Thermosetting polymer electrolyte composition and electrochromic device manufactured by comprising same

Abstract

A polymer electrolyte composition according to the present disclosure has remarkably excellent yellowing resistance and high adhesive strength, and thus an electrochromic device manufactured by comprising same not only has excellent optical and mechanical durability, but also has a large difference in transmittance between a coloration state and a bleaching state. In addition, the electrochromic device is excellent in coloration and bleaching speeds, and thus can be usefully used as a smart window.

Description

Thermosetting polymer electrolyte composition and electrochromic device manufactured including the same

[0001] The present disclosure provides a polymer electrolyte composition having excellent yellowing resistance and an electrochromic device manufactured including the same.

[0002] Since electrochromic (EC) devices can effectively control light transmittance, smart windows using them can reduce glare to users and prevent indoor temperatures from rising, thereby reducing the energy required for cooling, and their use is increasing.

[0003] The above electrochromic device changes light transmittance by controlling voltage and current, and is generally composed of two electrodes, an oxidation / reduction chromic layer, and an electrolyte.

[0004] Conventional electrochromic devices are manufactured using inorganic optical materials such as glass and liquid electrolytes, which are very heavy and easily damaged by external impacts. In addition, conventional electrochromic devices including liquid electrolytes have the advantage of very short discoloration times due to the high ionic conductivity of the liquid electrolyte, but conversely, the high fluidity of the liquid electrolyte makes sealing difficult during the process, and physical stability is poor.

[0005] Accordingly, in order to achieve the long-term durability and large-area expansion of the conventional electrochromic device, a polymer electrolyte was attempted to be used. However, the polymer electrolyte not only has lower ionic conductivity than a liquid electrolyte, but also rapidly increases in yellowness, especially when used or left for a long period of time, so that an electrochromic device including the polymer electrolyte has difficulty maintaining high performance for a long period of time.

[0006] Therefore, in order to manufacture an electrochromic device with significantly superior performance, a new polymer electrolyte composition is needed that has very little yellowing even after long-term use or storage, excellent storage stability, excellent adhesive strength, and high ionic conductivity.

[0007] One embodiment of the present invention provides a polymer electrolyte composition that not only has excellent long-term durability and can be manufactured on a large area, but also exhibits very low yellowing when used or left for a long period of time.

[0008] One embodiment of the present invention provides a polymer electrolyte composition capable of forming a gel-polymer electrolyte having excellent process sealing properties and physical stability with high adhesive strength in an oxidation / reduction electrochromic layer.

[0009] As one embodiment of the present invention, the polymer electrolyte composition can have not only remarkably excellent yellowing resistance and excellent adhesive strength, but also have satisfactory ionic conductivity, thereby providing an electrochromic device having high performance.

[0010] As one embodiment of the present invention, a smart window having excellent durability and easy control of transmittance is provided, including an electrochromic element having the above-described high performance.

[0011] One embodiment of the present invention provides a polymer electrolyte composition comprising: a) a branched polyhydric isocyanate compound prepared using a diisocyanate compound of the following chemical formula 1 and an aliphatic polyhydric alcohol, b) an acrylic copolymer containing a repeating unit of the following chemical formula 2, c) a lithium salt, and d) an organic solvent.

[0012] [Chemical Formula 1]

[0013]

[0014] [Chemical Formula 2]

[0015]

[0016] (In the above chemical formulas 1 and 2, A1 and A2 are independently a single bond or a straight or branched C1-C7 alkylene, R1 is hydrogen or a straight or branched C1-C7 alkyl, X is a hydroxy group or *-O-A3-OH, and the above A3 is a single bond or a straight or branched C1-C7 alkylene.)

[0017] As one embodiment of the present invention, the aliphatic polyhydric alcohol may be represented by the following chemical formula 3.

[0018] [Chemical Formula 3]

[0019]

[0020] (In the above chemical formula 3, R2 is hydrogen or straight or branched C1-C7 alkyl, and A4, A5 and A6 are each independently a single bond or straight or branched C1-C7 alkylene.)

[0021] As one embodiment of the present invention, the branched polyisocyanate compound may be represented by the following chemical formula 4.

[0022] [Chemical Formula 4]

[0023]

[0024] (In the above chemical formula 4, R3 is hydrogen or straight or branched C1-C7 alkyl, A7, A8 and A9 are independently a single bond or straight or branched C1-C7 alkylene, and A 10 , A 11 , A 12 , A 13 and A 14 and A 15 are independently a single bond or a straight or branched C1-C7 alkylene.)

[0025] As one embodiment of the present invention, in the chemical formula 1, A1 and A2 may independently be straight-chain or branched-chain C1-C5 alkylene.

[0026] As one embodiment of the present invention, the lithium salt may include one or two or more selected from the group consisting of LiF, LiCl, LiBr, LiI, LiClO4, LiClO3, LiAsF6, LiSbF6, LiAl04, LiAlCl4, LiNO3, LiN(CN)2, LiPF6, Li(CF3)2PF4, Li(CF3)3PF3, Li(CF3)4PF2, Li(CF3)5PF, Li(CF3)6P, LiSO3CF3, LiSO3C4F9, LiSO3(CF2)7CF3,LiN(SO2CF3)2, LiOC(CF3)2CF2CF3, LiCO2CF3, LiCO2CH3, LiSCN, LiB(C2O4)2, LiBF2(C2O4), and LiBF4.

[0027] In one embodiment of the present invention, the organic solvent may include one or two or more selected from the group consisting of dimethyl carbonate, diethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, methylethyl carbonate, ethyl fluoroethyl carbonate, ethylene carbonate, propylene carbonate, fluoroethylene carbonate, and butylenes carbonate.

[0028] As an embodiment of the present invention, the acrylic copolymer may contain 10 to 50 mol% of the repeating unit of the chemical formula 2 described above with respect to the total repeating unit.

[0029] As one embodiment of the present invention, the polymer electrolyte composition may contain 5 to 20 wt% of the branched polyisocyanate compound with respect to the total mass.

[0030] As one embodiment of the present invention, the polymer electrolyte composition may have an [NCO] / [OH] equivalent ratio of the branched polyisocyanate compound and the acrylic copolymer of 1 / 3 to 3 / 1.

