JPH01165603A - Method for manufacturing conductive polymer compound - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical field to which the invention pertains) The present invention relates to a method for producing a conductive polymer compound used for electrode active materials of secondary batteries, electronic materials, etc.

[Description of prior art]

Conventionally, conductive polymer compounds such as pi-electron conjugated polymer compounds have excellent flexibility, processability, and light weight, and their application to uses different from inorganic electronic materials has been actively researched.

Polyacetylene is the most well-known representative example of such pi-electron conjugated polymer compounds, and polyacetylene has electron acceptors such as iodine, pentafluoride, arsenic fluoride, etc., and potassium, sodium, etc. By doping with an electron donor, the electrical conductivity is increased by
It can be easily controlled from '5-cs-' to 10''3・all''. Further, the electrical conductivity of the polyacetylene can be controlled by doping it using an electrochemical redox reaction.

On the other hand, as an example of the application field of polyacetylene and other pi-electron conjugated polymer compounds, the application to secondary batteries has been actively researched, but it has not yet been put into practical use.

As a conventional method for producing polyacetylene, a method is known in which acetylene gas is polymerized using a tetrabutoxytitanium-triethylaluminum catalyst according to the Ziegler-Natsuta method. However, the polyacetylene obtained by this method has the following problems. That is, (a) the catalyst remains without being completely removed; (b) the unpaired electron density is as high as 1011 to 10"/J;
It is unstable in air and deteriorates by oxidation; (c) it is unstable even when doped, and its electrical conductivity gradually decreases; (d) it requires a special catalyst removal process, which increases production costs. etc.

In particular, because of the points (b) and (c) above, there is a problem that it is extremely difficult to obtain stable characteristics for a long period of time even when the polyacetylene is used as a semiconductor thin film or a positive electrode active material of a secondary battery. be.

On the other hand, attempts have also been made to produce conductive polymer compounds by a simple plasma polymerization method, which is a different production process from the above-mentioned catalyst-based polymerization method. Specifically, plasma polymerization of organic compounds such as acetylene, ethylene, tetrafluoroethylene, benzene, toluene, and xylene by high frequency or microwave discharge has been attempted, but this method involves various reactions and crosslinking reactions occur. Therefore, the actual situation is that a polymer compound having a sufficiently long pi-electron conjugated double bond chain and desired electrical properties has not been obtained. That is, for example, a polymer compound obtained by plasma polymerization using acetylene as a hexamer becomes an insulator.
When acetylene is brought into a plasma state, acetylene as a monomer decomposes and carbonizes without polymerizing, and also because uniform decomposition does not occur, the resulting polymer compound has branches and high-density bridges. This is because it has a hanging structure.

[Purpose of the invention]

The present invention solves the problems in the conventional methods for producing conductive polymer compounds as described above, and provides a conductive polymer compound with stable electrical conductivity over a long period of time and excellent resistance to oxidative deterioration. It is an object of the present invention to provide a method for manufacturing a pi-electron conjugated conductive polymer compound, which has an easy manufacturing process.

[Structure of the invention]

The inventor of the present invention solved various problems in the conventional manufacturing method of conductive polymer compounds as described above and conducted extensive research in order to achieve the above-mentioned object of the present invention. Instead, a plasma of highly reactive hydrogen atoms is generated by discharging a hydrogen-containing gas, and the plasma is transported to a reaction chamber, where the hydrogen atoms react with a monomer containing a halogen element, such as dehydrohalogenation. By causing this, it is possible to suppress the carbonization reaction, branching and cross-linking reactions of monomers in plasma polymerization reactions, and to create conductive polymer compounds with long pi-electron conjugated double bond chains that have desired electrical properties. I gained knowledge of what I can achieve.

The present invention was completed based on this knowledge, and the gist of the invention is to introduce a gas containing hydrogen gas into a plasma generation chamber provided separately from a reaction chamber and generate a plasma-like gas by electric discharge. The plasma-like gas is introduced into the reaction chamber in which the deposited film forming substrate is installed, and the general formula 〇*HJXsYn, (where X is Halogen element, Y represents an element selected from nitrogen and sulfur, ★+
1+ “+” is a positive integer, ★≧2゜0≦l≦2
★, which satisfies the relationship 1≦Atsushi≦2LO≦n. ) is introduced into the reaction chamber, and the organic compound and the plasma-like gas are reacted to form a high-density compound on the substrate. 1. A method for producing a conductive polymer compound, which comprises depositing a molecular compound film.

