Angstrom confined ion transport in graphene oxide membranes enables highly reversible zinc anodes

Aqueous zinc anodes have been plagued by dendrite growth and interfacial side reactions. Here, we construct an angstrom scale two-dimensional (2D) ionic sieve to resolve the trade-off between high ion flux and fast desolvation kinetics. The interlayer spacing of a potassium intercalated highly expanded graphene oxide (K⁺-heGO) membrane is precisely engineered to 1.03 nm. By subtracting the graphene skeleton thickness of 0.34 nm, yields an effective ion transport channel of 0.69 nm, approaching the critical size (~0.86 nm) for desolvating [Zn(H₂O)_n]²⁺. This upper limit proximity design can maximizes both ion flux and desolvation kinetics. To overcome the inherent ion flux attenuation in sub-nanochannels, an ultrathin sodium alginate (SA) suction layer was integrated beneath the K⁺-heGO layer. This zincophilic polymer layer functions as a chemical osmotic pump, which actively pulls Zn²⁺ through the 2D channels via strong adsorption. This synergistic design enables high Zn²⁺ transference number of 0.88. Consequently, Zn//Zn symmetric cells achieve an extended cycling lifespan over 4000 h at 1 mA cm⁻², and maintain stability for 2000 h even at 20 mA cm⁻². This work demonstrates that angstrom scale 2D confinement, synergized with a polymer assisted kinetic pump, provides an effective strategy for stabilizing zinc metal anodes.