A secondary fuel cell

Abstract

The application discloses a secondary fuel cell, which comprises a cavity with an opening, a hydrogen storage material arranged in the cavity, a plurality of solid oxide fuel cells, an anode side of the solid oxide fuel cell being connected with the inside of the cavity through the opening, and a cathode side of the solid oxide fuel cell being connected with the outside, and a ventilation pipe with one end connected with the inside of the cavity and the other end connected with a hydrogen storage container or a pipeline. The secondary fuel cell has a simple structure, which is composed of the cavity, the plurality of solid oxide fuel cells and the ventilation pipe, and the structural complexity is greatly reduced compared with a reactor based on a traditional SOFC.

Description

TECHNICAL FIELD

[0001] The present application relates to a secondary fuel cell. BACKGROUND

[0002] Fuel cells can directly convert the chemical energy in fuel (hydrogen) and oxidizing gas (air or oxygen) into electricity through internal electrochemical reactions, and the power generation process is environmentally friendly, efficient and sustainable. The chemical reaction in the fuel cell is not limited by the Carnot cycle, so the energy conversion efficiency of the fuel cell is much higher than that of the internal combustion engine. In recent years, fuel cell technology has gradually matured and is on the verge of large-scale commercialization.

[0003] Solid oxide fuel cells (SOFC) based on oxygen ion conduction are currently a hot research topic, and they can be used as both stationary power sources and small mobile power sources for cars, computers and mobile phones. However, SOFCs can only convert energy and cannot store energy, and the operation of the battery requires a constant supply of fossil fuels, which limits the application of SOFCs.

[0004] Combining SOFCs with hydrogen storage materials to form a reusable secondary fuel cell is an important method to expand the application of SOFCs.

[0005] Compared with SOFCs, the secondary fuel cell has a more complex reaction mechanism, hydrogen production / storage components and other systems, and requires a completely new reactor design.

[0006] However, current secondary fuel cell reactor designs, such as the one proposed by Kevin Huang of the University of South Carolina in a patent (US61627362P0) that inserts a hydrogen storage unit into the traditional SOFC tube reactor structure, and the one proposed by the German Cornelius M. Berger research group (DOI: 10.1111 / jace.14439) that digs holes in the traditional SOFC flat plate reactor structure to place the hydrogen storage unit.

[0007] However, these reactor designs are based on small modifications to the traditional SOFC reactor, and have the following defects. First, the cost is high. Digging holes to place the hydrogen storage unit increases the cost of special-shaped structures and manufacturing, and the hydrogen storage unit is prone to caking. Once the hydrogen storage unit placed in the hole caked, the entire battery stack needs to be disassembled, increasing maintenance costs. Second, the energy density is low. The energy density is determined by the hydrogen storage unit, and the space utilization rate of the traditional SOFC is high, so there is little space to place the hydrogen storage unit. Third, the designability of the reactor based on the traditional SOFC is poor. The energy density and power density are fixed values, and cannot meet the requirements of many common scenarios such as high energy and low power density, and low energy and high power density. SUMMARY

[0008] The main purpose of the present application is to provide a secondary fuel cell.

[0009] The technical scheme adopted by the present application to solve the technical problems is:

[0010] A secondary fuel cell comprises:

[0011] A cavity having an opening;

[0012] A hydrogen storage material arranged in the cavity;

[0013] A plurality of solid oxide fuel cells, the anode side of the solid oxide fuel cells being sealingly connected to the inside of the cavity through the opening, and the cathode side of the solid oxide fuel cells being in communication with the outside;

[0014] An air pipe, one end of which is connected to the inside of the cavity, and the other end of which is connected to a hydrogen storage container or a pipeline.

[0015] The plurality of groups in the present application preferably refers to 2-10 groups.

[0016] In a preferred embodiment, the cavity and the air pipe are respectively made of metal, and the inner and outer surfaces of the cavity and the air pipe are respectively provided with a coating, and the coating is made of ceramic.

[0017] In a preferred embodiment, the thickness of the coating ranges from 0.1 to 500 μm. If the thickness of the ceramic coating is less than 0.1 μm, hydrogen gas is easy to enter the metal to cause hydrogen embrittlement, and if the thickness of the ceramic coating is greater than 500 μm, the pre-sintering process of the metal and the ceramic coating consumes too much energy.

