Solid oxide electrolysis cell stack

Abstract

The application discloses a solid oxide electrolysis cell stack, which comprises a cathode current collector plate, an anode current collector plate, a sealing element and repeated units with trace alkali metal corrosion resistance between the cathode current collector plate and the anode current collector plate, wherein the repeated units comprise electrolysis cell sheets, connecting plates, power taking grids 1 and power taking grids 2. The stack is particularly suitable for high-temperature water vapor electrolysis containing trace alkali metal elements.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of fuel cells and electrolytic cells, in particular to a solid oxide electrolysis cell stack. BACKGROUND

[0002] Solid oxide electrolysis cell (SOEC) is a kind of full solid device that can directly convert thermal energy and electrical energy into chemical energy in fuel at medium-high temperature (700-850℃), which can be regarded as the reverse process of solid oxide fuel cell (SOFC). Compared with the low-temperature water electrolysis technology such as alkaline water electrolysis, SOEC high-temperature water vapor electrolysis has the following outstanding technical advantages: (1) SOEC electrical efficiency can reach 100%, and the system efficiency is expected to reach 90%, which is considered as the most efficient water electrolysis hydrogen production technology; (2) SOEC runs at high temperature, and does not need to use noble metal catalyst, mainly using perovskite rare earth oxide catalyst, which has lower material cost; (3) SOEC is a full solid structure, which is more safe and reliable; (4) in the process of chemical industry, metallurgy, steelmaking and other processes that produce high-temperature water vapor and waste heat, SOEC can directly couple with these high-temperature heat sources to produce green hydrogen by electrolysis, which is more helpful for the low-carbon transformation of the industry, and has broad application prospects.

[0003] The water vapor in the industrial industry may contain trace amounts of alkali metal elements and alkaline earth metal elements, and the direct electrolysis of the SOEC stack using the water vapor will enrich on the surface of the traditional nickel-based composite electrode, occupy the active sites, reduce the performance of the electrolytic cell, and may also corrode the connecting plate, resulting in reduced performance of the stack. Therefore, it is necessary to develop an electrolysis stack suitable for water vapor feed containing trace amounts of alkali metals. SUMMARY

[0004] The present application provides a solid oxide electrolysis cell stack, which comprises an anode current collector plate, a cathode current collector plate, a sealing element and a repeating unit between the anode current collector plate and the cathode current collector plate,

[0005] The repeating unit comprises, in sequence, a power extraction grid 1, an electrolytic cell sheet, a power extraction grid 2 and a connecting plate.

[0006] The electrolytic cell sheet comprises, in sequence, an anode, an electrolyte and a cathode, the cathode being a composite cathode composed of an electrocatalyst and an electrolyte, the electrocatalyst being a M-doped Ni-based catalyst, M being one or more of Na, K, Al and Ti; the molar ratio of M to Ni being 20:80-0.01:99.99.

[0007] Two surfaces of the connecting plate are respectively provided with an anode flow channel and a cathode flow channel, the anode flow channel and the cathode flow channel are provided with a protective coating, and the cathode flow channel coating is composed of Ni, Ti, Nd, La and Ce; the coating mass content is 90-99% of Ni, 0.01-1% of Ti, 0.01-5% of Nd, 0.01-2% of La and 0.01-2% of Ce.

[0008] The power taking net 1 is adjacent to the anode of the electrolytic sheet, and the power taking net 2 is adjacent to the cathode of the electrolytic sheet.

[0009] The assembly sequence of the stack is as follows: a cathode current collecting plate, a repeating unit (a power taking net 1, an electrolytic cell sheet, a power taking net 2 and a connecting plate), a sealing member, a repeating unit (a power taking net 1, an electrolytic cell sheet, a power taking net 2 and a connecting plate), an anode current collecting plate, the anode of the electrolytic cell sheet is connected with the anode flow channel of the connecting plate, the cathode of the electrolytic cell sheet is connected with the cathode flow channel of the connecting plate, the connecting plates are connected by the sealing member, and the connecting plates and the anode current collecting plate and the connecting plates and the cathode current collecting plate are connected by laser welding.

[0010] Further, in the above technical solution, the preparation of the composite cathode comprises the following steps:

[0011] The electrolytic cell sheet cathode electrocatalyst is prepared by using a coprecipitation method combined with an impregnation method, a nickel salt solution is added dropwise into a precipitant solution to form a precipitate, the precipitate is washed and dried, and the precipitate is heat treated at 200-450 DEG C in a muffle furnace for 1-10 h to obtain NiO; a mixed aqueous solution of M salt is added dropwise onto the surface of the NiO, and the mixture is dried at 60-90 DEG C in an oven for 10-24 h and then calcined at 200-500 DEG C for 5 h to form a cathode electrocatalyst precursor; the definition of M is the same as above; the cathode electrocatalyst precursor and an electrolyte are mixed as a mixed cathode precursor, and after reduction at 750 DEG C, an electrocatalyst and electrolyte composite cathode is formed; the dosage ratio of the cathode electrocatalyst precursor to the electrolyte is 0.7:0.3-0.4:0.6.

[0012] Further, in the above technical solution, the electrolyte is YSZ.

