JP3216689B2 - Hydrogen storage alloy electrode and nickel-hydrogen storage battery - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method for reversibly storing and storing hydrogen.
The present invention relates to a hydrogen storage alloy electrode mainly composed of a hydrogen storage alloy to be released, and more particularly to a binder for holding the hydrogen storage alloy. This electrode is particularly suitable for use in nickel-metal hydride batteries in combination with nickel electrodes.

[0002]

2. Description of the Related Art Conventionally, as a binder for a hydrogen storage alloy electrode used in a nickel-hydrogen battery or the like, a cellulose derivative (methylcellulose, hydroxypropyl) used in a binder such as a cadmium electrode of a nickel-cadmium battery has been used. Methylcellulose, carboxymethylcellulose, etc.)
And a water-soluble polymer such as polyvinyl alcohol. However, the first problem with hydrogen storage alloy electrodes using these as a binder is that they have low flexibility,
Second, the hydrogen storage alloy powder and the hydrogen storage alloy powder, the binding property between the hydrogen storage alloy powder and the conductive support base is low, and among the above binders, polyvinyl alcohol is particularly preferred.
The third problem that gas permeability is inferior was mentioned. When the electrode having low flexibility, which is the first problem, is used particularly in a wound cylindrical battery, at the time of winding, peeling of the hydrogen storage alloy powder from the conductive support base, that is, removal of the hydrogen storage alloy powder from the electrode. Shedding occurs. In the battery wound in such a manner, the dropout is promoted by the expansion and contraction of the hydrogen storage alloy powder due to the repetition of the charge / discharge cycle, and the progress of the pulverization accompanying the expansion. If the hydrogen storage alloy falls off, the electrode capacity will be reduced, or the cycle life performance will be poor. In addition, the dropped powder moves to the positive electrode, conducts the positive electrode and the negative electrode, and may cause a short circuit. Generally, a resin having a low glass transition point (hereinafter, referred to as Tg) is very flexible in itself, and can be made flexible when integrated with powder. Resins having a low Tg generally include polyurethane resins and polyolefin resins. However, in a battery using an alkaline electrolyte such as a nickel-hydrogen battery, the resin itself is required to have alkali resistance. Polyurethane-based resins have low alkali resistance and are quickly decomposed when placed in an alkaline electrolyte. When an electrode having a low binding property of the hydrogen storage alloy powder, which is the second problem, is used, not only the drop of the hydrogen storage alloy powder when assembling the battery, but also the first charge / discharge cycle when the charge / discharge cycle is repeated. You will have the same problem as the problem. When an electrode with low gas absorption performance, which is the third problem, is used, in a sealed battery using a cathode absorption method, the absorption of oxygen gas from the positive electrode at the end of charging at the cathode cannot catch up with the generation, and the internal pressure of the battery increases. This causes the safety valve to operate. To solve these problems,
No. 84857 proposes a method for manufacturing an electrode plate having mechanical strength by using polyethylene oxide as a binder. This is because the addition amount of polyethylene oxide as a binder is 0.5% by weight or more and 2% by weight or less based on the hydrogen storage alloy, and the viscosity is 10,000 to 1%.
The slurry of the hydrogen storage alloy powder of 0.00000 mPa · s is held on a conductive support.

[0003]

The electrode manufactured by the technique disclosed in the above publication has sufficient flexibility until the packing density of the hydrogen-absorbing alloy powder reaches a certain value. When the value is increased, the flexibility rapidly decreases. Further, the gas absorbing performance cannot be improved with the conventional binder. In addition, since the above-described binder is originally a non-conductor, the presence of the binder itself hinders charging / discharging and becomes a factor of deteriorating high-rate discharge performance. A first object of the present invention is to provide a hydrogen storage alloy electrode having excellent gas absorption performance while maintaining sufficient flexibility and binding properties, and a nickel-hydrogen storage battery using the same. A second object of the present invention is to provide a hydrogen storage alloy electrode which achieves the first object and has improved high-rate discharge performance, and a nickel-hydrogen storage battery using the same.

