Glycine-Driven Dynamic Interfacial pH Buffering Enables Highly Reversible Zinc Metal Anodes

Aqueous zinc-ion batteries are severely hindered by interfacial side reactions including dendrite growth and by-product accumulation, primarily caused by local pH fluctuations at the Zn/electrolyte interface. Here, we propose a dynamic interfacial pH-buffering strategy using glycine (Gly), which simultaneously anchors onto the Zn surface and regulates proton transfer through its reversible acid-base equilibria. In situ pH mapping with an ultramicroelectrode probe directly confirms that Gly effectively suppresses interfacial alkalization and maintains a stable interfacial environment during Zn plating/stripping. Benefiting from this local buffering effect, the Gly-containing electrolyte achieves a Coulombic efficiency (CE) of 99.5% in Zn||Cu cells, stable cycling over 1000 h in symmetric cells, and durable cycling for 2000 cycles in Zn||NaV₃O₈ full cells. This work establishes interfacial pH stabilization as an important design criterion for electrolyte-additive engineering in aqueous Zn batteries.