WO2006103757A1

WO2006103757A1 - Coolant composition for fuel cell

Info

Publication number: WO2006103757A1
Application number: PCT/JP2005/006050
Authority: WO
Inventors: Hiroshi Egawa; Hidemi Kado
Original assignee: Shishiai-Kabushikigaisha
Priority date: 2005-03-30
Filing date: 2005-03-30
Publication date: 2006-10-05
Also published as: JP5027656B2; JPWO2006103757A1

Abstract

A coolant composition for fuel cells which prevents a base from oxidizing and thus generating an ionic substance and thereby maintains low conductivity over long. It further has excellent antifreezing properties. The composition is characterized by containing a compound represented by a structural formula which includes a cyclic atomic arrangement having a carbonyl group introduced therein and having an unsaturated bond therein.

Description

Coolant composition for fuel cell

Technical field

TECHNICAL FIELD [0001] The present invention relates to a coolant composition used for cooling a fuel cell, in particular, a fuel cell for automobiles. Specifically, the conductivity of the composition is a fuel excellent in maintaining a low conductivity over a long period of time. The present invention relates to a coolant composition for a battery.

Background art

[0002] A fuel cell is generally configured as a cell stack having a structure in which a large number of unit cells and separators, which are power generation units, are stacked. Stack power is generated during power generation, so a cooling plate was inserted every several cells to cool the cell stack.

[0003] A cooling fluid passage is formed inside the cooling plate, and the stack is cooled by the flow of the cooling fluid through the passage.

[0004] In this way, the coolant in the fuel cell performs power generation! /, And circulates in the stack to cool the stack. Therefore, if the electrical conductivity of the coolant is high, the electricity generated in the stack Flows to the coolant side and loses electricity, reducing the power generation in the fuel cell.

[0005] Therefore, conventional fuel cell coolants have low electrical conductivity, in other words, high electrical insulation! Pure water was used.

However, when considering, for example, a fuel cell for automobiles and a fuel cell for household cogeneration systems, the coolant is lowered to the ambient temperature when not operating. In particular, when there is a possibility of use below freezing point, there was a risk that the performance of the fuel cell would be impaired, such as freezing in pure water and damage to the cooling plate due to volume expansion of the coolant.

[0007] Under such circumstances, a low conductivity and antifreeze are required for a coolant of a fuel cell, particularly an automobile fuel cell.

[0008] As a fuel cell coolant composition capable of meeting the above requirements, conventionally, a base composed of a mixed solution of water and darikols, and an ammonia that maintains the conductivity of the coolant at a low conductivity. A material containing an alkaline additive has been proposed (see Patent Document 1).

Patent Document 1: Japanese Patent Laid-Open No. 2001-164244 Disclosure of the invention

Problems to be solved by the invention

[0009] However, bases such as glycols in the composition are oxidized during the operation of the fuel cell to produce an ionic substance. For this reason, the mass of ionic substances in the cooling liquid increases with long-term use, and as a result, the low conductivity of the cooling liquid cannot be maintained.

[0010] The present invention has been made in view of such circumstances, and by suppressing the formation of ionic substances due to oxidation of the base, it maintains a low conductivity over a long period of time and is antifreeze. It is an object of the present invention to provide a fuel cell coolant composition that is superior to the above.

Means for solving the problem

[0011] The fuel cell coolant composition of the present invention (hereinafter simply referred to as the composition) has a cyclic atomic arrangement in which a carbonyl group is introduced in the structural formula, and is unsaturated in the cyclic atomic arrangement. It is characterized by containing a compound in which a bond is present.

[0012] The base in this composition has one of low conductivity and non-freezing properties, specifically water, alcohols, glycols, and glycol ethers. What consists of 2 or more types of mixtures can be used.

[0013] Examples of alcohols include one or two or more selected from among methanol, ethanol, propanol, butanol, pentanol, hexanol, heptanol, and octanol.

[0014] Examples of glycols include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, 1,3-propanediol, 1,3-butanediol, 1,5-pentanediol, and hexylene glycol. The thing which consists of 1 type or 2 types or more can be mentioned.

[0015] Glycol ethers include polyoxyalkylene glycol alkyl ethers such as ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, triethylene glycol monomethyl ether ether, tetraethylene glycol monomethyl methanol ether, ethylene glycol monomethyl ether. Chinoleatenore, diethylene glycolenomonoeno chinoreatenore, triethyleneglycolenomonochinenoatenore, tetraethyleneglycolenore One or more selected from monoethino elenotere, ethyleneglycolole butylenoleatenore, diethyleneglycolole monobutinoleether, triethyleneglycolole butylenoleether, tetraethylene glycol monobutyl ether You can list things that consist of:

[0016] A compound having a cyclic atomic arrangement in which a carbonyl group is introduced into the structural formula in the above-mentioned base, and having an unsaturated bond in the cyclic atomic arrangement (hereinafter simply referred to as a compound! /, It is included. Since this compound has a function of effectively suppressing the formation of an ionic substance by the above-mentioned base acid, it is cooled to dilute the composition containing this compound to cool the fuel cell. When used as a liquid, the coolant will maintain a low conductivity over a long period of time.

[0017] As a compound having such a function, a compound having a cyclic atomic arrangement in which a carbo group is introduced into the structural formula and having an unsaturated bond in the cyclic atomic arrangement is particularly preferable. Although it is not limited, in particular, those having 3 to 35 carbon atoms in the cyclic atomic arrangement (especially 5 to: LO) force Effectively suppress the production of ionic substances by the base acid. It is preferable because of its excellent effect.

