Hauch, Anne

Online Research Database In Technology

                       General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.  • Users may download and print one copy of any publication from the public portal for the purpose of private study or research. • You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal   If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.     Downloaded from orbit.dtu.dk on: Dec 20, 2017High performing SOFC via multilayer tape casting?Hauch, AnnePublication date:2015Document VersionPeer reviewed versionLink back to DTU OrbitCitation (APA):Hauch, A. (2015). High performing SOFC via multilayer tape casting?. Poster session presented at EuropeanFuel Cell Forum 2012, Luzern, Switzerland.Microstructure   Findings  DTU Energy Conversion produce SOC anode half-cells by MTC and co-sintering in a pre-pilot plant. Investigations of microstructure and performance of cells (Ni/3YSZ-Ni/8YSZ-8YSZ-LSM/YSZ) with MTC anodes reveal:  1)  A “window” for the co-sintering from 1255°C to 1335°C 2) Uniform microstructures of desired thicknesses, porosities, particle sizes and percolation 3) High initial performance 4) Correlations of microstructure and performance with sintering temperature — increased porosity and decreased Ni particle size with lower sintering temperature  decreased gas diffusion and charge transfer reaction resistance in the Ni/YSZ anode half cell. High performing SOFC via multilayer tape casting?  Aim – Decreased SOFC manufacturing cost while keeping high fuel cell performance:   Substitute processing steps that have low material yield (e.g. spraying) and those not suitable for industrial scale production. Decrease number of sintering steps and handling efforts.   Multilayer tape casting (MTC) and co-sintering of support layer, anode and electrolyte could be a solution!  Questions: i. Can the entire anode half cell be produced via multilayer tape casting? ii. Can we co-cast anode and electrolyte layers at thicknesses of just 10-15µm?  iii. Can we obtain optimal microstructures for all half cell components in one single sintering step providing high performing anodes? Electrochemical performance Figure 2: Low voltage (0.9kV) in-lens SEM images of reduced, non-tested MTC half cells. Bright  particles constitute the percolating Ni-network.  Figure 3: High voltage (8 kV) SE-detector SEM images of reduced, non-tested MTC half-cells. Pores appear black. Ni and YSZ phases are designated in the image of the 1295-cell.  The MTC anode half-cell High voltage SEM: Impact of sint. temperature Figure 1: High voltage SE-detector SEM image of reduced, non-tested MTC half-cell sintered at 1315°C. Figure 4: Microstructural analysis of reduced, non-tested half-cells sintered at 1255°C, 1275°C, 1295°C, 1315°C and 1335°C. Uncertainties for the measured intercept lengths are app. ±0.04µm and ±1.4% for phase fractions. Measurements were performed on high voltage SE-detector images, at 11.3 kX (Figure 3), using in-house developed Matlab-based software ManSegv0.31. A minimum of 1000 line intercepts were measured for each phase in anode and support of all 5 cell samples. Sint. temp. 1255°C Sint. temp. 1335°C Sint. temp. 1255°C – active anode Sint. temp. 1295°C – active anode Sint. temp. 1335°C – active anode Sint. temp. 1255°C – support layer Sint. temp. 1295°C – support layer Sint. temp. 1335°C – support layer  Ni  YSZ Low voltage SEM: The percolating Ni network Microstructural analysis:  Phase fractions and mean intercept lengths Sint. temp. ASRFU (mcm2) Rs (mcm2) Rtpb (mcm2) fs,tpb  (Hz) RDiff (mcm2) fs,Diff  (Hz) RConv (mcm2) fs,Conv (Hz) 1255C 128 51 52 8442 15 39 51 4 1335C 158 42 85 7112 34 39 61 4 Figure 5: Nyquist (left) and DRT plot (right) of impedance spectra (IS) at 850°C, OCV, air to the cathode, 21-23% H2O in H2 to the anode. The Nyquist plot is corrected for inductance. Figure 6: IV curves at 850°C, air to the cathode, 4% H2O in H2 to the anode.  Table 1: ASRFU at 700 mV from iV-curves in Figure 6 and resistances and summit frequencies from CNLS-fit of the IS shown in Figure 5. Estimated error for the resistances 3 mcm2.  Figure 7: Equivalent circuit model applied in CNLS fitting of IS shown in Figure 5. Inductance L and  series resistance Rs are connected in series with 5 RQ elements, representative of the polarisation resistance.  Corresponding results are given in Table 1.   Gas conv. Gas diff. LSM,  low freq.  LSM,  high freq.  Ni,tpb EIS analysis: CNLS fitting Performance analysis: EIS, DRT, iV Sintering temperature: 1255°C → 1335°C            Microstructure  1) Lower porosity                                                             (support: from 31% to 23%;  active anode: from 18% to 13%)  2) Ni particle coarsening                                                      (active anode: from 0.88 µm to 1.03 µm)       Cell performance  1) ~2-fold increase in gas diffusion resistance  2) Increase in charge transfer reaction resistance from              52 mcm2 to 85 mcm2  (850 C) > < 

High performing SOFC via multilayer tape casting?

http://orbit.dtu.dk/ws/files/105037934/EFCF_poster_cbir_2012_06_22_hauc_edit_FINAL.pdf

High performing SOFC via multilayer tape casting?

Abstract

Similar works

Full text

Available Versions

Online Research Database In Technology