Zinc influence on the structural manipulation of manganese-based spinel materials: A sustainable approach on the electrochemical performance of supercapacitor electrodes in aqueous media

Abstract

The increasing demand for energy storage devices requires sustainable practices for implementation, functionalization and recycling procedures that enable a circular economy with minimal wastes. Zinc and manganese are non-critical raw materials with an environmentally friendly character and proven merits in several energy storage solutions, amongst which supercapacitors, important electrochemical energy storage devices able to manage high-power, however lacking energy density. In this work, we demonstrate how these materials can be combined to improve the energy storage ability of manganese-based electrodes, through a simple, low-cost, and eco-friendly chemical precipitation method. The manipulation of manganese-based spinel was performed through the introduction of zinc, developing an enhanced electrochemical response in aqueous electrolyte media. A binary Mn3O4 + ZnMn2O4 phase achieved a high specific capacitance of 238 F/g at 0.5 A/g in a 1 V potential window. This material displayed 80.5 % rate capability at 10 A/g, and excellent capacitance retention (97 %) after 5000 consecutive GCD cycles. Furthermore, the work evidences that the concentration of zinc in the ZnMn2O4 structure can enlarge the active potential window up to 1.2 V, keeping high-rate reversibility. These electrodes reached a specific capacitance of 175 F/g at 0.5 A/g, 84 % rate capability at 10 A/g, and 78 % capacitance retention after 5000 consecutive GCD cycles. A comprehensive electrochemical study was performed to extract information on the energy storage mechanisms of the developed Manganese-based materials.