JPS62157678A - Secondary battery - Google Patents

Abstract

PURPOSE:To obtain the secondary battery with high energy density, small self- discharge, long cycle life and high efficiency of charge/discharge, by employing alphatype ferric trioxide as a negative electrode and polyaniline or the derivative thereof as a positive electrode. CONSTITUTION:As active material of a negative electrode 4, alpha type ferric trioxide, which can storage a lot of alkaline metal ions as guest ions and have an electrode reaction potential capable of stably performing reversible reaction in nonaqueous electrolyte, is employed. And polyaniline or the derivative thereof is employed as a positive electrode 6. The polyaniline or the derivative thereof is manufactured by either of an electrochemical and chemical polymerization methods. The alpha type ferric trioxide electrode is formed in such a way that carbon black as a conductive assistant and a specific surface increasing agent is mixed to the alpha type ferric trioxide, and polyethylene as a binder is mixed, the molding being performed.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention has high energy density, low self-discharge,
The present invention relates to a non-aqueous secondary battery that has a long cycle life and good charge/discharge efficiency (Coulombic efficiency).

[Conventional technology]

Currently, the commonly used secondary batteries are lead acid batteries, Ni/C
There are d% ponds, etc. These secondary batteries have a single cell battery voltage of about 2.0 V at most, and are generally water bath type batteries. In recent years, when the battery voltage is increased, Qi 1-L-04?
--Hisen L: ``Research into secondary batteries is being actively conducted.

When used in an Lltl-electrode, it is necessary to use a non-aqueous electrolyte because of the high reactivity between water and Li.

In this case, polyaniline, which is a type of conductive polymer, has recently attracted attention as having excellent performance as a positive electrode active material. Polyaniline has an extremely high capacitance density per unit weight, and also has extremely excellent reversibility of charging and discharging as a positive electrode. Furthermore, when the entire battery is constructed using L1 metal for the negative electrode, it is considered that a high energy density can be exhibited.

[Problem that the invention seeks to solve]

However, when Ll metal is used as the negative active # material, the electrode reaction potential is very low, and there is no electrolytic solution that can reversibly continue the battery reaction in combination with the positive electrode polyaniline. Furthermore, dendrites are formed on the L1 electrode side during photovoltaic charging, resulting in problems such as a decrease in charging and discharging efficiency and a short circuit between the positive and negative electrodes. As a method to prevent dendrites, the LL of the negative electrode is made of other metals,
For example, there is a method to prevent dendrites by increasing the electrodeposition potential of L4+ by alloying it with At or the like.
This is insufficient to prevent side reactions with the electrolyte. Next, a small amount of an inhibitor for preventing side reactions, such as hexamethylene phosphoramide or polyethylene oxide, is added to the electrolyte to form an ion-conductive protective film at the interface between the negative electrode and the electrolyte, thereby preventing side reactions from occurring between the electrolyte and the electrolyte. Although there have been attempts to prevent the reaction, it is difficult to completely cover the inhibitor with retained skin farming, and new problems such as the stability of the inhibitor itself have arisen, which poses practical problems.

The purpose of the present invention is to solve the problems of the prior art described above, and to provide a non-aqueous secondary battery with high energy density, low self-discharge, long cycle life, and good charge/discharge efficiency (Coulombic efficiency). is to provide.

[Means for solving problems]

As a result of intensive studies to solve the problems of the prior art, the present inventors found that the negative electrode active material is capable of collecting a large amount of electricity as alkali metal ions as dust ions, and is stable in known non-aqueous electrolytes. The battery is constructed using α-type ferric trioxide (α-F6□03), which has an electrode reaction potential that allows reversible reactions, and boria or its derivatives, which have excellent electrode performance as a positive electrode. It is found that the above purpose is achieved by configuring the following.

In the non-aqueous solvent secondary battery of the present invention, the negative electrode is not made of α-type ferric trioxide, and the positive electrode is made of polyaniline or a derivative thereof! ! It is assumed to be f-symptom.

The polyaniline or its derivative used in the present invention refers to a heptad polymer represented by the following general formula (1).

