JPH0374051A - Polymer secondary battery - Google Patents

Abstract

PURPOSE:To obtain polypyrrole having output performance by specifying the ratio of the maximum peak intensities in the highest wavenumber region of peak intensity in Raman spectrum obtained by irradiating argon ion laser as an excitation beam source onto the cross section of polypyrrole on an electrode. CONSTITUTION:In the cross section of polypyrrole, which is a positive active material, accumulated on an electrode, the R value defined by the ratio of the spectrum maximum intensity in the wavenumber region of 1580+ or -20cm<-1> obtained by vertical incidence of the laser polarization plane to a surface of the electrode and the spectrum maximum intensity in the wavenumber region of 1850+ or -20cm<-1> obtained by parallel incidence of the laser polarization plane to the surface of the electrode in the resonance Raman spectrum analysis by use of argon laser beam is specified to 1.2 or more. High R value shows that vertical orientation of polypyrrole chains is higher than parallel orientation of them. Polypyrrole having high capacity in high constant-current discharge and high output can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a secondary battery characterized by using polypyrrole produced by an electrolytic oxidation polymerization method as a positive electrode.

<Prior Art> In recent years, with the aim of reducing the weight of batteries, various studies have been conducted on two-thorn batteries that use conductive polymer materials such as polyacetylene, polyaniline, polypyrrole, and polythiophene as electrode active materials.

However, secondary batteries using these conventional conductive polymers as electrode active materials have the following problems.

The conventional polymer secondary battery, polyaniline, has a small capacity during high constant current discharge and is difficult to obtain high output. Although it is good for long-term use with a low output comparable to memory backup batteries, A battery that is lightweight and exhibits high output characteristics for use in portable electronic devices that are rapidly progressing and require high output, but has insufficient performance. is needed.

<Objective of the Invention> The present invention was made in view of the current situation, and an object of the present invention is to obtain a secondary battery using polypyrrole as a positive electrode, which exhibits excellent output characteristics.

<Structure and operation of the invention> The present invention is a polymer secondary battery using polypyrrole, which is a positive electrode active material and has an R value of 1.2 or more in the cross section of the polypyrrole stacked and deposited on the electrode. The present invention, which is a polymer secondary battery using polypyrrole obtained by electrolytic oxidative polymerization of pyrrole at a polymerization temperature of 0° C. or lower, will be described in detail below.

First, the R value is 1.2 or more, preferably 1.3.
above, more preferably 1.4 or above.

Here, the R value is one index for evaluating the orientation of the cross section of polypyrrole polymerized and deposited on the electrode. In other words, this is
By resonance Raman spectroscopy, an argon ion laser (wavelength 488 m>) was used as an excitation light source to irradiate a cross section of polypyrrole stacked on an electrode, and the highest peak intensity in the obtained Raman spectrum was 1580 ± 20.
This is done by comparing the maximum peak intensities at 34.

This R is R = (1580±20 (maximum peak intensity of spectrum in the wave number range of !114 obtained when the polarization plane of the laser is incident perpendicular to the electrode surface) / (the maximum peak intensity of the spectrum in the wave number range of !114) On the other hand, 1580±203 obtained by incident in parallel direction
The maximum peak intensity of the spectrum in the wave number range of 4) is defined as:

Here, the electrode surface refers to the surface on which polypyrrole is actually deposited, and in the case of a flat electrode, it means the flat surface, and in the case of a mesh-like or sponge-like electrode, it means the mesh or sponge-like electrode. means the surface of the linear electrode object or porous electrode object that constitutes the electrode object. Therefore, in this case, the above-mentioned R is measured by cutting out a minute portion of the electrode.

In the case of this evaluation of orientation, the higher the R value, the higher the orientation than the lower R value. In other words, a higher value means that the orientation of the polypyrrole chains is higher in the direction perpendicular to the electrode surface than in the parallel direction.
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The higher this value, the greater the discharge capacity at a high constant current, which is thought to be due to the fact that the polymer molecular chains are oriented perpendicularly to the electrode, which is related to the diffusion of electrolyte anions into the polymer. It will be done.