[0004]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a hydrogen storage alloy electrode having a conductive support substrate holding a hydrogen storage alloy for reversibly storing and releasing hydrogen. Indispensable component of binder to fix powder,
It is characterized by using an ethylene-vinyl acetate resin having a glass transition point (Tg) of −10 ° C. or lower and an acrylic resin having a glass transition point (Tg) higher than 0 ° C. Ethylene-
The vinyl acetate resin is, for example, a copolymer of vinyl acetate, ethylene and acrylic, or a copolymer of vinyl acetate, ethylene and long-chain vinyl ester, and has a vinyl acetate content of 50% or more. Say. The acrylic resin is, for example, a resin obtained by copolymerizing acrylic acid, styrene, or the like with an alkyl acrylate as a main component, and having an alkyl acrylate content of 50% or more. Further, in addition to the essential binder, it is preferable to use one or more selected from a cellulose derivative, a polyethylene oxide, and a polyacrylate as the combined binder. Further, the addition amount of each of the above-mentioned ethylene-vinyl acetate resin and acrylic resin, which are essential binders, is set to 0.1% by weight or more and 1.0% by weight or less with respect to the weight of the hydrogen storage alloy in the electrode. It is more preferable that the total amount of the binder is 2% by weight or less based on the weight of the hydrogen storage alloy in the electrode. The first object described above can be achieved by manufacturing a battery using the hydrogen storage alloy electrode described above. Further, the above-mentioned second object can be achieved by producing a battery in which nickel powder is contained in the hydrogen-absorbing alloy electrode that has achieved the first object in an amount of 3% by weight or less based on the weight of the hydrogen-occluding alloy in the electrode. .

[0005]

The hydrogen storage alloy electrode according to the present invention can be used as an essential component of a binder such as an ethylene-vinyl acetate-acryl copolymer or an ethylene-vinyl acetate-long chain vinyl ester copolymer having a Tg of -10 ° C or less. An ethylene-vinyl acetate resin and an acrylic resin such as an acrylic acid-alkyl acrylate copolymer or an acrylic acid-styrene-alkyl acrylate copolymer having a Tg higher than 0 ° C are used. T
A resin having a low g has a very flexible film itself, and can be made flexible when integrated with powder. It also has a very strong binding force. Further, when an acrylic resin having a Tg higher than 0 ° C. is added to an ethylene-vinyl acetate resin having a Tg of −10 ° C. or less, the hydrogen storage alloy powder is further firmly bound together with the conductive support base. be able to. Also, Tg is 0
An acrylic resin having a temperature higher than ℃ has good oxygen gas permeability, and by adding this to an ethylene-vinyl acetate resin, the electrode is more excellent in gas absorption performance than when ethylene-vinyl acetate resin is used alone. Is obtained. Further, even if any of the conventional binders are used in combination with the above binder, the above-described effects can be obtained.However, methyl cellulose, cellulose derivatives such as hydroxypropylmethyl cellulose, polyethylene oxide, and polyacrylate are particularly used. The best battery performance. It is considered that the gas permeability can be further imparted by combining these binders. It is considered that this makes it easier for the negative electrode to absorb oxygen gas generated from the positive electrode when the battery is overcharged. The binder is essentially an unnecessary substance in the charge / discharge reaction, and the smaller the amount added, the better. The same applies to the ethylene-vinyl acetate-based resin and the acrylic resin used in the present invention, but from the results of the experiments described later, the amount of the ethylene-vinyl acetate-based resin or the acrylic resin added to the weight of the hydrogen storage alloy in the electrode. On the other hand, the amount is preferably 0.1% by weight or more and 1.0% by weight or less, and more preferably the total amount of the binder is 2% by weight or less. When these binders are used, significant improvements in electrode flexibility, binding properties, and internal pressure characteristics of the battery are seen, but since the binder itself is a non-conductor, the conductivity inside the electrodes is somewhat It has to be inferior. Therefore, by simultaneously adding the binder and the nickel powder, the conductivity can be improved, and an electrode having excellent high-rate discharge characteristics can be obtained.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A hydrogen storage alloy electrode according to the present invention will be described in detail below by taking a cylindrical sealed nickel-hydrogen storage battery as an example. Table 1 shows binders used in Examples and Comparative Examples described below. Hereinafter, each binder is abbreviated as shown in Table 1.

