JP3227787B2 - Ion conductive solid electrolyte - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a primary battery, a secondary battery,
The present invention relates to an ion-conductive solid electrolyte that can be used as an electrolyte for an electrochromic display element, a large-capacity capacitor, and the like.

[0002]

2. Description of the Related Art Liquid electrolytes have been used as electrolytes for primary batteries, secondary batteries, electrochromic display devices, large-capacity capacitors, and the like. However, the liquid electrolyte has a problem of long-term reliability because the liquid electrolyte easily leaks to the outside of the component and elution of the electrode material. On the other hand, the solid electrolyte does not have such a problem, and the components of each device can be simplified, and furthermore, there is an advantage that the weight and size of the components can be reduced by thinning. Since these features meet the requirements for various components that are small, light, and highly reliable with the development of electronics, their development and research is being actively conducted.

As the solid electrolyte material, inorganic substances such as β-alumina, silver oxide, rubidium, lithium iodide and the like have hitherto been known. However, it is often difficult to form and form an inorganic film into an arbitrary shape, and it is generally expensive, so that there are many practical problems.

On the other hand, polymer materials (polymers) have the advantage that a uniform thin film can be easily processed into an arbitrary shape. Therefore, solid electrolytes using various polymers have been proposed. That is, as a base polymer such as polyethylene oxide, polypropylene oxide, polyethyleneimine, polyepichlorohydrin, Li, Na
Solid electrolyte compositions comprising a combination with an inorganic salt such as described above and batteries using such compositions have already been disclosed (for example, JP-A-55-98480 and JP-A-58-108).
No. 667, No. 58-188062, No. 58-1880
No. 63 and U.S. Pat. Nos. 4,576,882). However, compositions of these polymers and inorganic salts have insufficient ionic conductivity for practical use, and improvements have been required.

[0005] For example, Japanese Patent Application Laid-Open No. 58-82477 discloses a solid electrolyte in which a composition comprising polyethylene oxide, an alkali metal salt and a polymer capable of forming a network has a network structure. However, since the polyethylene oxide used here has a high molecular weight and easily forms a crystalline complex with an alkali metal salt, the ion conductivity is insufficient. Also disclosed is an ion-conductive solid electrolyte obtained by curing a composition comprising an acryloyl-modified polyalkylene oxide and an inorganic salt, or a composition obtained by further adding a polyethylene alkylene glycol or an organic solvent (JP-A-63-94501). Bulletin, 63-94
563 and 63-135377.

Further, an ionic conductor mainly comprising a fluorine-containing polymer such as polyvinylidene fluoride and a copolymer thereof and an inorganic salt has been known (Japanese Patent Application Laid-Open No. 59-14960).
No. 1, JP-A-60-31554).

[0007] In addition, high molecular weight polyethylene oxide
A method of adding a crown ether is also known (J.
Electrochem. Soc. , Vol. 13
7, 3830 (1990)). These solid electrolytes have a problem that the cation transport number, which is an important property as well as the ionic conductivity, is low. That is, it is considered that the movement of both the cation and the anion caused by the dissociation of the inorganic salt contributes to the ionic conductivity. However, in the case of application to a battery or the like, the movement of the anion has a drawback of lowering the stability of the electrolyte. Therefore, it is desirable that the proportion of the ionic conductivity contributed by the cation, that is, the cation transport number be as high as possible.

As a method for improving the cation transport number, for example, JP-A-61-47713 discloses a solid electrolyte using a copolymer of lithium methacrylate and methyl ether oligoethylene oxide methacrylate. I have. However, this solid electrolyte has a drawback that although the cation transport number is high, the ionic conductivity is low.

[0009]

SUMMARY OF THE INVENTION The present invention provides a polymer ion conductive solid electrolyte having excellent ion conductivity and cation transport number.

[0010]

[Technical Solution to Solve the Problem]

Embedded image (Wherein, R ₁ and R ₂ represent hydrogen or a lower alkyl group, and n represents an integer of 1 to 30). A composition comprising an acryloyl-modified polyalkylene oxide, an inorganic salt and a crown ether compound having a structure represented by the following formula: The present invention relates to an ion-conductive solid electrolyte obtained by curing an object.

