KR19990000633A - Nickel Electrode and Alkaline Secondary Battery Employing the Same - Google Patents

Abstract

The present invention relates to a nickel electrode comprising a porous nickel current collector and an active material composition filled in pores of the porous nickel current collector, wherein the active material composition includes a nickel hydroxide, a conductive agent, a binder, and a thickener. The present invention relates to a nickel electrode and an alkaline secondary battery employing the nickel electrode, wherein the styrene-butadiene rubber is present in an amount of 0.01-1% by weight based on the total weight of the nickel hydroxide. In the nickel electrode according to the present invention, even if only a small amount of the binder is added, dropping of the active material and subsequent short circuit of the battery do not occur. In addition, it is very useful to realize the overall improvement of the battery characteristics, such as the effect of increasing the active material capacity and to prevent the deterioration of conductivity. That is, according to the present invention, there is an advantage in that a battery which is inexpensive and has excellent performance can be obtained.

Description

Nickel electrode and alkaline secondary battery employing the same

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nickel electrode and an alkaline secondary battery employing the same, and more particularly, to a nickel electrode having a low cost and excellent performance and an alkaline secondary battery employing the same.

In the manufacture of an alkaline secondary battery, an electrode includes a current collector having a plurality of pores and an active material filled in the pores of the current collector, and is generally manufactured by a sintering method. This method impregnates a porous sintered substrate as a current collector in a solution containing an active material, and then repeats a series of steps of washing and drying several times to precipitate the active material chemically or electrochemically in the pores of the porous sintered substrate. This is a method for producing an electrode by treating in an alkaline solution. According to this method, the binding force between the active material and the current collector is large and the electrical contact area is large, so that an electrode having excellent active material utilization, high rate charge / discharge characteristics, and lifetime characteristics can be manufactured.

However, since the impregnation of the active material has to be repeated several times, not only is the manufacturing process complicated, but also the manufacturing cost is high, and the porosity of the porous sintered substrate used is only about 80%. Due to the problem of low, the paste electrode manufacturing method is a trend that is recently preferred.

Paste-type electrode manufacturing method is a method of manufacturing an electrode by spraying or applying the active material composition mixed with the electrode active material and other additives in a paste form on the surface of a porous current collector or a steel substrate, and dried. This method is very preferable in that the manufacturing process is simpler and the energy density is higher than that of the sintered electrode manufacturing method.

In the preparation of the paste type electrode, additives which may be added during the preparation of the active material composition include a conductive agent for increasing the conductivity of the active material, a conductive agent for increasing the binding force of the active material to prevent detachment of the active material, and a viscosity of the active material. Thickening agent for increasing, etc. are mentioned.

Of these, PTFE (polytetrafluoroethylene) or PVA (polyvinyl alcohol) has been mainly used as the binder. However, although PTFE and PVA are expensive, the binding strength is weak, and a large amount must be added to obtain the desired strength binding strength. However, since these are insulators, there is a problem that as the amount of addition increases, the battery performance, such as conductivity of the battery, is degraded and the lifespan is shortened. That is, PTFE and PVA are undesirable binders from an economical point of view or from the viewpoint of battery performance improvement.

On the contrary, SBR (styrene-butadiene rubber) is relatively inexpensive compared to PTFE or PVA, and the binding force is excellent, and thus it may show good binding force even if a small amount is added. Therefore, there is an advantage that it is economically advantageous and hardly affects the conductivity of the battery.

The technical problem to be achieved by the present invention is to provide a nickel electrode having excellent conductivity without falling off of the active material even when a small amount of the binder is added.

Another technical problem to be achieved by the present invention is to provide an alkaline secondary battery having improved conductivity and lifespan characteristics by employing the nickel electrode.

Technical problem of the present invention is a nickel electrode comprising a porous nickel current collector and an active material composition filled in the pores of the porous nickel current collector, the active material composition comprises a nickel hydroxide, a conductive agent, a binder and a thickener, The binder may be made of a styrene-butadiene rubber and a nickel electrode having a content of 0.01-1% by weight based on the total weight of the nickel hydroxide.

Another technical problem of the present invention can be achieved by an alkaline secondary battery employing the nickel electrode.

In the nickel electrode according to the present invention, foamed nickel or nickel felt may be used as the porous nickel current collector.

In addition, the conductive agent and the thickener is not particularly limited as long as it can be commonly used in the field of the present invention, preferably a metal cobalt or cobalt compound as a conductive agent, carboxymethylcellulose or methylcellulose may be used as a thickener. have. In addition, the content of the conductive agent and the thickener is preferably 1-10% by weight and 0.1-5% by weight based on the total weight of the nickel hydroxide.

Hereinafter, although an Example and a comparative example are given and this invention is demonstrated in detail, this invention is not limited to this.

