Asymmetric 1, 2-naphthoquinone cathode material with enhanced capacity for rechargeable aluminium ion batteries

Abstract

Rechargeable aluminium ion batteries (RAIBs) offer higher safety and lower costs than traditional lithium-ion batteries and have therefore been seen in recent years as a very promising potential development in areas such as large-scale energy storage. However, the development of RAIBs is limited by the cathode material, with most research currently focused on inorganic materials. Organic small molecules like naphthoquinone (NQ) based derivants have the potential to be advantageous in designing high performance cathode materials due to their molecular structural diversity and tunability. Together with 1, 4-NQ, 1, 2-NQ was successfully prepared by chemical oxidation using naphthol derivatives and assembled as RAIBs. Elucidated by Gaussian calculation, the asymmetric structure of 1, 2-NQ provides reaction sites with a higher possibility of binding to AlCl2+ ions than 1, 4-NQ, to the extent that there is an expected enhancement in its electrochemical performance. It is verified by the experimental results that the chemical and electrochemical stability of NQ cathode materials in ionic liquids is improved by the asymmetric structure. The 1, 2-NQ based RAIBs exhibits an outstanding initial specific capacity of 165.9 mAh g−1 and remains at 117.2 mAh g−1 with a Coulombic efficiency of about 98 % after the cycling of 600 and longer cycle life than the 1, 4-NQ based ones. The working concept and satisfying performance of the NQ based cathode material suggest that asymmetric molecules could be a promising design strategy for developing high-performance electrode materials for RAIBs.