Hierarchically Organized Ultrathin NiO Nanofibers/Highly Defective‐rGO Heteronanocomposite: An Advanced Electrode Material for Asymmetric Supercapacitors

Abstract

Herein, defective‐rGO (D‐rGO) is endorsed as a unique conducting matrix for defect‐induced interfacial growth of ultrathin dangling‐NiO nanofibers. The physicochemical analyses corroborate added defect density on the graphene surface, defect‐induced growth of NiO, and excellent hydrophilicity of NiO/D‐rGO heteronanocomposite. Thorough electrochemical analyses of NiO/D‐rGO heteronanocomposite show high specific capacitance of 1992 F g−1, ultralow equivalent series resistance (ESR) of 1.7 Ω, and ≈92.5% retention of charge storage after 5000 galvanostatic charge–discharge (GCD) cycles. The advanced NiO/D‐rGO ‖ Bi2O3 asymmetric supercapacitor (ASC) device delivers high areal/mass specific capacitance and exhibits outstanding rate capacitance under extreme current density conditions. The ASC device retains a significant 89.5% of areal capacitance after 5000 GCD cycles under high rate conditions. The ASC device also delivers a high energy density of ≈43.7 Wh kg−1 at a power density of ≈4799 W kg−1 and retains ≈46% of the energy density at a very high power density of ≈18 518 W kg−1. The excellent performance of the ASC device is ascribed to defect‐induced improved bonding between D‐rGO and NiO, microstructural stability of NiO/D‐rGO, D‐rGO prompted conductivity, and “ion‐buffering‐reservoir” ‐alike behavior of the fiber assembly. The present approach is significant in developing new‐age supercapacitors for high rate applications.

Recent progress in carbon-based materials for supercapacitor electrodes: a review

“…Table 2 lists some typical asymmetric supercapacitors based on carbon/metal oxide or metal [187] hydroxides (MnO 2 , Co 3 O 4 , NiO, etc.). It can be seen that it is effective to expand the working voltage window of the device by constructing asymmetric supercapacitors, which brings an increase in both E d and P d .…”

Printable and Homogeneous NiOx Hole Transport Layers Prepared by a Polymer‐Network Gel Method for Large‐Area and Flexible Perovskite Solar Cells

“…In addition, due to the differentiated particle surface state, the smaller size particles are more likely to be adsorbed to the surface of large particles during the dispersion process, thereby forming agglomeration. [29][30][31] The grains with large size differences usually result in a rougher film morphology, which in turn leads to poor interface contact. [32][33][34] Therefore, the uniformity of NiO x film fabricated based on low-temperature solutions is usually a big challenge, especially under flexible or large-area conditions.…”

Facile Synthesis of Manganese‐Cobalt‐Sulfur/Reduced Rraphene Oxide Composite as High Performing Faradaic Electrode

“…Figure 5c shows the linear relationship between (E o ‐E R ) and (ν) 1/2 . Higher linearity (R 2 =0.99) indicates that the material possesses excellent dynamic reversibility [30] . In this case, E o and E R are the peak potentials of the oxidation and reduction processes at a certain scan rate ν, respectively.…”

“…Higher linearity (R 2 = 0.99) indicates that the material possesses excellent dynamic reversibility. [30] In this case, E o and E R are the peak potentials of the oxidation and reduction processes at a certain scan rate ν, respectively. The increase in the (E O -E R ) value is due to the excess voltage during the electron transfer process at higher scan rates.…”