[0031] As one embodiment of the present invention, the polymer electrolyte composition may have a yellowness difference (△YI) of 1 or less between the yellowness (YI0) of the initial polymer electrolyte composition and the yellowness (YI1) of the polymer electrolyte composition left for 2 weeks, as measured by a spectrophotometer (Hitachi, U-4100).

[0032] As an embodiment of the present invention, an electrochromic device can be provided that includes a reduction electrochromic layer, an oxidation electrochromic layer, and a gel-polymer electrolyte layer manufactured by thermally curing the polymer electrolyte composition between the reduction electrochromic layer and the oxidation electrochromic layer.

[0033] As one embodiment of the present invention, the reduction electrochromic layer may include one or two or more selected from the group consisting of WO3, MoO3, Nb2O5, Ta2O5, and TiO2.

[0034] As one embodiment of the present invention, the oxidation electrochromic layer may include one or two or more selected from the group consisting of LiNiO2, IrO2, NiO, V2O5, LixCoO2, Rh2O3, and Procyanide blue.

[0035] As one embodiment of the present invention, the electrochromic element may include an electrode including Sb, Ba, Ga, Ge, Hf, In, La, Se, Si, Ta, Se, Ti, V, Y, Zn, Zr or an oxide of an alloy thereof on one surface of a reduction electrochromic layer and an oxidation electrochromic layer.

[0036] As one embodiment of the present invention, the electrochromic device has a transmittance (T) of a 550 nm wavelength light source measured by ASTM D1003 in a discolored state. c ) is less than 10%, and the transmittance (T) of a 550 nm wavelength light source measured by ASTM D1003 in the bleached state d ) can be more than 50%.

[0037] As one embodiment of the present invention, the electrochromic device has a transmittance (T) in a decolorized state d ) and transmittance (T) of the discolored state c ) can have a transmittance difference (△T) of 40 to 60%.

[0038] As one embodiment of the present invention, the electrochromic device may have a color change speed and a color fading speed of 15 seconds or less.

[0039] As one embodiment of the present invention, the gel-polymer electrolyte layer may have a measured adhesive strength of 5 N / 2.5 cm or more.

[0040] As one embodiment of the present invention, the polymer electrolyte composition has remarkably excellent yellowing resistance, in which the yellowness difference (△YI) between the yellowness (YI0) of the initial polymer electrolyte composition and the yellowness (YI1) of the polymer electrolyte composition left for two weeks, as measured by a U-4100 measuring device, is 1.0 or less, 0.5 or less, preferably 0.4 or less, and more preferably 0.22 or less, so that even if stored for a long period of time, there is no deterioration in optical properties, and an electrochromic device manufactured including the same can be used with its initial performance for a long period of time.

[0041] As one embodiment of the present invention, the polymer electrolyte composition has a remarkably high adhesive strength of 180° peel strength measured by AR-1000-120 of 100 g / 2.5 cm or more, 110 g / 2.5 cm or more, preferably 120 g / 2.5 cm or more, and even more preferably 140 g / 2.5 cm or more, so that an electrochromic device using the composition can have even better physical stability.

[0042] As one embodiment of the present invention, the electrochromic device has a difference in transmittance between a discolored state and a discolored state of 50% or more, preferably 55% or more, and can be usefully used as a smart window having excellent light source blocking performance.

[0043] As one embodiment of the present invention, the electrochromic element has a very high driving speed of 15 seconds or less in which the time required to change between a discolored state and a discolored state is changed, and thus a high-performance smart window can be provided using the electrochromic element.

[0044] Therefore, the polymer electrolyte composition solves the low yellowing resistance and low ionic conductivity of conventional polymer electrolyte compositions, and thus an electrochromic device having remarkably excellent optical / mechanical durability can be used.

[0045] Figure 1 is a schematic drawing of an electrochromic device manufactured in Example 1.

[0046] Figure 2 is a drawing showing the measured transmittance values ​​of the electrochromic device of Example 1.

[0047] Figure 3 is a drawing showing the transmittance measurement values ​​of the electrochromic device of Comparative Example 2.

[0048] Figure 4 is a drawing showing the transmittance measurement values ​​of the electrochromic device of Comparative Example 3.

[0049] Figure 5 is a drawing showing the measured transmittance values ​​of the electrochromic device of Comparative Example 4.

[0050] Hereinafter, the polymer electrolyte composition according to the present invention will be described. In this context, unless otherwise defined, the technical and scientific terms used have the meanings commonly understood by those of ordinary skill in the art to which this invention pertains. In the following description, descriptions of well-known functions and configurations that may unnecessarily obscure the gist of the present invention will be omitted.

[0051] As used herein, the singular forms may be intended to include the plural forms as well, unless the context clearly indicates otherwise.

[0052] Additionally, the numerical ranges used herein include lower and upper limits and all values ​​within that range, increments logically derived from the shape and width of the defined range, all doubly defined values, and all possible combinations of upper and lower limits of numerical ranges defined in different shapes. Unless otherwise specifically defined in the specification of the present invention, values ​​outside the numerical range that may arise due to experimental error or rounding of values ​​are also included in the defined numerical range.

[0053] The term "comprises" in this specification is an open-ended description equivalent to expressions such as "includes," "contains," "has," or "characterized by," and does not exclude additional elements, materials, or processes not listed herein.

[0054] Conventional electrochromic devices have utilized liquid electrolytes. However, to utilize liquid electrolytes with high fluidity, they are typically manufactured by including the liquid electrolyte together with optical materials such as glass. As a result, conventional electrochromic devices not only have very low impact resistance, but are also heavy and difficult to manufacture on a large scale.

[0055] Conventional electrochromic devices using the above liquid electrolyte have difficulties in production due to the low impact resistance, high weight, and high surface area described above, and efforts have been made to replace the liquid electrolyte with a polymer electrolyte composition.

[0056] However, conventional electrochromic devices using the polymer electrolyte have very low yellowing resistance and ionic conductivity of the polymer electrolyte, so there are limitations in manufacturing high-performance electrochromic devices.

[0057] Accordingly, the inventors of the present invention have discovered that a polymer electrolyte composition manufactured by including a branched polyisocyanate compound having a specific structure of the present invention has remarkably excellent yellowing resistance and excellent adhesive strength, and that a high-performance electrochromic device can be manufactured using the same, despite the use of a polymer electrolyte, and have completed the present invention.

