JP3030146B2 - Electrode - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrode, and more particularly to an improvement in a binding means for binding a powdery electrode material and a base material via a binder.

[0002]

2. Description of the Related Art Some electrodes have a structure in which a powdery electrode material and a base material are integrated through a binder through a binder. Alloy electrodes are one of them. This hydrogen storage alloy electrode is a reversible electrode obtained by binding a hydrogen storage alloy powder and a porous core (substrate) via a binder, and has a high energy density per volume and therefore has a high capacity. It has been proposed that a nickel / hydrogen storage alloy electrode battery be applied to a negative electrode because of the possibility of occurrence of environmental pollution and the like.

The following method (1) is used to fabricate a hydrogen storage alloy electrode in this nickel / hydrogen storage alloy electrode battery.
Methods (3) to (3) have been proposed. (1) A mixture of a hydrogen storage alloy powder and a solution obtained by dissolving a binder powder in a solvent to form a slurry, which is made of a nickel-made punched metal or foamed metal core (base material)
After drying, the solvent is removed by evaporation. (2) After filling a mixture of a hydrogen storage alloy powder and a binder powder into a core, the mixture is pressed into a sheet and then 360 °
A method of firing at a temperature of about C. (3) A method in which a hydrogen absorbing alloy powder is filled in a core body, then pressed into a sheet, and then sintered at a temperature of about 900 ° C.

However, according to the above method (1), most of the surface of the hydrogen storage alloy powder is covered with the binder, and as a result, the hydrogen and the hydrogen storage alloy are occluded by oxygen generated at the positive electrode during charging. Since the reaction speed with hydrogen slows down and the internal pressure of the battery rises, there are problems such as not only lack of safety but also deterioration of battery characteristics.
This problem is particularly noticeable in the case of quick charging or overcharging. Further, since the effective surface area of the electrode is reduced, the utilization rate of hydrogen as an active material is reduced, and a large current cannot be obtained.

[0005] The above-mentioned methods (2) and (3) have solved the problem of the excessive coating on the surface of the hydrogen storage alloy by heat treatment. These methods also have the following problems. That is, in the method (2), the surface of the hydrogen storage alloy is oxidized, so that it becomes difficult to exhibit the original characteristics as an electrode. In the method (3),
In addition to this problem of surface oxidation, the physical properties themselves change due to the so-called annealing effect, so that it is difficult for the hydrogen storage alloy to exhibit the characteristics that should be originally exhibited.

[0006] The problems such as the excessive coating of the electrode material and the surface oxidation as described above are not limited to the above-described hydrogen storage alloy electrodes, but are common to the electrodes using a powdery substance as the electrode material. . The present invention has been made in view of the above circumstances, and it is intended that the surface of the electrode material is not excessively coated, and that the surface is hardly oxidized, for example, as a battery electrode. It is intended to provide an electrode suitable for use.

[0007]

According to the present invention, there is provided an electrode comprising a powdery electrode material and a base material integrated with a binder, wherein the powdery electrode is The material and the base material are integrated by melting the binder with an ultrasonic wave to such an extent that the surface of the powdery electrode material is not excessively coated, and then drying and solidifying the binder. It is characterized by having been done.

[0008] As the powdered electrode material, TiFe,
TiCo, ZrMn ₂ , ZrV ₂ , CaNi ₅ , LaN
i _5, MmNi ₅ (Mm: misch metal), Mg ₂ N
i, Mg ₂ Cu and the like are typical examples, but not limited to these, binding such as manganese dioxide powder (positive electrode material), zinc powder (negative electrode material), carbon powder (positive electrode or negative electrode material), etc. A material which is kneaded with an agent (and, if necessary, a conductive agent) and then bound to the substrate, and which has a problem in terms of battery characteristics that the material surface is excessively covered with the binder. Then, it is included in the electrode material of the present invention.

Examples of the substrate include various metal materials having excellent conductivity, such as an aluminum plate, a copper plate, nickel foam, and a punched metal made of nickel, which are conventionally used as a core material of a battery electrode.

Examples of the binder include resin powders which are solid at room temperature, such as PEO (polyethylene oxide), fluororesin such as PTFE (polytetrafluoroethylene) and PVF (polyvinylidene fluoride). When a hydrogen storage alloy powder is used as the powdered electrode material, it is preferable to use a binder having a melting point of 500 ° C. or lower, more preferably 300 ° C. or lower, in order to prevent oxidation of the alloy surface.

