Spring-roll-like Ti3C2 MXene/carbon-coated Fe3O4 composite as a long-life Li-ion storage material

Abstract

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.