JPS5927468A - Fuel cell - Google Patents

Abstract

PURPOSE:To stabilize the reaction at high temperature by forming an interconnector having fuel gas or oxidizing gas supply grooves with a mixture of solid resol type phenol resin and artificial graphite. CONSTITUTION:Electrode 12 and 12a are arranged on the both sides of a matrix 11, and an interconnector 27 obtained by forming intersecting fuel gas and oxidizing gas supply grooves 15 and 15a and by embedding a cooling pipe 26 is placed to form a unit cell 10. A plurality of unit cells are stacked to form a fuel cell 17. The connector 27 is formed by mixing 5-40wt% solid resol type phenol resin and 60-95wt% artificial graphite having a particle size of 10- 300mu and kneading them, then molding. Therefore, heat resistance and heat conductivity are improved and stability at high temperature is increased and energy conversion efficiency is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a fuel cell in which the composition and structure of a plate having electric and cooling functions are improved.

[Technical background of the invention]

2. Description of the Related Art Fuel cells (hereinafter referred to as batteries) are conventionally known as devices that directly convert chemical energy contained in fuel into electrical energy. This battery usually has a pair of porous electrodes sandwiching an electrolyte, and a fuel gas that supplies hydrogen gas is brought into contact with the back of one electrode, and a fuel gas that supplies hydrogen gas is brought into contact with the back of the other electrode. By bringing an oxidizing gas into contact with each other and utilizing the electrochemical reaction that occurs at this time, electrical energy can be extracted from between both electrodes with high energy conversion efficiency.

By the way, based on the above principle, special 6 diphosphoric acid (H11
A unit cell constituting a battery using PO4) as an electrolyte is formed as follows. That is, the unit cell is formed of porous material on both sides with a matrix impregnated with an electrolyte as a boundary, and a pair of electrodes on the matrix side (to which two catalyst layers are added) are arranged on each side. A plate (hereinafter referred to as an interconnector) with ribs serving as a groove and a convex portion is placed on the back surface of the ( ) ill and l two plates. On the surface of this interconnector located at each 'electrode 1tlI, a plurality of grooves in the directions @f2, which are perpendicular to each other, are formed in half rows by means of lips C2, respectively. The grooves on one side of the interconnector serve as flow paths for fuel gas, and the grooves formed in the orthogonal direction on the other side serve as flow paths for oxidizing gas. A plurality of unit cells are stacked via the interconnectors formed in this way, beam electrical plates are arranged at the upper and lower ends, and insulating plates and clamping members are attached and tightened together to stack the battery. form the body.

Then, two reaction gas supply containers (hereinafter referred to as manifolds) are arranged on mutually opposing surfaces of this integrated electrical structure.One opposing manifold supplies and discharges fuel gas,
The other opposed manifold introduces and discharges oxidizing gas and allows the respective grooves 1 and 2 of the above-mentioned interconnectors to flow respectively. In this way, the interconnector type! A pond is constructed.

Others≦There is an electrode type 'a pond with Nirib. This battery is constructed by dividing the aforementioned interconnector into a separator and a lip (-). That is, electrodes with lips on which a catalyst 1- is formed are arranged on both sides of the matrix to form a unit cell. Similar to the interconnector, grooves and ribs are formed on the opposite side of the RL pole that contacts the IJ rack, and the grooves and ribs of both electrodes are formed in directions perpendicular to each other. When stacking a plurality of unit cells, they are stacked with a plate, ie, a plate-shaped separator, in between to prevent the two gases from mixing, and a battery stack is formed in the same manner as described above. Attach a manifold to each of the two to form a lip-equipped electrode type battery.

