Development of Porous Metals by Liquid Metal Dealloying

Nanoporous metals having large surface area and unique bicontinuous structure have attracted much attention due to the excellent functional properties. Conventionally, nanoporous metals were prepared by dealloying in aqueous solution, which is a selective corrosion of less-noble component from the multicomponent alloy. However, the corrosion-based dealloying can only be applicable to synthesize noble nanoporous metals. We have recently developed an innovative dealloying method using liquid metal, termed as liquid metal dealloying, in which nanoporous metal is evolved in a liquid metal. We have successfully prepared various nanoporous less-noble metals in Ti, Nb, V, Cr, Fe, Si, and C which could not be synthesized in the aqueous solution. The developed nanoporous metals exhibited excellent performance as energy related materials. For example, nanoporous Si improved cyclic performance of the lithium-ion battery anode because the many open channels act as ideal volume expansion buffers. Nanoporous Nb significantly increased mass-specific capacitance in electrolytic capacitor because bicontinuous nanostructure was ideal for uniform formation of dielectric layer while keeping large surface area and conduction path. The liquid metal dealloying is a versatile technique that can be used to synthesize nanoporous less-noble metals, nano hetero composite materials and to modify the surface and composition of structural materials. ©2022 Japan Society of Powder and Powder Metallurgy.