JP2005190879A - Aluminum primary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a negative electrode material for an aluminum primary battery capable of suppressing generation of hydrogen gas during discharge.
An aluminum primary battery using, as a negative electrode, pure aluminum or an aluminum alloy having a reaction surface oriented in a [100] plane.
In the above aluminum primary battery, the area ratio of crystal grains having a [100] plane whose inclination angle from the reaction surface is 15 ° or less is 70% or more.
[Selection] Figure 1

Description

  The present invention relates to an aluminum primary battery including a negative electrode material for an aluminum primary battery and a negative electrode including the negative electrode material for an aluminum primary battery.

  Currently, manganese batteries and alkaline batteries are widely used as primary batteries for portable devices. With the development of portable devices, high voltage, high capacity and light weight are desired in this primary battery.

 A primary battery using aluminum for the negative electrode has been studied for a long time since it can be expected to have a higher capacity than a primary battery made of zinc. In particular, Japanese Patent Laid-Open No. 54-25208 (Patent Document 1) discloses that various alloy compositions have been tried in order to reduce the potential during no energization and energization, or to suppress self-corrosion. Has been described.

However, this Patent Document 1 does not present any problem regarding the generation of hydrogen gas during discharge. In the conventional structure of this Patent Document 1, the Al rolled surface usually has many {110} surfaces. In Patent Document 1, the crystal plane is not taken into consideration. This can be reasonably estimated to be mainly composed of the {110} plane even if a part of the {100} plane is included. In such an electrode structure, unless the generation of hydrogen during discharge is suppressed, there is a risk that the internal pressure of the battery will increase and rupture unless gas is allowed to escape well, and current efficiency will also deteriorate. The inventors have found that the generation of hydrogen gas during discharge is neither a proportional relationship nor a linear relationship with the generation of hydrogen gas during storage or storage (self-discharge).
JP-A-54-25208

A conventional primary battery using aluminum for the negative electrode has a problem that hydrogen gas is generated during discharge, and the internal pressure of the battery is increased and explosion may occur unless the gas is allowed to escape.
The present invention has been made in view of the above problems, and it is an object of the present invention to provide an aluminum primary battery that can suppress the generation of hydrogen gas during discharge and has a low risk of explosion due to an increase in internal pressure of the battery. To do.

  In order to solve the above problems, an aluminum primary battery according to claim 1 of the present invention includes a positive electrode, a negative electrode in which a reaction surface disposed to face the positive electrode is a metal containing at least aluminum, the negative electrode, and the negative electrode In an aluminum primary battery having an electrolyte solution interposed between positive electrodes, the metal containing aluminum on the reaction surface of the negative electrode is oriented in the [100] plane.

  The aluminum primary battery according to claim 2 is the aluminum primary battery according to claim 1, wherein the area ratio of crystal grains having a [100] plane within an inclination angle of 15 ° or less from the reaction surface is 70% or more. And Here, the area ratio is the area (percentage) occupied by a [100] plane on the surface and a plane with an inclination angle of 15 ° or less in a certain observation plane. Since a certain observation surface must be able to represent the whole, it is required to take a sufficient number of photographs as necessary and take an average, or to make an observation surface with a sufficient area.

  An aluminum primary battery according to claim 3 is characterized in that, in claim 1, the electrolytic solution is an aqueous solution.

  An aluminum primary battery according to claim 4 is characterized in that, in claim 3, the electrolytic solution is an aqueous solution containing at least aluminum chloride, potassium chloride, and bipyridyl.

  The aluminum primary battery according to claim 5 is the aluminum primary battery according to claim 1, wherein the metal containing aluminum is an aluminum alloy having a composition represented by the following formula (1). Primary battery.

ZnaMgBncMdAl100-abcd (1)
Where M is at least one element selected from the group consisting of Ga, Ti, Zr, Cr, Mg, Bi and rare earth elements, and a, b, c and d are each 0.01 wt. % ≦ a ≦ 20 wt%, 0.01 wt% ≦ b ≦ 10 wt%, 0 ≦ c ≦ 0.01 wt%, and 0 ≦ d ≦ 3 wt%.

  As described above in detail, according to the present invention, it is possible to provide an aluminum primary battery that suppresses the generation of hydrogen gas during discharge and has a low risk of rupture.

  The aluminum primary battery according to the present invention will be described.

  The aluminum primary battery includes a negative electrode including the negative electrode material described in detail above, a positive electrode, a separator disposed between the positive electrode and the negative electrode, and an electrolytic solution.

(Negative electrode)
A negative electrode in which the reaction surface of pure aluminum or aluminum alloy used as the negative electrode material is oriented in the [100] plane is adopted. The reaction surface here is the surface of the electrode facing the positive electrode. Further, the [100] plane includes (010) and (001) planes that are equivalent in a cubic crystal, and also includes (n00) planes such as (200) and (400), and is used as a generic term.