In the interconnector-type and lip-attached electrode-type batteries 52 configured as described above, performance degradation may occur due to deterioration of the catalyst J- due to heat generation (2) in the unit cell portion during operation. In order to prevent this (-In the case of interconnector type batteries, an interconnector type cooling plate with a cooling pipe embedded in the interconnector is provided for every few unit cells. In this type of battery, a separator-type cooling plate with cooling pipes embedded is installed for each unit cell.In this way, the heat generated inside the unit cell is taken out to the outside and the battery is discharged. These interconnector-type and separator-type cooling plates both have high thermal conductivity and electrical conductivity in the stacking direction of the unit cells, as well as phosphoric acid resistance, heat resistance, and C
Nitrochemical stability is required.

This tC General 1: is a novolac type phenolic resin, hexamethylenetetramine is used as a di-curing agent, natural scale-like or earth-like graphite is mixed and molded, and the next part C2 is machined and the cooling pipe is Either by embedding the cooling pipe or by integrally molding the cooling pipe (by machining).

[Problems with background technology]

However, due to the high output and large size of batteries, C
Second, it has become necessary to operate at high temperatures of 190°C to 200°C. However, the conventional plate formed using hexamethylenetetramine as a hardening agent for the novolak type phenolic resin described above inevitably has a usage temperature limit of C2, and must be used at a temperature below 150°C.

Furthermore, when natural flaky graphite is used as in the past, it has excellent properties in the plane direction due to its shape characteristics, but the properties in the stacking direction required for plates are poor, and dimensional changes in the thickness direction There was a risk that cracks would occur due to thermal deterioration C2, causing gas leakage.

Furthermore, when earth-like graphite is used, the amount of fixed carbon is small at about 70 to 80% by weight, and the thermal conductivity and electrical conductivity are low, resulting in a decrease in battery efficiency. There was a risk that

[Purpose of the invention]

The present invention has been made in consideration of the above points, and its 1st and 9th aspects are to provide a fuel cell that can operate stably at high temperatures of 190°C to 200°C.

[Summary of the invention]

In order to achieve the above object, the present invention has a structure in which a plurality of unit cells are stacked together via a plate that has the function of preventing mixing of fuel gas and oxidant gas and electrically connecting the unit cells. The plate is formed by mixing and kneading a composition consisting of 5 to 40% by weight of a homogeneous resol type phenolic resin and 60 to 95% by weight of artificial graphite with a particle size of 10 to 300μ. ~2
The FC plate has excellent thermal conductivity, electrical conductivity, phosphoric acid resistance, heat resistance, and dimensional stability at a high temperature of 00°C. Note that it is suitable to arrange a cooling plate with integrally molded cooling pipes in several unit cells when molding the plate. Furthermore, in the case of an interconnector-type T-cell, it is suitable to form the plate as an interconnector. Plus, it comes with ribs! In polar cells, it is suitable to form the plate as a separator.

[Embodiments of the invention]

The present invention will be described below with reference to an embodiment shown in drawing C1. In Fig. 1, the unit cell is a matrix Q1 in which a thin sheet made of carbonaceous material is impregnated with WLS material.
Porous electrodes (la, (12a)) are arranged on both sides of the electrode (12a), which is usually made of a carbonaceous material, and a catalyst nozzle (not shown) is placed on the side that contacts the matrix. Also, both electrodes (12) !(12a
)'s Matrix Q sword and the back of each 'HOB).

(15z) and the rib that becomes the convex part (to)? (16a) plate 081 (hereinafter referred to as interconnector)
to be placed. On one side of this interconnector αB), a plurality of groove grips and ribs (16) are formed (two parallel). Also, the screen f2 is arranged in the direction C2 perpendicular to the grooves (b) and ribs (lfl). Multiple rows of t”4-rows (-grooves (15α) and ribs (
16a) is formed. These grooves (b) and (15, 2
) are flow paths for fuel gas and oxidant gas, respectively. Then, a plurality of unit cells are stacked together via interconnectors (Cl8), current collector plates (not shown) are brought into contact with the upper and lower ends, and a sense of unity is created through insulating members and tightening members (not shown): Then, form a battery laminate (b).

