JPS6016064B2 - Manufacturing method for storage battery cathode plates - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a cathode plate for a storage battery that generates electrical energy by an electrochemical reaction between oxygen and hydrogen stored in the cathode.

Conventional lead-acid batteries and nickel-cadmium batteries contain active materials in both electrode plates, are heavy and bulky, and therefore have a relatively low energy storage capacity per unit weight or volume. Therefore, as a storage battery with a large amount of energy storage per unit weight or volume, for example, La
Ni5 alloy, Ti-N of Japanese Patent Publication No. 49-25135
It has been proposed to use alloys that reversibly absorb and release hydrogen (hereinafter abbreviated as hydrogen storage/release alloys), such as i-based alloys, for the cathode plates of alkaline storage batteries. These mountains Ni5 alloy, Ti-Ni alloy or TIMn (
, -x) Mx (M is Ni, Co, Cu, Fe, etc.) based hydrogen storage/desorption alloys can store a large amount of hydrogen, and also contain hydrogen-activated metals (Ni, Co, Cu, Fe, etc.). ) in the form of alloys and can electrochemically absorb and release hydrogen. Therefore, when these alloys are used as cathode materials, the amount of energy stored per unit weight or volume can be relatively large. can.

However, although these alloys differ depending on the type, they generally do not activate hydrogen sufficiently during charging and discharging of storage batteries.
The polarization is large, and therefore the charging efficiency during high rate charging is lower than the charging efficiency during low rate charging.

Furthermore, since the voltage drop is large in high-rate discharge, it is not suitable for storage batteries that repeatedly discharge large currents over a relatively short period of time, such as starting storage batteries. The purpose of the present invention is to provide a cathode plate that eliminates the above-mentioned drawbacks, and the present invention is to provide a porous cathode plate for an alkaline storage battery made of a hydrogen storage/release alloy, in which a metal that activates hydrogen is used as a catalyst. By adding it, it is intended to increase the activity of hydrogen during charging and discharging and to enable high rate charging and discharging.

The cathode plate of the present invention is made of a porous molded body of a hydrogen storage/release alloy, and the surface thereof is coated with at least one of hydrogen-activating metals, such as platinum group metals such as palladium to platinum, or nickel and cobalt. is attached as a catalyst,
A large number of hydrogen activation points are formed.

By adopting the above-described configuration, the present invention activates hydrogen generated during charging to facilitate adsorption to the surface of the porous cathode plate and diffusion into the interior, allowing gas to permeate from outside the battery system at high current densities. do less.

Additionally, since hydrogen is activated in the same device during discharge, ionization is promoted on the surface of the porous cathode plate and electrochemical oxidation progresses rapidly. The difference in hydrogen concentration becomes large, and ``hydrogen moves quickly,''
Enables high current density discharge with small polarization. The method for manufacturing the cathode plate of the present invention involves forming a porous cathode plate using an alloy that reversibly absorbs and releases hydrogen, adding a catalytic metal salt that activates hydrogen to it, and placing it in a hydrogen stream. The method is characterized in that heat treatment is performed at the decomposition temperature of the salt to generate a catalyst metal, and then hydrogen occluded and adsorbed in the cathode plate and the catalyst metal is removed by vacuum treatment.

Note that the heat treatment performed in a hydrogen stream is performed to prevent the formation of oxides on the electrode alloy during the catalyst addition process and to activate the catalyst, and is performed during the process of depositing the catalyst on the electrode alloy. . In addition, vacuum treatment is performed to prevent the electrode alloy from oxidizing and deteriorating the activity of the catalyst when it comes into contact with air while the electrode alloy absorbs and absorbs hydrogen. It's for a reason. Examples thereof will be described below. Example 1 Commercially available high-purity metals such as lanthanum and nickel are melted in an arc furnace.
An alloy having the composition No. 5 was obtained, and this was ground in an argon atmosphere to form a powder with a diameter of 1 to 1. After molding and solidifying in a vacuum at a temperature of 9,000 to 100 psi for several hours, the adhesive was removed to obtain a porous alloy electrode molded body.

This alloy electrode molded body was impregnated with an aqueous solution of palladium chloride.

