Nanoconfined Supercooled Water in Hydrated Two-Dimensional Polyaniline for Sub-Zero Solid-State Zinc-Ion Hybrid Capacitor.

Solid-state electrochemical energy systems have attracted numerous attentions for their excellent performance, high safety, and low cost. Recently, ice of aqueous electrolytes is reported as a new kind solid-state electrolyte for low-temperature solid-state devices. However, the lack of kinetically favorable electrodes hampers the performance of this new class of icy electrolyte-based solid-state devices at sub-zero temperatures. In this work, a hydrated layered polyaniline cathode active material (h-LPANi) with nanoconfined supercooled water by metatungstate clusters is utilized to improve the performance of sub-zero solid-state zinc ion hybrid capacitors (ZIHCs). The interlayer confined hydrated network of h-LPANi improves kinetics, surpassing pristine polyaniline and conventional porous carbon-based active materials. At -15 °C, the solid-state iced ZIHCs with h-LPANi cathode demonstrate an areal energy density of 580.0 µWh cm -2 at 1.1 mW cm -2 and 155.7 µWh cm -2 at 43.3 mW cm -2 , surpassing other low-temperature solid-state ZIHCs with conventional cathodes.