rGO‐Wrapped Hexagonal WO₃ Nanorod as Advanced Electrode Material for Asymmetric Electrochemical Supercapacitors

Abstract

The multiple oxidation states of redox‐active materials enable them to store high‐energy better than the commonly used carbon‐based electrode materials. Accounting for these advantages, designing asymmetric supercapacitors by coupling redox‐active materials as positive electrodes with carbon‐based negative electrodes becomes a very attractive strategy. Herein, reduced graphene oxide‐wrapped hexagonal WO3 nanorod (rGO‐WO3 NR) by simple hydrothermal synthesis method is synthesized. Because of improved reaction kinetics resulting from the close contact between rGO and WO3 NRs, rGO‐WO3 NR demonstrates superior electrochemical properties than pure WO3. Motivated by the very high areal capacitance (2.5 F cm−3 at the applied current of 30 mA cm−2), an asymmetric SC device by combining rGO‐WO3 NR with activated carbon is assembled. The as‐assembled rGO‐WO3 NR//activated carbon asymmetric supercapacitor device demonstrates outstanding electrochemical performance in an operating voltage window of 1.2 V, admirable cycling stability of ≈95% (even after 14 000 cycles), with an energy density of 24.1 Wh Kg−1 at a power density of 1532.6 W Kg−1. These demonstrate the combination of redox‐active materials with high energy density can importantly boost the energy storage capacity of a supercapacitor.

Sodium Storage Properties of Carbonaceous Flowers

“…In general, the Raman spectrum of carbonaceous materials exhibits two prominent peaks, which are commonly referred to as the D and G bands. The D-band, which occurs at approximately 1372 cm −1 , is attributed to the A 1g vibration mode of the sp 3 -hybridized carbon aromatic rings that arises from the existence of defects or disorders caused by O/N doping [ 39 ]. Conversely, the G-band, which occurs at approximately 1580 cm −1 , corresponds to the E 2g mode of the C-C bond stretching of sp 2 hybridized C-atoms and is indicative of the presence of ordered graphitized sp 2 carbon in specimens [ 40 ].…”

Sodium‐Substituted Tungsten Oxide Nanoflowers: An Efficient Electrode Enhancing the Pseudocapacitive Storage in Aqueous Asymmetric Supercapacitors

“…Normally, WO 3 exhibits cubic WO 3 , monoclinic (ɛ-WO 3 ), triclinic (δ-WO 3 ), orthorhombic (β-WO 3 ) and tetragonal (α-WO 3 ) crystal structure. [15][16][17][18][19] Further, the alkali metal elements like potassium (K), and sodium (Na) substitution in the tungsten oxide matrix can enhance the electrical conductivity, leading to faster charge and discharge rates without disturbing the original crystal structure. [20,21] Additionally, the redox reaction mechanism at the electrode/electrolyte interface can be tailored.…”

Experimental and theoretical insights into the supercapacitive performance of interconnected WS2 nanosheets

“…7 Furthermore, increasing the effective surface area of electrodes results in higher specific capacitance due to the increased quantity of charges stored on their surfaces. 8–11 Substantial efforts have recently been directed toward the development of nanostructured electrode materials in order to meet the aforementioned objectives by bridging their better material characteristics to more efficient electrode designs. 12 Typically, carbon-based materials are used as electrode materials in EDLCs because of their large surface areas, controllable pore size, and high chemical stability.…”