Template-free preparation of layer-stacked hierarchical porous carbons from coal tar pitch for high performance all-solid-state supercapacitors

Abstract

From a practical perspective, coal tar pitch is a suitable precursor for preparing two-dimensional hierarchical porous carbons (HPCs) due to its specific components consisting of a large amount of polynuclear aromatic building blocks. However, the design and fabrication of pitch-based HPCs commonly depends on the complicated templating approaches. In this work, we first present an effective and simple self-assembly method without using templates to prepare layer-stacked hierarchical porous activated carbons (LHPCs) from coal tar pitch. It is shown that the component homogeneity of pitch precursors, the functional groups beneficial to cross-linking and the suitable heat treatment kinetic conditions are the indispensable key factors controlling the formation of layer-stacked structures. The as-obtained LHPCs have a super large BET-specific surface area of 3114.2 m² g⁻¹ and exhibit excellent electrochemical performances with a high specific capacitance of 356.8 F g⁻¹ at a current density of 0.5 A g⁻¹ in 6 M KOH. In addition, a symmetrical all-solid-state supercapacitor was assembled using LHPCs, which achieves excellent flexibility and outstanding cycling stability (up to 100 000 cycles), as well as a high energy density of 10.25 W h kg⁻¹ at a power density of 496 W kg⁻¹. This paves a new way to the controllable synthesis of activated carbons from coal tar pitch and would also be beneficial to the industrial development of carbon materials from cheap value-added by-products from coal.