A direct carbon fuel cell, a method for manufacturing the same, and a direct carbon fuel cell stack

Abstract

The application discloses a direct carbon fuel cell and a preparation method and a direct carbon fuel cell stack thereof, and relates to the technical field of fuel cells. The direct carbon fuel cell comprises a single cell, an oxidant and fuel. The single cell comprises a first silver-plated support net, a cathode, an electrolyte layer, an anode and a second silver-plated support net which are sequentially stacked. The oxidant is applied to the side of the first silver-plated support net and is used for reacting with the cathode. The fuel is applied to the side of the second silver-plated support net and is used for reacting with the anode. The oxidant comprises air and carbon dioxide. The mixed gas of carbon dioxide and air is applied to the side of the first silver-plated support net as the oxidant and is used for reacting with the cathode. The carbon dioxide significantly promotes the redox reaction efficiency of the cell, reduces the reaction activation energy, greatly improves the ionic conductivity (which is doubled at 680 DEG C), and improves the electrochemical reaction life, open-circuit voltage, current and power density of the cell.

Description

Technical Field

[0001] This invention relates to the field of fuel cell technology, and in particular to a direct carbon fuel cell, its preparation method, and a direct carbon fuel cell stack. Background Technology

[0002] Currently, direct carbon fuel cells (DCFCs) are a cutting-edge energy conversion technology. Specifically, they are novel fuel cells that use solid carbon (coal, graphite, activated carbon, biochar, etc.) as fuel and directly output electrical energy through an electrochemical oxidation reaction. The carbon dioxide and carbon ash emitted during the energy conversion process are easily collected and reused. Traditional direct carbon fuel cells generally use solid oxide fuel cells (SOFCs) reactors, which produce carbon dioxide through the reaction of carbon and oxygen ions at high temperatures (>700 °C), converting the chemical energy of the carbon fuel into electrical energy. However, traditional direct carbon fuel cells generally suffer from the following problems:

[0003] 1. High electrochemical reaction activation energy, low ionic conductivity, and low power density (<200 mW / cm²). 2 The reaction is unstable;

[0004] 2. The reaction requires a high temperature, and the stability of operation at medium temperature (600~700 ℃) is poor. The continuous operation time is short, generally not exceeding 24 hours, and the power output fluctuates greatly.

[0005] 3. Limited fuel loading capacity and unsustainable fuel supply make the anode layer prone to ash (carbon ash). Ash accumulation will isolate the anode from the fuel reaction, thus affecting the battery's operating life and stability.

[0006] 4. Traditional anode structures struggle to balance conductivity, catalytic activity, and structural stability, and excellent electrochemical catalytic activity relies on expensive rare metal catalyst materials or complex synthesis processes.

[0007] The aforementioned inherent limitations restrict the industrial application of direct carbon fuel cells. Therefore, existing technologies urgently need to be improved and developed to meet industrial requirements. Summary of the Invention

[0008] Based on the shortcomings of the prior art, the purpose of this invention is to provide a direct carbon fuel cell, its preparation method, and a direct carbon fuel cell stack, aiming to solve the problems of high activation energy, high reaction temperature, low ionic conductivity, low power density, and short reaction life of traditional direct carbon fuel cells.

[0009] The technical solution of the present invention is as follows:

[0010] In a first aspect, the present invention provides a direct carbon fuel cell, wherein the direct carbon fuel cell comprises a single cell, an oxidant, and fuel;

[0011] The single cell includes a first silver-plated support mesh, a cathode, an electrolyte layer, an anode, and a second silver-plated support mesh, which are stacked in sequence.

[0012] The oxidant is applied to the side of the first silver-plated support mesh to react with the cathode;

[0013] The fuel is applied to the second silver-plated support mesh side for reacting with the anode;

[0014] The oxidant includes air and carbon dioxide.

[0015] Optionally, the direct carbon fuel cell further includes:

[0016] A ceramic tube for containing fuel is disposed on the single cell and attached to the second silver-plated support mesh. The top of the ceramic tube is provided with a through hole, and the side wall of the ceramic tube is provided with a sealable fuel inlet pipe and a sealable ash outlet pipe, respectively.

[0017] A pressure plate is disposed inside the ceramic tube;

[0018] The lifting pipe has one end connected to the pressure plate and the other end passing through the through hole and can move up and down in the through hole. An exhaust hole is provided on the side wall of the lifting pipe near the pressure plate. The lifting pipe is used to drive the pressure plate to move up and down and to introduce nitrogen into the ceramic tube.

[0019] The first silver wire is drawn out from the first silver-plated support mesh;

[0020] The second silver wire is drawn out from the second silver-plated support mesh.

[0021] Optionally, the oxidant, by volume percentage, consists of the following components:

[0022] Air 66% and carbon dioxide 34%.

[0023] Optionally, the fuel includes a first fuel and a second fuel, wherein the first fuel includes at least one of anthracite, bituminous coal, biochar, activated carbon and graphite, and the second fuel includes a carbonate, wherein the carbonate includes at least one of lithium carbonate, sodium carbonate and potassium carbonate.

[0024] Optionally, the fuel includes anthracite and carbonates, wherein the molar ratio of the anthracite to the carbonates is (80~95):(5~20); the carbonates include lithium carbonate, sodium carbonate and potassium carbonate in a molar ratio of 1:1:1.

[0025] Optionally, the electrolyte layer includes a first electrolyte layer and a second electrolyte layer, and an electrolyte powder layer located between the first electrolyte layer and the second electrolyte layer;

[0026] The first electrolyte layer, the second electrolyte layer, and the electrolyte powder layer all include electrolyte A and electrolyte B, and the molar ratio of electrolyte A to electrolyte B is (0.176~1.5):1;

[0027] Electrolyte A includes carbonates, and electrolyte B includes oxide electrolytes;

[0028] The oxide electrolyte includes at least one of samarium oxide-doped cerium oxide, CeO2, ZrO2, and lanthanum, strontium, gallium, and magnesium oxide.

[0029] Optionally, the cathode is a porous cathode, and the anode is a porous anode;

[0030] The porous cathode includes a cathode material, an electrolyte C, pore-forming graphite, and a binder, wherein the electrolyte C includes at least one of electrolyte A and electrolyte B;

[0031] The porous anode includes an anode material, an electrolyte D, pore-forming graphite, and a binder, wherein the electrolyte D includes at least one of electrolyte A and electrolyte B;

[0032] The first silver-plated support mesh includes a silver-plated metal mesh or a silver-plated non-metal mesh. The silver-plated metal mesh includes one of a silver-plated stainless steel mesh, a silver-plated nickel mesh, or a silver-plated copper mesh. The silver-plated non-metal mesh includes a silver-plated ceramic mesh.

[0033] The second silver-plated support mesh includes a silver-plated metal mesh or a silver-plated non-metal mesh. The silver-plated metal mesh includes one of a silver-plated stainless steel mesh, a silver-plated nickel mesh, or a silver-plated copper mesh, and the silver-plated non-metal mesh includes a silver-plated ceramic mesh.

