Facile synthesis of ultrathin NiCo2S4 nano-petals inspired by blooming buds for high-performance supercapacitors

3D petal-like NiCo2S4 nanostructures have been fabricated via a simple, mild and efficient hydrothermal strategy and the growth mechanism of NiCo2S4 nano-petals has been investigated. Such NiCo2S4 nano-petal electrodes can deliver an ultrahigh specific capacitance of 2036.5 F g(-1) at a current density of 1 A g(-1), superior rate capability and remarkable cycle stability (94.3% of capacitance retention after 5000 cycles). The as-fabricated asymmetric supercapacitors based on NiCo2S4 nano-petals//active carbon electrodes demonstrate a high energy density of 35.6 W h kg(-1) at a power density of 819.5 W kg(-1), with both long-term cycling and high rate stabilities. Such supercapacitors have been tested to power ten LEDs (2.03 V, 20 mA) in series for around 60 minutes, indicating their great potential for practical application.