JPH0574467A - Macromolecular solid electrolyte - Google Patents

Abstract

PURPOSE:To provide a macromolecular solid electrolyte whose ion conductivity is high at room temperature. CONSTITUTION:A copolymer having hexachlorotriphosphazene, oligoethylene gricole of molecular weight about 550, and monometyl oligoethylene gricole of molecular weight about 350 in a ratio of 1:1:4 is employed as a solid solvent. Anionic polythiophene is prepared by Na chlorination of thiophene-3-(2-ethane sulfonic acid methyl) after electrolytic oxidation and polymerization. The solid solvent and the anionic polythiophene are compounded in such a manner that the ether oxygen ratio of the Na to the phosphazene-oligoether copolymer is 1:16.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a copolymer of a phosphazene compound and an oligoalkylene glycol, which has only a cation as a mobile ion and has a high ionic conductivity, and a π-conjugated polymer having an anionic substituent. The present invention relates to a polymer solid electrolyte composed of a complex of

[0002]

2. Description of the Related Art Polymer solid electrolytes have been attracting attention in recent years from the viewpoint of application to polymer solid secondary batteries, capacitors, wet solar cells and antistatic applications as new ionic conductors replacing conventional electrolyte solutions. ..

In order to increase the ionic conductivity of these polymer solid electrolytes, it is desirable that the polymer have a low glass transition point. Therefore, recently, a solid polymer electrolyte using phosphazene as a polymer has been proposed.
"Journal of the American Chemical Society (J. Am. Chem. Soc.), Vol. 106, 6.
854, 1984 ", AgSO ₃ CF ₃ was added to polyphosphazenes having oligooxyethylene chains in the side chains.
An example in which a salt is melted to obtain an ionic conductivity of about 10 ⁻³ s / cm at 70 ° C. is described. Furthermore, JP-A-63-
In 186766, a composite of oligoalkyleneoxypolyphosphazene and LiClO ₄ was used at 22 ° C.
Discloses a method of obtaining ionic conductivity of about 10 ⁻³ s / cm.

Further, the above-mentioned solid polymer electrolyte uses a composite of a solid polymer solvent and a low-molecular salt. Therefore, both cations and anions contribute to ionic conduction, and when used for a long period of time, there arises a problem that the conductivity decreases due to a concentration gradient of the ions. Annual Meeting of Macromolecules 2
Pp. 337, 1985 ”, an attempt is made to bond an anion to the main chain of a solid polymer solvent to transfer only a cation. In addition, "Journal of American Chemical Society (J. Am. Chem. Soc.)
, 107, p. 3823, 1985 ", an attempt is made to move only cations by complexing a polymer solid solvent with an anionic polymer such as polystyrene sulfonic acid.

[0005]

However, although the above studies have been successful from the viewpoint of cation migration alone, their conductivity is 10% probably because the dissociation of cations and anions is restricted. ^It was as low as ^-6 s / cm or less.
Therefore, in the present invention, only the cation moves due to delocalization of the electron in the π-conjugated polymer that becomes an anion,
An object is to provide a polymer solid electrolyte having a high ionic conductivity at room temperature.

[0006]

The present invention has been made to solve the above problems, and the gist thereof is to provide triphosphazene represented by the following general formula (I) and general formula (I
I) the side chain of phosphorus of the copolymer with oligoalkylene glycol represented by, a solid solvent in which a monoalkyl oligoalkylene glycol represented by the general formula (III) is introduced,
It is intended to provide a polymer solid electrolyte comprising a complex with a π-conjugated polymer having an anionic substituent represented by the general formula (IV) or (V).

