JPS62100951A - Secondary battery - Google Patents

Abstract

PURPOSE:To prevent decomposition of electrolyte and production of inactive coat on the surface of a negative electrode, by adding predetermined amount of hexamethyl-phosphoramide into the electrolyte. CONSTITUTION:A battery is composed of a negative electrode made of an alkaline metal alloy or a complex body composing an alkaline alloy and a conductive high polymer, a positive electrode made of an aniline series polymer, and electrolyte made of an alkaline metal salt and a nonaqueous solvent. And hexamethyl-phosphoramide of 0.01-5vol% with respect to the nonaqueous solvent is added into the electrolyte. By this composition, the electrolyte can be prevented from decomposition and at the same time an ion conductive protective coat is produced on the surface of the negative electrode for preventing the production of an inactive coat. As a result, becomes possible to prolong the cycle lifetime of the battery, while maintaining high charge and discharge performance.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention provides a high-performance secondary battery that has high energy density, good charge/discharge reversibility, extremely low self-discharge rate, and excellent thermal stability. Regarding the next battery.

[Prior Art] Currently, commonly used secondary batteries include lead-acid batteries, nickel/cadmium (Ni/Cd) batteries, and the like. These secondary batteries are single-cell batteries with a pressure of no more than 2.0
V, and is generally an aqueous battery. BACKGROUND ART In recent years, research has been actively conducted on the development of secondary batteries that use lithium as a negative electrode as a secondary battery that can provide a high battery voltage.

When lithium is used for the negative electrode, it is necessary to use a nonaqueous electrolyte because of the high reactivity of water and lithium.

However, when performing a secondary battery reaction using lithium as the 014 active material, lithium ions (Li+) are generated during charging.
Puntorai 1- occurs when is reduced, causing problems such as a decrease in charging and discharging efficiency and a short circuit between the positive and negative electrodes. Therefore,
Many technological developments have been reported to prevent dendrites and improve the charge/discharge efficiency and cycle life of negative electrodes.
For example, a method using a methylated cyclic ether solvent as a solvent for battery electrolytes (K. M. Abraham et al. Palidium Paplies°', edited by G. B. Calvano 3, published by Academic Press, London (1983).
) <K, H, Abraham et at.

in"Ll1un Batteries", J.
P, Gabano.

Editor, ^ academic press, Lo
A method of preventing lithium dendrites by alloying the electrode itself with aluminum [B, M, L, Rao, R, W.

Francis and Age, Nee, Christopher.

Journal of Electrochemical Society, Vol. 124, No. 10, pp. 1490-1492 (1
977) (B, H, L, Itao, R, 14
,Francis,and■,Christo
pher, J., EIectrochem, So.
c.

Vol, 124. No, 10.1490-1492
(1977) > ) etc. have been proposed.

First, as negative electrode active materials, alkali metals and lithium/
In addition to alkali metal alloys such as aluminum, it is also known to use conductive polymers that have conjugated double bonds in their main chains [Lieu Age Curfman, Liu Double Calafer.

Nie Liu Heeger, Earl Kerner.

Nie G. McDiarmid, Physics Review,
, vol. 82G, p. 2327 (1982) (J, t(,
Kaufman, J.W., awfer, ^,
J:lIeger.

Ro to aner, ^, G, HacDiarmid,
phys, Rev,, 826, 2327 (
1982)>) Well-known conductive polymers used in this method include polyacetylene, polythiophene, polyparaphenylene, polypyrrole, and the like.

On the other hand, it is known that a conductive polymer is used as the positive electrode active material in the same way as the negative electrode active material, and Ti82
It is also known to use compounds that form intercalation compounds with alkali metals such as, other chalcogenide compounds, inorganic oxides, and the like.

As a 2J conductive polymer used as a positive electrode active material,
In addition to polyacetylene, there are polythiophenes, polythiophene derivatives, polyparaphenylene, polyparaphenylene derivatives, polypyrrole, polypyrrole derivatives, etc.
Other aniline polymers such as polyaniline and polyaniline derivatives are well known. In addition, specific examples of chalcogenide compounds and non-mM compounds used as positive electrode active materials include TiS2, Nb3S4
.

