JP3188651B2 - Negative electrode zinc base alloy powder for alkaline batteries - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a negative electrode zinc-based alloy powder for an alkaline battery containing a trace amount of metal, which is effective for suppressing generation of hydrogen gas before and after discharge and improving load discharge characteristics.

[0002]

2. Description of the Related Art Zinc powder for alkaline batteries is usually produced by an atomizing method, and often has a relatively round potato-like particle shape. Since zinc in the form of powder having a large surface area is used for the negative electrode, the reactivity in the electrolytic solution is excellent, so that this type of alkaline battery is suitable for large-current discharge.
On the other hand, since the surface area is large, the negative electrode zinc is easily corroded in the electrolytic solution. Therefore, in the old days, corrosion resistance was maintained by using a large amount of mercury. However, due to concerns about environmental pollution caused by mercury in waste dry batteries, efforts have been made to make mercury-free alkaline batteries mercury-free.

That is, the amalgamation of zinc powder with mercury is abolished, and instead, a zinc-based alloy powder to which a small amount of an appropriate alloying element is added is used as a negative electrode active material to improve its corrosion resistance and battery characteristics. They are trying to improve. Intensive research has been conducted from such a viewpoint, and some alloying elements effective for corrosion prevention have been found. For example, bismuth, aluminum, indium, gallium,
Lithium, sodium and the like. As a result, the addition of these metals prevents corrosion of the zinc anode,
Practical mercury-free alkaline batteries that prevent the generation of hydrogen have been realized.

[0004] In addition, a lot of meaningful data is accumulated about which of these alloying elements and how much should be added to be effective, and which elements should be combined with which elements to obtain a large synergistic effect. It has been. For example, electrochemical 59, No. 4 (1991), pp. 325 to 329, hydrogen gas generation due to self-discharge occurs from the crystal grain boundaries of the zinc-based alloy powder, and hydrogen gas generation is controlled to a certain extent by adding bismuth having a high hydrogen overvoltage alone. It has been reported that it is necessary to take a method that can suppress but does not change to bismuth oxide.

Here, the reason why the above-mentioned hydrogen gas is generated from the crystal grain boundary is that the crystal grain boundary has poorer coordination between atoms than in the crystal grain and the strain is accumulated. This is because the hydrogen gas generation reaction proceeds.

In order to verify the effectiveness and problems of adding bismuth alone, the present inventors conducted a test on hydrogen gas generation of a battery and examined the amount of gas generated during storage of the battery before discharging. And the gas generation amount after the discharge were measured.

At this time, in measuring the amount of gas generated before the discharge, the zinc-based alloy powder to which bismuth is added is put into a gas pipette together with a 40% by weight KOH solution saturated with zinc oxide, and heated at a temperature of about 60.degree. The amount of hydrogen gas generated when stored for days was measured. Then, the gas generation index K was calculated from the gas generation amount using the following equation, and the corresponding change in the gas generation index K was determined by changing the amount of bismuth added at this time. K = amount of gas generated [cc] / (amount of zinc-based alloy powder [g] × number of storage days [day]) In measuring a gas generated after discharge, the zinc-based alloy powder to which bismuth was added alone was used. Used for a battery having the configuration shown in the longitudinal sectional view of FIG.
Overdischarge by connecting to 2Ω resistor, discharge end voltage is 0V
The amount of gas generated after reaching was measured. Then, by changing the amount of bismuth added at this time, a corresponding change in the amount of generated gas was determined. In addition, measurement of gas generation amount,
The discharged battery is put in a gas pipette together with liquid paraffin, and stored in this state at a temperature of about 60 ° C. for 3 days.
The amount of hydrogen gas discharged from the battery during storage was determined.

The specific configuration of the battery shown in FIG. 1 used at this time is an alkaline battery of the LR-20 type based on the JIS standard, in which a power generating element is housed inside a bottomed cylindrical battery case 1. The inside of the battery is sealed by caulking a negative electrode terminal plate 3 to the opening thereof via a sealing gasket 2, and a current collecting rod 4 electrically connected to the negative electrode terminal plate 3 includes a sealing gasket as a power generation element. 2, a negative electrode 5, a separator 6, and a positive electrode mixture 7 mainly composed of manganese dioxide so as to surround the outer periphery of the current collecting rod 4.
Are concentrically filled. This negative electrode was made up of 34% by weight of a 40% by weight KOH solution saturated with zinc oxide, 65% by weight of a zinc-based alloy powder with respect to the KOH solution, and polyacrylic acid and polyacrylic acid as gelling agents. A mixture of soda and 0.5% by weight was used to form a gel.

