Abstract
Ultrathin 2D hexagonal transition metal borides (h-MBenes) hold significant promise for advancing energy storage technologies. Herein, with cost-effective methods and earth-abundant metals, the experimental feasibility of atomically thin Ti-based 2D h-MBenes (TiBT(x)) for lithium-ion battery application is reported for the first time. These thin-layer nanosheets are synthesized by using ZnCl(2) molten salt as Ti(2)InB(2) etchant, followed with a delaminated intercalation of tetrabutylammonium hydroxide (denoted as d-TiBT(x)). The formation of disorderly low-boiling-point Zn-In intermediate phase is revealed to significantly reduce the In migration energy barrier and accelerate the lattice-In release from parent Ti(2)InB(2) under low-temperature. Moreover, in-depth analyses reveal that the formation of O-termination on the atomic d-TiBT(x) surface endows d-TiBT(x) h-MBene with exceptional lithium-ion migration, achieving an impressive specific capacity of 530 mAh g(-1) at 0.1 A g(-1) and an exceptional rate capability of 120 mAh g(-1) at 10 A g(-1). Notably, a lithium full-cell paired with a LiFePO(4) cathode achieves an impressive energy density of 425 Wh kg(-1) and retains 94.3% of its capacity after 100 cycles, sufficient to power a toy car under normal operation. This work confirms the usefulness of ultrathin Ti-based 2D MBenes, paving the way for innovatively harnessing the potential application of h-MBenes.