The Misconception of Mg2+ Insertion into Prussian Blue Analog Structures from Aqueous Solutionстатья
Статья опубликована в высокорейтинговом журнале
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Дата последнего поиска статьи во внешних источниках: 9 апреля 2021 г.
Аннотация:Prussian Blue analogs (PBA) are commonly believed to reversibly insert divalent ions, such as calcium and magnesium, rendering them as perspective cathode materials for aqueous magnesium‐ion batteries. In this work, we show that Mg 2+ insertion into nanosized PBA materials is a misconception and provide conclusive evidence for the unfeasibility of this process for both cation‐rich and cation‐poor nickel, iron and copper hexacyanoferrates. Based on structural, electrochemical, IR spectroscopy and quartz crystal microbalance data, we deduce the charge compensation of PBA redox by protons rather than by divalent ions in aqueous Mg 2+ solution. The reversible insertion of protons involves complex lattice water rearrangements, while the presence of Mg 2+ ion and Mg salt anion stabilizes the proton (de)insertion reaction due to local pH effects and anion adsorption at the PBA surface. The obtained results draw attention to the design of proton‐based batteries operating in environmentally benign aqueous solutions with low acidity.