[0009]

[Table 1]

As a result of the above hydrogen gas generation test,
As shown in Table 1, it was confirmed that the gas generation amount before discharge was suppressed to some extent by adding bismuth alone.

[0011]

However, in the zinc-based alloy powder to which only bismuth is added alone as described above, as shown in Table 1, the amount of gas generated after discharge depends on the amount of bismuth added. It grows as you increase.
That is, if gas generation increases after discharge, there is a possibility of causing problems such as deterioration of load discharge performance and liquid leakage, so that it is not possible to add too much bismuth, and thus the effect of suppressing gas generation before discharge is also reduced. It cannot be said that it is sufficient yet, and it is desired to make improvements so that generation of hydrogen gas before and after discharge can be suppressed.

Further, the present mercury-free alkaline battery has some inadequate characteristics in comparison with the conventional alkaline battery using mercury. One is that the discharge utilization rate during large current discharge is poor and the discharge duration is short. In particular, in recent years, as devices have become smaller and more portable, there is an increasing demand for batteries to be made smaller and have higher capacities.

In order to increase the capacity while keeping the battery size the same, not only the type of material inside the battery as described above, but also the internal volume has been studied. In other words, in terms of the internal volume, a method of increasing the internal capacity of the negative electrode of the battery as much as possible and filling the negative electrode active material by the increased content integral to increase the capacity is adopted. However, there is a limit to this increase in the internal volume.

The present invention has been made in view of the above-described conventional problems, and has as its object to improve the amount of hydrogen gas generated before and after discharge and the large-current discharge characteristics, and to further improve mercury, cadmium and An object of the present invention is to provide a zinc-based alloy powder suitable for use as a negative electrode active material of an alkaline battery containing no harmful substance such as lead.

[0015]

In order to achieve the above object, the zinc-based alloy powder for an alkaline battery according to the present invention contains bismuth, zirconium and tin in an amount of 0.001 to 0.5 wt. % And contains no significant harmful substances such as mercury, cadmium and lead, and has a specific gravity of 1.0 to 1.5 g.
/ Cm ³ , wherein an inhibitor is added to a powder obtained by mixing two or more kinds having different particle sizes.

The above-mentioned inhibitors include indium oxide (commonly referred to as indium oxide, hereinafter referred to as indium oxide), indium hydroxide, stannic oxide (commonly referred to as tin oxide, hereinafter referred to as tin oxide), and hydroxide. Use any of calcium, and in the case of indium oxide,
In the range of 0.04 to 0.5% by weight in the case of indium hydroxide and 0.01 to 0.14% by weight in the case of tin oxide. In the case of calcium hydroxide, it is desirable to add this in the range of 0.004 to 0.05% by weight.

In the present invention having the above structure, the effect of containing bismuth (hereinafter referred to as Bi), zirconium (hereinafter referred to as Zr), and tin (hereinafter referred to as Sn), respectively, is clearly understood at present. Although it has not been clarified, the inventors presume as follows.

As described above, the generation location of hydrogen gas is as follows.
This is the crystal grain boundary of the zinc-based alloy powder, in which distortion and the like are accumulated and the consistency between atoms is poor. Therefore, when Bi is contained in pure zinc in a predetermined range, Bi has a high hydrogen overvoltage, and this precipitates at the crystal grain boundaries of zinc, thereby suppressing gas generation before discharge. However, load discharge produces bismuth oxide. Since bismuth oxide has a low hydrogen overvoltage, hydrogen gas is generated with load discharge. In addition, at the time of load discharge, zinc oxide is generated in addition to the above-described bismuth oxide, and this zinc oxide inhibits the load discharge reaction, so that the load discharge time is reduced.

