JPS61203565A - Secondary battery and its electrode - Google Patents

Abstract

PURPOSE:To produce a highly-efficient light battery by preparing the electrodes from an unsaturated heterocyclic compound having condensed three hexarings where the central hexaring contains two different atoms located at para- positions and these atoms are selected from a group including O, S and N. CONSTITUTION:Electrodes 4 and 7 are prepared from a powder of phenoxazine, phenothiazine or a similar compound which is an unsaturated heterocyclic compound having condensed three hexarings where the central hexaring contains two different atoms located at para-positions and these atoms are selected from among O, S, N and substituted N atoms. After the electrodes 4 and 7 are packed into the central holes of glass fiber filter paper pieces 3 and 6 in an argon atmosphere, a diaphragm 5 made of glass fiber filter paper or similar material is compressed between the paper pieces 3 and 6 thereby constituting a secondary battery. By the means mentioned above, it is possible to produce a light battery with a high electric charge density per unit weight by performing reversible electrochemical doping on electrodes made of a usual low-molecular- weight organic compound without performing any polymerization.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention is directed to a group consisting of O, S, N, and substituted N, wherein the central six-membered ring contains two heteroatoms at para positions, and the heteroatoms are O, S, N, and substituted N. The present invention relates to an electrode for an electrochemical secondary battery comprising a fused 6°6.6-membered unsaturated heterocyclic compound selected from the following, and an electrochemical secondary battery using the same.

As pollution and energy issues become more important, expectations for the development of non-polluting electric vehicles and the like are increasing. In response to this, development of new types of batteries that are lightweight and have high energy density has become active, and attempts have been made to use various materials as electrodes. As a result, new secondary batteries using polymer compounds as electrodes have recently been developed.

The present invention relates to these new types of secondary batteries and electrodes used therein.

(Prior Art) It has been found that by carrying out a pressure doping operation on a polymer which is originally an insulator, its electrical conductivity can be improved to the level of a semiconductor or a good conductor. Examples of these high molecular weight polymers include polyacetylene, polyphenylene,
Examples include polythiophene and polypyrrole. Generally, the following two methods are employed for the doping operation.

(1) Substances exhibiting Lewis acidity (e.g. I2, PF5, SO3, FeC
J3 etc.) and chemical doping with alkali metals (Li, Na% etc.).

(2) Electrochemical doping, in which a polymer is brought into contact with an electrolyte in a liquid or solid phase, a positive or negative voltage is applied to the polymer, and the polymer is doped with cations or anions generated by ion dissociation of the electrolyte. Law.

Of the above two doping methods, in (2) electrochemical doping, the doped dopant can also be undoped, and since the doping operation and undoping operation usually occur reversibly, this principle' is applied. A secondary battery has been proposed.

As mentioned above, a new type of secondary battery that utilizes reversible electrochemical doping and dedoping phenomena has recently been invented using a phase process.

For example, a secondary battery using an electrode mainly composed of polyacetylene (% open/close 56-136469, JP-A-57-121
168, etc.), secondary batteries using electrodes mainly made of polyparaphenylene (% opening/closing 59-46760, etc.) and batteries
While there are secondary batteries (such as % open/close 57-197759) that use electrodes mainly composed of 1-thiophene, the positive electrode is made of 2,4.7-)linitrol-9-fluorenone, which is an ordinary organic compound that is not a polymer. Some examples of batteries using lithium metal as the negative electrode are also known (J, Elect-rochem-E3oc,
, Vol. 131, No. 1, p. 57 (1984)).

(Problems to be Solved) As a result of intensive research into the development of batteries that are lightweight and have high energy density, the present inventors found that
The present invention was completed based on the discovery that an unsaturated heterocyclic compound having a specific structure can be an excellent material for electrodes for electrochemical secondary batteries.

That is, an object of the present invention is to provide a lightweight, high-energy-density electrochemical secondary battery made of an organic material, an unsaturated heterocyclic compound having a specific structure, and an electrode for use therein.

Another object of the present invention is to provide an electrochemical secondary battery that does not require special operations such as polymerization to produce electrode materials, and uses common low-molecular-weight organic compounds as they are, and electrodes for use therein.

Still another object of the present invention is to provide an electrochemical secondary battery and an electrode for use therein, in which the electrodes that are no longer used can be easily disposed of by incineration.

