JPS6380474A - Manufacture of electrode for cell - Google Patents

Abstract

PURPOSE:To make it possible to electrically charge the electrode in the caption to heighten its energy density by pressing a powdered conductive polymer on a collector made of a grid-shaped metal body for being made into an electrode active material. CONSTITUTION:A powdered conductive polymer is fixed to a collector from its both sides by means of a press in the form of burrying the collector made of a grid-shaped metal body therein by using a powdered conductive polymer synthesized by an electrochemical or chemical method. As the conductive polymer, polyaniline, polypyrrole or polyazurine is used. And, when pressing conductive polymer powder on the collector, pressing pressure is so set up that active material density may be as high as possible to be more than 1.0g/cc.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for manufacturing an electrode for a plastic battery that is rechargeable and has a high gravitational energy density and a high volumetric energy density.

(Prior art and its problems) With the spread of electronic devices in recent years, smaller and lighter batteries have come to be used for various purposes. In particular, lithium batteries have a high energy density, so the demand for them has been increasing rapidly recently.

Along with this, there has been a strong desire to convert the conventional lithium battery, which is a secondary Ti battery, into a secondary battery.

By the way, recently, by using organic polymer materials such as polyacetylene and polyaniline as electrode active materials, u! It has been found that rechargeable batteries can be produced in m (AJ, MacDIar+sld et al.).

J, EIectrochem, Soc, v, +28
p, 1851 (19B+)).

When these electrode materials use lithium as a negative electrode, a secondary battery with high energy density can be obtained, and therefore, their practical application is strongly desired. However, conventional batteries constructed using organic polymer materials as electrode active materials use film-like materials obtained by the so-called Yamakawa method or electrolytic method, but although these materials are lightweight, However, the density was as low as 0.2-0.5 g/cc, making it difficult to miniaturize the battery. Furthermore, the maximum thickness of the film obtained in this way is approximately 0.51 square meters, so in order to increase the capacity of the battery, the area of the film must be extremely thick. This was a turning point in the production of batteries.For this reason, the batteries that were actually manufactured had a power rating of several mAH, which made them unusable for practical use. Attempts have been made to increase the density of the active material by pressing film materials to increase the density of the active material, but increasing the density of the film material always resulted in deterioration of battery characteristics. This is due to the characteristics of the doping/dedoping reaction, which is a charging/discharging reaction of polymeric materials.In other words, this reaction is generally (P) n+nyA -+ (PAy) n+nye
It is expressed as Here, P is a repeating unit of a polymer, n is a degree of polymerization, y is a dope ffi, and A is an ion serving as a dopant. Here, in order to achieve a high energy density with an open circuit voltage of 3.5 V or more when lithium is used as a counter electrode, it is necessary to use a dopant that serves as a so-called acceptor. For this, CI as A
An anion with a large ionic radius such as 04 + BF4 + PF* + AsF5 must be used. In order for these ions to undergo the above reaction with the polymer material, the solvated and larger ions must penetrate well into the interior of the polymer film. Therefore, the solid structure of the polymer is required to be quite porous. However, such terms are incompatible with the demand for higher energy density, and a solution to this problem has been strongly desired.

(Means for Solving the Problem) In view of the above-mentioned circumstances, the present inventors have conducted intensive research and have discovered a method for manufacturing an electrode that has a high active material density and rapid ion diffusion, and has developed a method for manufacturing an electrode that is rechargeable and has an energy density. This led to the creation of high-quality plastic batteries.

The present invention is a method for manufacturing an electrode for a battery, characterized in that a powdery conductive polymer is fixed on a current collector made of a grid-like metal body by pressing to form an electrode active material. Using a powdered conductive polymer synthesized by a chemical method or a chemical method, the powdered conductive polymer is embedded in a current collector made of a lattice-shaped metal body. The above electrode is manufactured by fixing the current collector from both sides using a press.

