Rational-Designed Hybrid Aerogels for Ultra-Flyweight Electrochemical Energy Storage

Hybridizing 2D materials into 3D aerogels have attracted considerable interest in ultralight electrochemical energy storage devices. However, to optimize the device structure for more efficient charge storage and transport, a better understanding of the ratio-dependent hybridization process and interface charge transfer mechanisms is highly required. Here, we perform a comprehensive study to elucidate the fundamental process during the reduced graphene oxide (rGO) and carbon nanotube (CNT) hybridization, which enabled the fabrication of a rational-designed rGO/CNT hybrid aerogel (GCA) with a record energy storage performance beyond previously reported works. Based on spectroscopy and microscopy analysis, we found the hydrophilic and hydrophobic transition of GO, which eliminates the surface-functionalized oxygen-containing moieties, is the origin of the pi-pi stacking hybridization between rGO and CNTs. Moreover, we found the different amounts of CNTs that "solder" in between rGO sheets can offer GCA distinct mechanical elasticity, ion diffusion resistance, and specific capacitance. As illustrated in the electrochemical impedance spectroscopy (EIS) and charge/discharge analysis, we found GCA 2-2 (rGO:CNT = 2:2) displays the best gravimetric capacitance of 117 F center dot g(-1) at a discharge current density of 1 A center dot g(-1), which helps us to fabricate an ultra-flyweight supercapacitor with a large energy density of 3.53 Wh center dot kg(-1) at a power density of 283.4 W center dot kg(-1).