Multilayering VHB films for dielectric elastomer generators with improved lifetime

Abstract

Dielectric elastomer generators (DEGs) can convert mechanical energy into electricity based on variable capacitance. DEGs can potentially harvest energy from renewable energy source such as wind and ocean waves due to their light weight, low cost, and high energy density. To scale up the energy output, multiple single-layer generator units are stacked to form a multilayer DEG. The fabrication of DEGs with reliable multilayer structure having high deformability and long-term stability remains a critical challenge. We report a scalable multilayering technique to produce robust DEG stacks with circular diaphragm configuration. A 4-layer stacked VHB films showed a threefold voltage gain during constant charge operation and an estimated energy density of 100 J/kg. Furthermore, by introducing a dielectric elastomer binder between the VHB films, we demonstrate strong interlayer adhesion in the stacked DEGs, enabling long-term operation stability. As a result, a 4-layer circular diaphragm DEG survived more than 100,000 cycles of mechanical deformation between 0 and 100% area strain. Carbon nanotube (CNT) coating was used as the compliant electrode. Its resistance remains almost constant after 4000 cycles of conditioning.