Hierarchical assembled Ag2CuMnO4 nanoflakes as a novel electrode material for energy storage applications

Abstract

In this work, a novel electrode material of hierarchical assembled silver copper manganese oxide (Ag2CuMnO4) nanoflakes was successfully prepared by a hydrothermal process at temperatures of 120 and 140 ºC. Influences of hydrothermal temperatures on the structure, morphology, porosities, and electrochemical performance of the prepared samples were thoroughly investigated. At 120 ºC, the flower-like microspheres composed of smaller Ag2CuMnO4 nanoflakes delivered the specific capacitance as high as 617.06 F g−1 at a current density of 1 A g−1 with the corresponding energy density of 145.17 Wh Kg−1. By using in-situ X-ray absorption near-edge structure (XANES) measurements, the charge storage mechanisms of Ag2CuMnO4 in 3 M KOH aqueous electrolyte were revealed for the first time through the multiple redox reactions of Ag/Ag1+, Cu/Cu1+, Cu1+/Cu2+, and Mn3+/Mn4+. For practical application, the symmetric supercapacitor device was fabricated by using Ag2CuMnO4 as both positive and negative electrodes. As a result, the fabricated supercapacitor device could deliver maximum energy density and power density of 2.40 Wh Kg−1 and 60.06 W Kg−1 at 0.1 A g−1, respectively. Therefore, this work provides some new insights into the charge storage mechanisms of Ag2CuMnO4 and its potential use as novel electrode material in supercapacitors.