[0013] Further, in the above technical solution, the precipitant is any one of NH4HCO3, Na2CO3, NaHCO3 and urea.

[0014] Further, in the above technical solution, the preparation method of the cathode flow channel surface protective coating of the connecting plate is a magnetron sputtering method according to element content, the sputtering power is 20-70 Wcm -2 , the sputtering substrate temperature is 100-300 DEG C, and the sputtering time is 2-10 h.

[0015] Further, in the above technical solution, the cathode flow channel surface protective coating thickness of the connecting plate is 0.1-10 microns.

[0016] Further, in the above technical solution, the anode flow channel surface protective coating thickness of the connecting plate is 0.1-10 microns, and the coating is (Mn, Co)3O4.

[0017] Further, in the above technical solution, the repeating unit is at least 1, for example, 2-30, or 4-10.

[0018] Further, in the above technical solution, the cathode current collector plate and the adjacent repeating unit do not contain the connecting plate, the cathode current collector plate is connected with the power grid 2 in the adjacent repeating unit; the anode current collector plate is connected with the power grid 1 in the adjacent repeating unit.

[0019] The advantages of the present application are:

[0020] (1) The cathode electrocatalyst of the electrolytic cell sheet used in the solid oxide electrolysis cell stack of the present application is a M-doped Ni-based catalyst, M is one or several of Na, K, Al, Ti, M can form a nano-heterojunction with Ni, which promotes the adsorption of H2O molecules and reduces the dissociation energy of H2O. At the same time, the electrocatalyst weakens the adsorption and enrichment of alkali metals and alkaline earth metals in the steam on the cathode surface, and improves the resistance of the cathode.

[0021] (2) The cathode flow channel surface of the connecting plate of the solid oxide electrolysis cell stack of the present application is provided with a protective coating, the coating is composed of Ni, Ti, Nd, La, Ce, and the mass content of Ni is not less than 90%, the Nd, La, Ce and other elements promote the densification of the coating at low temperature, and improve the corrosion resistance.

[0022] (3) During long-term electrolysis of water vapor, trace amounts of alkali metals in the water vapor feed may deposit and scale on the cathode flow channel surface of the connecting plate, increasing the water vapor mass transfer resistance and failing to meet the demand of the cathode water vapor dissociation reaction, resulting in reduced performance of the stack. The solid oxide electrolysis cell stack of the present application uses a connecting plate with a coating, which effectively improves the corrosion resistance of the power grid and the connecting plate, ensures the supply of reactants in the cathode electrochemical reaction zone of the electrolytic cell sheet, and improves the performance of the stack.

[0023] (4) The present application sets the cathode catalyst, connecting plate and power grid, so that the stack has the ability to resist trace amounts of alkali metal corrosion, and when it is in contact with high-temperature steam containing trace amounts of alkali metal, it exhibits excellent structural stability, which is due to the cathode catalyst with high dissociation water molecule capacity and the corrosion-resistant coating on the surface of the connecting plate and the power grid.

[0024] (5) The solid oxide electrolysis cell stack is particularly suitable for high-temperature steam direct feeding in the steel industry, avoids the steam condensation purification process, reduces the cost of large-scale hydrogen production, and has a broad application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 The figure is a structural schematic diagram of the solid oxide electrolysis cell stack. DETAILED DESCRIPTION

[0026] The application will be further described below through examples.

[0027] Example 1:

[0028] A solid oxide electrolysis cell stack, as shown in the accompanying Figure 1 , comprises an anode current collector 2, a cathode current collector 1, a sealing element 6, and a repeating unit 3 located between the anode current collector 2 and the cathode current collector 1, wherein the repeating unit comprises, in sequence, an electricity extraction grid 1 7, an electrolysis cell sheet 4, an electricity extraction grid 2 8, and a connecting plate 5; the cathode current collector is provided with a cathode flow channel, and the anode current collector is provided with an anode flow channel; the cathode current collector does not contain a connecting plate with the adjacent repeating unit, and the cathode current collector is connected with the electricity extraction grid 2 8 in the adjacent repeating unit; and the anode current collector is connected with the electricity extraction grid 1 in the adjacent repeating unit.

[0029] The two surfaces of the connecting plate 5 are respectively provided with an anode flow channel and a cathode flow channel, the surface of the cathode flow channel is provided with a 1-micron-thick cathode protective coating 9, the cathode coating is 95wt% Ni, 0.5wt% Ti, 3.5wt% Nd, 0.5wt% La, and 0.5wt% Ce, the cathode coating is prepared by a magnetron sputtering method, the sputtering power is 50Wcm -2 , the sputtering substrate temperature is 150℃, the sputtering time is 3h, and the surface of the anode flow channel is provided with a 1-micron-thick anode protective coating MnCo2O4 10.

[0030] The electricity extraction grid 1 is adjacent to the anode of the electrolysis sheet, the electricity extraction grid 2 is adjacent to the cathode of the electrolysis sheet 4, the electricity extraction grid 1 is a stainless steel 441 grid, and the electricity extraction grid 2 is a Ni grid.

