Defect-rich carbonaceous interface enabling ultrathin separators to stabilize zinc anodes for aqueous zinc-ion...

Aqueous zinc-ion batteries (ZIBs) have attracted extensive research as a promising energy storage system, whereas their practical applications are plagued by zinc dendrite and parasitic reaction issues-caused poor stability of zinc anodes. The currently used glass fiber separators are incapable of stabilizing zinc anodes and also impair the energy density of ZIBs due to their large thickness (e.g., 260-780 μm). Herein, we report defect-rich carbonaceous interface-synergized cellulose nanofiber (CNF) membranes as functional ultrathin separators for ZIBs, which effectively inhibit zinc dendrite growth and parasitic reactions to realize stable zinc anodes. A carbonaceous material with rich N, O and Zn heteroatom defects is synthesized by carbonizing ZIF-8 precursor and then served as the modification interface of CNF membranes to fabricate 28 μm-thick bilayer-structured separators. For the designed functional ultrathin separators, the nanoporous CNF membrane substrate homogenizes Zn²⁺ flux, and more importantly, the defect-rich carbonaceous interface not only provides abundant zincophilic sites to promote Zn²⁺ desolvation and uniform zinc deposition but also suppresses parasitic reactions on zinc anodes. As a result, zinc anodes coupled with the designed separators present superior electrochemical stability such as a 2600 h operation lifetime, ∼50 times longer than that of zinc anodes coupled with glass fiber separators. The availability of the proposed functional ultrathin separators is further verified in Zn//NaV₃O₈‧1.5 H₂O ZIBs. This work provides new inspiration for designing advanced separators for high-performance ZIBs.