JPH0428159A - Secondary battery - Google Patents

Abstract

PURPOSE:To improve charge and discharge characteristics by utilizing a conductive polymer, which is polymerized on conductive material powders so that it is integrated with the powders, as an electrode material. CONSTITUTION:A conductive polymer, which is polymerized on conductive material powders so that it is integrated with the powders is used as an electrode material. Here metallic powders, carbon powders and the like are used as the conductive material powders. Metals or alloys selected from Ni, Ni-Cr, Ni-Cu, Ni-Fe-Cr, stainless steel, Fe-Cr, Cu, Fe, Cu-Ni, Pb, Cd, Au, Ag and the like are used as the metallic powders. As the carbon powders, acetylene black, ketjen black, graphite, an expanded graphite and the like are used.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a secondary battery using a conductive polymer such as polyaniline as an electrode material.

(B) Prior art In recent years, secondary batteries have been proposed that use conductive polymers made of various organic materials as electrode materials.

The conductive polymer that serves as the electrode material for this type of secondary battery is
Normally, the conductivity is slight, but it is possible to perform doping or undoping treatment with dopants such as various anions and cations, and the doping treatment dramatically increases the conductivity. Then, a conductive polymer doped with anions is used as a positive electrode material, a conductive polymer doped with cations is used as a negative electrode material, and a solution containing the above dopant is used as an electrolytic solution to remove the doped and undoped pins. A battery that can be charged and discharged is constructed by chemically reversibly performing the process.

As such conductive polymers, polymers having a military double bond in the main chain, such as polyacetylene, polyparaphenylene, polythenylene, polypyrrole, polyaniline, and polyparaphenylenevinylene, are conventionally known. For example, polyacetylene is used as the electrode material for at least one of the positive electrode and the negative electrode, and anions such as BF, -1CIO, -1SbF, -1PF, -, or Li'', Na4, R, -N'' (
A structure is adopted in which cations such as R represents an alkyl group are electrochemically reversibly doped or undoped.

(c) Problems to be Solved by the Invention Since such conductive polymers generally have low conductivity, sufficient characteristics cannot be obtained when used alone as an electrode material. Therefore, electrodes are constructed by mixing a conductive agent powder such as carbon with a conductive polymer.

However, when mixing and using conductive agent powder, it is difficult to mix it uniformly, and the mixing ratio of the conductive agent and the contact state between the conductive agent powder and the conductive polymer vary depending on the part of the electrode, so the conductivity of the electrode is Difficult to improve uniformly. Therefore, in an electrode using a conductive polymer,
It is difficult to improve electrode characteristics simply by mixing conductive agent powder.

The present invention has been made in view of such problems, and includes:
The aim is to improve the conductivity of electrodes using conductive polymers and improve the charge/discharge characteristics of this type of secondary battery.

(d) Means for Solving the Problems The secondary battery of the present invention is characterized in that a conductive polymer polymerized on a conductive agent powder and integrated with the conductive agent powder is used as an electrode material. It is.

Here, as the conductive agent powder, metal powder, carbon powder, etc. can be used.

This metal powder includes N1, Ni-Cr, Ni-Cu
, Ni-Fe-Cr, stainless steel, Fe-Cr, Cu,
Those made of metals or alloys such as Fe, Cu-Ni, Pb, Cd, Au, and Ag, and those made of acetylene black, Ketchen black, graphite, expanded graphite, etc. are used as carbon powder.

Further, as the conductive polymer, polymers having a conjugated double bond in the main chain, such as polyacetylene, polyparaphenylene, polythiophene, polypyrrole, polyparaphenylene vinylene, polyaniline, polyimidazole, polythiazole, Boffran, etc. can be used. However, in particular, 5 or 6 having a nitrogen atom, oxygen atom or sulfur atom as a heteroatom and having a conjugated π-electron system.
Preferred are polymers consisting of a group of membered heterocyclic compounds or aniline polymers such as polypyrrole, botaniline, polythiophene, and the like.

When the electrode using the conductive polymer is used as a positive electrode, it is preferable to use a metal with an electronegativity of 1.6 or less as the negative electrode. Examples of such metals include Ll, N
Examples of a) include Mg, AN, and alloys thereof, with Li and L1 alloys being preferred.

