am9b19349_si_001.pdf (1.51 MB)
Elucidating the Origin of the Electrochemical Capacity in a Proton-Based Battery HxIrO4 via Advanced Electrogravimetry
journal contribution
posted on 2020-01-17, 13:33 authored by Pierre Lemaire, Ozlem Sel, Daniel Alves Dalla Corte, Antonella Iadecola, Hubert Perrot, Jean-Marie TarasconRecently,
because of sustainability issues dictated by societal demands, more
importance has been given to aqueous systems and especially to proton-based
batteries. However, the mechanisms behind the processes leading to
energy storage in such systems are still not elucidated. Under this
scope, our study is structured on the selection of a model electrode
material, the protonic phase HxIrO4, and the scrutiny of the interfacial processes through suitable
analytical tools. Herein, we employed operando electrochemical quartz
crystal microbalance (EQCM) combined with electrochemical impedance
spectroscopy (EIS) to provide new insights into the mechanism
intervening at the electrode–electrolyte interface. First,
we demonstrated that not only the surface or near surface but the
whole particle participates in the cationic redox process. Second,
we proved that the contribution of the proton on the overall potential
window together with the incorporation of water at low potentials
solely. This is explained by the fact that water molecules permit
a further insertion of protons in the material by shielding the proton
charge but at the expense of the proton kinetic properties. These
findings shed a new light on the importance of water molecules in
the ion-insertion mechanisms taking place at the electrode–electrolyte
interface of aqueous proton-based batteries. Overall, the present
results further highlight the richness of the EQCM-based methods for
the battery field in offering mechanistic insights that are crucial
for the understanding of interfaces and charge storage in insertion
compounds.