JP2020204763A - Electrolyte composition, electrolytic sheet, electrochromic element and manufacturing method therefor - Google Patents

Abstract

To provide an electrolyte composition which allows for forming a highly transparent electrolytic layer.SOLUTION: An electrolyte composition of the present invention contains an electrolyte salt and at least one polymer selected from poly(meth)acrylates and polyvinylacetals.SELECTED DRAWING: None

Description

The present invention relates to an electrolyte composition, an electrolyte sheet, an electrochromic device, and a method for producing the same.

The transparent electrolyte layer is used in various fields including electrochromic devices. For example, an electrochromic element having at least a pair of opposing transparent electrodes and an oxidative color-developing electrochromic layer, a transparent ion conductive layer (transparent electrolyte layer), and a reducing color-developing electrochromic layer sandwiched between the transparent electrodes. It is known (Patent Document 1).

Japanese Unexamined Patent Publication No. 9-152634

However, the transparent electrolyte layer in the conventional electrochromic device has room for further improvement in transparency.

Therefore, a main object of the present invention is to provide an electrolyte composition capable of forming an electrolyte layer having excellent transparency.

One aspect of the present invention provides an electrolyte composition containing at least one polymer selected from poly (meth) acrylates and polyvinyl acetals and an electrolyte salt. The polymer may contain a poly (meth) acrylate or may contain a polyvinyl acetal.

The electrolyte composition may further contain an ionic liquid. In addition, the electrolyte composition may further contain a deep eutectic solvent. In addition, the electrolyte composition may further contain a plasticizer.

The poly (meth) acrylate is at least one selected from the group consisting of a structural unit derived from an alkyl (meth) acrylate, a structural unit derived from a urethane (meth) acrylate, and a structural unit derived from an epoxy (meth) acrylate. May contain structural units derived from alkyl (meth) acrylates.

Another aspect of the present invention provides an electrolyte sheet comprising a base material and an electrolyte layer provided on the base material, wherein the electrolyte layer is formed from the above-mentioned electrolyte composition.

The haze of the electrolyte layer may be 1% or less.

Another aspect of the present invention is an electrochromic device including an electrochromic electrode portion, an electrolyte portion, and a counter electrode portion in this order, wherein the electrolyte portion is formed from the above-mentioned electrolyte composition. A chromic element is provided.

Another aspect of the present invention is a method for manufacturing an electrochromic element including an electrochromic electrode portion, an electrolyte portion, and a counter electrode portion in this order, and between the electrochromic electrode portion and the counter electrode portion. Provided is a method for manufacturing an electrochromic element, comprising a step of forming the electrolyte portion by arranging an electrolyte layer formed from the above-mentioned electrolyte composition.

According to one aspect of the present invention, there is provided an electrolyte composition capable of forming an electrolyte layer having excellent transparency.

It is a schematic cross-sectional view which shows one Embodiment of the electrochromic element of this invention.

<Electrolyte composition>
The electrolyte composition according to one embodiment contains at least one polymer (hereinafter, also referred to as “specific polymer”) selected from poly (meth) acrylate and polyvinyl acetal, and an electrolyte salt. The electrolyte composition may contain a poly (meth) acrylate and an electrolyte salt, may contain a polyvinyl acetal and an electrolyte salt, and may contain a poly (meth) acrylate, a polyvinyl acetal and an electrolyte salt. May be good.

(Poly (meth) acrylate)
By containing the poly (meth) acrylate in the electrolyte composition, an electrolyte layer having excellent transparency can be formed. Further, the electrolyte composition tends to be able to form an electrolyte layer having excellent weather resistance and flexibility by containing a poly (meth) acrylate.

The poly (meth) acrylate contains a structural unit derived from the (meth) acrylate as a main structural unit. The poly (meth) acrylate can be obtained by polymerizing a composition containing (meth) acrylate as a main monomer component. The content of the structural unit derived from the (meth) acrylate may be 50% by mass or more, 70% by mass or more, or 90% by mass or more based on the total amount of all the structural units constituting the poly (meth) acrylate. ..

Examples of the (meth) acrylate include alkyl (meth) acrylate, urethane (meth) acrylate, and epoxy (meth) acrylate. The poly (meth) acrylate is at least one selected from the group consisting of a structural unit derived from an alkyl (meth) acrylate, a structural unit derived from a urethane (meth) acrylate, and a structural unit derived from an epoxy (meth) acrylate. May include. From the viewpoint of further improving the transparency of the electrolyte layer formed, the poly (meth) acrylate preferably contains a structural unit derived from the alkyl (meth) acrylate.

Examples of the alkyl (meth) acrylate include compounds represented by the following general formula (1). The poly (meth) acrylate may be a homopolymer of these monomers, or may be a copolymer containing a structural unit derived from these monomers.
H ₂ C = C (R ¹⁹ ) -COOR ²⁰ (1)

In the general formula (1), R ¹⁹ represents a hydrogen atom or a methyl group, and R ²⁰ represents an alkyl group having 1 to 10 carbon atoms. The alkyl group may be linear or branched. From the viewpoint of the transparency of the electrolyte layer formed further improved, R ²⁰ is preferably an alkyl group having 1 to 5 carbon atoms, more preferably an alkyl group having 1 to 3 carbon atoms.

