JPH11250905A - Nickel-hydrogen battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nickel hydrogen battery with electrochemical characteristics, long life, and high durability. SOLUTION: A nickel-hydrogen battery uses as a negative electrode a nickel- containing hydrogen storage alloy comprising (a) a fluorinated material of at least one nickel-containing hydrogen storage alloy selected from AB2 type, AB type, and BCC type nickel-containing hydrogen storage alloys, (b) a fluorinated material of at least one AB5 type nickel-containing hydrogen storage alloy, and if necessary fluorinated carbon black.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nickel-hydrogen battery having a stable output for a long period of time by using a hydrogen storage electrode capable of maintaining a high discharge capacity under a high discharge current condition as a negative electrode. is there.

[0002]

2. Description of the Related Art Alkaline storage batteries have been widely used as secondary batteries. An air electrode or a silver oxide electrode has been studied as a positive electrode of the alkaline storage battery. In most cases, a nickel electrode using nickel oxyhydroxide as an active material has been used. In these batteries, the electrical characteristics are improved by changing the nickel electrode from a pocket type to a sintered type, and a structure capable of being hermetically sealed can be obtained. On the other hand, cadmium electrodes have been mainly used as the negative electrode in the past.However, the use of cadmium has been restricted to prevent pollution, and the demand for higher energy density has increased. Has been attracting attention, and has been used as an energy source for small devices, mobile devices, electric vehicles and hybrid vehicles.

[0003] By the way, the hydrogen storage alloy includes a metal species A which easily forms a hydride by reacting with hydrogen, such as lanthanum, titanium and zirconium, and a metal species which hardly forms a hydride such as nickel and manganese. AB ₅ type, AB ₂ type, AB type and BCC type (body-centered cubic crystal structure) made of cobalt or the like are known.

[0004] Among these hydrogen storage alloys, LaNi ₅ alloy belonging to AB ₅ type shows excellent hydrogen storage characteristics,
The biggest disadvantage is that it is very expensive. Therefore, recently, a misch metal-nickel alloy containing a misch metal, which is a mixture of rare metals, has become the mainstream as a practical hydrogen storage alloy. However, the misch metal - nickel alloy, although it is less expensive than LaNi ₅ alloy, the hydrogen storage capacity and the discharge capacity, there is a drawback that can not be higher than the theoretical capacity of LaNi ₅ alloy.

[0005] On the other hand, AB ₂ type, AB-type, and BCC type nickel-containing hydrogen-absorbing alloy is small, the performance improvement of small-capacity secondary battery, a large capacity, while being expected as an electrode material as the key to the large batteries of It has not been put to practical use because it is highly toxic and forms a dense oxide on the surface to increase the hydrogen permeation resistance.

[0006] In addition, these AB ₂ type, AB-type and BC
Although the C-type nickel-containing hydrogen storage alloy generally has a large hydrogen storage amount, when used as a secondary battery, the nickel content originally in the alloy is small, so that ionic hydrogen (proton) and monoatomic hydrogen ( (Protium) has a drawback that it acts catalytically on the conversion between them and has a poor function of promoting the transmission of electrons.

[0007]

SUMMARY OF THE INVENTION The present invention overcomes the drawbacks of the conventional nickel-hydrogen batteries, and provides a novel nickel-hydrogen battery having electrochemical characteristics, long life and high durability. It is done for the purpose of.

[0008]

Means for Solving the Problems The present inventors have developed nickel-
In order to improve the electrical characteristics of the hydrogen storage alloy used as the negative electrode of the hydrogen battery, as a result of intensive research, a low initial discharge capacity of this hydrogen storage alloy and a sharp decrease in the discharge capacity during high-rate discharge, be due to the internal resistance larger for atomic hydrogen and electrons of the hydrogen storage alloy, the internal resistance, AB ₂ type, the AB-type or fluorination treatment of BCC-type nickel-containing hydrogen-absorbing alloy and AB ₅ type hydrogen storage alloy The problem can be solved by mixing a fluorinated material or using a material in which carbon black further fluorinated is mixed, and thus, nickel-
The inventors have found that the electrical characteristics of a negative electrode of a hydrogen battery are significantly improved, and have made the present invention based on this finding.

