Influence Of Electromechanical Properties Of Dielectric Elastomer Materials On Energy Harvesting Performance

Dielectric elastomer generator(DEG)uses variable capacitor principle for energy harvesting,consists of a thin dielectric elastomer(DE)film sandwiched between two compliant electrodes,can harvest energy by converting the input mechanical energy into electrical energy during a stretching-releasing cycle.The energy harvesting performance of DEG is affected by various factors such as device structure,circuit design and material performance,but,the electromechanical performance of DE materials is the essence that affects the energy harvesting performance of DEG.However,there is no systematic research on the relationship between DE material performance and energy harvesting performance.This topic firstly selects DE materials that meet the requirements of the self-made cone DEG,and then selects stretch-induced crystalline brominated butyl rubber(BIIR)and non-stretch crystalline polymethyl vinyl siloxane(PMVS)as the matrix material,the effects of the dielectric constant and elastic modulus of DE materials on the energy harvesting performance of cone DEG are revealed respectively.The specific conclusions are as follows:(1)The electromechanical performance requirements of DE materials suitable for the self-made cone DEG are proposed:low conductivity(≤10-13 S·cm-1),low dielectric loss(<10-1),high elongation at break(≥500%)and low elastic modulus.This shows that DE materials with high dielectric constant can theoretically obtain high generated energy,but the good insulation of DE materials is a key prerequisite for energy harvesting test.(2)The influence of the electromechanical performance of BIIR composites and PMVS composites on the energy harvesting performance of cone DEG has been explored.The results show that both the single-cycle generated energy and energy density are proportional to dielectric constant,and basically independent of the elastic modulus.The DE materials with high dielectric constant and low elastic modulus have high electromechanical conversion efficiency,under the premise of high tensile displacement.(3)By preparing PMVS composites with high dielectric constant,high electrical breakdown strength,low elastic modulus and high elongation at break,in this paper,the 40 phrTiO2/PMVS composite with a dielectric constant of 4.05 and an elastic modulus of 0.80 MPa can obtain the highest energy density of 28.6 mJ/g and higher conversion efficiency of 8.18%under the bias voltage U1=5.0 kV and the preset displacement Z=60 mm;higher energy density of 13.57 mJ/g and the highest conversion efficiency of 15.38%under U1=7.0 kV and Z=40 mm,which is the best energy harvesting performance of the PMVS-based cone DEG reported so far.Therefore,in order to obtain high energy density and high electromechanical conversion efficiency,it is necessary to prepare DE materials with high dielectric constant,high electrical breakdown strength,low conductivity(≤10-13 S·cm-1),low dielectric loss(<10-1),high elongation at break(≥500%),low elastic modulus and low density,which provides guidance for the design and preparation of DE materials with high energy harvesting performance.