The %L pond stack a formed in this manner is provided with a so-called manifold for supplying or discharging a reaction gas as shown in FIG. 2C. One side 1- of the t-pond laminate (b)
Attach a manifold with a pipe (e) for supplying fuel waste, and install a manifold (19u) with a pipe (18m) for discharging fuel exhaust gas on the opposing side lids. In addition, the other 1 ml 1 m + = manifold 1 having pipes facing each other and supplying oxidizing gas.
) and a hold (21i) with a pipe (20 m) for discharging the oxidizer exhaust gas. These manifolds (4), (19Fl), lmL (2x:i
r;) are both attached to the battery stack (b) while maintaining insulation and airtightness via an insulating backing (not shown).

In this way, an interconnector type battery is constructed.On the other hand, there is also a 111-pole type battery with one electrode. This battery is constructed by dividing the above-mentioned interconnect into a separator and a rib, which will be described next. That is, as shown in FIG. 3, on both sides of the matrix a1+, the catalyst layer)
22a) with ribs formed respectively &r, (2
3a) to form a unit cell α0). and,
ribbed electrode ml, each matrix a of (23a)
A plurality of grooves (B) and (15α) and ribs α6) and (16α) serving as convex portions are formed on the opposite side that contacts 1. That is, rib attachment * qr r two or more mutually 61 parallel #(
15) and ribs ■), and x&(23,
2) has grooves (15a) and ribs (16a) in orthogonal directions.
) to form. In this manner, a unit cell is formed, and a plurality of these unit cells are stacked with separators interposed therebetween to form a battery stack (lη) as a single unit in the same manner as described above. This separator (b) prevents the fuel gas and the oxidizing gas flowing through the adjacently laminated electrodes (23a) and (23a) from mixing. Comparing the interconnector type battery shown in Fig. 81 and the fixed electrode type battery with ribs shown in Fig. , as mentioned above, the plate (interface) and lip (g) and electrode (2) in Figure 1 are exactly equivalent to the ribbed part (-) C2 in Figure 2. do. Also, interconnector 08 in Figure 1
) is a part of the separator part ) in FIG.

In the ink-connector type and ribbed constant electrode type batteries constructed as described above, the temperature rises due to heat generation in the unit cell during operation.

In order to prevent catalysts from deteriorating and performance decreasing, several unit cells (g2) are embedded in the cooling pipe (for interconnector types, as shown in Figure 4). (hereinafter referred to as interconnector type cooling grate). In addition, if there is a constant electrode type battery with a lip, there are several unit cells (,.) as shown in Figure 5C2.
A (separator part in which two cooling pipes are embedded) (hereinafter referred to as a separator type cooling plate) is provided.

In this way, the interconnector type cooling plate (support)
) and separator type cooling plate) (When 281 is installed respectively, the heat generated in each ! pond is taken out from C2,
111 The temperature of the pond is suppressed.

Interconnector 0 of the above-mentioned interconnector type battery
8) and the composition of the molded member of the present invention forming the interconnector type cooling plate (separator (b) of the ribbed fixed electrode type battery) and separator type cooling plate (e) is as follows.

That is, 5 to 40% by weight of solid resol type phenolic resin and 60 to 95% of artificial graphite of 10μ to 300μ
u-jt% are mixed and kneaded and molded.

This solid resol type phenolic resin contains unreacted phenol of 0.05 to 15%, melting point of 20° to 100°C, and 15% of unreacted phenol.
It has a characteristic that the gelation time on a 0°C hot plate is 30 to 150 seconds. Moreover, the artificial graphite of 10 μm to 300 μm is made of artificial graphite manufactured from petroleum coke or anthracite, and has an internal carbon content of 95% by weight.

