π-Electron-Assisted Charge Storage in Fused-Ring Aromatic Carbonyl Electrodes for Aqueous Manganese-Ion Batteries

Rechargeable manganese batteries hold promise for large-scale energy storage due to the abundance and eco-friendly nature of manganese. A key challenge is developing cathode materials capable of reversibly inserting Mn ions with a high specific capacity. Here, we demonstrate that perylene-3,4,9,10-tetracarboxylic dianhydride electrodes efficiently and reversibly insert Mn²⁺ ions in 3 M MnCl₂ aqueous electrolyte solutions. Leveraging the carbonyl groups and the π-electron configuration, such compounds can serve as robust redox centers, facilitating reversible interactions with divalent ions such as Mn²⁺. Through comprehensive studies involving electrochemistry, elemental analyses, spectroscopy, and structural analysis, we explored these systems and found them as promising anode materials for Mn batteries. Demonstrating excellent Mn storage capabilities, such molecules could attain a reversible capacity of approximately >185 mAh g^-1 at a current density of 100 mA g^-1, maintaining an average voltage of approximately 0.8 V vs Mn/Mn²⁺, while exhibiting notable capacity retention.