▎ 摘　　要

Electrically conductive and robust composite hydrogel films are the increasing demand for compact and portable energy storage systems and biosensor. We herein present a simple route for electrically conductive and strong graphene/poly(vinyl alcohol) (PVA) composite hydrogel films by a casting method using processable graphene sheets. Both pure PVA and graphene/PVA composite hydrogel films were characterized by various techniques including scanning electron microscopy (SEM), X-ray diffraction (XRD), electrical, and mechanical measurements. High-quality, processable graphene sheets effectively enhanced the composite's electrical conductivity; a percolation threshold was achieved at 4.6 vol% of graphene mass loading. At 10 wt% nanomaterials loading, Young's modulus, and tensile strength improved by 369% and 930%, respectively, compared with neat PVA hydrogel films. The significant reinforcement found in composite films containing water attributed to strong interface between water, high-quality graphene sheets, and PVA polymer chains. As supercapacitor electrodes, composite hydrogel film delivered a gravimetric capacitance of 9.5 F/g. This work provides a new approach for fabricating electrically conductive hydrogel films using nonconducting polymer for supercapacitor.