Amorphous Ti-Si functionalized cellulose separators for stable zinc-ion batteries: constructing three-dimensional isotropic networks to regulate ion flux

Abstract

Background Aqueous zinc-ion batteries (AZIBs) are expected for large-scale energy storage applications, but they are severely constrained by the uncontrollable growth of zinc dendrites and parasitic side reactions. Functionalized separators are widely expected to counteract these detrimental dendrite issues. Methods Here, an amorphous titanium-silicate composite oxide was coated onto cellulose filter paper to construct a Ti-Si separator (TS). The chemically cross-linked Si-O-Ti network provides isotropic Zn 2+ pathways, while oxygen vacancies and cycling-induced Si-O-Zn bonds dynamically regulate Zn 2+ migration, desolvation and deposition. Significant Findings The TS separator enables stable Zn||Zn cycling for 1400 h at 2 mA cm -2 and a Zn||Cu Coulombic efficiency of 99.8% over 3000 cycles. A Zn||NVO full cell also operates for >5000 cycles, demonstrating an effective amorphous-oxide separator strategy for dendrite-free AZIBs.