JP3136688B2 - Nickel-hydrogen 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 a nickel-hydrogen storage battery, and more particularly to a nickel-hydrogen storage battery using a hydrogen storage alloy negative electrode.

[0002]

2. Description of the Related Art Alkaline storage batteries widely used as various power sources can be expected to have high reliability, and small batteries can be used for various portable equipment and large batteries can be used for industrial purposes for any reason. Have been.

In most cases, a nickel electrode is used as a positive electrode in this alkaline storage battery. The characteristics have been improved from the pocket type to the sintering type, and the sealing has been made possible and the use has expanded.

On the other hand, at present, cadmium electrodes are mainly used as the negative electrode, but nickel-hydrogen storage batteries using a hydrogen storage alloy electrode have been attracting attention in order to achieve a higher energy density, and many proposals have been made on manufacturing methods and the like. It has been done. Improvements in rapid charge / discharge properties as well as high energy density are being pursued.

For example, in order to improve the hydrogen storage alloy powder, especially its oxidation resistance, and its utilization and moldability, a technique of forming a porous metal layer by plating the particle surface with nickel or copper is known. . Further, it has been proposed to add nickel, copper, nickel oxyhydroxide powder, etc., and to immerse them in an alkaline solution in order to improve the initial characteristics.

In addition, when applied to a sealed type, it has been attempted to add a fluororesin or a catalyst in order to improve the absorption of oxygen gas from the positive electrode during charging and hydrogen gas which may be generated during overcharging. Have been.

[0007]

The hydrogen storage alloy electrode is manufactured by sintering the alloy powder and filling or coating the porous material having a two-dimensional or three-dimensional structure such as foamed, fibrous, or punched metal. There is a paste type of method. In any case, there is room for improvement particularly in the discharge characteristics at the beginning of the charge / discharge cycle. In particular, Zr, Mn,
ZrMn _0.6 Cr _0.2 Ni composed of elements such as Ni
_{In the case} of AB ₂ -based Laves phase alloys such as _1.2 , although improvements have been made and high capacity can be achieved, there still remains a problem in the initial activation. In the case of the sealed type, if the initial acceptance of charging is poor, the battery will be based on the negative electrode law, and problems will occur in high discharge characteristics, self-discharge, life, and the like. In addition, the charge / discharge cycle life is worse than that of the cadmium electrode, and when the electrolyte is insufficient, the potential drops significantly. That is, even in the initial stage of charging and discharging, the battery is easily affected by the amount of the electrolyte, and the capacity obtained in a battery system rich in the electrolyte is considerably reduced in an electrolyte-impregnated system such as a closed type.

An object of the present invention is to solve such a problem, and an object of the present invention is to provide a nickel-hydrogen storage battery which exhibits excellent characteristics from the beginning and can maintain the characteristics over a long period of time.

[0009]

In order to solve this problem, a nickel-hydrogen storage battery according to the present invention comprises a hydrogen storage alloy electrode, particularly ZrMn _0.6 Cr composed of elements Zr, Mn and Ni.
_A nickel hydroxide powder is added to an AB ₂ -based alloy such as _0.2 Ni _1.2 to form a negative electrode, a nickel positive electrode, a separator, and a caustic electrolyte are used to form a battery. Further, as a more effective manufacturing method, a sealed battery may be formed by forming nickel hydroxide on a hydrogen storage alloy electrode from a nickel salt solution, using this, a nickel positive electrode, a separator, and a caustic electrolyte. Note that there is no lower limit on the amount of nickel hydroxide to be added, since the effect is as much as it is added. On the other hand, if it is added too much, the capacity becomes insufficient, so that about 3 to 15% by weight with respect to the hydrogen storage alloy is appropriate.

[0010]

[Function] Especially as a hydrogen storage alloy, ZrMn _0.6 Cr _0.2
When an AB ₂ -based alloy such as Ni _1.2 is used, the initial characteristics of the battery can be considerably improved by treating the hydrogen-absorbing alloy, so it can be estimated that it is necessary to improve the particle surface and the affinity for hydrogen. However, when nickel hydroxide is added to the hydrogen storage alloy, it is hard to imagine the surface modification. Therefore, it seems that the nickel hydroxide effect of the nickel-hydrogen storage battery having this configuration is harmless itself and plays the largest role as an electrolyte impregnating agent. Originally, a hydrogen storage alloy does not require high porosity (about 40%) like a cadmium electrode because hydrogen ions can diffuse through the alloy. This is considered as one of the reasons why a high energy density can be achieved, and is used under sufficiently pressurized condition. If it is a metal powder and has low porosity, the impregnation amount of the electrolytic solution is small, and thus there is a problem in the utilization factor and the cycle life.
Nickel hydroxide has a bulk specific gravity smaller than that of a metal, and is much more lyophilic to an electrolytic solution than a metal.

