JPS6231962A - Secondary battery - Google Patents

Abstract

PURPOSE:To reduce self discharge and lengthen discharge life by using a conductive polymer and electrolyte which have a specified constitution. CONSTITUTION:A conductive polymer is polyaniline whose molar ratio of hydrogen to carbon is 0.75-0.85 and having an anion structure in its principal chain. Electrolyte is prepared by dissolving a double salt of lithium in a mixture solvent of propylene carbonate and ether. Anions are doped by charge and undoped by discharge. This means that anions are released from polyaniline. Thereby, self discharge of a battery is reduced and discharge life is lengthened.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a secondary battery using a conductive aniline polymer as a positive electrode active material.

[Prior art]

Many reports are known regarding technologies for batteries that can be charged and discharged, that is, secondary batteries.

A typical secondary battery uses a conductive polymer as an electrode active material, and it is known that polyacetylene is used as an example of the conductive polymer. (For example, U.S. Pat. No. 4,321.

114, 4,442, 1.87).

JP-A No. 56-136469 discloses that polyacetylene is used as an electrode active material for the positive and negative electrodes, and
4- and other anions, and lithium ions and other negative electrodes.
CC4H9) Doping with cations such as 4N+
Techniques are disclosed for forming type and n-type conductive polyacetylene and for and-pumping these ions in a discharge.

Further, secondary batteries using polypyrrole as a positive electrode active material are also known, and secondary batteries using polythiophene or polyphenylquinoline as positive and negative electrode active materials are also known.

All of the known secondary batteries described above use a non-aqueous solvent electrolyte.

All of the above-mentioned known secondary batteries have relatively short cycle lives, and secondly, self-discharge is large, so they have not been put into practical use.

On the other hand, in recent years there have been reports on the electrochemical behavior of polyaniline, and attempts have been made to apply it as an electrode active material for secondary batteries. Polyaniline can be polymerized from an acidic aqueous solution of aniline by electrolytic oxidation reaction, and the polymer film formed on the electrode exhibits a reversible redox reaction in an acidic aqueous solution containing a supporting salt and is electrochemically active. The electrical conductivity of polyaniline in the dry state is from 10-” to 10-18-c.
It has been found that it changes up to +n-1.

The electrolytically synthesized polyaniline described above was used as the electrode active material for the positive electrode, zinc was used for the negative electrode, and 1 mol of Z was added to the electrolyte.
Adjust the pH by adding sulfuric acid to the nSO4 aqueous solution or the same aqueous solution.
It is possible to charge a battery using a battery with a reduced voltage, and an open circuit voltage of 1.2 to 1.6 V can be obtained after charging [Electrochemical Society of Japan 50th Conference Abstracts, p. 123 (198
3)).

However, as mentioned above, this battery uses an aqueous solution as the electrolyte, so the battery voltage is low, and dendritic precipitation of zinc is inevitable during charging, which can cause electrodes to fall off and short circuits between electrodes. , it is very difficult to function as a secondary battery.

In addition, polyaniline was synthesized by constant potential electrolysis on platinum with a 2M HCflO4 aqueous solution containing aniline, and this was used as an electrode active material in the positive electrode. Metallic lithium was used as the negative electrode, and 1 mofl/11 lithium perchlorate was added to the electrolyte. It is also known to use dissolved propylene carbonate solutions. The open circuit voltage of this secondary battery after charging is 3.6 to 4. O
v was obtained, and a charge/discharge cycle test was performed at 56% of the maximum capacity, and the coulombic efficiency was 100% after 50 cycles.
[Collection of abstracts of the 24th Battery Symposium, p.
1.97 (1983)). As mentioned above, this secondary battery has a high battery voltage and high energy density, but there is a phenomenon in which metallic lithium dendrites are deposited during charging.
Very short cycle life. Furthermore, according to research conducted by the present inventors, this secondary battery has a high self-discharge rate.

