Preparation Of Key Components And Micro Reactor Design In Direct Flame Fuel Cell

Direct flame fuel cell（DFFC）is a new type of SOFC device proposed in the past ten years.It has the advantages of no air chamber structure,no sealing material,less start-up time of SOFC and realization of combined heat and power supply.In this paper,the DFFC micro reactor design and the output performance were studied systematically.At the same time,The key components in DFFC: Al₂O₃ carrying plate and electrolyte of SOFC were fabricated by using the method of tape-casting to improve output performance and using life of DFFC.First of all,according to the traditional researches of DFFC,the DFFC device has been constructed and improved with using mica plate.After a long time DFFC test,the strength of the mica board decreases and becomes fragile.In this paper,through tape casting method,Al₂O₃ carrying plate was successfully prepared with high temperature resistance,good insulation and shape processing using in DFFC micro reactor instead of mica plate.In order to reduce the thickness and ohm resistance of electrolyte to improve the output performance of SOFC,tape casting method was used to prepare thin YSZ and ScSZ electrolyte with the thickness is between 100μm and 200μm.For the casting electrolyte of YSZ,the optimum sintering temperature is 1400 ℃by experimental comparison.The impedance of two kinds of cast electrolyte sheets was measured.The conductivity of YSZ and ScSZ electrolytes was 0.056 Scm-1 and 0.071 Scm-1 at 800℃,respectively.Secondly,in the double-chamber SOFC test,the traditional pressing electrolyte and casting electrolyte were compared.Because the thickness of casting electrolyte is smaller,the ohm resistance is less than pressing electrolyte,but the electrode sintering quality near the contacting surface of the electrolyte and the electrode is not good enough,the polarization impedance of casting electrolyte is higher and the output performance of casting electrolyte SOFC is lower.In order to improve the quality of the sintered electrode,this study tried to roughen the electrolyte surface.After roughen process,electrolyte surface appears many large electrolyte particles,increasing the electrolyte surface area,reducing the activation polarization of electrode,enhancing the output performance of the cell.When the rough Ni/YSZ SOFC works at 850℃,the peak power density is up to 393 mW·cm-2,with 0.17 Ωcm2 ohm impedance,0.68Ωcm2 polarization impedance.After the roughen of casting SOFC,the performance is far superior to the other electrolytes.Finally,in order to improve the output performance of DFFC,this paper studied the way to improve the temperature of cathode,to reduce the gas pressure near thecathode and to improve the oxygen partial pressure at cathode with lower cost.The final design of DFFC device is stainless steel tube structure.The stainless steel tube is equipped with DFFC micro stack to carry out the 6 cycles looping test in 3 hours,and the micro reactor can still discharge normally after the looping test.With using Ni/YSZ anode supported micro stack in DFFC,the open circuit voltage is 4.3V of 6batteries in series,the peak power density is about 150mW·cm-2 when the cathode temperature is 610℃ and this DFFC can support power for the external load in the practical application.The output performance of pressing and casting YSZ electrolyte supported batteries was tested.The peak power densities are 45.8 mW·cm-2 and 32.3mW·cm-2 when the cathode temperature is 610℃,respectively.To sum up,the output performance and using life of DFFC are improved by the preparation of the battery loading plate,roughened tape-casting electrolyte and the new design of micro reactor for DFFC.In this study of casting electrolyte,the electrolyte with low ohm impedance was successfully fabricated by tape casting method.The surface microstructure of electrolyte was optimized by surface roughening method...