Advanced Materials for Energy Conversion and Storage VI: Energy Conversion with Emphasis on SOFC
Sponsored by: TMS Functional Materials Division, TMS: Energy Conversion and Storage Committee
Program Organizers: Jung Choi, Pacific Northwest National Laboratory; Amit Pandey, Lockheed Martin Space; Partha Mukherjee, Purdue University; Surojit Gupta, University of North Dakota; Kyle Brinkman, Clemson University; Soumendra Basu, Boston University; Paul Ohodnicki, University Of Pittsburgh
Tuesday 8:30 AM
February 25, 2020
Room: 16B
Location: San Diego Convention Ctr
Session Chair: Jung Pyung Choi, Pacific Northwest National Laboratory; Hitoshi Takamura, Tohoku University
8:30 AM Invited
Preformed Oxide Scale Chemistry and Its Influence on Local Metal Loss during Dual Atmosphere Corrosion: Michael Reisert1; Ashish Aphale1; Yoed Tsur2; Prabhakar Singh1; 1University of Connecticut; 2Technion – Israel Institute of Technology
Stainless steels, commonly used for the fabrication of cell stack and balance-of-plant (BoP) components in intermediate temperature solid oxide electrochemical systems, are subject to simultaneous exposure of a bi-polar oxidizing (cathodic) and reducing (anodic) atmosphere. This exposure condition, often termed “dual atmosphere”, has been shown to induce anomalous, localized corrosion through selective and accelerated oxidation of the base alloy. Ferritic stainless steels are seen as candidate materials for interconnects within electrochemically active cell stacks because of their matching thermal expansion coefficient with contacting ceramic cell components (electrolyte/cathode/anode). The corrosion behavior of a select ferritic stainless steel has been experimentally examined under dual atmosphere conditions. In comparison, different treatments of the steel were carried out to preform an oxide scale and observe further oxidation behavior in dual atmosphere compared to as-received steel. Scale compositions and morphologies after pre-treatment and post dual atmosphere exposure will be mentioned and discussed. Hypotheses regarding the role of dual atmosphere in enhanced oxidation and the role of pre-treatments for steels used as interconnects will be discussed.
8:50 AM Invited
Enhancing Anodic Catalytic Activity in Solid Oxide Fuel Cells by Liquid Phase Infiltration: Soumendra Basu1; Yanchen Lu1; Paul Gasper1; Boshan Mo1; Srikanth Gopalan1; Uday Pal1; 1Boston University
Infiltration of nickel (Ni) nanoparticles into anodes of solid oxide fuel cell (SOFC) leads to an increase in the triple phase boundary (TPB) density. However, the deposited Ni nanoparticles on the yttria stabilized zirconia (YSZ) grains of the anode are isolated, and the lack of an electronic pathway makes the added TPBs inactive. The role of current density in spreading these nanoparticles to activate the newly formed TPBs was studied. Additionally, co-infiltrating of Ni and gadolinium-doped ceria (GDC), a mixed ionic electronic conducting (MIEC) phase was also explored. The GDC phase connects nickel nanoparticles, enabling them to be electrochemically active and stabilizes them to mitigate coarsening during operation at high fuel utilization conditions. Electrochemical I-V and EIS results to measure performance, and fracture cross-section SEM and TEM analysis to characterize the infiltrated microstructure and quantify particle degradation, will be presented.
9:10 AM Invited
Minimizing Cr-evaporation from Balance of Plant Components by Utilizing Cost-Effective Alumina-Forming Austensic Steels: Zhipeng Zeng1; Lingfeng Zhou1; Yukinori Yamamoto2; Michael Brady2; Xingbo Liu1; 1West Virginia University; 2Oak Ridge National Laboratory
Chromium (Cr) poisoning of the cathode is one of the major degradation mechanisms encountered during long-term operation of SOFC systems. Two major sources of Cr include the metallic interconnects in the stack and balance-of-plant parts such as heat exchangers and recuperators from which Cr evaporates. We have been developing and testing AFAs to replace 310S for applications around 750°C and the Ni-based Alloy 625 for applications around 900°C to minimize Cr evaporation from BOP components. This project continues the development of a new strategy for the in-situ formation of a Cr retention layer on the surface of AFAs to protect the cathode against damage caused by Cr-poisoning. The advantages of these proprietary AFAs include improved protection against Cr-poisoning at reduced cost and the ability to get full Al- containing scale coverage even on the most challenging BOP parts such as small-diameter tubes in heat exchangers.
9:30 AM
Phase Field Simulation of Ni Coarsening in SOFC Anodes under Operating Conditions: Yinkai Lei1; Tianle Cheng1; Harry Abernathy1; Gregory Hackett1; Youhai Wen1; 1National Energy Technology Laboratory
Ni coarsening is an important degradation mechanism in the anodes of Solid Oxide Fuel Cell (SOFC). Besides temperature, the coarsening rate of Ni also depends on operating conditions such as current density and steam content. However, such conditions were not considered in most previous coarsening simulation works. In this work we developed a phase field model capable of simulating Ni coarsening under operation. The effect of current is incorporated by considering generation of steam at the reaction fronts and the diffusion of steam in the pore phase. In the meantime, the reversible reaction between Ni and Ni(OH)2 under humidity atmosphere and the diffusion of Ni(OH)2 is also taken into account. The combined model has been used to simulate the Ni coarsening in synthetic microstructures of Ni-YSZ anodes. The effect of current density and humidity on the Ni coarsening rate is discussed.
