Strontium lanthanum manganate perovskite oxygen electrode material and solid oxide electrolytic cell sheet, preparation method and application

Abstract

This invention discloses a lanthanum strontium manganate perovskite-type oxygen electrode material, a solid oxide electrolytic cell, its preparation method, and its application. The oxygen electrode material is a cubic perovskite-type oxide, lanthanum strontium manganate, prepared by a molten salt method, with the general chemical formula La. a Sr b MnO 3‑δ Where a+b=1, and δ represents the non-stoichiometric ratio of oxygen in the material. Compared to the irregularly shaped lanthanum strontium manganate prepared by the sol-gel method, the lanthanum strontium manganate disclosed in this invention exhibits better electrochemical methane oxidative coupling performance. Further, by coating and sintering bismuth oxide or yttrium / sammarium co-doped bismuth oxide onto this electrode, a composite electrode can be obtained. This composite electrode can further improve the selectivity of ethane and ethylene and the methane conversion rate. When carbon dioxide is used as the cathode reactant, this electrode and its composite electrode can significantly reduce the electrolysis potential of carbon dioxide electrolysis through coupling the methane oxidative coupling reaction, and are considered to have good application prospects in the field of solid oxide electrolyzers.

Description

Technical Field

[0001] This invention relates to the field of solid oxide batteries and electrolytic cells, specifically to a strontium lanthanum manganate perovskite oxygen electrode material, a solid oxide full electrolytic cell sheet, its preparation method, and its application. Background Technology

[0002] Ethylene, a cornerstone of the global chemical industry, is primarily produced through the steam cracking of naphtha or ethane. However, this traditional process is not only energy-intensive but also generates significant carbon dioxide emissions, exacerbating the challenges of global climate change. With the deepening global exploration of new energy sources and sustainable development pathways, especially the widespread discovery of new natural gas resources, the conversion of methane into high-value-added olefins (such as ethylene) and aromatics has become a new focus for research and industry. This transformation aims to reduce dependence on fossil fuels and explore more environmentally friendly and efficient methods for chemical production.

[0003] Against this backdrop, the electrochemical oxidation of methane (EC-OCM) method within solid oxide electrolyzer (SOEC) technology has opened up a new avenue for the green production of ethylene. This technology utilizes the oxygen ion transfer properties of solid oxide electrolytes, avoiding the energy consumption and emissions associated with directly introducing oxygen in traditional processes. More notably, by coupling the electrochemical carbon dioxide reduction reaction with the methane oxidation process, this technology not only effectively balances the heat input and output during electrolysis but also achieves the conversion of carbon dioxide to carbon monoxide, thus endowing the entire production process with "carbon-negative" characteristics and contributing to the country's carbon neutrality and carbon peaking goals.

[0004] However, currently, only a handful of SOEC electrode materials are suitable for efficient methane oxidative coupling. The extremely low electron affinity, high ionization energy, and low polarizability of methane's C-H bonds make it difficult to activate. Although SOEC replaces oxygen with oxygen ions, improving the oxygen activity on the catalyst surface and thus enhancing methane activation, this often leads to deep oxidation of methane, resulting in low selectivity for ethane and ethylene, and high selectivity for carbon dioxide and carbon monoxide among the reaction products. Commercially available electrode materials commonly used in oxygen evolution reactions include irregularly shaped lanthanum strontium manganate (La). 0.6 Sr 0.4 MnO 3-δ ), Lanthanum strontium cobalt iron oxide (La) 0.8 Sr 0.2 Co 0.8 Fe 0.2 O 3-δ Materials such as [material name] have poor catalytic ability for electrochemical oxidation of methane coupling because they tend to deeply oxidize methane, resulting in undesirable products. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention prepares a cubic perovskite-type strontium lanthanum manganate oxide using a molten salt method, which exhibits better electrochemical methane oxidative coupling performance compared to the irregularly shaped commercial strontium lanthanum manganate prepared by the sol-gel method. The strontium lanthanum manganate perovskite-type oxygen electrode material is then fabricated into an oxygen electrode material. Further, bismuth oxide or yttrium / sammarium co-doped bismuth oxide is coated and sintered onto this electrode to obtain a composite electrode, which can be used as a methane oxidative coupling oxygen electrode in SOEC. This composite electrode can further improve the selectivity of ethane and ethylene and the methane conversion rate. When carbon dioxide is used as the cathode reactant, this electrode and its composite electrode can significantly reduce the electrolysis potential of carbon dioxide electrolysis through coupling the methane oxidative coupling reaction, and are considered to have good application prospects in the field of solid oxide electrolyzers.

[0006] One objective of this invention is to provide a strontium lanthanum manganate perovskite-type oxygen electrode material, with the general chemical formula La. a Sr b MnO 3-δ Where a+b=1, δ represents the non-stoichiometric ratio of oxygen in the material; and the strontium lanthanum manganate perovskite oxygen electrode material has a cubic morphology.

