Hello, A yearly allocation for the LCRC cluster has been requested with the following updated information: Submitter/PI: Jeffrey Greeley Project Name: DFT_corrosion Division: CNM Project title: First principles studies of lithiation and corrosion of metal and oxide surfaces Associated funding: DOE-BES Other Systems: I have access to the CNM's cluster, carbon, as a staff member. Research staff nominally split about 30% of carbon's resources, but given the recent, rapid increases in the number of staff and postdocs, this resource has become substantially strained. Science: This project uses periodic, planewave Density Functional Theory (DFT) calculations, combined with atomistic thermodynamic models, to probe both the lithiation and corrosion of metal and oxide surfaces. Lithiation and corrosion are distinct electrochemical processes (relevant to the operation of lithium ion batteries and to the durability of fuel cell electrodes, respectively), but they are also simultaneously relevant to the surface chemistry of lithium air batteries, which operate by growing, and subsequently decomposing, lithium oxide or peroxide structures on catalytic metal/oxide substrates. The primary goal of this project will be to perform detailed studies of the surface chemistry and physics of the latter (Li air battery) systems. An important secondary goal, however, will be to extend earlier work on the competition between oxidation and dissolution of platinum surfaces to alloy surfaces. These calculations, in turn, are relevant to the stability of met allic electrodes under both Li air battery and fuel cell operating conditions. Project description: For sustainable future energy needs, truly transformational technologies are needed to power both small-scale portable electronic devices, as well as medium-large scale transportation devices. While battery technology has seen improvement in the last 2-3 decades with the advent of the Li-ion battery for portable electronics, significant enhancements in battery energy density are still needed for transportation and other applications. An exciting alternative to this technology, particularly for large systems, is the Li-air battery, which may offer energy storage densities of comparable levels to that of gasoline. However, significant technical challenges relating to battery power and efficiency, battery recharge ability, and electrolyte stability must be addressed before Li-air batteries can truly compete with existing technologies. A particular catalytic challenge associated with Li-air systems concerns the performance of the Li2O2/Li2O cathode. At this electrode, oxygen combines with lithium ions and electrons migrating from the anode to produce either lithium peroxide or lithium oxide. While the formation of these oxidic species (termed “discharge” of the battery) is rapid and proceeds at voltages close to the appropriate equilibrium potential, the reverse process (decomposition of the oxidic species, or “charging” of the battery) suffers from significant kinetic inhibitions and requires large overpotentials. Most catalytic studies of Li-air focus, therefore, on finding catalytic electrode materials that facilitate oxide/peroxide decomposition and avoid fouling of the cathode due to excessive solid oxide/peroxide accumulation. In spite of a decade of research in this area, however, the fundamental atomic-scale mechanisms of Li-O2 reactions with catalytic species is poorly understood, and there is an urgent need to perform careful studies on model catalytic systems to elucidate the basic chemistry and physi cs that governs these systems. We intend to use periodic DFT calculations to study the surface catalytic chemistry of Li air batteries on transition metal surfaces. The periodic DFT calculations, in conjunction with physical-chemical descriptor models, to characterize the reaction thermodynamics and kinetics of Lix-Oy based species with single-component and binary alloys of transition metal (TM) surfaces. Binding energies and reaction barriers for a variety of intermediate and product species will be determined on the TM surfaces; these species will include Li, O, LiO, O2, LiO2, Li2O2, Li2O, Li3O2, Li2O4, Li3O4, Li4O4, and Li2. We will perform such calculations on both the low index, defect-free fcc(111) or hcp(0001) surfaces of Co, Ru, Os, Cu, Ni, Ag, Pd, Rh, Ir, Pt, and Au. Additionally, we will augment such calculations with calculations on stepped fcc(211) surfaces; these calculations will allow us to understand the effects on reaction energies of representative structures (primarily facets and edg es) of metallic nanoparticles. The DFT calculations, performed at the vacuum-solid interface, will be supplemented with simple thermodynamic corrections to estimate reaction free energy diagrams as a function of the electrode potential. The results will be used to propose rate-limiting steps and selective product distributions on the various surfaces, together with screening criteria for improved materials for control of Lix-Oy species production and decomposition. Finally, we will take calculations based on the resulting “best materials” identified in our analysis further; in this further work, we will extend our calculations to identify the thermodynamic properties of Lix-Oy-TM cluster, film, island, and bulk-like nanoparticle growth on the TM surfaces. Such work will be invaluable in identifying key mechanistic phenomena on model catalysts for lithium-air batteries. An important secondary goal of the proposed work will involve studies of oxidation and dissolution of metal alloy surfaces. This work, which is relevant to the long-term durability of both Li air and fuel cell electrodes under harsh electrochemical operating conditions, is an extension of earlier studies on the competition between oxidation and dissolution of platinum surfaces. The first step will be to determine the binding energies of atomic O and OH, as a function of coverage, on a single-crystal kinked metal surfaces. We will focus on metal overlayers (wherein a single layer of an alloying metal is deposited on a bulk metallic substrate) and will consider primarily fcc(763) kinks. Numerous configurations will be considered for each adsorbate coverage, and the lowest-energy configurations at each coverage will be input into an atomistic thermodynamic formalism (essentially a simplified Grand Canonical Monte Carlo technique) to determine the O coverage as a function of e lectrode potential. These results will then be compared to tabulated values of the equilibrium dissolution potential of the relevant overlayer metals as a function of the metal ion concentration in the surrounding solution; with this analysis, it will be possible to estimate the approximate coverages of surface O and OH that are present at the thermodynmically reversible potential on these surfaces, thereby providing important insights into the interplay between surface oxidation and platinum loss by dissolution. By studying how O and OH decorate the step edges at these higher potentials, it will also be possible to obtain semi-quantitative insight into passivation and place exchange mechanisms that may be operative in various potential ranges. These computational studies will be performed in collaboration with Nenad Markovic (ANL/MSD). The computational requirements of the proposed research will be substantial. Test calculations with the Dacapo code have indicated that the p(3x3) unit cells to be used for the Li air studies require approximately 5 hours per total geometric optimization on 24 cores on computer clusters similar to Fusion. We estimate that a total of 10 transition metals, with about 250 total optimizations required per metal, will be considered, giving a total of 300,000 requested core hours. The explicitly corrosion component of the project will also be substantial, likely requiring about 200,000 core hours. We are therefore requesting 500,000 core hours for the proposed project. Dacapo and VASP have been running successfully on Fusion, and GPAW has been recently installed on the system by John Low. Project URL: Current FY Hours Used: undetermined amount New FY Requested allocation: 500000 Justification: The computational requirements of the proposed research will be substantial. Test calculations with the Dacapo code have indicated that the p(3x3) unit cells to be used for the Li air studies require approximately 5 hours per total geometric optimization on 24 cores on computer clusters similar to Fusion. We estimate that a total of 10 transition metals, with about 250 total optimizations required per metal, will be considered, giving a total of 300,000 requested core hours. The explicitly corrosion component of the project will also be substantial, likely requiring about 200,000 core hours. We are therefore requesting 500,000 core hours for the proposed project. Thank You, The LCRC Accounts System