Charge storage mechanisms of birnessite-type MnO2 nanosheets in Na2SO4 electrolytes with different pH values: In situ electrochemical X-ray absorption spectroscopy investigation

Tanggarnjanavalukul, Chan; Phattharasupakun, Nutthaphon; Wutthiprom, Juthaporn; Kidkhunthod, Pinit

doi:10.1016/j.electacta.2018.04.022

Cited by 36 publications

(30 citation statements)

References 50 publications

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“…Initially, 0.1 wt% MnO 2 NT were added to the previously optimized CB/CNT dispersion resulting in: 0.01 wt% CB, 0.09 wt% CNT, 0.1 wt% MnO 2 NT, pH = 1.5, SDBS/(CB-CNT-MnO 2 NT) ratio = 1.5. We found this solution was not spinnable probably due to the instability of MnO 2 at pH = 1.5 [44]. However, we were able to synthesise fibres from dispersions with pH in the range from 2.5 to 6.5.…”

Section: Resultsmentioning

confidence: 82%

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One-step wet-spinning process of CB/CNT/MnO2 nanotubes hybrid flexible fibres as electrodes for wearable supercapacitors

García-Torres

Roberts

Slade

et al. 2019

Electrochimica Acta

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Fibres made from different nanostructured carbons (carbon black (CB)), carbon nanotubes (CNT) and CB/ CNT were successfully developed by wet-spinning. The variation of dispersion conditions (carbon nanomaterial concentration, dispersant/Carbon nanomaterial concentration ratio, CB/CNT concentration ratio, pH) resulted in different electrochemical performance for each type of fibres. Fibres with the best capacitance values (10 F g −1) and good cycling stability (89%) were obtained from fibres containing 10% carbon black and 90% carbon nanotubes. A solid-state supercapacitor was fabricated by assembling the CB/CNT fibres resulting in 9.2 F g −1 electrode capacitance. Incorporation of 0.2 wt% birnessite-type potassium manganese oxide nanotubes dramatically increased the capacitance of the fibres up to 246 F g −1 due to the high specific capacitance of birnessite phase and the tubular nature of the nanomaterial.

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Section: Resultsmentioning

confidence: 82%

“…Moreover, the deviation from the ideal CV curves is observed, the curves becoming less ideal as the pH decreases ( Fig. 8C) because some parts of the MnO 2 NT can be dissolved in acidic dispersions causing the loss of the active material and therefore lower capacitance [44,51]. Thus, the enclosed areas of CV curves are smaller at more acid pH.…”

Section: Resultsmentioning

confidence: 97%

One-step wet-spinning process of CB/CNT/MnO2 nanotubes hybrid flexible fibres as electrodes for wearable supercapacitors

García-Torres

Roberts

Slade

et al. 2019

Electrochimica Acta

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“…Changes in lattice parameters, ion adsorption/desorption, chemical bonding formation/breakage, dimensional/mass change, etc., are involved in the electrochemical process. [ 6–9 ] Several advanced characterization techniques (in situ X‐ray diffraction [XRD], in situ X‐ray scattering, in situ atomic force microscopy [AFM], in situ nuclear magnetic resonance [NMR], in situ Raman/infrared (IR) spectroscopy, electrochemical quartz crystal microbalance [EQCM], scanning electrochemical microscopy [SECM], etc.) have been utilized to study the dynamic processes in SCs.…”

Section: Introductionmentioning

confidence: 99%

Electrochemical Supercapacitors: From Mechanism Understanding to Multifunctional Applications

Chen

Lee

2020

Advanced Energy Materials

150

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Electrochemical supercapacitors (SC) with high power and long cycle life have been extensively studied and applied in certain areas. However, a majority of the efforts have been devoted to developing SCs with improved performance through novel electrode/electrolytes design. The full mechanistic understanding of SCs based on different electrode materials has not yet been realized. In addition, exploration of new functions for SCs to widen their applications must be accelerated. In this essay, the use of advanced characterization methods (in situ X‐ray diffraction, in situ X‐ray scattering, in situ atomic force microscopy, in situ nuclear magnetic resonance, in situ Raman/infrared spectroscopy, electrochemical quartz crystal microbalance, scanning electrochemical microscopy, etc.) to unveil the electrochemical process of SCs from different aspects will be discussed. The working principles, information to be extracted, and case studies of respective methods will be presented. The multipronged mechanism studies of electrode properties inspire and enable exploration of extra functions within the same electrochemical SCs. Realization of mechanically deformable, low‐temperature, color tunable, self‐healable, and self‐chargeable SCs; integrated SC‐sensors; and SC‐actuators with adoption of new electrode/electrolyte/current collectors/configurations are showcased. The remaining issues hindering the wide exploitation of SCs and the future development trend of SCs are also discussed.

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“…[ 15 ] In typical MnO 2 ‐based supercapacitors, sodium sulfate (Na 2 SO 4 ) is commonly used as an electrolyte, and a single Na + ion can only change an Mn atom from tetravalent to trivalent during the discharge process. [ 16 ] In contrast, a multivalent cation such as Ca 2+ , [ 17 ] Zn 2+ , [ 18 ] Mg 2+ , [ 19 ] Al 3+[ 20 ] can transfer twice or even three times more electrons to the electrode material. [ 21–23 ] The multivalent cation‐based electrolyte can thus provide a promising strategy for improving the performance of supercapacitors due to the charge transfer efficiency.…”

Section: Introductionmentioning

confidence: 99%

New Insight into the Mechanism of Multivalent Ion Hybrid Supercapacitor: From the Effect of Potential Window Viewpoint

Liu

Zhang

Sun

et al. 2020

Small

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Multivalent ion hybrid supercapacitors have been developed as the novel electrochemical energy storage systems due to their combined merits of high energy density and high power density. Nevertheless, there are still some challenges due to the limited understanding of the electrochemical behaviors of multivalent ions in the electrode materials, which greatly hinders the large scale applications of its based hybrid supercapacitors. Herein, the long‐term electrochemical behaviors of MnO2‐based electrode in the divalent Mg2+ ions electrolyte are systematically studied and linked with the morphological and electronic evolution of MnO2 by cycling at different potential windows (spanning to 1.2 V). It reveals that the different potential windows result in the different electrochemical behaviors, which can be divided into two ranges (below and above −0.2 V). And, the electrode cycled at a potential window of 0–1.2 V delivers the highest capacitance of 967 F g−1 at a scan rate of 10 mV s−1, in which the MnO2 is transformed into a uniformly distributed and nonagglomerated nanoflake morphology promoting the intercalation and deintercalation of Mg2+ ions. This study will enrich the understanding of the charge storage mechanism of multivalent ions and provide significant guidance on the performance improvement of the hybrid supercapacitors.

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Charge storage mechanisms of birnessite-type MnO2 nanosheets in Na2SO4 electrolytes with different pH values: In situ electrochemical X-ray absorption spectroscopy investigation

Cited by 36 publications

References 50 publications

One-step wet-spinning process of CB/CNT/MnO2 nanotubes hybrid flexible fibres as electrodes for wearable supercapacitors

One-step wet-spinning process of CB/CNT/MnO2 nanotubes hybrid flexible fibres as electrodes for wearable supercapacitors

Electrochemical Supercapacitors: From Mechanism Understanding to Multifunctional Applications

New Insight into the Mechanism of Multivalent Ion Hybrid Supercapacitor: From the Effect of Potential Window Viewpoint

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