Kinetics Conditioning of (Electro) Chemically Stable Zn Anode with pH Regulation Toward Long‐Life Zn‐Storage Devices

Abstract

AbstractThe safety, low cost, and high power density of aqueous Zn‐based devices (AZDs) appeal to large‐scale energy storage. Yet, the presence of hydrogen evolution reaction (HER) and chemical corrosion in the AZDs leads to local OH− concentration increasement and the formation of ZnxSOy(OH)z•nH2O (ZHS) by‐products at the Zn/electrolyte interface, causing instability and irreversibility of the Zn‐anodes. Here, a strategy is proposed to regulate OH− by introducing a bio‐sourced/renewable polypeptide (ɛ‐PL) as a pH regulator in electrolyte. The consumption of OH− species is evaluated through in vitro titration and cell in vivo in situ attenuated total reflection surface‐enhanced infrared absorption spectroscopy at a macroscopic and molecular level. The introduction of ɛ‐PL is found to significantly suppress the formation of ZHS and associated side reactions, and reduce the local coordinated H2O of the Zn2+ solvation shell, widening electrochemical stable window and suppressing OH− generation during HER. As a result, the inclusion of ɛ‐PL improves the cycle time of Zn/Zn symmetrical cells from 15 to 225 h and enhances the cycle time of aqueous Zn‐ I2 cells to 1650 h compared to those with pristine electrolytes. This work highlights the potential of kinetical OH− regulation for by‐product and dendrite‐free AZDs.