[0007] Wherein, the value of 'a' ranges from 0.5 to 0.9, with a preferred value of 0.6 to 0.8, and further values ​​such as 0.5, 0.55, 0.6, 0.65, 0.67, 0.7, 0.75, 0.8, 0.85, and 0.9. The value of 'b' ranges from 0.1 to 0.5, with a preferred value of 0.2 to 0.4, and further values ​​such as 0.5, 0.45, 0.4, 0.35, 0.33, 0.3, 0.25, 0.2, 0.15, and 0.1.

[0008] In this invention, δ represents the non-stoichiometric ratio of oxygen in the material. Those skilled in the art can determine the value of “δ” through iodine titration experiments. Typically, δ is 0 to 1.

[0009] This invention prepares a cubic strontium lanthanum manganate perovskite-type oxygen electrode material by a molten salt method using a metal nitrate-sodium chloride-potassium chloride system.

[0010] This invention utilizes a molten salt synthesis method to alter the crystal facet exposure ratio of lanthanum strontium manganate, thereby improving its selectivity for products of electrocatalytic methane oxidative coupling.

[0011] The second objective of this invention is to provide a method for preparing the strontium lanthanum manganate perovskite oxygen electrode material, comprising the following steps: mixing lanthanum, strontium and manganese metal nitrates to form a solution, then mixing it with sodium chloride and potassium chloride, drying it, and then performing heating, sintering and holding at the temperature, and cooling to obtain the oxygen electrode material.

[0012] The solution can use water, such as deionized water, as a solvent.

[0013] The total concentration of metal ions in the solution is 0.1–2.5 mol / L, for example, it can be 0.1 mol / L, 0.5 mol / L, 1 mol / L, 1.5 mol / L, 2 mol / L, 2.5 mol / L, etc.

[0014] The ratio of the total amount of sodium chloride and potassium chloride to the total amount of metal in the solution is 1 to 25, preferably 5 to 20, for example, 1, 5, 10, 15, 20, 25, etc.

[0015] The mass ratio of sodium chloride to potassium chloride is 1:(1-5), preferably 1:(1-4), for example, 1:1, 1:2, 1:3, 1:4, 1:5, etc.

[0016] The heating rate is 1–10 °C / min, preferably 1–5 °C / min.

[0017] The sintering holding temperature is 750–900℃, preferably 800–890℃, and can be, for example, 750℃, 780℃, 800℃, 820℃, 840℃, 860℃, 880℃, 890℃, 900℃, etc.

[0018] The heat preservation time is 2 to 10 hours, preferably 3 to 8 hours.

[0019] The cooling rate is 1–10 °C / min, preferably 1–5 °C / min.

[0020] The preparation method may further include the steps of washing and filtering, and then placing the filtered black solid powder in an oven to dry it thoroughly.

[0021] The third objective of this invention is to provide a solid oxide electrolytic cell sheet loaded with the above-described strontium lanthanum manganate perovskite oxygen electrode material or the strontium lanthanum manganate perovskite oxygen electrode material obtained by the above preparation method. Optionally, the solid oxide electrolytic cell sheet is further loaded with bismuth oxide or yttrium and samarium co-doped bismuth oxide.

[0022] When carbon dioxide is used as the cathode reactant, the electrodes and composite electrodes of this solid oxide electrolytic cell can significantly reduce the electrolysis potential of carbon dioxide electrolysis through the coupling reaction of methane oxidation, and are considered to have good application prospects in the field of solid oxide electrolytic cells.

[0023] The fourth objective of this invention is to provide a method for preparing the aforementioned solid oxide electrolytic cell sheet, comprising the following steps:

[0024] (1) Grind the strontium lanthanum manganate perovskite oxygen electrode material;

[0025] (2) Mix the powder obtained in step (1) with the binder to obtain oxygen electrode printing paste;

[0026] (3) Print the oxygen electrode printing paste onto the solid oxide electrolytic cell half, dry it, and repeat 3 to 6 times;

[0027] (4) The solid oxide electrolytic cell sheet is sintered at high temperature.

[0028] Step (1) Optionally, a pore-forming agent is added. Preferably, the pore-forming agent is at least one of starch, graphite, and PMMA powder.

[0029] The amount of the pore-forming agent added is 0-50% of the mass of the strontium lanthanum manganate perovskite oxygen electrode material, preferably 1-25%.

[0030] In step (2), the binder is preferably a mixture of turpentine oil percolate and ethyl cellulose. The ratio of turpentine oil percolate to ethyl cellulose is not particularly limited and can be selected according to actual conditions.

[0031] In step (2), the mass ratio of the powder to the binder is 0.1 to 1.5, preferably 0.5 to 1.

[0032] In step (3), the drying temperature is 65-85℃ and the time is 5-10 min.

[0033] In step (4), the heating rate during sintering is 1-10℃ / min, the sintering holding temperature is 1000-1150℃, the holding time is 2-5h, and the cooling rate is 1-10℃ / min.

