Unveiling the Intricate Intercalation Mechanism in Manganese Sesquioxide as Positive Electrode in Aqueous Zn‐Metal Battery
Yuan Ma, Yanjiao Ma, Thomas Diemant, Kecheng Cao, Xu Liu, Ute Kaiser, R. Jürgen Behm, Alberto Varzi, Stefano Passerini
Abstract
Abstract In the family of Zn/manganese oxide batteries with mild aqueous electrolytes, cubic α‐Mn 2 O 3 with bixbyite structure is rarely considered, because of the lack of the tunnel and/or layered structure that are usually believed to be indispensable for the incorporation of Zn ions. In this work, the charge storage mechanism of α‐Mn 2 O 3 is systematically and comprehensively investigated. It is demonstrated that the electrochemically induced irreversible phase transition from α‐Mn 2 O 3 to layered‐typed L‐Zn x MnO 2 , coupled with the dissolution of Mn 2+ and OH − into the electrolyte, allows for the subsequent reversible de‐/intercalation of Zn 2+ . Moreover, it is proven that α‐Mn 2 O 3 is not a host for H + . Instead, the MnO 2 formed from L‐Zn x MnO 2 and the Mn 2+ in the electrolyte upon the initial charge is the host for H + . Based on this electrode mechanism, combined with fabricating hierarchically structured mesoporous α‐Mn 2 O 3 microrod array material, an unprecedented rate capability with 103 mAh g −1 at 5.0 A g −1 as well as an appealing stability of 2000 cycles (at 2.0 A g −1 ) with a capacity decay of only ≈0.009% per‐cycle are obtained.