Effect of Synthesis on Performance of MXene/Iron Oxide Anode Material for Lithium-Ion Batteries

Two-dimensional heterostructures, such as Fe<sub>2</sub>O<sub>3</sub>/MXene nanoparticles, can be attractive anode materials for lithium-ion batteries (LIBs) due to the synergy between high lithium-storage capacity of Fe<sub>2</sub>O<sub>3</sub> and stable cyclability and high conductivity provided by MXene. Here, we improved the storage performance of Ti<sub>3</sub>C<sub>2</sub>T<i><sub>x</sub></i> (MXene)/Fe<sub>2</sub>O<sub>3</sub> nanocomposite by confining Fe<sub>2</sub>O<sub>3</sub> nanoparticles into Ti<sub>3</sub>C<sub>2</sub>T<i><sub>x</sub></i> nanosheets with different mixing ratios using a facile and scalable dry ball-milling process. Composites of Ti<sub>3</sub>C<sub>2</sub>T<i><sub>x</sub></i>-25 wt % Fe<sub>2</sub>O<sub>3</sub> and Ti<sub>3</sub>C<sub>2</sub>T<i><sub>x</sub></i>-50 wt % Fe<sub>2</sub>O<sub>3</sub> synthesized by ball-milling resulted in uniform distribution of Fe<sub>2</sub>O<sub>3</sub> nanoparticles on Ti<sub>3</sub>C<sub>2</sub>T<i><sub>x</sub></i> nanosheets with minimum oxidation of MXene as compared to composites prepared by hydrothermal or wet sonication. Moreover, the composites demonstrated minimum restacking of the nanosheets and higher specific surface area. Among all studied composites, the Ti<sub>3</sub>C<sub>2</sub>T<i><sub>x</sub></i>-50 wt % Fe<sub>2</sub>O<sub>3</sub> showed the highest reversible specific capacity of ∼270 mAh g<sup>–1</sup> at 1C (∼203 mAh g<sup>–1</sup> based on the composite) and rate performance of 100 mAh g<sup>–1</sup> at 10C. This can open the door for synthesizing stable and high-performance MXene/transition metal oxide composites with significantly enhanced electrochemical performance for LIB applications.