Symposium EN05—Emerging Materials for Electrochemical Energy Storage Devices—Degradation and Failure Characterization—From Composition, Structure and Interfaces to Deployed Systems

Maria Lukatskaya, ETH Zurich

Concentrated Mixed Cation “Water-in-Salt” Solutions as Low Cost High Voltage Electrolytes for Aqueous Batteries

Written by Xinzi He

Maria Lukatskaya started the talk with an introduction on the highly concentrated “water-in-salt,” WIS, and its capability of enlarging the electrochemical window and its drawbacks of the toxicity associated with organic imides and high price. Firstly, Prof. Lukatskaya proposed a mixed cation strategy that enable the utilization of cheaper and more soluble salts compared to lithium salts. Potassium acetate was studied, and an enlarged electrochemical window was found for a series of electrode materials including Li₄Ti₆O₁₂, Mo₆S₈, LiFePO₄, and LiMn₂O₄. Other advantages include cheaper (~0.5$/L) prices, environmentally friendly, and non-flammability. Secondly, co-dissolution effects in the K-Zn system were investigated by Dario Gomez, the PhD student in Prof. Lukatskaya’s group. Interpenetration of the hydration shells and ion-pairing is found upon increasing the concentration. Compatibility with traditional Zn-ion battery electrode materials while being low-cost and environmentally benign were demonstrated. “Bi-cation approach can enable new green and low-cost electrolyte formulations,” Prof. Lukatskaya emphasized at the end of the talk.