Interconnected Hierarchical Porous Carbon Synthesized from Freeze‐dried Celery for Supercapacitor with High Performance

With the increasing challenge of energy, resource, and environment, it is highly desired to develop renewable energy and corresponding efficient energy storage technologies basing on reproducible materials. Recently, using biomass and biotechnology to prepare electrode material for energy storage devices is gaining growing attention. Here, we use biomass, celery, as a material source and developed a new way to prepare highly qualified graphitized porous carbon. Besides, instead of direct carbonization, the celery is first freeze-dried to protect the original elements and structure of biomass. Furthermore, to sculpture more nanoscale pores in the produced material, the following carbonization process is also greatly modified by investigating proper carbonization temperature and time. Therefore, the interconnected hierarchical porous structure can be formed based on the protected original pores with size of micrometers and the newly formed pores with size of nanometers. The resulted interconnected hierarchical porous carbon is used to prepare supercapacitor electrode and exhibit excellent energy storage properties. Without any extra activating or doping process, the specific capacitance of the resulted electrode reached 350.0 F g(-1) at 1 A g(-1), which is 5.28 times of that of directly carbonized material. And the power density reached 8.0 kW kg(-1) with the energy density maintaining 16.3 Wh kg(-1).