High faradaic charge storage in ZnCo2S4 film on Ni-foam with a hetero-dimensional microstructure for hybrid supercapacitor. (September 2018)

• Record Type: Journal Article
• Authors: Pramanik, Atin; Maiti, Sandipan; Dhawa, Tanumoy; Sreemany, Monjoy; Mahanty, Sourindra
• Is Part Of: Materials today energy. Volume 9(2018)
• Page Start: 416
• Page End: 427
• Publication Date: 2018-09
• Subjects: Zinc cobalt sulfide -- Solvothermal synthesis -- Electrochemical energy storage -- Faradaic electrode -- Supercapacitor; Energy development -- Periodicals; Energy industries -- Periodicals; Power resources -- Periodicals; Energy policy -- Periodicals; Energy development; Energy industries; Energy policy; Power resources; Electronic journals; Periodicals; 621.042
• DOI: 10.1016/j.mtener.2018.07.007
• Languages: English
• ISSNs: 2468-6069

Abstract

Abstract: Ternary transition metal sulfides are fast evolving as high energy density faradaic electrode material for electrochemical energy storage. Herein, we report growth of carbon doped ZnCo2 S4 directly on Ni foam by solvothermal synthetic approach whereby a marigold flower-like morphology composed of interconnected nanoflakes (thickness ∼70–90 nm) is obtained. TEM studies reveal a hetero-dimensional morphology of the nanoflakes where small nanoparticles (dia ∼10–20 nm) are evenly embedded within the 2D sheets. When tested as a faradaic electrode vs Pt in 3.0 M aqueous KOH electrolyte, remarkably high specific capacity of 1282.5 C g −1 (356.2 mAh g −1 ) could be realized at a current density of 1.0 A g −1 . The origin of high capacity could be linked to the concurrent intercalation of both K + and OH − ions from the electrolyte as suggested by ex-situ X-ray photoelectron spectroscopy (XPS) study of the electrodes at different state of charge (SOC). The developed material could withstand a very high current density of 60 A g −1 and deliver a specific capacity of 186 C g −1 (51.7 mAh g −1 ). Such excellent rate performance could be attributed to the collective approach of in-situ carbon doping, binder-free design, use of 3D current collector and the morphological advantages of 2D-3D hetero-dimensional nanostructure. Further, the practical applicability of the developed ZnCo2 S4 has been checked by fabricating two-electrode hybrid ZnCo2 S4 //KOH//AC cells which exhibit a commendable performance with an energy density of 101.4 W h kg −1 at a power density of 1.3 kW kg −1 . Even after a 50-times increase in the current density (power density 57.5 kW kg −1 ), the hybrid cell could still retain an energy density of 40.4 Wh kg −1 outperforming other metal oxide/sulfide//AC based hybrid supercapacitors reported so far. Graphical abstract: Image 1 Highlights: Solvothermal synthesis of carbon doped ZnCo2 S4 film on Ni-foam with a 2D/3D hetero-dimensional microstructure. High energy density of 101.4 W h kg −1 at a power density of 1.3 kW kg −1 in ZnCo2 S4 //AC hybrid supercapacitor cells. The faradaic electrochemical processes involve concurrent intercalation of both K + and OH − ions.