JPH046072B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a novel organic electrolyte battery whose electrode active material is an electrically conductive organic polymeric material doped with an electron donating substance or an electron accepting substance. 2. Description of the Related Art In recent years, electronic devices have become increasingly smaller, thinner, and lighter, and as a result, there has been 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 thin dry batteries and small, lightweight, high-performance batteries. However, since these batteries are primary batteries, they cannot be used for long periods of time by being repeatedly charged and discharged. On the other hand, as a high-performance secondary battery, nickel
Although cadmium batteries are in practical use, they are inferior to the aforementioned batteries in terms of smaller size, thinner shape, and lighter weight. Furthermore, lead-acid batteries have been conventionally used as high-capacity secondary batteries in various industrial fields, but the biggest drawback of these batteries is that they are heavy. This is inevitable because lead peroxide and lead, which have a high specific gravity, are used as electrode active materials. In recent years, attempts have been made to improve the weight ratio and performance of batteries for electric vehicles, but they have not been put to practical use. However, there is a strong demand for the development of large capacity and lightweight secondary batteries for power storage. As described above, each of the batteries currently in use has advantages and disadvantages, and is used depending on the purpose, but there is a great need for smaller, thinner, and lighter batteries. As a battery that meets these needs, a battery that uses a thin film of polyacetylene, which is an organic semiconductor, doped with an electron-donating substance or an electron-accepting substance as an electrode active material has recently been researched and proposed. Although this battery has high performance as a secondary battery and has the possibility of being 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 oxygen in the air and 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. Normally, the conditions required for batteries include high load voltage and current, long life, small change in characteristics due to temperature, small battery weight and capacity, maintenance-free, and low cost. be. The present inventors conducted intensive research to develop a battery that does not have the drawbacks of batteries that are currently in practical use or have been proposed, and that satisfies the conditions required for batteries.As a result, an insoluble and infusible substrate containing a polyacene skeleton structure was developed. A battery that satisfies the above requirements can be obtained by constructing a battery using a positive electrode and/or a negative electrode, and an electrolyte containing a compound capable of producing ions that can be doped into the electrode by electrolysis, dissolved in an aprotic organic solvent. The present invention was completed by discovering that the present invention can be obtained. An object of the present invention is to provide a lightweight secondary battery with high performance. Another object is to provide a secondary battery that can be easily made smaller or thinner. Yet another object is to provide a battery that is easy to manufacture and inexpensive. The object of the present invention is to provide an insoluble and infusible substrate containing a polyacene skeleton structure having an atomic ratio of hydrogen atoms/carbon atoms of 0.33 to 0.15, which is a heat-treated product of an aromatic condensation polymer consisting of carbon, hydrogen, and oxygen. This is achieved by constructing a battery by using a positive electrode and/or a negative electrode, and using an electrolyte containing a compound capable of producing ions that can be doped into the electrode by electrolysis dissolved in an aprotic organic solvent. The insoluble and infusible substrate containing a polyacene skeleton structure used in the present invention is an aromatic condensation polymer consisting of carbon, hydrogen, and oxygen in a non-oxidizing atmosphere with an atomic ratio of hydrogen atoms/carbon atoms of 0.33 to 1.
It can be manufactured by heating and heat-treating to a temperature of 600 to 800°C so that the temperature becomes 0.15. According to research conducted by the present inventors, a heat-treated aromatic condensation polymer consisting of carbon, hydrogen, and oxygen has an atomic ratio of hydrogen atoms/carbon atoms of 0.60 to 0.15.