[0018] Specific examples of this compound include oxazolone, pyrazolone, jasmon, benzoquinone, pyrone, _Ίpyridone , uracil, tropone, trobolone, chromone, naphthoquinone, oxindole, phthalide, oxanthrone, anthrone, anthraquinone, alizarin, atalidone, and And their derivatives.

[0019] The above compound is desirably contained in the range of 0.01 to 20 parts by weight with respect to 100 parts by weight of the base. When the content of the compound is less than 0.01 parts by weight, when the content of the compound is insufficient to effectively suppress the formation of the ionic substance due to the oxidation of the base, the content of the compound exceeds 20 parts by weight. , You can not expect the effect of exceeding, it becomes uneconomical.

[0020] It should be noted that the composition of the present invention may contain, for example, an antifoaming agent or a coloring agent in addition to the above-mentioned components within the range not inhibiting the low conductivity of the composition! On the other hand, molybdate, tungstate, sulfate, nitrate, benzoate, amine, triazole, phosphate, and the like, which are other conventionally known anti-corrosive additives, can be used in combination.

Note that the present invention is not limited to the following examples, but is described in “Claims”. It is possible to change and implement freely within the specified range.

The invention's effect

The composition of the present invention contains a compound having a cyclic atomic arrangement in which a carbo group is introduced into the structural formula and having an unsaturated bond in the cyclic atomic arrangement. It is possible to effectively suppress the generation of ionic substances due to the acid of the agent, and to maintain a low conductivity over a long period of time.

Example

[0023] Hereinafter, the composition of the present invention will be described in more detail with reference to Examples. Table 1 below shows Example 1 in which 50% by weight of ethylene glycol and 50% by weight of ion-exchanged water were added as a base and 0.1% by weight of a-pyrone was added thereto. Example 2 was obtained by adding 1.7% by weight of hinokitiol (trobolone) to the agent.

[0024] In addition, an example in which only the above-mentioned base is effective is referred to as Comparative Example 1, and a case in which 1.0% by weight of furfuryl alcohol is added to the above-mentioned base is referred to as Comparative Example 2, and 5.0 to the above-mentioned base. Comparative Example 3 was obtained by adding wt% cinnamon alcohol.

[0025] [Table 1]

O o l £ ΛΓΗn I

O ○

t ID ^ ヽ —

o O

in

o 〇

ID LD

o O

ID 〇

[0026] The compositions of Examples 1 and 2 and Comparative Examples 1 to 3 were subjected to an oxidative deterioration test, and the conductivity (SZcm) after the test was measured. The results are shown in Table 2. The oxidative degradation test of each composition was conducted at 100 ° C for 168 hours.

[0027] [Table 2] Comparison ratio O 00

Example

ID C Subordinate Oxidation O

(LD J

CO

O

CO

CM CO

d

褂

[0028] From Table 2, the electrical conductivity of each composition after oxidative degradation is shown. The composition of Comparative Example 1 consisting only of the base material has an initial electrical conductivity of 0.2 after the oxidative degradation test. The conductivity was 43, and the fluctuation was as large as 42.8. It was confirmed that the conductivity was greatly increased due to oxidative degradation.

[0029] On the other hand, in the case of the composition of Comparative Example 2, the initial conductivity was 2.5, whereas the conductivity after the oxidative degradation test was 53, and the variation was compared with 50.5. It was confirmed that the increase in conductivity due to the oxidation degradation of the base larger than Example 1 was not suppressed at all, but rather the conductivity was increased. [0030] In the case of the composition of Comparative Example 3, the initial conductivity was 4.2, whereas the conductivity after the oxidative degradation test was 28, and the variation was 23.8. It was confirmed that the increase in conductivity due to oxidative degradation of the steel was somewhat suppressed.

[0031] On the other hand, in the composition of Example 1, the initial conductivity was 0.3, whereas the conductivity after the oxidation degradation test was 7.4. The fluctuation of the value was as small as 7.1, and it was confirmed that the increase in conductivity due to the deterioration of acidity of the base was effectively suppressed.

[0032] Further, with respect to the composition of Example 2, the initial conductivity was 3.6 and the conductivity after the oxidative degradation test was 4.9, and the variation was extremely small as 1.3. It was confirmed that the increase in electrical conductivity due to deterioration of the base due to acid and soot was effectively suppressed, and the antioxidant effect of the base in the composition was far better than expected.

[0033] From the above results, in the compositions according to Examples 1 and 2, the increase in electrical conductivity is extremely small despite being subjected to the oxidation deterioration test under severe conditions. Therefore, even when these compositions are diluted and applied as a fuel cell coolant, it is predicted that the production of ionic substances due to the oxidation of the base can be effectively suppressed. It can be expected to maintain low conductivity across the board.

Claims

The scope of the claims

[1] For a coolant composition for cooling a fuel cell,

A coolant composition for fuel cells, comprising a compound having a cyclic atomic arrangement in which a carbonyl group is introduced into the structural formula and having an unsaturated bond in the cyclic atomic arrangement.

[2] The coolant composition for fuel cells according to [1], wherein the compound has 3 to 35 carbon atoms in a cyclic atomic arrangement.

[3] The compound is oxazolone, pyrazolone, jasmon, benzoquinone, pyrone, γ-pyridone

3. The fuel cell coolant composition according to claim 2, which is uracil, tropone, trobolone, chromone, naphthoquinone, oxindone, phthalide, oxanthrone, anthrone, anthraquinone, alizarin, attaridone, and derivatives thereof.

[4] The compound is characterized in that it is contained in a base that can be selected from water, alcohols, glycols, and glycol ethers, and also has one or more kinds of mixture power. 4. The fuel cell coolant composition according to claim 3.

5. The fuel cell coolant composition according to claim 4, wherein the content of the compound is 0.01 to 20 parts by weight with respect to 100 parts by weight of the base.