Modifying the electrode-electrolyte interface of anode supported solid oxide fuel cells (SOFCs) by laser-machining

摘要

The NiO-yttrium stabilized zirconia (YSZ) anode substrates prepared by tape casting are modified via laser machining technique in mesoscale for electrode-electrolyte interface modification. Two different surface processing methods are applied: (i) scanning the whole surface with continuous tracks to produce a "coarser" surface; (ii) engraving spots on the substrates surface forming "pits array". The microstructure and electrical performance of the cells based on these anode substrates are investigated. For the scanned anode, confocal laser scanning microscope (CLSM) images show that the surface roughness increases with the laser intensity. The scanning electron microscopy (SEM) images of single cells show that electrode-electrolyte interface contact area is increased. Compared with the unmodified cell, the maximum power density of the cells fabricated with "coarser" anode substrates is improved by 47% at 800 degrees C. For the second case, the SEM images of cross-section of single cells show that the electrode-electrolyte interface is wavy, resulting increase in the electrochemically active area. It's found that the degree of performance enhancement of the cells is related to the pits size, and a suitable diameter and depth of the pits are needed. The highest power density of the cells with "pits array" increases by 55% at 800 degrees C. In both cases, electrochemistry impedance spectroscopy (EIS) results show that ohmic and polarization resistances of single cells are decreased after modification.