Intercorrelation between physical and electrochemical behavior of nitrogen-doping in graphene for symmetric supercapacit
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Intercorrelation between physical and electrochemical behavior of nitrogen‑doping in graphene for symmetric supercapacitor electrode Rohit Yadav1 · Prerna Joshi1 · Masanori Hara1 · Takumi Yana2 · Satoru Hashimoto2 · Masamichi Yoshimura1 Received: 17 April 2020 / Accepted: 20 August 2020 © Springer Nature Switzerland AG 2020
Abstract Graphene and heteroatom-doped graphene are potential candidates for high-performance energy storage applications, such as supercapacitors. Herein, we have studied the structure and defect generation in nitrogen-doped reduced graphene oxide (N-rGO), synthesized via pyrolysis of urea in a wide temperature range (600–900 °C). Nitrogen-doped defect densities were analyzed in detail by the deconvolution of the Raman spectrum, where we found the importance of additional I and D’’ peaks. I peak is found to be sensitive to the dopant, and D” peak is consistent with the crystallinity, which are further revealed by X-ray photoelectron spectroscopy and X-ray diffraction measurements. Synthesized N-rGO was then investigated for the supercapacitor electrode. N-rGO synthesized at 800 °C, having low crystallinity (crystallite size 3.44 nm), highest degree of reduction (C/O ratio = 23), high specific surface area (152.3 m2 g−1), and presence of both pseudocapacitive and electric double layer behavior, resulting in highest areal capacitance of 138.4 mF c m−2, lowest selfdischarge rate, and exceptional capacity retention of 121.7% after 10,000 cycles of charge–discharge. The synthesized electrode material has also been tested for a symmetric supercapacitor cell showing high specific capacitance 66.8 F g −1 in 0.5 M H2SO4 electrolyte. This study is a first of its kind of structural evaluation and Raman characterization of N-rGO for application in supercapacitor cell. Keywords Nitrogen-doped reduced graphene oxide · Symmetric supercapacitor · Raman deconvolution · Areal capacitance
1 Introduction Among energy storage devices, supercapacitors have attracted great interest since 1957, when General Electric patented and demonstrated their practical application [1]. Supercapacitors are classified into electric double-layer capacitors (EDLCs) [2], pseudocapacitors [3], and hybrid capacitors, on the basis of their charge storage mechanism. EDLC behavior is commonly shown by carbon-based
materials, where charge storage takes place via electrolyte ion intercalation inside porous electrode materials. The intercalation of ions results in the formation of an electrostatic double layer, which leads to the charging of EDLC supercapacitor materials. Among available carbon-based materials like carbon nanotubes (CNT), activated carbon, and graphene, graphene emerged as an appropriate candidate for EDLC electrode due to its high mechanical strength (Young’s
Electronic supplementary material The online version of this article (https://doi.org/10.1007/s42452-020-03401-x) contains supplementary material, which is available to authorized users. * Rohit Yadav, sd19503@toyota‑ti.ac.jp | 1Graduate School of Engin
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