Fatigue-resistant high-performance dielectric elastomer generator in alternating current method

Dielectric elastomer generator (DEG) is a solid-state electrostatic device with variable capacitance. As an energy harvester, it should be passive, high performance, and fatigue-resistant. However, no such DEGs can satisfy these requirements simultaneously as the high performance strongly depends on a high external voltage and large capacitance change, which are prone to dielectric elastomer film fatigue and failure. In this study, we developed a passive alternating current dielectric elastomer generator (AC-DEG) to reconcile the contradiction and satisfy these requirements. Based on the AC method, a high performance by structural parameters could be obtained with a small capacitance change, which avoids the large capacitance change, and consequently, fatigue and failure. The AC-DEG exhibits energy density of 111 mJ/g with an energy conversion efficiency of 51.8% and charge density of 5.6 mC/m2 per cycle at 1.5 Hz with only a two-fold capacitance change. Furthermore, the AC-DEG can maintain over 100 mJ/g and 4.6 mC/m2 per cycle in a continuous operation for over 7 days (> 1 million cycles) at 1.5 Hz. We developed an integrated device with two AC-DEGs to charge commercial Li-polymer batteries with different capacities. This study provides an effective route for development of DEGs toward practical applications and industrialization.