Energy Materials for Sustainable Development: Electrets and Magnetic Conversion/Capacitative Storage and Electrochemical Conversion
Sponsored by: ACerS Energy Materials and Systems Division
Program Organizers: Krista Carlson, University of Nevada, Reno; Armin Feldhoff, Leibniz University Hannover; Kyle Brinkman, Clemson University; Eva Hemmer, University of Ottawa; Nikola Kanas, BioSense Institute; Kjell Wiik, Norwegian University of Science and Technology; Lei Zuo, Virgina Tech; Joshua Tong, Clemson University ; Danielle Benetti, Institut National de la Recherche Scientifique; Katherine Develos-Bagarinao, National Institute of Advanced Industrial Science and Technology; Soumi Chatterjee, Aditya Birla Science & Technology Company, Ltd
Wednesday 8:00 AM
October 12, 2022
Room: 413
Location: David L. Lawrence Convention Center
Session Chair: Janusz Tobola, AGH University of Science and Technology; Amjad Almansour, NASA Glenn Research Center
8:00 AM Keynote
Electret Energy Sources Based on Electrical Conductors: Deborah Chung1; Xiang Xi1; 1State University of New York Buffalo
Electrets in the form of electrical nonconductors (ceramics and polymers) have long been addressed, but this work addresses electrets in the form of conductors (metals such as steel, and carbons such as graphite). The electret behavior of conductors stems from the carrier-atom interaction. In contrast to nonconductive electrets, conductive electrets do not require poling (since the charged state is thermodynamically stable) and allow continuous DC current to pass through. Upon short circuiting, a conductive electret discharges, with its voltage decreasing to zero. Upon subsequent open circuiting, the electret charges back (i.e., self-charge). The discharge/charge is due to capacitor discharge/charge, with the capacitance being the electret-based capacitance (electret charge divided by electret voltage), which is higher than the permittivity-based capacitance by as much as 16 orders of magnitude. This capacitor discharge notion is experimentally supported by the RC time constant for the discharge time and the CVV/2 for the discharge energy.
8:40 AM Invited
Bulk Nanostructured Oxide-metal Composites for Wind Turbines and Electric Vehicles: Javier Garay1; 1University of California San Diego
Permanent magnets (PMs) are essential to important renewable energy devices such as wind turbines and electric vehicles. Magnets with high rare earth (RE) contents such as Nd–Fe–B and Sm–Co and Pt containing phases are currently the state of the art PMs. Unfortunately, rare earth mining can environmentally detrimental, has supply chain issues and Pt is very expense. A promising solution is to use the so-called exchange-spring concept to replace expensive and threatened magnetic phases (such as REs or Pt) with more abundant and accessible materials. We present a simple, scalable synthesis route for producing exchange coupled soft/hard magnetic composite powder that outperforms pure soft and hard phase constituents. We demonstrate intimate mixtures of nanoscale hard oxide and Co–Fe (soft magnetic phase) with minimal reaction. The high-volume content of high-quality oxide/metal interfaces leads to magnetic exchange coupling in the composites.
9:00 AM Invited
Properties of Carbon Nanotube Composite Conductors for High Performance Propulsion Motors: Mike Sumption1; 1Ohio State University
Motors and generators with power densities in the 30-40 kW/kg are of great interest for electric aircraft propulsion, including both fixed wing and VTOL systems. Such advancements are important for energy sustainability. Rotating machines based on ambient Cu conductors can reach 10-20 kW/kg, but to push further, novel, lightweight conductors are of interest. Here we describe the properties so far achieved with CNT composite conductors both metallized CNT yarn and polymer yarn composites. The electrical and mechanical properties are presented for these composites. For the metallized yarns, tensile tests showed UTS up to 700 MPa, a Young’s modulus of 22.8 GPa , and a specific tensile strength as high as 146 kN*m/kg. Losses were estimated for these conductors based on a new model for composite CNT conductors. Losses due to external field and ohmic contributions were included, and compared to Cu conductors at ambient.
9:20 AM
A Thermodynamic and Properties Database for Permanent Magnetic Materials: Weiwei Zhang1; Paul Mason1; 1Thermo-Calc Software Inc.
