Medium temperature carbon fuel cell

Abstract

The invention provides a medium-temperature carbon fuel cell, the carbon fuel cell comprises an ion conducting layer, and a negative electrode and a positive electrode arranged at two sides of the ion conducting layer, the negative electrode comprises carbon particles, a first electrolyte and a catalyst; the first electrolyte is a molten salt electrolyte; the catalyst comprises one of metal nickel, nickel-chromium alloy, nickel-aluminum alloy and nickel-chromium-aluminum alloy; the ion conducting layer comprises an electrolyte membrane made of a second electrolyte, and the second electrolyte is a solid electrolyte or a composite electrolyte formed by mixing the solid electrolyte and a molten salt electrolyte; the positive electrode comprises a porous catalyst material and a third electrolyte, and the third electrolyte is a solid electrolyte or a composite electrolyte formed by mixing the solid electrolyte and a molten salt electrolyte.

Description

Technical Field

[0001] This invention belongs to the field of new energy, and in particular relates to a medium-temperature carbon fuel cell. Background Technology

[0002] Currently, the most reported carbon fuel cell is the MCFC (Multi-Chemical Fuel Cell) operating at 800℃, with a power generation efficiency of only 26%, as most of the carbon is emitted as carbon monoxide or used for other purposes. There are also molten alkaline fuel cells, where carbon is placed in molten alkaline, which consumes the alkaline, increasing internal resistance and making it difficult to achieve sustainable and stable power generation. Existing carbon fuel cells operate at around 800℃, but at these high temperatures, carbon dioxide reacts with the carbon fuel at the negative electrode to produce carbon monoxide, resulting in low efficiency. Furthermore, the high temperature of 800℃ places significantly higher demands on structural materials and sealing, greatly increasing manufacturing difficulty and cost. Summary of the Invention

[0003] The present invention provides a medium-temperature carbon fuel cell to achieve at least one of the following objectives: to solve the above-mentioned technical problems in the prior art, improve the fuel utilization rate of carbon fuel cells, and improve power generation efficiency.

[0004] To achieve the above and other related objectives, the present invention provides the following technical solution:

[0005] This invention provides a medium-temperature carbon fuel cell, comprising an ion-conducting layer, and a negative electrode and a positive electrode disposed on both sides of the ion-conducting layer. The medium-temperature carbon fuel cell operates at a medium-low temperature of 400-700°C.

[0006] The negative electrode comprises carbon particles, a first electrolyte, and a catalyst, wherein the catalyst comprises one of metallic nickel, nickel-chromium alloy, nickel-aluminum alloy, and nickel-chromium-aluminum alloy; the first electrolyte is a molten salt electrolyte.

[0007] The ion-conducting layer includes an electrolyte membrane made of a second electrolyte, wherein the second electrolyte is a solid electrolyte or a composite electrolyte consisting of a solid electrolyte and a molten salt electrolyte.

[0008] The positive electrode includes a porous catalyst material and a third electrolyte, wherein the third electrolyte is a solid electrolyte or a composite electrolyte consisting of a solid electrolyte and a molten salt electrolyte.

[0009] Furthermore, in the positive electrode, the mass ratio of porous catalyst material is 40-60 wt%.

[0010] Furthermore, the intermediate-temperature carbon fuel cell also includes a metal support layer, and from top to bottom, a mixture of carbon particles and molten salt electrolyte, a catalyst, the metal support layer, an ion-conducting layer, and a positive electrode are sequentially arranged. The mixture includes a first part and a second part, which are sequentially arranged from top to bottom. The first part includes the carbon particles, and the second part includes a mixture of carbon particles and molten salt electrolyte.

[0011] Furthermore, the solid electrolyte is selected from cerium dioxide-doped materials or PN-type composite materials;

[0012] The cerium dioxide doped material includes at least one of lanthanum oxide, samarium oxide, gadolinium oxide, magnesium oxide, calcium oxide, and strontium oxide, with a doping ratio of 5% to 20% and a molar ratio.

[0013] The PN-type composite material is a mixture of P-type semiconductor oxide and N-type semiconductor oxide, with a mass ratio of 1:0.1-10.

[0014] Furthermore, the P-type semiconductor oxide includes at least one of nickel oxide, ferrous oxide, cuprous oxide, tin oxide, manganese oxide, cerium trioxide, cobalt oxide, and cobalt tetroxide;

[0015] Furthermore, the N-type semiconductor oxide includes at least one of nickel oxide, iron oxide, cobalt oxide, copper oxide, manganese dioxide, tin dioxide, titanium dioxide, silicon dioxide, cerium dioxide, zinc oxide, gallium oxide, and aluminum oxide.

[0016] Furthermore, the PN-type composite material comprises a mixture of nickel oxide and at least one of aluminum oxide, zinc oxide, tin dioxide, silicon dioxide, titanium dioxide, and cerium dioxide;

[0017] Furthermore, the PN-type composite material comprises a mixture of cuprous oxide and at least one of aluminum oxide, zinc oxide, tin dioxide, silicon dioxide, titanium dioxide, and cerium dioxide;

[0018] Furthermore, the PN-type composite material comprises a mixture of manganese oxide and at least one of aluminum oxide, zinc oxide, tin dioxide, silicon dioxide, titanium dioxide, and cerium dioxide;

[0019] Furthermore, the PN-type composite material comprises a mixture of ferrous oxide and at least one of aluminum oxide, zinc oxide, tin dioxide, silicon dioxide, titanium dioxide, and cerium dioxide;

[0020] Furthermore, the PN-type composite material comprises a mixture of cobalt oxide and at least one of aluminum oxide, zinc oxide, tin dioxide, silicon dioxide, titanium dioxide, and cerium dioxide;

[0021] Furthermore, the PN-type composite material comprises a mixture of at least one of tin oxide and aluminum oxide, zinc oxide, tin dioxide, silicon dioxide, titanium dioxide, and cerium dioxide;

[0022] Furthermore, the PN-type composite material comprises a mixture of at least one of cerium trioxide and aluminum trioxide, zinc oxide, tin dioxide, silicon dioxide, titanium dioxide, and cerium dioxide;

[0023] Furthermore, the PN-type composite material includes a mixture of nickel oxide and zinc oxide, a mixture of cuprous oxide and aluminum oxide, or a mixture of cuprous oxide and zinc oxide.

[0024] Furthermore, the PN-type composite material comprises 30wt% nickel oxide + 70wt% zinc oxide, 58.5wt% cuprous oxide + 41.5wt% aluminum oxide, or 64wt% cuprous oxide + 36wt% zinc oxide.

[0025] Furthermore, the cerium dioxide doped material includes Sm 0.2 Ce 0.8 O2, Gd 0.2 Ce 0.8 O2, La 0.2 Ce 0.8 O2, Ca 0.2 Ce 0.8 O2, La 0.19 Sr 0.01 Ce 0.8 O2, La 0.05 Ca 0.15 Ce 0.8 O2, Sm 0.05 Ca 0.15 Ce 0.8 O2 or Gd 0.05 Ca 0.15 Ce 0.8 O2.

[0026] Furthermore, the molten salt electrolyte includes chlorides, sulfates, or carbonates.

[0027] The chloride molten salt comprises a first type of chloride, or a complex of a first type of chloride and a second type of chloride; when the chloride molten salt comprises a first type of chloride, the first type of chloride is calcium chloride, or magnesium chloride, or lithium chloride; when the chloride molten salt comprises the complex of the first type of chloride and the second type of chloride, the first type of chloride is one or two of calcium chloride, magnesium chloride, and lithium chloride, and the second type of chloride is at least one of sodium chloride and potassium chloride;

[0028] The sulfate includes lithium sulfate, or a mixed molten salt of sodium sulfate and lithium sulfate;

[0029] The carbonate includes at least one of sodium carbonate, potassium carbonate, and lithium carbonate.