That is, the present invention provides (a) A
B ₂ type, at least one fluoride treatment of nickel-containing hydrogen storage alloy selected from among type AB and BCC type nickel-containing hydrogen storage alloy, (b) at least one AB ₅
The present invention provides a nickel-hydrogen battery using a nickel-containing hydrogen storage alloy electrode comprising a fluorinated product of a nickel-containing hydrogen storage alloy and carbon black optionally fluorinated.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a partially cutaway perspective view showing the structure of the nickel-hydrogen battery of the present invention.
Inside the bottomed cylindrical case 1, a negative electrode plate 2 made of a hydrogen storage alloy film and a positive electrode plate 3 made of nickel are stacked with a separator 4 interposed therebetween to form a column as a whole.
The upper part of the case 1 is sealed by a sealing plate 5, and a cap 7 is attached to the center of the case 1 via a safety valve 6. The case 1 is filled with an alkaline aqueous solution.

As the material of the positive electrode in the present invention, the same material as the positive electrode in a conventional nickel-cadmium electrode or a conventional nickel-hydrogen battery, for example, a nickel foam, can be used. ) AB
A fluorinated product of at least one nickel-containing hydrogen storage alloy selected from nickel-containing hydrogen storage alloys of type ₂ , AB or BCC; and (b) at least one AB ₅
It is necessary to use a hydrogen storage material composed of a nickel-containing hydrogen storage alloy and a fluorinated product.

The component (a) of the hydrogen storage material includes:
AB ₂ type, AB type or BCC containing nickel as a component
A fluorinated product of a type hydrogen storage alloy is used. This AB
Examples of the type ₂ nickel-containing hydrogen storage alloy include NiT
i ₂ , NiMg ₂ , NiZr _2, and some of these constituent metals are replaced with other metals, for example, Al, Co, Cr, Cu, Fe, L
a, Mg, Mn, Nb, Si, V, Zn, Zr, and the like. Examples of AB-type nickel-containing hydrogen storage alloys include TiNi, ZrN
i, VNi, NbNi, MmNi (where Mm is a misch metal) and some of these constituent metals are other metals such as Al, Ce, Co, Cr, Cu, Fe, Mg, Mn, M
Examples include those substituted with a metal other than at least one kind of constituent metal selected from o, V, Zn, Zr, and the like.

In addition, as a mixed type of AB type and AB ₂ type, TiNi.TiNi ₂ or a part of Ni therein is replaced with V, Zr, Cr, Mn, Co, Cu, Fe, etc. formula _{Ti 1-y Zr y Ni x} ( where 0.5
<X ≦ 1.45, 0 ≦ y ≦ 1) can also be used. Further, as an example of the BCC type nickel-containing hydrogen storage alloy, there is an alloy in which a part of constituent metals of a hexagonal TiAl alloy or a hexagonal MgZn ₂ alloy is replaced with Ni.

Generally, each metal component A, B of the hydrogen storage alloy
Is not always an integer ratio such as 1: 2, 1: 1 or the like, and may fluctuate in a range of ± 0.3. Can be used.

Preferred examples of the composition of these hydrogen storage alloys
Fe_0.8Mn_0.2Zr_0.05Ti, Fe_0.8Mn_0.18A
l_0.02Ni_0.05Ti, Ti_0.5Zr_0.5Mn_0.8Cr_0.8N
i_0.4, Ti_0.5Zr_0.5Mn_0.5Cr_0.5Ni, Ti_0.5Z
r_0.5V_0.75Ni_1.25, Ti_0.5Zr_0.5V_0.5Ni_1.5, N
i_0.95Fe_0.8Mn_0.2Zr_0.05Ti_Two, Ni_0.95Fe_0.8
Mn_0.18Al_0.02Zr_0.05Ti, Zr_0.9Ti_0.1V_0.2
Co_0.1Mn_0.6Ni_1.1, ZrMn_0.6Cr_0.2Ni_1.2,
ZrMn_0.5Cr_0.2V_0.1Ni_1.2, ZrV_0.4Ni _1.6,
Ti_0.17Zr_0.16V_0.22Ni_0.39Cr_0.07, ZrNi
_1.43, Ti_0.5Zr_0.5(V_0.375Ni_0.625)_TwoEtc.
Can be