  The reason why the reaction surface is defined in the range oriented in the [100] plane will be described. The present inventors have found from various experiments that when the reaction surface of pure aluminum or an aluminum alloy is oriented in the [100] plane, the effect of suppressing the generation of hydrogen gas during discharge is high.

  That is, the present inventors have conducted intensive research to achieve the characteristics required for practical use of aluminum primary batteries. First, when we look at the X-ray diffraction pattern after a simple corrosion test on a non-oriented ordinary Al plate, we noticed that many (200) planes remain, so it is expected that such surfaces will be resistant to corrosion. (Here, simple corrosion refers to a corrosion test in which a test piece is immersed in an electrolyte without passing an electric current). Therefore, when a comparative test of simple corrosion was performed on a normal non-oriented surface and a [100] oriented surface, the [100] oriented surface was less likely to be corroded. On the other hand, when hydrogen gas generation during discharge was measured for these samples in an attempt, gas generation from the [100] orientation plane was much less. Because it is difficult to corrode, it can be considered that electrons were not used for hydrogen generation and flowed more to the external circuit.

The degree of orientation is ideal as it approaches 100%, but the tilt angle from the reaction surface has at least a [100] plane within 0 ° to 15 °, and the crystal grain area ratio is 70% or more, If it is desirably 90% or more, a sufficient effect can be expected in practical use.

  By containing an additive element in the alloy, the amount of hydrogen gas generated during discharge can be further reduced. As a candidate for the additive element, in addition to Zn, Mg, Bi, Mn, In, Sn, Ga, Ti, Zr, rare earth metals such as La, Nd, Dy, Er, and Ho can be used. However, the weight ratio of each element is a maximum of 10% by weight, and Al is at least 50% by weight. If the additive element is included beyond this range, the effect of suppressing the generation of hydrogen gas during discharge is saturated, but it may be difficult to align, which is not preferable.

  In the above-mentioned alloy, it is preferable that the total amount is not more than 0.01% by weight except for the above-mentioned elements added intentionally. In particular, Sn tends to increase the gas during discharge, so it should not exceed 0.01% by weight.

  It is considered that the higher the purity, the better the prevention of unintended elements may be prevented. However, if the purity of Al is 99.99% or more and the additive element material is 99.9% or more, which is inevitably mixed in? Impurity elements are generally within 50 ppm, and it is considered that sufficient quality can be obtained.

Since the negative electrode material according to the present invention described in detail above is an alloy whose reaction surface is oriented in the [100] plane, it is possible to realize an aluminum primary battery in which hydrogen gas generation during discharge is suppressed.
(Electrolyte)
As the electrolytic solution, an aqueous electrolytic solution containing at least one kind of ion selected from the group consisting of sulfate ion (SO ₄ ²⁻ ) and nitrate ion (NO ₃ ⁻ ) and a halogen ion is preferably used.

  Moreover, it is preferable that this electrolyte solution further contains at least one of a nitrogen-containing organic substance and an organic acid. Nitrogen-containing organic substances include pyrazine, bipyridyl (2,2'-bipyridyl), phenanthroline or 1,10-phenanthroline, cinchonine, piperazine, tripyridyltriazine (tri-pyridyl- triazine, or 2,4,6-tri-2-pyridyl-1,3,5-triazine). On the other hand, examples of the organic acid include maleic acid, tartaric acid, malonic acid, malic acid and the like.

  The optimum electrolytic solution composition may vary depending on the alloy composition, but it is preferable to use an aqueous electrolyte solution selected from the additives listed above.

(Positive electrode)
The positive electrode includes a positive electrode mixture containing an active material and a positive electrode current collector in electrical contact with the positive electrode mixture. Examples of the positive electrode active material include metal oxides, metal sulfides, and conductive polymers. Examples of the metal oxide include manganese dioxide, lead dioxide, nickel hydroxide, silver oxide, and the like. Examples of metal sulfides include iron sulfide and nickel sulfide. Examples of the conductive polymer include polyaniline and polypyrrole. Among these, electrolytic manganese dioxide is desirable. The powder shape is the form that is mainly used, and the particle size is preferably about 100 μm or less. The positive electrode mixture preferably further contains a conductive agent. Examples of the conductive agent include graphite, acetylene black, carbon black, and the like. The content of the conductive agent in the positive electrode mixture is preferably in the range of 2 to 20% by weight. The positive electrode mixture is produced, for example, by mixing an active material, a conductive agent, an electrolytic solution, and a binder, and then pressure-molding the mixture into a pellet.

