Vacancies and edges: Enhancing supercapacitive performance metrics of electrode materials

•Vacancy and Edges as active sites is discussed.•Correlation of defects with charge storage mechanism is reviewed.•Variation of supercapacitive performance metrices by the introduction of defects is studied.•Literature on edge and vacancy rich charge storage materials is reviewed along with future perspectives. Insight into the role of reactive sites in charge storage materials is highly significant for the design and development of high performance electrode materials for supercapacitor. These active sites constitute micro-structural vacancies and edge defects that effectively modulate the surface microstructure, carrier concentration, electronic, optical and electrochemical properties of material. This review summarizes the recent progress in designing the vacancies and edge defects in range of supercapacitors electrode materials for high performance. Special emphasis is put on correlating the performance metrics of supercapacitor with vacancies and edges induced tailored properties (carrier concentration, coordination number of atom, interlayer spacing, surface area and mechanical strength) of electrode materials. Further, the dependency of tailored properties of electrode materials on size, position, concentration and stability of defects is critically analyzed. We also highlighted the influence of vacancy and edge defects on charge storage mechanism evaluation parameter (b-value) which may help researchers in near future to adjust the operating mechanism as per the device application. The challenges and opportunities ahead in this emerging field are also proposed. Defects enriching the characteristics of electrode materials for enhancement of supercapacitive performance metrics [Display omitted]