Therefore, when Zr is added to pure zinc in addition to Bi, a Bi-Zr-based intermetallic compound is produced, and this Bi-Zr-based intermetallic compound suppresses the production of bismuth oxide accompanying load discharge. Therefore, gas generation after load discharge is suppressed. In addition, since Zr also has a function of suppressing the generation of zinc oxide during load discharge,
The load discharge time increases.

In addition to the above Bi and Zr, Sn
When Sn is contained in pure zinc, Sn has a high hydrogen overpotential like Bi, so that Sn precipitates at the crystal grain boundary of zinc and functions to suppress gas generation before discharge. In addition, when Sn is contained in the zinc-based alloy, it has a function of refining zinc crystal grains, so that the consistency between atoms at crystal grain boundaries is improved, and strain is reduced. In addition, Sn also has a function of finely dispersing the Bi-Zr-based intermetallic compound when contained in the zinc-based alloy, and this finely dispersed B
The i-Zr-based intermetallic compound precipitates at the crystal grain boundary of zinc and functions to suppress gas generation before discharge.

Further, when the appearance specific gravity of the zinc-based alloy powder is reduced, that is, the specific surface area is increased to improve the discharge utilization rate, a hydrogen gas generation reaction also easily occurs at the same time.
The generation of the hydrogen gas can be suppressed by containing the trace metal. That is, the external appearance specific gravity in the related art is disclosed in
No. 96451, generally, 2.5 to
Although the range of 3.5 g / cm ³ was considered to be good, in the course of the research and development so far, the present inventors have set the appearance specific gravity of the zinc-based alloy powder containing the trace metal as the conventional lower limit value. 1.5 g / c smaller than 2.5 g / cm ³
even down to m ³ can suppress the occurrence of pre hydrogen gas discharge,
It has been known that the discharge utilization can be improved, and this point has been proposed in the earlier application. However, even in this case, the effective range of the appearance specific gravity is 1.5 to
When it is 2.4 g / cm ³ and 1.5 g / cm ³ or less, the negative electrode zinc is easily corroded in the electrolytic solution. This is considered to be because the gap between the zinc-based alloy powders becomes too large.

Therefore, the present inventors formed a zinc-based alloy into two or more kinds having different grain sizes and mixed them from the viewpoint of further increasing the specific surface area without increasing the gap between the zinc-based alloy powders. As a result of further research and development, the corrosion resistance and the hydrogen resistance were reduced even if the above specific gravity was reduced to 1.0 g / cm ³ under the condition where an inhibitor was added. It has been found that the gas generation suppressing effect is not impaired. This is because the zinc-based alloy powder having a small particle size enters between the zinc-based alloy powders having a large particle size and fills the voids. The base alloy powder can be used as a part of the negative electrode, and the high current discharge performance of the battery can be improved.

As described above, by using the zinc-based alloy powder according to the present invention as a negative electrode active material in a battery, a high-capacity battery excellent in large current discharge characteristics can be manufactured in a small size.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a zinc-based alloy powder for an alkaline battery according to the present invention will be described below with reference to first to seventh embodiments. First, the first embodiment will be described. A pure zinc base metal having a zinc purity of 99.9986% by weight or more is used as a raw material. At this time, unavoidable impurities are not considered. A trace metal is added to the pure zinc at a ratio in the range described below to obtain a molten metal. Next, the molten zinc-based alloy is made into a powder state in a chamber by a well-known gas atomizing method.

In this gas atomizing method, a molten zinc-based alloy to which each trace metal has been added is gas-sprayed in a chamber, and the sprayed and atomized molten zinc-based alloy is cooled and solidified. It becomes powder.

According to the above atomizing method, 0.2% by weight of Bi, 0.05% by weight of Zr, and
A zinc-based alloy powder was prepared from a molten metal to which 0.15% by weight of Sn was added. Then, this zinc-based alloy powder is
The mixture was sieved into two types having a particle size range of 5 to 70 mesh and 75 to 300 mesh, and two types of zinc-based alloy powders having different particle sizes were mixed at a weight ratio of 1: 1 to obtain a mixed powder. Further, when producing the zinc-based alloy powder by the above-mentioned atomizing method, the value of the specific gravity of the appearance is 0.9 to
Seven types of zinc-based alloy powders differing in the range of 1.8 g / cm ³ were produced, and mixed powders of the above-mentioned zinc-based alloy powders were obtained for each specific gravity. The specific gravity of the appearance is JIS Z
2504.

