Recent advances in developing organic positive electrode materials for rechargeable aluminum-ion batteries

Rechargeable aluminum-ion (Al-ion) batteries have been highlighted as a promising candidate for large-scale energy storage due to the abundant aluminum reserves, low cost, high intrinsic safety, and high theoretical energy density. However, the strong Coulombic interaction between the high charge density Al3+ and electrode host lattices leads to poor kinetics and insufficient cycle life in Al-ion batteries with inorganic electrodes. In contrast, organic electrode materials exhibit the advantages of designable molecular structure, flexible framework, coordinated energy storage chemistry, and resource sustainability. Nevertheless, organic materials encounter inherently high solubility, low active center utilization, and low electrical conductivity. Herein, the recent advances in developing organic positive electrode materials for Al-ion batteries is reviewed, and the charge storage mechanisms and electrochemical performances of different types of organic materials are systematically summarized. This review also discusses design strategies to improve specific capacity, operating voltage, cycle life, and rate capability of organic positive electrodes for Al-ion batteries. Finally, the challenges and research outlook toward high performance Al/organic batteries are presented.