A Janus Separator Regulating Zinc Deposition Behavior Synergistically by Cellulose and ZrO₂ Nanoparticles Toward High‐Performance Aqueous Zinc‐Ion Batteries

Aqueous zinc-ion batteries (AZIBs) stand out among many energy storage systems due to their many merits, and it's expected to become an alternative to the prevailing alkali metal ion batteries. Nevertheless, the cumbersome manufacturing process and the high cost of conventional separators make them unfavorable for large-scale applications. Herein, inspired by the unique nature of cellulose and ZrO₂, a Janus cellulose fiber (CF)/polyvinyl alcohol (PVA)/ZrO₂ separator is prepared via the vacuum filtration method. The interwoven cellulose fibers offer robust mechanical strength, which prevents dendrites from penetrating through the separator, while ZrO₂ nanoparticles with Maxwell-Wagner effect regulate electric field and effectively promote uniform nucleation. Density functional theory (DFT) reveal CF/PVA/ZrO₂ separator's ability to manipulate Zn²⁺ deposition orientation to Zn (002), resulting in a dendrite-free, compact, and flat anode. Consequently, the obtained Zn||Zn symmetric cell exhibits superior electrochemical performance, able to operate at 1 mA cm^-2 for more than 1500 h and 6 mA cm^-2 for 400 h. In addition, CF/PVA/ZrO₂ separator outperforms the commercially available glass fiber (GF) separator and CF separator when assembled into full cells using either polyaniline (PANI)@carbon nanotube (CNT) or MnO₂@CNT as cathode material. This work serves as a reference for the subsequent research in high performance AZIBs.