Simultaneously Regulating Solvation Structure and Interphase by Strong Donor Cosolvent for Stable Zn-Metal Batteries

Abstract

Aqueous Zn-metal battery has been regarded as the most scalable system for grid-scale energy storage, yet challenges arise from arbitrary dendrite growth and Zn anode corrosion, thus restricting its practical application. Herein, a strong donor cosolvent (hexamethylphosphoramide, HMPA) is introduced to enable highly reversible Zn anode. It is demonstrated that the HMPA can preferentially adsorb on the surface of Zn as well as regulate the solvation structure of Zn 2+ by excluding H 2 O from the solvation sheath and thus weakens the activity of H 2 O, which contributes to a dense and uniform SEI layer that enables the homogeneous Zn electrodeposition. Owing to the above advantages, the resultant HMPA-containing electrolyte enables highly reversible Zn plating/stripping for thousands of cycles in Zn||Ti and Zn||Zn cells. Consequently, the cycling stability of Zn|| V 2 O 5 full cells is also significantly improved with a high capacity of 155 mAh g −1 maintained after 1500 cycles.