Example 1

First, 100 g of nickel hydroxide (Ni (OH) ₂ , an average particle diameter of about 10 μm), 10 g of cobalt oxide, and 5 g of a carboxymethylcellulose aqueous solution were mixed to prepare a paste-like active material composition. Subsequently, the composition was applied to foamed nickel having an average diameter of about 300 µm, dried and rolled, and then cut into a size of 120 x 35 mm to obtain a nickel electrode plate. Subsequently, the nickel electrode plate was coated by dipping for 5 seconds in a solution containing 1 g of SBR (48% dispersion) and 1,000 g of water, followed by dry calendering at 60 ° C. to complete the nickel electrode.

Next, the AB _2- based hydrogen absorbing metal (average diameter: 35 µm) was mixed with carbon powder, PTFE and carboxymethyl cellulose aqueous solution to form a paste-like active material composition, which was then coated on a steel substrate and dried to obtain hydrogen. The electrode was completed.

The nickel electrode and the hydrogen electrode were used as the positive electrode and the negative electrode, respectively, and a polypropylene resin sheet was interposed between the positive electrode and the negative electrode as a separator, and then wound up to form an electrode group, which was then housed in a cylindrical can and encapsulated to form nickel-hydrogen. 100 secondary batteries were prepared.

For the batteries thus produced, the battery capacity, the short circuit rate, the number of charge / discharge cycles, and the electrical resistance were measured, and the average values of the batteries were obtained, and the results are shown in Table 1 below.

Example 2

100 nickel-hydrogen secondary batteries were prepared in the same manner as in Example 1, except that the nickel electrode plates were coated by dipping for 5 seconds in a solution containing 1 g of SBR (48% dispersion) and 500 g of water. . The battery capacity, the short circuit rate, the number of charge and discharge cycles, and the electrical resistance of the battery were measured, and their average values were determined. The results are shown in Table 1 below.

Comparative Example 1

100 nickel-hydrogen secondary batteries were prepared in the same manner as in Example 1, except that the nickel electrode plates were coated by dipping for 5 seconds in a solution containing 1 g of PTFE (60% dispersion) and 50 g of water. . The battery capacity, the short circuit rate, the number of charge and discharge cycles, and the electrical resistance of the battery were measured, and the average values of the batteries were measured. The results are shown in Table 1 below.

Comparative Example 2

100 nickel-hydrogen secondary batteries were prepared in the same manner as in Example 1, except that the nickel electrode plate was coated by dipping for 5 seconds in a solution containing 1 g of PTFE (60% dispersion) and 30 g of water. . The battery capacity, the short circuit rate, the number of charge and discharge cycles, and the electrical resistance of the battery were measured, and the average values of the batteries were measured. The results are shown in Table 1 below.

Comparative Example 3

100 nickel-hydrogen secondary batteries were prepared in the same manner as in Example 1, except that the nickel electrode plate was coated by dipping for 5 seconds in a solution containing 1 g of PTFE (60% dispersion) and 10 g of water. . The battery capacity, the short circuit rate, the number of charge and discharge cycles, and the electrical resistance of the battery were measured, and the average values of the batteries were measured. The results are shown in Table 1 below.

Comparative Example 4

100 nickel-hydrogen secondary batteries were prepared in the same manner as in Example 1, except that the nickel electrode plate was coated by dipping for 5 seconds in a solution containing 1 g of PVA and 500 g of water. The battery capacity, the short circuit rate, the number of charge and discharge cycles, and the electrical resistance of the battery were measured, and the average values of the batteries were measured. The results are shown in Table 1 below.

TABLE 1

As can be seen from the results of the above table, the nickel-hydrogen secondary battery according to the present invention had a low short-circuit rate and electrical resistance due to dropping of the active material even when only a small amount of the binder was added, and had excellent conductivity. In addition, the battery capacity also appeared to be large, indicating that battery characteristics are generally good.

In the nickel electrode according to the present invention, even if only a small amount of the binder is added, dropping of the active material and subsequent short circuit of the battery do not occur. In addition, it is very useful to realize the overall improvement of the battery characteristics, such as the effect of increasing the active material capacity and to prevent the deterioration of conductivity. That is, according to the present invention, there is an advantage in that a battery which is inexpensive and has excellent performance can be obtained.

Claims (5)

In the nickel electrode comprising a porous nickel current collector and an active material composition filled in the pores of the porous nickel current collector, The active material composition includes a nickel hydroxide, a conductive agent, a binder, and a thickener, wherein the binder is styrene-butadiene rubber and its content is 0.01-1% by weight based on the total weight of the nickel hydroxide. . The nickel electrode according to claim 1, wherein the porous nickel current collector is foamed nickel or nickel felt. The nickel electrode according to claim 1, wherein the content of the conductive agent is 1-10% by weight based on the total weight of the nickel hydroxide. The nickel electrode according to claim 1, wherein the content of the thickener is 0.1-5% by weight based on the total weight of the nickel hydroxide. An alkaline secondary battery employing the nickel electrode according to claim 1.