JP2002260643A - Hydrogen storage alloy electrode and manufacturing method therefor, and alkaline storage battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an alkaline storage battery with superior discharge characteristics and charge and discharge cycle characteristics by improving the hydrogen storage alloy electrode. SOLUTION: A coating layer is provided on the surface of the hydrogen storage alloy electrode 2 with electrode material, using hydrogen storage alloy particles attached to the collector thereof. The coating layer contains at least one first element selected from among nickel and cobalt and at least one second element selected from among yttrium, ytterbium, lanthanum, erbium, bismuth, cerium, praseodymium, neodymium and calcium, and the hydrogen storage alloy electrode is used as the negative electrode of the alkaline storage battery.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an alkaline storage battery such as a nickel-hydrogen storage battery, a hydrogen storage alloy electrode used for a negative electrode of the alkaline storage battery, and a method of manufacturing the hydrogen storage alloy electrode. The present invention is characterized in that the alloy electrode is improved to improve high-rate discharge characteristics and charge / discharge cycle characteristics in an alkaline storage battery.

[0002]

2. Description of the Related Art Conventionally, as one of alkaline storage batteries, a nickel-based battery using a hydrogen storage alloy electrode for its negative electrode has been used.
Hydrogen storage batteries are known.

[0003] The hydrogen storage alloy electrode in such an alkaline storage battery is generally prepared by adding a binder to a hydrogen storage alloy powder to prepare a paste, applying the paste to a current collector, and drying the paste. Is used.

However, in the alkaline storage battery using the hydrogen storage alloy electrode as described above, the conductivity of the hydrogen storage alloy electrode is not sufficient, the charge / discharge characteristics at a high current are deteriorated, and the positive electrode is overcharged during overcharge. Due to the generated oxygen, the surface of the hydrogen storage alloy in the hydrogen storage alloy electrode is oxidized, or the hydrogen storage alloy is corroded by the alkaline electrolyte, the hydrogen storage alloy electrode deteriorates, and the discharge capacity gradually decreases. In addition, there is a problem that charge / discharge cycle characteristics are deteriorated.

To solve such a problem, for example,
JP-B-7-63006 (Japanese Patent Application Laid-Open No. 63-266767)
In the publication, a porous conductive layer made of nickel or the like is provided on the surface of the hydrogen storage alloy electrode to increase the conductivity of the hydrogen storage alloy electrode, and the hydrogen storage alloy electrode is formed by oxygen generated at the positive electrode during overcharge. 1 shows that the hydrogen storage alloy is prevented from being oxidized.

However, even when a porous conductive layer made of nickel or the like is provided on the surface of the hydrogen storage alloy electrode as described above, the conductivity of the hydrogen storage alloy electrode cannot be sufficiently increased. The hydrogen storage alloy at the hydrogen storage alloy electrode cannot be sufficiently prevented from being oxidized by oxygen generated at the positive electrode during overcharge, and the charge / discharge characteristics and charge / discharge cycle characteristics at high currents are sufficiently improved. Could not.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems in an alkaline storage battery using a hydrogen storage alloy electrode as a negative electrode.
It is an object of the present invention to improve a hydrogen storage alloy electrode so that an alkaline storage battery having excellent high rate discharge characteristics and charge / discharge cycle characteristics can be obtained.

[0008]

In the hydrogen storage alloy electrode according to the present invention, in order to solve the above problems, an electrode material using hydrogen storage alloy particles is applied to the surface of the electrode attached to the current collector. , A coating comprising at least one first element selected from nickel and cobalt and at least one second element selected from the group of yttrium, ytterbium, lanthanum, erbium, bismuth, cerium, praseodymium, neodymium and calcium A layer was provided.

When the hydrogen storage alloy electrode according to the present invention is used for a negative electrode of an alkaline storage battery, the hydrogen storage alloy electrode is formed by at least one first element selected from nickel and cobalt in a coating layer formed on the surface of the electrode. The conductivity of the electrode is improved, and the hydrogen storage alloy in the hydrogen storage alloy electrode is oxidized by oxygen generated in the positive electrode during overcharging. , Neodymium, and calcium are further suppressed by at least one second element selected from the group of.