Permanent magnets are widely used in turbines, generators, hybrid vehicles, mobile phones, and other electronic equipment that are essential to our daily lives. Thermo-Calc Software has developed a thermodynamic and properties database for rare-earth permanent magnetic materials (TCPMAG1) using the CALPHAD method. There are six elements (B-Ce-Fe-La-Nd-Pr) included in this database. 15 binary and 11 ternary systems are critically evaluated. This enables predictions to be made for multicomponent systems and alloys of industrial importance. The database can be used for a wide range of compositions from pure Nd2Fe14B to very complex rare-earth-based commercial permanent magnetic materials. It can be used for calculating phase diagrams and thermodynamic properties, predicting phase equilibria, curie temperatures and simulating solidification processes. In addition to thermodynamic data, the database includes thermophysical property data for molar volume of all phases, viscosity and surface tension of liquid.
9:40 AM
Ab Initio Modeling of Ionic and Electronic Conductivity of La2NiO4+δ Cathode Material for Solid Oxide Fuel Cell: Songge Yang1; Yu Zhong1; 1Worcester Polytechnic Institute
La2NiO4+δ exhibits a relatively high oxygen diffusivity and surface reaction activity, compatible thermal expansion coefficient with solid electrolyte and oxygen over-stoichiometry enabling the transportation of oxygen ions. The atomistic simulation technique provides detailed information concerning the diffusion mechanisms of the materials. The aim of the present study is to predict the oxygen diffusion mechanism and activation energy of migration of oxygen ions in tetragonal La2NiO4+δ through the ab initio approach. The nudged elastic band (NEB) method is adopted for the prediction of the diffusion coefficient and ionic conductivity. Additionally, the electronic conductivity of the La2NiO4+δ is predicted based on the Boltzmann transport theory. Finally, the comparisons between ab initio and experimental data are included and discussed.
10:00 AM Break
10:20 AM
A Metal-insulator Transition in a Complex Oxide at T ≥ 293K: Sepideh Akhbarifar1; 1Catholic University of America -Vitreous State Lab
Changes in electrical conductivity can be exploited in electronic devices, such as data storage and memory technology. Complex transition metal oxides and strongly correlated systems often exhibit a metal-insulator transition (MIT), induced by pressure, temperature, dopants, oxygen vacancies concentration, other defects, or phase transition. Lead-yttrium-ruthenate solid solutions were synthesized and investigated for electrical conductivity (293-575K). A MIT was discovered when doping the strongly electron correlated conductor lead ruthenate with yttrium. The MIT was independent of temperature and occurred when 10 mol% lead was replaced by yttrium. The MIT is explained by the Mott–Hubbard mechanism of electron localization. Yttrium opens a bandgap at this critical yttrium concentration. Obviously, the small lattice expansion with increasing temperature had no measurable effect on the location of the MIT.
10:40 AM Invited
Bandgap Engineering and Electrochemical Properties of Disordered LaFeO3 and Heterostructures: Uma Sharma1; Priyanka Jha1; Pardeep Jha1; Prabhakar Singh1; 1IIT (BHU) Varanasi
We systematically substituted hole (Sr) at La-site and electron (Ti) at Fe-site in LaFeO3. All the investigated samples are oxygen-rich and show orthorhombic (Pbnm) phase. La0.5Sr0.5FeO3 proves to be a robust and efficient electrode due to chronopotentiometry stability with a potential of 2 V (vs Ag/AgCl) at a higher current of 150 mA/cm2. Trap state in the case of LSFT (La0.5Sr0.5Fe0.5Ti0.5O3) shifts the Fermi level toward the conduction band, which leads to the formation of cation vacancies and makes it less stable at low currents. In our extended study, we were able to reduce these cation vacancies and least surface charge degradation by changing medium and found system stable at least for ~ 1000 h. in order to enhance the hole transport number, we intercalated LSFT with ZnO thin layer using pulsed laser deposition. Our results suggest that the band gap engineering can tailor the electrochemical behaviour of the system.