Research Overview

Protonic Ceramic Fuel Cell

Because of the generally lower activation energy associated with proton conduction in oxides compared to oxygen ion conduction, protonic ceramic fuel cells (PCFCs) should be able to operate at lower temperatures than solid oxide fuel cells (250° to 550°C versus ≥600°C) on hydrogen and hydrocarbon fuels if fabrication challenges and suitable cathodes can be developed. We fabricated the complete sandwich structure of PCFCs directly from raw precursor oxides with only one moderate-temperature processing step through the use of sintering agents such as copper oxide. We also developed a proton-, oxygen-ion–, and electron-hole–conducting PCFC-compatible cathode material, BaCo0.4Fe0.4Zr0.1Y0.1O3-δ (BCFZY0.1), that greatly improved oxygen reduction reaction kinetics at intermediate to low temperatures. We demonstrated high performance from five different types of PCFC button cells without degradation after 1400 hours. Power densities as high as 455 milliwatts per square centimeter at 500°C on H2 and 142 milliwatts per square centimeter on CH4 were achieved, and operation was possible even at 350°C.

Triple Conduction Cathode                                                        Science publication

Selected Publications

  1. LQ Le, CH Hernandez, J Huang, Y Kim, R O’Hayre, NP Sullivan, “Performance degradation in proton-conducting ceramic fuel cell and electrolyzer stacks” J. Power Sources, 537, 231356 (2022). https://doi.org/10.1016/j.jpowsour.2022.231356
  2. L. Zhu, C. Cadigan, C. Duan, J. Huang, L. Bian, L. Le, V. Avance, R. O’Hayre, and N. Sullivan, “Improving performance and enabling reversible operation in ammonia-fed proton-conducting fuel cells via a novel Ru-B2CA ammonia catalyst”, Communications Chemistry,4, 121 (2021): https://doi.org/10.1038/s42004-021-00559-2
  3. Y. Zhang, B. Chen, D. Guan, M. Xu, R. Ran, M. Ni, W. Zhou, R. O’Hayre and Z. Shao, “Achieving High Performance and Thermo-Mechanical Compatibility in a Solid-Oxide Fuel Cell Cathode by a Thermal-Expansion Offset Approach”, Nature, 591, 246-252, (2021). https://doi.org/10.1038/s41586-021-03264-1
  4. L. Le, M.H. Hernandez, M.H. Rodriguez, L. Zhu, C. Duan, H. Ding, R. O’Hayre, N. Sullivan, “Proton-conducting ceramic fuel cells: scale up and stack integration”, J. Power Sources, 482, 228868 (2021). https://doi.org/10.1016/j.jpowsour.2020.228868
  5. C. Duan, J. Huang, N. Sullivan, R. O’Hayre, “Proton -conducting oxides for energy conversion and storage”, Applied Physics Reviews, 7 (1), 011314, (2020). doi: 10.1063/1.5135319
  6. C. Duan, R. Kee, H. Zhu, N. Sullivan, L. Zhu, L. Bian, D. Jennings, R. O’Hayre, “Highly efficient reversible protonic ceramic electrochemical cells for power generation and fuel production”, Nature Energy, 4 (3), 230-240, (2019). doi: 10.1038/s41560-019-0333-2
  7. C. Duan, R.J. Kee, H. Zhu, C. Karakaya, Y. Chen, S. Ricote, A. Jarry, E. J. Crumlin, D. Hook, R. Braun, N. P. Sullivan, R. O’Hayre, “Highly durable, coking and sulfur tolerant, fuel-flexible protonic ceramic fuel cells”, Nature, 557, 217–222 (2018); doi:10.1038/s41586-018-0082-6

Solar Thermochemical Hydrogen Production

The STCH is a two-step high temperature water splitting process where sun heat is used to reduce the oxide material to a ABO3-δ or BO2-δ, creating oxygen vacancies, followed by a lower temperature step, where steam is introduced. The material splits water, by filling back the oxygen vacancies, and produces hydrogen in a carbon-neutral way. The goal in this project we design new materials for STCH that have higher H2 production capacity than the state-of-the-art ceria, and comparable reaction kinetics. The materials are predicted by computational DFT calculations combined with materials chemistry intuition, and tested in the Stagnation Flow Reactor at Sandia National Laboratory.

two-step high temperature water splitting process graph

 

Selected Publications

  1. M.D. Sanders, A.M. Bergeson-Keller, E.N. Coker, and R.P. O’Hayre, “A Thermogravimetric Temperature-Programmed Thermal Redox Protocol for Rapid Screening of Metal Oxides for Solar Thermochemical Hydrogen Production”, Frontiers in Energy Research, 343, (2022) https://doi.org/10.3389/fenrg.2022.856943
  2. A. Bergeson-Keller, M. Sanders, and R. O’Hayre, “Reduction Thermodynamics of Sr1-xCexMnO3 and CexSr2-xMnO4 Perovskites for Solar Thermochemical Hydrogen Production”, Energy Technology, 10 (1), 2100515, (2022).
  3. SJ Heo, M Sanders, RP O’Hayre, A Zakutayev, “Double-site Ce Substitution of (Ba, Sr) MnO3 Perovskites for Solar Thermochemical Hydrogen Production”, ACS Energy Letters, 6, 3037 (2021); https://doi.org/10.1021/acsenergylett.1c01214
  4. D.R. Barcellos, F. Coury, A. Emery, M. Sanders, J. Tong, A. McDaniel, C. Wolverton, M. Kaufman and R. O’Hayre, “Phase identification of the layered perovskite CexSr2-xMnO4 and application for solar thermochemical water splitting”, Inorganic Chemistry, 58 12, 7705-7714 (2019). doi.org/10.1021/acs.inorgchem.8b03487
  5. D.R. Barcellos, M. Sanders, J. Tong, A. McDaniel and R. O’Hayre, “BaCe0.25Mn0.75O3-δ — A promising perovskite-type oxide for solar thermochemical hydrogen production”, Energy and Environmental Science, 11, 3256-3265, (2018). DOI: 10.1039/C8EE01989D

Triple Conducting Oxides for Electrochemical Energy Conversion and Storage

This research is focused on understanding the effects of transition metal doping on triple conduction behavior in perovskite oxides to manipulate this behavior for particular applications. Specifically, we are working to develop a cathode for intermediate-temperature proton conducting fuel cells.

The research is conducted mainly at NREL, where we work with Dr. Andriy Zakutayev. We use NREL’s combinatorial pulsed laser deposition facilities for synthesis and combinatorial characterization tools for high-throughput screening.

Lattice Constants

Selected Publications

  1. M. Papac, K. Talley, R. O’Hayre, A. Zakutayev, “Instrument for Spatially Resolved, Temperature Dependent Electrochemical Impedance Spectroscopy of Thin Films under Controlled Atmosphere”, Rev. Sci. Inst., 92, 6 (2021). https://doi.org/10.1063/5.0024875
  2. M. Papac, V. Stevanovic, A. Zakutayev, R. O’Hayre, “Triple Ionic-Electronic Conductors for Next-Generation Electrochemical Devices”, Nature Materials, 20, 301-313 (2021). https://doi.org/10.1038/s41563-020-00854-8
  3. C. Duan, D. Hook, Y. Chen, J. Tong, R. O’Hayre, “Zr and Y co-doped perovskite as a stable, high performance cathode for solid oxide fuel cells operating below 500 °C”, Energy & Environmental Science, 10, 176–182 (2017) DOI: 10.1039/C6EE01915C