[0010] As described above, the conductivity of the hydrogen storage alloy electrode is improved, and the oxidation of the hydrogen storage alloy in the hydrogen storage alloy electrode by oxygen generated at the positive electrode during overcharge is suppressed. High rate discharge characteristics and charge / discharge cycle characteristics of the storage battery are improved. In particular, when the coating layer in which the first element is nickel and the second element is yttrium is provided, the high-rate discharge characteristics and the charge / discharge cycle characteristics of the alkaline storage battery are further improved. .

Here, in the hydrogen storage alloy electrode of the present invention, at least one first element selected from nickel and cobalt and yttrium, ytterbium, lanthanum, erbium, bismuth, Various methods can be used for providing a coating layer containing at least one kind of second element selected from the group consisting of cerium, praseodymium, neodymium, and calcium. In order to easily provide the above-described coating layer, it is preferable to form the coating layer by plating.
In particular, it contains at least one first element selected from nickel and cobalt and at least one second element selected from the group consisting of yttrium, ytterbium, lanthanum, erbium, bismuth, cerium, praseodymium, neodymium and calcium. It is preferable to form the above-mentioned coating layer on the surface of the electrode by electroless plating using a plating solution.

In addition, as described above, at least one first element selected from nickel and cobalt and at least one first element selected from the group consisting of yttrium, ytterbium, lanthanum, erbium, bismuth, cerium, praseodymium, neodymium and calcium are formed on the surface of the electrode. In forming a coating layer containing at least one selected second element, if the weight ratio of the coating layer to the weight of the hydrogen storage alloy particles in the electrode is small, oxygen generated at the positive electrode during overcharging causes Oxidation of the hydrogen storage alloy therein cannot be sufficiently suppressed, while if the weight ratio of the coating layer is too large, the entire surface of the hydrogen storage alloy electrode is covered by the coating layer and becomes full. Discharge reaction hardly occurs. For this reason, the weight ratio of the coating layer to the weight of the hydrogen storage alloy particles in the electrode is preferably in the range of 1% by weight to 10% by weight.

Further, in the above-mentioned coating layer, the second
If the amount of the element is small, it is not possible to sufficiently suppress oxidation of the hydrogen storage alloy in the electrode by oxygen generated at the positive electrode during overcharge, while if the amount of the second element is too large, It is considered that the second element makes it difficult for a charge / discharge reaction to occur in the hydrogen storage alloy electrode. Therefore, the weight ratio of the second element to the weight of the hydrogen storage alloy particles in the electrode is set to 0.5% by weight to 5% by weight.
It is preferable to be within the range.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the hydrogen storage alloy electrode according to the present invention, a method for producing the same, and an alkaline storage battery will be specifically described with reference to examples, and the alkaline storage battery according to the embodiment of the present invention will have a high rate discharge characteristic. It is clarified that the charge and discharge cycle characteristics are improved as well as the operating voltage is increased by a comparative example. In addition,
The hydrogen storage alloy electrode and the method for producing the same and the alkaline storage battery according to the present invention are not particularly limited to those shown in the following examples, and can be carried out by appropriately changing the scope without changing the gist thereof. .

(Example A1) In Example A1, a hydrogen storage alloy powder having an average particle diameter of 50 μm represented by a composition formula of MmNi _3.2 Co _1.0 Al _0.2 Mn _0.6 was used. In this hydrogen storage alloy powder, M
The misch metal represented by m is La: Ce: Pr: N
d = 25: 50: 6: 19 by weight.

Then, 0.5 parts by weight of a styrene-methacrylic acid ester copolymer and 0.5 parts by weight of polyethylene oxide were added as binders to 100 parts by weight of the above hydrogen storage alloy powder, and a small amount of polyethylene oxide was added. Water is added, and these are mixed to prepare a paste. This paste is uniformly applied to both surfaces of a current collector made of a nickel-plated punched metal, dried, and then rolled to form a hydrogen storage alloy electrode. Produced.

