JP4926325B2 - Electrolyte composition, electrochemical cell, photoelectrochemical cell, and non-aqueous secondary battery - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a novel polymer liquid crystalline electrolyte composition. Furthermore, it is related with the electrochemical cell using the said electrolyte composition, especially a non-aqueous secondary battery and a photoelectrochemical cell.
[0002]
[Prior art]
Electrolytes used in electrochemical cells such as non-aqueous secondary batteries and dye-sensitized solar cells are media that contain carrier ions according to their purpose and have the function of transporting the ions between electrodes (called ion conduction). is there. For example, in lithium secondary batteries, which are representative of non-aqueous secondary batteries, lithium ion transport is a problem, and in dye-sensitized solar cells, conductivity of iodine ions and iodine trimer ions is a problem. In these batteries, a solution system having high ion conductivity is generally used as an electrolyte. However, there is a problem that depletion or leakage of the solvent when the battery is incorporated in the battery lowers the durability of the battery. Further, in a lithium secondary battery, a metal container must be used to seal the solution, so that the battery mass becomes heavy and it is difficult to give the battery shape flexibility. In recent years, various electrolytes have been proposed in order to overcome such drawbacks of solution-based electrolytes. A so-called gel electrolyte in which a solution electrolyte is infiltrated into a polymer matrix (Japanese Patent Publication No. 61-23945 and Japanese Patent Publication No. 61-23947) has a small decrease in ionic conductivity with respect to a solution-based electrolyte and does not deteriorate battery performance. The volatilization of can not be completely suppressed. A polymer electrolyte (K. Murata, Electrochimica Acta, Vol. 40, No. 13-14, p2177-2184, 1995) in which a salt is dissolved in a polymer such as polyethylene oxide solves the problem of solution electrolytes. As expected, ionic conductivity is still not sufficient. On the other hand, the counter anion is BF_Four ^-, (CF_ThreeSO₂)₂N^-Such imidazolium salts and pyridinium salts are room temperature molten salts that are liquid at room temperature, and have been proposed as electrolytes for lithium ion batteries. However, the mechanical strength and ionic conductivity of the electrolyte are contradictory, and when the mechanical strength is increased by means such as increasing the viscosity of the molten salt itself or incorporating a polymer, the ionic conductivity is decreased. It is done. Furthermore, the above-described electrolyte has a large temperature dependency of ion conductivity, and in particular, ion conductivity at low temperatures is insufficient.
[0003]
By the way, for photovoltaic power generation that converts light energy into electrical energy, single crystal silicon solar cells, polycrystalline silicon solar cells, amorphous silicon solar cells, compound solar cells such as cadmium telluride and indium copper selenide have been put to practical use or research Although it is an object of development, it is necessary to overcome problems such as manufacturing cost, securing raw materials, and length of energy payback time in dissemination. On the other hand, many solar cells using organic materials aimed at increasing the area and reducing the cost have been proposed so far, but have the problems of low conversion efficiency and poor durability.
[0004]
Under such circumstances, Nature (Vol. 353, 737-740, 1991), US Pat. No. 4,927,721, etc., use a photoelectric conversion element using an oxide semiconductor sensitized with a dye (hereinafter referred to as dye sensitization). The abbreviated photoelectric conversion element) and a photoelectrochemical cell technology using the same have been disclosed. This battery includes a photoelectric conversion element functioning as a negative electrode, a charge transfer layer, and a counter electrode. The photoelectric conversion element includes a conductive support and a photosensitive layer, and the photosensitive layer includes a semiconductor having a dye adsorbed on the surface. The charge transfer layer is made of a redox material, and is responsible for charge transport between the negative electrode and the counter electrode (positive electrode). In the photoelectrochemical cell proposed in the above patent, an aqueous solution (electrolytic solution) containing a salt such as potassium iodide as an electrolyte is used as the charge transfer layer. This method is promising because it is inexpensive and can provide relatively high energy conversion efficiency (photoelectric conversion efficiency). However, when used over a long period of time, the photoelectric conversion efficiency decreases significantly due to evaporation and depletion of the electrolyte, and it functions as a battery. It was a problem to stop.
[0005]
To solve this problem, WO95 / 18456 describes a method using an imidazolium salt, which is a low-melting-point compound, as an electrolyte as a method for preventing electrolyte depletion. According to this method, water or an organic solvent conventionally used as a solvent for the electrolyte is unnecessary or a small amount is required, so that the durability is improved, but the durability is still insufficient, and imidazolium When the concentration of the salt is increased, there is a problem that the viscosity is increased and the charge transport ability is lowered, and the photoelectric conversion efficiency is lowered. Further, there is a method using a triazolium salt as an electrolyte, but this method also causes the same problem as that of an imidazolium salt.
[0006]
As described above, it is a very difficult task to achieve both mechanical strength and ion conductivity as an electrolyte of an electrochemical cell such as a lithium ion secondary battery or a solar battery.
[0007]
As one method for solving these problems, it has been proposed that a liquid crystal compound is contained in an electrolyte composition. Examples thereof include a compound having a mesogenic group and a site having a coordination ability to ions such as an alkyleneoxy group (Japanese Patent Laid-Open No. 11-86629), and a compound having a mesogenic group introduced into a polyethylene oxide molecular chain (Japanese Patent Laid-Open No. Hei 4- 323260), a compound having a liquid crystalline moiety in the side chain of polyethylene oxide (Japanese Patent Laid-Open No. 11-116792) and the like. These are composed of flexible parts that dissolve electrolyte salts by complexing with cations and conduct ions and have high mobility, and rigid parts (mesogenic groups) for molecular assembly to maintain mechanical strength. ing.
[0008]
By the way, based on recent research by Shigehara et al. (Journal of Power Source, Vol. 92, pp. 120-123, 2001), in order for an electrolyte to function efficiently in an electrochemical cell, the ion conductivity must be high. In addition, it has been found that it is important in performance that ions serving as carriers are more selectively conducted, that is, a high carrier ion transport number. For example, it is desirable that a lithium ion transport number be high in a lithium ion battery, and a high iodine anion transport number in a dye-sensitized solar cell in which iodine anion serves as a carrier. In the electrolyte using the liquid crystalline compound described above, it is necessary to add ions according to the purpose in the form of a salt, and the conduction of the counter ions of the carrier ions lowers the transport number of the carrier ions and lowers the battery performance. .
[0009]
[Problems to be solved by the invention]
An object of the present invention is to solve the conventional problems and achieve the following objects. That is, an object of the present invention is to provide a polymer liquid crystalline electrolyte composition that is substantially non-volatile and excellent in charge transporting ability, and further includes the electrolyte composition, and is excellent in durability and ion conductivity. An electrochemical cell, a photoelectrochemical cell excellent in durability and photoelectric conversion characteristics, and a non-aqueous secondary battery excellent in cycle characteristics without lowering the battery capacity.
[0010]
[Means for Solving the Problems]
  Means for solving the above problems are as follows. That is,
<1> In the polyalkylene oxide main chain, a cation moiety or an anion moietyAnd a liquid crystalline compound comprising the structure represented by the formula (IV)It has a side chain and a counter ion of the side chain.DoPolyalkylene oxideAnd carrier ionsIt is an electrolyte composition characterized by containing.
(In formula (IV), Y ₁₁₁ Represents a divalent 6-membered aromatic group, a 5-membered heterocyclic group, a 6-membered heterocyclic group, or a condensed ring group thereof. Q ₁₂₁ And Q ₁₃₁ Each represents a divalent linking group or a single bond. n represents 1, 2 or 3, and when n is 2 or 3, a plurality of Y ₁₁₁ , Q ₁₂₁ And Q ₁₃₁ May be the same or different. )
<2> Y ₁₁₁ Are the divalent groups (Y-1), (Y-2), (Y-3), (Y-2 ′), (Y-3 ′), (Y-17), The electrolyte composition according to <1>, which is any one of (Y-18), (Y-19), (Y-20), (Y-21), and (Y-22).
<3> Y ₁₁₁ Is any one of the divalent groups (Y-1), (Y-2), (Y-17) and (Y-20) represented by the above formula, It is a thing.
<4> Q ₁₂₁ And Q ₁₃₁ Are —CH═CH—, —CH═N—, —N═N—, —N (O) ═N—, —COO—, —COS—, —CONH—, —COCH, respectively. ₂ -, -CH ₂ CH ₂ -, -OCH ₂ -, -CH ₂ NH-, -CH ₂ -, -CO-, -O-, -S-, -NH-,-(CH ₂ ) _1-3 -, -CH = CH-COO-, -CH = CH-CO-,-(C≡C) _1-3 The electrolyte composition according to any one of <1> to <3>, wherein-is a combination of divalent linking groups or a single bond.
<5> Q ₁₂₁ And Q ₁₃₁ Are each -CH ₂ CH ₂ -, -OCH ₂ -, -CH ₂ The electrolyte composition according to any one of <1> to <3>, which is-, -O-, a combination of these divalent linking groups, or a single bond.
[0012]
<6> The electrolyte composition according to any one of <1> to <5>, wherein the polyalkylene oxide includes a structure represented by the formula (I).
(In the formula (I), A isSide chainY representsAboveTable counter ionYou. )
<7>  The polyalkylene oxide isAbove<1> to <1> including the structure represented by formula (II)<6>The electrolyte composition according to any one of the above.
(In formula (II), R represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group.)
[0014]
<8>  Said <1>-whose said side chain is a liquid crystalline anion<7>The electrolyte composition according to any one of the above.
<9>  <1>-wherein the side chain is a liquid crystalline cation<7>The electrolyte composition according to any one of the above.
<10>  The counter ion of the side chain is an alkali metal ion<8>It is an electrolyte composition as described in above.
<11>  The counter ion of the side chain is an iodine anion or an anion in which at least one selected from sulfonamide, disulfonimide, N-acylsulfonamide, carboxylic acid, sulfonic acid, alcohol, active methylene, and active methine is dissociated Said<9>It is an electrolyte composition as described in above.
<12> The electrolyte composition according to any one of <1> to <11>, wherein the counter ion is the carrier ion.
<13>  <1> to above<12>It is an electrochemical cell characterized by including the electrolyte composition of any one of these.
<14>  <1> to above<12>A photoelectrochemical cell comprising a charge transfer layer containing the electrolyte composition according to any one of the above, a photosensitive layer containing a semiconductor sensitized with a dye, and a counter electrode.
<15>  <1> to above<12>A non-aqueous secondary battery comprising the electrolyte composition according to any one of the above.
  In the electrolyte, it is important that only ions to be moved do not move (the target ion has a high transport number). When the target ion is added in the form of a salt, the conduction of the counter ion of the target ion reduces the transport number of the target ion.
  According to the electrolyte composition of the present invention, in the polymer having an anion moiety in the side chain, by changing the counter cation to, for example, lithium, itself becomes a lithium salt, so that no new lithium salt is added. It can be used as an electrolyte, and since the anion is bound (chemically bonded) to the polymer chain, it does not move, and the lithium ion transport number is 1 (single ion transfer). Moreover, in the electrolyte which wants to transport an anion like the dye-sensitized solar cell, only the counter anion (for example, iodine) can be moved by fixing the cation to the side chain. As described above, the transport number of the target ions can be improved by fixing the ions that do not move in the polymer by chemical bonding.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail.
[Electrolyte composition]
The electrolyte composition of the present invention can be used for a reaction solvent such as a chemical reaction and metal plating, a CCD (charge coupled device) camera, various electrochemical cells (so-called batteries), an electrochemical sensor, a photoelectrochemical sensor, and the like. . It is preferably used for a non-aqueous secondary battery (particularly a lithium secondary battery) and a photoelectrochemical battery using a semiconductor described later, and more preferably used for a photoelectrochemical battery.