[0034] A second aspect of the present invention provides a method for preparing a direct carbon fuel cell as described above, wherein the preparation method comprises the following steps:

[0035] The electrolyte material membrane, the anode material membrane, and the second silver-plated support mesh are stacked sequentially and then pre-pressed at room temperature to form a half-cell blank.

[0036] The half-cell blank is placed at a first preset temperature and kept at that temperature for a first preset time, and then kept at a first preset pressure for a second preset time. After cooling, a half-cell is obtained.

[0037] The cathode material slurry is coated onto the electrolyte material membrane in the half cell to form a cathode coating layer. Then, the first silver-plated stainless steel mesh is pressed onto the cathode coating layer. After drying, it is annealed at a second preset temperature for a third preset time. After cooling, a single cell is obtained, which includes a first silver-plated support mesh, a cathode, an electrolyte layer, an anode, and a second silver-plated support mesh stacked in sequence.

[0038] An oxidant is applied to the first silver-plated support mesh side, and fuel is applied to the second silver-plated support mesh side to obtain the direct carbon fuel cell.

[0039] Optionally, the pre-compression pressure is 0.1~1 ton / cm; the first preset temperature is 500~650 ℃, the first preset time is 30~90 min, the first preset pressure is 5~20 tons, the second preset time is 1~10 min; the second preset temperature is 500~700 ℃, and the third preset time is 2~6 h.

[0040] In a third aspect, the present invention provides a direct carbon fuel cell stack, wherein the direct carbon fuel cell stack comprises a plurality of direct carbon fuel cells as described above or a plurality of direct carbon fuel cells prepared by the preparation method described above.

[0041] Beneficial effects: This invention uses a mixture of carbon dioxide and air as an oxidant. Carbon dioxide can promote redox reactions, significantly reduce the activation energy (down to 0.47 eV), and increase ionic conductivity (up to 0.275 S / cm). This improves the electrochemical reaction lifetime, open-circuit voltage, current, and power density of direct carbon fuel cells. Furthermore, the peak power density can reach 590 mW / cm² at 600 °C and 680 °C, respectively. 2 and 830 mW / cm 2 . Attached Figure Description

[0042] Figure 1 This is a schematic diagram of a direct carbon fuel cell.

[0043] Figure 2 This is a schematic diagram of the fabrication process for a single cell.

[0044] Figure 3 The image shows the X-ray diffraction pattern of the 30 mol% carbonate-SDC electrolyte material in Example 1.

[0045] Figure 4The images shown are scanning electron microscope (SEM) images of the single cell cross section and the elemental distribution map of the single cell cross section measured by energy dispersive spectroscopy in Example 1. Among them, (a) is the elemental distribution map of the single cell cross section, (b) is the SEM image of the single cell cross section, and (c) is the SEM image of the 30 mol% carbonate-SDC electrolyte material.

[0046] Figure 5 The figures show the electrochemical performance test results of direct carbon fuel cells at different temperatures using different oxidants. Among them, (a) is the current-voltage curve and current-power density curve when air is used as the oxidant, (b) is the current-voltage curve and current-power density curve when a mixture of air and carbon dioxide is used as the oxidant, (c) is the impedance spectrum when air is used as the oxidant, and (d) is the impedance spectrum when a mixture of air and carbon dioxide is used as the oxidant.

[0047] Figure 6 The graphs show the conductivity and activation energy of a direct carbon fuel cell at 680 °C using different oxidants. (a) shows the conductivity results, and (b) shows the activation energy results.

[0048] Figure 7 (a) shows the thermogravimetric analysis results of anthracite in nitrogen and air atmospheres, respectively; (b) shows the results of the direct carbon fuel cell in Example 1 using a mixture of air and carbon dioxide as the oxidant at 0.2 A / cm². 2 The result of long-term operation under the current is shown in the figure.

[0049] Figure 8 The graph shows the electrochemical performance test results of the direct carbon fuel cell in Comparative Example 2 at 680 °C.

[0050] Appendix Figure 1 The number in the middle:

[0051] 1. Single cell; 11. Cathode; 111. First silver wire; 12. Electrolyte layer; 13. Anode; 131. Second silver wire; 2. Ceramic tube; 3. Fuel feed pipe; 31. First valve; 32. Second valve; 33. Third valve; 4. Ash discharge pipe; 41. Fourth valve; 42. Fifth valve; 5. Pressing plate; 6. Lifting pipe; 61. Exhaust port. Detailed Implementation

[0052] This invention provides a direct carbon fuel cell, its preparation method, and a direct carbon fuel cell stack. To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention is further described in detail below. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0053] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0054] The terms used in this document, such as “vertical,” “horizontal,” “up,” “down,” “left,” “right,” and similar expressions, are for illustrative purposes only and do not represent the only possible implementation.

[0055] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0056] If the embodiments of the present invention involve descriptions such as "first" or "second", such descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated.

[0057] This invention provides a direct carbon fuel cell, wherein, as... Figure 1 As shown (the first and second silver-plated support meshes are not shown), the direct carbon fuel cell includes a single cell 1, an oxidant, and fuel.

[0058] The single cell 1 includes a first silver-plated support mesh, a cathode 11, an electrolyte layer 12, an anode 13, and a second silver-plated support mesh, which are stacked in sequence.

[0059] The oxidant is applied to the side of the first silver-plated support mesh to react with the cathode;

[0060] The fuel is applied to the second silver-plated support mesh side for reacting with the anode;

[0061] The oxidant includes air and carbon dioxide.

[0062] In this embodiment, the direct carbon fuel cell uses a mixture of carbon dioxide and air as the oxidant. Carbon dioxide assists the reaction, improves polarization behavior, reduces resistance, and expands the three-phase reaction interface (TPB) range. Carbon dioxide can promote redox reactions, significantly reduce the activation energy (down to 0.47 eV), and increase ionic conductivity (up to 0.275 S / cm), thereby improving the battery's electrochemical reaction lifetime, open-circuit voltage, current, and power density. Furthermore, the peak power density can reach 590 mW / cm² at 600 °C and 680 °C, respectively. 2 and 830 mW / cm 2 .

[0063] When only air is used as the oxidant, the carbonates in the battery (i.e., the carbonates in the electrolyte layer) are in a glassy semi-molten state. The alkali metal ions in these carbonates combine with oxygen ions to form high-melting-point alkali metal oxides (M₂O, where M is Na, K, or Li). Because their melting point is higher than the battery's operating temperature, these alkali metal oxides accumulate at the cathode, reducing the battery's electrochemical performance. When carbon dioxide and air are used together as the oxidant, the high-melting-point alkali metal oxides react with carbon dioxide to form alkali metal carbonates, which then ionize into alkali metal ions and carbonate ions (metastable state), providing a large amount of free radicals—carbonate ions. This large amount of carbonate ions, driven by concentration gradient, replenishes the anode where carbonate ions are largely consumed, thereby increasing ionic conductivity and lowering the activation energy of the reaction.

[0064] In addition, the silver-plated support mesh has excellent electronic conductivity, which not only strengthens the support of the battery substrate, but also plays an excellent role in current collection.

