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Kazunari SASAKI Last modified date:2024.04.10

Professor / Hydrogen Utilization Processes
Department of Mechanical Engineering
Faculty of Engineering

Graduate School
Undergraduate School
Other Organization
Administration Post
Vice President
Director of International Research Center for Hydrogen Energy
Director of Next-Generation Fuel Cell Research Center

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Homepage of Prof. Kazunari SASAKI`s Laboratory .
Homepage of International Research Center for Hydrogen Energy .
Academic Degree
Dr. sc. techn. ETH
Country of degree conferring institution (Overseas)
Field of Specialization
Fuel cell science and engineering, Hydrogen technology, Inorganic materials chemistry, Electrochemistry
ORCID(Open Researcher and Contributor ID)
Total Priod of education and research career in the foreign country
Outline Activities
In the research group of Dr. Kazunari Sasaki, we focus on the R&D of fuel cell materials. Two major activities, on polymer electrolyte fuel cells (PEFC) and on solid oxide fuel cells (SOFC), are both supported by several research fundings, including national R&D project of SOFCs and PEFCs.

In our reserach group, we have various facilities including 60 evaluation systems of fuel cell electrchemical performance/properties (with Solartron impedance analyzers, Potentiostat/Galvanostat, CVs, multimeters), microscopes (High-resolution FESEM-EDX-STEM, SEM-EDX, AFM, STM, KFM), materials evaluation apparatus (XRD, XPS, BET, TG-DTA, TG-MS etc.), several gas chromatographs and GC-MS, as well as preparation apparatus for electrode catalysts and fuel cells. Thus our graduate students and research staffs can prepare FC-related materials and fuel cells and can analyze their performanece by themselves.

(1) Nano-structured Electrode Catalysts for PEFCs

Polymer electrolyte fuel cells (PEFCs) are promising energy systems with several advantages including high energy density, low-temperature operation, short start-up time etc., so that automobile, portable, as well as stationary applications are of technological interest. However, in the state-of-the-art cells, a large amount of noble metals should be used, leading to too high cost of fuel cell systems. A higher performance of electrode catalysts using less amount of noble metals, especially platinum, is essential, and this is one of the most relevant technological tasks in PEFC research and development.

In this research period, we focus on carbon support materials and oxide-based additives for electrode catalysts. Various types of carbon materials were applied and the influence of carbon nanostructure on electrochemical properties was analyzed to realize higher power generation characteristics and a reduction of noble metal loading of the electrode catalysts. Downsizing of electrode catalysts, Pt, was also carried out. We have succeeded, via colloidal processes, to prepare Pt nanoparticles with a crystallite size of ca. 3 nm. Effect of nanostructuring on electrochemical properties are also analyzed to establish materials design strategies of PEFC/DMFC electrode catalysts.

(2) Multi-Fuel Capable SOFCs

In our institution, we systematically characterize electrochemical performance, relevant transport properties of ceramic materials, the interactions between the fuel cell components and the fuel gas species, and equilibria in fuel gases. We wish to contribute to solid oxide fuel cells (SOFC) development and commercialization based on our fundamental research activities, e.g. by establishing optimum operational conditions of fuel cells, proposing alternative materials, and analyzing electrochemical reaction phenomena. We have focused on power generation characteristics of SOFCs operated with various kinds of fuel gases (including lower and higher hydrocarbons, alcohols, biogases, coal gases, GTL fuels, and fuels with various impurities), as one of the most advantageous features of SOFCs is their flexibility for fuel selections. Based on these advantages, we may realize e.g. zero-emission renewable energy systems with SOFCs. We have also developed sulfur-tolerant SOFCs with chemically modified fuel electrodes.

Such research activities are conducted as the Director of International Research Center for Hydrogen Energy, the Director of Next-Generation Fuel Cell Research Center, and a Distingished Professor. Educational activities are made in Department of Hydrogen Energy Systems (Graduate School of Engineering), and Department of Mechanical and Aerospace Engineering (School of Engineering).

