NOVEL AQUEOUS-BASED ELECTROLYTES AND ELECTRODE SYSTEMS FOR THE NEXT GENERATION OF AQUEOUS LITHIUM-ION BATTERIES

Abstract

Aqueous Li-ion batteries are a vital component for the future electrification of society. Their extreme safety and reduced manufacturing costs could enable them to fit into many niche markets. Current aqueous Li-ion battery systems suffer from many of the same form factor restrictions as organic Li-ion batteries and rely heavily on maximizing the amount of LiTFSI in the system at the cost of important properties such as electrolyte cost, viscosity, and ionic conductivity in order to maintain the highly concentrated electrolyte classification. They are also limited by the lack of suitable anodes to replace the dominant choice of LTO. Much of the advancement in recent years has been due to the focus on improving the SEI with less attention paid to other important concerns. The goal of this research is not only to continue advancing the limits of aqueous Li-ion batteries, but to shed light on some of the other areas that are often overlooked but of equal importance. Reported here are three key advancements in the development of a novel aqueous cell chemistry for form factor, electrolyte, and anode. First is the development of a gel polymer electrolyte and gel protection layer for the fabrication of a flexible 4V aqueous Li-ion battery employing a Graphite/LCO electrode pair, with focus given to the system’s feasibility to be transitioned to industry. Second, the development of a safer hybrid electrolyte and subsequent transition from the highly concentrated electrolyte regime to the first reported localized highly concentrated hybrid aqueous/non-aqueous electrolyte. Finally, the first incorporation of TNO as an anode replacement for LTO. With the combination of this novel electrolyte and aqueous anode chemistry, a TNO/LMO full cell using a 1,4-dioxane diluted water/TEP co-solvent electrolyte provided an initial discharge capacity of 187 mAh/g reaching a Coulombic efficiency of >99.5% and a capacity retention of 92% after 90 cycles at a cycling cutoff potential of 2.8V.