[0007]

[Table 1]

(Experiment 1) First, the fact that the hydrogen storage alloy electrode using the binder according to the present invention is superior to the hydrogen storage alloy electrode using another binder will be specifically described below. I do. Examples 1 to 4 and Comparative Examples 1 to 3 Hydrogen storage alloy electrodes were produced as follows. For hydrogen storage alloy, Mm (Misch metal) mainly composed of lanthanum
A Ni alloy to which Co, Al, and Mn were added in predetermined amounts was used. The hydrogen storage alloy was heated and melted by arc melting each of the above-mentioned samples, and then was subjected to a particle size of 100 using a ball mill.
It was obtained by mechanical pulverization to a fine powder of about μm. A (Tg: an essential binder of the present invention) is added to this hydrogen storage alloy.
−30 ° C.) and C (Tg: 2 ° C.) so as to be 0.25% by weight with respect to the hydrogen storage alloy, and the combined binder E so as to be 0.5% by weight with respect to the hydrogen storage alloy. Add,
A slurry having a viscosity of about 20,000 mPa · s was produced.
At this time, A and C used an emulsion solution in which a resin was dispersed in water. The slurry was applied to both sides of a 60 μm-thick conductive support substrate by a doctor blade method, dried, and pressed to a predetermined thickness to produce an electrode. At this time, the packing density of the hydrogen storage alloy electrode was 5.0.
g / cm ³ . This is the electrode of Example 1. The hydrogen storage alloy electrodes of Examples 2 to 4 and Comparative Examples 1 to 3 having the compositions shown in Table 2 using the binder were prepared in the same manner as described above. In order to evaluate the flexibility of the hydrogen storage alloy electrode prepared as described above, a diameter of the hydrogen storage alloy electrode was 3 m.
After being wound around the shaft of m, the film was rewound and the falling rate of the hydrogen storage alloy (rolling falling rate) at that time was measured. The wound dropout rate was a value obtained by subtracting the electrode weight after the winding test from the electrode weight before the winding test and dividing the value by the electrode weight before the test. Table 2 shows the wound dropout rates of the electrodes of Examples 1 to 4 and Comparative Examples 1 to 3 together with the packing density.

[0009]

[Table 2]

As is clear from Table 2, the electrode of Comparative Example 1 using G alone, which is a conventional binder, has a binding capacity but a low flexibility, so that the electrode has a high capacity (high density). In the case of the above), dropping still occurs. In addition, the electrodes of Comparative Examples 2 and 3, in which I and J were used alone, immediately peeled off and dropped off due to low binding properties between the hydrogen storage alloys and between the hydrogen storage alloy and the conductive support base. . On the other hand, the electrodes of Examples 1 to 4 according to the present invention are very excellent not only in binding force but also in flexibility, and thus are less likely to fall off even when filled with high density than the electrodes of Comparative Examples. Next, using a nickel electrode having a theoretical capacity of 1000 mAh and a nylon non-woven fabric separator using nickel hydroxide as an active material and an active material prepared by a conventional method together with the hydrogen storage alloy electrode, the outermost periphery is wound so as to be a hydrogen storage alloy electrode. did. After inserting this electrode group into a cylindrical battery container, a 31% by weight aqueous solution of potassium hydroxide was injected to produce a sealed positive-type nickel-hydrogen storage battery having a theoretical capacity of 1000 mAh. The cycle life characteristics of the produced storage batteries were evaluated. The evaluation is performed by repeatedly performing charge and discharge after performing an activation process by a conventional method.
Charging is performed at a current of 1000 mA at an ambient temperature of 20 ° C., and ends when the battery voltage drop (−ΔV) reaches 10 mV. Discharging is performed at a current of 1000 mA, and ends when the battery voltage reaches 1.0 V. FIG. 1 shows the results of the cycle life test. Batteries using the electrodes of Comparative Examples 2 and 3 using the conventional binders I and J alone, as shown in the above-mentioned winding-off rate, have low electrode flexibility, and Since the binding force of the agent is weak, peeling or falling off of the hydrogen storage alloy occurs during winding. Therefore, the hydrogen storage alloy is miniaturized due to repetition of charge and discharge, and peels off and falls off from the conductive support base due to gas generation, which indicates that the life is extremely short. Further, the battery using the electrode of Comparative Example 1 to which G was solely added exhibited better characteristics than Comparative Examples 2 and 3 due to the strong binding force, but the internal pressure increased with the progress of the charge / discharge cycle. As a result, the electrolyte solution was released outside the system, and the capacity was rapidly deteriorated. This is considered to be one of the causes of a shortage of charge reserve due to a decrease in electrode capacity due to the drop of the hydrogen storage alloy during winding. Another cause is considered to be that G covers the surface of the hydrogen storage alloy with a film having poor gas permeability. It is considered that the above-mentioned increase in the internal pressure occurred in any of these cases because the capacity of absorbing oxygen gas generated from the positive electrode was reduced during charging. On the other hand, the batteries using the electrodes of Examples 1 to 4 according to the present invention have 100% flexibility due to the flexibility of the electrodes, the excellent binding force of the binder and the excellent gas permeability.
In the cycle life test up to 0 cycles, only a slight decrease in capacity was observed. In Examples 1 to 4, the combined binder was used. However, even when only the essential binder was used, almost the same results were obtained. However, the case where the combined binder was used in addition to the essential binder was advantageous in that the increase in the internal pressure of the battery could be further suppressed.

