Spin Coating Fabrication And Properties Research Of1Ce10ScSz Electrolyte Thin Film For SOFC

Solid oxide fuel cell is a clean and efficient energy conversion device which ishelpful to solve the increasingly serious energy crisis and environmental pollutionproblems, and is considered as one of the most promising green energy sources inthe21stcentury. Research in this area focuses on lowering the operation temperaturerecently, to reduce cost and achieve large-scale application. Showing a goodprospect, scandia stabilized zirconia (ScSZ) has the highest oxygen-ion conductivityamong the currently most widely used zirconia-base electrolytes. Fabricating ScSZthin film to reduce the ohmic resistance of electrolyte is an effective way to reducethe operation temperature of SOFC. In this paper, we successfully fabricated ScSZcontaining1mol%ceria (1Ce10ScSZ) electrolyte thin film on NiO-ScSZ anodesubstrate by an easy and low-cost method of spin coating.We firstly synthesized1Ce10ScSZ nano powers by citric acid sol-gel method,and studied the influence of sintering temperature on properties of ScSZ electrolyte.As a result, the ScSZ electrolyte sintered at1550℃has the highest oxygen-ionconductivity. Its ionic conductivity was0.206S·cm-1at850℃and activationenergy was89.4kJ·mol-1. Then we prepared NiO-ScSZ anode substrates by tape-casting method, and got smooth anode substrate by pre-sintering with the heatingrate of2℃·min-1.Secondly, we fabricated1Ce10ScSZ thin film on NiO-ScSZ anode substrate byspin coating method, and studied the influence of properties of slurry, spin coatingprocedure, properties of anode substrate and sintering temperature on the propertiesof1Ce10ScSZ thin film. By characterizing morphology of1Ce10ScSZ thin film andtesting open circuit voltage of single cell, we successfully fabricated ScSZ thin filmwhich could meet the requirements of SOFC and optimized the preparationparameters. The duration of ball milling was12h; the content of ethyl cellulose inslurry was3wt%; the spin speed was7000rpm; the heat treatment temperature was450℃; the spin coating layers were more than3; the sintering temperature washigher than1500℃. Stress caused by the shrinkage mismatch of1Ce10ScSZelectrolyte and NiO-ScSZ anode during cosintering could be reduced by pre-sintering NiO-ScSZ anode without pore former starch at1200℃.Finally, we tested the performance of single cell sintering at differenttemperatures. The cell prepared with1Ce10ScSZ thin film sintered at1500℃had abetter performance. The maximum power densities were respectively115mW·cm-2,210mW·cm-2,368mW·cm-2, and492mW·cm-2at700℃,750℃,800℃, and 850℃. There was almost no performance degradation of the single cell afteroperating at750℃for8hours. Impedance spectra measurements showed thatelectrode polarization resistance limited the performance of single cell, so we couldimprove the performance of cell by optimizing composition and structure ofelectrode.