Two-Dimensional Mn₃O₄Nanowalls Grown on Carbon Fibers as Electrodes for Flexible Supercapacitors

Abstract

Emerging flexible and wearable electronic devices necessitates the development of fiber-type energy storage devices to power them. Supercapacitors received great attention for applications in flexible and wearable devices due to their scalability, safety, and miniature size. Herein, we report the fabrication of a flexible supercapacitor using manganese(II,III) oxide (Mn 3 O 4 ) nanowalls (NWs) grown by electrochemical deposition on carbon fiber (CF) as electrode-active material. Here, CF serves as both a substrate for the growth of Mn 3 O 4 NWs and a current collector for making a lightweight supercapacitor. Two-dimensional Mn 3 O 4 NWs were uniformly grown on CF with high surface coverage. A three-dimensional nanostructured electrode is obtained using these individual two-dimensional Mn 3 O 4 NWs. The Mn 3 O 4 NWs grown on CF are characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, and Raman spectroscopy. A symmetric sandwich-type supercapacitor is fabricated using two-dimensional Mn 3 O 4 NW electrodes in an aqueous 1 M Na 2 SO 4 electrolyte. The Mn 3 O 4 NW supercapacitor electrode exhibits a specific capacitance of 300.7 F g –1 at a scan rate of 5 mV s –1 . The assembled symmetric sandwich-type supercapacitor displayed high flexibility even at a bending angle of 180° without altering its performance. The Mn 3 O 4 NW supercapacitor also displayed a long cycle life of 7500 cycles with 100% capacitance retention.

New Method for the Synthesis of 2D Vanadium Nitride (MXene) and Its Application as a Supercapacitor Electrode

“…The use of Mn 3 O 4 NWs grown on CF as an electrode in a symmetric supercapacitor is reported previously. 42 The scanning electron microscopy (SEM) image of Mn 3 O 4 NWs grown on CF is shown in Figure 7 a from which it can be observed that the Mn 3 O 4 NWs are grown on CF uniformly with a porous architecture. In order to understand the electrochemical performance of the Mn 3 O 4 NWs, the CV study is conducted within a potential window of 0–0.8 V in a 3.5 M KOH aqueous electrolyte.…”

“…The electrochemical deposition method was used in the synthesis of two-dimensional Mn 3 O 4 NWs on the CF substrate as per the literature. 42 In a typical procedure, an electrochemical deposition bath consisting of 0.16 M Na 2 SO 4 and 0.16 M manganese acetate tetrahydrate was used in a three-electrode cell in which a surface-pretreated CF substrate was used as the working electrode, Ag/AgCl was used as the reference electrode, and platinum foil was used as the counter electrode. Mn 3 O 4 NWs were deposited at a constant potential of −1.8 V for a period of 20 min through the chronoamperometry technique.…”

“… 40 In the work reported by Qiao et al, porous Mn 3 O 4 synthesized via a solvothermal technique exhibited a specific capacitance of 302 F/g at 0.5 A/g with a capacitance retention of 89% even after 5000 cycles. 41 Herein, Mn 3 O 4 NWs grown on CF as reported earlier by us 42 were used as the positive electrode with V 2 NT x MXene as the negative electrode in the construction of ASCs. The ASC exhibited a cell voltage of 1.8 V in an aqueous KOH electrolyte.…”

Agar Hydrogel Template Synthesis of Mn3O4 Nanoparticles through an Ion Diffusion Method Controlled by Ion Exchange Membrane and Electrochemical Performance

“…The specific capacitance retention of Mn 3 O 4 electrodes increases gradually and reaches a highest value, and thereafter slowly decreases, the phenomenon may be attributed to the following reasons. First, electrolyte ions gradually penetrate into the interior of electrode materials and open more pore of electrode materials at the beginning stage of charge-discharge cycles, which will enhance the faradic reactions [47]. Second, the electrode is gradually wetted, which will increase the active sites of electrode materials and promote the faraday reaction [48,49].…”

Formation of Ordered Honeycomb-like Structures of Manganese Oxide 2D Nanocrystals with the Birnessite-like Structure and Their Electrocatalytic Properties during Oxygen Evolution Reaction upon Water Splitting in an Alkaline Medium

“…As is well known, manganese oxides are frequently used as, for instance, electrode materials for chemical current sources, 1−3 electrochemical sensors, 4 adsorbents, 5−7 etc. These oxides are also considered as promising noble metal-free electrocatalysts for the decomposition of water by electrolysis.…”