(Experiment 2) Next, the influence of the difference in Tg of the ethylene-vinyl acetate resin and the acrylic resin, which are essential binders, was examined. Experiment 1, Experiment 2 and Experiment 3 described later
The Tg of the ethylene-vinyl acetate resin used in Nos. 5 to 5 was used by changing the ethylene content. Similarly, the acrylic resin C used in Experiments 1 and 2 and Experiments 3 to 5 described below has a Tg of 10 ° C. (showa polymer
Tg = 2 ° C. (Polysol AP-4660, manufactured by Showa Polymer Co., Ltd.), Tg = −1
0 ° C (Toricle S-161W manufactured by Toyo Ink Mfg. Co., Ltd.)
Was used. Examples 2, 5 to 8 and Comparative Examples 4 to 6 Each of the essential binders B and C was 0.25% by weight based on the weight of the hydrogen storage alloy, and the combined binder E was added to the weight of the hydrogen storage alloy. A hydrogen storage alloy electrode was prepared in the same manner as in Example 1 except that the amount was 0.5% by weight. In Table 3, the binders used for the electrodes of Examples 2, 5 to 8, and Comparative Examples 4 to 6 are indicated by ○. Using these electrodes, the measurement of the winding drop-off rate and the internal pressure characteristics of the battery were evaluated in the same manner as in Experiment 1. The conditions for producing the battery and the method of measuring the wound dropout rate are the same as those described in Experiment 1. In the internal pressure characteristic test, a 1 mm hole was formed in the bottom of the can of each battery, and a pressure sensor was installed. Each battery was charged at 1 CmA for 90 minutes (150% charge), and the internal pressure of each battery was measured. Table 3 shows the test results of the unrolling rate and the internal pressure characteristics. As is clear from Table 3, Examples 2, 5 to 8 in which the Tg of B is −10 ° C. or less and the Tg of C is larger than 0 ° C.
Also, it is understood that the internal pressure characteristics are excellent. Comparative Examples 4 and 5 are excellent in internal pressure characteristics because C is partially substituted for B, but the use of B having a Tg higher than −10 ° C. results in an increased wound dropout rate. Comparative Example 6
Although B having a Tg of −30 ° C. was used, C having a Tg of 0 ° C. or less was used, so that the wound drop-off rate was excellent, but the internal pressure characteristics were significantly reduced. This is because the lower the Tg, the more flexible and resilient the binder is, so that the flexibility of the electrode is improved, but a film having poor gas permeability is formed,
It is considered that the internal pressure characteristics decreased. Therefore, Tg which is excellent in gas permeability is -10 at C larger than 0 ° C.
It can be seen that by partially substituting B at a temperature of not more than 0 ° C., an electrode having a reduced rate of wound drop and excellent internal pressure characteristics can be obtained.