Particularly preferably, the insoluble and infusible substrate containing a polyacene skeleton structure represented by 0.50 to 0.20 can be doped with an electron-donating substance or an electron-accepting substance, and by such doping, the undoped substrate can be doped with an electron-donating substance or an electron-accepting substance. It has been found that the electrical conductivity can be significantly increased. It has also been found that the substrate can be doped with an ionized electron-donating substance or electron-accepting substance in an aprotic organic solvent by an electrochemical method, and the electrical conductivity can be increased as described above. It has also been found that doped materials can be undoped by electrochemical methods. As the aromatic condensation polymer consisting of carbon, hydrogen and oxygen, a condensate of an aromatic monovalent hydrogen compound having a phenolic hydroxyl group and an aldehyde is suitable. Suitable examples of such aromatic compounds include so-called phenols such as phenol, cresol, and xylenol, but are not limited thereto. For example, methylene bisphenols, hydroxybiphenyls, and hydroxynaphthalenes may be used. Among these, phenols, particularly phenol, are preferred from a practical standpoint. Further, as the aldehyde, not only formaldehyde but also acetaldehyde and other aldehydes can be used, but formaldehyde is preferred. Further, as aromatic condensation polymers, there are also copolymers or mixtures of furan resins obtained from furfural or furfuryl alcohol, and condensates of the above-mentioned aromatic hydrocarbon compounds having phenolic hydroxyl groups and aldehydes. It can be used. It is advantageous that the aromatic condensation polymer consisting of carbon, hydrogen and oxygen is previously formed into a shape suitable for use in the battery of the present invention, such as a film, plate, fiber, cloth or composite thereof, and then heat treated. The aromatic condensation polymer can be molded by a conventionally known method. For example, a method in which a mixture of powdered novolac and a curing agent is pressure molded in a heated mold, a method in which a methanol solution of novolac resin is cast onto a glass plate, the methanol is evaporated, and then the mixture is cured in a hydrochloric acid-formalin bath; Examples include a method in which a prepreg is made from phenolic resin fibers or cured phenolic resin powder and liquid resol resin or furan resin, and then pressure molded under heat. The insoluble and infusible substrate containing a polyacene skeleton structure is prepared by molding the aromatic condensation polymer in a non-oxidizing atmosphere such as nitrogen, hydrogen, argon, helium, etc. or in vacuum at 400 to 800°C, preferably
It can be produced by heating to a temperature of 450 to 750°C, particularly preferably 500 to 750°C, and heat-treating. The preferred rate of temperature increase during heat treatment varies somewhat depending on the type of aromatic condensation polymer used, its shape, etc., but generally it is possible to achieve a relatively high rate of temperature increase from room temperature to a temperature of about 300°C. However, if the thickness of the normal molded body is h (mm), then
It is preferable to set the temperature increase rate to 80/h ² °C/hour or less. The atomic ratio of hydrogen atoms/carbon atoms of the insoluble and infusible substrate produced by setting the temperature to such a rate is
It becomes easy to control it within the range of 0.60 to 0.15, and it also becomes easy to stabilize the electrical conductivity or other mechanical properties. If the temperature of heating and heat treatment is lower than 400℃, thermal decomposition will be insufficient, while if the temperature is higher than 800℃, thermal decomposition will be too intense, and in either case, the atomic ratio of hydrogen atoms / carbon atoms will be lowered. It is extremely difficult or impossible to make the value between 0.60 and 0.15. In the battery of the present invention, the insoluble and infusible substrate containing a polyacene skeleton structure with a hydrogen atom/carbon atom atomic ratio of 0.33 to 0.15 obtained as described above is used as a positive electrode and/or a negative electrode, and is attached to the electrode by electrolysis. The electrolyte is composed of a compound capable of producing ions that can be doped dissolved in an aprotic organic solvent. The atomic ratio of hydrogen atoms/carbon atoms and the shape of the insoluble and infusible substrate used as an electrode can be arbitrarily selected depending on the performance, size, shape, etc. of the intended battery. Since the battery utilizes a reaction, it is important for the electrode to have a low electrical resistance and a large surface area in order to obtain a high-performance battery. Therefore, the atomic ratio of hydrogen atoms/hydrogen atoms is preferably 0.33 to 0.15.
