JP3287215B2 - Manufacturing method of nickel positive plate for alkaline storage battery - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a nickel positive electrode plate used for a nickel-cadmium storage battery or the like.

[0002]

2. Description of the Related Art Conventionally, a method for producing a nickel positive electrode for an alkaline storage battery has mainly been a method in which a porous substrate impregnated with nickel salts in micropores is subjected to negative electrolysis in an alkaline solution, or an alkaline solution without negative electrolysis. A chemical impregnation method, a thermal decomposition method, an electrolytic deposition method, and the like, in which nickel hydroxide is converted into nickel hydroxide, are known.

As the use of batteries has been expanded, miniaturization and higher performance have been required, and heat-consumption energy, less power, high utilization of active materials, and high-capacity density nickel positive plates are manufactured at low cost. There is a long-awaited method. Therefore, the majority of the required nickel hydroxide is filled by the electrolytic deposition method, and subsequently, by the chemical impregnation method,
A method has been proposed in which a nickel hydroxide positive electrode having a high capacity density and a high active material utilization rate is obtained at a low cost by filling the remaining nickel hydroxide.
No. 1865).

[0004] Further, with the miniaturization of equipment using an alkaline storage battery as a power supply, there has been a demand for a smaller and higher capacity density battery as a power supply. Therefore, by forming a layer mainly composed of cobalt hydroxide or cobalt oxide in a sandwich structure between two layers mainly composed of nickel hydroxide obtained by the chemical impregnation method, the utilization rate of the active material is improved. A method of improving the discharge potential characteristics of a battery has also been proposed (Japanese Patent Publication No. 6-77452).

[0005] Nickel-cadmium storage batteries and nickel-hydrogen storage batteries using such a nickel positive electrode charge and discharge at an appropriate current value at room temperature. Even with a nickel positive electrode plate filled with nickel hydroxide at a constant weight ratio by the impregnation method, its function has been exhibited without any problem.

[0006]

Recently, however, the use of batteries and the miniaturization of equipment have been advanced, and for example, backup batteries for storage of electromotive force of solar cells, and batteries for driving equipment installed outdoors have been developed. , Not only high capacity but also high reliability for a long time, that is, long life has been required. Then, when the durability test specified in JIS C 8705 7, 3, 9 was performed on the above battery at a high temperature, it was found that the conductivity on the positive electrode side was reduced. Due to this decrease in conductivity, the polarization on the positive electrode side increased, leading to an early decrease in battery capacity.

[0007] Further, even in a method of forming a layer mainly containing cobalt hydroxide or cobalt oxide in a sandwich structure between two layers mainly containing nickel hydroxide, the two layers are formed. The method of producing nickel hydroxide is a chemical impregnation method, which limits the amount of active material filling the micropores of the substrate from the manufacturing method, making it difficult to obtain a high capacity density electrode plate. However, it has a problem that its utilization factor is lower than that of nickel hydroxide obtained by the electrolytic deposition method, and it has been difficult to secure conductivity for a long period of time and keep the discharge capacity at a certain value or more.

[0008]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention relates to a sintered nickel substrate or the like obtained by adding cobalt to a paste applied to a core material such as a punching metal and performing sintering. The porous metal substrate is filled with a part of nickel hydroxide as an active material by an electrolytic deposition method, and then a cobalt oxide layer is formed by a chemical impregnation method. Is filled with a mixed solution of nickel nitrate and cobalt nitrate by a chemical impregnation method.

In this case, the amount of nickel hydroxide charged is about 30% by weight of the total amount of the required active material obtained by the electrolytic deposition method, and about 70% of the required amount of the active material obtained by the chemical impregnation method.
% By weight.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The invention according to claim 1 of the present invention is characterized in that a cobalt oxide such as cobalt oxide is added to a paste to be applied to a core material such as a patting metal, and sintering is performed. A substrate is prepared, a part of nickel hydroxide required by an electrolytic deposition method is filled, then a cobalt oxide layer is formed by a chemical impregnation method, and then a majority of the required total amount is formed by a chemical impregnation method. Of nickel hydroxide is filled with a mixed solution of nickel nitrate and cobalt nitrate. The nickel hydroxide obtained by the chemical impregnation method is larger in particle size than that by the electrolytic deposition method,
Because of its large volume and thickness, the electrolyte can be moved and diffused well inside the electrode plate, and the amount of electrolyte is small and the electrolyte can reach the filled active material deep inside the electrode plate for a long time It is possible to solve the problem that it is difficult to solve the problem and use the high packing density by partially filling the core material and the active material, and improving the conductive network of the active material and the active material, and partially filling nickel hydroxide obtained by electrolytic deposition. As a result, a nickel positive electrode plate having a high capacity density, a high utilization rate of the amount of active material, and a long life at high temperatures can be obtained.