55% by weight of the zinc-based alloy mixed powder having each specific gravity of appearance, 44.4% by weight of a 40% by weight KOH solution saturated with ZnO, and In ₂ as an inhibitor.
O ₃ (indium oxide) was mixed at a ratio of 0.1% by weight and polyacrylic acid as a gelling agent was mixed at a ratio of 0.5% by weight.
Type alkaline dry battery was produced.

The amount of the negative electrode material charged in each of these batteries and the voltage at the start and end of the continuous discharge of 2Ω and 10Ω were 0.9.
A discharge test up to V was performed, and the discharge duration time was measured. Table 2 shows these measurement results as Test Example 1.

In the first embodiment, as described above, B
The reason why the addition amount of i was 0.2% by weight, the addition amount of Zr was 0.05% by weight, and the addition amount of Sn was 0.15% by weight is that the present inventors have been involved in the research and development process leading to the present invention. Among the effective composition ranges already known in the above, the most desirable numerical values are adopted. The effective composition range will be described later in fifth to seventh embodiments.

[0030]

[Table 2]

That is, as shown in Table 2, in the first embodiment in which the appearance specific gravity is in the range of 1.0 to 1.5 g / cm ³ , the performance of the high load discharge duration (2Ω) is as follows. Appearance specific gravities of 0.9 g / cm ³ and 1.6 g /
cm ³ and 1.8 g / cm ^3, which are 5 to 15 compared with the comparative example.
%, The performance of the low load discharge duration (10Ω) does not decrease. Incidentally, the appearance specific gravity of 1.6 g / cm ^3, although the change of the anode charge in two comparative examples of 1.8 g / cm ³ is not observed, which is believed to be due to the following.

That is, the specific gravity of appearance is determined by using an alcohol as a solvent, sedimenting zinc powder in a measuring cylinder, and measuring the volume of the sedimented zinc powder. On the other hand, the filling amount of the negative electrode is determined by adding an electrolytic solution and polyacrylic acid to zinc powder to form a gel, and then measuring the filling amount when the gelled product is filled in a battery. Here, the zinc powder having a low appearance specific gravity is gelled to improve the fluidity of the powder and increase the packing density of the zinc powder. On the other hand, a powder having a large specific gravity in appearance has a high filling density of zinc powder even in an alcohol solvent, and consequently, when gelled, the filling density of zinc powder becomes low. Therefore, the negative electrode filling amount was the same between the appearance specific gravity of 1.6 g / cm ³ and the appearance specific gravity of 1.8 g / cm ³ .

By the way, in the battery of the first embodiment, each battery having the specific gravity of each appearance was put in a gas pipette together with liquid paraffin and stored at 60 ± 2 ° C. for 3 days, and the amount of gas generated during the storage was measured. A test was conducted to examine the relationship between the specific gravity of appearance and the amount of gas generated before discharge. In addition, as a reference example, a sample to which no inhibitor was added was also measured.
Table 3 shows these measurement results as Test Example 2.

[0034]

[Table 3]

That is, as shown in Table 3, even when the specific gravity of appearance is 1.5 g / cm ³ or less, In ₂ O
It is understood that the addition of 0.1% by weight of ₃ can suppress the amount of generated gas.

Therefore, In ₂ as this inhibitor
The following tests were conducted in order to verify the effectiveness and problems of the added amount of O ₃ and to obtain the effective range.

That is, in the above battery, the amount of In ₂ O ₃ was defined as a parameter and the amount of addition was 0.01 wt% to 0.5
The batteries were prepared by varying the values in eight kinds within the range of weight%, and the amount of gas generated before and after the discharge of each battery was measured. The measurement of the gas generation amount before the discharge was performed in the same manner as in Table 3 above. The amount of gas generated after the discharge was measured by over-discharging each battery at a constant resistance value of 2Ω at a temperature of about 20 ° C. It was stored in a gas pipette together with paraffin at 60 ° C. for 3 days, and the amount of hydrogen gas discharged from the battery during storage was measured. Table 4 shows these measurement results as Test Example 3.