[0058] As one embodiment of the present invention, the polymer electrolyte composition may include a) a branched polyhydric isocyanate compound prepared using a diisocyanate compound of the following chemical formula 1 and an aliphatic polyhydric alcohol, b) an acrylic copolymer, c) a lithium salt, and d) an organic solvent.

[0059] [Chemical Formula 1]

[0060]

[0061] (In the above chemical formula 1, A1 and A2 are each independently a single bond, straight chain or branched chain C1-C7 alkylene.)

[0062] As one embodiment of the present invention, in the chemical formula 1, A1 and A2 may be each independently a straight-chain or branched-chain C1-C7 alkylene, and as another embodiment, A1 and A2 may be each independently a methylene, ethylene or n-butylene.

[0063] A branched polyisocyanate compound manufactured by including the diisocyanate compound satisfying the above-described structure may have better miscibility, and a polymer electrolyte composition manufactured by including the same may have significantly better yellowing resistance, and thus may be preferred.

[0064] In addition, the diisocyanate compound of the above chemical formula 1 is not particularly limited as long as the manufactured polymer electrolyte composition has the properties targeted in the present invention, but may be xylene diisocyanate in terms of manufacturing a high-performance electrochromic device with remarkably excellent yellowing resistance and excellent adhesive strength.

[0065] In one embodiment of the present invention, the aliphatic polyhydric alcohol may contain two or more hydroxyl groups, and in another embodiment, it may contain two to four hydroxyl groups, or it may contain three or four hydroxyl groups.

[0066] The above aliphatic polyhydric alcohol may be, for example, one or a mixture of two or more selected from the group consisting of ethanediol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,4-butanediol, 1,5-pentanediol, and 1,6-hexanediol, trimethylolpropane, trimethylolbutane, trimethylolpentane, and pentaerythritol, but is not limited thereto.

[0067] As another embodiment of the present invention, the aliphatic polyhydric alcohol may be represented by the following chemical formula 3, in that the polymer electrolyte composition produced has better yellowing resistance and better adhesiveness, and has good viscosity for coating workability.

[0068] [Chemical Formula 3]

[0069]

[0070] (In the above chemical formula 3, R2 is hydrogen or straight or branched C1-C7 alkyl, and A4, A5 and A6 are each independently a single bond or straight or branched C1-C7 alkylene.)

[0071] The above aliphatic polyhydric alcohol is not particularly limited as long as it contains two or more hydroxyl groups, but in terms of the polymer electrolyte composition including the branched polyhydric isocyanate compound to be manufactured having a high gelation rate, high yellowing resistance and high adhesive strength, it may be preferred to use an aliphatic trihydric alcohol or an aliphatic tetrahydric alcohol.

[0072] In another embodiment of the present invention, in the chemical formula 3, R2 is a straight or branched C1-C7 alkyl, A4, A5 and A6 can be each independently a straight or branched C1-C7 alkylene, or R2 is methyl or ethyl, propyl, butyl, pentyl, and A4, A5 and A6 can be each independently methylene or ethylene, but this is not necessarily limited thereto.

[0073] As another embodiment of the present invention, the branched polyisocyanate compound may be represented by the following chemical formula 4.

[0074] [Chemical Formula 4]

[0075]

[0076] (In the above chemical formula 4, R3 is hydrogen or straight or branched C1-C7 alkyl, A7, A8 and A9 are independently a single bond or straight or branched C1-C7 alkylene, and A 10 , A 11 , A 12 , A 13 and A 14 and A 15 are independently single bonds, straight chain or branched C1-C7 alkylene.)

[0077] The branched polyisocyanate compound of the above chemical formula 4 is an embodiment manufactured by including an aliphatic trihydric alcohol, and a polymer electrolyte composition including the same can have excellent yellowing resistance and excellent adhesiveness.

[0078] The above chemical formula 4 is manufactured by including the diisocyanate compound of the above chemical formula 1 as a precursor material and the aliphatic polyhydric alcohol represented by the above chemical formula 3, and a detailed description thereof is omitted.

[0079] As one embodiment of the present invention, the branched polyisocyanate compound may be prepared by a urethane reaction with 1 equivalent or more of the diisocyanate compound of the above chemical formula 1, preferably 1 to 3 equivalents, per 1 equivalent of the aliphatic polyhydric alcohol, and preferably, a urethane reaction with an equivalent ratio of 1:2 to 2:1 may be preferred.

[0080] The above branched polyhydric isocyanate and aliphatic polyhydric alcohol urethane reaction may further include a catalyst, and the catalyst may be dibutyltin dilaurate (DBTDL), etc. However, the catalyst used in the above urethane reaction is not particularly limited as long as it is recognizable to a person skilled in the art.

[0081] As one embodiment of the present invention, the branched polyisocyanate compound may be a commercially available one, and as a non-limiting example, it may be Konnate X-110 from Hanwha Solutions, but is not necessarily limited thereto.

[0082] As one embodiment of the present invention, the polymer electrolyte composition is not limited in its composition ratio as long as the effect of the present invention is achieved, but for example, it may contain 5 to 20 wt% of the branched polyisocyanate compound with respect to the total weight of the polymer electrolyte composition, and in another embodiment, it may contain 5 to 15 wt%, or 5 to 10 wt%, but is not limited thereto.

[0083] A polymer electrolyte composition satisfying the above range may have excellent adhesive strength and remarkably excellent yellowing resistance, and may be preferred because it can manufacture a high-performance electrochromic device having a relatively wide transmittance difference with low transmittance in a discolored state and high transmittance in a decolorized state, and a very fast driving speed in a discolored state and a decolorized state.

[0084] As one embodiment of the present invention, the acrylic copolymer may contain a repeating unit represented by the following chemical formula 2.

[0085] [Chemical Formula 2]

[0086]

[0087] (In the above chemical formula 2, R1 is hydrogen or straight or branched C1-C7 alkyl, X is a hydroxy group or *-O-A3-OH, and in the above *-O-A3-OH, A3 is a single bond or straight or branched C1-C7 alkylene.)

[0088] Since the above acrylic copolymer contains a repeating unit represented by the above chemical formula 2, it can react with a branched polyisocyanate compound included in the polymer electrolyte composition and be thermally cured.

[0089] As one embodiment of the present invention, in the chemical formula 2, R1 is hydrogen or a straight or branched C1-C4 alkyl, X is a hydroxy group or *-O-A3-OH, and A3 may be a single bond or a straight or branched C1-C4 alkylene.

