Due to the global warming and energy depletion issues,developing sustainable and renewable energy resources has become a critical concern among researchers.The constantly growing demand for energy has urged researchers to develop highly improved energy storage devices.In relation to relevant energy storage systems,supercapacitor technology has drawn burgeoning interest in recent years owing to its environmentally safe and cost effective advantages.Especially,its high power density (>10 kW/kg),fast charge/discharge characteristics,and excellent cycle stability are highly beneficial in storing renewable energy.Currently,the rapid development of portable electronic devices and the expanding renewable energy systems have paved the way for energy storage systems to play an important role in human society.Many significant breakthroughs for the next-generation supercapacitors have been achieved in terms of material synthesis,device innovations,and multifunctional device designs.Therefore,this paper summarizes the latest progress on new materials and novel device assemblies.First,to fully assess the effect of device assembly on supercapacitor performance,five types of supercapacitor structures and their assembly principles are discussed in detail,including the three-electrode (also known as semi-battery) device,two-electrode supercapacitor,flexible solid-state supercapacitor,fiber supercapacitor,and planar (micro-) supercapacitor.Among them,the three-electrode system and the two-electrode device are still the most widely used types at present.The three-electrode cell is suitable for characterizing electrode materials or investigating the electrochemical storage processes.The structure of a two-electrode system is closer to an actual supercapacitor.Other specially designed cells,which are fabricated with the aim of meeting the requirements of flexible and lightweight energy sources,have also been proposed in recent years.The results indicate that the structural innovative design could provide a fascinating way to enhance the energy density of devices while also holding huge potential to enhance the compatibility between supercapacitor component and various portable or wearable electronic devices.A careful interpretation and rigorous scrutiny of the electrochemical characteristics of every supercapacitor is also conducted in this work.Moreover,the design principles for enhancing the supercapacitor performance are highlighted through a comprehensive analysis of the literature.The main challenges in the structural innovations for enhancing the electrochemical performance are analyzed.The solutions to overcome these challenges are proposed.Second,supercapacitors still suffer from a lower energy density compared with Li-ion batteries.Among various efforts to build high-performance supercapacitors in recent years,major improvements have been made in electrode materials with rational designs.This review article also examines the latest methodologies and performance evaluation metrics for several emerging electrode materials in terms of their improved electrochemical properties,including carbon materials,binary transition metal oxides (NiCo_2O_4,Ni_3V_2O_8,and Co_3V_2O_8,among others),transition metal chalcogenides/selenide/phosphide positive electrodes,and VN,Fe_2O_3 negative electrode materials.