Three-dimensional Graphene-based Composites and Two-dimensional Polymers: Synthesis and Application in Energy Storage and Conversion

A carbon sheet with single-atom thickness, graphene is unique for its nature in two-dimensional polymers (2DP). Recently, three-dimensional (3D) graphene architecture assembled from flexible 2D graphene via non-covalent interaction has attracted great attention, for the collective interaction between graphene sheets enables various functional advances while having the intrinsic properties of individual sheet well preserved. Typical macrostructures of 3D graphene involve hierarchical porosity, large specific surface area, superior mechanical strength, and excellent electrical conductivity, which endow this emerging material with great potential in catalytic, environmental, biomedical, and to the upmost importance, energy-related applications. Ever-growing concerns caused by fossil fuels about sustainability and environmental issues have urged extensive research on high-performance materials for electrochemical energy storage and conversion. Taking advantage of the controlled synthesis of novel electrochemically active nanomaterials and their efficient integration with 3D graphene framework, our group is innovatively developed several versatile strategies and successfully fabricated a series of 3D graphene composites. Carrying elaborate microstructures and synergistic effect, as-obtained materials demonstrate outstanding electrochemical performance when employed in flexible electrodes and devices such as supercapacitors, lithium/sodium-ion batteries, lithium-sulfur batteries, and electrocatalysts. Our studies have been decently recognized as effective solutions to address the impending energy problems. Meanwhile, the natural 2DP attribute of graphene has aroused great enthusiasm for rational organic synthesis of new 2DPs at the atomic or molecular level. The controllable synthesis of 2DPs with tailored molecular structure and excellent processability can promote immensely the progress of polymer synthetic chemistry. Further, it exhibits vast strength in the development of novel polymeric materials that hold desirable properties and functions rare in conventional one-dimensional polymers. Since it is challenging but meaningful in the energy arene to design and synthesize 2DPs that integrate simultaneously 2D conjugated plane, in-plane uniform micropores, and electrochemical active groups. This feature article summarizes the synthesis of 3D graphene-based composites and 2DPs progressed in our group, followed by their applications in energy storage and conversion. The contribution ends with brief discussions and outlook about the future challenges and opportunities of graphene materials and relevant research field.