[Problem that the invention seeks to solve]

81 The present invention aims to eliminate the drawbacks of the above-mentioned known secondary batteries (short charging and discharging life, and high self-discharge), and its purpose is to provide a rechargeable battery with low self-discharge and high self-discharge. The aim is to provide a secondary battery with a long discharge life.

[Means for solving problems]

In order to achieve the above object, the secondary battery of the present invention is a secondary battery in which a positive electrode using a conductive polymer as an electrode active material and a negative electrode made of a lithium alloy are opposed to each other with an electrolyte solution in between. The device is characterized by a jaw in which the conductive polymer and the electrolyte are configured as shown in (a) and (b) below, respectively.

(a) The conductive polymer has a molar ratio of hydrogen to carbon (
average value) is 0.75 to 0.85, the molar ratio of nitrogen to carbon (average value) is 0.15 to 0.18, and is made of polyaniline having an aniline structure in the main chain.

(b) The electrolytic solution is one in which a double salt of lithium is dissolved in a mixed solvent of polypropylene carbonate and an ether solvent.

[Effect]

In the secondary battery configured as described above, anions are doped by charging, and anions are undoped by discharging (that is, anions are released from polyaniline).

This phenomenon allows the battery to function as a secondary battery with little self-discharge and a long cycle life.

As anions (404-, PF6-, BF4-t
AsF, -, etc. can be used.

The polyaniline mentioned above is, for example, HBF4 containing aniline.
It is obtained by electrochemically oxidatively polymerizing an aqueous solution of (using platinum as an electrode).

Moreover, the polyaniline can also be obtained by chemical synthesis by adding an oxidizing agent such as ammonium persulfate to an aqueous solution of HBF4 containing aniline.

The general structural formula of the above polyaniline is listed below (1)
It is like the formula.

The component composition of this polyaniline was determined by thermally decomposing the polyaniline and measuring N by gas chromatography.

It can be obtained by measuring Go, H, and O and calculating the amounts of N, C, and H.

The structure of the above formula (1) includes modifications such as the following formula (1').

X- in the above formulas (1) and (2) means an anion. The value of n is considered to be 20 or more, judging from the molecular weight of polyaniline soluble in dimethylformamide. According to the inventor's experiments.

−11= When 20<n, it is easy to obtain good results.

The present inventor conducted elemental analysis of polyaniline obtained by electrolytic synthesis from a BHF4 aqueous solution containing aniline and polyaniline obtained by chemical synthesis, and found that it has a structural formula as shown in the following formula (2). I confirmed that there is.

Polyaniline having the structural formula of formula (2) above is used as the active material of the positive electrode, and anion BF4- is doped during charging, and the BF4- is doped during discharging.
The reaction when pinging is expressed by the following equation.

The electrical conductivity of polyaniline having the structure of the above formula (2) shows 58-an-1 in a dry state, and when it is undoped with an electrolyte, it changes as shown in Figure 1 and finally reaches 0.1 S cm. -am-', but it was experimentally confirmed that it exhibits excellent conductivity as an electrode active material even in a discharge state.

The positive electrode is a mixture of an active material powder made of polyaniline (the structural formula is formula (1) above) obtained by electrolytic synthesis or chemical synthesis, and a powder of a conductive material such as acetylene black. It can be manufactured by mixing a binder such as polytetrafluoroethylene and press-molding the mixture. When implementing the present invention, the above (1)
Polyaniline having the structure of the formula contains 50 to 1 in the active material.
00% (weight %). Above (1)
Polyaniline having a structure other than the above has insufficient (or no) ability to dope anions and does not have good performance.

In order to obtain polyaniline having the structural formula (1) above, the molar ratio of hydrogen to carbon is set to 0.75 to 0.85 (average value), and the molar ratio of nitrogen to carbon is set to 0.15 to 0.85 (average value). 18 (average value).

The lithium alloy of the negative electrode includes aluminum, silicon,
It is desirable to form an alloy of at least one of magnesium and lithium. In particular, alloys of aluminum and lithium tend to produce good results.

