Interface-Engineered Fe₃O₄/MXene Heterostructures for Enhanced Lithium-Ion Storage

Fe3O4 is a potential anode material for lithium-ion batteries (LIBs) due to its high theoretical capacity (926 mAh g–1) and low cost, but its practical application is restricted by its low electrical conductivity and large volume changes during lithiation/delithiation. Herein, rationally designed Fe3O4/MXene hybrid heterostructures are constructed using an interfacial self-assembly approach that allows spontaneous deposition of Fe3O4 nanodots over Ti3C2Tx MXene nanosheets. The van der Waals-facilitated self-assembly process results in an ideal interfacial arrangement where Fe3O4 and MXene are in a complementary configuration. Among the different mass ratio arrangements, the self-assembled composite with 70 wt % Fe3O4 (Fe3O4/MXene-7) exhibits a much enhanced capacity of 782.7 mAh g–1 at 0.1 A g–1 after 100 cycles, which retains 667.9 mAh g–1 at 1 A g–1 after 600 cycles without any capacity decay. The devised anode could further maintain a reversible capacity of 279.1 mAh g–1 when the current density reaches 5 A g–1. Moreover, the charge storage capability of Fe3O4/MXene-7 is concluded to follow a dual-mode charge storage (battery capacitive) mechanism, which anticipates the constructed heterostructures promising future for next-generation LIBs.