These AB ₂ type, AB type or BCC type nickel-containing hydrogen-absorbing alloys generally have a large hydrogen-absorbing power, but when used as a secondary battery electrode material, the nickel content in the alloy component is originally low. Due to the small amount, there is a drawback that it has a function of catalyzing the conversion between ionic hydrogen (proton) and monatomic hydrogen (protium) and has a poor function of promoting the transmission of electrons (electrons).

Next, as the component (b), a fluorinated AB ₅ type hydrogen storage alloy containing nickel as a component is used. As the AB ₅ type nickel-containing hydrogen storage _{alloy, La 1-x Mm x Ni} 5 ( where x is a number of 0 _{≦ x ≦ 1), Ca 1} -x Mm x Ni 5 ( where x is 0 <x <1 ),
Mm _x (where M is Ni, Co, Mn, Al, 4.5
5 ≦ x ≦ 4.76), Ca _1-x Mg _x Ni _y (however, 0
<X ≦ 0.27, 3.8 ≦ y ≦ 5.2), Ca _1-x La _x
Ni _{5- (y + z)} Al _y Co _z (provided that 0.5 ≦ x ≦ 0.
9, 0 ≦ y ≦ 0.4, 0 ≦ z ≦ 0.4, 0 <y + z ≦
4) and some of these constituent metals are replaced with other metals such as A
1, Ce, Co, Cr, Cu, Fe, Mg, Mn, M
Some are replaced with metals other than at least one kind of constituent metal selected from o, V, Zn, Zr, and the like. Also in these hydrogen storage alloys, the atomic ratio of each of the metal components A and B is not always an integer ratio of 1: 5, and is ± 0.1.
Although it may fluctuate within the range of 3, such a thing can be used in the present invention.

Among such nickel-containing hydrogen-absorbing alloys, examples of preferred LaNi ₅ -based alloys include LaNi ₅ ,
LaNi ₄ Cu, LaNi ₄ Al, LaNi _2.5 Co _2.5 ,
LaNi _2.5 Co _2.4 Al _0.1 , LaNi _4.7 Al _0.3 , La
_0.9 Zr _0.1 Ni _4.5 Al _0.5 , La _0.8 Nd _0.2 Ni ₂ C
o ₃ , La _0.8 Nd _0.2 Ni _2.5 Co _2.4 Al _0.1 , La _0.8
Nd _0.15 Zr _0.05 Ni _3.8 Co _0.7 Al _0.5 , La _0.7 Nd
_0.2 Ti _0.1 Ni _2.5 Co _2.4 Al _0.1 , La _0.8 Nd _0.2 N
i _2.5 Co _2.4 Si _0.1 , La _0.8 Ce _0.2 Ni ₅ , La _0.6
Ce _0.4 Ni ₅ , La _0.5 Ce _0.5 Ni ₅ , La _0.6 Pr _0.4 N
i ₅ , La _0.6 Nd _0.4 Ni ₅ , La _0.6 Pm _0.4 Ni ₅ , L
a _0.6 Sm _0.4 Ni ₅ , Ca _0.4 La _0.6 Ni ₅ , Ca _0.4 L
a _0.6 Ni _4.8 Al _0.1 Co _0.1 , Ca _0.8 La _0.2 Ni _4.5
Co _0.5 , LaNi _4.7 Al _0.3 and the like. These particularly preferred in are those containing rare earth metals as the A of AB _5, for example, misch metal (Mm). Such materials include MmNi _3.55 Co _0.75 Mn _0.4 Al _0.3 ,
MmNi _3.5 Co _0.7 Al _0.8 , MmNi _3.5 Co _0.8 Mn
_0.4 Al _0.3 , Mm _0.85 Zr _0.15 Ni _4.0 Al _0.8 V _0.2 ,
MmNi _3.7 Al _0.5 Fe _0.7 Cu _0.1 and the like.

