Acetamide-assisted hydrothermal growth of NiCo double hydroxide on graphene modified Ni foam for high-performance superc
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RESEARCH ARTICLE
Acetamide‑assisted hydrothermal growth of NiCo double hydroxide on graphene modified Ni foam for high‑performance supercapacitor Yu Jun Yang1 Received: 14 April 2020 / Accepted: 17 August 2020 © Springer Nature B.V. 2020
Abstract The free-standing hierarchical flower-like NiCo-double hydroxide/reduced graphene oxide composite (NiCo-DH/RGO) on Ni foam (NiF) was synthesized with a facile two-step method. First, the growth of partially reduced graphene oxide (PRGO) membrane on NiF was achieved via the direct reduction of graphene oxide (GO) by NiF, which acted as not only the reducing agent but also the current collector. Then, the growth of high mass-loading NiCo-DH on PRGO/NiF was realized with a hydrothermal process, in which acetamide plays a crucial role. The high mass-loading of NiCo-DH is due to the addition of acetamide into the hydrothermal bath, in which PRGO reacted with the solution, containing Ni(II), Co(II), acetamide and urea, to form a thick gelatinous membrane on Ni foam. During the hydrothermal process, PRGO was further reduced to RGO while both Ni(II) and Co(II) reacted with ammonium, released by the hydrolysis of urea, to form NiCo-DH. Used as the positive electrode of supercapacitor, NiCo-DH/RGO/NiF displays an ultrahigh areal capacity of 6.15 C cm−2 at 10 mA cm−2 and 94.6% capacity retention after 1000 GCD cycles at 10 mA cm−2. An asymmetric supercapacitor (ASC) is also assembled with NiCo-DH/rGO/NiF as the positive electrode and activated carbon (AC) as the negative electrode. The ASC exhibits a prominent energy density of 61.81 Wh k g−1 at a high power density of 842.63 W kg−1. It is especially worth noting that the ASC exhibited remarkable capacity retention of 84.53% even after 1000 GCD cycles at a current density of 10 mA cm−2.
Electronic supplementary material The online version of this article (https://doi.org/10.1007/s10800-020-01473-6) contains supplementary material, which is available to authorized users. * Yu Jun Yang [email protected] 1
College of Chemical and Materials Engineering, Xuchang University, Xuchang 461000, China
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Vol.:(0123456789)
Journal of Applied Electrochemistry
Graphic abstract
Keywords Binder-free · Graphene · Supercapacitor · Double hydroxide · Hydrothermal
1 Introduction Electrochemical supercapacitors (ESC), an efficient energy storage device, have attracted great attention due to their high power density, fast charge–discharge (CD) rate and long cycling life. ECSs can be divided into two categories, double-layer supercapacitor [1, 2] and faradaic supercapacitor [3]. The chalcogenides [4–17] and hydroxides [18–44] of transition metals are the most-commonly used positive electrode materials of faradaic supercapacitors. With multiple oxidation states and rich variety of redox reactions, transition metal hydroxides have very high theoretical specific capacity. Therefore, transition metal hydroxides are considered promising positive electrode materials for faradaic supercapacitors [18–22]. A widely accepted fact is that t
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