JPS5971266A - Battery - Google Patents

Abstract

PURPOSE:To improve performance and service life of a battery by providing a porous adsorbent in a solvent of supporting electrolyte in a chargeable battery using polyacethylene for poles. CONSTITUTION:In a chargeable battery using poles 4 made of polyacethylene, a porous adsorbent 6 is provided between separators 5 and it is sufficiently impregnated with a supporting electrolyte. A water content in an organic solvent is adsorbed and removed by such adsorbent 6 and impurity produced by electric decomposition of such organic solvent is also adsorbed and removed by it. As a result, a charging/discharging efficiency of battery is improved and service life of battery can be extended.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a rechargeable battery using an acetylene polymer (hereinafter abbreviated as polyacetylene) as an electrode and a supporting electrolyte solvent containing a specific substance.

[Prior art]

polyacetylene, ato4-1PF, - and BF4-
anions such as Ll" and (04Hll)4'
It is known that electrochemical doping of cations such as M+ produces polyacetylenes with n-type and p-type conductivity, respectively [see, for example, Chemical and Engineering News (Ckllll), p. 26.39 (1981)]. . Various types of rechargeable batteries applying such electrochemical doping have been reported.For example, a battery using polyacetylene as the positive electrode, lithium metal as the negative electrode, and Li0tO4 dissolved in propylene carbonate as the electrolyte, One with an open circuit voltage of 7 V and a short circuit current of 25 mm has been obtained. In addition, polyacetylene is used for the positive and negative electrodes, and propylene carbonate is used for the electrolyte (
A battery using a solution of C411I9)4Mcto4 has an open circuit voltage of 2.5 V and a short circuit current of 1 t1 mm [Journal of the Chemical Society? i, chemistry) j le communication (j, c, s.

Ohsm, Oomm, ), (1981) 317~
See page 319]. However, in both batteries, the battery voltage is high, and Llo, which serves as an electrolyte and dopant,
tOa or (04 horse) 4NCtOi etc. are dissolved in an organic solvent. In these batteries, since the battery voltage is high, it is necessary to completely remove water in the organic solvent. This moisture adversely affects the current efficiency during charging and discharging of the battery or the self-discharge of the battery. On the other hand, impurities in the organic solvent affect the life of the stain pond due to adsorption to the electrodes, etc.

For this reason, the organic solvent that dissolves the electrolyte is
It is used that has been purified by distillation using conventional methods to remove impurities and water.

However, even a battery using the supporting electrolyte obtained in this way has a high current efficiency and a long life, but when used repeatedly for charging and discharging, the battery performance deteriorates and the cycle life is short. This is because even if the organic solvent is purified and dehydrated, a small amount of water remains in the supporting electrolyte after battery formation, and the organic solvent is electrolyzed by repeated charging and discharging, and this impurity has an effect. There was found.

[Purpose of the invention]

The purpose of the present invention is to overcome the drawbacks of the prior art and provide a rechargeable battery with high performance and long life.

[Summary of the invention]

To summarize the present invention, the rechargeable battery of the present invention includes:
In a rechargeable battery using polyacetylene as an electrode,
It is characterized by the presence of a porous adsorbent in the supporting electrolyte solvent.

As a result of repeated studies on impurities and moisture in the supporting electrolyte solvent of batteries, the present inventors have found that impurities in organic solvents obtained immediately after purification using conventional methods can be detected using gas chromatography (detection method from F). was not detected, and moisture was 5.
, it was confirmed that the amount was around ppm. However, when batteries were left for a long time without being charged or discharged after formation, the moisture content in the supporting electrolyte was measured and found to have increased to 40 to 50 ppm). Gas chromatography analysis of the supporting electrolyte after the cycle revealed that the # of the organic solvent used was
A chromatogram with four peaks was obtained.

Based on the above findings, the present inventors have discovered that the above-mentioned problems can be solved by providing a porous adsorbent in the supporting electrolyte solvent as an element constituting the battery, and have invented the present invention. has been reached.

That is, in the present invention, as shown in FIG. 1 below, a porous adsorbent is placed in the supporting electrolyte layer constituting the battery, specifically between the separators in the battery, and is sufficiently impregnated with the supporting electrolyte. This absorbs water in organic solvents,
In addition, by adsorbing and removing impurities generated by electrolysis of organic solvents, the charging and discharging efficiency of the battery can be improved and the life of the battery can be extended.

The porous adsorbent used in the present invention is not particularly limited as long as it is not an insulator or a nonconductor, and may be any material that can adsorb and remove moisture and impurities, such as commercially available alumina, molecular sheep, silica, etc. Fine powder or porous molded products can be used as appropriate, and the particle size is usually 2.
A fine powder of about 0.00 to 400 mesh is suitable.

Furthermore, the porous adsorbent may be present in the battery between separators as shown in Examples below, but the porous adsorbent itself may also be used as a separator and supporting electrolyte holding material.

[Embodiments of the invention]

Next, the present invention will be explained in detail with reference to Examples, but the present invention is not limited to these in any way.