[0090] As another embodiment, in the above chemical formula 2, R1 is hydrogen or methyl, X is a hydroxy group or *-O-A3-OH, A3 may be a single bond, methylene, ethylene or butylene, and the repeating unit of the above chemical formula 2 may be a methacrylic acid and 2-hydroxy methacrylate repeating unit.

[0091] A polymer electrolyte composition including an acrylic copolymer satisfying the above structure may not only have excellent transparency, but may also be preferred because it can form a urethane bond with the branched polyisocyanate compound with high reactivity.

[0092] As one embodiment of the present invention, the acrylic copolymer may be copolymerized by including a base acrylic monomer that does not contain hydroxyl.

[0093] The above base acrylic monomer may be, as a non-limiting example, one or a mixed monomer of two or more selected from the group consisting of methyl (meth)acrylate, ethyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, t-butyl (meth)acrylate, cyclohexyl (meth)acrylate, benzyl (meth)acrylate, methoxyethyl (meth)acrylate, ethoxyethyl (meth)acrylate, and butoxymethyl (meth)acrylate.

[0094] In terms of providing a polymer electrolyte composition having better transparency and better adhesiveness, the above base acrylic monomer may preferably be a mixed monomer of methyl methacrylate, ethyl methacrylate, and n-butyl methacrylate, or may be more preferably a mixed monomer of methyl methacrylate and n-butyl methacrylate, but this is not necessarily limited as long as it does not impair the physical properties of the polymer electrolyte composition.

[0095] As one embodiment of the present invention, the acrylic copolymer may be a homopolymer containing only the repeating unit of the chemical formula 2 described above, but may contain 10 to 50 mol% of the repeating unit represented by the chemical formula 2 based on the total repeating unit, and in another embodiment, may be a copolymer containing 10 to 30 mol%, or 10 to 20 mol%.

[0096] An acrylic copolymer satisfying the above range may be preferred because it has excellent urethane reactivity with the branched polyisocyanate compound, and a polymer electrolyte composition containing the same may have high transparency, but is not necessarily limited thereto.

[0097] As one embodiment of the present invention, the acrylic copolymer may be represented by the following chemical formula 5.

[0098] [Chemical Formula 5]

[0099]

[0100] (In the above chemical formula 5, when a+b+c+d=1, a is 0.05 to 0.1, b is 0.05 to 0.1, c is 0.5 to 0.7, and d is 0.05 to 0.1.)

[0101] In one embodiment of the present invention, the acrylic copolymer may have a weight average molecular weight of 50,000 to 150,000 g / mol, and in another embodiment, it may have a weight average molecular weight of 50,000 to 100,000 g / mol, or 70,000 to 100,000 g / mol, but is not necessarily limited thereto.

[0102] An acrylic copolymer satisfying the weight average molecular weight within the above range may be preferred because a polymer electrolyte composition manufactured by including the acrylic copolymer can have a viscosity with good coating properties and can be cured to have excellent mechanical properties.

[0103] The above weight average molecular weight measurement method may be performed using dimethylformamide containing lithium bromide as a mobile phase solvent and gel permeation chromatography (GPC) equipment (Agilent Technologies) including a refractive index change detector, at 40°C and a mobile phase solvent flow rate of 1.0 mL / min. However, as long as it is a measurement method that can be recognized by a person skilled in the art, it is not necessarily limited thereto.

[0104] As one embodiment of the present invention, the acrylic copolymer may be a commercialized product, and as a non-limiting example, may be SERACRYL 8290 from Samhwa Paint Co., Ltd., but is not necessarily limited thereto.

[0105] In one embodiment of the present invention, the polymer electrolyte composition may have an [NCO] / [OH] equivalent ratio of the branched polyisocyanate compound and the acrylic copolymer of 1 / 3 to 3 / 1, and in another embodiment, it may be 1 / 2 to 2 / 1, or 1 / 1.5 to 1.5 / 1.

[0106] A polymer electrolyte composition satisfying the equivalence ratio in the above range may be preferred because it has high adhesive strength and can be heat-cured to form a gel-electrolyte layer with excellent mechanical properties.

[0107] As one embodiment of the present invention, the lithium salt may be one or two or more selected from the group consisting of LiF, LiCl, LiBr, LiI, LiClO4, LiC2F6NO4S2, LiClO3, LiAsF6, LiSbF6, LiAl04, LiAlCl4, LiNO3, LiN(CN)2, LiPF6, Li(CF3)2PF4, Li(CF3)3PF3, Li(CF3)4PF2, Li(CF3)5PF, Li(CF3)6P, LiSO3CF3, LiSO3C4F9, LiSO3(CF2)7CF3, LiN(SO2CF3)2, LiOC(CF3)2CF2CF3, LiCO2CF3, LiCO2CH3, LiSCN, LiB(C2O4)2, LiBF2(C2O4), and LiBF4, and may be used without limitation as long as it is used as a polymer electrolyte composition.

[0108] In another embodiment of the present invention, the lithium salt may preferably contain one or more fluorine substituents, or may preferably contain one or more selected from LiF, LiAsF6, LiSbF6, and LiC2F6NO4S2, in order to provide a polymer electrolyte composition having excellent ionic conductivity.

[0109] As one embodiment of the present invention, the polymer electrolyte composition may contain a lithium salt in an amount of 0.5 to 2 M, and as another embodiment, it may contain a lithium salt in an amount of 1 to 1.5 M.

[0110] A polymer electrolyte composition containing a lithium salt in the above range of concentrations may be preferred because it can simultaneously have excellent lithium salt solubility and high ionic conductivity.

[0111] As an embodiment of the present invention, the organic solvent may be used without limitation as long as it is used as a polymer electrolyte, and may be an ester solvent, an aromatic hydrocarbon solvent, a ketone solvent, an alkoxyalkane solvent, and a carbonate solvent. A carbonate solvent having excellent solubility of the branched polyvalent isocyanate compound, an acrylic copolymer, and a lithium salt may be preferred, but is not necessarily limited thereto.

[0112] In one embodiment of the present invention, the organic solvent may be one or more selected from the group consisting of dimethyl carbonate, diethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, methylethyl carbonate, ethyl fluoroethyl carbonate, ethylene carbonate, propylene carbonate, fluoroethylene carbonate, propylene carbonate, and butylenes carbonate, and in terms of the good coatability of the polymer electrolyte composition to be manufactured, it may be more preferable to include propylene carbonate or to use propylene carbonate alone.

