JPS58164170A - Cell stack of fuel cell - Google Patents

Abstract

PURPOSE:To improve the output characteristics by inserting cushion members between rigid plates and bipolar plates at both ends of a cell laminated body so as to absorb a slight camber of the bipolar plates and to unify the surface pressure applied to each unit cell. CONSTITUTION:Cushion members 5 made of a compound material of carbon powder and paper or fiber mat are inserted between bipolar plates 2 and cooling plates 4 at upper and lower ends of a cell laminated body 3. The bipolar plates 2 and rigid plates such as the cooling plates 4 arranged at upper and lower ends can be tightened and assembled in complete contact with each other even if a slight camber is present on the sintered mold of the bipolar plates 2. The distribution of surface pressures applied to electrodes of individual unit cells 1 is widely improved by tightening the cell stack.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is directed to an improvement in a cell stack of a fuel cell applied to, for example, a phosphoric acid electrolytically purchased fuel cell. The general structure is shown in Figure 1. On the right side of the figure is the 14i fuel electrode.
A matrix impregnated with electrolytes, and! A single cell consisting of a fi electrode, 2 is a bipolar plate as a separate grate made as a carbon sintered molded product with air passage binding and fuel passage forming in opposite directions, and the single cell 1 and bipolar plate 2 are The cell stack 3 is constructed by piling up the cell stacks 2 and 2 under alternating pressure. Historically, female cover plates 4 are placed on the upper and lower sides of this cell stack 3, and the entire assembly is attached with stud bolts (not shown) to form a cell stack. Reference numeral 1141 is a cooling water flow pipe connected to the cooling lk4. Note that the cell stack may be constructed by disposing a current collector plate or a support plate instead of the cooling switch 4. In addition, the cooling 41
4. The current collector plate or support plate is made as a rigid grate with high rigidity, and by pressurizing and holding the cell stack 3 at the threshold of this grate, the pibora plate 2 and the single cell are separated. 1 electrodes are pressed and brought into close contact.

On the other hand, Bipolar Grate 2 is made as a sintered molded product.
Since the air passage flange and the fuel passage groove are formed on both sides of the molded product, they are often slightly warped and curved as a whole. On the other hand, a rigid plate such as the cooling plate 4 is machined to have a flat surface, so when assembling the cell stack, the bipolar plate 2 is restrained by the rigid flat plate and cannot be seen over its entire surface. You won't get any more. This situation is shown in Figure 1.
As shown, the pain relief of the cell laminate 3 is hard and ugly with respect to the upper grate, and only the central portion of the lower end touches the lower plate. As a result, 6 cells l
The surface pressure distribution applied to the electrode surface varies depending on the location of the cell stack 3 and becomes non-uniform. In other words, the 111th!
! The blood pressure distribution in the planar direction applied to the electrodes is shown in Fig. 2, with 1-top unit cell of cell stack 3 in I as a, F as same as the central part, and 4 as lower part as C. Except for the central layer 6, the uppermost layer s1. At the bottom C, the blood pressure distribution becomes uneven. As a result, the output characteristics of the cell stack with the conventional structure shown in FIG. 1 are the same as those shown in FIG.
,H,0. Note that A, H, and O are each JI
The characteristics of a single cell corresponding to parts a, b, and c in the EI diagram are shown. As is clear from this figure, except for the central part of the layer of the cell stack 3, the upper part of the layer.

The characteristics of the lower part of the layer are greatly affected. Furthermore, if the cell laminate 3 and the cooling layer 4 do not form a vH layer over the entire area, the heat conduction of the heat generated in the cells will be poor, and sufficient cooling performance will not be achieved. Similarly, when the plate is a current collector, the electrical contact resistance between the current collector and the cell increases, and the resistance loss increases accordingly.

This invention was developed in consideration of the above points.1 Its purpose is to absorb the slight warpage of the bipolar plate, equalize the surface pressure applied to each unit cell forming the cell stack, and improve the output characteristics. The object of the present invention is to provide a cell stack for a fuel cell in which the cell has good contact with a grate such as a cooling plate and a current collector plate.

According to the present invention, this object is achieved by inserting an open cushion material between a rigid plate and a bipolar plate at the inner end of the cell stack.

The present invention will be described in detail below based on illustrated embodiments.

In FIG. 3, the basic structure of the cell stack is the same as @1. By the way, according to this invention, cushioning material 5 is inserted between the bipolar plate 2 and the cooling plate 4 at the upper and lower shoulders of the cell stack 1 and 3. This cushion @ 5 is made of carbon powder and paper or fiber mat, such as carbon paver or carbon fiber mat, so that the bipolar plate 3 and the cooling plate, and the rigid plate in front of the electric board A conductive cushioning material made of a composite material is used. Note that if the rigid plate is made of solid material like an end plate, the cushioning material does not necessarily have to be conductive.

Now, according to the configuration of the cell stack in which the cushioning material 5 is inserted as described above, even if the sintered molded product of the bipolar plate 2 has a slight warp, this warp is absorbed and the bipolar plate 2 is It is possible to assemble and tighten the rigid plate in complete contact with the cooling plate L4 arranged at both ends. Therefore, by tightening the cell stack, the surface pressure distribution applied to the electrodes of each unit cell is greatly improved. Also, from the driving test, the characteristics i1A, B, 0 in Fig. 4 are respectively), +,
Results were obtained in which the parameters such as Bl and Ql could be improved.

It is also possible to improve the thermal resistance or electrical resistance of contact with a cooling plate or current collector plate in the dark.

As described above, according to the present invention, even if the bipolar plate, which is a component of the cell stack, is slightly curved, the warp can be absorbed and the surface pressure distribution to the unit cells can be made almost uniform. As a result, it is possible to improve the output characteristics of the cell stack, as well as the cooling performance and current collection performance.

[Brief explanation of drawings]

1st and 3rd wJ are assembly configuration diagrams of cell stacks according to the conventional and embodiments of the present invention, respectively, and FIG.
The surface pressure distribution diagram applied to the half-1m turtle in the figure, Figure 4 is the 1st
FIG. 4 is an output characteristic diagram showing a comparison of the cell stacks in FIG. 3 and FIG. 3; 1: Cell, 2: Bipolar plate, 3: Cell laminate, 4: Cooling plate as a rigid plate, 5: Cushion material. 1 ') 1' 21 4 sides I11;

Claims (1)

[Claims] 1) A fuel electrode, a matrix impregnated with an electrolyte. It was constructed by stacking unit cells consisting of air electrodes horizontally via separate plates to form a cell laminate, and then clamping this cell laminate under pressure between rigid plates with high rigidity. A cell stack for a fuel cell, characterized in that a cushioning material is inserted between the rigid plate and the separate plate in the layered structure of the cell stack. 2. Scope of Claims Item 1: In the cell stack described above, the cushioning material is an electrically conductive cushioning material made of a combination of carbon powder and a paper or fiber V-cotton that is environmentally friendly. Battery cell stack.