.

  That is, as shown in FIG. 1, in a bottomed cylindrical negative electrode can 1 made of an aluminum alloy, a positive electrode mixture containing a positive electrode active material, a conductive agent, and an aqueous electrolyte solution via a separator 2 and a bottom paper 3. 4 is filled.

  An insulating washer 6 in which the gas vent hole 5 is opened is fitted into the upper end of the opening of the negative electrode can 1 to close the opening of the negative electrode can 1. The positive electrode current collector rod 7 is inserted into the opening of the insulating washer 6, and the upper end protrudes from the insulating washer 6. A space provided between the positive electrode mixture 4 and the insulating washer 6 in the negative electrode can 1 functions as an air chamber 8.

  The heat shrinkable tube 9 covers the periphery of the negative electrode can 1, fixes the insulating washer 6 to the opening of the negative electrode can 1, and fixes the negative electrode terminal plate 10 to the bottom surface of the negative electrode can 1. The cylindrical exterior body 11 covers the heat shrinkable tube 9. A cap-shaped sealing plate (positive terminal plate) 12 that also serves as a positive electrode terminal is disposed in the upper opening of the exterior body 11 so as to cover the upper end of the positive electrode current collector rod 7. A hole 13 is formed. The insulating ring 14 is interposed between the exterior body 11 and the sealing plate 12.

  When the obtained aluminum battery was discharged at 150 mA, continuous discharge for 17 hours was possible until the 0.6 V discharge cut. Further, no leakage occurred during discharge.

(Examples 2 to 17 and Comparative Example 1)
Except that the composition of aluminum alloy or aluminum, the composition and blending amount of intermetallic compounds, and the type and concentration of the electrolyte in the electrolytic solution are set as shown in Table 1 below, the same as described in Example 1 above An aluminum battery having a proper structure was prepared, and the discharge duration and the presence or absence of leakage were examined.

(Comparative Example 2)
Except for using only an aluminum alloy having the composition shown in Table 1 below as the negative electrode active material and setting the type and concentration of the electrolyte in the electrolytic solution as shown in Table 1 below, it was explained in Example 1 described above. An aluminum battery having the same configuration was manufactured, and the discharge duration and the presence or absence of leakage were examined.

(Comparative Example 3)
A zinc battery having the same configuration as described in Example 1 was prepared except that a negative electrode container made of Zn metal was used and the type and concentration of the electrolyte in the electrolytic solution were set as shown in Table 1 below. Then, the discharge duration and the presence or absence of liquid leakage were examined.

  As is apparent from Table 1, it can be understood that the aluminum batteries of Examples 1 to 17 have a long discharge duration and no leakage during continuous discharge.

  On the other hand, in the aluminum battery of Comparative Example 1 that uses a chlorine compound as an electrolyte and the aluminum battery of Comparative Example 2 that does not contain an intermetallic compound, the discharge duration is shorter than in Examples 1 to 15 and Leakage occurred due to the generation of hydrogen gas inside.

  On the other hand, in the zinc battery of Comparative Example 3 using Zn as the negative electrode active material, although the amount of hydrogen gas generated during discharge was small, no leakage occurred, but the continuous discharge time was shorter than in Examples 1-15. . Since the zinc negative electrode has low reactivity with water in the electrolyte, the zinc oxide layer on the negative electrode surface can suppress side reactions with water, but the discharge duration is shorter than that of aluminum batteries. Become.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

1 is a partial cross-sectional view showing a cylindrical aluminum negative electrode battery which is an embodiment of an aluminum battery according to the present invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Negative electrode can, 2 ... Separator, 3 ... Bottom paper, 4 ... Positive electrode mixture, 6 ... Insulating washer, 7 ... Positive electrode current collecting rod, 8 ... Air chamber, 9 ... Heat-shrinkable tube, 10 ... Negative electrode terminal plate, 11 ... exterior body, 12 ... positive electrode terminal plate, 14 ... insulating ring.

Claims (2)

A positive electrode;
An intermetallic compound comprising at least one of aluminum and an aluminum alloy and at least two elements selected from the group consisting of Al, Mg, Zn, Mn, Sn, and In, which are homogeneously dispersed in the aluminum and the aluminum alloy A negative electrode containing a negative electrode active material containing 0.001 wt% or more and 30 wt% or less,
An aluminum battery comprising: an electrolytic solution containing an iodine component. 2. The aluminum battery according to claim 1, wherein the intermetallic compound is Al—Mg—Zn or Al—Mn .

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