Specific examples of the gas containing hydrogen gas used in the present invention include hydrogen gas or at least one gas selected from helium, neon, argon, krypton, and xenon.
Examples include hydrogen gas diluted with more than one type of inert gas.

Further, a carbon-carbon double bond in the present invention or
Specifically, examples of organic compounds containing triple bonds include:
HC-CF, FC-CF.

HC-CCj, CjC-CCj, HC=CBr.

BrC-CBr, HCmCl, IC-Cl.

BrC-CCl, C1 (, -C1, BrC-Cl.

CHx ” CHF, CH* -CF proverb, FCH-
CHF.

FCH” CF*, CFt-CFz,
CH寞” CHC1.

CH oh CCJ,,CjCH鴫CHCj,(IcH=
CCj z, CCt! t −CCj *, CHt
-CHBr.

Examples include. Among these compounds, compounds that are not in a gas state at room temperature, that is, in a liquid or solid state, can be vaporized by bubbling an inert gas such as Ar or He as a carrier gas, or by heating to a temperature above the boiling point. used.

As a method for introducing the organic compound, a gaseous or vaporized organic compound can be introduced alone, or a mixture of a gas selected from helium, neon, argon, krypton, and xenon as a carrier gas can be introduced.

Preferred methods of plasma generation include direct current glow discharge,
Examples include high frequency discharge and microwave discharge, but it is preferable to use microwave discharge, which has a high electron density in plasma.

In the present invention, in order to produce high electrical conductivity in the polymer compound formed, it is sufficient to dope impurities in the same manner as polyacetylene. H
A method of doping impurities by contacting gas or vapor of halogen such as NOs, Lewis acid, protonic acid under reduced pressure, a method of doping impurities by immersing an alkali metal naphthalene complex in a tetrahydrofuran solution, LiCjOa
For example, a method of doping impurities by applying a voltage in an electrolytic solution of LiBF4 or LiBF4 can be mentioned. Furthermore, the electrical conductivity can be increased by doping impurities during polymerization of the polymer compound.

Specifically, a compound containing an impurity element as a component may be added to the gas containing hydrogen gas introduced into the activation chamber (A), and a compound containing the impurity element as a component may be added to the organic compound introduced into the reaction chamber. A compound may be added (or a compound containing the impurity element as a component may be added to both the gas containing hydrogen gas and the organic compound).

As a compound containing an impurity element as a component, a compound that is in a gaseous state at room temperature and normal pressure, or at least a gaseous state under the conditions for forming a deposited film, and that can be easily vaporized using an appropriate vaporizing device should be selected and used. is preferable. Specifically, as such compounds, PHs, PF%, PF3, P
Cjs, pczs.

BzHh, B Fs, B Clx * B B rs
*AaFs.

ksC12, AsHs + It r 5bHs
+5bFs and the like.

The discharge gas pressure for plasma generation is preferably 0.001 Torr to 10 Torr, more preferably 0.001 Torr to 0.5 Torr.

The (flow rate) ratio of the flow rate of hydrogen gas introduced into the plasma generation chamber to the flow rate of the organic compound is preferably 2-3001, more preferably 10-3001, in order to ensure sufficient reaction.
It is desirable that it be set to 100.

The substrate temperature is desirably set to preferably 400° C. or lower, more preferably 200° C. or lower so that the crosslinking reaction on the substrate surface is not accelerated by the substrate temperature.

It is also desirable to apply optical energy to the substrate surface in order to further improve the reactivity between the halide and the plasma gas obtained from the discharge of gas containing hydrogen gas.

Next, the present invention will be explained in detail using drawings.
The present invention is not limited to this in any way.

FIG. 1 is a schematic diagram schematically showing a typical example of an apparatus for producing a conductive polymer compound suitable for carrying out the method of the present invention.

In FIG. 1, 100 is a plasma generation chamber, 101 is a reaction chamber, 102 is a microwave waveguide, 103 is a microwave introduction window, 104 is a magnetic coil for plasma stabilization, 105 is an introduction pipe for gas containing hydrogen, and 106 is a microwave introduction window. 107 is a substrate, 108 is a substrate holder, 109 is an exhaust pipe, 110 is a plasma extraction port, 111 is a heater for heating the substrate, and 112 is a window for light energy incidence.

