JPS59111264A - Positive plate for alkaline battery - Google Patents

Abstract

PURPOSE:To provide an active material, which is easy to control formulation and has good quality, for a secondary battery positive plate by chemically preparing cobalt-nickel oxide which is electrochemically active. CONSTITUTION:Nickel or nickel compound such as NiO or Ni(OH)2, preferably its powder, is added to a solution containing cobalt salt such as cobalt nitrate or caobalt sulfate and they are stirred. Alkaline solution such as sodium carbonate or sodium hydroxide containing oxidizing agent such as sodium hypochlorite, bromine, or potassium peroxosulfate is mixed to above solution and stirred to form black precipitation. The precipitation is allowed to stand for about one hour after mixing to complete the reaction. The precipitation is washed, dried, and crushed. This cobalt-nickel mixed oxide is used as a positive active material and zinc or iron as a negative active material to manufacture an alkaline battery.

Description

DETAILED DESCRIPTION OF THE INVENTION Secondary batteries currently in use include lead batteries, nickel-cadmium batteries, and silver batteries. Of these, only lead batteries and nickel-cadmium batteries are used commercially. In other words, the active material of the positive electrode plate for secondary batteries is PbO2 for lead batteries that use an acidic aqueous solution, and N1(OH) for nickel-cadmium batteries that use an alkaline aqueous solution.
)2 only. It has recently been discovered that an electrochemically extremely active cobalt-nickel mixed oxide can be produced by anodic oxidation of nickel using an acidic bath containing cobalt salts, and it has become clear that it can be used as a positive electrode active material for alkaline batteries. It has become. However, this method using electrochemical means has the disadvantage that it is extremely difficult to control the composition of the cobalt-nickel mixed oxide, which changes depending on the concentration of cobalt salt in the bath liquid and the current density. Therefore, it would be desirable to have a chemical method that allows easy control of the composition.

The present invention is based on the discovery that an electrochemically active cobalt-nickel oxide can be synthesized by a chemical method.

The cobalt-nickel mixed oxide according to the present invention can basically be produced by the following method.

First, nickel or a nickel compound such as Ni 2 O or Ni(OH) 2 , preferably in powder form, is placed in a bath solution containing a cobalt salt such as cobalt nitrate or cobalt sulfate and stirred. In that case, since the bath liquid is acidic, if N1(OH)2 is used with nickel or a nickel compound, it will gradually dissolve, but it will not be a big problem for a short time. Subsequently, an alkaline aqueous solution such as sodium carbonate or sodium hydroxide containing an oxidizing agent such as sodium hypochlorite, oxalic acid, or potassium periodoxosulfate is mixed and stirred. Then, a black precipitate is formed. After mixing, the mixture is allowed to stand for about 1 hour to mature, and the reaction is almost completed. If this precipitate) 1 is washed, dried, and then ground, it will produce the powder according to the present invention.
It is possible to produce 1q of rut-nickel mixed oxide. The composition of this mixed oxide varies depending on the type of nickel compound, and some hydroxides of cobalt and nickel are included, but the main component is thought to be a cobalt-nickel mixed oxide.

Hereinafter, specific examples of the present invention and their effects will be described in detail.

Example 1. Add nickel powder to 2ft of 4M cobalt nitrate aqueous solution adjusted to ρ = 2 so that the amount becomes 10wt% based on the cobalt in the bath, and add 0.5M while stirring.
After gradually adding 6 portions of a 5M aqueous sodium hydroxide solution containing sodium hypochlorite nitrate (NaOCl), the mixture was allowed to stand for 2 hours. Thereafter, the precipitate was filtered and washed using a filter, and then dried at 110''C for 1 hour.Then, the precipitate was pulverized to obtain a positive electrode active material according to the present invention.

Example 2.1) NiO powder was added to two 4M cobalt nitrate aqueous solutions adjusted to H = 2 at a weight of 5w relative to the cobalt in the bath.
%, then add to 200ml while stirring.
of oxalic acid and 5M sodium hydroxide aqueous solution 69. After gradually adding , let stand for 2 hours. Thereafter, the precipitate is filtered and washed with a filter, and then dried at 110° C. during IFR. Thereafter, it was pulverized to obtain a positive electrode active material according to the present invention.