[0016]
  The electrolyte composition of the present invention comprises a polyalkylene oxide main chain having a side chain having a cation site or an anion site and a counter ion of the side chain, wherein the side chain or the counter ion is liquid crystalline. Contains alkylene oxide.
  The polyalkylene oxide can be used without adding a new salt by using a counter ion of the side chain as a carrier ion such as lithium ion (lithium battery system) or iodine anion (dye-sensitized solar cell system). Since itself can be used as an electrolyte, there are no mobile ions other than carrier ions, and the transport number of carrier ions can be improved.
  Examples of the polyalkylene oxide main chain include a polyethylene oxide main chain and a polypropylene oxide main chain.
  The polyalkylene oxide is contained in the molecular chain.AboveIt preferably has a structure represented by the formula (I).
[0018]
In formula (I), A represents a substituent having an anion site or a cation site, Y represents a counter ion of A, and at least one of A and Y is liquid crystalline.
In the present invention, it is preferable that A in Formula (I), that is, the side chain having a cation site or an anion site is liquid crystalline in that the counter ion can be a mobile carrier ion.
The polyalkylene oxide may have a substituent having two or more different anion sites or cation sites in its molecular chain.
[0019]
The anion moiety is preferably an anion in which iodine anion and sulfonamide, disulfonimide, N-acylsulfonamide, carboxylic acid, sulfonic acid, alcohol, active methylene, and active methine are dissociated, sulfonic acid, More preferred are disulfonimide and N-acylsulfonamide anions.
[0020]
Preferred examples of the cation moiety include those represented by the following formulas (III-a), (III-b) and (III-c).
[0021]
[Chemical 6]
[0022]
Q in formula (III-a)_y1Represents an atomic group capable of forming a 5- or 6-membered aromatic cation with a nitrogen atom, and R_y1Represents a substituted or unsubstituted alkyl group, a polymerizable group, or a substituted or unsubstituted alkenyl group.
[0023]
A in formula (III-b)_y1Represents a nitrogen atom or a phosphorus atom, R_y2, R_y3, R_y4And R_y5Each independently represents a substituted or unsubstituted alkyl group, a polymerizable group, or a substituted or unsubstituted alkenyl group. R_y2, R_y3, R_y4And R_y5Two or more of A_y1A non-aromatic ring containing may be formed.
[0024]
R in formula (III-c)_y1, R_y2, R_y3, R_y4, R_y5And R_y6Each independently represents a substituted or unsubstituted alkyl group, a polymerizable group, or a substituted or unsubstituted alkenyl group, and two or more of them may be linked to each other to form a ring structure.
[0025]
The cations represented by formula (III-a), formula (III-b), and formula (III-c) are represented by Q_y1Or R_y1~ R_y6A multimer may be formed via
[0026]
In the formula (III-a), an atomic group Q capable of forming an aromatic 5- or 6-membered ring cation with nitrogen._y1Are preferably selected from carbon, hydrogen, nitrogen, oxygen and sulfur.
[0027]
Q_y1As the 6-membered ring completed by the above, pyridine, pyrimidine, pyridazine, pyrazine, and triazine are preferable, and pyridine is more preferable.
[0028]
Q_y1Preferred examples of the aromatic five-membered ring completed in (1) are oxazole, thiazole, imidazole, pyrazole, isoxazole, thiadiazole, oxadiazole, and triazole, and more preferred are oxazole, thiazole, and imidazole. Particularly preferred are oxazole and imidazole.
[0029]
R in the formulas (III-a), (III-b) and (III-c)_y1~ R_y6Each independently represents a substituted or unsubstituted alkyl group (preferably having 1 to 24 carbon atoms (hereinafter referred to as C number), which may be linear or branched, and cyclic. For example, methyl, ethyl, propyl, butyl, i-propyl, pentyl, hexyl, octyl, 2-ethylhexyl, t-octyl, decyl, dodecyl, tetradecyl, 2-hexyldecyl, octadecyl, cyclohexyl, cyclopentyl) A polymerizable group (preferably a vinyl group, an acryloyl group, a methacryloyl group, a styryl group, a cinnamic acid residue, etc.), or a substituted or unsubstituted alkenyl group (preferably having a C number of 2 to 24, linear Or may be branched, for example, vinyl or allyl), preferably an alkyl group having 3 to 18 carbon atoms or C 2 to 1 It represents an alkenyl group, more preferably an alkyl group having a C number of 4-6.
[0030]
Q in formulas (III-a), (III-b) and (III-c)_y1And R_y1~ R_y6May have a substituent, and examples of preferable substituents include halogen atoms (F, Cl, Br, I), cyano groups, alkoxy groups (methoxy, ethoxy, butoxy, octyloxy, methoxyethoxy, methoxy Penta (ethyloxy), acryloyloxyethoxy, pentafluoropropoxy, etc.), aryloxy groups (phenoxy, etc.), alkylthio groups (methylthio, ethylthio, etc.), acyl groups (acetyl, propionyl, benzoyl, etc.), sulfonyl groups (methanesulfonyl, benzenesulfonyl, etc.) ), Acyloxy groups (acetoxy, benzoyloxy, etc.), sulfonyloxy groups (methanesulfonyloxy, toluenesulfonyloxy, etc.), phosphonyl groups (diethylphosphonyl, etc.), amide groups (acetylamino, benzoyl) Amide), carbamoyl group (N, N-dimethylcarbamoyl, N-phenylcarbamoyl etc.), alkyl group (methyl, ethyl, propyl, isopropyl, cyclopropyl, butyl, 2-carboxyethyl, benzyl etc.), aryl group (phenyl) , Toluyl, etc.), heterocyclic groups (eg, pyridyl, imidazolyl, furanyl, etc.), alkenyl groups (vinyl, 1-propenyl, etc.), alkoxycarbonyl groups (methoxycarbonyl, ethoxycarbonyl, etc.), and polymerizable groups (preferably vinyl) Group, acryloyl group, methacryloyl group, styryl group, cinnamic acid residue, etc.).
[0031]
In the formula (I), Y is a counter ion of A, and the same organic anion, organic cation, inorganic cation or inorganic anion as A described above is selected according to the charge of A.
[0032]
When Y is an inorganic cation, preferred examples include alkali metal ions, with lithium ions being particularly preferred.
When Y is an inorganic anion, a halogen anion (Cl^-, Br^-, I^-), Iodine trimer anion (I_Three ^-), NCS^-, BF_Four ^-, PF₆ ^-, O_FourCl^-, (C_nF_{2n + 1}SO₂) (C_mF_{2m + 1}SO₂) N^-(Wherein n and m are each a positive integer of 6 or less), C_nF_{2n + 1}SO_Three ^-Fluorosulfonate anion (n is a positive integer of 6 or less), Ph_FourB^-, AsF₆ ^-, SbF₆ ^-, B_TenCl_Ten ^-And the like.
[0033]
It is preferable that pKa of the conjugate acid of an anion part is 11 or less, and it is further more preferable that it is 7 or less.
[0034]
Examples of the mesogenic group contained in the liquid crystal moiety of A or Y in the formula (I) include those described in "Flussige Kristalle in Tabellen II, Dietrich Demus and Horst Zaschke, 7-18 (1984)." As mentioned. Among these, those represented by the following formula (IV) are preferable.
[0035]
[Chemical 7]
[0036]
In formula (IV), Y₁₁₁Represents a divalent 4- to 7-membered ring substituent or a condensed ring substituent composed thereof. Q₁₂₁And Q₁₃₁Each represents a divalent linking group or a single bond, n represents 1, 2 or 3, and when n is 2 or 3, a plurality of Y₁₁₁, Q₁₂₁And Q₁₃₁May be the same or different.
[0037]
In formula (IV), Q₁₂₁And Q₁₃₁Each represents a divalent linking group or a single bond. Examples of the divalent linking group include —CH═CH—, —CH═N—, —N═N—, —N (O) ═N—, —COO—, —COS—, —CONH—, — COCH₂-, -CH₂CH₂-, -OCH₂-, -CH₂NH-, -CH₂-, -CO-, -O-, -S-, -NH-,-(CH₂)_1-3-, -CH = CH-COO-, -CH = CH-CO-,-(C≡C)_1-3-Or a combination thereof is preferred, -CH₂-, -CO-, -O-, -CH = CH-, -CH = N-, -N = N- and combinations thereof are more preferred. In these, hydrogen atoms may be substituted. Q₁₂₁And Q₁₃₁Is particularly preferably a single bond.
[0038]
In formula (IV), Y₁₁₁Represents a divalent 4-, 5-, 6-, or 7-membered ring substituent, or a condensed ring substituent composed thereof, a 6-membered aromatic group, a 4- or 6-membered saturated or unsaturated aliphatic group More preferably, it is a 5- or 6-membered heterocyclic group or a condensed ring thereof, and examples thereof include substituents of the following formulas (Y-1) to (Y-27). It is not limited. Moreover, these combinations may be sufficient. More preferable among these substituents are (Y-1), (Y-2), (Y-18), (Y-19), (Y-21), and (Y-22). Particularly preferred are (Y-1), (Y-2), and (Y-21).
[0039]
[Chemical 8]
[0040]
[Chemical 9]
[0041]
It is preferable that any one of A and Y in the formula (I) includes an alkyl group, an alkenyl group, an alkylene group, or an alkenylene group. These alkyl groups or alkenyl groups preferably have 6 to 25 carbon atoms, more preferably 6 to 18 carbon atoms. Further, it may have a substituent, and preferred substituents include Q in the above formulas (III-a), (III-b) and (III-c)._y1And R_y1~ R_y6What was mentioned above as an upper substituent is mentioned.
[0042]
The polyalkylene oxide is preferably a salt composed of a combination of the above-mentioned organic and inorganic anions and organic and inorganic cations. In this case, the mesogenic group for imparting liquid crystal properties is an organic anion and an organic cation. Included in at least one.
[0043]
As an electrolyte for a lithium ion battery or a lithium battery, it is preferable that A has an anion portion and a mesogenic group, and the counter cation is lithium ion.
[0044]
For solar cells in which iodine ions are carriers, it is preferable that A has a cation moiety and a mesogenic group, and the counter anion is iodine ions.
[0045]
The polyethylene oxide in the present invention more preferably includes a structure represented by the formula (I) and a structure represented by the following formula (II). That is, if all the side chains have a liquid crystalline part, the material becomes a hard (small motility) material and the ionic conductivity is lowered. By making it a copolymer with a monomer having no liquid crystalline side chain, flexibility can be imparted.
[0046]
[Chemical Formula 10]
[0047]
R in formula (II) has a hydrogen atom, a substituted or unsubstituted alkyl group (preferably having 1 to 24 carbon atoms (hereinafter referred to as C number), and may be linear or branched. May also be cyclic, for example methyl, ethyl, propyl, butyl, i-propyl, pentyl, hexyl, octyl, 2-ethylhexyl, t-octyl, decyl, dodecyl, tetradecyl, 2-hexyldecyl, octadecyl , Cyclohexyl, cyclopentyl), or a substituted or unsubstituted aryl group (preferably having 6 to 24 carbon atoms, such as phenyl, 4-methylphenyl, 3-cyanophenyl, 2-chlorophenyl, 2-naphthyl), an alkyl group or Examples of the substituent on the aryl group include Q in the above formulas (III-a), (III-b) and (III-c)._y1And R_y1~ R_y6What was mentioned above as an upper substituent is mentioned.
[0048]
In the polyalkylene oxide in the present invention, the ratio of the alkylene oxide units represented by the formula (I) and the formula (II) is preferably 1: 1 to 1:50, more preferably 1: 3 to 1:30. preferable.
[0049]
The number average molecular weight of the polyalkylene oxide in the present invention is not particularly limited and can be appropriately selected according to the purpose. From the viewpoint of ionic conductivity and mechanical strength of the electrolyte material, 600 to 1, 1,000,000 are preferable, and 1,000 to 10,000 are more preferable.
