A method for simultaneously characterizing the stability of PCCs oxygen electrodes in both battery and electrolysis modes

Abstract

The application is a method for simultaneously representing the stability of PCCs oxygen electrode in battery and electrolysis mode, which adopts solid-phase three-electrode structure, places the solid-phase three-electrode structure in a high-temperature tube furnace, heats to the test temperature, introduces the test gas, first tests the initial EIS of the oxygen electrode on both sides of the solid-phase three-electrode by using an electrochemical workstation, then applies a certain polarization current or voltage to the solid-phase three-electrode structure, pauses the polarization current or polarization voltage after a period of polarization, waits for the oxygen electrode to recover to steady state, then tests the EIS of the oxygen electrode on both sides by using the electrochemical workstation, continues to apply the current or voltage after the test is completed, repeats the above operation steps until the required time of the stability test is reached, and thus the decay rate of the oxygen electrode in the battery mode and the electrolysis mode is tested. The application can accurately measure the stability of the PCCs oxygen electrode under the polarization current in the battery and electrolysis mode.

Description

Technical Field

[0001] This invention belongs to the field of solid oxide battery technology, specifically a method for simultaneously characterizing the stability of PCCs oxygen electrodes in both battery and electrolysis modes. Background Technology

[0002] Solid oxide batteries (SOCs) are highly efficient energy conversion devices that can convert the chemical energy of fuels such as hydrogen, methanol, and methane into electrical energy, and can also utilize renewable energy sources to produce hydrogen or syngas. They offer advantages such as not using precious metal catalysts, strong fuel adaptability, and an all-ceramic structure. SOCs consist of a porous hydrogen electrode, a dense electrolyte, and a porous oxygen electrode. Based on the type of charge carriers in the electrolyte, they can be classified into O… 2- Conductive solid oxide batteries (O-SOCs) and H + Conductive proton ceramic cells (PCCs). Due to the small ionic radius of protons and the low activation energy for transport (0.44-0.6 eV), protons can operate at medium and low temperatures (400-650℃). This not only makes them system-friendly and reduces operating costs, but also slows down interfacial reactions. Therefore, PCCs have good development prospects and application advantages.

[0003] Since the oxygen electrode significantly influences the polarization resistance of the battery, its stability determines the stability of PCCs (Polymerized Carbon Cells). During operation, the oxygen electrode of a PCC is constantly polarized. During power generation, it is cathodically polarized, undergoing reduction reactions; during electrolysis, it is anoly polarized, undergoing oxidation reactions. Under operating conditions, the oxygen electrode of a PCC exchanges substances with the external environment, and its surface is dynamic and constantly changing. Therefore, polarization has a significant impact on the microstructure and compositional stability of the oxygen electrode, and this impact differs between battery mode and electrolysis mode.

[0004] Currently, full-cell structures are generally used to study their stability under polarization, but the influence of polarization current on this stability is lacking. Because a full cell contains an oxygen electrode, an electrolyte, and a hydrogen electrode, the effects of electrolyte and hydrogen electrode decay cannot be eliminated, and there is currently a lack of accurate methods to measure the stability of the oxygen electrode under polarization current. Summary of the Invention

[0005] The purpose of this invention is to provide a method for simultaneously characterizing the stability of PCCs oxygen electrodes in both battery and electrolysis modes. This method can accurately measure the stability of PCCs oxygen electrodes under polarization current in both battery and electrolysis modes.

[0006] As a further aspect of the present invention, a method for simultaneously characterizing the stability of PCCs oxygen electrodes in battery and electrolysis modes includes the following steps: a solid-state three-electrode structure is used, the solid-state three-electrode structure is placed in a high-temperature tube furnace, heated to the test temperature, and a test gas is introduced. First, the initial EIS of the oxygen electrodes on both sides of the solid-state three-electrode structure is tested using an electrochemical workstation. Then, a certain polarization current or polarization voltage is applied to the solid-state three-electrode structure. After polarization for a period of time, the polarization current or voltage is paused, and the oxygen electrodes are allowed to return to a steady state. Then, the EIS of the oxygen electrodes on both sides is tested again using an electrochemical workstation. After the test, the current or voltage is applied again, and the above operation steps are repeated until the time required for the stability test is reached. Thus, the decay rate of the oxygen electrode in battery and electrolysis modes is tested.