In either case, the lithium content is preferably 20 to 80% (atomic %).

JP-A No. 56-86463 includes magazine A, Si,
Pb.

Mg, Sn, Na, Bi, Cd, Ca, C
o, Cu.

Lithium alloys containing Ag, etc. have been disclosed, and JP-A No. 57-98977 discloses Li-AfL-
Although Mg alloys are disclosed, these alloys are applicable to the present invention.

When an alloy in which these elements are added to lithium is used as an electrode, it has the effect of suppressing the precipitation of lithium dendrites during charging, resulting in a longer cycle life.

The electrolytic solution contains a lithium salt as an electrolyte, and is a mixture of propylene carbonate and an ether solvent. As the lithium salt, LiB F4. LiP
0 magazine 04. It is preferable to use LIASFG or the like. Further, as the ether solvent, dimethoxyethane, dimethoxymethane, etc. can be used, but it is preferable to use dimethoxyethane.

If an electrolytic solution that does not contain an ether solvent is used, there is a risk that self-discharge may occur or the Coulombic efficiency may decrease. The cause of such problems is thought to be that propylene carbonate decomposes during charging, and its products deteriorate polyaniline. It was found that when ether was mixed with propylene carbonate, the amount of propylene carbonate decomposed during charging was suppressed to 174 or less. Suppression of decomposition significantly reduces the negative effects of decomposition products.

Containing an ether solvent reduces the viscosity of the electrolyte, making it easier for the electrolyte to diffuse.

This lowers the electrical resistance of the electrolytic solution and improves its conductivity, making it possible to lower the charging voltage by 0.2 to 0.5 volts. By lowering the charging voltage, the effect of suppressing the decomposition of propylene carbonate during charging can be further enhanced. 8th
The figure shows the relationship between conductive dust and the amount of propylene carbonate in a mixed solvent of propylene carbonate and dimethoxyethane containing 1 mol of LiCa04, and Figure 9 shows the relationship between the viscosity of the electrolytic solution and the amount of propylene carbonate. ing.

The temperature of the electrolyte is 25°C. From these figures, it can be seen that the amount of propylene carbonate is preferably in the range of 20 to 80 vol 1%.

It is highly preferred that polyaniline, which is the active material of the positive electrode, is in the form of fibers. When polyaniline is obtained by electrolytic synthesis, fibrous polyaniline is obtained. Even when polyaniline is obtained by chemical synthesis, fibrous polyaniline can be obtained by maintaining the temperature of an aqueous solution containing aniline at about 30° C. or higher. The dimensions of the fibers obtained by these synthesis methods are approximately 1000 to 3000 angstroms in diameter and several micrometers to more than ten micrometers in length. When the temperature of the alidine-containing aqueous solution in chemical synthesis is about 20° C. or lower, the shape of the obtained polyaniline becomes granular. It was confirmed that when fibrous polyaniline was used as the positive electrode active material, the anion doping rate was significantly higher than when granular polyaniline was used, and the charge and discharge cycle life could be extended.

When assembling a secondary battery, it is preferable to use a porous separator and hold the electrolyte in the pores of the separator.

It is preferable to use an electrically insulating material such as polypropylene carbonate or a glass filter for the separator.

〔Example〕

Figure 1 shows the and-
FIG. 3 is a characteristic diagram showing ping and electrical conductivity.

(Example 1) Platinum was used as a working electrode and a counter electrode in an aqueous solution of 0.5MHBF containing 0.1M aniline, and the potential of the working electrode was maintained at 0.8■ with respect to a silver-silver chloride reference electrode. Polyaniline was produced on the platinum working electrode. This was scraped off, washed with water, vacuum dried, and powdered. When observed with an electron microscope, it was found to be fibrous. In addition, as a result of elemental analysis of carbon, hydrogen, and nitrogen to determine the molar ratio, the molar ratio between hydrogen and carbon is 0.75 to 0.85, and that between nitrogen and carbon is 0.15 to 0.18, The structural formula is (2
) was as shown in the formula.