Next, in one liter, 26 g of nickel sulfate containing nickel of the first element, 3.0 g of yttrium sulfate containing yttrium of the second element, 60 g of sodium citrate, 21 g of sodium hypophosphite, The above-mentioned hydrogen-absorbing alloy electrode was placed in a plating solution containing ammonium sulfate at a rate of 65 g, adjusted to pH 8 with ammonium hydroxide, and having a bath temperature of 90 ° C. for 31 minutes 3 minutes.
By dipping for 7 seconds, a coating layer containing the first element made of nickel Ni and the second element made of yttrium Y was formed on the surface of the hydrogen storage alloy electrode by electroless plating.

Here, the weight ratio of the coating layer to the weight of the hydrogen storage alloy particles in the hydrogen storage alloy electrode was 7% by weight. Further, the weight of the second element made of yttrium Y in the above-mentioned coating layer is determined by an ICP method (Inductivily Coupled Plasma Atomic Emission Spectral).
(rometry: ICP-AES), the weight ratio of the second element yttrium to the weight of the hydrogen storage alloy particles was 0.7% by weight.

Then, a hydrogen-absorbing alloy electrode having a coating layer formed on its surface containing the first element made of nickel Ni and the second element made of yttrium Y was used as a negative electrode, as shown in FIG. An alkaline storage battery having a cylindrical shape and a battery capacity of about 1 Ah was produced.

Here, in this alkaline storage battery,
As the positive electrode, a sintered nickel electrode prepared by impregnating an 85% porosity nickel sintered substrate with a nickel nitrate aqueous solution containing cobalt nitrate and zinc nitrate by a chemical impregnation method is used. An alkaline nonwoven fabric was used, and a 30% by weight aqueous solution of potassium hydroxide was used as an alkaline electrolyte.

In order to manufacture an alkaline storage battery, as shown in FIG. 1, a separator 3 is interposed between a positive electrode 1 and a negative electrode 2 and wound into a spiral shape. After that, the above-mentioned alkaline electrolyte is poured into the negative electrode can 4 and sealed, the positive electrode 1 is connected to the sealing lid 6 via the positive electrode lead 5, and the negative electrode 2 is connected to the negative electrode can 4 via the negative electrode lead 7. To the negative electrode can 4 and the sealing lid 6
Is electrically insulated by an insulating packing 8 and
Coil spring 1 between sealing lid 6 and positive external terminal 9
0 is set, and when the internal pressure of the battery rises abnormally, the coil spring 10 is compressed so that the gas inside the battery is released to the atmosphere.

(Examples A2 to A9) In Examples A2 to A9, the same composition formula Mm as in Example A1 was used.
Using a hydrogen storage alloy powder having an average particle diameter of 50 μm represented by Ni _3.2 Co _1.0 Al _0.2 Mn _0.6 , the hydrogen storage alloy powder 100 was used in the same manner as in Example A1.
As a binder, 0.5 parts by weight of a styrene-methacrylic acid ester copolymer and 0.5 parts by weight of polyethylene oxide were added as binders, a small amount of water was added, and these were mixed to prepare a paste. Then, the paste was uniformly applied to both surfaces of a current collector made of nickel-plated punched metal, dried, and then rolled to produce a hydrogen storage alloy electrode.

In forming a coating layer on the surface of the hydrogen-absorbing alloy electrode produced as described above, Example A2
In Examples A1 to A9, the type of the second element added to the plating solution used in Example A1 was changed, and instead of 3.0 g of yttrium sulfate, 2.1 g of ytterbium sulfate was used in Example A2, and Example A3 was used. Then lanthanum sulfate was added to 2.
4 g, 2.5 g of erbium sulfate in Example A4, 2.0 g of bismuth sulfate in Example A5, 2.8 g of cerium sulfate in Example A6, 2.4 g of praseodymium sulfate in Example A7, and 2.4 g of praseodymium sulfate in Example A8. 2.4 Neodymium sulfate
g, in Example A9, 4.0 g of calcium sulfate was added. Otherwise, in the same manner as in Example A1, the first element made of nickel Ni and Ytterbium Yb, Lantern L
a, a coating layer containing erbium Er, bismuth Bi, cerium Ce, praseodymium Pr, neodymium Nd and one kind of second element selected from calcium Ca was formed.

