| The solid oxide fuel cell (SOFC) is a new power generation equipment with the merits of high efficiency and low pollution, which is attentted extensively in the world. Tubular SOFC (tSOFC) is a power generation technology fitting to commercial development because of its characteristics such as high mechanical and thermal stability, simple sealed technique, and highly modularizing integration. In this paper, anode supported tSOFC was prepared and investigated. The cermet molding technology with lower cost was developed to prepare YSZ electrolyte film. The continuously grade anode functional layer was proposed to improve the anode performance. On these bases, the single cell and the stack of tSOFC were assembled, whose performance were systematically studied. This work lays a solid foundation for the cell stack with high power density.YSZ thin film was fabricated via dip-coating method. The dip-coating slurry is a new type of suspension system containing high solid content, which overcomes the disadvantages of long time and low efficiency compared with the traditional coating method. The optimal composition of the slurry was determined by the stability and viscidity of the slurry as well as the surface microstructure of the thin electrolyte film. The contents of all ingredients are 100g YSZ powder, 550mL solvent (methylethylketone/ethanol=1:1), 2.5g dispersant (triethanolamine, TEA), 4.5g binder (poly-vinyl-butyl, PVB) and 7.5g plasticizer (polyethylene glycol, PEG, and diethyl-o-phthalate, PHT), respectively. The dense YSZ film was prepared by this optimized composition, and the thickness of the electrolyte film was about 27μm. The performance of the cells with dip-coating electrolytes was measured, the OCVs reached 1.12~1.19V at 650~850℃, which was close to the theoretical value. The power density of the cell was 505 mW·cm-2 at 800℃. The conductivity of the YSZ film was 0.0098 S·cm-1 at 800℃, better than that of sol dip-coating.The effects of sintering procedure on YSZ bulk, YSZ thin film and the cell performance were investigated in the paper. The grain size and density of YSZ are the main factors of controlling the electrolyte conductivity. For the sintering procedures of S15, S14 and S12-20, the particle size of YSZ grains decreased and the YSZ conductivity increased gradually with 0.014 S·cm-1, 0.0445 S·cm-1 and 0.0564 S·cm-1, respectively. The maximum power densities of the cell corresponding to the three sintering procedure are 505mW·cm-2, 623mW·cm-2 and 671mW·cm-2 with the OCVs of 1.14V, 1.13Vand 1.11V, respectively. These results indicated that lower temperatures could effectively inhibit the sintering of anode, reduce the polarization resistance of the cell and improve the discharge performance of the cell. The sintering mechanism of YSZ thin film was studied, and the results showed that the crystallization in the YSZ sintering process had an obvious effect on the grain size and density of the sintered YSZ film. A step of 1,200°C for 2 h in the sintering procedure helped to form a lot of crystal grains whose grains sizes were bigger than the critical crystal grain size. Through the continuously increase of these crystal sizes, the dense YSZ film was obtained with the smaller crystal grains. The three-step sintering process was carried out to inhibit grain boundary migration and ensure the sufficiency of grain boundary diffusion, and the densification of YSZ film was realized under lower temperature.The tubular SOFC anode was prepared by isostatic cool pressing method. YSZ electrolyte film was obtained by dip-coating technology, and then the single tubular SOFC was assembled and tested. At 800℃, the OCV of the cell was 1.0V with H2 fuel, and the maximum power and power density were 0.42W and 110mW·cm-2, respectively, which was close to the international level of the tubular SOFC performance. Using SUS430 stainless steel as the connector, the tubular SOFC stacks were fabricated and discharged at 800℃with H2 at a flow rate of 300 mL·min-1. The output power of the stack was 0.65W with an OCV of 0.79V. The performance of this stack had a decrease of 14% in 8.5h under constant current condition.The idea of continuously graded anode functional layer (CG-AFL) prepared via electrophoretic co-deposition (EPD) technique was firstly proposed in our paper. The preparation process and the performance of this CG-AFL were also investigated. The initial electrophoretic current increased with increasing the external voltages and the current density reduce gradually under different voltage with the electrophoretic process. The weight of deposition layer was linear related with the external voltage. At a given voltage, the weight of deposition layer linear increased within a period of time. Then the deposition quantity and time were the parabolic relationship, and the slope of this parabolic curve decreased with increasing time. The ideal microstructure of anode functional layer was prepared at constant voltage of 40V. The ratios of NiO to YSZ showed continuous change along the thickness of the AFL. NiO content decreased from the 64mass% to the 50mass% when the deposition layer changed from 2.5μm distance to 13.3μm distance to the anode substrate, and the YSZ content increased from 36mass% to 50mass% at the same time. The cell performances were improved after AFL was added via electrophoretic co-deposition, and the maximum power densities were 0.88, 1.15 and 1.10 W·cm-2 at constant voltage electrophoretic deposition for 5, 10, and 20min. The EIS results showed that the TPB was increased because of the AFL prepared via electrophoretic co-deposition method. The cell polarization resistances Rp reached minimal value of 0.288?·cm2 when the AFL had a thickness of 9.8μm after electrophoretic co-deposition for 10min.
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