Examples of the Tri-conducting polymer in the present invention include polyaniline, polypyrrole, polyazulene, etc. polymerized by an electrochemical method or a chemical method. These are preferably synthesized by an electrochemical method, so-called electrolytic polymerization method, in which monomers such as aniline, pyrrole, azulene, etc. are combined with either hexafluorophosphate, perchlorate, or tetrafluoroborate. It is obtained as a precipitate by anodic oxidation in an electrolyte solution dissolved in a suitable solvent. Preferred solvents include water and virol in the case of aniline, and propylene carbonate and acetonitrile in the case of azulene. As the electrolysis method, a constant potential method is particularly preferable, and the potential is 400 mV to 10
00+sV is particularly preferred. Nickel or platinum is preferred as the substrate electrode for electrodeposition.

The synthesized conductive polymer is thoroughly washed in pure water, dried at 100° C. or less, and then ground in a mortar or ball mill to form a powder. The particle size of the powder is 100 to 100% from the viewpoint of density with the current collector, active material density, and strength as an electrode.
200 mesh is preferred.

The lattice-shaped metal body used as a current collector is not only lightweight and inexpensive, but also has sufficient mechanical strength due to the process of winding 7R1 poles in a spiral shape.
It must also have great flexibility. Furthermore, in some cases, it is often preferable to deposit a conductive polymer on the current collector as an undercoat before applying the conductive polymer to the current collector by pressing. The lattice metal body used as a current collector is preferably one capable of electrodepositing a conductive polymer in the above-mentioned electrodeposition solution.

As materials that meet these requirements, nickel mesh, nickel lattice obtained by punching, nickel expanded metal, etc. are particularly preferred, and nickel mesh is most preferred.

When pressing the conductive polymer powder onto the current collector, it is desirable to set the pressing pressure so that the active material density is as high as possible, preferably 1.0 g/cc or more. Note that if the active material density is less than 1.0 g/cc, the strength as an electrode and the reduction in size of the electrode will be insufficient. Normal press pressure is 2
~3t/cJ, preferably 2.3~? , 5
t/eJ, and for example, in a small 7ri pond, it is preferable to form a circular tube with 90 to 110 mg of conductive polymer powder per 1 cJ. This results in an average thickness of 0.6 to 0.81
It is possible to manufacture electrodes that retain active materials. In the case of large batteries, conductive polymer powder of 200 mg/cJ or more may be made into a circular tube. In either case, the density of the electrode active material is 1.0 to 1.5 g/cc.

When manufacturing a battery using the electrode manufactured by the method of the present invention, it is preferable to use lithium as the negative electrode active material in order to obtain high energy density. As the electrolyte, it is preferable to use lithium tetrafluoroborate, lithium hexafluorophosphate, lithium hexafluoride arsenic, lithium perchlorate, or a mixture thereof. Preferred solvents are dimethoxyethane, propylene carbonate, tetrahydrofuran, sulfolane, trimethylformamide, or mixtures thereof.

(Operations and Effects of the Invention) The electrode manufactured by the method of the present invention does not use a conductive material to improve the conductivity of the electrode or a viscous material to increase the strength of the electrode. The active material density a is much higher than that of electrodes using polymeric materials, so the electrode can be significantly miniaturized and can be spirally wound without peeling or cracking.

Furthermore, despite the high density of the active material, the electrolytic solution diffuses well within the electrode for unknown reasons, and a capacity of approximately 100 to 150 AH/per weight of the active material is obtained. Therefore, a capacity of about 120 to 150 AH/ can be obtained per unit volume. Furthermore, since a battery using the electrode obtained by the method of the present invention has an average discharge voltage of 3.2 to 3.5V, it has a performance that exceeds ordinary lead batteries and nickel-cadmium batteries when compared in terms of energy density. Since it has a high charging and discharging efficiency, its industrial value as a secondary battery is extremely great.

Hereinafter, the present invention will be explained in more detail with reference to Examples.