[0031] During the packaging process, the anode of the electrolysis cell sheet is connected with the anode flow channel of the connecting plate, the cathode of the electrolysis cell sheet is connected with the cathode flow channel of the connecting plate, the connecting plates are connected by the sealing element, and the connecting plates and the anode current collector and the connecting plates and the cathode current collector are connected by laser welding;

[0032] The electrolytic cell sheet comprises an anode, an electrolyte and a cathode in sequence, the electrocatalyst of the cathode of the electrolytic cell sheet is 0.2 at% K-0.2% at Na-99.6 at% Ni, the cathode is a composite of the cathode electrocatalyst and YSZ (8 mol% Y2O3 doped ZrO2), the mass fraction of YSZ is 55%, the electrolyte is YSZ, and the anode is La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O3-Gd 0.1 Ce 0.9 O2, and a 0.5-micron isolation layer Gd 0.1 Ce 0.9 O2.

[0033] The cathode electrocatalyst is prepared by a coprecipitation method combined with an impregnation method. 0.996 mol of Ni(NO3)2.6H2O is dissolved in deionized water to form a 0.5 mol / L nickel nitrate solution. A 0.5 M NH4HCO3 solution is used as a precipitant. The nickel nitrate solution is added dropwise to the NH4HCO3 solution to gradually form a precipitate. The precipitate is repeatedly washed by suction filtration for 3 times. The precipitate is dried in an oven (90°C) for 24 h and heat-treated in a muffle furnace at 350°C for 5 h to obtain NiO. 0.002 mol of KNO3 and 0.002 mol of NaNO3 are dissolved in 4 mL of deionized water to form a mixed aqueous solution. The mixed aqueous solution is added dropwise to the surface of the NiO. The mixture is dried in an oven (90°C) for 24 h and then calcined at 300°C for 5 h to form a cathode electrocatalyst precursor. The cathode electrocatalyst precursor is mixed with 0.4 g of a YSZ mixture as a mixed cathode precursor. After reduction at 750°C, a composite cathode of the electrocatalyst (0.2 at% K-0.2% at Na-99.6 at% Ni) and YSZ is formed.

[0034] When the stack is used to electrolyze hydrogen from a simulated water sample (containing 5 wt% Na2CO3), the electrolysis current reaches 53.66 A at a stack temperature of 750°C and a stack electrolysis voltage of 13 V.

[0035] Example 2

[0036] A solid oxide electrolytic cell stack comprises an anode current collector plate, a cathode current collector plate, a sealing element and a repeating unit located between the anode current collector plate and the cathode current collector plate, wherein the repeating unit comprises, in sequence, an electricity extraction net 1, an electrolytic cell sheet, an electricity extraction net 2 and a connecting plate; the cathode current collector plate is provided with a cathode flow channel, and the anode current collector plate is provided with an anode flow channel; the cathode current collector plate does not contain a connecting plate in the adjacent repeating unit, and the cathode current collector plate is connected with the electricity extraction net 2 in the adjacent repeating unit; and the anode current collector plate is connected with the electricity extraction net 1 in the adjacent repeating unit.

[0037] The two surfaces of the connecting plate are respectively provided with anode flow channel and cathode flow channel, the surface of the cathode flow channel is provided with a 1-micron cathode protection coating, the cathode coating is 95wt% Ni, 0.5wt% Ti, 3.5wt% Nd, 0.5wt% La, 0.5wt% Ce, the cathode coating is prepared by magnetron sputtering method, the sputtering power is 50Wcm -2 , the sputtering substrate temperature is 150℃, the sputtering time is 3h, the surface of the anode flow channel is provided with a 1-micron anode protection coating MnCo2O4,

[0038] The power taking net 1 is adjacent to the anode of the electrolytic sheet, the power taking net 2 is adjacent to the cathode of the electrolytic sheet, the power taking net 1 is a stainless steel 441 net, and the power taking net 2 is a Ni net.

[0039] During the packaging process, the anode of the electrolytic cell sheet is connected with the anode flow channel of the connecting plate, the cathode of the electrolytic cell sheet is connected with the cathode flow channel of the connecting plate, the connecting plates are connected by sealing elements, and the connecting plates and the anode current collecting plate and the cathode current collecting plate are connected by laser welding;

[0040] The electrolytic cell sheet comprises an anode, an electrolyte and a cathode in sequence, the electrocatalyst of the cathode of the electrolytic cell sheet is 0.2at% K-0.8at% Na-99at% Ni, the cathode is a composite of the cathode electrocatalyst and YSZ (8mol% Y2O3 doped ZrO2), the electrolyte is YSZ, and the anode is La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O3-Gd 0.1 Ce 0.9 O2, a 0.5-micron isolation layer Gd 0.1 Ce 0.9 O2 is arranged between the cathode and the electrolyte.

