Preparation Of Anode And Electrolyte For IT-SOFC By Tape Casting And Wet Powder Spraying

Solid Oxide Fuel Cell (SOFC) has attracted many interests as a direct chemical-to-electrical energy conversion device for its high efficiency, low pollution, wide use and high reliability. Recent research has focused on promoting its commercialization by reducing the operating temperature to intermediate temperature700-800℃.Wet powder spraying is a mature technique for mass and continuous producing thin films. Tape casting method is widely used in electronic ceramics area. This Ph.D. thesis focuses on preparing anode by tape casting, preparing anode functional layer and electrolyte by wet powder spraying. According to the research, results are obtained as follows.We investigated the effects of pore formers on anode. Graphite is a good pore former of stable properties and sufficient supplying. The pores formed by graphite were strip shape and well distributed perpendicularly to the anode thickness direction, and the anode microstructure was fine. Graphite is suitable for industrial producing. By partially using YSZ powder pre-sintered at1300℃, the three phases of anode, which were YSZ, NiO and pores, connected and distributed better and the microstructure of anode was improved. In our laboratory we used industrial production YSZ and NiO and improved the techniques of slurry preparing, casting and drying. A tape casting technique, which was suitable for mass producing SOFC anode, was created.A method for preparing SOFC was invented. The anode functional layer slurry was wet powder sprayed on the PET films and dried to form green layer. Then the anode slurry was tape cast on the green layer. After drying, the anode functional layer-anode green tape was separated from PET films and co-sintered. In this invention, the anode functional layer not only increased the active reaction regions and electrochemical activities of anode, but also modified the anode surface, which was very smooth, of few defects and thus suitable for electrolyte preparing after decoration. The single cell based on this invention was tested at750℃with OCV of1.10V and maximum power density of0.7W/cm2. Preparing YSZ electrolyte by wet powder spraying was investigated. The bi-layer wet powder spraying method combined the electrolyte, anode functional layer and anode preparing techniques, which simplified the process and increased the producing efficiency. The single cell prepared by bi-layer wet powder spraying was tested at750℃with OCV of1.05V and maximum power density of0.38W/cm2. The shrinkage match of anode and electrolyte during sintering was adjusted by pre-sintering anode before wet powder spraying electrolyte. The single cell based on the anode pre-sintered at1200℃performed a maximum power density of0.62W/cm2and OCV of1.10at750℃.