It is effective to impregnate a nickel salt instead of a powder and then dry and convert it to nickel hydroxide since nickel hydroxide can be formed on the surface of the hydrogen storage alloy.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A nickel-hydrogen storage battery according to one embodiment of the present invention will be described below. A hydrogen storage alloy was mechanically pulverized to 200 mesh or less, and a ZrMn _0.6 Cr _0.2 V _0.1 Ni _1.2 alloy was selected as an AB ₂ Laves phase alloy. 5% by weight of nickel hydroxide powder, which is a spherical fine powder, is added to the alloy powder, and the mixture is stirred and mixed so that it is sufficiently rubbed. A paste prepared by adding a 1.5% by weight aqueous solution of carboxymethycellulose was filled in a foamed nickel plate having a porosity of 95% and a thickness of 1.0 mm, and then dried and pressed. This electrode was cut into a width of 3 mm and a length of 210 mm, and a lead plate was attached by spot welding. This electrode is designated as A.

Next, for comparison, an electrode without nickel hydroxide was added as B. The electrode B was prepared in the same manner as the electrode A except that nickel hydroxide was not added.

A sealed nickel-hydrogen storage battery was constructed using these hydrogen storage alloy electrodes. A sealed nickel-hydrogen storage battery was constructed using a known foamed nickel electrode as a counter electrode and a hydrophilic non-woven polypropylene separator. The capacity of the negative electrode with respect to the positive electrode is 4.2 Ah (140
%). Then, 2 parts of caustic potash solution with specific gravity of 1.25
An electrolyte in which 5 g / l of lithium hydroxide was dissolved was injected. The battery is of SubC type and has a nominal capacity of 3.0 Ah. In this case, the battery constituted by the electrode A is referred to as a battery A, and the battery constituted similarly by the electrode B is referred to as a battery B.

First, 10 cells of each of the batteries A and B were formed. That is, after charging at 400 ° C. for 13 hours at an ambient temperature of 25 ° C., discharging was performed at 700 ° mA at 25 ° C. to a terminal voltage of 0.8 V. This charge / discharge was repeated three times.

The discharge characteristics of the batteries were compared.
At 0.2 C discharge, Battery A had an average voltage of 1.27 V and a discharge capacity of 3.01 Ah. On the other hand, for battery B,
V was 2.95 Ah. A is 1.21 in 1C discharge
V, 1.17V, 2.77A for B versus 2.94Ah
h.

Next, the charge / discharge cycle life was compared. With an ambient temperature of 25 ° C and a current of 1 / 3C (1A),
After 30% charging, charging and discharging were repeated under the condition that discharging was performed at 0.5 C (1.5 A) to 0.9 V. As a result, the discharge capacity of the battery A was 89 to 92% at the initial stage even at 800 cycles, whereas the discharge capacity of the battery B was 78 to 82%, indicating that the performance of the battery A was stable for a long time.

In the above embodiment, an example was shown in which nickel hydroxide powder, which is a spherical fine powder, was simply added. However, there is another method for adding nickel hydroxide. This alternative was also very beneficial. That is, a method of adding a nickel salt solution such as nickel nitrate to the electrode of the hydrogen storage alloy and then immersing the nickel salt in an aqueous alkali solution to convert it to nickel hydroxide. In this case, nickel hydroxide was finely formed on the surface of the hydrogen storage alloy, and the effect of the present invention worked particularly well.

[0019]

As is clear from the above description of the embodiments, according to the nickel-hydrogen storage battery of the present invention, the hydrogen storage alloy, particularly the ZrMn _0.6 Cr _0.2 V _0.1 Ni _1.2 alloy or Zr
Mn _{0. 6} Cr _0.2 Ni _1.2 or addition of nickel hydroxide powder in the negative electrode containing AB ₂ type alloy such as alloy or hydrogen absorbing alloy electrode to form the nickel hydroxide from nickel salt solutions, and this negative electrode, a nickel By forming a sealed battery using a positive electrode, a separator, and a caustic electrolyte, excellent characteristics are exhibited from the beginning, and the effect of the invention capable of maintaining the characteristics for a long period of time is great.

────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Yoichiro Tsuji 1006 Kazuma Kadoma, Kadoma City, Osaka Inside Matsushita Electric Industrial Co., Ltd. (56) References JP-A-4-255668 (JP, A) JP-A-4-4 179053 (JP, A) JP-A-4-259751 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01M 4/24-4/26 H01M 4/38 H01M 10/24- 10/30 H01M 10/34

Claims (5)

(57) [Claims] 1. A nickel-hydrogen storage battery having a configuration using a hydrogen storage alloy negative electrode to which nickel hydroxide is added, a nickel positive electrode, a separator, and a caustic alkaline electrolyte. 2. The nickel-hydrogen storage battery according to claim 1, wherein the nickel hydroxide is a spherical fine powder. 3. A nickel alloy comprising a negative electrode obtained by adding a nickel salt solution to a hydrogen storage alloy electrode and converting it to nickel hydroxide, a nickel positive electrode, a separator, and a caustic alkaline electrolyte. Hydrogen storage battery. 4. The nickel-hydrogen storage battery according to claim 1, wherein the amount of nickel hydroxide added is 3 to 15% by weight based on the hydrogen storage alloy. 5. The hydrogen storage alloy is preferably made of Zr, Mn, Ni
AB composed of elements _TwoClaim 1 comprising a Laves phase.
Or the nickel-hydrogen storage battery according to 3.