Highly durable aqueous Zn ion batteries based on a Zn anode coated by three-dimensional cross-linked and branch-liked bismuth-PVDF layer

Rechargeable aqueous Zn ion batteries have been regarded as one of the most promising candidates for next-generation energy storage devices due to their low cost, non-toxicity and high safety. However, the dendrite growth of Zn anode and severe undesired side-reactions largely limited their practical application. Here, we developed a bismuth (Bi)-PVDF layer with unique 3D cross-linked and branch-liked structures as a protective layer on the Zn surface (Zn@Bi-PVDF) to suppress the formation of Zn dendrites and side-reactions, leading to the uniform plating and stripping of Zn during the cycles. Consequently, the symmetric cell with Zn@Bi-PVDF electrodes exhibits long cycling life over 2400 h at a current density of 1 mA cm−2 with a fixed capacity of 1 mAh cm−2. When the Zn@Bi-PVDF anode is paired with a NaV3O8·1.5H2O (NVO) cathode, the fabricated Zn@Bi-PVDF//NVO cell maintains a high reversible capacity of 175.5 mAh g−1 at 1 A g−1 after 500 cycles with an initial capacity retention of 64.1%.