[0012]

[Table 3]

Here, B is used for the ethylene-vinyl acetate resin, which is an essential binder, and C is used for the acrylic resin, but the same applies when Tg is changed using A and D within the scope of the present invention. Was the effect. Although E was used as the combined binder, other cellulose derivatives such as F and J and G and H were also used.
The same effect was obtained in the case of using or the use of one or more of the above binders. The same result was obtained for C other than those used in this experiment if Tg was higher than 0 ° C.

(Experiment 3) The effect of the type of combined binder added simultaneously with the essential binder on the electrode characteristics was examined. Examples 2, 9 to 13 As essential binders, B (Tg: −30 ° C.), C (Tg:
2 ° C.), and with respect to the weight of the hydrogen-absorbing alloy, each is 0.1%.
25% by weight, and the binders shown in Table 4 were used in combination with the hydrogen storage alloys shown in Table 4 as weight percentages.
The hydrogen storage alloy electrode was produced in the same manner as in Example 1 except for the above. Using these electrodes, the measurement of the rate of winding-off and the cycle life characteristics of the battery were evaluated in the same manner as in Experiment 1. The conditions for producing the battery and the test method are the same as those described in Experiment 1. Table 4 shows the test results of the winding dropout rate.
Shown in As in Examples 2 and 9 to 13, when an ethylene-vinyl acetate resin and an acrylic resin are used as essential components of the binder, any conventional binder can be used as the binder to be used in combination. The rate of falling off by winding was lower than that obtained by using the conventional binder alone. In particular, it can be seen that when cellulose derivatives F, E and J, and G and H are used as the combined binder, more excellent properties are obtained than when I is used.

[0015]

[Table 4]

FIG. 2 shows the results of the cycle life test. For comparison, the results of the cycle life test of the battery of Comparative Example 1 are also shown. As can be seen from FIG. 2, in each of the examples, the cycle life characteristics were better than that of Comparative Example 1 because the binder having both excellent binding force and gas permeability was used. In the cycle life test up to the cycle, only a slight decrease in capacity was observed. However,
In Example 12, since the hydrogen storage alloy fell off during winding,
The cycle characteristics were somewhat inferior to the batteries of the other examples.
As described above, when the ethylene-vinyl acetate resin and the acrylic resin are used as the essential components of the binder, the conventional binder is used alone regardless of which conventional binder is used as the combined binder. The effect is obtained more than that used in the above. However, when F, E, J, G, and H were used as the combined binder, it was found that more excellent characteristics were obtained. Here, B (Tg: −30 ° C.) is added to the ethylene-vinyl acetate resin as an essential binder.
Used C (Tg: 2 ° C.) as an acrylic resin, but other than those, B or A, Tg: Tg: −10 ° C. or less
Similar effects were obtained when C or D higher than 0 ° C. was used. In this experiment, E, F, G, H, and J were used alone, but the same effect was obtained by using one or more of them.

(Experiment 4) Next, the influence on the electrode characteristics of the addition amount of the ethylene-vinyl acetate resin and the acrylic resin, which are essential binders, and the total amount of the binders including the combined binders was examined. Examples 2, 14 to 28 The essential binders and the combined binders were used at the weight percentages shown in Tables 5 and 6 with respect to the hydrogen storage alloy, and the others were the same as in Examples 1 and 2 as in Example 1. To 28 hydrogen storage alloy electrodes were produced. Using these electrodes, the measurement of the winding drop-off rate was performed as in Experiment 1, and the internal pressure characteristics of the battery were evaluated as in Experiment 2.
The production and test of the battery were performed under the same conditions as in Experiments 1 and 2.

