Experimental determination of the effective electrolyte conductivity in porous lead electrodes in the lead-acid battery
1997 (English)In: Electrochimica Acta, Vol. 42, no 8, 1239-1246 p.Article in journal (Refereed) Published
An electrochemical impedance technique which measures the impedance between two reference electrodes placed on opposite sides of the working electrode, and which can be used for the determination of the effective conductivity in the pore electrolyte in a porous electrode is presented. Information about the electroactive surface area and kinetic parameters can also be obtained from these measurements. A theoretical expression for the evaluation of the experimental results has been derived and analysed. The high frequency intercept of the impedance curve with the real axis will give the external ohmic resistance for electrode materials with an infinitely high conductivity. Even at very low frequencies, some of the current passing through the electrode will pass through the electrode in the solid material. The relative importance of this transfer of current in the solid phase through the electrode can be determined for the general case by the dimensionless quantity Î», which depends on the electrode thickness, the effective conductivity of the pore electrolyte and the local impedance. Two limiting cases can be observed. A comparison between this type of measurement and conventional electrochemical impedance spectroscopy measured between the working electrode and a reference electrode shows that the difference between the two methods depends on the relative magnitude of the local impedance. The method has been used for the evaluation of data for a porous lead electrode in the lead-acid battery system. The experimental data obtained at different states of discharge have been analysed by means of an impedance model, which takes into account the distribution of the local impedance in the porous structure, as well as the electrochemical reaction and mass transfer limitations in the electrode. Good agreement between the experimental data and the model has been obtained. Â© 1997 Elsevier Science Ltd. All rights reserved.
Place, publisher, year, edition, pages
1997. Vol. 42, no 8, 1239-1246 p.
Effective conductivity measurements, Electrochemical impedance spectroscopy, Lead electrode, Lead-acid battery, Porous electrode
IdentifiersURN: urn:nbn:se:kth:diva-80623OAI: oai:DiVA.org:kth-80623DiVA: diva2:496819
Source: Scopus NR 201408052012-02-102012-02-102012-02-10Bibliographically approved