High-performance asymmetric supercapacitors realized by copper cobalt sulfide crumpled nanoflower and N, F co-doped hierarchical nanoporous carbon polyhedron

Abstract Supercapacitors trigger tremendous interests in energy storage and conversion as they can safely provide high power density with long cycle life. However, the energy density of current supercapacitors is still restrained by microstructures and sluggish kinetics of electrode materials. Recently, zeolitic imidazolate frameworks (ZIFs) with excellent structural flexibility are demonstrated as one of promising precursors and templates to design novel supercapacitor electrode materials with high specific area and rich redox active sites. This work presents a systematic study of synthesis and characterizations of single ZIF-67-derived mesoporous copper cobalt sulfide (CuCo2S4) crumpled nanoflower and N, F co-doped hierarchical nanoporous carbon polyhedron (NFHPC). The obtained CuCo2S4 and NFHPC show superior capacitive performance due to abundant Faradic-redox active sites, efficient charge transport and excellent interfacial wettability. We further assemble an asymmetric supercapacitor based on CuCo2S4 as positive electrode and NFHPC as negative electrode. As a result, the assembled asymmetric supercapacitor achieves a high energy density of 55.1 Wh kg−1 at a power density of 799.8 W kg−1, and a long cycle life (91.1% of the initial capacitance after 5000 cycles). Our work thus provides an easy strategy to design effective electrode materials with superior performance for energy storage.