One-step preparation of large-size 1.5-μm-thick robust YSZ electrolyte for high CH4 conversion SOFCs at 600 °C

Ultrathin electrolytes can lower the operating temperature of yttria-stabilized zirconia (YSZ)-based solid oxide fuel cells (SOFCs) to below 600 °C, accelerating their commercialization. However, current technologies for fabricating robust electrolytes with large areas and a thickness of a few microns for SOFCs suffer from substantial practical limitations, including high manufacturing costs, intricate technical demands, and multistep fabrication processes. This study introduces a low-cost, high-yield, and facile one-step phase inversion technology to fabricate large-area and shape-variable ultrathin YSZ electrolyte-based SOFCs (disc diameter > 12 cm and area of 10 cm × 10 cm). An integrated form of SOFCs with dendritic YSZ microchannels supporting a 1.5-μm-thick dense YSZ thin film was fabricated. The ultrathin electrolyte layer lowered ohmic and polarization losses, enhancing SOFC electrochemical performance. The integrated anode/electrolyte structure overcame the interfacial thermal mismatch, resulting in more than 210 h of long-term stability even with cells operating in rapidly changing environments. The single cell also exhibited a high CH4 conversion efficiency (55 %), which was attributed to the fast gas diffusion and excellent catalytic activity within the integrated anode. In addition, our 4 cm × 4 cm flat SOFCs exhibited a high power output (5.1 W) at 600 °C, paving the way for the mass production of ultrathin and robust YSZ electrolytes.