Bi-Functional Agarose-Filled Porous Polysulfone Protective Layer for Dendrite-Free Zn Anode

The uneven electric field and slow Zn²⁺ desolvation lead to rapid dendrite growth during Zn plating and stripping, which severely deteriorates the performance of Zn metal anodes (ZMAs) in Zn-ion batteries (ZIBs). Although polymer-based artificial protective (PBAP) layers are widely applied to homogenize the electric field of ZMAs, they often fail to promote the desolvation process that eventually induces Zn dendrite growth. Herein, a bi-functional protective layer, comprising a finger-like porous matrix of polysulfone (PSF) and a hydroxyl-rich filler of agarose (AG), is constructed to suppress Zn dendrite growth. COMSOL simulation demonstrates the ZMAs with bi-functional protective layers (Zn@PSF/AG) exhibit uniform electric field and Zn²⁺ distribution. Besides, the Zn@PSF/AG has both low desolvation energy and nucleation overpotential, effectively promoting the desolvation of Zn²⁺. Therefore, the Zn@PSF/AG symmetric cell exhibits excellent cycling performance, achieving 4200 h at 1 mA cm⁻²/1 mAh cm⁻² and 1000 h at 5 mA cm⁻²/5 mAh cm⁻². When coupling with Zn_xV₂O₅ (ZnVO) cathode, the ZnVO‖Zn@PSF/AG full cell shows similarly high cycling stability, maintaining 72% of its capacity after 7000 cycles at 10 A g⁻¹. This research highlights the positive roles of PBAP layer with multi-functional matrix-filler structure in developing long-life ZIBs.