An improvement on capacitive properties of clew-like MnO2 by thermal treatment under nitrogen

Sun, Yin; Huang, Naibao; Sun, Xiannian; Wang, Dongchao; Zhang, Junjie; Qiao, Shaoming; Gao, Zhaoqing

doi:10.1016/j.ijhydene.2017.05.234

Cited by 28 publications

(6 citation statements)

References 28 publications

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“…[15] From 450°C to 700°C, the TG curve tends to be flat, with only a slight mass loss (less than 1.2 % of the original mass), which may be attributed to the release of oxygen molecules. [16] To study the effect of annealing temperature on the performance of NiMn 2 O 4 , as described above, 350°C À 650°C was selected as the annealing temperature range according to the TG curve.…”

Section: Thermogravimetric Analysis Of Nimn 2 O 4 Precursor Powdermentioning

confidence: 99%

Microwave‐Assisted Synthesis of NiMn₂O₄ Grown on Nickel Foam as Electrode Material for High‐Performance Supercapacitors

Yang

et al. 2021

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The spinel NiMn 2 O 4 has been directly grown on 3D nickel foam by combining a simple microwave-assisted hydrothermal with annealing process at different temperatures (350°C to 650°C), which can be used as a binder-free electrode for high-performance supercapacitors. The results indicate that the pure NiMn 2 O 4 can be obtained below 550°C. The as-prepared NiMn 2 O 4 at 450°C has the largest specific capacitance of 802 F g À 1 at 1 A g À 1 and excellent cycle stability (61 % capacity retention after 5000 cycles at 10 A g À 1 ) among all the obtained samples. This outstanding electrochemical performance may be attributed to its relatively large grain size, high specific surface area, and appropriate pore structure. This indicates that NiMn 2 O 4 grown on nickel foam shows great potential as an electrode material for supercapacitors.

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Section: Thermogravimetric Analysis Of Nimn 2 O 4 Precursor Powdermentioning

confidence: 99%

Microwave‐Assisted Synthesis of NiMn₂O₄ Grown on Nickel Foam as Electrode Material for High‐Performance Supercapacitors

Yang

et al. 2021

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“…A recent study by Sun et al has shown that annealing of asprepared δ-MnO 2 in N 2 can result in an increase in the conductivity of the material. 49 However, there was no discussion on any structural changes, as shown in this work. The XRD patterns in the work by Sun et al were measured in the range of 2θ equal to 15 o -90 o and do not show the (001) peak for birnessite type MnO 2 at ∼12.5 o .…”

Section: Resultsmentioning

confidence: 67%

Improved Capacitive Behavior of Birnessite Type Mn Oxide Coated on Activated Carbon Fibers

Abedi¹,

Leistenschneider²,

Ivey³

et al. 2022

J. Electrochem. Soc.

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Birnessite type Mn oxide (potassium birnessite hydrate) powder (as-δ-MnO2) with a layered microstructure was prepared via a hydrothermal process. To improve its capacitive performance, the microstructure was thermally modified (annealed) at 400 oC (400-δ-MnO2) in a N2 reducing environment. By removing the hydrated cations (K+) layers inserted between the main layers of birnessite, damaging the microstructure, intercalation/deintercalation of the electrolyte species (Li+1) became more effective. Characterization of as-δ-MnO2 and 400-δ-MnO2 revealed that no phase transformation occurred during the annealing process. The microstructure became less crystalline and the total pore volume increased from 0.20 cm3 g-1 to 0.43 cm3 g-1, while the oxidation state of Mn remained 4+ after annealing the as-δ-MnO2 at 400 oC. The 400-δ-MnO2 sample was then coated on asphaltene derived activated carbon fibers (ACF-400-δ-MnO2) to improve the performance by making use of the high electrical conductivity and capacitive behavior of ACF. Coating the 400-δ-MnO2 sample led to a significant increase in the capacitance (328 F g-1 and 195 F g-1 for ACF-400-δ-MnO2 and 400-δ-MnO2 at 0.4 A g-1, respectively), improved energy and power values (~7 kW kg-1 at ~4.2 Wh kg-1 for ACF-400-δ-MnO2 and 240 W kg-1 at 2.4 Wh kg-1 for 400-δ-MnO2) and improved cycling behavior.

