Safe Solvent-in-Salt Electrolytes for Dendrite-Free Zinc Metal Batteries

Abstract

As global markets for electric vehicles (EV) and energy storage systems (ESS) expand rapidly, there are growing needs to develop alternative battery systems to replace current lithium-ion battery (LIBs) technology, which suffers from high material cost, and insufficient safety. Rechargeable zinc batteries have emerged as one of the most viable and sustainable candidates to replace LIB owing to various beneficial features of zinc such as natural abundance, easy recyclability (by electrowinning), high safety and high volumetric capacity (5,854 Ah/L) compared with lithium (2,062 Ah/L). However, parasitic side reactions such as spontaneous Zn corrosion & hydrogen evolution, and unregulated dendritic growth of Zn deposit may occur in the aqueous electrolytes, which may eventually degrade the battery performance and safety seriously. In this work, we focus on an alternative method for regulating the morphological development of the Zn metal deposit using highly-concentrated organic electrolytes, which exhibits particular physicochemical properties such as high electrochemical window, high stability, and non-flammability. We will show that it does not only suppress the formation of dendrite effectively during Zn plating-stripping process via regulating the crystal growth of Zn deposits, but also hold a flame-retarding property, thereby making it appropriate as a highly-safe anode for rechargeable batteries. This study proposed a new strategy of making a battery with dendrite-free operation, high stability, and a long cycle-life by controlling the crystal facet of a Zn metal deposit using highly-concentrated organic electrolytes. Keywords: Zinc metal, highly-concentrated organic electrolytes, dendrite-free, high redox stability Acknowledgments This work was supported by the KIST institutional program (KIST-2E32582) and the National Research Foundation of Korea (NRF-2021R1A2C2008680)