[0113] As one embodiment of the present invention, the polymer electrolyte composition may further include a curing retarder.

[0114] The polymer electrolyte composition containing the above-mentioned retarder can have excellent storage stability because the viscosity does not increase when left in an environment other than the curing temperature without affecting the curing speed and curing rate, etc., by allowing the side reactions of the branched polyisocyanate compound and the acrylic copolymer to proceed.

[0115] The retarder is not particularly limited as long as it does not impair the properties of the polymer electrolyte composition, but as a non-limiting example, acetylacetone can be used. The acetylacetone can be prepared by condensing acetone and ethyl acetate in the presence of a base such as sodium or sodium alkoxide, or by condensing acetone and acetic anhydride in the presence of boron trifluoride. In addition, at least one acid selected from among anhydride, oxyacid, phosphoric acid, boric acid, and paratoluenesulfonic acid, or at least one ketone selected from among methyl ethyl ketone, methyl propyl ketone, methyl butyl ketone, ethyl propyl ketone, methyl isobutyl ketone, and methyl aryl ketone can be used.

[0116] As one embodiment of the present invention, the polymer electrolyte composition may contain a retardant in an amount of 5 wt% or less based on the total weight, and in another embodiment, it may contain a retardant in an amount of 3 wt% or less, or 2 wt% or less, and although the lower limit is not limited, it may be 0.1 wt% or more.

[0117] A polymer electrolyte composition containing a retarder in the above range of contents may be preferred because it can have an excellent curing speed and remarkably excellent storage stability, but this is not necessarily limited thereto.

[0118] As one embodiment of the present invention, the polymer electrolyte composition may have a yellowness difference (△YI) between the yellowness (YI0) of the initial polymer electrolyte composition and the yellowness (YI1) of the polymer electrolyte composition left for two weeks, as measured by a measuring device U-4100, of 1 or less and 0.5 or less, preferably, the yellowness difference (△YI) may be 0.4 or less, 0.3 or less, or even more preferably, 0.2 or less, and although the lower limit is not limited, it may be 0.1 or more.

[0119] Since the polymer electrolyte composition has remarkably excellent yellowing resistance as described above, it can prevent deterioration of optical properties due to long-term storage, and thus an electrochromic device manufactured using the composition can be used while maintaining its initial performance for a long period of time.

[0120] Accordingly, the polymer electrolyte composition comprises the branched polyisocyanate compound, the acrylic copolymer, the lithium salt, and the organic solvent, and has remarkably excellent yellowing resistance, high ionic conductivity, and high adhesive strength that can be used as an electrochromic device, so that a high-performance electrochromic device can be manufactured using the same.

[0121] An electrochromic device according to one aspect of the present invention may include a reduction electrochromic layer, an oxidation electrochromic layer, and a gel-polymer electrolyte layer manufactured by thermally curing the polymer electrolyte composition between the reduction electrochromic layer and the oxidation electrochromic layer.

[0122] The above electrochromic device can be manufactured on a large area using the above polymer electrolyte composition, has excellent flexibility, and has remarkably excellent yellowing resistance, so that it can maintain its initial performance even after long-term use.

[0123] According to one aspect of the present invention, the electrochromic element (100) may be of the form shown in the following Figure 1, and may be formed by sequentially stacking a lower transparent substrate (10), a first electrode (20), a reduction electrochromic layer (30), a gel-polymer electrolyte layer (40), an oxidation electrochromic layer (50), a second electrode (60), and an upper transparent substrate (70).

[0124] According to another aspect of the present invention, the electrochromic element (100) may be configured such that a lower transparent substrate (10), a first electrode (20), an oxidation electrochromic layer (50), a gel-polymer electrolyte layer (40), a reduction electrochromic layer (30), a second electrode (60), and an upper transparent substrate (70) are sequentially laminated.

[0125] As one embodiment of the present invention, the electrochromic device includes a gel-polymer electrolyte layer obtained by heat-curing a polymer electrolyte composition having excellent yellowing resistance and adhesive strength, so that the transmittance of a light source can be very easily controlled, the light source can be effectively blocked, and a very excellent driving speed can be achieved.

[0126] As one embodiment of the present invention, the electrochromic device has a transmittance (T) of a 550 nm wavelength light source measured by ASTM D1003 in a discolored state. c ) may be less than or equal to 10%, preferably less than or equal to 9%, less than or equal to 8%, more preferably less than or equal to 7%, and although the lower limit is not limited, it may be greater than or equal to 5%.

[0127] As one embodiment of the present invention, the electrochromic device has a transmittance (T) of a 550 nm wavelength light source measured by ASTM D1003 in a decolorized state. d ) can be greater than 50%, preferably greater than 51%, greater than 52%, even better greater than 53%, greater than 54%, and at best greater than 55%, and may not exceed 60%, although the upper limit is not limited thereto.

[0128] As one embodiment of the present invention, the electrochromic device has a transmittance (T) in a decolorized state d ) and transmittance (T) of the discolored state c ) can have a transmittance difference (△T) of 40 to 60%, and preferably 50 to 60%.

[0129] An electrochromic element having a transmittance within the above range in a discolored state and a decolored state can excellently block an external light source, and can also transmit an external light source with high transmittance when a light source is required, thereby being useful as a smart window.

[0130] As one embodiment of the present invention, the electrochromic device may have a color change speed and a color fade speed of 15 seconds or less, preferably 14 seconds or less, more preferably 12 seconds or less, and most preferably 11 seconds or less, and although the lower limit is not limited, it may be 9 seconds or more or 10 seconds or more.

[0131] The above electrochromic device not only has the excellent external light source blocking property described above, but surprisingly can also be operated quickly at the discoloration and fading speeds in the above range, so that it can be used as a smart window with even higher performance.

[0132] The following describes the above electrochromic device in more detail.

[0133] (Transparent materials and electrodes)

[0134] As one embodiment of the present invention, the lower or upper transparent substrate may be any one selected from the group consisting of glass, titania, zirconia, polyacrylate, polyurethane, and polyethylene terephthalate, but is not limited thereto as long as it can be used as an electrochromic element.

