Spring-roll-like Ti₃C₂MXene/carbon-coated Fe₃O₄composite as a long-life Li-ion storage material

Fe3O4 is a promising anode material for Li-ion batteries because of its high theoretical capacity, low cost, and natural abundance. Nevertheless, the intrinsically sluggish reaction kinetics and huge volume variation severely limit its reversible capacity and cycle life. Herein, we synthesized a few-layered Ti3C2 (f-Ti3C2)-wrapped carbon-coated Fe3O4 (C-Fe3O4) composite (C-Fe3O4/Ti3C2) with a three-dimensional (3D) spring-roll-like structure to circumvent the intrinsic limits and prolong the cycling life of Fe3O4. As an anode for a Li-ion battery, the 3D C-Fe3O4/Ti3C2 composite not only inherits the high electrochemical activity of Fe3O4, but also exhibits excellent electrical and ionic conductivity. The f-Ti3C2 can effectively increase the electrical and ionic conductivity of C-Fe3O4, and the f-Ti3C2 partially accommodates the huge volume change in Fe3O4 caused by the Li+ insertion/extraction processes. Furthermore, the self-restacking of f-Ti3C2 is significantly prevented by C-Fe3O4, which contributes a larger surface area and more accessible active sites. The C-Fe3O4/Ti3C2 anodes displayed remarkable electrochemical properties and ultralong cycling life at high current density. A reversible capacity of 997 mA h g-1 can be delivered at 1 A g-1 even after 2000 cycles, and as high as 543 mA h g-1 can be retained at 5 A g-1. These results indicate that the 3D C-Fe3O4/Ti3C2 composite is a promising candidate anode for a high-energy density battery with a long lifespan.