[0007] As a further aspect of the present invention: the solid-phase three-electrode structure includes a working electrode, a counter electrode, and a reference electrode disposed on a circular electrolyte sheet. The working electrode and the counter electrode are symmetrically disposed on the upper and lower sides of the electrolyte sheet, including two disposal methods. One method is to place the working electrode and the counter electrode at the center of the electrolyte sheet, in which case the reference electrode is disposed along the entire circumference of the outer surface of the electrolyte sheet and located at the center line of the outer circumference. The other method is to place the working electrode and the counter electrode on the upper and lower sides of the electrolyte sheet near the edge, respectively, and to place the reference electrode opposite to it, with the reference electrode covering part of the upper and lower sides and the side edges of the electrolyte sheet.

[0008] As a further aspect of the present invention: the electrolyte sheet is composed of an electrolyte, with sintered dense BaZrO 3-δ The base circular sheet is the electrolyte, with a diameter of 16-25 mm and a thickness of approximately 0.5-3 mm.

[0009] As a further aspect of the present invention: the working electrode and the counter electrode are sintered on both sides of the electrolyte sheet as oxygen electrodes for testing, with a diameter of 6-16 mm.

[0010] As a further aspect of the present invention: the reference electrode is one of Ag, Au, Pt, or Pd materials with a stable potential, and the distance between the side of the reference electrode close to the working electrode and the working electrode is d, where d is more than three times the thickness of the electrolyte sheet.

[0011] As a further aspect of the present invention, the test temperature in the high-temperature tubular furnace is 450-700℃.

[0012] As a further aspect of the present invention: the polarization current density is 0-2 Acm. -2 Polarization voltage 0-3V.

[0013] As a further aspect of the present invention: the test gas contains two to four of the following: oxygen, nitrogen, water vapor, and carbon dioxide atmosphere; air or simulated air containing 0-100% water and 0-100% carbon dioxide, wherein N2:O2 is 80%:20%; and a mixture of oxygen and nitrogen, with a gas flow rate of 30-100 sccm.

[0014] As a further aspect of the present invention: BaZrO 3-δ The base is BaZr 0.8 Y 0.2 O 3-δ .

[0015] Compared with existing technologies, this invention places a solid-state three-electrode structure in a high-temperature tube furnace, heats it to the test temperature, introduces a test gas, and uses an electrochemical workstation to test the EIS of the oxygen electrode on both sides of the solid-state three-electrode structure. This allows for the determination of the oxygen electrode's degradation rate in both battery and electrolysis modes. This invention can directly and accurately measure the oxygen electrode's degradation rate in both battery and electrolysis modes, and can further test the degradation rate under different operating conditions by changing the polarization current density / polarization voltage, test temperature, and atmosphere. Attached Figure Description

[0016] Figure 1 (a) is a top view of the working electrode or counter electrode of the solid-phase three-electrode system in this invention located at the center of the electrolyte sheet, and (b) is a front view of (a).

[0017] Figure 2 (a) is a top view of the working electrode or counter electrode of the solid-phase three-electrode system in this invention located on one side of the electrolyte sheet, and (b) is a front view of (a).

[0018] Figure 3 This is a schematic diagram illustrating the stability of the oxygen electrode during polarization testing in this invention.

[0019] Figure 4 This is a graph showing the attenuation rate of the BCFZY oxygen electrode under different polarizations in Example 1.

[0020] Figure 5 In Example 2, the BCFZY oxygen electrode is used at a polarization current density of 500 mA / cm². -2 Attenuation rate diagrams under different polarizations. Detailed Implementation

[0021] The invention will now be further described with reference to the accompanying drawings.