The amount of palladium chloride added was varied by changing the concentration of the aqueous solution so that it was equivalent to 1 to 40 9 Pd per electrode alloy. Next, after drying at about 100℃ to remove moisture, heat treatment is performed at a temperature of 30 to 400 degrees Celsius in a hydrogen stream for several hours, and the inside of the furnace is vacuumed (10-5 to 100 degrees Celsius).
0-6T) to remove hydrogen occluded and adsorbed in the alloy electrode, cooled to room temperature, and then taken out.

Figure 1 shows a storage battery manufactured to test the characteristics of the cathode plate of the present invention. 1 is a cathode plate made of the alloy manufactured by the above method, 2 is an anode plate made of nickel hydroxide, 3
4 is a separator made of nylon cloth, 4 is an electrolytic solution made of an aqueous solution of caustic potassium, 5 is a battery container, 61 is an anode terminal, and 7 is a cathode terminal.

The charge/discharge test was conducted at a current density of 255 to 7 per night for the electrode alloy.
5. Perform with loo (skin A), observe the state in which hydrogen gas is generated from the cathode during charging, and observe the generation of hydrogen gas from the cathode during discharging.
Discharge was performed until the potential compared with the standard electrode was -0.75 V, and the relationship between the elapsed discharge time and the potential was observed.
The amount of palladium catalyst added was 1, 2.5, 5, 10, 20 (9) of 3u40 per 1g of electrode alloy.

Among the charge and discharge tests, the charge test is approximately 9% compared to the discharge capacity.
The purpose is to investigate the current density of a charging current that does not generate gas until a charging capacity of approximately 0% is reached.

The results are as follows. When the palladium catalyst per electrode alloy is 1 of 9, it is 25 skin A2.5 p of 60 A, 75 mA of 5 female, 90 mA of 10 of 9, and 90 mA of 20 double 9. No gas was generated even when charged to nearly 100% at 100A.On the other hand, with a conventional cathode without a catalyst, gas was generated at about 70% charge at a current density of 50mA. It was estimated that the current density at which the cathode plate of the present invention can be charged at a higher current density than that of the conventional cathode plate is estimated to be about 40 A.Results of the discharge test. are as shown in Figure 2. In the figure, a is a conventional cathode without adding a catalyst, b, c, d, e
, f are the cathodes of the present invention in which 9 Pd catalysts were added, respectively: 1 p, 2.5 9, 5 9, 10, 20 m 9 to 40. It can be seen that by doing so, the polarization becomes smaller and the discharge capacity increases.This is because the conventional cathode plate has large polarization and reaches the end of discharge potential with dischargeable hydrogen remaining, whereas in the present invention hydrogen is activated by a catalyst,
This is because it is used efficiently. From the results of the above discharge test, it was confirmed that the appropriate amount of palladium catalyst to be added is 1 to 30 m9 per electrode alloy 1. In order to confirm the effect of vacuum treatment, 20 days of Pd catalyst was added to the electrode alloy, and after heat treatment in hydrogen atmosphere, it was cooled without vacuum treatment, and the inside of the furnace was filled with inert gas. When the test article was taken out into the air after being replaced, it generated some heat.

When a discharge test was conducted, the characteristics were as follows: Product C of the present invention, which was subjected to vacuum treatment with the addition of catalyst 5 of 9).
They were equivalent. This is thought to be due to residual hydrogen in the electrode alloy generating heat in the air, oxidizing a portion of the alloy, and deteriorating the activity of the catalyst. Example 2 A porous alloy electrode molded body of Ni5 alloy was produced in the same manner as in Example 1, and it was immersed in an ethanol solution of chloroplatinic acid to obtain a solution of 1 to 40 Pt per electrode alloy. After adding chloroplatinic acid, the same heat treatment and vacuum treatment as in Example 1 were performed.

The charging test was conducted in the same manner as in Example 1, and the charging current density at which no gas was generated for 90% charging was determined when the electrode alloy was 1gr.
When the platinum catalyst is 2.5 9, it is about 50 mA, 5 9
Approximately 60mA when , approximately 75mA when 9 of 10, 2
When it was 9 of 0, it was about 90 mA.