(Example 1) Synthesis of polyaniline Co-perchloric acid was dissolved in 100 cc of water at a concentration of 0.2 M/2, and aniline was added at a concentration of 0.1 M/2 to prepare an electrodeposition solution. Next, add 10c x 10c to the glass container.
Two nickel mesh plates of size (1) were placed facing each other, one of which was used as an anode, and anode oxidation was started by setting a potential of 800 mV with respect to the laminated gypsum electrode. When the electrolysis was stopped after 10 hours, 19.3 g of polyaniline was deposited on the anode side. This was taken out and washed in pure water for 24 hours. Next, this was dried at 80° C. for 24 hours, and then pulverized and passed through a 100-mesh sieve, and only the particles that passed through the sieve were taken out.

[Production of Polyaniline Electrode A core acrylic press mold was prepared, and the polyaniline powder prepared as described above was laid on it to a thickness of 1.31 cm. Then, on top of this, a thickness of 0.1 - and an area of 23.8
A cJ annealed nickel mesh was placed on top of which polyaniline powder was spread to a thickness of 1.3 cm. Place this in a press machine and apply a pressure of λ4t/c- from above to
Pressed for seconds. As a result, the thickness is 0.731 mm, the area is 23.8 d, and the weight of the active material (polyaniline) is 1.5 mm.
865g (90ml/g per 1cJ), active material density is 1
．． A polyaniline electrode of 0.07 g/cc was completed. The polyaniline was well integrated with the nickel mesh current collector and did not fall off.

[Production of polyaniline battery] The polyaniline electrode produced as described above is wrapped in a bag-shaped polypropylene nonwoven fabric, and a lithium counter electrode made of lithium crimped onto a nickel mesh is placed opposite to this. These were loaded into a rectangular cell as shown in FIG. 1 with a nonwoven fabric sandwiched therebetween. Next, 1M lithium tetrafluoroborate was added to this.
A5 cc of an electrolyte solution dissolved in a 1:1 mixed solvent of propylene carbonate and dimethoxyethane at a concentration of 1:1 was added.

The polyaniline battery manufactured in this manner had an open circuit voltage of 3.3V when uncharged. 4.2-2 with a constant current of 101 people. When charging and discharging in the OV voltage range,
A capacity of 2 eomAH is obtained, so the capacity per unit ff1fft of the positive electrode active material is 139.4 AIl/kg N
The capacity per unit volume was 149.8 AIl/O. The former value was almost the same as the specific capacity of polyaniline.

(Example 2) Polyaniline produced in the same manner as "Example 1"? ? !
+i and a 0.2 mu -thick lithium electrode, with a thickness of 0 between
．． A polypropylene nonwoven fabric of 31 mm was wound into a spiral shape with a separator interposed therebetween, and this was loaded into a single-inch aluminum battery container. No cracks or peeling occurred during the spiral winding process.

3.5 cc of the same electrolytic solution as in Example 1 was added to this.

This was then sealed with a lid.

The weight of the battery manufactured in this way is 15g, and the volume is 7.
．． 3 cc, and the mm was three-fifths that of a nickel-cadmium battery of the same size.

Kono battery 'f-4, 2-2, 0V 17) Voltage range Te1
When charged and discharged at a constant current of 0 mA (7), 243a
A capacity of +AH was obtained, and the average discharge voltage was about L5V. Therefore, the ffl energy density of this battery is 5a
7wu/kg tear, capacity! *Lugie density Ha11
It was 6.5 fil/. All of these values were significantly higher than those of a nickel-cadmium battery of the same size. After repeating charging and discharging 100 times, the battery was disassembled, the polyaniline electrode was taken out, and its shape was examined.
It was the same as the first time and no damage was seen.

As is clear from the above examples, batteries using polyaniline electrodes manufactured by the method of the present invention are significantly superior to conventional batteries in terms of weight and volumetric energy density, and their industrial value is extremely high. big.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a square cell container for evaluating electrode characteristics.

Claims (1)

[Scope of Claims] 1. A method for manufacturing an electrode for a battery, characterized in that a powdery conductive polymer is fixed on a current collector made of a grid-like metal body by pressing to form an electrode active material. 2. The method for manufacturing a battery electrode according to claim 1, wherein the electrode active material has a density of 1.0 g/cc or more.