JPH044561A - Battery - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to improvements in batteries, particularly polyaniline batteries, and relates to batteries that are rechargeable, have high gravimetric energy density and volumetric energy density, and have excellent cycle charge and discharge characteristics. It is.

(Prior Art) In recent years, with the spread of electronic devices, smaller and lighter batteries have come to be used for various purposes. In particular, batteries using lithium in their electrodes have a high energy density, so the demand for them has increased rapidly recently. Along with this, there is a strong demand for converting lithium batteries, which have conventionally been negative batteries, into secondary batteries.

Therefore, recently, it has been developed to obtain lightweight and rechargeable batteries by using organic polymer materials such as polyacetylene, polyaniline, polypyrrole, etc. as the active material of the positive electrode. Among these organic polymer materials,
It has been clarified that polyaniline exhibits excellent battery characteristics. In particular, it has been confirmed that when polyaniline is used for the positive electrode and lithium is used for the negative electrode, a secondary battery with high energy density characteristics can be obtained.

(Problems to be Solved by the Invention) However, the above-mentioned batteries were still insufficient in terms of cycle charge/discharge characteristics, which are considered to be an important performance among the performances required for batteries, that is, durability against repeated charging and discharging. 0 For example, in a battery using polyaniline as the positive electrode, when charging and discharging to a capacity of 120 to 140 Ah per unit weight (kg) is repeated, the discharge capacity significantly decreases to about 50% of the initial value after about 200 cycles.

Therefore, polyaniline batteries have not yet reached the stage of practical use in this respect, and there is an urgent need to improve their cycle charge and discharge characteristics.

(Objective of the Invention) An object of the present invention is to provide a polyaniline battery that exhibits little decrease in discharge capacity even after repeated charging and discharging many times and can withstand a long service life.

(Means for Solving the Problem) As a result of intensive research in response to such requests, the present inventors have found that the decrease in the discharge capacity of polyaniline batteries is caused by electrochemical oxidation of polyaniline due to repeated charging and discharging. It was found that polarons or bipolarons are generated in polyaniline, and this is caused by the reaction with solvent molecules or electrolyte molecules in the electrolytic solution, resulting in lower molecular weight. Moreover, it has also been found that the reaction can be suppressed by the presence of a compound (antioxidant) represented by the following general formula (1).

The battery of the present invention was developed based on the above knowledge, and is a battery using polyaniline as the main electrode active material of at least one of the two electrodes, and has the following general formula ( It is characterized by containing the polyphenol compound represented by 1).

The above general formula (
The polyphenol compounds shown in 1) include 2.
Examples include 5-di-tert-butylhydroquinone and 2,5-di-tert-amylhydroquinone.

The method of incorporating these antioxidants into the battery is not particularly limited; for example, they may be added to the electrolyte of the battery or mixed into the polyaniline electrode, but particularly preferred methods include When producing polyaniline by an electric field synthesis method, the above-mentioned antioxidant is mixed into the electrodeposition solution, or after mixing the same antioxidant with polyaniline powder,
This can be molded into an electrode, or a polyaniline electrode can be immersed in a solution of the antioxidant and then dried.

Note that polyaniline is obtained by polymerizing aniline by an appropriate electrochemical or chemical method, and aniline may be bonded to any position.

In addition, in the present invention, polyaniline is used for at least one of the two electrodes, but in order to obtain a battery with high energy density, it is preferable to use polyaniline as the positive electrode active material and lithium as the negative electrode active material. In this case, the electrolyte is preferably lithium perchlorate, lithium tetrafluoroborate, lithium trifluoromethanesulfonate, or a mixture thereof, and the solvent is dimethoxyethane, propylene carbonate, ethylene carbonate, tetrahydrofuran, sulfolane, gamma-butyrolactone, or any of these. A mixture is preferable 6 (effect) Since the battery of the present invention uses an antioxidant in its constituent materials, the polyaniline is difficult to oxidize even after repeated charging and discharging (and the discharge capacity is less likely to decrease. , when lithium is used as the negative electrode active material, the energy density is 45
Wh/kg or more can be obtained, and 500 at 100% depth of discharge.
Even after repeated charge and discharge cycles, the discharge capacity decreases by approximately 2 times.
It remained at 0%.

(Example 1) A. Production of polyaniline electrode Perchloric acid was dissolved in 100 cc of water to a concentration of 0.2 M.
Aniline was added to this to a concentration of 0.1M to prepare an electrodeposition solution, and then two nickel mesh plates with a size of IOXIOcm were placed facing each other in this solution, and one of them was used as an anode. A potential of 800 mV was set to the electrode, and anodic oxidation was performed for 10 hours to deposit 20.2 g of polyaniline on the mesh plate on the anode side. This polyaniline was taken out, washed in pure water for 24 hours, then dried at 80° C. for 24 hours, and then ground into a fine powder of 100 mesh or less.

