All-solid-state lithium-ion membrane reactor having symmetrical structure and use thereof

Abstract

The present invention relates to an all-solid-state lithium-ion membrane reactor having a symmetrical structure and a use thereof. The reactor is a gas diffusion electrode constructed in situ on two sides of a solid-state lithium-ion conductor membrane, wherein Pt and / or Ni are used as catalysts and a conductive material such as single-walled carbon nanotubes is used as a current collector. The reactor can work in a nitrogen-hydrogen mixed atmosphere, having a high level of integration and a flexible scale. The present invention changes the working mode of a conventional reactor that uses a liquid electrolyte, replaces the inefficient nitrogen and proton mass transfer with efficient lithium-ion mass transfer, couples lithium-mediated nitrogen reduction and a hydrogen oxidation reaction to synthesize ammonia, increases the maximum working current density to 1000 mA / cm2, and can work for a long time under the current density of 40 mA / cm2. The present invention is innovative and has wide industrial application prospects.

Description

An all-solid-state lithium ion membrane reactor with symmetrical structure and its application Technical Field

[0001] The present disclosure relates to the field of inorganic solid electrolyte materials and electrochemical catalysis technology, and in particular to an all-solid-state lithium ion membrane reactor with a symmetrical structure and applications thereof. Background Art

[0002] Ammonia is an irreplaceable nitrogen source with extensive applications in agriculture and chemical production, playing a vital role in social development. The Haber-Bosch process is the most mature industrial technology for directly producing ammonia from nitrogen and hydrogen. However, its reaction conditions are harsh (high temperature of 400-600°C, high pressure of 100-150 bar), it consumes a lot of electricity, and it is not adaptable to renewable energy. A membrane reactor based on a solid proton conductor has achieved electrochemical synthesis at normal pressure. However, due to the lack of an effective mechanism for the nitrogen reduction reaction (NRR), the yield of synthetic ammonia is very low.

[0003] The lithium-mediated nitrogen reduction reaction (LiNR) effectively dissociates strong N≡N triple bonds, enabling efficient room-temperature ammonia synthesis using intermittent electrochemical cells in non-aqueous liquid electrolyte systems (e.g., lithium salts dissolved in alcohol and tetrahydrofuran). However, the mass transfer of nitrogen and hydrogen in non-aqueous liquid electrolytes is limited, necessitating pressurization (5-50 bar) to ensure a stable supply of raw materials. Furthermore, such reactors require constant replenishment of the proton source, resulting in a short operating life. Using stainless steel cloth as a gas diffusion electrode (GDE) in a three-chamber cell circumvents the limitations of gas transport in liquid electrolytes and allows the direct use of hydrogen as a proton source. However, proton transport is still limited to organic solvents. Furthermore, the produced ammonia is mostly distributed in the electrolyte, requiring complex purification steps, further increasing production costs. Therefore, it is necessary to develop a new, efficient nitrogen fixation process that achieves both high gas diffusion rates and is compatible with renewable energy sources.

[0004] Summary of the Invention

[0005] To address the above problems, in this study, the present disclosure proposes a rational design, including a reactor based on an all-solid-state lithium-ion symmetric battery, in which the electrodes are gas diffusion electrodes synthesized in situ on a solid electrolyte. Sustainable proton replenishment is achieved through hydrogen oxidation reaction, and the N≡N triple bond is broken by the LiNR reaction, which can continuously produce ammonia for 100 hours at normal pressure and at a current density of 1000mA / cm 2 The maximum ammonia production was 101.9±7.9nmol / s / cm 2 .

[0006] The present disclosure provides the following technical solutions:

[0007] A fully solid-state lithium ion membrane reactor with a symmetrical structure comprises a solid-state lithium ion conductor membrane and a gas diffusion electrode. The reactor is characterized in that the gas diffusion electrodes are in-situ constructed on both sides of the solid-state lithium ion conductor membrane; the solid-state lithium ion conductor membrane comprises a solid-state lithium ion membrane material, which is one of an inorganic solid-state lithium ion membrane material and a polymer-based solid-state lithium ion membrane material; the gas diffusion electrode comprises one or both of Ni and Pt catalysts, and also comprises a conductive current collector material.

[0008] Preferably, the inorganic solid-state lithium ion membrane material is one of an oxide-type solid-state lithium ion membrane material, a halide-type solid-state lithium ion membrane material and a sulfide-type solid-state lithium ion membrane material.