On the other hand, the electrolyte used in the secondary battery of the present invention is as follows:
For example, a solution in which an electrolyte is dissolved in an organic solvent is used. As such an electrolyte, salts with cations and anions such as metal cations and organic cations having an electronegativity of 1.6 or less can be avoided. Examples of cations are:
Examples include quaternary ammonium ions, carbonium ions, oxonium ions, and the like. In addition, anions include BF, -2cpo, -1PF, -1AsF, -1CF
, S, -1■-1Br-1C1-1F-, and the like. Specific examples of such electrolytes include lithium tetrafluoroborate (LiBF), lithium perchlorate (Li CI!, O,), lithium hexafluorophosphate (L+PFe), and lithium tetrachloroaluminate. (LiAjICj!,), tetraethylammonium tetrafluoroborate (Et, NBFt),
Tetra n-butylammonium perchlorate (nBu, NC
CO2), lithium trifluoromethanesulfonate (L
ICF s S Os ), lithium iodide (LiI
), lithium bromide (LiBr), etc., but are not limited to these. For example, if a battery is constructed using the electrode material of the present invention in both the positive and negative electrodes and an electrolyte in which LiBF is dissolved as the electrolyte, during charging, the electrode material in the positive electrode is exposed to the electrolyte. BF
, -, and the electrode material in the negative electrode is doped with Li'' in the electrolyte. On the other hand, during discharge, BF I\L doped in the positive and negative electrodes are released into the electrolyte, respectively. .

In addition, as the organic solvent for dissolving the electrolyte, it is preferable to use an aprotic one with a high dielectric constant, such as nitrile, carbonate, ether, nitro compound, amide, sulfur-containing compound,
Chlorinated hydrocarbons, ketones, esters, etc. can be used. Moreover, two or more kinds of such solvents can also be used in combination. Representative examples of these include acetonitrile, propionitrile, fithyronitrile, benzonitrile, propylene carbonate, ethylene carbonate, tetrahydrofuran, dioxolane, 1,4-dioxane, nitromethane, N,N-dimethylformamide,
Examples include, but are not limited to, dimethyl sulfoxide, sulfolane, 1,2-dichloroethane, γ-butyrolactone, 1,2-dimethoxyethane, methyl phosphate, and ethyl phosphate.

The concentration of the electrolytic solution of the present invention is usually 0. OO1~1
0 mol/! It is preferably used in an amount of 0.1 to 3 mol/l.

In addition to being injected with the electrolytic solution described in 2, it can also be used by pre-impregnating an electrode using the electrode material of the present invention.

(e) Function Since the conductive polymer is polymerized on the conductive agent powder,
A conductive polymer is formed on or within the conductive agent. Since the conductive polymer integrated with the conductive agent powder is integrated in powder particle units, the contact condition is good, and when an electrode is constructed, the blending ratio of the conductive agent is uniform in each part of the electrode. Become. As a result, the conductivity of the electrode increases and the electrode properties are significantly improved.

(f) Example Embodiments of the present invention will be described below based on the drawings.

(Example 1) Aniline and acetylene black, which is a conductive agent powder, were mixed and heated to room temperature (20° to 40° C.) while stirring under a nitrogen atmosphere.
℃), and a Cu(BF4)/acetonitrile solution was added dropwise. Upon dropping, the reaction liquid immediately turned black and took on the form of a slurry. After the reaction was completed, the mixture was allowed to stand at room temperature. Thereafter, the reaction product was filtered to obtain acetylene black (conductive agent powder) on which a polyaniline layer (conductive polymer) was formed.

Positive electrode 1 (first
(see figure) was prepared. Incidentally, FIG. 1 is a longitudinal sectional view of the battery of the present invention. Further, a lithium-aluminum alloy is used for the negative electrode 2, and the separator 3 is impregnated with a lithium borofluoride-propylene carbonate solution. 4 is a positive electrode can that stores the positive electrode 1, and 5 is a negative electrode needle that stores the negative electrode 2. On the inner bottom surfaces of the positive electrode can 4 and the negative electrode needle 5,
A positive electrode current collector 6 and a negative electrode current collector 7 are respectively arranged. The positive electrode can 4 and the negative electrode needle 5 are insulated via an insulating backing 8 to form a sealed battery. In this way, the battery A of the present invention was produced.

(Comparative Example 1) A battery was produced in the same manner as in Example 1, except that an acetylene blank was mixed with polyaniline obtained by polymerization without adding acetylene black to produce a positive electrode.
It was designated as comparative battery X.

Using these batteries A and X, a charge/discharge performance comparative test was conducted. The experimental conditions at this time were that each battery was charged at a current of 1 mA to an end-of-charge voltage of 3.6V, and at a discharge current of 1 mA to an end-of-discharge voltage of 2.6V. Discharging is performed until OV.

