JPS62285954A - Solid electrolyte composed of high-molecular material - Google Patents

Abstract

PURPOSE:To provide the title electrolyte which has a short curing time and a high electrical conductivity and is storable and transparent, by curing a compsn. contg. an alkali metal salt and polyethylene glycol diacrylate. CONSTITUTION:A mixture (A) of polyethylene glycol diacrylate (a) wherein the number n of C-C-O units per molecule is 14 or above and optionally polyethylene glycol monoacrylate (b) is blended with alkali metal salts (B) of formulas I and/or II (wherein M is an alkali metal) in such a proportion that the ratio Y of the mol no. of the component B to that of the C-C-O units in the component A is 0.01<=Y<=0.07, thus obtaining a compsn. The compsn. is irradiated with electromagnetic rays (light) to cure it, thus obtaining the title electrolyte. The electrolyte is particularly suitable for use in large-dimension transmission type electrochromic element.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a polymer solid electrolyte with high electrical conductivity,
Particularly large-area transmission electrochromic elements (hereinafter referred to as
This invention relates to a transparent polymer solid electrolyte that can be used in EC devices (abbreviated as EC devices).

[Conventional technology]

As the polymer solid electrolyte, alkali metal salt or
Ammonium salt and polyethylene oxide (hereinafter P
(abbreviated as EO) (for example, li'ast
Ion Transport in 5olids,
/J/.

/979), and as the thermosetting polymer solid 7Ii solute, lithium salt/trifunctional polyethylene glycol (
(hereinafter abbreviated as JPEG). Those using aromatic diisocyanate derivatives are known.

(Polymer prepri, nts, Japan
n, J4Z, A! , 90+.

/LIE)) [Problems to be solved by the invention] When applying an alkali metal salt/PKO-based solid electrolyte to an EC device, it is first coated on one substrate (
After forming the solid electrolyte film, the EC film, i! It is necessary to stack the electrodes or to use a so-called hot melt method in which the electrode-attached substrate is pressed while being heated. However, with the former, it is difficult to increase the area, and with the latter, it is difficult to remove bubbles trapped in the electrolyte, and it cannot be used in EC elements that have poor heat resistance. There was a point. In addition, the alkali metal salt/JPK:G/aromatic diisocyanate derivative system has a low conductivity at room temperature of /O-58cm-1 or less, and also requires a long time to cure and has a short bot life. There were also problems with the production process.

[Means for solving problems]

In order to solve the above problems, the present inventors have developed an alkali metal salt and polyethylene glycol diacrylate (
A polymer electrolyte was prepared by curing a composition containing PEDA (hereinafter abbreviated as PEDA).

The electrolyte of the present invention is basically a PED expressed by formula (1).
A (PKDA in which an alkali metal salt is dissolved in an ethylene oxide part) undergoes a crosslinking reaction (a crosslinking reaction caused by electromagnetic radiation (light) irradiation) to change from a liquid state to a solid state.

PEDA.

This polymer electrolyte has a short curing time of about 10 minutes by light irradiation, and if stored in a shielded environment, curing rate can be completely suppressed, making it easier to handle than thermosetting electrolytes. It also has the advantage of being easy to store.

By the way, the ion conduction mechanism of amorphous polymer solid electrolytes is based on the free volume theory, and the temperature dependence of conductivity is (2
) is expressed by the formula. From this equation, it can be seen that the lower the glass transition point of Km solute, the higher the carrier mobility.

(Fast Ion'rransport i
n 5O1LaS, /3/, /wa7ri), r-Tl/
2-exp (Ea/ (Tg -T)) (
21 Here, σ is the ionic conductivity, Ea is the activation energy, Tg is the glass transition point of the electrolyte, and the relationship between the dielectric constant of the host polymer and the carrier density is expressed by equation (3).

n-No-eXp (-guchi/, 2tKT)
(31 Here, NO is a constant, S is the lattice diturbity of the alkali metal salt, and t is the dielectric constant of the polymer. However, since the dielectric constant of polymers is generally small, the conductivity of the solid polymer electrolyte is increased. An important issue is how to lower the glass transition point.

PEDA as the host polymer of the polymer solid electrolyte
When used alone, the larger the number n of ethylene oxide units in PEDA, the larger the crosslinking point distance after photocrosslinking, so the glass transfer rate L + (rolling input −V
In order to obtain the path rate of just kissing with ρ and f thick, it is preferable that n≧/Hiroshi.

Furthermore, by adding polyethylene glyfur monoacrylate (hereinafter abbreviated as PEMA) to P'EDA, it is possible to lower the -M glass transition point by reducing the crosslink density after photocrosslinking. It is. As the proportion of PEMA increases, the conductivity increases,
If the ratio is too large, crystallization will occur, resulting in clouding over time and a decrease in electrical conductivity. Therefore, (PEMA)
/ ((PEMA) + (PEDA))-X molar ratio to 0
．． It is preferable that 2<X<O, male.

The amount of the alkali metal salt added is expressed as the molar ratio Y of the alkali metal salt to the number of moles of ethylene oxide units in polyethylene glycol acrylate (hereinafter abbreviated as PK:A). Here, the number of moles of ethylene oxide units in PEA is the C-C-0 part of PEA (formula (
1) The weight of Part A) of PEDA in +C-C
It is the value divided by the formula quantity ≠ of −0+.

As the carrier density increases with the amount of alkali metal salt added, the conductivity increases in a small Y range, but when Y reaches a certain value, the glass transition point of the electrolyte becomes too large and the carrier mobility becomes small. The conductivity decreases because of this. As a result, the amount of added Al A'J metal salt was 0.
It is desirable that 07≦Y≦0.07.