[0065] In some implementations, such as Figure 1 As shown, the direct carbon fuel cell further includes:

[0066] A ceramic tube 2 for containing fuel is disposed on the single cell 1 and attached to the second silver-plated support mesh. A through hole is provided at the top of the ceramic tube 2, and a sealable fuel inlet pipe 3 and a sealable ash outlet pipe 4 are respectively provided on the side wall of the ceramic tube 2.

[0067] The pressing plate 5 is disposed inside the ceramic tube 2;

[0068] The lifting pipe 6 is connected to the pressure plate 5 at one end and passes through the through hole at the other end, and can move up and down in the through hole. An exhaust hole 61 is provided on the side wall of the lifting pipe 6 near the pressure plate 5. The lifting pipe 6 is used to drive the pressure plate 5 to move up and down and to introduce nitrogen into the ceramic tube 2.

[0069] The first silver wire 111 is drawn out from the first silver-plated support mesh;

[0070] The second silver wire 131 is drawn out from the second silver-plated support mesh.

[0071] Existing direct carbon fuel cells cannot achieve continuous feeding; the battery stops operating after the fuel is used up in a single cycle, and the fuel capacity is limited, leading to ash accumulation. Accumulated ash can isolate or reduce the contact between the anode and the fuel, thus affecting the electrochemical reaction. In this embodiment, the direct carbon fuel cell is a continuously fed direct carbon fuel cell supported by a silver-plated support mesh. Fuel can continuously enter through the fuel feed pipe, while ash can continuously exit through the ash discharge pipe, effectively solving the problems of ash accumulation (anode carbon ash can isolate the reaction) and fuel interruption (existing fuel loading capacity is limited, and fuel supply is unsustainable). The pressure plate continuously descends to contact the fuel (e.g., fuel including anthracite and carbonates) inside the ceramic tube, applying pressure to the fuel. This results in tighter contact between the anthracite particles and a denser network formed by the molten carbonate, thereby shortening the ion transport distance. Simultaneously, the tighter contact between the anthracite and carbonates creates a larger contact area, which is more conducive to the reaction of carbon in the anthracite with carbonate ions to produce carbon monoxide, facilitating the full conduct of the electrochemical reaction.

[0072] Before the battery is used, excess air is removed by introducing nitrogen into the riser pipe and then into the ceramic tube through the exhaust port. This prevents the presence of air from oxidizing the fuel (such as anthracite) and thus reducing the fuel utilization rate.

[0073] In some implementations, such as Figure 1 As shown, the sealable fuel feed pipe 3 is equipped with three valves arranged at intervals, namely a first valve 31, a second valve 32, and a third valve 33. Specifically, when the inner diameter of all parts of the fuel feed pipe is the same, the distance between the first valve 31 and the second valve 32 is greater than the distance between the second valve 32 and the third valve 33 (i.e., the pipe length between the first valve and the second valve is greater than the pipe length between the second valve and the third valve). When the inner diameter of all parts of the fuel feed pipe is not the same, the pipe volume between the first valve 31 and the second valve 32 is greater than the pipe volume between the second valve 32 and the third valve 33.

[0074] When refueling is required, firstly, open the first valve 31 while keeping the second valve 32 and the third valve 33 closed. This prevents air from entering the ceramic tube 2. Once the fuel is filled to the first valve 31 (i.e., fuel is being filled into the pipe between the first valve 31 and the second valve 32), close the first valve 31. Then, open the second valve 32 to allow the fuel to reach the third valve 33. At this point, close the second valve 32. Because the distance between the first valve 31 and the second valve 32 is greater than the distance between the second valve 32 and the third valve 33, some fuel will not enter the pipe between the second valve 32 and the third valve 33 when the second valve is closed. Instead, it will remain in the pipe between the first valve 31 and the second valve 32. This partial fuel in the pipe between the first valve 31 and the second valve 32 can effectively isolate air. Finally, open the third valve 33 to allow fuel to enter the ceramic tube, and then close the third valve 33.

[0075] The sealable ash discharge pipe 4 is equipped with two valves arranged at intervals, namely the fourth valve 41 and the fifth valve 42.

[0076] When it is necessary to remove the ash, first open the fifth valve 42 while the fourth valve 41 remains closed to push the ash outwards. Then close the fifth valve 42, and then open the fourth valve 41 to discharge the ash before closing the fourth valve 41 again.

[0077] Therefore, it can be seen that the present invention, through the rational design of the valves on the fuel feed pipe and ash discharge pipe, can isolate air during fuel replenishment and ash removal, thus preventing air from entering the ceramic tube and affecting the performance of the direct carbon fuel cell.

[0078] In some embodiments, the oxidant comprises, by volume percentage, the following components:

[0079] Air 66% and carbon dioxide 34%.

[0080] This ratio has the best effect in reducing the activation energy of the reaction, increasing ionic conductivity, and improving the open-circuit voltage, current and power density of the battery.

[0081] In some embodiments, the fuel includes a first fuel and a second fuel. The first fuel includes at least one of anthracite, bituminous coal, biochar, activated carbon, and graphite, but is not limited thereto. The second fuel includes carbonates, including at least one of lithium carbonate, sodium carbonate, and potassium carbonate, but is not limited thereto. In this case, the direct carbon fuel cell may not contain an anode, because anthracite and carbonates (molten state) have ion and electron conduction functions. When the anode is missing, the fuel has the ion and electron conduction functions of the anode and acts as the anode.

[0082] In some embodiments, the molar ratio of the first fuel to the second fuel is (80~95):(5~20), for example, it can be 80:20, 90:10 or 95:5, etc.

[0083] In some embodiments, the fuel comprises anthracite and carbonates, wherein the molar ratio of anthracite to carbonate is (80-95):(5-20); the carbonate comprises lithium carbonate, sodium carbonate, and potassium carbonate in a molar ratio of 1:1:1. This ratio allows the direct carbon fuel cell to achieve optimal performance. For example, the molar ratio of anthracite to carbonate is 80:5, 80:8, 80:12, 80:20, 88:5, 88:8, 88:12, 88:20, 95:5, 95:8, 95:12, or 95:20, etc.

[0084] In this embodiment, introducing carbonates into the fuel can solve the problem of discontinuous electrochemical reactions caused by ash accumulation, which is easily interrupted in existing direct carbon fuel cells. Specifically, by introducing carbonates into the fuel, the carbon oxidation reaction region can be extended from the two-dimensional plane close to the anode to the three-dimensional direction along the ceramic tube, which can accelerate the conversion of fuels such as coal and carbon into CO and its transfer to the anode interface. In addition, carbonates act as an electrochemical oxidation medium for carbon, reacting with carbon to generate CO and CO2, thereby increasing the carbon oxidation rate. Traditional direct carbon fuel cells do not contain carbonates and have a very small fuel loading. Therefore, once the carbon-containing solid fuel in contact with the anode turns into ash, it will block the contact between the fuel and the electrode, thus blocking C+2O. 2- -4e - = CO2 reaction. In this invention, the fuel is specially designed. Because it is mixed with carbonates, and the proportion of the mixed carbonates ensures that it can remain in a molten state within the reaction temperature range, the molten carbonates and carbon can fully react in three dimensions to generate CO. The CO gas can be distributed throughout the entire ceramic cavity, thereby solving the problem that the electrochemical reaction of existing direct carbon fuel cells is easily interrupted by ash accumulation, resulting in discontinuous electrochemical reaction.

