In‐situ expansion strategy towards hierarchical mesoporous carbon: Formation mechanism and application in supercapacitors
Nannan Guo, Wanxia Luo, Doudou Zhou, Mengjiao Xu, Daping Qiu, Ang Gao, Rui Ma, Rui Sheng, Dianzeng Jia, Luxiang Wang
Abstract
The microporous carbon with large surface area is widely used in supercapacitors. However, the sluggish ion transport kinetics drastically hampers the practical application. Herein, an efficient in-situ expansion strategy for the preparation of hierarchically structured mesoporous carbon is developed by the pyrolysis of sodium lignosulfonate with HCOOK. Various techniques including in-situ methods are employed and the formation mechanism of the hierarchical mesoporous structure is thus clarified. The grain refinement, crystal rearrangement and in-situ expansion enable the formation of the unique porous carbon with a high mesoporous volume, an interconnected and hierarchical porous structure and a large ion-accessible specific surface area. The specific capacitance and capacitance retention of the obtained sample reach 436 F g−1 (1 A g−1) and 64% at 100 A g−1 in the aqueous electrolyte in a three-electrode system. Moreover, the obtained sample also shows a high energy density of 41.2 Wh kg−1 in a two-electrode system using ionic liquid as electrolyte. The novel in-situ route can be extended to the synthesis of other biomass-based carbon materials for electrochemical applications.