JPH0726022A - Oligoethyleneoxypolyphosphazene with cyclic carbonate group and its production and use - Google Patents

Abstract

PURPOSE:To obtain a solid polyelectrolyte excellent in ionic conductivity by introducing cyclic carbonate groups into side chains of an oligoethyleneoxypolyphosphazene. CONSTITUTION:An oligoethyleneoxypolyphosphazene of formula I [wherein X and Y are each group of formula V (wherein 0<=h<=15) or group of formula VI (wherein R is methyl, ethyl, propyl, or allyl; and 0<=k<=15); and m is 3-200,000] having cyclic carbonyl groups in side chains, accelerating dissociation of an electrolytic salt and increasing the number of mobile ions, gives a solid polyelectrolyte excellent in ionic conductivity and is obtd. by reacting polychlorophosphonitrile of formula II (wherein m is the same as above- described), a compd. of formula III (wherein M is an alkali metal; and R and k are each the same as above-described), and a compd. of formula IV (wherein h and M are each the same as above-described) to give a substitution product, hydrolyzing acetonide groups to form a diol deriv., and conducting ring-closing reaction to introduce carbonate groups.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel oligoethyleneoxypolyphosphazene having a cyclic carbonate group, a process for producing the same and a use thereof. INDUSTRIAL APPLICABILITY The compound of the present invention can be used as an electrolyte in electrochemical devices such as all-solid-state primary and secondary batteries, solid-state display devices, sensors and capacitors.

[0002]

2. Description of the Related Art Conventionally, liquid electrolytes have been used for electrochemical devices such as primary batteries, secondary batteries, and electrochromic display devices. However,
The liquid electrolyte is liable to leak to the outside of the component, and the electrode material is likely to be eluted, which causes a problem of long-term reliability. On the other hand, the solid electrolyte does not have the above-mentioned problems, and accordingly, the configuration of the device can be simplified, and further, the weight reduction by thinning the film,
It has advantages such as miniaturization.

These characteristics meet the demands for miniaturization and weight reduction, expansion of shape freedom, and further various electronic parts having high reliability with the progress of electronics. As the solid electrolyte material, inorganic substances such as those described in Tetsuichi Kudo, Kazuo Fueki, "Solid State Ionics" (Kodansha Scientific, 1986), for example, stabilized zirconia,
Silver iodide, silver rubidium iodide, β-alumina and the like are well known. Among these inorganic solid electrolytes,
Some of them have an ionic conductivity similar to that of liquid electrolytes, but they have the fatal drawback of low decomposition voltage, and in many cases it is difficult to form or form a film into an arbitrary shape. Is extremely insufficient. On the other hand, compared with inorganic materials, organic polymers are light in weight, have viscoelasticity, have flexibility, and are characterized by excellent moldability and processability. Polyether such as poly (ethylene oxide) and poly (propylene oxide), as described in "Conductive polymer", pp. 95 to 150 (Kodansha Scientific, 1990),
Poly (ethylene succinate), polyesters such as poly (β-propiolactone), poly (ethyleneimine),
Matrix polymers such as polyimines such as poly (N-methylethyleneimine) have been reported. Furthermore, a solid electrolyte composition comprising a combination of these matrix polymers and an inorganic ionic salt such as lithium or sodium, and those compositions are used.
Batteries such as those described in -169873, 2-295070 and 3-129603 are reported. However, these polymer solid electrolytes have only obtained ion conductivity much lower than the organic liquid electrolytes conventionally used, for example, an organic liquid electrolyte using a mixed liquid of propylene carbonate and dimethoxyethane.

On the other hand, as an attempt to obtain a polymer solid electrolyte having a high ionic conductivity, a polymer solid electrolyte using poly (phosphazene) having a low molecular weight poly (ethylene oxide) introduced in its side chain is disclosed in Japanese Patent Laid-Open No. 61- Poly (phosphazene) in which an organic group containing an amide bond is introduced into the side chain of 254626
Japanese Patent Laid-Open No. 186766/1988 discloses a solid polymer electrolyte using poly (phosphazene) having a branched low molecular weight poly (alkylene oxide) introduced into its side chain. No. 252762. However, although these polymer solid electrolytes have good film-forming properties, they have not reached a level comparable to the ionic conductivity of the above-mentioned organic liquid electrolytes.