(In the formula, R1, R2, R, and R4 may be different or the same, and water, an atom, and an alkyl group having 1 to 10 carbon atoms are an alkoxy group having 1 to 1 carbon atoms.) ) Typical examples of the compound represented by the above general formula 〇) include aniline, ortho- or meta-toluidine, xylidine, ortho- or meta-anisidine.

Examples thereof include 2.5-/methoxyaniline, 2.5-jethoxyaniline, 3,5-dimethoxyaniline #2,6-simethoxyaniline, and the like. Among these, aniline is most preferred from the viewpoint of obtaining a secondary battery with good energy density.

For the electrolytic solution of the battery of the present invention, it is necessary to use an alkali metal salt as the electrolyte, and as the solvent, it is necessary to use a stable organic solvent that does not easily react with the positive electrode and the negative electrode.

Specific examples of alkali metal salts include LiC4O4tLi
BF, LiPF6*LiAsF6. LiBPh4. L
Lithium salts such as iBBu4tLiBPh3Bu and LtBEt3Bu, and sodium salts and potassium salts using Na or K instead of Li can be used.

In addition, as a suitable organic solvent, propylene carbonate is used.
) and carbonates such as ethylene carbinate, phosphoric acid esters such as trimethyl phosphate and triethyl phosphate, ethers such as tetrahydrofuran and 1,2-dimethoxyethane, sulfolanes such as sulfoladi and 3-methyl-sulfolane, γ-butyrolactone There are lactones such as and δ-butyrolactone, but propylene cargoonate or a mixed solvent of propylene cargoonate and ether is generally used.

The cathode-broken aniline or its derivatives may be produced by either an electrochemical polymerization method or a chemical polymerization method.For example, as an example of an electrochemical polymerization method, see Journal of the Chemical Society of Japan A11, p. 1801 (1984 An example of a chemical polymerization method is A. G. Green and A. E. Woodhead, Journal of the Chemical Society, p. 2388.

1910 (A, Gm Graen and A*E*W
oodhead.

J. Chem. Soc., 2388 (1910)).

In order to make the synthesized polyaniline powder, or its derivative, into a form that can be used as a positive electrode, it is generally necessary to mix polyaniline powder with carden black as a conductive agent, and further mix tetrafluoroethylene or the like as a binder to collect current. Apply or pressure mold on the body. In order to use electrochemically synthesized polyaniline or a derivative thereof as a positive electrode, a current collector is used as a substrate, and a compound represented by the general formula (I) is oxidized on the current collector and used as an electrode as it is. There is no problem. Further, in order to improve the electric capacity 1 density of polyaniline or its derivative, the synthesized polyaniline or its derivative can be used after being treated with alkali or reduced with hydrazine or the like.

The α-type ferric trioxide electrode used for the negative electrode is a commercial grade α-type ferric trioxide mixed with several layers of Kagen black, which has a high specific surface and bond, as a conductive additive and a high specific surface area agent. 1
・It can be made by mixing 0%, then adding a few 10% of polyethylene, polypropylene, etc. as a binder and molding.

In addition, it is possible to apply α-type ferric trioxide to the surface of the current collector, or to surface-treat the iron electrode chemically or electrochemically.
Alternatively, an α-type ferric trioxide electrode can also be produced by heat treatment.

However, the method for manufacturing the positive electrode and the negative electrode is not limited to the above method, and any manufacturing method may be used.

〔Effect of the invention〕

The battery of the present invention can be stably charged and discharged in organic solvents commonly used in batteries, and the battery of the present invention
Compared to batteries and lead-acid batteries, they have a higher energy density and an extremely low self-discharge rate, demonstrating high-performance battery characteristics.

〔Example〕

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

Example 1 [Manufacture of polyaniline] A platinum electrode (15 g + φ, diameter 0
．． Constant current density 1, 0 on the surface (with lead wire of 5wφ)
Electrolytic polymerization was performed at mA 7'cm2. in this case,
A platinum plate with the same diameter as above was used as the counter electrode, and AI! was used as the reference electrode. ,
'Heg, CT pole was used.

