TiO2 embedded in ultrathin N-doping carbon nanosheets derived from shape-engineered titanium metal-organic frameworks for lithium-ion storage

Abstract

The utility of TiO2 as an anode for lithium-ion storage is hindered by low conductivity and sluggish ionic diffusion. Here, the 2D N-doped carbon-wrapped TiO2 (TiO2 @NC) composite with a thickness of 5.5 nm derived from the 2D metal-organic framework was designed. This composite consisting of TiO2 nanoparticles embedded in ultrathin N-doping carbon was used to address the rate and cyclability of Li-ion batteries. The 2D nanosheet morphology obtained from Ti8O8(OH)4(BDC-NH2)6（NH2-MIL-125 (Ti)）effectively increases the specific surface area and shortens the electron/ion transport pathway. The chemical bond of Ti-C-O between TiO2 nanocrystals and N-doping carbon further improve conductivity. Due to its unique structure, the produced TiO2 @NC composite shows excellent cyclability with a reversible capacity of 110 mAh g–1 after 2000 cycles at 0.5 A g–1. Furthermore, the 2D TiO2 @NC exhibits outstanding rate performance (71 mAh g–1 at 5 A g–1) compared to bulk TiO2 @NC. This general concept can be extended to the development of metal oxide materials based on insertion mechanisms, such as Nb2O5.