Formation of MnxZny(OH)zSO4⋅5H2O – not intercalation of Zn – is the basis of the neutral MnO2/Zn battery first discharge reaction

Abstract At present there is no consensus on the charge-storage mechanism of the positive electrode in the chemistry of the MnO2/ZnSO4/Zn battery. We report the discovery of a novel, electrochemically active Mn-Zn layered double hydroxide (MnZnLDH), which, is analogous in structure to ZnLDH, and because of this similarity cannot be identified as a discharge product even by the operando XRD techniques used. We were able to synthesize MnZnLDH, for the first time, and, herein, demonstrate that its electrochemical behavior, structure, and Gibbs free energy of formation correspond to the products formed during the first discharge, providing clear evidence that this phase forms during the first discharge reaction through a conversion reaction of MnO2 and Zn2+.