Engineered transition metal pseudocapacitive electrodes from 0D to 3D structures: Emerging trend for high performance supercapacitors

Supercapacitors (SCs) store significantly more energy than conventional capacitors and the charge-discharge rates are far superior to those of batteries. However, their practical large-scale adoption remains constrained by inherently low capacitance and energy density. To address these challenges, transition metal (TM) based composites have emerged as promising SC electrode materials, exploiting their exceptional physical, mechanical, and electrochemical properties. Various TM nanostructures, ranging from 0D to 3D, have been developed highlighting their potential in energy storage applications. Notably, pseudocapacitive materials with diverse structures have demonstrated remarkable improvements in electrochemical performance when employed as SC electrodes. This review is dedicated to overviewing recent progress and key achievements in TM nanostructures and their application in SCs. Emphasis is placed on how structural dimensionality influences the synthesis, physicochemical properties, and electrochemical behavior of cathode materials. The review concludes by recognizing outstanding challenges and proposing to address them in the future direction, aiming to provide clear guidance toward the design and development of next-generation, high-performance SCs.