[0038]

[Table 4]

In Test Example 3 in Table 4 above, as practically desirable conditions, the amount of gas generated before discharge was less than 1.1 cc and the amount of gas generated after discharge was less than 1.5 cc.

As a result, In ₂ O mixed as an inhibitor in a zinc-based alloy powder containing Bi, Zr and Sn
_{(3) The} effects of the amount of gas generated before discharge and the amount of gas generated after discharge were observed in the range of 0.03 to 0.4% by weight.

Regarding gas generation before discharge, In ₂ O ₃
Is added, the inhibitory effect increases, and when the amount is 0.1% by weight, the inhibitory effect is greatest. Further, as the amount of In ₂ O ₃ added increases, the effect of suppressing the effect decreases.

As for the gas generation after the discharge, In
_{With the addition of 2} O ₃ , its suppression effect increases,
Similarly, when the content is 0.1% by weight, the suppression effect is the largest, and the suppression effect becomes weaker as the added amount of In ₂ O ₃ is further increased.

Therefore, as a practical range, Bi and Zr
And by adding in the In ₂ O ₃ and 0.03 to 0.4 wt% range as inhibitors of zinc-based alloy powder which had been contained and Sn, gas generation is suppressed, and using this alkaline cell discharge It has been found that hydrogen gas generation before and after discharge can be suppressed, and the load discharge characteristics are improved.

The above In ₂ O _{3 is used} as an inhibitor.
Instead of In ₂ (OH) ₃ (indium hydroxide), SnO ₂ (tin oxide), or Ca (OH) ₂
In order to verify the effectiveness of using (calcium hydroxide), a measurement experiment was performed in the same manner as described above.

That is, in the second embodiment, the first
A battery was manufactured in which the inhibitor was changed from In ₂ O ₃ to In ₂ (OH) ₃ in the embodiment. At this time, I
Batteries were fabricated by varying the amount of n ₂ (OH) ₃ added in the range of 0.02 to 0.6% by weight to eight types, and a measurement test of the gas generation amount of each battery was performed. Table 5 shows these measurement results as Test Example 4.

[0046]

[Table 5]

In Test Example 4 in Table 5 above, practically desirable conditions are that the amount of gas generated before discharge is less than 1.1 cc and the amount of gas generated after discharge is less than 1.5 cc as in Test Example 3. And

As a result, In ₂ (mixed as an inhibitor) in a zinc-based alloy powder containing Bi, Zr and Sn
OH) ₃ was effective in reducing the amount of gas generated before discharge and the amount of gas generated after discharge in the range of 0.04 to 0.5% by weight.

Regarding gas generation before discharge, In ₂ (O
H) With the addition of ₃ , its inhibitory effect increases,
When this is 0.1% by weight, the suppression effect is the largest. Further, as the amount of In ₂ (OH) ₃ added increases, the effect of suppressing the effect decreases.

Regarding gas generation after discharge, In
Its inhibitory effect As the adding ₂ (OH) ₃ is increased, also it is large and most its inhibitory effect upon the case of 0.1% by weight, further increasing the amount of In ₂ (OH) ₃ As a result, the inhibitory effect diminishes.

Therefore, as a practical range, Bi and Zr
By adding the In ₂ (OH) ₃ and 0.04 to 0.5 wt% range as inhibitors of zinc-based alloy powder which had been contained and Sn and, gas generation is suppressed, using the same alkaline batteries It was also found that hydrogen gas generation before and after discharge can be suppressed and load discharge characteristics are improved.

In the third embodiment, the inhibitor in the first embodiment is changed from In ₂ O ₃ to Sn.
A battery was prepared in which O ₂ was used. At this time, the battery was manufactured by varying the amount of SnO ₂ added in the range of 0.005 to 0.15% by weight to eight kinds, and the gas generation amount was measured and tested. Table 6 shows these measurement results as Test Example 5.

[0053]

[Table 6]

In Test Example 5 in Table 6 above, as a practically desirable condition, as in Test Example 3, the gas generation amount before discharge was less than 1.1 cc and the gas generation amount after discharge was 1.5 cc. Less than.

As a result, SnO ₂ mixed as an inhibitor in a zinc-based alloy powder containing Bi, Zr and Sn
The effect was recognized on the amount of gas generated before discharge and the amount of gas generated after discharge in the range of 0.01 to 0.14% by weight.