The weight average molecular weight of the poly (meth) acrylate may be 10,000 or more, 30,000 or more or 50,000 or more, and may be 5 million or less, 3 million or less or 1 million or less. As used herein, the weight average molecular weight is a standard polystyrene conversion value determined by gel permeation chromatography.

(Polyvinyl acetal)
By containing polyvinyl acetal in the electrolyte composition, it is possible to form an electrolyte layer having excellent transparency. Polyvinyl acetal usually has an acetal unit represented by the following formula (I) and a hydroxyl group unit represented by the following formula (II). The polyvinyl acetal may further have a vinyl acetate unit represented by the following formula (III). R in the formula (I) represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. A plurality of Rs in the same molecule may be the same or different. R may be a hydrogen atom, a methyl group or a propyl group.

The content of the acetal unit may be 60% by mass or more, or 90% by mass or less, based on the total amount of the acetal unit, the hydroxyl group unit, and the vinyl acetate unit. The content of the hydroxyl group unit may be 10% by mass or more, or 30% by mass or less, based on the total amount of the acetal unit, the hydroxyl group unit, and the vinyl acetate unit.

Examples of the polyvinyl acetal include polyvinyl butyral and polyvinyl formal. The polyvinyl acetal preferably contains polyvinyl butyral from the viewpoint of being able to form an electrolyte layer having better transparency.

The weight average molecular weight of polyvinyl acetal may be 10,000 or more, 25,000 or more, 50,000 or more, 70,000 or more, 80,000 or more, or 95,000 or more, and may be 200,000 or less, 150,000 or less, 120,000 or less, or 105,000 or less.

The content of the specific polymer is 20 based on the total amount of the electrolyte composition (excluding the dispersion medium described later, in other words, the total amount of the electrolyte layer; the same applies hereinafter) from the viewpoint of further improving the transparency of the formed electrolyte layer. It may be mass% or more, 30 mass% or more, 40 mass% or more, or 50 mass% or more. From the same viewpoint, the content of the specific polymer may be 95% by mass or less, 85% by mass or less, 75% by mass or less, or 65% by mass or less based on the total amount of the electrolyte composition. When the particular polymer is a poly (meth) acrylate, the content of the poly (meth) acrylate may be in the above range. When the specific polymer is polyvinyl acetal, the content of polyvinyl acetal may be in the above range. If the particular polymer contains both poly (meth) acrylate and polyvinyl acetal, the total content of poly (meth) acrylate and polyvinyl acetal may be in the range described above.

(Electrolyte salt)
The electrolyte salt may be at least one selected from the group consisting of potassium salt, lithium salt, sodium salt, calcium salt, and magnesium salt.

Anionic component of the electrolyte salt, a halide ion ^{(I -, Cl -, Br} - , _{^{etc.), SCN -, BF 4 -}} , BF 3 (CF 3) -, BF 3 (C 2 F 5) -, PF 6 - _{^{, AsF6 -, ClO 4 -,}} SbF 6 -, N (SO 2 F) 2 -, N (SO 2 CF 3) 2 -, N (SO 2 C 2 F 5) 2 -, B (C 6 H 5) _{^{4 -, B (O 2 C}} 2 H 4) 2 -, C (SO 2 F) 3 -, C (SO 2 CF 3) 3 -, CF 3 COO -, CF 3 SO 2 O -, C 6 F 5 It may be SO ₂ O ⁻ , B (O ₂ C ₂ O ₂ ) ₂ ^−, or the like. The anion component of the electrolyte salt is preferably an anion component represented by the formula (2) described later, such as N (SO ₂ F) ₂ ⁻ , N (SO ₂ CF ₃ ) ₂ ⁻ , CF ₃ SO ₂ O ⁻ . PF ₆ ⁻ , BF ₄ ⁻ , B (O ₂ C ₂ O ₂ ) ₂ ⁻ , or ClO ₄ ⁻ .

The content of the electrolyte salt may be 1% by mass or more, 2% by mass or more, 3% by mass or more, or 4% by mass or more based on the total amount of the electrolyte composition. The content of the electrolyte salt may be 40% by mass or less or 20% by mass or less based on the total amount of the electrolyte composition.

(Ionic liquid)
The electrolyte composition may further contain an ionic liquid. By containing the ionic liquid, the electrolyte composition tends to improve the ionic conductivity of the formed electrolyte layer, and tends to increase the response speed of the electrochromic element provided with the electrolyte layer. is there.

The ionic liquid may contain the following anionic and cationic components. The ionic liquid in the present specification is a substance that is liquid at −20 ° C. or higher.

Anion component of the ionic liquid, the anion of halogen ^{(Cl -, Br -, I} - , _{^{etc.), BF 4 -, N (}} SO 2 F) 2 - inorganic anions such ^{_{as, B (C 6 H 5)}} 4 -, CH ₃ SO ₂ O ⁻ , CF ₃ SO ₂ O ⁻ , N (SO ₂ C ₄ F ₉ ) ₂ ⁻ , N (SO ₂ CF ₃ ) ₂ ⁻ , N (SO ₂ C ₂ F ₅ ) ₂ ^{− and} other organic anions And so on. The anionic component of the ionic liquid preferably contains at least one of the anionic components represented by the following formula (2).
N (SO ₂ C _m F _{2 m + 1} ) (SO ₂ C _n F _{2n + 1} ) ⁻ (2)

In equation (2), m and n each independently represent an integer of 0 to 5. m and n may be the same or different from each other, and are preferably the same as each other.

