Scalable, flexible and hierarchically porous Janus membrane inducing Zn-Ion flux redistribution and desolvation for dendrite-free zinc anodes

Optimizing Zn2+ dispersion and regulating Zn2+ deposition is a key issue in the aqueous Zn-ion anodes. Herein, the flexible membrane (CNT/PAN/Ag) with uniformly interwoven pores was facilely fabricated by one-step phase inversion method. The complex woven pore structure can effectively disperse the flow of Zn2+, reduce current density of nucleation sites, and avoid the aggregated deposition of Zn2+. Furthermore, the scalable Janus membrane with different affinities to electrolyte on the two sides can be designed based on the membrane surface structure. The high wettability of the upper surface of the membrane with electrolyte facilitates rapid transfer of Zn2+ flux into the membrane for redispersion, and low wettability of the back surface is benefit to isolate electrolyte from surface of the zinc anode and to avoid side reactions brought about by the aqueous electrolyte. Meanwhile, by virtue of the high adsorption energy with Zn2+, the doped Ag active sites in the membrane further extend the dispersion path of Zn2+ within the membrane and induce portion of Zn2+ to be deposited within the membrane, balancing and reducing current density at the deposition interface. In the galvanostatic current test of the symmetric battery at 1 mA cm- 2, 0.5 mAh cm- 2, the battery can be stably cycled more than 1000 h, the specific capacity of pouch cell with NH4V4O10 reserved 384 mA h/g at 5 Ag- 1 after 95 cycles. The work presents a new flexible membrane design for solving the Zn dendrites in aqueous zinc ion batteries.