Enhanced Electrochemical Performance of Ultracentrifugation-Derived nc-Li3VO4/MWCNT Composites for Hybrid Supercapacitors

Nanocrystalline Li3VO4 dispersed within multiwalled carbon nanotubes (MWCNTs) was prepared using an ultracentrifugation (uc) process and electrochemically characterized in Li-containing electrolyte. When charged and discharged down to 0.1 V vs Li, the material reached 330 mAh g–1 (per composite) at...

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Veröffentlicht in:ACS nano Jg. 10; H. 5; S. 5398 - 5404
Hauptverfasser: Iwama, Etsuro, Kawabata, Nozomi, Nishio, Nagare, Kisu, Kazuaki, Miyamoto, Junichi, Naoi, Wako, Rozier, Patrick, Simon, Patrice, Naoi, Katsuhiko
Format: Journal Article
Sprache:Englisch
Veröffentlicht: United States American Chemical Society 24.05.2016
Schlagworte:
Chemical Sciences
Engineering Sciences
Material chemistry
Materials
hyperdispersion
initial electrochemical activation
Li3VO4
ultrafast charge storage
varied energy efficiency
ultracentrifugation
ISSN:1936-0851, 1936-086X
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Zusammenfassung:Nanocrystalline Li3VO4 dispersed within multiwalled carbon nanotubes (MWCNTs) was prepared using an ultracentrifugation (uc) process and electrochemically characterized in Li-containing electrolyte. When charged and discharged down to 0.1 V vs Li, the material reached 330 mAh g–1 (per composite) at an average voltage of about 1.0 V vs Li, with more than 50% capacity retention at a high current density of 20 A g–1. This current corresponds to a nearly 500C rate (7.2 s) for a porous carbon electrode normally used in electric double-layer capacitor devices (1C = 40 mA g–1 per activated carbon). The irreversible structure transformation during the first lithiation, assimilated as an activation process, was elucidated by careful investigation of in operando X-ray diffraction and X-ray absorption fine structure measurements. The activation process switches the reaction mechanism from a slow “two-phase” to a fast “solid-solution” in a limited voltage range (2.5–0.76 V vs Li), still keeping the capacity as high as 115 mAh g–1 (per composite). The uc-Li3VO4 composite operated in this potential range after the activation process allows fast Li+ intercalation/deintercalation with a small voltage hysteresis, leading to higher energy efficiency. It offers a promising alternative to replace high-rate Li4Ti5O12 electrodes in hybrid supercapacitor applications.
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ISSN:1936-0851
1936-086X
DOI:10.1021/acsnano.6b01617