Zhang Wenjie, Guo Zeyu, Liang Qinghua, Lv Ruitao, Shen Wanci, Kang Feiyu, Weng Yuqing, Huang Zheng-Hong
State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University Beijing 100084 P. R. China
Key Laboratory of Advanced Materials (MOE), School of Materials Science and Engineering, Tsinghua University Beijing 100084 P. R. China.
RSC Adv. 2018 May 8;8(30):16657-16662. doi: 10.1039/c8ra01908h. eCollection 2018 May 3.
Electrospun carbon fiber films have high contact resistance at the fiber junctions, which causes poor cycling stability and limits their further improvement in energy storage performances. To eliminate the contact resistance of the film, we provide a new strategy to fuse the fiber junctions by introducing MoO in the fibers, which replaces the C-C interface by a more active C-MoO-C interface at the fiber junction to promote mass transfer. MoO reacts with C matrix to generate MoC and form self-fused junctions during the carbonization process. Due to much lower charge transfer and sodium diffusion resistance, the C-MoC fiber film with self-fused junctions shows much better cyclability with capacity retention of 90% after 2000 cycles at a constant current density of 1 A g. Moreover, the MoC particles provide many electrochemically active sites, leading to additional improvement in sodium storage. The C-MoC fiber film has a capacity of 134 mA h g at 1 A g and a high capacity of 99 mA h g even at 5 A g.
电纺碳纤维薄膜在纤维连接处具有较高的接触电阻，这导致其循环稳定性较差，并限制了它们在储能性能方面的进一步提升。为了消除薄膜的接触电阻，我们提出了一种新策略，即在纤维中引入MoO来融合纤维连接处，在纤维连接处用更活跃的C-MoO-C界面取代C-C界面，以促进传质。MoO在碳化过程中与C基体反应生成MoC并形成自融合连接。由于电荷转移和钠扩散电阻低得多，具有自融合连接的C-MoC纤维薄膜表现出更好的循环性能，在1 A g的恒流密度下经过2000次循环后容量保持率为90%。此外，MoC颗粒提供了许多电化学活性位点，导致钠存储性能进一步提高。C-MoC纤维薄膜在1 A g时的容量为134 mA h g，即使在5 A g时也具有99 mA h g的高容量。
