archives@tulane.edu / This dissertation utilizes molecular theory and simulations to study thermodynamics of ions in electrolyte solutions of practical interest. The first half of this work focuses on two important electrochemical energy storage systems: Lithium ion batteries and supercapacitors based on carbon nanotube (CNT) forests. In lithium ion batteries, the characteristics of Li+ transport are studied in the solid electrolyte interphase of batteries. This study has potential applications in the design and theoretical testing of novel fast-charging batteries. The work on CNT supercapacitor focuses on the dependence of capacitance on pore spacing and electrode potentials. In the second half, the hydration of halides (fluoride and chloride) are studied using Quasi-chemical theory (QCT). Here, refinements in the implementation of QCT are pursued, leading to free energies that are in excellent agreement with experiments. This advancement should be helpful to address issues such as Hofmeister effects and selectivity in ion channels. / 1 / Ajay Muralidharan