A facile tip shielding strategy for highly reversible Zn anode

Abstract

Long-term reversibility and stability of aqueous Zn-ion batteries (AZIBs) at high current density are significantly impeded by uncontrolled Zn dendrites and side reactions on Zn anodes. Herein, a facile tip-shielding strategy was proposed via surface reduction approach aimed at liberating pure Zn sites for interfacial grafting of 5-amino-2-fluoro-pyridine (AFPD) molecular solid-electrolyte interface (SEI), realizing the direct utilization of the selective adsorption procedure in electrolyte optimization to substitute of the non-discriminatory modification process in interfacial engineering. This approach could effectively suppress Zn dendrite growth, hydrogen evolution reaction, and corrosion/passivation. Characterization and simulation results demonstrated that the parallel absorption mode of 5-amino-2-fluoro-pyridine (AFPD), preferential absorption of AFPD on non-Zn(002) facets, and homogeneous electric field distribution synergistically promote the deposition of planar and low-angle Zn lamellas. Consequently, the symmetrical battery assembled by the optimized AFPD-2–4@Zn electrodes achieved a significantly enhanced cycling performance (over 3400 h) in contrast to the bare Zn||bare Zn battery (approximately 370 h) at 5 mA cm−2 and 1 mAh cm−2. AFPD-2–4@Zn||MnO2 full cell also manifested elevated capacity retention of approximately 70.2 % at 1 A/g after 700 cycles. This strategy introduces a facile tip-shielding strategy to construct robust Zn anodes for achieving the practical implementation of AZIBs, especially at high current densities.