Ultrahigh Capacity from Complexation‐Enabled Aluminum‐Ion Batteries with C<sub>70</sub> as the Cathode
Chenli Huang, Ying Yang, Mengyang Li, Xiaoqun Qi, Changwang Pan, Kun Guo, Lipiao Bao, Xing Lü
Abstract
Abstract Restricted by the available energy storage modes, currently rechargeable aluminum‐ion batteries (RABs) can only provide a very limited experimental capacity, regardless of the very high gravimetric capacity of Al (2980 mAh g −1 ). Here, a novel complexation mechanism is reported for energy storage in RABs by utilizing 0D fullerene C 70 as the cathode. This mechanism enables remarkable discharge voltage (≈1.65 V) and especially a record‐high reversible specific capacity (750 mAh g −1 at 200 mA g −1 ) of RABs. By means of in situ Raman monitoring, mass spectrometry, and density functional theory (DFT) calculations, it is found that this elevated capacity is attributed to the direct complexation of one C 70 molecule with 23.5 (super)halogen moieties (superhalogen AlCl 4 and/or halogen Cl) in average, forming (super)halogenated C 70 ·(AlCl 4 ) m Cl n‐m complexes. Upon discharging, decomplexation of C 70 ·(AlCl 4 ) m Cl n‐m releases AlCl 4 − /Cl − ions while preserving the intact fullerene cage. This work provides a new route to realize high‐capacity and long‐life batteries following the complexation mechanism.