JP3734117B2 - Hydrogen storage alloy electrode - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a hydrogen storage alloy electrode using a hydrogen storage alloy that reversibly stores and releases hydrogen, and is used for a nickel-hydrogen secondary battery and the like.
[0002]
[Prior art]
In recent years, the use of electric vehicles has been taken up as one of the methods for preventing the progress of air pollution by gasoline engine vehicles and the like. In particular, in the United States, a bill stipulating that 10% of the sales volume of gasoline engine vehicles in California is required to be electric vehicles has been passed, and similar bills have been adopted in other states. Expectations for are increasing. Since this electric vehicle is required to have performance equivalent to that of a gasoline engine vehicle, the performance of the power source for the electric vehicle that greatly affects the performance is regarded as very important. The following seven items are listed as main basic performance required for the electric vehicle and its power supply.
(1) One charging mileage is long (energy density is high)
(2) Excellent acceleration and climbing performance (Excellent power density and high rate discharge characteristics)
(3) Can be used in various climatic environments (excellent temperature characteristics)
(4) Less repairs such as battery replacement (long cycle life)
(5) Do not pollute the environment (do not contain harmful substances)
(6) The price should be usable by general users (low cost)
(7) Be safe (high safety)
Currently, various batteries are being investigated as power sources for electric vehicles. However, nickel-metal hydride batteries using a hydrogen storage electrode as the negative electrode have a high energy density, a long cycle life, no harmful substances, and safety. From the standpoint of safety, it is attracting attention as the most promising candidate for electric vehicle power sources.
[0003]
This nickel metal hydride battery mainly uses a hydrogen storage alloy electrode obtained by applying a paste mainly composed of a hydrogen storage alloy to a punching metal conductive core obtained by nickel plating on iron.
[0004]
[Problems to be solved by the invention]
Punching metal in which nickel is plated on iron accounts for 6 to 13% of the volume of the hydrogen storage alloy electrode, restricts the amount of the hydrogen storage alloy as a reactant, and hinders high energy density. . When a conventional punching metal having a thickness of 0.06 to 0.10 mm and an aperture ratio of 31 to 46% is used to produce an electrode plate having a thickness of 0.55 mm, the volume occupied by the hydrogen storage alloy electrode of the conductive core is 6 to It accounts for 13%. If the thickness of the conductive core is reduced, the occupation ratio is reduced, and the hydrogen storage alloy is applied accordingly, the energy density increases. However, if the thickness is reduced, the resistance of the conductive core increases, so that the power density and high-rate discharge performance required for an electric vehicle are reduced, and acceleration and climbing performance are deteriorated. In order to prevent this, a nickel foil or the like having excellent electrical conductivity may be used. However, in order to make a thin foil, there is a drawback that the cost increases because the number of rolling increases.
[0005]
The present invention has been made in view of the above problems. By using a conductive core that is thin and excellent in conductivity and inexpensive, a hydrogen storage alloy electrode that has high energy density and excellent high-rate discharge performance can be obtained at low cost. It is to provide.
[0006]
[Means for Solving the Problems]
To achieve the above object, the hydrogen storage alloy electrode of the present invention, the metallic nickel powder powder paste is formed by sintering the sheet, and, to the conductive core which circular holes are formed a large number of hydrogen It is an electrode to which a paste mainly composed of a storage alloy is applied.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
The metallic nickel powder powder, after a paste with a thickening agent, passed through rolls circular protrusions are formed a large number, and sheet-like circular hole is formed. This is sintered in a reducing atmosphere to obtain a conductive core. Incidentally, without the metallic nickel powder powder and paste, the metallic nickel powder powder directly formed into a sheet may be sintered.
[0008]
This conductive core does not require many rolling processes, and has the advantage that the manufacturing process is simplified and the cost is reduced. Moreover, when it uses as a conductive core of a hydrogen storage alloy electrode, a high capacity | capacitance electrode can be obtained, maintaining the conventional output.
[0009]
【Example】
Embodiments of the present invention will be described below with reference to the drawings.
[0010]
FIG. 1 is a schematic view of an apparatus for producing a nickel sintered conductive core used for a hydrogen storage alloy electrode. The hydrogen storage alloy electrode of the present invention is a sheet 3 in which circular holes are formed by passing a paste 1 in which metallic nickel powder is added with a 1% aqueous solution of carboxymethyl cellulose through a roll 2 having a large number of circular protrusions. . This was sintered in a reduction furnace 4 at 1400 ° C. and then adjusted with a thickness adjusting roll 5, and a large number of circular holes having a diameter of 1.5 mm were formed, and the opening ratio was 46% and the thickness was 0.07 mm. A core body 6 was formed. FIG. 2 is a perspective view of a nickel sintered conductive core used for the hydrogen storage alloy electrode of the present invention. A predetermined amount of a paste prepared by adding a 1% aqueous solution of carboxymethyl cellulose as a thickener to a hydrogen storage alloy was applied to both sides of this conductive core, and after drying, pressing was performed to obtain 40 mm (length) × 30 mm ( Horizontal) × 0.55 mm (thickness) hydrogen storage alloy electrode of the present invention.
[0011]
Also, for comparison, a punching metal conductive core having an aperture ratio of 46% in which a number of circular holes having a thickness of 0.1 mm and a diameter of 1.5 mm formed by nickel plating on iron are formed. Similarly, a hydrogen storage alloy electrode of 40 mm (length) × 30 mm (width) × 0.55 mm (thickness) was produced.
[0012]
In order to investigate the high rate discharge characteristics of these hydrogen storage alloy electrodes, a paste-type nickel electrode was used as a counter electrode, and the hydrogen storage alloy electrode and the nickel electrode were disposed via a separator to constitute an open type battery. An electrolytic solution composed of a 6.8N potassium hydroxide aqueous solution was poured into this. This electrode was charged to 120% at a rate of 0.1 C, and discharged to -600 mV with respect to the mercury / mercury oxide reference electrode at rates of 0.2 C and 2 C.
[0013]
FIG. 3 is a diagram showing the discharge characteristics of each electrode at 0.2C rate and 2C rate. It can be seen that the electrode of the present invention has a higher capacity than the comparative example, although the discharge voltage does not decrease despite the fact that the electrode has the same dimensions.
[0014]
【The invention's effect】
As described above, the present invention uses a conductive core formed by sintering metallic nickel powder or metallic nickel fiber into a sheet, so that it is excellent in conductivity even at a thin thickness and can be manufactured at low cost. A hydrogen storage alloy electrode in which a paste mainly composed of a hydrogen storage alloy is applied to the core is excellent in high-rate discharge characteristics, and can provide a high energy density electrode at a low cost, and therefore has a great industrial value.
[Brief description of the drawings]
FIG. 1 is a schematic view of an apparatus for producing a nickel sintered conductive core used for a hydrogen storage alloy electrode of the present invention.
FIG. 2 is a perspective view of a nickel sintered conductive core used for the hydrogen storage alloy electrode of the present invention.
FIG. 3 is a graph showing discharge characteristics of the present invention and a comparative example.
[Explanation of symbols]
1 Paste 2 Roll 3 Sheet 4 Reduction furnace 5 Thickness roll 6 Conductive core

Claims (1)

The metallic nickel powder powder formed by sintering the sheet, and the hydrogen storage alloy, wherein a circular hole is a large number formed conductive core, and applying a paste consisting mainly of hydrogen storage alloy electrode.

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