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Underground coal gasification (UCG) technology can directly convert coal resources to syngas underground, making it important for coal utilization. In this work, the power generation, CO 2 electrolysis, and reversible operation of flat-tube solid oxide cells (SOCs) fueled with UCG syngas were studied. The factors affecting the performances of flat-tube solid oxide cells were investigated. Fueled with syngas (Swan Hills, Canada) at 750 °C, the flat-tube cell achieved a maximum power density of 329.4 mW cm−2 and a current density of 650.8 mA cm−2 at 1.4 V. 100-cycle (250 h) reversible operation of flat-tube SOCs running on syngas (Swan Hills) was accomplished. No carbon deposition on the surfaces of the cell fuel channels was detected. The syngas conversion in flat-tube cells was illuminated based on density functional theory calculations. • The performance of solid oxide cells (SOCs) with syngas was studied. • 100-cycle reversible operation of SOCs with UCG syngas was achieved. • No coking was detected after the long-term reversible test. • DFT calculations illustrated the reaction mechanisms of UCG syngas in SOCs. [ABSTRACT FROM AUTHOR]

BaCe 0.7 Zr 0.1 Y 0.1 Yb 0.1 O 3-δ (BCZYYb) is one of the most popular electrolyte materials in proton ceramic fuel cells (PCFCs). The synthesizing method and properties of BCZYYb powders have a significant impact on the sintering activity of electrolyte materials. In this work, the BCZYYb electrolyte was synthesized by ammonium bicarbonate co-precipitation method (CPT), and was compared with the powder produced by solid-state reaction (SSR) and sol-gel (SG) methods. XRD results show the BCZYYb powder synthesized by the CPT method belongs to orthorhombic crystal system with a space group of Pmcn (No. 62) and the refined lattice parameters are a = 8.774 Å, b = 6.173 Å, and c = 6.203 Å. In humid air atmosphere, the total conductivity at 650 °C and the activation energy for the BCZYYb powder prepared via the CPT method was 2.1 × 10−2 S cm−1 and 0.46 eV, respectively, as compared with 1.9 × 10−2 S cm−1 and 0.45 eV for the SSR method, and 1.8 × 10−2 S cm−1 and 0.44 eV for the SG method. Under similar testing conditions, the measured peak power densities were 0.51, 0.35, and 0.40 W cm−2 at 650 °C for the anode supported PCFCs using electrolyte powder prepared via CPT, SSR and SG methods, respectively, which proves the CPT method is an effective and viable route for PCFCs applications. • BCZYYb powders are successfully prepared by CPT, SG, and SSR methods. • The CPT method shows better conductivity and performance than the other methods under similar testing conditions. • A 600-h test showed the cell with electrolyte prepared by the CPT method has a good long-term stability. [ABSTRACT FROM AUTHOR]

In this study, electrolysis of seawater in flat-tube nickel-yttria-stabilized zirconia (Ni-YSZ) electrode-supported solid oxide electrolysis cells (SOECs) were modeled and the effects of variations in electrical conductivity and microstructure of Ni-YSZ electrode support were investigated. When the current density was greater than 700 mA·cm−2, the conductivity of the electrode support decreased slightly with an increase in current density at 800 °C in hydrogen reduction environment; the conductivity of the electrode support decreased with an increase in the current density when the current density was greater than 400 mA·cm−2 at 800 °C in the seawater electrolysis environment. During long-term durability experiment of seawater electrolysis, the degradation rates in area specific resistance (ASR) were 0.096 mΩ·cm2/100 h and 0.207 mΩ·cm2/100 h with a current density of 300 mA·cm−2 (i.e., ≤400 mA·cm−2) and 1000 mA·cm−2 (i.e., ≥400 mA·cm−2), respectively. Besides, the various ions commonly present in seawater did not contaminate the Ni-YSZ support during the long-term durability test. The degradation mechanism of seawater electrolysis in flat-tube SOECs is discussed and clarified. • Conductivity of Ni-YSZ support in seawater environment is quantitatively studied. • Conductivity of Ni-YSZ support first increases and then decreases with electrolysis current. • ASR of Ni-YSZ support increases by 0.207 mΩ·cm2/100 h under 1000 mA·cm−2. • Conductivity of Ni-YSZ support is mainly related to Ni element, but not to seawater ions. [ABSTRACT FROM AUTHOR]