[0135] As one embodiment of the present invention, the electrochromic device may include an electrode including an oxide of Sb, Ba, Ga, Ge, Hf, In, La, Se, Si, Ta, Se, Ti, V, Y, Zn, Zr or an alloy thereof on one surface of a reduction electrochromic layer and an oxidation electrochromic layer.

[0136] In another embodiment of the present invention, the electrode may be tin oxide, zinc oxide, silver, chromium, indium tin oxide, fluorine doped tin oxide (FTO), indium zincoxide (IZO), or a mixture thereof, and preferably, indium tin oxide or fluorine doped tin oxide (FTO) having excellent conductivity, but is not necessarily limited thereto.

[0137] As one embodiment of the present invention, the transparent substrate and electrode may use an indium tin oxide coated PET film (ITO / PET film) in which the transparent substrate and electrode are integrated.

[0138] The above ITO / PET film has excellent transparency, can have excellent electrical conductivity at the same time, and can be manufactured to a very thin thickness, so that an electrochromic device including the ITO / PET film can be lightweight and can be driven with very little energy, and thus may be preferred, but this is not necessarily a limitation.

[0139] (Oxidation electrochromic layer and reduction electrochromic layer)

[0140] As one embodiment of the present invention, if the reduction electrochromic layer is used as an electrochromic element, it may include, but is not particularly limited to, one or two or more selected from the group consisting of WO3, MoO3, Nb2O5, Ta2O5, and TiO2, and as another embodiment, it may be more preferable to use WO3, which has high transparency and can quickly change color to a deep blue-green when reduced.

[0141] As one embodiment of the present invention, the reduction electrochromic layer may be formed on the first electrode or the second electrode by a method such as a sol-gel method, a sputtering method, a slot-die coating method, a chemical vapor deposition method, or an electro-deposition method, and as another embodiment, it may be manufactured by a slot-die coating method.

[0142] The above slot-die coating method may be preferred because it is easy to control the thickness and has excellent processability for large areas, but it is not necessarily limited as long as it does not impair the properties of the electrochromic device being manufactured.

[0143] As one embodiment of the present invention, the oxidation electrochromic layer may include one or two or more selected from the group consisting of LiNiO2, IrO2, NiO, V2O5, LixCoO2, Rh2O3, and procyanide blue, and as another embodiment, procyanide blue may be preferred because it is advantageous for application to smart windows due to its ability to respond quickly in less than a second, but this is not necessarily limited thereto.

[0144] Since the above-mentioned oxidation electrochromic layer can be formed in the same manner as the reduction electrochromic layer described above on the first electrode or the second electrode, a detailed description thereof will be omitted.

[0145] As one embodiment of the present invention, the reduction electrochromic layer and the oxidation electrochromic layer may be formed on the upper surface of one side of the first electrode or the second electrode, and may be controlled according to the positive or negative electrode of the first electrode and the second electrode.

[0146] For example, if the first electrode is a positive electrode, an oxidation electrochromic layer can be formed on one side of the first electrode, and if the first electrode is a negative electrode, a reduction electrochromic layer can be formed on one side of the first electrode.

[0147] As one embodiment of the present invention, the reduction electrochromic layer and the reduction electrochromic layer may have a thickness of 0.1 to 10 μm, and as another embodiment, the thickness may be 0.1 to 5 μm.

[0148] The electrochromic layer having the above-described thickness and the electrochromic element including the same may have a significant difference in transmittance between the discolored state and the discolored state and may have excellent mechanical strength; however, this is not limited as long as the electrochromic element satisfies the target properties of the present invention.

[0149] (gel-polymer electrolyte layer)

[0150] As one embodiment of the present invention, the gel-polymer electrolyte layer may be manufactured by injecting a polymer electrolyte composition between a reduction electrochromic layer and an oxidation electrochromic layer, or by coating a polymer electrolyte composition on the surface of a reduction electrochromic layer and laminating the layers as described above.

[0151] As one embodiment of the present invention, the gel-polymer electrolyte layer may be formed by heat-curing the polymer electrolyte composition at 60 to 100°C, and as another embodiment, it may be formed by heat-curing at 60 to 80°C, or 65 to 75°C.

[0152] The above gel-polymer electrolyte layer may be preferred because it includes a polymer in which a branched polydiisocyanate compound and an acrylic copolymer are crosslinked with a urethane bond, and thus may have excellent adhesiveness and excellent sealing properties to the oxidation / reduction discoloration layer, as well as excellent ion conductivity.

[0153] In one embodiment of the present invention, the gel-polymer electrolyte layer may have a thickness of 10 to 200 μm, and in another embodiment, it may have a thickness of 10 to 150 μm, or 10 to 100 μm, but this is not necessarily limited thereto.

[0154] An electrochromic device including a gel electrolyte satisfying the thickness of the above range may be preferred because it has a high operating speed and can be lightweight, but this may be one embodiment, and the thickness may be 100 ㎛ or more or 200 ㎛ or more, and although the upper limit is not limited, it may be manufactured to be 1,000 ㎛ or less or 500 ㎛ or less.

[0155] As one embodiment of the present invention, the gel-polymer electrolyte layer may have an adhesive strength measured by a measuring device AR-1000-120 of 100 g / 2.5 cm or more, preferably 110 g / 2.5 cm or more, 120 g / 2.5 cm or more, and even more preferably 140 g / 2.5 cm or more, and although the upper limit is not limited, it may be 600 g / 2.5 cm or less, 500 g / 2.5 cm or less.

[0156] The above electrochromic device can have remarkably excellent durability because it includes a gel-polymer electrolyte layer having an adhesive strength in the above range, thereby preventing detachment of each layer.

[0157] The following examples will further illustrate the polymer electrolyte composition according to the present invention and the electrochromic device manufactured using the same. However, the following examples are merely a reference for explaining the present invention in detail and are not intended to limit the present invention, which may be implemented in various forms. In addition, unless otherwise defined, all technical and scientific terms have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention pertains. In addition, the terminology used in the description of the present invention is only for the purpose of effectively describing specific embodiments and is not intended to limit the present invention.

[0158] [measurement method]

[0159] 1. Measurement of yellowness change

[0160] The initial yellowness (Yellow Index) of the electrolyte compositions of the following examples and comparative examples was determined using a spectrophotometer (Hitachi, U-4100) as a standard light source. The electrolyte compositions were then left for two weeks, and the yellowness was measured in the same manner as above.

