Key Laboratory of Colloid & Interface Chemistry (Shandong University), School of Chemistry and Chemical Engineering, Ministry of Education , Shandong University , Jinan 250100 , P. R. China.
College of Materials Science and Engineering , Qingdao University of Science & Technology , Qingdao 266042 , P. R. China.
ACS Appl Mater Interfaces. 2018 Apr 11;10(14):11642-11651. doi: 10.1021/acsami.7b18955. Epub 2018 Mar 27.
Lithium-sulfur (Li-S) battery has been attracting increasing attention because of its high energy density and the presence of abundance of sulfur. However, its commercialization is still restricted owing to the low conductivity of sulfur, large volume expansion, and a severe polysulfide-shuttle effect. To address these problems, here, we have reported for the first time a simple template-free solvothermal method combined with a subsequent calcination method to prepare cobalt-doped vanadium nitride (VN) yolk-shell nanospheres, encapsulated in a thin layer of a nitrogen-doped carbon (Co-VN@C) composite as an ideal sulfur host. Benefiting from the unique structural advantages and the synergistic effect of conductive VN, cobalt, and nitrogen-doped carbon (NC), the obtained composite could not only facilitate the kinetics of polysulfide conversion as a functional catalyst but also physically confine and chemically absorb the polysulfides effectively. With these advantages, the batteries present a high initial discharge capacity of 1379.2 mAh g at 0.1 C (1 C is defined as 1675 mA g), good rate performance, and excellent cycling performances (∼715 mAh g at 0.5 C after 200 cycles and ∼600 mAh g at 1 C after 300 cycles, respectively), even with a high areal sulfur loading of 4.07 mg cm (∼830 mAh g at 0.2 C after 100 cycles). These results demonstrate that the rationally designed multifunctional sulfur host material Co-VN@C has great potential for application in Li-S batteries.
锂硫（Li-S）电池因其高能量密度和丰富的硫储量而受到越来越多的关注。然而，由于硫的导电性低、体积膨胀大以及严重的多硫化物穿梭效应，其商业化仍受到限制。为了解决这些问题，我们首次报道了一种简单的无模板溶剂热法与随后的煅烧法相结合，制备了钴掺杂氮化钒（VN）蛋黄壳纳米球，并封装在薄的氮掺杂碳（Co-VN@C）复合材料中，作为理想的硫主体。得益于独特的结构优势以及导电 VN、钴和氮掺杂碳（NC）的协同作用，所获得的复合材料不仅可以作为功能性催化剂促进多硫化物转化的动力学，而且还可以有效地物理限制和化学吸收多硫化物。具有这些优点，电池在 0.1 C（1 C 定义为 1675 mA g）时具有高初始放电容量 1379.2 mAh g，良好的倍率性能和优异的循环性能（在 200 次循环后约为 715 mAh g，在 300 次循环后约为 600 mAh g），即使硫的载量高达 4.07 mg cm（在 100 次循环后在 0.2 C 时约为 830 mAh g）。这些结果表明，合理设计的多功能硫主体材料 Co-VN@C 在 Li-S 电池中有很大的应用潜力。
