A Biomimetic Polymer-Based Composite Coating Inhibits Zinc Dendrite Growth for High-Performance Zinc-Ion Batteries

Because of their low cost, safety, and green nature, aqueous Zn-ion batteries are promising candidates for energy storage. However, the appearance of Zn dendrites, hydrogen evolution reaction (HER), and corrosion limit the development of the aqueous Zn-ion batteries. Here, inspired by fibrous cartilage, a biomimetic poly(vinylidene fluoride) (PVDF)-based composite polymer coating layer, including aramid nanofiber (ANF) and zinc trifluoromethanesulfonate [Zn(CF₃SO₃)₂], called ANFZ, was designed and fabricated. The high ionic conductivity (3.84 mS cm^-1) of the flexible PVDF matrix, optimized by Zn(CF₃SO₃)₂, combined with the highly mechanical ANF network can effectively guide the rate of Zn stripping/plating, homogenize the Zn²⁺ distribution, and suppress the dendrites. In addition, the high Coulombic efficiency is obtained due to the suppression of HER and corrosion by the biomimetic coating layer. Symmetric ANFZ@Zn//ANFZ@Zn can steadily work over 1000 h at 1 mA cm^-2 with a high degree of reversibility, which is greater than that of bare Zn//bare Zn. Furthermore, the ANFZ@Zn//MVO batteries show a high specific capacity (400.2 mAh g^-1, 0.1 A g^-1) and a long cycle life. This work presents a novel method combined with bionics for designing and assembling Zn anodes without dendrites for zinc-ion batteries.