Comparative analysis of ceramic-carbonate nanocomposite fuel cells using composite GDC/NLC electrolyte with different perovskite structured cathode materials

Abstract

A comparative analysis of perovskite structured cathode materials, La0.65Sr0.35MnO3 (LSM), La0.8Sr0.2CoO3 (LSC), La0.6Sr0.4FeO3 (LSF) and La0.6Sr0.4Co0.2Fe0.8O3 (LSCF), was performed for a ceramic-carbonate nanocomposite fuel cell using composite electrolyte consisting of Gd0.1Ce0.9O1.95 (GDC) and a eutectic mixture of Na2CO3 (NC) and Li2CO3 (LC). The compatibility of these nanocomposite electrode powder materials was investigated under air, CO2 and air/CO2 atmospheres at 550 o C. Microscopy measurements together with energy dispersive X-ray spectroscopy (EDS) elementary analysis revealed few spots with higher counts of manganese relative to lanthanum and strontium under pure CO2 atmosphere. Furthermore, electrochemical impedance (EIS) analysis showed that LSC had the lowest resistance to oxygen reduction reaction (ORR) (14.12 Ω cm 2) followed by LSF (15.23 Ω cm 2), LSCF (19.38 Ω cm 2) and LSM (>300 Ω cm 2). In addition, low frequency EIS measurements (down to 50 µHz) revealed two additional semicircles at frequencies below around 1 Hz. These semicircles can yield additional information about electrochemical reactions in the device. Finally, a fuel cell was fabricated using GDC/NLC nanocomposite electrolyte and its composite with NiO and LSCF as anode and cathode, respectively. The cell produced an excellent power density of 1.06 W/cm 2 at 550 o C under fuel cell conditions.

Wide bandgap oxides for low-temperature single-layered nanocomposite fuel cell

“…The voltage range V = 0 -OCV corresponds to the operational range of the fuel cell, whereas outside this region the fuel cell is more or less a passive resistor. The cells were further characterized with electrochemical impedance spectroscopy (EIS) to obtain the total cell resistance of the cells using an equivalent model reported in our previous studies [29][30][31].…”

Investigation of factors affecting the performance of a single-layer nanocomposite fuel cell

“…The most commonly highlighted performance indicator in CNFC (and SLFC) literature for the single cells is the maximum power density, so it was chosen as the main indicator for comparing different cells in this Thesis, although some other indicators, such as open circuit voltage (OCV, VOC) and area-specific resistance are relevant as well. Some noteworthy results include 1100 mW/cm 2 at 550 °C with SDC-NLKC [31], 1060 mW/cm 2 at 550 °C with GDC-NLC [25], 730 mW/cm 2 at 550 °C with SDC-NC [23], 900 mW/cm 2 at 580 °C with strontiumsamarium co-doped ceria (SSDC) -NC [24], 1704 mW/cm 2 at 650 °C with SDC-NLC [27] and 1085 mW/cm 2 at 600 °C [26] with SDC-NLC. Electrode materials of the cells mentioned above are shown in Table 1.…”

“…fluorides, chlorides and hydroxides [11][12][13][14]. More recently, the research has focused on alkali carbonates and their mixtures, such as Na2CO3 (NC) [22][23][24], (NaxLi1-x)2CO3 (NLC) [25][26][27][28][29][30] and (NaxLiyK1-x-y)2CO3 (NLKC) [31,32]. Typically the weight ratios between the different carbonates in NLC and NLKC are chosen to minimize the melting temperature.…”

“…The CNFC electrolyte is a composite material consisting of a solid oxide and a salt, typically doped ceria and alkali carbonate [22][23][24][25][26][27][28][29][30][31][32]. When a carbonate mixture is mixed with doped ceria, the resulting nanopowder has been shown to form a core-shell structure with ceria cores surrounded by carbonate shells [24].…”

“…For CNFCs, the crystalline structure of doped ceria [24,31] and perovskitestructured cathodes (such as LSM, LSC, LSF and LSCF) [25] can be identified by XRD. Besides identifying the materials, XRD allows to calculate the average particle sizes (from Sherrer equation) [24,31] and the lattice parameters [24] of the studied material.…”