Porosity‐Controlled TiNb2O7 Microspheres with Partial Nitridation as A Practical Negative Electrode for High‐Power Lithium‐Ion Batteries

Titanium niobium oxide (TiNb 2 O 7 ) has been recognized as a promising anode material for lithium‐ion batteries (LIBs) in view of its potential to operate at high rates with improved safety and high theoretical capacity of 387 mAh g −1 . However, it suffers from poor Li + ion diffusivity and low electronic conductivity originated from its wide band gap energy ( E g > 2 eV). Here, porous TiNb 2 O 7 microspheres (PTNO MSs) are prepared via a facile solvothermal reaction. PTNO MSs have a particle size of ≈1.2 μm and controllable pore sizes in the range of 5–35 nm. Ammonia gas nitridation treatment is conducted on PTNO MSs to introduce conducting Ti 1− x Nb x N layer on the surface and form nitridated PTNO (NPTNO) MSs. The porous structure and conducting Ti 1− x Nb x N layer enhance the transport kinetics associated with Li + ions and electrons, which leads to significant improvement in electrochemical performance. As a result, the NPTNO electrode shows a high discharge capacity of ≈265 mAh g −1 , remarkable rate capability (≈143 mAh g −1 at 100 C) and durable long‐term cyclability (≈91% capacity retention over 1000 cycles at 5 C). These results demonstrate the great potential of TiNb 2 O 7 as a practical high‐rate anode material for LIBs.