Arbitrary-Shaped, Ultrastrong, and Highly Conductive Monoliths Directly Annealed by Graphene Oxide Ionic Putties for Corrosion-Resistant Joule Heating

Compared with graphite products, graphene-assembled dense monoliths have superior mechanical, electrical, and thermal properties and show better performance in energy-related applications. However, current liquid or solid assembly methods have their own disadvantages resulting in a trade-off between dimensions and properties. Herein, inspired by ceramics technology, a direct annealing method based on graphene oxide (GO) ionic putties is developed to prepare graphene-based monoliths with both arbitrary shapes and high performance. The GO ionic putty is prepared by a vacuum rotary evaporation method from GO/ionic liquid aqueous dispersions in which the GO sheet sizes and contents are arbitrarily tunable, showing better scalability than traditional methods relying on high shear forces. The nonvolatile ionic solvent acts as the thermal medium and material precursor in the annealing process, which is different from that of the volatile solvents. Therefore, an optimal ionic putty with superior plasticity and ideal microstructure is obtained to endow the graphene-based monoliths with designable macrostructures and ultrahigh mechanical strength (190 MPa) and electrical conductivity (175 S cm–1), showing good application promise in corrosion-resistant Joule heating. These superior properties are attributed to the dense and interlocking graphene network. This work provides a scalable and simple approach for high-performance graphene-based monoliths toward practical applications.