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“…It can be clearly observed that with thermal treatment, the surface area of MnO 2 @400°C has been increased significantly by 9.95 m 2 /g that agrees well with HAADF analysis. The decrease in surface area and pore volume for MnO 2 @600°C might be related to the changes in the phase structure of MnO 2 that has partially converted into Mn 2 O 3 by further removal of lattice oxygen at 600°C, which has been confirmed through XRD [ 96 ] .…”

Section: Resultsmentioning

confidence: 99%

Thermal optimization of manganese dioxide nanorods with enhanced ORR activity for alkaline membrane fuel cell

Ahmad

Nawaz

Ullah

et al. 2020

Electrochemical Science Adv

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In this study, pristine MnO2 catalyst was synthesized by hydrothermal technique and annealed at 400 and 600°C (MnO2@400°C and MnO2@600°C) transforming it into nanorods in a nitrogen atmosphere. The heat treatment process ameliorates the catalytic activity of the MnO2 catalyst by inducing oxygen vacancies. The catalyst is characterized by scanning electron microscope, and X‐ray diffraction, Fourier transforms infrared spectroscopy (FTIR), Electron paramagnetic resonance (EPR), and X‐ray Photoelectron Spectroscopy, whereas the oxygen reduction reaction (ORR) activity examined through rotating disc electrode and fuel cell test station. To elucidate the effect of sintering temperature on the MnO2 nanorods, the high angle annular dark‐field (HAADF) imaging was carried out on the samples. MnO2@400°C showed preeminent robustness to withstand austere alkaline environment during the experiment and possessed high electrocatalytic activity for the ORR with current density and onset potential values of 6.4 mA cm–2 and 0.80 V VS (RHE), respectively. The single‐cell test experiment of alkaline fuel cell delivered peak power density 81 mW/cm at 50°C. It is believed that this idiosyncratic behavior of MnO2 nanorods is due to the preferential growth on (211) and (310) indices and coexistence of optimized Mn4+/Mn3+ oxidation states as well as the creation of optimum oxygen vacancies on MnO2 nanorods. Moreover, the stretching of MnO2 nanorods occurs with increasing temperature and thus increasing the surface area to volume ratio. Thus thermal treatment shows that MnO2 is highly sensitive toward temperature variation and optimum ORR results can be obtained at adequate temperatures.

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An improvement on capacitive properties of clew-like MnO2 by thermal treatment under nitrogen

Cited by 28 publications

References 28 publications

Microwave‐Assisted Synthesis of NiMn₂O₄ Grown on Nickel Foam as Electrode Material for High‐Performance Supercapacitors

Microwave‐Assisted Synthesis of NiMn₂O₄ Grown on Nickel Foam as Electrode Material for High‐Performance Supercapacitors

Improved Capacitive Behavior of Birnessite Type Mn Oxide Coated on Activated Carbon Fibers

Thermal optimization of manganese dioxide nanorods with enhanced ORR activity for alkaline membrane fuel cell

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An improvement on capacitive properties of clew-like MnO2 by thermal treatment under nitrogen

Cited by 28 publications

References 28 publications

Microwave‐Assisted Synthesis of NiMn2O4 Grown on Nickel Foam as Electrode Material for High‐Performance Supercapacitors

Microwave‐Assisted Synthesis of NiMn2O4 Grown on Nickel Foam as Electrode Material for High‐Performance Supercapacitors

Improved Capacitive Behavior of Birnessite Type Mn Oxide Coated on Activated Carbon Fibers

Thermal optimization of manganese dioxide nanorods with enhanced ORR activity for alkaline membrane fuel cell

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Microwave‐Assisted Synthesis of NiMn₂O₄ Grown on Nickel Foam as Electrode Material for High‐Performance Supercapacitors

Microwave‐Assisted Synthesis of NiMn₂O₄ Grown on Nickel Foam as Electrode Material for High‐Performance Supercapacitors