JPH06187982A - Manufacture of paste type nickel electrode plate for alkaline storage battery - Google Patents

Abstract

PURPOSE:To increase a utilization factor, and provide a long-life electrode plate by blending and using mixed powders of conductive materials to which a grinding process is applied with powders of nickel hydroxide active material. CONSTITUTION:Mixed powders of two or more sorts of conductive materials which are grinding processed are mixed with active material powders, and these mixed powders are grinding processed. Otherwise, mix of the conductive material mixed powders with the active material powders are grinding processed. Grinding-processed matter is mixed with solution of thickener to be paste, which is then filled to a porous metal substrate to be dried and rolled, thereby a nickel electrode plate with improved conductivity and utilization factor can be provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a paste type nickel electrode plate for alkaline storage batteries.

[0002]

2. Description of the Related Art Conventionally, nickel-hydrogen batteries, nickel-
A typical manufacturing method of a nickel electrode plate used as a positive electrode in an alkaline storage battery such as a cadmium battery is a sintering formula in which a nickel sintered substrate is impregnated with a nickel salt aqueous solution and is changed into nickel hydroxide in the alkaline aqueous solution. There is a paste type in which nickel hydroxide powder as an active material is made into a paste and filled in a porous metal substrate such as a foamed nickel substrate or a nickel fiber felt. In particular, the paste type is attracting attention because it can increase the battery capacity.

[0003]

In the pasted nickel electrode plate, since the active material becomes nickel oxide during charging, the current collecting property is lowered, the utilization factor and the rapid discharge performance are lowered, and therefore the conductivity is reduced. Nickel hydroxide powder may contain a small amount of cobalt hydroxide for the purpose of increasing the polarization and decreasing polarization, and further mixed with one or more of Ni powder, Co powder, CoO powder, etc. as conductive material powder. It has been attempted to fill the substrate into a paste form to manufacture the product, but the mixture of the conductive material powder and the active material powder is still insufficient, and the utilization factor of the positive electrode and the rapid discharge performance are sufficiently improved. Not. Therefore, it is desirable to further improve these characteristics.

[0004]

The present invention solves the above-mentioned conventional problems and provides a method for producing a paste-type nickel electrode plate for an alkaline storage battery which satisfies the above-mentioned needs. A mixed powder of milled and unmilled nickel hydroxide active material powder is filled into a porous metal substrate in a paste form, which is then dried,
Characterized by being rolled.

[0005]

By the above-mentioned grinding treatment, the particles are pressure-bonded to each other and have physical or chemical contact points, so that the conductivity is improved and, therefore, the mixing with the active material powder is performed well. Further, the utilization rate of the active material is increased, and the rapid discharge performance of the battery can be improved. In this case, it is preferable to use a mixed powder of Ni powder and Co powder or CoO powder as the conductive material powder. Ni powder and Co powder have a three-dimensional chain structure, but by the grinding treatment, the three-dimensional chain structure is destroyed,
Secondary aggregation is prevented and dispersibility in the active material powder is improved.
In the case of CoO powder, since it is a fine powder, secondary agglomeration is likely to occur, but the grinding treatment breaks and agglomerates the agglomerates and improves uniform mixing with the active material. On the other hand, by pressing fine Ni powder etc. on the particle surface,
It is possible to prevent the formation of Co ₃ O ₄ having poor conductivity by reacting with oxygen in the air or dissolved oxygen in the electrolyte before charging, and at the same time, to provide a nickel positive electrode with improved conductivity and utilization rate. . Further, when Ni powder adheres to the surface of Co powder particles, it accelerates the oxidation of Co to CoO that occurs during charging, resulting in the dissolution of CoO as HCoO ₂ ⁻ ions and as a conductive oxide. It assists the effect of improving the conductivity in the micro area due to the precipitation of. From the above, the nickel electrode plate produced by the above treatment of the present invention provides a battery having a high utilization rate, excellent rapid discharge performance, and a long life, as will be made clear later.

[0006]

EXAMPLES Next, examples of the present invention will be described. As the nickel hydroxide powder as the active material, nickel powder composed of spherical particles is generally preferably used. Further, it is general and preferable to use nickel hydroxide powder containing a small amount of cobalt hydroxide powder. Generally, Ni powder is preferably used as the conductive material powder, but of course other metal powders having good alkali resistance and good conductivity can also be used. Generally, Ni powder to Co powder or
It is preferable to use CoO powder or a mixture of both,
These are also dissolved in the alkaline electrolyte to become HCoO ₂ ⁻ ions and become a stable form of CoOOH, which works effectively for battery operation.

