Electrochemical advancements: MnO2-based electrode materials for supercapacitors

Abstract

Supercapacitors (SCs) have emerged as a promising energy-storage technology, bridging the power and energy density gap between conventional capacitors and batteries. Their high-power density, rapid charge–discharge rates, extended cycle life, and safe operation make them well-suited for next-generation energy applications. Among the materials investigated for SC electrodes, manganese oxide (MnO₂) is particularly promising due to its multiple oxidation states, high theoretical capacitance, and wide operating potential window. This review comprehensively examines recent advancements in MnO₂-based SCs, with an emphasis on MnO₂ composites incorporating carbon materials, conducting polymers (CPs), other transition metal oxides (TMOs), and metal–organic frameworks (MOFs) and covalent organic frameworks (COFs). The synergistic effects and electrochemical performance improvements achieved through these composites are discussed in depth, highlighting strategies for stabilizing MnO₂’s cycling performance and enhancing energy storage through structural integration. Additionally, we address emerging trends and future directions in MnO₂ composite design for SC applications, underscoring their transformative potential for high-performance, scalable energy storage solutions.