SOLID OXIDE FUEL CELL MODULE

Disclosed herein is a solid oxide fuel cell module including: a plurality of cylindrical unit cells including a cylindrical internal electrode, an electrolyte, and an external electrode; stack supports including a pair of current collecting plates arranged in parallel and elastic parts changing a gap between the pair of current collecting plates, wherein the stack supports are arranged so as to be in electrical communication with the external electrode of the unit cell.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The objects, features and advantages of the present invention will be more clearly understood from the following detailed description of the preferred embodiments taken in conjunction with the accompanying drawings. Throughout the accompanying drawings, the same reference numerals are used to designate the same or similar components, and redundant descriptions thereof are omitted. Further, in the following description, the terms “first”, “second”, “one side”, “the other side” and the like are used to differentiate a certain component from other components, but the configuration of such components should not be construed to be limited by the terms. Further, in the description of the present invention, when it is determined that the detailed description of the related art would obscure the gist of the present invention, the description thereof will be omitted.

FIG. 1is a perspective view schematically showing a solid oxide fuel cell module according to a preferred embodiment of the present invention.

A solid oxide fuel cell module according to a preferred embodiment of the present invention is configured of a unit cell100having a cylindrical shape and a stack support200.

More particularly, the cylindrical unit cell100is configured of an internal electrode110, an electrolyte120, an external electrode130, and an interconnector140as well known. The unit cell100includes a cylindrical internal electrode110, the electrolyte120disposed on an outer peripheral surface of the cylindrical internal electrode110, the external electrode130disposed on an outer peripheral surface of the electrolyte120, and the interconnector140extended from one portion of the outer peripheral surface of the cylindrical internal electrode110in a length direction. This interconnector140is arranged to be spaced apart from the external electrode130by a predetermined interval simultaneously with protruding outwardly from an outer peripheral surface of the external electrode130.

Referring toFIG. 1, in the unit cell,100the internal electrode110, the electrolyte120, and the external electrode130are sequentially stacked as described above. Here, the case in which the internal electrode110is formed as an anode and the external electrode130is formed as a cathode is will be described by way of example.

The anode of the cylindrical internal electrode110serves to support the electrolyte120and the cathode of the external electrode130stacked on the outer peripheral surface thereof The anode is formed in a cylindrical shape and receives fuel (hydrogen) from a manifold to generate negative current through an electrode reaction.

Preferably, the anode is formed by heating nickel oxide (NiO) and yttria stabilized zirconia (YSZ) to 1200 to 1300° C., wherein nickel oxide is reduced to metallic nickel by hydrogen to exhibit electron conductivity, and yttria stabilized zirconia (YSZ) exhibits ion conductivity as an oxide.

The electrolyte120, which assists oxygen ions generated in the cathode to be transferred to the anode, is stacked on an outer peripheral surface of the anode. The electrode may be formed by performing the coating using a dry coating method such as a plasma spray method, an electrochemical deposition method, a sputtering method, an ion beam method, an ion implantation method, or the like, or a wet coating method such as a tape casting method, a spray coating method, a dip coating method, a screen printing method, a doctor blade method, or the like, and then performing the sintering at 1300 to 1500° C. The electrolyte120is formed on the outside of the anode using YSZ or scandium stabilized zirconia (ScSZ), gadolinia-doped ceria (GDC), La2O3-Doped CeO2(LDC), or the like, wherein since in the yttria stabilized zirconia, tetravalent zirconium ions are partially substituted with trivalent yttrium ions, one oxygen hole per two yttrium ions is generated therein, and oxygen ions move through the hole at a high temperature. Meanwhile, since the electrolyte120has low ion conductivity, voltage drop is less generated due to ohmic polarization. Therefore, it is preferable that the electrolyte is formed as thin as possible. If pores are generated in the electrolyte120, since a crossover phenomenon of directly reacting fuel (hydrogen) with oxygen (air) may be generated to reduce efficiency, it needs to be noted so that a scratch is not generated.

The cathode, which receives air (oxygen) from the outside at which an oxidation atmosphere is formed to generate positive current through the electrode reaction, is stacked on the outer peripheral surface of the electrode120as shown inFIG. 1. The cathode may be formed by coating lanthanum strontium manganite ((La0.84Sr0.16) MnO3) having high electron conductivity, or the like, using a dry coating method or a wet coating method similar to that in the electrolyte, and then sintering the coated lanthanum strontium manganite at 1200 to 1300° C. That is, air (oxygen) is converted into oxygen ion by a catalytic action of lanthanum strontium manganite and transferred to the anode through the electrolyte120.

