Impact of Aluminium Electrode Potential during Charging on Aluminium-Ion Battery Performance with TEA-AlCl3 Electrolyte

Abstract

In aluminium (Al) symmetric cell, potentials during Al deposition on an Al foil at 1 mA cm−2 were 60–70 mV higher in TEA-AlCl3 electrolyte compared to those measured with EMIMCl-AlCl3 reference. Because of higher electrochemical stability of TEA-AlCl3 solution, cut-off voltage of charging step in AIB full-cell was set to 2.45 V compared to 2.40 V for the reference cell. During long-term cycling at 1 A g−1, the specific capacity of the AIB cell employing TEA-AlCl3 increased from 60 to 94 mAh g−1 (57 %) after 1000 cycles while that of cell with EMIMCl-AlCl3 was quite constant at about 60 mAh g−1. This behaviour was explained by continuous decreasing in Al electrode potential at End-of-Charge state (EOC) during deposition reaction (charging step) in TEA-AlCl3 allowing an increase in graphite electrode potential and consequently in AIB cell capacity over the whole experiment. This increase in capacity was accompanied by a raise of defect sites in graphite material.