Study on the Performance of Aqueous Aluminum‐Ion Battery with Al[TFSI]₃ Electrolyte

Abstract

Aqueous aluminum‐ion batteries have higher energy density and lower cost than traditional rechargeable batteries. Electrolytes play a vital role in aqueous aluminum‐ion battery and are directly related to battery performance. However, ionic liquid electrolytes suitable for aluminum are expensive and have potential environmental problems. To improve the energy density and reduce the environmental impact, this study innovatively proposes a new aqueous electrolyte. In this article, a battery preparation and performance testing bench is built to prepare a new aqueous aluminum‐ion battery. A novel aqueous aluminum‐ion battery is proposed using α‐MnO2 as the positive electrode, eutectic mixture‐coated aluminum anode (UTAl) as the negative electrode, and aluminum bistrifluoromethanesulfonate (Al[TFSI]3) aqueous solution as the electrolyte. The electrochemical performance of the prepared aqueous aluminum‐ion battery is studied under multiple working conditions. The results show that the assembled UTAl/Al[TFSI]3/α‐MnO2 battery exhibits an ultrahigh first‐cycle specific energy of up to 420 mAh g−1 at room temperature and a current density of 50 mA g−1 for 5 mol L−1 Al[TFSI]3. The newly developed battery can achieve a capacity retention rate of 63.4%, a Coulombic efficiency of over 94%, and a stable charge and discharge voltage platform of 1.65 and 1.4 V.