Fabricating hierarchically porous carbon with well-defined open pores via polymer dehalogenation for high-performance supercapacitor

Abstract Improving specific energy of supercapacitors (SCs) at high power has been intensively investigated as a hot and challengeable topic. In this work, hierarchically porous carbon (HPC) materials with well-defined meso-/macro-pores are reported via the dehalogenation reaction of polyvinyl fluoride (PVDF) by NaNH2. The pore hierarchy is achievable mainly because of the coupled effects of NaNH2 activation and the template/bubbling effects of byproducts of NaF and NH3. Electron microscopy studies and Brunauer–Emmett–Teller (BET) measurements confirm that the structures of HPC samples contain multiple-scale pores assembled in a hierarchical pattern, and most of their volumes are contributed by mesopores. Aqueous symmetric supercapacitors (ASSCs) were fabricated using HPC-M7 materials, achieving an ultrahigh specific energy of 18.8 Wh kg−1 at specific power of 986.8 W kg−1. Remarkably, at the ultrahigh power of 14.3 kW kg−1, the HPC-ASSCs still output a very high specific energy of 16.7 Wh kg−1, which means the ASSCs can be charged or discharged within 4 s. The outstanding rate capacitive performance is mainly benefited from the hierarchical porous structure that allows highly efficient ion diffusion.