[0005]

An object of the present invention is to provide a polyphosphazene having a novel cyclic carbonate group in the side chain, a method for producing the same, and a use thereof as a solid polymer electrolyte having excellent ionic conductivity.

[0006]

The present invention relates to an oligoethyleneoxypolyphosphazene having a cyclic carbonate group on the side chain substituent represented by the general formula (I).

[0007]

[Chemical 5]

[Wherein X and Y are the same or different,
A group (A) or a group (B) is shown.

[0009]

[Chemical 6]

—O (CH ₂ CH ₂ O) kR (B) R represents a methyl group, an ethyl group, a propyl group, or an allyl group, and these may be the same or different. h, and
k represents the average number of repeating ethyleneoxy units, and 0 ≦ h ≦ 15 and 0 ≦ k ≦ 15, respectively. m is 3 to 200
Indicates an integer of 000. However, in at least one repeating unit among the m repeating units, one of X and Y is a group (A) and the other is a group (B). ]

The polyphosphazene of the present invention includes, for example, a polyphosphonitrile chloride represented by the general formula (II) and a general formula (II
I) and the compound of the general formula (IV) are once reacted to obtain a substitution reaction product, and then the acetonide group on the side chain substituent is hydrolyzed to form a diol derivative, followed by a ring closure reaction. And introducing a carbonate group.

[0012]

[Chemical 7]

(In the formula, m is an integer of 3 to 200,000.)

MO (CH ₂ CH ₂ O) kR (III) (In the formula, k represents the average number of repeating ethyleneoxy units, and 0 ≦ k ≦ 15. M represents an alkali metal.)

[0015]

[Chemical 8]

(In the formula, h represents the average number of repeating ethyleneoxy units, and 0 ≦ h ≦ 15. M represents an alkali metal.)

The present invention also relates to a battery using the above-mentioned oligoethyleneoxypolyphosphazene having a cyclic carbonate group.

A feature of the present invention is that the basic structure is polyphosphazene in which oligoethyleneoxy side chains having high ion affinity are arranged in an inorganic polymer skeleton having phosphonitrile as a main chain, which is excellent in flexibility and low temperature characteristics. It is because by introducing a highly polar cyclic carbonate group into the polymer, the dissociation of the electrolyte salt is promoted and the number of mobile ions is increased to obtain a solid polymer electrolyte having excellent ion conductivity.

The present invention will be described in detail below. The oligoethyleneoxypolyphosphazene having a cyclic carbonate group on the side chain substituent represented by the general formula (I) used in the present invention is synthesized as follows. That is, in the dichlorophosphonitrile polymer obtained by ring-opening polymerization of hexachlorotriphosphonitrile, a correspondingly prepared oligoethylene glycol monoalkyl ether and a corresponding alkali metal alcoholate of oligoethylene glycol monopropylacetonide were prepared. It can be produced by carrying out a quantitative reaction. The reaction can be carried out by using a conventional organic solvent, for example, tetrahydrofuran, diglyme, toluene or the like, mixing the respective components at about 10 ° C. or lower, and subsequently heating and refluxing for several hours. As the alkali metal, lithium, Sodium or the like can be used. The acetonide compound thus obtained can be hydrolyzed according to a conventionally known method to obtain a diol derivative as shown in the following formula (V).

[0020]

[Chemical 9]

(In the formula, h represents the average number of repeating ethyleneoxy units, and 0 ≦ h ≦ 15.)

