A Ni–Co sulfide nanosheet/carbon nanotube hybrid film for high-energy and high-power flexible supercapacitors.

Flexible energy storage is the bottleneck for a variety of advanced electronic devices, and transition metal sulfides are regarded as an ideal candidate for this application due to their high capacitance, versatile microstructures, and low cost. However, to render this family of materials with high mechanical flexibility while maintaining their favorable electrochemical properties is especially challenging. Herein, we report a CNT@NiCo 2 S 4 hybrid film, in which bunches of ultrathin NiCo 2 S 4 nanosheet are firmly and uniformly anchored on a 3D CNT network. This material possesses tunable microstructures, high mechanical flexibility, good conductivity as well as lightweight, making it readily deployable in a flexible supercapacitor. Significantly, the asymmetric flexible supercapacitor based on this material possesses a high voltage output (1.8 V), a high energy/power density (59.5/34.5 Wh kg−1 at 900/18000 W kg−1), outstanding cycling stability (80.64% capacity retention after 10000 cycles), and excellent mechanical flexibility to withstand various deformations, all without sacrificing its performance. Moreover, this strategy has the potential to be extended to other metal sulfides or other carbon-substrates, which opens new avenues for the facile design and manipulation of flexible functional materials for future energy storage. Flexible, free-standing and ultralight NiCo 2 S 4 nanosheets/CNTs (NCS/CNT) films are prepared by a two-step solvothermal process. Uniform and ultrathin NiCo 2 S 4 nanosheets are intimately anchored on 3D CNTs network, retaining a rich porous structure. The as-prepared NCS/CNT hybrid film can be directly used as an electrode and delivers extraordinary electrochemical performance for flexible asymmetric supercapacitor. [Display omitted] [ABSTRACT FROM AUTHOR]