JPH09293501A - Manufacture of hydrogen storage alloy electrode - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture a hydrogen storage alloy electrode with excellent characteristics as an alkaline storage battery by treating hydrogen storage alloy powder with an alkaline solution containing the specified amount of lithium hydroxide mono hydrate and cobalt ions, of the specified temperature. SOLUTION: Hydrogen storage alloy powder, for example ZrTi0.2 Mn0.6 V0.1 Cr0.3 Co0.1 Ni1.2 having a particle size of 45μm or less is immersed in an alkaline solution containing 5-150g/l lithium hydroxide mono hydrate and cobalt ions or copper ions, of 80-150 deg.C. The content of cobalt or copper ions is preferable to be equivalent to 10wt.% or less metallic cobalt or copper based on the weight of the hydrogen storage alloy. The alkaline solution is preferable to be an aqueouous solution containing about 31% NaOH, KOH, or RbOH. An electrode is manufactured with this treated hydrogen storage alloy powder. An alkaline storage battery negative electrode having excellent high rate discharge characteristics at low temperature and high corrosion resistance to an alkaline aqueous solution at high temperature is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a hydrogen storage alloy electrode using a hydrogen storage alloy capable of reversibly storing and releasing hydrogen.

[0002]

2. Description of the Related Art Lead-acid batteries and alkaline batteries are widely used as various power sources. Of these, alkaline storage batteries can be expected to have high reliability and can be made compact and lightweight, so small storage batteries have been used for various portable devices, and large storage batteries have been used for industrial purposes.

In this alkaline storage battery, an air electrode, a silver oxide electrode, and the like are partly taken up as a positive electrode.
In most cases, it is a nickel electrode using nickel hydroxide. The nickel electrode of the alkaline storage battery has changed from the pocket type to the sintered type, and the battery characteristics have improved, and since it has become possible to seal it, the applications of the alkaline storage battery have expanded.

On the other hand, as the negative electrode, zinc, iron, hydrogen, etc. are targeted in addition to cadmium. In order to achieve a higher energy density, a nickel-hydrogen storage battery using a metal hydride, that is, a hydrogen storage alloy has been attracting attention, and many proposals have been made for its manufacturing method.

In an alkaline storage battery using a hydrogen storage alloy capable of reversibly absorbing and releasing hydrogen in the negative electrode, the theoretical capacity density of the hydrogen storage alloy electrode is larger than that of the cadmium electrode.
It can be expected as a negative electrode for alkaline storage batteries having a high energy density. In addition, since it does not cause dissolution and precipitation due to redox of metals such as cadmium electrode and zinc electrode, there is little deformation of electrode plates and formation of dendrites, so long life can be expected and there is no pollution. have.

As an alloy used for such a hydrogen storage alloy electrode, generally, Ti--Ni system, Zr--Mn--N are used.
i-based and La (or Mm) -Ni based multi-component alloys are well known. Ti-Ni-based multi-component alloys can be classified as AB type, and Zr-Mn-Ni-based alloys can be classified as AB ₂ type, but both types show high capacity at the initial stage, but have poor life characteristics and improved life characteristics. However, there is a problem that the discharge characteristics are very poor.

La (or Mm) -Ni type alloys classified as AB ₅ type with respect to these alloys have a slightly lower capacity than AB type and AB ₂ type, but have excellent life characteristics and discharge characteristics. Therefore, in recent years, many developments have been made as electrode materials and put to practical use.

However, even nickel-hydrogen storage batteries using AB ₅ type alloys are inferior to nickel-cadmium storage batteries in high rate discharge characteristics at low temperatures and the like, and therefore further improvement in the characteristics of AB ₅ type alloys is demanded. . Further, in AB type and AB ₂ type alloys, which can be expected to have higher capacities than AB ₅ type alloys, there is a demand for improvement in discharge characteristics with an alloy composition having improved life characteristics.