(Means for Solving the Problems) Therefore, the gist of the present invention is that the central six-membered ring contains two heteroatoms at para positions, and the heteroatoms are composed of O, S, N and substituted N atoms. Condensation selected from the group 6.6.6
The present invention relates to an electrode for an electrochemical secondary IE cell using a member-unsaturated heterocyclic compound as an electrode constituent material, and an electrochemical secondary battery using the above-mentioned electrode as at least one electrode.

The battery and electrode of the present invention are for electrochemical doping operation (2) of the above-mentioned two types of doping operation, and do not use the conventionally proposed high molecular weight polymer. When using an organic compound of
There are signs.

In order to facilitate understanding of the mechanism of action of the battery and electrode of the present invention, the electrochemical description will be made below using polyacetylene t, which works by a similar mechanism.

This will be explained using the case of . When Bot 1 acetylene is used for both the positive and negative electrodes, the reaction at the positive electrode is a photolayer reaction due to the incorporation (doping) of anions generated by the dissociation of the electrolyte substance (salt) into the polyacetylene, and an anion release ( The negative electrode reaction is a charging reaction due to the uptake of cations and a discharging reaction due to the release of cations.

In this case, lithium perchlorate (LICl) is used as the electrolyte.
04), and if polyacetylene is represented by (CH)n, the reactions at both the positive and negative poles can be expressed by the following formulas.

Positive electrode reaction (CH)n +n x CA' 04-Negative electrode reaction (CH) +n, re+nxL+ Polyacetylene, which can be electrochemically oxidized or reduced in this way, can be used as a positive electrode or negative electrode of a secondary battery, so a negative electrode other than polyacetylene can be used. Alternatively, a secondary battery can be constructed not only by combining it with a positive electrode but also by using polyacetylene χ for both electrodes.

On the other hand, when polyacetylene is used for the positive electrode and lithium is used for the negative electrode, the reaction formulas at both the positive and negative electrodes are shown by the following formulas.

Positive electrode reaction (CH) +n, z: (JO4- These high molecular weight polymers such as polyacetylene must be synthesized by polymerizing monomers, but condensation 6.6.6 used in the present invention Member-unsaturated heterocyclic compounds do not need to be made into high-molecular polymers (monomers can be used as they are in electrodes for secondary batteries. Therefore, the polymerization process required for the production of high-molecular polymers is not required. It is also advantageous in terms of manufacturing costs.

Furthermore, since purification of monomers is much easier than purification of polymers, it is easy to obtain highly purified products. Although the purity of the unsaturated heterocyclic compound used as the battery or electrode of the present invention is not limited to %, it goes without saying that higher purity is better. The larger the amount of impurities that do not act as electrodes, the less the amount of substances that can act as electrodes per unit weight, which not only lowers the energy density per unit weight, but also causes doping depending on the type of impurity. This is because it is also possible that the dedoping effect is reduced and the function as an electrode material is inhibited.

In the present invention, the central six-membered ring used in the electrode material has two
heteroatoms in the para position, and the heteroatoms are O
Representative examples of fused 6.6.6-membered unsaturated heterocyclic compounds selected from the group consisting of , S, N and substituted N atoms are shown below, but are not limited to these. .

Phenothiazine Phenoxazine Phenazinethianthrene The condensed 6,6,6-membered unsaturated heterocyclic compound in the present invention can be used as a commercially available product without any special processing. The electrode of the present invention can be used as either a positive or negative electrode, but when used as a positive electrode, it is superior in charge/discharge repeatability, charge/discharge coulombic efficiency, storage stability in charged state, and flatness during discharge. It is preferable because

As mentioned earlier, in the reaction during charging of a battery using polyacetylene as the positive and negative electrodes, the 11-thickum cation (Ll) and perchlorate anion ((JO4
−) are trap-doped at the negative and positive electrodes, respectively, and these ions are dedoped during discharge. On the other hand, in the reaction during charging of a battery that uses polyacetylene as the positive electrode and lithium as the negative electrode, perchlorate anions are doped into the polyacetylene of the positive electrode, lithium cations are reduced and lithium is deposited on the negative electrode, and the reverse reaction occurs during discharge. These ions are dedoped.

