Liu, Jinlong Wang, Zhenyu Lu, Zhouguang Zhang, Lei Xie, Fangxi Vasileff, Anthony Qiao, Shi-Zhang Efficient Surface Modulation of Single-Crystalline Na<sub>2</sub>Ti<sub>3</sub>O<sub>7</sub> Nanotube Arrays with Ti<sup>3+</sup> Self-Doping toward Superior Sodium Storage Although Na<sub>2</sub>Ti<sub>3</sub>O<sub>7</sub>-based anodes have been widely investigated in sodium-ion batteries (SIBs), their Na<sup>+</sup> storage properties especially high-rate capability and long-term cycling durability are far from practical application, because of their intrinsic low conductivity and unsatisfied Na<sup>+</sup> diffusion resistance. Here, we report the surface engineering of Na<sub>2</sub>Ti<sub>3</sub>O<sub>7</sub> nanotube arrays grown in situ on Ti foil through a hydrothermal method and subsequent NH<sub>3</sub>-assisted calcination. Benefiting from the effective surface modification, the as-derived free-standing electrode possesses highly crystalline surface with favorable Na<sup>+</sup> diffusion kinetics and self-incorporation of abundant Ti<sup>3+</sup> for improved electronic conductivity. These features enable the electrode to achieve remarkable reversible capacity (237.9 mAh g<sup>–1</sup>), ultra-high rate capability (88.5 mAh g<sup>–1</sup> at 100 C = 17.7 A g<sup>–1</sup>), and excellent cycling stability (92.32% capacity retention at 50 C after 5000 cycles), which are superior to the counterpart without surface modification, as well as almost all Na<sub>2</sub>Ti<sub>3</sub>O<sub>7</sub>-based anode materials reported so far for SIBs. The outstanding electrochemical performance demonstrates the feasibility of proposed surface modulation in designing more efficient electrode materials for energy storage. SIB;Efficient Surface Modulation;Na 2 Ti 3 O 7;Na 2 Ti 3 O 7 nanotube arrays;surface modification;electrode;NH;Single-Crystalline Na 2 Ti 3 O 7 Nanotube Arrays;Superior Sodium Storage 2019-08-28
    https://acs.figshare.com/articles/journal_contribution/Efficient_Surface_Modulation_of_Single-Crystalline_Na_sub_2_sub_Ti_sub_3_sub_O_sub_7_sub_Nanotube_Arrays_with_Ti_sup_3_sup_Self-Doping_toward_Superior_Sodium_Storage/9744989
10.1021/acsmaterialslett.9b00213.s001