Spontaneous evolution of bicontinuous nanostructures in dealloyed Li-based systems

Dealloying, the selective dissolution of one or more of the elemental components of an alloy, is an important corrosion mechanism and a technologically relevant process used to fabricate nanoporous metals for a variety of applications including catalysis(1), sensing(2), actuation(3), supercapacitors(4) and radiation-damage-resistant materials(5). In noble-metal alloy systems for which the ambient-temperature solid-state diffusivity is minuscule, dealloying occurs at a composition-dependent critical potential above which bicontinuous nanoporous structures evolve and below which a full-coverage layer of the more-noble component forms causing the alloy surface to become passive(6,7). In contrast, for alloy systems exhibiting significant solid-state diffusive transport, our understanding of dealloying-induced morphologies and the electrochemical parameters controlling this are largely unexplored. Here, we examine dealloying of Li from Li-Sn alloys and show that depending on alloy composition, particle size and dealloying rate, all known dealloyed morphologies evolve including bicontinuous nanoporous structures and hollow core-shell particles. Furthermore, we elucidate the role of bulk diffusion in morphology evolution using chronopotentiometry and linear sweep voltammetry. Our results may have implications for lithium-ion battery development while significantly broadening the spectrum of strategies for obtaining new nanoporous materials through dealloying.