[0009] Preferably, taking the preparation of a solid lithium ion conductor membrane using an oxide-type solid lithium ion membrane material as an example, the preparation method is one of a high-temperature solid-phase synthesis method and a casting method.

[0010] Preferably, the high temperature solid phase synthesis method for preparing an oxide-type solid lithium ion conductor film may include the following steps:

[0011] Step 1): obtaining an oxide-type solid-state lithium ion membrane material precursor;

[0012] Step 2): pouring the precursor into a mold and applying pressure to obtain a green body;

[0013] Step 3): The green body obtained in step 2) is heated and calcined to obtain an oxide-type solid lithium ion conductor membrane.

[0014] Preferably, the oxide-type solid-state lithium ion membrane material precursor in step 1) is one of garnet-type lithium lanthanum zirconate and its element-doped compounds, NASICON-type lithium aluminum titanium phosphate and its element-doped compounds, and perovskite-type lithium lanthanum titanate and its element-doped compounds. The preparation method of garnet-type lithium lanthanum zirconate and its element-doped compounds is as follows: after mixing the lithium source, lanthanum source, zirconium source, and doping source in a stoichiometric ratio, adding a grinding medium to grind and dry, and heating and calcining to obtain lithium lanthanum zirconyl oxide powder. The grinding medium is selected from any one of isopropanol and ethanol; the grinding is selected from at least one of manual grinding, drum ball milling, planetary ball milling, and high-energy ball milling, and the grinding time is 6-24h; the heating rate is 2-5℃ / min, the calcination temperature is 800-1000℃, and the calcination time is 6-20h.

[0015] Preferably, the pressure is applied in step 2) by at least one of uniaxial static pressing and cold isostatic pressing.

[0016] Preferably, the mass of the green body in step 3) is 0.1-1.0 g.

[0017] Preferably, the conductive current collector material is one or more of metal, conductive carbon and conductive ceramic.

[0018] Preferably, taking a solid lithium ion conductor membrane prepared from an oxide-type solid lithium ion membrane material as an example, the method for preparing a gas diffusion electrode comprises the following steps:

[0019] Step 1): NiO powder and oxide-type solid lithium ion membrane material are mixed and dispersed in a solvent such as ethanol to obtain a suspension;

[0020] Step 2): dissolving H2PtCl6 powder in a solvent such as ethanol to obtain a H2PtCl6 solution;

[0021] Step 3): One or both of the suspension obtained in step 1 and the H2PtCl6 solution obtained in step 2 are coated on both sides of the solid lithium ion conductor membrane, and then the temperature is increased and calcined in a glove box with an argon atmosphere. NiO and H2PtCl6 precipitate Ni metal and Pt metal on both sides of the solid lithium ion conductor membrane, and finally a solid lithium ion conductor membrane loaded with one or both of Ni and Pt catalysts is obtained.

[0022] Step 4): Coat the liquid conductive current collector material or the dispersion of the solid conductive current collector material on both sides of the solid lithium ion conductor membrane loaded with one or both of Ni and Pt catalysts obtained in step 3, so that a current collector conductive network structure coated with a metal element catalyst is formed on both sides of the solid lithium ion conductor membrane, that is, gas diffusion electrodes are formed on both sides of the solid lithium ion conductor membrane.

[0023] Preferably, in step 2), the concentration of the H2PtCl6 solution is 0.1-50 mol / L.

[0024] Preferably, in step 4), the dispersion of the solid conductive current collector material is prepared by uniformly dispersing the solid conductive current collector material in a solvent at a concentration of 1-10 mol / L.

[0025] Preferably, in step 3), the calcination is carried out at a temperature of 300-500° C. for 5-20 seconds.

[0026] The present disclosure further provides an ammonia synthesis method, which includes at least the following steps: introducing a mixture of N2 and H2 into the above-mentioned all-solid-state lithium ion membrane reactor, and energizing the gas diffusion electrodes formed on both sides of the solid lithium ion conductor membrane to react, i.e., synthesizing ammonia.

[0027] Preferably, the reaction temperature is 300-600°C.

[0028] Preferably, the current density of the reaction is 1-1000 mA / cm 2 .

