Overpotential engineering enables dendrite-free zinc anode for high-performance zinc-ion batteries

Large-scale energy storage applications can greatly benefit from the low-cost and safe zinc metal anode. However, corrosion, side reactions and dendrite growth in water significantly inhibit the cycle life of zinc-ion batteries. Here, 2-ethyl-1H-benzimidazole (EHB), a strong zincophilic and hydrophobic structure, is introduced into the ZnSO₄ (ZS) electrolyte to adjust the nucleation overpotential in Zinc-ion batteries for the initial time. The strong zincophilic side of EHB firmly adheres to the zinc anode, while the hydrophobic end further protects the zinc anode from the influence of active water molecules due to steric effect. With the addition of EHB, the nucleation overpotential of the modified electrolyte (ZS-EHB) increases from 53.0 mV to 74.2 mV at 1 mA cm^-2. Consequently, the inhibition efficiency of Zn anode in ZS-EHB electrolyte exceeds 90 %, and the lifespan of the symmetric Zn||Zn cells in ZS-HEB electrolyte reaches 6200 h at 5 mA cm^-2 and over 2400 h at 8 mA cm^-2, nearly 80-fold longer than that of the cells in ZS electrolyte. Furthermore, the designed Zn||α-MnO₂ cells can still deliver a consistent discharge capacity of 120.1 mAh g^-1 even after 500 cycles. The research offers a promising route for creating zinc anode electrolyte additives.