V/F Co-Doped TNO Anode Enables Superior High-Power and Long-Life Li-Ion Batteries

The pursuit of high-power and prolonged service life lithium ion batteries has driven extensive research into novel anode materials. Titanium niobium oxide (TNO) has arisen as a prospective contender due to its high reaction potential and low strain performance, which effectively avoid side reactions and suppress the formation of lithium dendrite. However, challenges such as poor conductivity and structural instability during high-rate cycling have hindered their practical application. In this study, high-performance V⁵⁺ and F^- codoping of the TiNb₂O₇ (V/F-TNO) anode is obtained by a facile solvothermal method and exhibits outstanding electrochemical properties in both liquid- and solid-state batteries. Under the synergistic effect of V⁵⁺ and F^- doping, impurity bands and additional oxygen vacancies are introduced to enhance the conductivity, while the particle size is reduced, which significantly improves its rate performance. In addition, a more stable crystal structure improves its cycle life. Thereby, the V/F-TNO anode displays a high reversible capacity of 322.8 mAh g^-1 at 0.1 C and a superior rate capability of 222.6 mAh g^-1 at 20 C. During long-term cycles, the V/F-TNO anode presents an outstanding discharge capacity of 178.5 mAh g^-1 after 1500 cycles at 10 C, equivalent to a capacity retention rate of 78.2%. LiFePO₄ (LFP)|Li_1.3Al_0.3Ti_1.7(PO₄)₃ composite polymer electrolyte (LATP_CPEs)|V/F-TNO solid-state batteries (SSBs) are assembled and display ideal capacities of 129.3 mAh g^-1 at 0.2 C and 83.5 mAh g^-1 at 5 C. Moreover, they retain an extraordinary capacity of 101.7 mAh g^-1 after 200 cycles at 0.5 C, corresponding to a high-capacity retention ratio of 86%. This study demonstrates that the V/F-TNO anode is a promising candidate for high-power liquid and solid-state batteries.