Regarding the gas generation before the discharge, the effect of suppressing the generation increases with the addition of SnO _2, and the effect of suppressing the gas generation is the greatest when the amount is 0.07% by weight. Further, as the added amount of SnO ₂ increases, the effect of suppressing the effect decreases.

Regarding gas generation after discharge, Sn gas
The suppression effect increases as O ₂ is added. Similarly, the suppression effect is greatest when the content is 0.07% by weight, and the suppression effect weakens as the addition amount of SnO ₂ increases. To go.

Therefore, as a practical range, Bi and Zr
By adding SnO ₂ as an inhibitor in the range of 0.01 to 0.14% by weight to a zinc-based alloy powder containing Sn and Sn, gas generation can be suppressed. It has been found that hydrogen gas generation after discharge can be suppressed and the load discharge characteristics are improved.

In a fourth embodiment, the inhibitor in the first embodiment is changed from In ₂ O ₃ to Ca.
A battery was prepared in which (OH) ₂ was used. At this time, Ca (O
H) The battery was manufactured by varying the addition amount of ₂ in eight kinds in the range of 0.003 to 0.06% by weight, and a measurement test of the gas generation amount was performed. Table 7 shows the results of these measurements as Test Example 6.

[0060]

[Table 7]

In Test Example 6 in Table 7 above, as a practically desirable condition, as in Test Example 3, the amount of gas generated before discharge was less than 1.1 cc and the amount of gas generated after discharge was 1.5 cc. Less than.

As a result, Ca (O) mixed as an inhibitor in a zinc-based alloy powder containing Bi, Zr and Sn
The effect of the addition amount of H) ₂ was recognized on the gas generation amount before discharge and the gas generation amount after discharge in the range of 0.004 to 0.05% by weight.

Regarding gas generation before discharge, Ca (O
H) With the addition of ₂ , the inhibitory effect increases,
When the content is 0.02% by weight, the suppression effect is the largest. Further, as the added amount of Bi is increased, the effect of suppressing Bi becomes weaker.

Regarding gas generation after discharge, Ca
As the (OH) ₂ is added, the inhibitory effect becomes greater. Similarly, when the content is 0.020% by weight, the inhibitory effect is the greatest, and as the amount of Ca (OH) ₂ added further increases. The suppression effect is diminished.

Therefore, as a practical range, Bi and Zr
By adding Ca (OH) ₂ as an inhibitor in the range of 0.004 to 0.05% by weight to a zinc-based alloy powder containing and Sn, gas generation is suppressed, and when this is used for an alkaline battery, It has been found that hydrogen gas generation before and after discharge can be suppressed, and that the load discharge characteristics are improved.

Hereinafter, the effective composition range of Bi, Zr, and Sn to be added in a small amount to pure zinc will be described.

First, a fifth embodiment for verifying the composition range of Bi will be described. In the fifth embodiment, Bi is added in an amount of 0.0005 to 0.60% by weight under the condition that 0.1% by weight of Zr and 0.15% by weight of Sn are added to pure zinc by the atomizing method.
By changing the composition range, seven kinds of zinc-based alloy powders having different amounts of added Bi were produced.

Then, each of the seven zinc-based alloy powders is sieved into two types having a particle size range of 35 to 70 mesh and 75 to 300 mesh, and the zinc-based alloy powders having different particle sizes are weight-weighted. The mixture was mixed at a ratio of 1: 1 to obtain a mixed powder.
When producing the zinc-based alloy powder by the above-mentioned atomizing method, the specific gravity of the appearance is adjusted by adjusting conditions such as atmosphere.
It was formed to 2 g / cm ³ .

55% by weight of the zinc-based alloy mixed powder having the above specific gravity, 44.4% by weight of a 40% by weight KOH solution saturated with ZnO, and In ₂ as an inhibitor.
0.1% by weight of O ₃ and 0.5% by weight of polyacrylic acid as a gelling agent were mixed at a predetermined volume as a negative electrode material to prepare the LR6 type alkaline dry battery of FIG. 1 described above. .

