Bulletin of the American Physical Society
APS March Meeting 2018
Volume 63, Number 1
Monday–Friday, March 5–9, 2018; Los Angeles, California
Session S25: Materials and Fuels for the New Energy EconomyInvited
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Sponsoring Units: GERA FIP Chair: Michelle Johannes, Naval Research Lab Room: LACC 403B |
Thursday, March 8, 2018 11:15AM - 11:51AM |
S25.00001: Quantifying the unusual anion redox activity in lithium intercalation compounds Invited Speaker: Y. Shirley Meng This work provides novel insights into the oxygen activity and its correlation with the chemical environment of transition metals at the surfaces and sub-surfaces of layered transition metal oxides in lithium ion and sodium ion batteries. The oxygen activity in battery materials are historically challenging to be analyzed due to the lack of proper techniques that can simultaneously probe the unoccupied oxygen 2p and transition metal 3d orbitals. The energy range of soft X-ray covers both the oxygen K-edge and transition metal L-edges, the combination of which can provide precise information on the local transition metal-oxygen (TM-O) octahedral crystal field. We take advantage of unique features of soft X-ray absorption spectroscopy (s-XAS) and electron energy loss spectroscopy (EELS) to investigate the differences in the oxygen activity between the classical layered oxides and Li rich layered oxides and the impact of such difference on the surrounding TM-O environment, during the first cycle and after a number of high voltage cycles. The experimental data will be carefully interpreted with the help of first principles computation. With a quantitative comparison between the classical layered oxides and lithium rich layered oxides, we hope to provide a strategy to effectively control the oxygen activities in layered oxides, especially when guest ion (Li+ and Na+) concentrations are low (high voltage range). Last but not least, we will demonstrate the important role of defects in anion redox active materials. |
Thursday, March 8, 2018 11:51AM - 12:27PM |
S25.00002: Nuclear Hydrogen Production: Enhancing the Climate Change - Nuclear Energy Nexus Invited Speaker: Ibrahim Khamis Nuclear energy is an inevitable option for effectively addressing climate change and other associated effects of global warming. Its limited lifecycle carbon emission makes nuclear energy a plausible solution when a clean-energy, low-carbon economy; and/or the increasingly forecasted demand for electricity is worldwide required. The potential of nuclear energy for climate change mitigation can be boosted when the cogeneration option is considered. Shifting to hydrogen economy is a potential solution to ensure energy security, supply of low-cost energy with environmental conservation. Nuclear power plants coupled to electrolysis, thermochemical, or hybrid water splitting plants is considered as a promising route for large-scale carbon-free hydrogen production. |
Thursday, March 8, 2018 12:27PM - 1:03PM |
S25.00003: MnxGa: Understanding a magnet in the hope of designing better magnets Invited Speaker: Dominic Ryan Generation and usage of electric power both depend on electric motors (generators are electric motors run backwards) and “electric” motors are really magnetic motors as they rely on the Lorentz force (I × B) for their action. Generating the magnetic field is key to the efficiency of the machine. For large-scale applications, copper wire wound on an iron core has been the method of choice. Cheap, reliable, but power hungry. The chance discovery of Nd2Fe14B in the late 80s led to motors with permanent magnet cores that draw zero power. Improvements in motor designs are now migrating to generators, trading up-front capital costs for long-term efficiency gains and putting pressure on permanent magnet supplies. |
Thursday, March 8, 2018 1:03PM - 1:39PM |
S25.00004: Reversible Electrochemical Cells for Fuel to and from Electricity Invited Speaker: Sossina Haile Over the past decade, the availability of electricity from sustainable energy sources has risen dramatically while the cost has fallen steeply. These factors have driven a surge in activity in the development of energy storage technologies. While much of this effort has been directed towards gridscale batteries, reversible hydrogen electrochemical cells offer untapped opportunities. In particular, electrochemical cells based on proton conducting ceramic oxides are attractive candidates for interconversion between hydrogen and electricity. When operated to produce electricity these function as fuel cells, and when operated to create hydrogen, they function as electrolysis cells. The proton conducting nature of the electrolyte provides inherent advantages in the gas flow configuration over traditional oxide cells in which the electrolyte is an oxygen ion conductor. However, despite high conductivity in protonic ceramic oxides, electrochemical performance as reported in the open literature has remained low. Moreove, the most commonly pursued electrolyte compositions suffer from poor chemical stability. We describe here recent progress achieved using a combination of three advances: a new electrolyte composition, a new air electrode, and processing methods to decrease the contact resistance between these two components. The resulting cells display exceptional power densities in fuel cell mode, and extremely high electricity-to-hydrogen conversion efficiency in electrolysis mode. In addition, the cells are extremely stable over hundreds of hours of operation. As such, protonic ceramic electrochemical cells are likely to play a major role in a sustainable energy future. |
Thursday, March 8, 2018 1:39PM - 2:15PM |
S25.00005: Novel Semiconductors for High Efficiency Photovoltaics Invited Speaker: Kirstin Alberi Monolithically-integrated III-V multijunction solar cells have the potential to reach very high efficiencies, especially for devices with 4+ junctions. Typical 3 junction solar cells are commonly grown on GaAs or Ge substrates. However, the general lack of lattice-matched III-V semiconductors with bandgaps below 1.4 eV has forced device growth to be carried out via metamorphic or multiple substrate approaches. One potential route to designing optimal low bandgap materials is to alloy GaAs with Bi. Dilute concentrations of Bi induce a strong reduction in the bandgap ($\sim$88 meV/\% Bi) with only a small change in the lattice constant. If co-doped with N, this alloy can be lattice-matched to GaAs with bandgaps spanning the range of 0 – 1.43 eV. In this talk, I will discuss the growth and physics of GaAsBi alloys. I will also highlight the promise and challenges of incorporating these materials into multijunction solar cells and the further research and development that is needed to realize high performance devices. |
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