For example, “New Experimental Chemistry Lecture” edited by The Chemical Society of Japan
14 ”, pp. 2495 to 2516, Maruzen (1978), in the presence of a mineral acid such as hydrochloric acid, acetic acid, p-toluenesulfonic acid, an acid such as an ion exchange resin (H ⁺ type). It can be hydrolyzed. The diol derivative thus obtained can be converted into the target oligoethyleneoxypolyphosphazene having a cyclic carbonate group according to a conventionally known method. The ring-closing reaction represented by the following formula (VI) is described in “The 4th Edition Experimental Chemistry Lecture 20”, 272, edited by The Chemical Society of Japan.
It can be carried out according to the method described in pages 276, maruzen (1992) and the like.

[0023]

[Chemical 10]

(In the formula, h represents the average number of repeating ethyleneoxy units, and 0 ≦ h ≦ 15.)

For example, a method by a transesterification reaction using dimethyl carbonate, diethyl carbonate, etc., a method by a ring closure reaction using phosgene, diphosgene, triphosgene, methyl chloroformate, ethyl chloroformate, p-nitrophenyl chloroformate, etc. Etc. The inorganic salt and the like produced by the reaction are finally removed from the polymer and provided for the polymer solid electrolyte.

The thus obtained polymer of the present invention has excellent adhesiveness to the negative electrode and positive electrode members, is dissolved in an ether solvent such as dimethoxyethane or tetrahydrofuran,
A thin film can be easily formed by drying after coating.

Among the organic solid electrolytes of the present invention, in particular, a solid electrolyte composed of an oligoethyleneoxypolyphosphazene having an allyl group or a mixture thereof and an electrolyte salt increases the mechanical strength of the electrolyte membrane by crosslinking. It is possible to The cross-linking can be carried out by a usual method, that is, a method by heating, a method by irradiating with ultraviolet rays or the like. Furthermore, it is also possible to add a solvent and produce a solid electrolyte membrane. Examples of the solvent include dimethoxyethane, ethoxymethoxyethane, diethoxyethane, dimethoxypropane, alkoxy polyalkylene ether,
Linear or cyclic ethers such as dioxane, 1,3-dioxolane, tetrahydrofuran, methyltetrahydrofuran, methoxytetrahydrofuran, ethyl acetate, γ-butyrolactone, γ-valerolactone, δ-valerolactone, diethyl carbonate, ethylene carbonate,
Propylene carbonate, linear or cyclic esters such as butylene carbonate, acetonitrile, nitriles such as methoxypropionitrile, methylpyrrolidone, cyclic amides such as cyclohexylpyrrolidone, sulfolanes, or phosphoric acid esters, or a mixture thereof. Can be used.

The electrolyte salt used in the battery using the oligoethyleneoxypolyphosphazene having a cyclic carbonate group of the present invention is not particularly limited, but if the cation is at least Li ⁺ , Na ⁺ , K ⁺ , Cs ⁺ , Ag. ^Containing one kind of ⁺ and the anion is BF ₄ ⁻ , AlCl ₄ ⁻ , PF ₆ ⁻ , As
_{^{F 6 -, ClO 4 -,}} CF 3 SO 3 -, Cl -, Br -, I -, SC
N ^- one or more electrolyte salts selected from the group of, for example,
LiBF ₄ , LiAlCl ₄ , LiPF ₆ , LiAsF ₆ , LiCl
O ₄ , LiCF ₃ SO ₃ , LiF, LiCl, LiBr, LiI,
LiSCN, NaBr, NaI, NaSCN, KI, NaSC
N, AgNO _{3 and the} like can be preferably used. Li
ClO ₄ , LiCF ₃ SO ₃ , LiBF _{4 and the} like are particularly preferable.

As the positive electrode active material, transition metals, chalcogens, metal oxides and those doped with a small amount of alkali metal ions, which are largely different in ionization potential from alkali metals, are suitable. Examples of the transition metal include Ni, Sn, Co and Fe, but Sn is most preferable. As chalcogens, CuS, FeS ₂ , Fe
Se ₂ , TiS ₂ , TiSe ₂ , VS ₂ , VSe ₂ , MoS ₂ , Mo
Se _{2 and the} like are preferable. As the metal oxide, Mn
O ₂ , CoO ₂ , V ₂ O ₅ , MoO ₃ , WO _{3 and the} like are suitable.

