Ultrahigh Capacity from Complexation-Enabled Aluminum-Ion Batteries with C70 as the Cathode
Chenli Huang, Ying Yang, Mengyang Li, Xiaoqun Qi, Changwang Pan, Kun Guo, Lipiao Bao*, Xing Lu*
Advanced Materials
https://doi.org/10.1002/adma.202306244
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, we report a novel complexation mechanism for energy storage in RABs by utilizing zero-dimensional fullerene C70 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, we found that this elevated capacity is attributed to the direct complexation of one C70 molecule with 23.5 (super)halogen moieties (superhalogen AlCl4 and/or halogen Cl) in average, forming (super)halogenated C70·[AlCl4]mCln-m complexes. Upon discharging, decomplexation of C70·[AlCl4]mCln-m releases AlCl4−/Cl− ions while preserving the intact fullerene cage. Our work provides a new route to realize high-capacity and long-life batteries following the complexation mechanism.
