A successive ionic layer adsorption and reaction (SILAR) method to fabricate a layer-by-layer (LbL) MnO2-reduced graphene oxide assembly for supercapacitor application

A facile, cost effective and additive-free successive ionic layer adsorption and reaction (SILAR) technique is demonstrated to develop layer-by-layer (LbL) assembly of reduced graphene oxide (RGO) and MnO2 (MnO2-RGO(SILAR)) on a stainless steel current collector, for designing light-weight and small size super capacitor electrode. The transmission electron microscopy and field emission scanning electron microscopy images shows uniform distribution of RGO and MnO2 in the MnO2-RGO(SILAR). The LbL (MnO2-RGO(SILAR)) demonstrates improved physical and electrochemical properties over the hydrothermally prepared MnO2-RGO (MnO2-RGO(Hydro)). The electrochemical environment of MnO2-RGO(SILAR) is explained by constant phase element in the high frequency region, and a Warburg element in the low frequency region in the Z-View fitted Nyquist plot. The equivalent circuit of the MnO2-RGO(Hydro), displays the coexistence of EDL and constant phase element, indicating inhomogeneous distribution of MnO2 and RGO by the hydrothermal technique. An asymmetric supercapacitor device is designed with MnO2-RGO(SILAR) as positive electrode, and thermally reduced GO (TRGO) as negative electrode. The designed cell exhibits high energy density of similar to 88 Wh kg(-1), elevated power density of similar to 23,200 W kg(-1), and similar to 79% retention in capacitance after 10,000 charge-discharge cycles. (C) 2016 Elsevier B.V. All rights reserved.