In addition, based on various experiences with industry and public sectors, Prof. Sasaki is currently acting as a Senior Vice President, as well as various committee members in the central and local Governments.
Research Interests
  • Electrode materials for SOFCs
    keyword : Fuel cells, SOFC, Electrode materials, durability, poisoning
  • Advanced Electrocatalysts for Polymer Electrolyte Fuel Cells
    keyword : Fuel Cells, PEFC, Electrocatalyst, Catalyst support materials, Carbon materials, Oxide electronic conductors
  • Alternative Electrolyte Materials for Fuel Cell Applications
    keyword : Hydrogen Energy, Fuel Cells, Solid State Ionics
  • Fuel Cell Materials Design by Nanostructuring
    keyword : Colloidal processes, Nano-size effects, Interfacial effects
  • Defect Chemistry of Functional Ceramics
    keyword : Defect chemistry,Chemical Thermodynamics, Electrical conductors
Current and Past Project
  • SOFCs are the most flexible fuel cells with respect to fuel selection. However, various impurities in practical fuels and/or from SOFC system components can cause poisoning of fuel electrodes and thus degradation of electrochemical performance. Impurity tolerance of SOFCs has been analyzed by using various impurity-containing gases with respect to operational conditions to understand poisoning mechanisms and to improve long-term durability of SOFC systems.
  • Higher performance and long-term durability of electrocatalysts are essential for polymer electrolyte fuel cells (PEFCs), where electrocatalyst support materials act as a very important role. In this study, as alternatives to conventional carbon black catalyst support, semiconducting oxides and carbon nanofibers have been applied. In-situ colloidal impregnation enables to prepare highly-dispersed Pt catalysts on such support materials. Principles for electrocatalyst design using alternative catalyst supports are discussed.
Academic Activities
1. Yasuharu Kawabata, Tatsuya Nakajima, Kazuo Nakamura, Toru Hatae, Yuya Tachikawa, Shunsuke Taniguchi, Yoshio Matsuzaki, Kazunari Sasaki, Proposal of ultra-high-efficiency zero-emission power generation systems, Journal of Power Sources, 10.1016/j.jpowsour.2019.227459, 448, 2020.02, Solid oxide fuel cell (SOFC) and protonic ceramic fuel cell (PCFC) have strong features that enables high efficiency power generation and efficient CO2 capture. Applying these technologies to the fossil fuel and biomass power generation, we can realize ultra-high efficiency zero-emission power generation by capturing liquefied CO2 (LCO2) for easy transport and utilization (CCU) or storage(fossil fuel CCS and bio-energy CCS: BECCS). In this study, we propose LCO2 capture ultra-efficient power generation systems consist of multi-stage SOFC/PCFC, oxygen or hydrogen transport membrane, CO2 cooling and liquidizing units driven by exhaust heat and generated power by fuel cells. Net power generation efficiency is estimated through heat mass balance analysis. As the results for natural gas, proposed PCFC system is suitable and expected 64.7 %LHV net power generation efficiency with more than 99 vol% LCO2 capture. For biogas direct supply case, net power generation efficiency of proposed PCFC system is 57%LHV with 99 vol% capture of CO2 in the air. These results indicates that proposed systems have quite strong potential that enables ultra-high efficient CO2-free fossil fuel power generation with CCS and CO2-reduction biomass fuel power generation with BECCS..