[0041] The cathode electrocatalyst is prepared by co-precipitation method combined with impregnation method. 0.99 mol of Ni(NO3)2.6H2O is dissolved in deionized water to form a 0.5 mol / L nickel nitrate solution. A 0.5 M NH4HCO3 solution is used as a precipitant. The nickel nitrate solution is added dropwise to the NH4HCO3 solution to gradually form precipitates. The precipitates are repeatedly washed by suction filtration for 3 times, dried in an oven (90°C) for 24 h, and heat-treated in a muffle furnace at 350°C for 5 h to obtain NiO. 0.002 mol of KNO3 and 0.008 mol of NaNO3 are dissolved in 10 mL of deionized water to form a mixed aqueous solution. The mixed aqueous solution is added dropwise to the surface of the NiO, dried in an oven (90°C) for 24 h, and then calcined at 300°C for 5 h to form a cathode electrocatalyst precursor. The 0.6 g of the cathode electrocatalyst precursor is mixed with 0.4 g of the YSZ mixture as a mixed cathode precursor, and after reduction at 750°C, a composite cathode of the electrocatalyst (0.2 at% K-0.8 at% Na-99 at% Ni) and YSZ is formed.

[0042] When the stack is used to electrolyze hydrogen from a simulated water sample (containing 5 wt% Na2CO3) feed, the electrolysis current reaches 50.05 A at a stack temperature of 750°C and a stack electrolysis voltage of 13 V, and the changes in the content of the elements of the electrocatalyst affect the performance of the stack.

[0043] Example 3:

[0044] A solid oxide electrolysis cell stack includes an anode current collector plate, a cathode current collector plate, a sealing element, and a repeating unit between the anode current collector plate and the cathode current collector plate, wherein the repeating unit includes, in sequence, a power extraction mesh 1, an electrolysis cell sheet, a power extraction mesh 2, and a connecting plate; the cathode current collector plate is provided with a cathode flow channel, and the anode current collector plate is provided with an anode flow channel; the cathode current collector plate does not contain a connecting plate in the adjacent repeating unit, and the cathode current collector plate is connected to the power extraction mesh 2 in the adjacent repeating unit; and the anode current collector plate is connected to the power extraction mesh 1 in the adjacent repeating unit.

[0045] The two surfaces of the connecting plate are respectively provided with an anode flow channel and a cathode flow channel, the surface of the cathode flow channel is provided with a 1-micron-thick cathode protective coating, the cathode coating is composed of 95 wt% Ni, 0.5 wt% Ti, 3.5 wt% Nd, 0.5 wt% La, and 0.5 wt% Ce, the cathode coating is prepared by a magnetron sputtering method, the sputtering power is 50 Wcm -2 , the sputtering substrate temperature is 150°C, the sputtering time is 3 h, the surface of the anode flow channel is provided with a 1-micron-thick anode protective coating MnCo2O4,

[0046] The power extraction mesh 1 is adjacent to the anode of the electrolysis sheet, the power extraction mesh 2 is adjacent to the cathode of the electrolysis sheet, the power extraction mesh 1 is a stainless steel 441 mesh, and the power extraction mesh 2 is a Ni mesh.

[0047] In the packaging process, the anode of the electrolytic cell sheet is connected with the anode flow channel of the connecting plate, the cathode of the electrolytic cell sheet is connected with the cathode flow channel of the connecting plate, the connecting plates are connected by a sealing element, and the connecting plate and the anode collector plate and the connecting plate and the cathode collector plate are connected by laser welding;

[0048] The electrolytic cell sheet comprises an anode, an electrolyte and a cathode in sequence, the electrocatalyst of the cathode of the electrolytic cell sheet is 0.2at% K-0.8% at Al-99at% Ni, the cathode is a composite of the cathode electrocatalyst and YSZ (8mol% Y2O3 doped ZrO2), the electrolyte is YSZ, and the anode is La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O3-Gd 0.1 Ce 0.9 O2, and a 0.5-micron isolation layer Gd 0.1 Ce 0.9 O2.

[0049] The cathode electrocatalyst is prepared by a coprecipitation method combined with an impregnation method. 0.99 mol of Ni(NO3)2.6H2O is dissolved in deionized water to form a 0.5 mol / L nickel nitrate solution, 0.5 M NH4HCO3 solution is used as a precipitant, the nickel nitrate solution is added dropwise into the NH4HCO3 solution to gradually form a precipitate, the precipitate is repeatedly washed by suction filtration for 3 times, dried in an oven (90°C) for 24 h, and heat-treated at 350°C for 5 h in a muffle furnace to obtain NiO. 0.002 mol KNO3 and 0.008 mol Al(NO3)3 are dissolved in 10 mL of deionized water to form a mixed aqueous solution, the mixed aqueous solution is added dropwise to the surface of the NiO, dried in an oven (90°C) for 24 h, and then calcined at 300°C for 5 h to form a cathode electrocatalyst precursor. 0.6 g of the cathode electrocatalyst precursor is mixed with 0.4 g of a YSZ mixture as a mixed cathode precursor, and after reduction at 750°C, a composite cathode of the electrocatalyst (0.2at% K-0.8% at Al-99at% Ni) and YSZ is formed.

[0050] When the stack is used to electrolyze hydrogen-containing simulated water samples (containing 5wt% Na2CO3), the electrolysis current reaches 49.95 A at a stack temperature of 750°C and a stack electrolysis voltage of 13V, and the changes in the content of the elements of the electrocatalyst affect the performance of the stack.

