JPS6291529A - Synthesis of polyaniline - Google Patents

Abstract

PURPOSE:To obtain polyaniline useful as an electrode material for secondary batteries at a low cost, by electrolytically polymerizing an aqueous aniline solution by using stainless steel as an anode for electrolysis. CONSTITUTION:A 0.01-5mol/l aqueous aniline solution, preferably, containing borofluoric acid, perchloric acid or the like is electrolyzed by using a 1-1,000mum-thick gauze or thin sheet-like electrode of stainless steel (e.g., austenitic stainless steel containing 1-10% Mo) as an anode.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for synthesizing polyaniline, particularly a method for synthesizing polyaniline useful as an electrode material for secondary batteries.

(Prior Art) When polyaniline is synthesized by an electrolytic polymerization method, in the conventional technology, it is necessary to make the electrolytic polymerization solution strongly acidic. Therefore, the anode (electrode on the side where polyaniline is deposited and formed) material that can be used during electrolytic polymerization has been limited. That is, only platinum and carbon are used as typical anode materials. In the case of platinum, there is a drawback in that it is expensive, and on the other hand, in the case of carbon, the polyaniline that is normally produced is brittle, and there is a type of carbon that is made into a film by pressing etc., but this is a flexible material. Although it satisfies the surface requirements, it has other disadvantages of high resistance and high cost.

In addition, when polyaniline is used as an electrode material in secondary batteries, it takes time and effort to peel the polyaniline film from the electrode and attach it to the current collector, and when assembling the battery. The process becomes complicated. In addition, in terms of battery characteristics, since a polyaniline film is separately attached to the current collector, internal resistance increases due to increased resistance at the interface. ! ! It had a problem.

(Means for Solving the Problem) The present inventors have arrived at the present invention as a result of extensive research and consideration in order to solve this problem. That is, the present invention uses an aniline aqueous solution .

It is characterized by using stainless steel as an anode when synthesizing polyaniline by an electrolytic polymerization method. This relates to a method for synthesizing polyaniline.

The details of the present invention will be sequentially explained below.

First of all, there are no particular restrictions on the stainless steel used for electrolysis, but it is selected in terms of corrosion resistance to the electrolytic polymerization solution, adhesion to the polyaniline produced, and reduction of internal resistance when used in secondary batteries. Austenitic stainless steel is preferred, and among these, those containing 1 to 10% molybdenum are more preferred. A specific example is Cr;16 for iron.
5LISH6 containing ~18%, Ni: 10~14%, No: 2~3%, etc., and Cr: 18~20% in iron.
, 3118317 containing 11 to 15% Ni, 3 to 4% Ni, and the like.

The form of the stainless steel substrate is selected depending on its intended use and the type of battery intended, but one of the purposes of the present invention is to use the substrate as a battery assembly or container That's what I'm trying to use. Therefore,
Thickness 1~1OflOgm, preferably 1()~511
04bm net shape or thin plate shape is preferable. This results in the achievement of miniaturization and thinning of batteries, or the iq is obsolete.

Next 1. The depolymerization conditions are also not particularly limited. However, in order to further improve the adhesion between the produced polyaniline and the stainless steel substrate, fluoroboric acid or perji! is used as the electrolytic polymerization liquid. A solution containing elementary acid or the like is preferred. The Ml composition of the solution is usually 2 degrees aniline or 0.0
1 to 5 anal λ/l, preferably 0.5 to 3 so/l and acid C degree from 0.02 to 10/l, preferably 1
~6so/l. In addition, the temperature of the electrolytic solution is preferably in the range of 0 to 30°C, from the viewpoint of suppressing the production rate of polyaniline and corrosion of stainless steel.
By setting the temperature to 20° C., the film forming properties of the polyaniline produced can be improved, so this is a more preferable range.

(Example) The Kibatsu 11 will be described in more detail below using Examples and Reference Examples.

[Example 1] Molybdenum-containing austenitic stainless steel (SO
3316) rectangular wire mesh base (4c+sx 2 c+
sx 90gm thick) as an anode and a lead plate as a cathode, aniline 1 oboro/l, borofluoric acid 2 on/l
An aqueous solution of 1 is used as an electrolytic polymerization solution at a constant current of 100
Electricity is applied for a certain period of time to perform electrolytic polymerization, and polyaniline is electrochemically synthesized on a wire mesh substrate.
A wire mesh substrate on which a polyaniline film of 23 to 25 g/cm2 was formed was obtained. This polyaniline had good adhesion to the wire mesh substrate.

[Example 2] Instead of fluoroboric acid in the electrolytic polymerization solution of Example 1,
A wire mesh substrate made of 5IIS3 on which a polyaniline film of 23 to 25 g/crn' was formed was obtained in the same manner as in Example 1, except that a perchlorine fi2/J1 aqueous solution was used. Its properties were similar to those of Example 1.

[Example 3] The back surface and outer periphery of the body (5c+w x 5c x 5t 1 thickness) were masked. Electrode surface! Xi4 cmX 4 c+*
Except for using the anode, we used the same electrode protection and electrolytic solution as in Example 1, and electrolyzed by applying a constant current of 200 IIA for 1 hour! Then, polyaniline was applied on the thin plate body.
It was synthesized electrochemically, then washed with water, dried, and the maskink was removed to obtain a thin plate substrate on which a polyaniline film of 23 to 25 g/c@'' was formed. This polyaniline was also synthesized with 25 thin plates. Adhesion was good.

[Example 4] In place of the fluoroboric acid in the electrolytic polymerization solution of Example 3, 11! 23 to 25 mg/crn in the same manner as in Example 3, except that the base i%72moJ1/standing tree solution was used.
11) is a thin plate substrate on which a polyaniline film is formed.

Its properties were similar to those of Example 3.

(Reference example) A state in which the wire mesh nof body having the polyaniline film obtained in Example 1 is cut into a predetermined size, the polyaniline film is used as a positive electrode, the wire mesh base is used as a positive electrode current collector, and the positive electrode and the current collector are integrated. A battery with a thickness of 1.6■■ was constructed. The negative electrode was lithium, the electrolyte was a propylene carbonate solution of LiBF41, and the separator was a polypropylene nonwoven fabric, which was impregnated with the electrolyte.

Using this polyaniline positive electrode and a secondary battery integrated with a 5US316 wire mesh current collector, the
A charge/discharge test was conducted on A, and the following results were obtained.

・Open circuit potential during charging 4V ・Charging capacity per polyaniline positive electrode 100 All/kg ・Internal resistance ioo Ω ・Coulombic efficiency during charging and discharging 98% This battery has a polyaniline film produced as described above and 5IIS] 16
@Since the adhesion to the wire mesh is extremely good, the positive electrode can be directly connected to the wire mesh.
Since it can be integrated and used as a positive electrode current collector,
It has become possible to reduce the number of steps during battery production and reduce the battery's internal resistance.

(Effect of the invention) With the completion of this invention.

(1) The anode used in aniline electropolymerization is made of stainless steel, which has a significant cost advantage compared to conventional platinum.

(2) The produced polyaniline has good adhesion to the stainless steel used as the anode, and compared to conventional polyaniline, it can be used as is as an electrode for secondary batteries.

(3) Therefore, it is possible to provide polyaniline that has a low internal resistance and meets the needs for smaller and thinner batteries.

Claims (1)

[Claims] A method for synthesizing polyaniline using stainless steel as an anode for electrolysis in synthesizing polyaniline by an electrolytic polymerization method using an aqueous aniline solution.