Abstract The rechargeable lithium-sulfur (Li–S) batteries have been regarded as the most promising alternatives for Li-ion batteries. However, the poor conductivity, the large volume expansion of sulfur, and the “shuttle effect” of polysulfides lead to the rapid capacity decay of sulfur cathodes, which impedes the practical application of Li–S batteries. Herein, a novel three-dimensional (3D) hierarchical structured high-efficiency sulfur host (Co-CNTs@TiO2), which was assembled by hollow TiO2 spheres and vertically rooted carbon nanotubes (CNTs) network framework, was developed by simple chemical vapor deposition (CVD) method. The 3D CNTs network promoted long-range conductivity and efficiently exposed the Co active sites. Remarkably, the Co particles acted as adsorptive and catalytic sites, which were effective for chemical fixation and conversion of polysulfides. Meanwhile, the hollow and porous structures of Co-CNTs@TiO2 microspheres were conducive to the buffering of volume change during the cycling process, and could physically encapsulate polysulfides. Consequently, the S/Co-CNTs@TiO2 cathode can deliver a high initial specific capacity of 1134.9 mAh g−1 at 0.2 C, remarkable long-term cycling stability over 500 cycles with a low capacity fading rate of 0.072% per cycle at 1.0 C, as well as excellent performance under high sulfur loading up to 5.9 mg cm−2.

中文翻译：

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在载钴空心二氧化钛球体上垂直生根的碳纳米管作为导电多功能硫主体，具有优异的锂硫性能

摘要 可充电锂硫（Li-S）电池被认为是锂离子电池最有前途的替代品。然而，硫的导电性差、体积膨胀大以及多硫化物的“穿梭效应”导致硫正极容量衰减迅速，阻碍了锂硫电池的实际应用。在此，通过简单的化学气相沉积开发了一种新型的三维（3D）分层结构高效硫主体（Co-CNTs@TiO2），由空心TiO2球体和垂直根状碳纳米管（CNTs）网络框架组装而成。 (CVD) 方法。3D CNTs 网络促进了长程导电性并有效地暴露了 Co 活性位点。值得注意的是，Co 颗粒充当吸附和催化位点，对多硫化物的化学固定和转化有效。同时，Co-CNTs@TiO2微球的中空多孔结构有利于缓冲循环过程中的体积变化，并可以物理包封多硫化物。因此，S/Co-CNTs@TiO2 正极在 0.2 C 时可提供 1134.9 mAh g-1 的高初始比容量，在 500 次循环中具有显着的长期循环稳定性，在 1.0 时每循环具有 0.072% 的低容量衰减率C，以及在高达 5.9 mg cm−2 的高硫负载下的优异性能。