Understanding intercalation chemistry for sustainable aqueous zinc-manganese dioxide batteries

Rechargeable aqueous Zn-MnO₂ technology combines one of the oldest battery chemistries with favourable sustainability characteristics, including safety, cost and environmental compatibility.  The ambiguous charge storage mechanism, however, presents a challenge to fulfil the great potential of this energy technology.

Here* we leverage on advanced electron microscopy, electrochemical analysis and theoretical calculations to look into the intercalation chemistry within the cathode material.  We show that Zn²⁺ insertion into the cathode is unlikely in the aqueous system; rather, the charge storage process is dominated by proton intercalation.  We further reveal anisotropic lattice change as a result of entering protons proceedings from the surface into the bulk, which accounts for the structural failure and capacity decay of the electrode upon cycling.  This work not only advances the fundamental understanding of rechargeable zinc batteries but also suggests the possibility to optimize proton intercalation kinetics for better-performing cell designs.

*'Understanding intercalation chemistry for sustainable aqueous zinc-manganese dioxide batteries'.