Graphene-wrapped sulfur nanospheres with ultra-high sulfur loading for high energy density lithium–sulfur batteries
Graphene-wrapped sulfur nanospheres with ultra-high sulfur loading for high energy density lithium–sulfur batteries
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DOI：
10.1016/j.apsusc.2014.10.176
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发表时间：
2015
影响因子：
6.7
通讯作者：
Ya Liu;Jinxin Guo;Jun Zhang;Qingmei Su;G. Du
中科院分区：
文献类型：
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作者：
Ya Liu;Jinxin Guo;Jun Zhang;Qingmei Su;G. Du
具有高理论能量密度的锂硫（Li-S）电池是电动汽车和间歇性可再生能源最有前途的储能系统之一。然而，由于活性材料的导电性较差，导电添加剂占据了电极相当大的重量。在这里，我们报告了一种硫含量高达 91 wt% 的石墨烯包裹的硫纳米球复合材料（S-nanosphere@G），作为锂硫电池的高能量密度正极材料。直径为 400–500 nm 的硫纳米球是在聚乙烯吡咯烷酮 (PVP) 的存在下通过基于溶液的方法合成的。然后通过氧化石墨烯和PVP之间的静电相互作用，将硫纳米球均匀地包裹在导电石墨烯片上，然后用肼还原氧化石墨烯。石墨烯包裹的硫纳米结构的设计提供了具有空隙空间的柔性导电石墨烯涂层，以适应硫的体积膨胀并最大限度地减少多硫化物的溶解。因此，含 91 wt% 硫的 S-nanosphere@G 纳米复合材料显示出 970 mA h g−1 的可逆初始容量，在 0.2 C 倍率下经过 100 次循环后，平均库仑效率 > 96%。考虑到电极的总质量，S-nanosphere@G 复合材料是一种有前途的高能量密度锂硫电池正极材料。
Lithium–sulfur (Li–S) battery with high theoretical energy density is one of the most promising energy storage systems for electric vehicles and intermittent renewable energy. However, due to the poor conductivity of the active material, considerable weight of the electrode is occupied by the conductive additives. Here we report a graphene-wrapped sulfur nanospheres composite (S-nanosphere@G) with sulfur content up to 91 wt% as the high energy density cathode material for Li–S battery. The sulfur nanospheres with diameter of 400–500 nm are synthesized through a solution-based approach with the existence of polyvinylpyrrolidone (PVP). Then the sulfur nanospheres are uniformly wrapped by conductive graphene sheets through the electrostatic interaction between graphene oxide and PVP, followed by reducing of graphene oxide with hydrazine. The design of graphene wrapped sulfur nanoarchitecture provides flexible conductive graphene coating with void space to accommodate the volume expansion of sulfur and to minimize polysulfide dissolution. As a result, the S-nanosphere@G nanocomposite with 91 wt% sulfur shows a reversible initial capacity of 970 mA h g−1and an average columbic efficiency > 96% over 100 cycles at a rate of 0.2 C. Taking the total mass of electrode into account, the S-nanosphere@G composite is a promising cathode material for high energy density Li–S batteries.