[0030] Furthermore, the composite electrolyte comprises a mixture of the cerium dioxide doped material and 10-30 wt% of the molten salt electrolyte, wherein the molten salt electrolyte comprises a mixture of at least one of sodium chloride, potassium chloride, calcium chloride, lithium sulfate, sodium sulfate, and sodium lithium sulfate.

[0031] The molten salt electrolyte comprises a mixture of at least one of sodium carbonate, potassium carbonate, lithium carbonate, sodium chloride, potassium chloride, calcium chloride, lithium sulfate, sodium sulfate, and sodium lithium sulfate.

[0032] Furthermore, the composite electrolyte includes Sm 0.2 Ce 0.8 A mixture of O2 and sodium carbonate, Gd 0.2 Ce 0.8 A mixture of O2 and sodium chloride, La 0.2 Ce 0.8 A mixture of O2 and sodium sulfate, Ca 0.2 Ce 0.8 A mixture of O2 and sodium chloride, La 0.19 Sr 0.01 Ce 0.8 A mixture of O2 and sodium carbonate, La 0.19 Sr 0.01 Ce 0.8 A mixture of O2 and sodium chloride, La 0.05 Ca 0.15 Ce 0.8 A mixture of O2 and sodium carbonate, La 0.05 Ca 0.15 Ce 0.8 A mixture of O2 and sodium chloride, Sm 0.05 Ca 0.15 Ce 0.8 A mixture of O2 and sodium chloride, Sm 0.05 Ca 0.15 Ce 0.8A mixture of O2 and sodium carbonate, La 0.19 Sr 0.01 Ce 0.8 A mixture of O2, sodium chloride, and calcium chloride, or Gd 0.05 Ca 0.15 Ce 0.8 A mixture of O2 and sodium chloride.

[0033] Furthermore, the composite electrolyte includes Sm 0.2 Ce 0.8 O2 + 20wt% sodium carbonate, Gd 0.2 Ce 0.8 O2 + 20wt% sodium chloride, La 0.2 Ce 0.8 O2 + 20wt% sodium sulfate, Ca 0.2 Ce 0.8 O2 + 20wt% sodium chloride, La 0.19 Sr 0.01 Ce 0.8 O2 + 20wt% sodium carbonate, La 0.19 Sr 0.01 Ce 0.8 O2 + 20wt% sodium chloride, La 0.05 Ca 0.15 Ce 0.8 O2 + 20wt% sodium carbonate, La 0.05 Ca 0.15 Ce 0.8 O2 + 20wt% sodium chloride, Sm 0.05 Ca 0.15 Ce 0.8 O2 + 20wt% sodium chloride, Sm 0.05 Ca 0.15 Ce 0.8 O2 + 20wt% sodium carbonate, La 0.19 Sr 0.01 Ce 0.8 O2 + 20wt% (sodium chloride + calcium chloride), or Gd 0.05 Ca 0.15 Ce 0.8 O2 + 20wt% sodium chloride.

[0034] Furthermore, the composite electrolyte comprises a mixture of the PN-type composite material and 10-30 wt% of the molten salt electrolyte, wherein the molten salt electrolyte comprises at least one of sodium carbonate, potassium carbonate, lithium carbonate, sodium chloride, potassium chloride, calcium chloride, lithium sulfate, sodium sulfate, and sodium lithium sulfate.

[0035] Optionally, the composite electrolyte comprises a mixture of cuprous oxide, zinc oxide, and sodium chloride. Preferably, the composite electrolyte comprises cuprous oxide, zinc oxide, and sodium chloride, wherein the mass of sodium chloride is 20% of the total mass of the composite electrolyte, and the mass ratio of cuprous oxide to zinc oxide is 64:36.

[0036] Optionally, the composite electrolyte comprises a mixture of nickel oxide, zinc oxide, and sodium carbonate. Preferably, the composite electrolyte comprises nickel oxide, zinc oxide, and sodium carbonate; more preferably, the first electrolyte comprises nickel oxide, zinc oxide, and sodium carbonate, wherein the mass of sodium carbonate is 20% of the total mass of the composite electrolyte, and the mass ratio of nickel oxide to zinc oxide is 30:70.

[0037] Optionally, the composite electrolyte comprises a mixture of cuprous oxide, aluminum oxide, and potassium carbonate. Preferably, the composite electrolyte comprises cuprous oxide, aluminum oxide, and potassium carbonate. More preferably, the first electrolyte comprises cuprous oxide, aluminum oxide, and potassium carbonate, wherein the mass of potassium carbonate is 20% of the total mass of the composite electrolyte, and the mass ratio of cuprous oxide to aluminum oxide is 58.5:41.5.

[0038] Optionally, the composite electrolyte comprises a mixture of cuprous oxide, zinc oxide, and sodium chloride. Preferably, the composite electrolyte comprises cuprous oxide, zinc oxide, and sodium chloride. More preferably, the first electrolyte comprises cuprous oxide, zinc oxide, and sodium chloride, wherein the mass of sodium chloride is 20% of the total mass of the composite electrolyte, and the mass ratio of cuprous oxide to zinc oxide is 64:36.

[0039] Optionally, the composite electrolyte comprises a mixture of nickel oxide, zinc oxide, sodium chloride, and calcium chloride.

[0040] Furthermore, the molten salt electrolyte and the composite electrolyte formed by mixing the solid electrolyte with the molten salt electrolyte have one or more of the following characteristics:

[0041] (1) The melting point of molten salt electrolyte is between 400-700℃; the working range of composite electrolyte is between 400-700℃.

[0042] (2) The total ionic conductivity is greater than 0.05 S / cm.

[0043] Furthermore, the porous catalyst material is titanium suboxide or manganese dioxide; or LaMO3, La （1-x） Ca x MO3, La （1-x） Sr x MO3, La 0.1 Sr （0.9-x） Ca xAt least one of MO3, wherein M = at least one of Mn, Fe, Ni, Co, Cu, and x is 0.1 to 0.9; or titanium suboxide or manganese dioxide supported on porous carbon-based material.

[0044] Furthermore, the porous catalyst material is LaMnO3, LaCoO3, LaNiO3, or LaMn. 0.5 Cu 0.5 O3, LaMn 0.5 Ni 0.5 O3, La 0.5 Ca 0.5 MnO3, La 0.5 Ca 0.5 CoO3, La 0.5 Ca 0.5 FeO3, La 0.5 Ca 0.5 NiO3, La 0.1 Sr 0.4 Ca 0.5 At least one of MnO3.

[0045] The beneficial effects of this invention are as follows:

[0046] 1. The carbon fuel cell provided by this invention uses solid carbon as fuel and a medium-low temperature electrolyte, which can reduce the operating temperature of the fuel cell to the range of 400-700℃, thereby improving the power generation efficiency of carbon fuel and reducing ineffective heat loss. It can achieve a power generation efficiency of 60-80%, which is higher than that of hydrogen fuel cells. At the same time, the battery of this invention can operate at a medium-low temperature of 400-700℃ for extended periods, greatly reducing the requirements for the high-temperature resistance of materials and lowering costs.

[0047] 2. In the direct carbon fuel cell provided by this invention, the carbon particles at the negative electrode are continuously consumed during power generation, while the carbon particles above are continuously replenished, ensuring that the carbon particles in the electrolyte are not completely consumed, so that the battery can generate electricity continuously and stably.

[0048] 3. Carbon fuel cells use solid powder C directly as a conductor, and there is no degradation in power generation performance due to oxidation residue. The voltage and current are stable, the internal resistance is low, the system power generation efficiency is higher than that of hydrogen fuel cells, and the reaction speed is faster than that of other gas fuel cells.

[0049] 4. The solid-state electrolyte system provided by this invention constructs a semiconductor heterojunction structure, which, combined with increased internal interfaces, enriches the channels for interfacial ion conduction, thereby improving conductivity. The electrolyte achieves conductivity exceeding that of traditional solid electrolyte YSZ in the mid-temperature range, reaching over 100 mS / cm. This, in turn, improves current density and power density, meeting the standards for automotive-grade power batteries. Simultaneously, it lowers the battery's operating temperature to the mid-to-low temperature range of 400-700℃ and solves problems such as gas permeation, low conductivity, low power density, high internal resistance, complex fuel handling, high gaseous fuel transportation costs, high refueling costs, and poor safety.