[0007]

[Chemical 4] _{HO- (R 1 -O) m -H} (II) R 2 -O- (R 3 -O) n - (III)

[Chemical 5]

[Chemical 6] (However, X is halogen, R ₁ and R ₃ are (CH ₂ ) ₂ or CH (CH ₃ ) CH ₂ , and R ₂ has 1 to 10 carbon atoms.
, An alkyl group having ₄ to 10 carbon atoms or an ether group, Y is CO ₂ or SO ₃ , and M is
Is H, or Li, Na, and K, and m, n, and k represent an integer of 1 or more. )

Examples of the method for synthesizing the copolymer of triphosphazene and oligoalkylene glycol used in the present invention include the following methods. First, N is used to dissolve oligoalkylene glycol in an organic solvent such as 1,4-dioxane (DIOX) or THF to convert a terminal OH group into Na.
Add reagents such as aH, Na naphthalene, or Na benzophenone and stir well. This solution was added to triphosphazene and the catalyst tetraethylammonium bromide (T
EAB) is gradually added to a solution dissolved in an organic solvent such as DIOX or THF, and the mixture is heated at a temperature at which the organic solvent used is refluxed at 5
Allow to react for ~ 10 hours.

The molecular weight of the above-mentioned copolymer in the present invention is preferably not too large, and is preferably 50,000 or less. This is because when the molecular weight of the copolymer is large, it becomes difficult to carry out thermal motion, and when it is combined with an alkali metal salt, high ionic conductivity cannot be exhibited. Therefore, it is desirable to adjust the reaction ratio of triphosphazene and oligoalkylene glycol when synthesizing the copolymer. That is, when the reaction ratio of triphosphazene is low, all the halogens react with glycol to form a high molecular weight product, and when the reaction ratio of triphosphazene is too high, crosslinking by glycol does not proceed and a liquid low molecular weight product is formed. can get. Therefore, the reaction ratio of triphosphazene and oligoalkylene glycol is preferably in the range of 1: 0.6 to 1: 2. The average molecular weight of the oligoalkylene glycol used when synthesizing such a copolymer is 10
It is preferably in the range of 0 to 1000.

There is no particular limitation on the method of reacting the above-mentioned copolymer with the monoalkylene glycol represented by the general formula (III). For example, the terminal OH is the same as in the reaction of the copolymer.
Examples thereof include a method in which the group is converted to Na and reacted.
Since the monoalkyl oligoalkylene glycol completely reacts with the halogen remaining in the copolymer, it is better to add it in an excess of about 1.1 times the molar amount of the copolymer. The molecular weight of this monoalkyl oligoalkylene glycol is
It is better not to be so large, and the range of 100 to 1500 is preferable. When the molecular weight is large, the movement of alkali metal ions in the solid polymer electrolyte due to thermal motion is small. Such a phosphazene-oligoalkylene glycol copolymer in which a monoalkyloligooxyalkylene is introduced into the side chain of phosphorus is used as a solid solvent for the polymer solid electrolyte.

Next, the anionic π-conjugated polymer used in the present invention is described in Japanese Patent Application Laid-Open No. 63-39916 ("conductor having self-doping function and novel polymer compound") by the present applicant. As described above, the structure has a conjugated double bond in the main chain, and the π electron can freely move in the conjugated system, thereby exhibiting conductivity. By binding an anion to the π-conjugated polymer, it is expected that the π-electrons affect the anion and promote the dissociation of the cation.

As the polymer main chain of such anionic π-conjugated polymer, polythiophene or polyaniline can be used as shown in the general formula (IV) or (V). These repeating structure is about one or more "-R ₄ -Y-M" group 0.01~100mol
% Of the monomer is substituted, preferably about 10 to 100 mol% of the monomer is substituted. It is preferable to use H, Li, Na or K for M, and C for X.
It is preferable to use O ₂ or SO ₃ , and R ₄ has 1 carbon atom.
An alkyl group or an ether group of 10 is used.

The general formula (IV) or (V) can be synthesized by the method described in the above-mentioned JP-A-63-39916. To introduce the R ₄ —Y—M group in the general formula (IV) or (V), R ₄ —Y— is added to the monomer.
Polymerization or copolymerization after introducing the M group, or making a polymer or copolymer of an unsubstituted monomer,
Then, a method of introducing the R ₄ —Y—M group into the main chain of the polymer can be mentioned. As a method of covalently bonding the R ₄ —Y—M group to a monomer or a polymer, “Journal of American Chemical Society (J. Am. C
hem. Soc. ), 70, 1556, 1948
The method described in “Year” can be used.
For example, using N-bromosuccinamide (NBS) to link an alkyl group on a monomer or polymer backbone to an alkyl halide, and then treating the halide with sodium cyanide / sodium hydroxide or sodium sulfite. Hydrolyzed to give R ₄ -CO
₂ H and R ₄ —SO ₃ H.

