Atomic scale, amorphous FeOx/carbon nanofiber anodes for Li-ion and Na-ion batteries

Zheng Long Xu, Shanshan Yao, Jiang Cui, Limin Zhou, Jang Kyo Kim

Research output: Contribution to journalArticlepeer-review

78 Scopus citations


Uniformly dispersed, atomic scale, amorphous FeOx particles are in situ embedded in carbon nanofibers (CNFs) via electrospinning followed by annealing and carbonization. The optimal annealing temperature, duration of carbonization and physical constraint from CNFs are identified as the critical parameters that enable the formation of atomic scale, amorphous FeOx particles. The FeOx/CNF composite electrodes present exceptional cyclic stability for both lithium ion batteries (LIBs) and sodium ion batteries (SIBs) after 500 cycles at 0.5 A g−1: an excellent capacity of 717 mAh g−1 with capacity retention (CR) of ~96% for LIBs, and 277 mAh g−1 with CR of almost 100% for SIBs. The ultrafine size and amorphous state of FeOx particles are upheld even after 500 cycles, offering solid evidence for excellent reversibility of the electrodes. Reversible conversion between the amorphous FeOx phase and Fe nanocrystals during charge/discharge reactions are identified as the principal energy storage mechanisms for both batteries. Interestingly, the Fe particles formed after discharge in SIBs are generally larger in size but much smaller in molar amount than in LIBs, which may partly account for the lower specific capacity of SIBs given the same electrode material and the same testing condition. These findings not only enrich our understanding of energy storage behaviors of iron oxide anodes, but also offer a potential strategy to improve the cyclic stability of electrodes made from other transition metal oxides that suffer from large volume changes and poor electrical conductivities.

Original languageBritish English
Pages (from-to)10-19
Number of pages10
JournalEnergy Storage Materials
StatePublished - 1 Jul 2017


  • Carbon nanofiber
  • Electrospinning
  • FeO
  • Lithium ion battery
  • Sodium ion battery


Dive into the research topics of 'Atomic scale, amorphous FeOx/carbon nanofiber anodes for Li-ion and Na-ion batteries'. Together they form a unique fingerprint.

Cite this