Disordered solid electrolytes and interfaces
Next-generation batteries with high energy density and safety require Li-metal anodes to be protected by new solid-state electrolytes that are electrochemically stable and have high ionic conductivity. Our goal is to advance atomistic simulation techniques and statistical analysis of ionic dynamics, and apply them to uncover key transport mechanisms needed to design new classes of ionic conductors. By analytically analyzing correlated transport in frustrated lattices and order-disorder phase transitions, we investigate the interplay between long-range interaction, sublattice incommensurability and residual entropy that gives rise to nonlinear effects in conductivity and can be controlled by the carrier concentration and amorphization. Using the largest US supercomputer, we performed ab-initio molecular dynamics to calculate ionic conductivity and are analyzing transport mechanisms of 1,500 known Li-containing oxide crystal prototypes in order to discover new classes of materials and to identify general descriptors of fast ionic motion.
Overall performance of batteries is governed by evolution and impedance of interfaces. Our current interests are in understanding kinetic aspects of electrochemical stability and charge transport in solid electrolyte-electrode interfaces, using DFT and large-scale MD simulations.
Long cycle life of solid-state batteries requires some degree of mechanical compliance to accommodate electrochemistry-driven stresses. Polymer electrolytes are a natural ingredient due to their low processing costs and self-healing characteristics. The highly tunable and complex chemical structure of polymers make them a fertile ground for computational design. Engineering high ionic conductivity and transference numbers in these materials demands much deeper understanding of the interplay between polymer chain dynamics and electrostatic ionic interactions. Large-scale molecular dynamics simulations allow us to zoom in on microscopic details of ionic transport mechanisms and coupling between charge carriers, which is particularly strong at practically relevant salt concentrations. Our goal is to reduce computational cost of such simulations and establish rapid design protocols for inventing new families of high-performance polymer systems.