MO3S4, Co82, FQ32, V2
05.

Cr205, Mn02, Si02,
Co02.

SnO2 and the like are known.

Among these positive electrode active materials, both the oxidation state and the reduction state are relatively stable in the air, and when used in batteries, they have good discharge flatness, can operate at high charge/discharge density, and have low self-discharge. Moreover, an active material with high energy density is an aniline polymer.

[Problems to be solved by the invention] However, when a secondary battery is constructed using an alkali metal alloy for the negative electrode and an aniline polymer for the positive electrode, it is difficult to achieve sufficient reversibility and a low self-discharge rate at the same time. It has been difficult to obtain a secondary battery with a satisfactory high energy density.

This difficulty is largely due to the fact that a stable electrolytic solution with a high ionic conductivity sufficient to reversibly charge and discharge a battery having a large electromotive force of 3 V or more has not been found. For example, LiBF4 or LiCρ04 is added to a mixed solvent of propylene carbonate and 1,2-dimethoxyethane that is commonly used in non-aqueous lithium batteries.
When the electrolyte solution is dissolved, the solvent decomposes during battery operation (charging or discharging), forming a high-resistance film on the negative electrode surface, or increasing the internal pressure of the battery due to decomposition gas, etc., resulting in charging with high current efficiency. Discharge cannot be repeated.

In particular, when a high-resistance film forms on the surface of the negative electrode, that part becomes passivated, and current concentrates locally in areas where electricity can easily pass.
This causes dendrite formation and electrode collapse, and the overvoltage increases rapidly, making it impossible to operate as a battery.

[Means for Solving the Problems] As a result of intensive studies to solve the drawbacks of the above-mentioned conventional techniques, the present inventors added a specific amount of hexamethyl phosphor to an electrolytic solution consisting of an alkali metal salt and a non-aqueous solvent. The present invention was completed based on the discovery that by adding amide, a high-performance secondary battery with an extremely low self-discharge rate, high energy density, high charge-discharge efficiency, and long repeated charge-discharge life can be obtained. I ended up doing it.

That is, in the present invention, the negative electrode is made of an alkali metal alloy or a composite of an alkali metal alloy and a conductive polymer, the positive electrode is made of an aniline polymer, and the electrolyte is a secondary compound made of an alkali metal salt and a nonaqueous solvent. The present invention relates to a secondary battery characterized in that hexamethylphosphoramide is added in an amount of 0.01 to 5% by volume temperature to a nonaqueous solvent in an electrolytic solution.

The alkali metal alloy used as the negative electrode in the present invention consists of an alkali metal, aluminum, magnesium, manganese, tin, zinc, soot, silicon, lead, and cadmium! It is an alloy of at least one metal selected from lY, and representative examples include Li/Aρ alloy, Si/Mg alloy, Li/Aρ/M(1 alloy, S*/S; alloy, 1 -1/8 to/3i alloy, etc. In this case, the alloy ratio is not particularly limited, but it is preferable that the alkali metal atomic ratio during charging is 45% or more.

In addition, the composite used as the negative electrode in the present invention includes the alkali metal alloy and at least one selected from the group consisting of polypyrrole, polypyrrole derivative 9 (wood, polythiophene, polythiophene derivatives, polyquinoline, boriacene, polyparaphenylene, and polyacetylene). Examples include a complex with a kind of conductive polymer. Representative examples of the complex include a complex of Li/AfJ alloy and polybaraphenylene, a complex of Li/Δg alloy and polyacetylene, and a complex of Li/M. (An example is a composite of 1 alloy and polybaraphenylene.The composite here refers to a homogeneous mixture of an alkali metal alloy and a conductive polymer, a laminate, and a base component modified with another component. means a modified form.

