National Energy Technology Laboratory
626 Cochrans Mill Road
P.O. Box 10940, MS 922-204
Pittsburgh, PA 15236-0940
National Energy Technology Laboratory
3610 Collins Ferry Road
P.O. Box 880, MS PO3B
Morgantown, WV 26507-0880
University of Connecticut
44 Weaver Road, Unit 5233
Storrs, CT 06269-5233
DOE Share: $499,372.00
Performer Share: $124,843.00
Total Award Value: $624,215.00
Performer website: University of Connecticut - http://www.engr.uconn.edu
The University of Connecticut (UConn) team will perform an evaluation and analysis—using experimentation and computational simulation—of degradation phenomena in lanthanum manganite- and cobaltite-based cathode electrodes when exposed to air atmosphere conditions during solid oxide fuel cell (SOFC) operation. The project will examine the role of dopants, electric polarization, gas phase contaminants, oxygen stoichiometry (proportions), and A:B ratio on the long-term bulk and interfacial stability of lanthanum manganite and cobaltite cathodes. Cathode materials will be characterized to develop both initiation and propagation processes responsible for chemical and morphological changes. The role of electrode poisoning in the presence of chromium vapor will be examined using existing test facilities capable of generating a wide range of vapor pressures in humidified air.
Program Background and Project Benefits
The U.S. Department of Energy (DOE) is developing the next generation of efficient fossil fuel technologies capable of producing affordable electric power with near-zero emissions. The Solid Oxide Fuel Cell (SOFC) program at DOE’s National Energy Technology Laboratory (NETL) is focused on developing low-cost, highly efficient SOFC power systems that are capable of simultaneously producing electric power, from either natural gas or coal, with carbon capture capabilities. Research is directed towards the technologies that are critical to the commercialization of SOFC technology. To successfully complete the development of SOFC technology from the present state to the point of commercial readiness, the SOFC Program efforts are aligned into three Key Technologies:
(1) Anode, Cathode, and Electrolyte (AEC) Development
(2) Atmospheric Pressure Systems
(3) Pressurized Systems
The AEC Development Key Technology is R&D in nature whereas the other two, Atmospheric Pressure Systems and Pressurized Systems, are focused on the development, demonstration, and deployment of SOFC power systems.
The AEC Development Key Technology consists of projects that will lead to substantially improved power density, enhanced performance, reduced degradation rate, and more reliable and robust systems. Research is focused on the technologies critical to the commercialization of SOFC technology, such as cathode performance, gas seals, interconnects, failure analysis, coal contaminants, fuel processing, and balance-of-plant components. Research is conducted at universities, national laboratories, small businesses, and other R&D organizations.
This project focuses on developing an understanding of the electrical, chemical, and physical processes responsible for cathode degradation under real world air atmosphere exposure conditions. Improved cell/stack life and performance will reduce operating cost and increase efficiency, resulting in reduction in the cost of electricity and reduction of CO2 emissions from the entire platform. Specifically, this project will study the role of electrode polarization and exposure conditions on cell performance degradation, examine the role of electrode poisoning in the presence of Cr vapor, and use computational tools to theoretically deduce cathode degradation mechanisms due to air contaminants.
Project Scope and Technology Readiness Level
This project is focused on evaluation and analysis of degradation phenomena in lanthanum manganite-based cathode electrodes when exposed to 'real-world' air atmosphere conditions during SOFC systems operation by both experimentation and computational simulation. In particular, the interest is in product formation and interactions with air contaminants, dopant segregation and oxide exolution at free surfaces, cation interdiffusion and reaction products formation at the buried interfaces, interface morphology changes, lattice transformation and the development of interfacial porosity and micro-cracking and delamination from the stack repeat units. The feasibility of the mitigation approaches will also be tested in accelerated conditions enabling rapid evaluation of the cation transport and gas-solid phase interactions. Sensitive probes to measure chemical composition and phase content, in concert with high-accuracy measurements of lattice constants, will provide the first evidence of the cation diffusion-controlled reactions. Structural and morphological characterization of cathode samples will be performed using existing laboratory capabilities such as electrical impedance spectroscopy, high temperature controlled atmosphere X-ray diffractometry, hot stage field emission scanning electron microscopy, focused ion beam microscopy and micro-machining, transmission electron microscopy, Auger electron spectroscopy, and X-ray photoelectron spectroscopy (XPS) techniques. The results will be used to identify and develop initiation and progression of the interfacial and surface reactions. Thermochemical simulation of interface atomic configurations using first principle thermodynamics, density functional theory and statistical mechanics will be utilized. Generalized gradient approximation (GGA) with projector augmented wave (PAW) method as implemented in Vienna Ab initio Simulation Package (VASP) along with a small number of beyond- density functional theory DFT computations will be performed.
The Technology Readiness Level (TRL) assessment identifies the current state of readiness of the key technologies being developed under the DOE’s Clean Coal Research Program. In FY 12, this project was not assessed.
The TRL assessment process and its results including definition and description of the levels may be found in the "2012 Technology Readiness Assessment-Analysis of Active Research Portfolio".