Abstract Nitrogen-doped carbon materials hold great potential for high-performance lithium storage. However, the excess defects introduced by dominated nitrogen doping methods may lead to a thickened solid electrolyte interphase (SEI), resulting in a higher Li+ diffusion resistance and inferior rate performance. Herein, composite carbon nanofibers (CNFs) with tuned microstructure and relatively high nitrogen content were fabricated by co-electrospinning the mixture of nitrogen-rich pitch, a soft carbon precursor, with polyacrylonitrile (PAN) in controlled mass ratio. The result shows that the SEI formed on the composite CNFs with less surface defects is much thinner yet tighter than that formed on the PAN-based CNFs. As such, the composite CNFs present a double capacity retention of 37.3% to that of the PAN-based CNFs at 10 A g−1. More importantly, the cycle retention of the composite CNFs anode is 88.0% after 1000 cycles at 2 A g−1, much higher than that of PAN-based CNFs (61.5%). It is believed that the improved rate and cycle performance are due to the superior structure and chemical composition of the SEI, which can be attributed to the modified microstructure by addition of nitrogen-rich pitch to a great extent.

中文翻译：

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电纺氮掺杂碳纳米纤维具有调整的微观结构和增强的锂存储性能

摘要 掺氮碳材料在高性能锂存储方面具有巨大潜力。然而，主要的氮掺杂方法引入的过量缺陷可能导致固体电解质中间相（SEI）增厚，导致更高的 Li+ 扩散阻力和较差的倍率性能。在本文中，通过共电纺富氮沥青（一种软碳前驱体）与聚丙烯腈（PAN）的混合物以受控质量比制造，具有可调节的微观结构和相对较高的氮含量的复合碳纳米纤维（CNF）。结果表明，在表面缺陷较少的复合 CNF 上形成的 SEI 比在 PAN 基 CNF 上形成的 SEI 更薄但更紧密。因此，在 10 A g-1 时，复合 CNF 的容量保持率是基于 PAN 的 CNF 的 37.3%。更重要的是，在 2 A g-1 下循环 1000 次后，复合 CNFs 阳极的循环保持率为 88.0%，远高于基于 PAN 的 CNFs (61.5%)。据信，SEI 优异的结构和化学成分导致倍率和循环性能的提高，这在很大程度上可以归因于通过添加富氮沥青来改变微观结构。