The magnetic coil 104 applies a magnetic field to the plasma generated by microwaves, thereby stabilizing the discharge and aligning the directions of movement of electrons and charged particles, thereby improving the effective electron density.

The production of a conductive polymer compound using the apparatus shown in FIG. 1 is carried out as follows.

That is, first, a continuous gas is introduced into the plasma generation chamber 10G from the gas introduction pipe 103, and zero-order microwaves are introduced from the microwave introduction window through the waveguide 102 to maintain the pressure in the reaction chamber 101 at a predetermined pressure. , generate plasma.

Quartz or alumina is generally used as the material for the microwave introduction window. A magnetic field can be applied to the plasma generation chamber 100 as needed by the magnetic coil 104, and plasma can be stably generated and the plasma can be extracted into the reaction chamber 101. Next, an organic compound as a raw material gas is introduced into the reaction chamber 101 through the gas inlet 106 and reacted for a predetermined time to form a deposited film on the substrate.

〔Example〕

Hereinafter, a method for producing a conductive polymer compound using the above-mentioned production apparatus will be specifically explained.

First, after mounting the cleaned quartz glass substrate 107 on the substrate holder 108 of the manufacturing equipment shown in FIG.
Exhaust to r. Next, the temperature of the substrate 107 is controlled to 170° C. by the substrate heating heater 111, and when it becomes stable, hydrogen gas is introduced into the plasma generation chamber 100 from the gas introduction pipe 105 for 100 seconds + g, and helium gas is introduced for 200 seconds.
ccgt, and the microwave is introduced through the waveguide 102 and the microwave introduction window 103, with an effective power of 200W.
It generated a plasma of gas containing hydrogen.

Next, difluoroethylene (F
CH-CHF) was introduced into the reaction chamber at 1 Qscc-, and the internal pressure was adjusted to 0.05 T by controlling the exhaust capacity of an exhaust device (not shown).
When the sample was reacted with a plasma-like gas containing hydrogen for 10 minutes, a polymer compound having a thickness of 2.1 μm was deposited on the quartz glass substrate.

In addition, when the substrate was irradiated with ultraviolet light from the entrance window 112 using a high-pressure mercury lamp during deposition, the deposition rate was doubled.0 When the visible absorption spectrum of the polymer compound deposited on the quartz glass substrate was measured. , An absorption peak was observed near 520 nm as shown in Figure 2 (al).Next, the unpaired electron density was measured by the ESR (electron spin resonance) method, and it was about 10''1/-. When the electrical conductivity was measured by the four-terminal method, it was 1O-11s'
It was cn-'. When a sample of this polymer compound was placed in a vacuum chamber and brought into contact with arsenic pentafluoride AsF5 at a pressure of 500 mTorr, the electrical conductivity increased to 20 s'cm-'.

In addition, using a polymer compound deposited in the same manner as described above except that the quartz glass substrate was replaced with an aluminum substrate, a standing test was conducted at 25°C in air for 30 days. An evaluation using infrared absorption spectroscopy revealed that the increase in absorption of carbonyl (C-0) bonds around 1790 cm-', which indicates oxidative deterioration, is observed in polyacetylene polymerized with Ziegler-Natsuta catalysts after a 30-day storage test. It was not recognized later.

Next, a titanium metal plate was used instead of the aluminum substrate, a polymer compound deposited in the same manner as above was used as the positive electrode active material, a lithium-aluminum alloy was used as the negative electrode active material, and the electrolyte was A secondary battery shown in FIG. 3 was prepared using a 0.6 M lithium perchlorate solution in propylene carbonate. FIG. 3 is a schematic cross-sectional configuration diagram of a secondary battery using a deposited film of a polymer compound obtained according to the present invention as a positive electrode active material. In FIG. 3, 300 is a positive electrode case, 301 is a positive electrode current collector, 302 is a positive electrode active material composed of a polymer compound deposited film obtained by the present invention, 303 is a gasket, 304 is a separator, 3
05 is a negative electrode active material, and 306 is a negative electrode case.

For the secondary battery produced in this way, 500μA
When charging and discharging was performed at a constant current of , the charging and discharging characteristics shown in FIG. 4 were obtained. The open circuit voltage of this secondary battery was 3.5V. Furthermore, when a charge/discharge cycle test was conducted using the secondary battery, it was found that the cycle life of the secondary battery was 270 cycles, compared to 270 cycles when using polyacetylene obtained by polymerizing acetylene using a Ziegler-Natsuta catalyst with tV cuft-off. The lifespan was over 1000 cycles.

