JPS6123945B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to compositions of materials with high ionic conductivity. In particular, it has excellent mechanical properties, such as the ease of forming and forming films into arbitrary shapes, which are inherent to polymers, and also has the properties of extremely high ionic conductivity of metals belonging to groups and groups of the periodic table. The present invention relates to an ionically conductive solid composition having an ion conductive solid composition. Conventionally, ion conductive materials have mainly been (a) so-called electrolyte solutions in which electrolytes are dissolved in water or organic solvents, and (b) beta alumina β-.
Al ₂ O ₃ , lithium iodide/alumina LiI−Al ₂ O ₃ ,
Solid electrolyte materials made of inorganic substances such as silver rubidium iodide RbAg ₄ I ₅ are known. Ion-conductive materials are used in a wide variety of industrial fields, but examples of their use as electronic components include primary batteries, secondary batteries, electrolytic capacitors, sensors, electrochromic display elements, and electrodes. It is widely used as a material for electronic components such as time-limiting elements and integral memory elements by detecting the integral value of electricity by precipitating metal. In recent years, in the field of electronics industry, not only high performance and miniaturization of electronic devices, but also high performance, small and thin electronic components, and high reliability as components are required. One of the requirements for highly reliable electronic components is that the materials used in the component first solidify, meaning that under the conditions in which the component is used, the material appears solid and flows like a liquid (hereinafter referred to as a fluid). (hereinafter referred to as a solid body). This is because when a fluid material is used in an electronic component, fluid often leaks from the inside of the component to the outside of the component. This leads to a deterioration in the performance of the electronic component and has an adverse effect on other electronic components near the electronic component, which ultimately causes the electronic device to malfunction. Therefore, when used as an ion conductive material in an electronic component, it can be said that an electronic component using a solid ion conductive material is more reliable than a fluid one. On the other hand, in order to obtain highly reliable parts using fluid ion-conductive materials, there are ways to make the parts completely airtight, but these end up resulting in expensive electronic parts that are often impractical. . Among the above-mentioned ion conductive materials, the electrolyte solution (a) is a fluid and has high reliability for the reasons mentioned above, but has the disadvantage that it cannot be used for inexpensive electronic components. On the other hand, the above-mentioned solid electrolyte material (b) has the advantage of being compatible with highly reliable electronic components since it is a solid body. However, there are very few solid electrolyte materials with high ionic conductivity, and most solid electrolyte materials have low ionic conductivity. Moreover, in order to obtain a solid electrolyte with high ionic conductivity using an inorganic compound, it is necessary to make full use of reaction operations that are considered extremely difficult, so there are currently very few practical examples. moreover,
Since most solid electrolyte materials are compositions of inorganic compounds, it is extremely difficult to mold them into arbitrary shapes and form them into films. That is, solid electrolytes made of inorganic compounds have the drawback of poor mechanical properties, such as ease of processing, which allows them to be molded and modeled into arbitrary shapes. For this reason, it has the disadvantage that the fields in which it can be used as an ion-conductive material are extremely limited. An intermediate form between the electrolyte solution of the above-mentioned ion conductive material (a) and the solid electrolyte of (b) is obtained by kneading an aqueous electrolyte solution, such as that used in dry batteries, into a paste-like form with an aqueous starch solution. There are other ionically conductive materials. Even though they are glue-like, they take on a form similar to that of a fluid under conditions of practical use. For example, in dry batteries, paper or non-woven fabric is used as a separator to prevent short circuits between the anode active material and the cathode active material. must be used. In reality, this separator separates the active materials of both electrodes and contains a paste-like ion-conductive material, so it can be used in the same way as a fluid such as an electrolyte solution. Even with a paste-like ion-conductive material, (a) liquid leakage occurs frequently, as is observed in ordinary dry batteries, and reliability is poor. (b) Furthermore, since it cannot be molded into any shape or formed into a film, it has the disadvantage that its applicable fields are extremely limited. If the aqueous solvent is removed by evaporation to an extent that does not cause liquid leakage, molding and film formation will not be impossible, but in this case, the ionic conductivity will drop significantly and it cannot be put to practical use. Furthermore, when water is used as a solvent, there are the following drawbacks.
