Pillar-free TiO2/Ti3C2 composite with expanded interlayer spacing for high-capacity sodium ion batteries

The lamellar transition metal oxides, sulfides and carbides with expanded interlayer spacing have attracted wide attention due to their enlargeable interlayer diffusion channels and larger contact areas. However, the existence of pillars between the interlayer would occupy the inter layer voids, which would hinder the accommodation of more lithium ion, sodium ion and so on. Pillar-free TiO2/Ti3C2 composite with expanded interlayer spacing was prepared by sintering the pre-intercalated pristine Ti3C2 with TMAOH under N2 atmosphere. The obtained TiO2/Ti3C2 composite showed remarkable capacity (237.8 mAh g−1 at 100 mA g−1) and long-term stability (153 mAh g−1after 100 cycles at current density of 600 mA g−1) as anode material for sodium ion batteries. These remarkable electrochemical properties of pillar-free TiO2/Ti3C2 were ascribed to its effective expanded interlayer distance fixed by TiO2 nanoparticles attached on the edge plane of Ti3C2, pseudocapacitance contribution of TiO2 nanoparticles, and the synergistic effect between TiO2 and Ti3C2. This work offered a general strategy for fabricating pillar-free MXene-based composites with enlarged interlayer spacing.