JPS6231961A - Organic electrolyte battery - Google Patents

Abstract

PURPOSE:To prevent self discharge by using electrolyte comprising tetraalkyl ammonium salt serving as electrolyte and gamma-butyrolactone or a mixture of gamma- butyrolactone and propylene carbonate serving as solvent. CONSTITUTION:Solvent of electrolyte 4 is gamma-butyrolactone or a mixture of gamma- butyrolactone and propylene carbonate of a ratio of 10:0-2:8 by weight. Electrolyte dissolved in the solvent is tetraalkyl ammonium salt. The electrolyte and solvent are used after the completion of dehydration. The concentration of electrolyte in the electrolyte 4 is 0.1mol/l or more in order to reduce the internal resistance of a battery.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an organic electrolyte battery, and more particularly to an organic electrolyte battery in which an insoluble and infusible substrate having semiconductor properties is used as a positive electrode and a negative electrode.

(Prior Art) In recent years, X-device devices have become increasingly smaller, thinner, and lighter, and as a result, there is a strong demand for smaller, thinner, and lighter batteries that serve as power sources. Currently, silver oxide batteries are widely used as small, high-performance batteries, and lithium batteries have been developed and put into practical use as thinner nine-dry batteries and small, lightweight, high-performance batteries. However, since these batteries are primary batteries, they can only be charged once! cannot be used repeatedly for a long time. On the other hand, although nickel-cadmium batteries have been put into practical use as high-performance secondary batteries, they are still unsatisfactory in terms of miniaturization, thinness, and weight reduction.

Further, although lead storage batteries have conventionally been used as large capacity secondary batteries in various industrial fields, the biggest drawback of these batteries is that they are heavy. This is due to the fact that peracid and lead are used as electrodes. In recent years, attempts have been made to reduce the weight and improve the performance of batteries for electric vehicles, but they have not been put to practical use. However, there is a strong demand for a large capacity and lightweight secondary battery as a storage battery.

As mentioned above, each of the batteries currently in practical use has advantages and disadvantages, and each is used differently depending on its purpose.
There is a great need for smaller, thinner, and lighter batteries. As a battery that attempts to meet these needs,
BACKGROUND ART Recently, batteries have been researched and proposed in which thin film polyacetylene, which is an organic semiconductor, is doped with an electron-donating substance or an electron-accepting substance as an electrode active material.

Although this battery has high performance as a secondary battery and has the potential to be made thinner and lighter, it has a major drawback.

The reason is that polyacetylene, which is an organic semiconductor, is an extremely unstable substance and is easily oxidized by reeds and oxygen in the air, and is also deteriorated by heat.

Therefore, battery manufacturing must be carried out in an inert gas atmosphere, and there are also restrictions on manufacturing polyacetylene into a shape suitable for electrodes.

Further, Japanese Patent Application No. 59-24165 describes carbon.

A heat-treated product of an aromatic condensation polymer consisting of hydrogen and oxygen, wherein the atomic ratio of hydrogen atoms/carbon atoms is o, 05
-'-0.5 and a specific surface I area value of 600 m/f or more according to the BET method, an insoluble and infusible substrate having a polyacene skeleton structure is used as a positive electrode and/or a negative electrode, An organic electrolyte battery has been proposed in which the electrolyte is an aprotic organic solvent solution of a compound capable of producing ions that can be doped into the electrode.

This battery has high performance, has the possibility of being made thinner and lighter, has a high oxidation stability of the electrode active material, and can be easily molded, making it a promising secondary battery with a long lifespan. However, several issues remain to be solved in order to put this battery into practical use. Among these problems, the problem of relatively high self-discharge has been addressed.An object of the present invention is to provide an organic electrolyte battery with low self-discharge.

Still another object of the present invention is to provide an organic electrolyte battery using an organic semiconductor electrode active material comprising an insoluble and infusible substrate having a polyacene skeleton structure of gold.

Still another object of the present invention is to reduce internal resistance.

Moreover, it is an object of the present invention to provide a secondary battery that can be charged and discharged for a long period of time.

