JPH06179936A - Negative electrode material for aluminum battery - Google Patents

Abstract

PURPOSE:To obtain negative electrode material for Al battery less in self- corrosion in strong alkali solution by specifying the content of Mg, Sn and Mn in an Al alloy. CONSTITUTION:The composition of the negative electrode material for Al-air battery is composed by wt.%. of 0.1-2.0% Mg, 0.03-1.0% Sn, 0.01-0.5% Mn and balance Al and inevitable impurities. The negative electrode material has excellent negative electrode performance and corrosion resistance due to the interaction between each of the alloy elements and particularly less in self-corrosion in the strong alkali electrolyte solution. Mg in the alloy improves the corrosion resistance in the strong alkali solution. Sn increases the negative electrode performance by making the potential of the alloy negative. The addition of Mn has the effect of decreasing the fluctuation of current in the case of dipping into the strong alkali solution and taking out <100 nA/cm<2> current and imparting excellent negative electrode performance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a negative electrode material for an aluminum battery, and more particularly to a negative electrode material for an aluminum-air battery having a small self-corrosion property and an excellent negative electrode performance.

[0002]

2. Description of the Related Art Aluminum-air batteries (hereinafter, aluminum batteries) are well known, and their anode reaction and cathode reaction are Al + 2H ₂ O = AlO ₂ + 4H + 3e,
And O ₂ + 2H ₂ O + 4e = 4OH. As is clear from the reaction formula, the higher the pH, the higher the oxygen pressure, and the lower the aluminate ion, the greater the potential difference.
A strong alkaline solution such as NaOH or KOH is used. As the aluminum alloy used as the negative electrode, an alloy containing an additive element that lowers the pitting potential and has a large hydrogen overvoltage is applied.

Various aluminum alloys have been conventionally developed for the negative electrode (anode) of aluminum batteries.
Anciently, the Al-Zn alloy was proposed by Glicksman in 1959, and was subsequently based on the Al-Zn alloy with Sn, In,
Many alloys with improved performance by adding Ga etc. have been developed. (JP-B-48-41411, JP-A-53-1616, JP-A-54-25208, JP-A-54-26211) Al-Ga alloys other than Al-Zn type aluminum alloys for aluminum batteries
(JFCooper et al .: 1980 Intersociety EnergyConvers
ion Conference, Seatle, WA.August 18-22,1980), Al-Sn
Alloy (Alluminio Mag.N1 / 2, 1991 "La batteria Allumini
o-aria puo sostituire i gruppi genera-tori diesel
? ") And Al-Mg-In-Mn alloys (Journal of Applied El
ectrochemi-story 20 (1990) 405-417) is introduced.

However, the above-mentioned conventional aluminum alloys for negative electrodes of aluminum batteries are all electrochemically base and have excellent negative electrode performance, and electrolytes for primary batteries such as aluminum chloride, sodium chloride, ammonium chloride and ammonium chromate. The self-corrosion inside is not so big,
In a strong alkaline solution such as NaOH or KOH solution, the corrosion resistance is poor, and the self-corrosion of the aluminum alloy negative electrode becomes large,
There is a drawback that the negative electrode material is wasted.

[0005]

The present invention has been made in order to solve the problems of the conventional negative electrode materials for aluminum batteries, and its object is to have excellent negative electrode performance and excellent corrosion resistance. In particular, it is to provide a negative electrode material for an aluminum battery that has less self-corrosion in a strong alkaline solution such as NaoH or KOH solution.

[0006]

Means for Solving the Problems The negative electrode material for an aluminum battery according to the present invention for achieving the above object is Mg0.
A characteristic feature of the invention is that it contains 1 to 2.0% (wt%, the same applies hereinafter), Sn0.03 to 1.0% and Mn0.01 to 0.5%, and the balance is Al and unavoidable impurities.

Mg, which is contained as an essential component, is an element that improves the corrosion resistance of the alloy in a strong alkaline solution, but if the content is less than 0.1%, its effect is small, and if it exceeds 2.0%, the potential becomes noble and the negative electrode becomes negative. Reduce performance. Therefore, 0.
The preferable content range is 1 to 2.0%.

Sn has the effect of making the potential of the alloy base and enhancing the performance of the negative electrode, but if it is less than 0.03%, the effect is small.
If it exceeds 0%, self-corrosion of the alloy tends to proceed. Therefore, the preferable content range is 0.03 to 1.0%.