When used as a negative electrode in the present invention, it is necessary that the hydrogen storage alloys of the above components (a) and (b) are both fluorinated. This fluorination treatment is performed by a known method such as M ₃ AlF ₆ ,
A metal fluoride compound represented by M ₂ TiF ₆ or M ₂ ZrF ₆ (where M is an alkali metal such as potassium or sodium) is reduced to a weight / volume ratio (w / v) of about 0.01 to 0.5. The nickel-containing hydrogen storage alloy particles are immersed in a supersaturated aqueous solution dissolved in water so that
C., preferably at 15 to 40.degree. C. for 0.5 to 5 hours (JP-A-5-213601), containing 0.2 to 10.0% by weight of alkali fluoride and adjusting the pH to 2 with hydrogen fluoride. In an aqueous solution adjusted to 0.0 to 6.5, the nickel-containing hydrogen-absorbing alloy granules were placed at 0 to 80 ° C under normal pressure.
Preferably, it can be easily carried out by a method of maintaining the temperature at 30 to 60 ° C. for 1 to 60 minutes (JP-A-9-302478). By such a treatment, a metal nickel-rich metal fluoride layer having a thickness of 0.01 to 1 μm is formed on the surface of each alloy particle.

In this fluorination treatment, the components (a) and (b) may be separately applied, and then both may be mixed. Alternatively, the components (a) and (b) may be mixed. May be applied to the mixture. When the component (a) and the component (b) are preliminarily mixed and the mixture is subjected to fluorination treatment, even if the AB ₂ type, AB type or BCC type hydrogen storage alloy does not contain nickel, it is not fluorinated. During the conversion process,
(B) nickel in the component is eluted into the processing solution once,
Since this forms a fluoride film on the surface of each alloy particle, the AB ₂ type, AB type or BCC type hydrogen storage alloy used as a raw material may not contain nickel. The fluorinated hydrogen storage alloy of the components (a) and (b) is usually formed as a granular material having an average particle size of 30 μm or less. If the particle size is larger than this, the fluorination treatment becomes insufficient, and the desired effect cannot be obtained.

In the hydrogen storage alloy thus fluorinated, the oxide is removed from the surface and, at the same time, nickel is dispersed on the surface as desired, so that it is stabilized. The resistance to corrosion, pulverization, decay, poisoning, ignition and the like is improved, and the hydrogen storage performance is maintained for a long period of time.

When used as the negative electrode of the present invention, the components (a) and (b) are in a weight ratio of 100: 1 to 1: 1.
00 are mixed. If the amount of the component (a) is smaller than this, the hydrogen storage capacity and charge / discharge capacity become insufficient, and if the amount of the component (b) is smaller than this, the effect of reducing the transfer resistance of hydrogen atoms and electrons is reduced. And high-speed emission and improvement of high-rate photoelectricity are hardly obtained. When the component (a) is added to the component (b), the hydrogen storage capacity and the charge / discharge capacity of the component (b) increase in proportion to the amount of the component (a). While maintaining the characteristics of the component and the component (b), more preferable characteristics can be imparted than in the case of the component (b) alone. Therefore, their mixing ratio can be appropriately selected in a wide range according to a desired purpose.

Next, in the present invention, the aforementioned (a)
By blending fluorinated carbon black in addition to the component and the component (b), the performance can be further improved. This fluorinated carbon black is subjected to fluorination treatment of ordinary carbon black such as furnace carbon black, channel carbon black, acetylene carbon black, and arc carbon black in the same manner as in the case of the above-described fluorination treatment of the hydrogen storage alloy. It can be obtained by:

The fluorinated carbon black is used in an amount of 1 to 10 parts by weight based on the total weight of the components (a) and (b).
When blended at a ratio of 10% by weight, high-speed hydrogen release characteristics and high-rate discharge characteristics can be significantly improved. The negative electrode of the present invention can be prepared by adding a binder at a ratio of 2 to 10% by weight to such a hydrogen storage alloy and compression molding. The binder used at this time may be either a thermoplastic resin or a thermosetting resin, but is preferably a binder that is stable for a long time even in contact with an electrolytic solution, for example, polytetrafluoroethylene. The electrode obtained in this way has excellent initial charge / discharge characteristics and hydrogen release characteristics under high-speed conditions,
It has the advantages of maintaining a high discharge capacity under a high discharge current, and low internal resistance during charge / discharge.