It is between 0.30 and 0.20. When the atomic ratio is greater than 0.33, electrochemical doping becomes difficult due to high electrical resistance, and the electrical conductivity of the insoluble and infusible substrate after doping does not become sufficiently small, making it impossible to obtain a high-performance battery. In addition, if the atomic ratio is less than 0.15, the polyacene skeleton structure due to thermal decomposition will be sufficiently developed and the electrical resistance will be small, but it will not be possible to dope the doping agent sufficiently by electrochemical doping, making it difficult to obtain a high-performance battery. Can not. In order to increase the surface area per volume, the electrode shape is usually film-like, paper-like, cloth-like, or perforated plate. As described above, a major feature of the present invention is that the composition and shape of the insoluble and infusible substrate used for the electrode can be arbitrarily selected depending on the purpose. It is something that cannot be obtained. Compounds that can be used in the electrolytic solution and can generate ions that can be doped into the electrode include alkali metal or tetraalkylammonium halides, perchlorates, hexafluorophosphates, hexafluoroarsenates, and tetrafluoroarsenates. Examples include boronates, specifically LiI, NaI, NH ₄ I, LiClO ₄ , LiAsF ₆ ,
LiBF ₄ , KPF ₆ , NaPF ₆ , (n-C ₄ H ₉ ) ₄ NClO ₄ ,
(n- _C4H9 ) _{4NAsF6 ,} (n- _C4H9 ) _{4NPF6 , etc. are} mentioned. Aprotic organic solvents are used as solvents for dissolving the above compounds, such as ethylene carbonate,
Propylene carbonate, γ-butyrolactone,
dimethylformamide, dimethylacetamide,
Examples include dimethyl sulfoxide, acetonitrile, dimethoxyethane, tetrahydrofuran, methylene chloride, or a mixture thereof, but it is important to select the electrolyte in consideration of the solubility of the compound used as the electrolyte, battery performance, etc. The concentration of the above compound in the electrolyte is at least 0.1 mol/mol to reduce the internal resistance caused by the electrolyte.
The amount is usually 0.5 to 1.5 mol/. As described above, the battery of the present invention uses an insoluble and infusible substrate containing a polyacene skeleton structure as a positive electrode and/or a negative electrode, and a compound that can generate ions that can be doped into the electrode by electrolysis in an aprotic organic solvent. The dissolved material is configured as an electrolyte, and the battery function is achieved by doping the positive electrode or negative electrode with an electron-accepting substance or an electron-donating substance. As a method for doping an insoluble and infusible substrate containing a polyacene skeleton structure with an electron-accepting substance or an electron-donating substance used in the present invention, a method conventionally used for conductive organic polymer materials such as polyacetylene or polyp-phenylene is used. Essentially the same doping methods can be used. Comparing the doping method of the present invention with conventionally known doping methods and describing the differences, the above-mentioned insoluble and infusible substrate used in the present invention is not only extremely stable against oxygen, but also has various other properties. Since it has high stability against chemical agents, the doping method of the present invention allows doping to be carried out under stronger conditions than conventionally known methods, for example, at a temperature of 100 to 200°C. Therefore, according to the doping method of the present invention, doping can be performed more efficiently and advantageously than conventionally known methods. When the electron-donating substance is an alkali metal, doping can be carried out by contacting the molten alkali metal or the vapor of the alkali metal with an insoluble and infusible substrate; for example, an alkali metal naphthalene complex formed in tetrahydrofuran Doping can also be carried out by bringing the material into contact with the insoluble and infusible substrate. When the electron-accepting substance is a halogen or a halogen compound, doping can be easily carried out by bringing these gases into contact with the insoluble and infusible substrate. When the electron-donating substance or electron-accepting substance can generate ions in the above-mentioned aprotic organic solvent, doping is carried out electrochemically by applying a DC voltage to the insoluble and infusible substrate as a negative or positive electrode. be able to. For example, when lithium perchlorate is dissolved in tetrahydrofuran, lithium ions and perchlorate ions are generated. When the insoluble and infusible substrate is immersed in the solution and a DC voltage is applied, the positive electrode side is doped with perchlorate ions and the negative electrode side is doped with lithium ions. When doping only the positive electrode or the negative electrode, an inert metal such as platinum, palladium, gold, etc. is used as the counter electrode. Doping conditions such as applied voltage and doping time can be arbitrarily