The addition of Mn has the effect of immersing the alloy in a strong alkaline solution such as a NaOH solution and imparting excellent negative electrode characteristics with little current fluctuation when a current of 100 mA / cm ² or less is taken out. . If the addition of Mn is less than 0.01%, its effect is small, and if it exceeds 0.5%, self-corrosion becomes large. Therefore, 0.01 to 0.5% is set as a preferable content range.

The aluminum alloy for negative electrode material of the present invention is
In order to impart better negative electrode performance and corrosion resistance, it is preferable that the alloying elements and impurities be solid-solved in the alloy matrix. After melting, an ingot is formed by a normal continuous casting method, and after homogenization treatment, it is preferably water-cooled in order to form a solid solution with alloy elements and impurities such as Fe and Si. Then, hot rolling is performed according to a conventional method, and cold rolling is performed while performing intermediate annealing as necessary to obtain a predetermined thickness. In order to remove the processing strain of the cold rolled material, final annealing may be performed at a temperature of 100 to 500 ° C, for example. Also in this case, it is preferable to perform rapid cooling after the final annealing in order to promote solid solution of alloying elements and impurities. In actual production, a continuous annealing furnace that continuously heats and cools a coiled plate material can be applied.

[0011]

The negative electrode material for an aluminum battery of the present invention has the above-mentioned constitution and function, and is provided with excellent negative electrode performance and corrosion resistance due to the interaction of each alloying element, and especially the self-corrosion of the material in a strong alkaline electrolyte solution. Since it is small, it can exhibit excellent performance as a negative electrode of an aluminum-air battery.

[0012]

EXAMPLES Examples of the present invention will be described below in comparison with comparative examples. Example 1 An aluminum alloy having the composition shown in Table 1 was subjected to homogenizing heat treatment at 580 ° C. for 5 hours, water-cooled, hot-rolled and cold-rolled to obtain a cold-rolled material having a thickness of 0.5 mm. This rolled material is 450
After the final annealing at a temperature of ℃, forced air cooling was used as a test material.

[0013]

[Table 1]

Immersing the test material in a 4 molar aqueous solution of NaOH,
For each test material, the self potential and 10
The potential when a current of 0 mA / cm ² was taken out was measured with a saturated calomel electrode as a reference, and the self-corrosion rate of each test material in this aqueous solution was also measured. The results are shown in Table 2. As shown in Table 2, each of the aluminum alloy negative electrode materials of the present invention has a low potential and a low self-corrosion rate, and has excellent negative electrode characteristics.

[0015]

[Table 2]

Comparative Example 1 An aluminum alloy having the composition shown in Table 3 was subjected to homogenizing heat treatment, hot rolling, cold rolling and final annealing under the same conditions as in Example 1 to prepare a plate material having a thickness of 0.5 mm. It was used as a test material. The component values different from the conditions of the present invention are underlined.

[0017]

[Table 3]

For each of the test materials shown in Table 3, the spontaneous potential, the potential when a current of 100 mA / cm ² was taken out, and the self-corrosion rate were measured in the same aqueous solution as in Example 1. The measurement results are shown in Table 4. According to Table 4, Comparative Alloy No. 1 having a low Mg content and No. 3 having a large amount of Sn have a high self-corrosion rate, and No. 2 having no Mn has a current of 100 mA / cm ² . The fluctuation of the electric potential is large. In No. 4 in which the amounts of Mg and Sn deviate from the conditions of the present invention, the natural electrode potential becomes noble and the negative electrode performance is poor. Comparative alloy No. 5 to which In was added without adding Sn and whose characteristics are similar to Sn has a low potential when a current of 100 mA / cm ² is taken out, and also has insufficient corrosion resistance.

[0019]

[Table 4]

[0020]

INDUSTRIAL APPLICABILITY As described above, according to the present invention, there is provided a negative electrode material having excellent negative electrode performance and excellent corrosion resistance, and particularly less self-corrosion in a strong alkaline solution. Very useful as a negative electrode.

Claims (1)

[Claims] 1. A negative electrode material for an aluminum battery, which contains Mg 0.1 to 2.0%, Sn 0.03 to 1.0% and Mn 0.01 to 0.5%, and the balance Al and inevitable impurities.