Graphite-Modified PAN Separator with Electron Buffer Layer for Regulating Zn2+ Deposition in Aqueous Zinc-Ion Batteries.

The passivation of zinc metal anodes and the formation of dendrites stand as critical challenges in the development of aqueous zinc-ion batteries (ZIBs), restricting their practical applications. In this work, polyacrylonitrile (PAN) and graphite nanoparticles are combined as a precursor to design a modified PAN nanofiber separator (GPAN) by electrospinning. Graphite nanoparticles act as an electron buffer layer, accelerating the interfacial charge transfer, dispersing the excess charge from the electrode surface to the graphite particles, reducing the polarization caused by charge accumulation, and suppressing the tip effect through electron consumption. As a result, the GPAN separator exhibits a high Zn²⁺ transference number of 0.92 and an ionic conductivity of 11.7 mS cm^-1. The Zn||Zn symmetric cells demonstrate long-term stability (up to 400 h) at a high current density of 10 mA cm^-2. Meanwhile, the Zn||Na₂V₆O₁₆·1.5H₂O (NVO) full cells with GPAN separators deliver a high specific capacity of 283 mAh g^-1 and excellent long-term durability with 74% capacity retention after 1000 cycles at 1 A g^-1. This work provides a simple and effective approach for developing high-performance ZIBs by designing PAN-based separators with high ion transference numbers and functional properties to regulate Zn²⁺ deposition.