Modulating Ion Behavior by Functional Nanodiamond Modified Separator for High-Rate Durable Aqueous Zinc-Ion Battery

Aqueous zinc-ion batteries (AZIBs) have garnered widespread attention due to their promising development and application prospects. However, progress of AZIBs has been hindered by zinc (Zn) dendrites and side reactions at the electrode-electrolyte interface (EEI). In particular, the large and uneven pores of commercial glass fiber (GF) separators lead to nonuniform Zn²⁺ transport, which causes side reactions. In this study, we employed nanodiamonds (NDs) to regulate the separator pore structure and utilized its surface oxygen-containing functional groups to control the Zn²⁺ transport properties. Due to their excellent chemical inertness, superhardness, ultrahigh thermal conductivity, and abundant surface functional groups, NDs modified GF separators for dendrite-free and high-performance AZIBs. Experimental outcomes demonstrate that Zn||Zn symmetric cells using NDs-GF separators exhibit regular charge-discharge profiles, minimal fluctuations, and an ultralong cycling lifespan of nearly 1800 h under a current density of 5 mA cm^-2 with a capacity density of 1 mAh cm^-2 and 240 h under a high current density of 10 mA cm^-2 with a capacity density of 10 mAh cm^-2. The Zn||MnO₂ full cells using NDs-GF separators showcase a high retention after 1000 cycles at 1 A g^-1. This research proposes a modification method for developing advanced separators in AZIBs technology.