Metallic Zinc Anode Working at 50 and 50 mAh cm-2 with High Depth of Discharge via Electrical Double Layer Reconstruction

Achieving high-rate and high-areal-capacity Zn anode with high depth of discharge (DOD) offers a bright future for large-scale aqueous batteries. However, Zn deposition suffers from severe dendrite growth and side reactions, which compromises achievable lifetime. Herein, an electrical double layer (EDL) reconstruction strategy is proposed by employing acetone as electrolyte additive to fully address these issues. Experimental and theoretical simulation results reveal that the adsorption priority of acetone to water on Zn creates a water-poor inner Helmholtz layer. Meanwhile, the intense hydrogen bonding effect between acetone and water confines the activity of free water and weakens the Zn2+ solvation in the outer Helmholtz layer and diffusion layer. Such ion/molecule rearrangement in EDL suppresses hydrogen evolution, facilitates the desolvation process, and promotes the Zn2+ diffusion kinetics, which guides homogeneous Zn nucleation and uniform growth, even in extreme situations. At both ultrahigh current density of 50 mA cm(-2) and areal capacity of 50 mAh cm(-2), the addition of 20 v/v% acetone in 2 m ZnSO4 extends the lifespan of Zn//Zn symmetric cells from 12 to 800 h, with a high DOD of 73.5%. The effectiveness of this strategy is further demonstrated in the Zn-MnO2 full batteries at wide temperature range from -30 to 40 degrees C.

Automated summary

By using acetone as an electrolyte additive, an electrical double layer (EDL) reconstruction strategy is proposed to solve the dendrite growth and side reactions issues in Zn deposition, improving the depth of discharge. Experimental and theoretical simulation results show that the adsorption priority of acetone creates a water-poor inner Helmholtz layer, while the hydrogen bonding effect between acetone and water weakens the Zn2+ solvation. This rearrangement of ions/molecules in EDL suppresses hydrogen evolution, promotes the Zn2+ diffusion kinetics, and guides homogeneous Zn nucleation and growth.