期刊
CHEMICAL ENGINEERING JOURNAL
卷 338, 期 -, 页码 211-217出版社
ELSEVIER SCIENCE SA
DOI: 10.1016/j.cej.2018.01.001
关键词
Electrochemical capacitor; Volumetric specific capcaity; In situ; Continuous phase change
资金
- National Natural Science Foundation of China [51271169]
- Program for Innovative Research Team in University of Ministry of Education of China [IRT13037]
The low active ratio of traditional (only surface-active) pseudocapacitive materials limits the fabrication of electrochemical energy storage/ conversion devices with high volumetric energy densities. This work focuses on the T-Nb2O5 phase that show bulk pseudocapacitance. The capacitor-like electrochemical kinetic of T-Nb2O5 was found to exsit in particles without nano structuring, thus providing possibility to design core@shell T-Nb2O5@C particles with larger core and thinner shell. By scaling the capacity to the volume of the particle, a T-Nb2O5@C with 85 nm core and 1.5 nm shell is able to provide a particle-level volumetric specific capacity of 928 mAh cm(-3), which is much larger than any other traditional pseudocapacitive materials that work with only their surfaces. Advanced in situ XRD and in situ TEM tools reveal that the T-Nb2O5 experiences a small and continuous phase change process without phase-separation and energy barrier for the formation of phase boundary. We propose the unique structural behavior of T-Nb2O5 is due to the existance of large amounts of intermediate phases between the original and lithiated state of T-Nb2O5.
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