Electrolyte comprising eutectic mixture and electrochromic device using the same

• US 20060072182A1
• Filed: 09/20/2005
• Published: 04/06/2006
• Est. Priority Date: 09/21/2004
• Status: Active Grant

• Current Assignee: LG Energy Solution Limited (LG Corporation)
• Original Assignee: LG Chem Limited (LG Corporation)
• Inventors: Lee, Byoung Bae, Mun, Su Jin, Oh, Jae Seung, Park, Jae Duk
• Granted Patent: US 7,630,117 B2
• Time in Patent Office: Days
• US Class Current: 359/265
• CPC Class Codes: G02F 1/1525 characterised by a particular ion transporting layer, e.g. electrolyte
• CPC Class Codes: G02F 2001/164 the electrolyte is made of polymers
• CPC Class Codes: Y10S 438/929 Eutectic semiconductor

Abstract

Disclosed is an electrolyte for electrochromic devices, which includes a eutectic mixture comprising: (a) a compound having an acidic functional group and basic functional group; and (b) an ionizable lithium salt. An electrochromic device using the same electrolyte is also disclosed. Because the electrochromic device uses the electrolyte comprising the eutectic mixture, which is cost-efficient and has excellent thermal and chemical stability, there are no problems related with evaporation and exhaustion as well as flammability of electrolyte. Additionally, it is possible to minimize side reactions with constitutional elements of an electrochromic device and electrolyte, thereby improving the safety. Further, it is also possible to improve the quality of an electrochromic device by virtue of a broad electrochemical window and high electroconductivity of the eutectic mixture.

Claims

1. An electrolyte for electrochromic devices, which includes a eutectic mixture comprising:

(a) a compound having an acidic functional group and basic functional group; and

(b) an ionizable lithium salt.

2. The electrolyte according to claim 1, wherein the acidic functional group is an amine group (—

NH₃⁺) and the basic functional group is a carbonyl group (—

CO).

3. The electrolyte according to claim 1, wherein the compound having an acidic functional group and basic functional group is an amide compound.

4. The electrolyte according to claim 1, wherein the lithium salt has at least one anion selected from the group consisting of F⁻

, Cl⁻

, Br⁻

, I⁻

, NO₃⁻

, N(CN)₂⁻

, BF₄⁻

, ClO₄⁻

, RSO₃⁻

, RCOO⁻

;

PF₆⁻

, (CF₃)₂PF₄⁻

, (CF₃)₃PF₃⁻

, (CF₃)₄PF₂⁻

, (CF₃)₅ PF⁻

, (CF₃)₆P⁻

, (CF₃SO₃⁻

)₂, (CF₂CF₂SO₃⁻

)₂, (CF₃SO₃)₂N⁻

, CF₃CF₂(CF₃)₂CO⁻

, (CF₃SO₂)₂CH⁻

, (SF₅)₃C⁻

, (CF₃SO₂)₃C⁻

, CF₃(CF₂)₇SO₃⁻

, CF₃CO₂⁻

, CH₃CO₂⁻

, SCN and (CF₃CF₂SO₂⁻

)₂N.

5. The electrolyte according to claim 1, wherein the eutectic mixture is represented by the following formula 1:

wherein

R₁ is a hydrogen atom, C1˜

C20 alkyl group, C1˜

C20 alkylamine group, alkenyl group, aryl group or allyl group;

R₂ is a hydrogen atom, C1˜

C20 alkyl group, alkenyl group, aryl group or allyl group;

X is a hydrogen, oxygen, carbon or nitrogen atom;

Y is an anion of a lithium salt; and

N is an integer of between 0 and 10.

6. The electrolyte according to claim 1, which is a liquid electrolyte comprising the eutectic mixture alone.

7. The electrolyte according to claim 1, which is a gel polymer electrolyte formed by polymerization of an electrolyte precursor solution comprising:

(i) the eutectic mixture; and

(ii) a monomer capable of forming a gel polymer by polymerization.

8. The electrolyte according to claim 7, wherein the monomer is a vinyl monomer.

9. The electrolyte according to claim 8, wherein the vinyl monomer is at least one selected from the group consisting of acrylonitrile, methyl methacrylate, methyl acrylate, methacrylonitrile, methyl styrene, vinyl esters, vinyl chloride, vinylidene chloride, acrylamide, tetrafluoroethylene, vinyl acetate, methyl vinyl ketone, ethylene, styrene, para-methoxystyrene and para-cyanostyrene.

10. The electrolyte according to claim 7, wherein the electrolyte precursor solution further comprises a polymerization initiator or photoinitiator.

11. The electrolyte according to claim 7, wherein the electrolyte precursor solution has a mixing ratio, on the weight basis, of 0.5-0.95:

0.05-0.5;

0.00-0.05, when expressed in terms of (ionic liquid) x;

(monomer capable of forming a gel polymer by polymerization) y;

(polymerization initiator) z, with the proviso that x+y+z=1.

12. The electrolyte according to claim 7, which is prepared by in-situ polymerization of the electrolyte precursor solution inside an electrochromic device.

13. The electrolyte according to claim 1, which comprises a polymer or gel polymer impregnated with the eutectic mixture.

14. The electrolyte according to claim 13, wherein the polymer is selected from the group consisting of polymethyl methacrylate, polyvinylidene difluoride, polyvinyl chloride, polyethylene oxide and polyhydroxyethyl methacrylate.

15. An electrochromic device comprising:

(a) a first electrode;

(b) a second electrode;

(c) an electrochromic material; and

(d) an electrolyte as defined in claim 1, which includes a eutectic mixture comprising;

(i) a compound having an acidic functional group and basic functional group; and

(ii) an ionizable lithium salt.

16. The electrochromic device according to claim 15, wherein the eutectic mixture is represented by the following formula 1:

wherein

R₁ is a hydrogen atom, C1˜

C20 alkyl group, C1-C20 alkylamine group, alkenyl group, aryl group or allyl group;

R₂ is a hydrogen atom, C1˜

C20 alkyl group, alkenyl group, aryl group or allyl group;

X is a hydrogen, oxygen, carbon or nitrogen atom;

Y is an anion of a lithium salt; and

N is an integer of between 0 and 10.

17. The electrochromic device according to claim 15, which comprises the electrochromic material in at least one of the first electrode, second electrode and the electrolyte.

18. The electrochromic device according to claim 15, wherein the electrochromic material comprises:

(a) an inorganic metal oxide selected from the group consisting of WO₃, Ir(OH)_x, MoO₃, V₂O₅, TiO₂, NiO_x, LiNiO_x and Li₂NiO_x;

(b) a conductive polymer selected from the group consisting of polypyrrole, polyaniline, polyazulene, polypyridine, polyindole, polycarbazole, polyazine and polythiophene;

or (c) an organic electrochromic material selected from the group consisting of viologen, anthraquinone and phenocyazine.

19. The electrochromic device according to claim 15, wherein either or both of the first electrode and second electrode comprise a transparent conductive film.

20. The electrochromic device according to claim 18, wherein the transparent conductive film is formed of at least one material selected from the group consisting of ITO (indium tin oxide), FTO (fluorine doped tin oxide) and IZO (indium zinc oxide).