(Means and effects for solving the problems) According to the present invention, the objects and advantages of the present invention are a heat-treated product of an aromatic condensation polymer consisting of carbon, hydrogen and oxygen, wherein hydrogen atoms/carbon atoms The atomic ratio of is 0.05 to 0.5, and the specific surface area by BE'I' method is 600?7//
In a battery in which the positive and negative electrodes are insoluble and infusible substrates containing a polyacene skeleton structure of f or more, (A) % tetraalkylammonium salt as an electrolyte, and (B) φγ-butyrolactone or γ-butyrolactone and propylene as a solvent. This is achieved by an organic electrolyte battery characterized in that it uses an electrolytic solution consisting of a mixture of carbonate and carbonate.

The most important thing in the present invention is that an electrolytic solution consisting of a specific electrolyte and a specific solvent is applied to a battery having a specific electrode as a component.

The point is that self-discharge of the battery can be prevented.

As per the above, the battery according to the present invention, which is composed of a specific electrolyte and a specific electrode, has particularly low self-discharge. A battery 7f to which the specific electrolyte according to the present invention is applied! :The leakage current when charging at 2V is the most drifting (02H5)4NOIO41moi when only the electrolyte is charged.
The voltage is 2 to 20 times lower than that of a battery substituted with a v/l propylene carbonate solution, resulting in a higher voltage retention rate. Similarly, the leakage current is about 10 to 100 times lower than that of a battery using a LiCIO41molIL'/l acetonitrile μ solution as an electrolyte.

The solvent of the electrolytic solution used in the present invention is sulfolane or a mixture of sulfolane and γ-butyrolactone. Good results regarding self-discharge can be obtained with sulfolane alone, but γ-butyrolactone/propylene carbonate =
A mixed solvent of 1010 to 2/8 (weight ratio) is preferable because it has the effect of reducing internal resistance in addition to the effect of reducing self-discharge. , is the most preferred.

The electrolyte to be dissolved in the solvent according to the present invention is a tetraalkylammonium salt, and specific examples thereof include those represented by the following formula.

And in the compound represented by the above formula (C2I(5)4NO
IQ, 4° (C2■5)4NBF4. (n'-C4I■
,)4NC104 and (n204EI,)4NBF4
is particularly preferred.

It is preferable to use the electrolyte and solvent that have been sufficiently dehydrated. The electrolyte solution is easily prepared by dissolving the electrolyte in a solvent, but the concentration of the electrolyte in the electrolyte solution should be at least 0.1 molar in order to reduce the internal resistance of the electrolyte solution.
It is preferably at least v/1, and more preferably from 0.2 to 1.5 mol/l.

The aromatic condensation polymer in the present invention is a condensate of an aromatic hydrocarbon compound having an phenolic hydroxyl group and an aldehyde. Suitable examples of such aromatic hydrocarbon compounds include so-called phenols such as phenol, cresol, and xylenol, but they are not limited thereto. For example, it can be methylene-bisphenols represented by the following formula, or hydroxybiphenols or hydroxynaphthalenes. Among these, phenols, particularly phenol, are practically preferred.

The aromatic condensation polymer in the present invention includes:

Further, a modified aromatic polymer in which a part of the aromatic hydrocarbon compound having a phenolic hydroxyl group is replaced with an aromatic hydrocarbon compound not having a phenolic hydroxyl group, such as xylene, toluene, etc., such as a condensation product of phenol, xylene, and formaldehyde. It is also possible to use a modified aromatic polymer.

In addition to formaldehyde, aldehydes include
Formaldehyde is preferred, although other aldehydes such as acetaldehyde and furfurer μ may also be used. The phenol formaldehyde condensate may be a novolac type, a resol type, or a composite thereof.

The insoluble and infusible substrate in the present invention is a heat-treated product of the aromatic condensation polymer as described above, and can be produced, for example, as follows.

Prepare an initial condensate of an aromatic hydrocarbon compound having a phenolic hydroxyl group or an aromatic hydrocarbon compound without a phenolic hydroxyl group and aldehydes, prepare an aqueous solution containing this initial condensate and an inorganic salt, and prepare an aqueous solution containing this initial condensate and an inorganic salt. The aqueous solution is poured into a suitable mold and heated to harden and convert it into a plate-like, film-like, or cylindrical shape within the mold, and then the cured product is heated at 350° to 800°C in a non-oxidizing atmosphere.
The heat-treated body is then washed to remove the inorganic salt contained in the heat-treated body.