The anion components represented by the formula (2) are, for example, N (SO ₂ C ₄ F ₉ ) ₂ ⁻ , N (SO ₂ F) ₂ ⁻ , N (SO ₂ CF ₃ ) ₂ ⁻ and N (SO ₂ C). ₂ F _{5) 2} ^- a. The anionic component of the ionic liquid has a relatively low viscosity, and from the viewpoint of further improving the ionic conductivity, N (SO ₂ C ₄ F ₉ ) ₂ ⁻ , CF ₃ SO ₂ O ⁻ , N (SO ₂ F) ₂ ⁻ , It preferably contains at least one selected from the group consisting of N (SO ₂ CF ₃ ) ₂ ⁻ and N (SO ₂ C ₂ F ₅ ) ₂ ⁻ .

The cation component of the ionic liquid may be at least one selected from the group consisting of a chain quaternary onium cation, a piperidinium cation, a pyroridinium cation, a pyridinium cation, and an imidazolium cation.

The chain quaternary onium cation is, for example, a compound represented by the following formula (3).

In the formula (3), R ^{1 to} R ⁴ are independently chain alkyl groups having 1 to 20 carbon atoms or chain alkoxyalkyl groups represented by R ⁰ −O− (CH ₂ ) _n −. (R ⁰ represents a methyl group or an ethyl group, n represents an integer of 1 to 4), and X represents a nitrogen atom or a phosphorus atom. The alkyl group represented by R ^{1 to} R ⁴ has preferably 1 to 20 carbon atoms, more preferably 1 to 10 carbon atoms, and further preferably 1 to 5 carbon atoms.

The piperidinium cation is, for example, a nitrogen-containing six-membered cyclic compound represented by the following formula (4).

In formula (4), R ⁵ and R ⁶ are independently alkyl groups having 1 to 20 carbon atoms or alkoxyalkyl groups represented by R ⁰ −O− (CH ₂ ) _n − (R ⁰ is Represents a methyl group or an ethyl group, and n represents an integer of 1 to 4). The alkyl group represented by R ⁵ and R ⁶ has preferably 1 to 20 carbon atoms, more preferably 1 to 10 carbon atoms, and further preferably 1 to 5 carbon atoms.

The pyrrolidinium cation is, for example, a five-membered cyclic compound represented by the following formula (5).

In formula (5), R ⁷ and R ⁸ are independently alkyl groups having 1 to 20 carbon atoms or alkoxyalkyl groups represented by R ⁰ −O− (CH ₂ ) _n − (R ⁰ is Represents a methyl group or an ethyl group, and n represents an integer of 1 to 4). The alkyl group represented by R ⁷ and R ⁸ has preferably 1 to 20 carbon atoms, more preferably 1 to 10 carbon atoms, and further preferably 1 to 5 carbon atoms.

The pyridinium cation is, for example, a compound represented by the following formula (6).

In formula (6), R ^{9 to} R ¹³ are independently alkyl groups having 1 to 20 carbon atoms and alkoxyalkyl groups represented by R ^0- O- (CH ₂ ) _n- (R ⁰ is methyl). Represents a group or ethyl group, where n represents an integer of 1 to 4), or represents a hydrogen atom. The alkyl group represented by R ^{9 to} R ¹³ has preferably 1 to 20 carbon atoms, more preferably 1 to 10 carbon atoms, and further preferably 1 to 5 carbon atoms.

The imidazolium cation is, for example, a compound represented by the following formula (7).

In formula (7), R ^{14 to} R ¹⁸ are independently alkyl groups having 1 to 20 carbon atoms and alkoxyalkyl groups represented by R ^0- O- (CH ₂ ) _n- (R ⁰ is methyl). Represents a group or ethyl group, where n represents an integer of 1 to 4), or represents a hydrogen atom. The alkyl group represented by R ^{14 to} R ¹⁸ has preferably 1 to 20 carbon atoms, more preferably 1 to 10 carbon atoms, and further preferably 1 to 5 carbon atoms.

As the ionic liquid, a complex of at least one salt selected from the group consisting of lithium salt, sodium salt, magnesium salt and calcium salt and glyme can be used. In addition, in this specification, these complexes may be referred to as "grime complex". The grime complex has flame-retardant and volatile properties and has a wide potential window.

