Facile Synthesis of Ni–Mn Layered Double Hydroxide Nanopetals on 3D Reduced Graphene Oxide/Ni Foam for High-Performance Supercapacitors

Abstract

In this work, the Ni–Mn layered double hydroxide (Ni–Mn LDH) nanopetals are fabricated on three-dimensional reduced graphene oxide/Ni foam (RGO/NF) by one-step hydrothermal method, in which the suspension of graphene oxide (GO) is directly reduced by nickel foam (NF) to obtain NF/RGO. The composite, which consists of interconnected Ni–Mn LDH nanopetals, forms a macroporous structure. Such an open space can promote electrolyte dispersion and ion diffusion of active substances, thus enhancing capacitance performance. Remarkable, during crystal growth, RGO can not only provide active sites for Ni–Mn LDH nanopetals, but also effectively connect Ni–Mn LDH nanopetals to NF, further promoting the electrochemical behavior of composite material. Moreover, RGO possess reasonable chemical stability which can improve the mechanical properties of the composite to obtain good stability. The experimental results show that the NF/RGO electrode material with Ni–Mn LDH nanopetals has excellent specific capacitance of 2250[Formula: see text]F[Formula: see text]g[Formula: see text] at 1[Formula: see text]A[Formula: see text]g[Formula: see text], good rate performance (the capacitance retention rate is still 64.0% at 10[Formula: see text]A[Formula: see text]g[Formula: see text] and excellent cycle life (45.1% at 10[Formula: see text]A[Formula: see text]g[Formula: see text] after 5000 cycles). NR/NM–LDH is used as the positive electrode and activated carbon is used as the negative electrode to assemble the asymmetric supercapacitor, the proper power density and energy density indicates that the NR/NM–LDH composite has great potential as an electrode material for supercapacitors.