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Co-Modified MnWO4 Nanorods Coupled with H2O2-Treated Carbon Nanotubes for a Charge-Balanced Aqueous Hybrid Supercapacitor
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DOI：10.3390/mi17080911.png)
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Abstract
En 中文
A charge-balanced aqueous hybrid supercapacitor was constructed by coupling Co-modified MnWO4 nanorods with H2O2-treated carbon nanotubes (OH-CNTs) in 1 M KOH. The samples were designated by the nominal Co/(Mn + Co) precursor molar fraction; ICP-OES measured bulk Co fractions of 0.09 ± 0.01, 0.47 ± 0.03, and 0.75 ± 0.04 mol% for the nominal 0.1, 0.5, and 0.8 mol% samples, respectively. Rietveld refinement confirmed retention of the monoclinic P2/c MnWO4 phase with only small composition-dependent lattice changes. At an active-material loading of 2.00 ± 0.05 mg cm−2, the optimized nominal 0.5 mol% sample delivered 429.5 ± 11.0 C g−1 (119.3 ± 3.1 mAh g−1) at 1 A g−1 and retained 280.5 ± 8.5 C g−1 (77.9 ± 2.4 mAh g−1) at 15 A g−1. Because the positive electrode exhibits battery-type behavior, specific charge and specific capacity are used as the primary performance descriptors. Over −0.9–0 V vs. SCE, pristine CNT and OH-CNT electrodes delivered of 189.0 ± 7.2 and 246.6 ± 8.1 C g−1, corresponding to electrode-level apparent specific capacitances of 215 ± 8 and 280 ± 9 F g−1 at 1 A g−1 after correction for the measured IR drop. These values apply to the stated 90:5:5 CNT (or OH-CNT)/acetylene-black/PVDF formulation and CNT-active-mass normalization and should not be interpreted as intrinsic capacitances of isolated commercial MWCNT powders. Charge matching based on the measured gave m+/m− = 0.574; integration at the actual device loadings yielded q+ = 0.861 ± 0.015 C and q− = 0.854 ± 0.015 C (q+/q− = 1.008). The device operated over 0–1.6 V and delivered 97.9 ± 3.1 F g−1 at 0.51 A g−1, corresponding to 34.8 Wh kg−1 at 408 W kg−1 when normalized to the combined active mass of both electrodes. Three independently assembled devices retained 96.0 ± 0.7% of the initial capacitance and showed a coulombic efficiency of 98.8 ± 0.1% at the 10,000th cycle at 5.13 A g−1. Device metrics are normalized to the combined active mass of both electrodes and exclude current collectors, separator, electrolyte, and packaging.
Keywords:
Co-modified MnWO<sub>4</sub>
H<sub>2</sub>O<sub>2</sub>-treated carbon nanotubes
aqueous hybrid supercapacitor
charge balance
battery-type electrode
combined-active-mass normalization
Journal
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1.3W
Citations:
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