[0050] 5. The molten salt electrolyte used in this invention controls the melting point to 400-700℃ through a combination of binary or multi-element salts, thereby reducing the battery operating temperature. Simultaneously, by incorporating cerium dioxide-doped semiconductor materials or PN-type semiconductor materials into the molten salt electrolyte, this invention breaks through the barrier of traditional solid-state electrolytes, which can only generate ionic conductivity through oxygen vacancies. Through oxygen vacancies and abundant interfaces, and via the coupling mechanism of ionic and electronic charges within the two semiconductors, this invention achieves a significant increase in ionic conductivity, ultimately obtaining a higher conductivity than the YSZ electrolyte of traditional SOFCs at 400-700℃. Attached Figure Description

[0051] Figure 1 This is a schematic diagram of the structure of a carbon fuel cell according to an embodiment of the present invention. Detailed Implementation

[0052] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification.

[0053] It should be understood that the structures, proportions, sizes, etc., illustrated in the accompanying drawings are merely for illustrative purposes to aid those skilled in the art and to facilitate understanding and reading. They are not intended to limit the implementation conditions of the invention and therefore have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to the size, without affecting the effectiveness and objectives of the invention, should still fall within the scope of the technical content disclosed in the invention. Furthermore, the terms "first," "second," and "third" in this specification are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0054] The embodiments of the present invention will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0055] One embodiment of the present invention provides a medium-temperature carbon fuel cell, referring to... Figure 1 The carbon fuel cell 10 includes an ion-conducting layer 1, and a negative electrode 2 and a positive electrode 3 disposed on both sides of the ion-conducting layer 1. The carbon fuel cell 10 operates at a medium-low temperature of 400-700℃. The negative electrode 2 includes carbon particles, a first electrolyte (molten salt electrolyte), and a catalyst 21. The catalyst 21 includes one of metallic nickel, nickel-chromium alloy, nickel-aluminum alloy, and nickel-chromium-aluminum alloy.

[0056] The ion-conducting layer 1 is an electrolyte membrane made of a second electrolyte, which includes a solid electrolyte or a composite electrolyte consisting of a mixture of a solid electrolyte and a molten salt electrolyte.

[0057] It should be noted that the electrolyte membrane of the ion-conducting layer is an impermeable solid membrane composed of an all-solid electrolyte or a mixture of solid electrolyte and molten salt electrolyte, possessing both ionic and oxygen ion conductivity, with a thickness of 0.01-1.0 mm. The electrolyte membrane prevents oxygen from the positive electrode side from entering the negative electrode through pores and undergoing oxidation, which would lead to ineffective reactions, reduced power generation efficiency, and waste of carbon fuel. As a physical barrier, the electrolyte membrane acts as a spatial barrier to prevent gas cross-contamination, while simultaneously providing a relatively fast channel for ions, especially oxygen ions, ensuring the smooth progress of the oxidation reaction at the negative electrode.

[0058] The positive electrode 3 includes a porous catalyst material and a third electrolyte, which is a solid electrolyte or a composite electrolyte consisting of a solid electrolyte and a molten salt electrolyte.

[0059] In one embodiment of the present invention, the mass ratio of porous catalyst material in the positive electrode is 40-60 wt%, and typical but non-limiting mass ratios in the present invention are 40 wt%, 45 wt%, 50 wt%, 55 wt%, or 60 wt%.

[0060] The positive electrode 3 also contains a conductive agent, which is a conductive material, such as a metal, metal oxide, or carbon-based conductive material with electronic conductivity. This invention does not impose any particular limitation on the conductive agent.

[0061] In this invention, the molten salt electrolyte, solid electrolyte membrane, and composite electrolyte have a certain oxygen ion conductivity or a certain ionic conductivity of both oxygen ions and hydrogen ions.

[0062] In this invention, the carbon particles can be in powder or block form.

[0063] In this invention, the carbon particles can be selected from at least one of electrolytically regenerated carbon materials, thermochemically regenerated carbon materials, coal, straw carbon, petroleum coke, graphite, carbon black, amorphous carbon, carbon nanotubes, carbon fibers, and spherical carbon. Different types of carbon fuels can be used for power generation in this invention.

[0064] In this invention, the reducing agent material at the negative electrode undergoes an oxidation reaction at 400-700°C. For example, carbon particles generate carbon dioxide.

[0065] In one embodiment of the present invention, reference is made to... Figure 1 The carbon fuel cell 10 also includes a metal support layer 4, with the negative electrode on top and the positive electrode on the bottom. From top to bottom, that is, from the negative electrode 2 to the positive electrode 3, a mixture of carbon particles and molten salt electrolyte, a catalyst 21, the metal support layer 4, an ion-conducting layer 1, and the positive electrode 3 are sequentially arranged. The catalyst 21 and the metal support layer 4 are tightly bonded, and ion charge transfer occurs through the channels of the metal support layer 4 and the ion-conducting layer. The reinforcement of the metal support layer improves the impact resistance of the solid-state battery and reduces the fragility and cracking caused by uneven local heating due to thermal shock.

[0066] The metal support layer has the following functions: 1. The metal support layer has channels or voids (porosity between 40-95%), which can provide rigidity and toughness to support the ion-conducting layer, specifically, mechanically supporting the electrolyte membrane. 2. Applying electricity to the metal support layer can raise the temperature of the carbon fuel cell. 3. When the carbon fuel cell is operating, if the internal temperature of the carbon fuel cell becomes overheated, the metal support layer can dissipate heat to the outside. 4. The channels or voids (porosity between 40-95%) of the metal support layer can provide ion channels for the carbon fuel cell. The material of the metal support layer in this invention is not particularly limited.

[0067] In one embodiment of the present invention, reference is made to... Figure 1 The mixture of carbon particles and molten salt electrolyte in the negative electrode includes a first part 22 and a second part 23. From top to bottom, and in the direction from the negative electrode 2 to the positive electrode 3, the first part 22 includes carbon particles, and the second part 23 includes a mixture of carbon particles and molten salt electrolyte. Alternatively, the height of the molten salt electrolyte can be understood as being less than the height of the carbon particles, with the negative electrode facing upwards and the positive electrode facing downwards. When the carbon fuel cell of this application is used, the carbon particles in the molten salt electrolyte at the negative electrode are converted into carbon dioxide. Due to gravity, the upper carbon particles fall downwards, ensuring that carbon particles are always present in the molten salt electrolyte so that the battery can operate normally and generate electricity sustainably and stably.

[0068] Preparation of the negative electrode: Heat the molten salt electrolyte to melt it, pour the melted molten salt electrolyte into the carbon particles so that some of the carbon particles are immersed in the molten salt electrolyte, with the lower part of the carbon particle pile immersed in the melted molten salt electrolyte and the upper part not immersed in the molten salt electrolyte; or mix some carbon particles with the melted molten salt electrolyte evenly, and then pile another part of the carbon particles on top; or mix some carbon particles with the molten salt electrolyte powder evenly, sinter it, and then pile another part of the carbon particles on top.

[0069] In one embodiment of the present invention, reference is made to... Figure 1 The carbon fuel cell also includes a negative electrode current collector 6 and a positive electrode current collector 7. The negative electrode 2 includes an inner side close to the ion-conducting layer 1 and an outer side away from the ion-conducting layer 1. The positive electrode 3 includes an inner side close to the ion-conducting layer 1 and an outer side away from the ion-conducting layer 1. The negative electrode current collector 6 is disposed on the outer side of the negative electrode 2, and the negative electrode 2 outputs electrons outward through the negative electrode current collector 6. The positive electrode current collector 7 is disposed on the outer side of the positive electrode 3, and the positive electrode 3 inputs electrons inward through the positive electrode current collector 7.