[0029] The beneficial effects of the present disclosure are:

[0030] This disclosure provides a symmetrically structured all-solid-state lithium-ion membrane reactor that implements lithium-mediated nitrogen reduction using a solid electrolyte. In situ synthesis of a gas diffusion electrode on the solid electrolyte catalyzes the oxidation of hydrogen to protons. Nitrogen and hydrogen can directly reach the surface of the gas diffusion electrode, eliminating the mass transfer limitations of conventional liquid reactors. Nitrogen and hydrogen can serve as continuous nitrogen and proton sources for the ammonia synthesis reaction.

[0031] 2. The present disclosure also provides a new method for synthesizing ammonia, which utilizes a symmetrical all-solid-state lithium ion membrane reactor to achieve an industrial-grade current density (1000 mA / cm 2 ), the ammonia yield was greatly improved to 101.9±7.9nmol / s / cm 2 The reactor can be started and stopped at will without damaging the catalyst, and can operate for up to 100 hours cumulatively, making it ideal for unstable renewable energy sources. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] FIG1 is a schematic diagram of an embodiment of the lithium-mediated electrochemical reduction of nitrogen to ammonia proposed in the present disclosure.

[0033] FIG2 is a diagram of Li synthesized in Example 1 and Comparative Example 1 of the present disclosure. 6.5 La3Zr 1.5 Ta 0.5 O 12 X-ray diffraction spectrum of solid-state lithium-ion membrane material at room temperature.

[0034] FIG3 is a diagram of Li synthesized in Example 1 and Comparative Example 1 of the present disclosure. 6.5 La3Zr 1.5 Ta 0.5 O 12 Arrhenius plot of the overall conductivity of solid-state lithium-ion membrane materials.

[0035] Figure 4 is a scanning electron microscope image and elemental energy spectrum analysis test image of the all-solid-state lithium ion membrane reactor with a symmetrical structure prepared in Example 1 and Comparative Example 1 of the present disclosure, wherein (a) is a cross-section of the reactor and (b) is the surface of the reactor.

[0036] Figure 5 is a working test diagram of the reactor prepared in Example 1 and Comparative Example 1 of the present disclosure, wherein (a) is a working voltage line diagram and an ammonia yield diagram, and (b) is a UV-visible absorption spectrum diagram of the collected reactor tail gas absorption liquid after the color development reaction.

[0037] FIG6 is a graph showing the ammonia synthesis performance test of the all-solid-state lithium ion membrane reactor prepared in Example 1 of the present disclosure, (a) is a graph showing the ammonia synthesis stability test, and (b) is a graph showing the stability of the ammonia synthesis at an industrial current density (1000 mA / cm 2 ) is a working condition diagram, and (c) is the XRD pattern of ammonium chloride prepared by this reactor (the inset is a photo of the product).

[0038] FIG7 is a test diagram of ammonia yield and corresponding Faraday efficiency of the all-solid-state ion membrane reactor prepared in Example 1 of the present disclosure operating at different temperatures.

[0039] FIG8 is a test graph of ammonia yield and corresponding Faraday efficiency of the all-solid-state ion membrane reactor prepared in Example 1 of the present disclosure operating at different current densities. DETAILED DESCRIPTION

[0040] The present disclosure will be described in detail below with reference to specific embodiments.

[0041] The present disclosure has no particular limitation on the sources of all raw materials in the following examples, and they may be commercially available products.

[0042] Example 1

[0043] This embodiment prepares a solid lithium ion conductor film according to the following steps:

[0044] Li2CO3, La2O3, ZrO2, Ta2O5 are pressed 6.5 La3Zr 1.5 Ta 0.5 O 12 The stoichiometric ratio is weighed. The purity of the above reagents is analytical grade. The amount of Li2CO3 added should be 10% excess by mass. La2O3 is preheated at 900℃ for 7h. The weighed powder is added to a ball mill, and an appropriate amount of isopropanol is added to the ball mill for 12h. After the end, it is dried in a 70℃ oven for 6h. 6.5 La3Zr 1.5 Ta 0.5 O 12 The precursor powder is placed in a crucible, and then the temperature is raised to 900°C at a rate of 5°C / min, kept at this temperature for 7 hours, and then cooled naturally. The obtained powder is again added with an appropriate amount of isopropyl alcohol and ball-milled for 12 hours. After the end, it is dried in a 70°C oven for 6 hours to obtain a solid lithium ion membrane material. Weigh 0.2g of powder and pour it into a mold with an inner diameter of 8mm, apply a small pressure, and hold it for 2 minutes to obtain a disc-shaped green body with a thickness of 0.8-1mm. Place the green body in a cold isostatic press and keep it at 270MPa for 5 minutes to obtain a compacted disc-shaped green body. Take a piece of green body and use ultra-fast high-temperature sintering technology to keep the green body at 1200°C for 5-10s to obtain a solid lithium ion conductor membrane.

