ACS Appl Mater Interfaces. 2019 Feb 13;11(6):5911-5918. doi: 10.1021/acsami.8b17549. Epub 2019 Jan 31.
The conversion reaction-based lithium-sulfur battery features an attractive energy density of 2600 W h/kg. Nevertheless, the unsatisfied performance in terms of poor discharge capacity and cycling stability still hinders its practical applications. Recently, porous carbon materials have been widely reported as promising sulfur reservoirs to promote the sluggish reaction kinetics of sulfur conversion, tolerate volume expansion of sulfur, and suppress polysulfide shuttling. However, porous carbon with a simply designed nanostructure is hard to satisfy all of these aspects simultaneously. Herein, we have applied a dual-template strategy that assembles carbon pores into carbon sheets to prepare three-dimensional (3D) nitrogen-doped porous carbon nanosheets (N-PCSs) as the multifunctional sulfur host for the Li-S battery. By arranging carbon pores within an interconnected 3D architecture, the porous carbon sheets enable rapid electron/ion transfer. Moreover, the micro/mesopores and nitrogen dopant in N-PCS provide both physical and chemical restrictions to polysulfide species. With these advances, the N-PCS/S cathode delivers a large initial discharge capacity of 1360 mA h/g at 0.1 C. When performed at 0.5 C for 1000 cycles, the cathode can still remain ∼50% of its capacity with a low decay rate of 0.05% per cycle, showing the important role of the 3D carbon material in the Li-S battery.
基于转换反应的锂硫电池具有 2600 W h/kg 的诱人能量密度。然而，其较差的放电容量和循环稳定性的性能仍阻碍了其实际应用。最近，多孔碳材料作为有前途的硫储层得到了广泛的报道，以促进硫转换的缓慢反应动力学、容忍硫的体积膨胀和抑制多硫化物穿梭。然而，具有简单设计的纳米结构的多孔碳很难同时满足所有这些方面。在此，我们采用了一种双重模板策略，将碳孔组装成碳片，制备了三维（3D）氮掺杂多孔碳纳米片（N-PCSs）作为 Li-S 电池的多功能硫宿主。通过在相互连接的 3D 结构中排列碳孔，多孔碳片实现了快速的电子/离子转移。此外，N-PCS 中的微孔/介孔和氮掺杂剂对多硫化物物种提供了物理和化学限制。通过这些改进，N-PCS/S 正极在 0.1 C 时提供了 1360 mA h/g 的初始大放电容量。当以 0.5 C 进行 1000 次循环时，正极仍能保持其容量的约 50%，其衰减率为 0.05%/循环，这表明 3D 碳材料在 Li-S 电池中的重要作用。