On the other hand, as the negative electrode active material, in addition to alkali metals such as lithium, sodium and potassium, those A
Examples thereof include alkali metal doping materials for l, Pb, Sn alloys, graphite, polyacetylene and the like.

The solid electrolyte battery of the present invention can be constructed by forming the positive electrode and the negative electrode of these materials into, for example, a thin plate shape, and adhering them to each other with the above-mentioned solid polymer electrolyte.

[0032]

The present invention will be described in detail below with reference to examples, but the invention is not limited to the examples.

Example 1 Hexachlorocyclotriphosphonitrile was placed in a polymerization tube, connected to a vacuum line, heated and melted, cooled and solidified, and
After deaeration was repeated several times, the tube was sealed under reduced pressure, and polymerization was carried out at 250 ° C. for about 8 hours. Unreacted hexachlorocyclotriphosphonitrile was removed by sublimation under reduced pressure to obtain a white rubbery dichlorophosphonitrile polymer. 0.25 unit mol of this dichlorophosphonitrile polymer was dissolved in about 500 ml of dioxane.

On the other hand, [ethylene glycol mono (2,2-dimethyl-1,3-dioxan-4-
(Ilmethyl) ether] 0.35 mol and methoxyethanol
0.35 mol was dissolved in 500 ml of tetrahydrofuran, and a hexane solution containing 0.60 mol of n-butyllithium was added dropwise thereto at 10 ° C or lower for 30 minutes. The dioxane solution of the dichlorophosphonitrile polymer prepared above was added dropwise to this alcoholate solution at 10 ° C. or lower for about 15 minutes, and then the reaction solution was heated and refluxed for 5 hours. After completion of the reaction, the reaction solvent was distilled off under reduced pressure, poured into water and neutralized with dilute hydrochloric acid. This polymer aqueous solution was dialyzed against pure water using a cellophane membrane to purify it by desalting and removing low molecular weight impurities.
Obtained 0.5 g.

[0035]

[Chemical 11]

0.20 unit mol of the polymer obtained above was dissolved in 300 ml of tetrahydrofuran, and 30 ml of 0.1N hydrochloric acid was added.
0 ml was added and reacted at 60 ° C. for about 2 hours. After neutralizing with an aqueous sodium hydroxide solution, tetrahydrofuran was distilled off under reduced pressure. The polymer aqueous solution was dialyzed against pure water using a cellophane membrane to purify it by desalting and removing low molecular weight impurities to obtain 48.5 g of a slightly yellow rubbery substance.

To 0.19 unit mol of the diol derivative obtained above, 1.90 mol of diethyl carbonate and 0.02 mol of potassium carbonate were added and reacted under reflux for 5 hours. After the reaction
The mixture was poured into ether to precipitate a polymer. Further, reprecipitation was repeated to purify the polymer, and 48.6 g of a rubber-like material was obtained.

The results of various analyzes of this polymer are as follows. In the IR spectrum, absorption of the carbonyl group of the cyclic carbonate group was observed at 1780 cm ^-1 . The result of elemental analysis is the theoretical value (%) calculated from the theoretical structural formula [Chemical formula 12].
For C: 38.44, H: 5.74, N: 4.98, P: 11.01,
The analytical values were C: 38.27, H: 5.93, N: 4.81, P: 11.29, which were in good agreement.

As a result of GFC analysis of this polymer shown in FIG. 1, the weight average molecular weight was 137 × 10 ⁴ , and Mw / Mn was 11.3. From the above results, it was confirmed that the target product was obtained.

[0040]

[Chemical 12]

Example 2 HO (CH ₂ CH ₂ O) k R has an average k value of about 7 and R is M
The reaction was carried out in the same manner as in Example 1 using an alcohol of e (methyl) and an alcohol having an average value of h of [Chemical Formula 13] of about 7, and after purification, 48.6 g of a rubber-like material was obtained. The results of various analyzes of this polymer are as follows, and absorption of the carbonyl group of the cyclic carbonate group was observed at 1780 cm ^-1 in the IR spectrum.