[0045] This embodiment prepares an all-solid-state lithium ion membrane reactor according to the following steps:

[0046] NiO powder and Li 6.5 La3Zr 1.5 Ta 0.5 O 12 The solid lithium ion membrane materials were mixed in a mass ratio of 1:1 and dispersed in ethanol to obtain a suspension. The suspension was pipetted twice with a total of 20 μL (10 μL each time) and coated on the Li 6.5 La3Zr 1.5 Ta 0.5 O 12 The two sides of the solid lithium ion conductor membrane were dried at 80 ° C. H2PtCl6 powder was dissolved in ethanol to obtain a H2PtCl6 solution with a concentration of 6 mol / L. The obtained solution was pipetted twice with a total of 20 μL (10 μL each time) and coated on the Li 6.5 La3Zr 1.5 Ta 0.5 O 12 The two sides of the solid lithium ion conductor membrane were heated and dried at 80 ° C. The treated ion membrane was kept at 500 ° C for 10s to obtain Li2O3 loaded with Ni and Pt catalysts. 6.5 La3Zr 1.5 Ta 0.5 O 12 Solid-state lithium ion conductor membrane. Single-walled carbon nanotubes were dispersed in N-methylpyrrolidone (NMP) to obtain a suspension with a concentration of 3 mol / L. The obtained suspension was pipetted twice with a total of 40 μL (20 μL each time) and coated on the Li 6.5 La3Zr 1.5 Ta 0.5 O 12 The two sides of the solid lithium ion conductor membrane were dried at 150 ° C. Finally, an all-solid-state lithium ion membrane reactor was obtained. The surface resistance of the all-solid-state lithium ion membrane reactor was tested with a multimeter and was less than 500Ω.

[0047] This example tests the ammonia synthesis performance of the all-solid-state lithium ion membrane reactor according to the following steps:

[0048] The synthetic ammonia performance test process of the all-solid-state lithium-ion membrane reactor is as follows: silver wires (for connecting to the electrochemical workstation) are led out from the electrodes on both sides of the all-solid-state lithium-ion membrane reactor, the all-solid-state lithium-ion membrane reactor is sealed in a quartz glass tube equipped with an air pipe, and then the device is fixed in a tube furnace and heated to the test temperature (350℃, 400℃, 450℃, 500℃) at a heating rate of 5℃ / min. A current (10mA / cm 2 -1000mA / cm2 ) are required to maintain uninterrupted testing for 0.5h. The flow rate of the gas used in the test is precisely controlled by a mass flow controller. An N2 / H2 mixed gas with a volume ratio of 2:1 is introduced into the air inlet pipe at a flow rate of 120mL / min. A dilute sulfuric acid absorption liquid with a concentration of 0.05mol / L is introduced into the exhaust pipe to absorb the generated ammonia. The absorbance of the absorption liquid is quantitatively detected by ultraviolet-visible spectrophotometry. Finally, the ammonia yield and the corresponding current Faraday efficiency are calculated based on the ammonia standard curve.

[0049] Comparative Example 1

[0050] The difference from Example 1 is that no current was applied during the test.

[0051] Result Analysis

[0052] 1. Analysis of the mechanism of ammonia synthesis in a symmetrical all-solid-state lithium-ion membrane reactor:

[0053] Figure 1 shows the structural details and working principle of the symmetrical all-solid-state lithium-ion membrane reactor. In order to clarify the reaction process, the cathode and anode in the battery structure are artificially distinguished. Pt and Ni catalysts are loaded on the Li 6.5 La3Zr 1.5 Ta 0.5 O 12 Both sides of the solid lithium ion membrane serve as catalysts for the gas diffusion electrode, with a thin carbon nanotube (CNT) layer as the current collector for the gas diffusion electrode. During the charging phase, lithium ions migrate to the cathode surface and obtain electrons from the external circuit, resulting in the formation of metallic lithium. Subsequently, nitrogen molecules quickly react with metallic lithium to form Li3N. Hydrogen molecules can react with Li3N at high temperatures to form Li2NH, which exists briefly on the electrode surface (the same process occurs on the anode surface to form Li2NH during the discharge phase). At the same time, Li2NH on the anode side reacts with Li3N to form Li2NH. + Driven by electric current, hydrogen molecules are converted into H + And added to the Li2NH + NH3 is formed at the cathode side (during the discharge phase, the same process occurs to generate NH3).