[0161] Afterwards, the yellowness difference (△YI) between the yellowness of the initial electrolyte composition (YI0) and the yellowness of the electrolyte composition left for two weeks (YI1) was obtained from the yellowness of the electrolyte composition.

[0162] 2. Adhesion measurement

[0163] The electrolyte compositions of the following examples and comparative examples were applied in an amount of 0.005 g to 0.025 g on a PET film (23 cm X 2.5 cm) and then overlapped with another PET film of the same size to prepare a sandwich-structured sample. At this time, the area of ​​the overlapping PET film was 20 cm X 2.5 cm, and the thickness of the electrolyte composition was 30 ㎛. Thereafter, the sandwich-structured sample was heat-cured at 70 ° C. for 60 minutes to prepare a measurement sample, and the adhesive strength of the prepared measurement sample was evaluated by measuring it at room temperature using an adhesive tester (ChemInstruments, AR-1000-120).

[0164] 3. Transmittance measurement of electrochromic devices

[0165] The transmittance of the electrochromic device in a discolored state after being driven at a voltage of -1.5 V for 30 seconds was measured for a light source with a wavelength of 300 to 850 nm using an optical measuring device (Ocean Insight, DH-2000-BAL). Conversely, the transmittance of the electrochromic device in a discolored state after being driven at a voltage of 1.5 V for 30 seconds was measured in the same manner as above. The transmittance of the electrochromic device in a discolored or discolored state measured thereafter is shown in FIGS. 2 to 5 below.

[0166] 4. Measurement of electrochromic device transmittance change and driving speed

[0167] The electrochromic element was switched between a discolored state and a decolored state for 20 cycles under the driving conditions of the above-mentioned transmittance measurement method, and the average transmittance (T) of the electrochromic element in the discolored state was measured for a light source with a wavelength of 550 nm. c ) and the average transmittance (T) of the electrochromic device in the bleached state d ) was obtained.

[0168] After this, the average transmittance (T) of the electrochromic element in the discolored state c ) and the average transmittance (T) of the electrochromic device in the bleached state d ) was obtained, and the average discoloration speed and fade speed of the electrochromic element were obtained in the above driving cycle.

[0169] Preparation of branched polyisocyanate compounds

[0170] [Manufacturing Example 1]

[0171]

[0172] 1,1,1-Trimethylolpropane and xylylene diisocyanate (Konnate X-100, Hanwha Solutions) were charged at an [OH] / [NCO] equivalence ratio of 1:1 into a reactor equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen injection device, and dibutyltin dilaurate (DBTDL) was charged at 0.02 parts by weight per 100 parts by weight of the xylene diisocyanate. Thereafter, the reactor was heated to 120°C and reacted for 2 hours to produce a branched polyhydric isocyanate compound containing a xylene diisocyanate structure.

[0173] [Comparative Manufacturing Example 1]

[0174]

[0175] In the above Manufacturing Example 1, the reaction was carried out in the same manner except that Hydrogenated Xylylene diisocyanate (HXDI) was used, and a branched polyhydric isocyanate compound containing the structure of Hydrogenated Xylylene diisocyanate (HXDI) was manufactured.

[0176] [Comparative Manufacturing Example 2]

[0177]

[0178] In the above Manufacturing Example 1, the reaction was carried out in the same manner except that methylene diphenyl diisocyanate (MDI) was used, and a branched polyhydric isocyanate compound containing the structure of methylene diphenyl diisocyanate (MDI) was manufactured.

[0179] [Comparative Manufacturing Example 3]

[0180]

[0181] Except for using Hydrogenated methylene diphenyl diisocyanate (HMDI) in the above Manufacturing Example 1, the reaction was carried out in the same manner to manufacture a branched polyhydric isocyanate compound containing the structure of Hydrogenated methylene diphenyl diisocyanate (HMDI).

[0182] [Comparative Manufacturing Example 4]

[0183]

[0184] In the above Example 1, a polymer electrolyte composition and an electrochromic device were manufactured in the same manner as in Comparative Manufacturing Example 4, except that a branched polyisocyanate compound containing the structure of toluene diisocyanate (TDI) was used.

[0185] Thereafter, the manufactured polymer electrolyte composition and electrochromic element were measured using the above measurement method, and the results are shown in Table 2 below.

[0186] Branched polyisocyanate compoundAcrylic copolymerType Content (weight%)Type Content (weight%)Example 1Preparation Example 1 (XDI)5.82Preparation Example 214.24Example 2Preparation Example 1 (XDI)7.2617.76Example 3Preparation Example 1 (XDI)8.7121.29Example 4Preparation Example 1 (XDI)11.6228.43Comparative Example 1Comparative Preparation Example 1 (HXDI)5.8214.24Comparative Example 2Comparative Preparation Example 2 (MDI)Comparative Example 3Comparative Preparation Example 3 (HMDI)Comparative Example 4Comparative Preparation Example 4 (TDI)

[0187] Yellowness difference (△YI) Adhesion (g / 2.5cm)T c (%)T d (%)△T(%)Discoloration speed(s)Fade speed(s)Example 10.21007.7255.0457.3213.8810.94Example 20.41108.2454.3446.1013.2310.85Example 30.51209.8154.0344.2213.4511.06Example 40.414010.0052.0341.9516.1113.38Comparative example 10.6757.951.7143.8122.1913.12Comparative example 238988.6845.8537.1713.5510.40Comparative example 30.6726.0144.6838.6711.499.27Comparative example 424.57310.7240.1029.387.409.84

[0188] In the above Table 2, it was confirmed that the polymer electrolyte compositions of Examples 1 to 4 had remarkably excellent yellowing resistance with a yellowness difference of 5 or less, preferably 1 or less, and excellent adhesive strength of 100 g / 2.5 cm or more. In addition, in the above Table 2, it was confirmed that the electrochromic devices of Examples 1 to 4 had a transmittance of 10% or less in a discolored state, a transmittance of 50% or more in a decolorized state, a transmittance difference between the two states of 40% or more, preferably 50% or more, and a speed of 15 seconds or less in a discolored state.

[0189] In contrast, it was confirmed that the polymer electrolyte compositions of Comparative Examples 1 to 4 had very low yellowing resistance and very low adhesive strength. In addition, Comparative Example 1 had a similar transmittance value to the Example, but the speed of discoloration and decolorization was slow, and Comparative Examples 2 to 4 had a very low difference in transmittance between the discoloration and decolorization states.

