JPS6297261A - Battery - Google Patents

Abstract

PURPOSE:To make inner resistance in a battery lower and cycle life longer instead, by using an organic conductive polymeric material, whose moisture content is specified, for an electrode active material. CONSTITUTION:An organic conductive polymeric material, whose moisture content is less than 500ppm, is used as an electrode active material. As for this polymeric material, polyaniline, especially, such polyaniline as secured by an electrolytic oxidative polymerizing process is separated and formed so excellent in coherence to an anode substrate in time of polymerization and that the substrate is utilizable for a collector body and a vessel for an electrode, so that it is desirable as electrode material. In addition, in order to make it into the moisture content of less than 500ppm, a method of electrochemical or an Soxhlet's extracting processes, etc., using a hygroscopic compound under vacuum heating is used. If this polymeric material is used, internal resistance becomes lowered, cycle life is prolonged and a lightweight battery is manufacturable.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a non-aqueous battery using an organic conductive polymer material such as polyaniline as an electrode active material.

In recent years, there have been many attempts to apply organic conductive polymer materials such as polyaniline to batteries in order to make them lighter. Batteries used as materials tend to have lower internal resistance and shorter cycle life than conventional batteries that use conductive materials such as metal materials as electrode active materials, so it will take some time before they can be put into practical use. Not yet reached.

In particular, is it possible to use organic S-conducting polymer materials as electrodes for batteries with high energy density and high discharge pressure, such as lithium secondary batteries, which are expected to have a wide range of applications in the future? ! When used as a quality, the above tendency becomes even more pronounced.

The present invention was made in view of the above circumstances, and even when used in batteries with high energy density and high discharge voltage such as lithium secondary batteries, polyaniline and other materials have low internal resistance and long cycle life. The object of the present invention is to provide a non-aqueous battery using an organic S-conductive polymer material as a W1 electrode active material.

1. Means and action for determining For example, secondary batteries using alkali metals or their alloys have a high battery voltage and cannot be used as an aqueous electrolyte. Focusing on the fact that non-aqueous electrolytes are used, we conducted intensive research on the effect that water in these non-aqueous secondary battery systems has on battery performance. As a result, these non-aqueous secondary batteries
In particular, because the battery voltage is high, moisture in the battery system can affect current efficiency, cycle life, and
Therefore, when an organic conductive polymer material such as polyaniline is used as an electrode active material, it may have an adverse effect on internal resistance, self-discharge, or the float equinox in a floating state. It is necessary to reduce the water content as much as possible, and the water content of organic 24-conducting polymer materials varies depending on the type of organic conductive polymer material and the synthesis method. The polyaniline that needs to be oxidized can be obtained either by polymerization using a chemical oxidizing agent such as persulfate or by electrolytic oxidation polymerization, or by organic conductive high-conductivity obtained by other synthesis methods. It was found that the moisture content was negligible 1 g compared to molecular materials. As a result of further investigation, we found that if the moisture content of organic conductive polymer materials, including polyaniline, which has these properties is 500 ppm or less, a battery using this organic S conductive polymer material as an electrode active material will have the following properties:
'Even if the IR pond has high energy density and high discharge voltage,
It was discovered that both the internal resistance and the cycle life can sufficiently satisfy the battery performance, and this led to the present invention.

To explain this point in more detail, as shown in the experiment described below, the present inventors heated and dried polyaniline synthesized by electrolytic oxidation polymerization method under reduced pressure, used it as a positive electrode,
A secondary battery was constructed using AJ-Li alloy as the negative electrode, the electrolyte and solvent were sufficiently purified, and the water content of the electrolyte was kept below 8 ppn+, and its characteristics were investigated. Even with these batteries, the current efficiency was not very high, the battery performance deteriorated with repeated charging and discharging, and the cycle life was not long. According to the results of the studies conducted by the present inventors, when polyaniline is prepared by oxidative polymerization method,
Conventionally, this was used by heating and drying it under reduced pressure, but even after such drying, there was still 50% of polyaniline in the polyaniline.
000 to 60,000 ppm, or less, of water remains in the polyaniline, and even if the amount of water in the electrolyte is regulated, this residual water in polyaniline has an adverse effect on battery performance. For this reason, when using conductive polymer materials such as polyaniline as electrodes for batteries, especially electrodes for non-aqueous secondary batteries, it is necessary to use them with a moisture content of 500 ppm or less in order to improve battery performance. This is what I discovered.

The present invention will be explained in more detail below.

