Regulating Zn-ion solvation structure and Zn(0 0 2) deposition for stable Zn anode

Abstract

Severe side reactions and Zn dendrite growth are two main causes deteriorating the stability of zinc metal anodes. N,N-dimethylpropionamide (DMP) is investigated as an electrolyte additive to suppress side reactions and regulate Zn deposition. Experimental results and theoretical calculations demonstrate that the DMP additive can facilitate solvation structure of hydrated Zn2+ and electrode–electrolyte interface in aqueous ZnSO4 electrolyte. DMP develops strong coordination with Zn2+ through the carbonyl group to reduce the water activity, consequently alleviating the water-associated side reactions. DMP prefers to adsorb on (100) and (101) planes rather than (002), inducing the preferential growth of Zn along the (002) crystal plane. As a result, the ZnSO4 + 10 % DMP electrolyte enables stable Zn plating/stripping in Zn||Zn symmetric cells with a capacity of 1 mAh cm−2 at 1 mA cm−2 for 4000 h, and offers good reversibility in Zn||Cu cells with an average Coulombic efficiency of 99.7 % over 2000 cycles. The coupled Zn||NH4V4O10 full cell using ZnSO4 with 10 % DMP additive exhibits enhanced stability.