[0190] As described above, the present invention has been described through specific matters and limited examples and comparative examples, but these are provided only to help a more general understanding of the present invention, and the present invention is not limited to the above examples, and those skilled in the art to which the present invention pertains can make various modifications and variations based on this description.

[0191] Therefore, the idea of ​​the present invention should not be limited to the described embodiments, and all things that are equivalent or equivalent to the following claims as well as the claims are considered to fall within the scope of the idea of ​​the present invention.

[0192] [Symbol explanation]

[0193] 100: Electrochromic device

[0194] 10: Lower transparent material

[0195] 20: First electrode

[0196] 30: Reduction electrochromic layer

[0197] 40: Gel-polymer electrolyte layer

[0198] 50: Oxidation electrochromic layer

[0199] 60: Second electrode

[0200] 70: Upper transparent material

Claims

1. a) A branched polyhydric isocyanate compound manufactured using a diisocyanate compound of the following chemical formula 1 and an aliphatic polyhydric alcohol; b) An acrylic copolymer containing a repeating unit of the following chemical formula 2; c) lithium salt; and d) A polymer electrolyte composition comprising an organic solvent. [Chemical Formula 1] [Chemical Formula 2] In the above chemical formulas 1 and 2, A1 and A2 are independently a single bond or a straight or branched C1-C7 alkylene, R1 is hydrogen or straight or branched C1-C7 alkyl, X is a hydroxy group or *-O-A3-OH, wherein A3 in *-O-A3-OH is a single bond or a straight or branched C1-C7 alkylene.

2. In paragraph 1, A polymer electrolyte composition wherein the above aliphatic polyhydric alcohol is represented by the following chemical formula 3. [Chemical Formula 3] In the above chemical formula 3, R2 is hydrogen or straight or branched C1-C7 alkyl, A4, A5 and A6 are independently a single bond or a straight or branched C1-C7 alkylene.

3. In paragraph 2, A polymer electrolyte composition wherein the branched polyisocyanate compound is represented by the following chemical formula 4. [Chemical Formula 4] In the above chemical formula 4, R3 is hydrogen or straight or branched C1-C7 alkyl, A7, A8 and A9 are independently a single bond or a straight or branched C1-C7 alkylene, A 10 , A 11 , A 12 , A 13 and A 14 and A 15 are independently a single bond or a straight or branched C1-C7 alkylene.

4. In paragraph 1, A polymer electrolyte composition in which, in the above chemical formula 1, A1 and A2 are independently straight-chain or branched-chain C1-C5 alkylene.

5. In paragraph 1, A polymer electrolyte composition comprising one or more selected from the group consisting of LiF, LiCl, LiBr, LiI, LiClO4, LiClO3, LiAsF6, LiSbF6, LiAl04, LiAlCl4, LiNO3, LiN(CN)2, LiPF6, Li(CF3)2PF4, Li(CF3)3PF3, Li(CF3)4PF2, Li(CF3)5PF, Li(CF3)6P, LiSO3CF3, LiSO3C4F9, LiSO3(CF2)7CF3, LiN(SO2CF3)2, LiOC(CF3)2CF2CF3, LiCO2CF3, LiCO2CH3, LiSCN, LiB(C2O4)2, LiBF2(C2O4), and LiBF4.

6. In paragraph 1, A polymer electrolyte composition comprising one or more selected from the group consisting of dimethyl carbonate, diethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, methylethyl carbonate, ethyl fluoroethyl carbonate, ethylene carbonate, propylene carbonate, fluoroethylene carbonate, and butylenes carbonate.

7. In paragraph 1, A polymer electrolyte composition wherein the acrylic copolymer contains 10 to 50 mol% of the repeating unit of the chemical formula 2 based on the total repeating units.

8. In paragraph 1, A polymer electrolyte composition comprising the branched polyisocyanate compound in an amount of 5 to 20 wt% based on the total mass of the polymer electrolyte composition.

9. In paragraph 1, The above polymer electrolyte composition is a polymer electrolyte composition in which the branched polyvalent isocyanate compound and the acrylic copolymer have an [NCO] / [OH] equivalent ratio of 1 / 3 to 3 / 1.

10. In paragraph 1, The polymer electrolyte composition is a polymer electrolyte composition in which the yellowness difference (△YI) between the yellowness (YI0) of the initial polymer electrolyte composition and the yellowness (YI1) of the polymer electrolyte composition left for 2 weeks, as measured by a spectrophotometer (Hitachi, U-4100), is 1 or less.

11. Reduction electrochromic layer; Oxidation electrochromic layer; and An electrochromic device comprising a gel-polymer electrolyte layer manufactured by thermally curing a polymer electrolyte composition selected from any one of claims 1 to 10 between the reduction electrochromic layer and the oxidation electrochromic layer.

12. In paragraph 11, An electrochromic device wherein the reduction electrochromic layer comprises one or more selected from the group consisting of WO3, MoO3, Nb2O5, Ta2O5, and TiO2.

13. In paragraph 11, An electrochromic device wherein the above-mentioned oxidation electrochromic layer comprises one or more selected from the group consisting of LiNiO2, IrO2, NiO, V2O5, LixCoO2, Rh2O3, and procyanide blue.

14. In paragraph 11, The above electrochromic device is an electrochromic device including an electrode including an oxide of Sb, Ba, Ga, Ge, Hf, In, La, Se, Si, Ta, Se, Ti, V, Y, Zn, Zr or an alloy thereof on one surface of a reduction electrochromic layer and an oxidation electrochromic layer.

15. In paragraph 11, The above electrochromic device has a transmittance (T) of 550 nm wavelength light source measured by ASTM D1003 in a discolored state. c ) is less than 10%, Transmittance (T) of a 550 nm wavelength light source measured by ASTM D1003 in the bleached state d ) electrochromic device having a 50% or greater chromaticity.

16. In paragraph 15, The above electrochromic device has a transmittance (T) in a decolorized state d ) and transmittance (T) of the discolored state c ) electrochromic element having a transmittance difference (△T) of 40 to 60%.

17. In paragraph 11, The above electrochromic device is an electrochromic device having a color change speed and a color fading speed of 15 seconds or less.

18. In paragraph 11, An electrochromic device in which the above gel-polymer electrolyte layer has a measured adhesive strength of 5 N / 2.5 cm or more.

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