In recent years, with the gradual depletion of traditional energy, Secondary battery is being widely researched and applied, and will become a vital force in a plenty variety of new green energy. Aluminium is the most abundant metal in the earth’s crust and each aluminum ion carries three electrons which make the capacity of the aluminum ion battery is expected to be greatly improved. Additionally, aluminum ion battery might offer significant cost savings and safety improvements over the Li-ion battery platform due to the price of aluminum is much lower than that of lithium. However, at present, the working voltage and energy density of the aluminum ion battery is lower than that of the lithium ion battery, so it is urgent to develop a new kind of positive electrode material of aluminum ion battery to improve the electrochemical performance. [1-2]

In the work, we report on a novel Al-ion battery system using graphite oxide as the cathode against an aluminium metal anode in an ionic liquid (IL), 1-butyl-3-methylimidazolium trifluoromethanesulfonate ([BMIM]OTF) and aluminum trifluoromethanesulfonate (Al(OTF)3), -based electrolyte. [3] As shown in Figure 1a, the charge and discharge capacity gradually decreased with the increase of cycle number. However, reduction of discharge capacity is much smaller than that of the charge capacity. As shown in Figure 1b, with the increase of cycle number, the discharge capacity is gradually reduced and the coulombic efficiency is gradually increased, which are consistent with the results obtained from the Fig.1a. It can be seen from the Fig.1a that the first discharge capacity of graphite oxide cathode is only 26.7 mAh/g and its electrochemical polarization is relatively large, so we will further improve the oxidation graphite to enhance the electrochemical properties of aluminum ion batteries.

Reference

1. Dunn, B.; Kamath, H.; Tarascon, J.M., (2011) Electrical energy storage for the grid: a battery of choices. Science, 334: 928-935

2. Lin, M.C.; Gong, M.; Lu, B.; Wu, Y. P.; Wang, D.Y.; Guan, M.; Angell, M.; Chen, C.;Yang, J.; Hwang, B.J.; Dai, H., (2015) An Ultrafast Rechargeable Aluminium-Ion Battery. Nature, 520: 524-528.

3. wang, H.L.; Gu, S.C.; Bai, Y.; Chen, S.; Wu, F.; Wu, C.; (2016) A high-voltage and non-corrosive ionic liquid electrolyte used in rechargeable aluminum battery. ACS Appl. Mater. Interfaces, 8: 27444-27448.

Acknowledgments

The experimental research was funded by the National Natural Science Foundation of China (no.51572024, 51372021)