determined in consideration of the size and shape of the electrode, the type of electrolyte, the amount of doping, and the like. Although any method may be used to dope the doping agent into the insoluble and infusible substrate, an electrochemical method is preferred in the present invention. Particularly suitable is the method of doping by electrochemical methods in the cell after assembly. The battery of the present invention uses an insoluble and infusible substrate containing a polyacene skeleton structure as a positive electrode and/or a negative electrode, and a doping agent dissolved in an aprotic organic solvent as an electrolyte. This method utilizes chemical or electrochemical doping and electrochemical undoping of a doping agent to an insoluble and infusible substrate used as a doping agent. That is, energy is stored by chemical or electrochemical doping of a doping agent into an insoluble, infusible substrate;
It is extracted externally as electrical energy through electrochemical undoping. Batteries according to the invention are divided into two types. The first type is a battery that uses an insoluble and infusible substrate containing a polyacene skeleton structure in both the positive and negative electrodes, and the second type uses an insoluble and infusible substrate in the positive electrode and an alkali metal or its anode. This is a battery that uses electrodes made of alloys. The first type is preferable for secondary batteries and for weight reduction, and the second type is preferable for batteries requiring high output, especially batteries using lithium metal for the negative electrode. The shape and size of the electrode, which is made of an insoluble and infusible substrate placed inside the battery, can be arbitrarily selected depending on the intended battery, but since the battery reaction is an electrochemical reaction on the electrode surface, it is possible to It is advantageous to increase the surface area as much as possible. Further, as a current collector for extracting current from the base to the outside of the battery, the base or a base doped with a doping agent may be used, but other conductive materials that are resistant to corrosion against the doping agent and the electrolyte may be used. Materials such as carbon, platinum,
Metals or alloys such as gold, copper, nickel, etc. can also be used. When the insoluble and infusible substrate has a high electrical resistance, or is in the form of a film or cloth, it is preferable to use a current collector in which carbon is a metal in terms of performance or battery assembly. In this case, the connection between the electrode and the current collector is to bury a part of the current collector in the electrode, press the current collector to the electrode, or create a metal layer on a part of the electrode by plating, vapor deposition, etc. to collect the current at that part. This can be done by adhering the electric body. 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, and 1 is an insoluble and infusible substrate containing a polyacene skeleton structure made of a positive electrode film, cloth, or porous plate, and has an electron-accepting property. It may be doped with a doping agent or may be undoped. 2 is a negative electrode, which is an insoluble and infusible substrate containing a polyacene skeleton structure in the form of a film, cloth, or porous plate, and may be doped with an electron-donating doping agent or not; must be in the same state. That is, if the positive electrode is doped, the negative electrode also uses a doped insoluble and infusible substrate, and if it is undoped, the negative electrode also uses an undoped substrate. After assembling the battery, voltage is applied from an external power source. Then, both electrodes are doped with a doping agent. 3 is a current collector for extracting current from each electrode to the outside of the battery case or for supplying current for electrochemical doping, that is, charging, and a voltage drop is caused at each electrode and external terminal 7 by the method described above. Not connected like that. Reference numeral 4 denotes an electrolytic solution in which the aforementioned compound capable of producing ions that can be doped into both positive and negative electrodes is dissolved in an aprotic organic solvent. The electrolytic solution is usually in a liquid size, but it can also be used in a gel or solid form to prevent leakage. A separator 5 is arranged for the purpose of preventing contact between the positive and negative electrodes and retaining the electrolyte. The separator is a non-electron conductive porous body with continuous pores that is resistant to electrolytes, doping agents, and electrode active materials such as alkali metals, and is usually made of glass fiber cloth, nonwoven fabric, polyethylene, polypropylene, etc. Cloths, nonwoven fabrics, and porous bodies made of synthetic resins are used. The thickness of the separator is determined in consideration of the amount of electrolyte retained, flowability, strength, etc., which is preferable to be thin in order to reduce the internal resistance of the battery.