According to the conventional typical nickel electrode plate manufacturing method, a small amount of cobalt hydroxide is added to spherical nickel hydroxide powder, and further Ni powder (nickel powder) and Co powder (cobalt cobalt) are used as the conductive material powder. Powder) or CoO powder (cobalt oxide powder), or both Co powder and CoO powder using a V-blender or the like, Co powder and Ni powder have a three-dimensional chain-like structure. It is difficult to obtain the one obtained by uniformly dispersing and mixing with the active material because the CoO powder, which is mixed with the material powder, easily secondary-aggregates. Therefore, such a mixture is kneaded with an aqueous solution of a thickener such as CMC to form a paste, which is filled in a foamed nickel substrate, a nickel fiber felt or other porous substrate having a three-dimensional network structure, and dried. Although the rolled nickel was the best nickel electrode plate, it was difficult to obtain the one in which the mixed powder was uniformly dispersed as described above, and at the same time, the active material powder and the conductive material powder were joined together, and the conductive material powder was joined together. Is poor, and therefore its conductivity and utilization are relatively low.

According to the present invention, in order to improve this,
Mixing one or more kinds of conductive material mixed powder by grinding, mixing with active material powder, further grinding these mixed powders, or mixing conductive material mixed powder and active material powder at once The porous metal substrate is filled with a paste that is mixed with an aqueous solution of a thickening agent, which is ground in any one of the steps of A nickel electrode plate having improved properties and utilization rate can be obtained.

This will be described in more detail with reference to a representative embodiment. That is, as the conductive material powder, two kinds of Ni powder and Co powder or CoO powder are mixed to prepare a conductive material mixed powder, or Ni powder and Co powder.
3 kinds of powder and CoO powder are mixed to prepare conductive material mixed powder,
After this is ground, the active material powder is mixed with it and ground. The grinding treatment is performed using a mortar or a stainless steel ball mill. By doing so, the Ni powder and the Co powder having a three-dimensional chain-like structure have their chains separated, so that a well-distributed conductive material mixed powder that is easy to uniformly disperse in the active material powder can be obtained. . Further, the conductive material mixed powder particles can be pressed against each other, and further the conductive material powder particles and the active material powder particles can be pressed against each other. As a result, the conductivity and the utilization rate of the active material are improved. In the case of CoO, since it is protected by Ni powder that is well pressed onto its surface, good results such as being prevented from being oxidized to Co ₃ O ₄ by oxygen in the air or dissolved oxygen in the electrolytic solution can be obtained. can get. Thus, the thus treated product is made into a paste with an aqueous solution of a thickening agent such as CMC, and the porous metal substrate is filled with the resulting product to improve the conductivity, the utilization rate, etc. of the nickel electrode plate. Is obtained.

Next, a more specific embodiment of the present invention will be described. Example 1 10 g of commercially available Ni (# 255 manufactured by INCO) and Co powder (UN, Extra Fin
5 g of e Co Powder) was ground in a mortar for 15 minutes.
To the obtained mixed powder, 85 g of spherical nickel hydroxide powder (containing about 1% of Co) was added, and further ground for 15 minutes.
35 g of a 2% carboxymethylcellulose (CMC) aqueous solution was added to the mixed powder thus obtained to form a paste, and a foamed nickel substrate was used as a porous metal substrate, which was filled and dried. And then 5% of this
The paste dispersion was impregnated with the PTFE dispersion, dried, and rolled to a predetermined thickness to prepare a paste-type nickel electrode plate of the present invention. This is electrode plate A
Called.

Example 2 10 g of commercially available Ni (# 255 manufactured by INCO) and 5 g of CoO powder (FCO-178 manufactured by Sumitomo Metal Mining Co., Ltd.) were ground in a mortar for 15 minutes. Spherical nickel hydroxide powder (Co
Of about 1%) was added, and the mixture was further ground for 15 minutes. Subsequent operations were performed in the same manner as in Example 1 to produce the paste-type nickel electrode plate of the present invention. This is called an electrode plate B.

Example 3 10 g of commercially available Ni (# 255 manufactured by INCO), 2.5 g of CoO powder (FCO-178 manufactured by Sumitomo Metal Mining Co., Ltd.) and Co powder (UN, Extra Fine)
2.5 g of Co powder) was ground in a mortar for 15 minutes.
To the obtained mixed powder, 85 g of spherical nickel hydroxide powder (containing about 1% of Co) was added, and further ground for 15 minutes.
Subsequent operations were performed in the same manner as in Example 1 to produce the paste-type nickel electrode plate of the present invention. This is called an electrode plate C.

