High energy density supercapacitors: electrode material,electrolyte and energy density limitation principle

Supercapacitors are power-type energy storage devices with high power density and long cycle life. However, the low energy density limits wider applications. In this paper, the working principle of supercapacitors was first introduced, and the characteristics of electrode materials needed and current progress were summarized. Then, the characteristics and related progress of aqueous, organic and ionic liquid electrolytes were introduced. Finally, the principle and the factors of energy density limitation of supercapacitors were pointed out, and the improvement methods were discussed from the aspects of electrode materials, electrolytes and the structure of supercapacitors, respectively.