JPH03167712A - Carbonaceous solid electrolytic material and solid electrolytic battery using it - Google Patents

Abstract

PURPOSE:To obtain the light carbonaceous solid electrolytic material having excellent formability by composing the carbonaceous material of sulfonated carbonaceous material obtained by a treatment with the sulfonating agent. CONSTITUTION:Carbonaceous material is composed of the sulfonated carbonaceous material obtained by a treatment with the sulfonating agent. Carbonaceous mesoface and (or) raw coke manufactured by a thermal treatment of pitch class, which is one of the heavy bituminous material, are desirably used as the raw material of the solid electrolyte. Concretely, carbonaceous material as raw material is treated with the sulfonating agent such as sulfuric acid and/or fuming sulfuric acid, and the treated material is distributed in the water to be washed once with water or filtrated with a filter as it is to eliminate the residual sulfuric acid or fuming sulfuric acid, and sulfone group is led into carbonaceous mesoface. Light carbonaceous solid electrolytic material is obtained which is stabilized in the air and has excellent formability for manufacturing through a relatively simple process.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a solid electrolyte for batteries, and in particular to a carbonaceous solid electrolyte material that is lightweight and has excellent moldability, and a leak-free battery using this electrolyte. be.

[Background of the invention]

In recent years, with the development of semiconductor technology, the power consumption of electronic devices has been decreasing. Along with this, it has become desirable for batteries used in electronic devices to be smaller, thinner, and lighter. Solid electrolyte batteries are available to meet this demanding demand. Solid electrolyte batteries have ionic conductivity in the electrolyte.
Because it uses a solid electrolyte that does not use any external components, there is no leakage from the battery, and therefore, there is no need to take measures to prevent leakage, and the container can be made lighter and simpler. .

Currently, solid electrolyte batteries that are already in practical use or in the development stage include Na-S batteries, LL-12 batteries,
t. There are i-v2o5 batteries, etc.

Na-S electric current uses Na as the negative electrode active material, S as the positive electrode active material, and β' alumina (β' alumina), which is conductive to Na ions, as the electrolyte.
3Na2・16Al203) 3 using ceramics
It is attracting attention as a high-temperature battery that operates between 00°C and 350°C.

In addition, Li-I solid electrolyte batteries use metallic lithium as the negative electrode active material, a complex of iodine and poly-2-vinylpyridine as the positive electrode active material, and LiI as the solid electrolyte. Utilizing its characteristic high electromotive force, it is widely used for cardiac and LA pacemakers.

Furthermore, the Li-V205 battery is a solid electrolyte battery that uses metallic lithium as the negative electrode active material, ■205 as the positive electrode active material, and a polyphosphazene/lithium salt composite as the solid electrolyte. Similarly, since a polymer is used for the electrolyte, it has flexibility and adhesion, and has the advantage of being able to follow changes in the shape of the object it comes in contact with, and can be shaped into any shape.

However, these solid electrolyte batteries have the following problems. For example, Na-S batteries are heated to temperatures of 300°C to 350°C during use due to the high temperature type battery.
It needs to be used at 1°C, which severely limits its uses. Moreover, for this reason, it cannot be made smaller or thinner, and its specific applications are limited to large-sized ones such as those for automobiles and industrial use. On the other hand, in a Li-1 battery or a Li-V205 battery, metallic lithium as a negative electrode active material is extremely active, so the manufacturing process and sealing technology for the conductive layer are complicated in order to resist oxidation and moisture. Furthermore, since compounds with relatively complex structures are used as these solid electrolyte materials, the reaction process for combining them is also complicated, which is advantageous in terms of cost. For example, Lt-V20
The reaction process for synthesizing the solid electrolyte polyphosphazene/lithium salt composite with five electrodes is complicated as follows.

That is, first, a dichloro-phosphazene trimer is made into a polydichloro-phosphazene by thermal ring-opening polymerization, and this is reacted with an alcoholate of oligoethylene glycol monomethyl ether to obtain a methoxyoligoethyleneoxypolyphosphazene. This requires a complicated process of dissolving a desired lithium salt at a desired concentration in an ethylene glycol dimethyl ether solution of this polymer and removing the solvent to synthesize a composite polymer solid electrolyte.

