High-performance aqueous zinc-ion batteries with highly oriented MFI zeolite nanosheet separators

Aqueous zinc-ion batteries (AZIBs) offer intrinsic safety and cost advantages for grid-scale energy storage, yet their practical deployment is severely hindered by parasitic hydrogen evolution and uncontrollable dendrite growth. Zeolite-based separators have emerged as a promising solution; however, conventional designs rely on randomly oriented zeolites and polymer binders, which compromise ion transport efficiency and mechanical robustness. Here, we demonstrate that binder-free separators fabricated from highly [010]-oriented MFI zeolite nanosheets (MFI-NS) can overcome these limitations. The binder-free strategy endows the MFI-NS separator with a tensile strength two orders of magnitude higher than that of commercial glass-fiber (GF) separators, providing exceptional mechanical robustness against dendrite penetration. The self-assembled lamellar stack of MFI-NS ensures straight channels well-aligned perpendicular to the electrode surface, delivering a Zn2+ transference number 266% higher and an ionic conductivity 62% higher than those of separators comprising randomly oriented MFI particles, thereby enabling rapid and efficient Zn2+ transport. Concurrently, the uniform micropores in MFI-NS effectively suppress hydrogen evolution and retard dendrite formation. These synergistic benefits markedly enhance the electrochemical performance of AZIBs. The V2O5||MFI-NS||Zn full cell delivers a high specific capacity of 420 mAh g-1 at 1 A g-1 and retains 71% of its initial capacity after 1,200 cycles, which substantially outperforms the cells with separators comprising conventional GF or randomly oriented MFI particles. This work establishes crystallographic orientation engineering in zeolite separators as a powerful strategy for addressing multiple degradation mechanisms in AZIBs.