Polyaniline powder was made into pellets with a diameter of 9rNn under a pressure of 100kg/cm', and the electrical conductivity was determined by measuring the resistance using the 4-terminal method.The results were 3.8 to 5. O8-■-1 was obtained.

Using this polyaniline pellet as a working electrode and platinum as a counter electrode, cyclic portammetry in a propylene carbonate and dimethoxyethane solvent containing IMLiBF was performed as shown in Figure 2. A reduction current (shown as a solid line) was observed.

The positively flowing current, ie, the oxidation current, is the doping of BF4- into polyaniline, and the negatively flowing current, ie, the reduction current, is the undoping of BF4- from the polyaniline. When polyaniline is used as the electrode active material in the positive electrode, the former doping corresponds to charging, and the latter undoping corresponds to discharging. The ratio of the amount of electricity for doping to the amount of electricity for undoping, ie, the Coulomb efficiency, was approximately 100%.

(Example 2) 11% by weight of carbon (acetylene black) was added to the polyaniline synthesized in Example 1 and mixed, further polytetrafluoroethylene was added as a binder,
A pellet formed by molding at a pressure of 100 kg/cmQ and having a diameter of 9IIw11 was used as a positive electrode. A mixed solvent of propylene carbonate and dimethoxyethane containing 1 M LiBF4 (1
:1 volume ratio) as the electrolytic solution and an 80Lj, -20AQ (atomic ratio) alloy as the negative electrode to construct a battery. BF4-
The doping rate of polyaniline was 20 mole percent (relative to aniline) units.

A shown by a solid line in FIG. 3 shows the change in charging voltage during constant current charging and discharging after discharging at 5 mA/am' until the battery voltage reached 1.5 cm in Example 2.

A' in the same figure similarly shows the change in discharge voltage. The open circuit voltage in this example is 3. Ov was obtained. The results of a charge/discharge cycle experiment conducted under the conditions described above are shown in FIG. 4C.

A total of 630 cycles were obtained. After the 25th charge, the battery was left open for 24 hours. Thereafter, the battery was discharged under the same conditions as charging, and the self-discharge rate was determined from the amount of electricity, and the result was 4.5%/day.

(Comparative Example 1) The polyaniline obtained in Example 1 was immersed and stirred in an IM KOH aqueous solution for 5 hours, then washed with water and vacuum dried. This was molded at a pressure of 100 kg/■2 to form a pellet with a diameter of 9 sides, and the resistance was measured using the 4-terminal method at a constant 20°C to determine the electrical conductivity.The result was approximately 10-S-■-1. . This polyaniline powder was mixed with 11% by weight of carbon (acetylene black) and formed into pellets with a diameter of 91 m under the above conditions. This was used as a positive electrode to construct a battery similar to Example 1, and under the same conditions. It discharged, but it could not be discharged.

It can be seen that in Comparative Example 1, polyaniline does not incorporate anions and does not function as a secondary battery.

The reason why anion cannot be doped in this way is that the structural formula of polyaniline is different from the above formula (1).

(Example 3) A 1M HBF4 aqueous solution containing 0.2M aniline was heated at 40°C.
Ammonium persulfate ((NH,)2S, O□)
was added to give a concentration of 0.1M, and the mixture was left to stand for 5 hours while stirring. The precipitate was washed with water and dried under vacuum to obtain powdered polyaniline, which was observed under an electron microscope and found to be fibrous.

This powder was molded at a pressure of 100 kg/an', and the electrical conductivity was determined by measuring the resistance using the 4-terminal method as pellets with a diameter of 9 m, and found to be 2.68-(1)-1. Polyaniline powder obtained by chemical synthesis in this way,
In the same manner as in Example 2, carbon and polytetrafluoroethylene were added to form pellets. A battery similar to that of Example 2 was assembled using this as a positive electrode, and a battery test was conducted under the same conditions. The number of charge/discharge cycles to obtain 100% coulombic efficiency was 720. The self-discharge rate of this battery was 4.8 percent/day.