[0050]
Specific examples of polyalkylene oxides including formula (I) and formula (II) are shown below, but the present invention is not limited to these.
[0051]
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[0052]
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[0053]
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[0054]
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[0055]
When the electrolyte composition of the present invention is used for an electrolyte of a photoelectrochemical cell, as a charge carrier, I^-And I_Three ^-It is preferable to use an electrolyte composition containing, which can be added in the form of any salt. Preferable counter cations of iodine salts include those represented by the aforementioned formula (III-a), (III-b) or (III-c). I_Three ^-The salt is I^-Iodine (I₂) Is generally produced in the electrolyte composition. At that time, I added₂Same amount of I_Three ^-Produces.
[0056]
I in the electrolyte composition of the present invention^-The concentration of is preferably 10 to 90% by mass, more preferably 30 to 70% by mass. In that case, it is preferable that all the remaining components are the compounds of the present invention.
[0057]
I_Three ^-Is I^-0.1 to 50 mol% is preferable, 0.1 to 20 mol% is more preferable, 0.5 to 10 mol% is further preferable, and 0.5 to 5 mol% is preferable. Most preferably it is.
[0058]
The electrolyte composition of the present invention may further contain another molten salt, and preferably used molten salts include organic cations represented by the above formulas (III-a), (III-b) and (III-c). Any anion is combined, and as anion, halide ion (Cl^-, Br^-Etc.), SCN^-, BF_Four ^-, PF₆ ^-, ClO_Four ^-, (CF_ThreeSO₂)₂N^-, (CF_ThreeCF₂SO₂)₂N^-, CH_ThreeSO_Three ^-, CF_ThreeSO_Three ^-, CF_ThreeCOO^-, Ph_FourB^-, (CF_ThreeSO₂)_ThreeC^-Etc. are mentioned as preferred examples, and SCN^-, CF_ThreeSO_Three ^-, CF_ThreeCOO^-, (CF_ThreeSO₂)₂N^-And BF_Four ^-Is more preferable. In addition, other iodine salts such as LiI and CF_ThreeCOOLi, CF_ThreeAlkali metal salts such as COONa, LiSCN, and NaSCN can also be added. The addition amount of the alkali metal salt is preferably about 0.02 to 2% by mass, and more preferably 0.1 to 1% by mass.
[0059]
In the electrolyte composition of the present invention, LiI, NaI, KI, CsI, CaI₂Metal iodides such as, quaternary imidazolium compound iodine salt, tetraalkylammonium compound iodine salt, Br₂And LiBr, NaBr, KBr, CsBr, CaBr₂Metal bromide such as, or Br₂Bromine salts of quaternary ammonium compounds such as tetraalkylammonium bromide and pyridinium bromide, metal complexes such as ferrocyanate-ferricyanate and ferrocene-ferricinium ions, sulfur compounds such as sodium polysulfide and alkylthiol-alkyldisulfides , A viologen dye, hydroquinone-quinone and the like can also be used. When contained, the amount of these compounds used is preferably 30% by mass or less of the entire electrolyte compound.
[0060]
In the present invention, a solvent can be used together with the polyalkylene oxide, preferably up to the same mass as this compound.
[0061]
The solvent used in the electrolyte composition of the present invention is a compound having a low viscosity and improving the ion mobility, or having a high dielectric constant and an effective carrier concentration, and can exhibit excellent ion conductivity. It is desirable. Examples of such a solvent include carbonate compounds such as ethylene carbonate and propylene carbonate, heterocyclic compounds such as 3-methyl-2-oxazolidinone, ether compounds such as dioxane and diethyl ether, ethylene glycol dialkyl ether, propylene glycol dialkyl ether, and polyethylene. Chain ethers such as glycol dialkyl ether and polypropylene glycol dialkyl ether, alcohols such as methanol, ethanol, ethylene glycol monoalkyl ether, propylene glycol monoalkyl ether, polyethylene glycol monoalkyl ether, polypropylene glycol monoalkyl ether, ethylene glycol, Propylene glycol, polyethylene glycol, polyp Polyhydric alcohols such as pyrene glycol and glycerol, nitrile compounds such as acetonitrile, glutarodinitrile, methoxyacetonitrile, propionitrile, and benzonitrile, esters such as carboxylic acid ester, phosphate ester, and phosphonate ester, dimethyl sulfone Aprotic polar substances such as xoxide and sulfolane, water and the like can be used. Among these, carbonate compounds such as ethylene carbonate and propylene carbonate, heterocyclic compounds such as 3-methyl-2-oxazolidinone, nitrile compounds such as acetonitrile, glutarodinitrile, methoxyacetonitrile, propionitrile, and benzonitrile, and esters are particularly preferred. preferable. These may be used alone or in combination of two or more.
[0062]
The solvent preferably has a boiling point at normal pressure (1 atm) of 200 ° C. or higher, more preferably 250 ° C. or higher, and even more preferably 270 ° C. or higher from the viewpoint of improving durability due to volatility.
[0063]
Hereinafter, a photoelectrochemical cell in which the electrolyte composition of the present invention is preferably used will be described. The photoelectrochemical cell of the present invention can be used for a battery application in which a photoelectric conversion element works in an external circuit, and includes a photosensitive layer containing a semiconductor sensitive to radiation, a charge transfer layer, and a counter electrode. Have. The charge transfer layer contains the electrolyte composition of the present invention.
[0064]
[Photoelectrochemical cell]
Hereinafter, the photoelectrochemical cell of the present invention using the electrolyte composition of the present invention will be described.
The photoelectrochemical cell of the present invention has a charge transfer layer containing the electrolyte composition, a photosensitive layer containing a semiconductor sensitized with a dye, and a counter electrode. It is configured to let you work in. Since the charge transfer layer contains the electrolyte composition of the present invention, the photoelectrochemical cell of the present invention exhibits excellent photoelectric conversion performance and excellent durability with little deterioration in battery performance over time.
[0065]
[1] Photoelectric conversion element
FIG. 1 shows an example of a photoelectric conversion element applicable to the present invention.
The photoelectric conversion element 10 is formed by sequentially laminating a conductive layer 12, an undercoat layer 14, a photosensitive layer 16, a charge transfer layer 18, and a counter electrode conductive layer 20. The photosensitive layer 16 includes a semiconductor layer 24 sensitized by the dye d and a charge transport material t. The semiconductor layer 24 is a porous layer made of semiconductor fine particles s, and voids are formed between the semiconductor fine particles s, and the charge transport material t penetrates into the voids. The charge transport material t is composed of the same components as the material used for the charge transfer layer 18. A substrate 26 is disposed below the conductive layer 12, and a substrate 28 is disposed above the counter electrode conductive layer 20. The substrates 26 and 28 are for imparting strength to the photoelectric conversion element, and may not be provided. Further, at the boundary of each layer, for example, the boundary between the conductive layer 12 and the photosensitive layer 16, the boundary between the photosensitive layer 16 and the charge transfer layer 18, the boundary between the charge transfer layer 18 and the counter electrode conductive layer 20, etc. The constituent components may be diffusively mixed with each other. Note that light may be incident on the photoelectric conversion element 10 from either or both, and the light-transmitting conductive layer 12 and the substrate 26 and / or the counter electrode conductive layer 20 and the substrate 28 may transmit light. It can comprise from the material which has.
[0066]
Next, the operation of the photoelectric conversion element 10 will be described. The case where the semiconductor fine particles s are n-type will be described.
When light enters the photoelectric conversion element 10, the incident light reaches the photosensitive layer 16 and is absorbed by the dye d or the like to generate an excited dye d. The excited dye d or the like passes high-energy electrons to the conduction band of the semiconductor fine particles s and becomes an oxidant itself. The electrons transferred to the conduction band reach the conductive layer 12 through the network of semiconductor fine particles s. Therefore, the conductive layer 12 has a negative potential with respect to the counter electrode conductive layer 20. In an embodiment in which the photoelectric conversion element 10 is used for a photovoltaic cell, when the photovoltaic cell is connected to an external circuit, electrons in the conductive layer 12 reach the counter electrode conductive layer 20 while working in the external circuit. The electrons are the components of this electrolyte (eg I^-) And reduced product (for example, I_Three ^-) Reduces and restores the oxidized form of the dye d. By continuing to irradiate light, a series of reactions occur and electricity can be taken out.
[0067]
Hereinafter, materials that can be used for each layer of the photoelectric conversion element and a method for forming the material will be described. In the following, the term “conductive support” includes both the conductive layer 12 and the conductive layer 12 and an optional substrate 26, and the term “counter electrode” includes only the counter conductive layer 20. And the counter electrode conductive layer 20 and the substrate 28 optionally provided.
[0068]
(A) Conductive support
The conductive support is composed of (1) a single layer of a conductive layer, or (2) two layers of a conductive layer and a substrate. In the case of (1), a material that can sufficiently maintain strength and hermeticity is used as the conductive layer. For example, a metal material (platinum, gold, silver, copper, zinc, titanium, aluminum, or the like is included) Alloy) can be used. In the case of (2), a substrate having a conductive layer containing a conductive agent on the photosensitive layer side can be used. Preferred conductive agents include metals (for example, platinum, gold, silver, copper, zinc, titanium, aluminum, indium, etc. or alloys containing these), carbon, or conductive metal oxides (indium-tin composite oxide, tin oxide). And those doped with fluorine or antimony). The thickness of the conductive layer is preferably about 0.02 to 10 μm.
[0069]
The lower the surface resistance of the conductive support, the better. The range of the surface resistance is preferably 50Ω / □ or less, more preferably 20Ω / □ or less.
[0070]
When irradiating light from the conductive support side, the conductive support is preferably substantially transparent. “Substantially transparent” means that the transmittance is 10% or more in a part or all of the light in the visible to near-infrared region (400 to 1200 nm), preferably 50% or more, 80% or more is more preferable. In particular, it is preferable that the transmittance in a wavelength region where the photosensitive layer is sensitive is high.
[0071]
The transparent conductive support is preferably formed by applying or vapor-depositing a transparent conductive layer made of a conductive metal oxide on the surface of a transparent substrate such as glass or plastic. A preferable transparent conductive layer is fluorine dioxide or antimony-doped tin dioxide or indium-tin oxide (ITO). As the transparent substrate, a transparent polymer film can be used in addition to a glass substrate such as soda glass which is advantageous in terms of low cost and strength, alkali-free glass which is not affected by alkali elution. Transparent polymer film materials include triacetyl cellulose (TAC), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), syndiotactic polystyrene (SPS), polyphenylene sulfide (PPS), polycarbonate (PC), polyarylate ( PAr), polysulfone (PSF), polyester sulfone (PES), polyimide (PI), polyetherimide (PEI), cyclic polyolefin, brominated phenoxy and the like. In order to ensure sufficient transparency, the amount of conductive metal oxide applied is 1 m of glass or plastic support.²It is preferable to be 0.01 to 100 g per unit.
[0072]
It is preferable to use a metal lead for the purpose of reducing the resistance of the transparent conductive support. The material of the metal lead is preferably a metal such as platinum, gold, nickel, titanium, aluminum, copper, or silver. The metal lead is preferably provided on a transparent substrate by vapor deposition, sputtering, or the like, and a transparent conductive layer made of conductive tin oxide or ITO film is preferably provided thereon. The decrease in the amount of incident light due to the installation of the metal lead is preferably within 10%, more preferably 1 to 5%.
[0073]
(B) Photosensitive layer
The photosensitive layer has a function of absorbing light and performing charge separation to generate electrons and holes. The photosensitive layer includes a dye-sensitized semiconductor. In a dye-sensitized semiconductor, light absorption and the generation of electrons and holes thereby occur mainly in the dye, and the semiconductor is responsible for receiving and transmitting these electrons (or holes). The semiconductor used in the present invention is preferably an n-type semiconductor in which conductor electrons become carriers under photoexcitation and give an anode current.
