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

Achieving high-temperature Zn-ion batteries with stable cycling performance and deep Zn utilization remains a great challenge due to the accelerated hydrogen evolution reaction (HER) and irreversible dendrite growth. Herein, contrary to conventional strategies that aim to suppress the HER for achieving stable performance, we report a bio-inspired pH-sensitive electrolyte that exploits the adverse and unwanted, inevitable HER to generate an initial high-pH microenvironment, which in turn autonomously drives the formation of a robust porous ZrO2/ZnF2 interphase. Such a self-triggered interphase not only spontaneously shields H2O molecules and homogenizes Zn2+ flux but also optimizes ionic and thermal field distributions, thus constantly mitigating further side reactions and prohibiting Zn dendrite growth. With this pH-sensitive electrolyte design, a Zn//Zn cell shows stable cycling for 130 h at 20 mA cm−2/5 mAh cm−2 at high temperatures (85.5% depth of discharge), which outperforms previously reported high-temperature Zn anodes. A stable full battery with high energy density (150.4 Wh kg−1) at 80 °C is also demonstrated.