Advanced Materials for Energy Conversion and Storage: Functional Materials I
Sponsored by: TMS Functional Materials Division, TMS: Energy Conversion and Storage Committee
Program Organizers: Amit Pandey, LG Fuel Cell Systems Inc.

Wednesday 2:00 PM
March 1, 2017
Room: 15A
Location: San Diego Convention Ctr

Session Chair: Corinne E Packard, CSM; Ritesh Sachan, ORNL

2:00 PM  Invited
Pressure-induced Phase Transformation in Xenotime Rare-earth Orthophosphates: Corinne Packard1; 1Colorado School of Mines
    Rare-earth orthophosphates (REPO4) have been explored for use as oxidation-resistant fiber coatings in oxide-oxide ceramic matrix composites. Fiber coatings of xenotime Gd0.4Dy0.6PO4 have been shown by R.S. Hay et al. to substantially reduce fiber push-out stresses compared to monazite LaPO4 and xenotime DyPO4, and show evidence of deformation-induced phase transformation to denser phases. We use diamond anvil cell experiments with in situ Raman spectroscopy to characterize the pressure-induced phase transformation under near hydrostatic conditions in REPO4s including TbPO4, DyPO4, and solid-solution orthophosphates with effective rare-earth radius similar to Tb (GdxDy(1-x)PO4 with x=0.4, 0.5, and 0.6). The solid solutions are shown to transform at similar pressures to TbPO4 within the resolution of our study, while DyPO4 transforms at a pressure ~30% higher. Thus, the reduction in fiber push-out stress in Gd0.4Dy0.6PO4 may be partially attributable to the substantial lowering of the transformation pressure.

2:25 PM  Cancelled
Starch Mediated Syntheses of Zinc Oxide and Hydrogenated Zinc Oxide (ZnO:H) Phases: Joshua Konne1; Bright Christopher1; 1Rivers State University of Sci. & Tech.
    ZnO nanoparticles synthesized with varying starch concentrations (0.00, 0.05, 0.10, 0.15 and 0.20 %) as stabilizing agent were placed in a glass tube under mild heat and exposed to H2 (gas) for 2 mins. The XRD results of the ZnO and ZnO:H samples showed strong reflections of ZnO as the major phase with a small impurity peak of Zn(OH)2 at 2θ, 32.60° and another due to ZnO-H bond at 2θ, 29.60° for the ZnO and ZnO:H samples respectively. The estimated XRD particle sizes were 47 and 30 nm and conductivities (ethanolic) of 30.90 and 27.5 μS/cm respectively. The SEM showed control of crystallite morphologies with change in starch concentrations while EDX confirm Zn and O as constituents. UV-VIS showed strong p- and n-type absorption bands at 310 cm-1 while IR bands within the characteristic regions of 430-552 (Zn-O vibrations) and 1500-1640 cm-1 (Zn-O stretching) merged for the corresponding ZnO:H samples.

2:45 PM  
Synthesis and Characterization of Spinel Copper Cobalt Oxide Catalyst for Oxygen Evolution Reaction(OER) in Anion Exchange Membrane Electrolyzer: Kyu Hwan Lee1; Sung Mook Choi1; Myung Je Jang1; Andreas Bund2; 1Korea Institute of Matarials Science; 2Technische Universität Ilmenau
    Hydrogen (H2) is considered as an excellent energy carrier for renewable and sustainable-based energy systems mainly because of its good energy density and the reversible conversion between hydrogen and electricity. Water electrolysis has a high potential to cope with the needs of distributed hydrogen production, especially when coupled with renewable electricity sources. Comparing to Proton exchange membrane electrolyzer, anion exchange membrane electrolyzer has several advantages as use of non-precious metal oxide catalysts, high pressure operation, and high efficiency compared with other type electrolyzers. The target of this study is the development of copper cobalt oxide based non-precious catalysts with high activity via simple and efficient synthesis method. The prepared OER electrocatalysts were characterized by various physicochemical analyses. Furthermore, we carried out electrooxidation activity measurements. The synthesized CuCoO4 catalysts show a different tendency in physicochemical properties and OER activity with synthesis conditions as pH, heat treatment temperature, and drying method.

