*3.1. Binder Variation*

Mechanical stress tests of the positive electrode coatings revealed the maintenance of the structural integrity of the coatings based on aqueous binders in the electrolyte solution but not in DI-water, in comparison to the non-aqueous binders showing a stability in both DI-water and electrolyte. This could refer to the lower solvation free energy of the water molecules in the electrolyte in consequence of the ZnSO4 and MnSO4 addition, stabilizing the aqueous binders.

Rate capability tests (RCT) showed a lower capacity/energy of the positive electrodes for the binder polymers with non-aqueous solvents compared to those with aqueous solvents, with the best results achieved for the aqueous binder PAN. This could be explained by the availability of the MnO2 active material loading of the coating: The aqueous binders allow a swelling of the coating by the electrolyte in contrast to the non-aqueous binders. The coating swelling makes the active material loading available for MnO2 deposition/dissolution mechanisms in relation to the suggested reaction mechanism of the ARZIB, resulting in higher capacity/energy values. Still, the non-aqueous binders show an increasing capacity/energy with the proceeding cycle number. This could be explained by a MnO2 deposition/dissolution mechanism on the electrode surface being confirmed by SEM+EDX characterizations of electrode cross sections. EIS measurements show that the characteristics of the spectra of the non-aqueous binder (here: PAN (DMSO)) in the charged state also changes by increasing the cycle number, which might indicate a growing MnO2 deposition layer for proceeding cycling.
