Vanadium Nitride Electrodes: Limitations and Practical Use in Electrochemical Capacitors
Bibliographic record
Abstract
Vanadium nitride has displayed many interesting characteristics for its use as a pseudocapacitive [1] electrode in an electrochemical capacitor, such as good electronic conductivity, good thermal stability, high density and high specific capacitance. Thin films of VN were prepared by D.C. reactive magnetron sputtering. The electrochemical stability of the films as well as the influence of dissolved oxygen in 1 M KOH electrolyte were investigated. In order to avoid material as well as electrolyte degradation, it was concluded that vanadium nitride should only be cycled between -0.4 and -1.0 V vs. Hg/HgO. After a 24 hours stabilization period, the prepared VN thin film showed an initial capacitance of 19 mF.cm-2 and a capacity retention of 96% after 10000 cycles. Furthermore, dissolved oxygen in the electrolyte was demonstrated to cause self-discharge up to a potential above -0.4 V vs. Hg/HgO, where VN was shown to be unstable. Additionally, the presence of oxygen was shown to shift the open circuit potential of a VN electrode to about 0 V through self-discharge processes [2]. Since the performances reached on thin film electrodes are difficult to translate to VN powder, the use of VN thin films in hybrid microdevices has been investigated [3]. Microdevices were designed using VN thin films as negative electrode and electrodeposited Co3O4 as positive electrode in order to combine the high capacity of the Faradaic type cobalt based electrode and the high capacitance and good cycling ability of VN electrode when used in an optimized electrochemical window. The performance of such devices will be reported and discussed with regards to existing literature on the field. References [1] Brousse, T.; Belanger, D.; Long, J. W. J. Electrochem. Soc. 2015, 162, A5185–A5189. [2] Morel, A.; Borjon-Piron, Y.; Lucio Porto, R.; Brousse, T.; Bélanger, D.; J. Electrochem. Soc. 2016, 163, A1077-A1082. [3] Eustache, E.; Frappier, R.; Porto, R. L.; Bouhtiyya, S.; Pierson, J.-F.; Brousse, T. Electrochem. Commun. 2013, 28, 104–106.
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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 | 0.003 | 0.004 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.002 | 0.002 |
| Open science | 0.003 | 0.001 |
| Research integrity | 0.002 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.001 |
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".