JPS59228373A - Secondary battery - Google Patents

Abstract

PURPOSE:To obtain a battery having high energy density, good cycle life, light weight, and compact size. CONSTITUTION:In a secondary battery in which high molecular compound having conjugated double bond in principal chain is used in positive and negative electrodes, a positive electrode 3 is doped with anion of halogen compound of element selected from IIIa, IVa, and Va groups of the periodic table, perchlorate ion, or HF2<-> ion, and a negative electrode 5 is doped with cation of metal of I a group of the periodic table, or cation of quaternary ammonium salt, and salts of anion and cation which are the same as anion and cation doped in the positive and negative electrodes respectively are used as the supporting electrolyte of electrolyte. This secondary battery is lightweight, compact, and has high energy density. Therefore, it is suitable for portable appliance, electric car, gasoline car, and power storage applications.

Description

[Detailed description of the invention] The present invention relates to a secondary battery with good performance.

Acetylene polymers obtained by polymerizing acetylene using so-called Ziegler-Natsuta catalysts, which are composed of transition metal compounds and organometallic compounds, have electrical conductivity in the semiconductor region, making them useful as electrical and electronic devices. It is already known that it is an organic semiconductor material.

Methods for producing practical molded products of acetylene high polymers include (a) a method of pressure molding powdered acetylene high polymers;
and (b) a method of obtaining a film-like acetylene polymer having a fibrous microcrystalline (fibril) structure and high mechanical strength by forming it into a film at the same time as polymerization under special polymerization conditions ( Special Publication No. 48-32581) was known.

The powdered acetylene polymer molded product obtained by the method (a) above is mixed with BF3, BCl3, HCl5C12, SO2,
Electron-accepting compounds such as NO2, HCN, 02, NO, etc.
It is already known that chemical treatment with an acceptor (acceptor) increases the electrical conductivity by up to three orders of magnitude, and conversely, treatment with an electron-donating compound (donor) such as ammonia or methylamine decreases the electrical conductivity by up to four orders of magnitude. It is being

In addition, the film-like acetylene polymer obtained by the method (b) contains ]2, C12, Br2.1cls lBrXAsF
5. By chemically doping an electron-accepting compound such as SbF5, PF6, etc. or Na with an electron-donating compound such as Li, the electrical conductivity of the acetylene polymer can be varied over a wide range of 1.0 to 10Ω・α. It is also already known that it can be freely controlled over a range.

The idea of using this doped film-like acetylene polymer as a material for the positive electrode of a primary battery has already been proposed.

On the other hand, in addition to the above chemical doping method, electrochemical doping methods such as cao-1PF;, AsF55 AsFQ,
Anions such as CF;, SO;, BF; etc. and stations (R
A method has also been developed for doping acetylene polymers with cations such as / , alkyl groups) to produce P-type and n-type conductive acetylene polymers.

A rechargeable battery using electrochemical doping using a film-like acetylene polymer obtained by the method (b) has been reported.

This battery is obtained by the method (b), for example, 0.1 m
Two acetylene polymer films with a thickness of m are used as positive and negative electrodes, respectively, and when these are immersed in a tetrahydrofuran solution containing lithium iodide and connected to a 9V DC power supply, lithium iodide is electrolyzed. The acetylene polymer film of the positive electrode is doped with iodine, and the acetylene polymer film of the negative electrode is doped with lithium. This electrolytic doping corresponds to the charging process. When a load is connected to the two doped electrodes, lithium ions and iodine ions react to generate electricity. In this case, the open circuit voltage (Voc) is 28v1 and the short circuit current density is 5 mAl
crl, and when a tetrahydrofuran solution of lithium perchlorate is used as the electrolyte, the open circuit voltage is 2.5V.
, the short circuit current density was about 3 mA/cm.

This battery uses an acetylene polymer as its electrode material, which is easy to reduce weight and size, so it is attracting attention as an inexpensive battery that has high energy density and is easy to reduce weight and size. There is. Also, JP-A-56
-136469, in addition to acetylene high polymers,
Poly(p-7 enylene), poly(m-phenylene), poly(phenylene sulfide), poly(phenylacetylene), polypyrrole, and the like have also been disclosed to be useful as electrode materials. However, the batteries that use the above-mentioned polymer compounds having conjugated double bonds in the main chain as the active material of the electrodes that have been known up to now have low electrical conductivity. Since the battery was used as an electrode as it is, overvoltage is applied at the beginning of the charge/discharge cycle, and side reactions of the solvent, reactions between the solvent and the electrode, and deterioration reactions of the electrode occur, so the cycle life of the battery is not necessarily satisfactory. It wasn't something.

In view of the above points, the present inventors have conducted various studies to obtain a battery that has high energy density, good cycle life, is easy to reduce weight and size, and is inexpensive, and as a result, they have developed the present invention. It is completed.

