Regulation of Zn2+ desolvation kinetics via interfacial hydrogen-bond network for a highly reversible Zn metal anode

Abstract

The uniform plating on zinc metal anode (ZMA) is imperative for stable aqueous zinc-ion batteries (AZIBs). However, the sluggish desolvation of hydrated Zn²⁺ is identified as the primary source of kinetic barriers in plating process, leading to dendrite growth and parasitic reaction. Herein, we introduce chitosan oligosaccharide (COS) as an interfacial hydrogen bond network constructor on ZMA surface to enhance the desolvation kinetics of hydrated Zn²⁺. Specifically, COS molecules preferentially adsorb on the ZMA surface, where desolvated H₂O from plating process can be immobilized by the multiple hydroxyl groups of COS. In addition, COS molecules capture hydrated Zn²⁺ through their amino groups, resulting in superior Zn²⁺ transport capability. Consequently, the introduction of COS into Zn(OTF)₂ electrolyte enables a lower nucleation overpotential (358 mV) and activation energy (32.34 kJ mol^-1) for plating. Such advantages further enable Zn||Zn symmetric battery to achieve a cycle life exceeding 1800 h, Zn||Cu battery to realize a high Coulombic efficiency of 99.68 %, and Zn||Zn_xV₂O₅ full battery to reach a considerable capacity retention of 83.56 % over 1000 cycles. The application of interfacial hydrogen bond network provides a novel perspective for optimizing the desolvation of Zn²⁺ plating on ZMAs.