The amount of gas generated before and after discharge of each battery was measured by the same method as described above. Table 8 shows these measurement results as Test Example 7.

[0071]

[Table 8]

In Test Example 7 in Table 8 above, as a practically desirable condition, as in Test Example 3, the gas generation amount before discharge was set to less than 1.1 cc and the gas generation amount after discharge was set to 1.5 cc. Less than.

As a result, when the Bi content in the zinc-based alloy containing Zr and Sn is in the range of 0.001 to 0.5% by weight, the effect on the gas generation amount before discharge and the gas generation amount after discharge are respectively recognized. Was.

As for the generation of gas before the discharge, the effect of suppressing the gas generation increases with the addition of Bi.
In the case of 5% by weight, the suppression effect is the largest. Further, as the amount of added Bi increases, the effect of suppressing the effect decreases.

Further, as described above, the amount of hydrogen gas generated after the discharge, which was a problem only by adding Bi alone, can be reduced, and the suppression effect increases with the addition of Bi. In the case of% by weight, the suppression effect is the largest, and the suppression effect decreases as the amount of added Bi increases.

Therefore, as a practical range, Zr and Sn
0.001-0.50 Bi in a zinc-based alloy containing
By adding in the range of weight%, gas generation was suppressed, and it was found that when this was used for an alkaline battery, hydrogen gas generation before and after discharge could be suppressed and load discharge characteristics were improved.

Next, a sixth embodiment for verifying the composition range of Zr will be described. In the sixth embodiment, Zr is added in an amount of 0.0008 to 0.60% by weight under the condition that 0.2% by weight of Bi and 0.15% by weight of Sn are added to pure zinc by the atomizing method. % Of Zr-based alloy powders having different amounts of Zr were prepared. In other respects, an LR6 type alkaline dry battery is manufactured in the same manner as in the fifth embodiment,
The amount of gas generated before discharge and the amount of gas generated after discharge of each battery were measured in the same manner as described above. Table 9 shows these measurement results as Test Example 8.

[0078]

[Table 9]

In Test Example 7 in Table 8 above, as a practically desirable condition, as in Test Example 3, the gas generation amount before discharge was set to less than 1.1 cc and the gas generation amount after discharge was set to 1.5 cc. Less than.

As a result, when the Zr content in the zinc-base alloy containing Bi and Sn is in the range of 0.001 to 0.5% by weight, the effect is recognized on the gas generation amount before discharge and the gas generation amount after discharge, respectively. Was done.

As for the generation of gas before discharge, the effect of suppressing the generation of Zr increases with the addition of Zr.
In the case of 0% by weight, the suppression effect is the largest. Further, as the added amount of Zr increases, the effect of suppressing the effect decreases.

Further, as described above, the amount of hydrogen gas generated after the discharge, which had been a problem only by adding Bi alone, can be reduced, and as Zr is added, the effect of suppressing the increase is increased. In the case of% by weight, the suppression effect is the largest, and the suppression effect becomes weaker as the added amount of Zr is further increased.

Therefore, as a practical range, Bi and Sn
0.001 to 0.50 in a zinc-based alloy containing
By adding in the range of weight%, gas generation was suppressed, and it was found that when this was used for an alkaline battery, hydrogen gas generation before and after discharge could be suppressed and load discharge characteristics were improved.

Next, a seventh embodiment for verifying the composition range of Sn will be described. In the seventh embodiment, Sn is added in an amount of 0.0005 to 0.60% by weight under the condition that 0.2% by weight of Bi and 0.1% by weight of Zr are added to pure zinc by the atomizing method. , And eight kinds of zinc-based alloy powders having different amounts of Sn added were prepared. In other respects, an LR6 type alkaline dry battery was manufactured in the same manner as in the fifth embodiment, and the amount of gas generated before and after discharge of each battery was measured by the same method as described above. . Test results 9
As shown in Table 10.

[0085]

[Table 10]

In Test Example 9 in Table 10 above, as a practically desirable condition, as in Test Example 3, the gas generation amount before discharge was set to less than 1.1 cc and the gas generation amount after discharge was set to 1.5 cc. Less than.

As a result, when the Sn content in the zinc-base alloy containing Bi and Zr was in the range of 0.001 to 0.5% by weight, the effect was recognized on the gas generation amount before discharge and the gas generation amount after discharge, respectively. Was done.