[0054] 2. Li 6.5 La3Zr 1.5 Ta 0.5 O 12 Phase structure analysis of solid-state lithium-ion membrane materials:

[0055] The Li synthesized in Example 1 and Comparative Example 1 6.5 La3Zr 1.5 Ta 0.5 O 12X-ray diffraction (XRD) analysis was performed, and the experimental results are shown in FIG2 , which show diffraction peaks with good crystallinity, which correspond one-to-one with the Garnet standard card of the cubic phase, indicating a pure cubic garnet phase.

[0056] 3. Li 6.5 La3Zr 1.5 Ta 0.5 O 12 Study on electrochemical properties of solid-state lithium-ion membrane materials:

[0057] In order to study Li 6.5 La3Zr 1.5 Ta 0.5 O 12 Electrochemical properties of solid-state lithium ion membrane materials. Silver paste was coated on both sides of the prepared electrolyte sheet and dried at 200℃ for 30min to construct Ag / Li 6.5 La3Zr 1.5 Ta 0.5 O 12 A symmetrical cell with a Ag-blocked electrode was used. Electrochemical impedance spectroscopy (EIS) was measured at different temperatures, and the corresponding conductivity was calculated. The Arrhenius plot of the total conductivity was obtained, as shown in Figure 3. It shows a low activation energy for conductivity (0.26 eV).

[0058] 4. Li 6.5 La3Zr 1.5 Ta 0.5 O 12 Morphology and element distribution analysis of solid-state lithium-ion membrane reactor

[0059] Li 6.5 La3Zr 1.5 Ta 0.5 O 12 The cross-section and surface morphology of the solid-state lithium-ion membrane reactor were characterized, and the scanning electron micrographs and element distribution are shown in Figure 4. It shows that the Ni and Pt elements are concentrated and uniformly distributed at the interface between the gas diffusion electrode and the solid-state lithium-ion conductor membrane within the scanning range.

[0060] 5. Li 6.5 La3Zr 1.5 Ta 0.5 O 12 Study on the performance of ammonia synthesis in solid-state lithium-ion membrane reactor

[0061] FIG5a shows the Li prepared in Example 1 and Comparative Example 1 of the present disclosure. 6.5 La3Zr 1.5 Ta 0.5 O 12The voltage curve and corresponding ammonia yield of the solid-state lithium-ion membrane reactor during operation. Figure b shows the UV-visible absorption spectrum of the reactor tail gas absorption liquid collected after the color development reaction. Without current, the reactor is almost incapable of ammonia synthesis. However, with current driving the reactor, lithium-mediated ammonia synthesis is achieved.

[0062] FIG6a is a graph showing the stability test of ammonia synthesis of the all-solid-state lithium ion membrane reactor prepared in Example 1 of the present disclosure (test temperature: 450° C., current density: 40 mA / cm 2 ), the reactor maintained 6.9±0.2nmol / s / cm within 100h 2 Figure 6b shows that the reactor can be used at an industrial current density (1000 mA / cm 2 ) under the condition of α-aminobutyric acid, the corresponding ammonia yield was 101.9±7.9nmol / s / cm 2 As shown in Figure 6c, since the reactor is fully solid-state, the generated ammonia is all distributed in the gas phase. The ammonia gas can be absorbed by the dilute hydrochloric acid absorption liquid and quickly prepared into ammonium chloride, which greatly saves the separation and purification costs.

[0063] Figure 7 shows the ammonia yield and corresponding Faradaic efficiency of the all-solid-state ion membrane reactor prepared in Example 1 of the present disclosure at different temperatures. In the range of 350-500°C, as the temperature increases, the reactor yield and Faradaic efficiency also increase.