[0070] In one embodiment of the present invention, the negative current collector layer or the positive current collector layer is selected from metal or graphite, with stainless steel or copper being preferred metals.

[0071] In one embodiment of the present invention, reference is made to... Figure 1 The carbon fuel cell 10 also includes a conductive element 5, which is disposed inside the negative electrode. One end of the conductive element 5 is in contact with the negative electrode current collector 6 and the other end is in contact with the metal support layer 4 for electrical connection.

[0072] In the carbon fuel cell of this application, the negative electrode faces upward and the positive electrode faces downward. The carbon particles at the negative electrode, located in the molten salt electrolyte, are converted into carbon dioxide. Due to gravity, the upper carbon particles fall downward, gradually decreasing the total height of the carbon particles and creating gaps between the carbon particles and the negative electrode current collector. When there are no gaps between the carbon particles and the negative electrode current collector, electrons from the carbon particles can transfer to the negative electrode current collector. When there are gaps between the carbon particles and the negative electrode current collector, electrons from the carbon particles can transfer from the conductive element to the negative electrode current collector; electrons can also transfer from the metal support layer to the conductive element, and then from the conductive element to the negative electrode current collector. This ensures the transfer of electrons in the fuel electric field.

[0073] In this embodiment, the positive electrode current collector 7 has a gas channel 8 for air flow. The positive electrode current collector 7 can be a porous foam metal. Through the pores on the positive electrode current collector, the pores of the porous catalyst material of the positive electrode can be fluidly connected with the air to ensure that oxygen in the air enters the porous material. In this invention, the battery uses oxygen in the air as an oxidant. The oxygen in the air enters the battery through the porous material of the positive electrode. The porous catalyst material absorbs oxygen from the air and combines with electrons to generate oxygen ions. The oxygen ions move towards the negative electrode.

[0074] In this invention, the positive electrode current collector has a gas flow channel on one side, facing the positive electrode, and oxygen or air is introduced to exchange gases with the positive electrode. The positive electrode gains electrons and converts oxygen into oxygen ions, which then move towards the negative electrode. For example, the positive electrode current collector can be a foamed metal layer, and oxygen or air enters the positive electrode through the channels on the positive electrode current collector.

[0075] In this invention, the positive electrode and the ion-conducting layer are tightly bonded together, and the ion-conducting layer provides a channel and carrier for the transfer of oxygen and oxygen ions. The ion-conducting layer can be the aforementioned solid electrolyte or a composite electrolyte resulting from a mixture of the aforementioned solid electrolyte and the aforementioned molten salt electrolyte, and can be formed into a film or sheet.

[0076] In one embodiment of the present invention, the third electrolyte of the positive electrode is a solid electrolyte. The positive electrode comprises a porous catalyst material, a solid electrolyte, a conductive agent solid powder, etc., which are uniformly mixed, and then a pore-forming agent, ammonium bicarbonate, is added and mixed evenly. After heating, the pore-forming agent decomposes into gas to form abundant pores, forming a porous material. Then, the material is sintered by further heating, cooled, and pressed into a sheet to obtain the positive electrode. That is, the positive electrode has enough pores for air to enter and exit.

[0077] In one embodiment of the present invention, when the third electrolyte of the positive electrode is a composite electrolyte, the molten salt electrolyte is heated and melted, and the porous catalyst material, conductive agent solid powder, solid electrolyte, etc. are immersed in the molten salt electrolyte, stirred evenly, cooled, ground into powder, and then the pore-forming agent ammonium bicarbonate is added. After mixing evenly, the mixture is pressed into a sheet, heated and the pore-forming agent decomposes to form a porous material, and then the temperature is further increased for sintering, cooled, and pressed into a sheet to obtain the positive electrode.

[0078] In one embodiment of the present invention, the solid electrolyte of the second electrolyte of the ion-conducting layer or the third electrolyte of the positive electrode, as well as the solid electrolyte in the composite electrolyte, are all selected from cerium dioxide doped materials or PN-type composite materials; wherein, the cerium dioxide doped material includes at least one of lanthanum oxide, samarium oxide, gadolinium oxide, magnesium oxide, calcium oxide, and strontium oxide, with a doping ratio of 5% to 20%, and a molar ratio. Typical but non-limiting doping ratios in the present invention are 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, or 20%.

[0079] The PN-type composite material is a mixture of P-type and N-type semiconductor oxides, with a mass ratio of P-type to N-type semiconductor oxides of 1:0.1-10. Typical but non-limiting mass ratios of P-type and N-type semiconductor oxides in this invention are 1:0.1, 1:0.5, 1:0.56, 1:0.71, 1:1.0, 1:1.2, 1:1.5, 1:1.8, 1:2.0, and 1:2.3. 3, 1:2.5, 1:2.53, 1:2.7, 1:3.0, 1:3.2, 1:3.6, 1:4.0, 1:4.5, 1:5.0, 1:5.3, 1:5.5, 1:5.8, 1:6.0, 1:6.2, 1:6.5, 1:7.0, 1:7.2, 1:7.6, 1:8.0, 1:8.5, 1:9.0, 1:9.1, 1:9.2, 1:9.5, 1:9.8 or 1:10.

[0080] P-type semiconductor oxides include at least one of nickel oxide, ferrous oxide, cuprous oxide, tin oxide, manganese oxide, cerium oxide, cobalt oxide, and cobalt tetroxide; N-type semiconductor oxides include at least one of nickel oxide, ferric oxide, cobalt oxide, copper oxide, manganese dioxide, tin dioxide, titanium dioxide, silicon dioxide, cerium dioxide, zinc oxide, gallium oxide, and aluminum oxide.

[0081] In one embodiment of the present invention, the PN-type composite material comprises a mixture of nickel oxide and at least one of aluminum oxide, zinc oxide, tin dioxide, silicon dioxide, titanium dioxide, and cerium dioxide.

[0082] In one embodiment of the present invention, the PN-type composite material comprises a mixture of cuprous oxide and at least one of aluminum oxide, zinc oxide, tin dioxide, silicon dioxide, titanium dioxide, and cerium dioxide.

[0083] In one embodiment of the present invention, the PN-type composite material comprises a mixture of manganese oxide and at least one of aluminum oxide, zinc oxide, tin dioxide, silicon dioxide, titanium dioxide, and cerium dioxide.

[0084] In one embodiment of the present invention, the PN-type composite material comprises a mixture of ferrous oxide and at least one of aluminum oxide, zinc oxide, tin dioxide, silicon dioxide, titanium dioxide, and cerium dioxide.

[0085] In one embodiment of the present invention, the PN-type composite material comprises a mixture of cobalt oxide and at least one of aluminum oxide, zinc oxide, tin dioxide, silicon dioxide, titanium dioxide, and cerium dioxide.

[0086] In one embodiment of the present invention, the PN-type composite material comprises a mixture of at least one of tin oxide and aluminum oxide, zinc oxide, tin dioxide, silicon dioxide, titanium dioxide, and cerium dioxide.

[0087] In one embodiment of the present invention, the PN-type composite material comprises a mixture of at least one of cerium trioxide, aluminum trioxide, zinc oxide, tin dioxide, silicon dioxide, titanium dioxide, and cerium dioxide.

[0088] In one embodiment of the present invention, the PN-type composite material includes a mixture of nickel oxide and zinc oxide, a mixture of cuprous oxide and aluminum oxide, or a mixture of cuprous oxide and zinc oxide.

[0089] In one embodiment of the present invention, the PN-type composite material comprises 30 wt% nickel oxide and 70 wt% zinc oxide.

[0090] In one embodiment of the present invention, the PN-type composite material comprises 58.5 wt% cuprous oxide and 41.5 wt% aluminum oxide.

[0091] In one embodiment of the present invention, the PN-type composite material comprises 64 wt% cuprous oxide and 36 wt% zinc oxide.

