The role of Al³⁺‐based aqueous electrolytes in the charge storage mechanism of MnOₓ cathodes

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, an in situ spectroelectrochemical methodology is used to unam...

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Published inSmall (Weinheim an der Bergstrasse, Germany) Vol. 17; no. 23; pp. e2101515 - n/a
Main Authors Balland, Véronique, Mateos, Mickaël, Singh, Arvinder, Harris, Kenneth D, Laberty‐Robert, Christel, Limoges, Benoît
Format Journal Article
LanguageEnglish
Published Weinheim Wiley 01.06.2021
Wiley Subscription Services, Inc
Wiley-VCH Verlag
Subjects
aluminium ions
Aluminum
aqueous batteries
Aqueous electrolytes
Cathodes
Chemical Sciences
conversion mechanism
Dissolution
Electrodissolution
Electrolytes
Gravimetry
Manganese dioxide
MnO 2
MnO2
Nanotechnology
Other
proton insertion
Protons
Rechargeable batteries
Storage batteries
zinc batteries
MnO 2
aqueous battery
proton insertion
zinc battery
aluminium-ion
conversion mechanism
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Summary: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, an in situ spectroelectrochemical methodology is used to unambiguously demonstrate that reversible proton-coupled MnO₂-to-Mn²⁺ conversion is the main charge storage mechanism occurring at MnO₂ cathodes for a range of slightly acidic Al³⁺-based aqueous electrolytes, with the Al³⁺ hexaaquo complex playing the key role of proton donor. In Zn/MnO₂ 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, a critical analysis of the data previously published on MnOₓ cathodes in Al³⁺-based aqueous electrolytes is conducted to conclude on a universal charge storage mechanism, i.e., the reversible electrodissolution/electrodeposition of MnO₂.
NRC publication: Yes
Bibliography:ObjectType-Article-1
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ISSN:1613-6810
1613-6829
1613-6829
DOI:10.1002/smll.202101515