Sp2-carbon dominant carbonaceous materials for energy conversion and storage

Sp(2)-carbon (Sp(2)-C) based carbonaceous materials, featured by its inherent unit structural characteristics of chemical tunability, conjugated network, as well as the topological structure of the carbon-carbon double bond, have been considered as a dazzling star in both scientific research and industrial applications. Compared with defect-free Sp(2)-carbon bonded carbon materials, Sp(2)-C dominant carbonaceous materials with abundant functionalities and tunable pore structures are more attractive as a candidate for energy storage and conversion systems due to their synergistic effects of the conjugated Sp(2) carbon network and the introduced extra functions induced by defects, heteroatoms, many other structure characters, thereby resulting in the combination of the firm and flexible skeleton network, improved electron/ion transport, as well as the rich and exposed active sites. In this Review, we try to give a comprehensive overview of the latest development of Sp(2)-C dominant carbonaceous materials for energy conversion and storage. First, we provide a brief summary of the structural features of Sp(2)-C dominant carbonaceous materials. Second, the controllable synthesis of these Sp(2)-C dominant carbonaceous materials are extensively discussed according to two representative approaches: the bottom-up approach via monomer-controlled synthesis, biopolymer transformation, and chemical vapor deposition, and top-down approach involving the chemical exfoliation, electrochemical exfoliation and unzipping. Particularly, after a thorough discussion of their applications as electrode materials for energy storage and conversion applications, the mechanism and the targeted structure-property relationships of the Sp(2)-C dominant carbon materials for specific energy storage and conversion are highlighted. Finally, we draw conclusions on the rational construction and engineering of the Sp(2)-C dominant carbon materials for energy-related systems and their opportunities in the future.