A Softwood Kraft Lignin/Polyvinylidene Fluoride Composite Coating for Dendrite-Free Zinc Anodes in High-Performance Aqueous Zinc-Ion Batteries

Increasing the stability of electrolyte–zinc anode interfaces by constructing functional coatings is a practical approach to improving the overall performance of zinc-ion batteries. Herein, softwood kraft lignin (SKL) is mixed with poly(vinylidene fluoride) (PVDF) to fabricate a novel hydrophobic coating (SKL-doped PVDF) for zinc anodes. The SKL-doped PVDF not only effectively prevents water molecules from directly contacting the zinc electrode but also features a wide pore-channel structure. Therefore, the hydrogen evolution reaction (HER) and corrosion are greatly inhibited, while uniform Zn2+ deposition is promoted. Moreover, the results for Zn//Zn symmetric and Zn//Cu asymmetric cells with modified zinc (SKL-doped PVDF@Zn) demonstrate enhanced stability and reversibility in terms of zinc-ion plating/stripping. In addition to an exceptional rate performance, the full batteries with SKL-doped PVDF@Zn exhibit an excellent cycling performance, retaining a capacity of 271.6 mAh g–1 after 100 cycles at a current density of 0.5 A g–1 and 93.9 mAh g–1 after 1000 cycles at a current density of 1.5 A g–1. Moreover, the surface of the post-run SKL-doped PVDF@Zn exhibits no dendrites and yields almost no byproducts. This study highlights the feasibility of using green and renewable lignin resources to fabricate a protective layer for the zinc anode.