Examples of organic conductive polymer materials that can be used as the electrode active material of the nonaqueous battery of the present invention include polymers of benzene and its derivatives such as polyacetylene, polybenzene, polyparaphenylene, and polyaniline, polypyridine, polythiophene, polyfuran, and polypyrrole. , polymers of hetero or polynuclear aromatic compounds such as anthracene and naphthalene, etc. ! There are no restrictions on the type of the material as long as it can be used as an electrode active material. Among them, polyaniline, especially polyaniline obtained by electrolytic oxidative polymerization, deposits and forms on the anode substrate with good adhesion during electrolytic oxidative polymerization, and the anode substrate can be used as a current collector or container for battery electrodes, and is useful for batteries. In addition to simplifying the manufacturing process, secondary batteries using polyaniline as an electrode active material have features such as lower internal resistance and improved Coulombic efficiency. , is suitable as the N electrode material of the battery of the present invention.

In the present invention, water content of these organic conductive polymer materials is 5001)I) 11 or less, preferably 10
0 ppm or less is used as an electrode active material. In this case, an organic conductive polymer material such as polyaniline, which is synthesized by electrolytic oxidative polymerization, washed thoroughly with distilled water, and dried for one day at room temperature, usually has a ppm of 50,000 to 60,000 pp.
m IJ, and it is difficult to reduce the moisture content to below 500 ppn+ using such drying methods. For example, even if the drying treatment is carried out for two days under a reduced pressure of approximately 1 mol Ha while being heated to 50° C., the desired water content cannot be achieved. In order to make the water content of the organic conductive polymer material 500 ppm or less, the following dehydration treatment methods (1) to (4) and combination methods of Class 21a or higher of these dehydration treatment methods are suitable. Note that the method described below can sometimes remove impurities other than water, and is also effective in improving the charging and discharging efficiency of the battery and extending the battery life.

(1) Dehydration treatment method using a hygroscopic compound.

In this method, an organic conductive polymer material is immersed in a non-aqueous solvent containing a hygroscopic compound, and the organic conductive polymer material is dehydrated using the hygroscopic ability of the hygroscopic compound.

Here, as the hygroscopic compound, for example, a fine powder or porous hygroscopic compound such as alumina, molecular sieve, silica, calcium chloride, calcium oxide,
Examples include chemical drying agents such as potassium carbonate, and non-aqueous solvents used during dehydration include the same non-aqueous solvents used as the solvent for the electrolyte of secondary batteries, methanol, Examples include non-aqueous solvents that can easily remove solvents such as ethanol and acetone.
One or more of these nonaqueous solvents can be used. Note that the dehydration treatment method using the hygroscopic ability of the hygroscopic compound is not particularly limited to υ1, and heating, stirring, etc. can be performed as appropriate depending on the type of organic conductive polymer material.

(2) Vacuum heating dehydration treatment method.

This method is a method of heating and dehydrating an organic conductive polymer material under a high vacuum of 0.1 nmt-10 or less, and the heating temperature, heating time, etc. are selected depending on the type of organic conductive polymer material. You can do it by doing this.

(3) Electrochemical dehydration treatment method.

This method uses an organic conductive polymer material as a working electrode,
1@polar material with cation storage and release ability, e.g.
Using an alkali metal or an alloy containing an alkali metal as a pair*, charging and discharging is performed in a dehydrated non-aqueous Fi solution,
Water contained in an organic conductive polymer material is electrochemically dehydrated by dedoping or by holding a working electrode made of an organic S conductive polymer material at a potential in a discharge state. be.

(4) Dehydration treatment method using Soxhlet extraction method.

This method uses a Soxhlet extractor to heat an organic conductive polymer material to reflux in a water-soluble non-aqueous solvent such as methanol, ethanol, acetone, etc. to remove water contained in the conductive polymer material. This method involves extraction and dehydration.

In the present invention, an organic conductive polymer material with a moisture content of 500 ppn+ or less obtained by the above-described dehydration treatment method is used as a Wi electrode active material to constitute either a positive or negative electrode, and this electrode and , the counter electrode of this electrode and a non-aqueous electrolyte constitute a battery as essential components.

When the organic conductive polymer material of the present invention is used as the positive electrode active material of the battery of the present invention, various negative electrode active materials can be used as the negative electrode active material of the battery of the present invention. It is preferable to use, as the active material, a material that can reversibly transfer cations in and out.

That is, it is preferable that the negative electrode active material incorporates cations into the active material in a charged state (reduced state) and releases cations in a discharged state (?I!l state). In this case, the negative electrode active material is preferably a substance with a high degree of conjugated bond in the molecule, and specifically, in addition to polynuclear aromatic compounds such as anthracene, naphthalene, and tetracene, Examples include organic conductive polymer materials and graphite materials similar to those used as the positive electrode active material.

