Hierarchical structured materials constructed with conductive carbon materials have been extensively studied as S host materials for Li-S batteries. However, their outwardly developed hierarchical structures, which do not contain structures or materials to inhibit polysulfide dissolution, lead to the dissipation of dissolved polysulfides and poor dispersion properties during the slurry-making process, which results in non-uniformity in the cathodes. Herein, an assembly of polar materials (hollow structured SiO2 microspheres) and electrically conductive hierarchical N-doped bamboo-like carbon nanotubes (b-NCNTs) is designed as an efficient S host material for minimizing the dissolution of polysulfides during Li-S battery operations. Highly aligned and packed b-NCNTs are grown in hollow structured SiO2 microspheres. The SiO2 layer coated on the surface of the hollow CoFe2O4 microspheres plays a key role in the synthesis of easily dispersible hierarchical b-NCNTs microspheres (b-NCNTs@SiO2). The S-loaded b-NCNTs@SiO2 electrodes show better cycling stability than S-loaded b-NCNTs electrodes. The polysulfide trapping of the polar SiO2 layer and the well-developed b-NCNTs minimize the dissolution of polysulfides during cycling. In addition, the introduction of electronegative N atoms into the b-NCNTs lattice enhances their polysulfide trapping ability. The S-loaded b-NCNTs@SiO2 electrodes exhibit stable discharge capacities of >771 mA h g-1 over 195 cycles at a current density of 0.5 C and a high reversible capacity of 486 mA h g-1 even at a high current density of 5.0 C.

中文翻译：

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极性中空微球和分层N掺杂碳纳米管的结构组合，用于高性能Li-S电池。

已经广泛研究了由导电碳材料构成的分层结构材料作为Li-S电池的S主体材料。然而，它们向外发展的不包含抑制多硫化物溶解的结构或材料的分层结构，导致在浆液制备过程中溶解的多硫化物的消散和较差的分散性，这导致阴极不均匀。本文中，极性材料（空心结构的SiO2微球）和导电的N型掺杂竹类碳纳米管（b-NCNT）的组件被设计为一种有效的S主体材料，可最大程度地减少Li-S电池运行过程中多硫化物的溶解。高度排列和堆积的b-NCNT在中空结构的SiO2微球中生长。空心CoFe2O4微球表面的SiO2涂层在易分散的分级b-NCNTs微球（b-NCNTs @ SiO2）的合成中起着关键作用。S负载的b-NCNTs @ SiO2电极显示出比S负载的b-NCNTs电极更好的循环稳定性。极性SiO2层和发达的b-NCNT的多硫化物捕集可最大程度地减少循环过程中多硫化物的溶解。此外，将负电性N原子引入b-NCNT晶格可增强其多硫化物的捕获能力。负载S的b-NCNTs @ SiO2电极在195个循环中在0.5 C的电流密度下显示稳定的放电容量> 771 mA h g-1，即使在高电流密度下也显示出486 mA h g-1的高可逆容量5.0C。