Speaker
Description
Aqueous Zn–MnO₂ batteries involve complex reaction processes during operation, including deposition/dissolution of the MnO₂-based electrode and zinc-containing species, and possible generation of side products. Understanding these material transformations under working conditions is essential for clarifying the reaction mechanism and degradation pathways of this battery system.
In this work, operando synchrotron X-ray diffraction was used to investigate the cathode evolution of aqueous Zn–MnO₂ batteries during electrochemical cycling. The XRD data provides direct structural information on the appearance, disappearance, and evolution of crystalline phases during battery operation. However, their interpretation is challenging due to the highly defective nature of MnO₂, the strongly crystalline zinc-containing by-products, and background contributions from the operando cell. Intense reflections from zinc hydroxysulfate-related species can mask weaker diffraction changes associated with the MnO₂ electrode and other evolving phases.
To assist the analysis, Multivariate Curve Resolution was used as a data-preprocessing tool rather than as a direct phase-identification method. MCR was applied to separate the dominant zinc hydroxysulfate-related diffraction contribution, which was then subtracted from the original patterns according to its evolution profile, followed by intensity renormalization to reduce background distortions. This treatment improves the visibility of weaker and broader diffraction peaks. The highlighted changes indicate relevant composition evolution of the Mn oxide during electrochemical cycling. This effect overlaps with the expected deposition-dissolution mechanism, which would simply show changes in intensity. These experiments expand our understanding of the dynamic material evolution in aqueous Zn–MnO₂ batteries.