Example 3. A 4M cobalt nitrate aqueous solution adjusted to p=2 was added with nickel hydroxide (Ni(OH)2>powder and 0.2% by weight of cobalt in the bath).
After simultaneously adding 6 ft of 5M sodium hydroxide aqueous solution containing potassium periodoxosulfate (K2820B) with stirring, it was left to stand for 2 hours.Then, the precipitate was filtered and washed with a filter, and then heated at 110°C. de1
Dry for an hour. Thereafter, it was pulverized to obtain a positive electrode active material according to the present invention.

Example 4. A 4M cobalt nitrate aqueous solution adjusted to pH = 2 was added with nickel oxyhydroxide (γ-N100wl) and 0.5wt% of the cobalt in the bath.
5M containing M sodium hypochlorite (NilOCl)
After gradually adding 6 mts of sodium hydroxide aqueous solution, 2 mts.
Let stand for a while. After that, the formed precipitate was filtered, washed, and dried at 110°C for 1 hour.
Ru. Thereafter, it was pulverized to obtain a positive electrode active material according to the present invention.

When the positive electrode active materials according to the present invention obtained in Examples 1 to 4 were examined using powder X-ray diffraction analysis (CoKα), 2
Broad peaks were observed around θ of 22-23°, 42-46°, and 77°. In addition, unreacted N1 was observed in Example 1, and a slight diffraction peak of NiO was observed in Example 2.

Next, in order to investigate the performance of an alkaline battery using the positive electrode active material according to the present invention, 20 wt% of graphite was mixed into the positive electrode active materials (150 mesh or less) obtained in Examples 1 to 4, and the mixture was press-molded. After that, it was wrapped in a 100-mesh nickel mesh and further pressure-molded to make a positive electrode plate. One of these positive electrode plates, a conventionally known negative electrode plate made by wrapping cadmium hydroxide powder in a nickel mesh and press-forming, a nylon nonwoven fabric as a separator, and a specific gravity of 1.2 as an electrolyte.
A sealed button battery (cobalt-cadmium battery) according to the present invention having a nominal capacity of 50 mAh was manufactured using a KOH aqueous solution of 50° C. (20° C.). Batteries using the active materials produced in Example 1゜2.3 and 4 were labeled A, B, and B, respectively.
Let them be C, fl and D. These batteries are 606C,0,
After discharging at IOA for 16 hours, 1 = then 0.5 at 0.2OA.
Figure 1 shows the charge-discharge characteristics when discharged to v. For comparison, a similar battery E using a cobalt-nickel mixed oxide obtained by anodizing a nickel plate in a 0.2M cobalt nitrate aqueous solution is also shown.

It can be seen from the figure that batteries A, B, C, and D according to the present invention have performance equivalent to battery E using a conventional electrochemically produced active material.

As described above, the present invention can chemically synthesize and provide a cobalt-nickel mixed oxide having an activity equivalent to that synthesized electrochemically.

In the synthesis of the cobalt-nickel mixed oxide according to the present invention, cobalt nitrate was used in the examples, but cobalt sulfate or cobalt chloride may also be used, and nickel oxides such as nickel and NIO may be mixed with an aqueous solution of cobalt nitrate. Mixed into the alkali aqueous solution, but may also be added to the alkaline aqueous solution, nickel oxide, alkaline aqueous solution,! ! ! The cobalt-containing acidic solution and the cobalt-containing acidic solution may be mixed in different orders, or even mixed at the same time to produce an equivalent cobalt-nickel mixed oxide.

Needless to say, this cobalt-nickel mixed oxide can also be applied to alkaline batteries using the positive electrode active material and zinc or iron as the negative electrode active material.

[Brief explanation of the drawing]

Figure 1 shows batteries (A) and (B) using positive electrode plates according to the present invention.
, (C) and (D) and a battery using a conventional positive electrode plate (E
) is the charging/discharging voltage characteristic.

Claims (1)

[Claims] 1. Nickel or a nickel compound such as Nip, Ni (OH) 2, an acidic solution containing a cobalt salt such as cobalt nitrate or cobalt sulfate, and sodium hypochlorite,
A positive electrode plate for alkaline batteries whose active material is a cobalt-nickel mixed oxide produced by mixing an oxidizing agent such as oxalic acid or potassium peroxosulfate with an alkaline aqueous solution such as sodium carbonate or sodium hydroxide.