The Construction of Binary Phase Electrolyte Interface for Highly Stable Zinc Anodes.

Metal zinc is a promising anode candidate of aqueous zinc-ion batteries due to high theoretical capacity, low cost and high safety. However, it often suffers from hydrogen evolution reaction (HER), Zn dendrite growth and formation of by-products. Herein, a triethyl phosphate (TEP)/H 2 O binary phase electrolyte (BPE) interface was developed by introducing TEP-based electrolyte-wetted hydrophobic polypropylene (PP) separator onto the Zn anode surface. The equilibrium of BPE interface depends on the comparable surface tension of H 2 O-based and TEP-based electrolytes on hydrophobic PP separator surfaces. The BPE interface will induce Zn 2+ solvation structure conversion from [Zn(H 2 O) x ] 2+ to [Zn(TEP) n (H 2 O) y ] 2+ , where most solvated H 2 O molecules are removed. In [Zn(TEP) n (H 2 O) y ] 2+ , the residual H 2 O molecules can be further constrained by the formation of H-bonds between TEP and H 2 O molecules. Consequently, the ionization of solvated H 2 O molecules is effectively suppressed, and the HER and by-products will be effectively restricted on Zn anode surfaces in BPE. As a result, Zn anodes exhibit a high Coulombic efficiency of 99.12% and superior cycling performance of 6000 h, which is much higher than the case in single-phase aqueous electrolytes. To illustrate the feasibility of BPE in full cells, the Zn/Al x V 2 O 5 batteries were assembled based on the BPE and exhibited enhanced cycling performance. This article is protected by copyright. All rights reserved.