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

• Published in: Electrochimica acta 2016-10, Vol.214, p.76-84
• Main Authors: Hou, Linrui, Bao, Ruiqi, Chen, Zhiyi, Rehan, Muhammad, Tong, Liuniu, Pang, Gang, Yuan, Changzhou
• Format: Article
• Language: English
• Subjects: Asymmetric supercapacitors; Hierarchical ellipsoids; Hollow mesoporous NiCo2S4; NiCo2O4; Pseudo-capacitance
• ISSN: 0013-4686; 1873-3859
• DOI: 10.1016/j.electacta.2016.08.038

Hierarchical hollow mesoporous NiCo2S4 ellipsoids were smartly fabricated, and exhibited large specific capacitances/energy density, and excellent cycling stability at high rates for advanced next-generation asymmetric supercapacitors. [Display omitted] •Hollow mesoporous NiCo2S4 ellipsoids were scalablly fabricated.•Hollow NiCo2S4 ellipsoids showed better supercapacitances than NiCo2O4.•Hollow NiCo2S4-based hybrid cell exhibited high specific energy density.•Hollow NiCo2S4-based asymmetric device owned superior cycling stability.•Underlying reasons for enhanced capacitances were comparatively unconvered. 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 NiCo2O4 (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 ∼495Fg−1 against its hollow NCO counterpart (∼185Fg−1) at the same rate of 10Ag−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 ∼187.5 Wh kg−1, and appealing cycle behaviors with a capacitance decay of ∼0.0058% per cycle over 5000 cycles at a high rate of 3Ag−1. It strongly highlights that the cost-effective HM-NCS ellipsoids would be a competitive pseudo-capacitive electrode candidate for advanced ECSs applications.