Anion salts are halide ions ^{(I -, Cl -, Br} - , _{^{etc.), SCN -, BF 4 -}} , BF 3 (CF 3) -, BF 3 (C 2 F 5) -, BF 3 (C 3 _{^{F 7) -, BF 3 (}} C 4 F 9) -, PF 6 -, ClO 4 -, SbF 6 -, [FSI] - ( bis (fluorosulfonyl) imide anion), [TFSI] ^- (bis (trifluoromethane Sulfonyl) imide anion), N (C ₂ F ₅ SO ₂ ) ₂ ⁻ , BPh ₄ ⁻ , B (C ₂ H ₄ O ₂ ) ₂ ⁻ , [f3C] ⁻ (Tris (fluorosulfonyl) carbanion), C ( CF ₃ SO ₂ ) ₃ ⁻ , CF ₃ COO ⁻ , CF ₃ SO ₂ O ⁻ , C ₆ F ₅ SO ₂ O ⁻ , [BOB] ⁻ (bisoxalate boronion), R ²¹ COO ⁻ (R ²¹ is , An alkyl group having 1 to 4 carbon atoms, a phenyl group, or a naphthyl group) and the like. Among these, the salt anion is preferably at least one selected from the group consisting of PF ₆ ⁻ , BF ₄ ⁻ , [FSI] ⁻ , [TFSI] ⁻ , [BOB] ⁻ , and ClO ₄ ⁻ , more preferably. Is [TFSI] ⁻ or [FSI] ⁻ .

Lithium salts as salts include LiPF ₆ , LiBF ₄ , Li [FSI], Li [TFSI], Li [f3C], Li [BOB], LiClO ₄ , LiBF ₃ (CF ₃ ), LiBF ₃ (C ₂ F _5). ), LiBF ₃ (C ₃ F ₇ ), LiBF ₃ (C ₄ F ₉ ), LiC (SO ₂ CF ₃ ) ₃ , LiCF ₃ SO ₂ O, LiCF ₃ COO, LiR ²¹ COO (R ²¹ has 1 carbon number) It may be an alkyl group of ~ 4, a phenyl group, or a naphthyl group) or the like. These may be used alone or in combination of two or more.

Sodium salts as salts are NaPF ₆ , NaBF ₄ , Na [FSI], Na [TFSI], Na [f3C], Na [BOB], NaClO ₄ , NaBF ₃ (CF ₃ ), NaBF ₃ (C ₂ F _5). ), NaBF ₃ (C ₃ F ₇ ), NaBF ₃ (C ₄ F ₉ ), NaC (SO ₂ CF ₃ ) ₃ , NaCF ₃ SO ₂ O, NaCF ₃ COO, NaR ²¹ COO (R ²¹ has 1 carbon number) It may be an alkyl group of ~ 4, a phenyl group, or a naphthyl group) or the like. These may be used alone or in combination of two or more.

Magnesium salts as salts are Mg (PF ₆ ) ₂ , Mg (BF ₄ ) ₂ , Mg [FSI] ₂ , Mg [TFSI] ₂ , Mg [f3C] ₂ , Mg [BOB] ₂ , Mg (ClO ₄ ). ₂ , Mg [BF ₃ (CF ₃ ) ₃ ] ₂ , Mg [BF ₃ (C ₂ F ₅ )] ₂ , Mg [BF ₃ (C ₃ F ₇ )] ₂ , Mg [BF ₃ (C ₄ F ₉ )) ] ₂ , Mg [C (SO ₂ CF ₃ ) ₃ ] ₂ , Mg (CF ₃ SO ₂ O) ₂ , Mg (CF ₃ COO) ₂ , Mg (R ²¹ COO) ₂ (R ²¹ has 1 to 1 carbon atoms) It may be an alkyl group, a phenyl group, or a naphthyl group of 4) or the like. These may be used alone or in combination of two or more.

Calcium salts as salts include Ca (PF ₆ ) ₂ , Ca (BF ₄ ) ₂ , Ca [FSI] ₂ , Ca [TFSI] ₂ , Ca [f3C] ₂ , Ca [BOB] ₂ , Ca (ClO ₄ ). ₂ , Ca [BF ₃ (CF ₃ ) ₃ ] ₂ , Ca [BF ₃ (C ₂ F ₅ )] ₂ , Ca [BF ₃ (C ₃ F ₇ )] ₂ , Ca [BF ₃ (C ₄ F ₉ )) ] ₂ , Ca [C (SO ₂ CF ₃ ) ₃ ] ₂ , Ca (CF ₃ SO ₂ O) ₂ , Ca (CF ₃ COO) ₂ , Ca (R ²¹ COO) ₂ (R ²¹ has 1 to 1 carbon atoms) It may be an alkyl group, a phenyl group, or a naphthyl group of 4) or the like. These may be used alone or in combination of two or more.

Among these, from the viewpoint of ionic conductivity, the salt is preferably a lithium salt, more preferably LiPF ₆ , LiBF ₄ , Li [FSI], Li [TFSI], Li [f3C], Li [BOB], and LiClO. _At least one selected from the group consisting of ₄ , more preferably Li [TFSI] or Li [FSI].

Grime is a compound represented by the following general formula (8).
R ²² O- (CH ₂ CH ₂ O) _t- R ²³ (8)

In formula (8), R ²² and R ²³ each independently represent an alkyl group having 1 to 4 carbon atoms, and t represents an integer of 1 to 6.

The alkyl group as R ²² and R ²³ may be, for example, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a t-butyl group and the like. Of these, the alkyl group is preferably a methyl group or an ethyl group.

