Non‐Drying Hydrogel Polyelectrolytes via Polymer‐Assisted Cation Solvation‐Confinement Toward H2O for Ultrahigh‐Voltage Aqueous Micro‐Supercapacitors

among all reported pure aqueous carbon-based MSCs. Even coupling with low-voltage MXene-based microelectrodes, the microdevice still maintains a high voltage exceeding 2 V, a significant areal energy density, and an ultra-long cycle life. Impressively, after exposing PAM-HPA polyelectrolytes to an oven at 60 °C for 24 h, the constructed MSCs retain nearly 90% of their capacitance compared to non-heat-treated polyelectrolytes. This work introduces a novel approach for developing non-drying polyelectrolytes with a wide electrochemical window, boosting the development of high-performance and safe micro-power sources.