Marangoni-Driven Self-Assembly MXene As Functional Membrane Enables Dendrite-Free and Flexible Zinc-Iodine Pouch Cells

Zn metal is a promising anode material in aqueous batteries, but the direct use of Zn foil encounters severe issues of dendrite formation and side reactions, causing short cycle life. Conventional thick and rigid insulating protection layers may impede Zn ion diffusion and detach during mechanical deformation of the battery. Herein, a dendrite-free zinc anode is demonstrated by grafting a thin (approximate to 10 nm) Ti3C2Tx MXene functional membrane which is formed via Marangoni-driven self-assembly. The thin MXene membrane initiates uniform nucleation and promotes deposition of (002)-oriented Zn in a lateral growth mode. Meanwhile, the membrane functions as a soft, stress-adaptive, and protective layer to the underneath active zinc. This functional membrane renders Zn anode with improved cycling stability without notable dendrite formation or side-reaction products. Flexible ZnI2 pouch cells fabricated from the MXene-covered Zn foil (20 mu m thick) anode and a modified ZnI2 cathode demonstrate stable capacity up to 1500 cycles and unchanged voltage upon various mechanical deformations. This work affords new insights into designing functional soft membranes for constructing flexible Zn-based energy devices. A thin Ti3C2Tx MXene membrane obtained by self-assembly is transferred and tightly adhered to Zn anode surface. This stress-adaptive and electrically conductive membrane enables reversible and stable the Zn deposition with improved Coulombic efficiency. This functional membrane differs from previously reported surface protection or 3D host. The ZnI2 pouch cells can retain stable capacity over 1500 cycles under various mechanical deformations. image