The aniline polymer used for the positive electrode in the present invention is an oxidized polymer of an aniline compound represented by the following general formula.

3R4 [In the formula, R1-R4 may be different or the same, and may be a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or a hydrogen atom having 1 to 10 carbon atoms.
It represents a 10 alkoxy group or an aryl group having 6 to 10 carbon atoms. ] Typical examples of aniline compounds represented by the above general formula include aniline, 2-methoxy-aniline, 3-methoxy-aniline, 2,3-dimethoxy-aniline, 2,5-
Dimethoxy-aniline, 2゜6-simethoxyaniline, 3,5-dimethoxy-aniline, 2-ethoxy-3-
Methoxy-aniline, 2,5-diphenylaniline, 2
-Phenyl-3-methyl-aniline, 2,3.5-1-
Rimethoxyaniline, 2,3-diphenylaniline,
Examples include 2.3.5.6-titramethyl-aniline, and among these, aniline is most preferred.

Electrochemical polymerization methods and chemical polymerization methods are known as methods for producing aniline polymers.

An example of a known document on the electrochemical polymerization method is the Journal of the Chemical Society of Japan, page 11, 1801 (1'1184), and an example of a known document on the chemical polymerization method is E.・G. Green and A. E. Woodhead, Journal of the Chemical Society,
, p. 2388, 1910 (A. G. Green
and^, E, 14oodhead, J, Chel,
Soc.

2388 (1910)) is known, but aniline polymers are generally produced by the following method.

In the case of electrochemical polymerization, the polymerization of aniline compounds is carried out by anodic oxidation, and approximately 0.01 = 50TrLA
/clI2, and the electrolytic voltage is usually in the range of 1 to 10 cm, and a constant current method, a constant voltage method, and any other method can be used. The polymerization is carried out in an aqueous solution, a non-aqueous solvent such as an alcohol, a 21-lyle compound, or a mixed solvent thereof, but it is preferably carried out in an aqueous solution. The non-aqueous solvent may or may not dissolve the produced aniline polymer (oxidized polymer).

There is no particular restriction on the pH of the electrolytic solution, but it is preferable that the pH of the electrolyte be
H is 4 or less, particularly preferably H is 2 or less.

pl+:J! A specific example of chu used in J section is HC.
N, HBF4, CF3Co
o G1. Examples include H2SO4 and HNO3, but are not particularly limited to these.

In the case of chemical polymerization, for example, aniline compounds can be oxidatively polymerized in an aqueous solution with a strong oxidizing acid or with a combination of a strong acid and a peroxide such as perfi:4M potassium. Since the aniline polymer (oxidized polymer) obtained by this method can be obtained in powder form, it can be separated and dried before use.

In addition, in both electrochemical polymerization and chemical polymerization, it is also possible to add other additives to the polymerization electrolyte, such as carbon black, Teflon powder, polyethylene glycol, polyethylene oxide, etc. It is.

The non-aqueous solvent for the electrolyte used in the secondary battery of the present invention includes:
Those that are aprotic and have a high dielectric constant are preferred. The nonaqueous solvent need not be the same as the hexamethylphosphoramide added to the electrolyte in the present invention, and may be, for example, ethers, ketones, sulfur compounds, phosphate ester compounds, chlorinated hydrocarbons, or esters. compounds, carbonates, nitro compounds, sulfolanes, etc. can be used, but
Among these, ethers, ketones, phosphate ester compounds, chlorinated hydrocarbons, carbonates, and sulfolanes are preferred, and it is particularly preferred to use ethers and carbonates in combination. Representative examples of these non-aqueous solvents include tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxane, monoglyme,
4-methyl-2-pentanone, 1,2-dichloroethane, γ-butyrolactone, valerolactone, dimethoxyethane, methylformate, propylene carbonate,
Ethylene carbonate, dimethyl sulfoxide, ethyl phosphate, methyl phosphate, chlorobenzene, sulfolane,
Examples include 3-methylsulfolane. Two or more of these solvents may be used in combination.

