An Aqueous Al-Ion Battery Boosted by Triple-Ion Intercalation Chemistry with a High-Energy MnAl
<sub>2</sub>O
<sub>4</sub> Nanosphere Cathode

AlCl₃ "water-in-salt" electrolyte has successfully expanded the electrochemical window of aqueous Al-ion battery to 4 volts, however, the limited Al intercalation capacity of graphite (165 mAh g^-1 ) preclude higher energy density. A high-energy MnAl₂O₄ cathode was synthesized by a simple two-step hydrothermal method, which can utilize triple-ion intercalation chemistry to achieve a high specific capacity of 330 mAh g^-1 with an average discharge voltage of 1.68V versus Al/Al³⁺ (a record energy density of 555 Wh kg^-1 ). Besides, a higher discharge capacity of 830 Wh kg^-1 was achieved with higher-concentration electrolyte, showing a potential capacity for cation intercalation. Unique triple-ion intercalation chemistry was firstly investigated thoroughly. Experimental characterization attributes this high voltage to the intercalation of anions, e.g., AlCl₄- and Cl- , and Cl- was also revealed an interaction function with intercalated Al³⁺ cations, which can benefit the design of Aluminium-ion batteries (AIBs) in the future.

Keywords: Aluminium-ion battery, Aqueous Al-ion battery, AlCl3 "water-in-salt" electrolyte, MnAl2O4 nanosphere cathode, High-energy cathode, Triple-ion intercalation chemistry, Intercalation of anions.

Suggested Citation: Suggested Citation

Pan, Wending and Mao, Jianjun and Wang, Y.F. and Zhao, X. and Zhang, Y.G. and Chen, Yue and Leung, Dennis Y. C., An Aqueous Al-Ion Battery Boosted by Triple-Ion Intercalation Chemistry with a High-Energy MnAl ₂O ₄ Nanosphere Cathode. Available at SSRN: https://ssrn.com/abstract=3569552 or http://dx.doi.org/10.2139/ssrn.3569552

This version of the paper has not been formally peer reviewed.