[0092] In one embodiment of the present invention, the cerium dioxide doped material includes Sm 0.2 Ce 0.8 O2, Gd 0.2 Ce 0.8 O2, La 0.2 Ce 0.8 O2, Ca 0.2 Ce 0.8 O2, La 0.19 Sr 0.01 Ce 0.8 O2, La 0.05 Ca 0.15 Ce 0.8 O2, Sm 0.05 Ca 0.15 Ce 0.8 O2 or Gd 0.05 Ca 0.15 Ce 0.8 O2.

[0093] In one embodiment of the present invention, the molten salt electrolyte in the first electrolyte of the negative electrode, the molten salt electrolyte in the composite electrolyte of the positive electrode, or the molten salt electrolyte in the composite electrolyte of the ion-conducting layer includes chloride, sulfate, or carbonate.

[0094] In one embodiment of the present invention, the chloride includes a first type of chloride, or a mixture of a first type of chloride and a second type of chloride; when the chloride molten salt includes the first type of chloride, the first type of chloride is calcium chloride, or magnesium chloride, or lithium chloride; when the chloride molten salt includes a mixture of the first type of chloride and the second type of chloride, the first type of chloride is one or two of calcium chloride, magnesium chloride, and lithium chloride, and the second type of chloride is at least one of sodium chloride and potassium chloride.

[0095] In one embodiment of the present invention, the sulfate includes lithium sulfate, or a mixed molten salt of sodium sulfate and lithium sulfate.

[0096] In one embodiment of the invention, the sulfate comprises a mixed molten salt of sodium sulfate and lithium sulfate, wherein the mass ratio of sodium sulfate to lithium sulfate is 1:0.1 to 1:10. Typical, non-limiting, mass ratios of sodium sulfate to lithium sulfate are 1:0.1, 1:0.5, 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, or 1:10.

[0097] In one embodiment of the present invention, the carbonate includes at least one of sodium carbonate, potassium carbonate, and lithium carbonate.

[0098] In one embodiment of the present invention, the carbonate comprises a ternary mixed molten salt of sodium carbonate, potassium carbonate and lithium carbonate, wherein the mass ratio of potassium carbonate:lithium carbonate:sodium carbonate is 3:1:6, or 3:2:5, or 4:2:4, or 5:2:3.

[0099] In one embodiment of the present invention, the chloride comprises a molten salt of a mixture of calcium chloride and sodium chloride.

[0100] In one embodiment of the present invention, the chloride comprises a molten salt of a mixture of calcium chloride, sodium chloride and potassium chloride.

[0101] In one embodiment of the present invention, the chloride comprises a molten salt of a mixture of calcium chloride, magnesium chloride, sodium chloride and potassium chloride.

[0102] In one embodiment of the present invention, the chloride comprises a molten salt of a mixture of calcium chloride, lithium chloride, sodium chloride and potassium chloride.

[0103] In one embodiment of the present invention, the molten electrolyte comprises a chloride, and the chloride molten salt comprises a mixture of a first type of chloride and a second type of chloride, wherein the first type of chloride comprises calcium chloride or magnesium chloride, and the molar proportion of calcium chloride or magnesium chloride in the mixture is not less than 20%. Preferably, the molar proportion of calcium chloride or magnesium chloride in the mixture is not less than 30%. Preferably, the molar proportion of calcium chloride or magnesium chloride in the mixture is 50%.

[0104] Preferably, in the mixture of the first type of chloride and the second type of chloride, the molar ratio of sodium chloride to calcium chloride is 1:1, or the molar ratio of potassium chloride to magnesium chloride is 1:1 or 2:1.

[0105] In one embodiment of the present invention, the second electrolyte of the ion-conducting layer or the third electrolyte of the positive electrode comprises a composite electrolyte of a solid electrolyte and a molten salt electrolyte, wherein the mass of the molten salt electrolyte accounts for 10-35% of the total mass of the composite electrolyte. Typical but non-limiting molten salt electrolyte mass ratios in the present invention are 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, or 35%.

[0106] In one embodiment of the present invention, the second electrolyte of the ion-conducting layer or the third electrolyte of the positive electrode comprises a mixture of the aforementioned cerium dioxide doped material and 10-30 wt% of the molten salt electrolyte, wherein the molten salt electrolyte comprises a mixture of at least one selected from sodium carbonate, potassium carbonate, lithium carbonate, sodium chloride, potassium chloride, calcium chloride, lithium sulfate, sodium sulfate, and sodium lithium sulfate. Preferably, it comprises Sm 0.2 Ce 0.8 A mixture of O2 and sodium carbonate, Gd 0.2 Ce 0.8 A mixture of O2 and sodium chloride, La 0.2 Ce 0.8 A mixture of O2 and sodium sulfate, Ca 0.2 Ce 0.8 A mixture of O2 and sodium chloride, La 0.19 Sr 0.01 Ce 0.8 A mixture of O2 and sodium carbonate, La 0.19 Sr 0.01 Ce 0.8 A mixture of O2 and sodium chloride, La 0.05 Ca 0.15 Ce 0.8 A mixture of O2 and sodium carbonate, La 0.05 Ca 0.15 Ce0.8 A mixture of O2 and sodium chloride, Sm 0.05 Ca 0.15 Ce 0.8 A mixture of O2 and sodium chloride, Sm 0.05 Ca 0.15 Ce 0.8 A mixture of O2 and sodium carbonate, La 0.19 Sr 0.01 Ce 0.8 A mixture of O2, sodium chloride, and calcium chloride, or Gd 0.05 Ca 0.15 Ce 0.8 A mixture of O2 and sodium chloride.

[0107] In one embodiment of the present invention, the second electrolyte of the ion-conducting layer or the third electrolyte of the positive electrode includes Sm 0.2 Ce 0.8 O2 + 20wt% sodium carbonate, Gd 0.2 Ce 0.8 O2 + 20wt% sodium chloride, La 0.2 Ce 0.8 O2 + 20wt% sodium sulfate, Ca 0.2 Ce 0.8 O2 + 20wt% sodium chloride, La 0.19 Sr 0.01 Ce 0.8 O2 + 20wt% sodium carbonate, La 0.19 Sr 0.01 Ce 0.8 O2 + 20wt% sodium chloride, La 0.05 Ca 0.15 Ce 0.8 O2 + 20wt% sodium carbonate, La 0.05 Ca 0.15 Ce 0.8 O2 + 20wt% sodium chloride, Sm 0.05 Ca 0.15 Ce 0.8 O2 + 20wt% sodium chloride, Sm 0.05 Ca 0.15 Ce 0.8 O2 + 20wt% sodium carbonate, La 0.19 Sr 0.01 Ce 0.8 O2 + 20wt% (sodium chloride + calcium chloride), or Gd 0.05 Ca 0.15 Ce 0.8 O2 + 20wt% sodium chloride.

[0108] In one embodiment of the present invention, the second electrolyte of the ion-conducting layer or the third electrolyte of the positive electrode comprises a mixture of the above-mentioned PN-type composite material and 10-30 wt% of the molten salt electrolyte, wherein the molten salt electrolyte comprises at least one of sodium carbonate, potassium carbonate, lithium carbonate, sodium chloride, potassium chloride, calcium chloride, lithium sulfate, sodium sulfate, and sodium lithium sulfate.

[0109] In one embodiment of the present invention, the second electrolyte of the ion-conducting layer or the third electrolyte of the positive electrode comprises a mixture of cuprous oxide, zinc oxide and sodium chloride, more preferably, comprising (64% cuprous oxide + 36% zinc oxide) + 20% sodium chloride, wherein the mass of sodium chloride is 20% of the total mass of the composite electrolyte, and the mass ratio of cuprous oxide to zinc oxide is 64:36.

[0110] In one embodiment of the present invention, the second electrolyte of the ion-conducting layer or the third electrolyte of the positive electrode comprises a mixture of nickel oxide, zinc oxide and sodium carbonate. More preferably, the second electrolyte of the ion-conducting layer or the third electrolyte of the positive electrode comprises (30% nickel oxide + 70% zinc oxide) + 20% sodium carbonate, wherein the mass of sodium carbonate is 20% of the total mass of the composite electrolyte, and the mass ratio of nickel oxide to zinc oxide is 30:70.