That is, the present invention provides a secondary battery in which a polymer compound having a conjugated double bond in the main chain is used as a positive electrode and a negative electrode.
The negative electrode is doped with a basic halide anion selected from Group A, perchlorate ion, or HF'2 anion, and the negative electrode is predoped with a cation of a metal from Group IA of the periodic table or
Doped with class ammonium ion cations,
The present invention also relates to a secondary battery characterized in that a salt of an anion and a cation which is the same as the anion and cation with which the positive electrode and the negative electrode are doped in advance is used as the supporting electrolyte of the electrolytic solution.

The secondary battery of the present invention has several advantages compared to conventional secondary batteries that use a polymer compound having a conjugated double bond in its main chain (hereinafter referred to as a conjugated polymer compound) with low conductivity as an electrode. Although it is not necessarily clear whether the conjugated polymer compound has a long cycle life, it is possible to use as an electrode a conjugated polymer compound doped with the above-mentioned anions or cations to increase the conductivity of the conjugated polymer compound, and Because a salt of the same anions and cations as the anions and cations pre-doped into the positive and negative electrodes was used as the supporting electrolyte, conventional side reactions of the solvent, reactions between the solvent and the electrodes, and deterioration reactions of the electrodes were suppressed. It is assumed that the cycle life will be improved.

The conjugated polymer compound used in the present invention may be a homopolymer or a copolymer, and specific examples include acetylene polymer (polyacetylene), polyphenylacetylene, polyparaphenylene, and polymethane. Ren, poly(25-chenylene), poly(3-methyl-
2,5-chenylene), polypyrrole, polyimide, polyacrylonitrile, and poly-α-cyanoacrylic thermal decomposition products, etc., but are not necessarily limited to these, and as long as it is a conjugated polymer compound. good. Among the above conjugated polymer compounds, acetylene polymers, polyparaphenylene, poly(25-chenylene), and polypyrrole are preferable, and acetylene polymers are particularly preferable, and polymers are particularly preferable. Examples include crystalline acetylene polymers.

The method for producing the acetylene polymer preferably used in the present invention is not particularly limited, and any method can be used. -129404,
No. 55-128419, No. 55-142012, No. 56-10428, No. 56-133133, Tra
ns.

Farady Soc, , 64.823 (1,96
8), J, Polymer Sci, A-1, J
3419 (1969), Makromol, Che
m.

Rapid Comm, , 1.621 (] 98
0), J. Chem.

Phys, 69 (IL) 06 (1978),
Synthetic Metals.

Examples include methods such as Yu, 81 (1681).

The conjugated polymer compound used in the present invention can be in the form of a film, powder,
Any form such as a short fiber form can be used, but it is preferable that forms other than a film form are molded by a method known to those skilled in the art to form a molded product having the necessary mechanical strength. In addition, other suitable conductive materials can be added to the conjugated polymer compound,
For example, it is also possible to mix graphite, carbon black, acetylene blank, metal powder, carbon fiber, etc.
There is no problem in using a metal net or the like as a current collector.

In the present invention, the anions pre-doped into the conjugated polymer compound as the positive electrode are group 1IIa of the periodic table,
Halide anions of elements selected from Group 1 Va and Va, perchlorate ions (CA-) and HF;
It is. Specific examples of /10genide anions of elements selected from Group 1IIa, Group 1Va, and Group Va of the periodic table include BF;, Alcl'', and.

Examples include SiF;, PF, -, AsF-' SbF, -, and the like.

I The cations pre-doped into the conjugated polymer compound as the negative electrode include cations of metals in Group 1a of the periodic table and cations of metals in Group 1a of the periodic table.
It is a class ammonium ion. Specific examples of metal cations in Group 1a of the periodic table include Li+, Na+, K
+, Cs+, etc., and a specific example of the quaternary ammonium ion is Bu4N+.

Et　N++　　Me4N+　etc.

As a method for doping the conjugated polymer compound with an anion or a cation, any conventionally known chemical doping method or electrochemical doping method may be employed.

The electrical conductivity of the military service polymer compound after doping is 10-2
Ω-1'Cr1L-1 or more, preferably 10-1Ω-1
・cIrL−1 or more, particularly preferably lΩ−1・cI
It is preferable that it is rL-1 or more. Further, the electric conductivities of the pre-doped positive and negative electrodes may be the same or different.

Examples of the solvent for the electrolytic solution used in the secondary battery of the present invention include ethers, ketones, aromatic or aliphatic hydroxides, amines, amides, sulfur compounds, chlorinated hydrocarbons, and esters. , carbonates, nitro compounds,
Phosphoric ester compounds, sulfolane compounds, etc. can be used, and among these, ethers, ketones, aromatic or aliphatic nitriles, chlorinated hydrocarbons, carbonates, and sulfolane compounds are preferred.