[0074]
(1) Semiconductor
Examples of the semiconductor include a single semiconductor such as silicon and germanium, a III-V compound semiconductor, a metal chalcogenide (for example, an oxide, sulfide, selenide, or a composite thereof), or a compound having a perovskite structure (for example, Strontium titanate, calcium titanate, sodium titanate, barium titanate, potassium niobate, etc.) can be used.
[0075]
Preferred metal chalcogenides include titanium, tin, zinc, iron, tungsten, zirconium, hafnium, strontium, indium, cerium, yttrium, lanthanum, vanadium, niobium or tantalum oxides, cadmium, zinc, lead, silver, antimony or Examples thereof include bismuth sulfide, cadmium or lead selenide, and cadmium telluride. Examples of other compound semiconductors include phosphides such as zinc, gallium, indium, and cadmium, gallium-arsenic or copper-indium selenides, and copper-indium sulfides. Furthermore, M_xO_yS_zOr M¹ _xM² _yO_z(M, M¹And M²Are each a metal element, O is an oxygen atom, and x, y, and z are the number of combinations in which the valence is neutral).
[0076]
Preferred specific examples of the semiconductor used in the present invention include Si and TiO.₂, SnO₂, Fe₂O_Three, WO_Three, ZnO, Nb₂O_Five, CdS, ZnS, PbS, Bi₂S_Three, CdSe, CdTe, SrTiO_Three, GaP, InP, GaAs, CuInS₂, CuInSe₂And more preferably TiO₂ZnO, SnO₂, Fe₂O_Three, WO_Three, Nb₂O_Five, CdS, PbS, CdSe, SrTiO_Three, InP, GaAs, CuInS₂And CuInSe₂And particularly preferably TiO₂And Nb₂O_FiveAnd most preferably TiO₂It is. TiO₂TiO containing 70% or more of anatase type crystals₂And particularly preferably 100% anatase crystal TiO₂It is. It is also effective to dope metals for the purpose of increasing the electronic conductivity in these semiconductors. The metal to be doped is preferably a divalent or trivalent metal. In order to prevent a reverse current from flowing from the semiconductor to the charge transfer layer, it is also effective to dope the semiconductor with a monovalent metal.
[0077]
The semiconductor used in the present invention may be single crystal or polycrystal, but polycrystal is preferable from the viewpoint of manufacturing cost, securing raw materials, energy payback time, etc., and a porous film made of semiconductor fine particles is particularly preferable. Moreover, a part amorphous part may be included.
[0078]
The particle size of the semiconductor fine particles is generally on the order of nm to μm, but the average particle size of the primary particles obtained from the diameter when the projected area is converted into a circle is preferably 5 to 200 nm, more preferably 8 to 100 nm. preferable. The average particle size of the semiconductor fine particles (secondary particles) in the dispersion is preferably 0.01 to 30 μm. Two or more kinds of fine particles having different particle size distributions may be mixed. In this case, the average size of the small particles is preferably 25 nm or less, more preferably 10 nm or less. For the purpose of improving the light capture rate by scattering incident light, it is also preferable to mix semiconductor particles having a large particle diameter, for example, about 100 nm or more and about 300 nm.
[0079]
A mixture of two or more different types of semiconductor fine particles may also be used. When using a mixture of two or more semiconductor fine particles, one is TiO₂, ZnO, Nb₂O_FiveOr SrTiO_ThreeIt is preferable that Another type is SnO₂, Fe₂O_ThreeOr WO_ThreeIt is preferable that A more preferable combination is ZnO and SnO.₂, ZnO and WO_ThreeOr ZnO, SnO₂And WO_ThreeAnd the like. When two or more kinds of semiconductor fine particles are mixed and used, their particle sizes may be different. Particularly preferred is a combination in which the semiconductor fine particles mentioned in the first type are large and the semiconductor fine particles mentioned in the second and subsequent types are small. A combination of particles having a large particle size of 100 nm or more and particles having a small particle size of 15 nm or less is preferable.
[0080]
Semiconductor fine particles can be prepared by Sakuo Sakuo's “Science of Sol-Gel Method” Agne Jofu Co., Ltd. (1998), “Thin Film Coating Technology by Sol-Gel Method” (1995) of the Technical Information Association, etc. The sol-gel method described, Tadao Sugimoto, “Synthesis and size control of monodisperse particles by a new synthetic gel-sol method”, Materia, Vol. 35, No. 9, 1012-1018 (1996) The gel-sol method described in 1 is preferred. Also preferred is a method of producing an oxide by high-temperature hydrolysis of chloride developed by Degussa in an oxyhydrogen salt.
[0081]
When the semiconductor fine particles are titanium oxide, the sol-gel method, the gel-sol method, and the high-temperature hydrolysis method in oxyhydrogen salt of chloride are all preferable, but Kiyoshi Manabu's “Titanium oxide properties and applied technology” The sulfuric acid method and the chlorine method described in Gihodo Shuppan (1997) can also be used. Further, as a sol-gel method, the method described in Journal of American Ceramic Society of Barbe et al., Vol. 80, No. 12, pages 3157-3171 (1997), and the chemistry of materials of Burnside et al. , Vol. 10, No. 9, pages 2419-2425 are also preferred.
[0082]
(2) Semiconductor fine particle layer
The semiconductor is used, for example, in the form of a semiconductor fine particle layer formed on the conductive support. In order to apply the semiconductor fine particles on the conductive support, in addition to the method of applying a dispersion or colloidal solution of the semiconductor fine particles on the conductive support, the above-described sol-gel method or the like can also be used. In consideration of mass production of photoelectric conversion elements, physical properties of semiconductor fine particle liquid, flexibility of conductive support, etc., a wet film forming method is relatively advantageous. Typical examples of the wet film forming method include a coating method, a printing method, an electrolytic deposition method, and an electrodeposition method. Also, a method of oxidizing metal, a method of depositing in a liquid phase from a metal solution by ligand exchange (LPD method), a method of vapor deposition by sputtering, a CVD method, or a metal that thermally decomposes on a heated substrate An SPD method in which a metal oxide is formed by spraying an oxide precursor can also be used.
[0083]
In addition to the sol-gel method described above, a method for producing a dispersion of semiconductor fine particles includes a method of grinding with a mortar, a method of dispersing while grinding using a mill, or a fine particle in a solvent when synthesizing a semiconductor. The method of depositing and using as it is is mentioned.
[0084]
Examples of the dispersion medium include water or various organic solvents (for example, methanol, ethanol, isopropyl alcohol, citronellol, terpineol, dichloromethane, acetone, acetonitrile, ethyl acetate, and the like). At the time of dispersion, for example, a polymer such as polyethylene glycol, hydroxyethyl cellulose, carboxymethyl cellulose, a surfactant, an acid, or a chelating agent may be used as a dispersion aid. By changing the molecular weight of the polyethylene glycol, the viscosity of the dispersion can be adjusted, and a semiconductor layer that is difficult to peel off can be formed and the porosity of the semiconductor layer can be controlled. Therefore, it is preferable to add polyethylene glycol.
[0085]
The application method is disclosed in Japanese Patent Publication No. 58-4589 as a roller method, a dip method, etc. as an application system, an air knife method, a blade method, etc. as a metering system, and the application and metering can be made the same part. The wire bar method, the slide hopper method, the extrusion method, the curtain method and the like described in U.S. Pat. Nos. 2,681,294, 2761419, 2761791 and the like are preferable. Moreover, a spin method and a spray method are also preferable as a general purpose machine. As the wet printing method, intaglio, rubber plate, screen printing and the like are preferred, including the three major printing methods of letterpress, offset and gravure. From these, a preferred film forming method is selected according to the liquid viscosity and the wet thickness.
[0086]
The semiconductor fine particle layer is not limited to a single layer, but a multi-layer coating of a dispersion of semiconductor fine particles having different particle diameters, or a multi-layer coating of a coating layer containing different types of semiconductor fine particles (or different binders and additives) You can also Multi-layer coating is also effective when the film thickness is insufficient with a single coating.
[0087]
In general, as the thickness of the semiconductor fine particle layer (same as the thickness of the photosensitive layer) increases, the amount of supported dye increases per unit projected area, and thus the light capture rate increases. Loss due to coupling also increases. Therefore, the preferred thickness of the semiconductor fine particle layer is 0.1 to 100 μm. When used for a photovoltaic cell, the thickness of the semiconductor fine particle layer is preferably 1 to 30 μm, and more preferably 2 to 25 μm. Semiconductor fine particle support 1m²The coating amount with respect to the hit is preferably 0.5 to 100 g, more preferably 3 to 50 g.
[0088]
After the semiconductor fine particles are applied on the conductive support, the semiconductor fine particles are preferably brought into contact with each other electronically, and heat treatment is preferably performed in order to improve the coating strength and the adhesion to the support. The range of preferable heating temperature is 40 ° C. or higher and 700 ° C. or lower, and more preferably 100 ° C. or higher and 600 ° C. or lower. The heating time is about 10 minutes to 10 hours. When using a support having a low melting point or softening point such as a polymer film, high temperature treatment is not preferable because it causes deterioration of the support. Moreover, it is preferable that it is as low temperature as possible (for example, 50-350 degreeC) also from a viewpoint of cost. The temperature can be lowered by heat treatment in the presence of small semiconductor fine particles of 5 nm or less, mineral acids, and metal oxide precursors, and irradiation with ultraviolet rays, infrared rays, microwaves, electric fields, and ultrasonic waves must be applied. Can also be performed. At the same time, for the purpose of removing unnecessary organic substances and the like, it is preferable to use a combination of heating, decompression, oxygen plasma treatment, pure water cleaning, solvent cleaning, gas cleaning and the like in addition to the above irradiation and application.
[0089]
After the heat treatment, for example, chemical plating using titanium tetrachloride aqueous solution or titanium trichloride to increase the surface area of the semiconductor fine particles, increase the purity in the vicinity of the semiconductor fine particles, and increase the efficiency of electron injection from the dye into the semiconductor fine particles. You may perform the electrochemical plating process using aqueous solution. In order to prevent a reverse current from flowing from the semiconductor fine particles to the charge transfer layer, it is also effective to adsorb an organic substance having a low electronic conductivity other than the dye on the particle surface. The organic substance to be adsorbed is preferably a substance having a hydrophobic group.
[0090]
The semiconductor fine particle layer preferably has a large surface area so that a large amount of dye can be adsorbed. The surface area of the semiconductor fine particle layer coated on the support is preferably 10 times or more, more preferably 100 times or more the projected area. This upper limit is not particularly limited, but is usually about 1000 times.
[0091]
(3) Dye
The sensitizing dye used in the photosensitive layer can be arbitrarily used as long as it is a compound that has absorption in the visible region and near-infrared region and can sensitize semiconductors. Organometallic complex dyes, methine dyes, porphyrin dyes, and phthalocyanine dyes A dye is preferred. Moreover, in order to make the wavelength range of photoelectric conversion as wide as possible and increase the conversion efficiency, two or more kinds of dyes can be used together or mixed. In this case, it is possible to select the dye to be used or mixed and the ratio thereof so as to match the wavelength range and intensity distribution of the target light source.
[0092]
Such a dye preferably has an appropriate interlocking group capable of adsorbing to the surface of the semiconductor fine particles. Preferred linking groups include COOH groups, OH groups, SO_ThreeH group, -P (O) (OH)₂Group and -OP (O) (OH)₂An acidic group such as a group, or a chelating group having π conductivity such as oxime, dioxime, hydroxyquinoline, salicylate or α-ketoenolate. Among them, COOH group, -P (O) (OH)₂Group and -OP (O) (OH)₂The group is particularly preferred. These groups may form a salt with an alkali metal or the like, or may form an internal salt. In the case of a polymethine dye, when the methine chain contains an acidic group as in the case where the methine chain forms a squarylium ring or a croconium ring, it may have this portion as a linking group.