The above solid resol type phenolic resin and 10μ~300
In the mixing ratio of μ artificial graphite, if the solid resol type phenolic resin is less than 5% by weight,
It becomes ineffective as a binder for artificial graphite of μ, and its mechanical properties deteriorate, making it unsuitable for practical use. 40 again]
If it exceeds 1-ji-h, there is no effect on phosphoric acid resistance and heat resistance. On the other hand, 10μ~300μ artificial graph eye) 60
]i (Thermal conductivity and electrical conductivity I: There is no effect if the value is less than 95. Phenolic resin 15-303: 'Jrc%, 40
70-85% by weight of artificial graphite with μ~200μ.

Next, a method for forming a molded member according to the present invention will be explained. Solid resol type phenolic resin crushed to appropriate particle size and 1
0μ~300μ artificial graphite and 1-1 Add a mold release agent or lubricant as necessary, mix at room temperature and disperse uniformly, then add an evaporable liquid dispersion medium and mix to form a slurry. Heat and knead in a machine. Then, after volatilizing the evaporative liquid dispersion medium, it is cooled and solidified, and then pulverized to an appropriate size using an appropriate pulverizer to form a molded member. The pulverized molded member is then heated to an appropriate temperature in a mold 1;
and mold the interconnector 011) and separator).

(26) Also, when molding with a mold 1: embedding cooling pipes C2) thereby molding an interconnector type cooling plate (width) and a separator type cooling plate μs).

The molded member of the present invention described above has excellent thermal conductivity, electrical conductivity, phosphoric acid resistance, one-dimensional stability, and heat resistance. Below C
EXAMPLE 2 The present invention will be explained in more detail using Examples≦2, but it goes without saying that the present invention is not limited to these Examples.

Comparative Example I A novolak type phenolic resin (containing hexamethylenetetramine as a hardening agent) was mixed with 75 tons of natural flaky graphite of 40μ to 200μ at room temperature, methyl alcohol was added to form a slurry, and the mixture was kneaded at 100°C. After heating and kneading in a machine and volatilizing the methyl alcohol, the cooled and pulverized composition material was heated to 160'C in a mold heated to 200°C.
It was cured and molded at a pressure of 4/- for 5 minutes.

This molded member was heated to 190°C in 85% by weight phosphoric acid solution.
As a result of weekly immersion treatment, the dimensional change rate before and after immersion was +
0.8 inch, swelling of the composition member 6 was observed, and the phosphoric acid solution also became black and cloudy, and the phosphoric acid solution was contaminated by the phosphoric acid solution and was not used for practical use.

Comparative Example ■ 4 weights of image-shaped resol type phenolic resin and 96 weights of artificial graphite of 8μ or less were mixed at room temperature, methyl alcohol was added to form a slurry, and the mixture was heated and kneaded in a mixer at 100°C. After volatilizing, the cooled and pulverized composition material was placed in a mold heated to 160°C for 200°C.
It is cured for 5 minutes at a pressure of Kz/cII and molded. As a result of phosphoric acid treatment of this molded part under the same conditions as in Comparative Example ■, the dimensional reduction ratio before and after immersion showed a stable value of -0.01%, but the bending strength of this molded part was measured. Then 2K
f/- and 7'C with a strength that is not suitable for practical use.

Example■ Solid resol type phenolic resin 25 weight x 40μ
75 weights of ~200μ artificial graphite was mixed at room temperature, and methylalurol was added to form a slurry.

After heating and kneading in a mixer at 100°C to volatilize the methyl alcohol, the cooled and pulverized composition material is cured and molded in a mold heated to 160°C at a pressure of 2001/- for 5 minutes. . The thermal conductivity 1 of this molded member is 20XCa1/mhrd8g, and the electrical conductivity is 90Vm.
I failed. Furthermore, as a result of phosphoric acid treatment under the same conditions as in Comparative Example I, the dimensional change rate before and after immersion was -o, oi%, and the bending strength was 7.0 to 9/-, both of which were excellent. The numbers were shown.

