Influence of Microstucture on the Charge Storage Properties of Chemically Synthesized Manganese Dioxide
Bibliographic record
Abstract
α-MnO 2 was synthesized by a very simple coprecipitation technique and tested as active electrode material for an electrochemical supercapacitor. The powder presents a poorly crystallized cryptomelane phase with a chemical composition of K 0.05 MnO 2 H 0.10 ·0.15H 2 O. Different aqueous electrolytes were tested including 0.1 M Na 2 SO 4, 0.5 M K 2 HPO 4 /KH 2 PO 4 buffer solution, 0.3 M H 2 SO 4, and 1 M NaOH, but interesting pseudocapacitance behavior was only observed in the case of 0.1 M Na 2 SO 4 . Further testing using this electrolyte showed that an average capacitance of 166 F/g can be reproducibly obtained within a voltage range −0.4/+0.5 V vs Hg/Hg 2 SO 4 using a sweep rate of 2 mV/s. This interesting value is mainly due to the chimisorption of Na + ions and/or protons at the surface of the α-MnO 2 electrode. Nearly all the Mn surface atoms are involved in the pseudocapacitive process. Therefore, the high specific capacitance seems to be related to the high surface area of the MnO 2 powder rather than intercalation of Na + ions and/or protons in the structure of α-MnO 2 . An optimum composition of 80% of active material in the composite electrode was determined. With such a composition, the α-MnO 2 electrode can withstand 1000 cycles with 100% capacitance retention.
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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 | 0.001 |
| 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 | 0.000 | 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".