Further, specific examples of the alkali metal salt used in the secondary battery of the present invention include Li PFe and Li Sb Fe.

LtCJlO+, LiAs Fθ, CF3803 L
i.

Li BF4, Li B (Bu)q.

Li B (Et)2(BU)2, Li B (
ph) 4, etc., but are not necessarily limited to these. These alkali metal salts may be used alone or in combination of two or more.

The concentration of the alkali metal salt varies depending on the charging conditions, operating temperature, type of alkali metal salt, type of non-aqueous solvent, etc., so it cannot be specified unconditionally, but it is generally 0.5.
It is preferably within the range of ~10 mol/l. The electrolyte may be homogeneous or heterogeneous.

In the present invention, hexamethylphosphoramide is added to the electrolyte. The amount of hexamethylphosphoramide added is 0.0 in terms of volume concentration relative to the nonaqueous solvent in the electrolyte.
It is 1-5%, preferably 0.1-2%. If the amount added is less than 0.01% at a volume of 111 degrees, the effect of the present invention cannot be obtained, and if the amount added is more than 5% in volume concentration, side reactions will increase, resulting in poor charge/discharge efficiency and reversibility. descend.

In the secondary battery of the present invention, the amount of the dopant doped into the aniline polymer of the positive electrode is 10 to 100 mol%, preferably 20 to 100 mol%, based on 1 mol of repeating units of the aniline polymer. %.

The amount of doping can be freely controlled by measuring the amount of electricity flowing during electrolysis. The doping may be carried out either under constant current, constant voltage or under varying conditions of current and voltage.

In addition, in the secondary battery of the present invention, the preferable value (discharge depth) of the amount of alkali gold that can be discharged at one time from the alkali metal alloy or the composite of the alkali metal alloy and conductive polymer of the negative electrode is 2% to the amount of alkali metal in
70%, particularly preferably 5% to 50%.

However, if the discharge depth is too large, the electrodes tend to deteriorate, and if the discharge depth is too small, the energy density of the entire battery decreases.
It is desirable to set a suitable discharge depth.

[Function] In the present invention, the effect of adding hexamethylphosphorus amide to the electrolytic solution is extremely remarkable, and although the details of its mechanism of action are not clear, when the volume concentration of 0.0% is added to the electrolytic solution,
By adding 1 to 5% hexamethylphosphoramide, the electrolyte is prevented from decomposing, and an ion-conductive protective film made of hexamethylphosphoramide is formed on the negative electrode surface, resulting in the formation of an ionically conductive protective film on the negative electrode surface. It is believed that the effects of the present invention are achieved because of the effect of preventing the formation of a dynamic film.

[Effects of the Invention] The secondary battery of the present invention has a higher energy density than existing Ni/Cd batteries and lead-acid batteries, has good charge/discharge reversibility, has an extremely low self-discharge rate, and has high performance. It shows the battery characteristics.

In particular, compared to secondary batteries that use electrolytes made from conventional non-aqueous solvents such as alkali metal salts, which do not include hexamethylphosphoramide, the battery can maintain high charge and discharge efficiency. The lifespan of the plaster can be improved well, and the effect is extremely remarkable.

[Example] Hereinafter, the present invention will be explained in further detail by giving Examples and Comparative Examples.

Example 1 [Manufacture of polyaniline] A platinum plate (15 sφ, diameter 0.5
A constant current density of 1.07
Electrolytic polymerization was carried out at 11 A/ax2. In this case, use a platinum plate with the same diameter as above for the counter electrode, and use a platinum plate with the same diameter as the reference electrode.
/Ag (J pole was used.

When the polymerization was stopped when the amount of electrolytic polymerization electricity reached 20 coulombs, a total of 9.6 ff1l was deposited on both sides of the platinum plate.
A dark green polyaniline film with intertwined fibrils as shown in (3) was obtained. The average polymerization potential is A(1/A(J
It was 0.74V with respect to the CJI reference pole.