[0085] In some embodiments, the electrolyte layer includes a first electrolyte layer and a second electrolyte layer, and an electrolyte powder layer located between the first electrolyte layer and the second electrolyte layer;

[0086] The first electrolyte layer, the second electrolyte layer, and the electrolyte powder layer all include electrolyte A and electrolyte B, and the molar ratio of electrolyte A to electrolyte B is (0.176~1.5):1, for example, it can be 0.176:1, 0.43:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 1:1, 1.2:1, 1.3:1, or 1.5:1, etc.;

[0087] Electrolyte A includes carbonates, and electrolyte B includes oxide electrolytes;

[0088] The carbonate includes, but is not limited to, at least one of lithium carbonate, sodium carbonate, and potassium carbonate.

[0089] The oxide electrolyte includes, but is not limited to, at least one of samarium oxide-doped cerium oxide (SDC), CeO2, ZrO2, and lanthanum strontium gallium magnesium oxide (LSGM).

[0090] Traditional oxygen ion conduction SOFCs (solid oxide fuel cells) conduct oxygen ions. 2- Primarily, in this embodiment, an electrolyte combining oxide electrolyte and carbonate electrolyte is used, which can achieve dual-ion (O2) electrolyte. 2- With CO3 2- Conductivity, that is, imparting O to direct carbon fuel cells 2- With CO3 2- The dual-ion conductivity mechanism endows direct carbon fuel cells with higher ion conductivity. The novel direct carbon fuel cell of this invention can generate a large amount of free CO3 on the cathode side. 2- It can be done in traditional O 2- Based on conductivity, the number of conductive ions is further increased significantly, thereby significantly improving the ionic conductivity and power density of the battery.

[0091] In some embodiments, the carbonates in the first electrolyte layer, the second electrolyte layer, and the electrolyte powder layer all comprise lithium carbonate, sodium carbonate, and potassium carbonate in a molar ratio of 1:1:1.

[0092] In some embodiments, the cathode is a porous cathode, and the anode is a porous anode. The porous nature of the electrodes can improve fuel catalytic efficiency, promote gas adsorption and desorption on the electrode surface, and thus enhance the electrochemical performance of direct carbon fuel cells.

[0093] In some embodiments, the porous cathode includes a cathode material, an electrolyte C, pore-forming graphite, and a binder, wherein the electrolyte C includes at least one of electrolyte A and electrolyte B (see above for specific selection of electrolyte A and electrolyte B); the porous cathode may also include pulp; the cathode material includes at least one of lithium nickel copper zinc, lanthanum strontium cobalt iron, but is not limited thereto.

[0094] In some embodiments, the porous anode includes an anode material, an electrolyte D, pore-forming graphite, and a binder, wherein the electrolyte D includes at least one of electrolyte A and electrolyte B (see above for specific selection of electrolyte A and electrolyte B); the porous anode may also include pulp; the anode material includes at least one of lithium nickel copper zinc and nickel cobalt lithium aluminum, but is not limited thereto.

[0095] In some embodiments, the first silver-plated support mesh comprises a silver-plated metallic mesh or a silver-plated non-metallic mesh. The silver-plated metallic mesh includes, but is not limited to, a silver-plated stainless steel mesh, a silver-plated nickel mesh, or a silver-plated copper mesh; the silver-plated non-metallic mesh includes, but is not limited to, a silver-plated ceramic mesh (or a silver-plated ceramic cloth). In some embodiments, the second silver-plated support mesh comprises a silver-plated metallic mesh or a silver-plated non-metallic mesh. The silver-plated metallic mesh includes, but is not limited to, a silver-plated stainless steel mesh, a silver-plated nickel mesh, or a silver-plated copper mesh; the silver-plated non-metallic mesh includes, but is not limited to, a silver-plated ceramic mesh (or a silver-plated ceramic cloth). Of course, the first and second silver-plated support meshes can also be other silver-plated metallic meshes or silver-plated non-metallic meshes with a melting point not lower than 700 °C.

[0096] This invention also provides a method for preparing the direct carbon fuel cell described above, wherein the preparation method includes the following steps:

[0097] S1. The electrolyte material film, the anode material film, and the second silver-plated support mesh are stacked in sequence, and then pre-pressed at room temperature to form a half-cell blank;

[0098] S2. The half-cell blank is placed at a first preset temperature and kept at that temperature for a first preset time, and then kept at a first preset pressure for a second preset time. After cooling, a half-cell is obtained. Then, the cathode material slurry is coated onto the electrolyte material membrane of the half-cell to form a cathode coating layer. Then, the first silver-plated stainless steel mesh is pressed onto the cathode coating layer. After drying, it is annealed at a second preset temperature for a third preset time (in an air atmosphere, the purpose of which is to create pores). After cooling, a single cell is obtained, comprising a first silver-plated support mesh, a cathode, an electrolyte layer, an anode, and a second silver-plated support mesh stacked in sequence.

[0099] S3. An oxidant is applied to the first silver-plated support mesh side, and fuel is applied to the second silver-plated support mesh side to obtain the direct carbon fuel cell.

[0100] The preparation method provided by this invention is simple. It involves hot-pressing and annealing a stacked electrolyte membrane, anode membrane, and a second silver-plated support mesh. Then, a cathode material slurry is coated onto the electrolyte membrane to form a cathode coating layer. A first silver-plated support mesh is then added, and after annealing, a sandwich single-cell structure is achieved. The resulting direct carbon fuel cell uses a mixture of carbon dioxide and air as an oxidant. Carbon dioxide promotes redox reactions, significantly reducing the activation energy (to 0.47 eV), increasing ionic conductivity (up to 0.275 S / cm), and improving the battery's electrochemical reaction lifetime, open-circuit voltage, current, and power density. Peak power densities can reach 590 mW / cm² at 600 °C and 680 °C, respectively. 2 and 830 mW / cm 2 In addition, the cast electrode can improve the cathode porosity, prevent the cathode from peeling off from the electrolyte layer, and make the silver-plated stainless steel mesh on the cathode side bond more firmly with the cathode.

[0101] In steps S1 and S2, in some embodiments, the electrolyte material membrane includes a first electrolyte material membrane (which includes electrolyte A and electrolyte B, with a molar ratio of electrolyte A to electrolyte B of (0.176~1.5):1, specifically 3:7), electrolyte powder (which includes electrolyte A and electrolyte B, with a molar ratio of electrolyte A to electrolyte B of (0.176~1.5):1, specifically 3:7) and a second electrolyte material membrane (which includes electrolyte A and electrolyte B, with a molar ratio of electrolyte A to electrolyte B of (0.176~1.5):1, specifically 3:7).

[0102] like Figure 2 As shown, the method for preparing the single cell specifically includes the following steps:

[0103] The first electrolyte material membrane 25, electrolyte powder 24, second electrolyte material membrane 23, anode material membrane 22, and second silver-plated support mesh 21 are sequentially stacked and then pre-pressed at room temperature for 1~5 min to form a half-cell blank.