On the other hand, as mentioned above, an organic compound other than a polymer, such as 2,4,7-11nitro-9, is used as the positive electrode of the secondary pond.
- Examples of using electron acceptors such as fluorenone are known, but these are always used only in the positive electrode, and metallic lithium is used in the negative electrode.During the electrical process, the lithium in the negative electrode is ionized and becomes lithium cations, which are then used in the positive electrode. It is believed that the electron acceptor is doped. Therefore, in these batteries, perchlorate anions do not participate in doping, and only lithium cations are doped and dedoped, so unlike batteries using polyacetylene, both electrodes use the same electron acceptor. You can't make batteries.

The condensed 6,6,6-membered unsaturated heterocyclic compound used in the present invention can be used for both electrodes at the same time as in the conventional polyacetylene electrode, and the low-molecular compound 'f! l! It is of a different type from the electrode used in J, and is also doped with anions such as perchloric acid.

In order to reduce the internal resistance in the 11th cell of the present invention, a metal plate, a metal mesh, a 6-membered unsaturated heterocyclic compound, etc.
Auxiliary collector electrodes (electrodes) made of graphite, carbon fiber paper, etc.
It is preferable to line it with Further, instead of using the unsaturated heterocyclic compound itself as an electrode, it is also possible to use it in combination with carbon black, since this has the effect of increasing the surface area and improving contact.

The electrolyte used in the present invention has a function as a dopant that is doped during charging and discharging,
This includes various electrolytes such as lithium perchlorate, Li
BF Tetraalkylammonium barchlorate,
LiPF6 or the like is used. Examples of non-aqueous solvents that dissolve these electrolytes include propylene carbonate, dichloromethane, and sulfolane p-. Water can also be used as a solvent if the electrodes used are both water-stable, in which case a wide range of electrolytes can be used, such as potassium iodide as a dopant, metallic materials as a cathode, etc. When using lithium metal, it is usual to use lithium metal, but it is not limited to lithium, and depending on the electrolyte used, zinc,
Other metals may also be used, such as aluminum and, in some cases, carbon.

When using metallic lithium as the negative electrode in the battery of the present invention, it is necessary to maintain ta under an argon atmosphere. Although other atmospheres can be used depending on the material of the negative electrode and the type of electrolyte used, it is generally reliable to use an argon atmosphere.

(Examples) The present invention will be explained in more detail with reference to Examples below, but these are merely illustrative and do not limit the present invention.

Example 1 Phenoxazine powder was used as the electrode material, carbon was used as the current collector, and =liUI (manufactured by Nippon Carbon Co., Ltd., trade name: Carboron) was used, and glass fiber tear paper was used as the diaphragm. A pond with a sandwich structure as shown in the figure was assembled.

FIG. 1 is a schematic explanatory diagram showing the structure of the battery used in this example, and FIG. 2 is a developed diagram thereof.

1 and 9 are current collector terminals, 2 and 8 are current collectors (both 1
2 x 17 dragon rectangles with a thickness of 0.31 m), 3 and 6 are made of glass fiber V5 paper with a 10 x 15 crane rectangular window in the center, and 50 m JF of phenoxazine powder (4 and 7) is filled in the window. 5 is a front cover of each glass fiber door paper diaphragm. 10 is a Teflon plate, and 11 is a diameter of 3
It is a 2m polyethylene container. The purpose of providing the Teflon plate 10 is to disperse the force applied from above with the knee of the cover 11 to ensure good and uniform contact between each layer of the battery, and to prevent the metal screw from directly touching the battery. It is for the purpose of

After assembling the battery Y, press it down from the top and add a propylene carbonate solution of lithium perchlorate (1
A charge/discharge test was conducted after adding 3TrLl of mol/l) so that 10 Teflon plates were immersed in the solution. All battery assembly, charge/discharge tests, etc. were conducted under an argon atmosphere.

Charging is performed by continuously flowing a constant current of KLOmA across the collector terminals for 60 minutes, and discharging is performed with a constant current of 0.5mA until the terminal voltage is 1.5mA. Discharge was performed until the voltage reached Ov.

This cycle is so good! 'Repeat 10 times! : The following results were obtained from D. Taking the 10th charge/discharge I cycle as an example, the terminal voltage is 2.7V immediately after charging starts.
It showed Y, but after that it gradually increased to 3.2■ after 60 minutes, and 3.2 immediately after the start of discharge. It showed OV, but then it gradually decreased to 1.0 after 83 minutes. Discharge was stopped when OV was reached.

