Comparative investigation of hollow mesoporous NiCo2S4 ellipsoids with enhanced pseudo-capacitances towards high-performance asymmetric supercapacitors

In the contribution, we explore an efficient synthetic platform to purposefully fabricate hollow mesoporous NiCo2S4 (HM-NCS) ellipsoids for advanced electrochemical supercapcitors (ECSs). Uniform hollow NiCo2S4 (NCO) as the intermidate is initially prepared by calcination, and subsequently chemically transformed into spinel HM-NCS ellipsoids through in situ anion-exchange reaction. Elaborate physicochemical and electrochemical investigations comparatively demonstrate that the resultant HM-NCS ellipsoids possess superior pseudo -capacitance of similar to 495 F g(-1) against its hollow NCO counterpart (similar to 185 F g(-1)) at the same rate of 10A g(-1), benefiting from its larger surface area, thinner porous shells, smaller internal and charge-transfer resistances, and higher-content Ni (II)/Co (II) species. Remarkably, an asymmetric supercapacitor assembled with HM-NCS ellipsoids obtains a high energy density of 28.9 Wh kg(-1) at a power density of similar to 187.5 Wh kg(-1), and appealing cycle behaviors with a capacitance decay of similar to 0.0058% per cycle over 5000 cycles at a high rate of 3 A g(-1). It strongly highlights that the cost-effective HM-NCS ellipsoids would be a competitive pseudo-capacitive electrode candidate for advanced ECSs applications. (C) 2016 Elsevier Ltd. All rights reserved.