[0104] The half-cell blank is hot-pressed, specifically by holding it at a first preset temperature for a first preset time, and then holding it under a first preset pressure for a second preset time to obtain a hot-pressed half-cell. Then, the cathode material slurry is coated onto the first electrolyte material membrane of the half-cell to form a cathode coating layer. Then, a first silver-plated stainless steel mesh (current collector) is pressed onto the cathode coating layer. After drying, it is annealed at a second preset temperature for a third preset time. After cooling, a single cell is obtained, which includes a first silver-plated support mesh, a cathode, a first electrolyte layer, an electrolyte powder layer, a second electrolyte layer, an anode, and a second silver-plated support mesh stacked in sequence. (The cathode coating layer is transformed into a cathode after the preparation process, the first electrolyte material membrane is transformed into a first electrolyte layer after the preparation process, the electrolyte powder is transformed into an electrolyte powder layer (i.e., an auxiliary electrolyte layer) after the preparation process. The electrolyte powder with a certain fluidity under high pressure can fill the tiny pores accidentally generated in the electrolyte membrane. The second electrolyte material membrane is transformed into a second electrolyte layer after the preparation process, and the anode material membrane is transformed into an anode after the preparation process. The first electrolyte layer, the electrolyte powder layer, and the second electrolyte layer together constitute the electrolyte layer, and the first silver-plated support mesh layer can be embedded in the cathode.)

[0105] In this embodiment, a silver-plated support mesh is used as the skeleton, and after annealing, a sandwich structure is formed with a porous electrode layer and a dense electrolyte layer.

[0106] In some embodiments, the method for preparing the cathode coating layer includes the following steps:

[0107] The cathode material is mixed with an appropriate amount of pore-forming graphite, a binder (such as terpineol, polyethylene glycol, ethyl cellulose, etc.), and electrolyte C. After thorough mixing, the mixture is ball-milled (ethanol may be added). After ball milling, a viscous cathode material slurry is obtained. This cathode material slurry is then coated onto the electrolyte material membrane to form a cathode coating layer.

[0108] Specifically, the method for preparing the cathode material slurry includes the following steps:

[0109] Mix 2-3 g of cathode material, pore-forming graphite (accounting for 10%-40% of the total mass of cathode material, pore-forming graphite and electrolyte C), binder (the binder is composed of terpineol and ethyl cellulose dissolved therein, with ethyl cellulose accounting for 4%-10% of the binder mass, and the ratio of binder to the total mass of cathode material, pore-forming graphite and electrolyte C is (1.5-2):1), and 0.5-1.5 g of electrolyte C, and grind them evenly with an automatic grinder. An appropriate amount of alcohol (accounting for 5%-30% of the total mass) can be added to improve the grinding uniformity. During the grinding process, the ethanol should be completely evaporated to finally form a cathode material slurry.

[0110] In some embodiments, the method for preparing the anode material film includes the following steps:

[0111] The anode material is mixed with an appropriate amount of pore-forming graphite, a binder (such as polyethylene glycol, ethyl cellulose, etc.), and electrolyte D, and then ball-milled with ethanol. After ball milling, an appropriate amount of pulp is added to the prepared slurry and mixed evenly to obtain a viscous slurry. The viscous slurry is then spread evenly on a glass plate and dried at room temperature after the ethanol is evaporated to form an anode material film.

[0112] Specifically, the method for preparing the anode material film includes the following steps:

[0113] 2–3 g of anode material is mixed with pore-forming graphite (10%–40% of the total mass of anode material, pore-forming graphite, binder, and electrolyte D), binder (polyethylene glycol, ethyl cellulose, etc., accounting for 5%–20% of the total mass of anode material, pore-forming graphite, binder, and electrolyte D), and 0.5–1 g of electrolyte D. Then, 20–50 mL of ethanol is added and the mixture is ball-milled. After ball milling, an appropriate amount of pulp is added to the prepared slurry and mixed evenly to obtain a viscous slurry. The viscous slurry is then spread evenly on a glass plate and dried at room temperature after the ethanol is evaporated, forming an anode material film with a thickness of 0.5–1.5 mm. The anode material film can be peeled off from the glass plate and cut into any size, like paper.

[0114] In some embodiments, the method for preparing the first electrolyte material membrane includes the following steps:

[0115] Electrolytes A and B are mixed with appropriate amounts of pore-forming graphite and binders (such as polyethylene glycol, ethyl cellulose, etc.), and then ethanol is added and ball-milled. After ball milling, an appropriate amount of ceramic fiber is added to the prepared slurry and mixed evenly to obtain a viscous slurry. The viscous slurry is then spread evenly on a glass plate, dried at room temperature, and the ethanol is evaporated to form the first electrolyte material membrane.

[0116] Specifically, the preparation method of the first electrolyte material membrane includes the following steps:

[0117] 2 g of electrolyte material (composed of electrolyte A and electrolyte B) is mixed with 0.2–0.5 g of binder (such as polyethylene glycol, ethyl cellulose, etc.), and 15–40 mL of ethanol is added for ball milling. After ball milling, 0.15–0.3 g of ceramic fiber is added to the prepared slurry and mixed evenly to obtain a viscous slurry. The viscous slurry is then spread evenly on a glass plate and dried at room temperature after the ethanol is evaporated, forming a first electrolyte material film with a thickness of 0.2–0.7 mm. After the first electrolyte material film is peeled off from the glass plate, it can be cut into any size, like paper.

[0118] In some embodiments, the method for preparing the second electrolyte material membrane includes the following steps:

[0119] Electrolytes A and B are mixed with appropriate amounts of pore-forming graphite and binders (such as polyethylene glycol, ethyl cellulose, etc.), and then ball-milled with ethanol. After ball milling, an appropriate amount of ceramic fiber is added to the prepared slurry and mixed evenly to obtain a viscous slurry. The viscous slurry is then spread evenly on a glass plate, dried at room temperature, and the ethanol is evaporated to form a second electrolyte material membrane (for specific preparation methods, please refer to the preparation method of the first electrolyte material membrane).

[0120] In step S2, in some embodiments, the pre-compression pressure is 0.1~1 ton / cm (e.g., 0.1, 0.2, 0.5, 0.8, or 1 ton / cm); the first preset temperature is 500~650℃ (e.g., 500, 520, 550, 580, 600, 620, or 650℃); the first preset time is 30~90 min (e.g., 30, 40, 50, 60, 70, 80, or 90 min); the first preset pressure is 5~20 tons (e.g., 5, 6, 7, 8, 9, 10, 11, 12, 15, 18, or 20 tons); the second preset time is 1~10 min (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 min); and the second preset temperature is 500~700℃. ℃ (e.g., 500, 600, 610, 620, 650, 660, 680 or 700 ℃, etc.), and the third preset time is 2~6 h (e.g., 2, 3, 4, 5 or 6 h).

[0121] The cathode material slurry is coated onto the first electrolyte material membrane of the half cell to form a cathode coating layer. Then, a first silver-plated stainless steel mesh is pressed onto the cathode coating layer. After drying (at a temperature of 150 °C for 4 to 8 hours), the subsequent annealing steps are performed.

