Impact of the charging conditions on the discharge performance of rechargeable iron-anodes for alkaline iron–air batteries
Pressed-plate carbonyl iron electrodes for rechargeable iron–air batteries have recently been described to undergo a considerable electrochemical formation before they attain a stable and competitive discharge capacity in concentrated alkaline electrolyte. In this study, the impact of the charging conditions on the discharge performance due to electrochemical formation was investigated. Based on the results, it is demonstrated that the preset charge capacity mainly determines the resulting discharge capacities of the porous electrodes in the steady state at the end of the formation period. Furthermore, the present study elucidates the electrode processes behind formation and expands the existing phenomenological model that has recently been established to explain the evolution of the discharge capacity. Finally, feasible criteria for the comparison of different anode architectures are discussed.
KeywordsRechargeable iron–air batteries Carbonyl iron electrodes Sulfide additives Formation Increasing surface area
The authors kindly acknowledge the financial support from the German Federal Ministry of Education and Research (BMBF) within the project “High Temperature and Energy Materials - Resource-Efficient Metal-Air Batteries with High Energy Density” Project No. 03EK3032 and the project SABLE “Skalenübergreifende, multi-modale 3D-Bildgebung Elektrochemischer Hochleistingskomponenten” Project No. 03EK3543. Moreover, the authors appreciate the support by C. Hellenbrandt and the SEM supervision by R. Schierholz at the Institute of Energy and Climate Research – Fundamental Electrochemistry (IEK-9), Forschungszentrum Jülich.
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