Nickel cadmium, secondary cell reactions

Nickel(lll) oxide, prepared from a nickel(ii) salt and sodium hypochlorite, is used for the oxidation of alkanols in aqueous alkali [46]. Residual nickel(Ii) oxide can be re-activated by reaction with sodium hypochlorite. Nickel oxides have also long been used in the manufacture of the positive pole in the Edison nickel-iron rechargeable battery, now largely superseded by die lead-acid accumulator, and in the Jungner nickel-cadmium batteries used as button cells for calculators [47]. Here, prepared nickel oxide is pressed into a holding plate of perforated nickel. Such prepared plates of nickel(lli) oxide have been proposed as reagent for the oxidation, in alkaline solution, of secondary alcohols to ketones and primary alcohols to carboxylic acids [48]. Used plates can be regenerated by anodic oxidation. 

E) Nickel-Cadmium (NiCd or "nicad") secondary (rechargeable) cell, invented by Jugner86 in 1899, uses nickel oxyhydroxide NiO(OH) and Cd metal as electrodes in the discharge mode the cell reaction is... 

Ni-Cd cells — The nickel-cadmium cell is a secondary - battery that has a nominal cell potential of 1.20-1.25 V. The negative electrode comprises nickel hydroxide-nickel oxyhydroxide, the positive electrode is cadmium, and the electrolyte solution is based on aqueous potassium hydroxide (KOH, 32% in water). At the anode, the discharge reaction is the oxidation of cadmium metal to cadmium hydroxide with the release of two electrons [i] ... 

The nickel-cadmium battery is the most popular alkaline secondary battery. The cell and its reaction are ... 

Leclanche cells are not rechargeable once the reactants are depleted, the battery must be discarded and replaced. Batteries that are not rechargeable are called primary batteries. A rechargeable battery is called a secondary battery or a storage battery. The nickel-cadmium (NiCd) battery is a popular rechargeable battery that uses the following redox reaction ... 

BATTERIES AND FUEL CELLS (SECTION 20.7) A battery is a self-contained electrochemical power source that contains one or more voltaic cells. Batteries are based on a variety of different redox reactions. Batteries that cannot be recharged are called primary cells, while those that can be recharged are called secondary cells. The common alkaline dry cell battery is an example of a primary cell battery. Lead-acid, nickel-cadmium, nickel-metal hydride, and lithium-ion batteries are examples of secondary cells. Fuel cells are voltaic cells that utilize redox reactions in which reactants such as H2 have to be continuously supphed to the cell to generate voltage. 

In battery systems based on aqueous electrolyte, water decomposition, which occurs above a cell voltage of 1.23 V, is such an unavoidable secondary reaction. But under certain conditions the resulting water loss can be avoided, and the system is used as a sealed one, as achieved with sealed nickel/cadmium, nickel/hydrogen, and nickel/metal hydride batteries. In lead-acid batteries corrosion is an additional unwanted secondary reaction with the consequence that lead-acid batteries cannot be made virtually sealed, but must have a valve, and a certain water loss cannot be prevented. 

This is the discharge process. If this were a primary non-rechargeable cell, at the end of discharge, it would be exhausted and discarded. The nickel-cadmium battery system is, however, a secondary (rechargeable) system, and on recharge the reactions are reversed. At the negative electrode the reaction is ... 

Zinc-carbon, alkaline, and mercury cells are primary batteries, which are not rechargeable. Batteries that are rechargeable are called secondary batteries, or storage batteries. A storage battery produces energy from a reversible redox reaction, which occurs in the opposite direction when the battery is recharged. A nickel-cadmium rechargeable battery is an example of a secondary battery. 

Unlike the cells above, which are all primary cells, this is a secondary (i.e. rechargeable) cell, and the two poles are composed in the uncharged condition of nickel and cadmium hydroxides respectively. These are each supported on microporous nickel, made by a sintering process, and separated by an absorbent impregnated with electrolyte. The charging reactions are ... 

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