[0122] Specifically, the temperature can be increased to 600-700℃ at a rate of 0.5-3℃ / min and held for 2-6 hours for annealing and pore formation, and then cooled to room temperature at a rate of 0.5-2℃ / min.

[0123] In step S3, the specific selection of oxidant and fuel is described above and will not be repeated here.

[0124] In some embodiments, the preparation method of a direct carbon fuel cell includes the following steps:

[0125] Preparation of single cells (see above for specific methods);

[0126] First silver wires and second silver wires are led out from the first and second silver-plated support nets of the single cell, respectively. The single cell is sealed and fixed to one end of the ceramic tube (see above for the specific structure of the ceramic tube) using ceramic glue, and the second silver-plated support net with the second silver wires is attached to the ceramic tube.

[0127] Fuel is added to the ceramic tube through the fuel feed pipe;

[0128] An oxidant (a mixture of air and carbon dioxide) is applied to the side of the single cell away from the ceramic tube.

[0129] This invention also provides a direct carbon fuel cell stack, wherein the direct carbon fuel cell stack includes a plurality of direct carbon fuel cells as described above or a plurality of direct carbon fuel cells prepared by the preparation method described above.

[0130] The present invention will be further described below through specific embodiments.

[0131] Unless otherwise specified, all raw materials used in the following examples are commercially available products.

[0132] In the following examples, the samarium oxide content in the SDC used is 20 mol% (i.e., 20 mol% samarium oxide-doped cerium oxide).

[0133] Example 1

[0134] This embodiment provides a continuously fed direct carbon fuel cell supported by a silver-plated stainless steel mesh, wherein, as... Figure 1 As shown, the direct carbon fuel cell includes:

[0135] A single cell 1 includes a first silver-plated stainless steel mesh, a cathode 11, an electrolyte layer 12, an anode 13, and a second silver-plated stainless steel mesh, which are stacked sequentially. The electrolyte layer includes a first electrolyte layer, a second electrolyte layer, and an electrolyte powder layer located between the first electrolyte layer and the second electrolyte layer. The first electrolyte layer, the second electrolyte layer, and the electrolyte powder layer all include an electrolyte material composed of 30 mol% carbonate and 70 mol% SDC. The carbonate is composed of lithium carbonate, sodium carbonate, and potassium carbonate in a molar ratio of 1:1:1 (this electrolyte material is referred to as 30 mol% carbonate-SDC electrolyte material).

[0136] A ceramic tube 2 for containing fuel is disposed on the second silver-plated stainless steel mesh of the single cell 1. The single cell 1 and the ceramic tube 2 are sealed with ceramic adhesive. A through hole is provided at the top of the ceramic tube 2. A sealable fuel inlet pipe 3 (with a first valve 31, a second valve 32 and a third valve 33 spaced apart) and a sealable ash outlet pipe 4 (with a fourth valve 41 and a fifth valve 42 spaced apart) are respectively provided on the side wall of the ceramic tube 2.

[0137] The pressing plate 5 is disposed inside the ceramic tube 2;

[0138] The lifting pipe 6 is connected to the pressure plate 5 at one end and passes through the through hole at the other end, and can move up and down in the through hole. An exhaust hole 61 is provided on the side wall of the lifting pipe 6 near the pressure plate 5. The lifting pipe 6 is used to drive the pressure plate 5 to move up and down and to introduce nitrogen into the ceramic tube 2.

[0139] The first silver wire 111 is drawn out from the first silver-plated stainless steel mesh;

[0140] The second silver wire 131 is drawn from the second silver-plated stainless steel mesh;

[0141] An oxidizing agent is applied to the side of the first silver-plated stainless steel mesh to react with the cathode; the oxidizing agent is composed of air (66% by volume) and carbon dioxide (34% by volume).

[0142] The fuel is added to the ceramic tube through a fuel feed pipe for reaction with the anode; the fuel consists of anthracite and carbonate in a molar ratio of 88:12; the carbonate consists of lithium carbonate, sodium carbonate and potassium carbonate in a molar ratio of 1:1:1.

[0143] The method for preparing the single cell includes the following steps:

[0144] (1) Preparation of cathode material paste: 3 g of LiNi 0.7 Cu 0.1 Zn 0.2 O 2-δ A mixture of 1.14 g of porous graphite (with high conductivity and low polarization resistance), 9 g of binder (composed of terpineol and ethyl cellulose dissolved in terpineol, with ethyl cellulose accounting for 5% of the binder mass), and 1 g of electrolyte material (composed of 30 mol% carbonate and 70 mol% SDC, the carbonate being composed of lithium carbonate, sodium carbonate, and potassium carbonate in a molar ratio of 1:1:1) was ball-milled. After ball milling, a uniform and viscous cathode material slurry was formed.

[0145] (2) Preparation of anode material film: 3 g of LiNi0.7 Cu 0.1 Zn 0.2 O 2-δ 1.14 g of porous graphite, 0.57 g of polyethylene glycol, and 1 g of electrolyte material (composed of 30 mol% carbonate and 70 mol% SDC, where the carbonate is composed of lithium carbonate, sodium carbonate, and potassium carbonate in a molar ratio of 1:1:1) were mixed and ball-milled with 50 mL of ethanol. After ball milling, 6 g of paper pulp was added to the prepared slurry and mixed evenly to obtain a viscous slurry. The viscous slurry was then spread evenly on a glass plate and dried at room temperature after the ethanol was evaporated to form an anode material film with a thickness of 1.2 mm.

[0146] (3) Preparation of the first electrolyte material membrane: 2 g of electrolyte material (composed of 30 mol% carbonate and 70 mol% SDC, wherein the carbonate is composed of lithium carbonate, sodium carbonate and potassium carbonate in a molar ratio of 1:1:1) was mixed with 0.3 g of binder (polyethylene glycol), and 30 mL of ethanol was added for ball milling. After ball milling, 0.2 g of ceramic fiber was added to the prepared slurry and mixed evenly to obtain a viscous slurry. The viscous slurry was then spread evenly on a glass plate, dried at room temperature, and the ethanol was evaporated to form a first electrolyte material membrane with a thickness of 0.5 mm.

[0147] (3) Preparation of the second electrolyte material membrane: The method is the same as that of the first electrolyte material membrane.

[0148] (4) Preparation of single cell: The first electrolyte material membrane (diameter 13 mm), electrolyte material (composed of 30 mol% carbonate and 70 mol% SDC, the carbonate being composed of lithium carbonate, sodium carbonate and potassium carbonate in a molar ratio of 1:1:1) powder (0.2 g), second electrolyte membrane material (diameter 13 mm), anode material membrane (diameter 13 mm) and second silver-plated stainless steel mesh (diameter 13 mm) are stacked in sequence from top to bottom. Then, the membrane is pre-pressed at a pressure of 1 ton / cm for 3 min at room temperature to obtain a half cell blank.

[0149] The half-cell blank is placed on a flat metal plate, and then heated to 550 ℃ in air at a heating rate of 2 ℃ / min and held at that temperature for 60 min. Then it is held under a pressure of 8 tons for 10 min. After cooling, the half-cell is obtained.