(Comparative Example 2) A battery was constructed using the same positive electrode and negative electrode as in Example 2, and using a propylene carbonate solvent containing 1 M LiBF4 as an electrolyte. The battery test was conducted under the same conditions as in Example 2. Voltage changes during constant current charging and discharging at a current density of 5 mA/am2 are shown as B and B' in FIG. A broken line B indicates a change in charging current when charging and discharging at a constant current in Comparative Example 2, and a broken line B' similarly indicates a change in discharge voltage.

It can be seen that the voltage flatness of Comparative Example 2 is inferior to the voltage change curves A, , A' (solid lines) in Example 2.

The coulombic efficiency in Comparative Example 2 is shown in D in FIG.

The number of charging and discharging cycles at which the coulombic efficiency remained 100% was 183. Further, the self-discharge rate in Comparative Example 2 was 8% and 7 days.

Comparative Example 2 revealed that a secondary battery using only propylene carbonate as an electrolyte had poor durability and voltage characteristics. The cause of such defects is thought to be that propylene carbonate has a high viscosity and does not wet the electrode well.

(Comparative Example 3) A battery similar to Example 2 except for the negative electrode was constructed, and a metallic lithium foil was used as the negative electrode.

The battery test was conducted under the same conditions as in Example 2. The open circuit voltage of the battery was almost the same as that of Example 2.

However, the number of charging and discharging cycles was approximately 120 to 1.50 times. This Comparative Example 3 revealed that it was difficult to obtain sufficient durability when pure lithium metal was used as the negative electrode.

(Example 4) A battery similar to Example 2 was constructed except for the negative electrode. A lithium-aluminum alloy having the following composition was used for the negative electrode, and each battery was assembled.

(i) 20Li-80AU (atomic ratio) (ji)
40Li-60AQ (atomic ratio) (iii) 50L
The i-50 AΩ (atomic ratio) battery test was conducted under the same conditions as in Example 2. The open circuit voltage of the batteries was 0.2 to 0.4 V lower than the open circuit voltage of the battery of Example 2 for all of the batteries (i), (n), and (in). The number of charging and discharging cycles and self-discharge rate at which nearly 100% Coulombic efficiency was obtained were as follows.

Battery (i), number of cycles: 764 times Self-discharge rate
3.5%/day (IT) battery, cycle count 1162 times Self-discharge rate 4.0%/day (III) battery, cycle count 1320 times Self-discharge rate 4.4%/day (Example 5) The parts other than the negative electrode constituted the same battery as in Example 2, and the negative electrode used a lithium alloy of 98Li-2AQ (atomic ratio). After discharging at a current density of 5 mA/cxn', charging was performed such that the doping rate of BF4- into polyaniline was 20 mol percent. Thereafter, the battery was left open for 15 hours to discharge. This charging-interval leaving-discharging cycle was defined as one cycle, and repeated tests were conducted.

The number of cycles at which a coulombic efficiency of 90 percent or more was obtained was 428, and the self-discharge rate was 3.8 percent/day.

(Example 6) The battery was constructed in the same manner as in Example 2 except for the electrolyte.

A mixed solvent of propylene carbonate and dimethoxyethane containing IMLi (404) was used as the electrolyte.The battery test was conducted under the same conditions as in Example 2, and the number of charging and discharging cycles to achieve 100% coulombic efficiency was 736. The self-discharge rate of this battery was 3.5%/day, which was excellent.

(Example 7) Platinum was used as a working electrode and a counter electrode in an aqueous solution of 0.5MHBF containing 0.1M aniline, and the potential of the working electrode was kept at 0.9V with respect to a silver-silver chloride reference electrode, at room temperature. Polyaniline was synthesized on the working electrode by electrolytic oxidation. Polyaniline was taken from the electrode, washed with water, vacuum dried at 80°C, and atomized. A scanning electron micrograph (magnification: X 10,000) of the polyaniline thus obtained showed that the polyaniline was fibrous with a diameter of about 1.500 angstroms.