[Summary of the invention]

The present invention has been made in view of the above-mentioned prior art, and provides a carbonaceous solid electrolyte material that is lightweight, stable in the air, and can be prepared in a relatively simple process, and a battery using the same. The purpose is to

The present inventor uses carbonaceous +4 materials such as pitch, mesophase ah pitch, carbonaceous mesophase, and raw coke, which can be produced industrially inexpensively and stably by hand, as raw materials, and by contacting them with a sulfonating agent, It is possible to introduce a sulfone group into the carbonaceous material component by a relatively simple method, and the sulfonated carbonaceous material obtained in this way has excellent properties as a solid electrolyte for batteries. The present invention has been completed based on this discovery.

That is, the carbonaceous solid electrolyte of the +4 family according to the present invention is characterized by consisting of a sulfonated carbonaceous material obtained by treating a carbonaceous material with a sulfonating agent.

Furthermore, the solid electrolyte battery according to the present invention is made of a carbonaceous solid electrolyte material made of a sulfonated carbonaceous material t4 obtained by treating a carbonaceous material with a sulfonating agent, and an electrode of 100%, which is the older brother of the two types. Become jF! There are some f symptoms.

[Specific description of the invention]

As the carbonaceous material used as a raw material for the solid electrolyte in the present invention, carbonaceous mesophase and/or raw coke produced by heat treatment of pitch, which is a heavy bituminous material, can be preferably used. The pitches used as raw materials for these carbonaceous + 4 materials are coal tar pitch, coal-based pitch of coal heptomide, petroleum distillation residue oil, naphtha tar pitch produced as a by-product during the thermal decomposition of naphtha, and fluid catalytic cracking of naphtha. (FCC method) as a by-product such as FCC decant oil, pitch obtained by thermal decomposition of synthetic polymers such as PVC, etc., especially if the carbide has an optically anisotropic structure. The type doesn't matter. These pitches are heat treated at about 350°C to 500°C. This heat treatment produces carbonaceous mesophase (including raw coke). The formation of carbonaceous mesophase can be easily detected by observing the heat-treated product under a polarizing microscope. That is, the carbonaceous mesophase is identified as an optically anisotropic phase in pitch, which is an optically isotropic phase. At this time, the form of the carbonaceous mesophase may be mesophase spherules generated at an early stage of carbonization, or a so-called bulk mesophase formed by growing and coalescing these spherules.

In the following description, a case in which carbonaceous mesophase is used as a raw material will be explained in particular, but the present invention is not limited thereto.

The heat treatment conditions that produce the carbonaceous mesoface can be determined by the elemental composition of the carbonaceous mesophase separated from the heat treated pitch. In particular, this heat treatment is preferably performed so that the hydrogen content becomes 2% by weight or more. This is because carbonaceous mesophase is highly heat-treated until the hydrogen content is reduced to 2% by weight or less, and the aromatic planar molecules forming the mesophase develop greatly and become chemically stable, making it easy to form carbonaceous mesophases. This is because it becomes difficult to introduce a sulfone group, and even if a sulfone group is introduced, the electronic conductivity increases, making it unsuitable as a battery electrolyte that requires ionic conductivity.

Using the carbonaceous material obtained as described above as a raw material, it is treated with a sulfonating agent such as sulfuric acid and/or fuming sulfuric acid. Next, the treated product is once dispersed in water and washed with water, or directly passed through a filter to remove residual sulfuric acid or fuming sulfuric acid. Through these operations, sulfone groups are introduced into the carbonaceous mesophase. In the above,
The conditions for introducing a sulfone group into the carbonaceous mesophase are as follows.

First, the sulfonating agent may be sulfuric acid, oleum, or a mixture thereof, and the mixing ratio of sulfuric acid and fuming sulfuric acid may be any ratio from 0 to 100% to 100 to 0%. . In the reaction, the quantitative ratio of sulfuric acid, oleum, and a mixture of these reagents to the carbonaceous mesophase is 5 reagents per 1 g of carbonaceous mesophase.
It is preferable to set it as ml or more. If the ratio is lower than this, the amount of sulfone groups introduced will be insufficient, and the cell electromotive force will not be large enough.Also, during the reaction, some reagents will be absorbed into the carbonaceous mesophase particles, and the This is not preferable because the liquid phase may be lost and the reaction temperature may become non-uniform. As the sulfonating agent, in addition to the above, chlorosulfonic acid, sulfurous acid, sulfur trioxide, surifyl chloride, sodium sulfite, an addition compound of dioxane and sulfuric anhydride, and the like can be used.