Specific examples of the acryloyl-modified polyalkylene oxide in the present invention include, for example, triethylene glycol monoacrylate, tetraethylene glycol monoacrylate, polyethylene glycol monoacrylate, methoxytetraethylene glycol monoacrylate, phenoxytetraethylene glycol monoacrylate, Methoxy polyethylene glycol monoacrylate, triethylene glycol monomethacrylate, polyethylene glycol monomethacrylate, methoxy polyethylene glycol monomethacrylate, polyethylene glycol cinnamate, polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, triethylene glycol trimethylolpropane triacryle DOO, and ethylene glycol structure in the above compounds can be used as the compound was changed to propylene glycol structure. The molecular weight of the acryloyl-modified polyalkylene oxide is not particularly limited,
Usually, the molecular weight is from 200 to 10,000, preferably from 250 to
3000's are used. The acryloyl-modified polyalkylene oxide can be used in combination of two or more.

Specific examples of the inorganic salt in the present invention include:
LiClO ₄ , LiI, LiSCN, LiBF ₄ , Li
AsF ₆ , LiCF ₃ SO ₃ , LiPF ₆ , Nal, N
aClO ₄ , NaSCN, NaBr, KI, CsSC
An inorganic salt containing one kind of an alkali metal or an alkaline earth metal such as N, AgNO ₃ , CuCl ₂ , and Mg (ClO ₄ ) ₂ can be used. Also, an ammonium salt containing a quaternary nitrogen, that is, (CH ₃ ) ₄ NSCN,
(CH ₃ ) ₄ , NCLO ₄ , (CH ₃ ) ₄ NCl, (C
H ₃ ) ₄ NBr, (CH ₃ ) ₄ NBF ₄ , (C ₂ H ₅ )
₄ NSCN, (C ₂ H ₅ ) ₄ NCLO ₄ , (C ₂ H ₅ )
₄ NCl, (C ₂ H ₅ ) ₄ NBr, (C ₂ H ₅ ) ₄ NC
F ₃ SO ₃ , (C ₆ H ₅ ) (CH ₃ ) ₃ NCl, (C ₆
H ₅ ) (CH ₃ ) ₃ NBr, (C ₆ H ₅ ) (C ₂ H ₅ )
Inorganic salts such as ₃ NBr and (C ₆ H ₅ ) (C ₂ H ₅ ) ₃ NBF ₄ can be used.

The content of the inorganic salt is (inorganic salt / EO) × 100 (mol%) based on the alkylene oxide unit (hereinafter abbreviated as EO) of the acryloyl-modified polyalkylene oxide and polyalkylene glycol. Preferably 0.05 to 50 mol%, more preferably 0.1 to 50 mol%.
The amount is 1 to 30 mol%. If the content of the inorganic salt is too large, the excess inorganic salt does not dissociate, but simply mixes, and consequently the ionic conductivity decreases. Also, when the content is too small, the number of dissociated ions decreases, and the ionic conductivity decreases. Further, two or more of the above inorganic salts can be used in combination.

Specific examples of the crown ether in the present invention include 1,4,7,10-tetraoxacyclododecane, 1,4,7,10,13-pentaoxacyclopentadecane (hereinafter abbreviated as 15Cr5), , 4,7,1
0,13,16-hexaoxacyclooctadecane,
2,3,11,12-dibenzo-1,4,7,10,1
3,16-hexaoxacyclooctadeca-2,11-
Dienes, 2,3,11,12-dicyclohexyl-1,
For example, 4,7,10,13,16-hexaoxacyclooctadecane can be used.

In the present invention, a polyalkylene glycol or an organic solvent may be added in addition to the above-mentioned three components of the acryloyl-modified polyalkylene oxide, inorganic salt and crown ether. As the polyalkylene glycol, those having a molecular weight of 2000 or less are preferable,
Examples thereof include tetraethylene glycol, hexaethylene glycol, octaethylene glycol, and their mono- or dimethyl ethers, and compounds in which the ethylene glycol structure of the above compound is changed to a propylene glycol structure.

Specific examples of the organic solvent include propylene carbonate, γ-butyrolactone, ethylene carbonate, diethyl carbonate, tetrahydrofuran, acetonitrile, dimethoxyethane, dimethylsulfoxide, dioxolan, sulfolane and the like. The content of the polyalkylene glycol or the organic solvent is preferably 500% by weight or less, more preferably 4% by weight, based on the acryloyl-modified alkylene oxide.
00% by weight or less. If the content of the polyalkylene glycol or the organic solvent is too large, the mechanical properties of the cured product are reduced, which is not practically preferable. Two or more polyalkylene glycols can be used in combination.

The ion conductive solid electrolyte of the present invention is prepared by adding a polyalkylene glycol or an organic solvent.
As the ionic conductivity is improved by plasticization,
The interaction between the acryloyl-modified polyalkylene oxide, the inorganic salt and the crown ether and the polyalkylene glycol or the organic solvent has an effect of improving ion conductivity and cation transport number.