[0009]

As one of the methods for solving the above problems, a method of immersing a hydrogen storage alloy powder or a hydrogen storage alloy electrode in an alkaline solution to improve discharge characteristics of the hydrogen storage alloy electrode. Is proposed. The so-called alkali treatment is a method of treating by immersing the hydrogen storage alloy powder or the hydrogen storage alloy electrode in an alkaline aqueous solution in which potassium hydroxide is dissolved. By this treatment, metal elements such as cobalt, manganese, vanadium, aluminum, and misch metal on the surface of the alloy, which are easily dissolved in the alkaline aqueous solution, are dissolved in the alkaline aqueous solution, and therefore, more stable than the above-mentioned metallic elements in the alkaline aqueous solution. Nickel remains in the surface layer of the alloy, and the nickel ratio in the surface layer is relatively increased to produce metallic nickel fine particles. It is considered that the metal nickel fine particles have an activity equivalent to that of a Raney-nickel catalyst which is well known as a highly active catalyst. In this way, the discharge characteristics have been improved by improving the electrochemical activity of the alloy powder or the alloy electrode. Further, it has been considered that the battery life is improved by previously removing the component elements on the surfaces of the alloy powder particles and the surface of the alloy electrode which are eluted in the alkaline aqueous solution.

However, even if the hydrogen-absorbing alloy powder or the hydrogen-absorbing alloy electrode is treated with an alkaline aqueous solution in which only potassium hydroxide is dissolved as described above, the discharge characteristics at a low temperature are improved and the alkaline solution at a high temperature is improved. Cannot improve corrosion resistance.

In view of the above, it is an object of the present invention to provide a hydrogen storage alloy electrode excellent as a negative electrode for an alkaline storage battery by improving high rate discharge characteristics at low temperature and improving corrosion resistance to an alkaline aqueous solution at high temperature.

[0012]

In order to achieve the above object, the present invention comprises a hydrogen storage alloy powder containing cobalt ions and / or copper ions, and lithium hydroxide monohydrate of 5 to 150 g / l. The method has a step of immersing it in an aqueous solution containing it in an alkaline solution at 80 to 150 ° C.

Further, the electrode made of a hydrogen storage alloy is contained in an aqueous solution containing cobalt ions and / or copper ions and 5 to 150 g / l of lithium hydroxide monohydrate.
There is a step of immersing in an alkaline solution at 0 to 150 ° C.

For the alkaline solution containing cobalt ions, cobalt hydroxide, cobalt oxide, cobalt chloride, cobalt nitrate, etc. are added to the alkaline solution, and for the alkaline solution containing copper ions, copper hydroxide, copper oxide, copper chloride, nitric acid is used. Copper and the like are added to the alkaline aqueous solution to adjust the contents.
It is preferable to add tartaric acid or citric acid to the alkaline aqueous solution containing copper ions.

The alkali treatment of the hydrogen-absorbing alloy powder or the hydrogen-absorbing alloy electrode is carried out with substantially oxygen gas in which the dissolution of oxygen in the alkaline aqueous solution is suppressed, such as in an inert gas atmosphere or in a state where the atmosphere is shut off. Is preferably performed in a state where the contact between the two is cut off.

The hydrogen storage alloy used in the present invention has the general formula L
nNi _x A _y (Ln is at least two lanthanides
Species, A is at least one element selected from the group consisting of Mn, Co, Al, Fe, Si, Cr, and Cu, and 4.5 <x + y <5.5, 3.0 <x, 0 <Y <
It is an alloy represented by 2.5). In addition, the general formula Zr _1.2-
a Ti _a Mn _w V _x Ni _y M _Z (where M is B, Al, S
i, Cr, Fe, Co, Cu, Zn, Nb, Mo, Ta
And at least one element selected from the group consisting of W and 0 ≦ a <1.2, 0.1 ≦ w ≦ 1.2, 0 ≦
x ≦ 0.4, 0.8 ≦ y ≦ 1.6, 0 <z ≦ 1.2,
1.7 ≦ (v + w + x + y + z) ≦ 2.7), in which the main component of the alloy phase is C14 (MgZ
n ₂ ) and C15 (MgCu ₂ ) type Laves phase.

An alloy containing Ln (where Ln is at least one of lanthanoid elements) and an alloy phase containing Ni as the main component in an amount of 30% by weight or less may be used.