An example of the structure of the aluminum primary battery according to the present invention will be described with reference to FIG. FIG.
It is a fragmentary sectional view which shows the aluminum primary battery of the coin type dry battery structure which is an example of the aluminum primary battery of this invention.

  1 is a battery case, 2 is a sealing plate, 3 is a negative electrode, 4 is a separator, 5 is a positive electrode, and 6 is a gasket.

  As shown in FIG. 1, a disk-shaped aluminum alignment plate having a diameter of 15 mm was used as the aluminum negative electrode. The positive electrode was formed by compression molding a positive electrode mixture containing a positive electrode active material, a conductive agent, and an electrolytic solution.

Hereinafter, the present invention will be described in detail by way of specific examples.
(Example 1)
The battery structure of FIG. 1 described above was prototyped under the following conditions, and performance was evaluated.
<Preparation of electrolyte>
Dissolve so that the concentrations of aluminum chloride, potassium chloride, and bipyridyl are 1.5 mol / L, 0.75 mol / L, and 0.1 mol / L (mol / L is abbreviated as “M” below), and use an aqueous electrolyte. Was prepared.
<Preparation of positive electrode mixture>
Electrolytic manganese dioxide was used as the positive electrode active material, and 5% by weight of acetylene black as a conductive agent was added and mixed therewith, and then the above electrolytic solution was further added to prepare a positive electrode mixture. This was compression molded into a positive electrode pellet.
<Production of negative electrode>
A 0.1 mm thick plate with {100} plane orientation made of 4nine purity Al was prepared. This was cut into a suitable size to fit the battery case 1 to form a negative electrode plate.
<Battery assembly>
A positive electrode pellet was disposed in the battery case 1, a separator was disposed thereon, and a negative electrode plate was disposed thereon. Further, a sealing plate was placed and fixed with a gasket.
For the purpose of examining gas generation later, the sealing was not performed completely, and the sealing plate and the battery case were fixed so as not to be separated. Thereafter, lead wires were attached to the sealing plate and the battery case.
<Discharge test>
The battery was discharged at a constant current so as to be 26 mA / cm ² at room temperature (20 ° C.). The gas generated at this time was collected and the volume was measured to determine the gas generation rate. Table 1 shows the results.

(Comparative Example 1)
A battery was fabricated in the same manner as in Example 1 except that the negative electrode in Example 1 was replaced with a normal plate (non-oriented) not oriented with the same composition (99.99% purity Al), and a discharge test was performed. Table 1 shows the results of the same evaluation test as in Example 1.

(Example 2 to Example 15)
In the following description of the embodiment, the description of the same content as that of the first embodiment is omitted, and the description is focused on different portions. In Examples 2 to 15, batteries were prepared in the same manner as in Example 1 except that the negative electrode material of Example 1 was changed to various aluminum alloys. Table 1 shows the negative electrode materials used in each Example and the results of evaluation tests. Only the intentionally added elements are shown as the alloy composition. Since Sn is an important impurity, the analysis results are shown on the right side. The Sn content was less than 0.01% by weight and most was 0.005% by weight or less.

  As can be seen from Table 1, the (100) oriented negative electrode material of Example 1 has a smaller amount of hydrogen gas generated during discharge (speed) than the case where it is not oriented (Comparative Example 1). Understand. Further, it was found that even if various aluminum alloys are used, the same effect can be obtained if the (100) orientation is applied in the same manner as in Example 1.

  Moreover, the result of having observed the negative electrode alloy of Example 1 by EBSP is shown in FIG. In FIG. 2, only crystal grains having a {100} plane and an inclination of 15 ° or less are colored (otherwise, white). The area ratio of these crystal grains was 95%. Regarding the other examples, the area ratio of the entire crystal grains was 95% as in Example 1.

  In the case of non-orientation in Comparative Example 1, the same area ratio was measured and found to be 20%.

(Example 16)
<Preparation of electrolyte>
An electrolyte solution was prepared in the same manner as in Example 1.

<Preparation of positive electrode mixture>
Electrolytic manganese dioxide was used as the positive electrode active material, and 10% by weight of acetylene black as a conductive agent was added and mixed therewith, and then the electrolyte solution was further added to prepare a positive electrode mixture.

<Production of negative electrode>
A 6 mm thick plate with {100} plane orientation made of 4nine purity Al was prepared. This was plastically deformed to obtain a bottomed cylindrical aluminum alloy container.
As in Example 1, when EBSP was observed, crystal grains having a {100} plane and an inclination within 15 ° were 90% in terms of area ratio.

<Battery assembly>
A separator was accommodated so as to cover the inner wall of the negative electrode container produced above, and a positive electrode mixture was filled therein, and a graphite positive electrode current collector was further inserted therein. For the purpose of examining gas generation later, no sealing or the like was performed.

  A discharge test was conducted in the same manner as in Example 1. Table 2 shows the amount of hydrogen gas generated during discharge.

