Three-dimensional virus scaffolds for energy storage and microdevice applications

Abstract

With constantly increasing demand for lightweight power sources, electrode architectures that eliminate the need for conductive and organic additives will increase mass specific energy and power densities. The increased demand for lightweight power is coupled with increasing device miniaturization. As the scale of devices decreases, current battery technologies add mass on the same scale as the device itself. A dual functional electro-mechanical material that serves as both the device structural material and the power source would dramatically improve device integration and range for powered movement. To address the demand for lightweight power with the objective of a dual functional electro-mechanical material, the M 13 bacteriophage was used to create novel 3-dimensional nano-architectures. To synthesize 3-dimensional nanowire scaffolds, the M13 virus is covalently linked into a hydrogel that serves as a 3-dimensional bio-template for the mineralization of copper and nickel nanowires. Control of nanowire diameter, scaffold porosity, and film thickness is demonstrated. The nanowire scaffolds are found to be highly conductive and can be synthesized as free-standing films. To demonstrate the viability of the 3-dimensional nanowire networks for electrical energy storage, copper nanowires were galvanically displaced to a mixed phase copper-tin system. These tin based anodes were used for lithium rechargeable batteries and demonstrated a high storage capacity per square area and stable cycling approaching 100 cycles. To determine the viability of the 3-dimensional nanowire networks as dual functional electro-mechanical materials and the mechanical stability of processing intermediates, phage hydrogels, aerogels, and metal nanowire networks were examined with nano-indentation. The elastic moduli of the metal networks are in the range of open cell metal foams The demonstration of 3-dimensional virus-templated metal nanowire networks as electrically conductive and mechanically robust should facilitate their implementation across a broad array of device applications to include photovoltaics, catalysis, electrochromics, and fuel cells.