AMaSiS 2021 - Abstract
Van der Ven, Anton
University of California, USA
Battery materials undergo significant chemical and dimensional changes during each charge and discharge cycle. The insertion of guest ions into electrode intercalation compounds, for example, requires cation diffusion and often leads to a variety of phase transformations that are accompanied by changes in lattice parameters. Continuum simulation approaches that rely on thermodynamic and kinetic phenomenological theories have proven invaluable in the modeling of battery behavior at the materials level. A challenge is that many of the thermodynamic and kinetic quantities that inform phenomenological theories are difficult to measure in isolation. An alternative approach is to calculate them from first principles. However, due to the importance of temperature and entropy in battery materials, it is essential that a statistical mechanics approach is used to connect the electronic structure of a battery material to its macroscopic thermodynamic and kinetic properties. In this talk I will describe how first-principles statistical mechanics approaches can be used to predict voltage curves, phase diagrams, diffusion coefficients and chemo-mechanical properties. The statistical mechanics approaches rely on effective Hamiltonians to extrapolate first-principles electronic structure methods within Monte Carlo simulations. Additional coarse graining schemes then enable a connection to be made between properties at the atomic and electronic scale to phenomenological descriptions of kinetic processes that can be modelled at the meso and continuum scales. Examples will be highlighted, including layered and spinel intercalation compounds for Li, Na, Mg and K-ion batteries as well as Wadsley-Roth intercalation compounds, which are promising anode materials.