Abstract Hard-soft composite carbons have shown great potential as one of the most promising anode materials for fast rechargeable lithium-ion batteries (LIBs). However, there is still a lack of systematic research about the influence of hard and soft carbons on rate performance. In this work, the influence of carbon microstructure on Li+ and electron transfer has been investigated thoroughly by controllable introduction of coal tar pitch (CTP) to polyacrylonitrile (PAN) in the electrospun carbon nanofibers (CNFs). The result indicates that the CTP derived carbon clusters introduced into low crystallinity carbon influence the electron transport and solid-state Li+ diffusivity simultaneously. As anode materials for LIBs, the enhanced electrical conductivity and balanced Li+ diffusion significantly improve rate performance. The composite CNFs exhibit a superior capacity retention of 53.7% from 0.1 to 5 A g−1, more than double of that for PAN-based CNFs. In addition, the composite CNFs present an ultra-stable cycle performance with 99.7% capacity retention at 1 A g−1 even after 1000 cycles. This work demonstrates that the balance between Li+ diffusion and electron transport plays a key role in lithium storage performance at high current density.

中文翻译：

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碳簇装饰硬碳纳米纤维作为锂离子电池的高倍率负极材料

摘要 硬软复合碳材料作为快速充电锂离子电池（LIBs）最有前途的负极材料之一显示出巨大的潜力。然而，目前还缺乏关于硬碳和软碳对倍率性能影响的系统研究。在这项工作中，通过在电纺碳纳米纤维 (CNF) 中可控地将煤焦油沥青 (CTP) 引入聚丙烯腈 (PAN)，彻底研究了碳微结构对 Li+ 和电子转移的影响。结果表明，引入低结晶度碳中的 CTP 衍生碳簇同时影响电子传输和固态 Li+ 扩散率。作为锂离子电池的负极材料，增强的导电性和平衡的 Li+ 扩散显着提高了倍率性能。从 0.1 到 5 A g-1，复合 CNF 表现出 53.7% 的优异容量保持率，是基于 PAN 的 CNF 的两倍多。此外，复合 CNF 表现出超稳定的循环性能，即使在 1000 次循环后，1 A g-1 下的容量保持率为 99.7%。这项工作表明，Li+ 扩散和电子传输之间的平衡对高电流密度下的锂存储性能起着关键作用。