[0150] Then, 0.3 g of cathode material slurry was coated onto the first electrolyte material membrane of the half cell to form a cathode coating layer. A first silver-plated stainless steel mesh (13 mm in diameter) was then pressed onto the cathode coating layer. After heating at 150 °C for 6 h, the mixture was dried. Finally, the temperature was increased to 680 °C at a rate of 2 °C / min and annealed at 680 °C in air for 2 h to create pores. The mixture was then cooled to room temperature at a rate of 1 °C / min to obtain the finished single cell.

[0151] Comparative Example 1

[0152] This comparative example provides a direct carbon fuel cell, which differs from Example 1 only in that it uses air as the oxidant.

[0153] Comparative Example 2

[0154] This comparative example provides a direct carbon fuel cell, which differs from Example 1 only in that the single cell is replaced with a half cell consisting only of a cathode and an electrolyte layer, lacking an anode.

[0155] test:

[0156] The X-ray diffraction pattern of 30 mol% carbonate-SDC electrolyte material powder (i.e., 30 mol% carbonate + 70 mol% SDC electrolyte) is shown below. Figure 3 As shown in the figure, the electrolyte material contains the SDC phase ( Figure 3 In the small image, the characteristic peaks of the 30 mol% carbonate-SDC electrolyte material powder correspond to the characteristic peaks of standard card PDF#43-1002, proving that it contains the SDC phase, and only a very small amount of the carbonate phase (as can be seen from the comparison of the characteristic peaks of the 30 mol% carbonate-SDC electrolyte material powder with the characteristic peaks of standard card PDF#21-0954, see...). Figure 3 (as shown in the larger image), while the vast majority of carbonates exist in amorphous form.

[0157] The cross-section of the single cell (excluding the silver-plated stainless steel mesh) in Example 1, the scanning electron microscope image of the 30 mol% carbonate-SDC electrolyte material, and the elemental distribution map of the single cell cross-section measured by energy dispersive spectroscopy are shown below. Figure 4 As shown, the K, Na, and C (carbonate) atoms are concentrated in the electrolyte layer, indicating that carbonate is part of the electrolyte system.

[0158] The electrochemical performance test results of direct carbon fuel cells at different temperatures (600 °C, 650 °C, and 680 °C) using different oxidants (i.e., the direct carbon fuel cells in Example 1 and Comparative Example 1) are shown in the figure below. Figure 5 As shown. Among them, by Figure 5As shown in (a) and (b), when a mixture of air and carbon dioxide is used as the oxidant of the battery (i.e., the direct carbon fuel cell in Example 1), the open-circuit voltage, current, and power density of the battery are significantly improved compared to when air is used alone as the oxidant (i.e., the direct carbon fuel cell in Comparative Example 1). At 680 °C, the highest power density of the battery is increased from 330 mW / cm³. 2 (Using air as the oxidant only) Increased to 830 mW / cm 2 (A mixture of air and carbon dioxide is used as the oxidant).

[0159] Impedance test results of direct carbon fuel cells using different oxidants (air; a mixture of air and carbon dioxide) show (e.g.) Figure 5 As shown in (c) and (d) in the figure, the ohmic impedance of the battery is reduced by more than 2 times when a mixture of air and carbon dioxide is used as the oxidant, compared to when air is used alone. The intercrystalline and intracrystalline impedances are also significantly reduced by about 2 times. In addition, the imaginary part of the battery impedance becomes smaller when a mixture of air and carbon dioxide is used as the oxidant, proving that the adsorption and dissociation of gas on the electrode surface are more rapid, and the charge is transported more quickly on the electrode.

[0160] The conductivity and activation energy results of direct carbon fuel cells at 680 °C using different oxidants (i.e., the direct carbon fuel cells in Example 1 and Comparative Example 1) are shown in the figure below. Figure 6 As shown, the ionic conductivity of the battery increased by more than two times compared to when air was used as the oxidant alone, with the conductivity at 680 °C increasing from 0.09 S / cm to 0.275 S / cm. Furthermore, the activation energy of the battery decreased from 0.61 eV to 0.47 eV after the carbon dioxide reaction was incorporated into the cathode reaction, compared to when air was used as the oxidant alone.

[0161] Thermogravimetric analysis results of anthracite and long-term operation test results of direct carbon fuel cells are as follows: Figure 7 As shown. Among them, as Figure 7As shown in (a), when heated in a nitrogen atmosphere, the anthracite mass loss at 150 °C is approximately 5%, mainly due to the volatilization of adsorbed gases and water vapor. Between 350 and 700 °C, the anthracite mass rapidly decreases to 63.26%, caused by the decomposition and volatilization of hydrocarbons and aromatic organic matter; the remaining portion consists of ash and carbon. When heated in air, the process is essentially the same as in nitrogen heating up to 150 °C, but upon further heating to 350 °C, the anthracite mass content drops to approximately 88%, this mass loss being due to the oxidation and decomposition of smaller molecular weight hydrocarbons. Further heating in air between 400 and 630 °C causes the anthracite mass content to rapidly decrease to 17.55% as larger molecular weight organic matter and carbon are oxidized into carbon dioxide and water. With continued heating, the mass content stabilizes at 17.55%, indicating that the ash mass content of the anthracite is 17.55%, and the carbon content is approximately 45.7%.

[0162] A direct carbon fuel cell (i.e., the direct carbon fuel cell in Example 1) using anthracite and mixed carbonates (the molar ratio of anthracite to carbonates is 88:12, and the carbonates consist of lithium carbonate, sodium carbonate, and potassium carbonate in a molar ratio of 1:1:1) as fuel operates at 0.2 A / cm². 2 The current density was subjected to long-term operation testing at 680 °C, and the results are as follows: Figure 7 As shown in (b), the results indicate that the overall battery response was relatively stable in the first 110 hours. Starting from 110 hours, the pressure of the pressure plate was increased (from 0.5 kg / cm²). 2 Increased to 0.9 kg / cm 2 The battery performance improved, with the voltage increasing by approximately 0.3 V. However, due to the increased pressure, the fuel changed from solid to gaseous CO, which needed to be expelled / extracted from the solid fuel. This process caused significant fluctuations in the battery reaction (corresponding to the 110-130 h range). Between 130 and 150 h, the battery reaction temperature was lowered to 450 °C. During this period, the reaction rate decreased, and the voltage dropped to 0.05 V. After maintaining the temperature at 450 °C for 20 hours, the temperature was raised back to 680 °C. The battery voltage gradually increased, not only returning to the initial reaction state but also showing a slight improvement, demonstrating excellent battery stability.

[0163] Figure 8 The graph shows the electrochemical performance test results of a direct carbon fuel cell (i.e., the direct carbon fuel cell in Comparative Example 2) based on a half-cell consisting only of a cathode and an electrolyte (without an anode) at 680 °C.