2. Shotaro FUTAMURA, Aki MURAMOTO, Yuya TACHIKAWA, Junko MATSUDA, Stephen M. LYTH, Yusuke SHIRATORI, Shunsuke TANIGUCHI, Kazunari SASAKI, SOFC Anodes Impregnated with Noble Metal Catalyst Nanoparticles for High Fuel Utilization, Intl. J. Hydrogen Energy, 10.1016/j.ijhydene.2019.01.223, 44, 16, 8502-8518, 44(16), pp. 8502-8518, 2019.03.
3. Yoshiki NAKAZATO, Daiki KAWACHINO, Zhiyun NODA, Junko MATSUDA, Stephen M. LYTH, Akari HAYASHI, Kazunari SASAKI, PEFC Electrocatalysts Supported on Nb-SnO2 for MEAs with High Activity and Durability: Part I. Application of Different Carbon Fillers, J. Electrochem. Soc., 10.1149/2.0311814jes, 165, 14, F1154-F1163, 165 (14), pp. F1154-F1163, 2018.10.
4. Shohei MATSUMOTO, Masaru NAGAMINE, Zhiyun NODA, Junko MATSUDA, Stephen M. LYTH, Akari HAYASHI, Kazunari SASAKI, PEFC Electrocatalysts Supported on Nb-SnO2 for MEAs with High Activity and Durability: Part II. Application of Bimetallic Pt-Alloy Catalysts, J. Electrochem. Soc., 10.1149/2.0321814jes, 165, 14, F1164-F1175, 165 (14), pp. F1164-F1175, 2018.10.
5. Junko MATSUDA, Tatsuya KAWASAKI, Shotaro FUTAMURA, Tsutomu KAWABATA, Shunsuke TANIGUCHI, Kazunari SASAKI, In situ Transmission Electron Microscopic Observations of Redox Cycling of a Ni–ScSZ Cermet Fuel Cell Anode, Microscopy, 10.1093/jmicro/dfy025, 67, 5, 251-258, 67 (5) , pp. 251-258, 2018.05.
6. Makito OKUMURA, Zhiyun NODA, Junko MATSUDA, Yuya TACHIKAWA, Masamichi NISHIHARA, Stephen M. LYTH, Akari HAYASHI, Kazunari SASAKI, Correlating Cathode Microstructure with PEFC Performance using FIB-SEM and TEM, J. Electrochem. Soc., 10.1149/2.0581709jes, 164, 9, F928-F934, 164 (9), pp. F928-F934, 2017.07.
7. Xuesong SHEN, Kazunari SASAKI, Robust SOFC anode materials with La-doped SrTiO3 backbone structure, Int. J. Hydrogen Energy, 10.1016/j.ijhydene.2016.08.024, 41, 38, 17044-17052, 2016.10.
8. Thomas BAYER, Benjamin V. CUNNING, Roman SELYANCHYN, Masamichi NISHIHARA, Shigenori FUJIKAWA, Kazunari SASAKI, Stephen M. LYTH, High Temperature Proton Conduction in Nanocellulose Membranes: Paper Fuel Cells, Chem. Mater., 10.1021/acs.chemmater.6b01990, 28, 13, 4805-4814, 2016.07.
9. Yuya TACHIKAWA, Junki SUGIMOTO, Masaru TAKADA, Tsutomu KAWABATA, Stephen M. LYTH, Yusuke SHIRATORI, Kazunari SASAKI, In Operando Visualization of SOFC Electrodes by Thermography and Visible Light Imaging, ECS Electrochemistry Letters, 4, 11, F61-F64, 2015.08.
10. Takeshi DAIO, Aleksandar STAYKOV, Limin GUO, Jianfeng LIU, Masaki TANAKA, Stephen M. LYTH, Kazunari SASAKI, Lattice Strain Mapping of Platinum Nanoparticles on Carbon and SnO2 Supports, SCIENTIFIC REPORTS, 10.1038/srep13126, 5, 13126, 2015.08.
11. Yoshio MATSUZAKI, Yuya TACHIKAWA, Takaaki SOMEKAWA, Toru HATAE, Hiroshige MATSUMOTO, Shunsuke TANIGUCHI, Kazunari SASAKI, Effect of proton-conduction in electrolyte on electric efficiency of multi-stage solid oxide fuel cells, SCIENTIFIC REPORTS, 5, 12640, 2015.07, 本研究は、燃料電池の高効率化に向けたシステム解析で、市販の燃料電池と比べ、約3割の発電効率向上が望めることを示した。高温型燃料電池システムにおいて、システム安定作動のために、発電に使用しなかった燃料を構造改良で活用しつつ、材料変更による燃料の希釈化を防ぐことで、相乗的な性能向上効果が得られ、供給した燃料のエネルギーの約80%を電気に変換可能である事を示すことができた。.
12. Takeshi DAIO, Thomas BAYER, Tatsuya IKUTA, Takashi NISHIYAMA, Koji TAKAHASHI, Yasuyuki TAKATA, Kazunari SASAKI, Stephen M. LYTH, In-Situ ESEM and EELS Observation of Water Uptake and Ice Formation in Multilayer Graphene Oxide, SCIENTIFIC REPORTS, 10.1038/srep11807, 5, 11807, 2015.07.
13. Yoshio MATSUZAKI, Yuya TACHIKAWA, Takaaki SOMEKAWA, Toru HATAE, Hiroshige MATSUMOTO, Shunsuke TANIGUCHI, Kazunari SASAKI, Effect of proton-conduction in electrolyte on electric efficiency of multi-stage solid oxide fuel cells, SCIENTIFIC REPORTS, 10.1038/srep12640, 5, 12640, 2015.07.