[0111] In one embodiment of the present invention, the second electrolyte of the ion-conducting layer or the third electrolyte of the positive electrode comprises a mixture of cuprous oxide, aluminum oxide, and potassium carbonate. More preferably, the second electrolyte of the ion-conducting layer or the third electrolyte of the positive electrode comprises (58.5% cuprous oxide + 41.5% aluminum oxide) + 20% potassium carbonate, wherein the mass of potassium carbonate is 20% of the total mass of the composite electrolyte, and the mass ratio of cuprous oxide to aluminum oxide is 58.5:41.5.

[0112] In one embodiment of the present invention, the second electrolyte of the ion-conducting layer or the third electrolyte of the positive electrode comprises a mixture of nickel oxide, zinc oxide, sodium chloride, and calcium chloride, wherein the mass of sodium chloride and calcium chloride is 20% of the total mass of the composite electrolyte, and the mass ratio of nickel oxide to zinc oxide is 1:2.53.

[0113] In one embodiment of the present invention, when the second electrolyte of the ion-conducting layer or the third electrolysis of the positive electrode contains a molten salt electrolyte, that is, a molten salt electrolyte or a composite electrolyte consisting of a solid electrolyte and a molten salt electrolyte, these electrolytes have one or more of the following characteristics:

[0114] (1) The melting point of molten salt electrolyte is between 400-700℃; the working range of composite electrolyte is between 400-700℃.

[0115] (2) Total ionic conductivity greater than 0.05 S / cm;

[0116] It should be noted that the mixed ion conductivity can be calculated by measuring the oxygen ion conductivity and the hydrogen ion conductivity separately and then summing them.

[0117] This invention can prepare solid electrolytes containing cerium dioxide doped with one or two of magnesium, calcium, strontium, lanthanum, samarium, and gadolinium using co-precipitation or sol-gel methods. For example, the preparation method includes: cerium nitrate and one, two, or three of magnesium nitrate, samarium nitrate, calcium nitrate, strontium nitrate, lanthanum nitrate, and gadolinium nitrate as precursors, dissolved separately in deionized water according to molar ratios, and then mixed thoroughly. An appropriate amount of citric acid as a precipitant is added, and the mixture is stirred and sonicated in a 70°C water bath, then stirred again in a 70°C water bath until a colloid is formed. Then, it is vacuum dried at 105°C for 12 hours. Finally, it is calcined at 600°C for 2 hours at a heating rate of 10°C per minute to obtain the cerium dioxide doped material.

[0118] The cerium dioxide-doped material obtained above is mixed with at least one of sodium carbonate, potassium carbonate, lithium carbonate, sodium chloride, potassium chloride, calcium chloride, lithium sulfate, sodium sulfate, and sodium lithium sulfate in a certain proportion, ground evenly, sintered at a high temperature of 600-900℃, and then ground into powder to obtain the composite electrolyte. The composite electrolyte is then formed into a film or pressed into a tablet and sintered to obtain an ion-conducting layer.

[0119] The present invention can prepare PN type composite material by solid-state synthesis: select P-type semiconductor oxide and N-type semiconductor oxide are weighed according to the designed ratio, ground evenly, sintered at high temperature of 600-900℃, cooled and ground into powder to obtain PN type composite material.

[0120] The PN-type composite material obtained above is used as a raw material and is mixed with at least one of sodium carbonate, potassium carbonate, lithium carbonate, sodium chloride, potassium chloride, calcium chloride, lithium sulfate, sodium sulfate, and sodium lithium sulfate in a certain proportion. The mixture is ground evenly, sintered at high temperature, and then ground into powder to obtain the molten salt PN-type composite electrolyte. The composite electrolyte is then formed into a film or pressed into a sheet and sintered to obtain an ion-conducting layer.

[0121] In this invention, the composite electrolyte is used as the positive electrode, and the following method can also be adopted: after melting the molten salt electrolyte, the solid electrolyte and other powder components (conductive agent, porous catalyst material, etc.) are immersed in the molten salt electrolyte, stirred evenly, cooled, ground into powder, pore-forming agent ammonium bicarbonate is added, mixed evenly, pressed into sheets, heated until the pore-forming agent decomposes to form a porous structure, and then sintered by continuing to heat to obtain a sheet-shaped positive electrode.

[0122] In this invention, the positive electrode, negative electrode, and ion-conducting layer contain an electrolyte with high conductivity, which can reduce the internal resistance of the battery.

[0123] In this invention, the composite electrolyte in the positive electrode and ion-conducting layer is a product of a mixture of solid electrolyte and molten salt. The conductivity of this composite electrolyte is higher than that of the solid electrolyte. At the same time, the working temperature of the electrolyte is reduced to 400-700℃, and it even has a high conductivity in the temperature range where the molten salt electrolyte has not melted, thus expanding the applicable temperature range of the composite electrolyte.

[0124] It should be noted that in a battery, the third electrolyte in the positive electrode and the second electrolyte in the ion-conducting layer can be the same material or different materials.

[0125] In one embodiment of the present invention, the porous catalyst material of the positive electrode is titanium suboxide or manganese dioxide; or LaMO3, La （1-x） Ca x MO3, La （1-x） Sr x MO3, La 0.1 Sr （0.9-x） Ca x At least one of MO3, wherein M = at least one of Mn, Fe, Ni, Co, Cu, and x is 0.1 to 0.9; or titanium suboxide or manganese dioxide supported on porous carbon-based material.

[0126] In one embodiment of the present invention, the porous carbon-based material includes, but is not limited to, one or more of carbon nanotubes, carbon fibers, graphite, graphene, and amorphous carbon powder.

[0127] In one embodiment of the present invention, the porous catalyst material is LaMnO3, LaCoO3, LaNiO3, or LaMnO3. 0.5 Cu 0.5 O3, LaMn 0.5 Ni 0.5 O3, La 0.5 Ca 0.5 MnO3, La 0.5 Ca 0.5 CoO3, La 0.5 Ca 0.5 FeO3, La 0.5 Ca 0.5 NiO3, La 0.1 Sr 0.4 Ca 0.5 At least one of MnO3.

[0128] The cathode of this invention employs the aforementioned third electrolyte and the aforementioned porous catalyst material, enabling these catalysts to achieve high oxygen reduction capabilities between 400-700°C. In existing high-temperature solid fuel cells, the oxygen reducing agent needs to remain active at temperatures of 800-1000°C.

[0129] The reaction process of the carbon fuel cell of this invention is as follows: air is introduced into the positive electrode current collector and the flow channel on the positive electrode side, and the oxygen in the air is reduced to O at the positive electrode. 2- O 2- The electrolyte is transported to the negative electrode through the electrolyte in the positive electrode, the electrolyte in the ion-conducting layer, and the electrolyte in the negative electrode, where it undergoes an oxidation reaction with the carbon fuel C to produce CO. 2 CO 2 It is discharged from the negative electrode side.

[0130] Example 1: Medium-temperature carbon fuel cell with molten salt cerium oxide-doped composite electrolyte

[0131] The negative electrode consists of carbon particles, a first electrolyte, and a catalyst. The catalyst is a nickel-aluminum alloy with aluminum accounting for 50% by mass (purchased from nickel-aluminum alloy powder). The first electrolyte is a ternary carbonate molten salt electrolyte with a mass ratio of potassium carbonate:lithium carbonate:sodium carbonate = 3:1:6, a melting point of 381℃, a heat of fusion of 122kJ / kg, and an operating temperature of less than 700℃.