To the polyaniline obtained as above, 10% by weight of acetylene black was added and mixed, and then polytetrafluoroethylene was added and stirred.
mg to 300 kg/an Q pressure, diameter 9+
Molded into a nn+ pellet and used as a positive electrode, IM Li
Propylene carbonate and dimethoxyethane in which BF4 was dissolved (
1:1 volume ratio) to the electrolyte, 50 Li -50AQ
A battery was constructed using a (atomic percent) alloy as a negative electrode and polypropylene as a separator between the electrodes. Once the cell was discharged and then charged at a current density of 1 mA/2, the doping rate of BF4- into polyaniline was 67 mole percent/aniline unit. In addition, we conducted a charge and discharge cycle test in which this battery was charged at a current density of 1 mA/am with a doping rate of 30 mol percent/aniline unit, and then discharged at the same current density until the battery voltage reached 1 ■. The coulombic efficiency (ratio of the amount of electricity charged and discharged) was 99% or more.The open circuit voltage of this battery after charging was completed was 3.5V.

(Example 8) Electrolytic oxidation was performed in an IMH, SO4 aqueous solution containing 0.1M aniline under the same conditions as in Example 7, and polyaniline powder was obtained by post-treatment in the same manner. A scanning electron micrograph of this polyaniline powder showed that it was fibrous.

Using this polyaniline, □ Back 5, □ 1. A.1. Aro. 81°-(7)t-'-t?
'When we calculated the puffer fish percentage, it was 58 mol%/
An aniline unit was obtained. In a similar charge/discharge cycle test, the coulombic efficiency was 740%.
More than 100 cycles were obtained.

(Example 9) 0.1M ammonium persulfate ((NH,)as*
ot) The solution was added for 1.5 hours while maintaining the temperature at 40°C to synthesize polyaniline. This polyaniline was washed with water and vacuum dried at 80° C. to form fine particles. A scanning electron micrograph (magnification: X 10,000) of the polyaniline obtained by chemical oxidation at high temperature showed a fibrous structure with a fiber diameter of about 1,500 angstroms.

A battery similar to that of Example 7 was constructed using this polyaniline, and the doping rate of BF4- to the polyaniline was determined to be 62 mol percent/aniline unit. In a similar charge/discharge cycle test, more than 680 cycles were obtained with a coulombic efficiency of 99%.

(Example 10) Chemical oxidation was performed in an IMH, SO4 aqueous solution containing 0.1M aniline under the same conditions as in Example 9, and polyaniline powder was obtained by post-treatment in the same manner. The morphology of this polyaniline in a scanning electron micrograph is fibrous;
Its diameter was approximately 2000 angstroms.

A battery similar to that in Example 7 was constructed using this polyaniline, and the doping rate of BF4- to the polyaniline was determined to be 60 mol percent/aniline unit, and the same charge and discharge cycles as in Example 7 were obtained. In the exam, 99
A cycle number of over 665 was obtained with a Coulombic efficiency of %.

(Example 11) A 0.1 M ammonium persulfate solution was added to a 0.5 M HBF4 aqueous solution containing 0.2 M aniline for 1.5 hours while maintaining the temperature at 20° C. to synthesize polyaniline. This polyaniline was washed with water and vacuum dried at 80° C. to form fine particles. A scanning electron micrograph (magnification: X10,000) of the polyaniline thus obtained showed that the polyaniline had a fine particle morphology.

A battery similar to that of Example 7 was constructed using this polyaniline, and the doping rate of B F4- to the polyaniline was determined to be 34 mol percent/aniline unit. In the same charging and discharging cycle test as in Example 7, 1
After 80 cycles, the Coulombic efficiency began to decrease.