[0042]

[Chemical 13]

On the other hand, in ¹ H-NMR, 3.3 (-CH ₃ ),
_{3.4~3.8 (-CH 2 O -),} 4.0~4.3 (POCH 2 -),
_{4.4~4.5 (-CHC H 2 O -)} , 4.85ppm (-C H CH 2
O-), and ³¹ P-NMR showed a peak based on polyphosphonitrile at -5.2 ppm (vs 85% phosphoric acid), and the active chlorine concentration was 0.01% or less. On the other hand, the results of elemental analysis are theoretical values (%) C calculated from the theoretical structural formula [Chemical formula 14] C:
With respect to 48.94, H: 7.97, N: 1.73, P: 3.82, the analytical values were C: 48.67, H: 8.12, N: 1.88, P: 3.86, which were in good agreement. As a result of GFC analysis of this polymer shown in FIG. 2, the weight average molecular weight was 161 × 10 4 and the Mw / Mn was 11.
It was 1. From the above results, it was confirmed that the target product was obtained.

[0044]

[Chemical 14]

Examples 3 to 13 Table 1 shows the reaction conditions and the analysis results of the polymers synthesized in the same manner as in Example 1.

[0046]

[Table 1]

Example 14 Table 2 shows the results obtained by dissolving lithium salts in the polymers obtained in Examples 1 to 13 and measuring the AC conductivity by the complex impedance method at 30 ° C.

[0048]

[Table 2]

Example 15 100 parts of oligoethyleneoxypolyphosphazene having a cyclic carbonate group and an allyl group obtained in Example 13 was dissolved in 10 parts of lithium perchlorate by ultrasonic treatment at 40 ° C. or lower to dissolve an electrolyte. Got This electrolyte is transparent ITO
It was sandwiched between electrodes and irradiated with light from a high-pressure mercury lamp of 400 W to cause a cross-linking reaction of polyphosphazene to form an electrolyte membrane having a cross-linked structure. The value of AC conductivity by the complex impedance method was 2.8 × 10 ^-4 S / cm (30 ° C).

Example 16 Oligoethyleneoxypolyphosphazene 40 having a cyclic carbonate group and an allyl group synthesized in Example 13
60 parts of propylene carbonate and 10 parts of lithium perchlorate were sonicated at 40 ° C. or lower to obtain an electrolyte. Insert this electrolyte between transparent ITO electrodes,
The polyphosphazene was cross-linked by irradiating it with light from a 400 W high-pressure mercury lamp to form an electrolyte membrane having a cross-linked structure. The value of AC conductivity by the complex impedance method is
The ionic conductivity was 3.0 × 10 ⁻³ S / cm (30 ° C.), which was an order of magnitude higher than that of an electrolyte containing no propylene carbonate.

Example 17 To 50 parts of oligoethyleneoxypolyphosphazene having a cyclic carbonate group obtained in Example 2, 40 parts of oligoethyleneoxypolyphosphazene having a methyl group represented by the following formula (VII) and LiBF ₄ Ten parts were ultrasonically treated at 40 ° C. or lower to dissolve them to obtain an electrolyte. AC conductivity value of this electrolyte by the complex impedance method is 2.9 × 10 ^-4 S / cm
(30 ° C).

[0052]

[Chemical 15]

Example 18 As a specific example of the battery according to the present invention, a sheet type thin film battery as shown in FIG. 3 was produced. The external dimensions are adapted to a business card size of 5.5 cm x 9 cm, and the thickness is about 0.1 mm.

First, ₂ parts of amorphous V ₂ O ₅ obtained by the ultra-quenching method were used.
% Aqueous solution, and 6.66 g is evenly applied to the central portion 36 cm ² of a 5.5 cm × 9 cm, 20 μm-thick stainless steel plate [Shin Nippon Steel Corporation]. This product was dried at 80 to 100 ° C for about 1 hour to form a film, and then vacuum dried at 220 ° C for 5 hours to obtain a positive electrode member. A dimethoxyethane solution of a polymer solid electrolyte based on polyphosphazene having a cyclic carbonate group described in Examples 2 and 14 is applied onto this member, and dimethoxyethane is removed to form an electrolyte coating.