[0011]

Next, specific examples of the present invention will be described. A nickel powder and a cobalt oxide powder are mixed at a weight ratio of 90:10, kneaded sufficiently with an ethylene glycol solution of methylcellulose, and a paste is applied to a perforated steel sheet and dried. Then, a sintered nickel substrate having a porosity of 80% was produced. Using this substrate, as an electrolytic solution in the electrolytic deposition method, a concentration of 3.5 mol / l and a pH of 2.0
Of nickel nitrate solution, and immersion was performed at a solution temperature of 80 ° C., and electrolytic deposition was performed using this as a cathode. The filling amount of nickel nitrate by electrolytic deposition was about 30% by weight of the required total amount in terms of nickel hydroxide after conversion with an aqueous alkali solution. Thereafter, the filled substrate is dried. Subsequently, the substrate is immersed in an aqueous solution of cobalt nitrate having a concentration of 3.0 mol / l, pH 1.5, and a liquid temperature of 80 ° C., and impregnated with cobalt nitrate. After drying, a concentration of 4.0 mol /
1, immersed in an aqueous solution of caustic soda at a liquid temperature of 60 ° C., and subsequently washed with water. Thereafter, the concentration is 3.0 mol / l.
Of a mixed solution of nickel nitrate and cobalt nitrate having a concentration of 0.05 mol / l was immersed in the mixture at a liquid temperature of 80 ° C., and then dried to obtain a concentration of 4.0 mol / l and a liquid temperature of 60 mol / l. It was immersed in an aqueous solution of caustic soda at ℃ to convert nickel nitrate and cobalt nitrate into nickel hydroxide and cobalt hydroxide, respectively, and then washed with water. Furthermore, chemical impregnation of this nickel salt and cobalt salt, alkali immersion,
Repeat the series of washing steps several times to reduce the total
Weight percent nickel hydroxide was charged. The substrate after the filling of the active material was cut into a size of 35 × 150 mm to produce a nickel positive electrode plate a according to the embodiment of the present invention. Using this positive electrode plate in combination with a known cadmium negative electrode, a nominal capacity of 700 m
Ah size A sealed nickel-cadmium storage battery A
Was prepared. As a comparative example, a nickel-sintered substrate to which cobalt was added in the same manner as in the above example was used, and nickel hydroxide equivalent to a required total amount of 70% by weight was filled by an electrolytic deposition method. A positive electrode plate prepared by immersion in a mixed solution of (1) and filling with the remaining 30% by weight of nickel hydroxide was used as a nickel positive electrode plate b according to a comparative example, and an A-size sealed nickel-cadmium storage battery was prepared in the same manner as in the example. Then, a battery B according to a comparative example was obtained. Also,
After filling about 60% by weight of the total active material amount by the chemical impregnation method, impregnation with cobalt nitrate is performed, and the remaining about 40% by weight of nickel hydroxide is also filled into the sintered substrate to which cobalt is added by the chemical impregnation method. The sealed electrode plate was used as a comparative example c, and a sealed nickel-cadmium storage battery was formed in the same manner as in the example, thereby obtaining a battery C according to the comparative example. Then, only the nickel powder was kneaded with an ethylene glycol solution of methylcellulose to form a paste, which was then applied to a perforated steel plate, dried, and sintered to produce a nickel sintered substrate. After filling nickel hydroxide equivalent to about 30% by weight of the required total amount by the analysis method, impregnation with cobalt nitrate is performed, and the remaining about 70% by weight of nickel hydroxide is added to a mixed solution of nickel nitrate and cobalt nitrate. The positive electrode plate prepared by immersion and filling was used as a nickel positive electrode plate d according to a comparative example.
The battery D according to the comparative example was obtained. Further, the electrode plate was filled by 70% by weight of the required amount of the active material by the electrolytic deposition method, and 30% by weight of the required amount of the active material by the chemical impregnation method. Using the nickel positive electrode plate as e, a battery E according to a comparative example was obtained. And
The chemical impregnation of the cobalt nitrate solution was carried out in the same manner as in the example, and the remaining 70% by weight of nickel hydroxide was filled with a 3.0 mol / l nickel nitrate aqueous solution at a liquid temperature of 8%.
After immersion in this at 0 ° C., drying was carried out and the concentration was 4.
It was immersed in an aqueous solution of caustic soda at 0 mol / l and a liquid temperature of 60 ° C., and after converting nickel nitrate to nickel hydroxide, a water washing treatment was performed. Further, a series of steps of chemical impregnation of this nickel salt, alkali immersion, and washing with water was repeated a plurality of times, and an electrode plate filled with about 70% by weight of nickel hydroxide of a required total amount was designated as Comparative Example f, and a battery F according to Comparative Example was obtained. Was.

Each of the batteries A, B, C, D, E and F was charged at a constant temperature of 20 ° C. and at a constant temperature of 20 ° C. for 15 hours at 0.1 C, and discharged at 0.2 C to a final voltage of 1.0 V. The charging and discharging were performed in a mode in which one cycle was performed, and the battery characteristics were evaluated based on the discharge capacity in the second cycle. The results are shown in (Table 1).