The results of the discharge test are shown in Figure 3. In the same figure, a is a conventional cathode without adding a catalyst, b, c, d
, e, f are platinum catalysts, 1, 9, 2.5, 9, and 5, respectively.
In the cathode of the present invention, the amount of platinum added is 9, 10 p, 20 to 40 o, and the amount of platinum added is 1 to 30 9, the same as the palladium catalyst.
was found to be appropriate. The reason why the polarization of Pd catalyst is smaller than that of platinum catalyst is because Pb has the property of activating hydrogen and occluding more hydrogen than platinum, which increases the hydrogen concentration on the surface of the porous electrode. Example 3 Using commercially available high-purity metals such as titanium, manganese, and copper, (
), and the condensation temperature is 800oo~850oo) TIMn
MC body. A porous alloy electrode molded body having the composition represented by No. 3 was prepared, and nickel nitrate corresponding to 5 to 150 nickel per electrode alloy was added by impregnating it with an aqueous solution of nickel nitrate.

Next, after drying at about 100 oo to remove moisture,
After reducing in a caustic potassium aqueous solution, washing with water, and drying, heat treatment and vacuum treatment were performed in the same manner as in Example 1, and a storage battery as shown in FIG. 1 was assembled. Figure 4 shows the discharge current at 50 m.
This is a graph showing the discharge characteristics when A/N is used, where a is a conventional cathode with no catalyst added, b, c, d, e, f, g are nickel catalysts of 5/9, 10/9, 25 claw 9. , 9 of 50,
In the alloy electrode of the present invention in which 75 twin 9 and 100 to 150 9 are added, it can be seen from the same figure that the appropriate amount of nickel catalyst to be added is in the range of 5 grade to 100 9.

The reason why there is no effect even when a large amount of catalyst (100 or more) is added is considered to be because the porous electrode alloy is clogged by the catalyst.

In addition, the results of a comparative test of heat treatment in a hydrogen atmosphere and vacuum treatment for dehydrogenation with those that were not performed.
It was confirmed that this method was as effective as Examples 1 and 2.

As described above, the porous cathode plate manufactured by the manufacturing method of the present invention can increase the current density of charging and discharging current. It has an excellent effect of being a storage battery that can be charged and discharged.

This is to prevent oxidation of the electrode alloy and increase the activity of the catalyst metal by performing heat treatment in a hydrogen stream in the step of adding a hydrogen-activated metal catalyst in the production method of the present invention, and to increase the activity of the catalyst metal. This effect is achieved by removing hydrogen occluded and adsorbed by the cathode plate and metal catalyst through vacuum treatment, thereby preventing oxidation of the electrode alloy and deterioration of the metal catalyst. In addition to palladium, platinum, and nickel shown in the examples, platinum such as ruthenium, osmium, iridium, and rhodium, platinum group metals other than palladium, or cobalt are similarly effective as catalysts; It is equally effective to use two or more types in combination.

[Brief explanation of the drawing]

Fig. 1: A cross-sectional view of a storage battery constructed for testing a storage battery cathode plate produced by the manufacturing method of the present invention, Fig. 2: A graph showing the discharge characteristics of the cathode plate of Example 1, Fig. 3: Example 2 FIG. 4 is a graph showing the discharge characteristics of the cathode plate of Example 3. 1... Cathode plate made of hydrogen storage/release alloy, 2.
... Anode plate, 3 ... Separator, 4 ...
...Electrolyte, 5...Battery container, 6...Anode terminal, 7...Cathode terminal. Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] 1. A porous cathode plate is formed from an alloy that reversibly absorbs and releases hydrogen, a catalytic metal salt that activates hydrogen is added to this, and this is placed in a hydrogen stream. A cathode of a storage battery, characterized in that heat treatment is performed at the decomposition temperature of the salt to generate a catalyst metal, and then hydrogen occluded and adsorbed in the cathode plate and the catalyst metal is removed by vacuum treatment. Method of manufacturing boards. 2. The catalyst metal consists of at least one kind of metal belonging to the platinum group, and the amount added is 1 g per 1 g of the cathode material.
The method for producing a cathode plate for a storage battery according to claim 1, wherein the amount is from mg to 30 mg. 3. The catalyst metal is at least one of nickel and cobalt, and the amount added is 5% per 1g of cathode material.
The method for producing a cathode plate for a storage battery according to claim 1, wherein the amount is from mg to 100 mg.