As a method for curing the composition of the present invention comprising the above-mentioned components, a method of heating or a method of irradiating active rays such as ultraviolet rays, visible rays and electron beams is preferably used.

In the case of the above-mentioned heating method, if necessary, a peroxide such as benzoyl peroxide, methyl ethyl ketone peroxide, diisopropyl peroxycarbonate or the like is preferably added to the composition if necessary.

In the case where the above-mentioned method of irradiating with actinic light is used, if necessary, benzoin, 2-methylbenzoin, trimethylsilylbenzophenone, 4-methoxybenzophenone, benzoin methyl ether, and It is preferable to add acetophenone, anthraquinone, 2,2-dimethoxy-2-phenylacetophenone and the like.

As a method of curing and thinning the above composition, a metal such as aluminum or stainless steel or a substrate such as glass is coated with the above composition by, for example, roller coating, doctor blade, bar coder, sicle screen, or Using a means such as spin coating to apply to make a uniform thickness to form a coating film,
Examples of the method include heating the coating film or irradiating the coating film with actinic rays to cure and thin the coating film.

[0022]

The ionic conductive solid electrolyte of the present invention has excellent ionic conductivity and cation transport number, and can be suitably used for primary batteries, secondary batteries, electrochromic display devices, large capacity capacitors, and the like. .

[0023]

Embodiments of the present invention will be described below. The ionic conductivity in the examples was measured by an alternating current method (10 KHz, 10 m
V) was measured in the range of 20 to 60 ° C. In addition, the cation transport number is calculated by the electromotive force method and Isothermal t.
transient ionic current (I
(TIC) method. In the electromotive force method, a concentration battery in which the concentration (X) of the inorganic salt was changed was prepared, the electromotive force of the battery was measured, the anion transport number was calculated from this value, and the cation transport number was further determined. ITI
In the method C, the cation mobility was determined by a cell using a stainless steel electrode, and the anion mobility was determined by a cell using a lithium electrode, and the transport number was calculated from them.

Example 1 Polyethylene oxide (EO chain) in the side chain as a monomer
A mixture of 1.35 g of methoxypolyethylene glycol methacrylate (M-90G manufactured by Shin-Nakamura Chemical Co., Ltd.) and 0.45 g of polyethylene glycol dimethacrylate (9G manufactured by Shin-Nakamura Chemical Co., Ltd.) with propylene carbonate of LiBF ₄ Solution (LiBF ₄ concentration 1.0m
ol / dm ³ ) and a propylene carbonate solution of 15Cr5 as a crown ether (15Cr5
5 concentration 0.1 mol / dm ³ ) 0.067 g was added.
Next, as a photopolymerization initiator, 2,2-dimethoxy-2-
0.4 wt% of phenylacetophenone was added, and UV light was irradiated for 900 seconds with an ultraviolet lamp 6W (FL6BLB manufactured by Toshiba) to polymerize. As a result, a transparent polyethylene oxide-grafted polymethyl methacrylate composite film (thickness: 1.0 mm) was obtained. A plot of the logarithm of the ionic conductivity versus the measurement temperature is shown in FIG. In addition, Table 2 shows the cation transport numbers according to the ITIC method.

Example 2 A transparent polyethylene oxide-grafted polymethyl methacrylate composite film (1.0 mm thick) was obtained in the same manner as in Example 1 except that the concentration of the 15Cr5 propylene carbonate solution was changed to 1.0 mol / dm ^3. Was. A plot of the logarithm of the ionic conductivity versus the measurement temperature is shown in FIG. Table 1 shows the cation transport number by the electromotive force method, and Table 2 shows the cation transport number by the ITCI method.

Comparative Example A transparent polyethylene oxide-grafted poly (methyl methacrylate) composite film (thickness: 1.0 mm) was obtained in the same manner as in Example 1, except that 15Cr5 was not added. A plot of the logarithm of the ionic conductivity versus the measurement temperature is shown in FIG. Table 1 shows the cation transport number by the electromotive force method, and Table 2 shows the cation transport number by the ITIC method.

[0027]

[Table 1]

[Table 2]

[Brief description of the drawings]

FIG. 1 is a plot of the logarithm of ionic conductivity versus measured temperature.

Claims (1)

(57) [Claims] 1. A compound of the general formula (Wherein, R ₁ and R ₂ represent hydrogen or a lower alkyl group, and n represents an integer of 1 to 30). A composition comprising an acryloyl-modified polyalkylene oxide, an inorganic salt and a crown ether compound having a structure represented by the following formula: An ion-conductive solid electrolyte obtained by curing an object.