Diminishing Space-Charge Layer Effect of Zinc Anodes by an Anion-Immobilized Electrolyte Membrane
Yang Yang, Haiming Hua, Zeheng Lv, Weiwei Meng, Minghao Zhang, Hang Li, Pengxiang Lin, Jin Yang, Guanhong Chen, Yuanhong Kang, Zhipeng Wen, Jinbao Zhao, Cheng Chao Li
Abstract
The Zn dendrite issue, which is closely related to the creation of the space-charge region upon local anion depletion during cycling, has plagued the practical applications of aqueous Zn metal batteries (ZMBs). Herein, we propose a Kevlar-derived hydrogel (KevlarH) electrolyte with immobilized anions to diminish the space-charge layer effect. SO 4 2– anions are strongly tethered to amide groups of polymer chains, which mitigates the concentration polarization of interfacial Zn 2+ ions by preventing the anion depletion. Furthermore, the relatively weak interaction between Zn 2+ cations and carbonyl groups can redistribute Zn 2+ -ion flux without sacrificing the ion diffusion rate. The synergistic “zincophilic” and “anionphilic” building blocks enable dendrite-free Zn deposition behavior and suppressed side reactions, thereby extending the lifespan of a Zn metal anode up to 3500 h with an ultrahigh Coulombic efficiency of 99.87%. Importantly, the KevlarH electrolyte can be directly used to assemble high-voltage bipolar ZMBs and break the 2 V barrier in aqueous ZMBs.