A Systematic Electrochemical Investigation of a Dimethylamine Cosolvent-Assisted Nonaqueous Zinc(II) Bis(trifluoromethylsulfonyl)imide Electrolyte

The development of the multivalent electrolytes is a critical component to advance polyvalent energy storage technology. In this work, a new and simple nonaqueous zinc electrolyte is developed and investigated where a secondary amine is introduced as a cosolvent. The addition of dimethylamine (DMA) as a cosolvent in THF facilitates the solubilization of Zinc (II) bis(trifluoromethanesulfonyl)imde (Zn(TFSI)(2)) and results in a homogeneous electrolyte with reversible plating of zinc achieved at high coulombic efficiencies. The electrochemical properties of the developed electrolyte and the effects of the cosolvent and salt concentrations are systematically investigated. It was found that increasing the ratio of the cosolvent DMA in THF for a Zn(TFSI)(2) electrolyte leads to more facile kinetics, better ion solubilization, and higher ion mobility evidenced by up a significant increase in conductivity as well as the plating/stripping current densities. Increased Zn(TFSI)(2) salt concentration in a 2.0 M DMA in THF solvent mixture not only leads to a higher current density and conductivity, but also a higher molar conductivity due to a redissociation mechanism. The findings in this study are relevant and important to further understand and characterize multivalent electrolytes from a simple and effective electrolyte design strategy.

Automated summary

The development of a new nonaqueous zinc electrolyte with dimethylamine as a cosolvent allows for reversible plating of zinc with high coulombic efficiencies. Adjusting the ratio of cosolvent DMA in THF can enhance kinetics, ion solubilization, and ion mobility, resulting in increased conductivity and plating/stripping current densities. Additionally, increasing the Zn(TFSI)(2) salt concentration in a 2.0 M DMA in THF solvent mixture leads to higher current density, conductivity, and molar conductivity due to a redissociation mechanism. These findings contribute to a better understanding of multivalent electrolytes and effective electrolyte design strategies.