When the electrolytic polymerization electricity amount reached 20 coulombs, the polymerization was stopped, and a film-like polyaniline having a total weight of 9.6 cm and dark green fibrils entwined on both sides of the platinum plate was obtained. The average polymerization potential was 0.74 V vs. Ag/AgCL reference electrode.

Next, this polyaniline together with the platinum plate was immersed in ammonia water having a concentration of 28% by weight for about one hour.

While immersed in ammonia water, ultrasonic waves were applied for about 1 minute.Next, when the polyurethane 1.1 with the platinum plate was washed with distilled water for about 1 hour, the - of the washing water was 7.2. The above-treated polyaniline was peeled off from the platinum substrate and dried under reduced pressure at 100°C for 15 hours. Mix 10% by weight of black (trade name: Black Gour) with 10% by weight of Teflon No. .0M9' was pressure molded to produce an electrode with a diameter of 10 mφ.

[Preparation of negative electrode]

Commercially available ferric oxide was heat-treated at 650°C for 1 hour, and 10% by weight of furnace plastic and 10% by weight of polyethylene as a binder were added, mixed well, and then cut into 10-shoulder diameter pieces. 8. Place the above mixture on a punched nickel wire mesh.
0cm was pressure molded to create an electrode with a diameter of 100mm. This electrode was placed in the experimental cell shown in Figure 1, with a glass seven-arm plate placed between them in an argon atmosphere, and a
Using a Li metal cut out to 1 m 1 Iφ, the LiBF4t volume ratio was 1:1 so that the electrolyte had a concentration of 1 mol/Z.
A battery was constructed using 1 dissolved in a mixed solvent of propylene carbonate and 1,2-somethoxyethane.

In this system, the direction in which Li+ is reduced to the iron oxide side is 0.2
A current was applied at a current density of 5 mA/-, and the current was stopped when the amount of electricity reached 12 coulombs.

[Battery experiment]

Using an experimental cell having the structure shown in FIG. 1, the polyaniline positive electrode prepared by the above method and the ferric oxide negative electrode reacted with Li were placed with the side where the mesh was exposed facing the current collector, and a 1. Containing propylene carbonate and 1,2-dimethoxyethane electrolyte in which LiBF4 at a concentration of mol/l was dissolved. Holding a glass porous layer with a thickness of 0m,
Further, an electrolytic solution was added so as to completely enter the nitrogen pores of the electrodes and separator to construct a battery.

When this battery was charged at a constant current density of 3.0-ψ-2 until the amount of electricity reached 5.3 coulombs, the open-circuit voltage after charging was 2.6V. Then 3.0mA/6
Lol? At a constant current density of , the battery voltage is 1. A repeated test of charging and discharging was performed by discharging until the voltage dropped to OV, photoelectrically applying an amount of electricity of 5.3 coulombs again, and discharging to 1.0'/.

In addition, after completing 20 days of repeated charging and discharging, a self-discharge test was conducted for 30 days with the battery system open circuit. As a result, the charge/discharge efficiency of this battery was less than 90% for the first few cycles, but after that it maintained almost 100%, and the charge/discharge efficiency decreased again, and the cycle life was 565 cycles until it reached 50%. was recorded. The self-discharge rate of this battery over 30 days was 12%, and the energy density per side rail weight was 171 wh/log. The radiation generation curve after the 10th repetition was as shown in FIG. 2 (-).

Comparative Example 1 A negative electrode with a diameter of 10+ was used in place of the ferric oxide used in the example.
Lithium gold N8 cut out to wφ. An experimental cell having the structure shown in FIG. 1 was constructed using the same positive electrode and electrolyte as in the example except that Ov was used. When this battery was charged until it reached 5.3 coulombs in the charging direction, the open circuit voltage showed 3.6V. However, when a repeated discharge/charge test was performed, the 17th cycle The efficiency decreased to 50%, and good battery performance could not be obtained. The discharge curve after the 10th repetition was as shown in FIG. 2 (6).

