Invited Presentation: Connecting Electronic Structure to Electrode Kinetics of Li-Ion Batteries

Kinetic processes within the electrodes of Li-ion batteries remain poorly understood. Lithium insertion and removal from electrode materials requires solid-state diffusion at non-dilute concentrations and is often also accompanied by a sequence of diffusional and structural phase transitions. Since these phase transformations happen rapidly at room temperature, they are difficult to characterize experimentally. First-principles statistical mechanical approaches are now capable of predicting key electronic, thermodynamic and kinetic properties of electrode and electrolyte materials. They have been especially useful in elucidating the role of chemistry and crystal structure on ionic mobility as a function of concentration in intercalation compounds. The kinetics of electrode materials becomes even more complex for reaction mechanisms that go beyond intercalation processes, such as displacement and conversion reactions. Non-intercalation reaction mechanisms in general are often accompanied by substantial hysteresis and sluggish rate capabilities. Electrode materials used in energy storage devices are also affected by a strong coupling between chemistry and mechanics. Charging and discharging of electrode materials can produce local stress intensities due to concentration gradients and misfit strain across migrating interfaces. First-principles electronic structure calculations have demonstrated that fracture properties can depend strongly on the local chemistry, making the susceptibility of electrode materials to fracture very sensitive to the state of charge. This talk will describe multi-scale approaches to predict the dynamic response of electrodes for rechargeable batteries starting from the electronic structure. It will emphasize the link to in-situ experimental observations and illustrate how multi-scale studies of the dynamic response of electrode materials can elucidate the role of chemistry and crystal structure in causing hysteresis and degradation.