Assembly of flexible CoMoO4@NiMoO4·xH2O and Fe2O3 electrodes for solid-state asymmetric supercapacitors

Abstract

In this work, CoMoO4@NiMoO4·xH2O core-shell heterostructure electrode is directly grown on carbon fabric (CF) via a feasible hydrothermal procedure with CoMoO4 nanowires (NWs) as the core and NiMoO4 nanosheets (NSs) as the shell. This core-shell heterostructure could provide fast ion and electron transfer, a large number of active sites, and good strain accommodation. As a result, the CoMoO4@NiMoO4·xH2O electrode yields high-capacitance performance with a high specific capacitance of 1582 F g−1, good cycling stability with the capacitance retention of 97.1% after 3000 cycles and good rate capability. The electrode also shows excellent mechanical flexibility. Also, a flexible Fe2O3 nanorods/CF electrode with enhanced electrochemical performance was prepared. A solid-state asymmetric supercapacitor device is successfully fabricated by using flexible CoMoO4@NiMoO4·xH2O as the positive electrode and Fe2O3 as the negative electrode. The asymmetric supercapacitor with a maximum voltage of 1.6 V demonstrates high specific energy (41.8 Wh kg−1 at 700 W kg−1), high power density (12000 W kg−1 at 26.7 Wh kg−1), and excellent cycle ability with the capacitance retention of 89.3% after 5000 cycles (at the current density of 3A g−1).

Homogeneous Core/Shell NiMoO4@NiMoO4 and Activated Carbon for High Performance Asymmetric Supercapacitor

“…It was also observed that the ESR of our homogeneous structure decreased by at least 68% compared with other heterogeneous structures or different morphologies of NiMoO 4 (Table S1). Moreover, the diameter of the semicircle represents the interfacial charge-transfer resistance (Rct) [51]. In our case, the Rct of Electrodes I, II, and III are 3.0 Ω, 2.35 Ω, and 2.65 Ω, respectively, exemplifying that Electrode II has the best charge-transfer characteristics.…”

“…Aside from surface area, the impedance of the electrode also has an important effect on the overall behavior of SCs. The impedance properties of the electrodes were investigated in an open-circuit voltage with 5 mV amplitude, utilizing an EIS measurement [15,29,50,51]. Figure 5d displays the Nyquist plots measured in the frequency range of 0.01–100 kHz and the equivalent circuit is shown in the inset.…”

Novel chemical route for CeO2/MWCNTs composite towards highly bendable solid-state supercapacitor device

“…The energy density of present device is substantially higher than those of recently reported all-solid-state symmetric SCs with electrode materials such as MoS 2 /carbon cloth (5.42 Wh/kg) 43 , GO/PPy (15.1 Wh/kg) 44 , SWCNTs/RuO 2 (18.8 Wh/kg) 36 , rGO-PEDOT/PSS (2.83 Wh/kg) 45 , MWCNTs (3.5 Wh/kg) 46 , N-doped cotton-derived carbon frameworks (NCCF)-rGO (20 Wh/kg) 47 , MoSe 2 (36.2 Wh/kg) 48 , PEDOT:PSS/MWCNT (13.2 Wh/kg) 2 , ZnS/CNTs (22.3 Wh/kg) 37 , ZnCo 2 O 4 /rGO (11.44 Wh/kg) 49 , Pt/n-CNT@PANI (30.22 Wh/kg) 50 , waste paper fibers-RGO–MnO 2 (19.6 Wh/kg) 51 , and porous carbon (7.22 Wh/kg) 52 . Due to current collector-free feature, present ultrathin device showed remarkable energy density, a value considerably higher than even solid-state asymmetric devices, such as CNT/polyaniline//CNT/MnO 2 /GR (24.8 Wh/kg) 53 , carbon aerogel//Co 3 O 4 (17.9 Wh/kg) 38 , graphene(IL-CMG)//RuO 2 –IL-CMG (19.7 Wh/kg) 41 , TiN@GNSs//Fe 2 N@GNSs (15.4 Wh/kg) 54 , NiCo 2 O 4 @PPy//activated carbon (AC) (58.8 Wh/kg) 40 , NiCo 2 O 4 /CC//porous graphene papers (PGP) (60.9 Wh/kg) 55 , γ-MnS//eggplant derived AC (EDAC) (37.6 Wh/kg) 56 , CoS//AC (5.3 Wh/kg) 57 , CoMoO 4 @NiMoO 4 •xH 2 O//Fe 2 O 3 (41.8 Wh/kg) 58 , CuS/3D graphene//3D graphene (5 Wh/kg) 59 , MnO 2 @PANI//3D graphene foam (GF) (37 Wh/kg) 60 , NiCo 2 S 4 /polyaniline//AC (54.06 Wh/kg) 61 , NiCo-LDH//carbon nanorods (59.2 Wh/kg) 39 , Ni(OH) 2 /RGO/Ni//RGO aerogel/Ni (24.5 Wh/kg) 62 , and rGO/CoAl-LDH//rGO (22.6 Wh/kg) 63 .…”

Hydrothermal synthesis of CoMoO 4 /Co 1- x S hybrid on Ni foam for high-performance supercapacitors

“…In the impedance spectra, the starting point intersecting with the X-axis in the high frequency region is series resistance ( R S ) caused mainly by the conductive substrate, connecting wires and contact resistance. The diameter of the semicircle represents the charge transfer resistance ( R CT ) at the electrode/electrolyte interface, curve slope in the low frequency region represents the diffusion-limited processes ( Z w ), respectively [31,[38][39][40][41][42][43][44] . Fig.…”