Ultraflexible, High‐Strength All‐in‐One Supercapacitors With GO/PVA Xerogel Electrolyte for Completely Dry and Extremely Cold Environments

Abstract

Flexible all‐solid‐state supercapacitors using liquid or hydrogel electrolytes face liquid leakage, volatilization, and freezing issues that disrupt ion conduction. This work pioneers a graphene oxide/polyvinyl alcohol (GO/PVA) xerogel electrolyte to overcome these challenges. The three‐dimensional GO/PVA network features abundant hydrogen‐bonded structures, enabling liquid‐free proton conduction within this network. The device is fabricated via in situ growth of polyaniline on both sides of a GO/PVA hydrogel, followed by pressurized drying, which generates a well‐integrated electrode–electrolyte interface. This monolithic structure facilitates proton transport via the Grotthuss mechanism. Under completely open conditions (no encapsulation), it retains 93.7% of initial capacitance after 768 h storage and 92.6% after 6 months. At 1 mA cm −2 (a fivefold increase from 0.2 mA cm −2 ), 98.5% capacitance is retained. Benefiting from its liquid‐free nature, it achieves 715 mF cm −2 at 1 mA cm −2 and −30 °C after 6 months of storage under these open conditions, preserving 88.7% of its room‐temperature capacitance. Pristine and boric acid‐modified devices show tensile strengths of 2.8 MPa (221% strain) and 8.8 MPa (164% strain). Importantly, tensile behavior and flexibility remain unchanged even at −30 °C compared to room temperature, positioning this material as a promising candidate for flexible energy‐storage devices operating in harsh environments.