Angstrom-Scale Confined Ion Sieve and Accelerator for Efficient Aqueous Zinc Batteries.

The commercialization of aqueous zinc-metal batteries (AZMBs) is hindered by dendrite growth caused by uncontrolled Zn2+ transport and side reactions involving water and anions. Here, an angstrom-scale confined ion sieve and accelerator is designed using unilamellar Ti0.87O2 nanosheets with atomic Ti vacancies (∼3.0 × 3.8 Å) and interlayer spacing (∼3.5 Å) to enable selective Zn2+ (∼1.5 Å) transport while blocking H2O (∼4.0 Å) and SO4 2- (∼5.9 Å). This design facilitates selective Zn2+ ion transport with high flux and Zn/SO4 2- selectivity, effectively mitigating water-/anion-induced parasitic reactions at the Zn anode. Consequently, the Ti0.87O2@Zn anode exhibits significantly suppressed dendrite growth and parasitic side reactions during repeated Zn plating/stripping, with stable cycle lives exceeding 5000 and 4000 h at 1 and 5 mA cm-2, respectively. The Ah-level Ti0.87O2@Zn//VO2 pouch cell retains 85.4% of its initial capacity after 300 cycles at 3 A g-1. This strategy provides a promising interfacial design concept for improving the reversibility of aqueous Zn metal anodes and may inspire the rational design of confined ion-transport interphases for related aqueous battery systems.