[0018] In a preferred embodiment, the difference between the thermal expansion coefficient of the metal and the thermal expansion coefficient of the ceramic is not more than 40%. When the thermal expansion coefficient of the metal and the thermal expansion coefficient of the ceramic meet the above relationship, the metal and the ceramic are not easy to crack when they expand and contract.

[0019] In a preferred embodiment, the secondary fuel cell further comprises a cavity cover, an anode lead wire, a cathode lead wire and a conductive part, the cavity cover is arranged on the opening of the cavity, the cavity cover is provided with a first through hole corresponding to the number of the solid oxide fuel cells, and the conductive part is arranged on the cavity cover, one side of the conductive part faces the inside of the cavity, and the other side of the conductive part faces the outside;

[0020] The solid oxide fuel cells are fixed in the first through hole, the anode side of the solid oxide fuel cells faces the inside of the cavity, and the cathode side of the solid oxide fuel cells faces the outside;

[0021] The cathode of the solid oxide fuel cell is connected to the negative pole of the external working circuit through the cathode lead wire, and the anode of the solid oxide fuel cell is connected to the positive pole of the external working circuit through the conductive part and the anode lead wire in turn.

[0022] In a preferred embodiment, the conductive part is a conductive sheet, the cavity cover is provided with second through holes corresponding to the number of the conductive sheets, and the conductive sheets are fixed in the second through holes. The anode of the solid oxide fuel cell is connected to the positive pole of the external working circuit through the conductive sheet and the anode lead wire in turn.

[0023] In a preferred embodiment, the first through holes and the second through holes are stepped holes.

[0024] In a preferred embodiment, the cavity cover is provided with two air pipes, each of which is provided with a lead wire pipe. The cathode lead wire passes through one of the lead wire pipes to connect to the negative pole of the external working circuit, and the anode lead wire passes through the other lead wire pipe to connect to the positive pole of the external working circuit.

[0025] In a preferred embodiment, the cavity cover is provided with conductive sheets, and the cathode lead wire is connected to the conductive sheets.

[0026] In a preferred embodiment, the secondary fuel cell includes four groups of solid oxide fuel cells, the cavity cover is square, the cavity cover is provided with four first through holes and one second through hole, the first through holes are respectively arranged at the four corners of the cavity cover, and the second through hole is arranged at the center of gravity of the cavity cover. The solid oxide fuel cells are fixed in the first through holes, the anode side of the solid oxide fuel cells faces the inside of the cavity, and the cathode side of the solid oxide fuel cells faces the outside. The conductive part is a conductive sheet, the conductive sheet is fixed in the second through hole, and the anode of the solid oxide fuel cell is connected to the positive pole of the external working circuit through the conductive sheet and the anode lead wire in turn.

[0027] In a preferred embodiment, the hydrogen storage material is a material capable of reversibly storing and releasing hydrogen, which can be an alloy hydrogen storage material, an inorganic hydrogen storage material, or an organic hydrogen storage material.

[0028] In a preferred embodiment, the hydrogen storage material is preferably a hydrogen storage material capable of reacting with water to produce hydrogen, and is preferably at least one of sodium, magnesium, calcium, aluminum, silicon, zinc, iron, lead, tin, nickel, and carbon, and is more preferably at least one of magnesium-graphite, magnesium-iron, magnesium-carbon nanotube, iron-graphene, magnesium-copper, and magnesium-nickel.

[0029] In a preferred embodiment, the cavity is heated and maintained at a predetermined temperature by a heating device.

[0030] Compared with the background art, the technical solution has the following advantages:

[0031] 1. The secondary fuel cell of the present application has a simple structure, which is composed of a cavity, multiple groups of solid oxide fuel cells, and a gas pipe, etc. Compared with the existing reactor based on the traditional SOFC, the structural complexity is greatly reduced. The energy density of the secondary fuel cell is determined by the hydrogen storage capacity of the hydrogen storage unit. The internal space of the reactor cavity is large, which is much higher than the space of the traditional SOFC with a hole plugged into the hydrogen storage unit. The storage space is large, and the energy density is greatly improved.

