First principles studies of complex hydrides for lithium ion battery and hydrogen storage applications
"We employ density functional theory in a computational study of two energy storage systems.
In the first, we explore the thermodynamic viability of light metal hydrides as a high capacity Li-ion battery negative electrode. Given a set of solid-state and gas-phase reactants, we have determined the phase diagram in the Li-Mg-B-N-H system in the grand canonical ensemble as a function of lithium electrochemical potential. We present computational results for several new conversion reactions with predicted capacities between 2400 and 4000 mAhg⁻¹ that are thermodynamically favorable and that do not involve gas evolution. We provide experimental evidence for the reaction pathway on delithiation for the compound Li₄BN₃H₁₀ and compare with our theoretical prediction. The maximum volume increase for these materials on lithium insertion is significantly smaller than that for Si, whose 400% expansion hinders its cyclability.
In the second study, we attempt to gain understanding of recent experimental results of lithium borohydride nanoconfined in highly ordered nanoporous carbon. The carbon environment is modeled as a single sheet of graphene, and adsorption energies are calculated for nanoparticles of the constituent phases of LiBH₄ desorption processes (LiBH₄, LiH, lithium and boron). We find good agreement with previous studies of a single lithium atom adsorbed onto graphene. We predict that infiltrated LiBH₄ will decompose such that boron is trapped in carbon vacancies, and that the resulting boron doping is required to achieve negative wetting energies for the remaining LiBH₄. Desorption enthalpies are found to increase with shrinking cluster sizes, suggesting that the observed lowering of desorption temperatures is a kinetic effect although interactions with the carbon surface itself are predicted to have an overall effect of decreasing the desorption enthalpy"--Abstract, page iii.
Majzoub, Eric H.
Medvedeva, Julia E.
Ph. D. in Physics
Missouri Space Grant Consortium
Missouri University of Science and Technology
Journal article titles appearing in thesis/dissertation
- DFT predictions of high-capacity metal hydride conversion materials for Li-ion batteries
- DFT study of nanocluster lithium borohydride energetics on carbon nanoscaffolds
xi, 146 pages
© 2011 Timothy Hudson Mason, All rights reserved.
Dissertation - Restricted Access
Energy storage -- Materials
Fourier transformations -- Mathematical models
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Electronic access to the full-text of this document is restricted to Missouri S&T users. Otherwise, request this publication directly from Missouri S&T Library or contact your local library.http://merlin.lib.umsystem.edu/record=b8623337~S5al
Mason, Timothy Hudson, "First-principles studies of complex hydrides for Li-ion battery and hydrogen storage applications" (2011). Doctoral Dissertations. 1809.
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