Bulletin of the American Physical Society
APS March Meeting 2015
Volume 60, Number 1
Monday–Friday, March 2–6, 2015; San Antonio, Texas
Session B34: Electrochemical Reactions |
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Sponsoring Units: GERA Room: 210A |
Monday, March 2, 2015 11:15AM - 11:51AM |
B34.00001: Modeling the Voltage Dependence of Electrochemical Reactions at Solid-Solid and Solid-Liquid Interfaces in Batteries Invited Speaker: Kevin Leung Electrochemical reactions at electrode/electrolyte interfaces are critically dependent on the total electrochemical potential or voltage. In this presentation, we briefly review ab initio molecular dynamics (AIMD)-based estimate of voltages on graphite basal and edge planes [1], and then apply similar concepts to solid-solid interfaces relevant to lithium ion and Li-air batteries. Thin solid films on electrode surfaces, whether naturally occuring during power cycling (e.g., undesirable lithium carbonate on Li-air cathodes) or are artificially introduced, can undergo electrochemical reactions as the applied voltage varies. Here the onset of oxidation of lithium carbonate and other oxide thin films on model gold electrode surfaces is correlated with the electronic structure in the presence/absence of solvent molecules. Our predictions help determine whether oxidation first occurs at the electrode-thin film or electrolyte-thin film interface. Finally, we will critically compare the voltage estimate methodology used in the fuel cell community [2] with the lithium cohesive energy calibration method broadly applied in the battery community, and discuss why they may yield different predictions. \\[4pt] This work was supported by Nanostructures for Electrical Energy Storage (NEES), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award Number DESC0001160. Sandia National Laboratories is a multiprogram laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S.~Deparment of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000. \\[4pt] [1] K. Leung and C.M. Tenney, J. Phys. Chem. C 117, 24024 (2013).\\[0pt] [2] J. Cheng and M. Sprik, Phys. Chem. CHem. Phys. 4, 11245 (2012). [Preview Abstract] |
Monday, March 2, 2015 11:51AM - 12:03PM |
B34.00002: Carbon composites with metal nanoparticles for Alcohol fuel cells Lakshman Ventrapragada, R.S. Siddhardha, Ramakrishna Podilla, V.S. Muthukumar, Stephen Creager, A.M. Rao, Sai Sathish Ramamurthy Graphene due to its high surface area and superior conductivity has attracted wide attention from both industrial and scientific communities. We chose graphene as a substrate for metal nanoparticle deposition for fuel cell applications. There are many chemical routes for fabrication of metal-graphene composites, but they have an inherent disadvantage of low performance due to the usage of surfactants, that adsorb on their surface. Here we present a design for one pot synthesis of gold nanoparticles and simultaneous deposition on graphene with laser ablation of gold strip and functionalized graphene. In this process there are two natural advantages, the nanoparticles are synthesized without any surfactants, therefore they are pristine and subsequent impregnation on graphene is linker free. These materials are well characterized with electron microscopy to find their morphology and spectroscopic techniques like Raman, UV-Vis. for functionality. This gold nanoparticle decorated graphene composite has been tested for its electrocatalytic oxidation of alcohols for alkaline fuel cell applications. An electrode made of this composite showed good stability for more than 200 cycles of operation and reported a low onset potential of 100 mV more negative, an important factor for direct ethanol fuel cells. [Preview Abstract] |
Monday, March 2, 2015 12:03PM - 12:15PM |
B34.00003: Prediction and Characterization of MXenes for non-lithium ion battery anodes Paul Kent, Yu Xie, Houlong Zhuang, Yohan Dall'Agnese, Michael Naguib, Michel Barsoum, Yury Gogotsi Rechargeable non-lithium-ion (Na+, K+, Mg2+, Ca2+, and Al3+) batteries have attracted great attention as emerging low-cost and high energy-density technologies for energy storage applications. However, their development is hindered by the limited choice of high-performance electrode materials. Building on our previous work for lithium-ion applications, here we show that MXene nanosheets, a class of two-dimensional transition-metal carbides, may serve as high-performing anodes for non-lithium-ion batteries by combined first-principles simulations and experimental measurements. Both O-terminated and bare MXenes are shown to be promising anode materials with high capacities and good rate capabilities, while bare MXenes show better performance. Our experiments clearly demonstrate the feasibility of Na- and K-ion intercalation into terminated MXenes. Moreover, stable multilayer adsorption is predicted for Mg and Al, which significantly increases their theoretical capacities. Our results provide insight into metal ion storage mechanisms on two-dimensional materials and also suggest a route to preparing bare MXene nanosheets. [Preview Abstract] |
Monday, March 2, 2015 12:15PM - 12:27PM |
