Modulating Aluminum Solvation with Ionic Liquids for Improved Aqueous-Based Aluminum-Ion Batteries

Abhishek Lahiri; Shaoliang Guan; Arunabhiram Chutia

doi:10.1021/acsaem.3c01745

Modulating Aluminum Solvation with Ionic Liquids for Improved Aqueous-Based Aluminum-Ion Batteries

ACS Appl Energy Mater. 2023 Nov 22;6(23):11874-11881. doi: 10.1021/acsaem.3c01745. eCollection 2023 Dec 11.

Authors

Abhishek Lahiri¹, Shaoliang Guan^{2

3}, Arunabhiram Chutia⁴

Affiliations

¹ Department of Chemical Engineering, Brunel University London, Uxbridge UB8 3PH, U.K.
² School of Chemistry, Cardiff University, Cardiff CF10 3AT, U.K.
³ HarwellXPS, Research Complex at Harwell, Rutherford Appleton Laboratory, Didcot OX11 0FA, U.K.
⁴ School of Chemistry, University of Lincoln, Brayford Pool, Lincoln LN6 7UY, U.K.

Abstract

Aqueous-based Al-ion batteries are attractive alternatives to Li-ion batteries due to their safety, high volumetric energy density, abundance, and recyclability. Although aluminum-ion batteries are attractive, there are major challenges to overcome, which include understanding the nature of the passive layer of aluminum oxide on the aluminum anode, the narrow electrochemical window of aqueous electrolytes, and lack of suitable cathodes. Here, we report using experiments in conjunction with DFT simulations to clarify the role of ionic liquids (ILs) in altering the Al solvation dynamics, which in turn affects the aluminum electrochemistry and aqueous-based battery performance significantly. DFT calculations showed that the addition of 1-ethyl-3-methylimidazolium trifluoromethylsulfonate (EMIMTfO) changes the aluminum solvation structure in the aqueous (Al(TfO)₃) electrolyte to lower coordinated solvation shells, thereby influencing and improving Al deposition/stripping on the Zn/Al alloy anode. Furthermore, the addition of an IL reduces the strain in manganese oxide during intercalation/deintercalation, thereby improving the Zn/Al-MnO_x battery performance. By optimizing the electrolyte composition, a battery potential of >1.7 V was achieved for the Zn/Al-MnO_x system.