14. Kazunari SASAKI, Zhiyun NODA, Takuya TSUKATSUNE, Kohei KANDA, Yuma TAKABATAKE, Yohei NAGAMATSU, Takeshi DAIO, Stephen M. LYTH, Akari HAYASHI, Alternative Oxide-supported PEFC Electrocatalysts, ECS Transactions, 64, 3, 221-227, 2014.10.
15. Yoshinori KOBAYASHI, Kenichiro KOSAKA, Kazuo TOMIDA, Norihisa MATAKE, Kohei ITO, Kazunari SASAKI, Start-Up Characteristics of Segmented-In-Series Tubular SOFC Power Modules Improved by Catalytic Combustion at Cathodes, Fuel Cell, 14, 1028-1035, 2014.09.
16. M. Hanasaki, C. Uryu, T. Daio, T. Kawabata, Y. Tachikawa, S. M. Lyth, Y. Shiratori, S. Taniguchi, K. Sasaki, SOFC durability against standby and shutdown cycling, Journal of the Electrochemical Society, 10.1149/2.0421409jes, 161, 9, F850-F860, 2014.09, To simulate realistic operating conditions in SOFC systems, we investigate the influence of thermal cycling on the performance of electrolyte-supported planar SOFCs. Thermal cycling is often associated with interruption of fuel supply, with three main modes; hot standby, cold standby, and shutdown. Cell performance degradation is most significant during shutdown cycles. Nickel oxidation and agglomeration are more pronounced when SOFCs are subjected to lower temperatures for longer periods of time, leading to significant performance degradation. Ostwald ripening at the anode leads to degradation as Ni grains increase in size with cycling. Ni particle precipitation on the anode zirconia grains and along electrolyte grain boundaries is found for the first time in shutdown cycling tests. When H2S is mixed with the fuel, the internal reforming reactions and electrode reactions are inhibited by sulfur poisoning of the Ni anodes, accelerating degradation. The SOFC cycling degradation mechanisms are discussed in detail..
17. Zhiyun NODA, Kyohei HIRATA, Akari Hayashi, Shunsuke TANIGUCHI,, Naoto NAKAZATO, Atsuko SEO, Isamu YASUDA, Seiji ARIURA, Hidetoshi SHINKAI, Kazunari SASAKI, PEFC-type Impurity Sensors for Hydrogen Fuels., Intl. J. of Hydrogen Energy, 10.1016/j.ijhydene.2012.08.062, 37, 21, 16256-16263, 2012.09.
18. Kazunari SASAKI, Kengo HAGA, Tomoo YOSHIZUMI, Dasuke MINEMATSU, Eiji YUKI, Runru LIU, Chie URYU, Toshihiro OSHIMA, Teppei OGURA, Yusuke SHIRATORI, Kohei ITO, Michihisa KOYAMA, Katsumi YOKOMOTO, Chemical Durability of SOFCs: Influence of impurities on long-term performance., J. of Power Sources, 196, 22, 9130-9140, 2011.11.
19. A. Masao, S. Noda, F. Takasaki, K. Ito, K. Sasaki, Carbon-free pt electrocatalysts supported on SnO2 for polymer electrolyte fuel cells, Electrochemical and Solid-State Letters, 10.1149/1.3152325, 12, 9, 2009.07, Carbon-free Pt-based electrocatalysts supported on semiconducting SnO 2 (Pt/ SnO2) have been developed for polymer electrolyte fuel cells (PEFCs) by various electrochemical and microstructural characterizations. Pt/ SnO2 exhibited comparable current-voltage characteristics to conventional Pt electrocatalysts and, in particular, a considerable tolerance against 10,000 cycles of voltages up to 0.9 and 1.3 VRHE (RHE denotes reversible hydrogen electrode) vs the RHE. These results indicate that the carbon-free oxide-supported Pt/ SnO2 can be a promising alternative electrocatalyst with long-term durability against voltage cycling up to higher potentials, as a possible fundamental solution to the PEFC degradation caused by carbon support corrosion..
