The objective of this project is to establish the scientific and engineering foundation for scalable fabrication of fractal nanoparticles, which can potentially be employed in energy storage devices to rival their highly-efficient living counterparts in nature. Fractal morphology in biological systems accounts for allometric scaling of metabolism by maximizing the internal reaction area while suppressing the increase in mass transportation path. Such an elegant balance is an important lesson we can learn from in order to improve our energy storage devices that are currently striving to simultaneously enhance energy and power densities. Currently the applications of fractal morphology in man-made energy storage devices are seriously limited by fabrication capability and high cost. In this project, a comprehensive multiscale approach is proposed to fabricate and assemble fractal energy storage devices. Specifically, high-voltage electrophoretic deposition (hvEPD) is proposed to assemble 1D nanoparticles into vertically-aligned nanoforests. The thin-film substrate of such nanoforests will then be rolled up to obtain branching nanorolls that can again be aligned into nanoforests by hvEPD. By repeated rolling and hvEPD, fractal particles with programmable heterogeneous nanocomponents can be obtained. 3D nanobatteries will be fabricated and characterized as exemplary energy storage devices in this project. Fundamental physics of the fabrication process and its scale-up will also be investigated to establish the scientific foundation for future research and development.
Successful completion of this project will enable integrated design, fabrication and application of engineered fractal systems for energy storage and conversion, such as batteries, supercapacitors, thermoelectric devices, fuel cells and solar cells. With our nation?s reliance on battery-powered devices, improvements in electrochemical energy storage devices could have a significant impact on society. The research effort will stimulate further interdisciplinary collaborative efforts to address the grand challenges raised by the current energy crisis. Education and community advancement are some of the most important outcomes of this project. Students from diverse backgrounds, especially those underrepresented in STEM, will be directly involved and trained. Research results will be widely disseminated through publications to stimulate further investigations and interdisciplinary collaborations on energy and nanotechnology.