A dendrite-free zinc anode for rechargeable aqueous batteries

Abstract

Zinc is a promising anode material for rechargeable aqueous batteries owing to its high specific capacity, low cost, and environmental friendliness. However, the uncontrollable Zn dendrite growth remains a grand challenge that hinders the practical application of this type of electrode. Here, we create a functional porous polybenzimidazole (PBI) nanofiber layer onto a Cu surface as the substrate of the Zn anode to mitigate dendrite formation. The PBI nanofibers with abundant N-containing functional groups not only allow uniform Zn nucleation on the Cu surface but also facilitate uniform transport of Zn²⁺ ions via electrokinetic conduction, leading to a dendrite-free Zn deposition and thus, a highly reversible Zn plating/stripping process. As a result, a symmetric cell equipped with this newly developed Zn electrode is stably cycled for over 1000 cycles without short-circuits at a current density of 10 mA cm⁻². More impressively, when paired with a MnO₂ cathode, the full cell delivers a nearly 100% capacity retention after 1000 cycles at 1 A g⁻¹ with a specific capacity of about 150 mA h g⁻¹. These results demonstrate that the functional porous PBI nanofiber layer created in this work stands to both dramatically extend battery cycle life and boost battery performance.