[0022] A solid-phase three-electrode structure is adopted, in which a working electrode, a counter electrode, and a reference electrode are set on a circular electrolyte sheet. The working electrode and the counter electrode are symmetrically arranged on both sides of the electrolyte sheet, including two arrangement methods. One method is to place the working electrode and the counter electrode at the center of the electrolyte sheet, such as... Figure 1 As shown in (a) and (b), in this case, the reference electrode is arranged along the entire circumference of the outer surface of the electrolyte sheet and is located at the center line of the outer circumference. The height of the reference electrode is less than the thickness of the electrolyte sheet; another arrangement is as follows... Figure 2 As shown in (a) and (b), the working electrode and the counter electrode are respectively set on one side of the electrolyte sheet, and the reference electrode is set on the other side. The reference electrode covers part of the upper and lower sides and the side edges of the electrolyte sheet.

[0023] Electrolyte sheets are composed of electrolytes, with sintered dense BaZrO₂. 3-δ The base circular sheet is the electrolyte. Electrolytes can be doped with elements. Experiments have shown that electrolytes containing Ce undergo a phase transition and are unstable under polarization current. Therefore, the electrolyte in this invention does not contain Ce and is a proton-conducting material, a densely sintered circular sheet. Both the working electrode and the counter electrode are oxygen electrode materials whose stability under polarization needs to be tested. The surfaces of both the working electrode and the counter electrode are coated with silver-palladium paste to collect electrons. The reference electrode is one of Ag, Au, Pt, or Pd, a material with a stable potential, coated on the entire circumference of the electrolyte sheet's outer surface, or coated on one side of the electrolyte sheet, such as... Figure 1 , Figure 1 As shown, the distance d between the reference electrode and the working electrode on the side closest to the working electrode is greater than three times the thickness of the electrolyte sheet. The solid-state three-electrode structure is placed in a high-temperature tube furnace and heated to the test temperature. A test gas containing three or four of the following atmospheres—oxygen, nitrogen, water vapor, and carbon dioxide—is introduced. First, the initial EIS of the oxygen electrodes on both sides is tested using an electrochemical workstation. Then, a certain DC current or voltage is applied to the three-electrode structure, such as... Figure 3 As shown, after polarization for a period of time, the polarization current or voltage is paused, and the oxygen electrode is allowed to return to a steady state. Then, the EIS of both oxygen electrodes is tested using an electrochemical workstation. After the test, the current or voltage is applied again, and the above steps are repeated until the time required for the stability test is reached. The oxygen electrode of PCECs is the oxygen electrode in electrolysis mode, while the oxygen electrode of PCFCs is the oxygen electrode in battery mode; both belong to the PCCs oxygen electrode category. However, their polarization differs during operation: in PCECs mode, the oxygen electrode is anoly polarized, while in PCFCs mode, the oxygen electrode is catholy polarized.

[0024] The following examples use BaZrO 3-δ The base is BaZr 0.8 Y 0.2 O3-δ The working electrode or counter electrode is BaCo. 0.4 Fe 0.4 Zr 0.1 Y 0.1 O 3-δ or PrBa 1.5 Sr 0.5 Co 1.5 Fe 0.5 O 6-δ This method was used as an oxygen electrode to verify the feasibility of the method of the present invention, but other oxygen electrodes suitable for proton ceramic batteries can also be tested using this method.

[0025] Example 1: BaZr 0.8 Y 0.2 O 3-δ (BZY82) Electrolyte powder and 2% PVB binder are mixed evenly, and 1% NiO is added as a sintering aid. 1g of the mixed powder is pressed into a circular blank with a diameter of 20mm and sintered at 1480℃ for 5h to obtain an electrolyte sheet with a three-electrode structure. The thickness of the electrolyte sheet is 0.8mm. BaCo 0.4 Fe 0.4 Zr 0.1 Y 0.1 O 3-δ (BCFZY) slurry is coated onto the center of the electrolyte as the working electrode or counter electrode, with an electrode diameter of 6 mm. It is sintered at 950℃ for 3 hours. Ag is coated onto the side of the BZY82 electrolyte as a reference electrode. Figure 1 As shown. The three-electrode structure was placed in a high-temperature furnace, heated to 600℃ and held at that temperature, and a N2 and O2 mixture containing 30% water was introduced at 50 sccm, with an N2:O2 ratio of 80%:20%, and a polarization current density of 200 mA / cm. -2 ,like Figure 3 As shown, the BCFZY oxygen electrode exhibits a decay rate of 0.313 Ωcm in cell mode FC. 2 The decay rate under 100h and electrolytic mode (EC) is 0.232 Ωcm. 2 / 100h. (e.g., ...) Figure 4 As shown.