[0034] The preparation may further include step (5) coating bismuth oxide or yttrium and samarium co-doped bismuth oxide onto the surface of the strontium lanthanum manganate perovskite oxygen electrode material obtained in step (4) by coating method.

[0035] The beneficial effects of this invention are at least as follows:

[0036] 1. This invention discloses a cubic lanthanum strontium manganate perovskite oxide electrode material prepared by molten salt method and a method for preparing the composite electrode. Compared with the irregular morphology of lanthanum strontium manganate synthesized by sol-gel method, the molten salt method requires a lower temperature and a shorter time in the muffle furnace, thus improving the synthesis efficiency.

[0037] 2. Compared to the irregularly shaped lanthanum strontium manganate synthesized by the sol-gel method, the cubic lanthanum strontium manganate exhibits a more than 8% higher selectivity for the two-carbon products in the electrocatalytic methane oxidation coupling reaction. The electrolysis potential of the full electrolyzer for carbon dioxide electrolysis coupled with methane oxidation is reduced by more than 300 mV, resulting in greater energy savings at the same power output.

[0038] 3. By coating and sintering bismuth oxide or yttrium / sammarium co-doped bismuth oxide as auxiliary catalysts onto a solid oxide electrolytic cell plate supported on a manganese-based perovskite oxide oxygen electrode, a solid oxide electrolytic cell plate with a composite electrode can be further obtained. The electrolysis potential of the electrolytic cell for carbon dioxide coupled with methane oxidation is reduced by more than 700 mV. The selectivity for the two-carbon product of the electrocatalytic methane oxidation coupling reaction is further improved by more than 8%, reaching a selectivity of 71.9%. Attached Figure Description

[0039] Figure 1 The XRD characterization results are for the strontium lanthanum manganate perovskite oxide oxygen electrode materials prepared in Example 1 and Comparative Examples 1-3 of this invention.

[0040] Figure 2 The above are the SEM characterization results of the strontium lanthanum manganate perovskite oxide oxygen electrode materials prepared in Examples 1, 1, 4, 5 and 4 of this invention.

[0041] Figure 2 In the figure, Figure (a) shows the strontium lanthanum manganate perovskite oxygen electrode material obtained in Example 1, Figure (b) shows the strontium lanthanum manganate perovskite oxygen electrode material obtained in Comparative Example 1, Figure (c) shows the strontium lanthanum manganate perovskite oxygen electrode material obtained in Comparative Example 4, Figure (d) shows the strontium lanthanum manganate perovskite oxygen electrode material obtained in Comparative Example 5, and Figure (e) shows the strontium lanthanum manganate perovskite oxygen electrode material obtained in Example 4. Detailed Implementation

[0042] The preferred embodiments of the present invention will now be described in detail with reference to examples. It should be understood that the following embodiments are given for illustrative purposes only and are not intended to limit the scope of the present invention. Those skilled in the art can make various modifications and substitutions to the present invention without departing from its spirit and intent. The technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0043] It should also be noted that the various specific technical features described in the following embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the various possible combinations will not be described separately in this invention.

[0044] Unless otherwise specified, the experimental methods used in the following examples are conventional methods. Unless otherwise specified, the materials and reagents used in the following examples are commercially available or prepared according to conventional methods in the art.

[0045] According to a preferred embodiment of the present invention, the preparation of the strontium lanthanum manganate oxygen electrode material may include the following steps:

[0046] (1) According to the stoichiometric ratios a and b of each metal element in the chemical formula, weigh the corresponding mass of lanthanum (La), strontium (Sr), and manganese (Mn) metal nitrates using an analytical balance or measure the corresponding volume of metal nitrate solution using a pipette.

[0047] (2) Add the metal nitrate or salt solution to a beaker containing a measured amount of deionized water and stir until homogeneous. This solution is referred to as solution A.

[0048] (3) Place a certain amount of sodium chloride and potassium chloride in a mortar and grind them evenly, then transfer them to an alumina crucible.

[0049] (4) Transfer the solution A containing metal nitrate to the crucible described in (3), place the crucible in an oven at 50-80°C for 1-2 hours, and dry the solution.

[0050] (5) Place the crucible in the muffle furnace and heat and cool it according to the set heating curve.

[0051] (6) After cooling to room temperature, use deionized water at 25-85°C to thoroughly wash and filter the solid mixture taken out of the crucible. Then, place the filtered black solid powder in an oven to dry it thoroughly to obtain the strontium lanthanum manganate perovskite oxide oxygen electrode material with a cubic morphology.

[0052] In step (1), the value of a ranges from 0.5 to 0.9, with a preferred value of 0.6 to 0.8, and further values ​​of 0.6, 0.65, 0.67, and 0.7. The value of b ranges from 0.1 to 0.5, with a preferred value of 0.2 to 0.4, and further values ​​of 0.4, 0.35, 0.33, and 0.3.