Next, the polypyrrole film of the present invention contains virol and/or
Alternatively, a derivative thereof can be deposited on an anode plate by constant potential electrolytic oxidation polymerization in the presence of an electrolyte, using an organic solvent containing water as a solvent, if necessary. (^
,F,Diaz,and,to,to.

ni anazawa; J, C, S, Chei, Co1
1979.635) According to this method, anions coexisting in the reaction system are taken in as bepants, so high conductivity can be achieved without doping with an electron-accepting compound.

The virole and its derivatives used in the present invention preferably have high purity, and are preferably purified by distillation before use. Examples of virole derivatives include substituents at the N-position of the pyrrole ring, and substituents at the β-position of the pyrrole ring. monosubstituted, β
, γ-position disubstituted products, etc. are used, and specific examples include pyrrole, N-alkylpyrrole such as N-methylpyrrole, N-ethylpyrrole, 3-alkylpyrrole such as N-7enylpyrrole, and 3-methylpyrrole. Examples include pyrrole and 3,4-dialkylvirol such as 3,4-dimethylvirol.

Pyrrole or its derivatives are 0.0001 to the solvent
IM to moles/liter (M), preferably 0.001
Polymerization is carried out using M to 0.5 M.

Examples of the electrolyte include tetraalkylammonium salts of inorganic and organic acids, alkali metal salts of inorganic and organic acids, and the like. Specifically, tetraethylammonium perchlorate, tetraethylammonium borofluoride, tetramethylammonium hexafluorophosphate, tetramethylammonium hexafluoroarsenate, tetrabutylammonium sulfonate, tetraethylammonium trifluoromethylsulfonate, lithium trifluoromethylsulfonate. Examples include, but are not limited to, salts such as , lithium perchlorate, and the like.

The electrolyte used is O, OOOIM to IM, preferably 0.001 M to -0.5 M relative to the solvent.

Examples of organic solvents that are polymerization solvents include acetonitrile, benzonitrile, nitrobenzene, tetrahydro-7rane,
Preferred are those that can easily dissolve the electrolyte, such as nitromethane, propylene carbonate, ethylene carbonate, sulfolane, and dimethoxyethane, but are not necessarily limited thereto.

The role of water used as required is to increase the effectiveness of electrolytes,
This improves the form in which polypyrrole is precipitated.

The amount used depends on the type of electrolyte used, and the concentration of water in the electrolyte solution is from 0.1M to 5M, preferably from 0.3M to 3M.

The anode material used in the reaction is deficient in the electrode reaction,
Any general-purpose material may be used as long as it does not undergo deterioration, and metals such as platinum, gold, copper, and nickel, or similar conductive materials, carbon electrodes, and the like may be used, but are not particularly limited. In addition, when the electrode area of the cathode is larger than that of the anode, the state of precipitation of polypyrrole that is generally produced is better. The ratio of cathode to anode surface area is 1.1
It is preferably 1.5 times or more, more preferably 21 times or more, particularly preferably 3 times or more.

The electrolytic potential used is 0.7 volts or more with respect to a silver/silver chloride (Ag/AgCf 2 ) reference electrode.

Preferably 0.8 to 1.2 volts, particularly preferably 0.8 to 1.2 volts.
9 to 1.1 volts are used. In order to suppress the electrolytic potential at a low temperature of 0° C. or lower, a KCI/agar salt bridge or the like is used. Any method may be used as long as the electrolytic potential can be controlled.The electrolytic current has a current density of 0.01 at the anode.
m^/-~10 garden^/-1 preferably 0.05mA/a
1 to 51 A/d.

