Schematic illustration.

Major Contributions

1.Demonstration of Self-Generated Protective Layer via Al Substitution
Partial substitution of niobium with aluminum in TiNb₂O₇ anodes leads to the formation of a self-generated protective layer at the particle surface through the solute drag effect during high-temperature annealing. This protective layer enables the selective induction of a solid electrolyte interphase (SEI) rich in lithium oxide and lithium fluoride upon contact with the electrolyte, effectively enhancing lithium-ion conductivity and suppressing undesirable side reactions and polarization during high-rate cycling.

2.Significant Improvement in Rate Performance and Cycle Stability
The TiNb₁.₉₅Al₀.₀₅O₇ (TNAO-0.05) anode exhibits remarkable electrochemical performance, including a high specific capacity of approximately 223 mAh g⁻¹ after 100 cycles at 0.1C and a capacity retention rate of 96.4% after 300 cycles at 1C. Even at a high rate of 5C, the specific capacity remains as high as 176 mAh g⁻¹, demonstrating substantial improvement over pristine TiNb₂O₇ anodes.

3.Mechanistic Elucidation of Enhanced Lithium-Ion Transport
Comprehensive analysis using electrochemical impedance spectroscopy, distribution of relaxation time (DRT), and X-ray photoelectron spectroscopy (XPS) confirms that the self-generated protective layer on TNAO-0.05 anodes reduces interface resistance and promotes the formation of a highly conductive SEI. This layer facilitates rapid lithium-ion diffusion and maintains low polarization, thereby supporting superior rate performance and long-term cycling stability.

主要貢獻

1.鋁取代誘導自生成保護層機制
透過部分以鋁取代TiNb₂O₇中的鈮元素，於高溫退火過程中產生自生成保護層。該保護層可選擇性誘導富含氧化鋰與氟化鋰的固態電解質界面（SEI）生成，有效提升鋰離子導電性並抑制高倍率循環下的不良副反應與極化現象。

2.倍率性能與循環壽命大幅提升
TiNb₁.₉₅Al₀.₀₅O₇（TNAO-0.05）負極展現優異的電化學性能，包括在0.1C下循環100次後仍具備約223 mAh g⁻¹的高比容量，以及在1C下經過300次循環後的容量保持率高達96.4%。即使在5C高倍率下，比容量仍可維持176 mAh g⁻¹，顯著優於原始TiNb₂O₇負極。

3.增強鋰離子傳輸的機制闡釋
透過電化學阻抗、鬆弛時間分布（DRT）及X光光電子能譜（XPS）等分析，證實TNAO-0.05負極表面的自生成保護層能降低界面阻抗，促進高導電性的SEI生成。該層有效提升鋰離子擴散速率並維持低極化，進一步支持其卓越的倍率性能與長循環穩定性。