9:50 AM Invited
Reversal of Chromium Poisoning in Solid Oxide Fuel Cell Cathodes: Michelle Sugimoto1; Zhikuan Zhu1; Srikanth Gopalan1; Soumendra Basu1; Uday Pal1; 1Boston University
The goal of this work is to clean solid oxide fuel cell cathodes free of chromium-containing deposits and reverse the effects of chromium poisoning. The cell cathodes were intentionally poisoned at 800°C with chromium-containing oxide deposits by operating the cell in the presence of humidity under galvanostatic conditions. After poisoning, the cells were electrochemically cleaned by imposing an electrolytic bias of 50 to 100 mV with air containing 5-15% water vapor and the fuel (H2) containing 20-40% water vapor between 800-900°C. I-V and electrochemical impedance spectroscopy results showed improvement in cell performance and lower concentrations of the chromium deposit after cleaning. The chemical nature of the chromium deposits before and after cleaning were also analyzed using various techniques.
10:10 AM Break
10:30 AM Invited
Effect of Aluminizing on the High-temperature Oxidation Behavior of an Alumina-forming Austenitic Stainless Steel and a Chromia-forming Ni Based Alloy: Sedigheh Rashidi1; Amit Pandey1; Jung Pyung Choi2; Rajeev Gupta1; 1The University of Akron; 2Pacific Northwest National Laboratory
High-temperature oxidation resistance of Fe-Cr and Ni-Cr based alloys can be improved by adding Al to the alloy and therefor forming an external alumina scale. However, the amount of Al required to form thee alumina scale has been reported to deteriorate the mechanical properties of the alloy and therefore any surface modification technique able to enrich the surface by Al is deemed beneficial. In this study, the influence a reactive air aluminizing method was used to aluminize the surface of two alloys: 1) an alumina-forming austenitic stainless steel (AFA 25), and 2) Ni based chromia-forming alloy (H230). The high-temperature oxidation behavior of both as-received and aluminized alloys was investigated at 850 °C in dry air. X-ray diffraction analysis, scanning electron microscopy, and energy-dispersive x-ray spectroscopy, performed on the oxide scales following high-temperatureoxidation tests, revealed the composition and structure of the scale on as-received and aluminized alloys.
10:50 AM Invited
Protonic Ceramic Fuel Cells: Materials and Device Development: Kyle Brinkman1; 1Clemson University
Solid oxide fuel cells (SOFCs) efficiently convert the chemical energy in fuels into electricity. However, the elevated working temperature (800-1000 ̊C), and the long-term performance/durability are the main obstacles limiting practical applications. Proton-conducting SOFCs (H-SOFCs) has attracted increased interest in recent years due to the lower working temperatures (400-700 ̊C) and a lower activation energy for proton transport as compared to oxygen ion systems. The structure of these protonic ceramic materials, the characteristics of proton conducting mechanisms, and the materials development for electrodes (anode and cathode) based on mixed ionic-electronic conductors will be summarized. Techniques for device fabrication including a one-step phase inversion method for anode design and additive manufacturing methods for ceramic devices will be discussed.
11:10 AM Invited
Catalytic Activity of Cobalt-containing Oxides for the Cathodic Reaction of IT-SOFC: Hitoshi Takamura1; 1Tohoku University
Cobalt-containing oxides such as LSC and BSCF are well-known to exhibit a superior oxygen reduction reaction (ORR) activity at intermediate temperatures for IT-SOFC. Even though their perovskite-type structure having a large amount of highly mobile oxygen vacancies is definitely responsible for their cathode performance, the catalytic activity of cobalt element itself is not well understood. The focus of this study is then to clarify its catalytic activity at intermediate temperatures apart from the perovskite-type structure. To investigate the surface kinetics of cobalt-containing oxides, a pulse isotopic exchange technique is utilized. The role of cobalt element on ORR will be discussed with respect to the surface and electronic structures of oxides.
11:30 AM Invited
Rational Design of Diffusion-blocking Layer to Suppress Chemical Degradation of Solid Oxide Fuel Cells: Kyung Joong Yoon1; 1Korea Institute of Science And Technology
Among the various sources of performance degradation of solid oxide fuel cells, the interdiffusion between the cathode and electrolyte has been identified as a predominant factor. Herein, we demonstrate a highly reliable diffusion-blocking layer that effectively suppresses detrimental chemical interactions at elevated temperatures. The diffusion-blocking layer is constructed via a bilayer approach, in which the top and bottom layers perform individual functions to control the bulk and interfacial properties. Harnessing two types of specially designed nanoparticles for each part enables the realization of the desired film structure. Consequently, the formation of insulating phases and decomposition of the cathode are prevented, resulting in a remarkable improvement in performance and stability. The scalability and feasibility of mass production is verified via the fabrication of large cells and a multi-cell stack. The stack in which the bilayer technique is implemented exhibits a low degradation rate of 0.23 %/kh.