Manganese Oxide/Carbon Composites for Supercapacitors and Zinc-Air Battery Applications

The increasing global demand for sustainable and cost-effective energy storage solutions has driven extensive research into advanced materials for next-generation energy technologies. Numerous studies have been conducted in this field, demonstrating that a wide range of materials exhibit promising electrochemical performance under laboratory conditions. However, the practical implementation of these materials in real-world applications depends on balancing cost, sustainability, and efficiency. Among the various candidates, manganese oxide has gained significant attention due to its natural abundance, affordability, and excellent redox properties. MnO₂ in its multiple polymorphic forms (α, β, δ, and λ), and other manganese oxides such as MnO and Mn₃O₄, have been widely explored for supercapacitors and as electrocatalysts for zinc-air batteries. However, its practical utilization is hindered by challenges such as low electronic conductivity, a limited active site exposure, and structural instability. Recent advancements in morphological engineering and composite materials have demonstrated that integration of manganese oxide and carbon-based materials such as carbon nanotubes, nanofibers, nanosheets, graphene, and activated carbon can significantly enhance the electrochemical performance of supercapacitors. This review critically evaluates recent progress in manganese oxide/carbon composites, highlighting key strategies to optimize their energy storage capabilities while maintaining cost-effectiveness and environmental sustainability. Additionally, insights gained from manganese oxide/carbon composite offer valuable guidance for their applications in energy storage. By addressing current challenges and future directions, this work aims to provide a comprehensive understanding of manganese oxide/carbon composites and their potential in advancing next-generation supercapacitors and zinc-air batteries.