Navaratnarajah Kuganathan

Development of rechargeable batteries for electronic appliances requires advancement of synthesizing new anode, cathode, and electrolyte materials. Li2GeO3 is a candidate anode material for use in lithium ion batteries owing to its fast Li-ion conductivity. Using advanced computational simulation techniques based on the classical potentials, we investigate the defect, diffusion, and dopant properties of Li2GeO3. Our simulation finds that the minimum energy defect process is the Li-Frenkel. The Li–Ge anti-site defect cluster is higher in energy by 0.45 eV than the Li-Frenkel. The long-range Li diffusion pathway is along the c-direction with an activation energy of 0.36 eV agreeing with the experimental observation. The most promising isovalent dopants on the Li and the Ge sites are the Na and the Si, respectively. Furthermore, the formation of lithium interstitials and oxygen vacancies can be experimentally verified by doping of Al3+ on the Ge site.

Materials are needed to preferentially remove heavy metal pollutants from waste streams. Here, atomic scale simulation, based on density functional theory, is used to predict encapsulation energies and electronic structures of the one-dimensional yttrium silicide electride (Y5Si3:e–) hosting the heavy metals such as zinc (Zn), cadmium (Cd), mercury (Hg), chromium (Cr), nickel (Ni), copper (Cu), or lead (Pb). Assuming that the metals are present as dimers in gaseous waste, encapsulation is highly exoergic for those metals with incomplete p or d electrons (Cr, Ni, Cu, and Pb). Of the heavy metals with complete d shells (Zn, Cd, and Hg), only Zn exhibits strong encapsulation. Differences in encapsulation behavior are analyzed in terms of electronic structures, electron affinities, atomic radii, and Bader charges.