Lithium-sulfur (Li–S) batteries with high theoretical specific capacity of 1675 mAh g and energy density of 2600 Wh kg are considered as a promising candidate for energy conversion and storage devices in future. However, some critical dilemmas such as low real energy density, high solubility of ether-based electrolytes and slow redox kinetics of long-chain polysulfides remain unsettled hindering their development. Here we design and propose a high-performance sulfur host material constructed by growing CoN/CoS nanoparticles enclosed in reduced graphene oxide (RGO) and CoS modified separator to enhance the electrochemical performance of Li–S batteries. The results of first principal calculations confirm that the calculated adsorption energies of LiS, LiS, LiS and LiS on the CoS (111) surface are lower than that of the CoN (111) surface, indicating that the CoS has stronger adsorbing effect with polysulfides. Furthermore, the catalytic effect in LiS symmetric batteries and the nucleation of the LiS tests display that the CoN/CoS@RGO has a fast conversion reaction kinetics and catalytic effect of polysulfides, thereby inhibiting the leakage of the polysulfides. Consequently, the S@CoN/CoS@RGO cathode with CoS layer represents a high discharge capacity of 1367.7 mAh g at 0.1C and a prolonged lifespan over 700 cycles at 1 C with an extremely low decay rate of 0.06 % per cycle and high cycling stability.

中文翻译：

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CoN//Co9S8 共嵌入还原氧化石墨烯中作为多硫化物催化转化的催化剂


锂硫（Li-S）电池具有1675 mAh g的高理论比容量和2600 Wh kg的能量密度，被认为是未来能量转换和存储设备的有前途的候选者。然而，一些关键的困境，如实际能量密度低、醚基电解质的高溶解度和长链多硫化物的氧化还原动力学缓慢等仍未解决，阻碍了它们的发展。在此，我们设计并提出了一种高性能硫主体材料，该材料通过生长封装在还原氧化石墨烯（RGO）和 CoS 改性隔膜中的 CoN/CoS 纳米颗粒来构建，以增强 Li-S 电池的电化学性能。第一主计算结果证实，计算得到的LiS、LiS、LiS和LiS在CoS（111）表面的吸附能均低于CoN（111）表面，表明CoS对多硫化物具有更强的吸附作用。此外，LiS对称电池中的催化作用和LiS的成核测试表明，CoN/CoS@RGO具有快速的转化反应动力学和多硫化物的催化作用，从而抑制了多硫化物的泄漏。因此，具有 CoS 层的 S@CoN/CoS@RGO 正极在 0.1C 下具有 1367.7 mAh g 的高放电容量，在 1 C 下具有超过 700 次循环的长寿命，并且具有每循环 0.06% 的极低衰减率和高循环性能稳定。