Nitrogen Doping Enhances Pseudocapacitive Lithium Storage and Ionic Conductivity in Ti2Nb2O9 Nanosheets

Titanium-niobium oxides (Ti_xNb_yO_2x+2.5y) are promising anode materials for lithium-ion batteries due to their suitable lithium insertion potential, excellent rate performance, cycling stability, and considerable capacity based on multi-electron reactions. However, the intrinsic low electrical conductivity and rapid capacity decay during cycling limit their application. In this study, nitrogen-doped Ti₂Nb₂O₉ nanosheets were synthesized using a chemical exfoliation method and the subsequent high-temperature phase transition. Meanwhile, introducing nitrogen atoms reduced the bandgap and increased the material's electrical conductivity. Thus, the lithium storage performance of the N-TNO electrode was improved with a reversible capacity of 348.1 mAh g⁻¹.