[0018]

【Example】

(Example 1) A hydrogen storage alloy sample is a ZrTi _0.2 Mn _0.6 V _0.1 Cr _0.3 Co _0.1 Ni _{1.2 with} a grain size of 45 μm or less.
The alloy powder represented by

31 wt% containing cobalt hydroxide corresponding to 1 g of metallic cobalt based on 100 g of this alloy powder
A predetermined amount of lithium hydroxide monohydrate was added to 200 ml of an aqueous KOH solution to prepare an alkaline treatment liquid.

The alkali treatment liquid was placed in a heat-resistant resin container and heated to 120 ° C. The alloy powder was put into an alkali treatment liquid at 120 ° C., the lid was stirred, and the mixture was treated for 4 hours. After the treatment, after cooling and standing to remove the supernatant,
The alloy powder was prepared by washing with water, lowering the pH of the liquid, filtering and drying.

Although the treatment this time was performed at 120 ° C., the treatment time can be shortened by raising the treatment temperature. (1) Single cell test Each alloy sample was subjected to a single cell test in order to evaluate the electrode characteristics as a negative electrode for alkaline storage batteries, particularly the discharge characteristics at 0 ° C.

With respect to 3 g of the alloy sample powder treated under each of the above treatment conditions, 0.15 g of polyethylene fine powder as a binder was thoroughly mixed and stirred, and to this was added a dilute aqueous solution of carboxymethyl cellulose (1% by weight aqueous solution) and water. Made into a paste, average pore size 150μm, porosity 95%, length 4
A foamed nickel sheet having a size of 0 mm, a width of 25 mm and a thickness of 1.0 mm was filled. This was vacuum dried at 130 ° C. and pressed at a total pressure of 100 tons to prepare a test alloy electrode plate.

A nickel wire lead was attached to these test alloy electrode plates as a negative electrode, a sintered nickel electrode having an excessive capacity was used as a positive electrode, and a polyamide nonwoven fabric was used as a separator. A test battery was prepared using an aqueous potassium solution as an electrolytic solution.

First, the alloy electrode for test was activated by repeating the charging and discharging cycle at a constant current at 25 ° C. for 20 to 50 cycles. The charging / discharging conditions were as follows: 1 g of hydrogen-absorbing alloy was charged with a current of 100 mA for 5 hours, and similarly, 1 g of alloy was discharged with a current of 50 mA, and the discharge end voltage was 0.8V.

After completion of activation, the alloy was charged at a current of 20 mA / g of alloy for 30 hours at 25 ° C., discharged at 50 mA / g of alloy, and the discharge capacity up to 0.8 V was measured. Then, again at 25 ° C., 20 g / g of alloy
After charging for 30 hours at a current of mA, the battery was discharged at a current of 250 mA per 1 g of the alloy at 0 ° C., and the discharge capacity was measured. Fig. 1 shows the test alloy electrode plates at 25 ° C and 50 ° C.
Discharge capacity of mA / alloy 1g and 0 ° C, 250mA / alloy 1
The discharge capacity ratio of g is shown. Further, the saturation magnetization of each test alloy powder was determined by a small fully-automatic vibration sample magnetometer, and the result was converted into the amount of metallic nickel in the sample, and the results are shown in FIG.

The black dots in FIGS. 1 and 2 are the results when treated with an aqueous solution in which only lithium hydroxide monohydrate and cobalt hydroxide are dissolved. From this result, lithium hydroxide
The alloy powder could not be sufficiently activated by an aqueous solution in which only monohydrate and cobalt hydroxide were dissolved. It has been found that the alkaline solution for treating the alloy needs to dissolve potassium hydroxide, sodium hydroxide, rubidium hydroxide and the like.

From the results shown in FIGS. 1 and 2, when lithium hydroxide is dissolved in an alkaline treatment aqueous solution of alloy powder, the amount of metallic nickel or cobalt having magnetism on the alloy surface is increased, and the high rate discharge characteristics of the alloy electrode are obtained. Was found to improve. It is presumed that this is because the presence of lithium hydroxide promotes the dissolved oxygen of the alloy or the oxidative dissolution by cobalt hydroxide, and active metal nickel or cobalt is generated on the alloy surface. However, the discharge characteristics tended to deteriorate in the region where the amount of lithium hydroxide monohydrate dissolved exceeded 100 g. This is because the corrosion of the alloy surface became too large and the contact resistance between the alloy particles increased. (2) Sealed battery test Next, a sealed battery was prototyped in order to investigate battery characteristics.

