Molecular Engineering of Multi-polar Groups Enables Longterm Stable Zn Anodes at High Current Density

Abstract

The cycling stability of aqueous zinc-ion batteries (AZIBs) is critically impeded by uncontrolled dendrite growth and severe concentration polarization at the Zn anode, especially at high current densities. Herein, a molecular engineering approach utilizing D-pantothenic acid (D-PA) with multi-polar functional groups as an electrolyte additive has been employed to realize long-lifespan and stable Zn anodes. Results demonstrate that the amide and carboxyl groups in D-PA, rich in lone-pair electrons, facilitate strong interactions with the Zn anode surface, promoting preferential adsorption. Meanwhile, the highly electronegative carboxyl groups coordinate with Zn 2+ to reshape the solvation structure. Additionally, the hydrophilic hydroxyl groups effectively trap free water molecules and reconstruct the hydrogen bond network. Benefiting from the synergistic effects of these functional groups on the electrode interface and coordination environment, the dendrite growth and concentration polarization on Zn anode at high current density were inhibited, thereby achieving protection for the Zn anode. As a result, the Zn||Zn symmetric cells exhibit an ultra-long cycling lifespan of 1200 h at a high current density of 10 mA/10 mAh cm -2 (13 times vs. ZnSO 4 ). Furthermore, the reversibility of Zn||Cu cells is significantly enhanced, achieving an average Coulombic efficiency of nearly 100% over 1000 cycles. This work reveals the regulatory mechanism of molecules with multipolar groups in stabilizing the Zn anode, offering a promising strategy for developing practical fast-charging Zn batteries.