A high discharge voltage dual-ion rechargeable battery using pure (DMPI⁺)(AlCl₄⁻) ionic liquid electrolyte

Dual-ion batteries (DIBs) are widely studied as novel electrochemical energy storage devices in view of their low cost, environmental friendliness, and high working voltage. However, the widespread application of these batteries is hindered by organic electrolyte decomposition at high working voltages and the absence of electrode materials allowing for high capacity and long cycle lifetime, which necessitates further investigations toward performance improvement. Herein, we use 1,2-dimethyl-3-propylimidazolium chloroaluminate (DMPI⁺)(AlCl₄⁻) as an ionic liquid electrolyte and graphite rods as electrodes to fabricate a DIB with excellent electrochemical performance, revealing that the redox amphotericity of carbon allows the intercalation/deintercalation of both cations and anions into/from the graphite electrodes. The developed DIB is shown to exhibit high discharge voltage plateaus of 4.2–4.0 and 3.6–3.1 V, a reversible specific capacity of ∼80 mAh g⁻¹ at a current density of 300 mA g⁻¹, and a high coulombic efficiency of ∼97% over 300 cycles. Moreover, the non-flammability and electrochemical stability of the employed electrolyte result in improved safety and performance, allowing the fabricated DIB to function under various critical conditions such as high C-rate charge/discharge, continuous bending, and even burning. Thus, the developed battery is concluded to hold great promise for grid energy storage and other applications.