UC San Diego

A great challenge in solid-state synthesis is the ability to predict and design reaction pathways to synthesize new materials. In order to rationally plan synthesis procedures, one must understand the reaction mechanism involving thermodynamic and kinetic forces such as diffusion, interfacial reactions, activation energies and metastable states. This work focuses on studying conversion reactions as a platform to investigate solid-state reaction kinetics, nanomaterial synthesis and energy storage applications. Conversion reactions are essentially displacement reactions in which the cations of two ionic compounds are exchanged to form a two-phase nanocomposite. They may be used for scaling synthesis procedures by lowering the activation energy of a reaction and can also serve as high-capacity battery materials due to the multiple electron transfers that occur per redox center.This work involves three parts: 1) developing an in-situ method of tracking a solid-state conversion reaction using AC impedance, 2) applying a conversion reaction to synthesize 1D nanomaterials from bulk precursors and 3) exploring the kinetics behind conversion reactions in all solid-state batteries. The first part leverages the sensitivity of AC impedance to be used as a characterization technique to help detect the onset of a reaction by measuring conductivity and using the data to provide insights into the kinetics of the reaction. The second and third parts apply conversion reactions to help tune nanomaterial synthesis and compare reaction mechanisms of iron halide conversion batteries.