Representative examples of cholera include tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxane, anisole, monoglyme, acetonitrile, propionitrile, 4-methyl-2-pentanone, butyronitrile, penzenitrile, 1,2-dichloroethane, γ- Examples include butyrolactone, dimethoxyethane, methylformate, propylene carbonate, ethylene carbonate, dimethylformamide, dimethyl sulfoxide, dimethylthioborumamide, sulfolane, 3-methyl-sulfolane, trimethyl phosphate, triethyl phosphate, etc. It is not limited to these.

In the secondary battery of the present invention, when a conductive conjugated polymer compound obtained by doping a conjugated polymer compound with an anion or a cation as described above is used for the positive electrode and the negative electrode, the supporting electrolyte of the electrolytic solution is used as the positive electrode. A salt of an anion and a cation which are the same as the anion pre-doped into the conjugated polymer compound and the cation pre-doped into the conjugated polymer compound serving as the negative electrode is used. If the anions and cations doped in the positive and negative electrodes are different from the anions and cations used as supporting electrolytes,
A battery with good performance cannot be obtained.

A specific example of a salt with an anion and a cation is LiPF6
, Li5bF, , LiAsF6, Llclo4, NaP
F6, NaSbF6, NaAsF6, Na(J?0.,
KPF, KSbF6, KAsF6, KC#04, [(
n-Bu)aN)”(AsF6)-1[(n-Bu),
Na"(PF6)-1[(n Bu) 4N"l'
・CIO,, LiAlCA,, LiBF4, Et,
N-BF, but is not necessarily limited to these.

The concentration of the supporting electrolyte used in the battery of the present invention depends on the types of positive and negative electrodes used, charging/discharging conditions, operating temperature,
It cannot be specified as it varies depending on the type of supporting electrolyte and the type of organic solvent, etc., but it is usually 0.0
It is in the range of 0.01 to 10 mol/4, and may be in the form of a slurry or haste in which the electrolyte is partially undissolved.

In the present invention, a conductive conjugated polymer compound pre-doped with an anion is used as a positive electrode, and a conductive conjugated polymer compound pre-doped with a cation is used as a negative electrode.

As a specific example in the case of a secondary battery, for example, if the doped acetylene polymer is (cH)x, then [(CH
)+0”2′(ClO4)−”2′]P positive electrode) y (
n-Bu, N)'・(ClO,)" (supporting electrolyte) '
[(n-Bu, N)+0-024(CHΣ0.024
)X (negative electrode), [(CH)+0°06(PF6)-00
6] Engineering (Tomari pole) / (Et, N)'-・(PF6)”
(Supporting electrolyte)/[(r,i)+0.06(CH)-0
,06)X(negative electrode),C(cu:ff0゛0''(CIO
4)-0050]x (positive electrode)/(Li)+・(C
AO,)-(supporting electrolyte)/[(CH)+0.020
(ClO,)-0,020)]X (negative electrode), [(n-B
u4N)+002(CHΣ0.02)X(positive electrode)/(n
-Bu, N) +・(ClO4)- (supporting electrolyte)
/C(Bu.

N))0.07 (CHΣ0.07)x (negative electrode), etc. can be opened.

In the case of polyvaraphenylene, the above (cH)xL:D
Instead of (C6H4)X, poly(25-thennylene)
In the case of (CH)x, (C4H3S)X is used, and in the case of polypyrrole, (C,H3N) is used instead of (CH)x.
) x is used as a secondary battery of the same type as above.

In addition, in the present invention, different military polymer compounds can be used for the positive electrode and the negative electrode, and specific examples thereof include (
CH) x xL IC'E04 / (C6H4)
X 1(CH)X/LiCAO,/(C,H2S), (
Examples include C6H4)xZLICIO4/(C4H2S)x.

In the present invention, if necessary, a porous membrane of synthetic resin such as polyethylene or polypropylene or natural fiber paper may be used as a diaphragm.

In addition, some of the conjugated polymer compounds used in the present invention undergo gradual oxidation reactions with oxygen, reducing the performance of the battery. It is necessary to be in the state. Additionally, the cells of the present invention may be thin cells, even paper-thin cells, and may have multiple layers stacked on top of each other and coupled together in series or parallel, or may be made up of one long cell each on its own. It may be wound or spiraled.

The secondary battery of the present invention has high energy density, high charge/discharge efficiency, long cycle life, low self-discharge rate, and good voltage flatness during discharge. Furthermore, the secondary battery of the present invention is lightweight, compact, and has a high energy density, so it is suitable for use in portable devices, electric vehicles, gasoline vehicles, and power storage batteries.

EXAMPLES The present invention will be explained in more detail below with reference to Examples and Comparative Examples.

