Selenium cathodes have attracted much more attention due to their much higher electronic conductivity and comparable volumetric capacity when compared with sulfur cathodes. However, selenium cathodes still suffer from low utilization of active materials, high volume changes and the shuttle effect of polyselenides, resulting in rapid capacity fading. Herein, we prepared selenium–carbon composites as cathodes for sodium–selenium batteries to improve the utilization of selenium by embedding selenium in ZIF-8 derived N-doped microporous carbon polyhedrons (denoted as Se@N-MCPs). The N-MCPs could effectively accommodate the volume change of Se@N-MCPs, and alleviate the shuttle effect of polyselenides. The Se@N-MCP cathodes deliver an excellent discharge capacity of 612 mA h g⁻¹ after 100 cycles at a current density of 0.1 A g⁻¹ and a superior rate capability of 496 mA h g⁻¹ at 5 A g⁻¹ for Na–Se batteries. In addition, they also show a superior cycling life of ∼460 mA h g⁻¹ at the current density of 1 A g⁻¹ after 500 cycles with only 0.049% capacity decline per cycle.

中文翻译：

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嵌入MOF衍生的N掺杂微孔碳多面体中的硒作为钠-硒电池的高性能阴极†

与硫阴极相比，硒阴极具有更高的电子电导率和可比的体积容量，因此吸引了越来越多的关注。然而，硒阴极仍然遭受活性材料利用率低，体积变化大和聚硒化物的穿梭效应的困扰，导致容量快速下降。在这里，我们制备了硒碳复合材料作为钠硒电池的阴极，通过将硒嵌入ZIF-8衍生的N掺杂的微孔碳多面体（表示为Se @ N-MCPs）中来提高硒的利用率。N-MCPs可以有效地适应Se @ N-MCPs的体积变化，减轻聚硒化物的穿梭效应。Se @ N-MCP阴极具有612 mA hg ^-1的出色放电容量经过100次循环后，Na-Se电池的电流密度为0.1 A g ^-1，在5 A g ^-1时具有496 mA hg ^-1的出色倍率能力。此外，它们在500次循环后在1 A g ^-1的电流密度下也显示出约460 mA hg ^-1的出色循环寿命，每循环容量仅下降0.049％。