In Situ Electrochemical Impedance Measurements of α-Fe2O3 Nanofibers: Unravelling the Li-Ion Conduction Mechanism in Li-Ion Batteries

Batteries

Dolly Yadav¹  Hang Yang²  Chae-Ryong Cho²  Injun Jeon²  Jinhyun Hwang²  Jang-Won Seo²  Dingcheng Yang²  Minseung Kang³  Se-Young Jeong³ 

[1] Crystal Bank Research Institute, Pusan National University, Busan 46241, Korea;Department of Nano Fusion Technology, Pusan National University, Busan 46241, Korea;Department of Nanoenergy Engineering, Pusan National University, Busan 46241, Korea;

关键词: Li-ion battery;    anode;    α-Fe₂O₃;    charge transfer;    in situ EIS;   

DOI  :  10.3390/batteries8050044

来源: DOAJ

【 摘 要 】

Unravelling the lithium-ion transport mechanism in α-Fe₂O₃ nanofibers through in situ electrochemical impedance studies is crucial for realizing their application in high-performance anodes in lithium-ion batteries. Herein, we report the effect of heat treatment conditions on the structure, composition, morphology, and electrochemical properties of α-Fe₂O₃ nanofibers as an anode for lithium-ion batteries. The α-Fe₂O₃ nanofibers were synthesized via electrospinning and post-annealing with differences in their annealing temperature of 300, 500, and 700 °C to produce FO300, FO500, and FO700 nanofibers, respectively. Improved electrochemical performance with a high reversible specific capacity of 599.6 mAh g⁻¹ at a current density of 1 A g⁻¹ was achieved after 50 cycles for FO700. The in situ electrochemical impedance spectroscopy studies conducted during the charge/discharge process revealed that the charge transfer and Li-ion diffusion behaviors were related to the crystallinity and structure of the as-synthesized α-Fe₂O₃ nanofibers. The surfaces of the α-Fe₂O₃ nanofibers were converted into Fe metal during the charging/discharging process, which resulted in improved electrical conductivity. The electron lifetime, as determined by the time constant of charge transfer, revealed that, when a conversion reaction occurred, the electrons tended to travel through the iron metal in the α-Fe₂O₃ nanofibers. The role of iron as a pseudo-resistor with negligible capacitance was revealed by charge transfer resistance analysis.

【 授权许可】

Unknown