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Ultrathin MXene Nanosheets Decorated with TiO2 Quantum Dots as an Efficient Sulfur Host toward Fast and Stable Li–S Batteries
Small ( IF 13.0 ) Pub Date : 2018-09-02 , DOI: 10.1002/smll.201802443
Xiao-Tian Gao 1, 2 , Ying Xie 3 , Xiao-Dong Zhu 4 , Ke-Ning Sun 4 , Xu-Ming Xie 5 , Yi-Tao Liu 1 , Jian-Yong Yu 1 , Bin Ding 1
Small ( IF 13.0 ) Pub Date : 2018-09-02 , DOI: 10.1002/smll.201802443
Xiao-Tian Gao 1, 2 , Ying Xie 3 , Xiao-Dong Zhu 4 , Ke-Ning Sun 4 , Xu-Ming Xie 5 , Yi-Tao Liu 1 , Jian-Yong Yu 1 , Bin Ding 1
Affiliation
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Being conductive and flexible, 2D transition metal nitrides and carbides (MXenes) can serve in Li–S batteries as sulfur hosts to increase the conductivity and alleviate the volume expansion. However, the surface functional groups, such as OH and F, weaken the ability of bare MXenes in the chemisorption of polysulfides. Besides, they create numerous hydrogen bonds which make MXenes liable to restack, resulting in substantial loss of active area and, thus, inaccessibility of ions and electrolyte. Herein, a facile, one‐step strategy is developed for the growth of TiO2 quantum dots (QDs) on ultrathin MXene (Ti3C2Tx) nanosheets by cetyltrimethylammonium bromide‐assisted solvothermal synthesis. These QDs act as spacers to isolate the MXene nanosheets from restacking, and preserve their 2D geometry which guarantees larger electrode–electrolyte contact area and higher sulfur loading. The stronger adsorption energy of polysulfides with TiO2 (than with Ti3C2Tx), as proven by density functional theory calculations, is essential for better on‐site polysulfide retention. The ultrathin nature and protected conductivity ensure rapid ion and electron diffusion, and the excellent flexibility maintains high mechanical integrity. In result, the TiO2 QDs@MXene/S cathode exhibits significantly improved long‐term cyclability and rate capability, disclosing a new opportunity toward fast and stable Li–S batteries.
中文翻译:
用TiO2量子点装饰的超薄MXene纳米片,作为快速,稳定的Li-S电池的有效硫基质
2D过渡金属氮化物和碳化物(MXenes)具有导电性和柔性,可以在Li-S电池中用作硫主体,从而增加导电率并减轻体积膨胀。然而,表面的官能团,如 OH和女,削弱裸MXenes的在多硫化物的化学吸附的能力。此外,它们产生大量的氢键,使MXene易于重新堆积,从而导致活性区的大量损失,从而使离子和电解质难以接近。在此,轻便,一步法策略对于TiO 2的生长开发2个量子点(QD)上超薄MXene(TI 3 c ^ 2 Ť X)十六烷基三甲基溴化铵辅助溶剂热合成的纳米片。这些QD充当隔离物,以隔离MXene纳米片,防止其重新堆叠,并保留其2D几何形状,从而确保更大的电极-电解质接触面积和更高的硫负载量。密度泛函理论计算证明,与TiO 2相比,多硫化物具有比Ti 3 C 2 T x更高的吸附能,对于更好地保留多硫化物至关重要。超薄特性和受保护的导电性确保了离子和电子的快速扩散,并且出色的柔韧性保持了很高的机械完整性。结果,TiO 2 QDs @ MXene / S阴极具有显着改善的长期循环能力和倍率性能,为快速稳定的Li-S电池提供了新的机遇。
更新日期:2018-09-02
中文翻译:
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用TiO2量子点装饰的超薄MXene纳米片,作为快速,稳定的Li-S电池的有效硫基质
2D过渡金属氮化物和碳化物(MXenes)具有导电性和柔性,可以在Li-S电池中用作硫主体,从而增加导电率并减轻体积膨胀。然而,表面的官能团,如 OH和女,削弱裸MXenes的在多硫化物的化学吸附的能力。此外,它们产生大量的氢键,使MXene易于重新堆积,从而导致活性区的大量损失,从而使离子和电解质难以接近。在此,轻便,一步法策略对于TiO 2的生长开发2个量子点(QD)上超薄MXene(TI 3 c ^ 2 Ť X)十六烷基三甲基溴化铵辅助溶剂热合成的纳米片。这些QD充当隔离物,以隔离MXene纳米片,防止其重新堆叠,并保留其2D几何形状,从而确保更大的电极-电解质接触面积和更高的硫负载量。密度泛函理论计算证明,与TiO 2相比,多硫化物具有比Ti 3 C 2 T x更高的吸附能,对于更好地保留多硫化物至关重要。超薄特性和受保护的导电性确保了离子和电子的快速扩散,并且出色的柔韧性保持了很高的机械完整性。结果,TiO 2 QDs @ MXene / S阴极具有显着改善的长期循环能力和倍率性能,为快速稳定的Li-S电池提供了新的机遇。