Enhancement of Electrochemical Properties, Impedance and Resistances of Micro‐tubular IT‐SOFCs with Novel Asymmetric Structure Based on BaZr_0.1Ce_0.7Y_0.1Yb_0.1O_3−δ Proton Conducting Electrolyte

Abstract

Anode‐supported micro‐tubular SOFCs based on a proton and oxide ion mixed conductor electrolyte, BaZr0.1Ce0.7Y0.1Yb0.1O3−δ (BZCYYb), have been successfully fabricated via phase‐inversion process. Typical micro‐tubular cell with the configuration of Ni‐BZCYYb|BZCYYb|La0.6Sr0.4Co0.2Fe0.8O3–δ, consists of anode support, electrolyte and cathode with thicknesses of 200, 12, and 10 μm, respectively. The cells show excellent electrochemical performance with the peak power densities of 1.040, 0.902, 0.721, and 0.590 W cm−2 at 750, 700, 650, and 600 °C, respectively, with humidified (3 vol.% H2O) hydrogen as fuel and ambient air as oxidant. The AC impedance spectroscopy result shows low concentration polarization values of 0.016–0.021 Ω cm2 at 750–600 °C. Further, significant performance enhancement is observed during long‐term stability test at 600 and 750 °C under constant voltage of 0.5 and 0.7 V over 120 h, respectively, indicating excellent stability of BZCYYb under fuel cell operating condition. The high performance is attributed to high‐quality cell, validated by the dense, crack‐free BZCYYb electrolyte film supported by the anode with micro sponge‐like pores.

Manipulating and Optimizing the Hierarchically Porous Electrode Structures for Rapid Mass Transport in Solid Oxide Cells

“…The electrolyte support design is to use the electrolyte as the support structure, with the cathode and anode on both sides of the electrolyte. [ 136 ] The electrode support design is to use the cathode or anode [ 142 ] as support. The electrolyte was then deposited on the porous electrode as a thin electrolyte layer.…”

3D Printing Enabled Highly Scalable Tubular Protonic Ceramic Fuel Cells

“…36−39 Furthermore, during the conventional methods (extrusion, dip coating, and phase inversion) and fused filament fabrication, a high amount of binder (e.g., mass ratios of binder/ceramics are 10−25 wt %) is usually required, which may cause severe deformation issues during the postdrying/ sintering processes. 18,27,29,30,41 In our case, the binder content (e.g., hydroxypropyl methylcellulose) in the paste is only 0.31 wt %, ensuring the feasible viscosity for printing and mitigating the deformation issues. Moreover, to further achieve good shape retainability of the anode and ensure good adhesion between printed layers without requiring high paste viscosity, a CO 2 laser was used for rapid in situ drying of the printed green body after printing each layer of the anode support.…”

“…Therefore, fast startup/shutdown and better thermal cycling stability can be realized . Second, the high-temperature sealing issue can be mitigated by putting the sealing parts outside the high-temperature heating region. , Third, tubular geometry can offer greater mechanical strength than planar geometry with the same thickness so that portable characteristics and higher volumetric power densities can be achieved. , So far, several techniques have been utilized for manufacturing tubular supports of PCFCs, such as extrusion, ,− dip coating, − slip casting, ,− and phase inversion. − …”

“…It can effectively reduce manufacturing costs compared to other 3D printing techniques. In comparison, inkjet printing and aerosol jet printing require ultrafine powders (submicrometer size) and low solid contents to prepare printable low-viscosity inks, leading to an increased cost; digital light processing–stereolithography needs expensive and special photosensitive resin in the slurry as well as lengthy debinding (hours to days). − Furthermore, during the conventional methods (extrusion, dip coating, and phase inversion) and fused filament fabrication, a high amount of binder (e.g., mass ratios of binder/ceramics are 10–25 wt %) is usually required, which may cause severe deformation issues during the postdrying/sintering processes. ,,,, In our case, the binder content (e.g., hydroxypropyl methylcellulose) in the paste is only 0.31 wt %, ensuring the feasible viscosity for printing and mitigating the deformation issues. Moreover, to further achieve good shape retainability of the anode and ensure good adhesion between printed layers without requiring high paste viscosity, a CO 2 laser was used for rapid in situ drying of the printed green body after printing each layer of the anode support.…”

“…Generally, the tubular cell shows high ohmic losses due to the geometrical configuration of the current collectors, which reduces the overall performance . For the as-fabricated single tubular PCFCs, the ASR o values (0.56 Ω cm 2 at 650 °C for the 3.0 cm 2 tube, 0.63 Ω cm 2 at 650 °C for the 12.5 cm 2 tube) are comparable with those prepared by conventional methods (e.g., 0.94 Ω cm 2 at 650 °C for a 2.07 cm 2 tube via extrusion; 0.59 Ω cm 2 at 650 °C for a 1.6 cm 2 tube via slip casting; 0.27 Ω cm 2 at 650 °C for a 1 cm 2 tube via phase inversion, as shown in Table S1), although we used BCZY27 as the electrolyte. Generally, BCZY27 possesses much lower conductivity (∼21 mS/cm under wet oxygen at 650 °C) than BaCe 0.7 Zr 0.1 Y 0.1 Yb 0.1 O 3−δ (BCZYYb) (∼38 to 70 mS/cm under wet oxygen at 650 °C). , However, BCZY27 has far better chemical stability against CO 2 and steam-rich environments.…”