Asymmetric Supercapacitors Based on Activated‐Carbon‐Coated Carbon Nanotubes
Bibliographic record
Abstract
Abstract A new method is developed for the fabrication of asymmetric supercapacitor devices containing fibrous electrode materials. The approach is based on the synthesis of uniform polypyrrole (PPy) coatings on multiwalled carbon nanotubes (MWCNT), which were used for the fabrication of MWCNTs coated with N‐doped activated carbon (N‐AC). The N‐AC‐MWCNT electrodes show good electrochemical performance in positive and negative potential windows. The electrochemical performance of positive electrodes is further enhanced by the development of MnO2‐coated N‐AC‐MWCNT. In this approach, the problem of MWCNT degradation in the reaction with KMnO4 is avoided by the use of a sacrificial N‐AC layer, which allows a relatively high mass content of MnO2 in the final material. The approach offers the advantages of small size of MnO2 nanoparticles, good electrical contact of MnO2 and MWCNT and fibrous microstructure of the material. Testing results show a remarkably high specific capacitance of 6.29 F cm−2 (311.7 F g−1) at a mass loading of 20 mg cm−2. The important finding is the possibility to fabricate asymmetric devices, which show a specific capacitance of 2.19 F cm−2 (62.7 F g−1) in a voltage window of 1.9 V in aqueous Na2SO4 electrolyte, an energy density of 26.4 mWh g−1 and a power density of 1.7 W g−1. The electrodes and devices show good capacitance retention at high charge–discharge rates and good cycling stability. The asymmetric capacitors developed herein are promising for practical energy‐storage applications.
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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 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".