Liquid metal batteries for future energy storage

Abstract

Search for alternatives to traditional Li-ion batteries is a continuous quest for chemistry and materials science communities. One representative group is the family of rechargeable liquid metal batteries, which were initially exploited with the view for the implementation of intermittent energy sources due to their specific benefits including ultrafast electrode charge-transfer kinetics and the ability to resist microstructural electrode degradation. Although conventional liquid metal batteries require high temperatures to liquify electrodes, and maintain high conductivity of molten salt electrolytes, degrees of electrochemical irreversibility induced by the corrosive active components emerged as a drawback. In addition, safety issues caused by the complexity of parasitic chemical reactivities at high temperatures further complicated practical applications. To address these challenges, new paradigms for liquid metal batteries operated at room or intermediate temperatures are explored to circumvent the thermal managements, corrosive reactions, and challenges related to hermetic sealing, by applying alternative electrodes, manipulating the underlying electrochemical behavior via electrolyte design concepts, and engineering the electrode-electrolyte interfaces, thereby enabling both conventional and completely new functionalities. This report briefly summaries preceding research on liquid metal batteries and, in particular, highlights our fresh understanding of electrochemistry of liquid metal batteries that have arisen from researchers’ efforts, along with discovered hurdles that have been realized in reformulated cells. Finally, the feasibility of new liquid metal batteries is discussed along with their distinct chemistries and performance characteristics to answer the question of how liquid metals can be accessible for next-generation battery systems