[0132] The ion-conducting layer includes an electrolyte membrane made of a second electrolyte, which is a composite electrolyte consisting of a mixture of molten salt and electrolyte, specifically La. 0.19 Sr 0.01 Ce 0.8 O2 + 20wt% sodium carbonate. The total conductivity of this composite electrolyte at 550℃ was 112 mS / cm, as measured using an electrochemical workstation. This is higher than the conductivity of 9 mol% yttrium-doped YSZ solid electrolyte in conventional SOFC fuel cells at 550℃ (less than 10 mS / cm).

[0133] The positive electrode comprises a porous catalyst material and a third electrolyte, which is a composite electrolyte consisting of a mixture of molten salt and electrolyte, and is La 0.19 Sr 0.01 Ce 0.8 O2 + 20wt% sodium carbonate. The porous catalyst material is La. 0.1 Sr 0.4 Ca 0.5 MnO3.

[0134] Preparation method of ternary carbonate molten salt: Potassium carbonate: Lithium carbonate: Sodium carbonate = 3:1:6. Weigh each component according to the mass ratio, then mix and grind them into powder. Then put them in a crucible and heat to 700-900℃. After melting, stir evenly, let stand for 2-4 hours and then cool. Then crush them into powder for later use.

[0135] Preparation method of composite electrolyte: La 0.19 Sr 0.01 Ce 0.8 O2 + 20wt% sodium carbonate.

[0136] La 0.19 Sr 0.01 Ce 0.8 The O2 preparation method employs a sol-gel method, comprising: cerium nitrate, strontium nitrate, and lanthanum nitrate as precursors, dissolved separately in deionized water according to molar ratios and mixed thoroughly. An appropriate amount of citric acid as a precipitant is added, and the mixture is stirred and sonicated in a 70°C water bath, then stirred again in a 70°C water bath until a colloid is formed. It is then vacuum dried at 105°C for 12 hours. Next, it is calcined at 600°C for 2 hours at a heating rate of 10°C per minute, and then cooled and pulverized to obtain the cerium dioxide-doped solid electrolyte material La. 0.19 Sr 0.01 Ce 0.8 O2.

[0137] Preparation of composite electrolyte: La-doped material is used... 0.19 Sr 0.01 Ce 0.8 O2 is added to 20% sodium carbonate, mixed evenly, ground, then pressed into tablets, and sintered at 900℃ for 2 hours to obtain a solid electrolyte or composite electrolyte membrane (ion-conducting layer) doped with molten salt cerium dioxide.

[0138] Porous catalyst material La 0.1 Sr 0.4 Ca 0.5 MnO3 preparation method: Citric acid-sol-gel method. The precursors are lanthanum nitrate, strontium nitrate, calcium nitrate, and manganese nitrate (divalent manganese ions), which are dissolved separately in deionized water according to their molar ratios and then mixed thoroughly. An appropriate amount of citric acid is added, and the mixture is stirred and sonicated in a 70°C water bath, then stirred again in a 70°C water bath until a colloid is formed. Then, it is vacuum dried at 105°C for 12 hours. Finally, it is calcined at 800°C for 4 hours at a heating rate of 5°C per minute to obtain the porous catalyst La. 0.1 Sr 0.4 Ca 0.5 MnO3.

[0139] Cathode preparation method: The porous catalyst material and the third electrolyte are weighed separately in a mass ratio of 1:1. Then, 10%-20% of the pore-forming agent ammonium bicarbonate is added, mixed evenly, and then pressed into tablets at a pressing pressure of 30 MPa. After heating to 150℃ to decompose the pore-forming agent, the temperature is further increased to 900℃ and maintained for 2 hours to obtain the cathode material.

[0140] The following components were stacked sequentially: negative electrode current collector, a mixture of carbon particles and molten salt electrolyte, catalyst, a 1.7 mm thick stainless steel braided mesh metal support layer, an ion-conducting layer, positive electrode, and positive electrode current collector. These were placed in a container with an air channel on one side of the positive electrode and the other side facing the ion-conducting layer, and sealed. Wires were connected to the positive electrode and catalyst layers respectively. The mixture was then heated to 550°C and held at that temperature for 12 hours before testing. Air heated to 550°C was introduced through the positive electrode side. The open-circuit voltage was 0.76 volts, the operating voltage was 0.62 volts, and the current was 0.70 A. The amount of carbon particles added was 0.1 g, and the continuous power generation time was 1 hour. The fuel utilization rate was 78%, with the remainder released as carbon monoxide. The fuel cell efficiency was 62%, and the system efficiency based on fuel consumption was 48%, exceeding the 43-45% power generation efficiency of coal-fired power generation.

[0141] Example 2: PN-type composite electrolyte intermediate-temperature carbon fuel cell

[0142] The negative electrode includes carbon particles, a first electrolyte, and a catalyst, the catalyst being metallic nickel; the first electrolyte is a molten salt electrolyte, specifically a ternary carbonate molten salt electrolyte; the mass ratio of the ternary carbonate molten salt is potassium carbonate:lithium carbonate:sodium carbonate = 3:1:6, melting point 381℃, heat of fusion 122kJ / kg, and operating temperature less than 700℃.

[0143] The ion-conducting layer includes an electrolyte membrane made of a second electrolyte, which is a composite electrolyte consisting of a mixture of molten salt electrolytes; the positive electrode includes a porous catalyst material and a third electrolyte, which is a composite electrolyte consisting of a mixture of a solid electrolyte and a molten salt electrolyte.

[0144] The composite electrolyte consists of (30wt% nickel oxide + 70wt% zinc oxide) + 20wt% sodium carbonate.

[0145] The porous catalyst material is manganese dioxide, and manganese dioxide powder with a particle size of 100 nanometers is commercially available.

[0146] Preparation method of molten salt PN-type composite electrolyte: A solid-phase synthesis method is adopted. Nickel oxide and zinc oxide are weighed separately at a mass ratio of 30:70, then ground evenly, sintered at 900℃, cooled, and ground into powder to obtain solid electrolyte powder. The molten salt mass ratio is 20%. Molten sodium carbonate is first heated to 600℃ to melt, then the above solid electrolyte powder is added, stirred evenly, cooled, and pulverized to obtain molten salt PN-type composite electrolyte powder. The resulting molten salt PN-type composite electrolyte is pressed into tablets and sintered to form a solid electrolyte membrane for use as an ion-conducting layer.

[0147] Preparation method of anode material: Manganese dioxide and molten salt PN type composite electrolyte are weighed separately in a mass ratio of 1:1, and then 20% ammonium bicarbonate pore-forming agent is added. After mixing evenly, the mixture is pressed into tablets at a pressure of 30 MPa. Then, the tablets are heated to 150℃ to decompose the pore-forming agent, and the temperature is further increased to 900℃ and maintained for 2 hours to obtain the anode material.

[0148] The following components were stacked sequentially: a negative electrode current collector, a mixture of carbon particles and molten salt electrolyte, a nickel catalyst mesh (foamed nickel mesh), a 1.7 mm thick stainless steel woven mesh metal support layer, an ion-conducting layer, a positive electrode, and a positive electrode current collector. These were placed in a container with an air channel on one side of the positive electrode and the other side facing the ion-conducting layer, and the container was sealed. Wires were connected to the positive electrode and catalyst respectively. The container was then heated to 550°C and held at that temperature for 12 hours before testing. Air heated to 550°C was introduced through the positive electrode side. The open-circuit voltage was 0.72 volts, the operating voltage was 0.60 volts, and the current was 0.68 A. The amount of carbon particles added was 0.1 gram, and the continuous power generation time was 1 hour. The fuel utilization rate was 76%, with the remainder released as carbon monoxide. The fuel cell efficiency was 60%, and the system efficiency based on fuel consumption was 45.6%, exceeding the 43-45% power generation efficiency of coal-fired power generation, demonstrating significant application value.

[0149] Throughout this specification, references to "an example," "an embodiment," or "an embodiment" indicate that a particular feature, structure, or characteristic described in connection with an embodiment is included in at least one embodiment. Therefore, the appearance of "an example," "an embodiment," or "an embodiment" in various places throughout this specification does not necessarily refer to the same embodiment. Furthermore, a particular feature, structure, or characteristic may be combined in any manner in one or more embodiments.