Here, the weight ratio of each coating layer to the weight of the hydrogen storage alloy particles in each of the hydrogen storage alloy electrodes is 7% by weight, and the weight ratio of each of the coating layers to the weight of the hydrogen storage alloy particles is 7% by weight. The weight ratio of the second element is 0.7
Weight percent.

Then, in the same manner as in Example A1 except that the hydrogen storage alloy electrode on which each coating layer is formed as described above is used as the negative electrode, the battery capacity becomes about 1 Ah in the cylindrical shape. Each of the alkaline storage batteries of Examples A2 to A9 was manufactured.

Example B1 In Example B1, the same compositional formula MmNi _3.2 Co as in Example A1 was used.
_Using a hydrogen storage alloy powder having an average particle size of _1.0 Al _0.2 Mn _{0.6 and} having a particle size of 50 μm, a binder was added to 100 parts by weight of the hydrogen storage alloy powder in the same manner as in Example A1. 0.5 parts by weight of styrene-methacrylic acid ester copolymer and 0.5 parts by weight of polyethylene oxide
A part by weight and a small amount of water were added, and these were mixed to prepare a paste.This paste was uniformly applied to both surfaces of a current collector made of a nickel-plated punched metal, dried, and then rolled. To produce a hydrogen storage alloy electrode.

In forming a coating layer on the surface of the hydrogen storage alloy electrode produced as described above, in Example B1, 15 g of cobalt sulfate containing cobalt of the first element in 1 liter, 1.8 g of yttrium sulfate containing two elements of yttrium, 115 g of sodium tartrate, 30 g of boric acid, and 21 g of sodium hypophosphite are contained at a ratio of 21 g with sodium hydroxide.
The hydrogen storage alloy electrode was immersed for 21 minutes and 5 seconds in a plating solution having a bath temperature of 90 ° C.
By electroless plating, a first element made of cobalt Co and yttrium Y are formed on the surface of the hydrogen storage alloy electrode.
And a coating layer containing the second element consisting of

Here, the weight ratio of the coating layer to the weight of the hydrogen storage alloy particles in the hydrogen storage alloy electrode is 7% by weight, and is made of the above-mentioned yttrium Y with respect to the weight of the hydrogen storage alloy particles. The weight ratio of the second element was 0.7% by weight.

Then, in the same manner as in Example A1 except that the hydrogen storage alloy electrode on which the coating layer is formed is used as the negative electrode, a cylindrical battery having a battery capacity of about 1 A is used.
h, an alkaline storage battery of Example B1 was produced.

(Examples B2 to B9) In Examples B2 to B9, the same composition formula Mm as in Example A1 was used.
Using a hydrogen storage alloy powder having an average particle diameter of 50 μm represented by Ni _3.2 Co _1.0 Al _0.2 Mn _0.6 , the hydrogen storage alloy powder 100 was used in the same manner as in Example A1.
As a binder, 0.5 parts by weight of a styrene-methacrylic acid ester copolymer and 0.5 parts by weight of polyethylene oxide were added as binders, a small amount of water was added, and these were mixed to prepare a paste. Then, the paste was uniformly applied to both surfaces of a current collector made of nickel-plated punched metal, dried, and then rolled to produce a hydrogen storage alloy electrode.

In forming a coating layer on the surface of the hydrogen-absorbing alloy electrode produced as described above, Example B2
In Examples B2 to B9, the type of the second element added to the plating solution used in Example B1 was changed, and instead of 1.8 g of yttrium sulfate, 1.2 g of ytterbium sulfate was used in Example B2, and Example B3 was used. Then lanthanum sulfate was added to 1.
In Example B4, 1.4 g of erbium sulfate, in Example B5, 1.1 g of bismuth sulfate, in Example B6, 1.5 g of cerium sulfate, in Example B7, 1.3 g of praseodymium sulfate, and in Example B8, 1.3 Neodymium sulfate
g, in Example B9, 2.2 g of calcium sulfate was added. Otherwise, in the same manner as in Example B1, the surface of the hydrogen storage alloy electrode was coated with the first element made of cobalt Co and Ytterbium Yb, Lantern L
a, a coating layer containing erbium Er, bismuth Bi, cerium Ce, praseodymium Pr, neodymium Nd and one kind of second element selected from calcium Ca was formed.

