Green Electrochemical Energy Storage Devices Based on Sustainable Manganese Dioxides

Abstract

Green and sustainable electrochemical energy storage (EES) devices are critical for addressing the problem of limited energy resources and environmental pollution. A series of rechargeable batteries, metal–air cells, and supercapacitors have been widely studied because of their high energy densities and considerable cycle retention. Emerging as a promising electrode material for these devices, MnO2 has drawn great attention due to its abundance, environmental sustainability, low cost, and high activity. This review provides a systematic overview of environmentally benign MnO2 syntheses and representative applications in various electrochemical storage devices including metal-ion batteries, Zn–air batteries, and supercapacitors. A major emphasis is placed on ameliorating the environmental impact of MnO2 materials via green syntheses and the eco-friendly and safe properties of advanced aqueous energy storage devices with MnO2-based electrodes. This review should provide insights into how intrinsic structure, modification of compositions or facets, and morphology influence the electrochemical performance of MnO2 electrodes. Additionally, current challenges and future research opportunities are also discussed to facilitate further improvements in this field.