[0150] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. An intermediate temperature carbon fuel cell, characterized by, The medium-temperature carbon fuel cell comprises an ion conductive layer, and a negative electrode and a positive electrode arranged on both sides of the ion conductive layer, wherein the negative electrode comprises carbon particles, a first electrolyte and a catalyst; the first electrolyte is a molten salt electrolyte; The ion conductive layer comprises an electrolyte film made of a second electrolyte, wherein the second electrolyte is a solid electrolyte or a composite electrolyte mixed with a solid electrolyte and a molten salt electrolyte; The positive electrode comprises a porous catalyst material and a third electrolyte, wherein the third electrolyte is a solid electrolyte or a composite electrolyte mixed with a solid electrolyte and a molten salt electrolyte.

2. The intermediate-temperature carbon fuel cell according to claim 1, characterized by The mass ratio of the porous catalyst material in the positive electrode is 40-60 wt%.

3. The intermediate-temperature carbon fuel cell according to claim 1 or 2, characterized by The medium-temperature carbon fuel cell further comprises a metal support layer, and the carbon particles and the molten salt electrolyte mixture, the catalyst, the metal support layer, the ion conductive layer and the positive electrode are sequentially arranged from top to bottom, wherein the mixture comprises a first part and a second part, the first part and the second part are sequentially arranged from top to bottom, the first part comprises the carbon particles, and the second part comprises a mixture of the carbon particles and the molten salt electrolyte.

4. An intermediate temperature carbon fuel cell according to any one of claims 1 to 3, characterised in that, The solid electrolyte is selected from a cerium dioxide doped material or a PN type composite material; The cerium dioxide doped material comprises at least one of cerium dioxide doped lanthanum oxide, samarium oxide, gadolinium oxide, magnesium oxide, calcium oxide and strontium oxide, and the doping ratio is 5% to 20% (mole ratio). The PN type composite material is a mixture of a P type semiconductor oxide and an N type semiconductor oxide, and the mass ratio of the P type semiconductor oxide to the N type semiconductor oxide is 1:0.1-10; The P type semiconductor oxide comprises at least one of nickelous oxide, ferrous oxide, cuprous oxide, stannous oxide, manganous oxide, cerium sesquioxide, cobaltous oxide and tricobalt tetroxide; The N type semiconductor oxide comprises at least one of nickel sesquioxide, iron sesquioxide, cobalt sesquioxide, copper oxide, manganese dioxide, tin dioxide, titanium dioxide, silicon dioxide, cerium dioxide and zinc oxide. Optionally, the PN type composite material comprises a mixture of nickelous oxide+zinc oxide, a mixture of cuprous oxide+aluminum sesquioxide or a mixture of cuprous oxide+zinc oxide.

5. The intermediate-temperature carbon fuel cell of claim 4, wherein, The ceria-doped material comprises Sm 0.2 Ce 0.8 O2, Gd 0.2 Ce 0.8 O2, La 0.2 Ce 0.8 O2, Ca 0.2 Ce 0.8 O2, La 0.19 Sr 0.01 Ce 0.8 O2, La 0.05 Ca 0.15 Ce 0.8 O2, Sm 0.05 Ca 0.15 Ce 0.8 O2 or Gd 0.05 Ca 0.15 Ce 0.8 O2.

6. An intermediate temperature carbon fuel cell according to any one of claims 1 to 5, characterised in that, The molten salt electrolyte comprises a chloride or a sulfate or a carbonate; The chloride molten salt comprises a first type of chloride or a composite of the first type of chloride and a second type of chloride; when the chloride molten salt comprises the first type of chloride, the first type of chloride is calcium chloride or magnesium chloride or lithium chloride; when the chloride molten salt comprises the composite of the first type of chloride and the second type of chloride, the first type of chloride is one or two of calcium chloride, magnesium chloride and lithium chloride, and the second type of chloride is at least one of sodium chloride and potassium chloride; The sulfate comprises lithium sulfate or a mixed molten salt of sodium sulfate and lithium sulfate; The carbonate comprises at least one of sodium carbonate, potassium carbonate and lithium carbonate.

7. The intermediate-temperature carbon fuel cell of claim 6, wherein, The composite electrolyte comprises a mixture of the cerium dioxide doped material and 10-30wt% of the molten salt electrolyte, the molten salt electrolyte comprising a mixture of at least one of sodium carbonate, potassium carbonate, lithium carbonate, sodium chloride, potassium chloride, calcium chloride, lithium sulfate, sodium sulfate, lithium sodium sulfate; Optionally, the composite electrolyte comprises Sm 0.2 Ce 0.8 O2 + sodium carbonate, Gd 0.2 Ce 0.8 O2 + sodium chloride, La 0.2 Ce 0.8 O2 + sodium sulfate, Ca 0.2 Ce 0.8 O2 + sodium chloride, La 0.19 Sr 0.01 Ce 0.8 O2 + sodium carbonate, La 0.19 Sr 0.01 Ce 0.8 O2 + sodium chloride, La 0.05 Ca 0.15 Ce 0.8 O2 + sodium carbonate, La 0.05 Ca 0.15 Ce 0.8 O2 + sodium chloride, Sm 0.05 Ca 0.15 Ce 0.8 O2 + sodium chloride, Sm 0.05 Ca 0.15 Ce 0.8 O2 + sodium carbonate, La 0.19 Sr 0.01 Ce 0.8 O2 + sodium chloride + calcium chloride, or Gd 0.05 Ca 0.15 Ce 0.8 O2 + sodium chloride.

8. The intermediate-temperature carbon fuel cell of claim 6, wherein, The composite electrolyte comprises a mixture of the PN type composite material and 10-30wt% of the molten salt electrolyte, the molten salt electrolyte comprising at least one of sodium carbonate, potassium carbonate, lithium carbonate, sodium chloride, potassium chloride, calcium chloride, lithium sulfate, sodium sulfate, lithium sodium sulfate. Optionally, the composite electrolyte comprises a mixture of cuprous oxide + zinc oxide + sodium chloride. Optionally, the composite electrolyte comprises a mixture of cuprous oxide + zinc oxide + sodium chloride. Optionally, the composite electrolyte comprises a mixture of cuprous oxide + zinc oxide + sodium chloride. Optionally, the composite electrolyte comprises a mixture of cuprous oxide + zinc oxide + sodium chloride.

9. An intermediate temperature carbon fuel cell according to any one of claims 1 to 8, characterised in that, The molten salt electrolyte and the composite electrolyte mixed with the molten salt electrolyte have one or more of the following characteristics: (1) The melting point of the molten salt electrolyte is between 400-700℃; the working range of the composite electrolyte is between 400-700℃. (2) The total ionic conductivity is greater than 0.05S / cm. The intermediate temperature carbon fuel cell according to claim 1, wherein The porous catalyst material is titanium suboxide or manganese dioxide; or LaMO3, La （1-x） Ca x MO3, La （1-x） Sr x MO3, La 0.1 Sr （0.9-x） Ca x MO3, La （1-x） Sr x MO3, La 0.1 Sr （0.9-x） Ca x MO3, La （1-x） Sr x MO3, La 0.1 Sr （0.9-x） Ca x MO3, La （1-x） Sr x MO3, La 0.1 Sr （0.9-x） Ca x MO3, La （1-x） Sr x MO3, La 0.1 Sr （0.9-x） Ca x MO3, La （1-x） Sr x MO3, La 0.1 Sr （0.9-x） Ca Optionally, the porous catalyst material is at least one of LaMn03, LaCo03, LaNi03, LaMn 0.5 Cu 0.5 O3, LaMn 0.5 Ni 0.5 O3, La 0.5 Ca 0.5 Mn03, La 0.5 Ca 0.5 Co03, La 0.5 Ca 0.5 Fe03, La 0.5 Ca 0.5 Ni03, La 0.1 Sr 0.4 Ca 0.5 Mn03.

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