[0053] In step (2), the amount of deionized water added is such that the total concentration of metal ions is maintained at 0.1 to 2.5 mol / L.

[0054] In step (3), the ratio of the total amount of sodium chloride and potassium chloride to the total amount of metal is 1 to 25, preferably 5 to 20.

[0055] In step (5), the heating rate during the heating process is 1-10℃ / min, preferably 1-5℃ / min, and the temperature is raised to 750-900℃, preferably 800-890℃. The holding time is 2-10h, preferably 3-8h. The cooling rate is 1-10℃ / min, preferably 1-5℃ / min.

[0056] According to a preferred embodiment of the present invention, the process of preparing the obtained strontium lanthanum manganate oxygen electrode material powder into an oxygen electrode and its composite electrode is as follows:

[0057] (1') Take oxygen electrode material powder and optional pore-forming agent, place them in a ball mill jar, add anhydrous ethanol three times the mass of the powder, and then place the ball mill jar in a ball mill for thorough ball milling.

[0058] (2') After ball milling, remove the ball mill jar, dry it in a forced-air drying oven, and then grind the obtained mixed powder evenly with an agate mortar.

[0059] (3') Take the mixed powder, turpentine percolate and ethyl cellulose mixture, place it in an agate mortar and grind and mix evenly to obtain oxygen electrode printing paste.

[0060] (4') The mixed slurry is screen-printed onto the half-cell of the solid oxide electrolytic cell and then dried in an oven.

[0061] (5') Repeat the contents of (4') 3 to 6 times, place the prepared solid oxide electrolytic cell sheet in a muffle furnace for high-temperature sintering, and take it out after sintering to obtain a solid oxide electrolytic cell sheet loaded with manganese-based perovskite oxide oxygen electrode.

[0062] (6') Optionally, two auxiliary catalysts, bismuth oxide or yttrium and samarium co-doped bismuth oxide, can be coated and sintered onto a solid oxide electrolytic cell plate loaded with a manganese-based perovskite oxide oxygen electrode by coating method, to further obtain a solid oxide electrolytic cell plate with a composite electrode.

[0063] The pore-forming agent mentioned in step (1') can be starch, graphite, or PMMA powder. The amount of pore-forming agent added is 0-50% of the mass of the strontium lanthanum manganate perovskite oxygen electrode material powder, preferably 1-25%.

[0064] The preparation method of the mixture of turpentine percolate and ethyl cellulose in step (3') is as follows: take turpentine percolate and ethyl cellulose in a mass ratio of 95:5, stir evenly with a stirring paddle at 60°C, let stand to defoam, and cool to room temperature to obtain the mixture of turpentine percolate and ethyl cellulose.

[0065] The ratio of the mixed powder and the mixture of turpentine percolate and ethyl cellulose mentioned in step (3') is 0.1 to 1.5, preferably 0.5 to 1.

[0066] The solid oxide half-cell described in step (4') can be any commercially available or self-made nickel-YSZ cathode support half-cell coated with yttrium-stabilized zirconium oxide (YSZ) electrolyte, or a YSZ electrolyte support half-cell with nickel oxide-YSZ as the cathode, or a strontium iron molybdate (Sr2Fe) half-cell. 1.5 Mo 0.5 O 6-δ YSZ support or lanthanum-strontium-gallium-magnesium oxide (La) is used as the cathode. 0.8 Sr 0.2 Ga 0.8 Mg 0.2 O 3-δ Electrolyte-supported half-cells, etc.

[0067] The drying temperature in step (4') is 65-85°C and the drying time is 5-10 min.

[0068] In step (5'), the heating rate during the sintering process is 1-10℃ / min, the sintering holding temperature is 1000-1150℃, the holding time is 2-5h, and the cooling rate is 1-10℃ / min.

[0069] The coating and sintering process of the coating method described in step (6') is similar to steps (1') to (5') of the preparation method. The difference is that the oxygen electrode material described in step (1') should be replaced with bismuth oxide or yttrium and samarium co-doped bismuth oxide powder, and the solid oxide electrolytic cell half cell described in step (4') should be replaced with a solid oxide full electrolytic cell sheet loaded with strontium lanthanum perovskite oxide oxygen electrode. Step four is performed only once, and the solid oxide full electrolytic cell sheet loaded with composite electrode described in step (5') is used.

[0070] Example 1

[0071] This embodiment provides a method for preparing a cubical lanthanum strontium manganate perovskite oxide oxygen electrode material using a NaCl-KCl molten salt, the chemical formula of which is La. 0.6 Sr 0.4 MnO 3-δ The method for preparing the corresponding SOEC full electrolytic cell sheet oxygen electrode includes the following steps:

[0072] (1) A method for preparing strontium lanthanum manganate perovskite oxide oxygen electrode material, comprising the following steps:

[0073] According to the chemical formula La 0.6 Sr 0.4MnO 3-δ The stoichiometric ratio of the metal elements is 6:4:10. Weigh out the corresponding masses of lanthanum nitrate hexahydrate, strontium nitrate, and 50wt% manganese nitrate aqueous solution. Add the metal nitrate or salt solution to a beaker containing 100ml of deionized water and stir well. The total molar concentration of the cations is 0.18mol / L.

