CN112310454B - Integration method of solid oxide fuel cell stack based on symmetrical double-cathode structure - Google Patents

Abstract

The present invention provides an integration method based on a symmetrical double cathode structure solid oxide fuel cell stack. In the method, the cathode layers of two adjacent symmetric dual-cathode structure solid oxide fuel cells A and B are opposed to each other, and a cathode connecting member is arranged between the two cathode layers, and the cathode connecting member is a flexible conductive connecting member. Therefore, the distance between the battery cells can be adjusted during assembly, so as to ensure that the external dimensions of the stack are consistent, which is convenient for installation and debugging; at the same time, the cathode surfaces of the battery cells can be well attached, thereby reducing the contact resistance and improving the electrical power. In addition, the battery unit body can be prevented from being damaged during installation and disassembly, and it can be disassembled and reassembled for repeated use, which has a market prospect.

Description

Integration of a Solid Oxide Fuel Cell Stack Based on Symmetric Double Cathode Structure method

technical field

The invention relates to the technical field of solid oxide fuel cells, in particular to an integration method of a solid oxide fuel cell stack based on a symmetrical double cathode structure.

Background technique

Solid oxide fuel cell (Solid Oxide Fuel Cell, SOFC) is an energy conversion device that can directly convert chemical energy into electrical energy. SOFC has the advantages of high energy conversion efficiency and environmental friendliness, so it has received extensive attention from researchers.

The basic structure of SOFC consists of a porous anode, a porous cathode, and a dense electrolyte layer. When fuel is introduced into the anode, and oxidant gas is introduced into the cathode, an electrochemical reaction occurs at the three-phase interface between the electrolyte and the electrode to generate electrons, and the electrons form a discharge circuit through an external circuit to generate electrical energy and thermal energy. In practical applications, it is necessary to combine the basic structure of SOFC with connector components such as metal or ceramics to form SOFC cells, which are further connected in series and parallel to form a high-power stack to supply power to electrical equipment.

Existing stacks are formed by stacking multiple cells, and it is unavoidable that there is a slight difference in thickness between cells. However, the "small thickness difference" mentioned after stacking multiple cells will be magnified due to the superposition, and finally the thickness difference of the stack will be quite large, which is mainly manifested in the unevenness, distortion, unevenness of the stack, and more serious It will cause the stack to become trapezoidal. Such a stack is difficult to assemble and disassemble, and at the same time affects the sealing performance of the battery. In addition, during use, rupture or failure of one of the cells can cause rupture and failure of the other cells.

Patent document CN 106033819A discloses a top-down symmetrical distributed cell structure centered on a supporting electrode layer, and the supporting electrode layer has a hollow channel (or hole) inside, and fuel gas and oxidant gas come from the hollow channel (or hole) and the flat plate respectively. The upper and lower sides are connected to form a discharge circuit through the electrolyte and the electrode to form the ion conduction of the oxidizing gas and the electronic conduction of the external circuit. This structure is conducive to maintaining the flatness of the battery during the sintering process of the battery; at the same time, since the three-phase interface where the electrochemical reaction occurs is located on the upper and lower sides of the supporting electrode layer, the generated thermal stress can be effectively offset, which can greatly reduce the thermal stress, reduce the damage to the electrolyte and the electrodes, so as to effectively protect the operation of the battery under harsh conditions such as high temperature and cold and heat cycles; in addition, the thickness of the traditional battery structural unit is 400-1000 μm, the hollow upper and lower distributed electrode support structure The thickness can be increased to more than 10 times that of the traditional structure, so it has high mechanical strength, and it is easy to prepare large-area batteries and can carry out secondary processing.

When the anode layer is the support layer, a symmetrical double cathode structure solid oxide fuel cell is formed. At this time, the oxygen in the air undergoes an electrochemical reaction at high temperature through the cathode to generate oxygen ions, which pass through the oxygen ion conductor electrolyte, and the hydrogen in the porous anode. An electrochemical reaction occurs to generate water and release electrons. The electrons generate electrical energy through the anode metal electrode (ie, the metal electrode connected to the anode layer), the external circuit load, and the cathode metal electrode (ie, the metal electrode connected to the cathode layer). The symmetric double-cathode structure solid oxide fuel cell is developed on the basis of the tubular structure and the flat-plate structure. advantage.

