The importance of the cathode specific interfacial area in modeling a cylindrical alkaline cell

Low initial cell voltage predictions from a mathematical model of a Zn/MnO2 cylindrical alkaline cell are corrected by increasing the cathode specific interfacial area. A simplified model of the cathode region is used to estimate the initial polarization loss when the cathode specific interfacial area is changed, for a particular AA-size design and galvanostatic discharge rate. The model expression for the cathode specific interfacial area is reformulated to match the literature values for this quantity more closely. A new formulation is accepted as the revision, and the discharge time improvement is substantial with respect to the base case when simulations using the complete model are performed. The physical effects of raising the cathode specific interfacial area are analyzed. The increased discharge time leads to a localized region in the cathode that is totally depleted of zincate ion. This creates numerical problems in the cell voltage calculation. (C) 1999 Elsevier Science S.A. All rights reserved.