[0026] Example 2: BaZr 0.8 Y 0.2 O 3-δ (BZY82) Electrolyte powder and 2% PVB binder were mixed evenly, and 1% NiO was added as a sintering aid. 1g of the mixed powder was pressed into a 20mm diameter circular blank and sintered at 1480℃ for 5 hours to obtain an electrolyte sheet with a three-electrode structure and a thickness of 0.8mm. BaCo 0.4 Fe 0.4 Zr 0.1 Y 0.1 O3-δ (BCFZY) slurry is coated onto the center of the electrolyte as the working electrode and counter electrode, with an electrode diameter of 6 mm. It is sintered at 950℃ for 3 hours. Ag is coated onto the side of the BZY82 electrolyte as the reference electrode. Figure 1 As shown. The three-electrode structure was placed in a high-temperature furnace, heated to 600℃ and held thereafter. A mixture of N2 and O2 containing 30% water was introduced at 50 sccm, with an N2:O2 ratio of 80%:20%. The polarization current density was 500 mA / cm. -2 The BCFZY oxygen electrode was tested to have a decay rate of 0.354 Ωcm in cell mode (FC). 2 The decay rate was 0.203 Ωcm under 100h and electrolytic modes. 2 / 100h, such as Figure 5 As shown.

[0027] Example 3: BaZr 0.8 Y 0.2 O 3-δ (BZY82) Electrolyte powder and 2% PVB binder were mixed evenly, and 1% NiO was added as a sintering aid. 1g of the mixed powder was pressed into a circular blank with a diameter of 20mm, and sintered at 1480℃ for 5h to a thickness of 0.8mm, serving as an electrolyte sheet with a three-electrode structure. BaCo 0.4 Fe 0.4 Zr 0.1 Y 0.1 O 3-δ (BCFZY) slurry is coated on both sides of the electrolyte as the working electrode and counter electrode, with an electrode diameter of 6 mm. It is sintered at 950℃ for 3 hours. Ag is coated on the side of the BZY82 electrolyte as the reference electrode. Figure 2 As shown. The three-electrode structure was placed in a high-temperature furnace, heated to 600℃ and held at that temperature, and a N2 and O2 mixture containing 30% water was introduced at 50 sccm, with an N2:O2 ratio of 80%:20%, and a polarization current density of 200 mA / cm. -2 The degradation rate of the BCFZY oxygen electrode was tested in both battery and electrolysis modes.

[0028] Example 4: BaZr 0.8 Y 0.2 O 3-δ (BZY82) Electrolyte powder and 2% PVB binder were mixed evenly, and 1% NiO was added as a sintering aid. 3g of the mixed powder was pressed into a circular blank with a diameter of 20mm and sintered at 1480℃ for 5h to obtain an electrolyte sheet with a three-electrode structure and a thickness of 2.5mm. PrBa 1.5 Sr 0.5 Co 1.5 Fe 0.5 O 6-δ(PBSCF) slurry was coated on both sides of the electrolyte as the working electrode and counter electrode, with an electrode diameter of 6 mm. It was sintered at 950℃ for 3 hours. Ag was coated on the side of the BZY82 electrolyte as the reference electrode. Figure 2 As shown. The three-electrode structure was placed in a high-temperature furnace, heated to 600℃ and held thereafter, and a N2 and O2 mixture containing 5% CO2 was introduced at 100 sccm, with an N2:O2 ratio of 80%:20%, and a polarization current density of 200 mA / cm. -2 The decay rate of the PBSCF oxygen electrode was tested in both battery and electrolysis modes.

