Uniform MgCo2O4 porous nanoflakes and nanowires with superior electrochemical performance for asymmetric supercapacitors

Abstract

In this work, MgCo2O4 nanoflakes (NFs) and nanowires (NWs) on stainless steel foil (SSF) were hydrothermally prepared followed with an additional annealing conversion of the precursors. These MgCo2O4 nanomaterials possessed mesoporous structures and electrochemical tests demonstrated their battery-like feature. The MgCo2O4 were peeled off the SSF, and the NF-based powders exhibited a high specific capacity of 424.98 C g−1 at 1 A g−1, while the NW powders delivered 351.17 C g−1. An asymmetric supercapacitor (ASC) was assembled with MgCo2O4 as cathode and AC as anode, respectively, and the MgCo2O4 NFs//AC ASC possessed an excellent electrochemical performance such as a capacity up to 146.10 C g−1, a long-life cycling stability with 108.28% capacity retention over 5000 cycles at 6 A g−1, and an high energy density of 41.10 W h kg−1 at a power density of 1012.80 W kg−1. In contrast, the MgCo2O4 NWs//AC ASC exhibited a similar cycling durability and an inferior energy density of 36.97 W h kg−1. Such impressive results indicate that the mesoporous MgCo2O4 NFs and NWs may serve as promising battery-like cathode materials for the next-generation advanced supercapacitors. Besides, the present method can provide some merits including simple and cost-effective synthesis, large production, and especially the shape of MgCo2O4 is uniform and can be easily tuned by changing the reaction parameters. The current method can be extended for the preparation of other transition metal oxides (TMOs)-based electrode materials with superior performances.