Flexible and low-temperature-resistant double-network hydrogel with a bionic octopus-tentacle-like structure for integrated supercapacitor and nanogenerator sensor fabrication

Flexible and stretchable hydrogels are important components of flexible electronics; however, they are typically easily detached upon repeated high-strain stretching because of their smooth surfaces and cannot be used at subfreezing temperatures because of ice formation. To address these shortcomings, we prepared a low-temperature-resistant and flexible double-network hydrogel with a bionic octopus-tentacle-like structure composed of polyvinyl alcohol and sodium alginate. We also verified its suitability for developing high-performance, flexible, stretchable, and environmentally durable supercapacitors and nanogenerator sensors. The influence of melting temperature on the hydrogel’s surface morphology decreased the interfacial resistance. The fabricated supercapacitor demonstrated exceptional performance, with 1326.5 mF cm −2 (areal capacitance) at 1 mA cm −2 , a maximum energy and power densities of 172.3 μWh cm −2 , and 708.6 mW cm −2 , respectively, outperforming most integrated supercapacitors previously reported. The corresponding nanogenerator sensor demonstrated outstanding suitability for energy harvesting and low-temperature sensing, with potential applications in underwater information transmission using international Morse code. The results of this study paves the way for the fabrication of intelligent wearable electronics and solves the problems associated with the fabrication of flexible and low-temperature-resistant hydrogels.