20. K. Haga, S. Adachi, Yusuke Shiratori, Kohei Ito, Kazunari Sasaki, Poisoning of SOFC anodes by various fuel impurities, Solid State Ionics, 10.1016/j.ssi.2008.02.062, 179, 27-32, 1427-1431, 2008.09, Poisoning effects by various fuel impurities, including H2S, CH3SH, COS, Cl2, and siloxane, to Ni-ScSZ cermet anodes have been analyzed and compared. Degradation of cell performance caused by these impurities was characterized by measuring cell voltage and anode polarization at a constant current density of 0.2 Acm- 2 for humidified H2 and CH4 fuels. Poisoning for hydrogen-based fuels containing 5 ppm sulfur compounds, H2S, CH3SH, and COS, caused an initial cell voltage drop of about 15 mV at 1000 °C. The initial voltage drop was independent of the kind of sulfur compounds, whereas in the case of poisoning by CH3SH, an additional gradual decrease in cell voltage was clearly detected after the initial voltage drop. Thermochemical calculation and FESEM-EDX analysis also indicated that the poisoning by Cl2 caused the formation of nickel nano-particles on zirconia grains via NiCl2 (g), while the poisoning by siloxane formed segregated silica (SiO2) in porous cermet anodes..
21. Kazunari Sasaki, K. Susuki, A. Iyoshi, M. Uchimura, N. Imamura, H. Kusaba, Y. Teraoka, H. Fuchino, K. Tsujimoto, Y. Uchida, N. Jingo, H 2S poisoning of solid oxide fuel cells, Journal of the Electrochemical Society, 10.1149/1.2336075, 153, 11, 2006.10, The influence of H2 S fuel impurity on power generation characteristics of solid oxide fuel cells (SOFCs) has been analyzed by measuring cell voltage at a constant current density, as a function of H2 S concentration, operational temperature, and fuel gas composition. Reversible cell voltage change was observed around 1000°C, while fatal irreversible degradation occurred at a lower operational temperature, at a higher H2 S concentration, and at a lower fuel H2 CO ratio. Sulfur tolerance of SOFCs was improved by using Sc2 O3 -doped Zr O2 instead of Y2 O3 -doped Zr O2 as electrolyte and/or as electrolyte component in the anode cermets. It has been found that H2 S poisoning consists of at least two stages, i.e., an initial cell voltage drop within a short time period to a metastable cell voltage, followed by a gradual larger cell voltage drop. Possible H2 S poisoning processes are discussed..
22. K. Sasaki, K. Watanabe, K. Shiosaki, K. Susuki, and Y. Teraoka, Multi-fuel Capability of Solid Oxide Fuel Cells, JOURNAL OF ELECTROCERAMICS, 10.1007/s10832-004-5174-z, 13, 1-3, 669-675, 13 (1-3): 669-675 2004, 2004.11.
23. K. Sasaki, K. Shinya, S. Tanaka, Y. Kawazoe, T. Kuroki, K. Takata, H. Kusaba, and Y. Teraoka, Nanostructured PEFC Electrode Catalysts Prepared via In-situ Colloidal Impregnation, Mater. Res. Soc. Symp. Proc., 835, 241-246, Vol. 835, 241-46 (2004)., 2004.11.
24. K. Sasaki, K. Watanabe, and Y. Teraoka, Direct-alcohol SOFCs: Current-voltage characteristics and fuel gas compositions, JOURNAL OF THE ELECTROCHEMICAL SOCIETY, 10.1149/1.1756884, 151, 7, A965-A970, 151 (7): A965-A970 2004, 2004.07.
25. K. Sasaki and Y. Teraoka, Equilibria in fuel cell gases - II. The C-H-O ternary diagrams, JOURNAL OF THE ELECTROCHEMICAL SOCIETY, 10.1149/1.1577338, 150, 7, A885-A888, 150 (7): A885-A888 JUL 2003, 2003.07.
26. K. Sasaki and Y. Teraoka, Equilibria in fuel cell gases - I. Equilibrium compositions and reforming conditions, JOURNAL OF THE ELECTROCHEMICAL SOCIETY, 10.1149/1.1577337, 150, 7, A878-A884, 150 (7): A878-A884 JUL 2003, 2003.07.
27. K. Sasaki and J. Maier, Low-temperature defect chemistry of oxides. II. Analytical relations, JOURNAL OF APPLIED PHYSICS, 10.1063/1.371542, 86, 10, 5434-5443, 86 (10): 5434-5443 NOV 15 1999, 1999.11.
