(435c) All-Climate and Ultrafast Rechargeable Aluminum Batteries Enabled By Tertiary Eutectic Electrolytes | AIChE

(435c) All-Climate and Ultrafast Rechargeable Aluminum Batteries Enabled By Tertiary Eutectic Electrolytes


Fetrow, C., University of New Mexico
Wei, S., University of New Mexico
Lithium-ion technology is one of the most successful energy storage technologies every hit the market and yet the application towards the grid-storage and electric vehicles is limited. Multivalent metal-ion batteries remain as one of the promising and potential contenders to address the inherent challenges posed by Li-ion chemistry. In recent years, Al has attracted great interest due to advantages envisaged such as high volumetric capacity (8046 mAh.cm-3 vs. 2262 mAh.cm-3 for Li), high abundance in earth’s crust (82000 ppm vs. 65ppm for Li), multiple electrons transfer per single metal reduction (3e- vs. 1e- for Li) and low cost (1.9 USD.kg-1 vs. 19.2 USD.kg-1 for Li). However, the major challenge is the development of electrolytes which offer wide thermal and potential stability window.

Here, we designed a tertiary eutectic electrolyte comprised of 1-ethyl-3-methylimidazolium chloride([C2mim]Cl):1-butyl-3-methylimidazolium chloride([C4mim]Cl):AlCl3 for the application of aluminium batteries, suitable for all-climate conditions. The binary eutectic phase between [C2mim]Cl:[C4mim]Cl (1:1 mole ratio) at ~40 °C is identified due to the dominating Van der walls forces of attraction between the different-alkyl chain containing organic molecules than the electrostatic forces present between the cations and anions. Further, the addition of AlCl3 to the binary eutectic, forms tertiary phase eutectic at room temperature based on the acid-base reactions. The differential scanning calorimetry studies on the tertiary eutectic renders significantly low freezing point (<-50 °C) which is a prerequisite condition for all-climate batteries and appreciably high ionic conductivity of ~8 mS.cm-1 at room temperature. The eutectic offers improved electrochemical stability window of ~2.8V vs. Al/Al+3 against the stainless-steel electrode. Galvanostatic charge-discharge analysis of Al||graphene cell retrieves a high discharge capacity of ~150 mAh.g-1 at ultra-high current density of 1 A.g-1 and ~120 mAh.g-1 at 3A.g-1. The rapid charge-discharge (<1 minute) at ultra-high current density of ~5A.g-1 delivers ~70 mAh.g-1 capacity and shows a very minimum capacity fade of <1% per cycle. The study opens-up a broad area of research to investigate the mixed ionic liquid-based eutectics for the design of highly efficient, safe batteries with improved energy density.