[0164] Traditional fuel cells consist of three parts: the cathode, the anode, and the electrolyte. The electrochemical reaction cannot proceed normally if any part is missing. In this invention, because anthracite and carbonates (in the molten state) possess ion and electron conduction capabilities, the fuel portion assumes the ion and electron conduction function of the anode when it is missing, thus acting as the anode. Simultaneously, because the electrolyte layer of the battery contains composite carbonates, it forms a unified ion conduction system with the carbonates in the fuel. Figure 8 As can be seen, the battery open-circuit voltage still reached 0.7 V, and the battery power density reached 56 mW / cm³ at 680 ℃. 2 This is also the key to the direct carbon fuel cell provided by this invention being able to continuously feed and react, unlike conventional direct carbon fuel cells which cannot continuously feed and are easily blocked by the ash produced in the reaction.

[0165] In summary, the direct carbon fuel cell provided by this invention uses a mixture of air and carbon dioxide as the oxidant, resulting in a significantly reduced electrochemical activation energy (down to 0.47 eV) and a significantly improved conductivity (up to 0.275 S / cm); it achieves a conductivity of 830 mW / cm at 680℃. 2 The peak power density is achieved, and stable operation is possible under intermediate temperature conditions. A 30 mol% carbonate-SDC electrolyte material imparts O2 to direct carbon fuel cells. 2- With CO3 2- Dual-ion conductivity. The electrolyte material has a single, high-purity crystal phase and uniform grain microstructure. The electrode material is porous, improving fuel reaction efficiency, promoting gas adsorption and desorption on the electrode surface, and enhancing battery density and ion transport capabilities. The direct carbon fuel cell provided by this invention can achieve continuous fuel supply and continuous ash removal, effectively solving the problems of ash accumulation and fuel interruption (limited fuel loading capacity and unsustainable fuel supply). The combination of anthracite and carbonate can solve the problem of unsustainable reaction caused by anode ash accumulation. The addition of a pressure plate improves the fuel supply and reaction sustainability of the battery, solving the problem of low electrochemical reaction rate caused by loose fuel-anode contact in previous types of batteries, further improving the power density compared to previous direct carbon fuel cells. The direct carbon fuel cell provided by this invention can operate continuously for 270 hours until the fuel is exhausted after several replenishments, and discharges waste, improving the short operating life of traditional direct carbon fuel cells.

[0166] It should be understood that the application of the present invention is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A direct carbon fuel cell, characterized in that, The direct carbon fuel cell includes a single cell, an oxidant, and fuel. The single cell includes a first silver-plated support mesh, a cathode, an electrolyte layer, an anode, and a second silver-plated support mesh, which are stacked in sequence. The oxidant is applied to the side of the first silver-plated support mesh to react with the cathode; The fuel is applied to the second silver-plated support mesh side for reacting with the anode; The direct carbon fuel cell also includes: A ceramic tube for containing fuel is disposed on the single cell and attached to the second silver-plated support mesh. The top of the ceramic tube is provided with a through hole, and the side wall of the ceramic tube is provided with a sealable fuel inlet pipe and a sealable ash outlet pipe, respectively. A pressure plate is disposed inside the ceramic tube; The lifting pipe has one end connected to the pressure plate and the other end passing through the through hole and can move up and down in the through hole. An exhaust hole is provided on the side wall of the lifting pipe near the pressure plate. The lifting pipe is used to drive the pressure plate to move up and down and to introduce nitrogen into the ceramic tube. The first silver wire is drawn out from the first silver-plated support mesh; The second silver wire is drawn out from the second silver-plated support mesh; The oxidant, by volume percentage, consists of the following components: Air 66% and carbon dioxide 34%.

2. The direct carbon fuel cell according to claim 1, characterized in that, The fuel includes a first fuel and a second fuel. The first fuel includes at least one of anthracite, bituminous coal, biochar, activated carbon, and graphite. The second fuel includes carbonates, which include at least one of lithium carbonate, sodium carbonate, and potassium carbonate.

3. The direct carbon fuel cell according to claim 2, characterized in that, The fuel comprises anthracite and carbonates, wherein the molar ratio of the anthracite to the carbonates is (80~95):(5~20); the carbonates comprise lithium carbonate, sodium carbonate and potassium carbonate in a molar ratio of 1:1:

1.

4. The direct carbon fuel cell according to claim 1, characterized in that, The electrolyte layer includes a first electrolyte layer and a second electrolyte layer, and an electrolyte powder layer located between the first electrolyte layer and the second electrolyte layer; The first electrolyte layer, the second electrolyte layer, and the electrolyte powder layer all include electrolyte A and electrolyte B, and the molar ratio of electrolyte A to electrolyte B is (0.176~1.5):1; Electrolyte A includes carbonates, and electrolyte B includes oxide electrolytes; The oxide electrolyte includes at least one of samarium oxide-doped cerium oxide, CeO2, ZrO2, and lanthanum, strontium, gallium, and magnesium oxide.

5. The direct carbon fuel cell according to claim 4, characterized in that, The cathode is a porous cathode, and the anode is a porous anode; The porous cathode includes a cathode material, an electrolyte C, pore-forming graphite, and a binder, wherein the electrolyte C includes at least one of electrolyte A and electrolyte B; The porous anode includes an anode material, an electrolyte D, pore-forming graphite, and a binder, wherein the electrolyte D includes at least one of electrolyte A and electrolyte B; The first silver-plated support mesh includes a silver-plated metal mesh or a silver-plated non-metal mesh. The silver-plated metal mesh includes one of a silver-plated stainless steel mesh, a silver-plated nickel mesh, or a silver-plated copper mesh. The silver-plated non-metal mesh includes a silver-plated ceramic mesh. The second silver-plated support mesh includes a silver-plated metal mesh or a silver-plated non-metal mesh. The silver-plated metal mesh includes one of a silver-plated stainless steel mesh, a silver-plated nickel mesh, or a silver-plated copper mesh, and the silver-plated non-metal mesh includes a silver-plated ceramic mesh.

6. A method for preparing a direct carbon fuel cell according to claim 1, characterized in that, The preparation method includes the following steps: The electrolyte material membrane, the anode material membrane, and the second silver-plated support mesh are stacked sequentially and then pre-pressed at room temperature to form a half-cell blank. The half-cell blank is placed at a first preset temperature and kept at that temperature for a first preset time, and then kept at a first preset pressure for a second preset time. After cooling, a half-cell is obtained. The cathode material slurry is coated onto the electrolyte material membrane in the half cell to form a cathode coating layer. Then, the first silver-plated support mesh is pressed onto the cathode coating layer. After drying, it is annealed at a second preset temperature for a third preset time. After cooling, a single cell is obtained, which includes the first silver-plated support mesh, cathode, electrolyte layer, anode and second silver-plated support mesh stacked in sequence. An oxidant is applied to the first silver-plated support mesh side, and fuel is applied to the second silver-plated support mesh side to obtain the direct carbon fuel cell.

7. The preparation method according to claim 6, characterized in that, The pre-compression pressure is 0.1~1 ton / cm²; the first preset temperature is 500~650 ℃, the first preset time is 30~90 min, the first preset pressure is 5~20 tons, the second preset time is 1~10 min; the second preset temperature is 500~700 ℃, and the third preset time is 2~6 h.

8. A direct carbon fuel cell stack, characterized in that, The direct carbon fuel cell stack includes a number of direct carbon fuel cells as described in any one of claims 1-5 or a number of direct carbon fuel cells prepared by the preparation method described in any one of claims 6-7.

Images