Both the positive and negative electrodes and the separator are fixed in the battery case 6 so as not to cause any practical problems. shape of the electrode,
The size etc. are appropriately determined depending on the shape and performance of the intended battery. For example, to manufacture thin batteries, electrodes in the form of film or cloth are suitable; to manufacture large capacity batteries, electrodes in the form of film, cloth, or perforated plates can be laminated alternately with positive and negative electrodes. can. Above, we have explained the case where an insoluble and infusible substrate is used for both electrodes, but basically the same is true when using the substrate for the positive electrode and an alkali metal or its alloy for the negative electrode, but an insoluble and infusible substrate doped with a doping agent in advance Preferably, a substrate is used. The battery of the present invention uses an insoluble and infusible substrate containing a polyacene skeleton structure that has better oxidation resistance, heat resistance, and moldability than conventionally known organic semiconductors as a positive electrode and/or negative electrode, and an electron-accepting substance in the electrode. Alternatively, it is a battery in which the electrode active material is doped with an electron-donating substance, and the electrolyte is a compound that generates ions that can be doped into the electrode by electrolysis, dissolved in an aprotic organic solvent.
The purpose of the present invention is to provide a new high-performance battery that can be made lighter and thinner, and has a higher capacity, higher output, and longer life at a lower cost. The present invention will be specifically explained below using Examples. Example 1 A nonwoven fabric made of phenolic resin fibers (manufactured by Nippon Kynol Co., Ltd., weight 500 g/m ² ) was immersed in a 10% by weight methanol solution of resol-type phenolic resin, squeezed with a mangle, and air-dried. Phenol resin fiber/resol type phenol resin = 9/1
(Weight ratio) prepreg was made. One sheet of the prepreg is heated to 150°C and molded for 20 minutes.
A porous plate with a thickness of 1 mm was obtained by curing for 30 minutes under a pressure of Kg/cm ² . This board was placed under a nitrogen atmosphere.
Heat treatment was performed at 480°C to 700°C to obtain insoluble and infusible substrates containing polyacene skeleton structures with different atomic ratios of hydrogen atoms/carbon atoms. The resulting perforated plate is cut into pieces of 1 cm wide and 3 cm long, and platinum wire is generally glued with conductive adhesive and placed on both sides of lithium foil of the same size with 1 mm thick glass fiber paper (separator) in between. and concentration 0.5
A battery was constructed by immersing 2 cm into a propylene carbonate solution of lithium perchlorate at mol/l.
Next, a DC voltage of 10 V was applied for 2 hours using the insoluble and infusible substrate as the positive electrode and the lithium foil as the negative electrode, and then the open circuit voltage and short circuit current were measured. The results are shown in Table 1. Table 1 shows that the atomic ratio of hydrogen atoms to carbon atoms of the insoluble and infusible substrate containing a polyacene skeleton structure is from 0.33 to 0.15, preferably from 0.30 to 0.20.

[Table] Example 2 The atomic ratio of hydrogen atoms/carbon atoms obtained in Example 1 is
A porous plate made of a 0.23 insoluble and infusible substrate was cut out to a width of 1 cm and a length of 3 cm in the same manner as in Example 1, and a platinum wire for current collection was glued to one end with a conductive adhesive, with a thickness of 1 mm between the two sheets. A pair of electrodes were assembled by inserting glass fiber paper, and a battery was assembled using a propylene carbonate solution of lithium perchlorate with a concentration of 0.5 mol/ml as the electrolyte. Next, a DC voltage of 15 V was applied for 3 hours using one of the insoluble and infusible substrates as a positive electrode and the other as a negative electrode, and then the open circuit voltage and short circuit current between both electrodes were measured, and they were 3.0 V and 3 mA, respectively. Also, when discharged at a constant current of 1 mA for 30 minutes, the open circuit voltage was
It became 1.8V. When 15V DC voltage was applied again for 30 minutes, the open circuit voltage recovered to 3.0V. Example 3 A pair of electrodes were assembled in the same manner as in Example 2, and a battery was assembled using a propylene carbonate solution of tetrabutylammonium produced from perchlorate at a concentration of 1 mol/molar as the electrolyte instead of the lithium perchlorate solution.
