Superhydrophobic Flexible Supercapacitors Formed by Integrating Hydrogel with Functional Carbon Nanomaterials

Main observation and conclusion With the rapid development of the wearable electronics, the flexible supercapacitor with high energy density has attracted more and more attentions. From the viewpoint of outdoor and underwater application, this research tried to impart the superhydrophobicity to the flexible supercapacitors. The polyvinyl alcohol/HNO 3 hydrogel was utilized as the electrolyte, which could achieve self‐healing capability without the freezing/thawing process. Both microscale graphene and nanoscale carbon nanotubes were utilized as the electrode materials. After surface modification, the hydrophobic suspension composed of graphene and carbon nanotubes was sprayed onto the two sides of hydrogel electrolyte to construct superhydrophobic electrode. Hence, the superhydrophobicity endows the supercapacitor with outstanding self‐cleaning performance. The all‐in‐one structure endows the supercapacitor with improved capacitive ability, outstanding flexibility, good anti‐abrasion property, and reliable self‐healing capability. The combination of superhydrophobicity and flexible energy storage might have a broad application for the outdoor and underwater wearable electronics applications.