[0018]

[Table 5]

[0019]

[Table 6]

Tables 5 and 6 show the test results of the falling-off rate of the wound and the internal pressure characteristics. As can be seen from Tables 5 and 6, the electrodes (0.05) of Examples 22 and 23 in which the added amount of B or C as an essential binder was less than 0.1% by weight.
% By weight) is advantageous in terms of battery internal pressure characteristics, but the amount of falling off is slightly increased due to a decrease in binding force. In addition, the addition amount of B, which is an essential binder, or the addition amount of C is 1.0% by weight.
In Examples 16 and 19, which are larger than the above, the internal pressure of the battery is slightly higher. In the case of Example 16, the B film having poor gas permeability is excessively present, and in the case of Example 19, even the C film having excellent gas permeability is present excessively, so that the internal pressure of the battery is reduced. Is considered to be slightly higher. The electrodes of Examples 26, 27, and 28 in which the total amount of the binder was more than 2.0% by weight had a low wound dropout rate due to the large amount of the binder, but the hydrogen storage alloy Is excessively covered with the film, and thus the internal pressure of the battery is slightly increased. It is also disadvantageous in increasing the electrode packing density. B and C, which are essential binders, are added in an amount of 0.1% by weight or more and 1.0% or more.
Examples 2, 14, 15, 17, 18, 20, 21, and 2 in which the total amount of the binder was 2% by weight or less.
Nos. 4 and 25 have low dropout during winding while maintaining a high packing density, and are more preferable in improving the internal pressure characteristics. Here, B (Tg: −30 ° C.) was used for the ethylene-vinyl acetate resin, which is an essential binder, and C (Tg: 2 ° C.), was used for the acrylic resin.
The same effect was obtained when using B or A with g: -10 ° C or lower and C or D with Tg higher than 0 ° C. Although E was used as the combined binder, the same effect was obtained when other cellulose derivatives such as F and J and G and H were used, or when one or more of the combined binders were used. was gotten.

(Experiment 5) Next, the effect of the type and amount of the conductive material on the battery characteristics was examined. Examples 29 to 37 Various nickel powders were added to the hydrogen storage alloy at the weight percentages shown in Table 7, and the other conditions were the same as in Example 1 to produce hydrogen storage alloy electrodes. Ni1 shown in Table 7 is nickel powder in the form of a chain of spheres having spiky projections, Ni2
Is a spherical nickel powder having spike-like protrusions, and Ni3 is a filament-like ultrafine powder. Further, the packing density shown in Table 7 indicates the weight per unit volume of the hydrogen storage alloy in the electrode. For the batteries fabricated using these electrodes, the measurement of the rate of winding-off and the high-rate discharge characteristics of the batteries and the internal pressure characteristics of the batteries were evaluated as in Experiment 2, as in Experiment 1. In the high rate discharge characteristic test of the battery, after charging was performed at a current of 1 CmA for 90 minutes, 0.2 CmA, 1.0 CmA, and 3.
The battery was discharged at a discharge rate of 0 CmA until the battery voltage reached 1.0 V. For comparison, a high-rate discharge characteristic test of Example 1 in which no nickel powder was added was also performed. 1.0 CmA discharge capacity / 0.2 CmA discharge capacity (hereinafter referred to as 1.0 C / 0.
The results of 3.0 CmA discharge capacity / 0.2 CmA discharge capacity (hereinafter referred to as 3.0 C / 0.2 C) are shown in Table 7. As is evident from Table 7, no matter which shape of the nickel powder was used, if the addition amount was 3% by weight or less, the high-rate discharge characteristics better than those of Example 1 in which the nickel powder was not added were exhibited. However, when the addition amount exceeded 3% by weight, a decrease in high-rate discharge characteristics was observed. This is considered to be due to the fact that when the amount of addition exceeds 3% by weight, the rate of falling off the winding is slightly increased. In other words, if the nickel powder is originally in the form of a spike or a filament, it plays a role of a wedge in the binder layer between the particles, thereby compensating for a decrease in the binding force or as a non-conductive binder. It is believed that the layers also act as conductive networks. However, when the amount exceeds a certain amount, it is considered that a large amount is present between the binder and the layer between the core material and the alloy, and the binding property is weakened, or the peeling-off and falling off of the binder cause the deterioration of the high-rate discharge characteristics. . Further, if the addition amount exceeds 3% by weight, it is disadvantageous in that the packing density is reduced. Further, as shown in Table 7, the addition of the nickel powder did not affect the internal pressure of the battery, and all the examples exhibited good characteristics. From the above, there is no influence by the type of the nickel powder used, but it is preferable that the addition amount is 3% by weight or less based on the weight of the hydrogen storage alloy. Here, A (Tg: −30 ° C.) was used for the ethylene-vinyl acetate resin, which is an essential binder, and C (Tg: 2 ° C.), for the acrylic resin. The same effect was obtained when B or A at a temperature of 0 ° C. or lower and C or D at a temperature higher than 0 ° C. were used.
Although E was used as the combined binder, the same effect was obtained when other cellulose derivatives such as F and J and G and H were used, or when one or more of the combined binders were used. was gotten.

