Fabrication and Characterization of Thin-Film Nickel Hydroxide Electrodes for Micro-Power Applications
Bibliographic record
Abstract
INTRODUCTION Micro power sources are very attractive for nano- and micro-scale devices, such as Point-of-Care medical diagnostics and Micro Electro Mechanical Systems, where only low power densities and capacities are required. In the present work, we report on the micro-fabrication of patterned α-Ni(OH) 2 films which are suitable for rechargeable nickel metal hydride (Ni-MH) and nickel-zinc (Ni-Zn) micro-batteries as well as for micro-capacitors. The main objective of the current research is to investigate the influence of three-dimensional (3D) patterned structures on the mechanical stability as well as on the electrochemical performance of the electrode. ELECTRODE FABRICATION The patterned electrode is fabricated through multi-layered films which are deposited by employing e-beam evaporation, UV photolithography (using a negative KMPR photoresist), and electro-deposition techniques. In detail, thin films of chromium and nickel with a thickness of 40nm are deposited on glass and used as adhesion (seed) and current collector layers, respectively. NiOx/Ni(OH) 2 is electro-deposited from NiCl 2 solution followed by electro-precipitation of Ni(OH) 2 films from Ni(NO 3 ) 2 .6H 2 O aqueous solution to form a grid-like patterned layer. Figure 1 schematically depicts the fabrication process. MATERIALS & ELECTROCHEMICAL CHARACTERIZATION The chemical composition of the micro fabricated electrodes is characterized by employing X-Ray diffraction (XRD) and X-Ray photoelectron spectroscopy (XPS). The feature size of the grid-like pattern is determined to be roughly 20 microns in height by using a mechanical profilometry technique. Figure 2 illustrates the XPS spectrum of the Ni(OH) 2 electrode material based on the Ni2p3/2 spectrum. The electrochemical characteristics are studied using cyclic voltammetry (CV) in a 1M KOH electrolyte. Measurements are performed for unpatterned as well as patterned electrodes to investigate the influence of the 3D structure as shown in Figure 3. CONCLUSIONS We observe that electrode patterning considerably improves the adhesion of the α-Ni(OH) 2 film to the nickel current collector layer. It is also found that the micro fabricated α-Ni(OH) 2 electrode is reversible and diffusion limited according to the Randles-Sevcik linearity. Furthermore, the electrolyte concentration dependency is studied via CV which shows minimum concentration of around 0.2M required for good electrode REDOX reactions.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 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 | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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 teacher head, 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".