The reaction temperature and time depend on the raw materials used, but are generally preferably 50 to 200°C and 10 to 300 minutes. 50'
Under gentle conditions such as less than C or less than 10 minutes, the amount of sulfone groups introduced is small, and this is used as an electrolyte to generate electricity! When assembled, there are cases where a satisfactory electromotive force cannot be obtained. In addition, under severe conditions such as 200° C. or 300 minutes or more, the amount of sulfone groups introduced does not change much from the above-mentioned preferred conditions, and the yield of sulfonated mesophase after the reaction decreases. Therefore, appropriate conditions suitable for each raw material are selected from the above-mentioned preferred temperature and time ranges.

The inventors of the present invention further investigated various aspects of the method and found that there is a certain relationship between the sulfone group introduced by the sulfonation treatment and the sulfur content of the sulfonated product. That is, according to the findings of the present inventors, good results can be obtained by selecting conditions in which the sulfur 6-M increases by 2.5 weight 96 or more compared to the raw material (untreated) due to the sulfonation treatment. Understood. Tsuchisoka with sulfur content is 2.5
If it is less than % by weight, when a battery is assembled using this as an electrolyte, the amount of sulfone groups involved in the battery reaction will be insufficient, and sufficient electromotive force may not be obtained.

In the present invention, the upper limit of the sulfur content is not particularly limited, but when the above-mentioned reaction temperature is in the range of 50 to 200°C, it is at most 10% by weight.

Furthermore, the introduction of sulfone groups into the carbonaceous mesophase can be confirmed by infrared spectroscopy.

When the infrared spectrum of the sulfonated carbonaceous mesophase, that is, the sulfonated mesophase, was measured under the above reaction conditions, the infrared spectrum was 1180ca+-' and 1230cm.
A peak is clearly observed at the -' position, indicating the presence of a sulfone group. The state of the sulfonated mesophase obtained in this way is in the form of a free-flowing powder with a bulk density of about 0.6 g/ci, and can be easily molded by a conventional method, for example, with a bulk density of about 100 kg/cJ. When molded under pressure, various shapes with a bulk density of about 1.0 g/cm can be obtained.

It is possible to generate an electromotive force by sandwiching the sulfonated mesophase thus obtained between two different types of electrodes to form a battery set L2.

The electrodes used here are metals such as lead, silver, and copper, lead dioxide,
Oxides such as silver oxide and oxidized steel, or conductive polymer compounds,
Furthermore, a conductive polymer compound doped with iodine or persalt may be used. Choose a substance that is easily reduced for the positive electrode, and a substance that is easily oxidized for the negative electrode. When a sulfonated mesophase, which is a solid electrolyte, is sandwiched between two different types of electrodes, a reduction reaction of the positive electrode active material at the positive electrode and an oxidation reaction of the negative electrode active material occur at the negative electrode due to the action of the sulfone group, which is a strong acidic group, resulting in an electromotive force. is born. In this case, the solid electrolyte used, sulfonated mesofes, can be selected from various forms depending on the purpose.

That is, the powder may be incorporated into something like a retainer as it is, or it may be molded and used alone. At this time, it is also effective to include water in order to activate the movement of ions in the electrolyte involved in the reaction and improve the electromotive force. In this case, the water content is 30% by weight.
In the following, even when the electrolyte is pressurized for molding, water does not seep out, and the electrolyte can be used sufficiently as a solid electrolyte. Furthermore, the sulfonated mesophase obtained here is thermally stable, and the sulfone group remains unchanged even after heat treatment at 300° C., so it can be expected to be used as an electrolyte for high-temperature electrodeposition.

Hereinafter, the present invention will be explained in more detail with reference to Examples.

