The Role of Al3+‐Based Aqueous Electrolytes in the Charge Storage Mechanism of MnOx Cathodes
Résumé
Rechargeable aqueous aluminium batteries are the subject of growing interest, however, the charge storage mechanisms at manganese oxide-based cathodes remain poorly understood. In essense, every study proposes a different mechanism. Here, we use an in situ spectroelectrochemical methodology to unambiguously demonstrate that reversible protoncoupled MnO 2-to-Mn 2+ conversion is the main charge storage mechanism occurring at MnO 2 cathodes for a range of slightly acidic Al 3+-based aqueous electrolytes, with the Al 3+ hexaaquo complex playing the key role of proton donor. In Zn/MnO 2 assemblies, this mechanism is associated with high gravimetric capacities and discharge potentials, up to 560 mAh•g-1 and 1.65 V respectively, attractive efficiencies (CE > 99.5 % and EE > 82%) and excellent cyclability (almost 100% capacity retention over 1 400 cycles at 2 A•g-1). Finally, we conducted a critical analysis of the data previously published on MnO x cathodes in Al 3+-based aqueous electrolytes to conclude on a universal charge storage mechanism, i.e., the reversible electrodissolution/electrodeposition of MnO 2 .
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Autre
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Balland_2021_manuscript final version HAL.pdf (1.32 Mo)
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Balland_2021_SI final version HAL.pdf (947.41 Ko)
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Origine | Fichiers produits par l'(les) auteur(s) |
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