[0051] Example 4:

[0052] A solid oxide electrolysis cell stack comprises an anode current collector plate, a cathode current collector plate, a sealing element and repeating units between the anode current collector plate and the cathode current collector plate, wherein the repeating units comprise, in sequence, an electricity extraction grid 1, an electrolysis cell sheet, an electricity extraction grid 2 and a connecting plate; the cathode current collector plate is provided with a cathode flow channel, and the anode current collector plate is provided with an anode flow channel; the cathode current collector plate does not contain a connecting plate in the adjacent repeating unit, and the cathode current collector plate is connected with the electricity extraction grid 2 in the adjacent repeating unit; and the anode current collector plate is connected with the electricity extraction grid 1 in the adjacent repeating unit.

[0053] An anode flow channel and a cathode flow channel are respectively arranged on two surfaces of the connecting plate, a 1-micron cathode protective coating is arranged on the surface of the cathode flow channel, the cathode coating is 98.5wt% Ni, 0.1wt% Ti, 1.2wt% Nd, 0.1wt% La and 0.1wt% Ce, the cathode coating is prepared by a magnetron sputtering method, the sputtering power is 50Wcm -2 , the sputtering substrate temperature is 150℃, the sputtering time is 3h, an anode protective coating MnCo2O4 of 1 micron is arranged on the surface of the anode flow channel,

[0054] The electricity extraction grid 1 is adjacent to the anode of the electrolysis sheet, the electricity extraction grid 2 is adjacent to the cathode of the electrolysis sheet, the electricity extraction grid 1 is a stainless steel 441 grid, and the electricity extraction grid 2 is a Ni grid.

[0055] During the packaging process, the anode of the electrolysis sheet is connected with the anode flow channel of the connecting plate, the cathode of the electrolysis sheet is connected with the cathode flow channel of the connecting plate, the connecting plates are connected by the sealing element, and the connecting plates and the anode current collector plate and the cathode current collector plate are connected by laser welding;

[0056] The electrolysis sheet comprises, in sequence, an anode, an electrolyte and a cathode, the electrocatalyst of the cathode of the electrolysis sheet is 0.2at% K-0.8at% Na-99at% Ni, the cathode is a composite of the cathode electrocatalyst and YSZ (8mol% Y2O3 doped ZrO2), the electrolyte is YSZ, and the anode is La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O3-Gd 0.1 Ce 0.9 O2, and a 0.5-micron separation layer Gd 0.1 Ce 0.9 O2 is arranged between the cathode and the electrolyte.

[0057] The cathode electrocatalyst is prepared by co-precipitation combined with impregnation method. 0.99 mol of Ni(NO3)2.6H2O is dissolved in deionized water to form a 0.5 mol / L nickel nitrate solution. A 0.5 M NH4HCO3 solution is used as a precipitant. The nickel nitrate solution is added dropwise to the NH4HCO3 solution to gradually form precipitates. The precipitates are repeatedly washed by suction filtration for 3 times, dried in an oven (90°C) for 24 h, and heat-treated in a muffle furnace at 350°C for 5 h to obtain NiO. 0.002 mol of KNO3 and 0.008 mol of NaNO3 are dissolved in 10 mL of deionized water to form a mixed aqueous solution. The mixed aqueous solution is added dropwise to the surface of the NiO, dried in an oven (90°C) for 24 h, and then calcined at 300°C for 5 h to form a cathode electrocatalyst precursor. 0.6 g of the cathode electrocatalyst precursor is mixed with 0.4 g of a YSZ mixture as a mixed cathode precursor, and a composite cathode of the electrocatalyst (0.2 at% K-0.8 at% Na-99 at% Ni) and YSZ is formed after reduction at 750°C.

[0058] When the stack is used to electrolyze hydrogen from a simulated water sample (containing 5 wt% Na2CO3), the electrolysis current reaches 51.23 A at a stack temperature of 750°C and a stack electrolysis voltage of 13 V, and the changes in the content of the elements of the electrocatalyst affect the performance of the stack.

[0059] Comparative Example 1

[0060] A solid oxide electrolysis cell stack includes an anode current collector plate, a cathode current collector plate, a sealing element, and repeating units between the anode current collector plate and the cathode current collector plate. Each repeating unit includes, in order, a power collection mesh 1, an electrolysis cell sheet, a power collection mesh 2, and a connecting plate. The cathode current collector plate is provided with a cathode flow channel, and the anode current collector plate is provided with an anode flow channel. The cathode current collector plate does not contain a connecting plate in the adjacent repeating unit, and the cathode current collector plate is connected to the power collection mesh 2 in the adjacent repeating unit. The anode current collector plate is connected to the power collection mesh 1 in the adjacent repeating unit.

[0061] The two surfaces of the connecting plate are respectively provided with an anode flow channel and a cathode flow channel, and the surface of the anode flow channel is provided with an anode protective coating layer MnCo2O4 of 1 micrometer.

[0062] The power collection mesh 1 is adjacent to the anode of the electrolysis cell sheet, and the power collection mesh 2 is adjacent to the cathode of the electrolysis cell sheet. The power collection mesh 1 is a stainless steel 441 mesh, and the power collection mesh 2 is a Ni mesh.