[0032] 2. The cavity, cavity cover, and gas pipe of the present application are made of metal, which has strong designability. The metal material properties of the reactor make the reactor cavity can be made into various shapes to adapt to different working environments. In addition, the energy density and power density of the reactor can be designed separately to adapt to different working scenarios. The energy density is determined by the hydrogen storage capacity and can be realized by controlling the storage capacity of the hydrogen storage unit. The power density is determined by the number of battery pieces and can be realized by controlling the number of grooves to place different number of battery pieces.

[0033] 3. Multifunctional, can switch to traditional SOFC mode when the power is depleted, continue to work with fuel, and switch to traditional SOEC mode when the power is surplus, store excess fuel.

[0034] 4. Low material cost, the metal can use cheap and durable stainless steel, and the sealing paste can use cheap glass powder, which greatly reduces the cost. BRIEF DESCRIPTION OF DRAWINGS

[0035] The present application will be further described below in conjunction with the drawings and examples.

[0036] Figure 1 It is a structural schematic diagram of the secondary fuel cell of the present application.

[0037] Figure 2 It is a structural schematic diagram of the cavity and pipe.

[0038] Figure 3 It is a structural schematic diagram of the cavity cover.

[0039] Figure 4 It is a structural schematic diagram of the battery piece.

[0040] Figure 5 It is a structural schematic diagram of the conductive sheet.

[0041] Figure 6 It is a connection schematic diagram of the first wire.

[0042] Figure 7 It is a connection schematic diagram of the second wire.

[0043] Figure 8 Fig. 1 is a schematic diagram of the principle of the present application.

[0044] Reference numerals:

[0045] A1 - connector; A2 - anode; A3 - hydrogen storage unit; A4 - cathode; A5 - load; A6 - power supply; A7 - pump; A8 - Fe-Fe304;

[0046] B1 - partial schematic diagram; B2 - sealing material; B3 - connector; B4 - current collector; B5 - air electrode; B6 - electrolyte; B7 - fuel electrode; B8 - current collector; B9 - hydrogen storage unit;

[0047] 1 - cavity; 2 - cavity cover; 3 - cell; 4 - conductive sheet; 5 - first lead wire; 6 - second lead wire; 7 - hydrogen storage material; 8 - first air tube; 9 - first lead tube; 10 - second air tube; 11 - second lead tube; DETAILED DESCRIPTION

[0048] Please refer to Figure 1 A secondary fuel cell includes a cavity 1, which is a square-shaped body with an open top in this embodiment. A square-shaped cavity cover 2 is provided at the open top.

[0049] See Figures 2 to 5 The cavity cover 2 is square-shaped, and four square-shaped holes, i.e., a first square-shaped hole 2-1, a second square-shaped hole 2-2, a third square-shaped hole 2-3, and a fourth square-shaped hole 2-4, are provided at the four corners of the cavity cover. A fifth square-shaped hole 2-5 is provided at the center of the cavity cover. The five square-shaped holes are all stepped holes, i.e., the upper half of the hole is large, and the lower half is small, forming a step between the upper half and the lower half. A cell 3 is provided in each of the first square-shaped hole 2-1, the second square-shaped hole 2-2, the third square-shaped hole 2-3, and the fourth square-shaped hole 2-4. A conductive sheet 4 is provided in the fifth square-shaped hole 2-5, and the conductive sheet 4 is square-shaped corresponding to the square-shaped hole.

[0050] The cell 3 is provided with an anode facing downward and a cathode facing upward, and the cell 3 and the conductive sheet 4 are sealed by a sealing ring.

[0051] The anode is formed of, for example, LSM, LSC, or the like, and has a catalytic function for the reduction reaction of oxygen and the oxidation reaction of water, in addition to electronic conductivity, air permeability, and stability in an oxidizing atmosphere.

[0052] The cathode is formed of, for example, a composite material of yttria-stabilized zirconia and nickel, and has a catalytic function for the oxidation reaction of hydrogen and the reduction reaction of hydrogen ions, in addition to electronic conductivity, air permeability, and stability in a reducing atmosphere.

[0053] A hydrogen storage material 7 is arranged in the cavity 1, and the hydrogen storage material 7 is a material capable of reversibly storing and releasing hydrogen, such as one or more of magnesium-graphite, magnesium-iron, magnesium-carbon nanotube, iron-graphene, magnesium-copper, and magnesium-nickel.

[0054] The cavity 1 is connected with a first air pipe 8 and a second air pipe 10, the first air pipe 8 is provided with a first wire pipe 9, and the second air pipe 10 is provided with a second wire pipe 11. The first wire pipe 9 and the second wire pipe 11 are both ceramic pipes.