(i) Water reacts electrochemically with most metals and corrodes them. Therefore, in application,
metallic materials in contact with ionically conductive materials containing water;
For example, there is a drawback in that the metal materials used for the electrode parts and the parts that seal the electronic elements are extremely limited. (ii) The decomposition voltage of water is approximately 1.2V, which is generally lower than that of organic solvents, and cannot be used at voltages higher than the decomposition voltage. (iii)
Ion conductive materials containing water are limited to operating temperatures close to the freezing point (0°C) and boiling point (100°C) of water, and maintain high and stable ionic conductivity at other temperatures. I can't.
(iv) In ionic conductive materials containing water, H ⁺ and OH ^- generated by ion dissociation of water also function as conductive carriers, and if you want to use only metal ions as conductive carriers, the number of carrier species will continue to increase. Instead, it forms an extremely complex conductive mechanism by ionically bonding with metal ions. For this reason, the ionic conductivity becomes unstable, making it unsuitable for use in, for example, a timing element or an integral storage element to detect an integral value of capacitance. The object of the present invention is to create a new ion-conductive material that solves these conventional drawbacks, namely, an ion-conductive solid material that has both high ion conductivity and excellent mechanical properties such as ease of processing and forming films into arbitrary shapes. The objective is to provide body compositions. According to the present invention, the electrolyte is composed of an electrolyte made of metal ions belonging to a group and/or group of the periodic table, an organic polymer compound having a dielectric constant of 4 or more, and an organic solvent that dissolves the electrolyte and the organic polymer compound. An ionically conductive solid composition is obtained. The first feature of the present invention is that the ionically conductive solid composition contains an organic solvent in order to eliminate the conventional drawbacks, particularly the many drawbacks that appear when water is used as a solvent. If an organic solvent is applied,
() It is stable with very little chemical reaction with various metal materials. () The decomposition voltage of organic solvent is higher than the decomposition voltage of water, which is 1.2V. () If an appropriate solvent is selected, the usable temperature range will be wider than in the case of water. () Very few organic solvents, like water, dissociate into H ⁺ and OH ^- ions and have a negative effect. For the above-mentioned reasons, the use of organic solvents has the advantage of making it possible to construct ion-conductive materials that are more stable and have a wider range of applications than conventional aqueous solvents.
On the other hand, the ionic conductivity τi tends to decrease compared to when a water solvent is used. The ionic conductivity σi generally increases in proportion to the product of the concentration ni of the carrier ionic species and its mobility μi. Therefore, effective organic solvents for increasing σi include those that (A) dissolve electrolytes at high concentrations and contribute to an increase in ni, and (B) dissolve not only electrolytes but also organic polymer compounds well. Organic solvents that provide uniform ion distribution and increase ion mobility are desirable. For this reason, the organic solvent is not limited to one type, and a mixed solvent of two or more types may be used. In this way, the organic solvent functions as a material for preparing the solid composition by dissolving the electrolyte and organic polymer compound, and ultimately remains in the solid composition to express the ionic conductive function. It is also an important constituent of ionically conductive solid compositions. The second feature of the present invention is that the ionically conductive solid composition contains an organic polymer compound.
This material can be molded into any shape by providing excellent mechanical processability inherent to organic polymer compounds.