The interconnector140is directly connected to one portion of an exposed outer peripheral surface of the internal electrode110as shown inFIG. 1to transfer the negative current generated in the anode to the outside of the unit cell100(or a current collector). In other words, since the interconnector140is a member for collecting current of the internal electrode110, the interconnector140needs to have electric conductivity.

In the unit cell100, one portion of the outer peripheral surfaces of the electrolyte120and the external electrode130are removed, thereby exposing an exposed portion111(SeeFIG. 2) of the outer peripheral surface of the internal electrode110. Next, the interconnector140is disposed on the exposed portion111. Since the interconnector140is in electrical communication with the internal electrode110as described above, in the case in which the interconnector contacts the external electrode130, a short is generated. Therefore, the interconnector140and the external electrode130are arranged so as to be spaced apart from each other by a predetermine interval D (SeeFIG. 2).

Particularly, the interconnector140protrudes outwardly so as to be higher than the uppermost portion or the outermost portion of the external electrode130. This is to assist in connecting the interconnector140to another current collecting member200or the current collector.

The stack support200serves as a buffer between unit cells adjacent to each other simultaneously with collecting electric energy generated in the cylindrical unit cell100. To this end, in the solid oxide fuel cell module according to the preferred embodiment of the present invention, at least one, preferably, three stack supports200are arranged along the outer peripheral surface of the cylindrical unit cell100.

In the present invention, the stack supports200are disposed in a U shape in which one portion is opened, and disposed so as to be perpendicular to each other at a lower surface, a left surface, and a right surface of the unit cell100except for the portion of the outer peripheral surface of the unit cell100on which the interconnector140is disposed.

The stack support200includes a pair of current collecting plates210and an elastic part220for spring action of the plate, as shownFIG. 1. Preferably, the stack support200includes the elastic part220between a pair of current collecting plates210arranged in parallel with each other, and the elastic part220may be fixed to the current collecting plate210by a welding method, or the like.

The current collecting plate210has a flat plate shape, and a plurality of through holes211are formed therein. However, the current collecting plate210is not limited thereto, but may be curved with the same curvature as that of the outer peripheral surface of the unit cell100(SeeFIG. 1A) to achieve an area-contact with the outer peripheral surface of the unit cell100, such that a contact area between the unit cell100and the current collecting plate210of the stack support200may be maximized, thereby making it possible to significantly increase current collection efficiency.

The current collecting plate210may include the plurality of through holes211to efficiently supply gas (oxygen or hydrogen) to the external electrode130. The elastic part220may be made of an SUS-based alloy bent in a V shape so as to provide elastic force. However, the elastic part220is not limited thereto, but may be made in various types, a coil spring shape, or the like.

Since the oxidation atmosphere is formed at the outside of the solid oxide fuel cell module according to the preferred embodiment of the present invention, in order to prevent the stack support200from being oxidized, it is preferable that the stack support200is made of the SUS-based alloy and oxidation protective coating is applied thereto.

Further, in the solid oxide fuel cell according to the preferred embodiment of the present invention, a metal mesh150(SeeFIG. 2) may be additionally arranged between the unit cell100and the stack support200. The metal mesh150is attached to only the portion of the outer peripheral surface of the unit cell100using a conductive ceramic paste. More specifically, the metal mesh150may be attached on the outer peripheral surface of the external electrode130so as to prevent a contact of the interconnector140in advance. The metal mesh may uniformly improve an electric contact between the external electrode130of the unit cell100and the current collecting plate210of the stack support200.

FIG. 2is a view showing a state in which the solid oxide fuel cells shown inFIG. 1are coupled in parallel with each other.

A plurality of unit cells100may be arranged in parallel through the stack support200as shown inFIG. 2so as to collect current. Each of the unit cells100may be received in an internal space between the stack supports200disposed in the U shape and be arranged in parallel so as to be in electrical communication with the stack supports200at the lower surface, and left and right surfaces of the unit cell100.

FIG. 3is a cross-sectional view of the case in which the solid oxide fuel cell modules according to the preferred embodiment of the present invention are stacked.

Referring toFIG. 3, a stack in which the unit cells100are connected in series and/or with each other may be formed as shown inFIG. 3by contacting a side of each of the stack supports200installed in a vertical direction with the unit cell to arrange the stack supports200in parallel or stacking the unit cells100to vertically contacting the interconnector140and the stack supports200.