T in the formula (8) is 1 to 6, preferably 3 or 4, and more preferably 4. When a grime having t in such a range is used, it tends to easily form a grime complex with a salt.

Glyme is ethylene glycol dimethyl ether (also referred to as "monoglyme" or "G1"), diethylene glycol dimethyl ether (also referred to as "diglyme" or "G2"), triethylene glycol dimethyl ether (also referred to as "triglyme" or "G3"). , Tetraethylene glycol dimethyl ether (also referred to as "tetraglyme" or "G4"), pentaethylene glycol dimethyl ether (also referred to as "pentaglyce" or "G5"), hexaethylene glycol dimethyl ether ("hexaglyclime" or "G6"). It may also be called) or the like. Among these, the grime is preferably triglime or tetraglime, and more preferably tetraglime.

The grime complex is preferably a complex of a lithium salt and a tetragrime. Specific examples thereof include a complex [LiG4] [TFSI] of Li [TFSI] and tetraethylene glycol dimethyl ether, and a complex [LiG4] [FSI] of Li [FSI] and tetraethylene glycol dimethyl ether.

The method for producing the grime complex is not particularly limited. The grime complex can be obtained, for example, by mixing the above salt with the above grime at a temperature below the boiling point of the grime. The mixing time and temperature can be appropriately set.

The mixed molar ratio of the number of moles of glyme to the number of moles of salt (number of moles of glime / number of moles of salt) may be 0.5 or more, 0.7 or more or 0.9 or more, and 2.0 or less. , 1.4 or less or 1.0 or less. When the mixed molar ratio is 0.5 or more, the viscosity of the grime complex tends to be in an appropriate range. When the mixed molar ratio is 2.0 or less, the ratio of grime not forming a complex tends to be small.

The ionic liquid is preferably a glyme complex, N, N-diethyl-N-methyl-N- (2-methoxyethyl) ammonium-bis (trifluoromethanesulfonyl) imide (DEME-TFSI), N, N-diethyl-N. -Methyl-N- (2-methoxyethyl) ammonium-bis (fluorosulfonyl) imide (DEME-FSI), 1-ethyl-3-methylimidazolium-bis (trifluoromethanesulfonyl) imide (EMI-TFSI), 1- Ethyl-3-methylimidazolium-bis (fluorosulfonyl) imide (EMI-FSI), N-methyl-N-propylpyrrolidinium-bis (trifluoromethanesulfonyl) imide (Py13-TFSI), N-methyl-N- Propropylpyrrolidinium-bis (fluorosulfonyl) imide (Py13-FSI), N-ethyl-N-methylpyrrolidinium-bis (trifluoromethanesulfonyl) imide (Py12-TFSI), or N-ethyl-N-methyl Pyrrolidinium-bis (fluorosulfonyl) imide (Py12-FSI), 1-ethyl-3-methylimidazolidium-bis (fluorosulfonyl) imide (EMI-FSI), 1-butyl-3-methylimidazolium-bis ( Trifluoromethanesulfonyl) imide (BMI-TFSI), 1-butyl-3-methylimidazolium-bis (fluorosulfonyl) imide (BMI-FSI), N-methyl-N-propylpiperidinium-bis (trifluoromethanesulfonyl) It is an imide (PP13-TFSI) or an N-methyl-N-propylpiperidinium-bis (fluorosulfonyl) imide (PP13-FSI).

When the electrolyte composition contains an ionic liquid, the content of the ionic liquid may be 10% by mass or more, 20% by mass or more, or 30% by mass or more based on the total amount of the electrolyte composition. The content of the ionic liquid may be 70% by mass or less, 60% by mass or less, or 50% by mass or less based on the total amount of the electrolyte composition. When the content of the ionic liquid is 10% by mass or more, the ionic conductivity of the obtained electrolyte layer tends to be improved, and when the content of the ionic liquid is 70% by mass or less, the independence of the obtained electrolyte layer tends to be improved. Tends to be better.

(Deep eutectic solvent)
The electrolyte composition may further contain a deep eutectic solvent. A deep eutectic solvent is obtained at around room temperature, which is obtained by mixing a "hydrogen bond donor compound" and a "hydrogen bond acceptor compound" (both or one of them is a solid near room temperature). A compound that becomes a liquid. Even if both or one of the hydrogen bond donor compound and the hydrogen bond acceptor compound is solid near room temperature, the deep eutectic solvent obtained by mixing the two causes a eutectic melting point drop and the room temperature. A liquid state in the vicinity can be created, and properties similar to ionic liquids can be exhibited. In the present specification, room temperature means 25 ° C., and near room temperature means a temperature range of 25 ° C. ± 5 ° C.

Hydrogen-bonded donor compounds (HD) include urea, acetamide, 1-methylurea, 1,3-dimethylurea, 1,1-dimethylurea, thiourea, benzamide, glycerol, ethylene glycol, malonic acid, and benzoic acid. Examples thereof include adipic acid, oxalic acid, succinic acid, and citric acid.

As the hydrogen bond acceptor compound (HA), it is preferable to use an ammonium halide salt, and as the ammonium halide salt, choline chloride, N-ethyl-2-hydroxy-N, N-dimethylethaneammonium chloride, 2 -(Chlorocarbonyloxy) -N, N, N, -trimethylethaneammonium chloride, N-benz-2-hydroxy-N, N-dimethylethaneammonium chloride and the like can be exemplified.