[0093]
Hereinafter, preferred sensitizing dyes used in the photosensitive layer will be specifically described.
(A) Organometallic complex dye
When the dye is a metal complex dye, a metal phthalocyanine dye, a metal porphyrin dye, and a ruthenium complex dye are preferable, and a ruthenium complex dye is particularly preferable. Examples of the ruthenium complex dye include, for example, U.S. Pat. And complex dyes described in JP-A No. 504512, World Patent No. 98/50393, JP-A No. 2000-26487, and the like.
[0094]
Furthermore, when the said dye is a ruthenium complex dye, the ruthenium complex dye represented by the following general formula (V) is preferable.
General formula (V)
(A¹)_tRu (Ba)_u(Bb)_v(Bc)_w
In the general formula (V), A¹Represents a mono- or bidentate ligand. A¹Is Cl, SCN, H₂It is preferably a ligand selected from the group consisting of O, Br, I, CN, NCO, SeCN, α-diketones, oxalic acid and dithiocarbamic acid derivatives. When t is 2 or more, 2 or more A¹May be the same or different. In the general formula (V), Ba, Bb, and Bc each independently represent a ligand represented by any of the following formulas (B-1) to (B-10). t represents an integer of 0 to 3, u, v, and w each represents 0 or 1, and coordinated so that the ruthenium complex represented by the general formula (V) is a hexacoordinated complex. They are combined as appropriate according to the type of child.
[0095]
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[0096]
In the formulas (B-1) to (B-10), R^aRepresents a hydrogen atom or a substituent, and examples of the substituent include a halogen atom, a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted aralkyl group having 7 to 12 carbon atoms, Examples thereof include a substituted or unsubstituted aryl group having 6 to 12 carbon atoms, an acidic group (these acidic groups may form a salt), and a chelating group. The alkyl part of the alkyl group and the aralkyl group may be linear or branched. The aryl moiety of the aryl group and aralkyl group may be monocyclic or polycyclic (fused ring, ring assembly). In the general formula (V), Ba, BB, and Bc may be the same or different.
[0097]
Although the preferable specific example (exemplary compound R-1-17) of an organometallic complex pigment | dye is shown below, the pigment | dye used for this invention is not limited to the following specific examples.
[0098]
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[0099]
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[0100]
(B) Methine dye
Preferred methine dyes for use in the present invention are polymethine dyes such as cyanine dyes, merocyanine dyes, and squarylium dyes. Examples of polymethine dyes preferably used in the present invention include, for example, JP-A-11-35836, JP-A-11-67285, JP-A-11-86916, JP-A-11-97725, JP-A-11-158395, and JP-A-11-158395. 11-163378, JP-A-11-214730, JP-A-11-214731, JP-A-11-238905, JP-A2000-26487, European Patents 892411, 911841, and 991092 And the described dyes. Specific examples of preferable methine dyes are shown below.
[0101]
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[0102]
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[0103]
(4) Adsorption of dye to semiconductor fine particles
In order to adsorb the dye to the semiconductor fine particles, a method of immersing a conductive support having a well-dried semiconductor fine particle layer in the dye solution or applying a dye solution to the semiconductor fine particle layer can be used. In the former case, an immersion method, a dip method, a roller method, an air knife method or the like can be used. In the case of the immersion method, the adsorption of the dye may be performed at room temperature or may be performed by heating and refluxing as described in JP-A-7-249790. Examples of the latter application method include a wire bar method, a slide hopper method, an extrusion method, a curtain method, a spin method, and a spray method. Preferred solvents for dissolving the dye include, for example, alcohols (methanol, ethanol, t-butanol, benzyl alcohol, etc.), nitriles (acetonitrile, propionitrile, 3-methoxypropionitrile, etc.), nitromethane, halogenated compounds, etc. Hydrocarbon (dichloromethane, dichloroethane, chloroform, chlorobenzene, etc.), ethers (diethyl ether, tetrahydrofuran, etc.), dimethyl sulfoxide, amides (N, N-dimethylformamide, N, N-dimethylacetamide, etc.), N-methyl Pyrrolidone, 1,3-dimethylimidazolidinone, 3-methyloxazolidinone, esters (ethyl acetate, butyl acetate, etc.), carbonates (diethyl carbonate, ethylene carbonate, propylene carbonate, etc.), ketones (acetone, 2-butyl Non, cyclohexanone), hydrocarbons (hexane, petroleum ether, benzene, toluene, etc.) or mixed solvents thereof.
[0104]
The total amount of dye adsorbed is the unit surface area of the porous semiconductor electrode substrate (1 m²) Is preferably 0.01 to 100 mmol. Further, the adsorption amount of the dye to the semiconductor fine particles is preferably in the range of 0.01 to 1 mmol per 1 g of the semiconductor fine particles. By setting the dye adsorption amount within the above range, a sensitizing effect in the semiconductor can be sufficiently obtained. On the other hand, if the amount of the dye is too small, the sensitizing effect becomes insufficient, and if the amount of the dye is too large, the dye not attached to the semiconductor floats, which causes a reduction in the sensitizing effect. In order to increase the adsorption amount of the dye, it is preferable to perform a heat treatment before the adsorption. In order to avoid water adsorbing on the surface of the semiconductor fine particles after the heat treatment, it is preferable to quickly perform the dye adsorption operation at a temperature of the semiconductor electrode substrate of 60 to 150 ° C. without returning to normal temperature. Further, for the purpose of reducing the interaction such as aggregation between the dyes, a colorless compound may be added to the dyes and co-adsorbed on the semiconductor fine particles. Compounds effective for this purpose are compounds having surface active properties and structures, and examples thereof include steroid compounds having a carboxyl group (for example, chenodeoxycholic acid) and sulfonates such as the following examples.
[0105]
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[0106]
The unadsorbed dye is preferably removed by washing immediately after adsorption. It is preferable to use a wet cleaning tank and perform cleaning with a polar solvent such as acetonitrile or an organic solvent such as an alcohol solvent. After adsorbing the dye, the surface of the semiconductor fine particles may be treated with an amine or a quaternary salt. Preferable amines include pyridine, 4-t-butylpyridine and polyvinylpyridine, and preferable quaternary salts include tetrabutylammonium iodide and tetrahexylammonium iodide. When these are liquids, they may be used as they are, or may be used after being dissolved in an organic solvent.
[0107]
(C) Charge transfer layer
The charge transfer layer is a layer containing a charge transport material having a function of replenishing electrons to the oxidant of the dye. Examples of typical charge transport materials that can be used for this charge transfer layer include: (i) a solution (electrolyte) in which redox pair ions are dissolved as an ion transport material, and a redox pair solution as a polymer matrix. Examples include so-called gel electrolytes impregnated in gels, molten salt electrolytes containing redox counterions, and solid electrolytes. In addition to charge transport materials that involve ions, (ii) electron transport materials and hole transport materials can also be used as charge transport materials that involve carrier movement in solids. In the present invention, the electrolyte composition of the present invention is used for this charge transfer layer, but other charge transport materials may be used in combination.
[0108]
(1) Formation of charge transfer layer
There are two possible methods for forming the charge transfer layer. One is a method in which a counter electrode is first bonded onto the photosensitive layer, and a liquid charge transfer layer is sandwiched between the gaps. The other is a method in which a charge transfer layer is provided directly on the photosensitive layer, and a counter electrode is subsequently provided.
[0109]
In the former case, as a method for sandwiching the charge transfer layer, a normal pressure process using a capillary phenomenon due to immersion or a vacuum process in which the gas phase in the gap is replaced with a liquid phase at a pressure lower than normal pressure can be used.
[0110]
In the latter case, in the wet charge transfer layer, a counter electrode is provided without being dried, and measures for preventing liquid leakage at the edge portion are taken. In the case of a gel electrolyte, there is a method in which it is applied in a wet manner and solidified by a method such as polymerization. In this case, the counter electrode can be applied after drying and fixing. As a method for applying the wet organic hole transporting material and the gel electrolyte in addition to the electrolytic solution, the same methods as those for the semiconductor fine particle layer and the dye can be used.
[0111]
(D) Counter electrode
Similar to the conductive support described above, the counter electrode may have a single-layer structure of a counter electrode conductive layer made of a conductive material, or may be composed of a counter electrode conductive layer and a support substrate. As the conductive material used for the counter electrode conductive layer, metal (for example, platinum, gold, silver, copper, aluminum, magnesium, indium, etc.), carbon, or conductive metal oxide (indium-tin composite oxide, fluorine-doped tin oxide, etc.) ). Among these, platinum, gold, silver, copper, aluminum, and magnesium can be preferably used as the counter electrode conductive layer. An example of a preferable support substrate for the counter electrode is glass or plastic, and the above-described conductive agent is applied or vapor-deposited on the glass or plastic. The thickness of the counter electrode conductive layer is not particularly limited, but is preferably 3 nm to 10 μm. The lower the surface resistance of the counter electrode conductive layer, the better. The range of the surface resistance is preferably 50Ω / □ or less, and more preferably 20Ω / □ or less.
[0112]
Since light may be irradiated from either or both of the conductive support and the counter electrode, in order for light to reach the photosensitive layer, at least one of the conductive support and the counter electrode may be substantially transparent. . From the viewpoint of improving the power generation efficiency, it is preferable to make the conductive support transparent so that light is incident from the conductive support side. In this case, the counter electrode preferably has a property of reflecting light. As such a counter electrode, glass or plastic deposited with a metal or conductive oxide, or a metal thin film can be used.
[0113]
The counter electrode may be formed by directly applying, plating, or vapor-depositing (PVD, CVD) a conductive material on the charge transfer layer, or attaching the counter electrode conductive layer side of the substrate having the counter electrode conductive layer. Further, as in the case of the conductive support, it is preferable to use a metal lead for the purpose of reducing the resistance of the counter electrode, particularly when the counter electrode is transparent. In addition, the preferable material and installation method of the metal lead, the decrease in the amount of incident light due to the installation of the metal lead, and the like are the same as in the case of the conductive support.
[0114]
(E) Other layers
In order to prevent a short circuit between the counter electrode and the conductive support, it is preferable to coat a dense semiconductor thin film layer as an undercoat layer between the conductive support and the photosensitive layer in advance. This is particularly effective when a material or a hole transport material is used. Preferred as an undercoat layer is TiO₂, SnO₂, Fe₂O_Three, WO_Three, ZnO, Nb₂O_FiveAnd more preferably TiO₂It is. The undercoat layer can be applied by, for example, a sputtering method in addition to the spray pyrolysis method described in Electrochim. Acta 40, 643-652 (1995). The preferred thickness of the undercoat layer is 5 to 1000 nm, and more preferably 10 to 500 nm.
[0115]
Moreover, you may provide functional layers, such as a protective layer and an antireflection layer, in the outer surface of one or both of the electroconductive support body which acts as an electrode, and a counter electrode, between an electroconductive layer and a board | substrate, or in the middle of a board | substrate. For forming these functional layers, a coating method, a vapor deposition method, a bonding method, or the like can be used depending on the material.
[0116]
In the photoelectrochemical cell of the present invention, it is preferable to seal the side surface with a polymer, an adhesive or the like in order to prevent the deterioration of the respective constituents and the volatilization of the contents.