Here, the weight ratio of each coating layer to the weight of the hydrogen storage alloy particles in each of the hydrogen storage alloy electrodes is 7% by weight, and the weight ratio of each of the coating layers to the weight of the hydrogen storage alloy particles is 7% by weight. The weight ratio of the second element is 0.7
Weight percent.

Then, in the same manner as in Example A1 except that the hydrogen storage alloy electrode on which each coating layer is formed as described above is used as the negative electrode, the battery capacity becomes about 1 Ah in the cylindrical shape. Each of the alkaline storage batteries of Examples B2 to B9 was manufactured.

Comparative Example a In Comparative Example a, the same compositional formula MmNi _3.2 Co _1.0 as in Example A1 was used.
Using a hydrogen storage alloy powder having an average particle diameter of 50 μm represented by Al _0.2 Mn _0.6 , and in the same manner as in Example A1, with respect to 100 parts by weight of the hydrogen storage alloy powder,
As a binder, 0.5 parts by weight of a styrene-methacrylic acid ester copolymer, 0.5 parts by weight of polyethylene oxide and a small amount of water were added, and these were mixed to prepare a paste. The collector was uniformly coated on both sides of a plated punched metal, dried, and then rolled to produce a hydrogen storage alloy electrode.

In Comparative Example a, when forming a coating layer on the surface of the hydrogen storage alloy electrode,
A coating layer made of nickel was formed on the surface of the hydrogen storage alloy electrode in the same manner as in Example A1 except that yttrium sulfate was not added to the plating solution used in Example A1. did.

The weight ratio of the coating layer to the weight of the hydrogen storage alloy particles in the hydrogen storage alloy electrode was 7% by weight.

Then, a hydrogen storage alloy electrode having a coating layer made of nickel on the surface is used for the negative electrode, and the other conditions are the same as in the case of the above-described Example A1, and the battery capacity is cylindrical. Was about 1 Ah, thereby producing an alkaline storage battery of Comparative Example a.

(Comparative Example b) In Comparative Example b, the same compositional formula MmNi _3.2 Co _1.0 as in Example A1 above.
Using a hydrogen storage alloy powder having an average particle diameter of 50 μm represented by Al _0.2 Mn _0.6 , and in the same manner as in Example A1, with respect to 100 parts by weight of the hydrogen storage alloy powder,
As a binder, 0.5 parts by weight of a styrene-methacrylic acid ester copolymer, 0.5 parts by weight of polyethylene oxide and a small amount of water were added, and these were mixed to prepare a paste. The collector was uniformly coated on both sides of a plated punched metal, dried, and then rolled to produce a hydrogen storage alloy electrode.

In Comparative Example b, when forming a coating layer on the surface of the hydrogen storage alloy electrode,
A coating layer made of cobalt was formed on the surface of the hydrogen storage alloy electrode in the same manner as in Example B1, except that yttrium sulfate was not added to the plating solution used in Example B1. did.

Here, the weight ratio of the coating layer to the weight of the hydrogen storage alloy particles in the hydrogen storage alloy electrode was 7% by weight.

Then, the hydrogen-absorbing alloy electrode having the coating layer made of cobalt formed on the surface is used as the negative electrode, and the other conditions are the same as in the case of the above-described Example A1, and the battery capacity is cylindrical. Was about 1 Ah to prepare an alkaline storage battery of Comparative Example b.

(Comparative Example c) In Comparative Example c, the same compositional formula MmNi _3.2 Co _1.0 as in Example A1 above.
Using a hydrogen storage alloy powder having an average particle diameter of 50 μm represented by Al _0.2 Mn _0.6 , and in the same manner as in Example A1, with respect to 100 parts by weight of the hydrogen storage alloy powder,
As a binder, 0.5 parts by weight of a styrene-methacrylic acid ester copolymer, 0.5 parts by weight of polyethylene oxide and a small amount of water were added, and these were mixed to prepare a paste. The collector was uniformly coated on both sides of a plated punched metal, dried, and then rolled to produce a hydrogen storage alloy electrode.

