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___________________________________________________ UDC: 621.355.9 Technical mechanics, 2024, 2, 124 - 136 MASS TRANSFER IN THE POROUS ELECTRODES OF A LEAD-ACID BATTERY DURING ITS DISCHARGE Yeliseyev V. I., Sovit Yu. P., Katrenko M. O.
Yeliseyev V. I.
At present, the study of diffusion-controlled processes with volume and heterogeneous chemical reactions
plays an important role in various systems, in particular engineering ones, which include electric
current sources. Based on familiar equations, this work considers ion exchange processes in the porous
spaces of the electrodes of a lead-acid battery during its discharge. Allowance is made for
electrochemical processes between the solid electrodes and the electrolyte that fills the porous space.
As distinct from the majority of works, allowance is also made for the two-dimensionality of the
process, which is due to the geometry of the apparatus and its physical characteristics. An important
feature of the work is that in the open zone between the electrodes, the mass transfer is assumed to be
convective, whose intensity is much higher than that of the diffusive one in the pores of the electrodes.
This allows one to ignore, at least as a first approximation, the resistance of the central zone of the
electric cell in the process of ion transfer. This, as one might say, limiting scheme, greatly simplifies
the problem of charge transfer through the central zone of the electrochemical cell. It is shown that the
electrical conductivity of the solid part of the electrodes plays an important role in the distribution
of potentials both in the electrodes themselves and in the porous space. Due to the high electrical
conductivity, the negative electrode relative to the positive one operates practically in a
one-dimensional mode. It should also be noted that the additional resistance of the separator has a
noticeable effect on the operation of the positive electrode, which manifests itself at relatively high
currents, when the lack of the charging component becomes noticeable. Another important aspect of the
calculation is the determination of the distribution of poorly soluble and poorly conductive lead sulfate
(PbSO4), which affects the mass transfer process to a large extent, up to the termination of the discharge.
It is shown that at relatively high currents, the formation of the passivating product is concentrated on
the outer sides of the electrodes.
lead-acid battery, anode, cathode, system of equations, porosity, potential, diffusion transfer
1. Dasoyan M. A., Aguf I. A. Current Theory of Lead Acid Batteries. Stonechouse Glos. Technicopy Limited, 1979. 371 pp.
Copyright (©) 2024 Yeliseyev V. I., Sovit Yu. P., Katrenko M. O. Copyright © 2014-2024 Technical mechanics ____________________________________________________________________________________________________________________________ |
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