[0013]

[Table 1]

As apparent from Table 1, the battery A in which the cobalt oxide layer was formed between the nickel hydroxide obtained by the electrolytic deposition method and the nickel hydroxide obtained by the chemical impregnation method, The utilization rate of the active material is higher than that of the battery B of the comparative example without the cobalt oxide layer. This is because cobalt oxide diffuses around the nickel hydroxide obtained by the electrolytic deposition method and the nickel hydroxide obtained by the chemical impregnation as cobalt oxide ions, and forms a cobalt oxyhydroxide having good conductivity during charging. It is considered that the utilization rate of the active material has improved. Comparative battery C in which cobalt oxide was formed between layers and between particles of nickel hydroxide obtained by a chemical impregnation method.
Battery A has a higher capacity density and a higher active material utilization rate than that of battery A.
This is because the contact area of the nickel hydroxide obtained by the electrolytic deposition method is larger than that of the nickel hydroxide obtained by the chemical impregnation method, and the effect of forming a cobalt oxide layer on the surface of the nickel hydroxide particles is improved. It is thought that it becomes big.
Further, in the battery D of the comparative example containing no cobalt in the substrate, and in the filling of nickel hydroxide by chemical impregnation,
The active material utilization is higher than that of the battery F of the comparative example which is not a mixed solution with cobalt nitrate. This is due to the presence of cobalt hydroxide in the substrate, together with cobalt hydroxide and nickel hydroxide impregnated by the chemical impregnation method. This is probably because the conductivity between the filled nickel hydroxide, the nickel hydroxide filled by the chemical impregnation method, and the nickel hydroxide filled by the chemical impregnation method is synergistically improved.

The batteries A, B, C, D, E, and F
The durability characteristics of the cycle specified in 7, 8 and 7 of SC8705 were evaluated. FIG. 1 shows the relationship between the number of cycles at an ambient temperature of 50 ° C. and the capacity ratio of each cycle (standard capacity ratio) when the capacity of the first cycle is 100. Battery A having high conductivity in the electrode plate has good characteristics over a long period of time. However, in battery B, the characteristics deteriorated in an early cycle due to insufficient conductivity between nickel hydroxide filled by electrolytic deposition and chemical impregnation. Further, the battery C also has a certain degree of conductivity, but is insufficient, and the characteristics are deteriorated.
Batteries D and F also have considerable conductivity, but are insufficient in terms of conductivity for maintaining characteristics over a long period of time. In the battery E, the utilization rate of the active material is almost the same.
In this embodiment, nitrate is used as the salt of nickel and cobalt. However, it is needless to say that substantially the same effect can be obtained when sulfate is used.

[0016]

As described above, according to the present invention, cobalt is contained in the porous metal substrate, and nickel hydroxide obtained by the electrolytic deposition method is filled as a part of the total amount of the necessary active material. An oxide layer is formed by chemical impregnation, and then a majority of the required amount of nickel hydroxide is filled with a mixed solution of nickel nitrate and cobalt nitrate by a chemical impregnation method. Nickel hydroxide by chemical method-Cobalt hydroxide by chemical impregnation-Nickel hydroxide by chemical impregnation-Cobalt hydroxide by chemical impregnation-Nickel hydroxide by chemical impregnation And the diffusion of the electrolyte into the inner part of the electrode plate is improved, so that the nickel positive electrode has a high capacity density, a high utilization rate of the active material, and a long life. It is possible to obtain.

[Brief description of the drawings]

FIG. 1 is a diagram showing a relationship between the number of cycles of a battery and a standard capacity ratio in each cycle when the capacity of the first cycle is set to 100 in the embodiment.

Continuation of the front page (56) References JP-A-59-27457 (JP, A) JP-A-9-274914 (JP, A) JP-A-9-274916 (JP, A) JP 2-41865 (JP) , B2) Tokiko Hei 6-77452 (JP, B2) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01M 4/26 H01M 4/32

Claims (3)

(57) [Claims] A porous metal substrate contains cobalt, and nickel hydroxide serving as an active material is filled in a hole of the substrate as a part of a necessary amount of the active material by an electrolytic deposition method. Forming a layer by chemical impregnation, then
A method for producing a nickel positive electrode plate for an alkaline storage battery, comprising filling a majority amount of nickel hydroxide in the required total amount by a chemical impregnation method. 2. The amount of nickel hydroxide obtained by the electrolytic deposition method is about 30% by weight of the total amount of the required active material, and the amount of nickel hydroxide obtained by the chemical impregnation method is the amount of the required active material. The method for producing a nickel positive electrode plate for an alkaline storage battery according to claim 1, which is about 70% by weight of the amount. 3. The method for producing a nickel positive electrode plate for an alkaline storage battery according to claim 1, wherein a mixed solution of nickel nitrate and cobalt nitrate is used as the salt solution in the chemical impregnation method of filling nickel hydroxide.