In Comparative Example c, no coating layer was provided on the surface of the above-mentioned hydrogen storage alloy electrode, and this hydrogen storage alloy electrode was used as it was as a negative electrode. A cylindrical alkaline storage battery of Comparative Example b3 having a battery capacity of about 1 Ah was produced in the same manner as in the case of A1.

Next, Examples A1 to A5 prepared as described above were used.
A9, each of the alkaline storage batteries of Examples B1 to B9 and Comparative Examples a, b, and c were charged at 100 mA for 16 hours under a temperature condition of 25 ° C., and then discharged to 1.0 V at 100 mA. As one cycle, 10
Each cycle of charge and discharge was repeated to activate the alkaline storage batteries of Examples A1 to A9, Examples B1 to B9, and Comparative Examples a, b, and c.

Next, Examples A1 to A9, Examples B1 to B9, and Comparative Examples a, b,
Each of the alkaline storage batteries of c was charged at 100 mA for 16 hours under a temperature condition of 25 ° C., and then charged at 1 A
, And the voltage of each alkaline storage battery at half the discharge time was determined as the operating voltage. The results are shown in Table 1 below.

Further, Examples A1 to A9, Examples B1 to B9, and Comparative Examples a, b, and c activated as described above.
Each of the alkaline storage batteries was charged at 2 A for 0.6 hours under a temperature condition of 25 ° C., then discharged at 2 A to 1.0 V, and this was repeated as one cycle. Was determined as the cycle life until it reached 60% of the initial capacity at the time of activation, and the results are shown in Table 1 below.

[0047]

[Table 1]

As is apparent from these results, a kind of the first element selected from nickel and cobalt on the surface and yttrium, ytterbium, lanthanum, erbium,
Examples A1 to A9 and Examples B1 to B9 using a hydrogen storage alloy electrode provided with a coating layer containing a second element selected from the group consisting of bismuth, cerium, praseodymium, neodymium and calcium as a negative electrode Comparative Examples a and b in which each alkaline storage battery used a hydrogen storage alloy electrode having a coating layer made of nickel or cobalt on its surface as a negative electrode.
The operating voltage was higher and the cycle life was remarkably improved as compared with the respective alkaline storage batteries of Comparative Example c and the alkaline storage battery of Comparative Example c using a hydrogen storage alloy electrode having no coating layer as the negative electrode. In particular, in the alkaline storage battery of Example A1 using nickel as the first element and yttrium as the second element in the coating layer, the operating voltage was further increased and the cycle life was improved.

(Examples A1.1 to A1.9) Example A
In 1.1 to A1.9, the first element made of nickel and the second element made of yttrium were formed by electroless plating on the surface of the hydrogen storage alloy electrode produced in the same manner as in Example A1. In forming the coating layer including the hydrogen absorbing alloy electrode, only the time during which the hydrogen storage alloy electrode was immersed in the plating solution used in Example A1 was changed.

When the hydrogen storage alloy electrode was immersed in the plating solution used in Example A1 as described above, the immersion time was 3 minutes 37 in Example A1.1.
Second, 4 minutes 04 seconds in Example A1.2, 4 minutes 31 seconds in Example A1.3, 13 minutes 33 seconds in Example A1.4, 22 minutes 35 seconds in Example A1.5, Example A1. 6 for 36
Minutes 08 seconds, Example A1.7: 45 minutes 10 seconds, Example A
In 1.8, 49 minutes 41 seconds, and in Example A1.9, 54 minutes 1
2 seconds.

The weight ratio of each coating layer to the weight of the hydrogen storage alloy particles was determined for each coating layer formed on the surface of the hydrogen storage alloy electrode as described above. In Example A1.1, 0.8% by weight, Example A1.2, 0.9% by weight, Example A1.3, 1% by weight, Example A1.4, 3% by weight, Example A1. 5, 5% by weight, 5% by weight in Example A1.6, 10% by weight in Example A1.7, Example A
1.8 at 11% by weight, Example A1.9 at 12% by weight
Had become.