The above-mentioned inorganic salt used together with the initial condensate is one that will be removed in a later step.
Examples of auxiliary agents for providing a specific surface area value of //g or more include zinc chloride, sodium phosphate, potassium hydroxide, and potassium sulfide. Among these, zinc chloride is particularly preferably used. The inorganic salt can be used in an amount of, for example, 0.05 to 10 times the weight of the initial condensate. If the amount is less than the lower limit, the specific surface area value will not be 600 vl/f or more, and if the amount is more than the upper limit, the mechanical strength of the final molded product will tend to decrease, which is not desirable.

The aqueous solution of the initial condensate and the inorganic salt can be prepared using, for example, 0.1 to 1 times the weight of the inorganic salt in water, although it varies depending on the type of the inorganic salt used, and the aqueous solution can be prepared in an appropriate mold. It is poured and heated at Iff of 50 to 200°C, for example, to form and harden.

In addition, when the above-mentioned initial condensate and inorganic salt are mixed and made into an aqueous solution, phenolic fiber (for example, Kynol fiber manufactured by Nippon Kynol Co., Ltd.) may be mixed together, or cloth, felt, etc. made of the fiber may be mixed. A prepreg sufficiently impregnated with the above-mentioned aqueous solution may be used for molding and curing.

Additionally, as shown in Japanese Patent Application No. 60-58604, the amount of inorganic salt is 2.5 to 10 times that of the initial condensate, and the viscosity of the mixed aqueous solution is adjusted to 100.000 to 100 centipoise.
If the evaporation of water in the aqueous solution is suppressed during heating, the initial condensate in the aqueous solution will be heated and gradually harden, allowing it to grow into a three-dimensional network structure with continuous pores with an average pore diameter of 10μ or less. It is possible.

The thus obtained cured product is then heated in a non-oxidizing atmosphere (including vacuum) at a temperature of 350-800'C, preferably 350-700'C, particularly preferably 400'C.
Heat treated by heating to a temperature of ~600°C.

The preferred rate of temperature increase during heat treatment varies somewhat depending on the aromatic condensation polymer used, the degree of its curing treatment, its shape, etc., but generally it is from room temperature to 300°C.
It is possible to increase the temperature at a relatively high rate up to a temperature of 100°C, for example, 100'O/hour. When the temperature reaches 300°C or higher, thermal decomposition of the aromatic condensation polymer starts, and water vapor (H2O),
Hydrogen, methane.

- It is advantageous to raise the temperature at a sufficiently slow rate, since gases such as carbon oxides begin to evolve.

Such heating and heat treatment of the aromatic condensation polymer is carried out in a non-oxidizing atmosphere. Examples of the non-oxidizing atmosphere include nitrogen, argon-helium, neon, carbon dioxide, etc., with nitrogen being preferably used. Such a non-oxidizing atmosphere may be stationary or flowing.

By thoroughly washing the obtained heat-treated body with water or dilute hydrochloric acid, the inorganic salts contained in the heat-treated body can be removed, and then when it is dried, the atomic ratio of hydrogen atoms/carbon atoms (hereinafter referred to as H (referred to as 'C ratio) is 0.
5 to 0.05, preferably 0.35 to 0.1, and has a specific surface area value of 60 by the BET method.
An insoluble and infusible substrate having a ratio of 0d/f/ or more is obtained.

According to XS diffraction (0uKa), the position of the main peak exists between 20.5 and 23.5 degrees in 2θ, and in addition to the main peak, there is a broad peak between 41 and 46". Other peaks exist.Also infrared absorption)
According to /L/, De=D2000~2940/D156
The absorbance ratio of 0 to 1640) is usually 0.5 or less, preferably 0.3 or less.

That is, it is understood that the above-mentioned insoluble and infusible substrate is one in which the polycyclic structure of polyacene-based benzene is evenly and appropriately developed between polyacene-based molecules.

If the H/O ratio exceeds 0.5 or is smaller than 0.05, the efficiency of charging and discharging when the substrate is used as an electrode of a secondary battery according to the method shown later is undesirable.

