(357c) Nanotube Forests for Electrochemical Energy Storage From Electrostatic Assembly

Electrical energy storage is increasingly important as the global need for efficient, carbon-free, sustainable energy production rises. Whether the energy comes from renewable or non-renewable sources, an efficient means of storage is needed for responsible energy consumption. Currently, lithium-ion batteries are prevalent in many of these applications because of their established reliability and superior performance relative to older technologies (i.e. Ni-Cad batteries); however, for energy storage at increasingly smaller dimensions, breakthroughs in electrode design are required. Nanostructured electrodes are poised to replace conventional two-dimensional planar electrodes and address many issues (i.e., surface area, diffusion distance, energy and power density).

Here, we combine layer-by-layer (LbL) assembly and nanotemplating to realize LbL-nanotube array cathodes containing vanadium pentoxide and polyaniline. V2O5 stores and intercalates Li+ ions and polyaniline conducts electrons while acting as a binder. Layer-by-layer assembly is performed on porous membranes, the membranes are selectively removed, and nanotube forests are left behind. The goal is to create a high surface area electrode that minimizes the diffusion resistance of Li+, which could boost energy and power density. The growth behavior of the V2O5/polyaniline assembly is monitored using UV-Vis spectroscopy and scanning force microscopy (SFM). Electrochemical properties are characterized using cyclic voltammetery. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images confirm that large areas of LbL nanotubes can be made in this fashion. Future work will assess how these nanostructured cathodes will behave electrochemically as nanotube aspect ratio is varied.