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.