Stabilizing Interface pH by N-Modified Graphdiyne for Dendrite-Free and High-Rate Aqueous Zn-Ion Batteries

Abstract

Zn dendrite issue was intensively studied via tuning zinc ion flux. pH change seriously influences dendrite formation, while its importance has not been revealed. Here, we construct a N-modification graphdiyne interface (NGI) to stabilize pH by mediating hydrated zinc ion desolvation. Operando pH detection reveals pH stabilization by NGI. This works with pores in NGI to achieve dendrite-free Zn deposition and an increased symmetric cell lifespan by 116 times. Experimental and theoretical results owe pH stabilization to desolvation with a reduced activation energy achieved by electron transfer from solvation sheath to N atom. The efficient desolvation ensures that electron directly transfers from substrate to Zn²⁺ (rather than the coordinated H<inf>2</inf>O), avoiding O−H bond splitting. Hence, Zn-V<inf>6</inf>O<inf>13</inf> battery achieves a long lifespan at 20.65 mA cm⁻² and 1.07 mAh cm⁻². This work reveals the significance of interface pH and provides a new approach to address Zn dendrite issue.