SUMMARY OF THE INVENTION

In view of the above technical status, the present invention provides an integration method based on a solid oxide fuel cell stack with a symmetrical double cathode structure, which has the advantages of flat stack after integration, easy assembly and disassembly, and can avoid cell rupture and damage.

The technical scheme of the present invention is: an integration method based on a solid oxide fuel cell stack with a symmetrical double cathode structure, wherein a plurality of the solid oxide fuel cell units with a symmetrical double cathode structure are integrated into a stack;

The symmetric double-cathode structure solid oxide fuel cell unit takes the anode as the support layer and is in an up-down distribution structure, that is, in the cell structure unit, the anode layer, the electrolyte layer and the cathode layer are stacked up and down along the thickness direction, and the electrolyte layer includes the first layer. an electrolyte layer and a second electrolyte layer, the first electrolyte layer is located on the upper surface of the anode layer, the second electrolyte layer is located on the lower surface of the anode layer; the cathode layer includes a first cathode layer and a second cathode layer, the first cathode layer is located on the first cathode layer The upper surface of an electrolyte layer, the second cathode layer is located on the lower surface of the second electrolyte layer; and the anode layer is provided with a hollow channel for fuel gas circulation;

It is characterized in that: as shown in FIG. 1 , the two adjacent symmetric double-cathode structure solid oxide fuel cell units are battery unit A and battery unit B, and the second cathode layer of battery unit A and the first cathode layer of battery unit B are the same. A cathode layer is opposite, a cathode connector is provided between the battery unit A and the battery unit B, and the cathode connector is a flexible connector, that is, the cathode connector material is a flexible conductive material with a certain mechanical strength.

The flexible conductive materials are not limited, including metal flexible materials and non-metal flexible materials. The flexible metal materials include, but are not limited to, high temperature alloys, and high-temperature functional ceramics; the flexible non-metallic materials include, but are not limited to, graphite, carbon fiber, and the like.

As a preferred implementation manner, considering the transmission of oxidant gas, the surface of the cathode connector has pores for allowing oxidant gas to pass through to reach the cathode layer, so as to provide oxidant gas for the two cathode surfaces of each battery unit.

In order to improve the tightness of each battery cell in the stack, thereby improving the sealing performance and integrity of the stack, it is preferable to set pressure plates at both ends of the outermost side of the stack, that is, assuming that the stack consists of N (N≥ 2) It is composed of a solid oxide fuel cell unit with a symmetrical double-cathode structure. The battery units at both ends of the stack are respectively the battery unit 1 and the battery unit N. The cathode connector is arranged on the surface of the first cathode layer of the battery unit 1. A pressure plate A is arranged on the surface of the cathode connector; the cathode connector is arranged on the surface of the second cathode layer of the battery unit N, and a pressure plate B is arranged on the surface of the cathode connector. A and the pressure plate B exert pressure to make the battery cells in the stack tightly connected through the cathode connector. Since the cathode connector is an elastic connector, the breakage of the connector due to pressure is avoided. At the same time, the battery body will not be damaged during installation and disassembly, and it can be disassembled and used repeatedly. The cathode connector may be composed of a plurality of cathode connector units, the structures of which cooperate with each other to achieve tightness between the cathode surfaces of each battery unit.

In order to improve the sealing performance of the anode layer end face of each battery cell in the stack, preferably, each battery cell is further provided with an anode connector. As an implementation manner, the anode connector includes a gland that is adapted to the shape of the end face of the anode layer and that can be snapped over the end face of the anode layer, and that is adapted to the outer shape of the end of the anode layer and can be wrapped around the end of the anode layer. end cap. The end cap and the pressing cap are connected to each other to form a sealing member for the end face of the anode layer of each battery unit, which can realize the sealing of the end of the anode layer. As a further preference, the end cap and the pressure cap are made of flexible materials. In order to further improve the sealing performance between the end cap and the end surface of the anode layer, it is preferable to provide a first sealing member between the end cap and the end surface of the anode layer. As a further preference, the end cap can form an integral structure with the cathode connector, which is favorable for assembly and integration.

