Abstract Lithium-sulfur batteries (Li-S) are identified as one of the most promising rechargeable energy systems due to their high theoretical capacity, high gravimetric energy density, low cost and low environmental impact. However, the insulating nature of sulfur and the migration of soluble polysulfides during discharge limit their practical application. In an attempt to mitigate these drawbacks here we report the preparation of a novel composite formed by hydrothermally reduced graphene oxide (HrGO) and submicrometer-sized sulfur particles. The role of HrGO is not restricted to enhance the electronic conductivity of the composite, but also sulfur wrapping in order to prevent polysulfides migration. Besides, the addition of polyvinylpyrrolidone (PVP) during the synthesis of the sulfur particles allows a greater control of their size and improves its homogeneous distribution within the composite. The material is tested as cathode for Li-S batteries showing reversible capacities over 900 mAh g−1 at a rate of 0.2 C and more than 650 mAh g−1 after 100 charge-discharge cycles. Moreover, this simplistic and environmentally friendly approach allow obtaining composites with sulfur loadings as high as 92 wt%, and large areal capacities up to 1.5 mAh cm−2.

中文翻译：

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用于有效包裹硫颗粒的水热还原氧化石墨烯显示出作为锂硫电池电极的长期稳定性

摘要 锂硫电池（Li-S）因其理论容量高、重量能量密度高、成本低和对环境影响小而被认为是最有前途的可充电能源系统之一。然而，硫的绝缘性质和放电过程中可溶性多硫化物的迁移限制了它们的实际应用。为了减轻这些缺点，我们报告了一种由水热还原氧化石墨烯 (HrGO) 和亚微米级硫颗粒形成的新型复合材料的制备。HrGO 的作用不仅限于提高复合材料的电子电导率，还包括硫包裹以防止多硫化物迁移。除了，在硫颗粒的合成过程中添加聚乙烯吡咯烷酮 (PVP) 可以更好地控制它们的尺寸并改善其在复合材料中的均匀分布。该材料作为锂硫电池的阴极进行测试，显示可逆容量超过 900 mAh g-1，在 0.2 C 的速率下，在 100 次充放电循环后超过 650 mAh g-1。此外，这种简单且环保的方法允许获得硫负载量高达 92 wt% 和高达 1.5 mAh cm-2 的大面积容量的复合材料。