(Example 12) Figures 5 and 6 show a comparison of the performance of secondary batteries using fibrous polyaniline and fibrous polyacetylene as conductive polymers, respectively.

As the positive electrode of the battery in this example, the one obtained in Example 7 was used. The structure of the battery is the same as that of the present invention and that of a comparative example using polyacetylene as the positive electrode active material, and has the structure shown in FIG. FIG. 7 shows a perspective view and a partial sectional view of the secondary battery. Reference numeral 1 indicates a positive electrode, 2 indicates a negative electrode, 3 indicates a positive electrode current collector, and 4 indicates a negative electrode current collector. Current collector 3
゜4 is austenitic stainless steel, for example 18wt%
It is made of Cr-8wt%Ni steel or expanded metal. In this embodiment, stainless steel is used. Reference numeral 5 denotes a separator, which is made of a porous electrically insulating material and holds an electrolytic solution in its pores. Examples of separator materials include polypropylene carbonate,
Glass filters etc. can be used. In this example, polypropylene carbonate is used. Reference numeral 6 is the positive current collector terminal.

7 is a current collector terminal of the negative electrode. These current collector terminals have 18w
Austenitic stainless steel containing t% Cr and 8%+1% Ni was used. 8 is a battery container, and 9 is a cap. A male thread is cut into the cap 9, and a female thread is cut into the inner surface of the battery container 8 so as to engage with this thread. By screwing in the cap 9, the positive electrode 1 is connected to the negative electrode 2.
It's pressed to the side.

The battery container and cap were made of polytetrafluoroethylene. ! The doping rate is 20 mole percent/aniline unit, (3 mole percent/aniline unit) for cells using polyaniline.
(carbon unit), and for batteries using polyacetylene, the horizontal axis is 4 mol percent/carbon unit.
Discharge time (h) and self-discharge rate (%) are plotted on the vertical axis, respectively, where E indicates a battery using polyaniline and F indicates a battery using polyacetylene. In Figure 6, the horizontal axis shows charge-1 hour rest-discharge (current density 5 mA
The number of cycles (times) with / mark 2) as the cycle mode is taken, and the vertical axis is the coulombic efficiency (%), where E is a battery using polyaniline and F is a battery using polyacetylene. It shows.

Batteries using polyacetylene have a high self-discharge rate, and the coulombic efficiency (%) decreases after several tens of cycles.
Batteries using polyaniline have a low self-discharge rate of 4.5%/day after 90 hours of storage time, and a low coulombic efficiency (
%), no decrease was observed even after several hundred tests.

〔Effect of the invention〕

As detailed above, the secondary battery to which the present invention is applied has excellent practical effects such as less self-discharge and long charging and discharging life.

[Brief explanation of drawings]

FIG. 1 is a diagram for explaining the present invention in detail,
FIG. 2 is a characteristic diagram showing the relationship between the undoping and electrical conductivity of electrochemically synthesized polyaniline. Figure 2 is a characteristic diagram showing the cyclic portum gram of a polyaniline electrode in an electrolyte, and Figure 3 is a characteristic diagram showing the charge-discharge curve of a battery with polyaniline as the positive electrode active material and a lithium alloy as the negative electrode. , FIG. 4 is a characteristic diagram showing coulomb efficiency and cycle number, that is, cycle life. FIGS. 5 and 6 are diagrams for explaining the present invention in detail. FIG. 7 is a perspective view showing the structure of a secondary battery according to an embodiment of the present invention. FIG. 8 is a characteristic diagram showing the relationship between the electrical conductivity of the electrolytic solution and the amount of propylene carbonate, and FIG. 9 is a characteristic diagram showing the relationship between the viscosity of the electrolytic solution and the amount of propylene carbonate. 1... Positive electrode, 2... Positive electrode, 3... Positive electrode current collector,
4... Negative electrode current collector, 5... Separator, 6,7...
...Current collector terminal, 9...Cap. Figure 1 B's andjing j1 shot □ 1% Figure 2 Figure 3 F7 Lit! (Professional) Figure 5: Father Okimaki Fe”l (h) Hero, ＼Dan Idori Figure 7

