Formation of highly porous NiCo2S4 discs with enhanced pseudocapacitive properties through sequential ion-exchange

Publication date: 5 May 2018
Source:Materials & Design, Volume 145
Author(s): Xing Yu, Mengyi Wang, Annie Gagnoud, Yves Fautrelle, Zhongming Ren, Xi Li
In this work, we have developed a sequential chemically topotactic transformation strategy to fabricate highly porous thin NiCo2S4 discs with complex crisscross pore channels through sequential in situ ion-exchange. Starting from Co3O4 discs prepared by direct pyrolysis of solid Co-glycolate discs, complex porous Co3S4 and NiCo2S4 discs are obtained after the sequential ion-exchange reactions with S²⁻ and Ni²⁺ ions, respectively. Physicochemical and electrochemical investigations demonstrate that the as-derived NiCo2S4 discs with high electrical conductivity, ion-diffusion-derived large accessible surface area and pore volume present attractive pseudocapacitive properties including remarkably high capacitivity (908Fg⁻¹ at 3Ag⁻¹), good rate capability (610Fg⁻¹ at 20Ag⁻¹) and outstanding electrochemical stability with a capacitance retention of 82% after continuous cycling for 5000cycles. Furthermore, a hybrid device using the NiCo2S4 discs and carbon-based composite as positive and negative electrodes, respectively, delivers a high energy density of 42.7Whkg⁻¹ at a power density of 375Wkg⁻¹, suggesting that the NiCo2S4 discs could be a powerful electrode platform for advanced supercapacitors.

Graphical abstract

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