Oxygen vacancies engineering via Sc3+ doping to boost Li-ion transport and cycling stability in TiNb2O7 anodes

With the rapid growth of portable electronics and electric vehicles, lithium-ion batteries (LIBs) have become a core technology for modern energy storage systems. However, the increasing demand for lithium resources, coupled with rising extraction costs, poses significant challenges to the sustainable development of LIBs. TiNb 2 O 7 (TNO) has attracted attention due to its intercalation-type mechanism, moderate operating voltage and a theoretical capacity of ∼387 mAh g −1 . This study investigates the effects of Sc 3+ doping on enhancing the structural and electrochemical properties of TNO. A combination of analytical techniques, including DFT calculations and pseudocapacitive analysis, is employed to elucidate lithium-ion storage behavior. The sample with 3 mol.% Sc 3+ doping achieved the highest reversible capacity of 363.9 mAh g −1 at 0.1C, with a capacity retention of 86.6% after 500 cycles at 5C. CV, GITT, and EIS tests all showed improved lithium-ion diffusion kinetics and charge transfer properties at this doping level. This study demonstrates that targeted compositional modifications can significantly optimize the structural features and electrochemical behavior of TiNb 2 O 7 , providing a promising pathway for developing high-rate, long-cycle lithium-ion battery anode materials.