Ultra-Stable Zn Anode Enabled by Fiber-Directed Ion Migration Using Mass-Producible Separator

Aqueous zinc-ion battery (AZB) is a promising candidate for next-generation energy storage owing to inherent safety and low cost. However, AZBs are currently plagued by Zn dendrite growth and undesirable side-reactions, leading to poor cycling stability and premature failure. To restrain the uncontrollable Zn growth, a unique separator is developed based on polyacrylonitrile/graphene oxide (abbreviated as PG) composite nanofibers, which contain abundance of zincophilicity functional groups to regulate the migration and distribution of Zn2+ ions in the separator. It is demonstrated that the cyano ligands on PG not only facilitate the dehydration of solvated Zn2+ ions prior to deposition, but also form fast lanes to enable homogenous scattering of deposition spots. Benefiting from these features, the PG separator offers a high ionic conductivity of 7.69 mS cm(-1) and a transference number of 0.74 for Zn2+. The Zn||Zn symmetrical cells with PG separators achieve an ultra-stable cycle life over 13 000 h. Zn||Zn0.27V2O5 full batteries with PG separators retain 71.5% of the original capacity after 2800 cycles at a high current density of 2 A g(-1). This work offers future research directions toward the design of multifunctional separators to overcome the limits of Zn metal anode in AZBs.

Automated summary

Aqueous zinc-ion battery (AZB) is a promising candidate for next-generation energy storage due to its inherent safety and low cost. However, current AZBs face challenges such as Zn dendrite growth and undesirable side-reactions, resulting in poor cycling stability. To address this issue, researchers have developed a unique separator based on polyacrylonitrile/graphene oxide (PG) composite nanofibers, which effectively regulate the migration and distribution of Zn2+ ions in the separator. The PG separator demonstrates high ionic conductivity and stable performance, providing a potential solution to overcome the limitations of Zn metal anode in AZBs.