In the case in which the unit cell100and the stack support200are alternately stacked, three stack supports200arranged in the U shape may be selectively contacted with only the external electrode130of the unit cell100, but the stack support200arranged at a different stack height may be selectively contacted with the interconnector140of the unit cell100. to Therefore, the unit cells100received in the stack supports arranged in the U shape to be horizontally arranged are connected in parallel with each other, and the unit cells100received in the stack supports having different stack heights to be vertically disposed are connected in series with each other. Finally, the solid oxide fuel cell module according to the preferred embodiment of the present invention may implement the required voltage by adjusting the numbers of stack supports200and unit cells100.

In the present invention, as described above, the unit cells100and the stack supports200are connected in series and/or in parallel with each other in a box shaped housing30to form the stack. Preferably, the housing is formed so as to maintain and support the unit cell100and the stack support200as the stack in an internal portion enclosed by support walls31to34. In the housing30, a current collector311is arranged beneath an upper support wall31. In addition, in the housing30, another current collector313is arranged directly above of a lower support33.

The current collector311is arranged so as to selectively contact only the upper support wall31and the interconnector140of the unit cell100arranged at the uppermost end to collect the current generated in the internal electrode110(SeeFIG. 1) of the unit cell100as shown inFIG. 3.

Similarly, the current collector331is arranged so as to connect the vertically arranged unit cells100in series with each other through the lower support wall33and a bottom surface of the stack support200arranged at the lowermost end to collect the current generated in the external electrode130(SeeFIG. 1) of the unit cell100.

Particularly, an insulation plate312is additionally provided in order to prevent shorts between the upper support wall31and the current collector311arranged beneath the upper support wall31and between the upper support wall31and the support walls32and34. Similarly, an insulation plate332is additionally provided in order to prevent shorts between the lower support wall33and the current collector331arranged directly above the lower support wall33and between the upper support wall33and the support walls32and34.

Selectively, insulation plates342and322are arranged at inner side surfaces of the support walls32and34, respectively, thereby allowing the current collected in the stack support200to flow to only the current collectors311and331.

As shown inFIG. 3, in the solid oxide fuel cell module according to the preferred embodiment of the present invention, the stack support200is fixed to the support walls32and34by various coupling method, for example, a screw fastening method, thereby making it possible to support and maintain the unit cell100in the stack support200. That is, the stack support200to be attached to the side of the unit cell in the vertical direction is screwed and fixed to the support wall32or34of the housing30, wherein a width of the stack supports200arranged at the same height may be adjusted by tightening and loosening screws35. When the screw35is tightened (such as in the case of the stack support shown at a lower end portion ofFIG. 3), the stack support200is pressed in a side direction to forcibly press the elastic part220, such that the width of the stack support200(for example, a spaced distance between the pair of current collecting plates) may be reduced. Therefore, current may be stably collected in the stack with respect to external stress, and contact resistance at the time of vertically and/or horizontally collecting the current may be reduced through elastic and repellent force. Additionally, in the solid oxide fuel cell module according to the preferred embodiment of the present invention, the case in which the unit cell100includes the cylindrical internal electrode110, the electrolyte120, and the external electrode130sequentially stacked therein as shown inFIG. 1and described above, the internal electrode110is formed as the anode, the external electrode130is formed as the cathode is described above by way of example.

As widely known in those skilled in the art, the unit cell may be sufficiently configured of an internal electrode formed of a cathode, an electrolyte, and an external electrode formed of an anode, and a detailed description and drawing thereof will be omitted.

As set forth above, the present invention provides the solid oxide fuel cell module in which at least one stack support capable of improving a current collection function and a support function is arranged on the outer peripheral surface of the unit cell instead of the mesh and/or foam according to the prior art.

According to the present invention, a stable contact state between the unit cell and the stack support may be maintained, and at the same time, the current collection efficiency may be improved.

According to the present invention, even though unexpected external force is applied at the time of integrating the stack, the plurality of unit cells arranged in the vertical and horizontal directions may be stably supported through gap stress acting on the elastic part of the stack support, and current collection in the stack may be performed. Therefore, serial and/or parallel connection of the unit cells may be freely constructed.

In addition, according to the present invention, at least one stack support is provided at the outside of the unit cell, such that contact resistance may be reduced.