A dilute aqueous solution of carboxymethyl cellulose (1% by weight aqueous solution) and water were added to the above-mentioned alkali-treated alloy sample powder, and the mixture was mixed and stirred to form a paste. The average pore size was 150 μm, the porosity was 95%, and the thickness was 1 0.0 mm
Was filled in the foamed nickel sheet. This was dried at 120 ° C., pressed by a roller press, and the surface thereof was coated with fluororesin powder to prepare an electrode.

These electrodes have a width of 3.5 cm and a length of 14 c.
m, and the thickness was adjusted to 0.4 mm, and lead plates were attached at two predetermined places. Then, the positive electrode (capacity: 1.5 Ah) and the separator were combined and wound into a spiral shape and housed in a 4/5 A size battery case. A known foaming nickel electrode was used for the positive electrode of these batteries, and a polypropylene nonwoven fabric imparted with hydrophilicity was used for the separator. Specific gravity 1.3
30g / l lithium hydroxide to the potassium hydroxide aqueous solution
After injecting the dissolved electrolytic solution, the battery case was sealed to prepare a sealed battery.

The battery thus prepared was charged at 25 ° C. to 150% at 0.1 C (10 hour rate),
Charge and discharge at a final voltage of 0.8 V at 0.2 C
A battery was formed by cycling. 20 after battery formation
After charging 120% at 1C and 0.2C, the battery was discharged to 0.8V at 0.2C, and the discharge capacity up to 0.8V was measured. Again, 20
120% charge at 1 ° C, 1C discharge at 0 ° C,
The discharge capacity up to 0.8 V was measured. 3 ° C and 1C
The ratio of the discharge capacity at 20 ° C. to the discharge capacity at 0.2 C is shown.

From FIGS. 2 and 3, it was found that the 0 ° C. and 1 C discharge characteristics of the battery were greatly improved when the saturated magnetization equivalent nickel content in the alloy was about 2% or more. From this result, it was found that an electrode having excellent characteristics can be obtained by the treatment of this example.

(Example 2) The hydrogen storage alloy sample had a particle size of 4
General formula of 5 μm or less ZrMn _0.55 V _0.15 Cr _0.2 Co _0.1
An alloy powder represented by Ni _1.15 was used and treated with an alkaline aqueous solution containing copper ions. This alkaline aqueous solution is obtained by adding a predetermined amount of lithium hydroxide monohydrate to 200 ml of a 31 wt% KOH aqueous solution containing copper hydroxide corresponding to 1 g of metallic copper per 100 g of alloy powder.

The alkali treatment liquid was placed in a heat-resistant resin container and heated to 120 ° C. The alloy powder was put into an alkali treatment liquid at 120 ° C., the lid was covered, and the mixture was stirred and treated for 6 hours. After the treatment, after cooling and standing to remove the supernatant,
The alloy powder was obtained by washing with water, lowering the pH of the liquid, filtering and drying. (1) Single cell test A test alloy electrode plate was prepared in the same manner as in Example 1, and the same test was performed. Fig. 4 shows the temperature of each test alloy electrode plate at 25 ° C.
A discharge capacity ratio of 50 mA / alloy 1 g and a discharge capacity ratio of 0 ° C. and 250 mA / alloy 1 g are shown. Further, the saturation magnetization of each test alloy powder was measured, and the converted amount as metallic nickel in the sample was obtained from the value. The results are shown in FIG.

Since the activity of metallic copper as a catalyst is lower than that of metallic cobalt of Example 1, the result of FIG. 4 shows a lower value than that of FIG. In addition, the amount of nickel equivalent to the saturation magnetization in the alloy of FIG. 5 is also as shown in FIG.
Showed a lower value than However, the discharge characteristics of the alloy electrode could be improved by further dissolving lithium hydroxide / monohydrate in an alkaline aqueous solution in which copper ions were treated to treat the alloy powder.

In the case of copper, the discharge characteristics were improved because the activation of the surface of the alloy produced by the alkali treatment with metallic nickel and the contact resistance between the alloy particles due to the metallic copper reduced by the corrosion of the alloy decreased.