In the present invention, vibration energy by ultrasonic waves is used as a means for melting the binder, but in order to achieve the above-mentioned object of the present invention, the vibration applied to the binder is required. The amount of energy, or frequency,
It is necessary to appropriately select the type according to the type of the binder used. That is, in consideration of the molecular weight of the binder, which is a polymer compound, the fluidity at the time of melting, the melting point, and, if necessary, the glass transition point, the electrode material can be bound to such an extent that the electrode material does not fall off the substrate,
In addition, it is necessary to select the frequency of the ultrasonic waves and the time for using them so that the surface of the electrode material is not excessively coated so as to adversely affect the electrode characteristics.

Next, a specific method for manufacturing an electrode according to the present invention will be described by taking as an example a case where a hydrogen storage alloy electrode is manufactured by a batch method. First, a hydrogen storage alloy powder and P were added to a porous base material such as foamed nickel or nickel punched metal.
An appropriate amount of a mixture with a binder powder such as EO, PTFE, or PVF is filled. Next, both terminals of an ultrasonic oscillator are brought into contact with the above-mentioned base material, and ultrasonic waves of an appropriate frequency are applied over a predetermined period of time to give a fine vibration to the binder to be contained, thereby melting the binder. After drying the melted binder, it is processed into a predetermined thickness by a rolling roll to form an electrode.

In the actual production of electrodes, a continuous production system is adopted in which an endless core material is fed to a rolling roll to produce electrodes. As described above, as a method of manufacturing the electrode according to the present invention by continuously operating the production line without stopping, the terminal of the ultrasonic oscillator is connected to the roll shaft of the rolling roll, and the ultrasonic vibration is applied thereto. For example, a method of indirectly applying micro-vibration to the core material by giving the same may be used.

Among the electrodes according to the present invention, an electrode using a hydrogen storage alloy as a powdery electrode material can be suitably used as a negative electrode of a nickel / hydrogen storage alloy electrode battery. In this case, as the positive electrode, the electrolyte, and the separator, the same materials as those used in nickel / hydrogen batteries which have been already practically used can be used.

[0015]

In the electrode according to the present invention, ultrasonic conditions are appropriately set so that the surface of the electrode material is not excessively coated when the binder is melted, and the electrode material and the base material are integrated. Because of this, the effective surface area as an electrode is large. Further, since no heat treatment such as sintering or sintering is performed in the manufacturing stage, the surface oxidation and the change in physical properties of the electrode material are small.

[0016]

The electrode according to the present invention has not been subjected to heat treatment such as sintering and sintering in the manufacturing stage, so that the electrode material has almost no surface oxidation or change in physical properties, and can be used for a battery electrode or the like. It is suitable. In addition, since the electrode surface is not excessively covered with the binder, the effective surface area of the electrode is large, so that the utilization rate of hydrogen is high and a large current can be taken out. In particular, when the hydrogen storage alloy electrode according to the present invention is used as a negative electrode of a nickel / hydrogen storage alloy electrode, the reaction between oxygen generated at the positive electrode during charging and hydrogen stored by the hydrogen storage alloy can be efficiently performed. It is safe because there is no increase in internal pressure. As described in detail above, the present invention has excellent unique effects.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Fugo Mizutaki, 2-18-18 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (72) Yoshinori Matsuura 2--18 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (72) Inventor Koji Nishio 2-18-18 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (72) Nobuhiro Furukawa 2--18 Keihanhondori, Moriguchi-shi, Osaka (56) References JP-A-53-112433 (JP, A) JP-A-58-73966 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01M 4 / 02-4/08 H01M 4/16-4/34

Claims (3)

(57) [Claims] 1. An electrode in which a powdered electrode material and a base material are integrated with a binder, wherein the powdered electrode material and the base material are superposed on the surface of the powdered electrode material by ultrasonic waves. An electrode, wherein the electrode is integrated by melting the binder to such an extent that it is not excessively coated, and then drying and solidifying the binder. 2. The electrode according to claim 1, wherein said powdery electrode material is a hydrogen storage alloy. 3. The electrode according to claim 1, wherein said binder is a polyethylene oxide or a fluororesin.