On the Source of Conductivity in Alkaline Zn Anodes: Zn Percolation and ZnO Bridging

Journal Article · Wed Mar 12 00:00:00 EDT 2025 · Journal of the Electrochemical Society

DOI:https://doi.org/10.1149/1945-7111/adacc4· OSTI ID:3019750

Guida, Dominick P. ^[1]; Chuang, Andrew Chihpin ^[2]; Okasinski, John S. ^[2]; Wendling, Matthew T. ^[3]; Chadderdon, Xiaotong H. ^[3]; Gallaway, Joshua W. ^[1]

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1. Northeastern Univ., Boston, MA (United States)
2. Argonne National Laboratory (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
3. Energizer Holdings, Inc., Westlake, OH (United States)

Alkaline Zn anodes are fundamental to commercial Zn-MnO₂ batteries as well as emerging rechargeable designs. In these electrodes, Zn particles are both the active material and source of electronic conduction. However, there are known cases in which electronic connectivity between Zn particles or the current collecting pin is lost even though the battery continues to function. Here we use X-ray computed tomography (CT) of AA batteries to demonstrate several examples of Zn particle-to-particle connectivity breakdown, which is observed even in cases at relatively high discharge rate. This indicates maintenance of the electronic network through the less-conductive ZnO discharge product. We introduce a new equation for electronic conductivity maintained through bridges of ZnO formed between percolating Zn particles. This necessitates discarding the Bruggeman correlation and instead redefining effective electronic conductivity using percolation theory. We demonstrate that such a model for conduction enables prediction of an inverted reaction zone, which is an experimentally observed case in which significant Zn dissolution and ZnO formation occurs heavily near the current collecting pin. Current computational Zn-MnO₂ models never predict an inverted reaction zone, and thus the updated conductivity enables models to accurately explain a wider range of experimental conditions.

• Research Organization: Argonne National Laboratory (ANL), Argonne, IL (United States)
• Sponsoring Organization: National Science Foundation (NSF); USDOE Office of Science (SC), Basic Energy Sciences (BES). Scientific User Facilities (SUF)
• Grant/Contract Number: AC02-06CH11357
• Other Award/Contract Number: CBET-ES-2044602
• OSTI ID: 3019750
• Journal Information: Journal of the Electrochemical Society, Journal Name: Journal of the Electrochemical Society Journal Issue: 3 Vol. 172; ISSN 1945-7111; ISSN 0013-4651
• Publisher: IOP Publishing
• Country of Publication: United States
• Language: English