[0117]
The photoelectrochemical cell of the present invention has basically the same configuration as that of the photoelectric conversion element, and is configured to connect the photoelectric conversion element to an external circuit via a lead wire or the like so that work is performed in the external circuit. Is. As the external circuit itself connected to the conductive support and the counter electrode via a lead wire or the like, a known one can be used. Further, the photoelectrochemical cell of the present invention can basically have the same module structure as a conventional solar cell module. The solar cell module generally has a structure in which a cell is formed on a support substrate such as metal or ceramic, and the cell is covered with a filling resin or protective glass, and light is taken in from the opposite side of the support substrate. A transparent material such as tempered glass can be used for the support substrate, and a cell can be formed thereon so that light is taken in from the transparent support substrate side. Specifically, a module structure called a super straight type, a substrate type, a potting type, a substrate integrated module structure used in amorphous silicon solar cells, etc. are known, and the photoelectrochemical cell of the present invention is also used and used Depending on the location and environment, these module structures can be selected as appropriate. Specifically, it is preferable to apply the structure and aspect described in Japanese Patent Application Laid-Open No. 2000-268892.
[0118]
[Non-aqueous secondary battery]
Hereinafter, the non-aqueous secondary battery of the present invention using the electrolyte composition of the present invention will be described.
The nonaqueous secondary battery of the present invention is characterized by including the electrolyte composition of the present invention. Since the nonaqueous secondary battery of the present invention contains the electrolyte composition of the present invention, it exhibits excellent cycle performance without greatly reducing the capacity.
[0119]
When the electrolyte composition of the present invention is used for a non-aqueous secondary battery, the positive electrode active material may be a transition metal oxide capable of reversibly inserting and releasing lithium ions, but a lithium-containing transition metal oxide is particularly preferable. Preferable lithium-containing transition metal oxide positive electrode active materials used in the present invention include oxides containing lithium-containing Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Mo, and W. Alkali metals other than lithium (elements of the first (IA) group and second (IIA) group of the periodic table) and / or Al, Ga, In, Ge, Sn, Pb, Sb, Bi, Si, P , B, etc. may be mixed. The mixing amount is preferably 0 to 30 mol% with respect to the transition metal.
[0120]
More preferable lithium-containing transition metal oxide positive electrode active materials used in the present invention include lithium compounds / transition metal compounds (wherein transition metals are Ti, V, Cr, Mn, Fe, Co, Ni, Mo, W) It is preferable to synthesize by mixing so that the total molar ratio of at least one selected from (1) is 0.3 to 2.2.
[0121]
As a particularly preferable lithium-containing transition metal oxide positive electrode active material used in the present invention, a lithium compound / transition metal compound (where the transition metal is at least one selected from V, Cr, Mn, Fe, Co, Ni) It is preferable to synthesize by mixing so that the total molar ratio of
[0122]
A particularly preferred lithium-containing transition metal oxide positive electrode active material used in the present invention is Li_gM^ThreeO₂(M^ThreeIs a material containing one or more selected from Co, Ni, Fe and Mn, g = 0 to 1.2), or Li_hM^Four ₂O_Four(M^FourIs a material having a spinel structure represented by Mn, h = 0 to 2), and M^ThreeAnd M^FourFor example, Al, Ga, In, Ge, Sn, Pb, Sb, Bi, Si, P, or B may be mixed in addition to the transition metal. The mixing amount is preferably 0 to 30 mol% with respect to the transition metal.
[0123]
As the most preferable lithium-containing transition metal oxide positive electrode active material used in the present invention, Li_gCoO₂, Li_gNiO₂, Li_gMnO₂, Li_gCo_jNi_(1-j)O₂, Li_hMn₂O_Four(Where g = 0.02 to 1.2, j = 0.1 to 0.9, h = 0 to 2). Here, said g value is a value before the start of charging / discharging, and it increases / decreases by charging / discharging.
[0124]
The positive electrode active material can be synthesized by a known method such as a method of mixing and baking a lithium compound and a transition metal compound or a solution reaction, but a baking method is particularly preferable.
[0125]
The average particle size of the positive electrode active material used in the present invention is not particularly limited, but is preferably 0.1 to 50 μm. Although it does not specifically limit as a specific surface area, it is 0.01-50m in BET method²/ G is preferred. The pH of the supernatant when 5 g of the positive electrode active material is dissolved in 100 ml of distilled water is preferably 7 or more and 12 or less.
[0126]
To obtain a predetermined particle size, a well-known pulverizer or classifier can be used. For example, a mortar, a ball mill, a vibration ball mill, a vibration mill, a satellite ball mill, a planetary ball mill, a swirling air flow type jet mill, a sieve, or the like is used. The positive electrode active material obtained by firing may be used after washing with water, an acidic aqueous solution, an alkaline aqueous solution, or an organic solvent.
[0127]
One of the negative electrode active materials used in the present invention is a carbonaceous material capable of occluding and releasing lithium. The carbonaceous material is a material substantially made of carbon. Examples thereof include carbonaceous materials obtained by baking various synthetic resins such as artificial pitches such as petroleum pitch, natural graphite, and vapor-grown graphite, and PAN-based resins and furfuryl alcohol resins. Furthermore, various carbon fibers such as PAN-based carbon fiber, cellulose-based carbon fiber, pitch-based carbon fiber, vapor-grown carbon fiber, dehydrated PVA-based carbon fiber, lignin carbon fiber, glassy carbon fiber, activated carbon fiber, mesophase micro Examples thereof include spheres, graphite whiskers, and flat graphite.
These carbonaceous materials can be divided into non-graphitizable carbon materials and graphite-based carbon materials depending on the degree of graphitization. Further, the carbonaceous material preferably has the surface spacing, density, and crystallite size described in JP-A-62-222066, JP-A-2-6856, and 3-45473.
The carbonaceous material does not need to be a single material, and a mixture of natural graphite and artificial graphite described in JP-A-5-90844, graphite having a coating layer described in JP-A-6-4516, or the like is used. You can also.
[0128]
Other examples of the negative electrode active material that can be used in the present invention include oxides and / or chalcogenides.
In particular, amorphous oxides and / or chalcogenides are preferable. The term “amorphous” as used herein refers to an X-ray diffraction method using CuKα rays that has a broad scattering band having a peak in the region of 20 ° to 40 ° in terms of 2θ values. You may have. Preferably, the strongest intensity among the crystalline diffraction lines seen at 2θ values from 40 ° to 70 ° is 100 of the diffraction line intensities at the apexes of the broad scattering bands seen from 2 ° values to 20 ° to 40 °. It is not more than twice, more preferably not more than 5 times, and particularly preferably not having a crystalline diffraction line.
[0129]
In the present invention, amorphous oxides of metalloid elements and / or chalcogenides are preferable, and elements in groups 13 (IIIB) to 15 (VB) of the periodic table, Al, Ga, Si, Sn, Ge, Pb Sb, Bi, or an oxide or chalcogenide composed of a combination of two or more thereof is selected.
[0130]
For example, Ga₂O_Three, SiO, GeO, SnO, SnO₂, PbO, PbO₂, Pb₂O_Three, Pb₂O_Four, Pb_ThreeO_Four, Sb₂O_Three, Sb₂O_Four, Sb₂O_Five, Bi₂O_Three, Bi₂O_Four, SnSiO_Three, GeS, SnS, SnS₂, PbS, PbS₂, Sb₂S_Three, Sb₂S_Five, SnSiS_ThreeEtc. are preferable. These are also complex oxides with lithium oxide, such as Li₂SnO₂It may be.
[0131]
In the negative electrode material in the present invention, an amorphous oxide centered on Sn, Si, and Ge is more preferable, and among them, an amorphous oxide represented by the following general formula (VI) is preferable.
General formula (VI)
SnM¹ _dM² _eO_f
Where M¹Represents at least one element selected from Al, B, P and Ge;²Represents at least one element selected from Group 1 (IA) elements, Group 2 (IIA) elements, Group 3 (IIIA) elements and halogen elements in the periodic table, and d is 0.2 or more and 2 or less. Number, e is a number from 0.01 to 1 and 0.2 <d + e <2, and f is a number from 1 to 6.
[0132]
Examples of the amorphous oxide mainly composed of Sn include the following compounds, but the present invention is not limited thereto.
C-1 SnSiO_Three
C-2 Sn_0.8Al_0.2B_0.3P_0.2Si_0.5O_3.6
C-3 SnAl_0.4B_0.5Cs_0.1P_0.5O_3.65
C-4 SnAl_0.4B_0.5Mg_0.1P_0.5O_3.7
C-5 SnAl_0.4B_0.4Ba_0.08P_0.4O_3.28
C-6 SnAl_0.4B_0.5Ba_0.08Mg_0.08P_0.3O_3.26
C-7 SnAl_0.1B_0.2Ca_0.1P_0.1Si_0.5O_3.1
C-8 SnAl_0.2B_0.4Si_0.4O_2.7
C-9 SnAl_0.2B_0.1Mg_0.1P_0.1Si_0.5O_2.6
C-10 SnAl_0.3B_0.4P_0.2Si_0.5O_3.55
C-11 SnAl_0.3B_0.4P_0.5Si_0.5O_4.3
C-12 SnAl_0.1B_0.1P_0.3Si_0.6O_3.25
C-13 SnAl_0.1B_0.1Ba_0.2P_0.1Si_0.6O_2.95
C-14 SnAl_0.1B_0.1Ca_0.2P_0.1Si_0.6O_2.95
C-15 SnAl_0.4B_0.2Mg_0.1Si_0.6O_3.2
C-16 SnAl_0.1B_0.3P_0.1Si_0.5O_3.05
C-17 SnB_0.1K_0.5P_0.1SiO_3.65
C-18 SnB_0.5F_0.1Mg_0.1P_0.5O_3.05
For the amorphous oxide and / or chalcogenite in the present invention, either a firing method or a solution method can be adopted, but a firing method is more preferable. In the firing method, it is preferable to obtain an amorphous oxide and / or chalcogenite by thoroughly mixing oxides, chalcogenites or compounds of the corresponding elements and then firing them. These can be prepared by a known method.
[0133]
The average particle size of the negative electrode material used in the present invention is preferably 0.1 to 60 μm. To obtain a predetermined particle size, a well-known pulverizer or classifier is used. For example, a mortar, a ball mill, a sand mill, a vibrating ball mill, a satellite ball mill, a planetary ball mill, a swirling air flow type jet mill, a sieve, or the like is used. When pulverizing, wet pulverization in the presence of water or an organic solvent such as methanol can be performed as necessary. In order to obtain a desired particle size, classification is preferably performed. The classification method is not particularly limited, and a sieve, an air classifier, or the like can be used as necessary. Classification can be used both dry and wet.
[0134]
In the present invention, a negative electrode material that can be used in combination with an amorphous oxide negative electrode material centering on Sn, Si, and Ge includes a carbon material that can occlude and release lithium ions or lithium metal, lithium, and a lithium alloy. And metals that can be alloyed with lithium.
[0135]
An aprotic organic solvent is added to the electrode mixture used in the present invention in addition to a conductive agent, a binder, a filler, and the like.
[0136]
The conductive agent may be anything as long as it is an electron conductive material that does not cause a chemical change in a configured battery. Usually, natural graphite (scale-like graphite, scale-like graphite, earth-like graphite, etc.), artificial graphite, carbon black, acetylene black, ketjen black, carbon fiber and metal powder (copper, nickel, aluminum, silver (Japanese Patent Laid-Open No. Sho 63- 148554), etc.), metal fibers or polyphenylene derivatives (Japanese Patent Laid-Open No. 59-20971) can be contained as one kind or a mixture thereof. The combined use of graphite and acetylene black is particularly preferred. The addition amount is preferably 1 to 50% by mass, and particularly preferably 2 to 30% by mass. In the case of carbon or graphite, 2 to 15% by mass is particularly preferable.