[0064] FIG8 shows the ammonia yield and the corresponding Faraday efficiency of the all-solid-state ion membrane reactor prepared in Example 1 of the present disclosure at different current densities. 2 -1000mA / cm 2 In the current density range, the ammonia yield increases with the increase of current density, but the Faraday efficiency of the reactor is low at a current density of 100 mA / cm 2 reaches its maximum value when .

[0065] The above are merely preferred embodiments of the present disclosure and are not intended to limit the present disclosure. Although the present disclosure has been described in detail with reference to the aforementioned embodiments, those skilled in the art may still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein with equivalents. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present disclosure shall be included within the scope of protection of the present disclosure.

Claims

1. A all-solid-state lithium-ion membrane reactor with a symmetric structure, the composition structure including a solid-state lithium-ion conductor membrane and a gas diffusion electrode, characterized in that: The gas diffusion electrode is in-situ constructed on both sides of the solid-state lithium-ion conductor membrane; the composition of the solid-state lithium-ion conductor membrane includes a solid-state lithium-ion membrane material, and the solid-state lithium-ion membrane material is one of an inorganic solid-state lithium-ion membrane material and a polymer-based solid-state lithium-ion membrane material; the composition of the gas diffusion electrode includes one or both of Ni and Pt catalysts, and also includes a conductive current collector material.

2. The all-solid-state lithium-ion membrane reactor according to claim 1, characterized in that, The inorganic solid-state lithium-ion membrane material is one of an oxide-type solid-state lithium-ion membrane material, a halide-type solid-state lithium-ion membrane material, and a sulfide-type solid-state lithium-ion membrane material.

3. The all-solid-state lithium-ion membrane reactor according to claim 2, characterized in that, The oxide-type solid-state lithium-ion membrane material is one of lithium lanthanum zirconate garnet and its element-doped compounds, lithium aluminum titanium phosphate NASICON and its element-doped compounds, and lithium lanthanum titanate perovskite and its element-doped compounds.

4. The all-solid-state lithium-ion membrane reactor according to claim 1, characterized in that: The conductive current collector material is one or more of a metal, conductive carbon, and conductive ceramics.

5. The all-solid-state lithium-ion membrane reactor according to claim 2, wherein The preparation method of the gas diffusion electrode includes the following steps: Step 1): Mix NiO powder and the oxide-type solid-state lithium-ion membrane material, and disperse them in a solvent to obtain a suspension; Step 2): Dissolve H2PtCl6 powder in a solvent to obtain an H2PtCl6 solution; Step 3): Coating one or both of the suspension obtained in Step 1 and the H2PtCl6 solution obtained in Step 2 on both sides of the solid-state lithium-ion conductor membrane, and then heating and roasting in a glove box under an argon atmosphere. Ni metal and Pt metal are precipitated on both sides of the solid-state lithium-ion conductor membrane from NiO and H2PtCl6, and finally a solid-state lithium-ion conductor membrane loaded with one or both of Ni and Pt catalysts is obtained; Step 4): Load the conductive current collector material on both sides of the solid-state lithium-ion conductor membrane loaded with one or both of Ni and Pt catalysts obtained in Step 3, so as to form a current collector conductive network structure covering the metal single-catalyst on both sides of the solid-state lithium-ion conductor membrane, that is, gas diffusion electrodes are formed on both sides of the solid-state lithium-ion conductor membrane.

6. The all-solid-state lithium-ion membrane reactor according to claim 5, wherein, In Step 2), the concentration of the H2PtCl6 solution is 0.1 - 50 mol / L.

7. The all-solid-state lithium-ion membrane reactor according to claim 5, wherein In Step 3), the conditions for the heating and roasting are to keep the temperature at 300 - 500 °C for 5 - 20 s.

8. A method for ammonia synthesis, characterized in that, At least include the following steps: Introduce a mixed gas of N2 and H2 into the all-solid-state lithium-ion membrane reactor as described in any one of claims 1 - 7, and energize the gas diffusion electrodes formed on both sides of the solid-state lithium-ion conductor membrane for reaction, that is, synthesize ammonia.

9. The ammonia synthesis method according to claim 8, characterized in that: The temperature of the reaction is 300 - 600 °C.

10. The ammonia synthesis method according to claim 8, wherein: The energized current density of the reaction is 1 - 1000 mA / cm 2 .

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