It is hoped that this material will develop the ability to form a film. There is also a method of using an organic polymer compound simply as a binder, but in this case there is a certain limit to the improvement of ionic conductivity. In other words, the presence of an organic polymer acts as a steric hindrance when ions move, resulting in a tendency for the ion mobility μi to decrease. Therefore, in order to remove this obstacle to the movement of ions, the inventors thought of making the organic polymer swollen by impregnating it with an organic solvent that has excellent solubility for organic polymer compounds. . When organic polymers are in a swollen state, the distance between them is expanded, allowing ions to move freely. Furthermore, the interaction between ions and organic polymers is relaxed, and ion mobility is greatly improved. As the content of the organic solvent increases, the distance between the organic polymers becomes wider, and the organic polymers are completely dissolved to reach a solution state. In a solution state, it becomes a fluid and cannot be molded into a certain shape. Therefore, in order to maintain a certain solid state, it is necessary to specify the maximum content of organic solvent contained in the composition, and this maximum content is
It varies depending on the solubility of the organic polymer compound in the organic solvent, as well as the molecular weight and molecular weight distribution of the organic polymer compound. As a result of examining various organic polymer compounds that are effective in the present invention, it was found that the ionic conductivity σi significantly influences the dielectric constant ε of the organic polymer compound. Therefore, as a result of using various organic polymer compounds with different dielectric constants ε and examining the relationship between the ionic conductivity σi and the dielectric constant ε of the composition, it was found that when the organic polymer compound has ε of 4 or more, We have reached the conclusion that it is effective and exhibits a higher σi than the following. Relative permittivity ε of organic polymer compounds
It is thought that as a result of promoting ion dissociation in the electrolyte, during conduction, the ion carrier concentration ni increases and the ion mobility μi increases, thereby contributing to an increase in the ionic conductivity σi. In the end, the organic polymer compound used in the present invention that has a dielectric constant ε of 4 or more and is soluble in various organic solvents gave good results. A third feature of the present invention resides in the configuration of a solid composition containing a salt consisting of ions of metals belonging to groups and groups of the periodic table as an electrolyte. In order to exhibit high ionic conductivity, it is necessary for the metal salt to have low ionic dissociation energy and to have excellent solubility in organic solvents. As a result of examining electrolytes that are effective in the present invention from this point of view, it was concluded that salts consisting of ions of metals belonging to groups and groups of the periodic table are particularly effective. The larger the content of electrolyte in the solid composition, the more it contributes to increasing the electrical conductivity, but if it is present in a large amount, the composition becomes hard and brittle, and mechanical workability decreases. Furthermore, the larger the amount of organic solvent contained in the solid composition, the greater the mobility of ions and the higher the electrical conductivity, but if it is present in a large amount, the composition will soften and eventually become a fluid. . Therefore, there is a practical maximum value for the electrolyte and solvent contents. Furthermore, although this maximum value cannot be uniformly defined depending on the type and physical properties of the compounds constituting the solid body composition, as a result of various experiments, the maximum value of the electrolyte content is approximately 70 to 90 mol%, and the solvent The maximum content was between 50 and 90 wt%. Examples of the present invention will be described below. The measurement samples were prepared in such a way that the contents of the electrolyte and organic solvent in the ionically conductive solid composition did not exceed the maximum values mentioned above. [Example] An electrolyte solution in which an electrolyte was dissolved in an organic solvent and a polymer solution in which an organic polymer compound was dissolved in an organic solvent were prepared. The prepared electrolyte solution and polymer solution were mixed and sufficiently stirred until uniform. If it is difficult to obtain a uniform solution, a predetermined uniform solution can be obtained by stirring the mixed solution while heating it. after that,
The mixed solution was decompressed and degassed using a rotary pump. Next, a certain amount of this mixed solution was poured into a Teflon container prepared in advance, and the organic solvent was gradually evaporated while flowing nitrogen gas at a temperature from room temperature to below the boiling point of the organic solvent. This continued until the sample in the Teflon container changed from a solution state to a gel state. After the sample was in a gel state, the Teflon container containing the sample was transferred to a vacuum heating dryer and heated and dried under normal pressure at a temperature below the boiling point of the organic solvent used while flowing nitrogen gas. In addition, when the boiling point of the organic solvent was 100° C. or higher, it was dried by heating under reduced pressure. Heat drying is
The sample state continued until it changed from a gel state to a state that does not deform even if the container is tilted, that is, a solid state. After heating and drying, the Teflon container containing the sample was transferred into a glove box filled with nitrogen gas, and the sample was peeled from the Teflon container and cut into a certain shape. The cut sample piece was sandwiched between platinum black electrodes in a sandwich pattern, and the resistance value of the sample piece was measured using the AC two-terminal method. The measurement was performed in a nitrogen gas atmosphere using a measurement frequency of 1 KHz, and the conductivity σ of the sample was calculated from the resistance value, thickness, and area of the platinum black electrode of the sample piece. Combinations of the compounds constituting the solid composition sample, that is, various organic polymer compounds with different dielectric constants, organic solvents, and electrolytes, conducted using the sample preparation procedure and measurement method as described above, and the combinations thereof. The ionic conductivity σi of the solid body composition formed by is shown in the table. In addition, among the combinations of solid compositions in the table, the organic polymer compound does not completely dissolve in the organic solvent, but is partially dissolved or partially insoluble, or the organic polymer compound swells, or the electrolyte metal Although some of the salts were not completely dissolved in the organic solvent, some were dissolved, and others were not dissolved, but this did not affect the effects of the present invention such as sample preparation, moldability, and conductivity, so it was applied in this example. did. Further, as a result of measuring the electronic conductivity of all the samples, the electronic conductivity was 10 ^-14 S·cm ^-1 or less, so the conductivity σ measured by the above-mentioned measurement method is shown in the table as the ionic conductivity σi.

