The Anode Structure Design,control And The Effects On The Performance Of SOFC

Solid oxide fuel cell(SOFC)is a device that can convert chemical energy in fuel directly into electrical energy,which has the characteristics of high energy conversion efficiency and environmental protection.In order to reduce the operating temperature and ohmic resistance of SOFC,the anode-supported thin film SOFC has been extensively studied.A thick anode layer will reduce the diffusion of the fuel gas,and will result in concentration polarization.Decreasing the operating temperature will decrease electrochemical reaction rates and increase the activation overpotential.A suitable anode microstructure and porosity will help reduce the polarization of the cell.In this paper,the influence of the anode structure on battery performance has been studied through the design and regulation of the anode structure.The morphology of the anode pores was controlled by adding four pore-forming agents,that is,graphite,starch,polymethyl methacrylate(PMMA)and polystyrene(PS).The results showed that due to the different morphology of the pore-forming agents,four kinds of characteristic pores were obtained,which had different anode porosity and mechanical strength.For the anodes formed by the four pore formers,the electrical conductivities of the anodes were measured and the electrical conductivity was ranked as PMMA>starch>graphite>PS anode.The graphite,starch,PMMA,and PS cells were tested by using hydrogen as the fuel gas at 800?.Their open circuit voltage(OCV)was about IV,and their maximum power densities were 0.281 W/cm2,0.346 W/cm2,0.454 W/cm2 and 0.403 W/cm2,respectively.The effect of anode porosity on the performance of SOFC was studied by controlling the content of graphite.Results showed that the porosity of the anode increased while the mechanical strength and conductivity decreased with the increasing graphite content.The best electrical properties was obtained at the anode graphite content of20%,and its maximum power density was0.491W/cm2at800?.In order to increase the anode reaction area,an anode gradient structure and a functional layer were also designed.The maximum power density at800? was0.533 W/cm2and0.582W/cm2,respectively.The anode structure were also greatly influenced by the process of co-firing of the anode and the electrolyte.The density of YSZ electrolyte prepared was poor by traditional sintering process at 1200?,but greatly increased by the cold sintering process at the same temperature.It was found that the electrical conductivity of the YSZ electrolyte prepared by the cold sintering process was higher than that of the YSZ electrolyte prepared by the traditional process.The cold sintering process effectively reduced the co-firing temperature of the anode and the electrolyte,which resulted in a significant decrease in the grain size of anode and obtaining a richer reaction zone.The electrical performance test of the single cell prepared by the two processes showed that the maximum power density of the single cell prepared by cold sintering process at 800? was 0.474W/cm2,which was better than the single cell electrical performance of the traditional sintering process at 1400?.