Martin Z. Bazant

Particle Size Dependence of the Ionic Diffusivity

Diffusion constants are typically considered to be independent of particle size with the benefit of nanosizing materials arising solely from shortened transport paths. We show that for materials with one-dimensional atomic migration channels, the diffusion constant depends on particle size with diffusion in bulk being much slower than in nanoparticles. This model accounts for conflicting data on LiFePO(4), an important material for rechargeable lithium batteries, specifically explaining why it functions exclusively on the nanoscale.

Double Layer in Ionic Liquids: Overscreening versus Crowding

We develop a simple Landau-Ginzburg-type continuum theory of solvent-free ionic liquids and use it to predict the structure of the electrical double layer. The model captures overscreening from short-range correlations, dominant at small voltages, and steric constraints of finite ion sizes, which prevail at large voltages. Increasing the voltage gradually suppresses overscreening in favor of the crowding of counterions in a condensed inner layer near the electrode. This prediction, the ion profiles, and the capacitance-voltage dependence are consistent with recent computer simulations and experiments on room-temperature ionic liquids, using a correlation length of order the ion size.

Induced-charge electro-osmosis

We describe the general phenomenon of ‘induced-charge electro-osmosis’ (ICEO) – the nonlinear electro-osmotic slip that occurs when an applied field acts on the ionic charge it induces around a polarizable surface. Motivated by a simple physical picture, we calculate ICEO flows around conducting cylinders in steady (DC), oscillatory (AC), and suddenly applied electric fields. This picture, and these systems, represent perhaps the clearest example of nonlinear electrokinetic phenomena. We complement and verify this physically motivated approach using a matched asymptotic expansion to the electrokinetic equations in the thin-double-layer and low-potential limits. ICEO slip velocities vary as

INTERATOMIC POTENTIAL FOR SILICON DEFECTS AND DISORDERED PHASES

u_s \,{\propto}\,E_0^2 L

Environment-dependent interatomic potential for bulk silicon

, where

Suppression of Phase Separation in LiFePO4 Nanoparticles During Battery Discharge

E_0

Suppression of Phase Separation in LiFePO 4 Nanoparticles During Battery Discharge

is the field strength and

Coherency strain and the kinetics of phase separation in LiFePO4 nanoparticles.

L

Induced-charge electrophoresis of metallodielectric particles.

is a geometric length scale, and are set up on a time scale

Analysis of granular flow in a pebble-bed nuclear reactor

\tau_c \,{=}\,\lambda_D L/D