Nickel and cobalt bimetallic hydroxide catalysts for urea electro-oxidation

Although cobalt hydroxide is currently added to Ni(OH)
 2
 paste to prepare nickel composite electrodes used in Ni-based rechargeable alkaline batteries, its redox chemistry in alkaline media is still poorly documented. The Co(OH)
 2
→CoOOH oxidation reaction in KOH media was investigated, and found to be dependent upon the experimental conditions, namely, temperature, oxidizing agent and reaction time. In addition, this reaction was shown, as determined by means of X-ray diffraction, electronic microscopy and atomic absorption measurements, to occur through a two step mechanism process involving first a dissolution process followed by a solid state reaction. This dissolution step enables preparation, by adjusting the cycling conditions, of cobalt oxyhydroxide with well defined morphology and texture, thereby providing an opportunity to optimize its efficiency as an additive in nickel electrodes.

Oxidation mechanism of cobalt hydroxide to cobalt oxyhydroxide

A universal equivalent circuit is proposed for carbon-based supercapacitors. The circuit, which actually applies to all porous electrodes having non-branching pores, consists of a single vertical ladder network in series with an RC parallel network. This elegant arrangement explains the three most important shortcomings of present-day supercapacitors, namely open circuit voltage decay, capacitance loss at high frequency, and voltammetric distortion at high scan rate. It also explains the shape of the complex plane impedance plots of commercial devices and reveals why the equivalent series capacitance increases with temperature. Finally, the construction of a solid-state supercapacitor simulator is described. This device is based on a truncated version of the universal equivalent circuit, and it allows experimenters to explore the responses of different supercapacitor designs without having to modify real supercapacitors.

https://link.springer.com/content/pdf/10.1007%2Fs10008-013-2328-4.pdf

A universal equivalent circuit for carbon-based supercapacitors

Nickel-cobalt nanostructures coated reduced graphene oxide nanocomposite electrode for nonenzymatic glucose biosensing

A vacuum-tight wafer carrier, and a load lock suitable for use with this wafer carrier. The wafers are supported at each side by a slightly sloping shelf, so that minimal contact (line contact) is made between the wafer surface and the surface of the shelf. This reduces generation of particulates by abrasion of the surface of the wafer. The carrier also contains elastic elements to restrain the wafers from rattling around, which further reduces the internal generation of particulates. When the wafer carrier is placed into the load lock, its body is lowered from beneath its cover through an aperture into a lower chamber, where wafers are loaded and unloaded under vacuum; the carrier cover remains covering the aperture into the lower chamber, so that the wafers never see any surface which is directly exposed to atmosphere. A wafer transport arm mechanism permits interchange of wafers among one or more processing stations and one or more load locks of this type.

Integrated circuit processing system

An investigation into the effects of adding cobalt hydroxide to nickel hydroxide electrodes has provided some insight as to why cobalt is an effective additive. The investigative techniques emphasized in situ measurements of electrode mechanical behavior rather than electrochemical data as employed previously. It is found that electrode growth markedly reduced by the addition of cobalt and conclude that increasing the amount of cobalt hydroxide in the nickel hydroxide active material results in an active material deposit of decreased mechanical rigidity. Decreasing rigidity results in less mechanical strain of the nickel sinter and thus a reduced rate of nickel electrode capacity loss due to mechanical fatigue. 9 refs.

The Mechanics of Electrochemically Coprecipitated Cobalt Hydroxide in Nickel Hydroxide Electrodes

In most electrochemical capacitor applications it is necessary to series a set of capacitors (cells) to obtain a single capacitor capable of operating at a desired voltage. Performance modeling of these devices has proven difficult because of their nonideal behavior and the need to series a large number of equivalent circuits. In this paper open literature data is analyzed using the equations derived herein. The analysis considers two different load situations, constant resistance and constant-power, for an arbitrary number of series-connected cells. Data from a device built by the Evans Electric Company,' and a prototype device are analyzed. In general, excellent agreement is obtained between the model results and the reported data. This agreement allows delineation of capacitor characteristics, at the cell level, that heretofore has not been available. However, it was found that reported data are generally not adequate to allow full capacitor characterization. In part this is due to the requirements o the derived equations, but often it is due to reported data that do not fully describe the performed experiment. In doing this analysis a hierarchy of equivalent circuits was used to provide a good data fit so as to determine capacitor cell parameters. The cell model proposed by Conway 2 and a transmission-line model were used. The dispersion of capacitance values, due to various manufacturing variables, was also modeled using a simple Beta distribution.

An Analysis of Electrochemical Capacitors

An alkali metal plus halide electrical battery cell of, for example, the sodium and sulfuryl chloride type is disclosed. The disclosed cell provides accommodation for cell chemical reaction products that otherwise preclude achievement of secondary battery action or rechargeable nature in such cells and provides two physical accommodation changes, a reaction space and a reaction space temperature, in the cell arrangement to enable repeated charge and discharge cycling of the cell. The disclosed cell is shown to be embodied in a laboratory type structure and is described with net reaction or end result equations of a combined chemical and physical nature.

Alkali and halogen rechargeable cell with reactant recombination

A low shear battery plaque and a nickel electrode fabricated therefrom, the latter consisting essentially of a centrally located layer of a conductive felt, layers of sintered nickel on each side of the felt and nickel hydroxide active material disposed throughout the pores of the sintered nickel.

Method for fabricating battery plaque and low shear nickel electrode

A method for preparing nickel electrodes is provided in which zinc hydroxide is deposited onto a metal plaque simultaneously with nickel hydroxide. A nickel electrode so prepared exhibits improved dimensional stability.

David H. Fritts

Papers

The Mechanics of Electrochemically Coprecipitated Cobalt Hydroxide in Nickel Hydroxide Electrodes

An Analysis of Electrochemical Capacitors

Alkali and halogen rechargeable cell with reactant recombination

Method for fabricating battery plaque and low shear nickel electrode

Method of nickel electrode production