Abstract
It is generally acknowledged that the activation method and component of the precursor are of great importance for making porous carbon. In this study, four plant materials belong to one genus were selected as optimized plant material to produce hierarchical porous carbon for supercapacitors, the influence of initial structure was discussed. All the produced porous carbons have large specific surface area (higher than 2342 m2 g−1), high microporosity (more than 57%), and high pore volume (larger than 1.32 cm3 g−1). All the samples show characteristic of electrical double layer capacitance, and the onion-based porous carbon obtain highest specific capacitance of 568 F g−1 at the current density of 0.1 A g−1. With the current density rising from 1 A g−1 to 50 A g−1, the specific capacitance only decreases for 20%. After 5000 cycles, all the samples show relatively high capacitance retention (up to 97%). Two-step acid pickling has washed most impurities and directly lead to small equivalent series resistance (lower than 0.2 Ω). The samples show high power density and energy density (71 W h kg−1@180 W kg−1, 210 kW kg−1@33 W h kg−1). This study open an avenue to create high-performance hierarchical porous carbon based on plant architecture.
Highlights
It is generally acknowledged that the activation method and component of the precursor are of great importance for making porous carbon
More pores are formed because some impurities are removed (Fig. 3c).It can be seen clearly from Figs. 3d,e that the structures of vascular bundle can be preserved after activation
A conclusion can be drawn from Fig. 3 that the structure of vascular bundle can be inherited after activation, and hierarchical porous structure, which has huge potential for charge storage, can be created based on the vascular structure
Summary
It is generally acknowledged that the activation method and component of the precursor are of great importance for making porous carbon. Four plant materials belong to one genus were selected as optimized plant material to produce hierarchical porous carbon for supercapacitors, the influence of initial structure was discussed. All the produced porous carbons have large specific surface area (higher than 2342 m2 g−1), high microporosity (more than 57%), and high pore volume (larger than 1.32 cm[3] g−1). All the samples show characteristic of electrical double layer capacitance, and the onion-based porous carbon obtain highest specific capacitance of 568 F g−1 at the current density of 0.1 A g−1. This study open an avenue to create high-performance hierarchical porous carbon based on plant architecture. Many studies have already proved that some special structures of biomass precursor can be kept after preparation process. A more developed hierarchical structure can be constructed by introducing a certain amount of activate agent based on its natural structure
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