期刊
ACS APPLIED MATERIALS & INTERFACES
卷 13, 期 16, 页码 18876-18886出版社
AMER CHEMICAL SOC
DOI: 10.1021/acsami.1c02962
关键词
oxygen vacancy; 2D Li4Ti5O12 nanosheets; Li+ ion diffusion kinetic; DFT; bifunctional lithium storage
资金
- National Natural Science Foundation of China [21965034, U1903217, 21666037]
- Resource Sharing Platform Construction Project of Xinjiang Province [PT1909]
A two-dimensional LTO nanosheet with ultrafast charge storage oxygen vacancy was successfully fabricated to enhance Li+ ion mobility for high-rate lithium storage. Doping Al3+ into octahedron Li+/Ti4+ 16d sites not only provides stability to the Ti-O framework, but also lowers the energy barrier for Li+ ion diffusion, ultimately leading to excellent electrochemical performance.
Boosting sufficient Li+ ion mobility in Li4Ti5O12 (LTO) is crucial for high-rate performance lithium storage. Here, an ultrafast charge storage oxygen vacancy two-dimensional (2D) LTO nanosheet was successfully fabricated through a one-pot hydrothermal method. The selectively doped Al3+ into octahedron Li+/Ti4+ 16d sites not only provide bulk oxygen vacancy and appropriate distorted TiO6 octahedra to facilitate Li+ ions diffusion, but also serve as a pillar to stabilize the Ti-O framework. The oxygen vacancy lowers Li+ ion diffusion energy barrier. Moreover, the 2D structure provides open diffusion channels for fast Li+ ion transport. As a result, the sample shows excellent electrochemical performance for bifunctional lithium storage. As a lithium-ion battery anode, the capacity retention reaches 112.8 mA h g(-1) after 5000 cycles at 40 C with a fading rate of 0.288% per 100 cycles. Meanwhile, as a lithium-ion capacitor anode, it exhibits an excellent rate capacity of 120 mA h g(-1) after 5000 cycles at 500 C with nearly 100% Coulombic efficiency. The produced LTO shows much higher rate capacity and longer lifetime than the reported LTO. Density functional theory calculations also demonstrate that oxygen vacancy can facilitate Li+ ion diffusion kinetics. The relationship between oxygen vacancy content and Li+ ions diffusion energy barrier in LTO is quantified. This work pioneers a defect engineering strategy for synthesized high-performance electrode materials.
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