【table】

[Table] As is clear from the table, sample systems with relative permittivity ε of organic polymer compounds up to 3.3 (sample Nos. 1 to 3 in the table)
Samples up to 5) have an ionic conductivity σi of approximately 10 ^-12
~10 ^-10 S cm ^-1 , whereas in sample systems where the dielectric constant ε of the organic polymer compound is 4 or more (samples 6 or more in the table), the dielectric constant of the organic solvent is all Ten
Although σi is less than about 10 ^-8 ~
10 ^-6 S·cm ^-1 , and the result was that σi increased by about 10 ² to 10 ⁴ times compared to the sample system with a small relative dielectric constant ε. Therefore, the ε of the organic polymer compound constituting the solid body composition has a very large effect on the increase in σi, and furthermore, when ε of the organic polymer compound constituting the solid body composition is 4 or more, the σi increases. was found to have a significant effect on In addition, for comparison, σi was measured using a solid composition containing no organic solvent, and the results were 10 ^-12 S.
It showed a value of cm ^-1 or less, and exhibited almost no ionic conductivity. Of course, if the solid composition does not contain an electrolyte, it will act as an electrical insulator and will not exhibit ionic conductivity. Therefore, for the expression of ionic conductivity, the effect of the present invention is achieved when three components are present: an electrolyte, an organic solvent, and an organic polymer compound, and the dielectric constant ε of the organic polymer compound is 4 or more. is recognized. Further, the ion conductive solid composition system obtained by the present invention can be formed into any shape or formed into a film depending on the volume and concentration of the solution to be prepared and the shape of the container into which the solution is injected. You can also do that. For example, by reducing the concentration of the prepared solution and reducing the amount of solution injected into a Teflon container, it was possible to form a highly flexible thin film with a thickness of 100 μm or less over a wide area. If the film can be made thin, the resistance in the cross-sectional direction of the film decreases in proportion to the film thickness and inversely to the area, so it can be used in a wider range of applications. In addition, from σi in the table, if the film thickness and area are controlled, the ionically conductive solid composition according to the present invention can be used in batteries, electrolytic capacitors, sensors, electrochromic devices, time devices, integral memory devices, etc. It goes without saying that the electrically conductive material can be used in electronic components for practical purposes.

Claims (1)

[Claims] 1. An electrolyte consisting of ions of metals belonging to a periodic table group and/or group, an organic polymer compound having a dielectric constant of 4 or more, and a dielectric constant having excellent solubility in the electrolyte and the organic polymer compound.
an ion-conductive solid composition comprising an organic solvent of less than 10%, and the content of the organic solvent contained in the solid composition is at least an amount that causes the organic polymer compound to be swollen; 90wt% or less of the solid body composition, and the content of the electrolyte is about
An ion conductive solid composition characterized in that the amount is selected to be at least an amount that provides an ionic conductivity of 10 ^-8 S·cm ^-1 or more and at most 90 mo% of the solid composition.