LSGM electrolyte thin films and electrochemical properties of
|School||Kunming University of Science and Technology|
|Keywords||Intermediate temperature solid oxide fuel cell LSGM thin film RF magnetron sputtering Slurry spin-coating Electrochemical properties|
Solid oxide fuel cell (SOFC), which is an energy conversion device can convert the chemical energy of the fuel into electrical energy directly, has attracted more and more attention attributing to high efficiency and environmental protection. The key current research is the fabrication of SOFC operating at a lower temperature (the operation temperature below 800℃). In order to achieve predominant output of cell, reducing the thickness of LSGM electrolyte and transforming the traditional electrolyte-supported SOFC into anode-supported type is a promising technology route.LSGM and LSCM powders were synthesized via glycine-nitrate process. X-ray diffraction (XRD) and energy spectrum analysis (EDS) results showed that the as-prepared powders possessed a pure phase of perovskite type structure and the molar ratio of the metal elements met the ratio of experimental design. At the same time, for the purpose of optimizing the microstructure of the anode support, the effects of type and additive amount of pore-formers on the anode apparent performance were carefully investigated. The results show that the maximum porosity and best microstructure were obtained when 8 wt.% starch was selected as the pore-former.LSGM electrolyte film was fabricated by slurry spin coating process. The particles of LSGM in a suspension were deposited onto anode substrates through a centrifugal force by high-speed rotation. The method has an advantage of simple, fast, and cost-effective. The parameters related to the performance of the LSGM films including the type and additive amount of binder and modifier, heating temperature and spin-coating number were investigated finely. The electrolyte films with the best compactness and somewhat roughness were obtained when the operating parameters fixed as follows:the content of ethyl cellulose which acted as binder is 5 wt.%, the content of terpineol which acted as modifier is 5 wt.%, the optimum coating number is 9 times and the best post-deposition sintering temperature is 1400℃for 4 h. Furthermore, RF magnetron sputtering technique was also used to fabricate LSGM films. The influence of key sputtering parameters on the quality of LSGM film was systematically studied. The technical parameters were optimized by the film morphology observation, the deposition rate and the adhesion state of the anode/electrolyte bilayer in the course of experiments. Sputtering pressure of 5 Pa, RF power of 210 W and substrate temperature of 300℃were identified as the best technical parameters. Under these conditions, LSGM electrolyte film obtained by magnetron sputtering technology has a high density, good crystallinity, and well adhesive with anode substrates after being annealed at 1000℃for 2 h in air.In addition, a two-electrode half cell configuration was selected to investigate the electrochemical performance of the thin films which were fabricated under the optimum condtions with RF magnetron sputtering technique and slurry spin coating process labeled 1# half cell and 2# half cell, respectively. The exchange current density of 1# half cell was larger than that of 2# determined by LSV and Tafel curves. Furthermore, the AC impedance spectrum test results show that the resistance of the electrolyte film prepared by RF magnetron sputtering is less than that of slurry spin coating. The electrochemical performance test results showed that RF magnetron sputtering technology is more appropriate to prepare LSGM electrolyte film for SOFC than slurry spin coating method.