The water-in-salt electrolytes have promoted aqueous Li-ion batteries to become one of the most promising candidates to overcome safety concerns/issues of traditional Li-ion batteries. A simple increase of Li-salt concentration in electrolytes can successfully expand the electrochemical stability window of aqueous electrolytes beyond 2 V. However, necessary stability improvements require an increase in complexity of the ternary electrolytes. Here, we have explored the effects of novel, Gemini-type ionic liquids (GILs) as a co-solvent systems in aqueous Li[TFSI] mixtures and investigated the transport properties of the resulting electrolytes, as well as their electrochemical performance. The devices containing pyrrolidinium-based GILs show superior cycling stability and promising specific capacity in the cells based on the commonly used electrode materials LTO (Li4Ti5O12) and LMO (LiMn2O4). © 2023, The Author(s).
Funding details: Vetenskapsrådet, VR, 2020-06701; Funding details: Energimyndigheten, 50119-1; Funding text 1: The work was supported by the Swedish Energy Agency contract no. 50119-1, entitled “Be WiSE—Robotic screening of water-in-salt electrolytes (WiSE) for environmental batteries” and the Swedish Research Council contract no. 2020-06701.