Example 2 [Preparation of positive electrode polyaniline] Aniline concentration is 0.22 mol/! 1 N hydrochloric acid aqueous solution 1
While stirring 00cc with a magnetic stirrer, add (NH4)2S equivalent to 0.25 mol/l as an oxidizing agent.
20a e was added and aniline was chemically polymerized. The obtained polyaniline was in the form of powder.

This polyaniline was washed with distilled water, then washed with 28% ammonia water, further washed several times with distilled water, and then dried under reduced pressure at 100° C. for 15 hours.

Next, out of the polyaniline treated above, 7.0
Take out the ■, and add the crushing agent
- and 0.5 µm of 7 Arness Black as a conductive additive were mixed well in a total amount of 8.0 µm of powder. This mixture was pressure-molded onto a platinum wire mesh having a diameter of 10+ m in the same manner as in Example 1 to produce an electrode.

[Preparation of negative electrode]

Add 2m9 of carbon black and 1.5cm of polyaniline positive electrode to 10cm of ferric oxide treated in the same manner as in Example 1, mix well, and then mold to a diameter of 10mφ to prepare an electrode.
Using the cell shown in FIG. 1, ferric oxide and Li were reacted in advance in the same manner as in Example 1, and the cell was used as a negative electrode.

[Battery experiment]

A battery was prepared in the same manner as in Example 1 using the experimental cell shown in FIG. 1 and using a propylene cargo solution in which 1.5 mol/1IIk degree IC104 was dissolved as an electrolyte.

The amount of electricity required to charge this battery from the charging direction to 55 mol% per repeating unit of polyaniline (calculated assuming a molecular weight of 91) is 5. It was charged at a constant current density of OtydV'cm. The open circuit voltage of this battery after charging was 2.7V.

Then, the battery voltage was increased to 1.0 mA with a current density of 7 cm2.
It was discharged until it reached Ov. Next, 5. OrFIA/
Charge the battery at a current density of cvr2 until the battery voltage reaches 4.21VK, and when the voltage reaches 4.2V, switch to constant voltage charging of 4.2V, and the charging time is 1 from the start of constant current charging.
Charging continued until the time elapsed. Then 5.0 mA
At a current density of 7'cm2, the battery voltage is 1. A repeated charging/discharging test was performed in which the battery was discharged until it reached Ov, and then charged at a constant current of up to 4.2V and a constant voltage of 4.2V for 1 hour.The cycle life was recorded at 963 times until the row density was halved. .

Example 3 [Preparation of positive electrode] Post-treatment and binding of the polymer except that an aniline derivative obtained by electrochemically oxidatively polymerizing orthotoluidine was used instead of the boria IJ used for the positive electrode in Example 1. agent,
A positive electrode was prepared in exactly the same manner as in Example 1, including the mixing ratio of the conductive auxiliary material.

[Battery experiment]

The negative electrode, electrolyte, experimental cell, etc. used were exactly the same as in Example 1, and the performance of the battery was examined in the same manner as in Example 1.

As a result, the cycle life until the charge/discharge efficiency reached 50% was 485 times, the self-discharge rate of this battery in 30 days was 15%, and the energy density at both extremes was 14
It was 7w-hA.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an example of the configuration of a secondary battery of the present invention. Figure 2 is a graph showing the relationship between discharge time (minutes) and discharge voltage (V) (in the figure, the curve (,) shows the characteristics of the battery of the present invention, and the curve (b) shows the characteristics of the battery of the comparative example. ). Reference numbers in FIG. 1 are as follows. 1: Negative electrode lead wire, 2: Piton O-ring, 3: Negative electrode current collector, 4: Negative electrode, 5: Porous diaphragm, 6: Positive electrode, 7
: Current collector for positive electrode, 8: Lead wire for positive electrode, 9: Teflon container. -marks

Claims (1)

[Claims] A non-aqueous solvent secondary battery characterized in that the negative electrode is made of α-type ferric trioxide and the positive electrode is made of polyaniline or a derivative thereof.