[0063] During the packaging process, the anode of the electrolysis cell sheet is connected to the anode flow channel of the connecting plate, and the cathode of the electrolysis cell sheet is connected to the cathode flow channel of the connecting plate. The connecting plates are connected by a sealing element, and the connecting plates and the anode current collector plate and the cathode current collector plate are connected by laser welding.

[0064] The electrolytic cell sheet comprises an anode, an electrolyte and a cathode in sequence, the electrocatalyst of the cathode of the electrolytic cell sheet is Ni, the cathode is a composite of the cathode electrocatalyst and YSZ (8 mol% Y2O3 doped ZrO2), the mass fraction of YSZ is 55%, the electrolyte is YSZ, and the anode is La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O3-Gd 0.1 Ce 0.9 O2, a 0.5-micron isolation layer Gd 0.1 Ce 0.9 O2.

[0065] When the hydrogen production electrolysis is carried out by feeding the electrolytic cell stack with a simulated water sample (containing 5 wt% Na2CO3), the electrolysis current reaches 43.72 A at a stack temperature of 750 ℃ and a stack electrolysis voltage of 13 V.

[0066] A solid oxide electrolytic cell stack comprises an anode current collector plate, a cathode current collector plate, a sealing element and repeating units located between the anode current collector plate and the cathode current collector plate, wherein the repeating units comprise, in sequence, an electricity extraction net 1, an electrolytic cell sheet, an electricity extraction net 2 and a connecting plate; the cathode current collector plate is provided with a cathode flow channel, and the anode current collector plate is provided with an anode flow channel; the cathode current collector plate does not contain a connecting plate in the adjacent repeating unit, and the electricity extraction net 2 in the adjacent repeating unit is connected to the cathode current collector plate; and the electricity extraction net 1 in the adjacent repeating unit is connected to the anode current collector plate.

[0067] The two surfaces of the connecting plate are respectively provided with an anode flow channel and a cathode flow channel, the surface of the cathode flow channel is provided with a 1-micron cathode protective coating, the cathode coating is composed of 95 wt% Ni, 0.5 wt% Ti, 3.5 wt% Nd, 0.5 wt% La and 0.5 wt% Ce, the cathode coating is prepared by a magnetron sputtering method, the sputtering power is 50 Wcm -2 , the sputtering substrate temperature is 150 ℃, and the sputtering time is 3 h; and the surface of the anode flow channel is provided with a 1-micron anode protective coating MnCo2O4.

[0068] The electricity extraction net 1 is adjacent to the anode of the electrolytic cell sheet, the electricity extraction net 2 is adjacent to the cathode of the electrolytic cell sheet, the electricity extraction net 1 is a stainless steel 441 net, and the electricity extraction net 2 is a Ni net.

[0069] In the packaging process, the anode of the electrolytic cell sheet is connected to the anode flow channel of the connecting plate, the cathode of the electrolytic cell sheet is connected to the cathode flow channel of the connecting plate, the connecting plates are connected by the sealing element, and the connecting plates and the anode current collector plate and the connecting plates and the cathode current collector plate are connected by laser welding.

[0070] The electrolytic cell sheet comprises an anode, an electrolyte and a cathode in sequence, the electrocatalyst of the cathode of the electrolytic cell sheet is Ni, the cathode is a composite of the cathode electrocatalyst and YSZ (8 mol% Y2O3 doped ZrO2), the mass fraction of YSZ is 55%, the electrolyte is YSZ, the anode is La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O3-Gd 0.1 Ce 0.9 O2, a 0.5-micron isolation layer Gd 0.1 Ce 0.9 O2.

[0071] When the hydrogen production electrolysis is carried out by feeding the electrolysis stack with simulated water sample (containing 5 wt% Na2CO3), the electrolysis current reaches 47.02 A at the electrolysis voltage of 13 V and the stack temperature of 750℃.

[0072] Comparative Example 3:

[0073] A solid oxide electrolytic cell stack comprises an anode current collector plate, a cathode current collector plate, a sealing element and repeating units located between the anode current collector plate and the cathode current collector plate, wherein the repeating units comprise, in sequence, an electricity extraction net 1, an electrolytic cell sheet, an electricity extraction net 2 and a connecting plate; the cathode current collector plate is provided with a cathode flow channel, and the anode current collector plate is provided with an anode flow channel; the cathode current collector plate does not contain the connecting plate in the adjacent repeating unit, and the electricity extraction net 2 in the adjacent repeating unit is connected to the cathode current collector plate; the electricity extraction net 1 in the adjacent repeating unit is connected to the anode current collector plate.

[0074] The two surfaces of the connecting plate are respectively provided with an anode flow channel and a cathode flow channel, the surface of the cathode flow channel is provided with a 1-micron cathode protective coating, the cathode coating is 95 wt% Ni, 0.5 wt% Ti, 3.5 wt% Nd, 0.5 wt% La and 0.5 wt% Ce, the cathode coating is prepared by a magnetron sputtering method, the sputtering power is 50 Wcm -2 , the sputtering substrate temperature is 150℃, the sputtering time is 3h, and the surface of the anode flow channel is provided with a 1-micron anode protective coating MnCo2O4.