[0137]
In the present invention, a binder for holding the electrode mixture can be used. Examples of the binder include polysaccharides, thermoplastic resins, and polymers having rubber elasticity. Preferred binders include starch, carboxymethyl cellulose, cellulose, diacetyl cellulose, methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, sodium alginate, polyacrylic acid, polyacrylic acid Na, polyvinyl phenol, polyvinyl methyl ether, polyvinyl alcohol, polyvinyl pyrrolidone. Water-soluble polymers such as polyacrylonitrile, polyacrylamide, polyhydroxy (meth) acrylate, styrene-maleic acid copolymer, polyvinyl chloride, polytetrafluoroethylene, polyvinylidene fluoride, tetrafluoroethylene-hexafluoropropylene copolymer, Vinylidene fluoride-tetrafluoroethylene-hexafluoropropylene copolymer, polyethylene, polypropylene (Meth) acrylic acid ester copolymers containing (meth) acrylic acid esters such as ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, polyvinyl acetal resin, methyl methacrylate, 2-ethylhexyl acrylate, (Meth) acrylic acid ester-acrylonitrile copolymer, polyvinyl ester copolymer containing vinyl ester such as vinyl acetate, styrene-butadiene copolymer, acrylonitrile-butadiene copolymer, polybutadiene, neoprene rubber, fluororubber, poly Emulsions (latex) of ethylene oxide, polyester polyurethane resin, polyether polyurethane resin, polycarbonate polyurethane resin, polyester resin, phenol resin, epoxy resin, etc. Rui can be mentioned suspension. Particularly preferred are polyacrylate ester latex, carboxymethylcellulose, polytetrafluoroethylene, and polyvinylidene fluoride.
These binders can be used alone or in combination. When the amount of the binder added is small, the holding power and cohesion of the electrode mixture is weak. If the amount is too large, the electrode volume increases and the capacity per electrode unit volume or unit mass decreases. For this reason, the addition amount of the binder is preferably 1 to 30% by mass, and particularly preferably 2 to 10% by mass.
[0138]
The filler may be any fibrous material that does not cause a chemical change in the battery. Usually, olefin polymers such as polypropylene and polyethylene, fibers such as glass and carbon are used. Although the addition amount of a filler is not specifically limited, 0-30 mass% is preferable.
[0139]
The electrolyte composition of the present invention can be used in combination with a separator to ensure safety. The separator used in combination for ensuring safety needs to have a function of blocking the current by blocking the above gap at 80 ° C. or higher and blocking the current, and the blocking temperature is 90 ° C. or higher and 180 ° C. or lower. It is preferable.
[0140]
The shape of the holes of the separator is usually circular or elliptical, and the size is 0.05 to 30 μm, preferably 0.1 to 20 μm. Furthermore, it may be a rod-like or irregular-shaped hole as in the case of making by a stretching method or a phase separation method. The ratio occupied by these gaps, that is, the porosity, is 20 to 90%, preferably 35 to 80%.
[0141]
These separators may be a single material such as polyethylene or polypropylene, or two or more composite materials. In particular, a laminate in which two or more kinds of microporous films having different pore diameters, porosity, pore closing temperatures, and the like are laminated is particularly preferable.
[0142]
As the positive / negative current collector, an electron conductor that does not cause a chemical change in the constructed battery is used.
As the positive electrode current collector, in addition to aluminum, stainless steel, nickel, titanium and the like, those obtained by treating the surface of aluminum or stainless steel with carbon, nickel, titanium or silver are preferable, and aluminum, aluminum are particularly preferable. It is an alloy.
As the current collector for the negative electrode, copper, stainless steel, nickel, and titanium are preferable, and copper and copper alloys are particularly preferable.
[0143]
The current collector is usually in the form of a film sheet, but a net, a punched one, a lath, a porous body, a foam, a fiber group molded body, or the like can also be used. The thickness is not particularly limited, but is 1 to 500 μm. Moreover, it is also desirable that the current collector surface be roughened by surface treatment.
[0144]
The shape of the battery can be applied to any of sheets, corners, cylinders and the like. The positive electrode active material and the negative electrode material mixture are mainly used after being applied (coated), dried and compressed on the current collector. Examples of the coating method include a reverse roll method, a direct roll method, a blade method, a knife method, an extrusion method, a curtain method, a gravure method, a bar method, a dip method, and a squeeze method. Of these, the blade method, knife method and extrusion method are preferred. The application is preferably performed at a speed of 0.1 to 100 m / min. Under the present circumstances, the surface state of a favorable coating layer can be obtained by selecting the said application | coating method according to the solution physical property and dryness of a mixture. The application may be performed one side at a time or simultaneously on both sides.
[0145]
The application may be continuous, intermittent, or striped. The thickness, length and width of the coating layer are determined by the shape and size of the battery, but the thickness of the coating layer on one side is preferably 1 to 2000 μm in a compressed state after drying.
[0146]
As a method for drying and dehydrating the electrode sheet coated product, a method in which hot air, vacuum, infrared rays, far infrared rays, electron beams and low-humidity air are used alone or in combination can be used. The drying temperature is preferably in the range of 80 to 350 ° C, particularly preferably in the range of 100 to 250 ° C. The water content is preferably 2000 ppm or less for the entire battery, and preferably 500 ppm or less for each of the positive electrode mixture, the negative electrode mixture and the electrolyte. As a sheet pressing method, a generally adopted method can be used, but a calendar pressing method is particularly preferable. The press pressure is not particularly limited, but is 0.2 to 3 t / cm.²Is preferred. The press speed of the calendar press method is preferably 0.1 to 50 m / min, and the press temperature is preferably room temperature to 200 ° C. The ratio of the negative electrode sheet width to the positive electrode sheet is preferably 0.9 to 1.1, particularly preferably 0.95 to 1.0. The content ratio of the positive electrode active material and the negative electrode material varies depending on the compound type and the mixture formulation.
[0147]
After stacking positive and negative electrode sheets via a separator, the sheet is processed into a sheet-like battery as it is, or after being folded and inserted into a rectangular can, the can and the sheet are electrically connected, and then the electrolyte of the present invention The composition is injected and a rectangular battery is formed using a sealing plate. In addition, after the positive and negative electrode sheets are overlapped and wound through a separator, inserted into a cylindrical can, the can and the sheet are electrically connected, the electrolyte composition of the present invention is injected, and the sealing plate is Used to form a cylinder battery. At this time, the safety valve can be used as a sealing plate. In addition to the safety valve, various conventionally known safety elements may be provided. For example, a fuse, bimetal, PTC element, or the like is used as the overcurrent prevention element.
[0148]
In addition to the safety valve, as a countermeasure against the increase in internal pressure of the battery can, a method of cutting the battery can, a method of cracking the gasket, a method of cracking the sealing plate, or a method of cutting the lead plate can be used. Further, the charger may be provided with a protection circuit incorporating measures against overcharge and overdischarge, or may be connected independently.
[0149]
In addition, as a measure against overcharging, a method of cutting off current by increasing the battery internal pressure can be provided. At this time, a compound for increasing the internal pressure can be contained in the mixture or the electrolyte. Examples of compounds used to increase internal pressure include Li₂CO_Three, LiHCO_Three, Na₂CO_ThreeNaHCO_Three, CaCO_Three, MgCO_ThreeAnd carbonates.
[0150]
For the can and lead plate, a metal or alloy having electrical conductivity can be used. For example, metals such as iron, nickel, titanium, chromium, molybdenum, copper, and aluminum, or alloys thereof are used.
[0151]
As a method for welding the cap, can, sheet, and lead plate, a known method (for example, direct current or alternating current electric welding, laser welding, or ultrasonic welding) can be used. As the sealing agent for sealing, a conventionally known compound or mixture such as asphalt can be used.
[0152]
The use of the non-aqueous secondary battery of the present invention is not particularly limited. For example, when mounted on an electronic device, a notebook computer, a pen input personal computer, a mobile personal computer, an electronic book player, a mobile phone, a cordless phone, a pager, Handy terminal, portable fax, portable copy, portable printer, headphone stereo, video movie, LCD TV, handy cleaner, portable CD, minidisc, electric shaver, transceiver, electronic notebook, calculator, memory card, portable tape recorder, radio, backup Examples include power supplies and memory cards. Other consumer products include automobiles, electric vehicles, motors, lighting equipment, toys, game equipment, road conditioners, watches, strobes, cameras, medical equipment (such as pacemakers, hearing aids, and shoulder grinders). Furthermore, it can be used for various military use and space use. Moreover, it can also combine with a solar cell.
[0153]
【Example】
Examples of the present invention will be described below, but the present invention is not limited to these examples.
Example 1 Synthesis Example of Polyalkylene Oxide
Synthesis of exemplary compound P-1
[0154]
Embedded image
[0155]
(1) Synthesis of intermediate M-1
Dimethyl malonate; 58.1 g (439 mmol) dissolved in methanol, sodium methoxide in 28% methanol solution; 88 ml was added, and 97.2 g (439 mmol) of 1-bromodecane was added dropwise over 1 hour, followed by refluxing for 8 hours. did. The reaction mixture was poured into diluted hydrochloric acid, neutralized, and extracted with ethyl acetate. The extracted solution was dried over magnesium sulfate and concentrated under reduced pressure, and the residue was distilled under reduced pressure to obtain 41 g (399 Pa (3 mmHg) / 82 ° C. fraction).
[0156]
(2) Synthesis of intermediate M-2
Lithium aluminum hydride (11 g, 289 mmol) was dispersed in 150 ml of diethyl ether, and a solution of M-1 (41 g, 170 mmol) dissolved in 50 ml of diethyl ether obtained in (1) was stirred for 2 hours while stirring at room temperature. It was dripped over. After the dropwise addition, after refluxing for 3 hours, the reaction mixture was slowly poured into dilute hydrochloric acid / ice to acidify the solution and then extracted. The extract was dried over magnesium sulfate, and the solvent was distilled off under reduced pressure to obtain 31 g of an oily crude product. The crude product was purified by silica gel column chromatography to obtain M-2 (14 g) as a colorless oil.
[0157]
(3) Synthesis of intermediate M-4
M-2 (13.85 g, 64 mmol) and M-3 (6.86 g, 64 mmol) obtained above were dispersed in 50 ml of toluene, 12 g of paratoluenesulfonic acid was added, and the mixture was heated to reflux for 5 hours while distilling off water. did. The reaction mixture was poured into 100 ml of water added with 10 g of potassium carbonate, extracted with ethyl acetate, the extract was dried, and the solvent was evaporated under reduced pressure. The residue was recrystallized from acetonitrile to obtain 7 g of the target M-4 as crystals.
[0158]
(4) Synthesis of P-1
M-4 (5 g, 16.4 mmol) obtained above and polymer MP-1 (3 g) were dispersed in 50 ml of acetonitrile and 20 ml of dimethylacetamide and reacted at 80 ° C. for 10 hours. The solvent was distilled off from the reaction mixture at 120 ° C. under reduced pressure to obtain 7.8 g of a polyalkylene oxide P-1 having a liquid crystalline side chain as a target product.
[0159]
(Example 2) Photoelectrochemical cell
2-1. Preparation of titanium dioxide dispersion
Zirconia beads with a Teflon-coated stainless steel vessel with an inner volume of 200 ml and titanium dioxide (Nippon Aerosil Degussa P-25) 15 g, water 45 g, dispersant (Aldrich Triton X-100) 1 g, 0.5 mm diameter 30 g (manufactured by Nikkato Co., Ltd.) was added and dispersed for 2 hours at 1500 rpm using a sand grinder mill (manufactured by Imex). The zirconia beads were filtered off from the dispersion. In this case, the average particle diameter of titanium dioxide was 2.5 μm. The particle size at this time is measured with a master sizer manufactured by MALVERN.