Example 1 Positive electrode and negative electrode, specific gravity Q: 91, thickness 230F 111%
Using polyacetylene with a diameter of 2em, as the dopan F and supporting electrolyte, (04ks) Amazon at 120℃,
It was thoroughly dehydrated under the conditions of 10-"m1H1<, and then mixed with propylene carbonate and dimethoxyethane (volume ratio 1:1).
) mixed solvent (dehydrated and distilled with molecular sieves)
Then, a battery was assembled using polypropylene dissolved in a concentration of α5 mol/l and dried and dehydrated polypropylene as the supporting electrolyte holding material and separator. Figure 1 is a schematic cross-sectional view showing the structure of this battery), 1 is a battery case, 2 is a battery holder (polytetrafluoroethylene), 3 is an electrode current collector, 4 is an electrode (polyacetylene), 5 indicates a separator, and 6 indicates a porous adsorbent. As shown in FIG. 1, alumina (M,W)y' (M, W
oe1mJ! +8chwege) was placed so that the distance between the electrodes was 2.5 to 5 m, and the supporting electrolyte was sufficiently impregnated to form a battery.

This battery was charged at a current density of 1 mA/cW1" for 1 hour, and then charged at a current density of 1 mA/cyi" until the battery voltage reached 1V.
discharged at a current density of FIG. 2 shows the results of examining the battery characteristics when this cycle was repeated up to 65 times. In other words, Figure 2 is a graph showing the relationship between the number of charge/discharge cycles (horizontal axis) and current efficiency (ratio of charge amount to discharge charge amount: Ch) (vertical axis). indicates the case of Example 1, B indicates the case of Example 2 described later, and C indicates the case of Comparative Example described later.

From the curve A in FIG. 2, in the case of Example 1, the current efficiency in the 3rd to 15th cycles was 90 to 93 inches, and the current efficiency in the 65th cycle was 89 inches, with no significant decrease. Further, when the water content in the organic solvent after the 65th discharge was measured by the Karl Fischer method, a result of 4 ppm was obtained. On the other hand, when this organic solvent was analyzed by gas chromatography (detected from F), no peaks other than those of propylene carbonate and dimethoxyethane were observed.

Furthermore, the results of examining the 65th charge/discharge characteristics of the battery in the above test are shown in FIG. In other words, Figure 3 is 65
This is a graph showing the relationship between the charging rate and discharging rate (H) (horizontal axis) and the battery voltage ('V) (vertical axis) in the second cycle. Example 2 below
In the case of , 7 shows the case of the comparative example described later.

As is clear from the curve in FIG. 3, the voltage after charging is 12V, which is low.

Example 2 A battery having the same structure as in Example 1 was assembled, and a molecular sieve 4A with a particle size of 200 to 400 mesh was used as the porous adsorbent 6 [Fuji-Devison Chemical Limited (Fuj
A charge/discharge cycle test similar to that in Example 1 was conducted on a battery using a battery manufactured by i-Davison Ob@1m, I+ta, ), and the following results were obtained.

The relationship between the number of cycles and current efficiency is shown in curve B in Figure 2 above, where the current efficiency in the 3rd to 15th cycles is 90 to 92 cm, and the current efficiency in the 65th cycle is 85 cm. Ta. Further, the amount of water in the organic solvent after the 65th discharge was 3 ppm. On the other hand, this organic solvent was analyzed by gas chromatography (detected from F), and a chromatogram with one peak in addition to the peaks of propylene carbonate and dimethoxyethane was obtained. Further, regarding the charging/discharging characteristics of the battery at the 65th time in the test, the voltage after charging was 3.4 V, as shown by curve E in FIG. 3 above.

Comparative Example A battery having the same battery configuration as Example 1 but without the porous adsorbent shown in FIG. 1 was subjected to the same charge/discharge cycle test as Example 1, and the following results were obtained.

The relationship between the number of cycles and current efficiency is shown in curve C in Figure 2 above, where the current efficiency in the 3rd to 15th cycles is 68 to 70%, and the current efficiency in the 65th cycle is 35%. decreased. Also, as shown in 7 of FIG. 3, the charging end voltage at the 16565th cycle is 4.
．． It was extremely high at 2■. On the other hand, when the moisture content in the organic solvent was measured after the 65th cycle, the concentration was 48 ppm. Furthermore, as a result of analyzing this organic solvent by gas chromatography, a chromatogram was obtained that had four peaks in addition to the propylene carbonate and dimethoxyethane peaks.

〔Effect of the invention〕

As is clear from the results of the above Examples and Comparative Examples, the presence of a porous adsorbent in the supporting electrolyte solvent of a battery can improve the charging and discharging efficiency of the battery and extend the life of the battery. can.

Therefore, the battery of the present invention is useful as a new type of secondary battery.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional schematic diagram showing the configuration of a battery in an example of the present invention, FIG. 2 is a graph showing the relationship between the number of charge/discharge cycles and current efficiency in an example of the present invention and a comparative example, and FIG. FIG. 5 is a graph showing the relationship between charging rate, discharging rate, and battery voltage in Examples and Comparative Examples of the present invention. 1...Battery case, 2...Battery holder, 3.
...electrode current collector, 4...electrode, 5...separator, 6...porous adsorbent Patent applicant Hitachi Ltd. Showa Denko K.K. agent Hiroshi Nakamoto Figure 1 Figure 2 310 Third area

Claims (1)

[Claims] t A rechargeable battery having an acetylene polymer as an electrode, characterized in that a porous adsorbent is present in a supporting electrolyte solvent.