Conductive, self-healing and recyclable electrodes for dielectric elastomer generator with high energy density

Dielectric elastomer generator (DEG), consisting of highly deformable dielectric elastomer (DE) film sandwiched between two compliant electrodes, can convert mechanical energy into electrical energy. To achieve high energy harvesting performance and practical durability, electrode material with high stability of electrical conductivity (EC) and self-healing/recycling capability is required. In this study, we designed and prepared conductive rubber electrode with high EC, high stability of EC at high strain and high durability during cyclic stretching, self-healing and recycling ability for DEG by synthesizing a hydrogen bond crosslinked supramolecular network of silicone rubber (SiR-SN) followed by introducing a commercially available, highly conductive carbon black (CB) and carbon grease (CG) into SiR-SN matrix. The addition of CG composed of silicone oligomer (SO) and CB can induce the partial phase separation of polar SiR-SN and the formation of segregated conductive network, leading to the significantly enhanced EC and stability of EC at high strain. The presence of SO chains also increases the chain mobility, leading to the high durability, self-healing ability and recyclability of the electrode. Compared with CG electrode commonly used in laboratory, the energy loss at 3 kV and 400% strain of DEG using the 5 phr CB/60 phr CG/SiR-SN electrode is reduced by 83.5%, and the harvested energy density increases by 73.1%, which reaches 23 mJ/cm³, much higher than that reported in previous studies. Meanwhile, this electrode shows high self-healing efficiency of conductivity (92% at 60 °C for 4 h), and can be recycled for 5 times without negative effect on performance.