Recent advances and fundamentals of Pseudocapacitors: Materials, mechanism, and its understanding

The development of electrochemical energy storage devices that can provide both high power and high energy density is in high demand around the world. The scientific community is trying to work together to solve this problem, and one of the strategies is to use pseudocapacitive materials, which take advantage of reversible surface or near-surface Faradaic processes to store charge. It enables pseudocapacitors to transcend the capacity and mass transfer limitations of electrical double-layer capacitors and batteries. The study of pseudocapacitance, as well as materials that exhibit this behavior, has advanced dramatically during the last decade. The contribution of this study is to look at the history of the idea of pseudocapacitance and how it became popular in electrochemical energy storage, as well as to explain new families of materials with pseudocapacitive electrochemical energy storage behavior. The advanced next-generation electrode materials are expected to deliver high energy density without compromising it with the power density aspects. This review seeks to provide a complete overview of electrochemical energy storage in terms of its foundations, technological applications, recent advances, and the outlook of various transition metal-based electrode materials for energy storage applications. This review suggests that the current problem with the energy storage systems and how to solve them like diffusion kinetics, fast ionic transport, rate-capability, high-rate performance, peeling of the materials, enhancing the electronic conductivity, etc. by providing the recent re-engineering approach of novel next-generation electrode materials, their material designing strategies like nanostructurization, atomic-level engineering using creating the defect structures, interlayer tuning of the nanostructures. These are some approaches to enhance and explore the new charge storage phenomenon. High-rate capability is one of the very major concerns about the current trends amongst the energy storage materials, the author has provided a simple approach to address this very crucial problem.