Electrospun Mesoporous Mn–V–O@C Nanofibers for High-Performance Asymmetric Supercapacitor Devices with High Stability

Abstract

Supercapacitors (SCs) are being considered the next-generation power storage devices due to the many favorable properties. In this regard, mesoporous nanostructures are excellent supercapacitor electrodes as they enjoy a large number of active sites and high surface area promising the utilization of the full capacitance of the active materials. In this study, we report on the assembly of electrospun, binder-free mesoporous Mn 0.56 V 0.42 O@C fibrous electrodes. The morphological and structural analyses of the fabricated Mn 0.56 V 0.42 O@C electrodes were investigated using field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), and glancing angle X-ray diffraction (GAXRD). The X-ray photoelectron spectroscopy (XPS) and GAXRD confirm the formation of Mn 0.56 V 0.42 O nanofibers and their successful bonding to carbon during crystal growth. Those fibrous composite electrodes showed excellent specific capacitance of 668.5 F g −1 at 1 A g −1 . The highly obtained capacitance is attributed to the multiple oxidation states of the Mn−V oxides, the binder-free electrodes, surface roughness, and the mesoporous nature of the fabricated nanofibers. The asymmetric supercapacitor composed of the mesoporous Mn 0.56 V 0.42 O@C nanofibers as the positive electrode and graphene hydrogel as the negative electrode possesses ultrahigh energy density of 37.77 W h kg −1 and a power density of 900 W kg −1 with superior Coulombic efficiency over 13 000 charge−discharge cycles.

Oxygen Vacancy‐Engineered Ti−Mo−Ni Ternary Oxide Nanotubes as Binder‐Free Supercapacitor Electrodes with Exceptional Potential Window

“…The cyclic voltammograms (CVs) exhibit a quasi-rectangular shape, indicating linear variation of the potential with time. [48] Moreover, the CVs revealed symmetric characteristics with voltage at zero current, indicating that TiÀ MoÀ NiÀ O nanotubes have a pseudocapacitive electrochemical behavior. This could be related to the presence of nickel and molybdenum oxides, which are known for their redox capacitance contribution.…”

Fullerene C76: An Unexplored Superior Electrode Material with Wide Operating Potential Window for High‐Performance Supercapacitors

“…A typical supercapacitor device mainly depends on the adsorption/desorption of ions on its surface, namely the electrical double layer (EDL). Moreover, developments included the use of Faradic materials such as the diffusion‐controlled pseudo and the redox battery‐like capacitors . Although Faradic materials can deliver high energy density, they suffer from poor cycling stability compared to the EDL counterparts.…”

Recycling of Li−Ni−Mn−Co Hydroxide from Spent Batteries to Produce High‐Performance Supercapacitors with Exceptional Stability

“…To confirm the charge storage behavior of our recycled material, Tafel's plot was demonstrated as shown in Figure b according to the relation , where i is the current, v is the scan rate, and b is the slope. The slope was found to be ∼0.5, revealing diffusion‐controlled process as supported by the redox peaks shown in the CV scans . Therefore, the electrochemical measurements indicate a battery‐like behavior, which can be related to faradic process …”

“…Graphene oxide (GO) was synthesized via a modified Hummers’ method and graphene hydrogel (GHG) was prepared via a hydrothermal method as reported before …”

“…The slope was found to be~0.5, revealing diffusion-controlled process as supported by the redox peaks shown in the CV scans. [26,30] Therefore, the electrochemical measurements indicate a battery-like behavior, which can be related to faradic process. [31] Figure 3c depicts the CCCD graphs at different current densities (1-4 A g À 1 ), showing nonlinear curves of potential versus time, which confirm the battery-like behavior of the recycled material.…”