A three-dimensional LiVPO^sub 4^F@C/MWCNTs/rGO composite with enhanced performance for high rate Li-ion batteries

Lithium vanadium fluorophosphate (LiVPO4F) composite with three-dimensional conductive networks architecture is synthesized with synergistic modification of pyrolytic carbon (C), multi-walled carbon nanotubes (MWCNTs) and graphene sheets (rGO). The differences between LiVPO4F@C, LiVPO4F@C/MWCNTs, Li...

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Bibliographic Details
Published in:Electrochimica acta 2018-12, Vol.292, p.502
Main Authors: Hu, Guorong, Gan, Zhanggen, Cao, Yanbing, Du, Ke, Du, Yao, Peng, Zhongdong
Format: Article
Language:English
Subjects:
Batteries
Charge transfer
Diffusion coefficient
Discharge
Graphene
High voltages
Lithium
Lithium-ion batteries
Multi wall carbon nanotubes
Nanotubes
Performance enhancement
Rechargeable batteries
Scanning electron microscopy
Three dimensional composites
Transmission electron microscopy
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Summary:Lithium vanadium fluorophosphate (LiVPO4F) composite with three-dimensional conductive networks architecture is synthesized with synergistic modification of pyrolytic carbon (C), multi-walled carbon nanotubes (MWCNTs) and graphene sheets (rGO). The differences between LiVPO4F@C, LiVPO4F@C/MWCNTs, LiVPO4F@C/rGO and LiVPO4F@C/MWCNTs/rGO composites are compared through a variety of characterization means. By means of SEM and TEM analysis, it can be seen that pyrolyzed C, MWCNTs and rGO are interwoven, which forms a three-dimensional conductive network structure wrapping the LiVPO4F particles. The difference of discharge specific capacity between LiVPO4F@C and LiVPO4F@C/MWCNTs/rGO composites is becoming larger and larger with the increase of charge-discharge rate. Additionally, CV and EIS results indicate that the LiVPO4F@C/MWCNTs/rGO has the smallest polarization value and charge transfer impedance (Rct) as well as the highest diffusion coefficient of lithium ion (DLi+) in all samples. Consequently, LiVPO4F@C/MWCNTs/rGO composite exhibits a high rate capability (97.9 mAh/g cycles at 10 C) and cycling stability (93.74% capacity retention over 800 cycles at 10 C)，showing potential application for high power LIB with high voltage.
ISSN:0013-4686
1873-3859
DOI:10.1016/j.electacta.2018.09.142