Small Dipolar Molecules Containing Electrolytes for Aqueous High-energy Dual-ion Batteries

Project: Research

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It is particularly important to develop large-scale energy storage systems integrated with renewable energy. Aprotic lithium-ion batteries (LIB) have been successfully applied in various scenarios but their inevitably applying flammable organic electrolyte make LIB not an absolutely safe candidate due to the fire-catching and explosive concerns. Aqueous batteries are ideal choices because of its natural advantages of safety and intrinsically low cost. However, the dominant shortcoming of aqueous batteries is the low output voltage and inferior specific energy density. Voltage and capacity of batteries jointly determine their energy density. The voltage is limited by the narrow electrochemical stability window (ESW) of the aqueous electrolytes, which also limits the selection of electrode materials. One feasible approach to broaden the ESW of aqueous electrolytes is to regulate the water hydrogen bond networks and deplete water molecules in the solvation sheath structure of charge carriers. One representative example is the ‘water-in-salt’ concept, but its eye-catching drawbacks is the high-cost and chemical environments either too acidic or too alkaline. Inspired by the working principle, there is a promising strategy that introducing small dipolar molecules into aqueous electrolytes to break the hydrogen bond networks between water molecules and modify the solvent sheath structure. Anion intercalation throughout the 2D layered materials possesses high theoretical potentials, e.g., over 2 V. Thus, it is promising to develop a high-energy aqueous dual-ion battery by coupling this kind of mechanism with cation-based working anode with lower operating potential. In addition, the output voltage of the full cell can be further manipulated through the optimization of the intercalation energy and solvation energy of both cations and anions as well as their matching majorization. In this project, we propose to develop three small dipolar molecule-containing electrolytes (SMCEs) based on acetamide, glycerol and erythritol to expand the ESW of aqueous electrolytes. In addition, to obtain high performance full cells, functional additives toaccelerate film forming and enhance ionic conductivity will be introduced. High entropy electrolytes based on the SMCEs with both broad ESW and wide operating temperature range will also be explored. Prototypical dual-ion zinc-graphite batteries will be designedbased on the SMCEs, where the output voltage can be regulated by intercalation energy and solvation energy of both cationic Zn2+ ion and different anions. In addition, the Li4Ti5O12/phosphorene/MXene dual-ion battery systems will be constructed utilizing thedeveloped SMCEs and the effects of different cathode materials will be elaborately explored. 


Project number9043395
Grant typeGRF
Effective start/end date1/01/23 → …