As for the generation of gas before the discharge, the effect of suppressing the gas generation increases with the addition of Sn.
In the case of 5% by weight, the suppression effect is the largest. Further, as the amount of Sn added increases, the effect of suppressing the effect becomes weaker.

Further, as described above, the amount of hydrogen gas generated after the discharge, which had been a problem only by adding Bi alone, can be reduced, and as Sn is added, the effect of suppressing the increase is increased. In the case of% by weight, the inhibitory effect is the largest, and the inhibitory effect becomes weaker as the added amount of Sn increases.

Therefore, as a practical range, Bi and Zr
0.001 to 0.50 in a zinc-based alloy containing
By adding in the range of weight%, gas generation was suppressed, and it was found that when this was used for an alkaline battery, hydrogen gas generation before and after discharge could be suppressed and load discharge characteristics were improved.

[0091]

As described above in detail, according to the negative electrode zinc-based alloy powder for an alkaline battery of the present invention, harmful substances such as mercury, cadmium, and lead are not contained in zinc, and the safety is relatively high. By containing a combination of metals Bi, Zr and Sn, the amount of hydrogen gas generated is suppressed, and the suppression of hydrogen gas generation before and after discharge of an alkaline battery using this as a negative electrode and the load discharge characteristics are improved. Can be improved.

In addition, under the condition of adding the inhibitor, the zinc-based alloy powder is formed into two or more kinds having different particle sizes and used as a mixed powder by mixing them. The zinc-based alloy powder having a small particle size is filled in to fill the voids, so that the specific gravity of appearance is 1.0 to 1.5 g / cm while obtaining the corrosion resistance and the effect of suppressing the generation of hydrogen gas. A zinc-based alloy powder having a large specific surface area and excellent reactivity in an electrolytic solution, which is in the range of ³ , can be used as a negative electrode active material in a battery.

Therefore, by using the zinc-based alloy powder according to the present invention, a high-capacity battery excellent in large-current discharge characteristics can be manufactured in a small size.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an alkaline battery having a structure common to a conventional battery to which a zinc-based alloy powder of the present invention can be applied.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Battery case 2 Sealing gasket 3 Negative electrode terminal plate 4 Current collecting rod 5 Negative electrode 6 Separator 7 Positive electrode mixture

──────────────────────────────────────────────────続 き Continued on front page (72) Inventor Takaaki Yasumura 5-36-11 Shimbashi, Minato-ku, Tokyo Inside Fuji Electric Chemical Co., Ltd. (72) Yoshiteru Nakagawa 5-36-11 Shimbashi, Minato-ku, Tokyo Fuji Electric Chemical Co., Ltd. (72) Kazuo Matsui 5-36-11 Shimbashi, Minato-ku, Tokyo Fuji Electric Chemical Co., Ltd. (56) References JP-A-10-3908 (JP, A) JP Hei 4-26067 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01M 4/42 H01M 4/24 H01M 4/62

Claims (5)

(57) [Claims] 1. A zinc containing bismuth, zirconium and tin in a range of 0.001 to 0.5% by weight with respect to pure zinc and containing no harmful substances such as mercury, cadmium and lead. An alkaline battery comprising a base alloy, a powder having a specific gravity in the range of 1.0 to 1.5 g / cm < ³ > and a mixture of two or more kinds having different particle sizes, and an inhibitor added to the powder. Negative electrode zinc-based alloy powder. 2. The negative electrode zinc-based alloy powder for an alkaline battery according to claim 1, wherein said indium oxide is added in an amount of 0.03 to 0.4% by weight as said inhibitor. 3. The negative electrode zinc-base alloy powder for an alkaline battery according to claim 1, wherein indium hydroxide is added as the inhibitor in a range of 0.04 to 0.5% by weight. 4. The negative electrode zinc-base alloy powder for an alkaline battery according to claim 1, wherein stannic oxide is added as the inhibitor in a range of 0.01 to 0.14% by weight. 5. The negative electrode zinc-base alloy powder for an alkaline battery according to claim 1, wherein calcium hydroxide is added as the inhibitor in a range of 0.004 to 0.05% by weight.