2.5 g of polyaniline powder synthesized in this way
-D-tert-butylhydroquinone powder 0.2g
Add and mix the active material to a thickness of 0.05 mm and a width of 4 cm.
The electrode was crimped onto a stainless steel expanded metal having a length of 5.6 cm to obtain a polyaniline electrode in which the weight of polyaniline alone was 1.8 g.

B. Production of polyaniline battery The polyaniline electrode thus obtained was used as a positive electrode, and the thickness was 0.2
A lithium plate with a thickness of 0.3 mm is used as the negative electrode, and a 0.3 mm thick
A polypropylene non-woven fabric separator interposed therebetween was wound into a spiral shape and loaded into a single metal battery container. .1
3.2% dissolved in a mixed solvent at a concentration of 2.5M
cc injection, leads were taken out from the positive and negative electrode parts by a known method, and the lids were closed to obtain a battery of the present invention.

The weight of this battery was 13 g and the volume was 8.3 cc, which was about 1/2 lighter than a nickel cadmium battery.
When charged and discharged at a constant current of 10 mA in the voltage range of OV, a capacity of 189 mAh was obtained, and the average discharge voltage was about 3.5 V. Therefore, the gravimetric energy density of this battery was 51 Wh/kg, and the capacitive energy density was 79.7 Wh/I2. All of these values were larger than those of conventional nickel-cadmium batteries. Further, when the discharge capacity was measured after 500 cycles, it was 150 mAh, and the capacity reduction rate was about 20%.

(Example 2) A. Production of polyaniline electrode Dissolve perchloric acid in 100 cc of water at a concentration of 0.2 M.
Aniline and 2,5-di-tert-butylhydroquinone were added to this at concentrations of 0 and IM, respectively, to prepare an electrodeposition solution. A stainless steel expanded metal with a thickness of 0.05 mm, a width of 4 cm, and a length of 5.6 cm was placed in this electrodeposition solution as an anode.
Anodic oxidation was performed for about 10 hours by applying a potential of 0 mV, and an active material mainly consisting of polyaniline was deposited on the extended metal. This was installed as a cathode in a perchloric acid aqueous solution with a concentration of 0 and OIM, and the dedoped 2
After drying under vacuum for 8 hours at 80° C., the mixture was pressed to obtain a polyaniline electrode containing 1.83 g of polyaniline.

B. Production of polyaniline battery Using the polyaniline electrode thus obtained, the method of Example 1 was carried out.
A single Ill type battery of the present invention was obtained in the same manner as described above.

As a result of measuring the performance of this battery in the same manner as in Example 1, the gravimetric energy density of the battery was 53°2 W h /
kg, and the rate of decrease in discharge capacity after 500 cycles was 19%.

(Example 3) Perchloric acid was dissolved in 100 cc of water at a concentration of 0.2M,
Aniline was added to this at a concentration of O and IM to obtain an electrodeposition solution, and then a polyaniline active material was deposited on the expanded metal in the same manner as in Example 2 to obtain a polyaniline electrode, which was used in Example 2. Single III under the same conditions as 1.
Next, 2.5M and 0.01M of lithium tetrafluoroborate and 2.5-di-tert-butylhydroquinone as a deepening agent were loaded into the same container.
1 of propylene carbonate and dimexyethane at a concentration of
3 cC of an electrolytic solution dissolved in a :l mixed solvent was injected to obtain a single type battery of the present invention.

As a result of testing this battery under the same conditions as in Example 1, the gravimetric energy density was 52.2Wh/k.
g, and the rate of decrease in discharge capacity after 500 cycles is 21
．． It was 3%.

(Comparative example) All the same examples as in Example 3 except that 2.5-di-tert-butylhydroquinone was not added to the electrolyte in Example 3.
A battery of a comparative example was obtained in the same manner as described above.

As a result of testing this battery under the same conditions as in Example 1, the rate of decrease in discharge capacity after 500 cycles was 8.
It was 8%.

(Effects of the Invention) The battery of the present invention has excellent cycle charging and discharging characteristics, with a decrease in discharge capacity of about 20% even after 500 cycles of charging and discharging at 100% depth of discharge, and has a long life. , is extremely useful industrially.

Furthermore, the battery of the present invention surpasses conventional lead batteries and nickel-cadmium batteries in terms of various performances including weight energy density and volumetric energy density, and its industrial value is extremely large. .

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Claims (1)

[Claims] A battery in which polyaniline is used as the main electrode active material of at least one of two electrodes, in which a polyphenol compound represented by the following general formula (1) is included in the constituent materials. A battery characterized by comprising: ▲There are mathematical formulas, chemical formulas, tables, etc.▼(1) (In the formula, R_1 and R_2 are alkyl groups)