The Cooperation with University of Hyogo and Hyogo Prefectural Institute of Technology
KAWANISHI-CITY, Japan — Fuel cells are intensively developed because they are a highly efficient power source that can directly change the chemical energy of gases such as hydrogen, hydrocarbon, natural gas etc. into electricity.
SOFC (Solid Oxide Fuel Cell) is said to be a highly efficient electrical power source. Its low CO2 emission is an attractive feature in the context of energy savings and sustainability.
Green Science Alliance Co., Ltd. (Fuji Pigment Group) has been in the business of synthesizing and supplying various types of electrodes and solid electrolytes for SOFC. They also perform the custom synthesis of SOFC materials and measurements of electrochemical technical data based on customer requests.
Green Science Alliance has been developing apatite type lanthanum silicate-based solid electrolyte for some years and have been actively research collaborating with the University of Hyogo. This time, Dr. Atsushi Mineshige and their colleague research groups at the University of Hyogo and Hyogo Prefectural Institute of Technology have successfully developed SOFC with lanthanum silicate-based solid electrolyte.
In general, research of ion conductors with high ionic conductivity is the important key technology for developing SOFC, battery, sensor, catalyst etc. Normally, fluorite and perovskite-type crystalline is said to be to possess high ion conductivity although apatite type lanthanum silicate ionic conductor also indicates high ionic conductivity especially when they are doped with magnesium or aluminum ion. Apatite type ionic conductor does not contain expensive rare metal and still indicates high ion conductivity due to low ohmic and polarization resistance, especially at 500～800 °C. Therefore, it is considered as one of the good candidate solid electrolytes for SOFC, particularly for intermediate temperature range.
In this project, magnesium doped lanthanum silicate solid electrolyte La9.8(Si5.7Mg0.3)O26.4 (MDLS) was combined with La2SiO5 as other lanthanum silicate based material, it was possible to obtain even higher ionic conductivity. On top of that, we have also found that solid electrolyte layer could be densified in order to prevent gas leak so that voltage was maintained at high side. Furthermore, by applying Gd (Gadrlnium) doped ceria (Ce0.9Gd0.1)O1.95 (GDC) as an intermediate layer between solid electrolyte and cathode, it was possible to suppress the reaction between solid electrolyte and cathode during sintering, which resulted in suppressing cell resistance. (La,Sr)(Co,Fe)O3 as cathode material was also supplied by Green Science Alliance and by using simple and economically friendly printing procedure such as spin coating and screen printing method, it was able to prepare SOFC with apatite type lanthanum silicate-based solid electrolyte. They will further challenge to develop apatite type lanthanum silicate-based solid electrolyte with preferential orientation along the fast conducting path, in order to create SOFC with even better electrochemical property.
This research and development were supported by A-STEP Full-Scale R&D (High-risk challenge) Program (#AS2524056L), Japan Science and Technology Agency (JST), and published to Journal of Power Sources from Elsevier, Holland, with the article title, Lanthanum silicate-based layered electrolyte for intermediate-temperature fuel cell application.
Journal of Power Sources, Volume 475, 1 November 2020, 228543
Title: Lanthanum silicate-based layered electrolyte for intermediate-temperature fuel cell application
Author Names: Atsushi Mineshige, Atsushi Saito, Mio Kobayashi, Hikaru Hayakawa, Mizuki Momai, Tetsuo Yazawa, Hideki Yoshioka, Mitsumasa Sakao, Ryohei Mori, Yuki Takayama, Yasushi Kagoshima, Junji Matsui