Furthermore, metals that can be monovalent or divalent cations, specifically lithium, sodium, potassium, magnesium, calcium, barium, subcomplexes, etc., and alloys containing them (lithium-aluminum alloys, etc.) are also suitable. Can be used.

In addition, when the organic conductive polymer material according to the present invention is used as the negative electrode active material of the battery of the present invention, the above-mentioned known conductive substances and graphite can be used as the positive electrode active material, and Active material and shite, Meva Ti 02
, Cr203, V20S.

V6013, MnO2, Cuo, MO03.

Metal oxide such as CLISV2010, T f S 21
Metal sulfides such as FeS, CuCoSa, MoSs, Nb3e3. Metal selenides such as vse 2 and the like can also be used.

The electrolyte constituting the battery of the present invention is a compound consisting of a combination of anions and cations, and examples of anions include P
F6-, Sb Fa-, AS Fs-.

Halide anions of group VA elements such as 5bfJ6-, halide anions of group 11A elements such as B Fa -, #CJ4-, r"' (■+ -), Br
−.

Halogen anions such as C2-, perchlorate anions such as Cj Oa-, HF2-, CF(SO3-.

5CN-, SOa --, ) (SO4-8), but is not necessarily limited to these anions. In addition, the cation is Li +.

Alkali metal ions such as Na'', ni+, Mg2'',
Examples include alkaline earth metal ions such as C32'' and 3a2+, A13+, and quaternary ammonium ions such as RaN'' (R represents hydrogen or a hydrocarbon residue). , but not necessarily limited to these cations.

Specific examples of electrolytes having such anions and cations include Li PF6, Li Sb F6,
Li As F et al.

LiClO4, I-ir, LiBr,
I-i C1゜N a P F s + N a S
b F 6+ N ” A S F 6 .

NaCjO< , Na r, KPFs , KSb F
6.

KAs F6, K (JO4, L'l BFa.

+-+MC ora, Li HF2, Li SCN.

KSCN, Li SOg CF3.

(n-C4Hy)a NAS F 6
.

(Low Cs Ht) 4 NPFa.

(n-C4Hy)4NCH)a.

(n-04H7)4 NBF4.

(C2Hs) a NCf0a.

(n -Cal-17>4Nr, etc.) Among these, LiClOs, L
iBF4 are preferred, but the invention is not limited to these compounds.

Note that these electrolytes are usually used in a state dissolved in a solvent, and in this case, the solvent is not particularly limited other than being a non-aqueous solvent, but a relatively highly polar solvent is preferably used. Specifically, buOpyrene carbonate,
Ethylene carbonate, benzonitrile, acetonitrile, tetrahydrofuran, 2-methyltetrahydrofuran, γ-butyrolactone, triethyl phosphate,
Examples include triethyl phosphite, dimethyl sulfate, dimethylformamide, dimethylacetamide, dimethyl sulfoxide, dioxane, dimethoxyethane, polyethylene glycol, sulfolane, dichloroethane, chlorinated benzene, nitrobenzene, etc., or a mixture thereof for 2 or more seconds. can.

Furthermore, as the electrolyte constituting the battery of the present invention, an organic solid electrolyte in which the above electrolyte is impregnated with a polymer such as polyethylene oxide, polypropylene oxide, isocyanate crosslinked product of polyethylene oxide, or phosphazene polymer having an ethylene oxide oligomer in the side chain. , Li 3 N, Li BIJ4, and other inorganic ionic conductors.

Li 4 Si Oa-, Li 3 BO2, etc. (7)
Inorganic solid electrolytes such as IJ tium glass can also be used.

In the battery of the present invention, the lower the water content in the non-aqueous electrolyte, the more preferable it is.
It is preferably at most ppm, particularly at most 10 ppm.

The battery of the present invention is usually constructed by interposing an electrolyte between the positive and negative electrodes, but in this case, if necessary, the positive Al
In between, a porous membrane made of synthetic resin such as polyethylene or polypropylene, natural fiber paper, or the like can be used as a separator.

11 animals 1i As explained above, the battery of the present invention has a water content of 115
By using an organic conductive polymer material of 0.00 ppm or less as an electrode active material, it has low internal resistance, long cycle life, and is lightweight, so it can be used in many fields such as automobiles, airplanes, portable machines, and electric vehicles. It is suitably used for this purpose.

EXAMPLES Hereinafter, the present invention will be specifically illustrated by examples and comparative examples, but the present invention is not limited to the following examples.