Example 2 In Example I, 50 mj of phenoxazine powder was used as the positive electrode.
A battery was assembled in the same manner as in Example 1, except that lithium foil (length: 15 m, width: 10 m, thickness: 0.2 m) was used for the i and negative electrodes, and a charge/discharge test was conducted.

1 cycle of charging at a constant current of 1 mA for 60 minutes and discharging at a constant current of 0.5 mA until the terminal voltage reaches 1.0 ■.
This was repeated five times and the following results were obtained.

Taking the 15th charge/discharge cycle as an example, the terminal voltage during charging gradually increased from 4.4V to 4.8V. The terminal voltage during discharge is 3. immediately after the start of discharge. It was showing Ov, but after 96 minutes it dropped to 2.4V, and then it dropped rapidly to 1V after 118 minutes. Discharge was stopped when OV was reached.

This battery is characterized by the fact that 80% of the time the air is discharged is in the flat part with a high elevation.

Example 3 Instead of repeating the charge/discharge cycle 15 times in Example 2, the battery was charged a third time after repeating the charge/discharge cycle two times, left as it was for 24 hours, and then discharged for a third time.

Example 4 Phenothiazine 80 trdi fzt: 0.5 was used instead of phenoxazine 50d in Example I.
A battery similar to that of Example 1 was assembled except that a constant current of 1 mA was used instead of a constant current of 1 rLA, and a VCo was used, and a test was performed for three charge/discharge cycles, and the following results were obtained.

Example 5 Example 3 except that 80 ml of phenothiazine was used instead of 50 mJi' of phenoxazine in Example 3.
A battery similar to the above was assembled and tested for three charge/discharge cycles, and the following results were obtained.

*The time from the end of the 33rd charge until the start of discharging is 24 hours Example 6 A propylene carbonate solution of 50 mJ of phenoxazine and lithium perchlorate used in Example 1 (
1 mol/l) instead of 3 ml, each phenothiazine 80
A battery was assembled in the same manner as in Example 1, except that 3 ml of a propylene carbonate solution (1 mol/l) of LiBF4 and LiBF4 was used, and a charge/discharge cycle test was conducted seven times to obtain the following results.

Example 7 In place of 50 ml of phenoxazine in Example 1,
A battery similar to that of Example 1 was assembled except that 50 ml' of Energin was used, and a test was performed through three charge/discharge cycles, and the following results were obtained.

Example 8 A battery was assembled in the same manner as in Example 1 except that Tiantre 750 ml was used instead of 50 ml of phenoxazine in Example 1, and 7 tests consisting of two charge/discharge cycles were performed to obtain the following results.

(Effects of the Invention) According to the present invention, ordinary low molecular weight organic compounds can be used as electrodes without special operations such as polymerization, are lightweight, have high charge density per unit weight, and are not corrosive. Provided with easy-to-handle batteries and
This has good charge/discharge efficiency and excellent flatness of bottom pressure during discharge.

[Brief explanation of the drawing]

FIG. 1 is a schematic explanatory diagram showing the configuration of the battery used in this example, and FIG. 2 is a developed diagram thereof. 1.9... Terminal assembly, 2,8... Current collector, 3.
6... Glass wL fiber P paper, 4,7... Electrode material,
5-...Glass fiber door paper diaphragm, 10...Teflon board,
11... Container. Applicant for license: Maruzen Petrochemical Co., Ltd.

Claims (3)

[Claims] (1) A fused 6-, 6-, 6-membered unsaturated ring in which the central 6-membered ring contains two heteroatoms in the para position, and the heteroatoms are selected from the group consisting of O, S, N, and substituted N atoms. An electrochemical secondary battery characterized in that a heterocyclic compound is used for at least one electrode. (2) The secondary battery according to claim 1, wherein the positive electrode is the heterocyclic compound. (3) A fused 6-, 6-, 6-membered unsaturated ring in which the central 6-membered ring contains two heteroatoms in the para position, and the heteroatoms are selected from the group consisting of O, S, N, and substituted N atoms. An electrode for electrochemical secondary batteries that uses a heterocyclic compound as an electrode constituent material.