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

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 H2O), avoiding O-H bond splitting. Hence, Zn-V6O13 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.