Utilizing hydrogen evolution reaction: bio-inspired pH-sensitive electrolyte for ultra-stable zinc-ion batteries at high temperatures

Abstract

Broader contextPractical high temperature (> 80 °C) zinc-ion batteries with high energy density and stable cycling performance are greatly desirable for sustainable energy storage, but they remain constrained by the notorious hydrogen evolution reaction (HER). Such unwanted reaction not only reduces the reversibility of Zn anode, but also accelerates battery swelling and even causes battery explosion.Inhibiting HER is a widely adopted strategy to enhance battery performance. However, since HER is severely exaggerated at high temperatures, the strategy fails to intrinsically prevent HER and Zn electrodes only work well with low depth of discharge (DOD) and low current densities/capacities.Herein, contrary to the commonly utilized HER suppression routes, a novel HER utilization strategy is proposed by introducing pH-sensitive electrolyte that harness the HER process to in situ form a unique ZrO 2 /ZnF 2 interface on Zn anode. The bio-inspired interface significantly shields H 2 O molecules, homogenizes Zn 2+ flux and optimizes ionic and thermal fields, thus mitigating further side reactions and prohibiting Zn dendrites growth. With the pH-sensitive electrolyte design, the stability of Zn anode is drastically enhanced with high DOD at high current densities/capacities, which also boards the tactics for the development of stable metal batteries with high energy densities at high temperatures.