Transition metal oxides as electrode materials for advanced energy storage – a decade of research on batteries and supercapacitors

Transition metal oxides (TMOs) have emerged as promising electrode materials for next-generation electrochemical energy storage due to their rich redox chemistry and high theoretical capacitance. However, their practical application is limited by poor conductivity, slow ion diffusion, and structural instability, which create a persistent trade-off between energy density, power capability, and cycle life. Similar challenges arise in rechargeable batteries, where TMOs face issues such as volume expansion, sluggish ion kinetics, and interfacial degradation. This review critically examines research published between 2015 and 2024, centered on a unified electrochemical framework that correlates material structure, ion transport kinetics, and charge storage mechanisms across supercapacitor and battery systems. It examines recent progress in addressing these limitations through nanoscale structural engineering, transition-metal doping, and composite formation. These strategies collectively enhance charge transport, increase electroactive surface area, and improve mechanical and structural stability under cycling. A critical assessment of recent literature highlights the consistent effectiveness of these approaches across supercapacitors and various battery chemistries. The review concludes by identifying key challenges in scalability, electrode design, and device integration, and outlines future research directions toward designing durable, high-performance, and application-relevant TMO-based energy storage systems, with particular emphasis on bridging laboratory-scale performance and practical device implementation.