[0074] 0.09 mol of sodium chloride and 0.09 mol of potassium chloride were ground and mixed evenly in a mortar and then transferred to an alumina crucible. 100 mL of a solution containing metal nitrates was transferred to the crucible containing sodium chloride and potassium chloride. The crucible was placed in an oven at 80°C for 2 hours to dry the solution. The crucible was then placed in a muffle furnace, and heating and cooling were performed according to a pre-defined heating curve. The heating rate was 5°C / min, the sintering holding temperature was 850°C for 5 hours, and the cooling rate was 5°C / min. After cooling to room temperature, the solid mixture removed from the crucible was thoroughly washed and filtered with deionized water at 60°C. The resulting black solid powder was then thoroughly dried in an oven to obtain a cubic strontium lanthanum manganate perovskite-type oxygen electrode material.

[0075] The process of preparing an oxygen electrode from the obtained strontium lanthanum manganate perovskite-type oxygen electrode material powder is as follows:

[0076] (2) Using strontium lanthanum manganate perovskite oxide La 0.6 Sr 0.4 MnO 3-δ Preparation of SOEC total electrolytic cell plate oxygen electrode for oxygen electrode:

[0077] Strontium lanthanum manganate perovskite oxygen electrode material powder and pore-forming agent were mixed at a mass ratio of 5:1 and placed in a ball mill jar. Three times the mass of the powder was added in anhydrous ethanol, and the jar was then placed in a ball mill for thorough ball milling. After ball milling, the jar was removed and dried in a forced-air drying oven. The resulting mixed powder was then ground uniformly using an agate mortar. A mixture of the mixed powder, turpentine peroxide, and ethyl cellulose at a mass ratio of 1:1 was placed in an agate mortar and ground uniformly to obtain the oxygen electrode printing paste. The mixed paste was then screen-printed onto a substrate containing strontium iron molybdate (Sr2Fe). 1.5 Mo 0.5 O 6-δ Lanthanum-strontium-gallium-magnesium oxide (La) cathode 0.8 Sr 0.2 Ga 0.8 Mg 0.2 O 3-δThe solid oxide full electrolytic cell sheet was placed on an electrolyte-supported half-cell and dried in an oven. This process was repeated three times. The prepared solid oxide full electrolytic cell sheet was then placed in a muffle furnace for high-temperature sintering. The heating rate was 5℃ / min, the sintering holding temperature was 1100℃, the holding time was 5h, and the cooling rate was 5℃ / min. After sintering, the solid oxide full electrolytic cell sheet loaded with cubic strontium lanthanum manganate oxygen electrode material was obtained, denoted as sample A.

[0078] Example 2

[0079] The difference from Example 1 is that in this example, the surface of the full electrolytic cell sheet obtained in Example 1, which is loaded with a cubic strontium lanthanum manganate oxygen electrode material, is further coated with a sintered bismuth oxide auxiliary catalyst, thereby obtaining a solid oxide full electrolytic cell sheet with a composite electrode.

[0080] The specific implementation steps are as follows:

[0081] Bismuth oxide powder and a pore-forming agent were mixed at a mass ratio of 5:1 and placed in a ball mill jar. Three times the mass of the powder was added in anhydrous ethanol, and the jar was then placed in a ball mill for thorough ball milling. After ball milling, the jar was removed and dried in a forced-air drying oven. The resulting mixed powder was then ground uniformly using an agate mortar. A mixture of the mixed powder and a solution of turpentine percolate and ethyl cellulose at a mass ratio of 1:1 was ground and mixed uniformly in an agate mortar to obtain an oxygen electrode printing paste. The mixed paste was screen-printed onto a full electrolytic cell sheet loaded with a cubic strontium lanthanum manganate perovskite oxide oxygen electrode material, covered, and dried in an oven. The prepared solid oxide full electrolytic cell sheet was then placed in a muffle furnace for high-temperature sintering at a heating rate of 5℃ / min, a holding temperature of 1100℃ for 5 hours, and a cooling rate of 5℃ / min. After sintering is completed, the sample is removed to obtain a solid oxide electrolytic cell plate loaded with a bismuth oxide-cubic strontium lanthanum manganate composite electrode, denoted as sample B.

[0082] Example 3

[0083] The difference from Example 2 is that, in the fabrication of the composite electrode, a yttrium and samarium co-doped bismuth oxide auxiliary catalyst is coated and sintered onto the surface of the full electrolytic cell sheet loaded with a cubic strontium lanthanum manganate oxygen electrode material, thereby obtaining a solid oxide full electrolytic cell sheet loaded with a yttrium and samarium co-doped bismuth oxide-cubic strontium lanthanum manganate composite electrode, denoted as Sample C.