Example ■ Isomorphic resol type phenolic resin 15% by weight (2100μ
~ 300μ artificial graphite 85wt. is mixed at room temperature, methyl alcohol is added to make a slurry,
After heating and kneading in a mixer at 00°C to volatilize the methylalcohol, the cooled and pulverized composition was cured for 5 minutes at a pressure of 200 h/cd in a mold heated to 160°C and molded. do. The thermal conductivity of this molded member is 25KOa↓/m
, hr4eg+ electrical conductivity was 110 trm. Further, as a result of phosphoric acid treatment under the same conditions as in Comparative Example I, the dimensional change rate before and after immersion was -0.01%.

The strength of the song was 6.0 and g/-, both of which were excellent values.

Example ■ Under the same conditions C2 as Example ■, a cooling plate formed integrally with 3φ cooling pipes embedded at 20 mm intervals was
Heat cycle test C in which this heat cycle was repeated three times, with one heat cycle applying a temperature change from 0° to 25°C: withstood and no cracks were generated.

Examples I, n, III and Comparative Example 1. It can be seen from II that the molded member made of the composition member of the present invention has various good properties. Therefore, each of the nine interconnector type and ribbed electrode type batteries in which an interconnector and a separator made of this molded f15@' are arranged,
All of the batteries had excellent thermal conductivity, electrical conductivity, quality, heat resistance, and mechanical properties1.In addition to the above-mentioned properties62, each battery also had excellent performance in suppressing temperature rise. There is.

〔Effect of the invention〕

As explained above, according to the fuel cell 5 unit of the first invention, a plurality of unit cells are stacked via plates, and the plates are made of solid resol type phenolic resin 5 to 40% by weight and 10% by weight.
~300μ artificial graphite) is molded after mixing and kneading 60 to 95% by weight52, it is stable in high temperature conditions, and self-installation of C2 cooling plate for every few unit cells (2, special (Two temperature rises can be suppressed.

[Brief explanation of the drawing]

FIGS. 1 and 4 are exploded perspective views showing interconnector-type fuel cells of the present invention, respectively. FIG. 2 and FIG. 5 are exploded perspective views showing lip-equipped electrode type fuel cells of the present invention, respectively. FIG. 3 is a perspective view of the fuel cell of the present invention shown in FIGS. 1 and 2. (10)...Unit cell (11)...Matrix (12), (12G)...Electrode (13)...
・Interconnector (15), (15α)...#
(16), (16α)...Reply (17)...
Battery stack (19), (19m), (21), (21]?l
)...Manifold (22), (22g)...Catalyst layer (23), (23g)...Ribbed electrode (25)...
・Separator (26)...Cooling pipe (27)...
Interconnector type cooling plate (28) Separator type cooling plate Patent attorney Mr. Inoue Figure 1 Figure 2 Figure f8 tlf Figure 3 Continued from page 1 0 Inventor Toshihisa Saito Toshiba-cho, Fuchu-shi, Tokyo 1 Tokyo Shibaura Electric Co., Ltd. Fuchu Factory ■Applicant Tokyo Shibaura Electric Co., Ltd. 72 Horikawa-cho, Saiwai-ku, Kawasaki City

Claims (1)

[Scope of Claims] (1) A unit cell in which a pair of 'vL electrodes are disposed with an electro-N material layer sandwiched between them, and a fuel gas and an oxidizing agent are passed through the back ports of each electrode to output electrical energy. A plurality of unit cells are stacked together via a plate having a function of forming a gas, preventing mixing of the fuel gas and the oxidizing gas, and electrically connecting the unit cells. Then, the plate was filled with solid resol-type phenolic resin at 5 to 40 f# and 60 to 60 g of artificial graphite with particles of 10 to 300μ.
A fuel cell characterized by being formed by mixing, cross-wiring, and molding composition members consisting of ~95% i:%. (8) The fuel cell according to claim 1, wherein the plate is an interconnector type plate in which grooves are formed as passages for fuel gas and oxidizing gas. battery. (4) Claim 1, in which the electrode is a ribbed electrode, and unit cells are stacked via a separator plate.
Fuel cell as described in Section.