[0029] Example 5: BaZr 0.8 Y 0.2 O 3-δ (BZY82) Electrolyte powder and 2% PVB binder were mixed evenly, and 1% NiO was added as a sintering aid. 0.8g of the mixed powder was pressed into a 20mm diameter circular blank and sintered at 1480℃ for 5 hours to form a 0.5mm thick electrolyte sheet with a three-electrode structure. 1.5 Sr 0.5 Co 1.5 Fe 0.5 O 6-δ (PBSCF) slurry was coated onto the center of the electrolyte as the working and counter electrodes, with an electrode diameter of 6 mm. The electrolyte was sintered at 950℃ for 3 hours. Ag was coated onto the side of the BZY82 electrolyte as the reference electrode. Figure 1 As shown. The three-electrode structure was placed in a high-temperature furnace, heated to 600℃ and held at that temperature, and a mixture of N2 and O2 containing 5% CO2 and 10% water was introduced at 30 sccm, with the N2:O2 ratio being 80%:20% and the polarization voltage being 1.5V. The decay rate of the PBSCF oxygen electrode was tested in both battery mode and electrolysis mode.

Claims

1. A method for simultaneously characterizing the stability of PCCs oxygen electrodes in both battery and electrolysis modes, characterized in that, The process includes the following steps: using a solid-state three-electrode structure, the solid-state three-electrode structure is placed in a high-temperature tube furnace and heated to the test temperature. Test gas is introduced. First, the initial EIS of the oxygen electrodes on both sides of the solid-state three-electrode structure is tested using an electrochemical workstation. Then, a certain polarization current or voltage is applied to the solid-state three-electrode structure. After polarization for a period of time, the polarization current or voltage is paused, and the oxygen electrodes are allowed to return to a steady state. The EIS of the oxygen electrodes on both sides is then tested again using an electrochemical workstation. After the test, the current or voltage is applied again, and the above operation steps are repeated until the time required for the stability test is reached. This allows the degradation rate of the oxygen electrode in battery mode and electrolysis mode to be tested. The solid-phase three-electrode structure includes a working electrode, a counter electrode, and a reference electrode disposed on a circular electrolyte sheet. The working electrode and the counter electrode are symmetrically disposed on the upper and lower sides of the electrolyte sheet, respectively. There are two disposal methods: one is to place the working electrode and the counter electrode at the center of the electrolyte sheet, in which case the reference electrode is disposed along the entire circumference of the outer surface of the electrolyte sheet and located at the center line of the outer circumference; the other disposal method is to place the working electrode and the counter electrode on the upper and lower sides of the electrolyte sheet near the edge, respectively, and the reference electrode is disposed opposite to each other, with the reference electrode covering part of the upper and lower sides and the side edges of the electrolyte sheet. The electrolyte sheet is composed of an electrolyte, with sintered dense BaZrO 3-δ The base circular sheet is the electrolyte, which does not contain Ce and is a proton-conducting material. The working electrode and the counter electrode are both oxygen electrode materials whose stability under polarization needs to be tested. The surfaces of the working electrode and the counter electrode are coated with silver-palladium paste for current collection. The electrolyte sheet has a diameter of 16-25 mm and a thickness of 0.5-3 mm. The reference electrode is a material with a stable potential, such as Ag, Au, Pt, or Pd. The distance between the side of the reference electrode closest to the working electrode and the working electrode is d, and d is more than three times the thickness of the electrolyte sheet.

2. The method for simultaneously characterizing the stability of PCCs oxygen electrodes in battery and electrolysis modes according to claim 1, characterized in that, The working electrode and the counter electrode are sintered on both sides of the electrolyte sheet as oxygen electrodes for testing, with a diameter of 6-16 mm.

3. The method for simultaneously characterizing the stability of PCCs oxygen electrodes in battery and electrolysis modes according to claim 1, characterized in that, The test temperature in the high-temperature tubular furnace is 450-700℃.

4. The method for simultaneously characterizing the stability of PCCs oxygen electrodes in battery and electrolysis modes according to claim 1, characterized in that, The polarization voltage is 1.5V.

5. The method for simultaneously characterizing the stability of PCCs oxygen electrodes in battery and electrolysis modes according to claim 1, characterized in that, The test gas contains three or four of the following: oxygen, nitrogen, water vapor, and carbon dioxide, and the gas flow rate is 30-100 sccm.

6. The method for simultaneously characterizing the stability of PCCs oxygen electrodes in battery and electrolysis modes according to claim 1, characterized in that, BaZrO 3-δ Basic BaZr 0.8 Y 0.2 O 3-δ .

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