28. K. Sasaki and J. Maier, Low-temperature defect chemistry of oxides. I. General aspects and numerical calculations, JOURNAL OF APPLIED PHYSICS, 10.1063/1.371541, 86, 10, 5422-5433, 86 (10): 5422-5433 NOV 15 1999, 1999.11.
29. K. Sasaki, J. P. Wurth, R. Gschwend, M. Gödickemeier, L. J. Gauckler, Microstructure-property relations of solid oxide fuel cell cathodes and current collectors cathodic polarization and ohmic resistance, Journal of the Electrochemical Society, 10.1149/1.1836476, 143, 2, 530-543, 1996.02, Microstructure, cathodic polarization, and ohmic resistance on the cathode side of ZrO2-based solid oxide fuel cells have been studied for the intermediate temperature operation range between 700 and 900°C. Starting powder characteristics, powder calcination temperature, and sintering temperature strongly influence the final microstructure of cathodes. Electrochemical performance depends on these processing parameters as well as on the cathode thickness and the contact spacing of current collectors. A decrease in effective electrode area occurs both on the microscopic level with coarse and inhomogeneous cathode microstructure and on the macroscopic level with a wide contact spacing of the current collectors. The smaller effective electrode area causes inhomogeneous current density distribution and results consequently in higher ohmic losses originating from the electrolyte and higher cathodic polarization. These losses are evaluated using La0.35Sr0.15MnO3 cathodes with different microstructures and on the ZrO2-8 mole percent Y2O3 electrolyte. The influence of current path constrictions on the ohmic and nonohmic losses is demonstrated using Pt current collectors of different geometric spacings..
30. Kazunari Sasaki, Petr Bohac, Ludwig J. Gauckler, Phase Equilibria in the System ZrO2─InO1.5, Journal of the American Ceramic Society, 10.1111/j.1151-2916.1993.tb03661.x, 76, 3, 689-698, 1993.01, Phase equilibria in the system ZrO2─InO1.5 have been investigated in the temperature range from 800° to 1700°C Up to 4 mol%, InO1.5 is soluble in t‐ZrO2 at 1500°C. The martensitic transformation temperature m→t of ZrO2 containing InO1.5 is compared with that of ZrO2 solid solutions with various other trivalent ions with different ionic radii. The diffusionless c→t′ A phase transformation is discussed. Extended solid solubility from 12.4 ± 0.8 to 56.5 ± 3 mol% InO1.5 is found at 1700°C in the cubic ZrO2 phase. The eutectoid composition and temperature for the decomposition of c‐ZrO2 solid solution into t‐ZrO2+InO1.5 solid solutions were determined. A maximum of about 1 mol% ZrO2 is soluble in bcc InO1.5 phase. Metastable supersaturation of ZrO2 in bcc InO 1.5 and conditions for phase separation are discussed..
31. K. Sasaki, T. Maruyama, T. Iseki, Helium release from neutron-irradiated SiC containing 10B isotope, Journal of Nuclear Materials, 10.1016/0022-3115(89)90604-1, 168, 3, 349-351, 1989.12.
Membership in Academic Society
  • The Society of Automotive Engineers of Japan, Inc.
  • Hydrogen Energy Systems Society of Japan
  • The Japan Society of Mechanical Engineers
  • As the Director of International Research Center for Hydrogen Energy, a ministrial award for the Kyushu University hydrogen project was given from the Miniter of the Environment.
  • Research on Degradation Mechanisms in Solid Oxide Fuel Cells
  • PEFC electrocatalysts supported on semiconducting oxides
Educational Activities
Major teaching cources:
Hydrogen Utilization Process
Energy Policy
Fundamentals in Hydrogen Engineering
Other Educational Activities
  • 2003.01.
  • 2002.01.