Effect of the Components of the Electrode on the Pore Texture and Electrochemical Performance of Manganese Dioxide-Based Electrode for Application in Hybrid Electrochemical Capacitor <sup>1</sup>
Bibliographic record
Abstract
In the 1970s, Conway and others observed that the reversible redox processes occurring at or near the surface of an appropriate electrode material led to electrical double layer capacitor (EDLC)-like electrochemical properties and also a higher charge storage.2 Later, Lee and Goodenough were the first to report the pseudocapacitive behavior of manganese dioxide.3 Since that, it has been widely studied as active electrode material for application in aqueous electrochemical capacitors. Due to the low potential stability window of MnO2-based electrode of about 1V, a hybrid electrochemical capacitor using electrodes with different potential range has been proposed.4 Such hybrid electrochemical capacitor can consist of a carbon negative electrode, a manganese dioxide-based positive electrode and a mild neutral electrolyte.5 Manganese dioxide is characterized by a theoretical specific capacitance of about 1233 F/g, which is far from being experimentally attainable.6 Even for very thin film (< 100 nm) and very low mass (< 100 µg) loading, of MnO2, the specific capacitance rarely exceeds 1000 F/g.7-9 On the other hand, in the case of thicker composite electrode and higher loading of MnO2 the electrochemically addressable material is commonly in the 10 to 20 % range. 10, 11 To meet the requirements mentioned above, more fundamentals studies are needed to understand the role of all components of a composite electrode. Composite electrode based on manganese dioxide, a binder (poly(tetrafluoroethylene, PTFE) and a carbon additive (Acetylene black or high surface area Black Pearls 2000) were characterized by scanning electron microscopy and nitrogen gas adsorption. The electrochemical performances of the MnO2-Carbon-PTFE composite electrodes materials are evaluated by cyclic voltammetry. Brunauer–Emmett–Teller (BET) surface area measurements indicate that the addition of the PTFE binder does not block access to the porous network of MnO2 and the two carbon powders. Only acetylene black appears to slightly adversely affect the mesoporous surface, presumably because of its larger particle size compared to Black Pearls 2000. The electrochemical utilization of MnO2 is similar whether acetylene black or Black Pearls 2000 is used as carbon additive. This suggests that the porosity of Black Pearls, which could perhaps act as a reservoir of ionic species, does not appear to play a significant role as demonstrated by similar specific capacitance at slow scan rate. On the other hand, the effect of additional conductive agent such as acetylene black induces a slight increase of the specific capacitance at high scan rate. Finally, a plot of Coulombic efficiency as a function of the upper positive potential limit showed that using a high surface carbon support with MnO2 can cancel the effect of the larger potential window of electroactivity of MnO2 because of its smaller electrochemical potential stability range. References 1. A. Gambou-Bosca and D. Belanger, Journal of Materials Chemistry A, 2014 DOI: 10.1039/ c3ta14910b. 2. P. Simon, Y. Gogotsi and B. Dunn, Science, 2014, 343, 1210-1211. 3. H. Y. Lee and J. B. Goodenough, Journal of Solid State Chemistry, 1999, 144, 220-223. 4. T. Brousse and D. Bélanger, Electrochemical and Solid-State Letters, 2003, 6, A244-A248. 5. J. W. Long, D. Bélanger, T. Brousse, W. Sugimoto, M. B. Sassin and O. Crosnier, MRS Bulletin, 2011, 36, 513-522. 6. M. Toupin, T. Brousse and D. Bélanger, Chemistry of Materials, 2004, 16, 3184-3190. 7. R. Ranjusha, A. Sreekumaran Nair, S. Ramakrishna, P. Anjali, K. Sujith, K. R. V. Subramanian, N. Sivakumar, T. N. Kim, S. V. Nair and A. Balakrishnan, Journal of Materials Chemistry, 2012, 22, 20465-20471. 8. Suhasini, Journal of Electroanalytical Chemistry, 2013, 690, 13-18. 9. T. Bordjiba and D. Bélanger, Electrochimica Acta, 2010, 55, 3428-3433. 10. P. Staiti and F. Lufrano, Journal of Power Sources, 2009, 187, 284-289. 11. A. Zolfaghari, H. R. Naderi and H. R. Mortaheb, Journal of Electroanalytical Chemistry, 2013, 697, 60-67.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".