A First-Principles Study of Electro-Mechanical Coupling in Triboelectric Nanogenerators

Kansas State University, Manhattan KS

Investigators

Abstract

The triboelectric effect, a phenomenon wherein one material becomes electrically charged after it contacts a different material through friction, has been known since the times of ancient Greece. Mechanical contact between dissimilar surfaces is a ubiquitous part of life and thus a buildup of electric charge is constantly happening. Harvesting of this buildup of electrical charge provides an opportunity for the generation of electricity for devices that operate at very small scales. The tools for understanding and capitalizing on this phenomenon have only become available in the last decade due to the advent of nanotechnology. This fundamental research will provide a theoretical framework based on complementary modeling and experiments, which will allow the research team to engineer "triboelectric nanogenerators" that are capable of harvesting significant amounts of power in a more controlled way. Triboelectric nanogenerators have demonstrated a high area-wise power density of up to 1.2 kW/m2, a volume-wise power density of up to 490 kW/m3 (compare this to the stellar fusion of hydrogen ~276.5 W/m3), and similarly a very high energy conversion efficiency of ~50-85%. Harvesting of this energy that is inherently available from dissimilar surfaces is central to this research and can potentially pay dividends to the economy and society. This research will involve many disciplines including contact mechanics, solid mechanics, materials science, electrical engineering, and manufacturing. Participation of underrepresented groups in research and pedagogy will also be facilitated and broadened in this program through direct participation and exposure. The goal of this project is to understand the fundamental mechanism of triboelectrification and the surface charge density in triboelectric nanogenerators through the lens of a first-principles investigation, both theoretically and experimentally. The research team will perform first-principles simulations in conjunction with carefully designed experiments to: (1) derive an atomistic electrodynamic theory and integrate it into simulations that are directly compared to experiments thereby establishing a baseline between theory and experiment; (2) investigate the charging mechanism of contact mode triboelectrification and correlate normal strain with the induced, bound charges; and (3) relate the charging mechanism of sliding mode triboelectrification with shear strain, surface roughness, friction cycles and harvesting efficiency.