Graphdiyne for Electrochemical Energy Storage Devices

Electrochemical energy storage devices are becoming increasingly important in modern society for efficient energy storage. The use of these devices is mainly dependent on the electrode materials. As a newly discovered carbon allotrope, graphdiyne (GDY) is a two-dimensional full-carbon material. Its wide interlayer distance (0.365 nm), large specific surface area, special three-dimensional porous structure (18-C hexagon pores), and high conductivity make it a potential electrode material in energy storage devices. In this paper, based on the facile synthesis method and the unique porous structure of GDY, the applications of GDY in energy storage devices have been discussed in detail from the aspects of both theoretical predictions and recent experimental developments. The Li/Na migration and storage in mono-layered and bulk GDY indicate that GDY-based batteries have excellent theoretical Li/Na storage capacity. The maximal Li storage capacity in mono-layered GDY is LiC3 (744 mAh.g(-1)). The experimental Li storage capacity of GDY is similar to theoretical predictions. The experimental Li storage capacity of a thick GDY film is close to that of mono-layered GDY' (744 mAh.g(-1)). A thin GDY film with double-side storage model has two-times the Li storage capacity (1480 mAh.g(-1)) of mono-layered GDY. Powder GDY has lower Li storage capacity than GDY film. The maximal Na storage capacity in GDY corresponds to NaC5.14 (316 mAh.g(-1)), and mono-layered GDY possesses higher theoretical Na storage capacity (NaC2.57). The experimental Na storage capacity (261 mAh.g(-1)) is similar to its theoretical value. Besides, GDY as electrode material, applied in metal-sulfur batteries, presents excellent electrochemical performance (in Li-S battery: 0.1C, 949.2 mAh.g(-1); in Mg-S battery: 50 mA.g(-1), 458.9 mAh.g(-1)). This ingenious design presents a new way for the preparation of carbon-loaded sulfur. GDY electrode material is also successfully used in supercapacitors, including the traditional supercapacitor, Li-ion capacitors, and Na-ion capacitors. The traditional supercapacitor with GDY as the electrode material shows good double layer capacitance and pseudo-capacitance. Both Li-ion capacitor (100.3 W.kg(-1), 110.7 Wh.kg(-1)) and Na-ion capacitor (300 W.kg(-1), 182.3 Wh.kg(-1)) possess high power and energy densities. Moreover, the effects of synthesis of GDY nanostructure, heat treatment of GDY, and atom-doping in GDY on the performance of electrochemical energy storage will be introduced and discussed. The results indicate that GDY has great potential for application in different energy storage devices as an efficient electrode material.