B34.00004: Positive lithiation potential on functionalized Graphene sheets Rajiv Kumar Chouhan, Pushpa Raghani Designing lithium batteries with high capacities is major challenge in the field of energy storage. As an alternative to the conventional graphitic anode with a capacity of $\sim$372$ mAhg^{-1}$, we look at the adsorption of lithium on 2D graphene oxide (GO) sheets. We have included van-der-waal's interaction in our calculation and compared with literature showing its importance in Li binding on Graphene sheets. In comparison to the negative lithiation potential in prestine graphene sheets, we were able to get positive lithiation potential by introducing functional groups such as epoxy(-O-) and hydroxyl(-OH) on graphene. Also the non-stoichiometic nature of GO provides better potential to increase the lithiation potential in compare to the defects induced graphene 2D sheet. Dramatic charge redistribution within the sheet due to presence of highly electronegative oxygen plays an important role in increasing the capacity. [Preview Abstract] |
Monday, March 2, 2015 12:27PM - 12:39PM |
B34.00005: Simulating Electric Double Layer Capacitance by Using Lattice Boltzmann Method Ning Sun, Dilip Gersappe By using the Lattice Boltzmann Method (LBM) we studied diffuse-charge dynamics in electrochemical systems. We use the LBM to solve Poisson-Nernst-Planck equations (PNP) and Modified Poisson-Nernst-Planck equations (MPNP). The isotropic permittivity of electrolyte is modeled using the Booth model. The results show that both steric effect (MPNP) and isotropic permittivity (Booth model) can have large influence on diffuse-charge dynamics, especially when electrolyte concentration or applied potential is high. This model can be applied to simulate electric double layer capacitance of super capacitors with complex geometry and also incorporate other effects such as heat convection in a modular manner. [Preview Abstract] |
Monday, March 2, 2015 12:39PM - 12:51PM |
B34.00006: ABSTRACT WITHDRAWN |
Monday, March 2, 2015 12:51PM - 1:03PM |
B34.00007: ABSTRACT WITHDRAWN |
Monday, March 2, 2015 1:03PM - 1:15PM |
B34.00008: Role of site-disorder in energy materials: case of Li$_x$Nb$_2$O$_5$ pseudocapacitor and $\beta$-Li$_3$PS$_4$ solid electrolyte P. Ganesh, Andrew A. Lubimtsev, Gopi K.P. Dathar, Jonathan Anchell, Paul R.C. Kent, Adam J. Rondinone, Bobby G. Sumpter In this study, we will present computational studies to elucidate the importance of site-disorder in energy materials. We will specifically focus on two recently discovered materials: a Li-ion intercalation pseudocapacitor Li$_x$Nb$_2$O$_5$ (Nature Materials, {\bf 12} 518 (2013)) and a Li-ion solid-electrolyte.( JACS, {\bf 135} 975 (2013)). A combination of theoretical methods, such as density functional theory (DFT) based cluster-expansion, basin hopping, {\em ab initio} molecular dynamics, and nudged-elastic-bands calculations were employed to understand the origin of intercalation pseudocapacitance in the niobate-system.( J. Materials Chem. {\bf 1}14951 (2013)). It was found that having multiple sites with similar energies for ion-adsorption, lead to a site-occupancy disorder that eventually lead to a capacitative slope in the voltage profile over the entire range of ion intercalation, as seen in experiments. A similar site-occupancy induced sublattice melting in the $\beta$-Li$_3$PS$_4$ solid-electrolyte, which when ``frozen'' to RT, lead to high Li-ion conductivity.(G.K.P.Dathar et al, submitted (2014)). Further, we will elucidate how to take advantage of this control over site-disorder to better engineer improved energy materials for batteries and fuel-cells. [Preview Abstract] |
Monday, March 2, 2015 1:15PM - 1:27PM |
B34.00009: Al-Air Batteries: Fundamental Thermodynamic Limitations from First Principles Theory Leanne D. Chen, Jens K. Noerskov, Alan C. Luntz The Al-air battery possesses high theoretical specific energy (4140 Wh/kg) and is therefore an attractive candidate for vehicle propulsion applications. However, the experimentally observed open-circuit potential is much lower than what thermodynamics predicts, and this potential loss is widely believed to be an effect of corrosion. We present a detailed study of the Al-air battery using density functional theory. The results suggest that the difference between bulk thermodynamic and surface potentials is due to both the effects of asymmetry in multi-electron transfer reactions that define the anodic dissolution of Al and, more importantly, a large chemical step inherent to the formation of bulk Al(OH)3 from surface intermediates. The former results in an energy loss of 3{\%}, while the latter accounts for 14$-$29{\%} of the total thermodynamic energy depending on the surface site where dissolution occurs. Therefore, the maximum open-circuit potential of the Al anode is only $-$1.87 V vs. SHE in the absence of thermal excitations, contrary to $-$2.34 V predicted by bulk thermodynamics at pH 14.6. This is a fundamental limitation of the system and governs the maximum output potential, which cannot be improved even if corrosion effects were completely suppressed. [Preview Abstract] |
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