Tunneling Proton Grotthuss Transfer Channels by Hydrophilic-Zincophobic Heterointerface Shielding for High-Performance Zn-MnO 2 Batteries.

Hollandite-type manganese dioxide (α-MnO 2 ) is recognized as a promising cathode material upon high-performance aqueous zinc-ion batteries (ZIBs) owing to the high theoretical capacities, high working potentials, unique Zn 2+ /H + co-insertion chemistry, and environmental friendliness. However, its practical applications limited by Zn 2+ accommodation, where the strong coulombic interaction and sluggish kinetics cause significant lattice deformation, fast capacity degradation, insufficient rate capability, and undesired interface degradation. It remains challenging to accurately modulate H + intercalation while suppressing Zn 2+ insertion for better lattice stability and electrochemical kinetics. Herein, proton Grotthuss transfer channels are first tunneled by shielding MnO 2 with hydrophilic-zincophobic heterointerface, fulfilling the H + -dominating diffusion with the state-of-the-art ZIBs performance. Local atomic structure and theoretical simulation confirm that surface-engineered α-MnO 2 affords to the synergy of Mn electron t 2g -e g activation, oxygen vacancy enrichment, selective H + Grotthuss transfer, and accelerated desolvation kinetics. Consequently, fortified α-MnO 2 achieves prominent low current density cycle stability (≈100% capacity retention at 1 C after 400 cycles), remarkable long-lifespan cycling performance (98% capacity retention at 20 C after 12 000 cycles), and ultrafast rate performance (up to 30 C). The study exemplifies a new approach of heterointerface engineering for regulation of H + -dominating Grotthuss transfer and lattice stabilization in α-MnO 2 toward reliable ZIBs.