In addition, the specific surface area value of the insoluble and infusible substrate containing the polyacene skeleton structure by the BET method is extremely large because it is manufactured using an inorganic salt such as zinc chloride. Those that are equal to or greater than f are used. 600
If it is less than 772'/f, for example, when charging a secondary battery using the substrate as an electrode, the charging voltage will need to be increased.The energy density, etc. will decrease, and the electrolyte will deteriorate. Undesirable. Magaku special request 1986-586
0'''fy'' shows the inorganic salt as 2.5 of the initial condensate.
~10 times the volume of the aqueous solution ff? 100,000~1
When heat-treated in a non-oxidizing atmosphere using a molded body adjusted to 0.00 centivoise and cured in such a way as to inhibit moisture evaporation during heating, the porous insoluble material of the present invention having continuous pores with an average pore diameter of 10 μm or less is produced. An infusible substrate is obtained. When the base body is used as an electrode, the electrolyte can easily enter and exit through the communication holes.

I really like it.

Further, the electric conductivity of the above-mentioned insoluble and infusible substrate is usually 1 (11
1 to 101Ω-101K".As will be described later, when doping with i-solite ions and using it as an electrode material, the conductivity increases significantly, so it is necessary to use an electrode material that also has current collecting properties. Become.

Furthermore, since the insoluble and infusible substrate can take various forms, such as a film plate, when used together with electrode materials, it enables small batteries, thin batteries, lightweight batteries, etc.

The porous insoluble and infusible substrate used in the present invention is 6
Despite having a large specific surface area value of 00 nf/f or more, in reality, there is no change in the physical properties of the electrical conductivity even if it is left in the air for a long time, and it has excellent oxidation stability. In addition, since it has excellent heat resistance and chemical resistance, when it is used as an electrode material to construct a battery, there is no problem of electrode deterioration.

The organic electrolyte battery of the present invention uses the above insoluble and infusible substrate as a positive electrode and a negative electrode, uses a tetraalkylammonium salt as an electrolyte, and uses a mixed solvent of γ-butyrolactone and propylene carbonate (including γ-butyrolactone alone) as a solvent. ) is an organic electrolyte battery using

The battery action of the battery of the present invention utilizes electrochemical doping and electrochemical undoping of the above-mentioned electrolyte ions onto the insoluble and infusible substrate used as the electrode.

It is used for That is, energy is stored by doping the insoluble and infusible substrate, and is taken out as electrical energy by undoping.

The shape and size of the electrodes, which are made of insoluble and infusible substrates placed inside the battery, can be chosen arbitrarily depending on the type of battery intended, but the battery reaction is an electrochemical reaction on the electrode surface. Therefore, it is advantageous for the electrode to have as large a surface area as possible. Although an insoluble and infusible substrate can be used as a current collector for extracting current from the substrate to the outside of the battery, other conductive materials having corrosion resistance such as carbon and platinum may also be used.

Nickel, stainless steel, etc. can also be used.

Next, embodiments of the present invention will be explained with reference to the drawings. FIG. 1 is a basic configuration diagram of a battery according to the present invention. In FIG. 1, (1) is a positive electrode, which is an insoluble and infusible substrate in the form of a film or a plate! (2) is a negative electrode, which is also an insoluble and infusible substrate in the form of a film or a plate. After assembling the battery.

The electromotive voltage of the battery is Ov, and by applying a voltage from an external power source and doping both electrodes with electrolyte ions, the battery comes to have an electromotive voltage. (3) j (
3)' is a current collector for supplying current for electrochemical doping, that is, charging, from which current is extracted from each electrode to the outside, and each electrode and external terminal (7) # (
7)' is connected so as not to cause a voltage drop to (
A) is an electrolytic solution, and (5) is a separator arranged for the purpose of preventing contact between the positive and negative electrodes and retaining the electrolytic solution. The separator is a durable porous material with continuous pores and no electron conductivity. Usually, a cloth, nonwoven fabric, or porous material made of glass fiber, polyethylene, polypropylene, etc. is used. The thickness of the separator is preferably thin in order to reduce the internal resistance of the battery, but it is determined by taking into account the amount of electrolyte retained, flowability, and strength. The positive electrode, negative electrode, and separator are fixed within the battery case so as not to cause any practical problems. shape of electrode,
The size etc. are determined depending on the shape and performance of the target battery. For example, to manufacture thin batteries, film-shaped electrodes are suitable, and to manufacture large-capacity batteries, film-shaped or plate-shaped electrodes are suitable. This can be achieved by stacking a large number of positive and negative electrodes alternately.