In Example 1, the substrate temperature was controlled at 150°C, and instead of hydrogen gas, arsine As diluted with hydrogen at 100 pp- was used.
)(, was introduced into the plasma chamber at 10Oscc-, and dichloroethylene (CICH-
When 10105e (CHCI) was introduced and the reaction was carried out for 10 minutes in the same manner as in Example 1, a polymer compound having a film thickness of 1.7 μm was obtained.

When the electrical conductivity of the polymer compound was measured by the four-probe method, it was 3s-cs+-'.Similar to Example 1, when the polymer compound was left in the air for 30 days, the electrical conductivity was hardly decreased, and no increase in the infrared absorption spectrum at 1790 cm −' attributed to the C═O bond was also observed.

In Example 1, the substrate temperature was controlled at 180° C., the effective power of the microwave was changed from 200 W to 150 W, and Mugas was introduced into the reaction chamber at 100 scgg as a carrier gas instead of difluoroethylene. Internal pressure Q,
When the reaction was carried out at 1 Torr for 20 minutes in the same manner as in Example 1, a polymer compound having a thickness of 2.3 μm was deposited.

In the visible absorption spectrum of the obtained polymer compound, an absorption peak was observed at 500 nm, as shown in Figure 2 (Figure 2). The presence of an absorption peak on the long wavelength side indicates that the pi-conjugated bond chain is long. Furthermore, the electrical conductivity was measured to be 10-I@5-cm-1 by the four-terminal method. The measurement result of unpaired electron density by ESR method is 10"l
/J.

Next, when an attempt was made to improve the electrical conductivity using ASFs gas in the same manner as in Example 1, the electrical conductivity increased to 14s-cs-'.

Next, a polymer compound was deposited on a titanium metal substrate in the same manner as in Example 1, and a secondary material as shown in FIG. When the battery was made, the open circuit voltage was 3.6v.
Met. Further, in a constant current charge/discharge cycle test of 500 μA, a life of 870 cycles was obtained.

In Example 3, instead of helium used as a carrier gas for difluorobenzene, argon dilution 11 was used as the carrier gas for difluorobenzene.
A polymerization reaction was carried out in the same manner as in Example 3, except that 100 pp of phosphorus trifluoride PF was introduced into the reaction chamber at 100 sccm, and as a result, a polymer compound having a thickness of 2.4 μm was deposited.

The electrical conductivity of the obtained polymer compound measured by the four-terminal method was 1S-es-'. As in Example 1, after the polymer compound was left in the air for 30 days, the infrared absorption spectrum was measured by the ATR method. However, there was almost no increase in the absorption peak at 1790as-', which is attributed to the C-O bond. I was not able to admit.

Using a conventional parallel plate capacitively coupled glow discharge plasma polymerization apparatus, a quartz glass substrate was mounted on a substrate holder, and then the temperature of the substrate was lowered to 10 Torr by exhausting the substrate to 10 Torr.
Difluoroethylene (FCH=CHF
) was introduced at 100seca+, and the internal pressure was 0.5Torr.
When 100 W of 13.56 MHz high frequency power was applied and a plasma polymerization reaction was performed for 10 minutes, the film thickness was 1.5
A deposited film of a polymer compound of μm size was obtained. The visible absorption spectrum of the obtained polymer compound is shown in Figure 2 1dl.
The absorption peak appears to be on the short wavelength side of 400 nm or less, indicating that the carbon-carbon pi-conjugated double bond chain is short.

The electrical conductivity measured by the four-terminal method is 10-I3s・cI
It was I-1. Further, as in Example 1, AsF.

When brought into contact with gas, the electrical conductivity increased only up to lQ-"s-cs-'.

Even if the polymer compound is left in the air for 30 days, C-0
No increase in the infrared absorption spectrum of 1790011-', which was attributed to the bond, was observed.

When the reaction was carried out in the same manner as in Comparative Example 1, except that acetylene (CH-CH) was introduced at 100 scc instead of difluoroethylene, a deposited film of a polymer compound with a film thickness of 2.3 μm was obtained. Obtained.

The visible absorption spectrum of the obtained polymer compound is shown in Figure 2.
dl, indicating that the conjugated double bond chain is short as in Comparative Example 1.

The electrical conductivity measured by the four-terminal method is 1O-12S・am
-' was. Further, when it was brought into contact with AsF5 gas in the same manner as in Example 1, the electrical conductivity increased only to lQ-'s-cs-'.

