High-performance layered NiCo2S4@rGO/rGO film electrode for flexible electrochemical energy storage. (20th December 2019)

• Record Type: Journal Article
• Authors: Liu, Yue; Su, Dong; Sang, Zhiyuan; Su, Xiaohan; Chen, Han; Yan, Xiao
• Is Part Of: Electrochimica acta. Volume 328(2019)
• Publication Date: 2019-12-20
• Subjects: NiCo2S4 -- rGO-based hybrid film -- Loose layered structure -- Flexible hybrid supercapacitor; Electrochemistry -- Periodicals; Electrochemistry, Industrial -- Periodicals; 541.37
• DOI: 10.1016/j.electacta.2019.135088
• Languages: English
• ISSNs: 0013-4686

Abstract

Abstract: The rapid development of portable and wearable electronic devices requires novel energy storage devices. Flexible, high-performance electrode materials are critical for meeting the demands yet remain challenging. Here, a rationally designed flexible NiCo2 S4 @rGO/rGO film constructed with NiCo2 S4 @rGO frameworks is successfully prepared through a step-wise process (hydrothermal, freeze-drying, vacuum filtration, and then sulfurization/reduction). The NiCo2 S4 @rGO/rGO film as flexible electrode shows typical battery-type faradaic redox features and exhibits a high specific capacitance of 1100.0 F g −1 at 1 A g −1, a good rate performance of 89.1% capacity retention at 10 A g −1 coupled with long cycling stability of 90.2% after 5000 cycles. The good electrochemical performance is mainly attributed to the loose layered structure and strong interaction between NiCo2 S4 and rGO nanosheets, which enhance the diffusion of electrolyte ions/electrons and decreases intrinsic resistance and contact resistance. A flexible hybrid supercapacitor assembled using the NiCo2 S4 @rGO/rGO film as cathode and the rGO film as anode shows a high energy density of 30.0 Wh kg −1 at a power density of 857.6 W kg −1 at an extended operating voltage of 1.8 V. The method can also be readily adapted for loading other bimetallic sulfides on rGO films, indicative of its feasibility and flexibility to prepare rGO-based hybrid film for high-performance flexible electrochemical energy storage. Highlights: A flexible NiCo2 S4 @rGO/rGO film with a unique loosely-layered structure was constructed with NiCo2 S4 @rGO frameworks. The NiCo2 S4 @rGO/rGO film exhibits excellent electrochemical performances. A flexible hybrid supercapacitor delivers high energy and power density. This work provides an ideal and feasible route of constructing flexible rGO-based hybrid film electrodes.