The molar ratio of HD to HA (HD / HA) may be 0.5 or more or 0.6 or more, 1.5 or less or 1.3 or less. When the electrolyte composition contains a deep eutectic solvent, the content of the deep eutectic solvent may be 10% by mass or more, 20% by mass or more, or 30% by mass or more based on the total amount of the electrolyte composition. It may be 70% by mass or less, 60% by mass or less, or 50% by mass or less.

(Plasticizer)
The electrolyte composition may further contain a plasticizer. The plasticizer may be any one that is compatible with a specific polymer and does not interfere with the effects of the present invention. Examples of the plasticizer include glycerins such as glycerin, diglycerin, and triglycerin; ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, polybutylene glycol, and the like. (Poly) alkylene glycols; and trimethylol propane. These may be used alone or in combination of two or more.

The plasticizer preferably contains polyalkylene glycol such as polyethylene glycol, polypropylene glycol, and polybutylene glycol from the viewpoint that it is possible to more easily achieve both transparency and ionic conductivity of the formed electrolyte layer. More preferably, it contains polyethylene glycol. The weight average molecular weight of the polyalkylene glycol may be 200 or more, 250 or more or 300 or more, and may be 2000 or less, 1500 or less or 1000 or less.

When the electrolyte composition contains a plasticizer, the content of the plasticizer may be 10% by mass or more, 20% by mass or more, or 30% by mass or more, and 70% by mass or less, based on the total amount of the electrolyte composition. , 60% by mass or less, or 50% by mass or less.

(Other ingredients)
The electrolyte composition may contain other components such as a polymer, a dispersion medium, and a filler other than poly (meth) acrylate and polyvinyl acetal, if necessary.

The polymer other than the poly (meth) acrylate and the polyvinyl acetal may be polytetrafluoroethylene, polyvinylidene fluoride, a copolymer of vinylidene fluoride and hexafluoropropylene, or the like.

The dispersion medium may be water or an organic solvent. Organic solvents include N-methyl-2-pyrrolidone (NMP), N, N-dimethylacetamide, N, N-dimethylacetamide, methylethylketone, toluene, 2-butanol, cyclohexanone, ethyl acetate, 2-propanol, acetone, It may be ethyl cell solve or the like.

The electrolyte composition can be easily formed into a film by applying it on a substrate and drying it. The viscosity of the electrolyte composition is not particularly limited, but may be 0.01 mPa · s or more, or 500 mPa · s or less.

The pH of the electrolyte composition may be 3 or more, 4 or more, 5 or more or 6 or more, and may be 9 or less, 8 or less or 7 or less. The pH here means a value measured after diluting the electrolyte composition 10-fold with water and heating at 80 ° C. for 1 hour. Since the electrolyte composition contains the above-mentioned specific polymer, the acidity of the electrolyte composition tends to be suppressed, and the corrosion of the formed electrolyte layer on the electrode portion tends to be suppressed.

The electrolyte composition may contain 20% by mass or less of an inorganic filler such as oxide particles based on the total amount of the electrolyte composition, but from the viewpoint of further improving the transparency of the formed electrolyte layer, the oxide particles and the like may be contained. It is preferable that the inorganic filler of the above is not contained.

<Electrolyte sheet>
The electrolyte sheet according to one embodiment includes a base material and an electrolyte layer provided on the base material. The electrolyte layer is formed from the above electrolyte composition. The method for forming the electrolyte layer on the substrate using the electrolyte composition is not particularly limited, and for example, the electrolyte layer may be formed by applying the electrolyte composition on the substrate and drying it. Good. The base material may be a film made of resin, and examples thereof include a polyethylene terephthalate film (PET film).

The haze of the electrolyte layer may be 1% or less, 0.9% or less, 0.8% or less, or 0.7% or less. The haze can be measured with a haze meter as described below.

The ionic conductivity of the electrolyte layer can be appropriately adjusted according to the use of the electrolyte layer and the like. For example, when used as an electrolyte layer in an electrochromic device that requires a high response rate, the ionic conductivity of the electrolyte layer is ^10-6 S / cm or more, ^10-5 S / cm or more, or 10 ^-4 S / cm. It may be the above. When used as an electrolyte layer in an electrochromic device that requires a low response rate, the ionic conductivity of the electrolyte layer is 10 ^-1 S / cm or less, ^10-2 S / cm or less, or 10 ^-3 S / cm. It may be as follows.

<Electrochromic device and its manufacturing method>
As shown in FIG. 1, the electrochromic element 100 according to the embodiment includes an electrochromic electrode portion 10, an electrolyte portion 3, and a counter electrode portion 20 in this order. The electrolyte part 3 is formed from the above electrolyte composition. The electrolyte portion 3 may be a sheet-shaped electrolyte layer formed from the electrolyte composition. Examples of the electrochromic device 100 include a proton transfer type, a K ⁺ transfer type, and a particle orientation utilization type.

