Boosted π-Li Cation Effect in the Stabilized Small Organic Molecule Electrode via Hydrogen Bonding with MXene.

Abstract

The high solubility of the small organic molecule materials in organic electrolytes hinders their development in rechargeable batteries. Hence, this work designs an ultrarobust hydrogen-bonded organic-inorganic hybrid material: the small organic unit of the 1,3,6,8-tetrakis (p-benzoic acid) pyrene (TBAP) molecule connected with the hydroxylated Ti3C2Tx MXene through hydrogen bonds between the terminal groups of -COOH and -OH. The robust and elastic hydrogen bonds can empower the TBAP, despite being a low-molecule organic chemical, with unusually low solubility in organic electrolytes and thermal stability. The alkali-treated Ti3C2Tx MXene provides a hydroxyl-rich conductive network, and the small organic molecule of TBAP reduces the restacking of MXene layers. Therefore, the combination of these two materials complements each other well, and this organic-inorganic TBAP@D-Ti3C2Tx electrode delivers large reversible capacities and long cyclic life. Notably, with the assistance of the in situ FT-IR characterization of the electrode within the fully lithiated (0.005 V) and the delithiated (3.0 V) states, it is revealed that a powerful π-Li cation effect mainly governs the lithium-storage mechanism with the highly activated benzene ring and each C6 aromatic ring, which can reversibly accept six Li-ions to form a 1:1 Li/C complex.