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Demand for energy in day to day life is increasing exponentially. However, existing energy storage technologies like lithium ion batteries cannot stand alone to fulfill future needs. In this regard, potassium ion batteries (KIBs) that utilize K ions in their charge storage mechanism have attracted considerable attention due to their unique properties and are therefore established as one of the future battery systems of interest among the scientific community. Nevertheless, the development and identification of appropriate electrode materials is very essential for practical applications. This review features the current development in KIBs electrode and electrolyte materials, the present challenges facing this technology (in the commercial aspect), and future aspects to develop fully functional KIBs. The potassium storage mechanisms, evolution of the KIBs, and the advantages and disadvantages of each category of materials are included. Additionally, various approaches to enhance the electrochemical performances of KIBs are also discussed. This review is not only an amalgamation of different viewpoints in literature, but also contains concise perspectives and strategies. Moreover, the potential emergence of a novel class of K‐based dual ion batteries is also analyzed for the first time. [ABSTRACT FROM AUTHOR]

Current energy crises are inspiring researchers to focus intensively on development of feasible ways to produce high performing composite electrode materials for increasing energy demands. The present work addresses this objective by developing a novel structure of NiFe2O4 (NFO) nanoparticles coated on graphene capsules (GCs) by a simple hydrothermal technique. This NFO–GCs electrode material was subjected to different types of electrochemical performance evaluations to investigate its feasibility as a supercapacitor electrode. The as-prepared NFO–GCs nanocomposite electrode exhibits high specific capacitance of 1028 F g−1 at a current density of 2 A g−1 and 94% capacitance retention at the end of 10 000 charge–discharge cycles, whereas pristine NFO electrode shows 720 F g−1 specific capacitance with 88% capacitance retention. The high specific capacitance, good rate capability, and excellent cycling stability of NFO–GCs composite can be attributed to effective synergism between the GCs and NFO. The superior electrochemical performance of NFO–GCs nanocomposite demonstrates possible application of this material as a working electrode for fully functional supercapacitor devices. [ABSTRACT FROM AUTHOR]