[0022]

[Table 7]

In the above embodiment, the cylindrical closed nickel-
Although only the hydrogen storage battery has been described, any other battery using a hydrogen storage alloy electrode can be applied to other shapes and other battery systems.

The C used in Experiments 1 to 5 used the reagent described above.
Similar results are obtained if the temperature is higher than ° C.

[0025]

As described above, according to the present invention, it is possible to provide a hydrogen storage alloy electrode having excellent gas absorption performance while maintaining sufficient flexibility and binding properties, and a nickel-hydrogen storage battery using the same. Could be provided. In addition, a hydrogen storage alloy electrode with improved high rate discharge performance and a nickel-hydrogen storage battery using the same can be provided.

[Brief description of the drawings]

FIG. 1 is a diagram showing cycle life characteristics of a battery using a hydrogen storage alloy electrode according to Examples 1, 2, 3, and 4, and batteries of Comparative Examples 1, 2, and 3.

FIG. 2 is a diagram showing cycle life characteristics of a battery using a hydrogen storage alloy electrode according to Examples 2, 9, 10, 11, 12, and 13 and a battery of Comparative Example 1.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01M 4/24-4/26 H01M 4/62

Claims (8)

(57) [Claims] In a hydrogen storage alloy electrode in which a hydrogen storage alloy that reversibly stores and releases hydrogen is held on a conductive support base, an essential component of a binder for fixing the alloy powder is a glass transition point ( A hydrogen storage alloy electrode using an ethylene-vinyl acetate resin having a glass transition point (Tg) higher than 0 ° C. and an ethylene-vinyl acetate resin having a glass transition point (Tg) of −10 ° C. or lower. 2. The hydrogen storage according to claim 1, wherein the ethylene-vinyl acetate resin is selected from an ethylene-vinyl acetate-acryl copolymer and an ethylene-vinyl acetate-long chain vinyl ester copolymer. Alloy electrode. 3. The hydrogen storage alloy electrode according to claim 1, wherein the acrylic resin is selected from an acrylic acid-alkyl acrylate copolymer and an acrylic acid-styrene-alkyl acrylate copolymer. 4. The method according to claim 1, wherein at least one selected from the group consisting of cellulose derivatives, polyethylene oxides and polyacrylates is used simultaneously with the ethylene-vinyl acetate resin and the acrylic resin. 4. The hydrogen storage alloy electrode according to any one of 3. 5. The method according to claim 1, wherein the amounts of the ethylene-vinyl acetate resin and the acrylic resin are each 0.1% by weight or more and 1.0% by weight or less based on the weight of the hydrogen storage alloy in the electrode. Item 5. A hydrogen storage alloy electrode according to any one of Items 1 to 4. 6. The hydrogen storage alloy electrode according to claim 1, wherein the total amount of the binder is 2% by weight or less based on the weight of the hydrogen storage alloy in the electrode. 7. The hydrogen storage alloy electrode according to claim 1, wherein the hydrogen storage alloy electrode contains 3% by weight or less of nickel powder based on the weight of the hydrogen storage alloy in the electrode. . 8. A nickel alloy comprising an electrode group having a separator interposed between a nickel electrode and a hydrogen storage alloy electrode.
2. The hydrogen storage battery according to claim 1, wherein the hydrogen storage alloy electrode is provided.
8. A nickel-hydrogen storage battery, which is the hydrogen storage alloy electrode according to any one of claims 7 to 7.