[0160]
2-2. TiO with adsorbed dye₂Production of electrode (electrode A)
The above dispersion was applied to the conductive surface side of conductive glass coated with tin oxide doped with fluorine (TCO glass-U manufactured by Asahi Glass cut into a size of 20 mm × 20 mm) using a glass rod. At this time, adhesive tape was applied to a part of the conductive surface side (3 mm from the end) to form a spacer, and glass was arranged so that the adhesive tape came to both ends, and 8 sheets were applied at a time. After application, the adhesive tape was peeled off and air-dried at room temperature for 1 day. Next, this glass was put into an electric furnace (a muffle furnace FP-32 manufactured by Yamato Scientific Co., Ltd.) and baked at 450 ° C. for 30 minutes. After this glass was taken out and cooled, an ethanol solution of the dye (Exemplary Compound R-1) (3 × 10^-FourMol / liter) for 3 hours. The dyed glass was immersed in 4-tert-butylpyridine for 15 minutes, then washed with ethanol and air dried. The thickness of the photosensitive layer thus obtained is 10 μm, and the coating amount of the semiconductor fine particles is 20 g / m.²It was. The surface resistance of the conductive glass was about 30Ω / □.
[0161]
2-3. Production of photoelectrochemical cell
Dye-sensitized TiO prepared as described above₂To an electrode substrate (1 cm × 1 cm), an acetonitrile solution of the electrolyte composition of the present invention shown in Table 1 below or a comparative electrolyte composition (E-102 to E-112) (acetonitrile is the same mass as the electrolyte composition). Apply TiO 2 under reduced pressure at 60 ° C₂Acetonitrile was distilled off while soaking into the electrode. A photoelectrochemical cell (samples B-102 to B-112) was obtained by superimposing platinum-deposited glass of the same size on these electrodes. In addition, the electrolytic solution using the solvent (E-101 in Table 1) is the same dye-sensitized TiO as described above.₂A platinum-deposited glass of the same size as the electrode is superimposed on an electrode substrate (2 cm × 2 cm), and then the electrolyte is infiltrated into the gap between the two glasses using a capillary phenomenon, so that a photoelectrochemical cell (sample B- 101).
[0162]
According to this example, as shown in FIG. 2, the conductive glass 1 (the conductive layer 3 is formed on the glass 2), the photosensitive layer 4 (TiO 2 adsorbed with the dye)₂Layer), the electrolyte layer 5, the platinum layer 6 serving as the counter electrode, and the glass 7 were sequentially laminated.
[0163]
[Table 1]
[0164]
Embedded image
[0165]
2-4. Measurement of photoelectric conversion efficiency
By passing light from a 500 W xenon lamp (made by Ushio) through an AM1.5 filter (made by Oriel) and a sharp cut filter (KenkoL-41), simulated sunlight containing no ultraviolet rays is generated, and the intensity of this light is set to 100 mW. / Cm²Adjusted.
[0166]
Alligator clips are connected to the conductive glass and platinum-deposited glass of the above-described photoelectrochemical cell, respectively, and simulated sunlight is irradiated at 70 ° C., and the generated electricity is supplied to a current-voltage measuring device (Keutley SMU238 type). Measured. The open-circuit voltage (Voc), short-circuit current density (Jsc), form factor (FF) [= maximum output / (open-circuit voltage × short-circuit current)], conversion efficiency (η) and constant temperature obtained by this Table 2 collectively shows the reduction rate of the short-circuit current density after aging for 400 hours under constant humidity (60 ° C., 70% RH).
[0167]
[Table 2]
[0168]
A photoelectrochemical cell (sample B-101) using a comparative electrolyte using a solvent has very poor durability because the solvent evaporates. In addition, batteries (samples B-102 and B-103) using the molten salts RE-1 and RE-2 as comparative compounds have little deterioration over time, but have insufficient photoelectric conversion performance. On the other hand, the battery using the electrolyte composition of the present invention is excellent in both initial performance such as short-circuit current density and conversion efficiency, and durability. Such an effect was seen when any dye was used.
[0169]
Example 3 Lithium secondary battery
3-1. Production of positive electrode sheet
LiCoO as positive electrode active material₂43 parts by mass, 2 parts by mass of graphite flakes, 2 parts by mass of acetylene black, 3 parts by mass of polyacrylonitrile as a binder, and a slurry obtained by kneading 100 parts by mass of acrylonitrile as a medium with a thickness of 20 μm After coating with aluminum foil using an extrusion coater, drying and compression molding with a calendar press, an aluminum lead plate is welded to the end, and the positive electrode is 95 μm thick, 54 mm wide x 49 mm long A sheet was made.
[0170]
3-2. Production of negative electrode sheet
43 parts by mass of mesophase pitch-based carbon material (Petka) as a negative electrode active material, 2 parts by mass of acetylene black and 2 parts by mass of graphite as a conductive agent, and 3 parts by mass of polyacrylonitrile as a binder are added. Then, 100 parts by mass of N-methylpyrrolidone was kneaded as a medium to obtain a negative electrode mixture slurry.
The negative electrode mixture slurry was applied to a copper foil having a thickness of 10 μm using an extrusion coater, and after drying, compression molding was performed by a calendar press machine to produce a negative electrode sheet having a thickness of 46 μm, a width of 55 mm × a length of 50 mm. . A nickel lead plate was welded to the end of the negative electrode sheet, and then heat treated at 230 ° C. for 1 hour in dry air having a dew point of −40 ° C. or lower. The heat treatment was performed using a far infrared heater.
[0171]
3-3. Fabrication of sheet battery
Each of the negative electrode sheet and the positive electrode sheet was dehydrated and dried at 230 ° C. for 30 minutes in dry air having a dew point of −40 ° C. or less. In a dry atmosphere, a dehydrated and dried positive electrode sheet having a width of 54 mm × length of 49 mm, a separator (polyethylene porous film) cut into a width of 60 mm × length of 60 mm and a nonwoven fabric are laminated, and the composition shown in Table 3 below is formed on the nonwoven fabric. A solution prepared by dissolving the electrolyte composition (E-202 to 212) in the same amount of acetonitrile was applied, and acetonitrile was distilled off at 50 ° C. under reduced pressure. Moreover, the electrolyte solution (E-201) using a solvent was made to soak into a nonwoven fabric as it was. A negative electrode sheet having a width of 55 mm and a length of 50 mm was laminated thereon, and an outer covering material made of a laminate film of polyethylene (50 μm) -polyethylene terephthalate (50 μm) was used, and the four edges were heat-sealed under vacuum. Sealed to prepare a sheet type battery (Sample B-201 to 212).
[0172]
According to this example, as shown in FIG. 3, a sheet type battery was produced in which a negative electrode sheet 33 provided with a negative electrode terminal 35, a polymer solid electrolyte 32, and a positive electrode sheet 31 provided with a positive electrode terminal 34 were sequentially laminated. .
[0173]
[Table 3]
[0174]
3-4. Battery performance evaluation
About the sheet type battery produced by the above method, the current density is 1.3 mA / cm.²The charge and discharge were repeated 30 times under the conditions of a charge end voltage of 4.2 V and a discharge end voltage of 2.6 V, and the discharge capacity at the 30th cycle was determined. This was examined for five batteries of the same formulation, and the average was taken as the capacity of the battery. Thus, the capacity | capacitance of each battery was calculated | required and the relative capacity | capacitance with respect to sample B-201 was calculated | required. Further, the discharge capacity at the 200th cycle of each battery was obtained, and the ratio to the discharge capacity at the 10th cycle was calculated and expressed as the cycle capacity. The respective values are shown in Table 4.
[0175]
[Table 4]
[0176]
From the above results, it can be seen that the electrolyte composition of the present invention has improved cycle performance without a significant decrease in capacity.
[0177]
【The invention's effect】
According to the present invention, there is provided a polymer liquid crystalline electrolyte composition that is substantially non-volatile and excellent in charge transporting ability, and further includes the electrolyte composition, which is an electric material having excellent durability and ion conductivity. It is possible to provide a chemical battery, a photoelectrochemical battery excellent in durability and photoelectric conversion characteristics, and a non-aqueous secondary battery excellent in cycle characteristics without reducing the battery capacity.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram illustrating an example of a photoelectric conversion element of the present invention.
2 is a cross-sectional view showing the configuration of the photoelectrochemical cell produced in Example 2. FIG.
3 is a schematic view of a sheet type battery produced in Example 3. FIG.
[Explanation of symbols]
1 Conductive glass
2 Glass
3 Conductive layer
4 Photosensitive layer (Dye-adsorbed TiO₂layer)
5 Electrolyte layer
6 Platinum layer
7 Glass
10 Photoelectric conversion element
12 Conductive layer
14 Undercoat layer
16 Photosensitive layer
18 Charge transfer layer
20 Counter electrode conductive layer
24 Semiconductor layer
26 Substrate
28 substrates
s Semiconductor fine particles
d Dye
t Charge transport material
31 Positive electrode sheet
32 Polymer solid electrolyte
33 Negative electrode sheet
34 Positive terminal
35 Negative terminal

Claims (15)

Polyalkylene oxide backbones, polyalkylene oxides to organic and liquid crystalline side chain of the side chain pairs and an ion containing a structure represented by the cationic site or anionic sites and the following formula (IV),
And an electrolyte composition comprising carrier ions .
(In Formula (IV), Y ₁₁₁ represents a divalent, 6-membered aromatic group, 5-membered heterocyclic group, 6-membered heterocyclic group, or a condensed ring group thereof. Q ₁₂₁ and Q ₁₃₁ Each represents a divalent linking group or a single bond, n represents 1, 2 or 3, and when n is 2 or 3, a plurality of Y ₁₁₁ , Q ₁₂₁ and Q ₁₃₁ may be the same. May be different.) Y ₁₁₁ The electrolyte composition according to claim 1, wherein is one of divalent groups represented by the following formula.
Y ₁₁₁ The electrolyte composition according to claim 1, wherein is one of divalent groups represented by the following formula.
Q ₁₂₁ And Q ₁₃₁ Are —CH═CH—, —CH═N—, —N═N—, —N (O) ═N—, —COO—, —COS—, —CONH—, —COCH, respectively. ₂ -, -CH ₂ CH ₂ -, -OCH ₂ -, -CH ₂ NH-, -CH ₂ -, -CO-, -O-, -S-, -NH-,-(CH ₂ ) _1-3 -, -CH = CH-COO-, -CH = CH-CO-,-(C≡C) _1-3 The electrolyte composition according to any one of claims 1 to 3, which is-, a combination of these divalent linking groups, or a single bond. Q ₁₂₁ And Q ₁₃₁ Are each -CH ₂ CH ₂ -, -OCH ₂ -, -CH ₂ The electrolyte composition according to any one of claims 1 to 3, which is-, -O-, a combination of these divalent linking groups, or a single bond. The electrolyte composition according to any one of claims 1 to 5, wherein the polyalkylene oxide includes a structure represented by the following formula (I).
(Formula (in I), A represents the side chain, Y table to the counter ion.) The electrolyte composition according to any one of claims 1 to 6 , wherein the polyalkylene oxide includes a structure represented by the following formula (II).
(In formula (II), R represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group.) The electrolyte composition according to claim 1, wherein the side chain is a liquid crystalline anion. The electrolyte composition according to claim 1, wherein the side chain is a liquid crystalline cation. The electrolyte composition according to claim 8 , wherein the counter ion of the side chain is an alkali metal ion. The counter ion of the side chain is an iodine anion or an anion in which at least one selected from sulfonamide, disulfonimide, N-acylsulfonamide, carboxylic acid, sulfonic acid, alcohol, active methylene, and active methine is dissociated The electrolyte composition according to claim 9 . The electrolyte composition according to claim 1, wherein the counter ion is the carrier ion. An electrochemical cell comprising the electrolyte composition according to any one of claims 1 to 12 . A photoelectrochemical cell comprising a charge transfer layer comprising the electrolyte composition according to any one of claims 1 to 12 , a photosensitive layer comprising a semiconductor sensitized with a dye, and a counter electrode. . A non-aqueous secondary battery comprising the electrolyte composition according to any one of claims 1 to 12 .