Mitigating water-related challenges in aqueous zinc-ion batteries through ether-water hybrid electrolytes

Abstract

Aqueous zinc-ion batteries (AZIBs) are an attractive option for different energy storage applications due to their cost-effectiveness, safety benefits, and high capacity. Nevertheless, their development is constrained by challenges such as hydrogen evolution reaction (HER), significantly affecting the battery lifespan. This work presents a promising solution to this problem using a hybrid electrolyte, consisting of water and tetra ethylene glycol dimethyl ether (TEGDME) containing Zn(OTf)2. Results demonstrate that this hybrid electrolyte can suppress HER and can lessen zinc corrosion by reorienting hydrogen bonds with water and actively participating in the solvation structure of Zn2+ ions. Such reorientation reduces water activity and weakens the interactions between water molecules and between water and Zn2+ ions. By employing an optimal TEGDME/H2O ratio of 2:1 in the hybrid electrolyte, hydrogen evolution overpotential increased by 0.26 V. As a result, in the Zn//Zn symmetrical cells, the developed hybrid electrolyte is seen to enable the Zn electrode to exhibit excellent cycle durability, lasting over 4300 h with coulombic efficiency (CE) of 99.68% at 0.5 mA cm−2 and 0.5 mAh cm−2, surpassing the 92.79% achieved by the base electrolyte (1 M Zn(OTf)2 aqueous solution) cells. Moreover, when implemented in Zn/δ-MnO2 batteries, the hybrid electrolyte maintained its performance for over 1800 cycles at a discharge rate of 100 mA g−1. This cost-effective and adaptable strategy highlights its wide-ranging potential, offering vital insights for the enhancement of AZIB technology.