Ultrathin Nanotube/Nanowire Electrodes by Spin Spray Layer-by-Layer Assembly: A Concept for Transparent Energy Storage

Abstract

Fully integrated transparent devices require versatile architectures for energy storage, yet typical battery electrodes are thick (20-100 mu m) and composed of optically absorbent materials. Reducing the length scale of active materials, assembling them with a controllable method and minimizing electrode thickness should bring transparent batteries closer to reality. In this work, the rapid and controllable spin spray layer-by-layer (SSLbL) method is used to generate high quality networks of 1D nanomaterials: single-walled carbon nanotubes (SWNT) and vanadium pentoxide (V2O5) nanowires for anode and cathode electrodes, respectively. These ultrathin films, deposited with similar to 2 nm/bilayer precision are transparent when deposited on a transparent substrate (>87% transmittance) and electrochemically active in Li-ion cells. SSLbL-assembled ultrathin SWNT anodes and V2O5 cathodes exhibit reversible lithiation capacities of 23 and 7 mu Ah/cm(2), respectively at a current density of 5 mu A/cm(2). When these electrodes are combined in a full cell, they retain similar to 5 mu Ah/cm(2) capacity over 100 cycles, equivalent to the prelithiation capacity of the limiting V2O5 cathode. The SSLbL technique employed here to generate functional thin films is uniquely suited to the generation of transparent electrodes and of