Doping or undoping may be carried out under constant current, constant voltage, or under varying conditions of current and voltage, but the amount of doping agent doped into the insoluble and infusible substrate depends on the amount of the substrate. The percentage of the number of doped ions per carbon atom is preferably 0.5 to 20%. The battery of the present invention using an insoluble and infusible substrate as an electrode is a secondary battery that can be repeatedly charged and discharged.

The electromotive voltage varies depending on the doping amount (charge amount) of the battery, but is 1.0 to 3.5 V. Furthermore, since the specific gravity of the insoluble and infusible substrate and the electrolytic solution constituting the battery of the present invention is small, the capacity per weight is large. In addition, although there are differences in power density depending on the structure of the battery, lead-acid batteries have a much higher power density than lead-acid batteries. Furthermore, when the insoluble and infusible substrate of the present invention is used as an electrode, it is possible to produce a secondary battery that has a low internal resistance, can be repeatedly charged and discharged, and has no deterioration in battery performance over a long period of time.

(Effects of the Invention) The secondary battery manufactured by the present invention is an insoluble insoluble material containing a polyacene skeleton structure that has superior oxidation resistance, heat resistance, moldability, and mechanical strength compared to conventionally known organic semiconductors. The fusible substrate is used as an electrode, and the tetraalkylammonium salt is
- Miniaturization of batteries using a solution of a mixed solvent of butyrolactone and propylene carbonate as the electrolyte;
It is a secondary battery that is thin and lightweight, has high capacity and high output, and has low self-discharge. The present invention will be specifically explained below with reference to examples.

Example 1 □; Water-soluble reso-/l/(approximately 60% concentration)/sulfur chloride
An aqueous solution prepared by mixing water in a weight ratio of 10/25/4 was formed on a glass plate using a film applicator. After covering the aqueous solution with a glass plate to prevent the water from evaporating, approx. It was cured by heating at a temperature of 100° C. for 1 hour.

The phenolic resin film was placed in a siliconite electric furnace and heated at a rate of 40°C/hour under a nitrogen stream to 50°C.
Also heat treated to 0℃. Next, the heat-treated product was washed with dilute hydrochloric acid, washed with water, and then dried to obtain a film-like porous body. The thickness of the film is approximately 200 μm
The apparent density is approximately 0.35f/cII.
The electrical conductivity of the first film, which had excellent mechanical strength, was measured using the DC four-terminal method at room temperature.
It was O-4(Ω·cIrL)-1. Further, elemental analysis revealed that the atomic ratio of hydrogen atoms/carbon atoms was 0.27. The shape of the peak from X-ray diffraction is a pattern based on the polyacene skeleton structure υ, 20 to 22 degrees in 2θ.
There is a broad main peak nearby and 41-46
A small peak was confirmed near .

In addition, when the specific surface area was measured using the BET method, 21
It was an extremely large value of 0 (1//).

2. Next, add (C
2■5) 4NCI04' (il-1 mo/I//l dissolved at a concentration of The battery was assembled as shown in the figure, using stainless steel mesh as the current collector and felt made of glass fiber as the separator.

The amount of doping is expressed as the number of ions doped per carbon atom of the porous film substrate, but in the present invention, the number of ions doped is determined from the amount of current flowing through the circuit. . The voltage immediately after the battery was assembled was Ov. Next, a voltage of 92.5 V was applied using an external power source, and the battery was charged by doping the positive electrode K0IO4- ions and the negative electrode (C2■5)4N+ ions for about 1 hour. Naturally, the electromotive voltage of the battery is 2.5■
Met.

Next, when the battery was discharged at a rate such that the amount of and-ping per hour was 3%, the voltage of the battery returned to OV in about 1 hour.