Next, this polyaniline, like a platinum plate, was immersed in aqueous ammonia having a purity of 28 wt % for about 1 hour. While immersed in ammonia water, ultrasonic waves were applied for about 1 minute.

Next, the polyaniline film together with the platinum plate was transferred to distilled water, and the above operation was repeated twice.

Finally, the polyaniline together with the platinum plate was washed with distilled water for about 1 hour, and the pH of the washing water was 7.2.

Then, it was dried under reduced pressure at 80° C. for 4 hours. The weight M of the polyaniline after drying was (3,8Rg) and had a yellow color.

[Experimental cell configuration]

For the positive electrode, use the polyaniline obtained on the platinum plate by the above operation as a current collector, and set Ll and Δg at 4
An alloy powder 20111jl having an atomic ratio of 50:50 was placed on a nickel wire gauze and pressure-molded into a shape of 15 sφ at about 350° C., and a nickel wire was drawn out from a part of the nickel wire gauze to serve as a negative electrode lead wire.

The exposed portion of the nickel wire was sealed with Teflon shrink tubing.

The electrolyte was prepared by dissolving 1 mol/degree of oxidation of 1iBF4 in a mixed solvent of propylene carbonate and 1,2-dimethoxyethane at a volume ratio of 1:1, and further adding hexamethylphosylamide in the mixed solvent amount. 0.5% was used.

The experimental cell shown in FIG. 1 with the above configuration was used.

[Battery performance test]

First, take the assembled battery in 2. 1 until the voltage reaches OV.
．． Although discharge was carried out at a constant electric density of 07FLA/α2, almost no current flowed. Then, the battery was immediately charged at the same current density until the battery voltage reached 4.0 square meters, and the above operation was repeated under the same conditions. At the 6th cycle, the amount of charging electricity and the amount of M electricity became almost constant, and the amount of electricity was 3.61 coulombs.

Thereafter, the above charging and discharging process was continued, and after the 10th charge, the battery system was left open circuit for 240 hours and a self-discharge test was performed, and the discharge electrical loss after being left unused was 3.
42 coulombs, self-discharge rate for 10 days is 5.2%
Met.

Furthermore, when this battery was repeatedly tested for charging and discharging, the amount of electricity charged and discharged decreased slightly, but the charging and discharging efficiency at the 100th cycle was 94%, and the discharge color was 2.89 coulombs. there were.

The energy density of the positive electrode and negative electrode types determined from the discharge curve of this battery at the 6th cycle is 108Wh/N
It was 9.

Comparative Example 1 Hexamethylphosphoramide was added instead of the electrolyte used in [experimental cell configuration] of Example 1.
:) It/fLmrl (DLi BF4 wo volume ratio is 1
: Completely the same method as in Example 1, except that 1 dissolved in a mixed solvent of propylene carbonate and 1,2-dimethoxyethane was used as the electrolyte [Battery performance test]
I did it.

As a result, at the fourth cycle, the charging/discharging efficiency was 96%, but the maximum discharge electricity m3.48 coulombs was obtained. After that, both the charging and discharging efficiency and the amount of discharged electricity gradually decreased. After the 10th cycle of charging was completed, the self-tli electric rate was examined for 10 days in the same manner as in Example 1, and was found to be 12.3%.

Furthermore, when repeated charging and discharging tests were conducted, the charging and discharging efficiency fell below 50% at the 54th cycle, and the color of discharge electricity at that time also decreased to 1.23 coulombs.

The energy density determined from the discharge curve of this battery at the fourth cycle was 98Wh//(9).

Example 2 [Manufacture of polyaniline] 72+)nmrlllfi 0.22-E/Lz/u(
7) While stirring the 1N-HCl aqueous solution IQOcc with a magnetic stirrer, (NH4)2820B equivalent to 0.25 mol/1 was added as an oxidizing agent to chemically polymerize aniline. The obtained polyaniline was in powder form.

After washing this polyaniline several times with distilled water, it was dried under reduced pressure at 100° C. for 24 hours.