[Example 1, 2. Comparative Example] Polyaniline was synthesized on a stainless mesh substrate by constant current electrolytic oxidation polymerization using an aqueous solution containing 1M aniline monomer and 2M HF3F4 as an electrolytic polymerization solution. After thoroughly washing the obtained polyaniline together with the substrate with distilled water, it was dried for one day at room temperature, and then dried for two days under a reduced pressure of approximately 1 + wm l-1 (J) while heating to about 50°C. The moisture content in polyaniline was calculated using the Karl Fischer method and was found to be 560001111111.
Met. - The above polyaniline was immersed in dimethoxyethane to which Molecular Sheeps 4A (manufactured by Wako 1I4i Yakuhin Kogyo Co., Ltd.) was added and dehydrated for two weeks. After removing the solvent from this polyaniline, it was dried for 10 hours under a reduced pressure of approximately 1 mmH (l) while heating to approximately 50'C.
When quantified by Fisher method, it was 4901)l)IS.

Furthermore, it contains water! -490111111 polyaniline was used as the positive electrode, metallic lithium was used as the negative electrode, and the non-aqueous electrolyte was a mixture of propylene carbonate and dimethoxyethane whose water content was 8 ppm or less by thorough dehydration treatment.
:1 Using LiBFa 3M dissolved in a mixed solvent, the upper limit voltage is 4.0 V to the lower limit voltage is 2.0 V171 range is 0.28 m A/d17) if current density is 10
Charge and discharge cycles were performed to electrochemically dehydrate. The water content of the obtained polyaniline was measured by Karl Fischer method and was found to be 85 pplm.

Three types of polyaniline 40 with different moisture contents
When we measured the electric capacity of
ppm was 3.7+nAH, 490 ppm water content was 411 AH, and 85 ppm water content was 4.1111AI-1.

In addition, 40 cm of polyaniline of type 311 with different water content was used as the positive electrode active material, and 1-i-A was used as the negative electrode.
A secondary battery was constructed using a nonaqueous F8 electrolyte having the same composition as that used in the electrochemical dehydration treatment of polyaniline. Note that [+-A1 alloy has a thickness of 200 μm in an electrolytic solution having the same composition as the non-aqueous electrolyte of a secondary battery.
m, an aluminum plate on a disk with a diameter of 15- was used as a working electrode, and Li metal was used as a counter electrode, and a current corresponding to charge compensation of 120 coulombs was applied to the working electrode. +-t- was obtained at the working electrode.
AJ alloy was used.

When the internal resistance of each of the three types of secondary batteries with the above configuration was measured, the water content was 560001)I)T
The secondary battery of the comparative example using polyaniline I, which is outside the scope of the present invention, as an electrode active material has a resistance of 200 Ω and a water content of 49Qppm185 ppm, which uses polyaniline as an electrode active material that satisfies the scope of the present invention. The secondary batteries of Example 1.2 were 50Ω and 30Ω, respectively.

Next, the secondary batteries of Example 1.2 and Comparative Example were
．． By repeatedly charging and discharging by charging at a current density of 28 mA/cwf for 2 hours and then discharging at a current density of 0.28i A/cwf, and measuring the coulombic efficiency (ratio of charge charge m to discharge charge amount). When I investigated the cycle life f life, I'J! shown in the drawing! One was scored.

From the results in the drawings, the cycle life of the secondary battery of Example 1 is 361 cycles, the cycle life of the secondary battery of Example 2 is 420 cycles, and the cycle life of the secondary battery of Comparative Example is 4 cycles.
It was 0 times.

From the above results, the secondary battery of Example 1.2 using an organic tetraelectric polymer material that satisfies the water content range of the present invention as the 74-electrode active material can be made using the same organic conductive polymer material. Even when used as an electrode active material, it was found that the internal resistance was clearly lower and the cycle life was longer than that of the secondary battery of the comparative example whose water content was outside the range of the present invention. The effect was confirmed.

[Brief explanation of drawings]

The drawing is a graph showing the relationship between the number of cycles of charging and the coulombic efficiency (ratio of the amount of charge to the amount of electric charge) in Examples 1 and 2 and the comparative example.

Claims (1)

[Scope of Claims] 1. A non-aqueous battery characterized in that an organic conductive polymer material with a water content of 500 ppm or less is used as an electrode active material. 2. The battery according to claim 1, wherein the organic conductive polymer material is polyaniline. 3. The battery according to claim 1 or 2, wherein the electrolyte constituting the battery is a non-aqueous electrolyte with a water content of 50 ppm or less.