posted on 2024-02-27, 18:55authored byMinxia Jiang, Minxi Li, Chang Cui, Jie Wang, Yang Cheng, Yixin Wang, Xing Zhang, Jinwen Qin, Minhua Cao
Ti3C2Tx MXene
often suffers from poor lithium storage behaviors due to its electrochemically
unfavorable OH terminations. Herein, we propose molecular-level interfacial
chemistry regulation of Ti3C2Tx MXene with phytic acid (PA) to directly activate its OH terminations.
Through constructing hydrogen bonds (H-bonds) between oxygen atoms
of PA and OH terminations on Ti3C2Tx surface, interfacial charge distribution of Ti3C2Tx has been effectively
regulated, thereby enabling sufficient ion-storage sites and expediting
ion transport kinetics for high-performance energy storage. The results
show that Li ions preferably bind to H-bond acceptors (oxygen atoms
from PA), and the flexibility of H-bonds therefore renders their interactions
with adsorbed Li ions chemically “tunable”, thus alleviating
undesirable localized geometric changes of the OH terminations. Meanwhile
the H-bond-induced microscopic dipoles can act as directional Li-ion
pumps to expedite ion diffusion kinetics with lower energy barrier.
As a result, the as-designed Ti3C2Tx/PA achieves a 2.4-fold capacity enhancement compared
with pristine Ti3C2Tx (even beyond theoretical capacity), superior long-term cyclability
(220.0 mAh g–1 after 2000 cycles at 2.0 A g–1), and broad temperature adaptability (−20
to 50 °C). This work offers a promising interface engineering
strategy to regulate microenvironments of inherent terminations for
breaking through the energy storage performance of MXenes.