Facile template-free synthesis of 3D hierarchical ravine-like interconnected MnCo2S4 nanosheet arrays for hybrid energy storage device

Engineering of nanostructured electrodes for enhancing their electrochemical performance is a critical issue to further development in energy storage systems. In the present study, we have developed a facile template-free method to engineer 3D hierarchical ravine-like electrode based on MnCo2S4 nanosheet arrays as an efficient material for high-performance electrochemical capacitors. The physico-chemical characteristics of ravine-like structure of MnCo2S4 nanosheets are investigated by different techniques such as X-ray diffraction (XRD), transmission electron microscopy (TEM), field-emission scanning electron microscopy (FESEM) and X-ray photoelectron spectroscopy (XPS). The as-prepared MnCo2S4 electrode exhibits an ultrahigh specific capacity of 834 C g(-1) (231 mAh g(-1)) at the current density of 1 A g(-1), excellent rate capability and good cycle performance. Thiospinel nature of the MnCo2S4 electrode and its ravine-like nanosheet structure with effective spatial confinement for the electrolyte ions and charge transportation are responsible for this remarkable performance. Furthermore, the assembled MnCo2S4//AC asymmetric device shows the maximum energy density of 57 W h kg(-1) and the highest power density of 20.8 kW kg(-1). (C) 2020 Elsevier Ltd. All rights reserved.