The method of polymerizing the monomer may be a chemical coupling method or an electrochemical method. For example, when synthesizing a thiophene-based polymer represented by the general formula (IV),
A solution containing a methyl ester form of thiophene (Y = SO ₃ ) is added to a solvent such as acetonitrile together with an electrolyte such as tetrabutylammonium perchlorate or tetrabutylammonium fluoroborate. About 0.5 to 5 mA / cm 2 using a working electrode such as glass coated with platinum, nickel or indium tin oxide and a counter electrode (cathode) of platinum or aluminum, preferably platinum.
A current of ² is applied to the electrode, and the electrolytic oxidative polymerization reaction is performed for several minutes to several hours depending on the desired degree of polymerization. The temperature of the polymerization reaction is about -30 ° C to about 25 ° C, preferably about 5 ° C to about 25 ° C. A similar reaction can be performed chemically using an oxidizing agent such as iron chloride. After polymerizing the sulfonic acid derivative, the methyl group is removed by treatment with sodium iodide or the like. The aniline-based polymer represented by the general formula (V) can be synthesized by electrochemical oxidation or chemical oxidation like the above-mentioned thiophene-based polymer.
It can also be prepared by reacting phenylenediamine with appropriately substituted cyclohexanedione.

There is no particular limitation on the method for complexing the solid solvent comprising the phosphazene-oligoether copolymer of the present invention and the anionic π-conjugated polymer, but the following method can be mentioned, for example. Since many anionic π-conjugated polymers are water-soluble, their aqueous solution is added to a solution obtained by dissolving or swelling a phosphazene-oligoether copolymer in water. After that, water is removed by vacuum drying or the like, and the residue becomes a composite polymer electrolyte of the present invention.

The mixing ratio of the phosphazene-oligoether copolymer of the present invention and the anionic π-conjugated polymer is 4 to 40 oxygen in the phosphazene-oligoether, and the anionic π-conjugated polymer is high. 1 cation in the molecule
The amount to be mixed individually is preferable. If the number of cations is more than 1 out of 4 oxygen atoms, it becomes difficult for the ions to move. If the number of cations is less than 1 out of 40 oxygen atoms, the number of ions themselves is small and the conductivity becomes small.

The above-mentioned polymer solid electrolyte can be applied to batteries, capacitors, antistatic agents, electrochromic displays and the like.

[0018]

In the present invention, by using a phosphazene-oligoether copolymer having a low glass transition point as a solid solvent, high ionic conduction is achieved, and electrons in the π-conjugated polymer that becomes an anion are delocalized. As a result, the dissociation of cations is promoted and the cations move independently,
It is estimated that the ionic conduction is further improved.

[0019]

EXAMPLES Next, the present invention will be described in detail by showing examples. Example 1 [Production of phosphazene-oligoether copolymer [A]] 5 g of commercially available hexachlorocyclotriphosphazene was dissolved in 300 ml of DIOX. It has a molecular weight of about 5
50 oligo-ethylene glycol 7.9g both ends N
200 ml of DIOX solution which was converted to Na using aH
Was added dropwise over about 30 minutes and mixed well, then TEAB
0.175 g was added, and the mixture was stirred at 80 ° C. for 8 hours. After the reaction solution was cooled to room temperature, 40 g of monomethyl oligoethylene glycol having a molecular weight of about 350 was similarly charged with N.
300 ml of the DIOX solution of the a-modified product was added dropwise over 30 minutes and mixed well, 0.35 g of TEAB was added, and the mixture was stirred at 80 ° C. for 8 hours. Then, after removing DIOX under reduced pressure, 800 ml of distilled water was added to the residue and mixed well,
The precipitate was exposed and the product was further washed with water and dried at 100 ° C. for 24 hours to obtain a solid solvent which was a copolymer of triphosphazene and polyethylene glycol. Elemental analysis of this solid solvent revealed that the reaction was carried out at a ratio of triphosphazene / oligoethylene glycol / monomethyloligoethylene glycol of 1: 1: 4.

