Mixed-Phase MnO2/N-Containing Graphene Composites Applied as Electrode Active Materials for Flexible Asymmetric Solid-State Supercapacitors

Abstract

MnO2/N-containing graphene composites with various contents of Mn were fabricated and used as active materials for the electrodes of flexible solid-state asymmetric supercapacitors. By scanning electron microscopes (SEM), transmission electron microscope (TEM), energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectrometer (XPS), fourier-transform infrared spectroscopy (FTIR) and Raman spectra, the presence of MnO2 and N-containing graphene was verified. The MnO2 nanostructures decorated on the N-containing graphene were of α- and γ-mixed phases. N-containing graphene was found to reduce the charge transfer impedance in the high-frequency region at the electrode/electrolyte interface (RCT) due to its good conductivity. The co-existence of MnO2 and N-containing graphene led to a more reduced RCT and improved charge transfer. Both the mass loading and content of Mn in an active material electrode were crucial. Excess Mn caused reduced contacts between the electrode and electrolyte ions, leading to increased RCT, and suppressed ionic diffusion. When the optimized mass loading and Mn content were used, the 3-NGM1 electrode exhibiting the smallest RCT and a lower ionic diffusion impedance was obtained. It also showed a high specific capacitance of 638 F·g−1 by calculation from the cyclic voltammetry (CV) curves. The corresponding energy and power densities were 372.7 Wh·kg−1 and 4731.1 W·kg−1, respectively. The superior capacitance property arising from the synergistic effect of mixed-phase MnO2 and N-containing graphene had permitted the composites promising active materials for flexible solid-state asymmetric supercapacitors. Moreover, the increase of specific capacitance was found to be more significant by the pseudocapacitive MnO2 than N-containing graphene.

Synthesis of a NiMoO4/3D-rGO Nanocomposite via Starch Medium Precipitation Method for Supercapacitor Performance

“…Generally, three types of electrode materials-carbon materials, metal oxide, and conducting polymers-have been used for supercapacitors [3]. However, transition metal oxides and hydroxides, such as NiO [4], Ni(OH) 2 [5][6][7], MnO 2 [8,9], MoO 3 [10], and Co 3 O 4 [11], are mostly employed as the supercapacitors material. These types of electrode materials are low cost and naturally abundant, with significant specific capacity based on redox reactions and high electrochemical activity [12].…”

Carbon Nanotube-Graphene Hybrid Electrodes with Enhanced Thermo-Electrochemical Cell Properties

“…Due to good electric and thermal conductivities, excellent chemical stability, and unique structural properties, carbon nanotubes (CNTs) showed promising properties in the TEC application [4,5,7,8,9,10,11,12,13,14], and the electrophoretic deposition (EPD) method was applied to fabricate CNT TECs for merits of process simplicity and large-scale capability [5,10,15]. The graphene, with priorities of large surface area, high electric/thermal conductivities, and high chemical/electrochemical stabilities, has been widely investigated in the energy storage and conversation applications [16,17,18,19,20]. Recently, CNT-based hybrid electrodes, i.e., the electrodes with at least two composition materials, were applied to fabricate TEC electrodes with improved energy conversation efficiency because of the synergetic effect between different materials [8,11,12,13].…”

Magnesium Klorida (MgCl2): Karakteristik dan Dinamika Molekuler Pada MgCl2

“…Jika dua elektroda (206)(207)(208)(209)(210) yang terpisah dengan jarak l berada pada selisih potensial (   ), maka ion dalam larutan diantara kedua elektroda tersebut, mengalami medan listrik (211)(212)(213)(214)(215)…”