Fabricating hierarchically porous carbon with well-defined open pores via polymer dehalogenation for high-performance supercapacitor - Carbon4Energy

Improving specific energy under ultrahigh power has long been pursued as a challengeable topic for supercapacitors (SCs). In this work, hierarchically porous carbon (HPC) electrode materials with well-defined meso-/macro-pores are reported via the dehalogenation reaction of polyvinyl fluoride (PVDF) by NaNH2. The pore hierarchy is mainly formed because of the coupled effects from NaNH2 activation and the template/bubbling effects from byproducts. Both 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 electrode 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 benefited from the hierarchical porous structure that allows highly efficient ion diffusion.