The polymerization temperature used is 0°C or lower, preferably -20°C or lower. The lower the humidity, the more highly oriented polypyrrole can be obtained, so lower temperatures are preferred; however, it must be carried out above the melting point of the electrolyte (
(Japanese Patent Application Laid-open No. 59-140027) If desired, ultrasonic waves can be
The ultrasonic generator used for the ultrasonic irradiation of the present invention may be one for ultrasonic cleaning. I!, which is mainly used for biochemistry!
Those for Ii cell crushers are mainly used. The frequency of ultrasonic waves is not particularly limited, but from the perspective of the Radio Law, the frequency of ultrasonic waves is 20
Those of KH2 or higher are mainly used. The power is appropriately selected depending on the size of the reaction vessel.

Since ultrasonic irradiation is performed during polymerization, the irradiation temperature is taken as the polymerization temperature.

The polymerization reaction time is appropriately selected from the relationship between the amount of current and the time of current application in order to produce a film with a desired thickness.

Hereinafter, the present invention will be explained in detail with reference to Examples. However, the present invention is not limited to this.

Examples and Comparative Examples A glassy carbon plate (GC-20 manufactured by Tokai Carbon Co., Ltd.) whose surface was polished as an anode in a 500 m1 separable flask
, using platinum foil as the cathode, 10
Mixed solution of 400 ml of pyrene carbonate, 4 ml of water, 5.51 g of tetraethylammonium barchlorate
(0,024 mol) was added, and nitrogen gas was introduced to remove oxygen. Thereafter, 1.61° (0,024 mol) of pyrrole was added. -20°C as Example 1.

As Example 2, the Ag/AgCJ electrode was cooled to 0°C, and as a comparative example, it was cooled to 20°C under a nitrogen stream. Electrolytic oxidation polymerization was performed in OV for 24 hours (current application amount: 425 clones).
After the polymerization was completed, the resulting 30 μm film was peeled off from the anode plate, washed with acetonitrile, and dried. The obtained film was cut, and the R value of the cross section was determined by resonance Raman spectroscopy. The results are shown in Table 1.

Next, using an 80-mesh platinum wire mesh instead of the glassy carbon plate as an anode, polypyrrole was precipitated and deposited on the platinum wire mesh by the method described above. 32->, L1 metal was used as the negative electrode (approximately 32-), and propylene carbonate containing 1.0 mol/l of lithium barchlorate was used as the electrolyte to assemble a polymer secondary battery using a non-aqueous electrolyte.

And for these batteries, the end-of-charge voltage is 3.6V,
Discharge end voltage2. The constant current discharge capacity (normalized by the discharge capacity at the lowest constant current IIIA tested) was determined as OV.
FIG. 1 shows this discharge characteristic.

From Table 1, the R values of Examples 1 and 2 are 1.41° and 1.3, respectively.
2, which is higher than 1.2, and the comparative example is 1.16, which is 1.
It showed a value lower than 2. From FIG. 1, Example 1.2
It was found that the discharge capacity of 2011A and high discharge current were both higher than those of the comparative example, indicating that the discharge capacity was good.

Table 1

[Brief explanation of drawings]

FIG. 1 is a graph showing the normalized discharge capacity for a constant discharge current of the present invention and a comparative example.

Claims (3)

[Claims] (1) In a polymer secondary battery using polypyrrole produced by electrolytic oxidative polymerization as the positive electrode active material, Argo-elase laser light with a wavelength of 488 mm is applied to the cross section of the polypyrrole, which is the positive electrode active material, and is stacked and deposited on the electrode. In the resonance Raman spectrum analysis used, the following formula; R = (maximum peak intensity of the spectrum in the wave number range of 1580 ± 20 cm^-^1 obtained by making the polarization plane of the laser incident in the direction perpendicular to the electrode surface)/ (1580±20 obtained when the polarization plane of the laser is incident parallel to the electrode surface
Maximum peak intensity of the spectrum in the wave number range of cm^-^1)
A polymer secondary battery characterized by having an R value of 1.2 or more, (2) A polymer secondary battery according to claim 1, wherein the polypyrrole of the positive electrode active material is produced at a polymerization temperature of 0° C. or lower. (3) A polymer secondary battery according to claim 1, characterized in that polypyrrole is directly electrolytically polymerized on the positive collecting electrode.