The electrochromic electrode portion 10 includes, for example, a first conductive substrate 1 and a first electrochromic layer 2 formed in contact with the first conductive substrate. In this case, the electrolyte portion 3 is arranged on the first electrochromic layer side of the electrochromic electrode portion 10.

The counter electrode portion 20 includes, for example, a second conductive substrate 5 and a counter electrode layer 4 formed in contact with the second conductive substrate. In this case, the electrolyte portion 3 is arranged on the counter electrode layer side of the counter electrode portion 20. The counter electrode layer 4 may include a second electrochromic layer.

The first and second conductive substrates are preferably transparent. The first conductive substrate and the second conductive substrate may be the same or different. Examples of the first and second conductive substrates include a glass substrate with a transparent electrode and a plastic substrate with a transparent electrode.

The electrochromic layer is formed from a material for forming an electrochromic layer containing an electrochromic compound. The material for forming the electrochromic layer can be appropriately set according to the type of the electrochromic element. Examples of the electrochromic compound include tungsten oxide, a viologen compound, a phenazine compound, Prussian blue, and a hexacyanoiron compound.

The counter electrode portion 20 may be appropriately set according to the type of the electrochromic element and the material of the electrochromic electrode portion 10.

The electrochromic element 100 according to one embodiment includes a step of forming the electrolyte portion 3 by arranging an electrolyte layer formed from the electrolyte composition between the electrochromic electrode portion 10 and the counter electrode portion 20. It can be manufactured by the method. Examples of the method of arranging the electrolyte layer include a method of bonding the electrochromic electrode portion 10, the electrolyte layer obtained by peeling the base material from the electrolyte sheet, and the counter electrode portion 20 in this order.

By using the electrolyte layer formed by using the above-mentioned electrolyte composition, the electrolyte part 3 can manufacture the electrochromic element 100 without going through a sealing step for preventing the electrolyte part from sticking out. ..

Hereinafter, the present invention will be described in more detail based on Examples, but the present invention is not limited to the following Examples.

(Example 1)
Methyl methacrylate polymer (PMMA, manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.) is used as the poly (meth) acrylate, potassium bis (trifluoromethanesulfonyl) imide (K-TFSI) is used as the electrolyte salt, and 1 as the ionic liquid. -Methyl-1-propylpyrrolidinium bis (trifluoromethanesulfonyl) imide (Py13-TFSI) is used as a dispersion medium for Py13-TFSI, PMMA and K-TFSI so that the mass ratio is 4: 6: 1. An electrolyte composition was prepared by dispersing in NMP. The obtained electrolyte composition was applied onto a PET film (manufactured by Toray Industries, Inc., trade name: Lumirror) as a base material, and heated to volatilize the dispersion medium to form an electrolyte layer having a thickness of 25 μm.

(Example 2)
An electrolyte composition was prepared in the same manner as in Example 1 except that the mass ratio of Py13-TFSI, PMMA and K-TFSI was changed to 4: 6: 0.5. In the same manner as in Example 1, the obtained electrolyte composition was applied onto a substrate and heated to volatilize the dispersion medium to form an electrolyte layer having a thickness of 34 μm.

(Example 3)
Choline chloride and urea were mixed in an equimolar ratio to obtain a deep eutectic solvent. Using the obtained deep eutectic solvent, methyl methacrylate polymer (PMMA) and K-TFSI, the deep eutectic solvent, PMMA and K-TFSI were dispersed in NMP so as to have a mass ratio of 4: 6: 1. To prepare an electrolyte composition. The obtained electrolyte composition was applied onto a PET film as a base material and heated to volatilize the dispersion medium to form an electrolyte layer having a thickness of 25 μm.

(Example 4)
Polyvinyl butyral (PVB) (manufactured by Kuraray Co., Ltd., product name: Mobile B60H) is used as the polyvinyl acetal, K-TFSI is used as the electrolyte salt, Py13-TFSI is used as the ionic liquid, and Py13-TFSI and PVB K-TFSI was dispersed in a dispersion medium ethyl cell solution so as to have a mass ratio of 4: 6: 1 and dissolved at 60 ° C. to prepare an electrolyte composition. The obtained electrolyte composition was applied onto a PET film as a base material and heated to volatilize the dispersion medium to form an electrolyte layer having a thickness of 27 μm.

(Example 5)
An electrolyte composition was prepared in the same manner as in Example 4 except that the electrolyte salt K-TFSI was changed to potassium trifluoromethanesulfonate (KTFS). In the same manner as in Example 4, the obtained electrolyte composition was applied onto the substrate and heated to volatilize the dispersion medium to form an electrolyte layer having a thickness of 28 μm.

(Example 6)
100 g of tetraethylene glycol dimethyl ether (manufactured by Tokyo Chemical Industry Co., Ltd.) was distilled under reduced pressure at 90 ° C. Next, 3.77 g (17 mmol) of tetraethylene glycol dimethyl ether obtained by vacuum distillation was added to 4.85 g (17 mmol) of lithium bis (trifluoromethanesulfonyl) imide (manufactured by Kishida Chemical Co., Ltd.) under an argon atmosphere. The mixture was stirred at room temperature for 24 hours to obtain a colorless and transparent liquid as a glyme complex. Using the obtained grime complex, PVB and K-TFSI, the grime complex, PVB and K-TFSI were dispersed in a dispersion medium ethyl cell solution so as to have a mass ratio of 4: 6: 1 and dissolved at 60 ° C. The electrolyte composition was prepared. The obtained electrolyte composition was applied onto a PET film as a base material and heated to volatilize the dispersion medium to form an electrolyte layer having a thickness of 27 μm.