(Example 1) Raw coke obtained by a delayed coal force method was pulverized to a particle size of 250 μm or less. This elemental composition is carbon 9
4. 9 N m 96, hydrogen 3.3 weight? 6,
Nitrogen 0.5% by weight, sulfur 0. 5 heavy children Oo, oxygen 0.
8 weight? There were 6. The volume of this 20 g is m50
The mixture was added little by little to 240 ml of 96% sulfuric acid in a L'llm1 Erlenmeyer flask. After adding the entire amount, add 1
Heated in an oil bath heated to 00°C for 1 hour. Next, it was filtered through a glass filter (No. 4), thoroughly washed with water, and then dried. The yield was 12690. Also, the elemental composition of the sulfonated mesophase obtained in this way is carbon 67.2% by weight, hydrogen 2.8% by weight, 9% by weight, nitrogen 0% by weight {)6, sulfur 7.9% by weight? 6. Oxygen 22.
It was 1% by weight. This sulfonated mesophase was used as a battery electrolyte in a phenol resin tube with an inner diameter of 10 mm reinforced with a stainless steel tube, and lead dioxide powder was added as a positive electrode active material at the bottom of the tube. I packed 0.5g on top of the 2g stuffed stuff. This was pressurized from the top with a stainless steel push rod and molded, and water was added to the sulfonated mesoface If? 20 weight m 96 iii. After removing the stainless steel push rod, a temporary lead having a thickness of 0.5 mm was brought into contact with the sulfonated mesophase as a negative electrode active material. A resistor of IMΩ was loaded onto the battery thus assembled, and the voltage at both ends of the resistor was measured and found to be 1.4V.

(Example 2) Elemental composition is carbon 95, double ffi? o, hydrogen 4.4 weight 06, nitrogen 0 weight %, sulfur 0.1 weight 96, oxygen 0.3
The weight of carbonaceous mesoface is crushed to a diameter of 250μ.
m or less. This 2 Q g was added little by little to a 500 ml Erlenmeyer flask containing 240 ml of 96% sulfuric acid. After adding the entire amount, it was heated for 1 hour in a bath heated to 200°C in advance.

Next, with a glass filter (No. 4)? After passing through the door and thoroughly washing with water, it was dried. The yield is 1 4 7 9
It was 6. The elemental composition of the sulfonated mesophase thus obtained was 57.4% by weight of carbon, 3.1% of hydrogen, and 1% of hydrogen.
% by weight, 0% by weight of nitrogen, 7.4% by weight of sulfur, 32% by weight of oxygen.
It was 1% by weight. This sulfonated mesophase was used as a battery electrolyte in a phenolic resin tube with an inner diameter of 10 mm, reinforced with a stainless steel tube, and 0.0 mm of lead dioxide powder was placed at the bottom as a positive electrode active material. I packed 0.5g on top of the 2g stuffed stuff. This was pressurized from the top with a stainless steel push rod and molded, and water was added to the sulfonated mesoface at a rate of 10% by weight.
It was added dropwise in weight%. After removing the stainless steel push rod, a zero-thickness film was placed on the sulfonated mesophase as the negative electrode active material.
．． A 5 m+g lead plate was brought into contact. A resistor of IMΩ was loaded onto the battery thus assembled, and the potential difference across the resistor was measured and found to be 1.8V.

Claims (6)

[Claims] 1. A carbonaceous solid electrolyte material comprising a sulfonated carbonaceous material obtained by treating a carbonaceous material with a sulfonating agent. 2. The carbonaceous solid electrolyte material according to claim 1, wherein the carbonaceous material is carbonaceous mesophase and/or raw coke obtained by heat treating pitches. 3. The carbonaceous solid electrolyte material according to claim 1, wherein the carbonaceous material has a hydrogen content of 2% by weight or more. 4. The carbonaceous solid electrolyte material according to claim 1, wherein the sulfonating agent comprises sulfuric acid or fuming sulfuric acid. 5. The carbonaceous solid electrolyte material according to claim 1, wherein the sulfur content of the sulfonated carbonaceous material is 2.5% by weight or more greater than the sulfur content of the carbonaceous material as a raw material. 6. A solid electrolyte battery comprising a carbonaceous solid electrolyte material made of a sulfonated carbonaceous material obtained by treating a carbonaceous material with a sulfonating agent, and electrodes made of two different materials.