Regensburg 2016 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 36: Functional materials II: Batteries II

MM 36.2: Vortrag

Mittwoch, 9. März 2016, 12:00–12:15, H53

Charge localization and energetics of Li-ion batteries cathodes from Hubbard-corrected DFT functionals — Matteo Cococcioni and •Nicola Marzari — EPFL, Lausanne, Switzerland

An accurate modeling of the electronic, magnetic and structural properties of transition-metal (TM) compounds is essential for their deployment in many emerging technologies. Unfortunately, the importance of electronic correlations makes first-principles calculations on these systems very challenging. This is particularly true for Li-ion battery materials and for all the electrochemical energy conversion and storage applications based on mixed-valence TM ions. DFT functionals augmented with corrective terms based on the Hubbard model (DFT+U) improve significantly the description of these correlated materials and have proven themselves as the standard choice when high computational efficiency is required (e.g., for screening large numbers of compounds). This work shows how an extended formulation of DFT+U, including on-site (U) and inter-site (V) interactions, improves the description of mixed-valence materials. Focusing on LixFePO4 and LixMnPO4 we discuss their structural and electronic properties in dependence of Li content. Contradicting common practice, we also show that using computed interaction parameters is actually crucial to reliably compare the energy of different Li concentrations and, in particular, to assess the thermodynamic stability of various compositions and to evaluate the voltage of the resulting battery.