Amorphous Carbon Coated High Grain Boundary Density Dual Phase Li4Ti5O12-TiO2: A Nanocomposite Anode Material for Li-Ion Batteries

This work introduces an effective, inexpensive, and large‐scale production approach to the synthesis of a carbon coated, high grain boundary density, dual phase Li4Ti5O12‐TiO2 nanocomposite anode material for use in rechargeable lithium‐ion batteries. The microstructure and morphology of the Li4Ti5O12‐TiO2‐C product were characterized systematically. The Li4Ti5O12‐TiO2‐C nanocomposite electrode yielded good electrochemical performance in terms of high capacity (166 mAh g−1 at a current density of 0.5 C), good cycling stability, and excellent rate capability (110 mAh g−1 at a current density of 10 C up to 100 cycles). The likely contributing factors to the excellent electrochemical performance of the Li4Ti5O12‐TiO2‐C nanocomposite could be related to the improved morphology, including the presence of high grain boundary density among the nanoparticles, carbon layering on each nanocrystal, and grain boundary interface areas embedded in a carbon matrix, where electronic transport properties were tuned by interfacial design and by varying the spacing of interfaces down to the nanoscale regime, in which the grain boundary interface embedded carbon matrix can store electrolyte and allows more channels for the Li+ ion insertion/extraction reaction. This research suggests that carbon‐coated dual phase Li4Ti5O12‐TiO2 nanocomposites could be suitable for use as a high rate performance anode material for lithium‐ion batteries. A nanocomposite of high grain boundary density Li4Ti5O12‐TiO2‐C is synthesized by a simple molten salt process and its electrochemical properties are investigated in this study. For comparison, Li4Ti5O12 and Li4Ti5O12‐TiO2 are also investigated. Electrochemical measurements indicate that the carbon incorporated grain boundary plays an important role in both the capacity retention and the rate capability of the electrode.