[0075] The electricity extraction net 1 is adjacent to the anode of the electrolytic sheet, the electricity extraction net 2 is adjacent to the cathode of the electrolytic sheet, the electricity extraction net 1 is a stainless steel 441 net, and the electricity extraction net 2 is a Ni net.

[0076] During the packaging process, the anode of the electrolytic cell sheet is connected to the anode flow channel of the connecting plate, the cathode of the electrolytic cell sheet is connected to the cathode flow channel of the connecting plate, the connecting plates are connected by the sealing element, and the connecting plates and the anode current collector plate and the connecting plates and the cathode current collector plate are connected by laser welding.

[0077] The electrolytic cell sheet comprises an anode, an electrolyte and a cathode in sequence, the electrocatalyst of the cathode of the electrolytic cell sheet is 0.2at% K-0.2% at Mg-99.6at% Ni, the cathode is a composite of the cathode electrocatalyst and YSZ (8mol% Y2O3 doped ZrO2), the electrolyte is YSZ, and the anode is La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O3-Gd 0.1 Ce 0.9 O2, and a 0.5-micron isolation layer Gd 0.1 Ce 0.9 O2.

[0078] The cathode electrocatalyst is prepared by a coprecipitation method combined with an impregnation method, 0.996 mol of Ni(NO3)2.6H2O is dissolved in deionized water to form a 0.5 mol / L nickel nitrate solution, a 0.5M NH4HCO3 solution is used as a precipitant, the nickel nitrate solution is added dropwise into the NH4HCO3 solution to gradually form a precipitate, the precipitate is repeatedly washed by suction filtration for 3 times, is dried in an oven (90°C) for 24 h, and is heat-treated in a muffle furnace at 350°C for 5 h to obtain NiO. 0.002 mol of KNO3 and 0.002 mol of Mg(NO3)2 are dissolved into 4 mL of deionized water to form a mixed aqueous solution, the mixed aqueous solution is added dropwise onto the surface of the NiO, is dried in an oven (90°C) for 24 h, and is then calcined at 800°C for 5 h to form a cathode electrocatalyst precursor. 0.6 g of the cathode electrocatalyst precursor and 0.4 g of a YSZ mixture are mixed as a mixed cathode precursor, and after reduction at 750°C, a composite cathode of the electrocatalyst (0.2at% K-0.2% at Mg-99.6at% Ni) and YSZ is formed.

[0079] When the stack is used to electrolyze hydrogen from a simulated water sample (containing 5wt% Na2CO3), the electrolysis current reaches 48.76 A at a stack temperature of 750°C and a stack electrolysis voltage of 13 V, and the change in the composition of the electrocatalyst elements causes the performance of the stack to decrease.

[0080] Comparative Example 4:

[0081] A solid oxide electrolytic cell stack comprises an anode current collector plate, a cathode current collector plate, a sealing element and repeating units located between the anode current collector plate and the cathode current collector plate, wherein the repeating units comprise, in sequence, an electricity extraction net 1, an electrolytic cell sheet, an electricity extraction net 2 and a connecting plate; the cathode current collector plate is provided with a cathode flow channel, and the anode current collector plate is provided with an anode flow channel; the cathode current collector plate does not contain a connecting plate in the adjacent repeating unit, and the electricity extraction net 2 in the adjacent repeating unit is connected to the cathode current collector plate; and the electricity extraction net 1 in the adjacent repeating unit is connected to the anode current collector plate.

[0082] The connecting plate has an anode flow channel and a cathode flow channel on its two surfaces, respectively. The cathode flow channel surface is coated with a 1-micron cathode protective coating. The cathode coating consists of 95 wt% Ni, 0.5 wt% Ti, 3.5 wt% Nd, 0.5 wt% La, and 0.5 wt% Ce. The cathode coating is prepared by magnetron sputtering at a sputtering power of 50 W / cm². -2 The sputtering substrate temperature was 150℃, the sputtering time was 3h, and the anode channel surface was coated with a 1-micron anode protective coating of MnCo2O4.

[0083] The wire mesh 1 is adjacent to the anode of the electrolytic cell, and the wire mesh 2 is adjacent to the cathode of the electrolytic cell. Wire mesh 1 is made of stainless steel 441 mesh, and wire mesh 2 is made of Ni mesh.

[0084] During the encapsulation process, the anode of the electrolytic cell sheet is connected to the anode flow channel of the connecting plate, and the cathode of the electrolytic cell sheet is connected to the cathode flow channel of the connecting plate. The connecting plates are connected by a sealing element, and the connecting plate and the anode current collector, as well as the connecting plate and the cathode current collector, are connected by laser welding.

[0085] The electrolytic cell plate sequentially comprises an anode, an electrolyte, and a cathode. The electrocatalyst for the cathode is 1 at% K - 24 at% Mg - 75 at% Ni. The cathode is a composite of the cathode electrocatalyst and YSZ (8 mol% Y₂O₃-doped ZrO₂). The electrolyte is YSZ, and the anode is La. 0.6 Sr 0.4 Co 0.2 Fe 0.8 O3-Gd 0.1 Ce 0.9 O2, with a 0.5-micron isolation layer Gd between the cathode and the electrolyte. 0.1 Ce 0.9 O2.

