Soft Hybrid Scaffold (SHS) Strategy for Realization of Ultrahigh Energy Density of Wearable Aqueous Supercapacitors

Future wearable electronics requires safe and high-energy-density supercapacitors (SCs). Commercial SCs making use of organic electrolytes show high energy density, but the flammability of the electrolyte raises serious safety concerns. Aqueous SCs, on the other hand, are very safe, but the energy density is low due to the much narrower voltage window and the difficulty of fabricating thick electrodes. A new materials strategy named soft hybrid scaffold (SHS), which allows easy buildup of ultrathick electrodes made of 3D porous pseudo-material-modified carbon networks, is reported. The carbon network provides excellent mechanical stability and electric conductivity, the hierarchically porous structures ensure rapid ionic transport, and the pseudomaterials enlarge the electrochemical window. Asymmetric aqueous SCs using SHS electrodes show higher energy density than both commercial organic SCs and literature-reported aqueous SCs, with good cycle life and mechanical flexibility. The aqueous SC device is tailorable, waterproof, and fire-retardant, representing a high safety toward practical applications.