LAUSR

A multifunctional supercapacitor based on reduced graphene oxide (rGO) hydrogels deposited onto Kevlar fibers and woven cloth is reported, which exhibits both excellent mechanical performance and electrochemical energy storage. The specific strength of rGO hydrogel–Kevlar fibers reaches 1.6 MPa m3 kg−1 and the specific capacitance is 57 F g−1 with 38.1% of rGO. Such high specific strength is comparable to one of the as‐received Kevlar fibers (2.0 MPa m3 kg−1), indicating that the gelation process does not harm the fibers. The gel‐state symmetric device based on rGO hydrogel–Kevlar cloth survives impact from a 9.1 N force from a falling metal ball as well as deformation during bending to 90°. The high specific strength is due to the Kevlar while the specific capacitance stems from the 3D interconnected macrostructure of rGO hydrogels. To demonstrate the combination of these properties, a multifunctional efficiency is introduced based on the geometric average of mechanical and energy storage properties as compared to epoxy and carbon aerogel supercapacitor, respectively. This metric predicts an optimum combination or properties at a volume ratio of Kevlar/rGO gel between 0.0008 and 0.35.