Low-Cost AlCl<sub>3</sub>–GdnHCl Deep Eutectic Solvent Electrolyte for High-Performance Al/Graphite Batteries
Lu Kang, Qingning Li, Ketong Luo, Shengkui Zhong, Dongliang Yan
Abstract
Nonaqueous rechargeable Al batteries (RABs) have attracted significant research interest due to the extremely abundant reserves, high theoretical capacities, and low-cost. However, the commonly used nonaqueous RAB ionic liquid (IL) electrolytes are highly air-sensitive and high-cost, which seriously limits their commercial application. Herein, AlCl 3 –guanidine hydrochloride (AlCl 3 –GdnHCl), a new low-cost and environmentally friendly deep eutectic solvent (DES) with only 1/40 of the cost of [EMIm]Al x Cl y is introduced into applications for nonaqueous RABs. The battery displays a discharge capacity of 128 mAh g –1 at 0.1 A g –1, which is significantly higher than that of 88 mAh g –1 in [EMIC]Al x Cl y electrolyte. It can reach 124.6 mAh g –1 at 1 A g –1 with the Coulombic efficiency of 99.5% for 1000 cycles. According to the mechanism studies, during the charge–discharge cycle, the fast deposition/dissolution reaction of Al took place at the anode side, while intercalation/deintercalation reaction of [AlCl 2 (Gdn) n ] + ions and chloroaluminate anions [Al x Cl y ] − (i.e., Al 2 Cl 7 – and AlCl 4 – ) occurred at the graphite cathode side. With such significant electrochemical behaviors, the AlCl 3 –GdnHCl DES possesses great potential for use in high-performance storage devices.