Next, after applying a DC voltage of 10 V for 5 hours, the open circuit voltage and short circuit current were measured and found to be 2.8 V and 5 mA, respectively. Example 4 A solution of novolak resin with a number average molecular weight of 1000/methanol/formalin (aqueous solution with a concentration of about 37%) mixed in a weight ratio of 3/3/1 was poured onto a glass plate and stretched using an applicator. .
Thereafter, the film was air-dried for about 30 minutes to remove methanol, and then placed on a glass plate in 5N hydrochloric acid for curing reaction at a temperature of 70°C for 90 minutes. Thereafter, it was thoroughly washed with warm water and air-dried for about one day to obtain a cured phenolic resin film with a thickness of 20 μm. The obtained resin film was heated to 670°C in a nitrogen gas atmosphere.
By heating to ℃, the atomic ratio of hydrogen atoms/carbon atoms becomes
An insoluble and infusible film containing a polyacene skeleton structure of 0.25% was obtained. The film is 1cm wide and 3cm long.
Cut into cm pieces and glue a part of one end to a carbon plate with conductive adhesive to make two sheets, and use them as separators to make a thick
A pair of electrodes was made using 0.2 mm paper. The obtained electrode was immersed in a saturated solution of lithium iodide in tetrahydrofuran, and a DC voltage of 10 V was applied for 2 hours. Open circuit voltage is 3.0V, short circuit current is 1mA
It was hot.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing the basic configuration of a battery according to the present invention, in which 1 is a positive electrode, 2 is a negative electrode, 3 is a current collector,
4 is an electrolyte, 5 is a separator, 6 is a battery case,
7 represents an external terminal.

Claims (1)

[Scope of Claims] 1. An insoluble and infusible heat-treated product of an aromatic condensation polymer consisting of carbon, hydrogen and oxygen, containing a polyacene skeleton structure with an atomic ratio of hydrogen atoms/carbon atoms of 0.33 to 0.15. The positive electrode or/
and an organic electrolyte battery, characterized in that the negative electrode is an electrolytic solution prepared by dissolving in an aprotic organic solvent a compound capable of producing ions that can be doped into the electrode by electrolysis. 2. Claim 1, wherein the aromatic condensation polymer is a condensate of phenol and formaldehyde.
The organic electrolyte battery described in Section 1. 3 The insoluble and infusible substrate containing a polyacene skeleton structure has a DC conductivity of 10 to 10 ^-7 Ω ^-1 cm ^-1 at room temperature.
An organic electrolyte battery according to claim 1. 4 Compounds that can generate ions that can be doped include LiI, NaI, NH ₄ I, LiClO ₄ , LiAsF ₆ ,
LiBF ₄ , KPF ₆ , NaPF ₆ , (n-C ₄ H ₉ ) ₄ NClO ₄ ,
The organic electrolyte _battery according to claim 1 _{, which} is (n- _C4H9 ) _4NAsF6 or ( _n - _C4H9 ) _4NPF6 . 5 The aprotic organic solvent is propylene carbonate, γ-butyrolactone, dimethylformamide, dimethylacetamide, dimethyl sulfoxide, ethylene carbonate, dimethoxyethane,
The organic electrolyte battery according to claim 1, which is tetrahydrofuran, methylene chloride, or a mixture of two or more thereof. 6. The organic electrolyte battery according to claim 1, wherein the positive electrode is an insoluble and infusible substrate containing a polyacene skeleton structure, and the negative electrode is an alkali metal or an alkali metal alloy. 7. The organic electrolyte battery according to claim 6, wherein the alkali metal is lithium. 8. The organic electrolyte battery according to claim 1 or 6, wherein the insoluble and infusible substrate containing a polyacetone skeleton structure is a film, plate, perforated fiber, cloth, nonwoven fabric, or a composite thereof.