Electrodes zinc electrode additives

Zinc/carbon (Leclanchc cell) Electrode additive, current collector... 

It is to be noted that zinc is not deposited on the zinc electrode. In the case of this cell, the second condition of reversibility is not satisfied even though the first condition may be satisfied. The cell is, therefore, irreversible. As an additional example of cell irreversibility mention may be made of the cell having a liquid junction. 

The aging behavior of the porous zinc electrode in 6 M KOH in the presence of different electrolyte additives such as ZnO, LiOH, and KF has been studied using cyclic voltammetry by Shivkumar etal. [212]. The mechanism of the electrode reaction in all these electrolytes was investigated. 

There were also studied processes that cause passivation of the zinc electrode in many cycling operations of Ni-Zn batteries [323]. Positive effect for increasing the reaction reversibility was found when zinc-ion additives were introduced to the positive electrode [324]. 

For the development of a long-lived, electrically rechargeable zinc-air battery, the structure and wettability of pasted zinc electrodes (with 1-10% cellulose) were optimized [330]. It was found that the addition of 10 wt % cellulose to the pasted zinc electrode, improved the life cycle and peak power drain capacity of the battery substantially. 

An application of thick-film printing technology for the fabrication of a Zn-Mn02 alkaline batteries [342] was also described. The mechanism of the capacity fade of rechargeable alkaline zinc-manganese cell was studied and discussed [343]. Zinc electrode with addition of several oxides (HgO, Sb203) for alkaline Zn-Mn02 cells [344] was also studied. 

Various problems related to the construction and performances of these batteries, such as changes in materials of membranes and additives both to the electrode materials and to the electrolyte, were studied in recent years. Some instability of the silver electrode during such storage period and the ways of avoiding these difficulties were studied and discussed [347]. Reserve activated silver oxide-zinc cells were constructed [348] with synthetic Ag20 and Pb-treated zinc electrodes were produced by a nonelec-trolytic process. The cells were tested before and after thermally accelerated aging. 

In addition, the separator must have a low electrical resistance, good thermal and chemical stability and must be light in order to retain the high energy density characteristics of the cell. Practical separators have a composite multilayer configuration. A silver-stopping layer of cellophane or non-woven synthetic polyamide is located next to the positive electrode which reduces soluble silver species back to the metal. A potassium titanate paper layer may be placed next to the zinc electrode, and a number of cellophane layers which swell in aqueous KOH make up the middle section. In most cells the separators are fabricated as envelopes or sacks which completely enclose the zinc electrodes. 

Delaurier cell — This was a chromic acid (carbon electrode)-zinc - battery with a chromic acid electrolyte that contained additionally iron(lll) sulfate. See also - chromic acid battery, -> Daniell cell, -> zinc, -> Zn2+/Zn electrodes, -> Zn2+/Zn(Hg) electrodes, -> zinc-air batteries (cell), and - Leclanche cell. 

Corrosion of zinc was initially prevented by amalgamation of the zinc electrode (i.e., by adding soluble mercury salts which result in a mercury deposit by -> cementation). Currently organic additives are used for corrosion prevention. 

Jasaitis et al. (1983) proposed a carbon electrode with covalently bound alkaline phosphatase (AP) for the determination of Zn2+. Apo-phosphatase was created by treating the electrode with EDTA. Addition of a zinc ion-containing sample restored the enzymatic activity of AP within 30 s as demonstrated by the formation of electrode-active hy-droquinone from hydroxyphenyl phosphate. After each measurement the electrode was regenerated by treatment with EDTA. As little as 0.8 pmotyl of Zn2+ could be detected. 

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