Example 1 [Production of film-like acetylene polymer] 1 was placed in a glass reaction vessel with an internal volume of 500 d under a nitrogen atmosphere.
．． Add 7 m, l of titanium tetrabutoxide,
A catalyst solution was prepared by dissolving in 0 ml of aninole and then adding 2.7 ml of triethylaluminum with stirring.

This reaction vessel was cooled with liquid nitrogen, and the nitrogen gas in the system was exhausted using a vacuum pump. Next, this reaction vessel was
After cooling to 0.degree. C. and keeping the catalyst solution stationary, purified acetylene gas at a pressure of 1 atmosphere was bubbled through.

Polymerization immediately occurred on the surface of the catalyst solution, producing a film-like acetylene high polymer. 49 minutes after the introduction of acetylene, the acetylene gas in the reaction vessel system was exhausted to stop the polymerization.

After removing the catalyst solution with a syringe under nitrogen atmosphere, -78
It was washed repeatedly with 100 ml of purified toluene five times while maintaining the temperature at °C. The film-like acetylene polymer swollen with toluene was a uniform film-like swollen product in which fibrils were tightly intertwined. This swollen product was then vacuum-dried to obtain a reddish-purple film with a metallic luster and a cis content of 98%. In addition, the bulk density of this film-like acetylene polymer is 0.45 g/cc, and its electrical conductivity (DC four-terminal method) is 3.2
Met.

[Preliminary doping]

From the film-like acetylene polymer obtained by the above method, 2
．． Two films of 5cnL x 2.5cm were taken out, and one of them was immersed in a nitromethane solution in which NOKichi BF: was dissolved. - An α-1 P-type layer conductive acetylene polymer was obtained. Also, put another piece of film in N
a.N-type conductive acetylene polymer having a composition of [:CH(Na)0.11] and electrical conductivity of 270-1.c77+, -1 was obtained by immersion in a tetrahydrofuran solution in which a.naphthalene was dissolved. .

[Battery experiment]

FIG. 1 is a configuration explanatory diagram showing one embodiment of a secondary battery of the present invention. In FIG. 1, a positive electrode current collector 2 made of a metal mesh is spot welded onto a stainless steel positive electrode battery frame 1, and a diameter of 15 mm is pre-doped onto the current collector 2 [CH(BF4)0. 09:).

A separator 4 with a thickness of about 2.0 mm made of a polypropylene nonwoven fabric is placed on the positive electrode 3, and the separator 4 contains N a B F 4 purified by a conventional method.
A propylene carbonate solution with a concentration of 1.0 M/L was added, and the top of the separator 4 was doped in advance [
After sequentially stacking the negative electrode 5 made of CH (Na) 0.11) and the negative electrode current collector 6 made of a metal mesh, the stainless steel negative electrode battery frame 7 is mounted, and the positive electrode battery 1 is caulked and sealed. be. 8 is the backing.

This battery was charged for 25 minutes at a current density of 2 mA/ci (doping rate: 6 mol%), and then discharged at the same current density until it became 1. As a result, the number of repetitions was 20,707.・The coulombic efficiency of discharge was below 50%.

Comparative Example 1 Example 1 was performed except that in the [battery experiment] of Example 1, an acetylene polymer doped with Na+ was used as the negative electrode.
A cycle test was conducted under the same conditions.

The number of repetitions was 15,353, and the coulomb efficiency of discharge was below 50%.

Comparative Example 2 In the [battery experiment] of Example 1, BF2 was used as the positive electrode.
A cycle test was conducted under the same conditions as in Example 1, except that a highly doped acetylene polymer was used.

The number of repetitions was 16,666, and the coulomb efficiency of discharge was below 50%.

Comparative Example 3 In the [battery experiment] of Example 1, a cycle test was conducted under the same conditions as in Example 1, except that BF: and Na'' undoped acetylene polymer were used for both the positive and negative electrodes, respectively. At the 95th repetition, the coulombic efficiency of charging and discharging fell below 50%.

[Brief explanation of the drawing]

FIG. 1 is a configuration explanatory diagram showing one embodiment of the two-sink battery of the present invention. 2... Positive electrode current collector, 3... Positive electrode, 4... Separator, 5... Negative electrode, 6... Negative electrode current collector. Patent applicant Showa Denko Co., Ltd. Hitachi Ltd. Representative Patent attorney Sei Kikuchi Figure 1

Claims (1)

[Claims] In a secondary battery in which a polymer compound having a conjugated double bond in the main chain is used for the positive and negative electrodes, the positive electrode is made of a halide of an element selected from Group Ma, Group 1 Va, and Group Va of the periodic table. anion, perchlorate ion or HF
The negative electrode is pre-doped with the anion of the periodic table.
It is doped with a cation of a group A metal or a cation of a quaternary ammonium ion, and a salt of the same anion and cation as the anion and cation pre-doped into the positive and negative electrodes is used as the supporting electrolyte of the electrolyte. A secondary battery characterized by: