Preparation And Characterization Of The Hollow Symmetrical Anode-supported SOFC

The conventional anode-supported planar solid oxide fuel cell(SOFC)will suffer from some problems such as substrate warpping and electrolyte cracking after running for a long time.These problems result from tensile stress induced by asymmetric temperature distribution and low redox stability of the cell.To solve the problems of the conventional planar SOFC,a novel design of SOFC hollow symmetrical anode-supported planar SOFC is proposed in this work.The new type of SOFC with advantages of geometric symmetry has been prepared.At the same time,performance of the new structural cell have been studied in depth.The main results are as follows:(1)The anode substrate and functional layers of the cell are obtained through the dry pressure forming method and the screen printing process.Finally,a hollow symmetrical anode-supported SOFC was successfully prepared for the experiment.The novel type of SOFC is sealed and assembled.The performance of the SOFC have been tested.The maximal power density(MPD)of the novel type cell can reach 0.48 W/cm2 when gas flow rate of H2 is 0.2 SLM and gas flow rate of air is 0.6 SLM at 750℃.During the experiment we also prepared industrial grade hollow symmetrical anode-supported SOFC with 180 cm2 effective area.The MPD of the industrial grade SOFC is 0.268 W/cm2 when gas flow rate of H2 is 1.2 SLM and gas flow rate of air is 5.0 SLM at 750℃.(2)In order to explore the optimum testing atmosphere of the novel structure SOFC,we tested the discharge of the cell under multigroup atmosphere.In terms of fuel efficiency,we focus on the discharge performance and electrochemical impedance spectroscopy(EIS)of the cell under the 0.2 SLM and 0.3 SLM gas flow rate of H2.In a fixed H2 flux,the performance of the cell became better with air flow rate increasing.However,the air flow rate will not affect the cell performance after the air flow rate reached 1.0 SLM.(3)This work also analysed the EIS of the novel type of the cell under open circuit state and different discharge current.It was found that the impedance of the high frequency(frequency>10 kHz)impedance was not changed with the discharge current.And the impedance of the medium frequency segment(10 kHz～100 Hz)as well as low frequency segment(100 Hz～0.01 Hz)was significantly changed with the discharge current.According to impedance data,a function of the polarization impedance with the logarithm of the current is fitted.By changing the composition of the anode gas and the ratio of H2 and N2,a low frequency arc is determined to represent the anode process of the cell.(4)The discharge performance of the cell in the rarefied atmosphere has been tested.The new type of structural cell was proved to have good redox stability after multiple discharge cycles.The instantaneous discharge of the cell with N2 inlet showed that the metal Ni in the anode substrate can participate in electrochemical reaction with micro structure intact.It is possible to develop the high temperature solid storage battery with anode metal as energy storage medium.