[Preparation of positive electrode]

Next, from the polyaniline treated above, 10.0
Take out the fIPJ and add 1.1 Teflon powder as a binder, 1. OIItg as a binder, and 1. carbon black as a conductive agent. Total 1i12. containing ORg. The powder of o■ was mixed well. Next, this mixture was molded onto a 10-diameter disc so as to include a platinum wire mesh current collector therein. A platinum wire was taken out as a lead wire from a part of the platinum wire mesh, and the lead wire portion was sealed with a Teflon shrink tube to prevent the lead wire from coming into direct contact with the electrolyte.

[Preparation of negative electrode]

An aluminum plate (thickness: 100 μm) with a purity of 99.9% was washed with a 7 molar 71 mm NaOH aqueous solution for 20 seconds, washed several times with distilled water, and dried under reduced pressure.

Next, the aluminum surface was polished with emery paper in an argon gas atmosphere, washed several times with 1,2-dimethoxyethane, and air-dried in an argon gas atmosphere.

This aluminum plate was cut into a disk shape of 10 mm in diameter, leaving a portion of the aluminum plate as a lead wire, and the lead wire portion was sealed with a Teflon shrink tube. The weight corresponding to a disc-shaped aluminum having a diameter of 10 mInφ was 20.0 Ing.

This aluminum electrode and a counter electrode of 110OR lithium metal crimped onto a nickel mesh were combined at a concentration of 1 mol/length.
The aluminum plate was immersed in a tetrahydrofuran solution of BF4, and lithium was deposited on the aluminum plate at a constant electric density of 0.5 mA/as 2 until the amount of electricity reached 35.0 coulombs to electrochemically alloy it. In this case, the interior of the aluminum pole, which was not electrochemically alloyed, was used as an electrode substrate.

[Experimental cell configuration]

The polyaniline obtained in the above [Preparation of positive electrode] was used as the positive electrode, the Li/8ρ gold obtained in (Preparation of negative electrode) was used as the negative electrode, and 1 mol/11 degrees of Li PFe was added to propylene as the electrolyte. A mixture of carbonate and 2-medylene-tetrahydrofuran (1:1 (volume ratio)) was dissolved, and 1.0% hexamethylphosphoramide was added to the mixed solvent (m). The experimental cell shown in FIG. 2 was constructed using a 0.5 mm thick polypropylene diaphragm with an electrolyte impregnated between the two electrodes.

[Battery performance test]

First, a current was started to flow in the direction of the lightning strike at a constant density of 5 mA/cttr 2, and the discharge was stopped when the cell voltage reached 1.5 V. Next, perform the first charge, charging at the same current density until the amount of electricity becomes 4.2 coulombs, and then continue charging to 1.5V.
The charge and discharge characteristics of this battery were investigated by repeatedly discharging it.
.

As a result, the relationship between the charge/discharge efficiency and the number of cycles after the first charge was as shown in FIG. 3(a), indicating extremely good I-Nicle characteristics.

Comparative Example 2 Instead of the electrolyte used in [Experimental cell configuration] in Example 2, 1 mole/19 degrees of 1iPFe was mixed with propylene carbonate at a volume ratio of 1:1 without adding hexamethylphosphoramide. [Battery performance test] was carried out in exactly the same manner as in Example 2, except that a solution dissolved in a mixed solvent of 2-mebule-tetrahydrofuran was used as the electrolyte. As a result, the relationship between the number of cycles and the charging tIi current efficiency was as shown in FIG. 3(b).

Example 3 (Preparation of Negative Electrode) Mo CJ 550Rg was placed in a glass container equipped with a stirrer, and then benzene 200- was added dropwise and reacted at 50° C. for 2 hours with thorough stirring to obtain polyparaphenylene.

This polyparaphenylene was once dried under reduced pressure, washed with a hydrochloric acid-methanol solution, further washed with methanol, and dried under reduced pressure again. Then at 400 °C under an inert atmosphere for 15
Heat treated for hours.

