Construction of α-MnO2 on Carbon Fibers Modified with Carbon Nanotubes for Ultrafast Flexible Supercapacitors in Ionic Liquid Electrolytes with Wide Voltage Windows

Abstract

In this study, α-MnO2 and Fe2O3 nanomaterials are prepared on a carbon fiber modified with carbon nanotubes to produce the nonbinder core–shell positive (α-MnO2@CNTs/CC) and negative (Fe2O3@CNTs/CC) electrodes that can be operated in a wide voltage window in ultrafast asymmetrical flexible supercapacitors. MnO2 and Fe2O3 have attracted wide research interests as electrode materials in energy storage applications because of the abundant natural resources, high theoretical specific capacities, environmental friendliness, and low cost. The electrochemical performance of each electrode is assessed in 1 M Na2SO4 and the energy storage properties of the supercapacitors consisting of the two composite electrodes are determined in Na2SO4 and EMImBF4 electrolytes in the 2 V and 4 V windows. The 2 V supercapacitor can withstand a large scanning rate of 5000 mV S−1 without obvious changes in the cyclic voltammetry (CV) curves, besides showing a maximum energy density of 57.29 Wh kg−1 at a power density of 833.35 W kg−1. Furthermore, the supercapacitor retains 87.06% of the capacity after 20,000 galvanostatic charging and discharging (GCD) cycles. The 4 V flexible supercapacitor shows a discharging time of 1260 s and specific capacitance of 124.8 F g−1 at a current of 0.5 mA and retains 87.77% of the initial specific capacitance after 5000 GCD cycles. The mechanical robustness and practicality are demonstrated by physical bending and the powering of LED arrays. In addition, the contributions of the active materials to the capacitive properties and the underlying mechanisms are explored and discussed

Dual Role is Always Better than Single: Ionic Liquid as a Reaction Media and Electrolyte for Carbon‐Based Materials in Supercapacitor Applications

“…Reproduced with permission. [68] Copyright 2022, MDPI. performance of IL-based material with bare MWCNTs and observed that IL enhances the device's performance by 85%.…”

“…Further, at 298 K, a specific capacitance of 148 F g −1 and ED of 82 Wh kg −1 was obtained, and at 373 K, the obtained specific capacitance was 290 F g −1 with an ED of 161 Wh kg −1 . Li M. et al [ 68 ] fabricated α‐MnO 2 on CF‐modified CNT (α‐MnO 2 @CNTs/CNFs), which was used as positive and negative electrodes for SC. The electrode was prepared by chemical vapor deposition followed by the hydrothermal method as described in Figure a along with b unit cell and c crystal structure of α‐MnO 2 , and EMIMBF 4 was utilized as electrolyte.…”

National Policies, Recent Research Hotspots, and Application of Sustainable Energy: Case of China, USA, and European Countries

“…Specifically, the electric transformation from other energy forms is often stored in robust, reliable, and cost-effective energy storage devices such as lithium-ion, lithium-sulfur batteries, and sodium-ion batteries [14][15][16][17]. At present, the lithium-ion battery is the most widely used; however, due to the scarcity of the lithium element, the cost of lithium-ion batteries is increasing, which restricts their future development.…”

Manufacturing Shape-Controllable Flexible PEDOT/rGO Composite Electrodes for Planar Micro-Supercapacitors

“…Based on their charge storage mechanism, supercapacitors are categorized into electric double-layer capacitors (EDLCs) and pseudocapacitors [9,10]. Carbon materials, with their excellent conductivity, stable chemical properties, high specific surface area, low cost, and mature processing technology, are considered high-quality electrode materials for EDLCs [11,12]. The electrode materials for pseudocapacitors mainly include metal oxides and conductive polymers [13,14].…”