The amount of lithium hydroxide monohydrate dissolved is 100
In the region exceeding g, neither the discharge characteristics of the alloy electrode nor the amount of nickel equivalent to saturation magnetization were improved. (2) Sealed battery test Next, a sealed battery was prototyped in order to investigate battery characteristics.

A sealed battery was prepared in the same manner as in Example 1 using the alloy sample powder subjected to the above alkali treatment.

The battery thus produced was charged at 25 ° C. to 150% at 0.1 C (10 hour rate),
Charge and discharge at a final voltage of 0.8 V at 0.2 C
A battery was formed by cycling. 20 after battery formation
After charging 120% at 1C and 0.2C, the battery was discharged to 0.8V at 0.2C, and the discharge capacity up to 0.8V was measured. Again, 20
120% charge at 1 ° C, 1C discharge at 0 ° C,
The discharge capacity up to 0.8 V was measured. 6 ° C and 1C
The ratio of the discharge capacity at 20 ° C. to the discharge capacity at 0.2 C is shown.

From the results shown in FIG. 6, it was found that by treating the alloy powder with an alkaline treatment aqueous solution in which lithium hydroxide / monohydrate and copper hydroxide were dissolved, the 0 ° C., 1 C discharge characteristics were improved. From this result, an electrode having excellent characteristics can be obtained by the treatment according to this embodiment.

(Example 3) The hydrogen storage alloy sample had a particle size of 7
General formula of 5 μm or less MmNi _3.6 Co _0.65 Mn _0.4 Al
An alloy powder represented by _0.2 Cr _0.15 was used.

5% by weight of polyethylene fine powder was added to the above alloy powder to obtain an average pore size of 150 μm and a porosity of 95.
%, 40 mm in length, 25 mm in width, and 1.0 mm in thickness. This sheet was pressed at a total pressure of 100 tons and then heat-treated at 130 ° C. in a vacuum dryer to prepare an electrode containing 2 g of the alloy.

This electrode was mixed with 200 ml of a 31% by weight KOH aqueous solution containing cobalt hydroxide corresponding to the amount of metallic cobalt of 0.6% by weight based on the alloy.
The sample was immersed in an aqueous solution containing monohydrate to perform alkali treatment. The alkali treatment was carried out at 100 ° C. for 1 hour. After treatment,
It was taken out from the alkaline treatment liquid, washed with water, and dried to prepare alloy electrode plates for each test. (1) Single Cell Test The same single cell test as in Example 1 was performed. FIG. 7 shows the discharge capacity ratio of each test alloy electrode plate at 25 ° C., 50 mA / g alloy and 0 ° C., 250 mA / g alloy. Further, alloy powder was taken out from each test alloy electrode, its saturation magnetization was measured, and the converted amount as metallic nickel in the sample was obtained from the value. The result is shown in FIG.

From the results shown in FIG. 7, it was found that the discharge characteristics of the alloy electrode were improved by using an alkaline aqueous solution in which lithium hydroxide monohydrate and cobalt hydroxide were dissolved. According to the result of FIG. 8, the amount of nickel equivalent to the saturation magnetization in the alloy is smaller than that of FIG. 2 because the activation treatment with the alkaline aqueous solution is performed in the electrode plate state, so that the alloy corrosion inside the electrode plate hardly occurs. This is because.

The activation by the electrode plate has lower characteristics than the activation treatment in the powder state, but the deterioration of the characteristics due to excessive treatment conditions is small. (2) Sealed battery test Next, a sealed battery was prototyped in order to investigate battery characteristics.

A dilute aqueous solution of carboxymethyl cellulose was added to the above alloy sample powder, mixed and stirred to form a paste, and filled into a foamed nickel sheet having an average pore size of 150 μm, a porosity of 95% and a thickness of 1.0 mm. This was dried at 120 ° C. and pressed with a roller press to form an electrode. This electrode plate was treated in the same manner as the above electrode plate treatment. After the electrode plate treatment, the surface of the electrode plate was coated with fluororesin powder.

