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Journal of Applied Electrochemistry

, Volume 17, Issue 6, pp 1281–1295 | Cite as

Influence of various coated paper separator materials on the corrosion, polarization and impedance characteristics of zinc in concentrated soldium chloride solution

  • L. M. Baugh
  • N. C. White
Papers

Abstract

The corrosion characteristics of amalgamated zinc have been studied in 2.7M NaCl at pH 4.8 using steady-state polarization and a.c. impedance methods, and the influence of various coated paper separators has been determined. It is shown that the polarization behaviour in either the presence or absence of the separator materials can be interpreted if due consideration is given to diffusion and charge transfer effects. The anodic zinc dissolution process is jointly controlled by these effects whereas the cathodic hydrogen evolution (proton reduction) process is diffusion limited.

Using a simple model which takes into account the quasi-reversible nature of the zinc dissolution process, good agreement between calculated and observed current inhibition factors can be obtained if the surface blocking (coverage) effect of the separators is combined with the effect of the change in diffusion path length through the separator pores. Application of this model to the diffusionlimited hydrogen evolution reaction, however, fails unless the blocking term is ignored.

Keywords

Hydrogen Evolution Diffusion Path Impedance Characteristic Hydrogen Evolution Reaction Polarization Behaviour 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Nomenclature

Ae

area fraction of electrolyte in contact with the electrode

Ap

area fraction of polymer in contact with the electrode

ba

anodic slope of semi-logarithmic current-potential plot

bc

cathodic slope of semi-logarithmic current-potential plot

C

surface concentration of zinc species in the absence of the separator

Cs

surface concentration of zinc species in the presence of the separator

Cb

bulk concentration of protons

Cdl

double layer capacity

D

diffusion coefficient in the absence of the separator

Ds

diffusion coefficient in the presence of the separator

i

current in the absence of the separator

is

current in the presence of the separator

ict

charge transfer current

id

diffusion current

ic

cathodic current

i0

exchange current

icor

corrosion current

\(i_{cor}^{R_{de} } \)

corrosion current derived fromRde value

\(i_{cor}^{R_p } \)

corrosion current derived fromRp value

icorExt

corrosion current derived by extrapolation of polarization curves

icorBat

corrosion current estimated in complete batteryenvironment

Icor

corrosion inhibition efficiency (%)

kf

potential-dependent forward rate constant

kb

potential-dependent backward rate constant

l

mean pore length

re

resistance of free electrolyte having the same overall volume and geometry as the separator

rs

resistance of electrolyte within the separator matrix

RΩ

resistance of electrolyte between Luggin reference probe and electrode surface in the absence of the separator

RΩs

resistance of electrolyte between Luggin reference probe and electrode surface in the presence of the separator

Rct

charge transfer resistance

Rdc

d.c. resistance

Rp

polarization resistance

l

thickness of the separator

tp

thickness of the base paper

tc

thickness of the coating layer

Ve

volume fraction of electrolyte in the separator

x

distance of Luggin reference probe from electrode surface (absence of separator) or electrolyte exposed outer separator surface (presence of the separator)

δ

diffusion layer thickness

θ

tortuosity factor

Subscripts/superscripts

1,2

separator 1,2

A,B,C

separator A,B,C

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References

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Copyright information

© Chapman and Hall Ltd. 1987

Authors and Affiliations

  • L. M. Baugh
    • 1
  • N. C. White
    • 1
  1. 1.Technical DivisionEver Ready LtdStanleyUK

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