As the alkali metal salt used in the polymer solid electrolyte of the present invention, various salts of various alkali metals can be used, among which thiocyanate and trifluoromethanesulfonic acid have high solubility in PEA and large ionic dissociation. salt,
Although it is not clear why the anion twerk formation made of polyatoms such as (MSCN, MCF3SO3, M-alkali metal) is larger than that of thermosetting polymer solid electrolytes, one reason is that the thermosetting electrolytes are cross-linked. In addition to increasing the glass transition temperature due to
It is considered that the hydrogen bond between the -H groups increases the glass transition point. Furthermore, it can be considered that a highly polar group such as a N--H group acts as a trapper for cation migration and may reduce the mobility.

Next, a method for producing the polymer electrolyte of the present invention will be described.

P
The solution was added to EA and sufficiently stirred to form a homogeneous solution, then packaged with aluminum wheels and stored in a light-shielded state. A high-pressure mercury lamp was used as a light source for photocuring.

〔Example/〕

The molecular weight is 75 each! ;J! Three types of PEDA solutions of r, 3/I<The number of C-a-O units is /≠ for each
.

94) 1c KCF3sO3 was added to give KY-0.03, and a homogeneous solution was obtained by sufficiently stirring.

After the crosslinking reaction was completed by light irradiation with a high-pressure mercury lamp for about 7 hours, the conductivity of the sample at room temperature was measured by the AC impedance method, and the results are shown in FIG. This indicates that the conductivity of the solid electrolyte increases significantly with the molecular weight of PEDA. When applied to EC devices, the conductivity is preferably IO-lo-68C or higher, so the molecular weight of PEDA is 7! ; 1 or more, that is, P
It can be seen that 13n of the C-C-0 unit in EDA is preferably /≠ or more.

[Example 2] (PEMA) / ((PEMA) + (PEDA)
) -X% Le ratio is 0, 0.2, 0.
0. B, 0. Create samples of B type with za, /, O, and make each sample Y-0,03 K KCF3S○3
was added and thoroughly stirred to obtain a homogeneous solution. The PEMA used here has a molecular weight of /≠2ge and is solid at room temperature, so when using it, KCF3SO3 is melted by heating to about 6O''C in a nitrogen atmosphere. Figure 2 shows the results of measuring the electrical conductivity of each sample at room temperature after curing by light irradiation using the AC impedance method.This shows that the larger X is, the higher the electrical conductivity is. , X2O3, 0.2≦X≦0, which is a problem for crystallization.
It is particularly desirable to

[Example 3] Three samples of X-O,t were created, and each Y-0゜0
．． 0/, 0.03, O, OK, 0.07
KCF3SO3 was added so that FIG. 3 shows the results of measuring the electrical conductivity of each sample at room temperature by an alternating current impedance method after stirring the solution sufficiently to obtain a homogeneous solution and curing it by irradiation with light. This indicates that the conductivity is maximum at approximately Y-0.03. Therefore, from the viewpoint of electrical conductivity, it is particularly desirable that 0.07≦Y≦0.07.

〔Effect of the invention〕

A solid polymer electrolyte obtained by irradiating light onto PEA in which an alkali metal salt has been dissolved has features that thermosetting electrolytes do not have, such as a short curing time and the ability to be stored. Therefore, when considering application to EC devices, for example, it is not only possible to create EC devices with good contact without causing thermal damage to the EC film, but also to improve productivity and simplify the production process. We can expect it to change.

A method for increasing the conductivity of the solid polymer electrolyte according to the present invention is to increase the number of ethylene oxide units in PEDA to increase the distance between crosslinking points after photocrosslinking, and to add an appropriate amount of PEDAK PEMA. By reducing the crosslinking density, the molar ratio Y of the alkali metal salt to the number of moles of ethylene oxide units in PEA is reduced to 0. It is particularly effective to satisfy O/≦Y≦0.07.

Further, the polymer solid electrolyte according to the present invention is, for example, typical polymer solid electrolytes such as direct PEO and 1icA'.
The electrical conductivity is about two to three orders of magnitude higher than that of the crystalline composite with 04, which was recently reported (pol, ymerPr8print
S, Japan,, l, AJ, 90II (/I
! ;)) Since the conductivity is about 7 orders of magnitude higher than that of thermosetting polymer electrolytes, the response speed will be faster when applied to EC devices.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the relationship between the molecular weight and conductivity of polyethylene glycol diacrylate in the solid polymer electrolyte prepared in Example 1, and Figure 2 shows the relationship between the molecular weight and conductivity of polyethylene glycol diacrylate in the solid polymer electrolyte prepared in Example 2. Diagram showing the relationship between material composition and electrical conductivity,
FIG. 3 is a drawing showing the relationship between the alkali metal content and conductivity of the solid polymer electrolyte prepared in Example 3. O300600900 PEDA molecular weight Figure 1 0 0.2 0.4 0.6 0.8
1[PEMA] / ([pEMAl 4-[P
EDA]) Figure 2

Claims (5)

[Claims] (1) A solid polymer electrolyte obtained by curing a composition containing an alkali metal salt and polyethylene glycol diacrylate. (2) The photocurable polymer solid electrolyte according to claim 1, wherein the number n of C-C-O units in the molecule of the polyethylene glycol diacrylate is 14≦n. (3) Claim 1 or 2, wherein the composition contains polyethylene glycol monoacrylate.
Polymer solid electrolyte described in Section 1. (4) The ratio Y of the number of moles of the alkali metal salt to the total number of moles of C-C-O units of polyethylene glycol diacrylate and polyethylene glycol monoacrylate is 0.01≦Y≦0.07. Polymer solid electrolyte according to item 3. (5) The alkali metal salt is MSCN and/or MC
The solid polymer electrolyte according to claims 1 to 4, which is F_3SO_3 (M=alkali metal).