The results are shown in FIG.

From FIG. 2, it can be seen that although all the batteries showed a charging efficiency of 100Z, the battery A of the present invention can be charged up to 6 mA h, whereas the comparative battery X can only be charged up to S mA h. The reason for this is that in Comparative Battery This is thought to be due to the fact that the conductive agent powder is integrated with the powder, and the contact state and blending ratio do not change depending on the electrode location, making it stable and uniform.

(Example 2) Aniline and graphite, which is a conductive agent powder, were mixed, and while stirring in a nitrogen atmosphere, Cu(BF, ),
Acetonitrile solution was added dropwise. Upon dropping, the reaction liquid immediately turned black and took on the form of a slurry. After the reaction was completed, the reaction solution was left at room temperature overnight. Thereafter, the reaction product was filtered to obtain graphite with a polyaniline layer formed on its surface. A positive electrode was produced using the polyaniline-graphite (electrode material) obtained as described above. Further, a battery B of the present invention was prepared in the same manner as in Example 1, using a lithium-aluminum alloy for the negative electrode and a lithium borofluoride-propylene carbonate solution for the electrolyte.

(Comparative Example 2) Except that a positive electrode was prepared by mixing graphite with bot aniline obtained by polymerization without adding graphite,
A battery was produced in the same manner as in Example 2 and designated as Comparative Battery Y.

Using these batteries B and Y, a comparative test of charging and discharging characteristics was conducted. The experimental conditions at this time were the same as in Example 1 above.

The results are shown in FIG.

From this result, both batteries show a charge/discharge efficiency of 00%, but inventive battery B can be charged up to 5.5 mA h, whereas comparison battery Y can only be charged up to 4.5 mA h. I understand that. This is the above-mentioned invention battery A
It is thought that this is based on the same factors as those considered when comparing Comparative Battery X and Comparative Battery X.

(Example 3) Mixing aniline and stainless steel powder, which is a conductive agent powder,
Cu (BFI) at room temperature with stirring under nitrogen atmosphere.
! - Acetonitrile solution was added dropwise.

Upon dropping, the reaction liquid immediately turned black and took on the form of a slurry. After the reaction was completed, the reaction solution was left at room temperature overnight. Thereafter, the reaction product was filtered to obtain stainless steel powder (electrode material) with a polyaniline layer formed on the surface.

A positive electrode was produced using the polyaniline-stainless steel powder obtained as described above. Further, a battery C of the present invention was prepared in the same manner as in Example 1, using a lithium-aluminum alloy for the negative electrode and a lithium borofluoride-propylene carbonate solution for the electrolyte.

(Comparative Example 3) A battery was prepared in the same manner as in Example 3, except that a positive electrode was prepared by mixing stainless filter powder with polyaniline obtained by polymerization without adding stainless steel powder, and a comparative battery was prepared. It was set as 2.

A comparison test of charging and discharging characteristics was conducted using these batteries C and Z. The experimental conditions at this time were the same as in Example 1 above.

The results are shown in FIG.

These results show that both batteries show 100% charge/discharge efficiency, but inventive battery C can be charged up to 5.7 mAh, while comparison battery Z can only be charged up to 4.7 mAh. . This is considered to be based on the same factors as those considered when comparing the battery A of the present invention and the comparative battery X and the battery B of the present invention and the comparative battery Y.

(G) Effects of the Invention According to the present invention, since the conductive polymer integrated with the conductive agent powder is used as the electrode material, the contact state between the conductive polymer and the conductive agent powder is good, and the conductivity of the electrode is improved. It is possible to provide a secondary battery with improved charging and discharging characteristics, and its industrial value is extremely large.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of the battery of the present invention, and FIGS. 2, 3, and 4 are comparison diagrams of the charging and discharging characteristics of the batteries. 1...Positive electrode, 2...Negative electrode, 3...Separator, 4
... Positive electrode can, 5... Negative electrode needle, 6... Positive electrode current collector,
7...Negative electrode current collector, 8...Insulating backing, A, B, C...Battery of the present invention, x, y, z...Comparative battery.

Claims (3)

[Claims] (1) A secondary battery characterized in that a conductive polymer polymerized on a conductive agent powder and integrated with the conductive agent powder is used as an electrode material. (2) The secondary battery according to claim 1, wherein the conductive agent powder is made of metal powder. (3) The secondary battery according to claim 1, wherein the conductive agent powder is made of carbon powder.