(Example 17)
Regarding the aluminum of Example 16, the crystal grains having a {100} plane and an inclination of 15 ° or less were 90% in terms of area ratio, but it was Example 16 that made this 75%. This is the same as Example 16. The performance evaluation of Example 17 was performed in the same manner as in Example 16 and is shown in Table 2.

(Example 18)
Regarding the aluminum of Example 16, the crystal grains having a {100} plane and an inclination of 15 ° or less were 90% in terms of area ratio, but this was changed to 70% in Example 18, and the others. This is the same as Example 16. The performance of Example 18 was evaluated in the same manner as in Example 16 and is shown in Table 2.

(Example 19)
Regarding the aluminum of Example 15, the crystal grains having a {100} plane and an inclination of 15 ° or less were 90% in terms of area ratio, but this was changed to 60% in Example 19, and the others. This is the same as Example 16. The performance of Example 19 was evaluated in the same manner as in Example 16 and is shown in Table 2.

  The negative electrode materials of Examples 16 to 19 all show better characteristics than Comparative Example 1. In particular, it has been found that the current efficiency can be dramatically improved by setting the area ratio to 90%.

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. Moreover, when Examples 16-19 are examined, it turns out that a crystal grain with a {100} plane and the inclination within 15 degrees has a favorable characteristic, so that it approaches 100% in area ratio. However, it can be seen that there is a slightly large difference between the area ratio of 60% and 70%, and an area ratio of 70% or more is particularly preferable. Accordingly, it is desirable that crystal grains having a {100} plane and an inclination of 15 ° or less are 70% or more in terms of area ratio.

(Reference examples 1-2)
The aluminum alloys having the compositions of Examples 6 and 15 were heat-treated at about 550 ° C. to produce non-oriented ones. At this time, the crystal grains having a {100} plane and an inclination within 15 ° were both about 20% in terms of area ratio. The other points are the same as in the first embodiment. For Reference Examples 1 and 2, performance evaluation was performed in the same manner as in Example 1, and the results are shown in Table 3.

  About these compositions, the characteristic substantially equivalent to what was orientated was acquired. Impurity elements other than those specified here were within 100 ppm (0.01 wt%) in total including Sn. Although not shown in the table, this peripheral composition was evaluated for performance. As a result, it was confirmed that Sn was small and that Zn, Mg, and In were within a predetermined range. all right. If Zn exceeds 5% by weight, Mg exceeds 3% by weight, and In exceeds 1% by weight, gas generation during discharge is increased. Further, if any one of Zn, Mg, and In is missing, gas generation during discharge is not reduced as compared with the reference example. Even if a small amount of other elements such as Sn and Bi are added, the generation of gas during discharge increases. Here, since an additive element of less than 0.01% by weight is regarded as an impurity, the addition of a trace amount means 0.01% by weight or more. In the composition of the reference example, it was found that the influence of the orientation plane was specifically small and the gas during discharge was small. In other words, it can be said that the essence of the proposal is that the optimum composition can be expanded by {100} plane orientation.

The fragmentary sectional view which shows the aluminum primary battery of the coin dry battery structure which is an example of the aluminum primary battery which concerns on this invention. 3 is an EBSP image of the reaction surface of the negative electrode material of Example 1. FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Battery case, 2 ... Sealing plate, 3 ... Negative electrode, 4 ... Separator, 5 ... Positive electrode, 6 ... Gasket.

Claims (5)

In an aluminum primary battery having a positive electrode, a negative electrode in which a reaction surface disposed opposite to the positive electrode is a metal containing at least aluminum, and an electrolyte solution interposed between the negative electrode and the positive electrode, An aluminum primary battery characterized in that a metal containing aluminum is oriented in the [100] plane. 2. The aluminum primary battery according to claim 1, wherein an area ratio of crystal grains having a [100] plane within an inclination angle of 15 ° or less from the reaction surface is 70% or more. The aluminum primary battery according to claim 1, wherein the electrolytic solution is an aqueous solution. 4. The aluminum primary battery according to claim 3, wherein the electrolytic solution is an aqueous solution containing at least aluminum chloride, potassium chloride, and bipyridyl. The aluminum primary battery according to claim 1, wherein the metal containing aluminum is an aluminum alloy having a composition represented by the following formula (1).
ZnaMgBncMdAl100-abcd (1)
Here, M is at least one element selected from the group consisting of Ga, Ti, Zr, Cr, Bi, In, Mn, and rare earth elements, and a, b, c, and d are each 0. 01 wt% ≦ a ≦ 20 wt%, 0.01 wt% ≦ b ≦ 10 wt%, 0 ≦ c <0.01 wt%, and 0 ≦ d ≦ 3 wt% are shown.

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