[0084] Comparative Example 1

[0085] This comparative example provides a method for preparing lanthanum strontium manganate perovskite oxide oxygen electrode material with an irregular morphology via a sol-gel method, the chemical formula of which is La. 0.6 Sr 0.4MnO 3-δ The method for preparing the corresponding SOEC full electrolytic cell sheet oxygen electrode includes the following steps:

[0086] (1) Manganese-based perovskite oxide oxygen electrode material La 0.6 Sr 0.4 MnO 3-δ Preparation:

[0087] According to the chemical formula La 0.6 Sr 0.4 MnO 3-δ The stoichiometric ratio of the metal elements is 6:4:10. Weigh out the corresponding masses of lanthanum nitrate hexahydrate, strontium nitrate, and a 50wt% manganese nitrate aqueous solution. Add the weighed raw materials to a beaker containing 100ml of deionized water, resulting in a total cation concentration of 0.1mol / L. Add citric acid and glucose in equal amounts to the metal cations and stir until homogeneous. Heat to 100℃ and maintain for 1 hour, allowing the solution to gradually thicken into a wet gel. Transfer the beaker to a 180℃ oven and dry and foam for 2 hours, forming a dry gel. Grind the dry gel into powder, place the powder in an alumina or zirconium oxide crucible, and sinter it in a muffle furnace at high temperature. The heating rate is 5℃ / min, the sintering temperature is 1000℃, the holding time is 5 hours, and the cooling rate is 5℃ / min. Grind the sintered product evenly in an agate mortar to obtain manganese-based perovskite oxide electrode material powder.

[0088] (2) Manganese-based perovskite oxide La 0.6 Sr 0.4 MnO 3-δ Preparation of SOEC total electrolytic cell plate oxygen electrode for oxygen electrode:

[0089] Oxygen electrode material powder and pore-forming agent were mixed at a mass ratio of 5:1 and placed in a ball mill jar. Three times the mass of the powder was added in anhydrous ethanol, and the jar was then placed in a ball mill for thorough ball milling. After ball milling, the jar was removed and dried in a forced-air drying oven. The resulting mixed powder was then ground uniformly using an agate mortar. A mixture of the mixed powder, turpentine percolate, and ethyl cellulose at a mass ratio of 1:1 was placed in an agate mortar and ground until uniformly mixed to obtain the oxygen electrode printing paste. The mixed paste was then screen-printed onto a substrate coated with strontium iron molybdate (Sr2Fe). 1.5 Mo 0.5 O 6-δ Lanthanum-strontium-gallium-magnesium oxide (La) is used as the cathode. 0.8 Sr 0.2 Ga 0.8 Mg 0.2 O 3-δThe solid oxide full electrolytic cell sheet was placed on an electrolyte-supported half-cell and dried in an oven. This process was repeated three times. The prepared solid oxide full electrolytic cell sheet was then placed in a muffle furnace for high-temperature sintering. The heating rate was 5℃ / min, the sintering holding temperature was 1100℃, the holding time was 5h, and the cooling rate was 5℃ / min. After sintering, the sample was removed, yielding a solid oxide full electrolytic cell sheet loaded with a strontium lanthanum manganate oxygen electrode with an irregular morphology, denoted as sample D.

[0090] Comparative Example 2

[0091] The difference from Comparative Example 1 is that, in this comparative example, the surface of the strontium lanthanum manganate perovskite oxide oxygen electrode material with irregular morphology loaded on the full electrolytic cell sheet obtained in Comparative Example 1 is further coated with a sintered bismuth oxide auxiliary catalyst, thereby obtaining a solid oxide full electrolytic cell sheet with a composite electrode, denoted as Sample E.

[0092] Comparative Example 3

[0093] The difference from Comparative Example 1 is that, in this comparative example, the surface of the strontium lanthanum manganate perovskite oxide oxygen electrode material with irregular morphology loaded on the full electrolytic cell sheet obtained in Comparative Example 1 is further coated with a sintered yttrium and samarium co-doped bismuth oxide auxiliary catalyst, thereby obtaining a solid oxide full electrolytic cell sheet with a composite electrode, denoted as sample F.

[0094] Comparative Example 4

[0095] This comparative example provides a method for preparing a lanthanum strontium manganate perovskite oxide oxygen electrode material using the sodium nitrite-molten salt method, the chemical formula of which is La. 0.6 Sr 0.4 MnO 3-δ The method for preparing the corresponding SOEC full electrolytic cell sheet oxygen electrode includes the following steps:

[0096] The preparation method of strontium lanthanum manganate perovskite oxide oxygen electrode material includes the following steps:

[0097] According to the chemical formula La 0.6 Sr 0.4 MnO 3-δ The stoichiometric ratio of the metal elements is 6:4:10. Weigh out the corresponding masses of lanthanum nitrate hexahydrate, strontium nitrate, and 50wt% manganese nitrate aqueous solution. Add the metal nitrate or salt solution to a beaker containing 100ml of deionized water and stir well. The total molar concentration of the cations is 0.18mol / L.