Further, the weight of the second element made of yttrium in each of the above-mentioned coating layers was determined. 08% by weight, Example A
1.2 was 0.09% by weight, and Example A1.3 was 0.19% by weight.
% By weight, 0.3% by weight in Example A1.4, Example A
1.5 at 0.5% by weight, Example A1.6 at 0.8% by weight, Example A1.7 at 1.0% by weight, Example A1.
8 in Example 1.1, 1.2% by weight in Example A1.9
Had become.

The hydrogen absorbing alloy electrode formed with the above-mentioned respective coating layers containing the first element made of nickel and the second element made of yttrium was used as the negative electrode, except that it was used as the negative electrode. In the same manner as in the case, the alkaline storage batteries of Examples A1.1 to A1.9 each having a cylindrical shape and a battery capacity of about 1 Ah were produced.

Example A produced in this manner
With respect to each of the alkaline storage batteries of 1.1 to A1.9, the operating voltage and the cycle life of each of the alkaline storage batteries were determined in the same manner as in the case of the alkaline storage battery of Example A1, and the results are shown in Table 2 below. Was.

[0055]

[Table 2]

As a result, the weight ratio of the coating layer containing the first element made of nickel and the second element made of yttrium to the weight of the hydrogen storage alloy particles in the hydrogen storage alloy electrode was 1% by weight to 10% by weight. A in the range of
1. Each of the alkaline storage batteries of A1.3 to A1.7 has a weight ratio of the above-mentioned coating layer of less than 1% by weight.
The cycle life is longer than those of the alkaline storage batteries of A1 and A1.2, and the weight ratio of the coating layer is 1
The operating voltage was higher than those of the alkaline storage batteries of Examples A1.10 and A1.11 which exceeded 0% by weight.

In particular, in the alkaline storage batteries of Examples A1 and A1.5 to A1.7 in which the weight ratio of the coating layer to the weight of the hydrogen storage alloy particles was in the range of 5% by weight to 10% by weight, As the cycle life became longer, the operating voltage became higher.

(Examples A1.10 to A1.18) In Examples A1.10 to A1.18, the above-mentioned Example A1
Used in Example A1 above to form a coating layer containing a first element made of nickel and a second element made of yttrium by electroless plating on the surface of a hydrogen storage alloy electrode produced in the same manner as in the case of The amount of yttrium sulfate containing yttrium of the second element in the plating solution was changed, and the time during which the hydrogen storage alloy electrode was immersed in the plating solution was set at 45 minutes 10 as in the case of Example A1.7. Seconds.

Here, the amount of yttrium sulfate in one liter of the plating solution used in Example A1 was 0.84 g in Example A1.10.
11, 1.1 g in Example A1.12, 1.4 g in Example A1.13, 6.9 g in Example A1.14, 12 g in Example A1.15, Example A1.
The weight was 19 g in Example 16, 29 g in Example A1.17, and 44 g in Example A1.18.

When the amount of the second element yttrium in each coating layer formed on the surface of the hydrogen storage alloy electrode as described above was determined, the weight ratio of yttrium to the weight of the hydrogen storage alloy particles was as follows. As shown in Table 3, in Example A1.10, 0.3% by weight, Example A
0.41% by weight for 1.11 and 0.1% for Example A1.12.
5% by weight, 0.8% by weight in Example A1.13, 2% by weight in Example A1.14, 3% by weight in Example A1.15, 4% by weight in Example A1.16, Example A1. 17
Was 5% by weight, and Example A1.18 was 6% by weight.

Further, for each coating layer formed on the surface of the hydrogen storage alloy electrode as described above, the weight ratio of each coating layer to the weight of the hydrogen storage alloy particles was determined. 10% by weight.

The hydrogen absorbing alloy electrode on which each of the above-described coating layers containing the first element made of nickel and the second element made of yttrium was used as the negative electrode, except that the anode was used as the negative electrode. Similarly to the case, Examples A1.10 to A1.1 in which the battery capacity was about 1 Ah in a cylindrical shape.
8 were prepared.

Example A produced in this manner
For each alkaline storage battery of 1.10 to A1.18,
The operating voltage and the cycle life of each alkaline storage battery were determined in the same manner as in the case of the alkaline storage battery of Example A1, and the results are shown in Table 3 below.

