Stabilizing interfacial pH value towards stable zinc anode for aqueous zinc metal batteries

The stability of Zn anode is significantly affected by the fluctuation of interfacial pH value, but there is still limited attention paid to this issue. In this work, we regulating the interfacial pH value to enhance the stability of Zn anode via a novel environmentally-friendly additive D-galactose (D-Gal). D-Gal with great negative electrostatic potential and a low lowest unoccupied molecular orbital (LUMO) level energy was chemisorbed on Zn anode to not only isolate H₂O contact with Zn anode. The in-situ pH test confirmed that D-Gal guaranteed a stable pH environment. Furthermore, the D-Gal additive contributes to uniform deposition for stable Zn anode. Therefore, the Zn||Zn symmetric cell exhibits a cycle life of 2600 h at 1.0 mA·cm⁻² and 1.0 mAh·cm⁻². Even at high current density of 10 mA·cm⁻², it can stabilize 900 h. When paired with a vanadium-based cathode, the full battery demonstrated a stable capacity retention of 62.78% at 1.0 A·g⁻¹ following 2000 cycles. This work provides a new insight into interfacial stability for aqueous zinc metal batteries.