[0098] 0.09 mol of sodium nitrite was placed in an alumina crucible. 100 ml of a solution containing metal nitrates was transferred to the sodium nitrite crucible, and the crucible was placed in an oven at 80°C for 2 hours to dry the solution. The crucible was then placed in a muffle furnace, and heating and cooling were performed according to a pre-defined heating curve. The heating rate was 5°C / min, the sintering holding temperature was 850°C for 5 hours, and the cooling rate was 5°C / min. After cooling to room temperature, the solid mixture removed from the crucible was thoroughly washed and filtered with deionized water at 60°C. The resulting black solid powder was then thoroughly dried in an oven to obtain the strontium lanthanum manganate perovskite oxygen electrode material.

[0099] The process of preparing the obtained strontium lanthanum manganate perovskite oxygen electrode material powder into an oxygen electrode is the same as in Example 1 above, and the resulting battery cell is denoted as sample G.

[0100] Comparative Example 5

[0101] This comparative example provides a method for preparing a lanthanum strontium manganate perovskite oxide oxygen electrode material using an oxide-molten salt method, the chemical formula of which is La. 0.6 Sr 0.4 MnO 3-δ The method for preparing the corresponding SOEC full electrolytic cell sheet oxygen electrode includes the following steps:

[0102] The preparation method of strontium lanthanum manganate perovskite oxide oxygen electrode material includes the following steps:

[0103] According to the chemical formula La 0.6 Sr 0.4 MnO 3-δ The stoichiometric ratio of the metal elements in the solution is 6:4:10. Weigh out the corresponding masses of lanthanum oxide, strontium oxide, and manganese trioxide. Simultaneously, take five times the total amount of NaCl and KCl (based on the total amount of metal ions) and grind them thoroughly in a mortar until homogeneous. Transfer the mixture to an alumina crucible. Place the crucible in a muffle furnace and heat and cool according to the set heating curve. The heating rate is 5℃ / min, the sintering holding temperature is 850℃, the holding time is 5h, and the cooling rate is 5℃ / min. After cooling to room temperature, thoroughly wash and filter the solid mixture taken from the crucible with 60℃ deionized water. Then, dry the resulting black solid powder thoroughly in an oven to obtain the lanthanum strontium manganate perovskite oxygen electrode material.

[0104] The process of preparing the obtained strontium lanthanum manganate perovskite oxygen electrode material powder into an oxygen electrode is the same as in Example 1 above, and the resulting battery cell is denoted as sample H.

[0105] Example 4

[0106] This embodiment provides a method for preparing a lanthanum strontium manganate perovskite oxide oxygen electrode material using NaCl-KCl molten salt, the chemical formula of which is La. 0.6 Sr 0.4 MnO 3-δ The method for preparing the corresponding SOEC full electrolytic cell sheet oxygen electrode differs from Example 1 in that the sintering and holding temperature during the synthesis process is 900℃.

[0107] The process of preparing the oxygen electrode from the obtained strontium lanthanum manganate perovskite oxygen electrode material powder is the same as that in Example 1 above, and the resulting battery cell is referred to as Sample I.

[0108] according to Figure 1 It is evident that both the lanthanum strontium manganate synthesized by the molten salt method and the sol-gel method possess a perovskite structure and exhibit good crystallinity. The lanthanum strontium manganate synthesized by the molten salt method shows peak splitting in some diffraction peaks, indicating subtle changes in its internal crystal symmetry or interplanar spacing. Furthermore, changes in the intensity ratio of some peaks suggest alterations in the proportion of its dominant diffraction planes. All these changes affect its morphology.

[0109] according to Figure 2 It can be seen that lanthanum strontium manganate with a cubic morphology was synthesized according to the method described in Example 1, while lanthanum strontium manganate with an irregular morphology was obtained according to the methods described in Comparative Examples 1, 4 and 5.

[0110] Table 1 shows a performance comparison of each embodiment and comparative example in the SOEC carbon dioxide reduction oxygen evolution reaction and coupled methane oxidative coupling reaction.

[0111] Table 1

[0112]

[0113] The performance test conditions in Table 1 are: cathode 20 sccm CO2, anode 20 sccm CH4, and constant current test 100mA.

[0114] Based on Table 1, the following conclusions can be drawn:

[0115] 1. Compared to the irregularly shaped lanthanum strontium manganate, the cubic lanthanum strontium manganate exhibits a 100 mV lower full-cell electrolysis potential during the carbon dioxide electrolytic oxygen evolution reaction. When coupled with the methane oxidative coupling reaction, the overpotential of the cubic lanthanum strontium manganate electrode decreases by nearly 600 mV compared to the oxygen evolution reaction, and by nearly 300 mV compared to the irregularly shaped lanthanum strontium manganate electrode. Furthermore, the cubic lanthanum strontium manganate electrode demonstrates a carbon two-carbon product selectivity exceeding 8% of the control sample, reaching 63.7%.