A sealed battery similar to that of Example 1 was prepared using these electrodes. The battery created in this way is
A battery was formed by performing 10 cycles of charging and discharging at 5 ° C. to 150% at 0.1 C (10 hour rate) and discharging to a final voltage of 0.8 V at 0.2 C. After forming the battery,
After charging 120% at 20 ° C. and 1 C, it was discharged to 0.8 V at 0.2 C, and the discharge capacity up to 0.8 V was measured. again,
After charging 120% at 20 ° C. and 1 C, 1 C discharge at 0 ° C. and discharge capacity up to 0.8 V were measured. In Figure 9, 0 ℃,
The ratio of the discharge capacity at 1C to the discharge capacity at 20 ° C and 0.2C is shown. From the results shown in FIG. 9, it was found that by treating the alloy electrode plate with an alkaline treatment aqueous solution in which lithium hydroxide / monohydrate and cobalt hydroxide were dissolved, 0 ° C. and 1 C discharge characteristics were improved. From this result, an electrode having excellent characteristics can be obtained by the treatment according to this embodiment.

Example 4 The hydrogen storage alloy sample had a particle size of 7
General formula of 5 μm or less MmNi _3.2 Co _0.85 Mn _0.6 Al
An alloy powder represented by _0.2 Cr _0.15 was used.

An electrode plate containing 2 g of alloy was prepared in the same manner as in Example 3 using the above alloy powder. This test electrode was dipped in an aqueous solution containing a predetermined amount of lithium hydroxide / monohydrate in 200 ml of a 31% by weight KOH aqueous solution containing copper hydroxide corresponding to the amount of metallic copper of 0.6% by weight with respect to the alloy. Alkali treatment was performed. The alkali treatment was carried out at 100 ° C. for 1 hour. After the treatment, it was taken out from the alkaline treatment liquid, washed with water and dried to prepare each test alloy electrode plate. (1) Single Cell Test The same single cell test as in Example 1 was performed. FIG. 10 shows the discharge capacity ratio of each test alloy electrode plate at 25 ° C., 50 mA / g of alloy 1 g and the discharge capacity ratio of 0 ° C., 250 mA / g of alloy 1 g.
Further, alloy powder was taken out from each test alloy electrode, its saturation magnetization was measured, and the converted amount as metallic nickel in the sample was obtained from the value. The results are shown in FIG.

From the results shown in FIG. 10, the discharge characteristics of the alloy electrode were improved by activating the alloy electrode plate with an alkaline aqueous solution in which lithium hydroxide monohydrate and copper hydroxide were dissolved. (2) Sealed battery test Next, a sealed battery was prototyped in order to investigate battery characteristics.

A dilute aqueous solution of carboxymethyl cellulose was added to the above alloy sample powder, mixed and stirred to form a paste, and filled into a foamed nickel sheet having an average pore size of 150 μm, a porosity of 95% and a thickness of 1.0 mm. This was dried at 120 ° C. and pressed with a roller press to form an electrode. This electrode plate was treated in the same manner as the above electrode plate treatment. After the electrode plate treatment, the surface of the electrode plate was coated with fluororesin powder.

A sealed battery similar to that of Example 1 was prepared using these electrodes. The battery created in this way is
A battery was formed by performing 10 cycles of charging and discharging at 5 ° C. to 150% at 0.1 C (10 hour rate) and discharging to a final voltage of 0.8 V at 0.2 C. After forming the battery,
After charging 120% at 20 ° C. and 1 C, it was discharged to 0.8 V at 0.2 C, and the discharge capacity up to 0.8 V was measured. again,
After charging 120% at 20 ° C. and 1 C, 1 C discharge at 0 ° C. and discharge capacity up to 0.8 V were measured. 0 in FIG.
The ratio of the discharge capacity at 1 ° C. to 20 ° C. and 0.2 C is shown. From the results shown in FIG. 12, it was found that by treating the alloy electrode plate with an alkaline treatment aqueous solution in which lithium hydroxide monohydrate and copper hydroxide were dissolved, 0 ° C. and 1 C discharge characteristics were improved. From this result, an electrode having excellent characteristics can be obtained by the treatment according to this embodiment.

In this embodiment, the alkaline aqueous solution in which potassium hydroxide is dissolved has been described above, but the same effect can be obtained also in the alkaline aqueous solution in which sodium hydroxide and rubidium hydroxide are dissolved.

Further, the same effect can be obtained by forming an electrode using an alkali-treated alloy powder and subjecting it to alkali treatment.