[Production of poly (thiophen-3- (sodium 2-ethanesulfonate)) [B]] Dry pyridine 20
10 g of 2- (3-thienyl) -ethylmethanol in ml
(1.6 × 10 ^-2 mol) was dissolved, and 40 ml of a pyridine solution of methanesulfonium chloride (1.8 × 10 ^-2 mol) was added over 30 minutes at 5 ° C. Then, the mixture was stirred overnight at room temperature and then extracted with ether. Then, the ether was removed to obtain 2- (3-thienyl) -ethyl methanesulfonate, of which 10.7 g (5.2
× 10 ^-2 mol) was converted to NaI (15.4 g, 1.0 x 10 ^-1).
(mol) in 60 ml of acetone and reacted at room temperature for 24 hours. The precipitate was filtered off, the filtrate was extracted with chloroform, and the chloroform was removed under reduced pressure to obtain 2- (3-thienyl) ethyl iodide. Na ₂ SO ₃ 5.3g
In 10 ml of an aqueous solution of (4.2 × 10 ^-2 mol), 2-
5.0 g of (3-thienyl) ethyl iodide (2.1
(× 10 ^-2 mol) was added, and the mixture was heated at 70 ° C. for 45 hours. Then, water was removed under reduced pressure, and washed with chloroform and acetone to obtain crude sodium 2- (3-thienyl) ethanesulfonate, of which 2 g was suspended in ether and 2 ml of thionyl chloride was added dropwise. Stir for 30 minutes. A white powder precipitated upon quenching with ice water, so it was filtered off and recrystallized from chloroform-hexane.
White crystals of 2- (3-thienyl) ethanesulfonyl chloride were obtained. 105 mg (5 × 10 ⁻⁴ mol) of 2- (3-thienyl) ethanesulfonyl chloride was added to 1.5 ml of a distilled methanol solution, and while stirring, 1.74.
ml N, N-diisopropylamine was added. Then, the mixture was stirred for 12 hours and extracted with chloroform. Then, 2- (3-
To obtain methyl thienyl) -ethanesulfonate, 100 mg
Was dissolved in 10 ml of acetonitrile, and electrolytically oxidatively polymerized at −30 ° C. on a platinum electrode using LiClO ₄ as an electrolyte to give black blue poly (thiophen-3- (methyl 2-ethanesulfonate)) on the platinum electrode of the positive electrode. ) Got. By dipping this in an acetone solution of NaI (1 mol / l) at room temperature (24 hours), the methyl group was removed, Na was salified, and poly (thiophene-3- (sodium 2-ethanesulfonate)) [B ] Was obtained.

[Compounding into Polymer Solid Electrolyte] The above N
A 1 wt% aqueous solution of a-type anionic polythiophene [B] was prepared, and the ratio of Na of [B] and ether oxygen of the phosphazene-oligoether copolymer [A] was 1/32, 1 /.
24, 1/16, 1/12, 1/8 [B]
Was added to [A].

The aqueous solution was vacuum dried at 100 ° C. for 24 hours to obtain a polymer solid electrolyte. The result of measuring the ionic conductivity of this solid electrolyte at 25 ° C. by the impedance method is as shown in a) of FIG. 1, and a high ionic conductor with Na ion migrating alone was obtained. FIG. 1 is a graph showing the relationship between the ratio of alkali metal ions contained in the solid electrolyte to ether oxygen in the oligoether and the ionic conductivity, where the vertical axis is the ionic conductivity and the horizontal axis is the alkali metal ion. And the ratio of ether oxygen in the oligoether.

Example 2 Li-type anionic polythiophene [C] was prepared by using the Na-type anionic polythiophene [B] used in Example 1 with an ion exchange resin. This aqueous solution of [C] was prepared and Li-type polymer solid electrolytes of various concentrations were obtained in the same manner as in Example 1. The result of measuring the ionic conductivity of this solid electrolyte at 25 ° C. by the impedance method is as shown in b) of FIG.

