Enhanced cycling stability performance for supercapacitor application of NiCoAl-LDH nanofoam on modified graphite substrate

Abstract

The high capacitive, cost-effective, non-toxic nickel-cobalt layered double hydroxide nanofoam pseudocapacitive electrode materials doped with aluminium (NiCoAl-LDH) have been hydrothermally synthesized on the electrochemically modified graphite (G) substrate with zinc and copper (Zn/G and Cu/Zn/G). The Al3+ diffusion in the LDH during the hydrothermal synthesis resulted in an ultrathin nanofoam morphological structure well adapted to the entire surface of Zn/G and Cu/Zn/G. The high areal capacitance of the best efficient NiCoAl-LDH/Cu/Zn/G electrode of 2.17 F cm(-2) at 5 mA cm(-2) decreases to 1.83 mF cm(-2) at 75 mA cm(-2) showing an excellent rate capability of 84%. An asymmetric supercapacitor (ASC) designed with graphite as negative electrode exhibits an energy density of 29.3 Wh kg(-1) at a power density of 575 W kg(-1). It still remains at 5.6 Wh kg(-1) at a higher power density of 3477 W kg(-1) at a discharge time of 5.8 s indicating ultra-fast energy storage ability of the G//NiCoAl-LDH/Cu/Zn/G device. Its cyclic tests were also made by constructing a coin-cell-type device for industrial applications. The capacitance of the coin-cell operating within 1.6 V was protected around 100% even after over 10,000 charge-discharge cycles at the current densities up to 1.8 mA cm(-2). (C) 2021 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.