[0055] Referring to Figure 6 and Figure 7 , the first wire 5 includes a circular part 5-1 connected with the positive poles of the four batteries and a wire 5-2 connected with the circular part 5-1 and passing through the second wire pipe 11. The second wire 6 includes a cross-shaped part 6-2, and four end points of the cross-shaped part 6-1 are respectively connected with the negative poles of the four battery pieces, and the intersection point is connected with the lower surface of the conductive sheet 4. One end of the wire 6-1 is located on the upper surface of the conductive sheet 4, and the other end passes through the first wire pipe 9. The first wire pipe 9 and the second wire pipe 11 can prevent the wires from contacting with metal.

[0056] In the present application, the inner and outer surfaces of the cavity 1, the upper and lower surfaces of the cavity cover 2, and the inner and outer surfaces of the first air pipe 8 and the second air pipe 12 are all provided with a ceramic coating. The thickness of the coating is about 200 μm. The difference between the thermal expansion coefficient of the metal and the thermal expansion coefficient of the ceramic is not more than 40%. In this way, the ceramic coating is not easy to crack when it expands and contracts with heat.

[0057] The assembly of the present application is as follows:

[0058] The inner and outer surfaces of the cavity 1, the upper and lower surfaces of the cavity cover 2, and the inner and outer surfaces of the first air pipe 8 and the second air pipe 12 are coated with sealing paste, and then placed in a muffle furnace and dried at 200℃ for 2h;

[0059] The hydrogen storage unit is placed in the cavity;

[0060] The sealing ring (a glass sealing ring resistant to 850℃, which can be commercially purchased), the conductive sheet, and the battery pieces are sequentially placed in the square holes (2-1 / 2-2 / 2-3 / 2-4) at the four corners of the cavity cover, and the sealing ring and the conductive sheet are sequentially placed in the fifth square hole 2-5 in the center of the cavity cover 2;

[0061] The silver wire is connected with the battery pieces and the conductive sheet 4 by using conductive silver paste according to the distribution mode of the first wire 5 and the second wire 6, and the cavity cover with the completed connection is placed in a muffle furnace, and the conductive silver paste is cured according to the procedure of "30℃-12h, 80℃-4h, 150℃-2h, and a temperature rising rate of 1℃ / min";

[0062] The first wire tube 9 and the second wire tube 11 with silver wire in the middle are fixed on the first air pipe 8 and the second air pipe 10 respectively by iron wire;

[0063] The sealing paste is coated on the connection between the cavity cover 2 and the cavity 1, the cavity cover 2 is covered, the silver wire on the cover is connected with the silver wire on the first air pipe 8 and the second air pipe 10, the reactor is placed in a muffle furnace, the temperature is raised at a rate of 2 ℃ / min to 850 ℃, and the reactor is prepared for 4 h.

[0064] The principle of the application is as shown in Figure 8

[0065] 1. Secondary fuel cell mode:

[0066] The discharging process is as follows, the valves connected after the first air pipe 8 and the second air pipe 10 are closed, the silver wire led out of the ceramic tube (the first wire tube 9 and the second wire tube 11) is connected to the working circuit, the reactor is placed in a muffle furnace, the temperature is raised at a rate of 2 ℃ / min to 850 ℃, the hydrogen storage unit releases hydrogen, the anode side of the battery sheet is downwardly contacted with hydrogen and reacts H2+O 2- 2e-,the electron flows from the anode to the cathode through the working circuit, the cathode side of the battery sheet is upwardly exposed to air and reacts O2+4e-=2O 2- , and the total reaction is 2H2+O2=2H2O.

[0067] In other embodiments, the muffle furnace can also be replaced by a resistance heating body, arc heating, induction heating, medium heating, microwave heating, etc., which can perform heating at about 650 ℃-1000 ℃, and can be operated by external power supply.

[0068] The charging process is as follows, the positive and negative electrodes of the power supply are connected with the silver wire led out of the ceramic tube, the anode of the battery sheet loses electrons and reacts 2O2-=O2+4e-, the cathode of the battery sheet obtains electrons and reacts H2O+2e-=H2+O 2- , the total reaction is 2H2O=2H2+O2, and the generated hydrogen is stored in the hydrogen storage unit.