[0116] 2. By coating bismuth oxide or yttrium and samarium co-doped bismuth oxide onto the surface of lanthanum strontium manganate, the electrode potential of the carbon dioxide electrolytic oxygen reaction and the electrode potential after the coupled methane oxidative coupling reaction can be reduced, indicating that the composite structure has the ability to significantly improve the performance of the electrolyzer.

[0117] 3. The most significant improvement in battery performance was achieved by combining yttrium and samarium co-doped bismuth oxide with cubic strontium lanthanum manganate using a coating method to form a composite electrode. Comparing the electrode before and after composite formation, the electrode potential for the carbon dioxide electrolysis coupled with methane oxidative coupling reaction showed the most significant reduction, with a decrease of nearly 400 mV, and the selectivity for the two-carbon product increased by more than 8%. This indicates that the cubic strontium lanthanum manganate electrode has better compatibility with auxiliary catalysts compared to the random strontium lanthanum manganate electrode.

[0118] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A lanthanum strontium manganate perovskite oxygen electrode material, with the general chemical formula La. a Sr b MnO 3-δ , where a+b=1, and δ represents the non-stoichiometric ratio of oxygen in the material; the strontium lanthanum manganate perovskite oxygen electrode material has a cubic morphology.

2. The strontium lanthanum manganate perovskite oxygen electrode material according to claim 1, characterized in that: The value of a ranges from 0.5 to 0.9, preferably from 0.6 to 0.8; the value of b ranges from 0.1 to 0.5, preferably from 0.2 to 0.

4.

3. A method for preparing the strontium lanthanum manganate perovskite oxygen electrode material according to claim 1 or 2, comprising the following steps: The oxygen electrode material is obtained by mixing lanthanum, strontium and manganese metal nitrates to form a solution, then mixing it with sodium chloride and potassium chloride, drying it, and then heating, sintering and holding at the temperature, and cooling.

4. The method for preparing the electrode material according to claim 3, characterized in that: The total concentration of metal ions in the solution is 0.1–2.5 mol / L; and / or, The ratio of the total amount of sodium chloride and potassium chloride to the total amount of metal in the solution is 1–25, preferably 5–20; and / or, The mass ratio of sodium chloride to potassium chloride is 1:(1-5), preferably 1:(1-4).

5. The method for preparing the electrode material according to claim 3, characterized in that: The heating rate is 1–10 °C / min, preferably 1–5 °C / min; and / or, The sintering holding temperature is 750–900℃, preferably 800–890℃; the holding time is 2–10 h, preferably 3–8 h; and / or, The cooling rate is 1–10 °C / min, preferably 1–5 °C / min.

6. A solid oxide electrolytic cell sheet, loaded with the strontium lanthanum manganate perovskite oxygen electrode material according to claim 1 or 2, or the strontium lanthanum manganate perovskite oxygen electrode material obtained by any one of claims 3 to 5, wherein optionally the solid oxide electrolytic cell sheet is further loaded with bismuth oxide or yttrium and samarium co-doped bismuth oxide.

7. The method for preparing the solid oxide electrolytic cell sheet according to claim 6, comprising the following steps: (1) Grind the strontium lanthanum manganate perovskite oxygen electrode material; (2) Mix the powder obtained in step (1) with the binder to obtain oxygen electrode printing paste; (3) Print the oxygen electrode printing paste onto the solid oxide electrolytic cell sheet, dry it, and repeat 3 to 6 times; (4) The solid oxide electrolytic cell sheet is sintered at high temperature.

8. The method for preparing the solid oxide electrolytic cell sheet according to claim 7, characterized in that: In step (1), a pore-forming agent is optionally added. Preferably, the pore-forming agent is at least one of starch, graphite, and PMMA powder. The amount of the pore-forming agent added is 0-50% of the mass of the strontium lanthanum manganate perovskite oxygen electrode material, preferably 1-25%. The binder mentioned in step (2) is a mixture of turpentine oil percolate and ethyl cellulose; and / or, The mass ratio of powder to binder in step (2) is 0.1 to 1.5, preferably 0.5 to 1; and / or, In step (3), the drying temperature is 65–85°C, and the time is 5–10 min; and / or, In step (4), the heating rate during sintering is 1-10℃ / min, the sintering holding temperature is 1000-1150℃, the holding time is 2-5h, and the cooling rate is 1-10℃ / min.

9. The method for preparing the solid oxide electrolytic cell sheet according to claim 7 or 8, characterized in that... include: (5) Bismuth oxide or yttrium and samarium co-doped bismuth oxide is coated and sintered onto a solid oxide electrolytic cell sheet by coating method.

10. The application of the solid oxide electrolytic cell sheet according to claim 6 or the solid oxide electrolytic cell sheet obtained by any one of claims 7 to 9 in the production of ethylene and ethane from carbon dioxide oxidized methane.

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