The polyparaphenylene 5Rg obtained by the above method, 20I1g of Li/Δ9 alloy powder with an atomic ratio of 50:50, and 3η of Teflon powder as a binder were thoroughly mixed. This mixture was placed on a nickel wire mesh, and a 15Mφ It was formed into a disk, and a nickel wire was pulled out from a part to serve as a lead wire.

[Experimental cell configuration]

The positive electrode and electrolyte were exactly the same as in Example 1, and the negative electrode was polybaraphenylene obtained in the above [Preparation of Negative Electrode] to construct the experimental cell shown in FIG. 1.

[Battery performance test]

The charging/discharging efficiency of this battery after the ninth repetition of charging and discharging was 99%, and the discharge capacity at that time was 3°82 coulombs. After the 10th cycle of charging, the battery system was left open for 240 hours and a self-discharge test was performed.The amount of electricity discharged in the unused case was 3.54 coulombs, which was 1.
The self-discharge rate on day 0 was 7.3%.

It took 184 cycles for the battery to have a discharge capacity of 25 coulombs or less.

In addition, the energy density per weight of the positive electrode and negative electrode determined from the discharge curve at the 9th repetition was 91.5wh/K.
It was g.

Comparative Example 3 [Battery performance test] was conducted.

As a result, the charging/discharging efficiency of this battery at the 9th repeated charging/discharging cycle was 97%, and the discharge capacity at that time was 3.5
It was 0 coulombs.

Further, the self-discharge rate at the 10th cycle was 15.2%, and the cycle life was 61 times.

Further, the energy density determined from the discharge curve after the ninth repetition was 81.8 wh/K9.

Comparative Example 4 Instead of the electrolytic solution used in [experimental cell configuration] of Example 1, a mixture of propylene carbonate and 1,2-dimethoxyethane in a volume ratio of 1:1 with l, 1BFq at a concentration of 1 mole/percentage was used. The same method as in Example 1 was used, except that the electrolyte was prepared by adding hexamethylphosphoramide in an amount of 6% based on the amount of the mixed solvent to the solution dissolved in the solvent.
Battery performance test] was conducted.

As a result, (the maximum charging/discharging efficiency was 98% in the 5th cycle, and the amount of discharged electricity was 3.53 coulombs, but IJ
, the charge/discharge efficiency and the amount of electricity decreased for each connected body.

After the 10th cycle of charging, the 10
The daily self-discharge rate was found to be 18.5%.

Further, when a repeated charging/firing test was conducted, the charging/discharging efficiency fell below 50% at the 48th cycle, and the discharge electricity ω at that time also decreased to 1.42 coulombs.

The energy density determined from the discharge curve of this battery at the fifth cycle was 104 Wh/Kg.

[Brief explanation of drawings]

1 and 2 are schematic cross-sectional views of a battery experimental cell, and FIG. 3 is a diagram showing the relationship between charge/discharge efficiency and cycle number in Example 2 and Comparative Example 2. 1... Positive electrode 2... Negative electrode 3... Positive electrode lead wire sealed with a Teflon tube 4... Negative electrode lead wire sealed with a Teflon tube 5... Electrolyte 6... Glass container 7...
・Negative electrode 8...Polypropylene diaphragm 9...Positive electrode 10...Positive electrode lead wire 11 sealed with Teflon tube...Negative electrode lead wire 12 sealed with Teflon tube...Teflon container patent Applicant Showa Denko Co., Ltd. Hitachi Ltd.

Claims (1)

[Claims] The negative electrode is made of an alkali metal alloy or a composite of an alkali metal alloy and a conductive polymer, the positive electrode is made of an aniline polymer, and the electrolyte is a secondary compound made of an alkali metal salt and a nonaqueous solvent. In batteries, the volume concentration of the nonaqueous solvent in the electrolyte is 0.01 to 5%.
A secondary battery characterized by adding hexamethylphosphoramide.