Publication Type Journal Article
Title Free-standing N-Graphene as conductive matrix for Ni(OH)(2) based supercapacitive electrodes
Authors Kush Kumar Upadhyay N. Bundaleska M. Abrashev N. Bundaleski O. M. N. D. Teodoro I. Fonseca Andre Mao de Ferro Rui Pedro Silva E. Tatarova Maria F. Montemor
Groups CSSE
Year 2020
Month February
Volume 334
Abstract Free-standing N-doped graphene (NG2N1O) sheets with 2.3 at. \% of nitrogen and residual oxygen content were synthesized using low-pressure microwave plasma. A composite made with Ni(OH)(2) and NG2N1O was prepared by the hydrothermal route. Physicochemical characterizations evidenced the formation of crystalline beta-phase of Ni(OH)(2) nanoplates interconnected with graphene nanosheets. The electrochemical results of N-graphene electrodes evidenced very good supercapacitive response with a high rate capability of 97\%, negligible charge transfer resistance of 0.05 Omega cm(2) and very low time constant of 50 ms. The specific capacity of the Ni(OH)(2) + NG2N1O composite increased 20\% compared to Ni(OH)(2) (107 mAh g(-1) vs. 86 mAh g(-1), respectively) and the rate capability was 75\% at current density of 10 A g(-1), higher than Ni(OH)(2) which retained only 34.4\%. The composite showed excellent stability, by retaining 92\% of its initial specific capacity after 4000 charge-discharge cycles. Furthermore, electrochemical impedance spectroscopy evidenced that graphene decreased the charge transfer resistance and diffusional contributions while enhancing the capacitive behaviour and the high-frequency response of the electrodes. An asymmetric cell was assembled using activated carbon as negative electrode and the composite as positive electrode. The cell displayed good capacitive response in a potential window of 1.8 V, in aqueous electrolyte, stored a maximum energy density of 38.64 W h kg(-1) at a power density of 450 W kg(-1) and retained 16 W h kg(-1) at a power density of 4.7 kW kg(-1). (C) 2019 Elsevier Ltd. All rights reserved.
Book Title
ISSN 0013-4686
EISSN 1873-3859
Conference Name
Bibtex ID ISI:000508560000031
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