[0054]

According to the present invention, since the alkali treatment can be performed at a high temperature, it is possible to obtain a hydrogen storage alloy electrode having an improved working efficiency and excellent electrode characteristics of discharge capacity at a low temperature.

[Brief description of drawings]

FIG. 1 is a graph showing a high rate discharge capacity ratio at a low temperature with respect to a dissolved amount of lithium hydroxide / monohydrate according to Example 1 of the present invention.

FIG. 2 is a graph showing the weight ratio of metallic nickel in the electrode to the dissolved amount of lithium hydroxide monohydrate according to Example 1 of the present invention.

FIG. 3 is a graph showing the discharge capacity ratio at low temperature to the amount of lithium hydroxide monohydrate dissolved according to Example 1 of the present invention.

FIG. 4 is a diagram showing a high rate discharge capacity ratio at a low temperature with respect to a dissolved amount of lithium hydroxide / monohydrate according to Example 2 of the present invention.

FIG. 5 is a diagram showing the weight ratio of metallic nickel in the electrode to the amount of dissolved lithium hydroxide monohydrate according to Example 2 of the present invention.

FIG. 6 is a graph showing a discharge capacity ratio at a low temperature with respect to a dissolution amount of lithium hydroxide / monohydrate according to Example 2 of the present invention.

FIG. 7 is a graph showing a high rate discharge capacity ratio at low temperature with respect to a dissolution amount of lithium hydroxide / monohydrate according to Example 3 of the present invention.

FIG. 8 is a graph showing the weight ratio of metallic nickel in the electrode to the dissolved amount of lithium hydroxide monohydrate according to Example 3 of the present invention.

FIG. 9 is a graph showing a discharge capacity ratio at low temperature with respect to a dissolution amount of lithium hydroxide / monohydrate according to Example 3 of the present invention.

FIG. 10 is a diagram showing a high rate discharge capacity ratio at low temperature to the amount of dissolved lithium hydroxide / monohydrate according to Example 4 of the present invention.

FIG. 11 is a diagram showing the weight ratio of metallic nickel in the electrode to the dissolved amount of lithium hydroxide monohydrate according to Example 4 of the present invention.

FIG. 12 is a graph showing the discharge capacity ratio at low temperature to the amount of dissolved lithium hydroxide monohydrate according to Example 4 of the present invention.

Claims (7)

[Claims] 1. A hydrogen storage alloy powder is prepared from lithium hydroxide.
An electrode is formed using a step of immersing in an alkaline solution containing 5 to 150 g / l of monohydrate and containing cobalt ions at a temperature of 80 to 150 ° C., and the hydrogen storage alloy powder subjected to the above treatment. A method of manufacturing a hydrogen storage alloy electrode having a step. 2. An electrode formed using a hydrogen storage alloy powder, containing 5-150 g / l of lithium hydroxide monohydrate,
A method for producing a hydrogen storage alloy electrode, which comprises a step of immersing the electrode in an alkaline solution in which cobalt ions are present and at a temperature of 80 to 150 ° C. 3. The method for producing a hydrogen storage alloy electrode according to claim 1, wherein the treatment is carried out using cobalt ions corresponding to 10% by weight or less of metallic hydrogen cobalt with respect to the hydrogen storage alloy. 4. A hydrogen storage alloy powder is prepared from lithium hydroxide.
An electrode is formed using a step of immersing in an alkaline solution containing 5-150 g / l of monohydrate and containing copper ions at a temperature of 80 to 150 ° C., and the hydrogen storage alloy powder that has been subjected to the above treatment. A method of manufacturing a hydrogen storage alloy electrode having a step. 5. An electrode formed using a hydrogen storage alloy powder, containing 5-150 g / l of lithium hydroxide monohydrate,
And a method for producing a hydrogen storage alloy electrode, which comprises a step of immersing the electrode in an alkaline solution containing copper ions at a temperature of 80 to 150 ° C. 6. The method for producing a hydrogen storage alloy electrode according to claim 4, wherein the treatment is carried out using copper ions corresponding to 10% by weight or less of metallic copper with respect to the hydrogen storage alloy. 7. The method for producing a hydrogen storage alloy electrode according to claim 1, wherein the alkaline treatment solution is a solution in which at least one of potassium hydroxide, sodium hydroxide and rubidium hydroxide is dissolved.