In order to improve the air tightness of the cathode, preferably, a mask is provided on the end face of the cathode layer of each battery unit in the stack to seal the end face of the cathode layer, and the mask is provided with an inlet and outlet for gas circulation. The inlet and outlet of the oxidizing gas flow into the stack to provide the oxidizing gas for the cathode layer of each battery cell. Preferably, a second sealing member with a channel is arranged between the mask and the end face of the cathode layer of each battery cell, so as to further improve the sealing performance.

Preferably, the stack is provided with a pipeline for fuel gas circulation, and the pipeline is connected to the hollow channel of the anode layer of each cell structure unit. In the working state, the fuel gas enters the stack from the pipeline, and then passes through each cell structure unit. The hollow channel of the anode layer flows out of the stack through the pipe. Preferably, the duct includes a duct inlet for fuel gas inflow and a duct outlet for fuel gas outflow.

Compared with the prior art, the present invention has the following beneficial effects:

(1) In the stack of the present invention, the solid oxide fuel cells of the symmetrical double cathode structure are not stacked directly, but a flexible connector with certain mechanical properties is selected as the cathode connector to be arranged between the cathode layers of adjacent battery cells. , so the distance between the battery cells can be adjusted during assembly, so as to ensure that the external dimensions of the stack are consistent, which is convenient for installation and debugging; at the same time, the cathode surfaces of the battery cells can be well fitted, thereby reducing contact resistance and improving electricity. In addition, the battery unit body can be prevented from being damaged during installation and disassembly, and it can be disassembled and reassembled for repeated use, which has a market prospect. When pores are preferably provided on the surface of the cathode connector, the flowability of the oxidizing gas on the cathode surface of each battery cell can be improved.

(2) In the present invention, anode connectors are preferably provided to achieve sealing of the anode layer end faces of each battery cell, and tightness between anode connectors is preferably achieved by providing seals between anode connectors.

(3) In the prior art, the cathode of the solid oxide fuel cell structural unit needs to be sealed, and the cathode usually needs to be provided with a gas channel. In the present invention, the cathode side of the solid oxide fuel cell structural unit can be exposed without considering sealing, and the cathode The plate does not need to be provided with a gas channel, as long as the current is collected, so the difficulty of sealing and assembly is reduced, and the difficulty of battery fabrication is reduced.

Description of drawings

FIG. 1 is an assembly diagram of a solid oxide fuel cell stack with a symmetrical dual cathode structure in an embodiment of the present invention.

FIG. 2 is a detailed assembly view of the solid oxide fuel cell unit of the symmetrical dual cathode structure in FIG. 1 .

Detailed ways

The present invention will be further described in detail below with reference to the embodiments and the accompanying drawings. It should be noted that the following embodiments are intended to facilitate the understanding of the present invention, but do not have any limiting effect on it.

The reference numerals in Fig. 1 are: 1. face mask; 2. second sealing member; 3. cathode pressure plate A; 4. cathode current terminal; 5. first end cap; 6. second end cap; 7, Pressing seat; 8. Conductive rod; 9. Pipe; 10. Gland; 11. Mounting screw; 12. Sealing gasket; 13. Symmetrical double-cathode structure solid oxide fuel cell unit A; 14. First seal; 15 .brittle pin; 16, anode current terminal; 17, mounting screw; 18, cathode pressure plate B; 19, pressure screw; 20, cathode connection unit A; 21, cathode connection unit B; 22, symmetrical double cathode structure solid Oxide fuel cell unit B; 23. Import and export.