Claims (1)

[Claims] 1. A secondary battery in which a positive electrode using a conductive polymer as an electrode active material and a negative electrode made of a lithium alloy are opposed to each other with an electrolyte interposed therebetween, in which the conductive polymer and the electrolyte are A secondary battery characterized by having each structure as shown below. (a) The conductive polymer has a hydrogen to carbon molar ratio (average value) of 0.75 to 0.85, and a nitrogen to carbon molar ratio (average value) of 0.15 to 0.18. It is made of polyaniline with an aniline structure in its main chain. (b) The electrolytic solution is a solution in which a double salt of lithium is dissolved in a mixed solvent of polypropylene carbonate and an ether solvent. 2. The conductive polymer has a hydrogen to carbon molar ratio (average value) of substantially 0.75 to 0.85, and a nitrogen to carbon molar ratio (average value) of 0.15 to 0.15. 0.18 polyaniline
Secondary batteries described in section. 3. The secondary battery according to claim 1, wherein the ether solvent is dimethoxyethane. 4. The above lithium alloy has a content of 20% to 80% (atomic %)
The secondary battery according to claim 1, which is a lithium-aluminum alloy containing lithium. 5. The above-mentioned lithium double salt is LiBF_4, LiPF_
6, LiClO_4, and LiAsF_6. 6. The above-mentioned polyaniline has an electrical conductivity of 0.1 S・c
1. The secondary battery according to claim 1, wherein the secondary battery is m^-^1 or more. 7. Claim 1, characterized in that the conductive polymer is polyaniline in the form of fibers, and its structural formula is ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(1) Secondary batteries described in section. 8. The secondary battery according to claim 7, wherein the conductive polymer is polyaniline having the structural formula described above and having a substantially fibrous shape. 9. The positive electrode includes polyaniline powder and carbon powder,
The secondary battery according to claim 1, which is bonded with a binder made of polytetrafluoroethylene. 10. The secondary battery according to claim 1, wherein the electrolytic solution is impregnated and held in a porous electrically insulating separator. 11. The secondary battery according to claim 10, wherein the separator is made of polypropylene carbonate. 12. The secondary battery according to claim 10, wherein the polyaniline is in the form of fibers. 13. The above fiber-shaped polyaniline has a diameter of 1
13. The secondary battery according to claim 12, wherein the secondary battery has a diameter of 000 to 3000 angstroms and a length of several microns to more than ten microns. 14. The secondary battery according to claim 10, wherein the positive electrode is a mixture of polyaniline powder and carbon powder bound together with a binder made of polytetrafluoroethylene. 15. The secondary battery according to claim 14, wherein the carbon powder is acetylene black. 16. The secondary device according to claim 1, wherein the positive electrode and the negative electrode each have a current collector provided with a current collector terminal, and are installed adjacent to each pole. battery. 17. The secondary battery according to claim 16, wherein the polyaniline is fibrous. 18. Claim 1, wherein the positive electrode is made by bonding polyaniline powder and carbon powder with a binder made of polytetrafluoroethylene.
The secondary battery according to item 6. 19. Claim 1, wherein the mixture of polypropylene carbonate and an ether solvent contains 20% to 80% (by volume) of carbon polypropylene, with the remainder being ether. secondary battery. 20. Claim 7, wherein the mixture of polypropylene carbonate and an ether solvent contains 20% to 80% (by volume) of carbon polypropylene, with the remainder being ether. secondary battery. 21. According to claim 10, the mixed liquid of polypropylene carbonate and an ether solvent contains 20% to 80% (volume %) of carbon polypropylene, with the remainder being ether. secondary battery. 22. Claim 16, characterized in that the mixture of polypropylene carbonate and an ether solvent contains 20% to 80% (volume %) of carbon polypropylene, with the remainder being ether. secondary battery.