On the other hand, in an argon atmosphere, 5.5 cm × 9 cm, thickness 20 with a polyolefin sealing material attached on the periphery.
A 30-μm-thick lithium foil is pressure-bonded to the central portion 36 cm ² of a μm-stainless steel plate to separately prepare a negative electrode member. The bipolar members were thermocompression bonded under vacuum to produce a sheet battery. The open circuit electromotive voltage of this battery is 3.90V, 1.0mA at 30 ℃.
The result of the constant current discharge was as shown in FIG. 4, and the discharge capacity density until the voltage dropped to 2 V was 170 Ah / kg with respect to the positive electrode active material. Further, FIG. 5 shows the situation of up to 10 cycles when the charge / discharge repeated test of the battery was performed. Curve portions a and a'represent a rest period after charging, b a discharging state, c a rest period after discharging, and d a charging state. The charge / discharge efficiency of the battery was 99% or more, and it was confirmed that the battery system including the electrolyte was a secondary battery having good charge / discharge characteristics.

[0056]

As described above, the oligoethyleneoxypolyphosphazene having a novel cyclic carbonate group of the present invention has a dramatically improved ionic conductivity as compared with the conventional one by dissolving a salt, It is a polymer solid electrolyte capable of passing a current that can be put to practical use.

Accordingly, the oligoethyleneoxypolyphosphazene having a cyclic carbonate group of the present invention and a mixture thereof are used as polymer solid electrolytes for electrochemical reactions such as all-solid-state primary and secondary batteries, solid-state display devices, sensors, and capacitors. It can be applied to a wide range of fields such as electricity, electronics industry, chemical industry, and medical field as an electrolyte for devices.

[Brief description of drawings]

FIG. 1 is a diagram showing the results of GFC analysis in Example 1.

FIG. 2 is a diagram showing the results of GFC analysis in Example 2.

FIG. 3 is a schematic cross-sectional view of a specific example of the battery of the present invention.

FIG. 4 is a diagram showing the results of constant current discharge of the battery of Example 18 at 30 ° C. and 0.5 mA.

5 is a diagram showing the results of a charge / discharge test of the battery of Example 18. FIG.

[Explanation of symbols]

1 …… V ₂ O ₅ membrane 2 …… Metallic lithium 3 …… Organic solid electrolyte membrane 4 …… Stainless steel foil 5 …… Sealant

Claims (3)

[Claims] 1. An oligoethyleneoxypolyphosphazene having a cyclic carbonate group on the side chain substituent represented by formula (I). [Chemical 1] [In the formula, X and Y are the same or different and each represents a group (A) or a group (B). [Chemical 2] _{-O (CH 2 CH 2 O)} kR (B) R is a methyl group, an ethyl group, a propyl group, or an allyl group, these may be different from one in the same. h, and
k represents the average number of repeating ethyleneoxy units, and 0 ≦ h ≦ 15 and 0 ≦ k ≦ 15, respectively. m is 3 to 200
Indicates an integer of 000. However, in at least one repeating unit among the m repeating units, one of X and Y is a group (A) and the other is a group (B). ] 2. A polyphosphonitrile chloride represented by the general formula (II) is reacted with a compound of the general formula (III) and a compound of the general formula (IV) to once obtain a substitution reaction product, and then side chain substitution is carried out. The method for producing a polyphosphazene according to claim 1, wherein the acetonide group on the group is hydrolyzed to form a diol derivative, and then a ring-closing reaction is performed to introduce a carbonate group. [Chemical 3] (In the formula, m is an integer of 3 to 200,000.) MO (CH ₂ CH ₂ O) kR (III) (In the formula, k represents the average number of repeating ethyleneoxy units, and 0 ≦ k ≦ 15. Yes, M represents an alkali metal.) (In the formula, h represents the average number of repeating ethyleneoxy units, and 0 ≦ h ≦ 15. M represents an alkali metal.) 3. A battery using the polyphosphazene according to claim 1.