Zincophilic polyurethane-based porous film enables dendrite-free zinc anode for reversible aqueous zinc-based batteries

Rechargeable aqueous zinc ion battery represents a promising technology for large-scale energy-storage because of its excellent theoretical capacity and intrinsic safety. However, Zn anodes suffer from uncontrollable dendrite growth, which limits the cycling stability and results in low Zn utilization. Herein, a hierarchically porous film of polyurethane (PU) and zinc trifluoromethanesulfonate (Zn(OTf)2) is fabricated as protective layer of Zn anode and effectively restrains Zn dendrite growth. Owing to the hierarchical pores and abundant polar bonds, the PU/ Zn(OTf)2 (PUZ) layer not only exhibits high zinc ion transport number but also guides Zn2+ uniform deposition. Importantly, the recycled PUZ film still shows good performance due to its stability. Consequently, the dendrite-free Zn anode is achieved, and excellent cycling stability toward the zinc-based battery is obtained. A sym-metrical cell with PUZ protected Zn anode displays a long cycle lifespan (>1800 h) at the current density of 0.5 mA cm-2 during Zn stripping/plating, compared with that of the bare Zn symmetrical cell (80 h). Furthermore, the protected zinc anode coupled with a Mn-doped V2O5 (MnVO) cathode constitutes a stable and rechargeable full battery with a good capacity retention of 70.3% after 3400 cycles at 1 A g � 1. This work provides a feasible strategy to solve the zinc dendrite problem, and presents a great promise for application of aqueous zinc ion batteries.