[0069] 2. Emergency mode / conventional SOFC mode: when the power is exhausted and it is inconvenient to charge, the hydrogen tank valve connected after the first air pipe 8 and the second air pipe 10 is opened to input hydrogen, and the discharging process of the fuel cell continues.

[0070] 3. SOEC mode / fuel synthesis mode: after charging is completed, the hydrogen tank valve connected after the first air pipe 8 and the second air pipe 10 is opened, and the discharged hydrogen is collected.

[0071] ​The above merely describes preferred embodiments of the present application, and therefore cannot limit the scope of the present application, i.e. equivalent changes and modifications made according to the patent scope and content of the present application should still fall within the scope of the present application.

Claims

1. A secondary fuel cell, characterized by: The application relates to a secondary fuel cell, which comprises: a cavity with an opening; a hydrogen storage material arranged in the cavity; a plurality of solid oxide fuel cells, the anode side of the solid oxide fuel cells being connected to the inside of the cavity through the opening, and the cathode side of the solid oxide fuel cells being connected to the outside; During discharge, the hydrogen storage material in the chamber releases hydrogen gas, which contacts the solid oxide fuel cell anode side and reacts H2+ O 2- =H2O+2e - The electrons flow from the anode to the cathode through the working circuit, and the cell cathode side is exposed to air and reacts O2+4e - =2O 2- The overall reaction is 2H2+O2=2H2O; During charging, the positive electrode of the battery sheet loses electrons and undergoes the reaction 2O2-=O2+4e - , the negative electrode of the battery sheet gains electrons and undergoes the reaction H2O+2e - =H2+O 2- , and the generated hydrogen is stored in the hydrogen storage material in the cavity. an air pipe, one end of which is connected to the inside of the cavity, and the other end of which is connected to a hydrogen storage container or a pipeline.

2. A secondary fuel cell according to claim 1, characterised in that: The cavity and the air pipe are made of metal, and the inner and outer surfaces of the cavity and the air pipe are respectively provided with a coating made of ceramic.

3. A secondary fuel cell according to claim 2, characterised in that: The thickness of the coating is 0.1-500 microns.

4. A secondary fuel cell according to claim 2, wherein: The difference between the thermal expansion coefficient of the metal and the thermal expansion coefficient of the ceramic is not more than 40%.

5. The secondary fuel cell of claim 1, wherein: The secondary fuel cell further comprises a cavity cover, anode wires, cathode wires and conductive parts, the cavity cover is arranged on the opening of the cavity, the cavity cover is provided with a plurality of first through holes corresponding to the number of the solid oxide fuel cells, the conductive parts are arranged on the cavity cover, one side of the conductive parts faces the inside of the cavity, and the other side of the conductive parts faces the outside; The solid oxide fuel cells are fixed in the first through holes, the anode side of the solid oxide fuel cells faces the inside of the cavity, and the cathode side of the solid oxide fuel cells faces the outside; The cathode of the solid oxide fuel cell is connected to the negative electrode of an external working circuit through the cathode wire, and the anode of the solid oxide fuel cell is connected to the positive electrode of the external working circuit through the conductive part and the anode wire in sequence.

6. A secondary fuel cell according to claim 5, characterised in that: The conductive part is a conductive sheet, the cavity cover is provided with a plurality of second through holes corresponding to the number of the conductive sheets, the conductive sheets are fixed in the second through holes, and the anode of the solid oxide fuel cell is connected to the positive electrode of the external working circuit through the conductive sheet and the anode wire in sequence.

7. A secondary fuel cell according to claim 6, characterised in that: The first through holes and the second through holes are stepped holes.

8. A secondary fuel cell according to claim 5, wherein: The air pipe has two, each of the air pipes is provided with a wire pipe, the cathode wire passes through one of the wire pipes to be connected to the negative electrode of the external working circuit, and the anode wire passes through the other wire pipe to be connected to the positive electrode of the external working circuit.

9. A secondary fuel cell according to claim 5, wherein: The application further comprises a conductive sheet arranged on the cavity cover, and the cathode wire is connected to the conductive sheet.

10. A secondary fuel cell according to any one of claims 1 to 9, characterised in that: The application further comprises a heating device, which is used for heating and maintaining the cavity at a temperature above a predetermined temperature.

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