In this embodiment, the symmetric double-cathode structure solid oxide fuel cell unit uses the anode as the supporting layer, which is in an up-down distribution structure, that is, in the cell structure unit, the anode layer, the electrolyte layer and the cathode layer are stacked up and down along the thickness direction, and the electrolyte layer The layer includes a first electrolyte layer and a second electrolyte layer, the first electrolyte layer is located on the upper surface of the anode layer, the second electrolyte layer is located on the lower surface of the anode layer; the cathode layer includes a first cathode layer and a second cathode layer, the first cathode layer The layer is located on the upper surface of the first electrolyte layer, and the second cathode layer is located on the lower surface of the second electrolyte layer; and the anode layer is provided with a hollow channel for fuel gas circulation.

The symmetric dual-cathode structure solid oxide fuel cell unit is integrated into a stack.

As shown in Figures 1 and 2, the two adjacent symmetric dual-cathode structure solid oxide fuel cell units are battery unit A13 and battery unit B22, and the second cathode layer of battery unit A13 is opposite to the first cathode layer of battery unit B22 A cathode connection unit A20 and a cathode connection unit B21 are arranged between the battery unit A13 and the battery unit B22. The cathode connection unit A21 and the cathode connection unit B21 are both flexible high-temperature alloys with a certain mechanical strength. The structures of the two cooperate with each other to realize the battery Tight connection of the cathode side between cell A and cell B. These cathode current units in the stack are connected to form a cathode current terminal 4, and the cathode current terminal 4 is connected to the conductive rod 8 to be electrically connected to the outside.

The cathode connecting unit A21 and the cathode connecting unit B21 have pores on the surface for allowing the oxidant gas to pass through to reach the cathode layer, and provide the oxidant gas for the two cathode surfaces of the battery unit A13 and the battery unit B22.

Each battery cell is also provided with an anode connector, and each anode connector is connected by mounting screws 17 to form an anode block current terminal 16, which is connected to the conductive rod 8 and electrically communicated with the outside.

As shown in FIG. 2 , the anode connector includes a first end cap 5 , a second end cap 6 , and a gland 10 . The first end cap 5 and the second end cap 6 are adapted to the peripheral shapes of the two ends of the anode layer and can surround the ends of the anode layer. The gland 10 is adapted to the shape of the end face of the anode layer, and the cover is fastened on the end face of the anode layer by means of mounting screws 11 and sealing gaskets 12 , and a seat 7 is pressed on each gland in the stack. The first end cap 5 , the second end cap 6 and the pressing cap 10 are connected to each other to form a sealing member for the end face of the anode layer of each battery cell, so as to seal the end of the anode layer. In order to further improve the sealing between the end cap and the end face of the anode layer, a first sealing member 14 is provided between the end cap and the end face of the anode layer. In this embodiment, the second end cap 6 and the cathode connecting unit A21 form an integral structure, which is beneficial to assembly and integration.

In this embodiment, the cathode connection unit A20 is arranged on the surface of the first cathode layer of the battery unit on the leftmost side of the stack, the cathode pressure plate A3 is arranged on the surface of the cathode connection unit, and the battery unit on the rightmost side of the stack is arranged on the surface of the first cathode layer. A cathode connection unit A20 is arranged on the surface of the second cathode layer of the cathode, and an anode pressure plate B 18 is arranged on the surface of the cathode connection unit. Apply pressure to the anode pressure plate A3 and the anode pressure plate B18 through the pressure screw 19, so that the battery cells in the stack are tightly connected by the cathode connecting piece. Since the cathode connecting piece is an elastic connecting piece, the connecting piece is avoided. Broken due to pressure and other problems, at the same time, the battery body will not be damaged during installation and disassembly, and it can be disassembled and recycled many times.

In this embodiment, a mask 1 is provided on the end face side of the cathode layer of each battery unit in the stack to seal the end face of the cathode layer, and the mask is provided with an inlet and outlet 4 for gas circulation. In the working state, the oxidizing gas passes through the inlet and outlet 4 It flows into the stack and provides oxidizing gas to the cathode layer of each cell. In order to further improve the sealing performance, a second sealing member 2 with holes is arranged between the mask 1 and the end face of the cathode layer of each battery cell.

