Efficient coupling of MnO₂/TiN on carbon cloth positive electrode and Fe₂O₃/TiN on carbon cloth negative electrode for flexible ultra-fast hybrid supercapacitors

Abstract

MnO2 ultrathin nanosheet arrays and Fe2O3 nanoparticles are fabricated on carbon based TiN nanowires to produce binder-free and core–shell positive and negative electrodes for a flexible and ultra-fast hybrid supercapacitor.

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

“…Figure 2c shows the Mn 2p spectrum of α-MnO 2 @CNTs/CC, revealing peaks at 654.2 eV for Mn 2p 1/2 and 642.5 eV for Mn 2p 3/2 of MnO 2 . The satellite peak (sat) is related to α-MnO 2 , consistent with previous studies and further confirming the formation of MnO 2 [28]. The H-O-H (531.9 eV) and Mn-O-H (530.2 eV) peaks in Figure 2d of α-MnO 2 @CNTs/CC are attributed to the hydroxyl groups and absorbed water, respectively [30][31][32].…”

“…All in all, the potential time curves in Figure 6b show a stable output potential of 467 mV after 4 h and it remains at about 385 mV after 21 h, which is comparable to previous studies [46]. The relationship between impedance data and frequency of complex capacitance model is essential to analyze the supercapacitor electrodes [28]. Figure 6c depicts the relationship between the real part of the capacitance C (ω) with the frequency of CNTs/CC, α-MnO 2 /CC, and α-MnO 2 @CNTs/CC, according to Equations S1, S2, and S3.…”

“…The high-resolution image of the α-MnO2@CNTs coreshell structure in Figure 4e reveals lattice spacings of 0.14 nm, 0.31 nm, and 0.24 nm corresponding to the (300), (101), and (110) planes of α-MnO2, respectively [27,38]. The coreshell structure comprising the MnO2 film and CNTs is confirmed by the elemental maps of α-MnO2@CNTs in Figure 4f and the elemental distributions of C, Mn, and O in Figure 4(f1-f3), indicating that large amounts of Mn and O are uniformly distributed on the CNTs [28]. The α-MnO 2 @CNTs and Fe 2 O 3 @CNTs core-shell structures were stripped from the composite electrodes ultrasonically to analyze by TEM.…”

“…The H-O-H (531.9 eV) and Mn-O-H (530.2 eV) peaks in Figure 2d of α-MnO 2 @CNTs/CC are attributed to the hydroxyl groups and absorbed water, respectively [30][31][32]. The Fe 2p peaks at 724.58 eV and 710.86 eV in Figure 2e are the Fe 2p peaks of Fe 2 O 3 @TiN/CC representing Fe 2p 1/2 and Fe 2p 3/2 in α-Fe 2 O 3 [28]. As shown in Figure 2f, the peaks at 530.0, 531.4, and 532.5 eV of Fe 2 O 3 @CNTs/CC arise from O 2− , OH − , and O-C=O, respectively [25], and that at 532.6 eV corresponds to the H-O-H of the adsorbed water molecules [33].…”

“…The mechanism of the α-MnO 2 @CNTs/CC electrode is explored by calculating the pseudocapacitance ratio based on the CV plots in Figure 7a and k1 (Figure 7b shows the images corresponding to six groups of random voltages during charge-discharge) [28] by Equation ( 6…”