The electrolyte in the nickel-hydrogen battery of the present invention can be arbitrarily selected from those used in conventional nickel-cadmium batteries and nickel-hydrogen batteries, and is not particularly limited.

[0026]

Next, the present invention will be described in more detail by way of examples.

Note that the ampere-hour efficiency (A
h) and voltage (V) are measured according to JIS C8708-1.
997.

[0028] Reference Example 1 AB ₂ type _{alloys, Zr 0.9 Ti 0.1 V 0.2 Co} 0.1 Mn
The _0.6 Ni _1.1, as AB ₅ type alloys, LaNi _4.7 Al
_{Using 0.3} , both of them (weight ratio 100: 5) were each pulverized to a particle size of 30 μm by mechanical pulverization. Next, the granular material thus obtained is sealed in a reaction vessel for Giebert PcT measurement, hydrogenated at 30 ° C. by injecting 2.5 MPa of hydrogen gas, and then the internal hydrogen is evacuated. After repeating the operation of pulling and degassing 5 times, the granular material 5 was removed at room temperature.
0 g of fluorinated solution (KF 1% by weight aqueous solution is HF
The mixture was added to 1000 ml of water, and stirred until the pH value changed from 5.0 to 7.5 to prepare a hydrogen storage material.

Reference Example 2 As an AB type alloy, Ti _0.70 Zr _0.30 Mn _0.25 Ni _0.55
The V _0.13 Co _0.07, the AB ₅ type alloys, LaNi _4.7 A
Using _0.3 , both of them (weight ratio: 100: 5) were pulverized by mechanical pulverization to a particle size of 30 μm. Next, the granular material thus obtained is sealed in a reaction vessel for Giebert PcT measurement, hydrogenated at 30 ° C. by injecting 2.5 MPa of hydrogen gas, and then the internal hydrogen is evacuated. After the operation of pulling and degassing was repeated 5 times, 50 g of the granular material was treated at room temperature with a fluorinated solution (aqueous solution containing 1% by weight of KF as H
Adjust to pH 5 with F)
A hydrogen storage material was prepared by stirring until the value changed from 5.2 to 7.2.

Example 1, Comparative Example 1 A nickel-hydrogen battery having the structure shown in FIG. 1 was manufactured as follows. That is, 1% by weight of carboxymethylcellulose (CMC) and an appropriate amount of water were added to the hydrogen storage material obtained in Reference Example 1 to form a paste, which was applied to a commercially available nickel-plated punched iron plate, and roller-pressed through a slit. Hydrogen storage alloy negative electrode 2 having an average thickness of 0.4 mm
Was prepared. Next, using a commercially available foamed nickel electrode (600 mah / cc) as the positive electrode 3 and a polypropylene film (150 μm thickness) as the separator 4, a sealed cylindrical nickel battery (International Standard Sub-C) was constructed. Lithium oxide aqueous solution was charged. After leaving the battery at 30 ° C. overnight, the battery was charged at 0.1 C for 18 hours.
The battery of Example 1 was manufactured by repeating the operation of discharging at a terminal voltage of 0.9 V at 2 C twice. Next, for comparison, a negative electrode was produced using an alloy having the same composition as in Example 1 and a hydrogen storage material not subjected to fluorination treatment, and a battery of Comparative Example 1 was produced in the same manner. The battery characteristics were measured and the results are shown in Table 1. Note that 1C, 2
C and 3C mean the discharge capacity for 1 hour, 2 hours or 3 hours, respectively.