In this embodiment, the stack is provided with a pipeline 9 for fuel gas circulation, which communicates with the hollow channel of the anode layer of each cell structural unit. In the working state, the fuel gas enters the stack from the pipeline 9, and then circulates through the hollow channel of the anode layer of each cell structural unit.

The above embodiments describe the technical solutions of the present invention in detail. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Anything done within the scope of the principles of the present invention Any modifications, additions or substitutions in similar manners, etc., shall be included within the protection scope of the present invention.

Claims (9)

1. An integration method of a solid oxide fuel cell stack based on a symmetrical double-cathode structure integrates a plurality of solid oxide fuel cell units with symmetrical double-cathode structures into a stack;

the solid oxide fuel cell unit with the symmetrical double-cathode structure takes an anode as a supporting layer and is of a vertically-distributed structure, namely, in the cell structure unit, an anode layer, an electrolyte layer and a cathode layer are vertically stacked along the thickness direction, the electrolyte layer comprises a first electrolyte layer and a second electrolyte layer, the first electrolyte layer is positioned on the upper surface of the anode layer, and the second electrolyte layer is positioned on the lower surface of the anode layer; the cathode layer comprises a first cathode layer and a second cathode layer, the first cathode layer is positioned on the upper surface of the first electrolyte layer, and the second cathode layer is positioned on the lower surface of the second electrolyte layer; the anode layer is provided with a hollow channel for the circulation of fuel gas;

the method is characterized in that: two adjacent solid oxide fuel cell units with a symmetrical double-cathode structure are a cell unit A and a cell unit B, a second cathode layer of the cell unit A is opposite to a first cathode layer of the cell unit B, a cathode connecting piece is arranged between the cell unit A and the cell unit B, and the cathode connecting piece is a flexible conductive connecting piece; the surface of the cathode connecting piece is provided with a pore channel;

each battery unit is provided with an anode connecting piece;

the anode connecting piece comprises a gland which is matched with the end face of the anode layer in shape and can be buckled on the end face of the anode layer, and an end cover which is matched with the peripheral shape of the end part of the anode layer and can surround the end part of the anode layer; the end cover and the cathode connecting piece form an integrated structure;

arranging a mask on the end face side of the cathode layer of each battery unit in the electric pile, wherein the mask is used for sealing the end face of the cathode layer and is provided with an inlet and an outlet for gas circulation;

the electric pile is provided with a pipeline for fuel gas circulation, and the pipeline is communicated with the hollow channel of the anode layer of each cell structure unit.

2. The method for integrating the solid oxide fuel cell stack based on the symmetrical double cathode structure as claimed in claim 1, wherein: the cathode connecting piece is made of flexible metal or flexible nonmetal.

3. The method for integrating the solid oxide fuel cell stack based on the symmetrical double cathode structure as claimed in claim 2, wherein: the flexible metal material comprises high-temperature alloy and high-temperature functional ceramic.

4. The method for integrating the solid oxide fuel cell stack based on the symmetrical double cathode structure as claimed in claim 2, wherein: the flexible non-metallic material comprises graphite and carbon fiber.

5. The method for integrating the solid oxide fuel cell stack based on the symmetrical double cathode structure as claimed in claim 1, wherein: and two ends of the outer side of the electric pile are provided with pressurizing plates.

6. The method for integrating the solid oxide fuel cell stack based on the symmetrical double cathode structure as claimed in claim 1, wherein: the end cover and the gland are made of flexible materials.

7. The method for integrating the solid oxide fuel cell stack based on the symmetrical double cathode structure as claimed in claim 1, wherein: a first seal is disposed between the end cap and the anode layer end face.

8. The method for integrating the solid oxide fuel cell stack based on the symmetrical double cathode structure as claimed in claim 1, wherein: and a second sealing piece with a pore passage is arranged between the face mask and the end surface of the cathode layer of each battery unit.

9. The method for integrating the solid oxide fuel cell stack based on the symmetrical double cathode structure as claimed in claim 1, wherein: the duct includes a duct inlet for inflow of fuel gas and a duct outlet for outflow of fuel gas.

Images