[0064]

[Table 3]

As a result, Example A1.7 in which the weight ratio of the second element made of yttrium was in the range of 0.5% to 5% by weight with respect to the weight of the hydrogen storage alloy particles in the hydrogen storage alloy electrode. , A1.12 to A1.17, Examples A1.10 and A110 in which the weight ratio of the second element made of yttrium was less than 0.5% by weight.
The cycle life is longer than that of each alkaline storage battery of 1.11, and the operating voltage is higher than that of the alkaline storage battery of Example A1.18 in which the weight ratio of the second element made of yttrium exceeds 5% by weight. Had become.

The above Examples A1.1 to A1.18
Has described the case where a coating layer containing the first element made of nickel and the second element made of yttrium is formed on the surface of the hydrogen storage alloy electrode, but the case where cobalt is used as the first element, Similar results are obtained when an element selected from ytterbium, lanthanum, erbium, bismuth, cerium, praseodymium, neodymium and calcium is used.

[0067]

As described above in detail, in the hydrogen storage alloy electrode according to the present invention, the electrode material using the hydrogen storage alloy particles is selected from nickel and cobalt on the surface of the electrode attached to the current collector. A coating layer comprising at least one first element and at least one second element selected from the group consisting of yttrium, ytterbium, lanthanum, erbium, bismuth, cerium, praseodymium, neodymium and calcium. While the conductivity of the hydrogen storage alloy electrode is improved by the first element in the above, the hydrogen storage alloy in the hydrogen storage alloy electrode is oxidized by oxygen generated at the positive electrode during overcharging,
It was controlled by the second element in this coating layer.

As a result, when the above-mentioned hydrogen storage alloy electrode was used as a negative electrode of an alkaline storage battery, an alkaline storage battery having excellent high rate discharge characteristics and charge / discharge cycle characteristics was obtained.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of an alkaline storage battery manufactured in an example of the present invention and a comparative example.

[Explanation of symbols]

 1 positive electrode 2 negative electrode (hydrogen storage alloy electrode)

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tadayoshi Tanaka 2-5-5 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (72) Inventor Toshiyuki Noma 2 Keihanhondori, Moriguchi-shi, Osaka 5-5-5 Sanyo Electric Co., Ltd. (72) Inventor Ikuro Yonezu 2-5-5 Keihanhondori, Moriguchi-shi, Osaka F-term in Sanyo Electric Co., Ltd. 5H028 AA05 BB10 EE01 EE10 HH01 5H050 AA02 AA07 BA14 CA03 CB17 DA03 DA09 EA02 EA03 FA04 GA24 HA01

Claims (7)

[Claims] At least one first element selected from nickel and cobalt and yttrium, ytterbium, lanthanum, and erbium are provided on the surface of an electrode having an electrode material using hydrogen storage alloy particles attached to a current collector. A hydrogen-absorbing alloy electrode provided with a coating layer containing at least one second element selected from the group consisting of, bismuth, cerium, praseodymium, neodymium and calcium. 2. The hydrogen storage alloy electrode according to claim 1, wherein the coating layer is formed by plating. 3. The hydrogen storage alloy electrode according to claim 1, wherein the weight ratio of the coating layer to the weight of the hydrogen storage alloy particles in the electrode is 1% by weight to 1%.
The range is 0% by weight. 4. The hydrogen storage alloy electrode according to claim 1, wherein the weight ratio of the second element to the weight of the hydrogen storage alloy particles in the electrode is 0.5% by weight. -5% by weight. 5. The hydrogen storage alloy electrode according to claim 1, wherein the first element in the coating layer is nickel and the second element is yttrium. 6. At least one first element selected from nickel and cobalt, and at least one second element selected from the group consisting of yttrium, ytterbium, lanthanum, erbium, bismuth, cerium, praseodymium, neodymium and calcium. Using a plating solution containing
A method for producing a hydrogen storage alloy electrode, comprising: forming a coating layer by electroless plating on a surface of an electrode having an electrode material using hydrogen storage alloy particles adhered to a current collector. 7. An alkaline storage battery using the hydrogen storage alloy electrode according to claim 1 as a negative electrode.