UC San Diego

Nanoporous metals, characterized by their nanoscale apertures, mechanical strength, and electrical conductivity, hold significant potential for energy storage and conversion devices. Conversion reaction synthesis (CRS) has emerged as a versatile and scalable method for fabricating various nanoporous metals. This process involves the chemical reduction of an ionic metal precursor (salt or oxide) with n-butyllithium, resulting in a Li salt-metal nanocomposite. The subsequent removal of the Li-containing product yields the nanoporous metals. To enable their energy-related applications, achieving tunable and controllable microstructures and morphologies in nanoporous metals is essential.The first part of this thesis systematically investigates how the anions in copper (Cu) compound precursors affect the morphology of nanoporous copper (NP-Cu) produced via conversion reaction synthesis (CRS). By altering the diffusion of Cu through various Li salts with different anions, the study achieves control over the dimensions of NP-Cu. Thermal annealing experiments and theoretical calculations demonstrate that Cu diffusion occurs through the bulk phase of the salt, ultimately determining the size of the Cu structures and the porosity of the resulting nanoporous metal. The thesis then explored the applications of nanoporous metals. A nanoporous nickel (NP-Ni) current collector was carefully designed with a textured surface to resist lateral creep of Li metal, while its compliant nature helps reduce stress concentrations from uneven Li deposition. These features prevent additional defects in the solid electrolyte layer, mitigating Li penetration during both fabrication and cycling. Additionally, a porous metal substrate was developed for thin-film solid oxide fuel cells (TF-SOFCs). By modifying the surface with NP-Ni and yttria-stabilized zirconia (YSZ) nanoparticles, the substrate demonstrated compatibility with the sputtering process and achieved the highest performance reported for metal-supported TF-SOFCs Overall, this dissertation provides valuable insights into the morphological control of nanoporous metals via CRS and advances their application in energy storage and conversion technologies.