(Example 7)
An electrolyte composition was prepared in the same manner as in Example 6 except that PVB was changed to PMMA. In the same manner as in Example 6, the obtained electrolyte composition was applied onto the substrate and heated to volatilize the dispersion medium to form an electrolyte layer having a thickness of 25 μm.

(Example 8)
PMMA was used as the poly (meth) acrylate, K-TFSI was used as the electrolyte salt, and polyethylene glycol 400 (PEG400, manufactured by Fuji Film Wako Pure Chemical Industries, Ltd., weight average molecular weight 360-440) was used as the plasticizer. An electrolyte composition was prepared by dispersing PMMA, K-TFSI and PEG400 in a dispersion medium methyl ethyl ketone so that the mass ratio was 5.0: 1.2: 3.8. The obtained electrolyte composition was applied onto a PET film as a base material and heated to volatilize the dispersion medium to form an electrolyte layer having a thickness of 15 μm.

(Example 9)
An electrolyte composition was prepared in the same manner as in Example 8 except that the electrolyte salt K-TFSI was changed to KTFS. In the same manner as in Example 8, the obtained electrolyte composition was applied onto the substrate and heated to volatilize the dispersion medium to form an electrolyte layer having a thickness of 16 μm.

(Comparative Example 1)
A copolymer of vinylidene fluoride and hexafluoropropylene (P (VDF-HFP)) was used as the polymer, K-TFSI was used as the electrolyte salt, Py13-TFSI was used as the ionic liquid, and SiO ₂ was used as the filler. Using particles (manufactured by Nippon Aerosil Co., Ltd., product name: Aerosil R202), the polymer, electrolyte salt, ionic liquid, and SiO ₂ particles are dispersed in the dispersion medium NMP so that the mass ratio is 6: 1: 4: 1. To prepare an electrolyte composition. The obtained electrolyte composition was applied onto a PET film as a base material, heated to volatilize the dispersion medium, and the base material was peeled off to form a solid electrolyte layer having a thickness of 25 μm.

(Measurement of total light transmittance and haze)
Total light transmittance of the electrolyte layers obtained in Examples 1 to 9 and Comparative Example 1 at 380 nm to 780 nm using a spectroscopic haze meter (Nippon Denshoku Industries Co., Ltd. “SH7000”) according to JIS K7136-1. And haze were measured. These results are shown in Table 1 below. The total light transmittance of the PET film as the base material was 91.0%, and the haze of the PET film alone was 0.7%. A small haze (%) means that the electrolyte layer is highly transparent.

From Table 1, it was confirmed that the electrolyte layers obtained in Examples 1 to 9 were excellent in transparency.

1 ... 1st conductive substrate, 2 ... 1st electrochromic layer, 3 ... electrolyte section, 4 ... counter electrode layer, 5 ... second conductive substrate, 10 ... electrochromic electrode section, 20 ... counter electrode section, 100 … Electrochromic element.

Claims (12)

An electrolyte composition containing at least one polymer selected from poly (meth) acrylate and polyvinyl acetal, and an electrolyte salt. The electrolyte composition according to claim 1, wherein the polymer comprises the poly (meth) acrylate. The electrolyte composition according to claim 1, wherein the polymer contains the polyvinyl acetal. The electrolyte composition according to any one of claims 1 to 3, further containing an ionic liquid. The electrolyte composition according to any one of claims 1 to 4, further containing a deep eutectic solvent. The electrolyte composition according to any one of claims 1 to 5, further comprising a plasticizer. At least one of the poly (meth) acrylates selected from the group consisting of structural units derived from alkyl (meth) acrylates, structural units derived from urethane (meth) acrylates, and structural units derived from epoxy (meth) acrylates. The electrolyte composition according to any one of claims 1 to 6, which comprises a seed. The electrolyte composition according to any one of claims 1 to 7, wherein the poly (meth) acrylate contains a structural unit derived from an alkyl (meth) acrylate. A base material and an electrolyte layer provided on the base material are provided.
An electrolyte sheet in which the electrolyte layer is formed from the electrolyte composition according to any one of claims 1 to 8. The electrolyte sheet according to claim 9, wherein the haze of the electrolyte layer is 1% or less. An electrochromic element including an electrochromic electrode portion, an electrolyte portion, and a counter electrode portion in this order.
An electrochromic device in which the electrolyte portion is formed from the electrolyte composition according to any one of claims 1 to 8. A method for manufacturing an electrochromic element, which comprises an electrochromic electrode portion, an electrolyte portion, and a counter electrode portion in this order.
A step of forming the electrolyte portion by arranging an electrolyte layer formed from the electrolyte composition according to any one of claims 1 to 8 between the electrochromic electrode portion and the counter electrode portion. A method for manufacturing an electrochromic element.