Example 4 10 g of commercially available Ni (# 255 manufactured by INCO) and 2.5 g of CoO powder (FCO-178 manufactured by Sumitomo Metal Mining Co., Ltd.) were ground in a mortar for 15 minutes. To the obtained mixed powder, 85 g of spherical nickel hydroxide powder (containing about 1% of Co) was added and mixed with a V-blender. The following operations were performed in the same manner as in Example 1 to produce the paste-type nickel electrode plate of the present invention. This is called an electrode plate D.

Comparative Example 1 10 g of commercially available Ni (# 255 manufactured by INCO) and Co powder (UN, Extra Fin
e Co Powder) 5 g and spherical nickel hydroxide powder (Co
Of about 1%) was placed in a V-blender and mixed for 30 minutes. 35 g of a 2% carboxymethyl cellulose aqueous solution was added to the obtained mixed powder to form a paste, which was filled in a nickel foam substrate and dried. This was impregnated with a 5% PTFE dispersion, dried, and rolled to a predetermined thickness to prepare a conventional paste-type nickel electrode plate. This is called an electrode plate E.

Comparative Example 2 10 g of commercially available Ni (# 255 manufactured by INCO), 5 g of CoO powder (FCO-178 manufactured by Sumitomo Metal Mining Co., Ltd.) and 85 g of spherical nickel hydroxide powder (containing about 1% of Co) were added as V. Place in blender and mix for 30 minutes. Subsequent operations were performed in the same manner as in Comparative Example 1 to produce a conventional paste-type nickel electrode plate. This is called an electrode plate F.

These electrode plates A to D of the present invention and conventional electrode plates E and F are used as positive electrodes, respectively, and are laminated and wound with a hydrogen storage alloy negative electrode via a separator to form a wound electrode plate group, which is placed in a cylindrical can. Then, an alkaline electrolyte having a specific gravity of 1.36 was injected and immediately sealed to prepare a number of AA size sealed nickel-hydrogen batteries each having a rated capacity of 1100 mAh.

These batteries were charged under a 20 ° C. environment at a current of 0.2 C for 7.5 hours, and discharged at the same current until the battery voltage became 1.0 V, repeated twice, and then left at 40 ° C. for 24 hours. Initial activation was performed. After the initial activation, the following battery test was conducted. Capacity test After charging for 7.5 hours at 20 ° C and a current of 0.2C, the battery was discharged at 0.2C until the battery voltage became 1.0V, the capacity was measured, and the utilization rate was investigated. Rapid Discharge Test After charging at 20 ° C. and 0.2 C current for 7.5 hours, the battery was discharged at 3 C until the battery voltage became 1.0 V, the capacity was measured, and the utilization factor was examined. Life test 25 ° C, 1C, charging by -ΔV method, 3
At C, discharging is repeated until the battery voltage becomes 1.0V. The number of charge / discharge cycles until the battery capacity reached 700 mAh was examined. The results of the above tests are summarized in Table 1 below.

[0018]

[Table 1]

As is apparent from Table 1 above, at least the nickel electrode plate A of the present invention produced by using a mixed powder in which at least a mixed powder of the conductive material is subjected to grinding treatment in advance and mixed with the active material powder, B, C, and D use the battery capacity more than the conventional nickel electrode plates E and F manufactured by using the mixed powder in which the conductive material mixed powder without such grinding treatment is mixed with the active material powder. It can be seen that excellent rate, rapid discharge capacity utilization rate, and charge / discharge cycle life are all obtained.

[0020]

As described above, according to the present invention, the mixed powder of the mixed powder of the conductive material, which has been subjected to the grinding treatment, and the powder of the nickel hydroxide active material, which has or has not been ground, is previously prepared. Since it was prepared and a paste-type nickel electrode plate was manufactured using this, compared to a conventional paste-type nickel electrode plate manufactured by using a mixed powder formed by simply mixing a mixed powder of a conductive material and an active material powder. The paste type nickel plate having a high utilization rate and excellent rapid discharge performance and a long life is obtained, and it has an advantageous effect of being used as a positive electrode of an alkaline storage battery.
In this case, as the mixed powder of the conductive material, Ni powder and Co powder or CoO
It is particularly effective when applied to the present method for a mixed powder with powder or a mixture of Ni powder with Co powder and Co powder.

[Table 1]

Claims (2)

[Claims] 1. A porous metal substrate is filled in a paste form with a mixed powder of a mixed powder of a conductive material, which has been subjected to a grinding treatment, and a powder of nickel hydroxide active material which has or has not been ground. Next, a method for producing a paste-type nickel electrode plate for an alkaline storage battery, which is characterized by being dried and rolled. 2. A mixture of conductive material powder is Ni powder and Co powder or /
The method for producing a paste-type nickel electrode plate for an alkaline storage battery according to claim 1, which is a mixture of CoO and CoO.