After the polymer compound was left in the air for 30 days, the infrared absorption spectrum was measured, and as a result, 1 was assigned to the C-0 bond.
A slight increase in the absorption spectrum at 790 cs-' was confirmed.

This one run 20m with toluene! , tetrabutoxytitanium Ti(On
CaHq>a 1. Om A! (3 mmol
), triethylaluminum ARE ts 1.6mj
(12 mmol) were added in this order to a Schlenk flask purged with argon and aged for 30 minutes, then cooled in a dry ice-methanol bath (-78°C) and thoroughly degassed. Next, a catalyst is attached to the inner wall of the flask, acetylene gas (500 to 700 Torr) is introduced at room temperature, polymerization is carried out for a predetermined period of time, unreacted acetylene gas is exhausted, and the flask is thoroughly washed with toluene and dried under reduced pressure. A polyacetylene film was prepared. The unpaired electron density of the obtained polyacetylene was IQ"cs-' from ESR measurement. The electrical conductivity measured by the four-probe method was lQ-'s
-cs-'.

When brought into contact with AsF and gas in the same manner as in Example 1, the electrical conductivity increased to 3×10's-am-'.

As a result of measuring the infrared absorption spectrum after leaving the polyacetylene in the air for 30 days, it was found that the polyacetylene was 1790
There was a significant increase in the absorption spectrum attributed to the C=O bond in cm-'. After being left in the air for 30 days after measurement by ESCA, the ratio of oxygen atoms to carbon atoms is O
/C-0.5.

When a battery test was performed on the secondary battery prepared in Example 1 by replacing the positive electrode active material with the polyacetylene obtained here, the open circuit voltage was 3.6 V, and the constant current charge/discharge cycle life of 500 μA was 270 cycles. there were.

〔Effect of the invention〕

According to the method of the present invention, a plasma-like gas is generated in a plasma generation chamber by discharging a gas containing hydrogen gas, and this plasma-like gas is reacted with an organic compound, thereby replacing the raw material gas of the conventional method. Compared to plasma polymerization by direct discharge, crosslinking reactions can be suppressed, the pi-conjugated carbon chain is sufficiently long, and polymer compounds with high electrical conductivity can be easily produced stably and reproducibly.

Furthermore, the oxidation stability is significantly improved compared to polyacetylene produced using a Ziegler-Natsuta catalyst.

Furthermore, since no catalytic reaction is used, there is no need for a catalyst removal process, which is excellent in simplifying the process and improving productivity.

[Brief explanation of the drawing]

Figure 1 is a schematic configuration diagram of a typical manufacturing apparatus suitable for carrying out the method of the present invention, and Figure 2 shows the absorption spectrum of the polymer compound obtained in Example 1. The figure shown in FIG. 3 is a cross-sectional configuration diagram of the secondary battery created in Example 1,
FIG. 4 is a diagram of the charging/discharging characteristic curve of the secondary battery prepared in Example 1. 100... Plasma generation chamber, 101... Reaction chamber, 1
02...Microwave waveguide, 103...Microwave introduction window, 104...Magnetic coil for plasma stabilization, 10
5... Hydrogen gas inlet, 106... Halogenated hydrocarbon inlet, 107... Sample substrate, 108... Substrate holder, 109... Exhaust system, 110... Plasma extraction port, 111・・・Substrate heating heater, 112・
・・Excitation light incidence window, 300 ・Positive electrode case, 301・
...Positive electrode current collector, 302...Positive electrode active material, 303...
・Gasket, 304...Separator, 305...
-Negative electrode active material, 306...Negative electrode case.

Claims (1)

[Scope of Claims] A gas containing hydrogen gas is introduced into a plasma generation chamber provided separately from a reaction chamber, a plasma-like gas is generated by electric discharge, and the plasma-like gas is deposited and a film-forming substrate is installed. The following general formula (
An organic compound having at least one carbon-carbon double bond or triple bond represented by I) is introduced into the reaction chamber, and the organic compound and the plasma-like gas are reacted to form a compound on the substrate. 1. A method for producing a conductive polymer compound, which comprises depositing a polymer compound film. Formula CkHlXmYn...(1) (However, X is a halogen element, Y is an element selected from nitrogen and sulfur, k, l, m, and n are positive integers, and k≧
2, 0≦l≦2k, 1≦m≦2k, and 0≦n. )