Example 3 [Production of polyaniline dicarboxylic acid sodium salt [D]] In a nitrogen atmosphere, in 380 ml of distilled butanol,
8.51 g of 2,5-dicarboxyethyl-1,4-cyclohexanedione were suspended in which 3.59 g of p was added.
-Phenylenediamine butanol solution (20 ml) was added and 40 ml glacial acetic acid was added. Then, the mixture was refluxed for 36 hours and then refluxed for 12 hours in an oxygen atmosphere. The black precipitate was filtered and subjected to Soxhlet extraction with chloroform, chlorobenzene and ether to obtain polyaniline dicarboxylic acid ethyl ester. The above ester was then suspended in DMF and 50 wt% NaOH aqueous solution (excess) was added,
The mixture was stirred at 100 ° C. for 48 hours in a nitrogen atmosphere. The reaction solution was added to excess HCl aqueous solution at 10 ° C. or lower, and filtered to obtain [D].

[Compounding with Polymer Solid Electrolyte] A 1 wt% aqueous solution of the above-mentioned sodium-type anionic polyaniline [D] was prepared and added to [A] so that the ratio of Na to ether oxygen was 1/16. It was This aqueous solution at 100 ° C for 24 hours
After vacuum drying for a period of time, a polymer solid electrolyte was obtained. As a result of measuring the ionic conductivity of this solid electrolyte at 25 ° C. by an impedance method, it was 8 × 10 ⁻⁶ s / cm.

Example 4 [Production of phosphazene-oligoether copolymer [E]] In Example 1, 7.9 g of oligoethylene glycol having a molecular weight of about 550 used in the production of phosphazene-oligoether copolymer [A]. In the same manner as in the production of [A], except that 40 g of monomethyl oligoethylene glycol having a molecular weight of about 350 and 6.39 g of oligopropylene glycol having a molecular weight of about 445 and 13.8 g of 2,2-methoxyethoxyethanol were used. Phosphazene
Oligoether copolymer [E] was produced. Elemental analysis of [E] revealed that the reaction of triphosphazene, oligopropylene glycol, and 2,2-methoxyethoxyethanol was 1: 1: 4.

[Compounding with Polymer Solid Electrolyte] A 1 wt% aqueous solution of Na-type anionic polythiophene [B] produced in Example 1 was prepared using [E] as a solid solvent.
It was added so that the ratio of Na in [B] to ether oxygen in [E] was 1/16. This aqueous solution was vacuum dried at 100 ° C. for 24 hours to obtain a polymer solid electrolyte. The ionic conductivity of this solid electrolyte at room temperature was 5.8 × 10 ⁻⁵ s / cm.

Example 5 [Preparation of poly (thiophen-3- (sodium 2-butanesulfonate)) [F] 4-to 250 ml of dry pyridine
7. Dissolve 10.5 g of (3-thienyl) butanol,
5 g of methanesulfonyl chloride was added at 25 ° C over 10 minutes. The reaction mixture was stirred at room temperature for 6 hours and then extracted with ether. Then, the ether was removed to obtain 4- (3-thienyl) butyl methanesulfonate, and 7.55 g (3.2 × 10 ^-2 mol) of 9.65 g was obtained.
Was added to 70 ml of a solution of NaI in acetone and reacted at room temperature for 24 hours. The precipitate was filtered, the filtrate was extracted with chloroform, and the chloroform was removed under reduced pressure to obtain 4- (3-thienyl) butyl iodide. 6.35 g (5 x 10
^-(2 mol) of Na ₂ SO ₃ aqueous solution 10 ml, 4- (3
-Thienyl) butyl iodide 6.70 g was added,
Refluxed for 18 hours. Next, water was removed under reduced pressure, and the residue was washed with chloroform and acetone to obtain crude sodium 4- (3-thienyl) butanesulfonate. 2 of these
g was suspended in 20 ml of distilled DMS, 2.86 g of thionyl chloride was added, and the mixture was stirred for 3 hours. The reaction solution was quenched with ice water, extracted with ether, and the solvent was removed under reduced pressure.
4- (3-thienyl) butanesulfonyl chloride was obtained. 362 mg (1.5 × 10 ⁻³ mol) of 4- (3-thienyl) butanesulfonyl chloride was dissolved in distilled methanol, and 392 mg of N, N-diisopropylethylamine was added. Then, the mixture was stirred for 2 hours, extracted with chloroform, and the solvent was removed under reduced pressure to give 4-
Methyl (3-thienyl) -butanesulfonate was obtained. 200 mg of this is dissolved in 10 ml of acetonitrile,
When LiClO ₄ was used as an electrolyte and electrolytically oxidatively polymerized at −30 ° C. on a platinum electrode, black-brown poly (thiophen-3- (methyl 4-butanesulfonate)) was obtained on the platinum electrode of the positive electrode. This is a solution of NaI in acetone (1mo
1 / l) at room temperature (24 hours) to remove the methyl group, followed by Na salification to give poly (thiophen-3-
(Sodium 4-butanesulfonate)) [F] was obtained.

