Li Peihao, Wang Wei, Gong Sheng, Lv Fan, Huang Hanxin, Luo Mingchuan, Yang Yong, Yang Chao, Zhou Jinhui, Qian Chang, Wang Bin, Wang Qian, Guo Shaojun
ACS Appl Mater Interfaces. 2018 Nov 7;10(44):37974-37980. doi: 10.1021/acsami.8b11354. Epub 2018 Oct 26.
With its inherent zig-zag layered structure and open framework, NaTiO (NTO) is a promising anode material for potassium-ion batteries (KIBs). However, its poor electronic conductivity caused by large band gap (∼3.7 eV) usually leads to low-performance KIBs. In this work, we synthesize the fluff-like hydrogenated NaTiO (HNTO) nanowires grown on N-doped carbon sponge (CS) as a binder-free and current-collector-free flexible anode for KIBs (denoted as HNTO/CS). High-resolution X-ray photoelectron spectroscopy (XPS) and electron spin-resonance spectroscopy (ESR) confirm the existence of Ti-OHs and O vacancies in HNTO. The first-principles calculation discloses that both Ti-OHs and O vacancies are equivalent to n-type doping because they can shift the Fermi level up to the conduction band, thus leading to a higher electronic conductivity and better performance for KIBs. In addition, the N-doped CS can further reinforce the conductivity and avoid the aggregation of HNTO nanowires during cycling. As a result, the as-made HNTO/CS can deliver a capacity of 107.8 mAh g at 100 mA g after 20 cycles, and keep the capacity of 90.9% and 82.5% after 200 and 1555 cycles, respectively, much better than the samples without hydrogenation treatment or N-doped CS and reported KTi O -based materials. Our work highlights the importance of hydrogenation treatment and N-doped CS in enhancing the electrochemical property for KIBs.
由于其固有的锯齿形层状结构和开放框架，NaTiO（NTO）是一种很有前景的钾离子电池（KIBs）负极材料。然而，其由大带隙（约3.7 eV）导致的不良电子导电性通常会导致KIBs性能不佳。在这项工作中，我们合成了生长在氮掺杂碳海绵（CS）上的绒毛状氢化NaTiO（HNTO）纳米线，作为KIBs的无粘结剂和无集流体的柔性负极（表示为HNTO/CS）。高分辨率X射线光电子能谱（XPS）和电子自旋共振光谱（ESR）证实了HNTO中存在Ti-OHs和氧空位。第一性原理计算表明，Ti-OHs和氧空位都相当于n型掺杂，因为它们可以将费米能级向上移动到导带，从而导致更高的电子导电性和更好的KIBs性能。此外，氮掺杂的CS可以进一步增强导电性，并避免HNTO纳米线在循环过程中聚集。结果，制备的HNTO/CS在100 mA g下循环20次后可提供107.8 mAh g的容量，在200次和1555次循环后分别保持90.9%和82.5%的容量，远优于未经氢化处理或氮掺杂CS的样品以及报道的基于KTi O的材料。我们的工作突出了氢化处理和氮掺杂CS在增强KIBs电化学性能方面的重要性。