3:05 PM  
Synthesis and Processing of NaSICON/Polymer Membranes: Shan-Ju Chiang1; Caihong Liu1; Leon Shaw1; 1Wanger Institute for Sustainable Energy Research / Illinois Institute of Technology
    The development of renewable energy sources has attracted the attention of researchers. Energy storage techniques of flexible production and demand on batteries based on electrochemistry have been explored during past decades. However, the state-of-the-art developments have been impeded due to the lack of sustainable cell component materials. One way to improve the energy density is through the solid ion exchange membrane, called sodium super ionic conductor (NaSICON). The fundamental challenges in synthesizing high purity NaSICON/polymer membrane lies in achievable of porous sintered body and polymer infiltration. In this study, we demonstrate, that NaSICON/polymer membranes thinner than 50µm can be manufactured through one-step synthesis, sintering and followed by polymer infiltration. The sintering condition as well as the polymer infiltration technique of NaSICON/polymer membrane will be discussed.

3:25 PM Break

3:45 PM  Invited
Understanding the Disordered Structure in Energetic Ion Radiation Induced Fast Ion Conducting Nanofibers: Ritesh Sachan1; Yanwen Zhang1; Matthew Chisholm1; William Weber2; 1Oak Ridge National Laboratory; 2University of Tennessee
    Besides interesting features such as frustrated magnetism, ferroelectricity, photocatalysis, photoluminescence, and giant magnetoresistance, materials with the A2B2O7 pyrochlore structure have attracted significant interest as fast-ion conductors for electrolytes in solid oxide fuel cells. In the present study, we show that ionic conductivity in disordered phases of Gd2Ti2O7 is increased by 2 orders. Such disordered phases are formed in a nanofiber shape by high energy ion irradiation. Microstructure observations reveal that nanofibers consist of amorphous phase surrounded by a tensile strained disordered crystalline phase. The theoretical calculations show that the disordered phase formation under tensile strain is the necessary condition to have higher ion conductivity and it dramatically increases as a function of increasing strain. Based on the results, we establish that strain controlled phase stability and enhanced ion conductivity would open up new avenues for materials design for fast ion conducting applications.

4:10 PM  
Utilization of Silver Nanowires in Supercapacitors: Recep Yuksel1; Sahin Coskun1; Husnu Unalan1; 1Middle East Technical University
    In this work, we report on the fabrication of supercapacitors using silver nanowires and its nanocomposites with molybdenum oxide (500.7 F/g), nickel hydroxide (1165.2 F/g), polypyrrole (70.4 F/g) and some PEDOT derivatives (68.2 F/g). Highly conductive silver nanowires were utilized as the only current collectors and templates for these in-situ deposited electrode active materials. Electrochemical properties of the fabricated silver nanowire based nanocomposite supercapacitor electrodes were investigated through galvanostatic charge-discharge, cyclic voltammetry, and electrochemical impedance spectroscopy. We will present a detailed analysis of utilization of silver nanowires in the fabricated supercapacitors to underline their charge transport behavior. Our obtained results show the potential of the use of silver nanowires in energy storage devices and the structures presented in this work is highly plausible and can be easily extended to other metal nanowire and conducting polymer systems.

4:30 PM  Invited
Mapping the Kinetic Modes of Phase Transformation in Intercalation Compounds: Ming Tang1; Liang Hong1; Linsen Li2; Song Jin3; 1Rice University; 2MIT; 3University of Wisconsin-Madison
    Many important battery electrode materials undergo first-order phase transformations upon cycling. In literature, phase transformations accompanying the intercalation process are usually considered to be either bulk-transport-limited (BTL) or surface-reaction-limited (SRL). The actual mechanisms nonetheless remain inadequately understood due to challenges in direct observation of phase growth in individual particles. Using LiFePO4 as a model system, we predict from phase-field modeling that phase transformation could exhibit richer and unexpected kinetic behavior in intercalation compounds. A new hybrid mode, in which phase boundary migration is SRL or BTL along different directions, is identified. This finding is confirmed by in operando x-ray transmission microscopy, and elucidates the importance of the interplay between surface reaction and diffusion in determining the transformation rate. In particular, our study leads to a surprising prediction that lattice defects in LiFePO4, which block 1D [010] channels and reduce Li diffusion anisotropy, could benefit the rate performance of batteries.