[Compounding with Polymer Solid Electrolyte] A 1 wt% aqueous solution of Na-type anionic polythiophene [F] was prepared, and Na and ether were added to the phosphazene-oligoether copolymer [A] produced in Example 1. Oxygen ratio is 1/16
Was added. This aqueous solution was vacuum dried at 100 ° C. for 24 hours to obtain a polymer solid electrolyte. The ionic conductivity of this solid electrolyte at room temperature is 1.8 × 10 ⁻⁵ s / c.
It was m.

Example 6 [Production of poly (thiophen-3-sodium acetate [G]] 200 mg of commercially available thiophen-3-acetic acid was dissolved in 10 ml of acetonitrile, and electrolytically polymerized on a platinum electrode at room temperature using LiClO ₄ as an electrolyte. However, black-blue poly (thiophene-3-acetic acid) was produced, which was dissolved in water and exchanged with Na-type cation exchange resin to form Na-type poly (thiophene-3-sodium acetate) as a 1 wt% aqueous solution. A 1 wt% aqueous solution of [G] was obtained.

[Compounding with Polymer Solid Electrolyte] A 1 wt% aqueous solution of Na-type anionic polythiophene [G] was added to the phosphazene-oligoether copolymer [A] prepared in Example 1 in a ratio of Na to ether oxygen. Was added to be 1/16. The polymer solid electrolyte was obtained by vacuum-drying this aqueous solution at 100 ° C. for 24 hours. The ionic conductivity of this solid electrolyte at room temperature is 3.8 × 10 ⁻⁶ s /
It was cm.

[0032]

EFFECTS OF THE INVENTION According to the constitution of the present invention, which is composed of a complex of a phosphazene-oligoether copolymer and a π-conjugated anionic polymer, the cations move independently and the ionic conductivity at room temperature is increased. A polymer solid electrolyte having a high degree can be obtained.

[Brief description of drawings]

FIG. 1 is a graph showing a relationship between a ratio of an alkali metal ion of a solid electrolyte and an ether oxygen in an oligoether and an ionic conductivity.

Claims (1)

[Claims] 1. A monoalkyl group represented by the general formula (III) is added to the phosphorus side chain of a copolymer of triphosphazene represented by the following general formula (I) and an oligoalkylene glycol represented by the general formula (II). A polymer solid electrolyte comprising a complex of a solid solvent having an oligoalkylene glycol introduced therein and a π-conjugated polymer having an anionic substituent represented by the following general formula (IV) or (V). [Chemical 1] _{HO- (R 1 -O) m -H} (II) R 2 -O- (R 3 -O) n - (III) ## STR2 ## [Chemical 3] (However, X is halogen, R ₁ and R ₃ are (CH ₂ ) ₂ or CH (CH ₃ ) CH ₂ , and R ₂ has 1 to 10 carbon atoms.
, An alkyl group having ₄ to 10 carbon atoms or an ether group, Y is CO ₂ or SO ₃ , and M is
Is H, or Li, Na, and K, and m, n, and k represent an integer of 1 or more. )