Next, connect the battery to an external power source again, 2. Charging was performed for 1 hour by applying a voltage of OV. The leakage current flowing into the circuit at the end of charging is F5.・//It was A. The electromotive voltage of the battery at this point is 2. Examples 2 to 4 About 200μ obtained in the same manner as Example 1. Thick phenol/I
The 'Al fat film was heated in a siliconite electric furnace at a rate of about 30° C./hour under a nitrogen stream to various predetermined temperatures shown in Table 1 to perform heat treatment. Thereafter, it was washed with dilute hydrochloric acid and water and dried to obtain an insoluble and infusible base film.

The obtained base film was subjected to elemental analysis and measurement of the specific surface area value by the BET method. The results are summarized in Table 1.

Next, add (CI, 1 liter) a mixed solvent of sufficiently dehydrated γ-butyrolactone and propylene carbonate (3:1 by weight).
ET5) Self-discharge was investigated using a solution in which 4NBF4 was dissolved at a concentration of 1 mo/I//l as the electrolytic solution, the above-mentioned base film as the positive and negative electrodes, and other conditions being the same as in Example 1. . 2. After charging with OV.

Table 1 shows the electromotive force after being left for 10 hours. In both cases, small self-discharge was observed.

Example 5 The film-like insoluble infusible substrate obtained in Example 1 was used as a positive electrode and a negative electrode, and sufficiently dehydrated γ-butyrolactone and propylene carbonate were mixed in a solvent (C2H6) in the ratio (weight ratio) shown in Table 2. )4NOIO4 at a concentration of 1 mo/l/l was used as the electrolyte, a battery was assembled, and a self-discharge 'fe RWR was conducted in the same manner as in Example 1. These are summarized in Table 2 Comparative Example 1 Electrolyte (02H3) 4NOIO41Mo/L'
/ II 7"0 Self-discharge was investigated in the same manner as in Example 1 except that pyrene carbonate solution was used. 2.OV
When the battery was left for 10 hours after being charged, the electromotive voltage of the battery was 1.85V.

Comparative Example 2 Self-discharge was investigated in the same manner as in Example 1 except that a Li0A'041 moiv/l dimethoxyethane solution was used as the electrolyte. 2. After charging with OV and leaving it for 1 hour at 1°24, the electromotive voltage of the battery was 1.65 V.

[Brief explanation of the drawing]

Figure 1 shows the basic configuration of the battery according to the present invention, in which (1) is the positive electrode (2) is the negative electrode, (3J' is the current collector (4) and the electrolyte (5) is Separator, (6) represents battery case, (7). (7)' represents external terminal. VJ1 country

Claims (1)

[Scope of Claims] (1) A heat-treated product of an aromatic condensation polymer consisting of carbon, hydrogen and oxygen, in which the atomic ratio of hydrogen atoms/carbon atoms is 0.
．． 05 to 0.5 and whose specific elemental area value by the BET method is 600 m^2/g or more in a battery using an insoluble and infusible substrate containing a polyacene skeleton structure as a positive electrode and a negative electrode, (A) as an electrolyte. tetraalkylammonium salt,
(B) An organic electrolyte battery characterized in that an electrolytic solution consisting of γ-butyrolactone or a mixed solution of γ-butyrolactone and propylene carbonate is used as a solvent. (2) The organic electrolyte battery according to claim 1, wherein the aromatic condensation polymer is a condensate of phenol and formaldehyde. (3) Atomic ratio of hydrogen atom/carbon atom is 0.1 to 0.35
An organic electrolyte battery according to claim 1 or 2. (4) Claims 1 to 3, wherein the insoluble and infusible substrate has a large number of communicating pores with an average pore diameter of 10 μm or less.
The organic electrolyte battery (5) tetraalkyl ammonium salt described in section (C_2H_5)_4NClO_4, (C_2H_5)
_4NBF_4, (n-C_4H_9)_4NClO_
4 or (n-C_4H_9)_4NBF_4. The organic electrolyte battery according to claims 1 to 4. (6) The organic electrolyte battery according to any one of claims 1 to 5, wherein the solvent is a mixed solvent of γ-butyrolactone/propylene carbonate in a weight ratio of 10/0 to 5/5.