A 3D flower-like CoNi2S4/carbon nanotube nanosheet arrays grown on Ni foam as a binder-free electrode for asymmetric supercapacitors

Flower-like CoNi2S4/multiwalled carbon nanotube (MWCNT) nanosheet arrays were synthesized on Ni foam using a facile one-step hydrothermal method with thioglycerol (TA) as the sulfur source. The prepared CoNi2S4/MWCNT on Ni foam (CoNi2S4/MWCNT/Ni) was characterized with X-ray diffraction (XRD) and Xray photoelectron spectroscopy (XPS). The electrochemical performances of CoNi2S4/MWCNT/Ni were investigated with cyclic voltammetry (CV) and galvanostatic charge/discharge (GCD). CoNi2S4/MWCNT/Ni exhibits exceptional pseudocapacitve performance with high areal capacity of 5.65C cm(-2) at 10 mA cm-2 and superior cycling stability. The areal capacity of CoNi2S4/MWCNT/Ni even increased 9% after 2000 GCD cycles at 10 mA cm(-2). An asymmetric supercapacitor (ASC) was assembled with activated carbon (AC) and CoNi2S4/ MWCNT/Ni as the negative and positive electrodes, respectively. The ASC device can provide a maximum energy density of 60.83 W h kg(-1) at 284.9 W kg(-1) and retains 85% of its initial capacity after 2000 continuous GCD cycles.