Multi-layer-stacked Co9S8 micro/nanostructure directly anchoring on carbon cloth as a flexible electrode in supercapacitors.

Rational design and synthesis of electrode materials containing uniformly stacked lamella structures with high surface areas are attractive for efficient storage of electrochemical energy. In this work, Co9S8 clusters with a uniformly stacked lamella structure was directly anchored onto carbon cloth (CC) by an easy-to-implement chemical solution processing method, which involves the homogeneous growth of the CoCO3 precursor, promoting the formation of nanosheets during the subsequent sulfurization process. Due to the conductive substrate (CC) and special multi-layer micro/nanostructure (Co9S8), the flexible Co9S8/CC electrode, which can be tailored, bent and twisted arbitrarily without affecting its electrochemical properties, also exhibits excellent electrochemical properties with a high specific capacitance (1475.4 F g-1 at 1 A g-1), a good rate capacity (80.2% retention at 20 A g-1) and excellent cycling stability (92.9% retention over 5000 cycles). In addition, the assembled solid-state asymmetric supercapacitor device containing the fabricated Co9S8 as the positive electrode and activated carbon as the negative electrode, also exhibits a high energy density of 20.3 W h kg-1 at a power density of 22 796.1 W kg-1 and a high energy density of 33.2 W h kg-1 at a power density of 817.9 W kg-1. Because of its good electrochemical properties and flexibility, the flexible Co9S8/CC electrode material is very promising to be used in flexible supercapacitors and wearable electronic technology.