[0086] The cathode electrocatalyst was prepared by co-precipitation method combined with impregnation method. 0.75 mol of Ni(N03)2.6H20 was dissolved in deionized water to form a 0.5 mol / L nickel nitrate solution. A 0.5 M NH4HCO3 solution was used as a precipitant. The nickel nitrate solution was added dropwise to the NH4HCO3 solution to gradually form precipitates. The precipitates were repeatedly washed by suction filtration for 3 times, dried in an oven (90°C) for 24 h, and heat treated in a muffle furnace at 350°C for 5 h to obtain NiO. 0.01 mol of KNO3 and 0.24 mol of Mg(N03)2 were dissolved in 250 mL of deionized water to form a mixed aqueous solution. The mixed aqueous solution was added dropwise to the surface of the NiO, dried in an oven (90°C) for 24 h, and then calcined at 800°C for 5 h to form a cathode electrocatalyst precursor. 0.6 g of the cathode electrocatalyst precursor and 0.4 g of the YSZ mixture were mixed as a mixed cathode precursor, and after reduction at 750°C, a composite cathode of the electrocatalyst (1 at% K-24% at Mg-75 at% Ni) and YSZ was formed.

[0087] When the stack was used to electrolyze hydrogen from a simulated water sample (containing 5 wt% Na2C03) feed, the electrolysis current reached 22.03 A at a stack temperature of 750°C and a stack electrolysis voltage of 13 V. The change in the composition of the electrocatalyst elements caused a decrease in the performance of the stack.

Claims

1. A solid oxide electrolytic cell stack, characterized in that, Includes an anode current collector, a cathode current collector, a seal, and a repeating unit located between the anode current collector and the cathode current collector; The repeating unit includes, in sequence, a power grid 1, an electrolytic cell plate, a power grid 2, and a connecting plate; The electrolytic cell comprises an anode, an electrolyte, and a cathode. The cathode is a composite cathode composed of an electrocatalyst and an electrolyte. The electrocatalyst is a Ni-based catalyst doped with M, where M is one or more of Na, K, Al, and Ti. The molar ratio of M to Ni is 20:80 to 0.01:99.

99. The electrolyte is YSZ, and the anode is La. 0.6 Sr 0.4 Co 0.2 Fe 0.8 O3-Gd 0.1 Ce 0.9 O2, with a Gd insulating layer between the cathode and the electrolyte. 0.1 Ce 0.9 O2; The connecting plate has an anode flow channel and a cathode flow channel on its two surfaces, respectively. The surfaces of the anode flow channel and the cathode flow channel are covered with a protective coating. The cathode flow channel coating is composed of Ni, Ti, Nd, La and Ce. The mass content of each component of the coating is 90~99% Ni, 0.01~1% Ti, 0.01~5% Nd, 0.01~2% La and 0.01~2% Ce. The power grid 1 is adjacent to the anode of the electrolytic cell plate, and the power grid 2 is adjacent to the cathode of the electrolytic cell plate.

2. The solid oxide electrolytic cell stack according to claim 1, characterized in that, The preparation of the composite cathode includes the following steps: A nickel salt solution is added dropwise to a precipitant solution to form a precipitate. The precipitate is washed and dried, and then heat-treated in a muffle furnace at 200-450°C for 1-10 hours to obtain NiO. A mixed aqueous solution of M salt is added dropwise to the surface of NiO, and dried in an oven at 60-90°C for 10-24 hours, and then calcined at 200-500°C for 5 hours to form a cathode electrocatalytic precursor. The definition of M is the same as in claim 1. A mixture of cathode electrocatalytic precursor and electrolyte is used as a mixed cathode precursor, which is reduced at 750℃ to form a composite cathode of electrocatalyst and electrolyte; the ratio of cathode electrocatalytic precursor to electrolyte is 0.7:0.3~0.4:0.

6.

3. The solid oxide electrolytic cell stack according to claim 2, characterized in that, The precipitant is any one of NH4HCO3, Na2CO3, NaHCO3, and urea.

4. The solid oxide electrolytic cell stack according to claim 1, characterized in that, The protective coating on the cathode flow channel surface of the connecting plate is prepared by magnetron sputtering with a sputtering power of 20~70Wcm. -2 The sputtering substrate temperature is 100~300℃, and the sputtering time is 2~10h.

5. The solid oxide electrolytic cell stack according to claim 1, characterized in that, The thickness of the protective coating on the cathode flow channel surface of the connecting plate is 0.1~10 micrometers.

6. The solid oxide electrolytic cell stack according to claim 1, characterized in that, The protective coating on the anode flow channel surface of the connecting plate has a thickness of 0.1~10 micrometers and is (Mn,Co)3O4.

7. The solid oxide electrolytic cell stack according to claim 1, characterized in that, The minimum number of repeating units is one.

8. The solid oxide electrolytic cell stack according to claim 1, characterized in that, The cathode current collector does not have a connecting plate with the adjacent repeating unit, and the cathode current collector is connected to the power grid 2 in the adjacent repeating unit; the anode current collector is connected to the power grid 1 in the adjacent repeating unit.

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