[0031]

[Table 1]

Next, gas absorption characteristics during quick charging were examined. In Example 1, the internal pressure was 3 kgf / cm ² , whereas in Comparative Example 1, the negative electrode was rate-determined, so that the pressure resistance of the safety valve was 15 kg or more, and gas leakage occurred, making it unusable for practical use. In order to make this battery a practical level, it is necessary to repeat charging and discharging about 20 times.
Much less practical than cycles. In addition, with respect to a short circuit caused by a metal component eluted from the positive electrode or the negative electrode, when the nickel-containing hydrogen storage alloy is left at a high temperature for a long period of time, the elution metal normally passes through the separator, so that charging becomes impossible. The batteries of Example 1 and Comparative Example 1 were discharged at 0.2 C and then left at 60 ° C. in a circuit state. When the battery of Comparative Example 1 became 0 V in two weeks, the battery of Example 1 lost one month. Even after standing, 1V was shown. As described above, when the hydrogen storage alloy is fluorinated, components that may cause a short circuit are eluted, so that a short circuit does not occur when the battery is left after being constructed.

Example 2, Comparative Example 2 To the hydrogen storage material obtained in Reference Example 2, 1% by weight of carboxymethyl cellulose (CMC) and an appropriate amount of water were added to form a paste, which was applied to a commercially available nickel-plated punched iron plate. Then, a roller is pressed through a slit to obtain an average thickness of 0.1 mm.
A 4 mm hydrogen storage alloy negative electrode 2 was produced. Next, a commercially available foamed nickel electrode (600 mah / cc) is used as the positive electrode 3.
Using a polypropylene film (thickness: 150 μm) as the separator 4, the same sealed cylindrical nickel battery as in Example 1 was formed, and an aqueous lithium hydroxide solution was filled as an electrolyte. After leaving this battery at 30 ° C. overnight, 0.1 C
The battery of Example 2 was manufactured by repeating the operation of charging for 18 hours and discharging at 0.2 C between terminal voltages of 0.9 V twice. Next, for comparison, a negative electrode was produced using an alloy having the same composition as in Example 2 and a hydrogen storage material not subjected to fluorination treatment, and a battery of Comparative Example 2 was produced in the same manner.
The battery characteristics were measured, and the results are shown in Table 2.

[0034]

[Table 2]

As is clear from this table, the battery of Example 2 has much better discharge capacity and higher rate discharge than the battery of Comparative Example 2.

[Brief description of the drawings]

FIG. 1 is a partially cutaway perspective view showing the structure of a nickel-hydrogen battery of the present invention.

[Description of Signs] 1 case 2 negative electrode plate (hydrogen storage alloy) 3 positive electrode plate (nickel) 4 separator 5 sealing plate 6 safety valve 7 cap

Claims (4)

[Claims] 1. A negative electrode as (a) AB ₂ type, at least one fluoride treatment of nickel-containing hydrogen storage alloy selected from among type AB and BCC type nickel-containing hydrogen storage alloy, (b) at least hydrogen battery - nickel characterized by using a nickel-containing hydrogen storage alloy mixture consisting of fluoride treatment of one AB ₅ type nickel-containing hydrogen storage alloy. 2. An AB ₂ type Laves phase nickel-containing hydrogen storage alloy whose component (a) has been fluorinated, an AB type titanium-based nickel-containing hydrogen storage alloy that has been fluorinated, and an AB type zirconium that has been fluorinated. At least one selected from the group consisting of nickel-containing hydrogen storage alloys, and (b)
Hydrogen battery - nickel in the component according to claim 1, wherein at least one selected from the AB ₅ type rare earth-nickel containing hydrogen-absorbing alloy which has been fluorinated. 3. The nickel-metal hydride battery according to claim 2, wherein the content ratio of component (a) to component (b) is in the range of 100: 1 to 1: 100 by weight. 4. The hydrogen-absorbing alloy electrode is 1 to 3 based on the total weight.
4. The nickel-hydrogen battery according to claim 1, comprising 10% by weight of fluorinated carbon black.